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ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
Definition statement
This subclass covers:

Pumps with rotary or oscillating pistons for liquids, for elastic fluids, or for combination of liquid and elastic fluid.

Positive displacement machines, i.e. devices which could be equally an engine or pump, with rotary or oscillating pistons for liquids only.

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.

Classification is in F03C when the working fluid is a liquid but the machine is specifically an engine with reciprocating pistons or rotary or oscillating pistons.

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. 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 does not cover:

Positive displacement engines for liquids

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:

Rotary-piston or oscillating piston engines for liquids and elastic fluids

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

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

Refrigeration machines, plants or systems

Special rules of classification within this subclass

As a general rule a complete classification will contain at least one class specifying the type of pump concerned, combined with at least one class out of the control group F04C 14/00 or F04C 28/00, or of the sealing group F04C 27/00 or of the accessory group F04C 15/00 or F04C 29/00.

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 pumps which would be covered by different groups, the type of pump considered in the document should be classified by using the corresponding Indexing Code.

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

Glossary of terms
In this subclass, the following terms (or expressions) are used with the meaning indicated:

Pump

means a device for continuously raising, forcing, compressing, or exhausting fluid by mechanical means

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

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

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

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

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

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

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

Teeth or tooth equivalents

include lobes, projections or abutments

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

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 pumps (with non-parallel axes of co-operating members F04C 3/00; with the working-chamber walls at least partly resiliently deformable F04C 5/00; with fluid ring or the like F04C 7/00; rotary-piston pumps specially adapted for elastic fluids F04C 18/00; rotary-piston machines or pumps in which the working-fluid is exclusively displaced by, or exclusively displaces, one or more reciprocating pistons F04B)
References relevant to classification in this group
This group does not cover:

Rotary-piston machines or pumps in which the working-fluid is exclusively displaced by, or exclusively displaces, one or more reciprocating pistons

Rotary-piston machines or pumps with non-parallel axes of co-operating members

Rotary-piston machines or pumps with the working-chamber walls at least partly resiliently deformable

Rotary-piston machines or pumps with fluid ring or the like

Rotary-piston machines or pumps specially adapted for elastic fluids

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

Extruders in plastic moulding

{Carter}
References relevant to classification in this group
This subgroup does not cover:

Non intermeshing-engagement type machines

Special rules of classification within this group

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

{Construction of the stationary member}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Details of the mould

Rotary-piston machines or pumps, with non-parallel axes of movement of co-operating members, e.g. of screw type (with the working-chamber walls at least partly resiliently deformable F04C 5/00; rotary-piston pumps with non-parallel axes of movement of co-operating members specially adapted for elastic fluids F04C 18/48)
Definition statement
This group covers:

Rotary-piston machines or pumps, with non-parallel axes of movement of co-operating members, e.g. of screw type

References relevant to classification in this group
This group does not cover:

Rotary-piston pumps with the working-chamber walls at least partly resiliently deformable

Rotary-piston pumps with non-parallel axes of movement of co-operating members specially adapted for elastic fluids

Rotary screw type piston pumps with parallel axes

Rotary-piston machines or pumps with the working-chamber walls at least partly resiliently deformable (such pumps specially adapted for elastic fluids F04C 18/00)
References relevant to classification in this group
This group does not cover:

Peristaltic pumps

Such pumps specially adapted for elastic fluids

Rotary-piston machines or pumps with fluid ring or the like (such pumps specially adapted for elastic fluids F04C 19/00)
Definition statement
This group covers:

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

References relevant to classification in this group
This group does not cover:

Such pumps specially adapted for elastic fluids

Oscillating-piston machines or pumps (such pumps specially adapted for elastic fluids F04C 21/00)
Definition statement
This group covers:

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

References relevant to classification in this group
This group does not cover:

Such pumps specially adapted for elastic fluids

Rotary-piston pumps 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 pumps with non-parallel axes of movement between co-operating members F04C 3/00)}
References relevant to classification in this group
This subgroup does not cover:

Rotary-piston machines or pumps in which the working fluid is compressed in a flexible chamber

Rotary-piston machines or pumps with non-parallel axes of movement between co-operating members

Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type (combinations of such pumps specially adapted for elastic fluids F04C 23/00); Pumping installations (F04C 13/00 takes precedence; specially adapted for elastic fluids F04C 23/00; fluid gearing F16H)
Definition statement
This group covers:

Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type, such as multistage and parallel operating machines; Pumping installations

References relevant to classification in this group
This group does not cover:

Combinations of such pumps specially adapted for elastic fluids

Combination of engines with pumps or compressors 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

F04C 13/00 takes precedence.

Adaptations of machines or pumps for special use, e.g. for extremely high pressures (of pumps specially adapted for elastic fluids F04C 25/00)
References relevant to classification in this group
This group does not cover:

Of such pumps specially adapted for elastic fluids

Combination of engines with pumps or compressors driven thereby

Special rules of classification within this group

Documents classified here should have a main class elsewhere.

{Removing contaminants, deposits or scale from the pump; Cleaning}
References relevant to classification in this group
This subgroup does not cover:

Prevention of deposits in the pump

{Pumps for submersible use, i.e. down-hole pumping}
Definition statement
This subgroup covers:

Drawing well fluid out of a well with the adaptation for being below the earth's surface, and also pumps working in submersed conditions for other use.

Informative references
Attention is drawn to the following places, which may be of interest for search:

Earth drilling

Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations (of pumps or pumping installations specially adapted for elastic fluids F04C 28/00)
Definition statement
This group covers:

Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations.

References relevant to classification in this group
This group does not cover:

Of pumps or pumping installations specially adapted for elastic fluids

Special rules of classification within this group

Documents classified here should have a main class elsewhere.

specially adapted for stopping, starting, idling or no-load operation
Definition statement
This subgroup covers:

Measures or means for stopping, starting or idling a compressor or a pump; measures taken as a consequence or preceding starting, stopping or idling favouring the action, e.g. having reduced side sealing pressure at start.

characterised by varying the volume of the working chamber (by changing the positions of inlet or outlet openings F04C 14/10)
Definition statement
This subgroup covers:

Rotary-piston machines or pumps controlled by varying the volume of the working chamber also including those where the underlined expression is construed as changing the stroke ("stroke" as relative displacement between cooperating members defining the size of the working chamber as in reciprocating engines).

References relevant to classification in this group
This subgroup 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 group
This subgroup does not cover:

Internal gear pumps 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 of machines, pumps or pumping installations, not provided for in groups F04C 2/00 to F04C 14/00(of pumps specially adapted for elastic fluids F04C 18/00 to F04C 29/00)
Definition statement
This group covers:

Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C 2/00 to F04C 14/00.

References relevant to classification in this group
This group does not cover:

Of pumps specially adapted for elastic fluids

{Systems for the equilibration of forces acting on the machines or pump (interstice adjustment other than by fluid pressure F01C 21/102)}
References relevant to classification in this group
This subgroup does not cover:

Bearings

Interstice adjustment other than by fluid pressure

Silencing for compressors

{Internal leakage control}
References relevant to classification in this group
This subgroup does not cover:

Seals for sealing such spaces

{Equalization of pressure pulses (silencing for compressors F04C 29/06)}
References relevant to classification in this group
This subgroup does not cover:

Silencing for compressors

Vibration control

{for eccentric movement}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Oldham couplings

{Fixing rotors on shafts, e.g. by clamping together hub and shaft}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Couplings for rigidly connecting two coaxial shafts or other movable machine elements, with clamping hub or with hub and longitudinal key

Rotor/shaft keyed connections

Shaft sleeves

Rotary-piston pumps specially adapted for elastic fluids (with fluid ring or the like F04C 19/00; rotary-piston pumps in which the working-fluid is exclusively displaced by one or more reciprocating pistons F04B)
References relevant to classification in this group
This group does not cover:

Rotary-piston pumps in which the working-fluid is exclusively displaced by one or more reciprocating pistons

Rotary-piston pumps for liquids or both liquids and elastic fluids

Rotary-piston pumps 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 subgroup covers:

Outer member cooperating with the toothed wheels; casing

References relevant to classification in this group
This subgroup does not cover:

Non intermeshing-engagement type pumps

Special rules of classification within this group

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 pumps with fluid ring or the like, specially adapted for elastic fluids
Definition statement
This group covers:

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

Oscillating-piston pumps specially adapted for elastic fluids
Definition statement
This group covers:

Rotary-piston pumps in which the rotary-piston moves back and forth inside the working chamber.

{the piston oscillating in the space, e.g. around a fixed point (rotary-piston pumps with non-parallel axes of rotation between co-operating members F04C 18/48)}
References relevant to classification in this group
This subgroup does not cover:

Rotary-piston pumps in which the working fluid is compressed in a flexible chamber

Rotary-piston pumps with non-parallel axes of movement between co-operating members

Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids (F04C 25/00 takes precedence)
Definition statement
This group covers:

Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps operating in parallel or in series specially adapted for elastic fluids.

References relevant to classification in this group
This group does not cover:

Combination of engines with pumps or compressors driven thereby

Special rules of classification within this group

F04C 25/00 takes precedence.

Adaptations of pumps for special use of pumps for elastic fluids
Definition statement
This group covers:

Adaptations of pumps for special use of pumps for elastic fluids.

References relevant to classification in this group
This group does not cover:

Combination of engines with pumps or compressors driven thereby

Special rules of classification within this group

Documents classified here should have a main class elsewhere.

for producing high vacuum (sealing arrangements F04C 27/00; silencing F04C 29/06)
Definition statement
This subgroup covers:

Pumps adapted for working at pressures below atmospheric pressure.

References relevant to classification in this group
This subgroup does not cover:

Sealing arrangements

Silencing

Informative references
Attention is drawn to the following places, which may be of interest for search:

Discharge tubes with vacuum locks

Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof

Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids
Definition statement
This group covers:

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

{Axial sealings for working fluid}
Definition statement
This subgroup covers:

Especially scroll compressors where the axial sealing force is cancelled for capacity control purposes (e.g. forming an axial gap between scroll bodies).

Special rules of classification within this group

When capacity control is concerned, it is highly desirable to add the Indexing Code F04C 28/265.

Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
Definition statement
This group covers:

Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids.

Special rules of classification within this group

Documents classified here should have a main class elsewhere.

specially adapted for stopping, starting, idling or no-load operation
Definition statement
This subgroup covers:

Measures or means for stopping, starting or idling a compressor or pump; measures taken as a consequence or preceding starting, stopping or idling favouring the action, e.g. having reduced side sealing pressure at start.

using lift valves
References relevant to classification in this group
This subgroup does not cover:

Rotary-Piston pumps where a sliding valve controls an opening or port of non uniform section progressively (or a multiplicity of holes, passages forming as a whole an inlet or outlet port of a machine, pump).

Glossary of terms
In this subgroup, the following terms (or expressions) are used with the meaning indicated:

In this group, the following terms or expressions are used with the meaning indicated:

Lift valve

valve with an ON-OFF action, i.e. opening or closing a passage in one movement

characterised by varying the volume of the working chamber (by changing the positions of inlet or outlet openings F04C 28/10)
Definition statement
This subgroup covers:

Rotary-piston pumps controlled by varying the volume of the working chamber also including those where the underlined expression is construed as changing the stroke ("stroke" as relative displacement between cooperating members defining the size of the working chamber as in reciprocating engines).

References relevant to classification in this group
This subgroup does not cover:

By changing the positions of inlet or outlet openings

Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C 18/00 to F04C 28/00
Special rules of classification within this group

Documents classified here should have a main class elsewhere.

{Equalization of pressure pulses (silencing F04C 29/06)}
References relevant to classification in this group
This subgroup does not cover:

Silencing

Vibration control

{for eccentric movement}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Oldham couplings

{Fixing rotors on shafts, e.g. by clamping together hub and shaft}
Informative references
Attention is drawn to the following places, which may be of interest for search:

Couplings for rigidly connecting two coaxial shafts or other movable machine elements, with clamping hub or with hub and longitudinal key

Rotor/shaft keyed connections

Shaft sleeves

{Removing solid or liquid contaminants from the gas under pumping, e.g. by filtering or deposition; Purging; Scrubbing; Cleaning}
References relevant to classification in this group
This subgroup does not cover:

Prevention of deposits in the pump

Lubrication (of machines or engines in general F01M); Lubricant separation (separation in general B01D)
Informative references
Attention is drawn to the following places, which may be of interest for search:

Separation in general

Lubrication of machines or engines in general

Heating; Cooling (of machines or engines in general F01P); Heat insulation (heat insulation in general F16L 59/00)
Informative references
Attention is drawn to the following places, which may be of interest for search:

Heating, cooling of machines or engines in general

Heat insulation in general

Silencing (gas-flow silencers or exhaust apparatus for machines or engines in general F01N)
Informative references
Attention is drawn to the following places, which may be of interest for search:

Gas-flow silencers or exhaust apparatus for machines or engines in general

Fluid
Definition statement
This group covers:

Additional information regarding the function, the nature and the properties of fluids inside the machine.

Application
Definition statement
This group covers:

Additional information regarding the use of the machine.

Manufacture
Definition statement
This group covers:

Additional information regarding the manufacturing process of the machine, including surface treatments, repair, assembly and disassembly methods.

Components
Definition statement
This group covers:

Additional information regarding machine parts.

Geometry
Definition statement
This group covers:

Additional information regarding forms and dimensions of machine parts.

Control; Monitoring or safety arrangements
Definition statement
This group covers:

Additional information regarding parameters used to control or monitor a rotary-piston machine.

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Last Modified: 10/11/2013