Abstract: A hydraulic-pressure counter-force mechanism 37 which produces a counter force when a brake booster is operated is made up of an input-side member 38 slidable disposed within a valve body 3, a second constant-pressure chamber 39 formed on the rear side of the input-side member and into which a pressure is introduced from a constant pressure chamber A, and a second constant-pressure chamber 39 formed on the front side of the input-side member and into which a pressure is introduced from a variable pressure chamber B. The counter force from the hydraulic-pressure counter-force mechanism 37 is reduced by an orifice passage 43 as counter-force reducing means in rapid operation for brake.

Abstract: In an automatic brake booster, a sleeve 18 constituting a valve mechanism 15 has a drive portion 50 disposed on the front side, a valve portion 51 forming a second valve seat 19, a mating portion 52 for mating with a valve seat portion when the drive portion is moved forward, and a conical spring 53 disposed between the drive portion and the valve seat portion and used for separating both members from each other. The conical spring is compressed during the normal braking operation so as to make the opening amount of the second valve seat greater than that during the automatic braking operation. Moreover, a plate plunger 40 for transmitting braking counterforce is relatively displaceably provided and a first member 71 and a second member 71 for mutually contacting a reaction disc 41 is also provided, so that the braking counterforce of the first member is transmitted to the sleeve during the automatic braking operation.

Abstract: A cam case 23 is provided which swingably supports a cam ring 34 fitted to a rotor 33 having a vane 33a to form a pump chamber 36 from the outer surface such that the cam ring 34 is swingably supported by a swingable pin 35 disposed in the axial direction as a fulcrum, the cam case 23 serving as an intermediate body. Pump bodies are disposed on the two ends of the cam case in the axial direction. Moreover, a front body 21 and a rear body 22 for rotatively supporting a rotational shaft 40 of the rotor are disposed. A low-pressure chamber 80 for introducing low-level hydraulic pressure is formed at a position between the backside of the pressure plate and the front body, the position opposing a suction-side region 36A of the pump chamber.

Abstract: In a fluid pressure booster, an input rod 7 and a valve member 6 are stroked forward during the operation so as to cause a control valve to be switched over. The atmosphere is introduced into a working pressure chamber 30 via the control valve 41 and a power piston 19 then operates to make a negative pressure booster 1 produces an output from a output rod 13. As the atmosphere in the working pressure chamber 30 acts backward on a control piston 25 at this time, the valve member 6 will not be stroke further. However, the output rod 13 is continuously stroked forward and kept producing the output. Due to the stop of stroke of the valve member 6, the stroke of the input rod 7 is suppressed and set at an extremely short stroke. When the negative pressure falls, the negative pressure booster 12 produces an output from the output rod 13 since the input rod 7, the valve member 6 and the output rod 13 integrally give a stroke forward.

Abstract: An oil pump includes pump constituent elements, a pump body, and a driving shaft. The pump constituent elements define a pump chamber between a rotor and a cam ring that houses the rotor. The pump body is constituted by a front body and a rear body. The front body defines a housing space for housing the pump constituent elements. The driving shaft extends through and is axially supported by the front body to rotatably drive the rotor. An annular space is formed around the driving shaft in the front body, between a bearing for rotatably driving the driving shaft of the front body, and the pump chamber of the pump constituent elements. A flow control valve is placed in the annular space to return part of a pump discharge fluid from the pump chamber to a pump suction side.

Abstract: A counter-force mechanism (37), which produces a counter force when a brake booster is operated, is made up of an input-side member (38) slidably disposed within a valve body (3), a second constant-pressure chamber (39) formed on the rear side of the input-side member and into which a pressure is introduced from a constant pressure chamber (A), and a second constant-pressure chamber (39) formed on the front side of the input-side member and into which a pressure is introduced from a variable pressure chamber (B). The counter force from the counter-force mechanism (37) is reduced by an orifice passage (43) as a counter-force reducing means in rapid operation of the brake.

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 reaction transmitting means comprising a first and a second retainer, a coiled spring disposed between the both retainers, and a stop which prevents the both retainers from being spaced from each other beyond a given distance. The brake booster also includes a valve mechanism comprising an annular first valve seat formed on the inner periphery of the valve body, a second valve seat formed on the rear portion of the valve plunger at a location radially inward of the first valve seat, and a valve element adapted to be seated upon either valve seat. A backup plate having a diameter less than the internal diameter of the first valve seat is embedded into the valve element. This arrangement allows a sufficient hysteresis to be obtained in a region where the valve element causes an expansion and shrinkage of the coiled spring in the reaction transmitting means to provide a better brake feeling than a conventional arrangement.

Abstract: Reaction transmitting means of a brake booster includes a parallel combination of a first and a second reaction transmitting path each transmitting a brake reaction from a reaction disc to a valve plunger. The first reaction transmitting path includes a spring charged to a preset load, and the second reaction transmitting path includes a viscoelastic member as may be formed of rubber. With this construction, a hysteresis is obtained in both a low range of servo ratio during an initial phase of operation of a brake booster and a higher range of servo ratio during a later phase of operation, which occur before and after the spring in the reaction transmitting mechanism is compressed, thus allowing a good brake feeling to be maintained.

Abstract: A brake booster which permits a booster ratio to be changed in two stages. A first spring 25 is disposed between a first plunger plate 24 and the bottom of a stowage 8A of a valve plunger 8. Toward its front end, the outer periphery of the first plunger plate 24 slidably extends through a second plunger plate 26, which is in turn located at its inoperative position shown by a second spring 28 having a greater spring constant than the first spring 25. When the brake booster 1 is actuated, a reaction disc 33 which bulges rearward initially abuts against the first plunger 24, and subsequently, as the first spring 25 is compressed, it abuts against the end faces of the both plunger plates 24, 28. If a brake pedal is released under this condition, a hysteresis is substantially nullified. The invention provides an improved brake controllability in a region of a greater depression (or input) of the brake pedal.

Abstract: The collar 13 for slidably supporting and guiding a valve body of the control valve 55 of the hydraulic pressure type booster 1 is press-fitted into the small diameter portion 9a of the stepped hole 9 of the power piston 8. The valve seat member 10 of the control valve 55 is also press-fitted into the small diameter portion 9a. Further, the small diameter protrusion 6b of the stepped cylindrical protrusion 6a of the plug 6, which divides the power chamber 25, is also press-fitted into the small diameter portion 4a of the stepped hole 4 of the housing 3. In the cylindrical member 17 in which the second valve seat 17a of the control valve 55 is formed, the stopper 17b to restrict a limit of retraction of the input shaft 18 is integrally formed. Further, the cylindrical fixing member 11 to fix the flange 10a of the valve seat member 10 is fixed to the power piston 8 with C ring 12 in the axial direction.

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 booster 3 has a structure that a return valve 14 is formed into a two-step throttle incorporating a first throttle valve 36 and a second throttle valve 37 formed continuously from the first throttle valve 36. When a valve spool 28 has been moved forwards when the operation is performed, a gap of the first throttle valve 36 is reduced. Also a gap of the second throttle valve 37 is reduced. Therefore, hydraulic fluid discharged from a pump is passed through an inlet passage 12, and then introduced into the second annular groove 13. Then, the hydraulic fluid is throttled by the first throttle valve 36, and then throttled by the second throttle valve 37. That is, the hydraulic fluid is throttled in the two-step throttling manner. As a result of the two-step throttling structure, the overall velocity of the flow of the hydraulic fluid can smoothly be changed without rapid change. Therefore, fluid flow noise caused from the change in the velocity of the flow can be prevented.

Abstract: A brake reaction which occurs as a brake booster is actuated is prevented from being transmitted to a brake pedal, and instead pseudoction reaction imparting means 41 is provided to transmit a pseudo-reaction to the brake pedal. A valve body 5 and a power piston 3 are capable of relative movement in the axial direction, and are normally urged away from each other by a spring 8. The valve body 5 is normally urged forward by a spring 42 which is disposed within the variable pressure chamber B. This arrangement allows a variation in the advancing stroke of the brake pedal to be suppressed small if a variation occurs in the magnitude of a negative pressure which is introduced into a constant pressure chamber A as the brake booster is actuated, thus providing an improved brake feeling experienced by a driver.

Abstract: In a variable displacement pump, a pump body has an inner surface and is formed with suction and discharge paths communicating with the inner surface. First and second fluid pressure chambers are divisionally formed between the inner surface of the pump body and an outer surface of a cam ring through a seal portion including a swing fulcrum pin. A spring biases the cam ring from the second fluid pressure chamber toward the first fluid pressure chamber. A metering restrictor is provided between the discharge paths. A control valve is connected to the discharge paths formed upstream and downstream, respectively, of the metering restrictor and to the first and second fluid pressure chambers, and is driven by fluid pressures present upstream and downstream of the metering restrictor.

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: There is provided a master cylinder in which a large quantity of working fluid can be supplied rapidly, the air bleeding takes less time in the manufacturing process, and satisfactory performance can be provided when traction control is operated. For the master cylinder MC, a first supply passage 19 for supplying a working fluid from a working fluid reservoir to a pressure chamber 9 through a working fluid supply port 20a, supply passages 22, 23 and 24, and a working fluid supply port 5b formed in a piston 5, a second supply passage 50 is formed in parallel with the first supply passage directly between the working fluid supply port 20a and the pressure chamber 9, and a check valve 51 is disposed in the second supply passage 50.

Abstract: In a pump operation control apparatus for a hydraulic brake boosting system, an ECU 13 is provided with a timer 16 to which an output signal from a brake switch 12 is supplied and a pump-operation-control-signal generating means 17 for transmitting a signal for operating and controlling a motor 9 in response to an output signal from the timer 16. When the brake switch 12 has been switched on, the operation of the pump is started. After predetermined time T has elapsed from a moment at which the brake switch 12 has been switched on, the operation of the pump is interrupted. If the brake switch 12 is continuously switched on after the predetermined time T has elapsed, the pump is operated for time elongated from the predetermined time T until the brake switch 12 is switched off. If the brake switch 12 is again switched on before the predetermined time T elapses, the pump is operated until the predetermined time T elapses from the moment at which the brake switch 12 has again been switched on.

Abstract: If a determination is made by a pressure gradient comparison means 24 that gradient of the rise in the pressure in an accumulator calculated by a pressure gradient calculating means 21 and realized during the operation of a pump is lower than a predetermined level, occurrence of an abnormal condition of the pump or a motor is determined. If a pressure gradient comparison means 24 determines that the gradient of pressure depression of the hydraulic pressure in the accumulator realized after the operation of the pump has been interrupted is higher than a predetermined value, occurrence of an abnormal condition which is leakage of solution is determined. If determination of the abnormal condition is sequentially made predetermined number of times, an abnormal-condition deciding means 28 decides occurrence of an abnormal condition, and then produces an output to an alarm-signal generating means 29.

Abstract: A variable displacement pump has a swingable, displaceable cam ring fitted to form a pump chamber together with the outer circumferential surface of a rotor having vanes. Notches are formed by notching to have a substantially V-letter shape in the starting end portions, in the rotating direction of the rotor, of a pump suction opening and pump discharge opening that open to the pump chamber. The notch formed in the starting end portion, in the rotor rotating direction, of the pump suction opening is constituted by a plurality of notched grooves aligned in the radial direction of the pump chamber and having different lengths in the rotating direction of the rotor. Hence, the timing at which the pump suction opening communicates with a pressure chamber formed between the vanes changes in accordance with swing and displacement of the cam ring.