Patent GB-1491203-A (GB)
Title: Devices for limiting torsional shocks
IPC: F16D43/21
Filed: 1974-10-21
Abstract: 1491203 Friction clutches; slip clutches VOLVO AB 21 Oct 1974 [20 Oct 1973] 48992/73 Headings F2C and F2D In a friction clutch or brake wherein torque responsive means 11 between an intermediate member 8 and a driven shaft 2 normally provide a clutch or brake engaging pressure proportional to transmitted torque, the torque responsive means additionally provide a force which reduces clutch engagement when a rapid increase in the transmitted torque occurs. A torque responsive clutch, Fig. 1, comprises friction discs 3, 4 respectively splined to a driving housing 18 and the intermediate member 8 and urged into engagement by springs 5 which are variably loaded via the intermediate member 8 by torque responsive inclined struts 11 between the intermediate member 8 and a flange 14 on the driven shaft 2. When the transmitted torque increases the intermediate member 8 moves left to increase the clutch engaging pressure. A chamber 28 between the intermediate member 8 and housing 18 is continuously supplied with pressure liquid through a non-return valve 27 and fluid bleeds from the chamber 28 through an orifice 29. When a rapid increase in the transmitted torque occurs the struts 11 move the intermediate member rapidly left to compress the fluid in the chamber 28 which thus acts to move a clutch presser plate 6 right and reduce clutch engagement. The torque responsive struts 11 may be replaced by intermeshing helical teeth on the intermediate member 8 and flange 14 or by a cam and roller torque responsive means. In Fig. 2 the clutch is engaged by supplying pressure liquid from a control valve 48 to a clutch engaging piston 6<SP>1</SP> at a pressure which is proportional to a supply pressure 46 that is regulated by a valve 47 controlled by torque responsive axial movement of the intermediate member 8<SP>1</SP>. The pressure liquid supply 46 acts through an orifice 54 on one end 50 of the valve 48 and on a reduced diameter plug 58 at the other end of the valve 48. When the transmitted torque increases the struts 11<SP>1</SP> move the intermediate member 8<SP>1</SP> left to restrict the flow through the valve 47 and thus increase the supply pressure 46. The increased supply pressure acting on opposite ends of the valve 48 moves the latter left whereupon a spool 49 of the valve meters pressure liquid to the clutch engaging piston 6<SP>1</SP>. The clutch engaging pressure additionally acts between the plug 58 and spool 49 to move the latter right as clutch engaging pressure increases and thus cut off additional supply to the clutch engaging piston. When a rapid increase in the transmitted torque occurs the supply pressure increases rapidly and acts immediately on the plug 58 whereas the restriction 54 prevents immediate application of the increased force to the end 50 of the valve which thus moves right to a position in which the valve spool 49 vents the clutch engaging pressure at 53 for reduced clutch engagement. Thereafter the clutch engaging pressure is gradually increased as the pressure on the end 50 of the valve increases. The friction discs 3, 4 may be omitted and the intermediate member 8 directly splined to the input housing 18 to provide a torque responsive pressure regulating device providing a modulated output pressure 55 which is applied to ratio establishing clutches and brakes in a change-speed gear. In Fig. 3 (not shown) alternate struts 11 are inclined in opposite directions to provide a bi-directional torque responsive device.