Brake apparatus

A brake apparatus comprising:

• a brake operation member configured to be operated by a driver;
• a brake operation state detection unit configured to detect an operation state of the brake operation member,
• a housing including a first chamber on an opening side in a cylinder having closed one end side, a second chamber on a closed portion side, and a partition wall formed between the first chamber and the second chamber;
• an operation rod configured to be activated in an axial direction between the first chamber and the second chamber via a through-hole formed through the partition wall according to the operation of the brake operation member, and having a first diameter;
• a piston including a first portion formed on the opening side in the second chamber and having a small diameter, a second portion formed on the closed portion side and having a larger diameter than the diameter of the first chamber, an insertion hole provided in the second chamber and configured to allow the operation rod to be inserted from the axial direction in such a manner that one end side thereof protrudes, an intermediate-diameter portion having a diameter larger than the first diameter and corresponding to the first portion on one side, and a large-diameter portion formed continuously from the intermediate-diameter portion and having a diameter corresponding to the second portion;
• a first seal member in slidable contact with an outer peripheral surface of the protruding portion of the operation rod;
• a second seal member in slidable contact with an outer peripheral surface of the intermediate-diameter portion, and configured to permit only a flow of the brake fluid from one side:
• a first pressure chamber formed between the first seal member and the one side of the second seal member;
• a third seal member in slidable contact with an outer peripheral surface of the large-diameter portion;
• a second pressure chamber formed between an opposite side of the second seal member and the third seal member;
• a hydraulic source configured to supply the brake fluid to the first pressure chamber and the second pressure chamber;
• a first oil passage connecting the hydraulic source and the first pressure chamber to each other;
• a second oil passage connecting the hydraulic source and the second pressure chamber to each other;
• and
• a fluid amount control unit having a first state, in which the fluid amount control unit controls an amount of the brake fluid to be supplied to the first pressure chamber and the second pressure chamber, and a second state, in which the fluid amount control unit supplies the brake fluid to the second pressure chamber.

A brake system comprising:

• a brake operation member configured to be operated by a driver;
• a brake operation state detection unit configured to detect an operation state of the brake operation member;
• a cylinder formed in a housing and having closed one end side:
• a piston provided displaceably in an axial direction in the cylinder, and configured to change a master cylinder hydraulic pressure by being displaced in the axial direction;
• and
• an operation rod configured to activate the piston according to the operation of the brake operation member, wherein
• the cylinder includes a first portion, and a second portion having a larger diameter than a diameter of the first portion,
• the piston includes an insertion hole in which the operation rod is slidably inserted in such a manner that one end of the operation rod protrudes from one end of the piston, an intermediate-diameter portion configured to be positioned in the first portion and having a larger diameter than a diameter of the operation rod, and a large-diameter portion configured to be positioned in the second portion, formed continuously from the intermediate-diameter portion, and having a larger diameter than the diameter of the intermediate-diameter portion, and
• the brake system further comprising:
• a first seal member in slidable contact with an outer peripheral surface of the protruding portion of the operation rod;
• a second seal member in slidable contact with an outer peripheral surface of the intermediate-diameter portion, and configured to permit only a flow of the brake fluid from one side;
• a first pressure chamber formed between the first seal member and the one side of the second seal member;
• a third seal member in slidable contact with an outer peripheral surface of the large-diameter portion;
• a second pressure chamber formed between an opposite side of the second seal member and the third seal member;
• a hydraulic source configured to supply the brake fluid to the first pressure chamber and the second pressure chamber;
• a first oil passage connecting the hydraulic source and the first pressure chamber to each other;
• a second oil passage connecting the hydraulic source and the second pressure chamber to each other;
• and
• a fluid amount control unit configured to control an amount of the brake fluid to be supplied to the first pressure chamber and the second pressure chamber, wherein
• the fluid amount control unit includes a switching unit configured to supply the brake fluid to the second pressure chamber when the detected brake operation state is equal to a first preset request, and to supply the brake fluid to the first pressure chamber and the second pressure chamber when the detected brake operation state is equal to a second preset request, and
• wherein the fluid amount control unit is configured to activate the piston by the supplied brake fluid, and is configured in such a manner that the brake fluid discharged due to the activation of the piston is supplied to a hydraulic unit for anti-lock control.