GB1461885A - Variable speed hydroviscous drive unit with electronic control system - Google Patents

Abstract

1461885 Friction clutches; clutch control; change-speed control; viscous coupling control K E HANDKE 10 Jan 1974 01240/74 Headings F2C F2L F2D and F2W A torque transmitting unit 18 comprises a set of discs 74 rotating with an input shaft 14 interleaved with a set of discs 76 rotating with an output shaft 16, fluid for cooling being supplied to the discs 74, 76 (Fig. 1) by a centrifugal pump 100 mounted on a continuously rotating portion of the unit and below the level 96 of fluid in a housing 12, the centrifugal pump 100 having an annular inlet 112 from which fluid flows radially out between vanes 110 to ducts 114, 116, 118 leading to the discs. In the embodiment shown in Fig. 1 the unit 18 is a continuously slipping wet-type or viscous-shear clutch and a stationary electromagnet 84 is actuated to move an armature 80 axially and so compress the discs by means of a presser plate 78 attached to the armature by bolts 82. An initial compression of the discs is provided by springs 98. The passage 118 for the fluid is formed by the removal of certain of the teeth in the discs 74. A magnetic pickup 88 is provided adjacent a gear 94 rotating with the output shaft to provide an electrical control signal. A second embodiment, shown in Fig. 2, having an input shaft 122, output shaft 124 and centrifugal pump 161, comprising vanes 168 with angled leading edges 168a which passes fluid to the discs 132, 136 through passages 174, 178, 180 and through a thrust bearing 131, is hydraulically or pneumatically actuated. The actuating fluid is supplied to a chamber 148 to compress the discs via thrust bearings 156. The input and output shafts of Fig. 2, may be reversed, and the pump fixed to the opposite end of he clutch (Fig. 3, not shown). Clutch control of the embodiment of Fig. 1 to provide a desired output speed is by an electrical circuit in which the output of sensor 88 is compared with a desired signal and the difference amplified and applied to the coil 84 (Fig. 4, not shown). A similar system is shown in Fig. 6 where a clutch/brake combination is provided, the output from a sensor 200b responsive to output speed being compared at 206b with a desired signal 252, the difference being amplified in amplifiers 208b and 212b with a feedback 214b providing stability, and the output being applied to clutch 248. The brake 250 is operated in exactly the same way but inverters 264 and 266 cause it to operate oppositely to the clutch. Forward and reverse gearing employing a pair of electromagnetic slipping clutches as shown in Fig. 1, one clutch for each direction of rotation, can be operated by selecting one clutch of a pair by switches (Fig. 5, not shown) or by the circuit of Fig. 7 where the desired speed signal 278 can be positive or negative (for the two rotational directions) and clutch 272 or 274 operates to provide the desired rotation with the other clutch acting as a brake.