Patent GB-495307-A (GB)
Title: Improvements in or relating to boost controls for internal combustion engines
IPC: F02D29/04
Filed: 1937-02-10
Abstract: 495,307. Fluid - pressure servomotor control systems. SOC. GENERALE DES CARBURATEURS ZENITH. Feb. 10, 1937, Nos. 4018, 4019, and 4020. Convention dates, Feb. 11, 1936, April 21, 1936, and May 22, 1936. [Class 135] In a variable datum boost control for internal-combustion engines which has a relay the power member of which controls a device for regulating the quantity of air or mixture admitted to the engine, disposed in the intake manifold, and which is responsive to the induction pressure posterior to the said device the power member of the relay is connected to the device for varying the datum of the boost control. The device for regulating the quantity of air or mixture admitted to the engine may be a throttle valve or a supercharger driven at a variable speed. In the case of the throttle valve 4, Fig. 1, controlled jointly by the relay device in Fig. 2, and by a hand lever 5 by the linkage shown or alternatively by the means described in Specification 291,152, [Class 7 (vi)], or 356,619,[Group XXVII], the movement of the power member 29 of the relay device 7 in a direction to open the throttle 4 may be arranged to operate the device for varying the datum of the boost control so as to bring about a reduction in the rated induction pressure. In this way the throttle 4 is given a definite closing movement when the pilot's lever 5 is moved in the closing direction and is not merely re-opened by the power member to the same extent as the closing movement. The further desirable characteristic is also obtained that the maximum rated induction pressure decreases as the altitude increases. The intake manifold 1, Fig. 1, is fed by a supercharger 2 with combustible mixture from a carburetter 3. The throttle valve 4 is controlled by a floating lever 9 also connected to the power member 29 of the relay device and to the pilot's lever 5. The relay device 7 comprises a bellows or capsule 21 arranged in a chamber 19 connected by a pipe 20 to a point on the delivery side of the supercharger 2. One end of the capsule 21 is initially adjusted by means of a screwed spindle 23 and its other end is operatively connected to a pilot valve 34, the central collar 41 of which is less than the width of the orifice 32 leading to the power cylinder 28. The spring-biassed power piston 29 is connected by a rod 6 to the floating lever 9. The rod 6 is connected by a bell-crank 43 to a forked floating lever 46 engaging studs 47, 48 on the pilot valve 34 and capsule spindle 26 respectively. When the lever 5 is moved away from a stop 18, the lever 9 moves clockwise about its pivot 16 and the valve 4 tends to close. The pressure in the manifold 1 and the chamber 19 however then falls so that the capsule 21 expands moving the valve 34 to vent the chamber 28. The piston 29 then ascends so as to re-open the valve 4. The same movement however causes the lever 46 to shorten the effective connection between the capsule 21 and the valve 34 so that the former must now have a length l<1> greater than its original length l to retain the valve 34 in its neutral position. The induction pressure necessary to maintain the capsule at this length l<1> is less than the original rated pressure and hence the valve 4 re-opens only to the extent necessary to produce this reduced induction pressure. After the piston 29 reaches the limit of its travel, the throttle 4 is controlled entirely by the lever 5. Moreover, with the lever 5 against the stop 18, the capsule expands as the altitude increases and the movement of the piston 29 likewise causes the maximum permissible induction pressure to decrease as the altitude increases. The supercharger may be eliminated or located on the inlet side of the throttle 4. The relay device may utilize the engine lubricating oil as its working fluid, as described on Specification 306,587, [Class 7 (vi)], or the delivery pressure of the supercharger as described in Specification 346,503, [Group XXVII]. Alternatively the relay device may be of the electrical type, involving an electric motor and a control switch, such as that described in Specification 369,459. Figs. 3, 5, and 6 show other devices for varying the datum of the boost control actuated by the power member 29. In Fig. 3, the collar 41, is replaced by a spiral portion 50 the valve 34 itself being capable of rotational as well as axial movement and pressed against the capsule 21 by a spring 52. A shaft 53 carrying a crank arm 56 is non- rotatably connected to the valve 34. On upward movement of the piston 29, the arm 56 is turned by the connection 43, 57 so that the spiral part 50 no longer occupies the neutral position. Alternatively the rotary movement may be effected by the capsule and the axial movement by the power piston 29. In Fig. 5, the datum is varied by adjusting the load of an enclosed spring 70 acting on the capsule 21 through a lever 67 and the valve 34. This adjustment is effected by a lever 43 movable by the rod 6 and carrying a roller 78 which acts on the abutment 74 of the loading spring. In this arrangement also the rated induction pressure falls as the power member 29 moves in a direction to open the throttle valve 4. In Fig. 6, the datum is varied by alteration of the fluid pressure load effective on the valve 34 and hence through the lever connection 79 on the capsule 21. The left-hand end of the valve 34 is exposed to the fluid pressure in a chamber 80 communicating with the oil exhaust conduit 38 by a calibrated orifice 82 and with the cylinder 28 through a series of orifices or a slot 83 controlled by the power piston 29 so that the pressure falls in the chamber 80 as the piston ascends. In another form, the valve 34 is formed integrally with the spindle 26 at one end of the capsule the datum of which is varied by adjustment of a spindle at its opposite end by levers connected to the piston 29. In Fig. 8, the chamber 19 has conduits 8, 20 leading respectively to the inlet and outlet sides of a supercharger arranged as shown in Fig. 1. These conduits have calibrated orifices 87, 84 respectively, the former being controlled by a tapered valve 88 connected to the piston 29 so as to reduce the orifice 87 as the piston 29 ascends to open the throttle. The pressure in the chamber 19 is dependent upon the induction pipe pressure. The increased opening of the throttle 4 and the consequent reduction of the orifice 87 both tend to increase the pressure in the chamber 19 and so restore the valve 34 to its neutral position in which the pressure in the chamber 19 resumes its original value. The induction pipe pressure is then at its new rated value which is less than its original rated value, due to the adjustment of the valve 88 and the throttle valve 4. When the pilot's lever is moved in the throttle closing direction, the effect is the same as in the embodiments already described, whilst the rated induction pressure decreases as the altitude increases. The valve 88 may alternatively be arranged to control the orifice 84. If the supercharger is eliminated or located in the inlet of the. throttle, the pipe 86 opens respectively to the atmosphere or in the throttle valve inlet. As the pressure in the chamber 19 is less than that on the inlet side of the throttle valve, the valve 88 must be tapered in the reverse direction to produce the same control effect. Fig. 9 shows an arrangement with two independent throttle valves 150, 151 both located on the inlet side of the supercharger 2 one 150 being operated by the pilot's lever 5, and the other 151 being automatically controlled by one of the boost control devices, 7 already described, for instance that shown in Fig. 2. As in the Fig. 1 construction, progressive regulation of the air or mixture input is obtained by the lever 5 since as the throttle 150 is closed, the throttle 151 opens and the rated induction pressure is reduced by the boost control device. With the lever 5 in the fully open position shown, the maxmum permissible induction pressure, as before, decreases with increasing altitude. The supercharger may be eliminated or located between the valves 150, 151 or the valve 151 may be located on the inlet side of the valve 150, but in every case the pipe 20 opens on the engine side of both valves 150, 151. In another form which functions in the same manner as that in Fig. 9, the quantity of air or mixture admitted to the engine is controlled by regulating the speed of the supercharger. The throttle 151 is in this case dispensed with and the power member of the boost control device is connected to a member which changes the gear ratio of a known type of variable speed gear involving one or more friction rollers between discs with channels of semicircular cross section one of the discs being driven by the engine and the other connected to the supercharger. In another form, a throttle valve operated independently by the pilot is located in the intake manifold on the delivery side of another throttle valve operated by the variable datum boost control device, and a supercharger, when used, is located between the throttle or on the inlet side of the automatically controlled throttle valve. In these arrangements, progressive regulation of the air or mixture input would be attained whatever the form of the boost control and hence the variable datum type according to the invention is utilized purely to obtain a variation in the maximum permissible induction pressure as the altitude changes. The power member of the boost control device may alternatively control the change speed gear of the supercharger or any other device for regulating the air or mixture input of the engine. The bell-crank 43, Fig. 2, and the lever 46 may be arranged as shown in Fig. 13, to increase the effective distance between the pilot valve and the capsule as the piston 29 ascends so that the datum of the boost control is varied so as to increase the maximum permissible induction pressure as the alt