Patent GB-656684-A (GB)
Title: Improvements in or relating to engine starters
IPC: F02N7/08
Filed: 1948-10-01
Abstract: 656,684. Turning-gear. BENDIX AVIATION CORPORATION. Oct. 1, 1948, No. 25687. Convention date, Nov. 13, 1947. [Class 7(v)] [Also in Group XXVI] In an engine starting mechanism comprising in combination a rotatable member 10, Fig. 1, adapted for axial movement into and out of engagement with an element 12 of an engine to be started, an axially stationary rotative nut 14, driving means, such as sun and planet gears 62, 64, respectively, for rotating the nut, a screw shaft 20 axially movable relative to and rotatively movable by the nut and associated with the rotatable member 10 for rotating the latter, a meshing rod 22 adapted to move the rotatable member to engage the engine element 12 against the action of spring means 26, a first power means, such as an electrically driven gear pump 76, to effect the latter movement of the meshing rod 22, and a second independent power means, for example, a turbine 44, to effect rotation of the nut 14 through the driving means 62, 64, there is provided control means, such as a valve 80, operated by the pressure from pump 76 for initiating operation of the turbine 44 and the rotative action of the rotatable member 10 by the driving means 62, 64 following initiation of the axial movement of the rotatable member 10 by the pump 76 so that the latter and the turbine 44 coact to complete meshing of the rotatable member 10 with the engine element 12. The nut 14 which rotates the member 10 has a flange 68 supporting planet gears 64, the latter meshing with a sun gear 62, and the toothed discs of an adjustable multi-plate clutch 66, the alternate discs being located in the starter housing 38. The sun gear 62 is joined to a stub shaft 56, both of which are hollow and surround the rod 22, the shaft 56 being attached to a disc 54 in turn secured to the turbine rotor 44 that is rotatably mounted upon a cylinder 48. The rod 22 extends into the cylinder 48 and has a piston 50 attached thereto, whilst the spring 26 around the rod is contained between one end of the cylinder and the piston. In operation, hydrogen peroxide is forced by the gear pump 76 into the cylinder 48 and commences to move the piston 50 and hence member 10, the piston uncovers the reduced part 82 of a slot in the cylinder and admits the hydrogen peroxide into a chamber 40 provided with nozzles 42 that contains a catalyst. Sufficient steam pressure is generated to rotate the turbine slowly until the piston uncovers the enlarged part 84 of the slot. The member 10 is arranged to engage the engine element 12 before the turbine attains a predetermined speed so that in the event of abutment of member 10 and element 12 the former can be turned and meshed under the continued thrust of piston 50; compressed air or other gas may be substituted for the hydrogen peroxide and catalyst. The member 10 may be of the splined, toothed or jaw-clutch type. In a modification the turbine is replaced by an electric motor and the meshing of the engine engaging member is effected by a solenoid 129, Fig. 3, which comprises a coil 130 surrounding a hollow armature core 132 that carries a plunger 134 normally biassed against a seat 138 by a spring 32. The core 132 carries a bridge contact 143 for stationary contacts 144 connected in the circuit of the electric motor. When the coil 130 is energized the core 132 descends and the plunger acts through a lever 124 to move the mesh rod 22A rightwardly, and if the engine and starter member engage immediately the relative position of the plunger 134 and core 132 remains unchanged, the motor being started when contacts 143 and 144 complete the motor circuit. If abutment of the rotatable member and engine element occurs, then the downward movement of plunger 134 ceases, whilst that of core 132 continues until the " making " of contacts 143 and 144 starts the motor, whereupon the engine and starter member will index, the spring 32 completing the meshing operations before the motor has attained a predetermined speed. In another modification, the axially stationary nut 14B, Fig. 5, imparts rotation to a screwshaft 20B, which is splined to the jaw member 10B, the meshing movement of the jaw member being effected by the screwshaft 20B through a spring 190, the screwshaft acting as a piston within the nut 14B. When a switch 92B is closed a solenoid switch 130B, similar to that of Fig. 3, is energized, the plunger 134B of which, acting as a valve, permits fluid, such as compressed air, to flow from a source 214 into a chamber 164 and force the screwshaft 20B leftwardly, hence moving jaw member 10B into mesh with an engine part (not shown) to effect slow rotation of the screwshaft. Closure of contacts 34B on the solenoid core causes energization of either an electric motor or turbine starting switch 220 to bring about rotation of a disc 150 and so through a barrel 174, a clutch 178, nut 14B and screwshaft 20B to impart rotation to the member 10B. If abutment of member 10B and the engine element should occur, indexing will be completed upon first application of rotative driving power before a predetermined speed has been attained. The power may. however, be applied upon or at any time before or after the engagement of member 10B.