Other

Jidosha Kiki Co., Ltd.

Bosch Braking Systems Co. Ltd.

Bosch Automotive Systems Corporation

Denso Corporation

Bosch Corporation

Yoshiyasu Takasaki

Hidefumi Inoue

Hiroyuki Oka

Mamoru Sawada

Yuzo Imoto

Michio Kobayashi

Masahiro Shimada

Hiroaki Niino

Kazuya Maki

Masahiro Ikeda

Osamu Kanazawa

Isao Kobayashi

Hiroshi Ohsaki

Hiroyuki Yamaga

Yasushi Mori

Motomu Hakiai

Makoto Watanabe

Naohito Saito

Yoshio Tobisawa

Mitsuru Kakuda

Hiroshi Osaki

An object of the invention is to prevent abnormal noise from being generated when the pressure of brake fluid supplied to a brake caliper is reduced. A vehicle brake device includes first and second hydraulic brakes generating a hydraulic brake force and a regenerative brake generating a regenerative brake force and divides a braking force into the hydraulic brake force and the regenerative brake force. The vehicle brake device includes a regulating valve that is provided between the first and second hydraulic brakes and continuously regulates the flow rate of brake fluid flowing to the second hydraulic brake from the first hydraulic brake, and a pressure reducing valve that reduces the pressure of the brake fluid supplied to the second hydraulic brake. An opening of the regulating valve is continuously increased and the pressure reducing valve is opened, when the hydraulic brake force of the first hydraulic brake is reduced.

Vehicle brake device and method of controlling the same

There is provided a vehicle brake device that includes hydraulic brake means for generating a hydraulic brake force and regenerative brake means for generating a regenerative brake force and distributes the hydraulic brake force and the regenerative brake force for a driver-requested brake force. The hydraulic brake means includes a pressure reducing valve that reduces hydraulic pressure of wheel cylinders. The vehicle brake device includes hydraulic brake control means for maintaining the pressure reducing valve open while the driver-requested brake force is covered by only the regenerative brake force. The hydraulic brake control means does not open the pressure reducing valve when hydraulic pressure is present in the wheel cylinders.

Vehicle brake device and method of controlling vehicle brake device

A tubular memberis slidably fitted into a valve body, and is formed with a vacuum valve seat. The tubular member, a valve plungerand the valve bodyare maintained in their inoperative positions shown by abutment against a key member. A holderis formed with a tapered surfaceto assist in allowing an elastic deformation of a reaction disc. Immediately after the commencement of operation of a valve mechanismas an input shaftis driven forward, the input shaftand the tubular memberare maintained in their inoperative positions until a rear end face of a variable pressure passageabuts against the key member. The operating stroke of an input shaftcan be chosen to be less than the operating stroke of an output shaftwhile preventing the jumping value from increasing to an excessively high value.

Negative pressure brake booster

In a negative pressure boosting device, a movable valve seat is air-tightly and slidably disposed in a concavity of a valve body. The movable valve seat and a valve element compose a vacuum valve. A servo ratio changing device includes a control spring compressed and disposed between the movable valve seat and the valve body. The servo ratio changing device is provided on a valve mechanism (the vacuum valve). During operation, the valve element comes in contact with the movable valve seat. The movable valve seat does not move in a low-input range so that the servo ratio is a relatively large ratio for the normal operation. In a high-input range, the control spring starts to be compressed to move the movable valve seat, thereby changing the servo ratio to a small ratio.

Negative pressure boosting device

A brake booster includes a valve mechanism , and a solenoid which operates the valve mechanism . When the solenoid is energized, a solenoid plunger and a valve seat member move rearward relative to a valve body , whereby the valve mechanism is operated to actuate the brake booster without depressing a brake pedal. A core member which forms a magnetic path for the solenoid is disposed rearward of the solenoid plunger so as to be movable axially of the valve body and so as to move in linked relationship with a valve plunger . The invention allows the size of the solenoid to be reduced.

Brake booster

During a normal brake operation, a brake reaction from a reaction disc is transmitted to a valve plunger through an outer plunger and an inner plunger. During an emergency brake operation, as a valve plunger is driven forward through a given stroke relative to a valve body, a tubular member retracts relative to the valve body. In a servo balance condition, which is reached subsequently, the valve plunger, retracts by an amount corresponding to the retraction of the tubular member, and the outer plunger abuts against a holder. A brake reaction from the reaction disc is transmitted to the valve plunger only through the inner plunger, allowing a booster ratio to be greater and a jumping quantity to be greater than during a normal brake operation. It is possible to increase an output from a brake booster rapidly in immediate response to a quick depression of a brake pedal.

A brake fluid pressure generating device includes a first valve element connected to an input shaft, a first force device connected to the first valve element to provide a counter force relative to a force applied to the first valve, a second valve element situated adjacent to the first valve element, a power cylinder unit actuated by the first valve, a second force device situated between a power cylinder unit and the second valve element to move the second valve element, and a third force device connected to the second valve element to provide a counter force relative to a force applied to the second valve. A master cylinder is connected to the power piston to generate a master cylinder pressure to thereby output a regulated control valve output pressure. A desired stroke characteristic of the brake can be obtained.

Brake fluid pressure generating device

A brake system of the present invention comprises a brake operating means such as a brake pedal for carrying braking operation, a fluid variable stroke means which variably controls the stroke of the brake operating means by using fluid, and a braking force output means which is actuated by the operation of the brake operating means to produce braking forces. By manipulating the brake operating means , the braking force output means performs the braking operation. The traveling rang of the brake operating means i.e. the stroke can be changed variously by the fluid variable stroke means using fluid. Since the stroke of the brake pedal can be changed as mentioned above, a proper pedal stroke can be obtained.

Brake system

A hydraulic-pressure counter-force mechanism which produces a counter force when a brake booster is operated is made up of an input-side member slidable disposed within a valve body , a second constant-pressure chamber 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 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 is reduced by an orifice passage as counter-force reducing means in rapid operation for brake.

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. The arrangement is applicable to a wide variety of brake systems onboard a vehicle such as a regenerative brake unit, an engine brake or an exhaust gas brake unit or a brake assisting apparatus.

In a brake booster of the present invention, by depression of a brake pedal an input shaft travels to the left, a pedal input converter generates thrust, and a valve element moves to the left. A valve passage is shut off from a valve passage and a valve passage is connected to a valve passage so as to develop output pressure Pr at an output port of a control valve because of the pressure of a pressure source. The output pressure Pr is supplied to a wheel cylinder thereby actuating the brake. At this point, since the displacement of the input shaft required for operating the control valve is defined only by the converter the input side is not affected by the brake rigidity of a circuit from the control valve to the wheel cylinder The output pressure Pr of the control valve acts on the valve element through a first reaction receiving portion and is regulated to pressure proportional to the thrust of the converter The second reaction force is transmitted to a driver through a second reaction receiving portion The control of the output can be conducted during the operation regardless of the input of the input side and the respective characteristics can be varied without being affected by the output side.

In a brake fluid pressure boosting device of the present invention, by operation, an input shaft is moves forward to rotate a lever to actuate a control valve so that the control valve produce working fluid pressure corresponding to the input. The working fluid pressure is introduced into the power chamber By this working fluid pressure, the primary piston is actuated to develop master cylinder pressure. On the other hand, the fluid pressure of the power chamber is introduced into the first annular groove of the valve spool By the difference between pressure receiving areas of the first annular groove the valve spool is subjected to rightward force. The position of the pivot of the lever is fixed and the valve spool is controlled in such a manner that the force applied to the valve spool and the spring force of the spool return spring balances with the input, thereby exhibiting the function as a stroke simulator. Because of this function as a stroke simulator, the stroke characteristic on the input side can be changed without affecting the output side.

Fluid pressure boosting device and brake system employing the same

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.

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.

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. The master cylinder is capable of providing an increased braking force as required by intensifying a master cylinder pressure.

Growing community of inventors

Saitama-ken, Japan

Yoshiyasu Takasaki