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 brake master cylinder constructed to reduce the manufacturing cost and the size of the brake master cylinder includes first and second sealing members forming at least a part of first pressure chamber, and a third sealing member forming at least a part of a second pressure chamber. The first, second and third sealing members are engaged with the inner peripheral surface of a cylinder body and with the outer peripheral surface of respective first and second pistons. An annular member is positioned between the second and third sealing members. The annular member is supported by the cylinder body with a support member such as a pin or a ring.

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 brake master cylinder which prevents a contact between a projection of a spring retainer and a stopper of a sleeve when a piston is suddenly retracted by an operation of a pressure applying device of a brake system or by an air relieving operation to offer a high reliability without deformation and damages of the spring retainer and the sleeve. A groove extended in axial direction is provided on the sleeve. A distance between a rear end surface of the groove and a radial projection of a first spring retainer when the brake is not applied corresponds to the total of a distance of a retracting distance of a second piston from the position defined by the non-braking operation to a position where a piston port and an opening of a reservoir communication conduit are overlapped and a predetermined additional distance.

Abstract: A brake master cylinder constructed to reduce the manufacturing cost and the size of the brake master cylinder includes first and second sealing members forming at least a part of first pressure chamber, and a third sealing member forming at least a part of a second pressure chamber. The first, second and third sealing members are engaged with the inner peripheral surface of a cylinder body and with the outer peripheral surface of respective first and second pistons. An annular member is positioned between the second and third sealing members. The annular member is supported by the cylinder body with a support member such as a pin or a ring.

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 brake master cylinder for a vehicle brake system in which the assembling precision of a guide and a cup seal, the structure of a communication conduit, and the structure of a cylinder cap and the guide are improved to thereby improve the performance of the brake master cylinder while also reducing the cost and improving the sealing structure between a body and the cylinder cap to thus reduce the size of the cylinder cap. The brake master cylinder includes the cylinder cap positioned in an internal bore opening portion of the body, a first piston inserted into a cylinder housing through the cylinder cap and slidably supported by the guide in the axial direction, a second piston positioned coaxially with the first piston at the front of the first piston and slidable in the axial direction in the cylinder housing, and a cup seal at the front of the guide for liquid-tightly sealing a first pressure chamber formed between the first piston and the second piston.

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 master cylinder includes a cylinder housing formed by a cylinder body and a cap, a first guide member, a second guide member, a sleeve, a first piston and a second piston. To achieve accurate concentricity between a bore of the first guide member and a bore of the sleeve, and between a bore of the second guide member and the bore of the sleeve, the first guide member is coaxially provided in a bore of the cap, the second guide member is coaxially provided in the cylinder bore and has a first bore at its front side and a second bore at its rear side, and the sleeve is coaxially fitted into the bore of the cap at its rear end and is coaxially fitted into the second bore of the second guide member at its front end.

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.

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 servo apparatus capable of regulating the output accompanying the activation of an actuator to the maximum output or less includes a housing, movable walls located within the housing, a power piston, an input member, a valve mechanism, an output rod, a reaction disc and an actuator. A rear member forming part of an input member is able to move forward by a predetermined stroke with respect to a front member forming part of the input member so that the input member can be moved backward by the reaction disc in accordance with the activation of the actuator to cut off communication between rear chambers and the atmosphere.

Abstract: A vacuum servo unit or booster for a vehicle brake system includes a housing, movable walls disposed in the housing, a power piston, an input member, an atmospheric pressure valve seat, a negative pressure valve seat, a control valve having an atmospheric pressure seal portion and a negative pressure seal portion, an output rod, a reaction disc, and an actuator. The vacuum servo booster is designed so that the force produced from the output rod varies with the driving force of the actuator upon activation of the actuator.

Abstract: A brake master cylinder which prevents a contact between a projection of a spring retainer and a stopper of a sleeve when a piston is suddenly retracted by an operation of a pressure applying device of a brake system or by an air relieving operation to offer a high reliability without deformation and damages of the spring retainer and the sleeve. A groove extended in axial direction is provided on the sleeve. A distance between a rear end surface of the groove and a radial projection of a first spring retainer when the brake is not applied corresponds to the total of a distance of a retracting distance of a second piston from the position defined by the non-braking operation to a position where a piston port and an opening of a reservoir communication conduit are overlapped and a predetermined additional distance.

Abstract: A vacuum type brake booster for a vehicle is capable of compensating for inadequacy of the force with which a driver steps on a brake pedal during emergency braking whereby a reaction force corresponding to the output of the booster is applied to the brake pedal. A good brake pedal operation feeling is thereby obtained in both the outward and return strokes of the brake pedal and during when the booster has been switched to normal braking and when it has been switched to emergency braking.

Abstract: A pressure generator having a more efficient design and simple construction, and providing improved assembly efficiency and reduced cost includes a housing, a power piston which divides the inside of the housing into front chambers and rear chambers, an input member, a valve mechanism, an output rod, an auxiliary movable wall, an auxiliary variable pressure chamber, an electromagnetic valve unit, a master cylinder and a piston. The auxiliary variable pressure chamber is bounded by an auxiliary movable wall and a first movable wall.

Abstract: A vacuum servo apparatus in which, in a performance diagram having an input coordinate axis perpendicular to an output coordinate axis, the normal operation is represented by a first operating line and, after a plunger member is moved by a solenoid so that movement of the plunger member with respect to a transmission member is controlled, the operation is represented by a second operating line following additional jump biasing force to be supplemented and generated is appropriately set and an output of the apparatus is designed to be faster during the return stroke for straightforwardly reflecting the intention of the driver.