Patent GB-178140-A (GB)
Title: Improvements in or relating to couplings or brakes
IPC: F16D43/284
Filed: 1920-10-05
Abstract: 178,140. Noeggerath, J. E. Oct. 5, 1930. Clutches, friction.-In friction clutches or brakes actuated by fluid pressure, the pressure is generated in a viscous fluid, such as oil or grease, within the body of the clutch or brake by screw-groove viscosity-pumps disposed on surfaces in relative motion, and is controlled by stop-cocks in pipes connecting chambers under different pressure. In some cases the groovepumps serve also as packing between the spaces under different pressures. As applied to a clutch, Fig. 1, driving and driven shafts b, c, having slight axial freedom, carry respectively clutch-members b1, c1, containing between them a fluid-chamber l and running within and circumferentiallv in contact with a casing a provided with sealing-threads b3, c3. The screw pump g draws fluid from the space l and circulates it to a chamber d and through a pipe i. When a cock i1 is closed, pressure is generated in the space d, and the clutch is engaged. The unbalanced pressure may serve to counteract an axial thrust on the clutch, or may be neutralized by providing a screw pump h on the member c1 and an additional pipe (not shown), so that pressure is generated in the chamber e as soon as the driven shaft c revolves. Release may be accelerated by bringing the space l under pressure. A form operative in both directions of rotation is shown in Fig. 2. Clutch-members b1, c1 are brought into contact for one direction of rotation by pressure in chambers d, e, created by oppositely-directed grooves g, h and controlled by a throttle i1, as in the first example. Upon reversal, the fluid is pumped into the chamber l, and the members b1, c1 move to press against flanges m1, m2 on a floating ring m, which has screw-grooves g1, h, and runs in contact with the casing a. As the speed of the part m increases, the pumps g, h gradually become inoperative, but the pumps g1, h, then maintain the pressure, so that the shaft b, c are coupled through the ring m. In a modification, the grooves are formed spirally on the radial faces between modified forms of the parts a, m1, m2, b1, c1. In the form shown in Fig. 4, the parts b1, c1 are coupled through an intermediate member m by helical rolls g, which lie in grooves g2 and are pressed outwards into contact with the part m when the circulation of fluid in the pipe i is stopped. Fluid is drawn from an external source through a pipe i12À If the member b1, c1 and the ring m are each provided with pairs of oppositelv-directed pressure and sealing-grooves, no fluid reaches the spaces d, e, so that the casing a may be open-ended. A duplicate arrangement is described, wherein the driven member c, is mounted on a short intermediate shaft carrying the driving-member of the second clutch, the whole being contained in a single casing. Fig. 6 shows a modification of the form shown in Fig. 1, wherein the driving-member b1 has a low-pressure, high-delivery pump g1 and a high-pressure pump g5. The spaces d, e are quickly filled by the pump g4 through the pipes i2, i. Thereafter the cock i1 is closed, and pressure is raised by the pump g5. A controlling-throttle is provided in a pipe (not shown) connecting the space k and pipe i. In another modification of the construction shown in Fig. 1, the spaces d, e are made small, so that the action is rapid, and the sealing-grooves b3, c3 co-operate with bosses on the members b1, c1, the casing a being extended beyond these bosses to bear on the shafts, thereby relieving the fine screw-grooves of wear. The chambers d, e may communicate with an airvessel. The lower half of the casing a may form an oil-cooling chamber, particularly when the device is used as a brake. In the cone clutch shown in Fig. 9, oil drawn from a supply-pipe i11 is circulated simultaneously by pumps g6 around pipes i, i3 and by oppositely-acting pumps g7 around pipes i6, i3, sealing-threads g, h being provided. A cock i1 is closed to actuate the clutch, release being effected, after opening it, by closing a cock i4, so that pressure is communicated through a passage i5 to the conical surfaces and distributed thereon by grooves p, thus permitting a smaller angle of cone to be used. The driven shaft is here replaced bv a gear-wheel r mounted on an extension of the member c1. Fig. 10 shows a clutch in which one set of grooves on each member b1, c1, indicated diagrammatically by arrows g8, g11, operates in conjunction with pipes i9, i11 and a throttle i10 for one direction of rotation, and a second set g9, g10 with pipes i<6>, i8 and a throttle i7 operates for the other direction. The pipes i6, i9 may coalesce into a single pipe, and the cocks may be arranged to be simultaneously operable. A form is described in which the casing is dispensed with, and the viscosity-grooves are cut on the surfaces of fixed members, such as bearings, running in contact with the shaft, with a boss on one clutch-disc, and with an annular piston abutting on the other clutch-disc. An equalizing- pipe connects pressure-chambers in the fixed parts, and a throttle-controlled pipe leads to the suction end of the main groove, counter-threads being provided as packing. Fig. 12 shows means for clutching a part, such as a gear-wheel and casing r, to a shaft b in either direction of rotation. Members b, c, are slidably secured to the shaft by a squared part c4 or key and slot b5, or one member may be rigidly secured if the shaft has axial freedom. The suction and pressure ends of the pump-grooves g, h are connected by throttle-controlled piping, and an equalizing-pipe (not shown) connects the chambers d, e as before. Packing-threads b3, c3 are provided. The members b1, c1 move into contact with end walls r2 or a flange r1 according to the direction of rotation. In a modification, the part r runs on stationary bearings, between which and the shaft are disposed the screw-grooves, and in a further modification, the casing r is divided, each part enclosing a clutch-member and bearing also on a central bearing. Grooves may be cut on moving parts also. Any of the forms may function as a brake when one member is stationary, for example, the part r, Fig. 12. When necessary, an air-cushion, spring, or other clamping-device may be incorporated in order to hold the brake when the parts are at rest. The pressure, or, in the example shown in Fig. 6, the pressures, may be used for extraneous purposes, such as supplying forced-lubricated machine parts. Small leakage-channels may be provided in the clutchparts in order to allow circulation of the fluid for cooling purposes.