Patent GB-1480247-A (GB)
Title: Combination engine and air compressor
IPC: F01L13/06
Filed: 1974-06-19
Abstract: 1480247 Engines alternatively usable as compressors T UENO 19 June 1974 [22 June 1973 2 July 1973 5 July 1973] 27182/74 Headings F1B and F1N A combination I.C. engine and air compressor has at least one compression chamber able to operate in a first operating mode as a combustion chamber and in a second operating mode as an air compressing chamber for compressing air without admixture of fuel, and means comprising two transmissions between a crank-shaft and one or more respective valve timing cam-shafts of the combination, the transmissions being able to operate in a way in which they do not simultaneously inter-connect the crank-shaft with a common said cam-shaft, there being in the combination a compressed air source and means for connecting the source operatively to at least one said chamber. Engine 1 has an inlet valve cam-shaft 6 and an exhaust valve cam-shaft 7. The cam-shafts are driven at half crank-shaft speed for engine action by a first transmission comprising sprockets 9,10 and 11 each of which is associated with an electromagnetic clutch 12, 13, 14 by which a sprocket can be coupled to its shaft in a predetermined angular relationship. At the other end of the engine/compressor is a second transmission which is similar except that it drives the cam-shafts at the same speed as the crank-shaft, for compressor action and the angular relationship between the crank-shaft and cam-shafts is such that the inlet valve operation is delayed relative to its operation during engine action and the exhaust valve is timed to close at T.D.C. In a modification the valve timing is not altered, the cam-shaft speed merely being increased to that of the crank-shaft. When the unit is running as a compressor, air may be exhausted through the exhaust port and diverted by an electromagnetically-operated valve in the exhaust pipe to a storage tank Fig. 2 (not shown) or an additional automatic exhaust valve 29, Fig. 3, may be provided, connected by duct 45 and check-valve 46 to tank T. The second transmission may drive the cam-shafts at half the crankshaft speed so that the inlet and exhaust valves are opened on alternate down strokes of the piston, or the cam-shafts may be driven at crank-shaft speed so that both inlet and exhaust valves open on each down stroke of the piston. When the combination is operating as an engine the automatic valve 29 is held closed by ley oil or air-pressure or by electromagnetic means. In a further embodiment, Fig. 5, the cylinders are divided into a first set 52 which always operates as an engine and has an axiallydisplaceable cam-shaft 54. The inlet and exhaust cams on this shaft each comprise two sections, a first section providing a normal amount of valve overlap and a section providing an increased amount of valve overlap, the latter section being brought into operation when the cylinders are supercharged. The second set of cylinders, 53, have an axially displaceable cam-shaft 55, carrying inlet and exhaust cams which each have sections which enable this set of cylinders to operate as an engine, as a single or two-stage compressor or in a No-load condition in which air is drawn into the cylinders but not compressed. The facility to use the second set of cylinders as a single or two-stage compressor is used to reduce the load on the first set of cylinders, when these are being started, by compressing the air in two stages at first and then changing to single stage compression. The second set of cylinders are operated in the engine mode when maximum power is required, in the compressor mode to absorb power when the engine is slowing down, the compressed air being stored, or in the compressor mode with the air being used to supercharge the first set of cylinders, either directly or after the air has been expanded in a compressed air machine, such as one providing a cooling action. When the first set of cylinders is idling, the second set of cylinders operate in the No-load mode. The combination is arranged so that the functions of the sets of cylinders can be interchanged at intervals of e.g. 4,000 km. The cylinders can also be operated as air-motors either for starting the set of cylinders operating in the engine mode, or to improve acceleration by supplying compressed air to the cylinders operating in the compressor mode. In a further embodiment, Fig. 13, a residual air valve 83 is provided for exhausting high-pressure air remaining in the cylinder at the end of a compression stroke. The valve is also used to supply compressed air to the cylinders to produce either normal or reverse rotation of the engine. The port 82 controlled by valve 83 is connected to manifold 84 which has a branch 85 leading to atmosphere or a supercharger and a branch 86 connected to highpressure tank containing air at 20-50 kg/sq.cm. An electromagnetically controlled valve 89 controls the direction of flow. Valve 83 is operated by an axially displaceable cam which has (a) a cylindrical portion (92) which is associated with engine action and does not operate the valve, (b) a starting portion (93) for normal rotation as an engine and which opens the valve at about the beginning of the power stroke to admit compressed air, (c) a residual air exhaust portion (94) which acts during compressor mode operation (d) a reverse rotation starting portion (95) which opens the valve at a time corresponding to the end of the compression stroke of the engine mode of operation to admit compressed air and (e) a residual air exhaust section (96) which opens valve 83 which acts during operation in the compressor mode in reverse rotation . The axially displaceable cam for the inlet valve 31 includes (a) a section (102) which is operative during operation in the engine mode in the normal direction of rotation (b) a section (103) which is operative during compressor mode action in the normal direction of rotation (c) a section (104) for engine mode operation in the reverse direction of rotation (d) a section (105) for compressor mode operation in the reverse direction of rotation and (e) a cylindrical section (106) between sections (102) and (104). The cam for the exhaust valve 32 is similar to the inlet valve cam but arranged to produce appropriate timing of the valve. The inlet and exhaust cams are on one cam-shaft and the cam for valve 83 is on a separate cam-shaft.