| 主权项 |
1. A cylinder device which supplies, in order to operate a brake device provided at a wheel, a pressurized brake fluid to the brake device, comprising:
a housing whose front end portion is closed and which is shaped like a tube; a pressurizing piston which has a main body portion, a flange portion formed on a circumference of the main body portion, and a blind hole opening at a rear end of the pressurizing piston and which is disposed in the housing so as to define (A) a pressurizing chamber which is located in a front side of the pressurizing piston and which pressurizes the brake fluid supplied to the brake device, (B) an input chamber in which a pressure from a high pressure source is inputted in a rear side of the flange portion, and (C) an opposing chamber which is located in a front side of the flange portion with the flange portion interposed between the input chamber and the opposing chamber and which is opposed to the input chamber, respectively; an input piston which is inserted in the blind hole of the pressurizing piston so as to define an inter-piston chamber in front of the input piston by the input piston and the pressurizing piston, and which is connected to an operation member at a rear end of the input piston; an inter-chamber communication passage which always permits communication between the opposing chamber and the inter-piston chamber such that the opposing chamber and the inter-piston chamber serve as a single operation-reaction-force chamber, for accommodating a volume change of the opposing chamber and a volume change of the inter-piston chamber with each other that are caused by a forward and rearward movement of the pressurizing piston; an elastic-force dependent pressurizing mechanism which pressurizes the operation-reaction-force chamber formed by the inter-chamber communication passage depending on elastic force; and a communication-state switching mechanism which selectively realizes a communication state in which the reservoir and the operation-reaction-force chamber communicate with each other and a not-communication state in which they do not communicate with each other, and wherein the cylinder device is configured such that, in the not-communication state, an operation reaction force, in accordance with an operation amount of the operation member, is generated depending on the pressurization of the operation-reaction-force chamber by the elastic-force dependent pressurizing mechanism, while the brake fluid in the pressurizing chamber is permitted to be pressurized in accordance with the pressure inputted from the high pressure source to the input chamber; in the communication state, a volume of the operation-reaction-force chamber is permitted to be reduced, thereby permitting the input piston to come into abutting contact with the pressurizing piston by a forward movement of the input piston, whereby the brake fluid in the pressurizing chamber is permitted to be pressurized by the operation force applied to the operation member. |
