Abstract: A recess is formed in a rear portion of a pressurizing piston, and a small-diameter rod is formed in a front portion of an input piston. A sleeve is disposed inside the recess, and the small-diameter rod is liquid-tightly and slidably fitted to the sleeve. A space between the small-diameter rod and the recess serves as a volume chamber, which is held in communication with a reservoir. The input piston and the pressurizing piston are slidably fitted to each other via the sleeve. Therefore, the generation of a frictional force between the input piston and the pressurizing piston can be made unlikely, and the pressurizing piston can be favorably prevented from advancing as the input piston advances.

Abstract: A vehicle hydraulic brake system of the brake-by-wire type includes input piston and a master piston configured to be actuated under hydraulic pressure introduced into a second fluid chamber and mounted in the housing so as to be movable relative to each other through a partition wall and a first fluid chamber. The piston defines therein a communication passage which extends from a fourth fluid chamber to the first fluid chamber and in which a check valve is mounted. When the piston is advanced under hydraulic pressure introduced into the second fluid chamber, the volume of the fourth fluid chamber decreases, while the volume of the first fluid chamber increases. This allows brake fluid in the fourth fluid chamber to be quickly released into the first fluid chamber through the communication passage and through a pipe line in which an electromagnetic on-off valve are mounted.

Abstract: A vehicle brake system includes a first fluid chamber whose volume changes corresponding to the amount of advancement and retraction of the input piston, a second fluid chamber into which hydraulic pressure from a hydraulic pressure source is introduced after adjustment in a pressure regulator, a third fluid chamber kept at the atmospheric pressure, a stroke simulator which generates a reaction force to the brake operation corresponding to a change in volume of the first fluid chamber, a master cylinder, a partition member partitioning each of the second and third fluid chambers from the first fluid chamber, first and second seal members disposed in respective fitting gaps, and an annular member having both ends abutting respective seal members. The annular member divides a space into first and second space portions whose volumes respectively increases and decreases by the same amount when the annular member moves in one axial direction.

Abstract: A recess is formed in a rear portion of a pressurizing piston, and a small-diameter rod is formed in a front portion of an input piston. A sleeve is disposed inside the recess, and the small-diameter rod is liquid-tightly and slidably fitted to the sleeve. A space between the small-diameter rod and the recess serves as a volume chamber, which is held in communication with a reservoir. The input piston and the pressurizing piston are slidably fitted to each other via the sleeve. Therefore, the generation of a frictional force between the input piston and the pressurizing piston can be made unlikely, and the pressurizing piston can be favorably prevented from advancing as the input piston advances.

Abstract: A vehicle hydraulic brake system of the brake-by-wire type includes input piston and a master piston configured to be actuated under hydraulic pressure introduced into a second fluid chamber and mounted in the housing so as to be movable relative to each other through a partition wall and a first fluid chamber. The piston defines therein a communication passage which extends from a fourth fluid chamber to the first fluid chamber and in which a check valve is mounted. When the piston is advanced under hydraulic pressure introduced into the second fluid chamber, the volume of the fourth fluid chamber decreases, while the volume of the first fluid chamber increases. This allows brake fluid in the fourth fluid chamber to be quickly released into the first fluid chamber through the communication passage and through a pipe line in which an electromagnetic on-off valve are mounted.

Abstract: A vehicle brake system includes a first fluid chamber whose volume changes corresponding to the amount of advancement and retraction of the input piston, a second fluid chamber into which hydraulic pressure from a hydraulic pressure source is introduced after adjustment in a pressure regulator, a third fluid chamber kept at the atmospheric pressure, a stroke simulator which generates a reaction force to the brake operation corresponding to a change in volume of the first fluid chamber, a master cylinder, a partition member partitioning each of the second and third fluid chambers from the first fluid chamber, first and second seal members disposed in respective fitting gaps, and an annular member having both ends abutting respective seal members. The annular member divides a space into first and second space portions whose volumes respectively increases and decreases by the same amount when the annular member moves in one axial direction.

Abstract: A vacuum booster which moderates a retraction speed of a valve seat member to restrain a contact noise between a key member retracting in a unitary manner with the valve seat member and a flange surface of a plunger. The vacuum booster includes a noise restriction device.

Abstract: A vacuum booster which moderates a retraction speed of a valve seat member to restrain a contact noise between a key member retracting in a unitary manner with the valve seat member and a flange surface of a plunger. The vacuum booster includes a noise restriction device.

Abstract: A vacuum booster which moderates a retraction speed of a valve seat member to restrain a contact noise between a key member retracting in a unitary manner with the valve seat member and a flange surface of a plunger. The vacuum booster includes a noise restriction device.

Abstract: A negative pressure type brake hydraulic pressure generating device is proposed in which the stroke on the operating side can be set independently of the stroke on the output side. A slide resistance imparting means is provided between the fixed shell and a piston having a built-in control valve introducing atmospheric air to cancel the slide resistance which is the cause of increased stroke hysteresis of the piston, i.e. the slide resistance applied to the piston at airtight seal portions between the power plate and the piston.

Abstract: A negative pressure type booster, comprising a valve seat member (40), a spring (47) energizing the valve seat member (40), and a holding member (52) having an engaging part (52b) disposed on a power piston (22) movably only in radial direction and engaged with the valve seat member (40) and a tapered part (52a) in contact with a plunger (37), whereby, when the amount of movement of an input member (27) relative to the power piston (22) is larger than a specified value, the input member (27) is brought into contact with the tapered part (52a) and moves the holding member (52) in radial direction to disengage the holding member (52) from the valve seat member (40) in order to allow the valve seat member (40) to be moved rearwards.

Abstract: A negative pressure type brake hydraulic pressure generating device is proposed in which the stroke on the operating side can be set independently of the stroke on the output side. A slide resistance imparting means is provided between the fixed shell and a piston having a built-in control valve introducing atmospheric air to cancel the slide resistance which is the cause of increased stroke hysteresis of the piston, i.e. the slide resistance applied to the piston at airtight seal portions between the power plate and the piston.

Abstract: It is aimed to improve brake feeling of a negative pressure type brake hydraulic pressure generating device in which the stroke on the operating side can be set independently of the stroke on the output side. A spring for setting the stroke on the operating side is formed of coil springs arranged in series to impart the spring nonlinear characteristics, thereby biasing a piston, which can be moved axially relative to a power plate and includes a control valve for introducing atmospheric air, in the return direction.

Abstract: A vacuum servo unit is provided with an actuator for controlling the distance between the engaging portion of a first input member with a reaction disc and an air pressure valve seat in response to a driving force. The vacuum servo unit further includes a rubber member disposed between the first input member and a movable core. The rubber member is deformable in response to the relative movement of the first input member and the movable member forming a part of the actuator. When the actuator is inactive, an axial space is formed between the reaction member and the first input member and between the first input member and a second input member.

Abstract: A vacuum booster which moderates a retraction speed of a valve seat member to restrain a contact noise between a key member retracting in a unitary manner with the valve seat member and a flange surface of a plunger. The vacuum booster includes a noise restriction device.

Abstract: A vacuum brake booster includes a housing provided with at least one pressure chamber, a movable wall dividing the pressure chamber into a front chamber connected to the vacuum source and a rear chamber selectively connected to the front chamber and atmospheric pressure, a power piston connected to the movable wall, an input member disposed in the power piston, and a valve mechanism. An output member outputs the forward movement force of the power piston by moving forwardly with forward movement of the power piston in response to the movement of the movable wall. An auxiliary movable wall is disposed in the front chamber and is movable in the forward and rearward directions. The auxiliary movable wall moves the output member through engagement with the output member. A partition member is disposed in the front chamber and defines an auxiliary chamber in the front chamber with the auxiliary movable wall. The rear chamber and the auxiliary chamber are adapted to be connected with each other.

Abstract: A negative pressure type servo unit which allows the size of the actuator to be reduced includes a housing, a movable wall positioned in the housing, a power piston, an input member, a plunger, a valve mechanism, an output rod, an actuator and a seal member. The seal is designed to include a first engaging portion and a second engaging portion producing a pressure difference on a front side and a rear side of the seal.

Abstract: A vacuum servo unit includes a constant pressure chamber and a variable pressure chamber in a housing, a power piston, an output member, an input member, a plunger, a valve mechanism, and an actuator. The actuator is disposed in the power piston for moving the plunger in the forward and rearward directions. The outer periphery of the actuator is provided with a concave or recessed portion serving as a communicating passage between the constant pressure chamber and the variable pressure chamber. The concave or recessed portion is in the form of a notch defined in a yoke enclosing the solenoid coil of the actuator. The communicating passage is constituted by the notch and the inner periphery of a cylindrical portion of the power piston at the front side of the power piston.

Abstract: A brake control device includes a pressurization device having a first pressurization device for pressurizing the brake fluid supplied to wheel brakes in response to the driver's operation and a second pressurization device for pressurizing the brake fluid supplied to the wheel brakes independently of the driver's operation; a first detecting device for detecting a displacement of an input member of the pressurization device or an output pressure of the pressurization device; a second detecting device for detecting the condition of the vehicle; and a control device for memorizing relationships between a driving signal of the second pressurization device and the displacement of the input member or relationships between a driving signal of the second pressurization device and the output pressure of the pressurization device as control maps corresponding to the variety of the condition of the vehicle and for controlling the driving signal of the second pressurization device on the basis of the control

Abstract: A vacuum servo booster 10 for vehicle brake systems includes a housing 14, movable walls 17 and 20, a power piston 22, an input member 28, an input rod connected to a brake pedal 80, a valve mechanism 34, an output rod 49, and an actuator 41. In the vacuum servo booster 10, the input rod 27 has a front portion 271 and a rear portion 272 which are telescopically connected at a portion 273 within the power piston 22.