Patent GB-654385-A (GB)
Title: Improvements in electrical starting systems for internal combustion engines
IPC: F02N99/00
Filed: 1947-10-31
Abstract: 654,385. Starting prime-moulds. BENDIX AVIATION CORPORATION. Oct. 31, 1947, No. 29147. Convention date, April 14, 1939. [Class 38 (iv)] In a starting arrangement for an internal combustion engine of the kind wherein a switch controlling the starting motor is closed by the action of opening the throttle and the switch is automatically opened by engine suction to disconnect the motor when the engine becomes self-running, the switch is mounted on the carburetter so as to be operable by a rotor mounted directly on the throttle shaft and means are provided which are responsive to engine suction and which prevent movement of the rotor to its switch closing position when suction is above a predetermined value. In the arrangement shown in Figs. 3-5 the shaft 32 of a throttle valve 30 projects through a carburetter wall 28 into a chamber 40 closed by a diaphragm 44 and communicating with the induction tube of the carburetter through a passage 42. The chamber houses the normallyopen contacts 62, 64 of the starting switch and a switch-actuating sleeve 50 which is on the shaft 32 and is biassed against the diaphragm by a spring 54. The last also tends to rotate the sleeve in such direction that a lug 53 on the sleeve engages a stop 55 in the housing. An L-shaped slot 70 in the sleeve and a cooperating pin 66 mounted in shaft 32 control the axial and angular movements of the sleeve necessary for the correct operation of the switch. To start the engine the throttle is opened, the pin 66 thereby moving from surface 67 of the narrow end of the slot 70 to surface 68 and rotating the sleeve to cause a lug 52 thereof to move contact 64 of the starting switch into engagement with contact 62. When the engine becomes self-running diaphragm 44 tends to move sleeve 50 to the left due to the low pressure then obtaining in chamber 40. Movement is, however, prevented by a projection 69 of the slot engaging the pin 66 so long as the throttle is maintained open so that the starting switch remains closed until such time as the operator frees the pin by returning the throttle to the idling position. The diaphragm then moves the sleeve axially so that lug 52 disengages contact 64 and so opens the starting circuit. Pin 66 now works in the longer portion of slot 70 which allows free movement of the throttle without rotation of sleeve 50. If engine suction falls with the throttle open, automatic reclosure of the starting switch is prevented by the wall 71 of the slot engaging pin 66 to arrest the axial return of sleeve 50. In a modified arrangement a separate sleeve, axially displacable by the diaphragm, controls the extent of rotation of a switch-actuating sleeve mounted on the throttle shaft and coupled thereto by a spring. Fig. 11 shows another arrangement in which a switch-actuating member 471 mounted on, and spring-coupled to, the throttle shaft 472 has an extension 475 which is engaged by a suction-operated stop 477 to prevent closure of the switch contacts 463 when the throttle is open and the engine is producing within a common container 440 a predetermined degree of vacuum. In another construction, Figs. 8-10 (not shown), the switch comprises fixed brushes and a drum splined to the throttle shaft so as to be axially movable in response to engine suction, the drum consisting conducting and insulating portions and being provided with cam surfaces all of which co-operate with the brushes to control the switch in the manner desired.