Patent GB-969591-A (GB)
Title: Air cooling system for rotary piston mechanism
IPC: F02B55/06
Filed: 1962-05-07
Abstract: 969,591. Rotary piston machines. CURTISS-WRIGHT CORPORATION. May 7, 1962 [June 6, 1961], No. 17527/62. Heading F1F. A rotary piston I.C. engine comprising a housing 12, Fig. 1, having a peripheral wall 2 with a two-lobe epitrochoidal inner profile 18 and axially-spaced end walls 22, 24, Fig. 2, and a three-lobe rotor 10 eccentrically mounted on an output piston or shaft 26, and, whose apices 38 slidably mount seals 40 extending the full width of the rotor, includes adjacent each of the rotor apices a group of cooling passages 54 through which a gaseous cooling medium may be passed under pressure. The inlet ends of each group open into an inlet manifold 72 which communicates with a cooling gas inlet port 68 whilst the outlet ends thereof open into a series of cooling gas outlet ports 70. The end wall 22 is formed with two cooling gas supply ports 64 and the end wall 24 similarly with two cooling gas exhaust ports 66. In one embodiment, Fig. 1, the end wall 22 is formed with an intake port 48 through which a gaseous air-fuel mixture is admitted to the working chambers 42 of the engine and the end wall 24 with an exhaust port 50 through which spent gases are expelled. A spark-plug 46 is fitted diametrically opposite the ports 48, 50 in the peripheral wall 20. In the case of a Diesel engine fuel is injected at the spark-plug location and air only is admitted through the intake port 48. In another embodiment, Fig. 6 (not shown) the intake and exhaust ports pass through the peripheral wall 20 instead of the end walls 22, 24. An oil seal ring 82 fitted on each side rotor face prevents the leakage of lubricating oil from the engine bearings and gears, and gas seals 86 fitted on each rotor side face adjacent to and following the profile of the rotor 10 prevents leakage of combustible gas from the working chambers 42. The shape, size and location of each port 64, 66 is determined by the location of the oil seals 82 and the gas seals 86 and by a factor K which is the distance R of an apex 38 from the axis 14 of the rotor divided by the eccentricity e of this axis with respect to the axis 16 of the housing and the output shaft 26. The criteria is that the ports 64, 66 must at all times be completely isolated from the working chambers and the lubricated engine spaces. This criteria is fulfilled by the substantially triangular-shaped ports adjacent the ends of the minor axis 58 of the inner profile 18 shown in Fig. 1. The ports shown in Fig. 1 correspond to a K factor equal to 6. If this factor is increased the ports are increased in area and extend a greater distance on either side of the ends of the minor axis 58. With an engine having the intake port 48 through the end wall 22 it is also necessary on rotation of the rotor 10, for the ports 68 to be of such a size and shape that they can register with the ports 64 but at all times be isolated from the intake port 48. A port of the shape illustrated in Fig. 1 satisfies these requirements. To improve the flow of gaseous cooling medium through the rotor, pipes 122, Fig. 7, may be fitted connecting the cooling gas exhaust ports 66<SP>1</SP> with an exhaust port 114 (replacing the exhaust port 50). The cooling medium is then drawn through the rotor by the spent gases exhausting from the engine. The invention is not limited to a rotary piston I.C. engine but may be applied to any rotary piston machine in which it is required to cool the rotor. Also, although a two-lobed housing and a three-lobed rotor are shown, the invention may be applied to any n and n+ 1 lobe type of rotary piston machine in which the rotor has the greater number of lobes. The passages 54 and the rotor being made of aluminium alloy reduces the weight of the rotor and due to the location of the passages also the moment of inertia of the rotor.