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INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (plants in which engines use combustion products F02C, F02G; internal-combustion turbines F02C)
Informative references
Attention is drawn to the following places, which may be of interest for search:
Carburettors, fuel-injection apparatus
Apparatus for performing such pretreatments or additions
Apparatus for generating fuel, e.g. gas, see the relevant classes, e.g.
C10
Aspects predominantly concerning such devices, see the relevant classes for the devices
Engines characterised by fuel-air mixture compression (characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition F02B 11/00; characterised by precombustion chambers F02B 19/00; characterised by air-storage chambers F02B 21/00; characterised by special shape or construction of combustion chambers F02B 23/00)
Definition statement
This subclass/group covers:

Engine working on the compression of a homogeneous mixture of air and fuel.

The scope of this group is very wide so that it only makes sense to classify specific documents in the subgroups for which there is no other relevant classification.

References relevant to classification in this group
This subclass/group does not cover:
Characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition
Characterised by precombustion chambers
Characterised by air-storage chambers
Characterised by special shape or construction of combustion chambers
Synonyms and Keywords

In patent documents the following abbreviations are often used:

HCCI
Homogeneous Charge Compression Ignition
PCCI
Premixed Charge Compression Ignition
with positive ignition (with non-timed positive ignition F02B 9/06)
Definition statement
This subclass/group covers:

This group covers engines with positive ignition.

Just like F02B 1/00 the scope is too wide to classify all spark ignition (SI) engines.

Because of lack of discrimination of this class, it is in use primarily to classify engines running on alcohol. (ethanol).

with fuel-air mixture admission into cylinder
References relevant to classification in this group
This subclass/group does not cover:
Direct injection petrol engines
Methods of operating
Informative references
Attention is drawn to the following places, which may be of interest for search:
Controlling engines
with separate admission of air and fuel into cylinder
Informative references
Attention is drawn to the following places, which may be of interest for search:
With compression ignition
Methods of operating
Informative references
Attention is drawn to the following places, which may be of interest for search:
Controlling combustion engines
with compression ignition (with fuel-air charge ignited by compression ignition of an additional fuel F02B 7/00)
Definition statement
This subclass/group covers:

Engines operating on "homogeneous" mixed air-fuel.

Synonyms and Keywords

In patent documents the following abbreviations are often used:

HCCI
Homogeneous Charge Compression Ignition
PCCI
Premixed Charge Compression Ignition
Engines characterised by air compression and subsequent fuel addition (characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition F02B 11/00; characterised by precombustion chambers F02B 19/00; characterised by air-storage chambers F02B 21/00; characterised by special shape or construction of combustion chambers F02B 23/00)
Definition statement
This subclass/group covers:

Engines characterised by air compression and subsequent fuel addition. E.g. diesel engines, but this group also covers engines with air compression and subsequent gasoline fuel addition as in gasoline direct injection.

References relevant to classification in this group
This subclass/group does not cover:
Characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition
Characterised by precombustion chambers
Characterised by air-storage chambers
Characterised by special shape or construction of combustion chambers
with positive ignition (with non-timed positive ignition F02B 9/06)
Definition statement
This subclass/group covers:

Air compressing engines with spark ignition.

References relevant to classification in this group
This subclass/group does not cover:
With non-timed positive ignition
Methods of operating
References relevant to classification in this group
This subclass/group does not cover:
Controlling combustion engines
Electrical control of combustion engines
with compression ignition (F02B 13/02 takes precedence; with fuel-air charge ignited by compression ignition of an additional fuel F02B 7/00)
Definition statement
This subclass/group covers:

In short: The Diesel engine. Preferably only deviations of the Diesel engine should be classified here.

Methods of operating (F02B 3/12 takes precedence)
Definition statement
This subclass/group covers:

The method of operating should be a deviation of the "normal Diesel". Normally the method of operating is already embodied in the engine itself.

References relevant to classification in this group
This subclass/group does not cover:
Control of combustion engine
with intermittent fuel introduction
Definition statement
This subclass/group covers:

More than one injection per cycle or very closely spaced multiple injections

References relevant to classification in this group
This subclass/group does not cover:
Controlling fuel injection of the high pressure type with multiple injections
Fuel injection apparatus with each cyclic delivery being separated into two or more parts
Engines characterised by positive ignition (F02B 1/02, F02B 3/02 take precedence; with non-timed positive ignition F02B 9/06; characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition F02B 11/00; characterised by precombustion chambers F02B 19/00; characterised by air-storage chambers F02B 21/00; characterised by special shape or construction of combustion chambers F02B 23/00)
Definition statement
This subclass/group covers:

Engines characterised by positive ignition.

References relevant to classification in this group
This subclass/group does not cover:
Engines characterised by fuel-air mixture compression with positive ignition
Engines characterised by air compression and subsequent fuel addition with positive ignition
Informative references
Attention is drawn to the following places, which may be of interest for search:
Engines with non-timed positive ignition, e.g. with hot-spots
Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition
Engines characterised by special shape or construction of combustion chambers
Methods of operating
References relevant to classification in this group
This subclass/group does not cover:
Control of combustion engines
Engines characterised by the fuel-air charge being ignited by compression ignition of an additional fuel (characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition F02B 11/00; characterised by precombustion chambers F02B 19/00; characterised by air-storage chambers F02B 21/00; characterised by special shape or construction of combustion chambers F02B 23/00)
Definition statement
This subclass/group covers:

Engines characterised by the fuel-air charge being ignited by compression ignition of an additional fuel. E.g. a compressed fuel-air mixture being ignited by directly injecting a diesel fuel.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition
Engines characterised by precombustion chambers
Engines characterised by air-storage chambers
Engines characterised by special shape or construction of combustion chambers
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Pilot injection
The injection of an additional fuel for ignition of a compressed fuel-air mixture
Engines characterised by other types of ignition (characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition F02B 11/00; characterised by precombustion chambers F02B 19/00; characterised by air-storage chambers F02B 21/00; characterised by special shape or construction of combustion chambers F02B 23/00)
Definition statement
This subclass/group covers:

Engines characterised by other types of ignition.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition
Engines characterised by precombustion chambers
Engines characterised by air-storage chambers
Engines characterised by special shape or construction of combustion chambers
with incandescent chambers
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 9/08

E.g. "Hot bulb" engines

Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition, e.g. in different cylinders (characterised by recombustion chambers F02B 19/00; characterised by air-storage chambers F02B 21/00; characterised by special shape or construction of combustion chambers F02B 23/00)
Definition statement
This subclass/group covers:

Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition, e.g. in different cylinders. E.g.: engines switching between positive ignition and compression ignition, or performing homogeneous charge

compression ignition combustion during a first operating condition, and performing spark ignition or "diesel" combustion during a second operating condition.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Engines characterised by precombustion chambers
Engines characterised by air-storage chambers
Engines characterised by special shape or construction of combustion chambers
Engines characterised by the introduction of liquid fuel into cylinders by use of auxiliary fluid
Definition statement
This subclass/group covers:

Engines characterised by the introduction of liquid fuel into cylinders by use of auxiliary fluid.

E.g. using compressed air or gas for blowing fuel into combustion chamber.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Fuel injection apparatuses where fuel-injection is effected by means of high-pressure gas
Engines characterised by the method of introducing liquid fuel into cylinders and not otherwise provided for
Definition statement
This subclass/group covers:

This group is only used for exceptional cases of engines with fuel introduction into cylinder that cannot be classified elsewhere.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Indirect injection
Direct injection
Engines characterized by means for effecting stratification of charge in cylinders
Definition statement
This subclass/group covers:

Engines characterized by means for effecting stratification of charge in cylinders.

In a stratified charge engine, the fuel is injected into the cylinder just before ignition. This allows for higher compression ratios without "knock," and leaner air/fuel mixtures than in conventional internal combustion engines.

Relationship between large subject matter areas

The stratification of the charge of air and fuel in the cylinder is determined by:

the shape of the air intake, the position of the fuel injector, the shape of the cylinder head, the shape of the piston head or combustion space.

References relevant to classification in this group
This subclass/group does not cover:
Engines with air compression and subsequent fuel addition
Informative references
Attention is drawn to the following places, which may be of interest for search:
Cylinder heads (shape)
Combustion chambers (shape)
Pistons
Modifying induction systems for imparting a rotation to the charge in the cylinder
Electrical control of supply of combustible mixture or its constituents
Special rules of classification within this group

Classification should be limited to the constructional features of the combustion chamber for making stratification of charge possible.

Control features are classified in F02D

F02B 17/005: having direct injection in the combustion chamber

Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Stratification
Layers of air and fuel
Charge
Air and/or fuel contents in cylinder
Engines characterised by precombustion chambers (engines with incandescent chambers F02B 9/08)
Definition statement
This subclass/group covers:

Engines characterized by pre-combustion chambers.

Chambers are located at the cylinder head and connected to the engine cylinder by small holes. Generally the following steps in the combustion take place. During the compression stroke, air from the main cylinder enters the pre-combustion chamber. At this moment, fuel is injected into the pre-combustion chamber and is ignited by a spark plug or a glow plug. Pressure increases and the ignited charge is forced through the small holes into the main cylinder, resulting in an ignition of the main charge in the combustion chamber.

Relationship between large subject matter areas

Indirect injection diesel engine. Multi fuel engines. Lean burn engines. Gas engines.

References relevant to classification in this group
This subclass/group does not cover:
Engines with incandescent chambers
Engines with air storage cambers
Informative references
Attention is drawn to the following places, which may be of interest for search:
Engines with special shape of combustion chamber
Cylinders; Cylinder heads
Engines with fuel air mixture compression
Sparking plugs in partly enclosed ignition chamber
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Incandescent chamber
Chamber with hot spot
Torch passage
Passage between pre- and main combustion chamber
Squish area
Compressed area between piston top and cylinder head
Air swirl
Rotational movement of air
Synonyms and Keywords

In patent documents the following expressions/words "pre-combustion chamber", "pre-chamber" and "ignition chamber" are often used as synonyms.

Engines characterized by air-storage chambers
Definition statement
This subclass/group covers:

Engines with an auxiliary chamber which is connected and disconnected with the engine intake or cylinder during the compression or expansion period of the engine cycle in order to influence the compression or expansion process.

Relationship between large subject matter areas

Provision for charging and scavenging, F02B 29/00. Pumps for air charging and scavenging, F02B 33/00. Using engine as a brake, F02D 13/00.

References relevant to classification in this group
This subclass/group does not cover:
Compressed air driven engines
Air hybrid prime movers
Informative references
Attention is drawn to the following places, which may be of interest for search:
Cylinders; cylinder heads
Special rules of classification within this group

F02B 21/02: Chamber shapes or constructions

Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Auxiliary chamber
Chamber not being a combustion chamber
Synonyms and Keywords

In patent documents the following expressions/words "air storage chamber" and "air accumulator "are often used as synonyms.

In patent documents the following expressions/words "auxiliary chamber" and "air tank" are often used as synonyms.

Other engines characterised by special shape or construction of combustion chambers to improve operation (engines with incandescent chambers F02B 9/08)
Definition statement
This subclass/group covers:

Engines characterised by a special shape of the combustion chamber to improve operation. The shape of the combustion space between the cylinder head and the working piston determines how the combustible mixture of air and fuel is combusted. The group mainly deals with the configuration of the combustion space in the piston for compression but also for spark ignited engines.

Relationship between large subject matter areas

Configuration of cylinder heads and pistons, F02F 1/00. Position of fuel injectors, F02B 23/10 and air intake systems, F02B 31/00.

References relevant to classification in this group
This subclass/group does not cover:
Engines with incandescent chambers
Cylinders
Pistons
Fuel injectors
Informative references
Attention is drawn to the following places, which may be of interest for search:
Cylinders
Pistons
Air Induction systems
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Squish flow
Flow through a narrowing area
Swirl flow
Flow in a circular current
Engines characterised by using fresh charge for scavenging cylinders (aspects characterised by provision of driven charging or scavenging pumps F02B 33/00 to F02B 39/00)
Definition statement
This subclass/group covers:

Engines characterized by using fresh charge for scavenging cylinders.

Mostly two-stroke engines i.e. internal combustion engines that complete the process cycle in one revolution of the crankshaft, i.e. an up stroke and a down stroke of the piston. This is accomplished by using the beginning of the compression stroke and the end of the combustion stroke to perform simultaneously the intake and exhaust or scavenging functions. In this way, two-stroke engines often provide high specific power, at least in a narrow range of rotational speeds. The functions of some or all of the valves required by a four-stroke engine are usually served in a two-stroke engine by ports that are opened and closed by the motion of the piston.

Relationship between large subject matter areas

Gasoline, spark ignition versions are particularly useful in lightweight portable applications, such as lawn mowers. The concept is also used in diesel compression ignition engines in large applications, such as ships and locomotives.

References relevant to classification in this group
This subclass/group does not cover:
Aspects characterized by provision of driven charging or scavenging pumps.
Rotary engines
Informative references
Attention is drawn to the following places, which may be of interest for search:
Pumps for charging or scavenging
Other types of engines
Cylinders; cylinder heads
Rotary valve arrangements
Engines for driving hand-held tools
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Unidirectional scavenging
Scavenging gas flows in one directionin the cylinder
Reverse-flow scavenging
Scavenging gas flows up and down again
Reed valve
Type of unidirectional valve
Use of kinetic or wave energy of charge in induction systems, or of combustion residues in exhaust systems, for improving quantity of charge or for increasing removal of combustion residues (aspects characterised by provision of driven charging or scavenging pumps F02B 33/00 to F02B 39/00, e.g. use of driven apparatus for immediate conversion of combustion gas pressure into pressure of fresh charge F02B 33/42)
Definition statement
This subclass/group covers:

Internal combustion engines with a variable configuration intake manifold or exhaust manifold technology. Variable configuration intake or exhaust manifold technology can vary the configuration of the intake or exhaust tract in order to optimise power and torque across the range of engine speed operation, as well as help provide better fuel efficiency. The effect is often achieved by having two separate intake ports, each controlled by a valve, that open two different manifolds - one with a short path that operates at full engine load, and another with a significantly longer path that operates at lower load.

Relationship between large subject matter areas

Engines characterized by provisions for charging or scavenging not provided for in groups F02B 25/00,F02B 27/00, F02B 33/00 to F02B 39/00

References relevant to classification in this group
This subclass/group does not cover:
Aspects characterized by provision of driven charging or scavenging pumps
Use of driven apparatus for immediate conversion of combustion gas pressure into pressure of fresh charge
Informative references
Attention is drawn to the following places, which may be of interest for search:
Modifying induction systems
Exhaust silencing apparatus
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Resonance charging
Oscillating air column charging
Engines characterized by provision for charging or scavenging not provided for in groups F02B 25/00, F02B 27/00 or F02B 33/00 to F02B 39/00; Details thereof
Definition statement
This subclass/group covers:

Means to improve the engine's volumetric efficiency by increasing the air intake density. The pressure of ambient air drawn in is increased and the temperature is decreased before it enters into the engine cylinder. This results in a greater mass of air entering the cylinder on each intake stroke.

Relationship between large subject matter areas

Usually pumps, F02B 33/00 or turbochargers, F02B 37/00 are used to improve the engine's volumetric efficiency by increasing the air intake density. The compressor draws in ambient air and compresses it before it enters into the intake manifold at increased pressure. This results in a greater mass of air entering the cylinders on each intake stroke. In combination with these chargers provision, like cooling, F02B 29/00 or resonance charging, F02B 27/00 can be foreseen to improve the efficiency of these machines.

References relevant to classification in this group
This subclass/group does not cover:
Pumps for charging or scavenging
Turbo charging
Resonance charging
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Fluid dynamic features
For example: air storage tanks
After charging
Charging after turbo or super charging
Synonyms and Keywords

In patent documents the following expressions/words " heat exchanger" and "cooler" are often used as synonyms.

Modifying induction systems for imparting a rotation to the charge in the cylinder (structural features of induction systems F02M)
Definition statement
This subclass/group covers:

Modifications of the induction system of internal combustion engines to improve the mixing and distribution of air and fuel in the cylinder. The group covers modifications to the intake passages up until the intake port of the cylinder of the engine.

Relationship between large subject matter areas

A specific geometry of the induction system can create a beneficial air swirl or tumble pattern in the combustion chamber. The swirl or tumble helps to distribute the fuel and form a homogeneous air-fuel mixture. This aids the initiation of the combustion process.

References relevant to classification in this group
This subclass/group does not cover:
Cylinders, cylinder heads
Air induction systems
Shape of combustion chamber
Lift valves
Informative references
Attention is drawn to the following places, which may be of interest for search:
Air induction systems
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Swirl
Rotation around cylinder axis
Tumble
Rotation around transverse cylinder axis
Synonyms and Keywords

In patent documents the following expressions/words "swirl" and "turbulence" are often used as synonyms.

Engines characterised by provision of pumps for charging or scavenging (characterised by the introduction of liquid fuel into cylinders by use of auxiliary fluid F02B 13/00; characterised by after-charging F02B 29/06; characterised by provision of pumps for sucking combustion residues from cylinders F02B 35/00; characterised by provision of exhaust-driven pumps F02B 37/00)
Definition statement
This subclass/group covers:

Engines characterised by provision of pumps for charging or scavenging.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Engines characterised by introducing fuel into cylinders by auxiliary fluid, e.g. by air-pressure
Exhaust-driven pumps
After-charging
Engines with pumps for sucking combustion residues from cylinders
Arrangements of such pumps or other auxiliary apparatus on engines
Combined engine and pump control, control dependent on variables other than those generic to pumps
Turbochargers per se
Pumps per se
F04
with simple crankcase pump, i.e. with the rear face of a non-stepped working piston acting as sole pumping member in co-operation with the crankcase
Informative references
Attention is drawn to the following places, which may be of interest for search:
Cylinders characterised by having ports in cylinder for scavenging or charging
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/04

E.g.:

With reciprocating-piston pumps other than simple crankcase pumps
Definition statement
This subclass/group covers:

With reciprocating-piston pumps other than simple crankcase pumps, e.g. engine-driven piston pumps.

with the working-cylinder head arranged between working and pumping cylinders
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/08

E.g.:

the rear face of working piston acting as pumping member and co-operating with a pumping chamber isolated from crankcase, the connecting-rod passing through the chamber and co-operating with movable isolating member
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/12

E.g.:

working and pumping pistons forming stepped piston
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/14

with crankshaft being arranged between working and pumping cylinders
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/18

with pumping-cylinder axis arranged at an angle to working-cylinder axis, e.g. at an angle of 90 degrees
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/20

E.g.:

with pumping cylinder situated at side of working cylinder, e.g. the cylinders being parallel
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/22

E.g.:

Four-stroke engines characterised by having crankcase pumps
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/26

E.g.:

Control of inlet or outlet ports (controlling only working-cylinder inlets F01L)
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/30

E.g.:

Engines with pumps other than of reciprocating-piston type (with crankcase pumps F02B 33/02)
References relevant to classification in this group
This subclass/group does not cover:
Engines with crankcase pumps
with rotary pumps (with cell-type pressure exchangers or the like F02B 33/42)
References relevant to classification in this group
This subclass/group does not cover:
Cell-type pressure exchangers or the like
of Roots type
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/38

E.g.:

of non-positive-displacement type
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 33/40

E.g.:

with driven apparatus for immediate conversion of combustion gas pressure into pressure of fresh charge, e.g. with cell-type pressure exchangers (pressure exchangers per se F04F 13/00)
Definition statement
This subclass/group covers:

Engine with driven or non-driven apparatus for immediate conversion of combustion gas pressure into pressure of fresh charge, e.g. with cell-type pressure exchangers.

E.g.:

Informative references
Attention is drawn to the following places, which may be of interest for search:
Pressure exchangers per se
Passages conducting the charge from the pump to the engine inlet, e.g. reservoirs (cooling of charge after leaving pumps F02B 29/04)
Definition statement
This subclass/group covers:

Passages conducting the charge from the pump to the engine inlet, e.g. reservoirs. This group covers also air passages of turbocharged engines and scavenging channels with special features in two-stroke engines.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Cooling of charge after leaving the pump
Engines characterised by provision of pumps for sucking combustion residues from cylinders
Definition statement
This subclass/group covers:

Engines characterised by provision of pumps for sucking combustion residues from cylinders.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Arrangements of such pumps or other auxiliary apparatus on engines
After-charging
using rotary pumps
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 35/02

e.g.:

Engines characterised by provision of pumps driven at least for part of the time by exhaust (characterised by the introduction of liquid fuel into cylinders by use of auxiliary fluid F02B 13/00; characterised by after-charging F02B 29/06; characterised by passages conducting the charge from the pump to the engine inlet F02B 33/44)
Definition statement
This subclass/group covers:

Engines with turbocharging.

References relevant to classification in this group
This subclass/group does not cover:
Details or constructional aspects of turbines
Turbochargers
Pumps
F04
Turbocharger casings, arrangement of bearings in turbochargers, cooling or lubrication of turbochargers per se
Constructional aspects of bypass valves in turbochargers
Valves in general
Turbocompound
Engines characterised by provision of driven charging or scavenging pumps. Introducing fuel into cylinders by air-pressure
After-charging
Arrangements of such pumps or other auxiliary apparatus on engines
Combined engine and pump control, control dependent on variables other than those generic to pump
Informative references
Attention is drawn to the following places, which may be of interest for search:
Passages conducting the charge from the pumps to the engine inlet
with exhaust-driven pumps arranged in parallel, [N: e.g. at least one pump supplying alternatively]
Definition statement
This subclass/group covers:

with exhaust-driven pumps arranged in parallel. E.g. at least one parallel pump being driven alternatively.

with exhaust-driven pumps arranged in series
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 37/013

E.g.:

Engines with exhaust drive and other drive of pumps, e.g. with exhaust-driven pump and mechanically-driven second pump
Informative references
Attention is drawn to the following places, which may be of interest for search:
The specific drive of the other drive
Control of the pumps
Definition statement
This subclass/group covers:

Control of turbocharging of engines. These groups cover also electronic control of turbochargers.

References relevant to classification in this group
This subclass/group does not cover:
Details or constructional aspects of turbines
Constructional details of devices for control of turbochargers
Turbochargers
Combined engine and pump control, control dependent on variables other than those generic to pump
Controlling supercharged engines
Pumps
F04
[N: Control] of the alternation between [N: or the operation of] exhaust drive and other drive of a pump, e.g. dependent on speed
Informative references
Attention is drawn to the following places, which may be of interest for search:
Drives of a pump
by bypassing charging air
References relevant to classification in this group
This subclass/group does not cover:
Constructional aspects per se of such devices
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 37/16

by bypassing exhaust [N: from the inlet to the outlet of turbine or to the atmosphere]
Definition statement
This subclass/group covers:

Controlling the pump by bypassing exhaust.

References relevant to classification in this group
This subclass/group does not cover:
Constructional aspects of bypass valves
Informative references
Attention is drawn to the following places, which may be of interest for search:
Valves in general
[N: Arrangement of bypass valves or actuators therefor]
References relevant to classification in this group
This subclass/group does not cover:
Constructional aspects of bypass valves
Informative references
Attention is drawn to the following places, which may be of interest for search:
Valves in general
Actuating devices in general
[N: arrangements of actuators for bypass valves]
Definition statement
This subclass/group covers:

arrangement of actuators and linkage for bypass valves.

References relevant to classification in this group
This subclass/group does not cover:
Actuating devices per se
by increasing exhaust energy, e.g. using combustion chamber [N: by after-burning (using an auxiliary combustion chamber supplied by charging air F02B 37/166)]
Definition statement
This subclass/group covers:

by increasing exhaust energy, e.g. using combustion chamber upstream of turbine or injecting water.

References relevant to classification in this group
This subclass/group does not cover:
Using an auxiliary combustion chamber supplied by charging air
by varying cross-section of exhaust passages or air passages, [N: e.g. by throttling turbine inlets or outlets or by varying effective number of guide conduits (F02B 37/24 takes precedence)]
Definition statement
This subclass/group covers:

by varying cross-section of exhaust passages or air passages, e.g. by throttling turbine inlets or outlets or by varying effective number of guide conduits.

References relevant to classification in this group
This subclass/group does not cover:
By using pumps or turbines with adjustable guide vanes
Constructional aspects per se of such devices
[N: air passages]
References relevant to classification in this group
This subclass/group does not cover:
Constructional aspects per se of such devices
by using pumps or turbines with adjustable guide vanes
References relevant to classification in this group
This subclass/group does not cover:
Constructional aspects per se of such devices
Component parts, details, or accessories relating to, driven charging or scavenging pumps, not provided for in groups F02B 33/00 to F02B 37/00
Definition statement
This subclass/group covers:

Component parts, details, or accessories relating to, driven charging or scavenging pumps, not provided for in groups F02B 33/00 to F02B 37/00.

References relevant to classification in this group
This subclass/group does not cover:
Engines characterised by provision of driven charging or scavenging pumps. Introducing fuel into cylinders by air-pressure
After-charging
Arrangements of such pumps or other auxiliary apparatus on engines
Combined engine and pump control, control dependent on variables other than those generic to pump
Details or constructional aspects of turbines
Turbochargers
Pumps
F04
Plants in which engines use combustion products
Internal-combustion turbines
Pumps in general
F04
Machine element per se
F16
[N: Cooling of pump drives]
Definition statement
This subclass/group covers:

Arrangement of cooling system of super/turbocharger, layout (or partial layout) of cooling fluid circuits.

See e.g.:

(from ep160243)

References relevant to classification in this group
This subclass/group does not cover:
Turbocharger cooling per se, e.g. cooling a turbocharger bearing per se
Cooling of turbochargers
Cooling of turbocharger bearings
Cooling of turbocharger casing
Cooling of machines or engines in general; cooling of internal-combustion engines
Drives of pumps (exhaust drives or combined exhaust and other drives F02B 37/00); Varying pump drive gear ratio (control acting both on engine and on pump drive gear ratio F02D)
References relevant to classification in this group
This subclass/group does not cover:
Control acting both on engine and on pump drive gear ratio
Informative references
Attention is drawn to the following places, which may be of interest for search:
Exhaust drives or combined exhaust and other drives
Mechanical drives; Variable-gear-ratio drives (non-mechanical pump drives having variable gear ratio F02B 39/08)
References relevant to classification in this group
This subclass/group does not cover:
Non-mechanical pump drives having variable gear ratio
Drives characterised by use of couplings or clutches therein (using fluid slip couplings for varying gear ratio F02B 39/08)
Informative references
Attention is drawn to the following places, which may be of interest for search:
Using fluid slip couplings for varying gear ratio
Lubrication of pumps; Safety measures therefore
Definition statement
This subclass/group covers:

Lubrication of pumps; Safety measures therefore, e.g. arrangement of lubrication system of super/turbocharger, layout (or partial layout) of lubrication fluid circuits.

References relevant to classification in this group
This subclass/group does not cover:
Turbocharger lubrication per se, e.g. lubricating a turbocharger bearing per se
Lubricating of machines or engines in general; lubricating internal-combustion engines
Lubricating in general
Lubrication of bearings in general
Other safety measures for, or other control of, pumps
Informative references
Attention is drawn to the following places, which may be of interest for search:
Cleaning of turbomachines
Cleaning of pumps using liquids
Measuring vibration of turbo machines
Engines characterised by special means for improving conversion of heat or pressure energy into mechanical power
Definition statement
This subclass/group covers:

Engines characterised by special means for improving conversion of heat or pressure energy into mechanical power, e.g. modification of compression ratio to enhance thermal efficiency or by using "turbocompound" i.e. using the exhaust to drive a turbine connected to the crankshaft.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Variable compression ratio
Modified dwell of piston in TDC
Thermal insulation
Engines with prolonged expansion
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Prolonged expansion
relative to the compression
Modified dwell
The piston remains longer than usual at TOP DEAD CENTRE
Miller cycle
A modified four stroke cycle where the compression stroke is made shorter by blow back through late inlet valve closing, for turbo charged engines
Atkinson cycle
the same as Miller cycle, but for normally aspirated engines
in main cylinders
Definition statement
This subclass/group covers:

Engines with means and ways to make the compression stroke and the expansion stroke different.

E.g. engines using the Miller or Atkins cycles or using mechanical means in order to have special stroke of piston.

in compound cylinders
Definition statement
This subclass/group covers:

Engines with more than one expansion stroke. I.e. the exhaust is allowed to expand in an additional cylinder. The compounding is similar to the compounding in a steam engine.

Two-stroke compound engines
Definition statement
This subclass/group covers:

Two stroke engines with second expansion in an expansion cylinder

in exhaust turbines (use of exhaust turbines for charging F02B 37/00; turbines constructions F01D; gas turbine plant F02C)
Definition statement
This subclass/group covers:

Turbocompounding. The exhaust gas is expanded in a turbine which is directly or indirectly connected to the engine crankshaft.

E.g.:

Informative references
Attention is drawn to the following places, which may be of interest for search:
Use of exhaust turbines for charging
Turbine construction
Gas turbine plants
Engines characterised by operating on gaseous fuels; Plants including such engines (engines characterised by the gas-air charge being ignited by compression ignition of an additional fuel F02B 7/06; engines convertible from gas to other fuel consumption F02B 69/04)
Definition statement
This subclass/group covers:

Engines characterised by operating on gaseous fuels; Plants including such engines

References relevant to classification in this group
This subclass/group does not cover:
Engines characterised by the gas-air charge being ignited by compression ignition of an additional fuel
Engines convertible from gas to other fuel consumption
Installations for supply of gas per se
Control of gas supply per se
Informative references
Attention is drawn to the following places, which may be of interest for search:
Fuel supply apparatuses
Control of gas engines
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
LNG
Liquefied Natural Gas; behaves like an inert gas. It has a high critical compression ratio. Therefore, only used with spark ignition or pilot fuel ignition
LPG
Liquefied Petroleum Gas
CNG
Compressed Natural Gas
DME
Dimethyl ether
Engines or plants characterised by use of other specific gases, e.g. acetylene, oxyhydrogen
Definition statement
This subclass/group covers:

Engines of plants characterised by use of other specific gases, e.g. acetylene, oxyhydrogen, hydrogen, oxygen.

References relevant to classification in this group
This subclass/group does not cover:
Production of hydrogen
Fuel cell per se
Informative references
Attention is drawn to the following places, which may be of interest for search:
Supplying engines with gaseous fuel
Methods of operating
Definition statement
This subclass/group covers:

methods of operating such engines.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Controlling combustion engines
Engines characterised by operating on non-liquid fuels other than gas; Plants including such engines (plants involving generation of gaseous fuel from solid fuel F02B 43/08; engines convertible from gas to other fuel consumption F02B 69/04)
Definition statement
This subclass/group covers:

Engines operating on non-liquid fuels other than gas, such as solid or semi-solid fuels.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Plants involving generation of gaseous fuels from solid fuel
Engines convertible from gas to other fuel consumption
operating on powdered fuel e.g. powdered coal (operating on fuel containing oxidant F02B 45/06)
Definition statement
This subclass/group covers:

operating of powdered fuel e.g. powdered coal

Informative references
Attention is drawn to the following places, which may be of interest for search:
Operating on fuel containing oxidant
Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines
Definition statement
This subclass/group covers:

Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines:

the substances being water or steam
References relevant to classification in this group
This subclass/group does not cover:
Apparatus for adding water or steam to engine
the substance including non-airborne oxygen (F02B 47/10 takes precedence)
Definition statement
This subclass/group covers:

The added substance including non-airborne oxygen, e.g. N2O: Laughing gas

References relevant to classification in this group
This subclass/group does not cover:
Circulation of exhaust gas in closed or semi-closed circuits
Apparatus for supplying non-airborne oxygen to engine
the substances including exhaust gas
References relevant to classification in this group
This subclass/group does not cover:
Apparatus for adding exhaust gas to engines
Circulation of exhaust gas in closed or semi-closed circuits, e.g. with simultaneous addition of oxygen
References relevant to classification in this group
This subclass/group does not cover:
Apparatus for adding exhaust gas to engine
Methods of operating air-compressing compression-ignition engines involving introduction of small quantities of fuel in the form of a fine mist into the air in the engine’s intake
Definition statement
This subclass/group covers:

Methods of operating air-compressing compression-ignition engines involving introduction of small quantities of fuel in the form of a fine mist into the air in the engine's intake. E.g. as starting aid

Other methods of operating engines involving pretreating of, or adding substances to, combustion air, fuel, or fuel-air mixture of the engines
Definition statement
This subclass/group covers:

Other methods of operating engines involving pretreating of, or adding substances to, combustion air, fuel, or fuel-air mixture of the engines.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Apparatuses for treating combustion-air, fuel of fuel-air mixture, by catalyst, electric means, magnetism, rays, sound waves or the like
involving catalysts
References relevant to classification in this group
This subclass/group does not cover:
Apparatus for treating combustion-air, fuel, or fuel-air mixture by catalyst
involving electricity or magnetism
References relevant to classification in this group
This subclass/group does not cover:
Apparatus for treating combustion-air, fuel, or fuel-air mixture by electric means or magnetism
involving rays or sound waves
References relevant to classification in this group
This subclass/group does not cover:
Apparatus for treating combustion-air, fuel, or fuel-air mixture by sonic or ultrasonic waves
Internal-combustion aspects of rotary-piston or oscillating-piston engines (internal-combustion aspects of rotary pistons or outer members for co-operation therewith F02B 55/00)
Definition statement
This subclass/group covers:

Internal-combustion aspects of rotary-piston or oscillating-piston engines

Informative references
Attention is drawn to the following places, which may be of interest for search:
Rotary-piston machines or engines per se
Oscillating-piston machines or engines
Internal combustion aspects of rotary pistons or outer members of co-operating therewith
Internal-combustion aspects of rotary pistons; Outer members for co-operation with rotary pistons
Definition statement
This subclass/group covers:

Internal combustion aspects of rotary pistons or outer members for co-operation with rotary pistons.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Rotary-piston machines or engines per se
Oscillating-piston machines or engines
Cooling thereof
Special rules of classification within this group

Illustrative example of subject matter classified in F02B 55/10

E.g.:

Internal-combustion aspects of rotary engines in which the combusted gases displace one or more reciprocating pistons
Definition statement
This subclass/group covers:

Internal-combustion aspects of rotary engines in which the combusted gases displace one or more reciprocating pistons. E.g.:

Fuel or combustion-air supply (cylinder-charge admission or exhaust control F02B 57/04)
Informative references
Attention is drawn to the following places, which may be of interest for search:
Cylinder-charge admission of exhaust control
Control of cylinder-charge admission or exhaust (peculiar to two-stroke engines or to other engines with working-piston-controlled charge admission or exhaust F02B 57/06)
References relevant to classification in this group
This subclass/group does not cover:
Two-stroke engines or other engines with working-piston-controlled charge admission or exhaust
Two-stroke engines or other engines with working-piston-controlled cylinder-charge admission or exhaust (with combustion space in centre of star F02B 57/10)
References relevant to classification in this group
This subclass/group does not cover:
With combustion space in centre of star
Engines with star-shaped cylinder arrangements
Definition statement
This subclass/group covers:

Engines with star-shaped cylinder arrangements, e.g.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Reciprocating-piston machines or engines with rotating cylinders in star arrangement
Reciprocating-piston machines or engines with the rotating cylinders arranged substantially tangentially to a circle centred on the main shaft axis
with combustion space in centre of star
Definition statement
This subclass/group covers:

Engines with combustion space in centre of star, e.g.:

Internal-combustion aspects of other reciprocating-piston engines with movable, e.g. oscillating, cylinders (with yieldable walls F02B 75/38)
Definition statement
This subclass/group covers:

Internal-combustion aspects of other reciprocating-piston engines with movable, e.g. oscillating, cylinders. E.g.:

References relevant to classification in this group
This subclass/group does not cover:
Reciprocating-piston engines with parts of combustion- or working-chamber walls resiliently yielding under pressure
Adaptations of engines for driving vehicles or for driving propellers; Combinations of engines with gearing (the engine torque being divided by a differential gear for driving a scavenging or charging pump and the engine output shaft F02B 39/06; adaptations or combinations of rotary-piston or oscillating-piston engines F02B 53/14; arrangements in vehicles, see the relevant classes for vehicles)
Definition statement
This subclass/group covers:

Adaptations of engines for driving vehicles of for driving propellers; Combinations of engines with gearing.

References relevant to classification in this group
This subclass/group does not cover:
Engine torque being divided by a differential gear for driving a scavenging or charging pump and the engine output shaft
Adaptions of combinations of rotay-piston or oscillating-piston engines
Arrangement in vehicles
see the relevant classes for the specific vehicles
for driving cycles
Definition statement
This subclass/group covers:

Engines for driving cycles; E.g.:

for driving propellers
Definition statement
This subclass/group covers:

Engines for driving propellers; E.g.:

[N: for outboard marine engines]
Definition statement
This subclass/group covers:

Outboard marine and engines, Inboard marine engines, Jetski engines.

Combinations of engines with mechanical gearing (F02B 61/02, F02B 61/04 take precedence)
Definition statement
This subclass/group covers:

Combinations of engines with mechanical gearing

References relevant to classification in this group
This subclass/group does not cover:
Adaptations of engines for driving cycles
Adaptations of engines for driving propellers
Adaptations of engines for driving pumps, hand-held tools or electric generators; Portable combinations of engines with engine-driven devices (of rotary-piston or oscillating-piston engines F02B 53/14)
Definition statement
This subclass/group covers:

Adaptations of engines for driving pumps, hand-held tools or electric generators; Portable combinations of engines with engine-driven devices

References relevant to classification in this group
This subclass/group does not cover:
Adaptations of rotary-piston or oscillating-piston engines
for electric generators
Definition statement
This subclass/group covers:

Adaptations of engines for electric generators; E.g.:

Adaptations of engines for special uses not provided for in groups F02B 61/00 or F02B 63/00; Combinations of engines with other devices, e.g. with non-driven apparatus (of rotary-piston or oscillating-piston engines F02B 53/14; combinations of prime-movers consisting of electric motors and internal combustion engines for mutual or common propulsion B60K 6/20)
Definition statement
This subclass/group covers:

Adaptations of engines for special uses not provided for in groups F02B 61/00 or F02B 63/00; Combinations of engines with other devices, e.g. with non-driven apparatus. E.g. Internal combustion engine where an engine cylinder may act as an air compressor

References relevant to classification in this group
This subclass/group does not cover:
Adaptations of rotary-piston or oscillating-piston engines
Combinations of prime-movers consisting of electric motors and internal combustion engines for mutual or common propulsion
Engines characterised by the arrangement of auxiliary apparatus not being otherwise provided for, e.g. the apparatus having different functions; Driving auxiliary apparatus from engines, not otherwise provided for
Definition statement
This subclass/group covers:

Engines characterised by the arrangement of auxiliary apparatuses not being otherwise provided for, e.g. the apparatus having different functions; Driving auxiliary apparatus from engines, not otherwise provided for.

driven by means of chains, belts, or like endless members
Definition statement
This subclass/group covers:

Auxiliary devices driven by means of chains, belts, or like endless members

of non-mechanically driven auxiliary apparatus
Definition statement
This subclass/group covers:

Non-mechanically driven auxiliary apparatus. E.g. electrically, hydraulically or pneumatically driven.

of charging or scavenging apparatus
Definition statement
This subclass/group covers:

Engines characterised by the arrangement charging or scavenging apparatus. E.g driving arrangement or mounting arrangement. Also for particular positioning with respect to engine.

Internal-combustion engines convertible into other combustion-engine type, not provided for in F02B 11/00; Internal-combustion engines of different types characterised by constructions facilitating use of same main engine-parts in different types
Definition statement
This subclass/group covers:

Internal combustion engines convertible into other combustion-engine type not provided for in F02B 11/00; Internal-combustion engines of different types characterised by constructions facilitating use of same main engine-parts in different types.

E.g. engines convertible from two stroke to four stroke, or convertible for use with different fuels

References relevant to classification in this group
This subclass/group does not cover:
Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition, e.g. in different cylinders
Free-piston engines; Engines without rotary main shaft
Definition statement
This subclass/group covers:

Free-piston engines; Engines without rotary main shaft. E.g.:

Combinations of two or more engines, not otherwise provided for
Definition statement
This subclass/group covers:

E.g. combining two or more engines, not otherwise provided for, e.g. of the same or different type, e.g. an internal combustion engine and a Stirling engine.

Other engines
Definition statement
This subclass/group covers:

Other engines

[N: Double acting engines]
Definition statement
This subclass/group covers:

Double acting engines

[N: having horizontal cylinders (F02B 75/007 takes precedence)]
Definition statement
This subclass/group covers:

Engines having horizontal cylinders. E.g.:

References relevant to classification in this group
This subclass/group does not cover:
Engines having vertical crankshafts
[N: having vertical crankshafts]
Definition statement
This subclass/group covers:

Engines having vertical crankshafts

Engines characterised by their cycles, e.g. six-stroke
Definition statement
This subclass/group covers:

Engines characterised by their cycles, e.g. six-stroke.

Engines with variable distances between pistons at top dead-centre positions and cylinder heads
Definition statement
This subclass/group covers:

Engines with variable distances between pistons at top dead-centre positions and cylinder heads; E.g.:

Informative references
Attention is drawn to the following places, which may be of interest for search:
Controlling engines with variable distances between piston and cylinder head
Valve operation
[N: by means of cylinder or cylinder head positioning]
Definition statement
This subclass/group covers:

Engines characterised by means of cylinder or cylinder head positioning; E.g.:

[N: by means of an adjustable piston length]
Definition statement
This subclass/group covers:

Engines characterised by means of an adjustable piston length; E.g.:

[N: by means of a variable connecting rod length]
Definition statement
This subclass/group covers:

Engines characterised by means of a variable connecting rod length; E.g.:

[N: by means of variable crankshaft position]
Definition statement
This subclass/group covers:

Engines characterised by means of variable crankshaft position; E.g.:

[N: by means of a variable crank stroke length]
Definition statement
This subclass/group covers:

Engines characterised by means of a variable crank stroke length; E.g.:

Engines with means for equalising torque (compensation of inertial forces, suppression of vibration in systems F16F)
Informative references
Attention is drawn to the following places, which may be of interest for search:
Compensation of inertial forces, suppression of vibration in systems
[N: with double connecting rods or crankshafts]
Definition statement
This subclass/group covers:

Engines with double connecting rods or crankshafts; E.g.:

Engines with means for preventing corrosion in gas-swept spaces
Definition statement
This subclass/group covers:

Engines with means for preventing corrosion in gas-swept spaces

Informative references
Attention is drawn to the following places, which may be of interest for search:
Mid supported liners
F16J1/16M
Engines with means for rendering exhaust gases innocuous (apparatus per se F01N)
Definition statement
This subclass/group covers:

Engines with means for rendering exhaust gases innocuous.

References relevant to classification in this group
This subclass/group does not cover:
Apparatus for purifying, rendering innocuous or otherwise treating exhaust
Control of combustion engines
[N: with two or more pistons connected to one crank and having a common combustion space]
Definition statement
This subclass/group covers:

Engines with two or more pistons connected to one crank and having a common combustion space; E.g.:

with cylinders all in one line
Definition statement
This subclass/group covers:

Illustrative example of subject matter classified in this group:

with cylinders in V, fan, or star arrangement
Definition statement
This subclass/group covers:

Engines with cylinders in V, fan, or star arrangement

[N: with cylinder banks in narrow V-arrangement, having a single cylinder head]
Definition statement
This subclass/group covers:

Engines with cylinder banks in narrow V-arrangement, having a single cylinder head.

[N: with cylinders in star arrangement]
Definition statement
This subclass/group covers:

Engines with cylinders in star arrangement; E.g.:

[N: with cylinders in fan arrangement]
Definition statement
This subclass/group covers:

Engines with cylinders in fan arrangement

[N: having two or more crankshafts]
Definition statement
This subclass/group covers:

Engines having two or more crankshafts

[N: with cylinder banks in X-arrangement, e.g. double-V engines]
Definition statement
This subclass/group covers:

Engines with cylinder banks in X-arrangement, e.g. double-V engines

[N: with cylinders arranged in parallel banks]
Definition statement
This subclass/group covers:

Engines with cylinders arranged in parallel banks

[N: with only one crankshaft of the "boxer" type, e.g. all connecting rods attached to separate crankshaft bearings]
Definition statement
This subclass/group covers:

Engines with only one crankshaft of the "boxer" type, e.g. all connecting rods attached to separate crankshaft bearings

[N: with only one crankshaft of the "pancake" type, e.g. pairs of connecting rods attached to common crankshaft bearing]
Definition statement
This subclass/group covers:

Engines with only one crankshaft of the "pancake" type, e.g. pairs of connecting rods attached to common crankshaft bearing

Engines with cylinder axes coaxial with, or parallel or inclined to, main-shaft axis; Engines with cylinder axes arranged substantially tangentially to a circle centered on main-shaft axis
Definition statement
This subclass/group covers:

Engines with cylinder axes coaxial with, or parallel or inclined to, main-shaft axis; Engines with cylinder axes arranged substantially tangentially to a circle centered on main-shaft axis

Informative references
Attention is drawn to the following places, which may be of interest for search:
Reciprocating-piston machines or engines with cylinder axes coaxial with, or parallel or inclined to, main shaft axis
[N: Engines with cylinder axes substantially tangentially to a circle centred on main-shaft axis]
Definition statement
This subclass/group covers:

Engines with cylinder axes substantially tangentially to a circle centred on main-shaft axis

Engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders (arranged oppositely relative to main shaft F02B 75/24)
Definition statement
This subclass/group covers:

Engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders

References relevant to classification in this group
This subclass/group does not cover:
Multi-cylinder engines with cylinders arranged oppositely relative to main shaft
Informative references
Attention is drawn to the following places, which may be of interest for search:
Engines with with oppositely reciprocating pistons
[N: the pistons having equal strokes]
Definition statement
This subclass/group covers:

Engines with pistons having equal strokes

[N:comprising a free auxiliary piston]
Definition statement
This subclass/group covers:

Engines comprising a free auxiliary piston

[N:with several pistons positioned in one cylinder one behind the other]
Definition statement
This subclass/group covers:

Engines with several pistons positioned in one cylinder one behind the other

with one working piston sliding inside another
Definition statement
This subclass/group covers:

Engines with one working piston sliding inside another

Engines characterised by connections between pistons and main shafts and not specific to preceding main groups
Definition statement
This subclass/group covers:

This subgroup contains all mechanisms between pistons and main shafts not otherwise described in more pertinent classes.

This example is for an engine with pulled con-rods during working stroke.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Details for the given mechanism connecting pistons and main shafts
Ultra-small engines, e.g. for driving models
Definition statement
This subclass/group covers:

Ultra-small engines, e.g. for driving models

ANY "SMALL" ENGINE; MINIATURE CO2 ENGINES; COMPRESSED AIR ENGINES.

Cycles possible: DIESEL, GLOW IGN., SPARK ign.

Informative references
Attention is drawn to the following places, which may be of interest for search:
For steam or compressed air drive mechanism for toys
Compressed air engines
Homogeneous Charge Compression Ignition
Synonyms and Keywords

In patent documents the following expressions/words "diesel", "glowplug",

"c-methanol", "castor oil", " nitro methane" and "amylnitrate" are often used.

Engines with parts of combustion- or working-chamber walls resiliently yielding under pressure
Definition statement
This subclass/group covers:

Engines with parts of combustion- or working-chamber walls resiliently yielding under pressure

Reciprocating-piston engines (F02B 75/04 takes precedence; with resiliently-urged auxiliary piston in pre-combustion chamber F02B 19/06)
Definition statement
This subclass/group covers:

Reciprocating piston engines. E.g.:

References relevant to classification in this group
This subclass/group does not cover:
Engines with resiliently-urged auxiliary piston in pre-combustion chamber
Engines with variable distances between pistons at top dead-centre positions and cylinder heads
Other reciprocating-piston engines
Definition statement
This subclass/group covers:

Other reciprocating-piston engines

E.g.:

Component parts, details or accessories, not otherwise provided for
Definition statement
This subclass/group covers:

These groups covers component parts, details or accessories, not otherwise provided for. E.g. freeze plugs, thermal or acoustic insulation etc.

Surface coverings of combustion-gas-swept parts (of pistons or cylinders only F02F)
References relevant to classification in this group
This subclass/group does not cover:
Surface coverings of pistons or cylinders only
Cleaning of, preventing corrosion or erosion in, or preventing unwanted deposits in, combustion engines (cleaning of fuel injection apparatus F02M 65/00)
Definition statement
This subclass/group covers:

Any cleaning of engines, decarbonising, de-coking.

References relevant to classification in this group
This subclass/group does not cover:
Cleaning of fuel injection apparatus
Safety, indicating or supervising devices (thermal insulation F02B 77/11; rendering engines inoperative or idling F02D 17/04; dependent on lubricating conditions F01M 1/22; dependent on cooling F01P 11/14)
Definition statement
This subclass/group covers:

Indicating and warning devices.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Thermal insulation
Control of combustion engines
Rendering engines inoperative or idling
Rendering engines inoperative or idling on lubricant pressure failure
Indicating or safety devices relating to cooling
[N:relating to endless members (endless members, e.g. belts, for driving auxiliary apparatus F02B 67/04)]
Definition statement
This subclass/group covers:

Safety, indicating or supervising devices relating to endless members

Informative references
Attention is drawn to the following places, which may be of interest for search:
Endless members, e.g. belts, for driving auxiliary apparatus
[N:relating to valves]
Definition statement
This subclass/group covers:

Safety, indicating or supervising devices relating to valves

[N:relating to maintenance, e.g. diagnostic device (relating to lubrication F01M 11/10)]
Definition statement
This subclass/group covers:

Safety, indicating or supervising devices relating to maintenance, e.g. diagnostic device

Informative references
Attention is drawn to the following places, which may be of interest for search:
Indicating and safety devices concerning lubricant level
[N:indicating economy]
Definition statement
This subclass/group covers:

Safety, indicating or supervising devices indicating economy

[N:with sensors measuring combustion processes, e.g. knocking, pressure, ionization, combustion flame]
Definition statement
This subclass/group covers:

Safety, indicating or supervising devices with sensors measuring combustion processes, e.g. knocking, pressure, ionization, combustion flame

Informative references
Attention is drawn to the following places, which may be of interest for search:
Control of combustion engines
[N:Sensor arrangements in the exhaust, e.g. for temperature, misfire, air/fuel ratio, oxygen sensors]
Definition statement
This subclass/group covers:

Sensor arrangements in the exhaust, e.g. for temperature, misfire, air/fuel ratio, oxygen sensors

Informative references
Attention is drawn to the following places, which may be of interest for search:
Using sensors in exhaust for controlling combustion engine
[N:determining top dead centre or ignition-timing]
Definition statement
This subclass/group covers:

Safety, indicating or supervising devices determining top dead centre or ignition-timing

Informative references
Attention is drawn to the following places, which may be of interest for search:
Controlling combustion engines
[N:relating to tightness]
Definition statement
This subclass/group covers:

Safety, indicating or supervising devices relating to tightness

[N: relating to engine temperature (concerning coolant temperature F01P 11/16)]
Informative references
Attention is drawn to the following places, which may be of interest for search:
Indicating and safety devices concerning coolant temperature
Safety means relating to crankcase explosions
Definition statement
This subclass/group covers:

Safety means relating to crankcase explosions

Thermal or acoustic insulation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Thermal insulation in general
Acoustic insulation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Sound insulation of engine casings, e.g. crankcases
Engine-driven auxiliary devices combined into units
Definition statement
This subclass/group covers:

Engine-driven auxiliary devices combined into units: E.g. a water pump and an alternator combined in one unit.

Running-in of internal-combustion engines (lubrication thereof F01M)
Definition statement
This subclass/group covers:

Running-in of internal-combustion engines.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Lubrication of internal combustion engines
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Last Modified: 10/11/2013