| 摘要 |
<p>1,074,051. Fluid pressure brakes; fluid pressure control valves. BUDD CO. Feb. 16, 1965 [March 24, 1964], No. 6691/65. Headings F2F and F2V. A pressure-regulating valve for matching the characteristics of disc brakes to those of drum brakes comprises a valve housing having an inlet 25 and an outlet 28, a valve assembly 19 which is held in the closed position by a spring 31 until opened by hydraulic pressure, and, a check valve 33 permitting fluid to return from the outlet to the inlet. As shown, pipe 3 from the master cylinder of a motor vehicle supplies hydraulic fluid direct to drum type rear brakes through a pipe 4 and to disc type front brakes through the regulating valve and a pipe 7. At a low pressure the check valve 33 closes and no fluid passes to the front brakes. When the pressure rises to about 125 p.s.i. the pressure lifts a valve member 22 and fluid at a reduced pressure passes to the front brakes, the degree of pressure reduction depending on the ratio of the area D1 of the valve member 22 to the area D2 of a piston 20 one side of which is exposed to atmospheric pressure. At a pressure of about 320 p.s.i. the pressure acting on the area of the piston 20 maintains the valve in the open position, and the inlet and outlet pressures become equal. The check valve 33 permits fluid to return freely when the pressure is being reduced, the pressure at the ports 25 + 28 then being equal at all times.</p> |
