Patent GB-852301-A (GB)
Title: Improvements in or relating to a starter for a prime mover
Inventor: EMERSON REGINALD STANLEY
IPC: F02N5/02
Filed: 1958-05-06
Abstract: 852,301. Spring starters. BRYCE BERGER Ltd. April 10, 1959 [May 6, 1958], No. 14405/58. Class 7(5). A starter for a prime mover embodies an elastic energy storing member, a shaft driven by the prime mover for straining the elastic member, means for restraining and releasing the elastic member, driving means associated with the elastic energy storing member for transmitting energy to the prime mover and governing means for controlling the rate at which energy is transmitted from the elastic energy storing member to the prime mover. In operation the torsion springs 6 may be wound manually. In order to do this the dog 9 is moved so that its projection 19 is not in engagement with the lever 17, a handle 63 having serrations formed thereon is then inserted into a serrated bore formed in the dog 9 and when this handle is turned in the appropriate direction it winds the springs. The servo action of the clutch member 16 permits rotation of the arbor 4 with respect to the drum 5 in the spring winding direction but not in the other. The drum in turn is prevented from reverse rotation by gear train 21, 22, 24, 25, 27 and 28, pawls 42, brake drum 41 and brake band 43. When the springs have been fully wound the dog 9 is moved back into engagement with the lever 17. This action automatically ejects the handle 63. When it is desired to start a prime mover with which the starter is associated the handle 49 is turned clockwise. Approximately the first half of the permissible travel of the handle 49 causes the rocker 51 to be rocked, the rod 37 to be depressed and the dogs 34 formed on the gear wheel 35 to disengage the thrust faces of the centrifugal weights 30. This part of the movement of the handle also causes the pressure on the spring 46 to be relaxed. The second half of the handle's travel causes the fixed pin 44 on the disc 45 to move within the slot and to expand the brake band 43 and so release the brake drum 41 and with it the gear-wheel 28. Upon release of the gear-wheel 28 the governor comes into action. The gear tram represents a considerable step-up ratio to the flyweights 30 and therefore both the pinion 28 and the flyweights accelerate rapidly as the torsion springs 6 unwind slowly. The friction caused by the flyweights as they rub against drum 28 is approximately proportional to the second power of the speed of rotation of the arbor 4 and the arbor 4 therefore rotates at a slow even speed. Rotation of the arbor causes drive to be transmitted to the layshaft 7 and rotation of the layshaft causes the splines 8 formed thereon to drive the starter pinion 11 into engagement with the gear ring 12 associated with the prime mover. When the pinion 11 engages a shoulder 64 formed on the layshaft because of the freedom of angular movement between the layshaft 11 and the arbor 4 allowed by the dogs 9 and 10 the speed of rotation of the layshaft will be retarded by the friction of the prime mover whilst the arbor 4 will continue to rotate at a slow even speed. This differential rotation between the arbor and the layshaft will cause the projection of the dog 9 to engage the lever 17 which will in turn cause the lever 18 to engage the projection 20 formed on the clutch member 16 and cause the latter to contract and cease to transmit drive to the drum 5. Rotation of the arbor 4 is now unhindered by the governor and the torsion springs are therefore able to transmit their full torque and rapidly to spin the prime mover. When the energy of the torsion springs is spent the torque transmitted between the faces of the dogs 9 and 10 is relaxed and the lever 18 is therefore able to permit the clutch member 16 to expand again and engage the drum 5 thus bringing the arbor 4 to rest rapidly. In the meantime the governor will already have come to rest or nearly so because of its high torsional resistance and low inertia. When the prime mover is running it drives the spindle 39 via the flexible drive cable 40. The gear-wheel 35 will be driven by the pinion 38 and the dogs 34 caused to rotate. When the dogs 34 reach a suitable angular relationship with the flyweights 30 the spring 36 will displace the gear-wheel 35 axially until shoulder 65 formed thereon engages the flyweights 30. The inwardly spring loaded flyweights 30 will then be engaged by the rotating dogs 34 and these will cause the governor carrier 29 to rotate and thereby cause the members of the gear train 28, 27, 24, 22 and 21 to rotate also. This rotational movement of the members of the gear train will be transmitted to the arbor 4 and the torsion springs 6 will be wound. When fully wound the torsional resistance of the springs 6 suddenly increases. At a suitable and predetermined torsional value the geometry of the faces of the dogs 34 on the gear-wheel 35 is so arranged to develop a sufficiently large outward thrust to overcome the springs biasing the flyweights 30. When this happens, continuity of the drive is lost but the pawls 42 prevent the torsion springs 6 unwinding again. Moreover the shoulders 65 will lose contact with the flyweights 30 and when this happens the springs 36 will move the gearwheel 35 until a shoulder 66 provided thereon abuts the flyweights 30 a spigot 67 adjacent to the shoulders 64 then prevents the dogs 34 reengaging the flyweights 30 each time they come round. The starter is now fully wound and ready to start the prime mover once more. The starter can be adapted to "inch" the prime mover slowly or in small increments. If desired the flexible drive cable 40 may be connected to the fuel injection pump cam-shaft instead of to the tachometer point. A spindle driven by the arbor may comprise a projection engaging directly with the crank-shaft of the prime mover.