Patent GB-692114-A (GB)
Title: Improvements in and relating to control means for clutches in motor vehicles
IPC: F16H63/46
Filed: 1951-01-05
Abstract: 692,114. Operating clutches. PRACHAR, C. Jan. 5, 1951 [Jan. 6, 1950; Dec. 16, 1950], No. 437/51. Class 80 (ii). [Also in Groups XXIX, XXXI and XXXII] Control means for the clutch in a motor vehicle comprises power actuated means for disengaging the clutch, means associated either with the change speed gear control or with the brake applying member and operated by the driver manipulating either the control or member for causing actuation of the means for disengaging the clutch, means for retaining or locking the clutch in its disengaged position independently of the power actuated means, and means dependent upon operation by the driver of the accelerator pedal or throttle control member for releasing the retaining means to permit clutch engagement. As shown in Fig. 1 the actuating arm 2 of the motor vehicle clutch 1 is connected by linkage 3, 4, 5 to the core 6 of an electromagnet 7, the clutch disengaged position being shown in full lines. In the position shown the core 6 is retained in its position by a spring urged ball 11 engaging a groove in the core. The ball 11 is released by an electromagnet 17 actuated by depression of the accelerator pedal G. The winding of the electromagnet 7 is energised to disengage the clutch by either movement of the change-speed gear lever V or the brake pedal F, the winding being de-energised by the breaking of contacts 15 by an abutment member 14 on the core 6 when the latter reaches its clutch-disengaged position. Movement of the core from the clutchdisengaged position to the clutch-engaged position under the action of the clutch restoring spring is controlled by a hydraulic device 19, which may be of the type described in Specification 619,150. In the modification shown in Fig. 3 two windings 7, 22 are provided on the electromagnet having its core 6 linked to the clutch 1, a spring 21 restoring the clutch to its engaged position. The windings 7, 22 are in circuit with contacts 28, 29, which are controlled by relays 24, 25 and a battery 8. The relay 24 can be excited either by a circuit including earth, normally controlled contacts 30, 31, a key switch 26, the battery 8 and earth or by a circuit including earth, normally open contacts 9 controlled by the gear lever V, the key 26, the battery 8 and earth. The relay 25 can be excited either by a circuit including earth, the. contacts 30, 31, normally closed contacts 15, the key 26, the battery 8 and earth or by a circuit including earth, the contacts 9, the contacts 15, the key 26, the battery and earth. The arrangement is such that with the clutch engaged when the relays 24, 25 are operative the core 6 is moved to its clutch disengaged position when the contacts 15 are broken by the abutment 14, thus de-energised the main winding 7 whilst the winding 22 remains operative holding the clutch disengaged. The clutch can be re-engaged by a dynamo 27 driven by the vehicle engine reaching a critical speed and operating a relay 23 controlling the contacts 31. The vehicle can, however, have its clutch held disengaged to coast with the contacts 31 open by moving the gear lever V sufficiently to make the contacts 9 but not to vary the change speed gearing. The engine can be utilised for braking purposes by the action of the relay 23 until the engine speed falls below the critical speed. The contacts 30 are provided so that they form a switch intended to render it possible to engage the clutch when the speed of the dynamo is not sufficient to excite the relay 23 and especially when the engine is stopped. Movement of the core 6 into the clutch engaged position is controlled through a dashpot device (:see Group XXXII) having a variable throttling valve 48 (see Group XXIX) under the control of a relay 50, the field circuit of which includes earth, the battery 8, the key 26, contacts 56 and earth. The contacts 56 are closed when the gear lever V occupies one of the two positions corresponding to reverse and to first forward gear so that clutch engagement in these gears is more gradual than in the remaining gears when the contacts 56 are open.