Patent GB-841703-A (GB)
Title: Fluid coupling mechanism
IPC: F01P7/04
Filed: 1957-04-12
Abstract: 841,703. Friction clutches. SCHWITZER CORPORATION. April 12, 1957 [May 2, 1956], No. 12003/57. Class 80 (2). [Also in Groups XXVII and XXIX] In an hydraulic coupling comprising a rotor radially extending faces closely spaced from the inner walls of a housing and having liquid interposed for the transmission of torque, the rotor, or a member rotating with the housing, is provided with a radially extending fluid space, and a transverse opening is associated with the inner zone of the space so that the liquid circulates toroidally under centrifugal action when the rotor and housing rotate at different speeds in order to eliminate hot spots and dissipate the heat generated by fluid friction. As shown in Fig. 1, a coupling for driving engine-cooling fan blades 30 comprises a housing 26, 27 fast with a driving pulley 23 which also drives a water impeller 13 of the engine-cooling system. A rotor 32 is splined to the hub 29 of the fan and is closely spaced from the inner face of the housing part 27 and from a face of a disc 33 slidable axially of, but rotating with, the part 26. The rotor is formed with a radially-extending space 41 and ports 40. Due to the shearing action of the liquid, resulting from the rotation of the housing and plate 33, torque is transmitted to the rotor 32, causing the fan to rotate. Due to slip, the average angular velocity of the liquid between the rotor and the opposed faces of the housing and plate will be greater than that of the rotor and the centrifugal force on the liquid at the sides of the rotor will be greater than that on the liquid in the space 41. A circulation of the liquid will therefore result, radially outwardly along the sides of the rotor, inwardly through space 41 and axially outward through ports 40. This circulation aids the dissipation of heat caused by the slip, and the housing may be provided with heat dissipating fins. Plate 33 is connected by a rod 34 and a spring 47 to a temperature responsive element 45 which urges plate 33 to the right under the influence of rising coolant temperatures to reduce the spacing between the rotor and the opposed faces of the plate 33 and the housing to increase the torque transmitted and reduce slip. Element 45 may be capable of clamping the rotor between the disc and the housing; spring 47 prevents damage to the element in this event. Radially - extending outwardly - converging grooves 27a are formed in the inner face of the housing part 27, these grooves aid circulation of liquid and develop an hydraulic pressure tending to separate the rotor from the part 27. As a modification the rotor may be the input member and the fan blades be secured to the housing. In the embodiment shown in Fig. 7, fan blades 331 are secured to a housing 326, 327 having a torque transmitting plate 335 rotatable therewith but axially floating. The torque plate is formed in two sections spaced apart to provide a fluid space 335d. The rotor comprises a disc 334b formed with a portion 338 secured by dowel pins 341 to a flexible plate 342 which is secured to a shift pin 337 actuated by thermally responsive means. A support 333 in which the dowel pins are slidably mounted is fast with a driving hub 325, and a rotor plate 334a is axially slidable on the portion 338. The rotor drives the housing through the action of the liquid lying between the adjacent faces of the rotor plates, torque plate and the housing, and there is a toroidal circulation of liquid outwardly between these faces, inwardly through the radial space 335d and axially through ports 336 in the rotor. The rotor plates are lined with non-metallic material, and as the temperature of the cooling system increases the rotor plate 334b is displaced towards the torque plate until finally the adjacent faces of plate 334b, the torque plate, plate 334a and housing part 327 are in wet clutch engagement. In this embodiment radial grooves are provided in the faces of the torque plate as well as in the inner face of the part 327. In a modification (Fig. 8, not shown), the torque plate is fixed to the housing and the rotor plate 334a is fixed to the rotor portion 338 so that wet clutch engagement occurs between plate 334b and the torque plate and between plate 334a and the inner face of part 327. This may be further modified (Fig. 10, not shown), by dispensing with the torque plate and providing ports in the rotor discs to give toroidal flow radially outwardly between the rotor discs, radially inwardly between the discs and the housing and axially inwardly through the ports. In another modification (Fig. 3, not shown), the torque plate is again dispensed with and the rotor consists of two discs axially slidably keyed to the driving hub, the discs being moved apart by a camming arrangement under the control of a temperature responsive device, each disc approaching the adjacent wall of the housing with consequent approach to a wet clutch action. Ports are provided in the discs to give toroidal flow outwardly through the space between the discs, inwardly between the discs and the housing and axially inwardly through the ports. This may be further modified (Fig. 9, not shown), by having one of the rotor discs fixed to the input hub and the other disc axially slidable under the control of the temperature responsive. device.