GB607596A - Improvements in or relating to means for regulating internal combustion engines - Google Patents

Abstract

607,596. Fluid-pressure servomotor-control systems. BRISTOL AEROPLANE CO., Ltd., WARNER, S. C., and HENLY, A. G. March 16, 1945, No. 6737. [Class 135] [Also in Group XXVII] In automatic control mechanism for regulating the quantity of fuel supplied to an internalcombustion engine of the fuel injection type in accordance with changes in one or more engine variables, a coupling is provided in the linkage between the automatic control unit and fuel pump regulator and control means are provided for the coupling which in one position permit automatic regulation by the automatic control unit and which in another position permit the quantity of fuel to be increased beyond that demanded by the automatic control unit. As shown in Fig. 1, the engine fuel-injection pumps 32 are automatically regulated through a linkage 28, 29, 30, 31 by a vane type hydraulic servomotor 26 under the control of a valve 20 having inclined passages 21 and capable of axially motion due to movements in the stacks of capsules 12, 13 and of rotational movement by a pinion 19. The latter is operated through a lever 15 and a rack 17 by an element 11 responsive to temperature changes in the air delivered by the supercharger. The capsules 12, 13 are responsive to the engine boost pressure and the exhaust gas pressure respectively. The datum of the regulator is adjusted by a cam 33 operating on the element 11 and controlled by a link 10 from a cockpit lever. Figs. 2A, 2B show the coupling means 34 between the arms 30, 31 of the linkage. This comprises two hollow shafts 35, 36 journalled in a body member 38, a clutch member 37 and a clutch-actuating rod 42. The latter is connected by a linkage 55 with a lever in the cockpit which can be set to three positions corresponding to starting, stopping and normal running of the engine, the latter being intermediate the other two positions. The shaft 35 is connected by the arm 30 to the automatic regulating unit in Fig. 1, whilst the shaft 36 is connected by the arm 31 to the fuel pump adjusting means. The shaft 36 is biassed to a position of minimum'fuel delivery by a torsion spring 46, such movement being limited by teeth 45 inside the shaft engaging helical splines 44 on the rod 42. Rotation of the rod 42 is prevented by a pin 48 engaging a groove 47 therein. The clutch member 37 is urged against a collar 43 by a spring 40 having an abutment 41 within the pump shaft 36. The clutch member 37 has three equi-spaced dogs 54, Figs. 4, 5, which can engage corresponding sets of grooves 50, 53 in the shafts 35, 36 respectively. The shaft 36 also has another set of grooves 51, the width of which is equal to the distance apart of the grooves 50 or 53. The grooves 51 are separated by dogs 52 and one side of each of these is coplanar with one side of the corresponding groove 53, Fig. 6. Figs. 2A, 2B show the position for normal running under the automatic control of the fuel control unit, Fig. 1. If the linkage 55 is moved to the stop position, the rod 42 is moved to the right and after the clutch dogs 54 have been withdrawn from the grooves 50, the torsion spring 46 rotates the pump shaft 36 to the minimum delivery position, this being possible because splines 44 which are narrower than the distance between the teeth 45 have been moved away from the latter in the first part of the withdrawing movement of the rod 42. To restart the engine, the linkage 55 is moved through the normal or automatic position to the start position. At first the dogs 54 cannot engage the grooves 50 as these are out of phase. The splines 44, however, gradually advance the shaft 36 and hence the dogs 54, since the clutch member 37 and the shaft 36 are in engagement through grooves 53, until in the normal position, the dogs 54 engage the grooves 50 and leave grooves 53. Further movement of the rod 42 to the left causes the splines 44 to advance the shaft 36 still further. The arm 31 therefore increases the fuel supply for starting beyond what the fuel control unit calls for. This further advance of the shaft 36 is possible because the dogs 52 are free to move between the dogs 54. When the engine is started the linkage 55 is returned to the central or normal position in which the dogs 52, 54 engage one another as shown in Fig. 5.