Abstract: The invention relates to a brake system including a brake booster. A pneumatic pressure operated brake booster VBB or a liquid pressure operated brake booster includes a valve mechanism which is urged by a force of depression applied to a brake pedal BP to switch a flow path to cause the brake booster to develop an output which depends on the magnitude of the force of depression. A solenoid SOL urges the valve mechanism in the same direction as or in the opposite direction from the force of depression. A controller ECU is responsive to a braking effort increase/decrease demand signal to increase or decrease the urging force which is applied by the solenoid to the valve mechanism, thus increasing or decreasing the output from the brake booster. An output from the brake booster can be freely controlled independently from the force of depression applied to the brake pedal in response to a braking effort increase/decrease demand.

Abstract: In a fluid pressure boosting device 1 of the present invention, a control valve 4 is composed of a supply valve 44 and a discharge valve 45, the supply valve 44 comprises an annular valve cone 46 of a poppet type and a first valve seat 7 and the discharge valve 45 comprises an annular valve cone 46 of a poppet type and a second valve seat 8. Inside a rear end portion of a primary piston 21 of a master cylinder 2, a reaction disk 57 made of an elastic material such as rubber is fitted. An input shaft 3 penetrating the control valve is arranged such that, in the inoperative state, an end thereof confronts the reaction disk 57 with a predetermined space therebetween and, in the operative state, the end comes in contact with said reaction disk 57 so that a reaction force is transmitted to the input shaft 3. The passage for discharging hydraulic fluid of the power chamber 9 is composed of annular passages 52, 53.

Abstract: In a brake booster of the present invention, by depression of a brake pedal 3, an input shaft 4 travels to the left, a pedal input converter generates thrust, and a valve element 5a moves to the left. A valve passage 5a1 is shut off from a valve passage 5b1 and a valve passage 5a2 is connected to a valve passage 5b2 so as to develop output pressure Pr at an output port 5c of a control valve 5 because of the pressure of a pressure source. The output pressure Pr is supplied to a wheel cylinder 7, thereby actuating the brake. At this point, since the displacement of the input shaft 4 required for operating the control valve 5 is defined only by the converter 6, the input side is not affected by the brake rigidity of a circuit from the control valve 5 to the wheel cylinder 7. The output pressure Pr of the control valve 5 acts on the valve element 5a through a first reaction receiving portion 8 and is regulated to pressure proportional to the thrust of the converter 6.

Abstract: In a brake fluid pressure boosting device 1 of the present invention, by operation, an input shaft 4 is moves forward to rotate a lever 27 to actuate a control valve 8 so that the control valve 8 produce working fluid pressure corresponding to the input. The working fluid pressure is introduced into the power chamber 6. By this working fluid pressure, the primary piston 37 is actuated to develop master cylinder pressure. On the other hand, the fluid pressure of the power chamber 6 is introduced into the first annular groove 25 of the valve spool 10. By the difference between pressure receiving areas of the first annular groove 25, the valve spool 10 is subjected to rightward force. The position of the pivot of the lever 27 is fixed and the valve spool 10 is controlled in such a manner that the force applied to the valve spool 10 and the spring force of the spool return spring 32 balances with the input, thereby exhibiting the function as a stroke simulator.

Abstract: As the primary piston 3 is driven forward, a cup seal 32 moves forwardly of a communication path 17c in a first sleeve 17 to interrupt a communication between a first reservoir chamber 11 and the first liquid pressure chamber 5, thus generating a liquid pressure in the first liquid pressure chamber 5. As the secondary piston 10 is driven forward, a cup seal 25 moves forwardly of a communication path 18c, interrupting a communication between a second reservoir chamber 19 and a second liquid pressure chamber 6, thus generating a liquid pressure in the second liquid pressure chamber 6. The invention provides a master cylinder 1 which is simple in construction and inexpensive to manufacture.

Abstract: In a brake pedal apparatus of the present invention, as a brake pedal 2 is depressed when an engaging means 15 and a receiving portion 14 are engaged with each other, a second lever member 2a2 pivots about a second pivot pin 13. At this point, when the pedaling force Fp is smaller than a threshold value Fp0, the engagement between the engaging means 15 and the receiving portion 14 is maintained so that the second lever member 2a2 pivots about the second pivot pin 13. In this state, the pedal leverage is set to be a smeller ratio. As the pedaling force Fp, exceeds the threshold Fp0, the engaging means 15 is disengaged from the receiving portion 14. Then, the first and second lever members 2a1, 2a2 are coupled by a stopper portion 2a3 to pivot together about a first pivot pin 11. Therefore, the pedal leverage is changed to a larger ratio. In this manner, the brake pedal apparatus of which pedal leverage can be easily changed is provided.

Abstract: In a master cylinder including: a cylinder body having a cylindrical bore and an opening made in the circumferential wall, for a relief port communicating with the interior of hydraulic reservoir, a piston inserted slidably into said cylindrical bore to form a hydraulic pressure generating chamber in said cylindrical bore; and a cup seal having an inner circumferential lip portion contacting with said piston, an outer circumferential lip portion slidably contacting with the inner circumferential wall of said cylindrical bore, and a base portion connecting said lip portions which are so arranged as to face to said hydraulic pressure generating chamber, whereby said cup seal cuts the communication between said hydraulic pressure generating chamber and said hydraulic reservoir through said relief port when the top end of said outer circumferential lip portions passes by said relief port, the improvement in which means for rotating said cup seal relative to said cylindrical bore with the movement of said piston i

Abstract: The object of the present invention is to exhibit the function of a throttle valve mechanism without making the whole of a master cylinder large-sized and to simplify the structure and to reduce the number of pieces of parts. In order to attain this object, the present invention has throttle valve mechanisms with a floating valve body which sits and throttles the flow of the hydraulic fluid to the reservoir from the pressure generating chambers when the pistons operate and which opens when the pistons do not operate, and the throttle valve mechanisms are arranged in the fluid passage for the supplementation of the hydraulic fluid, and the throttle valve mechanisms have a floating valve body with a throttle passage and a valve seat with and from which the floating valve body is brought into contact and is separated, and the valve seat is provided at the tip of the connecting portions to the cylinder body of the reservoir.

Abstract: A brake system including an intensifying arrangement which allows a master cylinder pressure to be intensified by feeding a discharge pressure from a pump to an intensifying chamber. The brake system includes a master cylinder having a primary piston, on the rear portion of which a sleeve is fitted, with a spool valve slidably fitted into the sleeve. The spool valve has a rear end which abuts against the bottom of a bottomed opening formed in an input shaft. The invention allows a misalignment between the axes of the primary piston and the input shaft.

Abstract: A steering damper has a flow passage control valve for switching and connecting among a pump, a tank and left and right chambers in a power cylinder in correspondence to a steering operation, and left and right cylinder passages (3, 4) for connecting to the left and right chambers. The steering damper is provided with left and right damper portions (10A, 10B) having variable throttle valves (6, 7) arranged in the middle of the respective cylinder passages and limiting an inflow to the flow passage control valve from the power cylinder and pilot operated check valves (8, 9) connected thereto in parallel and allowing an inflow from the flow passage control valve to the power cylinder. A pilot plunger (30) arranging them at positions close to the respective passages and sliding between the left and right damper portions is provided.

Abstract: In a brake fluid pressure generating device of the present invention, a first valve element 5a is controlled to balance the input of an input shaft 4 and a first valve element converted force of a first stroke/force converter 6, and a second valve element 5b is controlled to balance a first control valve converted force F2 of a first control valve output-pressure/force converter 10 and a second valve element converted force of a second valve element stroke-force converter 7. Even when control for braking pressure Pw of wheel cylinder 9 side is conducted on the output side of a control valve 5, the stroke of the first valve element 5a is not affected by the braking pressure control. That is, even when the braking pressure control is conducted on the output side of the control valve 5, the pedal stroke can be prevented from being varied. Therefore, desired stroke characteristic of the brake operating means can be obtained independently of variation in consumption of brake fluid in the brake circuit.

Abstract: In a braking pressure intensifying master cylinder of the present invention, as an input shaft 53 travels forwards in a braking maneuver, a control valve 54 is actuated to develop fluid pressure according to the input in a reaction chamber 38 and a pressurized chamber 35. A stepped spool 45 as a part of the control valve 54 travels such that force produced by the fluid pressure and spring force of a spring 51 are balanced, whereby the stepped spool 45 can function as a travel simulator. By changing the pressure receiving areas of the stepped spool 45 and/or changing the spring force of the spring 51, the travel characteristic of the input shaft 53 as the input side can be freely changed independently from the output side, without influence on MCY pressure as the output side of the braking pressure intensifying MCY 1. In addition, the master cylinder pressure can be intensified when necessary with a simple structure.

Abstract: A brake system contains a safety mechanism which terminates an automatic brake upon detecting that unnecessary braking force is developed as a result of a failure in an automatic brake controller. In the event a braking output is developed when neither a brake pedal nor the automatic brake controller is operated, the safety mechanism determines the occurrence of an abnormality, and interrupts a communication between the master cylinder and the wheel cylinder while decompressing the oil pressure in the wheel cylinder by discharging it into a low pressure accumulator. The safety mechanism allows the automatic braking to be terminated, thus allowing a risk of a collision by a succeeding vehicle to be avoided and allowing a vehicle to continue running.

Abstract: A master cylinder which includes a primary piston and a thrust piston disposed within a housing, and defines an intensifying chamber at a location rearward of the thrust piston. An input shaft has a front end which is disposed within the intensifying chamber. The thrust piston is formed with a communication path (discharge passage), and a control valve is disposed between the thrust piston and the front end of the input shaft to open or close the communication path (discharge passage). When the input shaft is driven forward under the inoperative condition shown and the pump is operated to introduce a discharge pressure from the pump into the intensifying chamber, a liquid pressure is generated in the intensifying chamber and drives the primary piston forward, generating a liquid pressure in a liquid pressure chamber. In this manner, a master cylinder can be provided which has a simple and inexpensive construction with a reduced number of parts and which is compact in size.

Abstract: A detection switch is mounted on an input shaft through a clevis for detecting the operation of an automatic brake unit without the depression of a brake pedal. The detection switch may also be mounted on the brake pedal. The clevis and the brake pedal are connected together in a manner to permit a relative displacement therebetween through an operating stroke of the detection switch. When the brake pedal is depressed, the brake pedal is maintained at an advanced position relative to the input shaft, and the detection switch detects a retracting movement of the brake pedal with respect to the input shaft from the advanced position during an automatic brake operation. The arrangements allow the detection switch to be mounted on either the input shaft or the brake pedal, does not require design of a small size and facilitates the mounting of the detection switch.

Abstract: First and second fluid pressure chambers 43 and 44 are formed on both sides of a swingable cam ring 27. A control valve 40 for controlling a swing of the cam ring is provided. To operate the control valve, a variable metering throttle 61 is provided in the middle of a discharge path. The variable metering throttle 61 is formed with a communicating channel 62 which is formed in the side surface of one side of the cam ring in the axial direction, and communicates with a discharge-side hollow 33 being formed in a pressure plate 30 which faces the side surface, and a small hole 63 which is bored in the pressure plate 30 while facing a part of the communicating channel, and of which the opening area is varied with the side edge 62a of the communicating channel of the cam ring 27 when the cam ring swings.

Abstract: A brake system including a negative pressure booster, a master cylinder of tandem type and an intensifying arrangement. The intensifying arrangement defines an intensifying chamber disposed rearward of a primary piston, a pump for supplying a braking liquid to the intensifying chamber, and a reaction piston and a sleeve for controlling the pressure of the braking liquid which is supplied to the intensifying chamber. As a brake pedal is depressed and the intensifying arrangement is actuated, a sum of an urging force from the negative pressure booster and an urging force from the intensifying arrangement operates the primary piston to develop a master cylinder pressure. The sum is proportional to the input or a force depressing the brake pedal.

Abstract: An improvement of a reaction disc 25 and a valve plunger 8 disposed in a booster is provided. A recess 25a is formed in a rear end face 25b of the reaction disc while a projection 31a from the valve plunger 8 is loosely fitted into the recess 25a. When the break booster 1 is operated, the peripheral surface and the bottom of the recess 25a abut against the projection 31a, and the rear end face 25b abuts against the end face 31c of a plunger 31, whereby a brake reaction is transmitted to an input shaft 21. When an input or a force of depressing a brake pedal is reduced during the operation, a resistance is applied to a rearward retracting movement of the valve plunger 8 by the peripheral surface of the recess 25a. The invention allows the hysteresis to be increased without increasing the hardness of the reaction disc 25.

Abstract: A valve mechanism of an automatic brake booster comprises a vacuum valve seat formed on a valve body to face forward, an atmosphere valve seat formed on the rear portion of a valve plunger, and a valve element adapted to be seated on the both valve seats from the front side thereof. The valve plunger is associated with a solenoid plunger which allows the valve plunger to extend therethrough to permit a relative displacement therebetween and which is integrally connected thereto at an advanced end position thereof. A resilient member is provided which normally maintains the solenoid plunger at the advanced end position relative to the valve plunger. This simplifies a valve mechanism in comparison to a conventional automatic brake booster, thus improving the reliability.

Abstract: In a brake apparatus of the present invention, as MCY pressure is developed by a master cylinder (MCY) 1 according to the forward movement of a primary inner piston 9, a pump of a braking force control device arranged between the MCY 1 and wheel cylinders (WCYs) sucks up hydraulic fluid from the MCY 1 to discharge the hydraulic fluid to the WCYs. Thus, WCY pressure controlled according to operational conditions of various modes is developed. The WCY pressure is supplied to a control pressure chamber 40 to act on a step 8e of a primary outer piston 8. The primary outer piston 8 moves relative to the primary inner piston 9 in such a manner that the force produced by the MCY pressure, the force produced by the WCY pressure, the spring force of a control spring 13, and the frictional force of fluid-tightly slidable portions of the primary outer piston 8 are balanced, whereby the pedal travel can remain the same as that in service braking mode.