| 摘要 |
PURPOSE:To enable reduction of the space between a pair of pressure receiving pistons which control the rear wheel braking oil pressure to the minimum required distance by providing a pressure adjusting coil spring formed in long length to have small spring constant on the outer circumference shoulder of said pressure receiving pistons. CONSTITUTION:A proportional valve consists of valves 231 and 232, pressure receiving pistons 91 and 92 and a common pressure adjusting spring 12, shoulders 311 and 312 being formed on said pressure pistons 91 and 92, and the pressure adjusting spring 12 being installed on said shoulders in contracted condition. When a brake pedal 1 is operated to increase the output oil pressure of a master cylinder M the pressure in the first and second input/output pressure chambers 181 and 191 and 182 and 192 also increase until the pressure reaches certain level where the diferential pressures acting on the pistons 91 and 92 due to the differences in the pressure receiving areas of the inner and outer ends of the pistons 91 and 92 exceed respectively the set loads of the pressure adjusting spring 12 and a positioning spring 17, then the pistons 91 and 92 slide inward compressing the pressure adjusting spring 12 and the positioning spring 17. When the pistons 91 and 92 move by the distance ''1'' inward the valves 231 and 232 close the connecting holes to prevent the increase of braking oil pressure for the rear wheels. |
