| 摘要 |
PROBLEM TO BE SOLVED: To provide a brake mater cylinder which can solve fear that operating oil penetrates from a lubrication chamber to the inside of a brake assistor caused by the rust of an oil scavenging hole, can prevent penetration of rainwater from the discharge port of the oil scavenging hole to a piston and the closing of the oil scavenging hole due to the penetration of a foreign matter from the discharge port to the inside of the oil scavenging hole. SOLUTION: A fitting part 21 mounted in an attaching recessed part 72 arranged in the booster body of a brake booster 70, is arranged in the rear part of a cylinder body 2. A lubrication chamber 33 for operating oil is sectioned in the inner circumference and periphery of the cylinder hole of a piston 4 which is stored in the cylinder hole 3 of the cylinder body 2 and also whose rear end is projected to the inside of the brake booster 70. A seal zone where an interval between the cylinder hole 3 and the piston 4 is sealed, is sectioned behind further from the lubrication chamber 33, and also oil scavenging holes 8, 9 which have a discharge port in a part excluding the lower end of the periphery of the fitting part 21 and by which the seal zone where the interval between the cylinder hole 3 and the piston 4 is sealed is communicated with the outside, are arranged in a manner that they are lowered and inclined toward the discharge port of the part excluding the lower end of the periphery of the fitting part 21. |
