Patent GB-623732-A (GB)
Title: Control mechanism for supercharged internal combustion engines
IPC: F02D9/00
Filed: 1946-03-27
Abstract: 623,732. Fluid-pressure servomotor-control systems. GENERAL MOTORS CORPORATION. March 27, 1946, No. 9480. Convention date, April 11, 1945. [Class 135] A control mechanism for a supercharged internalcombustion engine by which the throttle valve position is determined by manual selection and by intake pressure operating jointly through a servomotor, comprises a manually operable device, e.g. movable in accordance with supercharger speed ratio changes, for modifying the selected engine intake pressure and for limiting the pressure obtainable, and a pressureresponsive device actuated by injection liquid under pressure for rendering the pressure limitation inoperative. As shown, anticlockwise movement imparted manually to the lever 54, Fig. 5, turns the lever 60 to which is pivoted a lever having an arm 61 connected through a cam slot, roller and link to a servomotor piston rod 69, Fig. 6, and an arm 62 for opening the throttle valve, and also turns a pressure selecting cam 84 through a lever 80, link 81 and lever 82. The sprmgloaded lever 87 follows the cam and shifts the piston valve 113 to the right to allow pressure oil to enter the cylinder 130 through the passage 143 and leave by the passage 145 and through the valve guide 116 to the chamber 150 and a drain 166a, Fig. 2, so that the piston moves to the left and opens the throttle still more to give the selected engine intake pressure. The lever 87 is pivoted at 88 to the bridge 89 connecting the ends of the evacuated bellows 105 and the bellows 92, the interior of which is subject to the intake pressure, so that as the atmospheric pressure falls, the bellows system moves the pivot 88 to move the piston valve 113 to the right so as to open the throttle and maintain the selected pressure. The springs 107, 108 and 97 ensure that the relation between the movement of the pin 88 and the changes in intake pressure are substantially linear. The shaft 83 carrying the cam 84 is journalled eccentrically in a shaft 180 having an arm 183, Fig. 3, which is mounted concentrically in a sleeve 181 having an arm 187, the arms heing connected by a spring 185 so that an extension 183a of the arm 183 abuts a bent out portion 187a of the arm 187. Under normal conditions, the arms move as one, and the arm 187 is connected to the manual control mechanism of a gear-box between the engine and a supercharger, and through a link 201 to a lever 203 mounted on a shaft 204 carrying an eccentric pin 208, Fig. 6. Mounted on the pin is a lever 211, one end of which abuts the end of a spring- loaded rod 231 for preventing the lever 87 from following the cam 84 under certain conditions, while the other end is connected to a spring- loaded diaphragm 218 exposed on one side to injection liquid pressure via pipe 227, and on the other side to the intake pressure of the supercharger via pipe 229. When the gear ratio is increased, the lever 187 moves to the right and shifts the cam 84 laterally by means of the eccentric shaft 180 to a position corresponding to a lower pressure selection by the lever 54. The control system provides for bleeding the pressure between the engine intake manifold and the bellows 92 when the gear ratio is increased so that the actual pressure is above the selected value. Movement of the lever 187 to the right moves the lever 211 which shifts the rod 231 into a position so that the lever 87 cannot follow the cam 84 to give high pressures at which detonation might occur. When the liquid injection is functioning, the diaphragm 218 moves the lever 211 to allow the rod 231 to be withdrawn from the path of the lever 87 so that the high pressures may be achieved. With the supercharger in high gear, the highest pressure is selected with the cam 84 in the position corresponding to the highest pressure selection when the supercharger is in low gear, because the shaft 83 is returned to its original position by the cam 260 on the lever 82 engaging a roller 261 on the casing so that the eccentric shaft 180 turns in the sleeve 181 against the tension of the spring 185.