Abstract: A brake booster is disclosed which functions as an automatic brake as required. Bellows is disposed within a constant pressure chamber of the brake booster, and has a front end which is connected, by a first support member, to a bulge which is formed in the axial portion of a shell. A seal member is connected to the outer periphery of the first support member, and is held in abutment against the wall surface of the shell at a location radially outward of an inlet for the atmosphere. A communication channel is formed by a space between the first support member and an opposing wall surface of the shell and the bulge and the like. A communication is established between the internal space of the bellows and the inlet through the communication channel. This construction allows the overall length of the brake booster to be reduced as compared with the prior art in which a spacer is provided outside the shell.

Abstract: According to the invention, the booster is not provided with a brake reaction transmission mechanism, and hence a reaction cannot be transmitted to a brake pedal. On the other hand, a pseudo-reaction imparting means is provided to impart a pseudo-reaction of suitable magnitude which depends on the degree of depression of the brake pedal. The pseudo-reaction imparting means is arranged so that when the brake pedal is depressed relatively rapidly, a relatively smaller braking reaction is imparted than during a usual depression. With this arrangement, the transmission of an abnormally high braking reaction to a driver which is experienced in a conventional booster during a quick braking operation due to an operational rag of the booster is avoided.

Abstract: A brake assembly (10,210,310,410) with a master cylinder totally integrated into a brake assembly. A housing for the brake assembly has an interior separated by a movable wall (30,30') to define first (32,32') and second (34,34') chambers. End element (18) secured to the housing has projection (17) located in the first chamber (32,32') with a plurality of passages (98,100) for communicating fluid to a brake system. A cylindrical member (60, 260,360,460) has a blind bore (74) that extends from a first end (70,264,364) toward a second end (72,266,366). The cylindrical member (60,260,360,460) slidably and sealingly engages the end element (18) to connect the blind bore (74) with the plurality of passages (98,100). A reaction member (120) is located between the hub member (46) and the cylindrical member (60, 260,360,460).

Abstract: An actuator system having a motor that drives a pneumatic spool valve to a known position based upon the number of step commands delivered to it. Valve ports or passages uncovered by the net position difference between the spool valve and a piston create gas flow to or from a control chamber. This gas flow causes a pressure differential across the face of the piston, inducing the piston to follow the spool valve. In this two-stage system, the piston acts as a force amplifier so that large forces and/or inertias may be actuated by positioning the motor. During steady state conditions, the piston achieves the same position as the spool valve is. Proportional control and very accurate positioning of the piston are provided without active position or position rate feedback control.

Abstract: A control valve is disclosed which is capable of supplying a required control pressure to an actuator such as a brake booster, for example. The control valve includes a valve mechanism within a housing, and the valve mechanism comprises a piston which is associated with a solenoid. When the solenoid is excited, the piston is driven for movement to switch a flow path within the housing. In this manner, the atmosphere, acting as a control pressure, is introduced into a variable pressure chamber defined within the housing. The atmosphere which is introduced into the variable pressure chamber is arranged to push back the piston, so that a control pressure which depends on the magnitude of a current passing through the solenoid can be generated within the variable pressure chamber. As compared with a prior art arrangement, the control valve of the invention reduces the cost of the entire arrangement, and allows a piping arrangement for pressure fluid to be simplified.

Abstract: The present invention is directed to a vacuum servo unit which is characterized in that a movable power piston has an outer cylindrical portion, an inner cylindrical portion, and a connecting portion for connecting an inner cylindrical portion to an outer cylindrical portion, the connecting portion has an input side end portion being shaped to be convex towards an input side so that a width in a peripheral direction thereof decreases towards the input side, a first path is provided in the connecting portion for communicating the variable pressure chamber with an inside space of the inner cylindrical portion, a second path is provided in the movable power piston for communicating the constant pressure chamber with the space between the outer cylindrical portion and the inner cylindrical portion. Accordingly, this vacuum servo unit can smoothly decrease the servo force for the movable power piston and the output force and restrain the production of the sound.

Abstract: A pneumatic brake booster (1) having a piston (5) which is responsive to first and second sources of air pressure. The booster (1) has a rigid casing (3) which is divided by a leaktight movable partition (4) into first (3a) and second (3b) chambers. The partition (4) including a pneumatic piston (5) which carries a control valve (7). A difference in pressure established between the first (3a) and second (3b) chambers causes the piston (5) to move within the casing (3). The inside (50) of the piston (5) is separated from the second source of air pressure by an impurities filter (14). A closing-off means (15,17) is located between an opening to the inside (50) of the piston (5) and the second source of air pressure to control an air inlet path which bypasses the impurities filter (14).

Abstract: A vacuum brake booster having sound absorbing members affixed to the front and rear shells to attenuate sounds caused by air movement in the brake booster. The front shell is joined to the rear shell to define the housing for the brake booster. The housing is divided into a first chamber and a second chamber by a wall structure. The first and second chambers in a first mode of operation are designed to be in communication with a first source of fluid (vacuum) having a first fluid pressure while in a second mode of operation the second chamber is in communication with a second source of fluid (atmospheric air) at a second fluid pressure. In the second mode of operation, a pressure differential is created across the wall structure to produce an output force corresponding to an input force associated with a desired braking application.

Abstract: A pneumatic booster (1) having casing (3) divided by a movable partition (3) into first (3a) and a second (3b) working chambers. The movable partition (4) being urged by a pressure differential derived from a first fluid pressure in the first working chamber (3a) and a second fluid pressure in the second working chamber (3b). The second fluid pressure is communicated to the second working chamber (3b) through the actuation of a shutter (70) by means of a plunger (8). The shutter (70) has freedom of movement with respect to the plunger (8) while being elastically urges against the plunger (8). The shutter (70) is connected to a mass (15) which is set in motion by a movement of the plunger (8). The mass (15) thereafter acts on and moves the shutter (70) away from the plunger (8) to increase the flow of the second fluid pressure to the second chamber (3b).

Abstract: A valve assembly (10) for controlling a pneumatic brake booster comprises a valve housing (16) with a first and a second valve seat (18, 20) as well as with a valve body (26) adapted to be applied to both valve seats (18, 20). In one position of an operating member (24) the valve body (26) is lifted off the first valve seat (18) only, while in another position of the operating member (24) it is lifted off the second valve seat (20). Radially outside the valve housing (16) an annular third valve seat (64) and a control sleeve (60) surrounding the valve housing are arranged, which as an additional valve body can be axially moved by means of the operating member (24) relative to the valve housing (16).

Abstract: A brake apparatus has a good brake operation feel provided by a combination of a link mechanism and a brake booster. The link mechanism changes a lever ratio so that the lever ratio is gradually decreased as a pedal stroke is increased after the pedal stroke reaches a predetermined point. The brake booster increases a rate of increase of an output force so that the rate of increase is increased as an input force is increased. A brake characteristic of the brake apparatus as a whole exhibits a linear relationship relative to the deceleration of the vehicle, the brake characteristic being defined as an inclination of the deceleration against the pressing force input to the link mechanism. One of the link mechanism and the brake booster may be used alone in a brake apparatus to provide their respective effect to a brake apparatus.

Abstract: A pneumatic brake booster for a motor vehicle having a rigid casing (1) with a first shell (10) which points toward the front of the vehicle and a second shell (11) which points toward the rear of the vehicle. At least one through bolt (5) fastened to the front shell (10) and rear shell (11) by respective cohesive forces which joins the front shell (10) to the rear shell (11) in an axial direction by a compressive force which tends to pull the front shell (10) toward the rear shell (11). The cohesive force between the through bolt (5) and the front shell (10) wholly consists of an elastic force exerted by the rigid casing (1) on the through bolt (5) in reaction to the compressive force exerted on the front shell (10) and rear shell (11) by the through bolt (5). The through bolt (5) has a threaded end (50) which passes through the front shell (10).

Abstract: An improvement of an output shaft of a booster is disclosed. An output shaft 23 is formed by a push rod 24 and an adjusting screw 25. The push rod 24 is formed with an axial bore 26 in its distal end, the axial bore including a portion 26b of a reduced diameter which is less than an outer diameter of a threaded section 25C of the adjusting screw. The threaded portion is formed as a self-tapping screw. The adjusting screw includes a guide 25D at a location which is initially inserted into the axial bore before the threaded portion is inserted into the threaded portion. The guide comprises a plurality of annular projections 27 having an outer diameter which is substantially equal to the inner diameter of the axial bore. With this construction, when the guide 25D is fitted into the portion 26b of the axial bore 26 which has a reduced diameter, the axis of the adjusting screw 25 may be brought into alignment with the axis of the push rode 24.

Abstract: An electronic control type brake booster having a brake booster; an air path separately formed from a path to which an engine vacuum pressure of said brake booster is applied; a pressure control valve arranged in the air path and driven by a solenoid valve, said pressure control valve providing a pilot pressure to the air path of said brake booster to control the pressure in the air path to a pressure between atmospheric pressure and the engine vacuum pressure; a wrinkled bellows tube connected to a predetermined portion of said air path connected to the pressure control valve; an operational chamber inwardly formed of a movable wall communicated with the bellows tube; a plunger located at an inside portion of the movable wall and formed with an operational chamber and a further chamber according to an operation of the plunger; an annular element arranged between the plunger and the movable wall; and a hole formed at the upper portion of the annular element and communicating with the further chamber.

Abstract: A pneumatic-controlled device for a vacuum brake booster having a hollow piston which retains a tubular shut-off member. The tubular shut-off member interacts with a stationary seat and a movable seat to define a chamber within the hollow piston when the movable seat is in an actuation position. An orifice formed in the tubular shut-off member places the chamber in communication with a passage defined between the stationary and movable seats to reduce hysteresis experienced by movement of the movable seat.

Abstract: A tandem pneumatic booster having a shell body, the inside of which is divided into two, front and rear, chambers by a center shell. Each chamber includes a negative pressure chamber and a working pressure chamber. A valve body is slidably fitted in the shell body and the center shell with seal members therebetween. The valve body is provided with an air passage for communication between the front and rear working pressure chambers. A valve mechanism is actuated in association with an input shaft to introduce atmospheric air into the front and rear working pressure chambers through the air passage so as to apply thrust to front and rear power pistons. The diaphragm of the front power piston has a bead on an inner periphery thereof. The valve body has a groove on an outer periphery thereof. A portion of the air passage which leads to the front working pressure chamber has a main passage portion extending axially in the valve body, and a bypass extending radially outward from the main passage portion.

Abstract: A pneumatic brake booster (10) and a hydraulic master cylinder (60) are arranged in a series along a common axis (A) to form an assembly which includes a booster housing (12), a power input member (30) and a power output member (40). A mechanical power transmitter (32) is arranged between the power input member (30) and the power output member (40). A sleeve (50) is rigidly attached at a valve housing (22) to enclose a portion of the power output member (40). At the booster housing (12) a master cylinder housing (62) is attached which has a guide (68) facing the power transmitter (32). A primary piston (70) is guided in the master cylinder housing (62) and includes a support (72) for the power output member (40) as well as an extension (74) which extends towards the power transmitter (32) and is guided in the guide (68). The sleeve (50) extends to near this support (72) and is provided with a head portion (52) which bears against the master cylinder (60) via the guide (68) in a radial direction.

Abstract: A hydraulic power booster for a brake apply system includes a mechanically actuated hydraulic booster of compact design that can be integrated in line with a conventional type master cylinder. Additionally, a combination of twin mechanically actuated check valves is arranged to provide a structure with essentially no leakage when the hydraulic booster is at rest and when the hydraulic booster is at poise. A mechanically actuated check valve is normally held open and is positioned in a passageway between the power piston and a fluid reservoir. This check valve is substantially, immediately closed upon the application of force to the brake pedal. Another mechanically actuated check valve is provided in a passageway between the hydraulic power supply and the power piston. This check valve is mechanically opened to supply a selected amount of pressurized fluid to the power piston which generates a selected amount of vehicle braking in response to actuation of the brake pedal.

Abstract: An electronically controlled brake booster for a road vehicle brake system having a housing comprises a vacuum chamber (16) and a servo chamber (14) separated from said vacuum chamber (16) by a movable wall (18), an electromagnetically operatable control valve device (20) which is coupled to said movable wall (18) for common relative movement with respect to the housing of the brake booster and a sensor (32) which, for an electronic control device (ECU), senses operating conditions of the road vehicle brake system and produces signals characteristic for these operating conditions which signals are evaluated by said control device (ECU) for producing drive signals (S.sub.1a, S.sub.1b) for said control valve device (20), wherein the sensor is formed as a pressure sensor (32) and senses at least the pressure (p.sub.AK) prevailing in said servo chamber (14).

Abstract: The present invention is directed to a vacuum servo unit which is characterized in that the negative pressure controlling valve seat is arranged in a position spaced from the atmosphere controlling valve seat in an axial direction, and the atmosphere and the negative pressure controlling seal portions of the control valve are spaced in the axial direction to cooperate with the atmosphere and the negative pressure controlling valve seats. The control valve is in air tightly engagement with an internal surface of the movable power piston at an external surface thereof, and the control valve has a path provided between the atmosphere controlling seal portion and the negative pressure controlling seal portion. Accordingly, when the brake operating member is operated, large quantities of the atmosphere can be introduced to the variable pressure chamber through the clearance between the atmosphere controlling valve seat and the atmosphere controlling seal portion.

Abstract: This boosted braking device comprises a pneumatic brake booster (1) associated with a master cylinder (2) and provided with an automatic control solenoid valve (26), this booster operating according to a mixed reaction principle and comprising a movable pneumatic piston (5) carrying a control valve (7) actuated by a rod (8), as well as a partition (4) which can be moved under the effect of a pressure difference, this movable wall (4) being mounted slidingly with respect to the pneumatic piston (5). The device of the invention makes it possible, with very few elements, to provide automatic braking without disturbing the normal operation of the booster.

Abstract: A pneumatic brake booster having a casing (10) with an axis of symmetry (X-X') divided in a leaktight fashion by a movable wall structure (12) into a front chamber (14) permanently connected to a source of low pressure, and a rear chamber (16). The rear chamber (16) is connected selectively to the front chamber (14) or a source of high pressure by a three-way valve means (36). The three-way valve means (36) is actuated by a control rod (30) capable of pressing, via a front face of a plunger (28), on a rear face of a push rod (56) secured to a reaction disc (58) when a plunger (28) slides in a bore (26) of the movable wall (12). The three-way valve (36) includes a valve element (36) located in a tubular rear part (22) of the movable wall (12) and interacts via of an annular front face (40) with a first annular valve seat (28a) formed on the plunger (28) and with a second annular valve seat (20a) formed on the movable wall (12).

Abstract: A traction control device includes a vacuum booster connected to a master cylinder. The master cylinder is in fluid communication with a driven wheel brake and a non-driven wheel brake via respective first and second solenoid valves. When the brake traction control initiation condition is established, the booster is activated to supply fluid pressure from the master cylinder to the driven wheel brake and the non-driven wheel brake. After elapse of a time from the activation of the booster, the second solenoid valve is closed to prevent a further increase of the brake fluid pressure in the non-driven wheel brake. Thereafter, the brake fluid pressure in the driven wheel brake is adjusted by controlling the first solenoid valve as well as by controlling a fluid pressure pump which is associated with the fluid communication between the master cylinder and the driven wheel brake.

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: 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 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: In a vacuum brake booster including a housing the interior of which is subdivided into negative and variable pressure chambers by means of a movable wall assembled therein, a piston body assembled with the movable wall to be axially movable in the housing, a valve plunger axially slidably coupled within the piston body, a first annular valve element formed on an outer end of the valve plunger, a second valve element formed on an internal cylindrical portion of the piston body, and a control valve assembly having a first annular sealing portion cooperable with the first valve element and a second annular sealing portion united with the first annular sealing portion to cooperate with the second valve element, the first valve element is arranged in a position spaced in an axial direction from the first valve element, and the first and second annular sealing portions of the control valve assembly are spaced in the axial direction to cooperate with the first and second valve elements.

Abstract: A brake booster includes a valve housing, an input rod movably mounted in the valve housing, a main filter, a noise absorbing member, a spring seat, a return spring for biasing the input rod, and a noise shielding member. The main filter, the noise absorbing member, the spring seat, the noise shielding member are fixed on the input rod and move integrally with the latter. The noise shielding member spaced apart from the noise absorbing member reduces the air suction noise.

Abstract: A brake booster having a fluid actuated piston in the form of a diaphragm (5) to which the supply of fluid is controlled by a valve mechanism (8A, 14A, 17), actuated by a driver-operated force input member (16) which acts via a reaction element (19) on an output member (10) providing power assisted input to a master cylinder. The booster includes a force transmission assembly (14,8) providing surfaces through which force is transmitted between the input and output members (16,10). A spring (24) is arranged to yield under a predetermined force to permit relative movement between parts (14) and (8) such as to change the ratio of the operative surface areas and thereby increase the boost ratio.

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: For the purpose of routing an electric cable through the movable wall of the two pneumatic working chambers of an electronically controllable bake booster, comprising a first pneumatic working chamber and a second pneumatic working chamber which are separated by a movable wall, where a simple assembly and a high functional reliability are to be ensured, a cable feed-through for at least one electric cable penetrating the movable wall is provided, with a portion of the cable-feed through penetrating the movable wall, and a holder which limits the movability of the cable feed-through at least in its longitudinal direction, and a seal surrounding the cable feed-through in the area of the movable wall.

Abstract: The invention relates to a pneumatic brake booster comprising a housing (10) which is divided into a vacuum chamber (14) and a working chamber (12), in which a dual valve arrangement (20) having a first valve (24, 26) between the vacuum chamber (14) and the working chamber (12) and a second valve (24', 26') between the ambient atmosphere (A) and the working chamber (12) is arranged at the housing (10), in which the valve arrangement (20), in an inoperative position, allows having pressure levels in the vacuum chamber (14) and in the working chamber (12) which are different from the ambient atmospheric pressure (A), and in an operative position, keeps the vacuum chamber (14) sealed off and allows communication between the ambient atmosphere (A) and the working chamber (12), wherein, in normal operation, the first valve (24, 26) and the second valve (24', 26') are actuatable by a common actuating rod, and, in a controlled operation, an electromagnetic actuator (40, 46) which is independent of the actuating rod

Abstract: A pneumatic servo for assisting braking. The servo has a casing with an axis of symmetry which is divided in leaktight fashion by a movable wall structure into a front chamber and a rear chamber. The front chamber is permanently connected to a source of partial vacuum while the rear chamber is connected selectively to the front chamber and to air in the surrounding environment by a three-way valve. A sleeve divided an annular bore located in a projection that extends through the movable wall through the casing into a static volume and a concentric annular volume. The sleeve engages the projection to position the three-way valve in the bore. A return spring located in the static volume engages the control rod while an end plug engages the sleeve to seal the static volume from the surrounding environment. The annular volume being is respectively connected by first and second openings to the surrounding environment and bore.

Abstract: A tandem vacuum booster includes a front shell and a rear shell which are connected to each other to form a housing, a front movable wall having an outer circumferential portion that is fit in a fluid-tight manner between the front shell and the rear shell, and a rear movable wall having an outer circumferential portion that is fixed to the rear shell. A fixed wall has an outer circumferential portion that is fit between the front movable wall and the rear shell, with the fixed wall including a bent portion which presses the outer circumferential portion of the rear movable wall to the rear shell.

Abstract: A pneumatic brake booster having a casing (10) with an axis of symmetry (X-X') divided in a leaktight fashion by a moving wall structure (12) into a front chamber (14) and a rear chamber (12). The front chamber (14) is permanently connected to a source of low pressure and the rear chamber (12) is connected selectively to the front chamber (14) or to a source of high pressure by a three-way valve (36). The three-way valve (36) is actuated by a control rod (30) capable of bearing via a front face of a plunger (28) on a rear face of a push rod (48) secured to a reaction disk (49). The plunger (28) slides in a bore (26) of the moving wall structure (12) in response to an input force applied by an operator.

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: A vacuum servo unit which is designed so that when a valve member associated with the plunger that is connected to an input member is out of engagement with the plunger, the power piston moves due to the pressure differential between a variable-pressure chamber and a constant pressure chamber for boosting the force to the input member, is provided with an arrangement for inhibiting or preventing inclination of the input member. The arrangement includes a plurality of projections extending outwardly from the input member, and a plurality of slots formed in the plunger for receiving the projections.

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: An integrated master cylinder and vacuum power booster provides a brake apply system wherein the master cylinder and power booster are structurally and functionally combined together to provide a uniquely packaged system. The integral system includes a master cylinder housing having a tubular extension that carries the power booster housing with at least two operating chambers. A power piston is movable by variable pressure levels between the two chambers. The power piston cooperates with a translating element carried within the tubular extension to communicate sliding movement of the power piston to the master cylinder piston.

Abstract: A pneumatic servo for assisting with braking. The servo has a casing with an axis of symmetry and is divided in a leaktight fashion by a movable wall structure into a front chamber which is permanently connected to a source of partial vacuum and a rear chamber connected selectively to the front chamber or to the surrounding environment by a three-way valve. The three-way valve is actuated by a plunger which slides in a bore in the movable wall in response to an axial control rod. The control rod is subjected to the action of a return spring located in an annular space between the control rod and a tubular part on the rear of the wall structure which extends or projects through the casing. The three-way valve being located in this tubular part and includes a shutter element which interacts via a first annular surface with a first valve seat formed on the plunger and via a second annular surface with a second valve seat formed on the movable wall.

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: A pneumatic brake booster with a booster housing part includes a vacuum chamber and a working chamber separated therefrom by a movable wall, and a valve body part including a control valve assembly and an electromagnet assembly. The control valve assembly can be actuated both by an actuation rod as well as by the electromagnet assembly, in order to make connections between the vacuum chamber and the working chamber, or between the working chamber and the ambient atmosphere. To improve the heat dissipation and to simplify the assembly the valve body part comprises several separate portions at least the first portion of the valve body part being at least partially designed as a magnetic return of the electromagnet assembly and is coupled with the second portion of the valve body part.

Abstract: A brake booster having separately formed valve bodies for the vacuum valve and the atmospheric valve, which minimizes an invalid portion of the operation stroke. There is provided a cylindrical inner member 800 air-tightly and slidably fitted in the internal bore of a hub portion 52 of a servo piston 50. The inner member 800 is biased backwardly by a spring 850. The inner member 800 has at its front end a valve body 510 of the vacuum valve 500. The rear end of the inner member 800 is caused to be abutted with the atmospheric air valve body 710 side of the atmospheric air valve 700 under the effect of force of the spring 850.

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 vacuum brake power booster for automotive vehicles includes a booster housing whose interior is subdivided into a vacuum chamber and a working chamber by a moveable wall. A control housing carries the moveable wall and accommodates a control valve which controls a pressure differential acting upon the moveable wall. The control valve has at least two sealing seats cooperating with an elastic valve member and is operable by an actuating rod. One of the sealing seats is operable, irrespective of the actuating rod, by an electromagnet whose armature is in force-transmitting interaction with one of the sealing seats. An electrical switching apparatus is also included, the control signals of which influence the current supply of the electromagnet thereby enabling its deactivation. The switching apparatus are operable by a relative movement between a valve piston and the control housing.

Abstract: The present invention is directed to a vacuum servo unit, wherein a variable pressure chamber is capable of communicating with the atmosphere through a clearance which is defined between an air valve member slidably mounted on an input member and a seal member provided in a cylindrical member, and wherein the variable pressure chamber is capable of communicating with a constant pressure chamber through a clearance which is defined between a vacuum valve member and a seal portion of a control valve member. Accordingly, when the air is introduced from the clearance between the air valve member and the seal member in the condition where the seal portion of the control valve member is in contact with the vacuum valve member, the control valve member is biased toward the vacuum valve member by the pressure difference between the negative pressure and the atmospheric pressure.

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 pneumatic servo for brake boosting intended for motor vehicles. The servo having a rigid casing divided into at least two chambers by a flexible membrane. The casing being composed of at least first and second elements and having at least two tie rods for joining the first and second elements together in an inward axial direction. The tie rods respond to any force which tends to move the first and second elements apart. At least one of the tie rods is compressible should an external force be applied to move the first element toward the second element to prevent communication of the external force through the second element into an operator compartment.

Abstract: A pneumatic brake booster having a casing (10) with a piston located therein. The piston has a hub (22,22') with a tubular part (24,24'), a portion of which extends in a sealed fashion through the casing (10). The hub (22,22') has an annular groove (29) which receives an internal peripherial bead (19) of a rolling seal (18) which holds a skirt (16) against a shoulder. The rolling seal (18) engages the casing (10) to define a front chamber (12) which is permanently connected to a source of depression and a back chamber (14) selectively connected to the front chamber (12) and to atmosphere via valve apparatus (22a,32a,36). The valve apparatus (22a,32a,36) is actuated by a control rod (34) capable of pressing, by way of a front face on a plunger (32), on a first face of reaction disk (40) secured to a second face on a push rod (42). The tubular part (24') of the piston is connected to the hub (22) by clipping.

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.