Abstract: A master cylinder includes a cylinder body, primary cups supported on the inner periphery of the cylinder body, and a primary piston and a secondary piston inserted in the cylinder body so as to be in sliding contact with the respective primary cups. The cylinder body is integrally formed with annular walls behind the respective primary cups. The annular walls have a greater inner diameter than the inner diameter of the cylinder body to define annular passages between the annular walls and the respective pistons. Connecting passages having a greater radial dimension than the annular passage are defined between the inner periphery of the cylinder body and the respective pistons behind the respective annular walls so as to communicate with a reservoir. While the master cylinder is not actuated, piston ports formed in the respective pistons communicate with the reservoir through the respective annular passages and connecting passages.

Abstract: A master cylinder includes a primary cup received in a groove formed in the inner wall of the cylinder body. Projections are formed on a radially inner portion of the cup so as to protrude forwardly from the front end of the radially inner portion. The projections are adapted to be pressed against the front end wall of the cup-receiving groove and elastically deformed under a pressure difference produced between the front and rear ends of the cup when the piston is returned quickly, allowing the cup to advance in the cup-receiving groove. When the cup advances in the groove, a fluid passage is defined between a base portion of the cup and the rear end wall of the groove.

Abstract: A master cylinder includes a cylinder body and primary and secondary pistons slidably received in the cylinder body, thereby defining first and second pressure chambers in the cylinder body. The first and second pressure chambers communicate with a reservoir through first and second fluid passages, respectively. During automatic brake control such as traction control or vehicle stability control, hydraulic fluid is drawn from the reservoir through the first and second pressure chambers. A throttle valve is received in each of the first and second fluid passages. The throttle valves are adapted to open while the master cylinder is inoperative and to close under backflow pressure when hydraulic fluid flows from the pressure chambers toward the reservoir. The throttle valves each include a floating valve body and a valve seat.

Abstract: A master cylinder includes a primary piston and a secondary piston, each formed with piston ports which include two different kinds of ports, i.e. first ports for ensuring communication between a reservoir and a pressure chamber of the master cylinder, and second ports through which brake fluid is sucked from the reservoir during automatic break control. The second ports are greater in number than the first ports and are positioned forwardly of the first ports so that the second ports are closed by primary cups which are provided on the inner wall of the cylinder body so as to be in sliding contact with the respective pistons before the first ports when the respective pistons are advanced. An annular wall having a greater inner diameter than the outer diameter of the pistons is formed on the inner wall of the cylinder body to support the back of each of the primary cups. An annular groove is formed in each piston so as to communicate with the first ports.

Abstract: A brake master cylinder includes a cylinder body having a circumferential groove formed therein. A primary cup is received in the groove and supported axially by a rear wall defined by the groove. A primary piston is inserted in the cylinder body in sliding contact with the primary cup. The rear wall has a radially inner surface formed with a plurality of grooves. A passage leading to a reservoir is provided in the rear of the grooves. The piston is formed with radial through holes corresponding to the grooves. When the piston is at the return end of its stroke, the pressure chamber defined in the cylinder body can communicate with the reservoir through the radial through holes, the grooves and the passage.

Abstract: A master cylinder includes a cylinder body and a piston slidably inserted in the cylinder while kept in slide contact with two cup members both fitted in the inner surface of the cylinder body to seal the gap between the piston and the inner surface of the cylinder body. On its radially inner surface, the cylinder body is formed with first to third piston guide portions. Each piston guide portion is formed with an odd number of grooves arranged at circumferentially equal distances. Each groove of each piston guide portion axially aligns with the corresponding grooves of the other piston guide portions. The circle including the bottoms of the grooves of the first guide portion has a diameter equal to or smaller than the rear opening of the cylinder body. The grooves of the first guide portion have a width gradually decreasing toward the front end thereof.

Abstract: A master cylinder includes a cylinder body and primary and secondary pistons slidably received in the cylinder body, thereby defining first and second pressure chambers in the cylinder body. The first and second pressure chambers communicate with a reservoir through first and second fluid passages, respectively. During automatic brake control such as traction control or vehicle stability control, hydraulic fluid is drawn from the reservoir through the first and second pressure chambers. A throttle valve is received in each of the first and second fluid passages. The throttle valves are adapted to open while the master cylinder is inoperative and to close under backflow pressure when hydraulic fluid flows from the pressure chambers toward the reservoir. The throttle valves each include a floating valve body and a valve seat.

Abstract: A master cylinder includes a cylinder body, a piston slidably received in the cylinder body to define a pressure chamber in the cylinder body, and a reservoir coupled to the cylinder body. The reservoir has a downwardly extending protrusion formed with a hole through which the interior of the reservoir communicates with the pressure chamber, and a shoulder at the top end of the hole. A valve body is received in the hole and includes a disk adapted to be moved into and out of contact with the bottom surface of the protrusion, and extensions extending upwardly from the disk and inserted in the hole. Each extension has an engaging portion protruding upwardly from the hole and engageable with the shoulder. The valve body is movable upwardly until the fluid passage defined between the disk and the protrusion is closed under the back flow pressure of hydraulic fluid toward the reservoir.

Abstract: Disclosed is a master cylinder wherein a seal member is given plural seal functions to reduce the number of seal members for partitioning a drain portion of the master cylinder, a constant-pressure chamber of a booster and the atmosphere from one another, so that the master cylinder is simplified in construction and reduced in manufacturing cost. When a piston is operated by an output shaft of the booster attached to a booster mounting surface of a cylinder body, the operating fluid from the fluid pressure chamber partitioned by a fluid-tight seal member is supplied to a brake system. An annular complex seal member is fit in an internal seal stepped portion which is formed by radially expanding an opening portion of the cylinder which opens to a booster mounting surface. A slide seal portion of the complex seal member partitions a drain portion behind the fluid-tight seal member from the constant-pressure chamber of the booster through sliding contact with the piston.

Abstract: A master cylinder apparatus is provided with a master cylinder and a booster. The booster comprises a booster shell whose interior is divided into a variable and constant pressure chambers. The master cylinder comprises a master piston inserted in a cylinder body. The cylinder body includes an installation flange to which the booster shell is attached. When the brake pedal is operated, a pull mechanism operates a control valve to communicate the variable-pressure chamber with atmosphere. The master piston is moved by an output member of the booster to generate a fluid pressure in the master cylinder that is delivered to wheel cylinders. The installation flange of the cylinder body can be attached to a dashboard so that the booster shell is disposed in the passenger room or the engine room, with the cylinder body protruding into the other room.

Abstract: A master cylinder includes a primary cup received in a groove formed in the inner wall of the cylinder body. Projections are formed on a radially inner portion of the cup so as to protrude forwardly from the front end of the radially inner portion. The projections are adapted to be pressed against the front end wall of the cup-receiving groove and elastically deformed under a pressure difference produced between the front and rear ends of the cup when the piston is returned quickly, allowing the cup to advance in the cup-receiving groove. When the cup advances in the groove, a fluid passage is defined between a base portion of the cup and the rear end wall of the groove.

Abstract: A master cylinder includes a cylinder body, primary cups supported on the inner periphery of the cylinder body, and a primary piston and a secondary piston inserted in the cylinder body so as to be in sliding contact with the respective primary cups. The cylinder body is integrally formed with annular walls behind the respective primary cups. The annular walls have a greater inner diameter than the inner diameter of the cylinder body to define annular passages between the annular walls and the respective pistons. Connecting passages having a greater radial dimension than the annular passage are defined between the inner periphery of the cylinder body and the respective pistons behind the respective annular walls so as to communicate with a reservoir. While the master cylinder is not actuated, piston ports formed in the respective pistons communicate with the reservoir through the respective annular passages and connecting passages.

Abstract: A master cylinder includes a primary piston and a secondary piston, each formed with piston ports which include two different kinds of ports, i.e. first ports for ensuring communication between a reservoir and a pressure chamber of the master cylinder, and second ports through which brake fluid is sucked from the reservoir during automatic break control. The second ports are greater in number than the first ports and are positioned forwardly of the first ports so that the second ports are closed by primary cups which are provided on the inner wall of the cylinder body so as to be in sliding contact with the respective pistons before the first ports when the respective pistons are advanced. An annular wall having a greater inner diameter than the outer diameter of the pistons is formed on the inner wall of the cylinder body to support the back of each of the primary cups. An annular groove is formed in each piston so as to communicate with the first ports.

Abstract: In a brake master cylinder, when a first piston is pushed forward, first and second fluid chambers of a cylinder which are partitioned respectively by first and second cup seals supply brake fluids therefrom to first and second brake systems. Even when slightly inclined upon receiving a pushing force, the first piston is slidably guided along a first sleeve which is softer than the first piston, without coming into contact with the cylinder body. Since the first piston is not abrasively damaged, it does not occur that the first cup seal is injured at a slide guide portion thereof.

Abstract: A master cylinder includes a cylinder body and a piston slidably inserted in the cylinder while kept in slide contact with two cup members both fitted in the inner surface of the cylinder body to seal the gap between the piston and the inner surface of the cylinder body. On its radially inner surface, the cylinder body is formed with first to third piston guide portions, with the first piston guide provided between the two cups, the second guide portion provided between the first guide portion and the cup remote from the rear opening of the cylinder body, and the third guide portion in front of the cup remote from the rear opening. Each piston guide portion is formed with an odd number of grooves extending parallel to the axis of the cylinder body and arranged at circumferentially equal distances. Each groove of each piston guide portion axially aligns with the corresponding grooves of the other piston guide portions.

Abstract: A master cylinder is proposed that is simple in structure, can minimize the stroke of the piston required to seal the port, and minimize the possibility of the primary cup getting damaged. 1. The master cylinder includes a cylinder body. A primary cup is provided on a radially inner surface of the cylinder body. A primary piston is inserted in the cylinder body while kept in slide contact with the primary cup. The cylinder body has a rear wall supporting the primary cup. The rear wall has a radially inner surface formed with a plurality of grooves. A passage leading to a reservoir is provided in the rear of the grooves. The piston is formed with radial through holes corresponding to the grooves. When the piston is at the return end of its stroke, the pressure chamber defined in the cylinder body is adapted to communicate with the reservoir through the radial through holes, the grooves of the rear wall and the passage.

Abstract: A sealing structure is provided with a seal member for sealing a double fitting portion where an annular member is fit in the internal surface of an outer member at its outer circumferential surface and is also fit on the outer circumferential surface of an inner member at its internal surface. In the sealing structure, the seal member is attached to an end surface of the annular member with an annular groove on its back surface being fit on an annular projection axially protruding from an end surface of the annular member at a radially mid position. At its forward end surface, the seal member is provided with annular outer and inner lips which are axially protruded for respective contacts with the internal surface of the outer member and the outer circumferential surface of the inner member, and is further provided an annular separation zone between the annular outer and inner lips.

Abstract: A master cylinder device connected with a brake booster device of an input rod pulling type is disclosed. In the brake booster device, the interior of a brake booster is partitioned by a diaphragm with a piston secured thereto, into a constant pressure chamber and a variable pressure chamber. The piston incorporates therein a valve mechanism operated by a brake pedal for making the variable pressure chamber communicate selectively with the atmosphere and the constant pressure chamber. The brake booster device transmits the axial movement of the diaphragm generated based on the pressure difference between the both chambers, from the piston through a reaction mechanism to an output rod. The output rod pulls a piston rod of a master cylinder rearward for making the master cylinder generate a braking pressure.

Abstract: A master cylinder device with a brake booster device of an input rod pulling type is provided which is easy to assemble and in which the brake booster device and the master cylinder device therefor can be assembled independently of each other. The brake booster device is constructed so that a booster is partitioned by a diaphragm into a constant pressure chamber and a variable pressure chamber and that a piston secured to the diaphragm incorporates therein a valve mechanism for changing over the variable pressure chamber into communication with the constant pressure chamber or into communication with the atmosphere. The master cylinder device is constructed so that a master piston is inserted in a master cylinder formed in a cylinder body and that the pressurized brake fluid is delivered when a piston rod connected to the master piston is pulled toward the passenger room of the vehicle.

Abstract: A master cylinder apparatus is provided with a master cylinder and a booster. The booster comprises a booster shell whose interior is divided into a variable-pressure chamber and a constant-pressure chamber, a control valve to regulate the communication of the variable-pressure chamber with the constant-pressure chamber and the atmosphere. The master cylinder comprises a cylinder body provided with a cylinder and a master piston inserted in the cylinder. The cylinder body formed with an installation flange to which the booster shell is attached at the same end that the cylinder opens. Pull means connected to a brake pedal at one end and to the control valve at the other end. The installation flange is attached to a dashboard, so that the booster shell is disposed in one of a passenger room and an engine room and the cylinder body protrudes into the other room.