Patent GB-601381-A (GB)
Title: Improvements in or relating to control apparatus for internal combustion engines
IPC: F02D1/08
Filed: 1944-09-13
Abstract: 601,381. Automatic control of internalcombustion engines. MINNEAPOLIS HONEYWELL REGULATOR CO. Sept. 13. 1944, No. 17538. Convention date, Feb. 1, 1943. [Class 38 (iv)] [Also in Group XXVII] An automatic system for controlling the pressure of the air supplied by a compresser to the intake manifold of an internal combustion engine is provided with means operated by a motor or motors for controlling the compression ratio of the compressor, the motor or motors being controlled by devices responsive respectively to the pressure of the air supplied by the compressor and the pressure in the exhaust manifold of the engine. The speed of the compressor may also introduce a controlling factor. The system is adapted for aircraft and may embody an ice responsive device such as that described in Specification 575,257, [Group XXXIII], which operates to increase the temperature of the air supplied to the carburetter by increasing the compression ratio of the compressor. In addition, the carburetter may contain a temperature responsive means which operates on a predetermined drop in temperature. A compresser supercharger 12, such as a fan, driven by a turbine 13 operated by the exhaust gases drives air through an after cooler 15 and carburetter 17 from whence the air, mixed with fuel, passes through an adjustable throttle 20, intake manifold 21, and direct driven compressor 23 to the engine 10. Exhaust gases from the exhaust manifold 28 pass either through an outlet pipe 30 provided with a controlled waste gate 31 or through a pipe 32 feeding the turbine 13. The throttle 20 is operated by a reversible D.C. series motor 34 through a gear train 35 and bevel wheels 36, the gear train also being connected to drive the slider 38 of a throttle follow-up potentiometer 40. The waste gate 31 is controlled similarly by a reversible D.C. series motor 44 and gear train 45 which also operates the slider 47 of a waste gate follow-up potentiometer 48. The relative amounts of opening of the throttle 20 and waste-gate 31 determine the compression ratio of the compressor 12. The motors 34, 44 are controlled in response to deviations in a Wheatstone bridge circuit to which current is supplied by the secondary winding of a transformer 115 connected across points 110, 111, the upper arms of the bridge comprising a principal potentiometer resistance 132 with a contact arm 133, while the lower arms comprise the pair of potentiometer resistances 40, 48 with contact arms 38, 47 arranged to be connected alternately to one terminal 73 of an electromagnetic amplifier which may be of the type described in Specification 6642/43 as open to inspection under Sect. 91. The other terminal 74 of the amplifier is connected over a line 137 to the contact arm 133 of the potentiometer resistance 132. The position of the arm 133 is controlled in accordance with the pressure in the intake manifold 21 and responds to a bellows 153 connected to the manifold by a pipe 154. Other variable resistances which may be introduced in series with the portion of resistance 132 in the top left hand arm of the bridge comprise resistance 130 with a contact arm 128 operated in accordance with the pressure in the exhaust manifold 28, resistance 125 controlled by a turbine speed governor 166, a master resistance 122 with a contact arm 121 controlled manually by a pilot or other operator, and a resistance 171 which can be inserted either manually or by an ice-responsive device 174 operating a switch 168., Changes in the variables enumerated produce corresponding A.C. signals at the amplifier terminals 73, 74, the phase of the signals being dependent on the direction of unbalance of the Wheatstone bridge. The amplifier 53 comprises a pair of relays 65, 66 which are energized selectively in accordance with the phase of the signal received and co-operate with a cyclic switching device comprising four semi-circular cams 55-58 on a continuously rotating shaft driven by a motor 54 and arranged to operate rocking arms 80, 83, 86, and 90 respectively. Arm 80 rocks between a contact 81 connected to field winding 51 of the waste gate motor 44, and a contact 82 connected to field winding 42 of the throttle motor 34, while arm 83 rocks between contacts 84, 85 respectively connected to the field windings 52, 43 of the two motors. Rocking-arm 86 operates between contacts 87, 88 and connects the potentiometer arms 47, 38 alternately to the amplifier 53. Energization of throttle motor field winding 42 operates the motor in the throttle closing direction, and energization of field winding 43 operates it in the closing direction. Similarly the waste gate is moved towards closure when field winding 52 of motor 44 is energized, and opened when winding 51 is energized. Balance is restored to the bridge by the follow-up movement imparted to the relative potentiometer arms 37, 47 driven through the gear trains 35, 45. In a modification,- Fig. 2 (not shown), separate amplifiers are provided for throttle and waste gate control, and the carburetter encloses a temperature responsive resistance connected in a Wheatstone bridge circuit associated with the throttle control amplifier and arranged so that when the carburetter air temperature is below a certain temperature it introduces into the throttle amplifier a signal which causes the energization of the circuit operating the throttle towards closed position. In a further modification, Fig. 3 (not shown), the throttle is operated manually and the pressure within the carburetter is compared with that in the exhaust manifold by a bellows device connected to the carburetter, the exhaust manifold being also provided with bellows similar to those shown in Fig. 1. In this case one motor only is provided, controlling the waste gate, which has alternative manual and automatic relayoperated control.