INTERNAL-COMBUSTION PISTON ENGINES

**Definition:** This place covers:

Engines characterised by the working fluid to be compressed or characterised by the type of ignition

Engines characterised by the method of introducing liquid fuel into cylinders

Engines characterised by precombustion chambers or air-storage chambers, or characterised by special shape or construction of combustion chambers to improve operation

Engines characterised by provision for charging or scavenging

Engines characterised by provision of driven charging or scavenging pumps

Engines operating on non-liquid fuels; Plants including such engines, i.e. combinations of the engine with fuel-generating apparatus

Methods of operating engines involving specific pre-treating of, or adding specific substances to, combustion air, fuel, or fuel-air mixture of the engines, and not otherwise provided for

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

Internal combustion aspects of reciprocating-piston engines with movable cylinders

Adaptations of engines for special use; Combinations of engines with devices other than engine parts or auxiliaries

**Limiting references (this place does not cover):** - Gas-turbine plants -> F02C - Hot-gas or combustion-product positive-displacement engine plants -> F02G

**Glossary:** - engine: a device for continuously converting fluid energy into mechanical power. Thus, this term includes, for example, steam piston engines or steam turbines, per se, or internal-combustion piston engines, but it excludes single-stroke devices. "Engine" also includes the fluid-motive portion of a meter unless such portion is particularly adapted for use in a motor; - pump: a device for continuously raising, forcing, compressing, or exhausting fluid by mechanical or other means. Thus, this term includes fans or blowers; - machine: a device which could equally be 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: the way 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 displacements of the mechanical member transmitting the energy, the dynamic effect of the fluid being of minor importance, and vice versa ; - non-positive displacement: the way the energy of a working fluid is transformed into mechanical energy, by transformation of the energy of the working fluid into kinetic energy, and vice versa ; - oscillating-piston machine: a positive-displacement machine in which a fluid-engaging work-transmitting member oscillates. This definition applies also to engines and pumps; - rotary-piston machine: a positive-displacement machine in which a fluid-engaging work-transmitting member rotates about a fixed axis or about an axis moving along a circular or similar orbit. This definition applies also to engines and pumps; - rotary piston: the work-transmitting member of a rotary-piston machine and may be of any suitable form, e.g., like a toothed gear; - cooperating members: the "oscillating piston" or "rotary piston" and another member, e.g., the working-chamber wall, which assists in the driving or pumping action; - movement of the co-operating members: is to be interpreted as relative, so that one of the "co-operating 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: 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; - free piston: a piston of which the length of stroke is not defined by any member driven thereby; - cylinders: positive-displacement working chambers in general. Thus, this term is not restricted to cylinders of circular cross-section; - main shaft: the shaft which converts reciprocating piston motion into rotary motion or vice versa ; - plant: an engine together with such additional apparatus as is necessary to run the engine. For example, a steam engine plant includes a steam engine and means for generating the steam; - working fluid: the driven fluid in a pump or the driving fluid in an engine. The working fluid can be in a compressible, gaseous state, called elastic fluid, e.g. steam; in a liquid state; or in a state where there is coexistence of an elastic fluid and liquid phase. - steam: includes condensable vapours in general, and "special vapour" is used when steam is excluded; - reaction type: as applied to non-positive-displacement machines or engines means machines or engines in which pressure/velocity transformation takes place wholly or partly in the rotor. Machines or engines with no, or only slight, pressure/velocity transformation in the rotor are called "impulse type".