Patent GB-573691-A (GB)
Title: Improvements in or relating to controls for internal combustion engines
IPC: F02D29/00
Filed: 1943-04-12
Abstract: 573,691. Fluid-pressure servomotor-control systems. BENDIX AVIATION CORPORATION. April 12, 1943, No. 5874. Convention date, May 15, 1942. [Class 135] Control mechanism for internal-combustion engines includes a common member for varying the datum of charging pressure, for preselecting the operating conditions at which supercharger capacity is varied and for varying propeller pitch. The arrangement shown diagrammatically in Fig. 1, with its parts in the sealevel position with the engine idling, comprises an air inlet 10, a charge-forming device 11, a multi-speed or multi-stage supercharger 14, a throttle 18, a propeller pitch control 21, a boost control including an evacuated bellows 57, and a servomotor having a control valve 68, a supercharger shift control including an evacuated bellows 100, a servomotor 106, and a lever 15, and a pilot's control lever 33. The lever 33 is connected to a member 30 having cams 43, 44, 45 and internally toothed to engage a pinion 29 mounted on a lever 28 and meshing with a pinion 32. During the initial part of its movement, the lever 33 partially opens the throttle 18, the counterclockwise movement of the member 30 moving the pinion 29 around the pinion 32 and acting through the levers 28, 27 and link 19. The boost control is then inoperative, since the cam 44 acts through a lever 48 and fingers 50 to increase the load on a spring 52 which tends to maintain the bellows 57 extended against the action of charging pressure in a chamber 58 and simultaneously causes the servo valve 68 to move to the left into its neutral position. Additional movement of the lever 33 additionally loads the spring 52 and moves the valve 68 to the left to admit pressure tb a chamber 39 and put a chamber 40 to exhaust. A rack 36 is thus moved to the right and the throttle is opened farther until the charging pressure in the chamber 58 is sufficient to collapse the bellows 57 and return the servo valve 68 to its neutral position. Hunting action of the valve is prevented by a rod 88, the end of which is disposed between extensions of damping pistons 86, 87, working in cylinders connected to restricted outlets 89, 90. In order to allow quick initial response, the cylinders are also connected to cylinders 92, 93 having pistons operated by the lever 48. Near the end of the movement of the lever 28, its nose 81 engages a slidable stop 78, which is eventually moved to act through the valve 68 to restrict and finally cut off the pressure supply to the chamber 39. The chamber 58 is connected to the engine manifold through a restriction 59 and to the induction passage before the supercharger by a passage 61 which is closed when the supercharger is in its low step. A byepass 62 around the restriction 59 is controlled by a valve 63 carried by a capsule 64. The supercharger is put into its high step when the cam 45 through the lever 53 so loads the spring 55 that it moves the valve 103 to the right against the action of the air pressure acting on the bellows 100. This movement allows pressure liquid to pass through a passage 122 and operate a quick-acting valve 116 to cause actuation of the servomotor 106. The supercharger shift may be prevented by closing the passage 122 by a valve 123 under the pilot's control. The propeller pitch control 21 is actuated by the cam 43 and a spring- loaded stop 135 normally limits the movement of the lever 33. A constructional form is described. Specification 572,647 is referred to.