Tokico, Ltd.

Hitachi, Ltd.

Hitachi Automotive Systems, Ltd.

Kabushiki Kaisha Hitachi Seisakusho

Kabushiki Kaisha Hitachi Seiksakusho

Takato Ogiwara

Naganori Koshimizu

Tomonori Mouri

Hiromi Ando

Takayuki Kinoshita

Toshio Takayama

Kenji Sano

Mitsuhiro Endo

Yasuhiko Amari

Ryoichi Yagi

Yasutoshi Nagatsuyu

Eiichi Takano

A controller controls a hydraulic control device to generate a target braking force corresponding to the stroke of a brake pedal by adjusting a controlled hydraulic braking force portion generated by the hydraulic control device on the basis of the relationship with a master hydraulic braking force portion generated from the brake hydraulic pressure in a master cylinder and a regenerative braking force portion generated by a regenerative brake device. The regenerative brake device maximizes the regenerative braking force portion before the stroke of the brake pedal reaches an idle stroke, and thereafter, the hydraulic control devicestarts braking by the controlled hydraulic braking force portion. When the stroke of the brake pedal reaches the idle stroke, the master cylinder starts braking by the master hydraulic braking force portion.

Brake apparatus

Provided are a vehicle braking system and a master cylinder which are capable of providing a good pedal feel. A valve-opening pressure for a pressure-reducing valve of the master cylinder is set higher than a hydraulic pressure which is obtained with a pressing force on a brake pedal being 500 N and lower than a hydraulic pressure obtained at a time when a booster reaches a full-load point in case of failure of the booster so as to be specialized for improving pedal feel. Required performance in case of failure of the booster is realized by a pressure-intensifying unit.

Vehicle braking system and master cylinder

A master cylinder includes a cylinder body which an operating fluid is introduced from a reservoir, a piston which is slidably fitted in the cylinder body and defines a pressure chamber inside the cylinder body, a supply pathway which is formed in the cylinder body and supplies the operating fluid from the reservoir to the pressure chamber, a bypass pathway which bypasses the supply pathway and allows the reservoir to communicate with the pressure chamber, and a check valve which is installed in the bypass pathway and opens a valve when the pressure inside the pressure chamber is lower than the pressure of the reservoir.

Master cylinder

A master cylinder includes a bottomed cylindrical cylinder body, a piston formed into a bottomed cylindrical shape by a forging method and slidably disposed in the cylinder body, and a spring assembly including a spring urging the piston toward an opening side of the cylinder body. A length of a spring of the spring assembly is determined by a retainer which can abut against an inner bottom portion of the piston. An annular groove is formed on the outermost side of the inner bottom portion of the piston by the forging method.

In a master cylinder, a supply passage for supplying operating liquid from a reservoir () to a pressure chamber () is provided in a cylinder body () coupled with the reservoir. A bypass passage () for bypassing the supply passage and connecting the reservoir and the pressure chamber is further provided, and a check valve () adapted to open when a pressure in the pressure chamber is lower than that in the reservoir is disposed in the bypass passage. A valve case () containing a valve body () of the check valve includes a valve seat () and a cylindrical wall () for slidably guiding the valve body which are integrally formed as a single member.

A master cylinder designed to facilitate an operation of assembling and adjusting a check valve is provided. A supply passage for supplying operating fluid from a reservoirto a pressure chamberis formed in a cylinder bodyconnected to the reservoir. A bypassfor bypassing the supply passage connecting the reservoirand the pressure chamberis formed and provided with a check valve systemadapted to open when a pressure in the pressure chamberis lower than that in the reservoir. A valve caseand a covering memberconstitute a cartridge, which accommodates a valve bodyand an urging spring, so as to form a check valve system. The cartridgeis placed in a valve chamberof the bypass

Master cylinder, method for manufacturing a master cylinder, and check valve system of the master cylinder

A master cylinder including a cylinder body having a tubular shape with a closed end; and a piston having one side slidably inserted into the cylinder body and another side that projects from the cylinder body. The piston and the cylinder body define a pressure chamber for generating hydraulic pressure. The master cylinder also includes a protecting member for covering the side of the piston projects from the cylinder body. The protecting member is adapted to extend and contract, and limit backward movement of the piston.

A master cylinder of the invention supplies a brake fluid from a large diameter pressurizing chamberto a small diameter hydraulic chamberby opening a reverse flow checking opening and closing portionby sliding movement of a stepped pistonforwardly, that is, fast fill and when the hydraulic pressure of the large diameter pressurizing chamberrises, a control valveescapes the hydraulic pressure of the large diameter pressurizing chamberto a reservoirto gradually lower in accordance with rise of the hydraulic pressure of the small diameter hydraulic chamberthereby capable of reducing a strange feeling in a pedal feeling caused by sudden pressure release of the large diameter pressurizing chamber

A master cylinder apparatus for a BBW system is provided, which enables accurate detection of a piston stroke without substantial increase in the size of a master cylinder. A master cylinder apparatus includes a master cylinder adapted to be connected to wheel cylinders through fail-safe valves, a stroke simulator for ensuring a desired stroke of a brake pedal upon receiving a brake fluid introduced from a fluid pressure chamber in the master cylinder through a simulator passage, and an opening/closing device for opening and closing the simulator passage. A stroke sensor for detecting a stroke of a primary piston is formed by a rotation angle detector, a sensor arm having one end connected to a rotary shaft of the rotation angle detector and a sensor pin extending from the primary piston. Linear motion of the primary piston is converted to rotational motion through engagement between the sensor pin and the sensor arm and is transmitted to the rotation angle detector.

Master cylinder apparatus

A master cylinder has a cylinder member in the shape of a cylinder, one end of which is closed, and a piston inserted in the cylinder member to form a pressure chamber in the cylinder member. The cylinder member is formed with a port for providing communication between the pressure chamber and a reservoir. The port is formed during casting of the cylinder member, thereby eliminating the need to form the port by boring, and forming the port into an elongated-hole shaped sectional configuration.

Master cylinder and method of producing the same

A master cylinder apparatus for a BBW system is provided, which eliminates a risk of brake delay, even with the use of a plunger-type master cylinder, and which therefore is able to achieve a reduction in size of a master cylinder. The master cylinder apparatus comprises a tandem-type master cylinder connected to wheel cylinders through fail-safe valves and a stroke simulator for ensuring a desired stroke of a brake pedal upon receiving a brake fluid introduced from a fluid pressure chamber in the master cylinder. The master cylinder is arranged in the form of a plunger-type master cylinder in which cup seals are provided on an inner surface of a bore of the cylinder body. A spring force of a second return spring for a secondary piston is set to be larger than that of a first return spring for a primary piston. A retracted position of the secondary piston is limited by a stopper pin extending through an oblong hole formed in the secondary piston.

A master cylinder that can sufficiently compensate for an ineffective fluid amount at an initial stage of a stroke, even at a time of sudden braking in a case where a hydraulic control unit is disposed between the master cylinder and a brake device, is provided. The master cylinder includes a control valve that releases hydraulic pressure in a large diameter pressurizing chamber to a reservoir side when the hydraulic pressure in the large diameter pressurizing chamber reaches a fluid-release pressure corresponding to hydraulic pressure introduced via a branched flow path that branches from a communication flow path that connects a hydraulic control unit and a small diameter hydraulic chamber. A restrictor is disposed in the branched flow path for introducing the hydraulic pressure to the control valve.

A master cylinder of the invention supplies a brake fluid from a large diameter pressurizing chamber to a small diameter hydraulic chamber by opening a reverse flow checking opening and closing portion by sliding movement of a stepped piston forwardly, that is, fast fill and when the hydraulic pressure of the large diameter pressurizing chamber rises, a control valve escapes the hydraulic pressure of the large diameter pressurizing chamber to a reservoir to gradually lower in accordance with rise of the hydraulic pressure of the small diameter hydraulic chamber , thereby capable of reducing a strange feeling in a pedal feeling caused by sudden pressure release of the large diameter pressuring chamber

A master cylinder including a cylinder having one end open to the outside. A secondary piston guide ring, a sleeve and a primary piston guide ring are adapted to be fitted in this order into the cylinder from the one open end. A piston is slidably fitted in an axial direction of the cylinder, into each of the secondary piston guide ring, the sleeve and the primary piston guide ring. A retainer is provided at the open end of the cylinder, and adapted to abut against the primary piston guide ring so as to prevent escape of the primary piston guide ring from the cylinder. An elastic member is provided between a rearward end portion of the sleeve and a forward end portion of the primary piston guide ring.

A master cylinder includes a cylinder, a piston slidably provided in the cylinder, an annular cup seal held on an inner circumferential surface of the cylinder, and a relief port formed in the piston. The piston and the cylinder define a pressure chamber for generating fluid pressure in front of the piston, and the cylinder and an outer circumferential surface of the piston define a fluid supply chamber which communicates with a reservoir. The cup seal is adapted to slide against the outer circumferential surface of the piston to separate the fluid supply chamber from the pressure chamber. The relief port provides communication between the pressure chamber and the fluid supply chamber. A control taper surface is formed on the outer circumferential surface of the piston rearwardly from the relief port. The control taper surface is tapered toward the front of the piston and is capable of abutting against an inner circumferential surface of the cup seal.

Growing community of inventors

Yamanashi-ken, Japan

Takato Ogiwara