| 摘要 |
PURPOSE:To suppress power consumption at the non-braking time while preventing the generation of noise based on cavitation inside a booster and at a relief valve part at the braking time. CONSTITUTION:A second relief valve 31 for generating back pressure is provided at the intermediate part of a drain oil pipe 28. The elasticity of a weak spring 32 and the oil pressure in a feed oil pipe 30 make the valve opening pressure of the second relief valve 31. At the non-braking time, oil pressure is low, so that the valve opening pressure is low. Accordingly, oil pressure discharged from a pressure oil pump 5 becomes also low to suppress power consumption. At the braking time, oil pressure is high, so that the valve opening pressure becomes high. Sufficient back pressure is thereby generated to prevent the generation of cavitation. |
