Patent GB-516127-A (GB)
Title: Improvements in or relating to electric starting arrangements for internal combustion engines
Filed: 1938-06-21
Abstract: 516,127. Starting prime movers. BOSCH GES., R., (formerly BOSCH AKT.-GES., R.). June 21, 1938, Nos. 18323 and 18324. Convention dates, June 21, 1937 and Jan. 20, 1938, [Class 38 (iv)] [Also in Group XXXVII] Relates to electric starting arrangements for vehicle and other internal combustion engines of the type incorporating a switch for the starting motor of the engine and an automatic safety device which after the starting motor has been switched off prevents its premature switching on again. The safety device constitutes a time switch incorporated in and energised by the starter gear manual switch, to introduce a time lag in the re-closing of the starter circuit immediately following an unsuccessful attempt to start the. engine, during which time lag the starter gear is brought to rest and the starter circuit remains open in spite of any operation of the manual starter switch. The pressing down of the switch spindle 6, Fig. 1, brings together by means of an entraining element 21, contacts 16, 17 of contact springs 13, 14 to complete through a third and lower contact spring 15 a battery circuit including the existing coil 27 of an electro-magnetic switch 29 for closing the circuit of the starting motor 1. The contact spring 15 has a preliminary tension to bear it downwardly though normally maintained as shown by an entraining element 22 on the spindle 6 until this is depressed and allows the spring 15 to move slightly down to be arrested by a pawl 23 on a bi-metal spring 24, heated by a coil 25 which is in the starter gear circuit and is energised by the current for closing the electro-magnetic switch 29. The heated bi-metal spring bends so that spring 15 is released from pawl 23 and moves down to separate its contact from contact 17 and so cut out the heating coil 25 and cut in a weaker heating coil 26 and a resistance winding 28 into the circuit of the electro-magnetic switch 29 so that the latter is maintained closed by the weakened current thus produced and the temperature of the bi-metal spring 24 kept raised to retain the pawl 23 in position out of the path of spring 15. If after failure to start the engine the spindle 6 is allowed to rise and is then depressed before the spring 24 cools and straightens, the circuit for closing the electro-magnetic switch is not completed, the weaker current which flows in the circuit including the resistance 28 not being requisite to close the electro-magnetic switch 29. The first part of the movement of the spindle 6 closes by means of a bridge 8 a battery circuit for heating incandescent plugs 3 for warming the internal combustion engine cylinders. In a modified construction of the same kind the heating of the spring 24 is switched on and off intermittently by the movements of the spring. Another form of switch, shown in plan in Fig. 4, comprises a rotatable operating spindle 33 carrying an arm 35 with a nose-piece 34, with engages in a notch 41 of a bell-crank lever 39 carried by a rotatable arm 37. Operation of the switch causes rotation of the arm 37 by pressure of the nose-piece on the lever 39, which turns about its pivot 38 and after sufficient rotation of the arm 37 presses contact 42 against contact 43 to switch on the starter. The rotation of the arm 37 winds up a clock-work mechanism so that when the switchoperating arm is released the arm 37 only returns after a time lag to a position allowing of operation by the arm 35. When the switch is released by the operator, immediate separation of the contacts 42, 43 occurs owing to the return rotation of the lever 39 on cessation of the pressure of the arm 35. An air or fluid piston brake may be used in place of the clockwork mechanism.