Patent GB-638741-A (GB)
Title: Improvements in regulating means for exhaust-driven superchargers of internal combustion engines
IPC: F02D9/00
Filed: 1945-08-09
Abstract: 638,741. Fluid-pressure servomotor-control systems. BENDIX AVIATION CORPORATION. Aug. 9, 1945, No. 20449. Convention date, Oct. 7, 1944. [Class 135] In regulating means for automatically controlling the output of an exhaust-driven supercharger 139 of an internal-combustion engine so as to maintain the pressure of the air supplied to the combustion chambers substantially constant over a normal altitude range, the means responsive to the air intake pressure is connected to the control valve 31 of a servomotor 16 controlling the supercharger through a linkage which includes a slotted link 200 by which the said means locks itself out of operative relation with the servomotor when a manually-adjustable control shaft 13 connected through eccentric means 13a to the linkage is adjusted to select a value of the air intake pressure below a predetermined low value. The linkage also includes two links 41, 43 and two floating levers 40, 44. Means are also provided to maintain the air intake pressure at least a minimum amount above atmospheric pressure when the latter approaches or exceeds the selected value of the air intake pressure. Further means prevent the supercharger from over-speeding. The regulating means is arranged in a casing 39, Fig. 8, and controls a waste gate 12b of a turbine 140 driving an auxiliary supercharger 139 by the gases in the engine exhaust pipe 141. The mechanism may be controlled in accordance with the carburetter air inlet 'pressure through a pipe 190, or in accordance with the auxiliary supercharger outlet pressure through a pipe 190a. The waste gate 12b is regulated by an arm 12 on a shaft 14, Fig. 4, operated by a double-acting vane type of servomotor 16 under the control of a plunger valve 31. Spring- pressed radially-sliding blades 25, 27, Fig. 5, prevent leakage between the chambers 23, 24 of the servomotor. The valve 31, Fig. 3, is operated from a shaft 49 by the linkage 43, 44, 41, 40, 46, 47. The levers 40, 44 are respectively fulcrumed on pins 13a, 14a which are eccentrically located on the ends of the respective shafts 13, 14b. The shaft 13 is adjusted by the pilot through levers 11a, 11. The shaft 14b, which may be replaced by a similar shaft having a pin of different eccentricity, is keyed at 14c to the servomotor shaft 14 which operates it. The pin 14a is so disposed on the shaft 14b that the movement of the lever 44 about a pivot 201 resulting from the movement of the servomotor 16 tends to restore the valve 31 to its neutral position after it has been displaced therefrom upon movement of the shaft 49 or of the hand-controlled shaft 13. To prevent over-control the eccentricity of the pin 14a is less than that of the pin 13a. The linkage 47, 46, 40, 41, 44, 43 with one end of the shaft 49 is disposed in a chamber 48 of the casing 39. The other end of the shaft 49 is disposed in a chamber 54 and carries an arm 53, Fig. 4, connected by a linkage comprising a floating lever 120, a link 122, a lever 123 with a fixed pivot 124 to a reciprocable member 56 carried by the head 58 of an evacuated bellows 63 prevented from collapsing by a spring 71. An unloaded flexible damping diaphragm 57 is also clamped to the head of the bellows 63 and the space 95 therebetween filled with oil. The expansion of the bellows 63 is limited by an adjustable screw 72 accessible after removal of a cap 72a. The controlling pressure in the pipe 190 or 190a'has access to the chamber 54 and acts on the diaphragm 57 which through the above-described linkages and the servomotor adjusts the waste gate 12b so as to keep the controlling pressure constant. The overspeed control and the minimum differential pressure control both control the waste gate 12b through the floating lever 120, Fig. 2. The overspeed control comprises a centrifugal governor 135 driven through shafting 137 from the auxiliary supercharger 139. A pin 134 slidable in the governor shaft 136 under the action of the fly-balls 142 contacts an arm 129 of a three-armed lever 127, 129, 130 biassed by an adjustable spring 131. The arm 127 is connected by a floating lever 126 and a link 121 to the floating lever 120. A cam 149 adjustably fixed by a clamping screw 150 limits the movement of the arm 127 under the spring 131. The minimum differential pressure control comprises a diaphragm 162 exposed to the controlling pressure in the chamber 54 through an opening 182 leading to a chamber 165 and to the pressure of the surrounding atmosphere through a port 172 in a cap member 171 which clamps the diaphragm. The diaphragm is clamped centrally to a cup-shaped member 155 on a stem 152 which is connected by a link 151 to the floating lever 126. The cup-shaped member 155 contains a biassing spring 180. When the minimum differential pressure is exceeded, an extension 152a of the stem 152 contacts the cap member 171. When the hand-controlled shaft 13 is set for a pressure below a predetermined low value, control by the bellows 63 and the diaphragm 162 are rendered inoperative by the slotted link 200 which has a pivot 201 and embraces the pivot 204 of the link 46 and the lever 40. According to the Specification as open to inspection under Sect. 91, the regulating means may be controlled in response to variations in the pressure of the engine exhaust gases in the pipe 141. This subject-matter does not appear in the Specification as accepted.