Abstract: A vacuum booster for a vehicle brake system provides a working pressure valve seat on a valve member axially movable with respect to an input member. A rotary electric motor within the booster has an output shaft coupled through rotary to linear motion conversion apparatus to move the valve member with its working pressure valve seat relative to the input member. The combination of elements is designed as a drop-in replacement for a standard air valve member. The motion conversion apparatus provides much greater mechanical force than a linear solenoid; and this allows a more straightforward design of the valve arrangement, particularly the use of a high friction seal such as a simple "O"-ring in a groove. In further contrast to a linear solenoid, it further provides positive control of the working pressure valve seat position and an extended range of travel with constant force throughout the range.

Abstract: In accordance with the invention, a booster is not provided with a mechanism which transmits a braking reaction, and accordingly, 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 which depends on an amount of depression of the brake pedal. The pseudo-reaction imparting means imparts a pseudo-reaction having a reduced rate of increase to the brake pedal when a travel of the brake pedal is small, and imparts a pseudo-reaction having an increased rate of increase to the brake pedal when a travel of the break pedal is higher. This arrangement avoids the drawback of the prior art that an abnormally high braking reaction is transmitted to a driver as a result of an operational lag of a conventional booster during a quick braking operation.

Abstract: A brake booster includes a solenoid disposed within a valve body. When the solenoid is energized under the inoperative condition of the brake booster, a piston associated with the solenoid is moved to its operative position to close a vacuum valve while opening an atmosphere valve. This allows the brake booster to be operated as an automatic brake without depressing a brake pedal. The brake booster also comprises output restriction means which may comprise a spring 55 shown in FIG. 1, for example, whereby as the output increases when the brake booster is operated as an automatic brake, the output restriction means operates to cease an increase in the output. With this arrangement, if the solenoid is energized inadvertently independently from the intent of a driver, the occurrence of a quick braking action is avoided, but a gentle braking action is assured, thus improving the safeguard.

Abstract: The invention relates to a pneumatic booster operated by a plunger (9) housed in a bore (61) and carrying a moving seat (102) intended to interact selectively with a shut-off member (111), this member being itself capable of interacting selectively with a fixed seat (101).According to the invention, the plunger (9) comprises a cylindrical body (91) and a collar (92) sliding between a front stop (911) and a rear stop (912) of the body, an anterior section (921) of the collar (92) being engaged between the cylindrical body (91) and the bore (61), a posterior section (922) of the collar (92) carrying the moving seat (102), and it being possible furthermore for the collar (92) to be held temporarily stationary in the bore independently of the movement of the body (91), by means of a channel (14) and of a snap ring (13), in order to allow extended operation of the booster after a sharp braking action.

Abstract: A displacement control device for a hydraulic unit includes: an actuator for applying operator input force to a movable member for varying displacement of the unit; a control valve having a spool and a sleeve displaceable with respect to each other, one of these being coupled with the movable member and the other being coupled with the actuator, the control valve being capable of generating a control signal based upon the relative displacement of the spool and sleeve; a servo which is operatively connected to the movable member and receives the control signal so as to move the movable member and change the fluid displacement of the unit in response to the control signal; and a bias coupling connecting the spool and the sleeve of the control valve. Thus, a preload force is interposed between and the spool and the sleeve such that relative displacement between the spool and the sleeve takes place when the feedback force exceeds the preload force.

Abstract: A pneumatic brake booster having a valve (7) actuated by movement of an operating rod (8) within a hub (6) from a position of rest to an extreme actuation position. In the position of rest, the valve (7) is closed to a pressure source (A) and when moved toward the extreme actuation opened to the pressure source (A). A purification filter (9) located between the pressure source (A) and valve (7) is made of a compressible material which has a minimum volume with the valve in the rest position and a maximum volume when the operating rod (8) reaches the extreme actuation position.

Abstract: A tandem brake booster includes a solenoid within a valve body, and the solenoid may be energized to move a first tubular member disposed on the valve body rearward. When an input shaft is driven forward in the inoperative condition of the brake booster, a vacuum valve is closed while an atmosphere valve is opened in the similar manner as occurs in the prior art, thus actuating the tandem brake booster 1. When an input or the force of depression applied to a brake pedal rises to a given value X during the operative condition of the brake booster, the solenoid is energized, whereupon the first tubular member is moved rearward relative to the valve body, and the valve element is also moved rearward. This opens the atmosphere valve which has been closed during the servo balance condition, allowing a further introduction of the atmosphere into variable pressure chambers B, D, enabling a rise in the output even though the input remains unchanged.

Abstract: A pneumatic brake booster having a right casing (10) divided in a leaktight fashion by a first moving partition (12) into a front chamber (14) and a rear chamber (16). The front chamber (14) being permanently connected to a source of low pressure (V) with the rear chamber (16) being selectively connected to the front chamber (12) and as source of high pressure by a three-way valve (40) operated by an operating rod (34). A three-way and two position solenoid valve (68) has a first inlet connected to the source of low pressure (V), a second inlet connected to a source of high pressure (A) and outlet connected to the rear chamber (14). A second moving partition (54,54') divides the rear chamber (14) into a working chamber (16) and a control chamber (50,50') with the outlet of the solenoid valve (68) being connected to the control chamber (50,50').

Abstract: An automatically operable negative pressure type booster can be applied for a front stage pressurizing function in a braking fluid pressure control apparatus with braking and steering control. The booster includes a housing, a movable wall dividing the housing interior into a front chamber and a rear chamber, a valve housing outputting a braking force to an output rod, an input member, and a control valve. The output rod can be divided into a first member and a second member. The booster further includes an auxiliary movable wall which can be engaged with the first member, a partition wall forming an auxiliary variable pressure chamber behind the auxiliary movable wall, and an electromagnetic valve unit selectively communicating the auxiliary variable pressure chamber with the front chamber or atmosphere.

Abstract: A push rod of a vacuum booster includes an inner rod section, a pipe-shaped outer rod section which is slidably fitted over an outer periphery of a rear portion of the inner rod section and connected to a brake pedal, and a buffer member made of a synthetic resin and fitted over the outer periphery of the inner rod section in front of the outer rod section. Usually, an end face of the outer rod section is retained in a position in which it abuts against a projection of the inner rod section. When an axial compressing force is applied to the push rod upon a collision of an automobile, the end face of the outer rod section slides forwards over and past the projection, while buckling the buffer member. Thus, the pushing-up of the brake pedal toward a vehicle compartment due to the retreating movement of a master cylinder is prevented, and the load applied to a driver's foot is alleviated.

Abstract: A brake booster which permits an axial relative movement between a power piston and a valve body is disclosed. An arrangement is made which prevents a brake reaction from being transmitted to a brake pedal. As an alternative therefor, pseudo-reaction imparting means transmits a pseudo-reaction to a brake pedal. A rear end of the valve body is covered by a tubular cover and bellows connected thereto, and its internal space is maintained in communication with a constant pressure chamber. The bellows has an effective diameter which is chosen to be of an equal size to the diameters of a vacuum valve seat and an atmosphere valve seat. This allows a pseudo-reaction and a brake pedal stroke to be obtained which depend on the force with which a brake pedal is depressed if a negative pressure within the constant pressure chamber varies, thus imparting a better brake feeling to a driver.

Abstract: An automatic brake booster includes a solenoid which drives a plunger, forming part of a valve mechanism, forward to switch a flow path in the valve mechanism, separately from an input shaft. A piston is mounted on the plunger, and the atmospheric pressure is introduced into an atmospheric pressure chamber disposed forwardly of the piston while a pressure which prevails in constant pressure chambers A, C is introduced into a negative pressure chamber disposed rearwardly of the piston, thus urging the piston rearward. Preferably, the piston has a pressure responsive area which is substantially equal to the pressure responsive area of an atmosphere valve seat formed on a plunger. This arrangement allows a variation in the output from the brake booster to be minimized or reduced substantially to zero if there is a variation in the magnitude of a negative pressure which is introduced into the constant pressure chambers A, C.

Abstract: A brake system has a brake booster secured to a dash panel which separates an engine compartment from a passenger compartment of a vehicle. A bracket off-sets the booster into the engine compartment from the dash panel. A cylindrical body has a flange on a first end located between the housing of the brake booster and the bracket. The cylindrical body has a partition wall located between the first end and a second end and a radial opening located between the partition wall and the second end. The partition wall has a central opening through which an input rod extends to provide a valve with an input force. An end boot, secured to the second end of the cylindrical body and the input rod, forms a resonant chamber within the cylindrical body. The radial opening provides unrestricted communication air from the engine compartment to the resonant chamber while the central opening forms an orifice to control the air flow from the resonant chamber into the valve body.

Abstract: The present invention discloses a brake force booster for automotive vehicles having a control valve which is operable independently of an actuating rod displacing a valve piston, by way of an electromagnet which actuates a third sealing seat. Displacement of the sealing seat in opposition to the actuating direction of the brake force booster permits ventilating the working chamber. To eliminate all pneumatically induced force components in an independent activation, according to the present invention, a permanent pneumatic connection is provided between a pneumatic chamber delimited in the control housing by the valve member and the vacuum chamber, and in that both a second sealing seat which is provided on the valve piston and used to ventilate the working chamber, the third sealing seat, and the valve member in its sealing lip delimiting the pneumatic chamber in the control housing have almost identical diameters.

Abstract: A pneumatic brake booster for providing braking assistance. The brake booster has an envelope (10) with an axis of symmetry (X-X') separated sealingly by at least one movable partition (12) to define at least a first chamber (14) connected permanently to a source of low pressure and at least a second chamber (16). The second chamber (16) being selectively connected to the first chamber (14) or a source of high pressure through a three way valve structure actuated by a control rod (30). The control rod (30) being capable of bearing, through the intermediary of a front face of a plunger (28) and a reaction disc (50) with a rear face of a thrust rod (48). The plunger (28) sliding in a bore (26) in the movable partition (12).

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 includes a housing in which is formed at least one pressure chamber, and a power piston disposed inside the housing for advancing and retreating movement with respect to the housing. A moving wall divides the pressure chamber into a front chamber connected to a vacuum source and a rear chamber selectively connected to the vacuum source and the atmosphere, and a valve housing is attached to the moving wall. A valve mechanism disposed inside the valve housing has a vacuum valve for connecting the rear chamber with the front chamber. The valve mechanism also has an atmospheric air valve for connecting the rear chamber with the atmosphere. An output member outputs a thrust force accompanying movement of the moveable wall, and a cylinder body is provided which has a cylinder bore and which is mounted on the front part of the housing. A piston is located in the cylinder bore for advancing and retreating movement.

Abstract: A vacuum brake power booster for automotive vehicles has a booster housing with a movable wall and a control housing which carries the movable wall. The control housing includes a main part which is accommodated in a guide tube along with a cover part axially slipped onto the main part. A solenoid for actuating a control valve is positioned in the control housing, and one axial side of the solenoid is mounted in the main part and the other axial side thereof is mounted in the cover part. The cover part has axially projecting centering segments which elastically deform and center the main part in a clearance-free manner during the assembly of the control housing.

Abstract: A brake booster (10) for a vehicle brake system comprises a housing (12) which is divided, by means of at least one movable wall (14), into a vacuum chamber (18) and a working chamber (16). A control valve arrangement (20), which is associated to the brake booster (10) and which optionally connects the working chamber (16) to atmospheric pressure or to a vacuum, comprises a control valve housing (21) which is connected to the movable wall (14) for joint relative movement with respect to the housing (12). An electromagnetic actuation unit (26) is received in the control valve housing (21), said actuation unit having a solenoid coil (44), a magnet armature (28) operating against the spring bias and which is rigidly coupled to a first valve seat (32) of the control valve arrangement (20), and an armature counter-element (46). For improving the magnetic flux in the electromagnetic actuation unit (26) while simultaneously reducing the number of parts, an insert (92) made of diamagnetic and preferably lightweight.

Abstract: A pneumatic brake booster having a casing (10) which is divided in a leaktight fashion by at least one movable wall (12) into a front chamber (14) and a rear chamber (16). A pneumatic piston (20) attached to the movable wall (12) has a tubular rear part (22) which extends through the casing (10). A three-way valve (36) which slides in a bore (26) of a pneumatic piston (20) has a valve element which interacts with a first valve seat (28a) formed on a plunger (28) and a second valve seat (20a) formed on the pneumatic piston (20) in response to an operating rod (30) moving a plunger (28) to selectively connects the rear chamber (16) to the front chamber (14) and to a source of high pressure to develop a pressure differential across the movable wall (12). A rear position of rest for the plunger (28) wherein the rear chamber (16) is connected to the front chamber (14) is defined by a front end (32) of a sleeve (34) located in the tubular rear part (22) of the pneumatic piston (20).

Abstract: A brake device having a master cylinder (1) connected to a pneumatic booster (2). The pneumatic booster (2) having a rigid casing (3) in which a partition (4) moves to delimit a front chamber (5) from a rear chamber (6). The casing (3) has a front shell (31) which is secured to the master cylinder (1) to form a first wall for the front chamber (5) and a rear shell (32) which forms a second wall for the rear chamber (32). In order to increase the absorption of kinetic energy in the event of an impact force being applied to the front shell (31), the front shell (31) has a peripheral member (311) secured to the rear shell (32) and a central member (312) secured to the master cylinder (1). The peripheral member (311) has a larger relative diameter (D1) than the diameter (D2) for the central member (312).

Abstract: An automatic emergency brake system for an automotive vehicle with an assistor having a backward push rod connected to a forward push rod coupled with a master cylinder's piston via a power piston and pushing the power piston so as to augment a force applied to a brake pedal by a driver, including a partition fixed to the backward push rod; a return spring disposed between the partition and a poppet; moving stoppers each having a moving rod, going in and out of a backward pushing rod housing, to support the back of the partition; an emergency spring disposed compressed between the moving stoppers and a housing end; a controller electrically connected to the moving stoppers to output a driving signal to the moving stoppers in accordance with a deceleration; and a deceleration/acceleration sensor electrically connected to the controller to input a reduced speed of the vehicle to the controller.

Abstract: A brake power booster is equipped with a device for determining an input force introduced at a brake pedal. According to the present invention, the device which uses a pressure generator for measuring the input force is interposed between the end of an actuating rod, connected to the brake pedal, and a valve piston that actuates a control valve of the brake power booster. The pressure generator is exposed to the effect of a pressure which develops in a pressure chamber and is built up in an elastic substance or an elastomer.

Abstract: A brake apply system includes a power booster in which, when released and at-rest, a leg of a stop engages a clip and an extension of a valve body engages the clip so that an annular rib of the valve body is axially spaced away from the stop by a distance G. At the same time, a first valve seat is engaged with a first annular valve element closing a pressure supply conduit off from a variable pressure chamber and a second valve seat is spaced away from a second annular valve element by a distance T, opening the variable pressure chamber to an atmospheric pressure chamber. When the power booster is applied, the second valve seat moves the distance T and engages the second annular valve element closing the variable pressure chamber off from the atmospheric pressure chamber and the first valve seat separates from the first annular valve element opening the pressure supply conduit to the variable pressure chamber.

Abstract: A power booster is operable at relatively low apply rates and at relatively high apply rates and includes an input assembly that has a movable input rod and a primary reaction piston having a first reaction area. An output support body is responsive to movement of the input rod, with a resilient reaction disc engaging the output support body. A secondary reaction body has a second reaction area and is engageable with the reaction disc and transfers loads between the reaction disc and the input assembly at relatively low apply rates. The amount of the load transferred is a function of both the first reaction area and the second reaction area at the relatively low apply rates resulting in a first reaction ratio. The primary reaction piston is engageable with the reaction disc and transfers loads between the output support body and the input assembly during relatively high apply rates.

Abstract: A plurality of axially extending ribs are formed in the inner periphery of a valve body at its front end for slidably supporting the outer peripheral surface of the output shaft at its rear end. With this arrangement, any dimensional error which may occur in the region of the ribs can be suppressed small during the manufacturing of the valve body if a diameter shrinkage occurs in the inner periphery thereof. Accordingly, when the rear end of the output shaft is slidably fitted into the ribs, the output shaft is less likely to be askew with respect to the axis of the valve body. Accordingly, a biased abrasion of an annular seal member which is disposed between an opening formed in the front portion of a shell and the outer periphery of the output shaft at its front end to maintain a hermetic seal therebetween can be suppressed.

Abstract: In accordance with the invention, a booster is not provided with a mechanism which transmits a braking reaction, and accordingly, 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 which depends on an amount of depression of the brake pedal. The pseudo-reaction imparting means imparts a pseudo-reaction having a reduced rate of increase to the brake pedal when a travel of the brake pedal is small, and imparts a pseudo-reaction having an increased rate of increase to the brake pedal when a travel of the break pedal is higher. This arrangement avoids the drawback of the prior art that an abnormally high braking reaction is transmitted to a driver as a result of an operational lag of a conventional booster during a quick braking operation.

Abstract: A negative pressure type booster 1 includes a housing 2, a movable wall 3 which divides the interior portion of the housing 2 into a constant pressure chamber 4 and a variable pressure chamber 5, a power piston 6 which outputs a brake output toward an output rod 10, an input member 8 which can be moved by a brake actuation, and a control valve 13. The output rod 10 can be divided into a first output rod 101 and a second output rod 102.

Abstract: In a vacuum brake power booster for automotive vehicles, including a stationary booster housing and a control housing which is axially slidable with respect to the booster housing, a sealing ring, arranged between the booster housing and the control housing, has a stop for an actuating piston. The actuating piston is axially slidably mounted on the control housing, and its purpose is actuation of a release switch to release an electromagnetic actuation of the vacuum brake power booster.

Abstract: In a method of operating an electromechanically actuatable pneumatic brake booster, an electromagnet which actuates a sealing seat of its control valve is energized in an interval by a short current pulse of maximum current strength with a subsequent ramp-like current rise, and the current being furnished to the electromagnet is decreased when a fixed value of the pressure that prevails in a master brake cylinder connected downstream of the brake booster is reached. When the hydraulic pressure introduced into the master brake cylinder reaches a nominal value, the current being furnished to the electromagnet is supplied by a pressure controller which maintains the hydraulic pressure constant.

Abstract: A pneumatic servo for assisting with braking having a casing (10) with a cylinder (38) and a cover (40) with an axis of symmetry (X-X'). A wall structure (12) divides the interior of the casing into a front chamber (14) and a rear chamber (16). The movable wall structure (12) has a rear tubular part (22) which slides in a leaktight fashion in the cover (40) and retains a three-way valve (26) which is actuated by a control rod (30). The front chamber (14) is permanently connected to a source of vacuum while the rear chamber (16) is connected selectively to the front chamber (14) and a source of pressure through the three-way valve (26). The cylinder (38) and cover (40) being made from two identical half-shells (38,40).

Abstract: A boosted braking system for a motor vehicle having a master cylinder (200) and a pneumatic booster (100). The master cylinder (200) causes an increase in pressure of brake fluid supplied to at least one wheel brake (300). The pneumatic booster (100) is controlled by the application of an input force (F2) to a control rod (26) to actuate the master cylinder (200). A main hydraulic piston (30) of the master cylinder (200) has a hollow cylinder (32) in which a reaction piston (34) slides in a leaktight and axial direction. The reaction piston (34) receives at least the input force (F2). An elastic member (46) located between the reaction piston (34) and hollow cylinder (32) exerts an elastic force for urging the reaction piston (34) toward the master cylinder (200). The reaction piston (34) delimits within the cylinder a reaction chamber (36) which is isolated from the interior volume (V) of the master cylinder (200).

Abstract: A pressure differential operated brake booster includes a housing, a diaphragm assembly adapted to divide the interior of the housing into a constant pressure chamber and a variable pressure chamber, a valve body carried by the diaphragm assembly, a valve mechanism arranged within the valve body and including a plunger connected to an input rod, and a reaction assembly disposed between the plunger and an output rod. The valve mechanism is operable to develop a pressure differential across the diaphragm assembly to transmit its movement to the output rod and feed part of the resulting reaction force back to the input rod through the reaction assembly and the plunger. The reaction assembly includes a front reaction disk and a separate rear reaction disk having a diameter less than that of the front reaction disk and greater than that of the plunger. The front reaction disk is disposed between the valve body and the output rod. The valve body has at its front end a recess to receive the rear reaction disk.

Abstract: A tandem vacuum servo unit includes a movable power piston having a supporting portion and a front movable wall member having a first engaging portion for engaging the movable power piston. The first engaging portion has an input side face that engages the output side face of the supporting portion along a first contacting portion. A rear movable wall member has a second engaging portion whose input side face engages the output side face of the first engaging portion along a second contacting portion. The first contacting portion is spaced radially outwardly of the second contacting portion. This construction of the vacuum servo unit increases the durability of the front movable wall member.

Abstract: A brake power booster for automotive vehicles has a control valve which is operable by a solenoid irrespective of the driver's wish. In order to adapt the force-travel characteristic curve of the solenoid to the consumer characteristic curve of the control valve exhibiting a drop in force, the present invention discloses an armature having two parts which are movable relative to each other and interact with stops that are axially offset in the housing of the solenoid in the actuating direction of the latter.

Abstract: A vehicle brake booster apparatus includes a housing, a movable wall positioned within the interior of the housing to divide the interior into a constant pressure chamber and a variable pressure chamber, a power piston connected to the movable wall for moving in response to movement of the movable wall, an axially movable input rod extending outwardly from the power piston for connection to a brake pedal, and an axially movable valve plunger mounted within the power piston and operatively connected to the input rod. A control valve is positioned within the power piston for controlling communication of the variable pressure chamber with atmospheric air. The control valve includes an air control valve and a vacuum control valve, with the air control valve including an air control seal arranged between the valve plunger and a valve body portion of the control valve.

Abstract: A vacuum servo unit includes a partition member having an outer periphery that engages the movable wall member in an air tight manner. A receiving chamber is defined between the partition member and the movable wall member, and the receiving chamber is adapted to be communicated with the atmosphere. A passage that introduces atmospheric air into the receiving chamber is engaged in an air tight manner with the partition member and extends through the constant pressure chamber. A change member in the form of a solenoid valve selectively communicates the receiving chamber with the constant pressure chamber or with the atmosphere. Accordingly, the servo efficiency of the vacuum servo unit is increased. In addition, the unit can be operated automatically by supplying electric power to thereby increase brake force so that the brake feeling is advanced.

Abstract: A tandem brake booster having a housing with a first front chamber separated from a first rear chambers by a first wall and a second front chamber separated from a second rear chamber by a second wall. The first and second front chambers are connected to the first and second rear chambers through passages in a hub which retains a control valve. In a first or ready mode of operation, the first and second front and rear chambers have a substantially identical first fluid pressure while in a second or actuation mode of operation, the control valve responds to an input force to allow a second fluid pressure to be communicated to the first and second rear chambers and create a pressure differential with the first fluid in the first and second front chambers. The pressure differential develops an output force which moves the first and second walls as a function of the input force applied to the control valve.

Abstract: A pneumatic brake booster having a casing (10) with an axis of symmetry (X-X') and divided in leaktight fashion by a movable wall structure (12,20) into a front chamber (14) and a rear chamber (16). The front chamber (12,20) is permanently connected to a source of partial vacuum while the rear chamber (16) is connected selectively to the front chamber (14) or to the outside atmosphere by a three-way valve (36). The three-way valve is actuated by a plunger (28) which slides in a bore (26) of the movable wall (12, 20) in response ton an input applied to an axial control rod (30). The three-way valve (36) is located in a rear tubular part (22) of the movable wall structure (12, 20) which projects outside of the casing (10) and including a valve element (36). Valve element (36) interacts via a first annular surface (A) with a first valve seat (28a) formed on the plunger (28) and via a second annular surface (B) with a second valve seat (20a) formed on the movable wall (20).

Abstract: The invention relates to a connection structure between a brake booster and a control valve which selectively introduces a negative pressure or an atmosphere into the booster. A brake booster of tandem type includes a front shell on which a pair of bosses are connected so as to extend parallel to each other. One end of one of the bosses is connected to a housing of the control valve while one end of the other boss is connected to the housing of the control valve through an L-shaped connection pipe. One end of the L-shaped connection pipe is rotatable with respect to one end of the other boss, and the other end of the L-shaped connection pipe is displaceable axially of the engaging opening in the housing during assembly. This construction allows the control valve to be assembled into the brake booster without requiring undue demand on the precision of the manufacturing various parts, while also minimizing the space required for the connection pipe.

Abstract: A servo operation apparatus for a transmission comprising an input shaft to which the shift-change operation force is mechanically transmitted from a shift lever, a servo unit for boosting the shift-change operation force by feeding a working fluid, and a valve device which feeds the working fluid to, or drains the working fluid from, the servo unit depending upon the shift-change operation of the shift lever, wherein provision is made of an working fluid feed control means which feeds the working fluid in such a manner that the pressure of the working fluid in the servo unit is raised with a steep gradient in the former half until a predetermined initially raised pressure value is reached and, thereafter, is raised in the latter half with a gradient less steep than that of said former half.

Abstract: A brake booster apparatus for a vehicle has a constant pressure chamber, a variable pressure chamber, a control valve, a power piston, a plunger member and a solenoid coil. The plunger member is actuated under the energized condition of the solenoid coil. The power piston is actuated in response to the depression of a brake pedal and/or plunger movement. The output force of the brake booster is amplified by the pressure difference between the variable and constant pressure chambers. A clearance is provided between the input member and the plunger member to permit relative movement of the input member and the plunger member. The relative movement generates a continuous variable output force of the brake booster.

Abstract: A pneumatic brake booster for providing braking assistance. The brake booster has a housing (10) with an axis of symmetry (X--X') separated sealingly by at least one movable partition (12) to define at least a first chamber (14) connected permanently to a source of low pressure and at least a second chamber (16). The second chamber (16) being selectively connected to the first chamber (14) or a source of high pressure through a three way valve structure actuated by a control rod (30,130). The three way valve structure have a valve member (36,136) which cooperates through an a first annular face (40,140) with a first annular valve seat (34,134) formed on a plunger (28,128) which slides in a bore (26,126) of a piston (20,90). The annular face (40,140) of the valve member (36,136) being urged forward in the direction of the annular valve seat (34,134) by a valve spring (42,142).

Abstract: A vacuum brake booster with an automatic braking actuation system of the type which includes an electric actuator assembled with a power piston to effect forward movement of a valve plunger assembly when activated under control of an electronic controller, wherein a depression amount of a brake pedal is detected to calculate a depression speed of the brake pedal based on the detected depression amount, and wherein the electric actuator is activated when the calculated depression speed of a brake pedal exceeds a predetermined threshold value and is deactivated when a release amount of the brake pedal is more than a predetermined value.

Abstract: A vacuum servo unit has a housing, a movable wall member, a constant pressure chamber, a variable pressure chamber, a movable power piston, an input member, an output member, a control member, an operation member for applying an axial propulsion on the output member when electric power is supplied thereto, a first input rod connected to a brake operation member, a second input rod, an electric switch member provided on either the first input rod or the second input rod, a switch operate member changing the state of the electric switch member according to a movement of the first input rod against the second input rod. Accordingly, when a driver returns a brake operation member in the condition that the operation member is applying the axial propulsion on the output member, a first input rod is pulled back. Therefore, the first input rod moves respectively to the second input rod, which changes a state of an electric switch member.

Abstract: A pneumatic brake booster having first and second sources of air pressure for developing an output force. The booster has a rigid casing (3) divided by a leaktight moving partition (4) into a first chamber 3(a) and a second chamber 3(b). The moving partition being moved by a difference in the fluid pressures prevailing between the first chamber 3(a) and the second chamber 3(b) to drive a pneumatic piston (5) which carries a valve (7). The valve (7) being actuated by an operating rod (10). The inside (50) of the piston (5) is separated from the second source of air pressure by a purification filter (14). The operating rod (10) slides in a sleeve (16) and which passes through the purification filter (14) has a widened part (100). The widened part (100) together with one end (162) of the sleeve (16) forms an additional valve allowing an additional and direct air intake into the piston (5) in the event of an abrupt application designed to effect a substantial braking force.

Abstract: A vacuum servo unit includes a movable power piston having a base portion and a cylindrical portion whose output side end portion is connected to the input side end portion of the base portion. The base portion has an annular first projection projecting into the inside of the cylindrical portion and a second projection projecting into the inside of the cylindrical portion. the second projection divides the space surrounded by the annular first projection into a first space and a second space. A vacuum path communicates the constant pressure chamber with the first space, and an air path communicates the variable pressure chamber with the second path. Thus, the area of the cross-section of the second space in a plane perpendicular to the axis of the movable power piston can be enlarged so that atmospheric air can smoothly flow into the variable pressure chamber.

Abstract: The invention relates to a pneumatic brake booster using two sources of air pressure and comprising a rigid casing (3) divided by a leaktight moving partition (4) into at least two chambers (3a, 3b), it being possible for the moving partition to be urged by a difference, brought about by an actuation of the valve, between the pressures supplied to the chambers in order to drive along a pneumatic piston (5) bearing an operating valve (7), the inside (50) of this piston being separated from the second source by a purification filter (14).

Abstract: A brake booster for vehicles prevents suction noise that is generated from a rapid inflow of air from being emitted to the outside. The brake booster includes a casing, a diaphragm mounted in the casing by which a constant-pressure chamber and a varying-pressure chamber are isolated from each other, a valve body one end of which is fixed to the inner surface of the diaphragm and the other end of which includes an air suction area, a poppet valve mounted in the valve body to connect or disconnect the varying-pressure chamber to the outside, an input shaft one end of which is arranged in the valve body to operate the poppet valve, an output shaft transmitting to a master cylinder the force boosted by the pressure difference between the constant-pressure chamber and the varying-pressure chamber, and a noise barrier mounted in the valve body.

Abstract: A fluid-operated brake actuator having a hollow actuator rod between a spring chamber of a spring brake housing and a spring chamber of a service brake housing incorporates a valve within the actuator rod. The valve isolates the two spring chambers from each other in normal operation and releases a vacuum in the spring brake housing spring chamber when the spring brake is activated. A separate one-way check valve mounted in a well of the spring brake housing permits fluid to exhaust from the spring chamber to atmosphere and prevents contaminants in the atmosphere from entering the spring chamber.