Abstract: A booster as may be used in a brake of an automobile is disclosed, which permits the generation of sounds during the suction stroke when pressure fluid is introduced into a variable pressure chamber to be reduced. The inner surface of a valve body, which defines the variable pressure passage is formed as an uneven surface. This improves the muffler effect without degrading the response of the booster.

Abstract: An improvement of a retainer which constitutes a valve mechanism for booster is disclosed. The retainer is used to secure the rear end of a valve element against a tubular terminal end of a valve body by abutment. The retainer comprises a tubular holder supporting the inner peripheral surface of the rear end and urging its outer peripheral surface into tight contact with the inner peripheral surface of the tubular terminal end, a securing portion, disposed rearward of the tubular holder and extending radially outward to be secured to the inner peripheral surface of the tubular terminal end, an anti-withdrawal portion disposed forwardly of the tubular holder and projecting radially outward, and a tapered portion disposed forwardly of the anti-withdrawal portion and extending radially inward and axially so as to be narrowed into a conical configuration. The construction, in particular, the provision of the tapered portion, facilitates fitting the rear end around the outer periphery of the tubular holder.

Abstract: An automatic brake booster having the functioning of an automatic brake, or more specifically, an improvement of bellows contained in a shell thereof is disclosed. The bellows comprises a stepped tubular member having portions of different diameters, namely, a reduced diameter, a medium diameter and an increased diameter. By using a reinforcing ring having a rigidity in the step, an expansion to increase the diameter of the bellows when the atmosphere is introduced into the internal space of the bellows can be prevented. Different diameters of the portions of the bellows allows the likelihood to be minimized that an output loss of the brake booster may be caused by contact of bellows portions to each other as the bellows is axially shrunk. As compared with an accordion-like bellows, the stepped tubular bellows can utilize a simplified die assembly and manufacturing steps and thus can be manufactured inexpensively.

Abstract: A first seat of a valve element which forms a vacuum valve is axially spaced from a second seat of the valve element which forms an atmosphere valve. The diameter of the first seat is reduced so as to be on the same order as the diameter of the second seat. This allows the load which must set into a spring that is used to maintain a hermetic seal around the first seat to be reduced, in turn allowing an input which must be applied to initiate the operation of the brake booster to be reduced.

Abstract: A butterfly valve of the present invention comprises holes formed in the side wall of a housing having a fluid passage, bushings pressed into the holes, a shaft of valve body inserted into the bushings to rotatably support the valve body, a step surface facing the upper stream which is formed at a substantially semi-circular portion on the peripheral wall of the fluid passage, and a step surface facing the lower stream which is formed at another substantially semi-circular portion thereon, the peripheral end surfaces of the valve disc being brought into contact with the step surfaces, wherein the shaft is arranged by being offset to the downstream side with respect to the valve disc.

Abstract: An improvement of a valve mechanism used in a brake booster is disclosed. A valve element comprises a first and a second annular member, both formed of a metal and which are connected together in an axial orientation, and an elastic deformation which is connected to the rear side of the second annular member. A rubber piece mounted on the first annular member defines a first seat area, and a rubber piece mounted on the second annular member defines a second seat area. With this construction, a spring which is used to urge either seat area of the valve element into seating engagement with the respective valve seat may be compressed to a lower load than in the prior art, thus allowing an input required to initiate the operation of the brake booster to be reduced.

Abstract: In a brake booster of the present invention, a valve plunger (20) rapidly moves forward to come into contact with a shaft portion (33a) of a first piston (33) and then presses the first piston (33)to quickly move forward according to the pedal pressure developed by quickly pedaling a brake pedal during emergency braking. Therefore, before an output shaft (32) outputs, i.e., before pressure is developed in a first fluid chamber (36) filled with fluid, the front end of a second cup packing (39) passes an open end of a first fluid path (31) formed at the first piston (33) side. As a result, the communication between the first fluid chamber (36) and the second fluid chamber (37) is permitted through the first fluid path (31) and a second fluid path (34) so that the fluid within the first fluid chamber (36) flows to the second fluid chamber (37), thereby stopping a reaction mechanism of the pressure in the first fluid chamber (36) and allowing the full load output of the brake booster (1) all at once.

Abstract: An improvement of a valve mechanism used in the booster is disclosed. A first and a second valve seat are formed so as to face forward while a valve element is disposed so as to face rearward in opposing relationship with both valve seats. Thus, the both valve seats and the valve element are disposed in an arrangement which is opposite from that used in a conventional valve mechanism. Such an arrangement allows the atmosphere valve to be located radially outward of the vacuum valve, thus permitting the diameter of the atmosphere valve to be increased as compared with a conventional booster. This enables the operational response of the booster to be improved.

Abstract: A main servo valve 4 is switched in response to a relative angular displacement between an input and an output shaft for supplying an operating oil discharged from a pump to or displacing such operating oil from a power cylinder 6. An auxiliary servo valve 10 is disposed between the input and the output shaft and is connected in parallel relationship with the main servo valve 4 so as to be operated jointly therewith. A vehicle speed responsive valve 16 which opens or closes a flow path in accordance with the vehicle speed is disposed upstream of the auxiliary servo valve 10. The pump comprises a pair of pumps 2, 12 of smaller size. At low speeds, the speed responsive valve 16 is closed, and the oil discharged from the pair of pumps 2, 12 are merged to be introduced into the main servo valve 4. As the vehicle speed increases, the speed responsive valve 16 is gradually opened, and at a vehicle speed above a given value, one of the pumps, 12, ceases to operate.

Abstract: A key member has an engaging portion, which is engaged with an annular groove formed in a valve plunger to prevent the valve plunger from coming off from a valve body. On the rear side of the key member, the valve body has a guide portion which is adapted to slidably guide the valve plunger. Axial passages are formed around the guide portion which form a variable pressure passage together with a radial passage. The key member is inserted in the radial passage in such a manner that its rear end face abuts against the end face of the guide portion. The distance between the engaging region of the key member and the valve plunger and the abutting portion of the key member and the valve body is decreased, so that the bending moment applied to the key member is decreased. This feature makes it possible to decrease the thickness of the key member and accordingly the weight of the latter.

Abstract: An improvement of a valve mechanism for brake booster is disclosed. According to the invention, a valve mechanism for booster comprises a first valve seat formed on a valve body, a first valve element adapted to be seated upon the first valve seat, a second valve seat formed on a rear side of a valve plunger, and a second valve element adapted to be seated upon the second valve seat. The first valve element is urged rearwardly by a first spring, whereby a rear end of the first valve element is maintained in abutment against the second valve element while maintaining a hermetic seal therebetween. The second valve element is urged toward the second valve seat by a second spring having a resilience greater than that of the first spring. The diameter of a first seat area S1 where a contact occurs between the first valve seat and the first valve element is substantially equal to the diameter of a second seat area S2 where a contact occurs between the second valve seat and the second valve element.

Abstract: A booster as may be used in a brake of an automobile is disclosed, which permits the generation of sounds during the suction stroke when pressure fluid is introduced into a variable pressure chamber to be reduced. The inner surface of a valve body, which defines the variable pressure passage is formed as an uneven surface. This improves the muffler effect without degrading the response of the booster.

Abstract: A booster as may be used in a brake of an automobile is provided. Specifically, an improvement of means for sealing between a stepped tubular portion formed on the rear side of a shell and a tubular terminal end of a valve body which extends therethrough is provided. According to the invention, an annular seal member and a bearing are sequentially fitted inside the stepped tubular portion of the shell from the front side and their inner peripheral portions are disposed in sliding contact with the tubular terminal end of the valve body. A plurality of projections are formed on either end face of the seal member or the bearing which opposes each other around its outer periphery. The provision of such projections is effective to prevent the seal member from being disengaged from the step of the stepped tubular portion in the rearward direction.

Abstract: In a brake system with an automatic braking mechanism of the present invention, a master cylinder pressure developed by pedaling a brake pedal 1 is supplied to wheel cylinders through first and second brake paths 6,7, first and second center valves 26', 26 and first and second outlets 24', 24 of an automatic broke actuator 8 so that the normal brake is actuated. An electronic control unit (ECU) 40 actuates a thrust generator 38 and thus an automatic braking signal pressure is developed, whereby first and second small-diameter pistons 18', 18 and first and second large-diameter pistons 16', 16 are moved forward to close the first and second center valves 26', 26 to develop pressures which are supplied to the Wheel cylinders, with the result that the automatic brake is actuated.

Abstract: A braking unit includes an intensifier mechanism for intensifying a braking liquid pressure of a master cylinder upon failure of a liquid pressure booster. The braking unit comprises the intensifier mechanism for intensifying the braking liquid pressure of the master cylinder when actuated, and a control valve which makes the intensifier mechanism operable upon failure of the liquid pressure booster. The control valve comprises a valve member which is urged by a spring tensioned with a given load and which is urged in the opposite direction from the spring by a liquid pressure of a power chamber of the liquid pressure booster. The valve member makes the intensifier mechanism operable whenever the resilience of the spring exceeds the urging force produced by the liquid pressure in the power chamber of the liquid pressure booster. This prevents an operational lag of the intensifier mechanism in the event the liquid pressure booster fails.

Abstract: A brake booster, specifically, an improvement of a valve mechanism for booster is disclosed. According to the invention, the rear side of a curved portion of a valve element is surrounded by a retainer to be interrupted from the atmosphere. This prevents the atmospheric pressure from acting upon the curved portion of the valve element owing to the presence of the retainer.

Abstract: To restrain the swinging of a movable displaceable cam ring and a spool of a control valve and to suppress pulsation on the discharge side of a variable displacement pump. In the variable displacement pump, a variable metering orifice (40) is provided midway in discharge-side passages (24, 29, 43, 44, 45) extending from a pump chamber. A spool-type control valve (30) is operated with the fluid pressure on the upstream and downstream sides of the orifice to control the fluid pressure supplied to fluid-pressure chambers around the cam ring in accordance with the flow rate of the fluid discharged from the pump chamber. A single or multistage throttle portion including throttles (50, 51, 52) is provided in at least one of fluid passages (46, 47) for communicating the upstream side of the orifice to one chamber of the valve, and fluid passages (35, 19b) for communicating the one chamber to the first fluid-pressure chamber as the valve operates.

Abstract: An object of the present invention is to decrease the machining cost and to improve the productivity. A liquid pressure control device (21) for load responding brake comprises a valve mechanism (25), which is slidably disposed in a housing (22), for decreasing the liquid pressure of a master cylinder in a predetermined proportion and transmitting the liquid pressure to a rear wheel brake cylinder by the movement of a plunger (24) operated in response to the liquid pressure from the master cylinder; and a load sensing mechanism (27) in which a load depending on the movable load of a vehicle is applied to the plunger (24) so as to move the pressure decrease operation start point of the valve mechanism (25). The housing (22) is formed by cutting a long material (50) formed by extrusion or drawing to a predetermined length and then by machining the cut material (51).

Abstract: An object of the present invention is to provide a master cylinder in which the buckling of spring is prevented and the packing is not damaged. To achieve this object, in a master cylinder in which a return spring is disposed between the end wall of a cylinder and a piston, and a packing fitted to the piston slides on the inner peripheral wall of the cylinder, the return spring 30 comprises a cylindrical large-diameter coil portion A with a diameter almost in contact with the inner peripheral wall of the cylinder 12 and a small-diameter coil portion B with a diameter enough smaller than the diameter of the inner peripheral wall of the cylinder 12, and the installation length of the small-diameter coil portion B is set so as to be nearly equal to a length of the range in which the packing 24 slides.

Abstract: An actuator which causes an input shaft to move forward is disposed within the inner periphery of a valve body at its rear end. When a brake booster is inoperative, an atmospheric pressure is introduced into a pressure chamber of the actuator, but when a flow path switching valve is operated to introduce a negative pressure into the pressure chamber as required, a pressure differential is developed across a piston of the actuator, thus driving the piston forward. This allows the input shaft to be driven forward, whereby the brake booster can be operated without depressing a brake pedal. Since the atmosphere is introduced into the pressure chamber of the actuator when the brake booster is inoperative, a fracture or disengagement of a conduit which is connected to the pressure chamber cannot develop a pressure differential across the piston of the actuator, thus preventing the actuator from operating.