Abstract: A cup seal 21 includes a base portion 21a, an inner circumferential lip 21b slidingly contactable with a plunger 19 and an outer circumferential lip 21c contactable with the bottom surface 26a of the seal groove 26. Further, on the cup seal 21, there are provided elastic projections 21d projecting from the outer circumferential side leading end of the inner circumferential lip 21b toward the cylinder hole bottom portion. The length of the cup seal 21 from the base end face 21e to the leading end portions 21f is set longer than axial length of the seal groove 26. When the cup seal 21 is fitted into the seal groove 26, force is imparted on the inner circumferential lip 21b toward the cylinder hole inner circumferential direction to energize the inner circumferential lip 21b toward the piston all the time.

Abstract: A cup seal 21 includes a base portion 21a, an inner circumferential lip 21b slidingly contactable with a plunger 19 and an outer circumferential lip 21c contactable with the bottom surface 26a of the seal groove 26. Further, on the cup seal 21, there are provided elastic projections 21d projecting from the outer circumferential side leading end of the inner circumferential lip 21b toward the cylinder hole bottom portion. The length of the cup seal 21 from the base end face 21e to the leading end portions 21f is set longer than axial length of the seal groove 26. When the cup seal 21 is fitted into the seal groove 26, force is imparted on the inner circumferential lip 21b toward the cylinder hole inner circumferential direction to energize the inner circumferential lip 21b toward the piston all the time.

Abstract: In a vacuum booster in which a reaction force mechanism is interposed between an input rod and a valve cylinder connected integrally with a booster piston, and an output rod, a valve piston is fitted onto an input piston connecting the input rod and the reaction force mechanism to be slidably movable forward from a predetermined retreat position with respect to the input piston, the valve piston is biased to the retreat position by a set spring, and locking device is provided between the valve piston and the valve cylinder to lock the valve piston at the valve cylinder thereby holding an atmosphere introduction valve seat in an open state at the time of emergency braking when the input piston moves forward by a predetermined number of strokes ahead of the valve cylinder. Thus, while a delay in atmosphere introduction into the operating chamber is eliminated irrespective of normal braking or emergency braking, the output is allowed to reach a servo limit point earlier and held at the time of emergency braking.

Abstract: In a vacuum booster in which a reaction force mechanism is interposed between an input rod and a valve cylinder connected integrally with a booster piston, and an output rod, a valve piston is fitted onto an input piston connecting the input rod and the reaction force mechanism to be slidably movable forward from a predetermined retreat position with respect to the input piston, the valve piston is biased to the retreat position by a set spring, and locking device is provided between the valve piston and the valve cylinder to lock the valve piston at the valve cylinder thereby holding an atmosphere introduction valve seat in an open state at the time of emergency braking when the input piston moves forward by a predetermined number of strokes ahead of the valve cylinder. Thus, while a delay in atmosphere introduction into the operating chamber is eliminated irrespective of normal braking or emergency braking, the output is allowed to reach a servo limit point earlier and held at the time of emergency braking.

Abstract: In a control valve of the vacuum booster, a valve portion is fitted with a valve cylinder to be slidably contacted with an inner wall of the valve cylinder, to form within said valve cylinder, a front annular chamber closed by a front face of the valve portion when the valve portion is seated on a vacuum introduction valve seat, and a read annular chamber, to which the rear of the valve portion is faced. The front annular chamber communicates with a first port, and the rear annular chamber communicates with a second port. An input rod is moved forward to separate the valve portion from an atmosphere introduction valve seat and to seat it on the vacuum introduction valve seat. Then, the valve portion is urged in accordance with the set load of a valve spring and the pressure difference between the front and rear annular chambers.

Abstract: A fluid injection port 10 is formed in the upper portion of a reservoir 5 at the front side of a vehicle. A first union hole 13 and a second union hole 14 are formed in a bottom wall 6g, and a level detector 15 is provided in a fluid chamber 4. The fluid chamber 4 is divided by partition walls 6i and 6j into a first fluid chamber 4a, a second fluid chamber 4b and a third fluid chamber 4c. The fluid injection port 10 communicates with the first fluid chamber 4a, the first union hole 13 communicates with both the first and the second fluid chambers 4a and 4b, and the second union hole 14 and the level detector 15 are placed in the third fluid chamber 4c. The second fluid chamber 4b and the third fluid chamber 4c communicate with each other via an opening 19.

Abstract: In a control valve of the vacuum booster, a valve portion is fitted with a valve cylinder to be slidably contacted with an inner wall of the valve cylinder, to form within said valve cylinder, a front annular chamber closed by a front face of the valve portion when the valve portion is seated on a vacuum introduction valve seat, and a read annular chamber, to which the rear of the valve portion is faced. The front annular chamber communicates with a first port, and the rear annular chamber communicates with a second port. An input rod is moved forward to separate the valve portion from an atmosphere introduction valve seat and to seat it on the vacuum introduction valve seat. Then, the valve portion is urged in accordance with the set load of a valve spring and the pressure difference between the front and rear annular chambers.

Abstract: A fluid injection port 10 is formed in the upper portion of a reservoir 5 at the front side of a vehicle. A first union hole 13 and a second union hole 14 are formed in a bottom wall 6g, and a level detector 15 is provided in a fluid chamber 4. The fluid chamber 4 is divided by partition walls 6i and 6j into a first fluid chamber 4a, a second fluid chamber 4b and a third fluid chamber 4c. The fluid injection port 10 communicates with the first fluid chamber 4a, the first union hole 13 communicates with both the first and the second fluid chambers 4a and 4b, and the second union hole 14 and the level detector 15 are placed in the third fluid chamber 4c. The second fluid chamber 4b and the third fluid chamber 4c communicate with each other via an opening 19.

Abstract: In a vacuum booster in which a holding tube is fitted in a cylindrical valve case, and the base end portion of a valve member is fitted in an annular holding groove formed in the outer surface of the front end portion of the holding tube in such a manner as to be sealingly engaged with the inner surface of the cylindrical valve case, the inner surface of the cylindrical valve case is gradually larger in diameter towards the open rear end thereof, while the outer surface of the holding tube is tapered towards the rear end thereof, and guiding grooves and arcuate engaging grooves are formed in the inner surface of the cylindrical valve case in such a manner that each guiding groove is axially extended a predetermined distance from the open end of the cylindrical valve case, and each engaging groove is extended circumferentially of the cylindrical valve case, while guiding pawls and engaging pawls are formed on the outer surface of the holding tube in such a manner that the guiding pawls are slidably engaged wit

Abstract: In a tandem type vacuum booster, the inner peripheral end of a front booster piston and the inner peripheral bead of a front diaphragm are clamped between a front end of a sleeve fitted over the outer periphery of a piston boss and a flange provided on the piston boss and are thereby fixed to a front portion of the piston boss, while the inner peripheral end of a rear booster piston and the inner peripheral bead of a rear diaphragm are clamped between a stopper member mounted on the piston boss and a rear end of the sleeve and are thereby fixed to a rear portion of the piston boss. A first port for communicating the front and rear working chambers with the control valve, and a second port for communicating the front and rear vacuum chambers with the control valve extend through both the piston boss and the sleeve, and communication between both the ports is inhibited by a single annular sealing member mounted at an axially intermediate portion of a junction surface between the piston boss and the sleeve.

Abstract: A peripheral wall of a rectangular pedestal is formed bulged on the rear wall of a booster shell and attached to a vehicle body by four connecting bolts. The wall is comprised of a pair of shorter side walls parallel to shorter sides of the rectangle connecting axes of the four connecting bolts, a pair of longer side walls each bent so as to be gradually separated farther from the corresponding longer side of the rectangle at a central portion than at an end portion thereof, and four arcuate corner walls with each corner wall connecting the adjacent shorter and longer side walls. Thus, an intermediate portion of the longer side wall of the pedestal is increased in rigidity, so that an increased burden of stress can be imposed on such longer side wall. This moderates the stress concentration around the corners, thereby improving the durability of the booster shell.

Abstract: A pedestal formed bulged on a rear wall of a booster shell and attached to a vehicle body by four connecting bolts has a pheripheral wall whose length from a general wall of the rear wall of the booster shell to a seating face wall of the pedestal becomes larger toward each of corners of the pedestal. This ensures that the concentration of a stress produced at each of the corners of the peripheral wall of the pedestal can be moderated, thereby providing an improvedment in durability of the rear wall of the booster shell and suppressing an increase in internal volume of the pedestal to the utmost.

Abstract: In a tandem type booster, the inner peripheral end of a front booster piston and the inner peripheral bead of a front diaphragm are clamped between a front end of a sleeve fitted over an outer periphery of the piston boss and a flange provided on the piston boss, so that they are connected to a front portion of the piston boss, and a rear booster piston and the piston boss are coupled to each other in a bayonet manner by retaining pawls formed on a inner peripheral end of a rear booster piston and retaining grooves provided in the outer periphery of the piston boss. The rear booster piston, the sleeve and the piston boss are engaged with one another while preventing relative rotation therebetween, and an inner peripheral bead of a rear diaphragm is clamped between the rear booster piston and a set ring and connected to a rear portion of the piston boss.

Abstract: A vacuum booster includes a booster piston having a front surface facing a vacuum chamber, a diaphragm superposed on the rear surface of the booster piston and having a rear surface facing a working chamber adapted to be selectively put into communication with the vacuum chamber or the atmosphere, a piston boss carried on a central portion of the rear wall of the booster shell for a longitudinal reciprocal movement and provided with an annular step with which an inner peripheral bead of the diaphragm engages from the rear, and an annular stopper retained on the piston boss to abut against the inner peripheral bead from the rear. The stopper includes an annular retaining portion at an outer periphery thereof to project forwardly which has a curved front end, and the inner peripheral bead of the diaphragm is formed into a ring shape projecting rearwardly to have its outer periphery engaged with the stopper retaining portion.

Abstract: A tandem-type vacuum booster comprises a partition plate fixedly mounted in a booster shell for partitioning the interior of the booster shell into a front shell chamber and a rear shell chamber; a front booster piston dividing said front shell chamber into a front-side fore vacuum chamber connected to a vacuum pressure source and a rear-side fore operating chamber; a rear booster piston dividing the rear shell chamber into a front-side hind vaccum chamber and a rear-side hind operating chamber, the both booster pistons being interconnected through a piston boss slidably carried on the partition plate and connected to an output rod; a valve tube integrally connected to the piston boss to project from a rear end of the piston boss and slidably supported on a rear wall of the booster shell; a first port permitting the interior of the valve tube to communicate with both the vaccum chambers; a second port permitting the interior of the valve tube to communicate with both the operating chambers, the first port bei

Abstract: A master cylinder comprising a cylinder body having a bore, a plunger in the bore, a bearing secured to the rear end of the cylinder body and slidably supporting the plunger, a sleeve fitted in the cylinder bore adjacent to the bearing and receiving the plunger therein, and stopper means between the sleeve and plunger for defining a retreat limit of the plunger, wherein the cylinder body is connected to a booster shell with a sealing member therebetween, and the rear end of the plunger protrudes into the booster shell for connection to an output rod of the booster, the sealing member having a lip placed in close contact with the outer peripheral surface of the plunger. An annular set screw is threadedly mounted to the rear opening of the cylinder bore to fix the sleeve while surrounding the plunger, so that the lip of the sealing member is received in a tool-engaging recess provided on the set screw. Alternatively, the plunger comprises a front plunger and a rear plunger.

Abstract: A vacuum type booster which includes a booster piston reciprocatively movable in a shell, a valve sleeve for a control valve fitted to the booster piston and having a disengagement preventive flange superposed on the piston, and a clamp plate engaged with pawls formed by cutting and bending portions of the booster piston for clamping the flange to the booster piston. The booster piston includes pairs of reinforcement ribs which cross the turning direction of the clamp plate and sandwich cutout holes resulting from formation of the pawls. A pair of the ribs on the rear side of the turning direction of the clamp plate permit the clamp plate to turn in a direction for engagement with the pawls and inhibits the clamp plate from turning in the disengaging direction. A space is provided between the outer peripheral part of the disengagement preventive flange and an engagement piece jointing part of the clamp plate body.