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ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES (internal-combustion aspects F02B 53/00, F02B 55/00)
Definition statement
This subclass/group covers:

Positive displacement machines, i.e. devices which could be equally an engine or pump, with rotary or oscillating pistons for elastic fluids or for combination of liquid and elastic fluid.

Relationship between large subject matter areas

Related subclasses F01C and F04C cover the same type of apparatus using rotary or oscillating pistons for positive displacement. The distinguishing characteristic used for classifying the machines, i.e. devices which could be equally be an engine or pump, is the working fluid used. Machines with rotary or oscillating pistons for working fluids containing elastic fluids, e.g. a combination of liquids and elastic fluids are classified in F01C. If only liquid is used as working fluid for these machines with rotary or oscillating pistons they are classified in F04C. However, devices with rotary or oscillating pistons that are only pumps, i.e. cannot be used as engines, are classified in F04C, irrespective of the working fluid.

Engines with reciprocating pistons or rotary or oscillating pistons wherein the working fluid is a liquid are classified in F03C.

F04B covers machines or pumps with reciprocating pistons, or other kinds of positive displacement mechanisms with the exception of rotary or oscillating piston type machines or pumps.

Subject matter like cyclically operating valves, lubricating or cooling are classified in subclasses F01L, F01M, F01P irrespective of their stated application, unless their novel and non-obvious features are peculiar to their application, in which case they are classified only in the relevant subclass of F04. The subclasses F01L, F01M, F01P do not cover pump or machine features per se.

References relevant to classification in this subclass
This subclass/group does not cover:
Internal-combustion aspects of rotary-piston or oscillating-piston engines
Engines with reciprocating pistons or rotary or oscillating pistons wherein the working fluid is a liquid.
Positive displacement machines for liquids, or pumps in which the working-fluid is displaced by one or more reciprocating pistons or by flexible working members
Informative references
Attention is drawn to the following places, which may be of interest for search:
Cyclically operating valves for machines or engines
Lubrication of machines or engines in general
Gas-flow silencer or exhaust apparatus for machines or engines in general
Cooling of machines or engines in general
Combustion engines with pumps for charging
Internal-combustion aspects of rotary pistons; Outer members for co-operation with rotary pistons
Hydraulic motors
Rotary-piston or oscillating piston machines for liquids
Rotary-piston or oscillating piston pumps for elastic fluids
Fluid pressure actuators
Rotary fluid gearing using pumps and motors of the volumetric type for conveying rotary motion
Sealing in general
Means for thermal insulation in general
Special rules of classification within this subclass

As a general rule a complete classification will contain at least one class specifying the type of machine concerned, combined with at least one class out of the control group F01C 20/00, or of the sealing group F01C 19/00 or of the accessory group F01C 21/00. The subgroups of F04C should be used for details not provided for in F01C and F03C.

In cases were a control or a "Details, component, parts, or accessories" has to be classified which can be used in a number of different types of machines which would be covered by different subgroups, the type of machine considered in the document should be classified by using the corresponding Indexing Code. For details not provided for in F01C, the Indexing Codes of the F04C scheme should be used.

The Indexing Code F05C is used to classify materials and material properties.

Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Cooperating members
means the "oscillating piston" or "rotary piston" and another member, e.g., the working-chamber wall, which assists in the pumping action or machine's action
Internal axis type
means that the rotational axes of the inner and outer co-operating members remain at all times within the outer member, e.g., in a similar manner to that of a pinion meshing with the internal teeth of a ring gear
Machine
means a device that could equally be both an engine and a pump and not a device which is restricted to an engine or one which is restricted to a pump
Movement of the cooperating members
is to be interpreted as relative, so that one of the "cooperating members" may be stationary, even though reference may be made to its rotational axis, or both may move
Oscillating piston machine
means a positive-displacement machine in which a fluid-engaging, work-transmitting member oscillates, e.g. a vane piston swinging back and forth about a fixed axis
Positive displacement engines
the energy of a working fluid is transformed into mechanical energy, in which variations of volume created by the working fluid in a working chamber produce equivalent movement of mechanical members, e.g. pistons transmitting the energy, the dynamic effect of the fluid being of minor importance
Positive displacement pumps
pumps using pistons or other mechanical members to displace a working fluid in a working chamber, the dynamic effect on the fluid being of minor importance
Pump
means a device for continuously raising, forcing, compressing, or exhausting fluid by mechanical means
Reciprocating piston
means a fluid-engaging, work-transmitting member of an reciprocating-piston type machine or pump that slides alternately back and forth usually along a straight line or path
Rotary piston
means a fluid engaging, work-transmitting member of a rotary-piston machine or pump that can completely rotate about a fixed axis or about an axis moving along a circular or similar orbit when operating, e.g. rotor having vanes or teeth
Rotary piston machine
means a positive-displacement machine in which a liquid-engaging, work-transmitting member rotates about a fixed axis or about an axis moving along a circular or similar orbit, e.g. machine with a rotor having vanes or teeth
Teeth or tooth equivalents
include lobes, projections or abutments
Working fluid
means the driven fluid in a pump or driving or driven liquid in a machine. The working fluid can be in a compressible, gaseous state, e.g. steam, called elastic fluid, a liquid state, or a state where there is coexistence of elastic fluid and liquid state
Rotary-piston machines or engines (with axes of co-operating members non parallel F01C 3/00; with the working-chamber walls at least partly resiliently deformable F01C 5/00; with fluid ring or the like F01C 7/00; rotary-piston machines or engines in which the working fluid is exclusively displaced by, or exclusively displaces, one or more reciprocating pistons F01B 13/00)
References relevant to classification in this group
This subclass/group does not cover:
Rotary-piston machines or engines in which the working fluid is exclusively displaced by, or exclusively displaces, one or more reciprocating pistons
With axes of co-operating members non parallel
With the working-chamber walls at least partly resiliently deformable
With fluid ring or the like
of intermeshing engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing
Informative references
Attention is drawn to the following places, which may be of interest for search:
Gear teeth manufacturing by metal processing
{Carter}
Definition statement
This subclass/group covers:

Outer members cooperating with the rotary pistons of intermeshing engagement type machines.

References relevant to classification in this subgroup
This subclass/group does not cover:
Non intermeshing-engagement type machines
Special rules of classification within this subgroup

If the carter is not the core topic, it is highly desirable to add the Indexing Code F04C 2240/10 or F04C 2240/30.

Rotary-piston machines or engines with non-parallel axes of movement of co-operating members (with the working-chamber walls being at least partly resiliently deformable F01C 5/00)
References relevant to classification in this group
This subclass/group does not cover:
Rotary-piston machines with the working-chamber walls being at least partly resiliently deformable
Rotary-piston machines or engines with the working-chamber walls at least partly resiliently deformable
References relevant to classification in this group
This subclass/group does not cover:
Rotary-piston peristaltic machines
Rotary-piston machines or engines with fluid ring or the like
Definition statement
This subclass/group covers:

Rotary-piston machines or engines in which the rotary-piston is sealed by a mass of liquid rotating inside the housing.

Oscillating-piston machines or engines
Definition statement
This subclass/group covers:

Rotary-piston machines or engines in which the rotary-piston moves back and forth inside the working chamber.

References relevant to classification in this subgroup
This subclass/group does not cover:
Rotary-piston machines with coaxially mounted members having continuously-changing circumferential spacing between them
{the piston oscillating in the space, e.g. around a fixed point (rotary piston machines or engines with non-parallel axes of rotation between co-operating members F01C 3/00) }
References relevant to classification in this subgroup
This subclass/group does not cover:
Rotary-piston machines where the working fluid is expanded in a flexible chamber
Rotary-piston machines or engines with non-parallel axes of rotation between co-operating members
Combinations of two or more machines or engines, each being of rotary-piston or oscillating-piston type (F01C 13/00 takes precedence; combinations of two or more pumps F04; fluid gearing F16H)
Definition statement
This subclass/group covers:

Combinations of two or more machines or engines, each being of rotary-piston or oscillating-piston type, such as multistage machines and parallel operating machines.

References relevant to classification in this group
This subclass/group does not cover:
Rotary-piston machines or engines with non-parallel axes of rotation between co-operating members
Combinations of two or more rotary-piston pumps
Combinations of engines with devices driven thereby
Informative references
Attention is drawn to the following places, which may be of interest for search:
Fluid gearing
Special rules of classification within this group

F01C 13/00 takes precedence.

Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby (aspects predominantly concerning driven devices, see the relevant classes for these devices)
Special rules of classification within this group

Documents classified here should have a main class elsewhere. In particular, aspects predominantly concerning the driven devices are classified in the relevant groups for these devices, e.g. F04C 18/0207.

Arrangements for drive of co-operating members, e.g. for rotary piston and casing
Special rules of classification within this group

Documents classified here should have a main classification elsewhere.

Sealing arrangements in rotary-piston machines or engines (sealings in general F16J)
Definition statement
This subclass/group covers:

Any seal construction or mode not provided by the groups, e.g. labyrinth.

References relevant to classification in this group
This subclass/group does not cover:
Sealing by liquid injection
Informative references
Attention is drawn to the following places, which may be of interest for search:
Sealing in general
for other than working fluid
Definition statement
This subclass/group covers:

Sealing arrangements for fluids other than the working fluid, e.g. lubricant, coolant. Sealing in other locations of the machine, i.e. not between successive working chambers of the machine, e.g. between housing parts, towards the external space etc.

Control of, monitoring of, or safety arrangements for, machines or engines
Special rules of classification within this group

Documents classified here should have a main classification elsewhere.

characterised by varying the volume of the working chamber (by changing the positions of inlet or outlet openings F01C 20/10)
Definition statement
This subclass/group covers:

Changing the stroke of a moving element of machines other than those meant for the sub-groups, e.g. with non parallel axes of movement.

References relevant to classification in this subgroup
This subclass/group does not cover:
By changing the positions of inlet or outlet openings
by changing the eccentricity between cooperating members
References relevant to classification in this subgroup
This subclass/group does not cover:
Internal gear machines with variable eccentricity (i.e. variable in direction and not in quantity)(no change of volume but only relative displacement of the working chamber to the inlet and outlet openings)
Component parts, details or accessories not provided for in groups F01C 1/00 to F01C 20/00
Special rules of classification within this group

Documents classified here should have a main class elsewhere.

{General arrangements of parts; Frames and supporting elements}
Definition statement
This subclass/group covers:

Supports, elastic suspension, outer frame elements of units, foundations.

References relevant to classification in this subgroup
This subclass/group does not cover:
Flow-sheets, multiple unit assemblies
{Driving elements, brakes, couplings, transmissions specially adapted for rotary or oscillating-piston machines or engines (brakes, couplings, transmissions per se F16, B60) }
Definition statement
This subclass/group covers:

All kinds of transmissions e.g. couplings, timing gears, gear boxes, shafts (as for example elastic, hollow), brakes.

Relationship between large subject matter areas

Brakes, couplings, transmissions per se: F16D, B60K.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Brakes
For pumps and compressors
{Construction of vanes or vane holders}
Definition statement
This subclass/group covers:

Details of vanes of engines but also of pumps and compressors.

{comprising guiding means, e.g. cams, rollers}
Definition statement
This subclass/group covers:

Guiding means including those for vanes guided or driven in synchronism with the piston movement.

Outer members for co-operation with rotary pistons; Casings (casings for rotary engines or machines in general F16M)
Definition statement
This subclass/group covers:

Details relating to the casing or to the stator of engines but also of pumps and compressors of the type other than intermeshing engagement.

References relevant to classification in this subgroup
This subclass/group does not cover:
Details relating to the casing or to the stator of machines of the intermeshing engagement type
Informative references
Attention is drawn to the following places, which may be of interest for search:
Casings for rotary engines or machines in general
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Last Modified: 10/11/2013