| 摘要 |
1,100,044. Fluid pressure control of brakes; disc brake. DUNLOP CO. Ltd. 4 May, 1965 [13 May, 1964; 11 Jan., 1965], Nos. 19832/64 and 1097/65. Headings F2E and F2F. A vehicle anti-skid system including an hydraulically operated friction member engageable with rotatable member and capable of limited movement about the axis thereof includes a means for controlling the pressure of fluid in the brake-applying mechanism, the control means comprising a fluid pressure operatad thrust device mounted adjacent the friction member and supplied with fluid at the pressure existing in the applying mechanism to generate a thrust to oppose the drag force exerted on the friction member, and a valve controlling the supply of fluid to the said mechanism and operated by the thrust device to interrupt or reduce the supply of fluid when the thrust exceeds the drag force. In the disc brake shown the caliper housing 4 containing opposed hydraulic cylinders and friction pads has small freedom to move about the axis of the disc 2 against spring restraint, the movement being limited by pins 11 in slots 13. The control means comprises a cylinder 14 with a piston 15 abutting the housing. Fluid pressure supplied to a chamber 19 from a master cylinder passes valve 22, held open by the piston, to enter chamber 20 and act on the piston 15, conduit 8 directing the fluid to the brake cylinders 5. The thrust of the piston 15 balances the frictional drag tending to move the housing 4 towards the cylinder 14, the drag being proportional to the fluid pressure and the piston thrust until the tyre 3 begins to slide relatively to the ground, when the drag reduces and the piston 15 and housing 4 move rightwards closing valve 22, the movement of the piston increasing the volume of chamber 20 to lower the braking pressure. In another embodiment (Figs. 2 and 3, not shown) a second piston (51) encircling the valve is provided between the chambers of the thrust member. When the valve closes this piston is moved towards the housing to bring one arm of an associated bell-crank lever (53) into contact with a cam surface formed on the edge of the disc, the piston then being oscillated thereby to pump the brakes. The oscillation is stated to also cause an oscillation of pressure in the master cylinder and to vibrate the brakeoperating lever to warn the driver that too much braking pressure has been applied. |
