Patent GB-841578-A (GB)
Title: Automatic clutch
IPC: F16D45/00
Filed: 1956-10-04
Abstract: 841,578. Clutches. BOCHORY, M. Oct. 4, 1956 [Oct. 6, 1955; Nov. 25, 1955; May 26, 1956], No. 30332/56. Class 80 (2). A centrifugal clutch 103, 104, 105, Figs. 2 and 3, comprises a plurality of shoes 104 loaded by springs 157 out of engagement with the driven drum 105 and pivotally mounted weights 103 for engaging the shoes which are loaded to inoperative position by springs 161. Progressive clutch engagement is thus provided in two successive phases, the first by engagement of the shoes alone against the springs 157 and the second by the action of the weights against the springs 161. As shown, the shoes 104 are pivoted on pins 155 and the springs 161 are blade springs. The shoes may be otherwise supported for radial movement and may also be loaded by blade springs. The shoes 104 and weights 103 are shown mounted upon the flywheel 102 of an engine and the driven drum 105 is rotatably supported on the driven shaft 111 of a vehicle transmission and is adapted to be clutched therto by the engagement of armatures 112 with a clutch disc 108 on the shaft 111 under the action of electromagnetic coils 107. To ensure a drive of the driving shaft by the driven shaft in one direction when the speed of the latter is higher, to allow of engine braking or of a towed start, a free-wheel device is provided between a ring 162 coupled by dogs 164, 165 to the drum 105 and an outer ring 169. This ring 169 carries cam projections 170 which on clutching of the ring 169 to ring 162 by balls 166 on cam slopes 163 move in a direction indicated by the arrow in Fig. 2 to engage members 158 secured to the shoes 104 to force the shoes into engagement with the drum 105 irrespective of whether the speed of the driving shaft is sufficient for centrifugal engagement. A combined centrifugal and electromagnetically-actuated clutch, as described above, is adapted for operation in conjunction with a gear-change mechanism of the vehicle as shown in Fig. 8. The electromagnetic clutch is represented by 207, 208, 212 while in the circuit there is a contact 223 adapted to be closed by engagement of any one of the gears, a contact 220 controlled by an engine speed responsive device and a changeover contact 224 controlled by the accelerator pedal of the vehicle to bring a resistance into or out of the circuit. In operation, with the engine stopped or slow running, the contact 220 is open so that the clutch is not energized to engage. On engaging a gear and speeding up the engine contacts 223 and 220 are closed and contact 224 puts the resistance R in circuit to provide a partial engagement of the clutch 207, 208, 212. On further acceleration the contact 224 cuts-out the resistance R to cause full clutch engagement. In a modified arrangement of electromagneticaly actuated clutch, Fig. 9, the clutch is engaged by spring pressure and released by the energization of the electromagnetic coils. The driven plate of the electromagnetic clutch may be of conical or concave form in its inoperative state to avoid the effect of remanent magnetism when disengaging. Alternatively, or in addition, the faces of the electromagnet and armature may be conical form. Specification 792,904 is referred to.