Nissin Kogyo Co., Ltd.

Nec Corporation

Honda Motor Co., Ltd.

Nec Home Electronics, Inc.

Nissin Kogyo Kabushiki Kaisha

Isao Matsuno

Kazuhiro Tagata

Teruyasu Ishikawa

Kenji Suzuki

Yasushi Aoki

Joichi Nakano

Masayuki Seki

Yoshinobu Mizusaki

A vehicle braking system having a hydraulic booster which applies output hydraulic pressure of a hydraulic power source to a boosted hydraulic pressure chamber after regulating the output hydraulic pressure as a control piston balances a reaction force generated by hydraulic pressure of the boosted hydraulic pressure chamber with brake operating input. The boosted hydraulic pressure chamber faces a rear face of a master piston of a master cylinder; and a brake stroke simulator installed between a brake operating member and the control piston. The hydraulic booster includes a backup piston slidably housed in a casing with its front face turned to the boosted hydraulic pressure chamber and which can directly push the master piston in response to operation of the brake operating member when the hydraulic pressure of the boosted hydraulic pressure chamber decreases. The control piston and the brake stroke simulator are contained in the backup piston.

Vehicle braking system

In a vehicle braking system, a backup piston pushes a master piston directly from behind when hydraulic pressure of a boosted hydraulic pressure chamber decreases. The backup piston has a piston body which is slidably fitted in a casing, and a pusher which is slidably fitted in the casing with a seal diameter smaller than seal diameters of the master piston and the piston body and which extends to the front end of the piston body, to push the master piston from behind. An annular input chamber communicated with a hydraulic power source is formed between the backup piston and the casing. When the pusher pushes the master piston forward, amount of volume increased in the boosted hydraulic pressure chamber is set to be substantially equal to amount of volume decreased in the input chamber. Thus, it is possible to avoid increase in the hydraulic pressure of the boosted hydraulic pressure chamber during forward movement of the backup piston, using a simple configuration with a reduced number of parts.

A hydraulic controller includes: a pair of liquid chambers; and an on-off valve capable of opening and closing a flow channel on the side of the liquid chamber with a higher hydraulic pressure out of the pair of liquid chambers. The flow channel can provide communication between the pair of liquid chambers. A baffling device is provided in the liquid chamber with a lower hydraulic pressure, to baffle hydraulic fluid flowing from the liquid chamber with the higher hydraulic pressure. Thus, it is possible to reduce operating noise resulting from operation of the on-off valves.

Hydraulic controller

A vehicle braking system includes: a hydraulic booster which applies output hydraulic pressure of a hydraulic power source to a boosted hydraulic pressure chamber after regulating the output hydraulic pressure as a control piston operates to balance reaction force generated by hydraulic pressure of the boosted hydraulic pressure chamber with brake operating input; and a brake stroke simulator installed between the brake operating member and the control piston in order for a driver to feel operating strokes of the brake operating member. The brake stroke simulator has: an input member axially slidably housed in the control piston of a cylindrical shape and linked to the brake operating member; and an elastic body interposed between the input member and the control piston. The elastic body is formed into a tubular shape so as to come into resilient contact with an inner circumference of the control piston by expanding its diameter under the action of axial compressive force generated by forward movement of the input member. Consequently, the brake stroke simulator allows large hysteresis width in relationship between brake operating stroke and operating load.

A simulator piston is slidably fitted in a control piston to form a stroke liquid chamber between itself and an end wall of a control piston. A port which is closed at a forward limit of the control piston with respect to a backup piston is provided in the end wall of the control piston. A first reaction piston which constantly abuts against the end wall of the control piston and a second reaction piston which abuts against the end wall of the control piston when the control piston advances toward the backup piston through a predetermined travel distance or more, are relatively slidably mounted on the backup piston so that hydraulic pressure of the boosted hydraulic pressure chamber acts on their front ends. Thus, it is possible to curb increase in a stroke and reaction of a brake operating member which would be invalidated by a brake stroke simulator when a hydraulic power source fails, and avoid insufficient strokes of the brake operating member even if spikes are inputted.

In a proportional booster valve V, a primary reaction piston and a secondary reaction piston are provided between a control piston which faces at one end thereof toward a control pressure chamber into which hydraulic pressure outputted from a primary master cylinder is inputted a boost pressure chambers connected to secondary master cylinders, the primary reaction piston being adapted to transmit at all times to the control piston a reaction force corresponding to hydraulic pressure of the boost pressure chamber the secondary reaction piston being adapted to transmit to the control piston a reaction force corresponding to the hydraulic pressure of the boost pressure chamber as the hydraulic pressure of the boost pressure chamber exceeds a set hydraulic pressure.

Hydraulic brake booster

There are provided a master cylinder M and proportional pressure intensification valves V V for each drawing a boosting hydraulic pressure in proportion to an output hydraulic pressure outputted from the master cylinder M from a source of hydraulic pressure S into a hydraulic pressure boosting chamber wherein one of pairs of front wheel brakes Bfa, Bfb and rear wheel brakes Bra, Brb connects to output ports 1 , 1 of the master cylinder M, and the other pair connects to the hydraulic pressure boosting chambers of the respective proportional pressure intensification valves V V Accordingly, it is possible to provide a vehicle braking system comprising proportional pressure intensification valves for generating a boosted hydraulic pressure intensified in proportion to an output hydraulic pressure outputted from a master cylinder without any increase in unsprung load of the vehicle.

A hydraulic brake booster includes a primary master cylinder M , a hydraulic power source , a fluid tank and proportional booster valves Vf, Vr for boosting an output hydraulic pressure from the primary master cylinder M proportionally so as to supply the hydraulic pressure so boosted to wheel brakes Bfa, Bfb, Bra, Brb, the proportional booster valves being constructed as a spool type proportional booster valve.

An antilock brake control system for a vehicle includes a control start determining device for determining that an antilock brake control should be started, in response to a slip rate calculated based on a wheel speed and a presumed vehicle speed exceeding a start determination threshold value determined as a function of the presumed vehicle speed. The control start determining device changes the function of the presumed vehicle speed for calculating the start determination threshold value, based on the state of the antilock brake control for a wheel other than a wheel which is subjected to the determination by the control start determining device, and the results of the determinations by the road surface friction coefficient determining device and the bad-road determining device. Thus, appropriate antilock brake control for the situation of a road surface is conducted.

Antilock brake control system for vehicle

An antilock brake control system for a vehicle includes a PID calculating device for carrying out a PID calculation based on a deviation between a target slip rate determined based on a presumed vehicle speed and a slip rate, and the operation of a braking liquid pressure regulating device is controlled based on the result of the calculation in the PID calculating device. The PID calculating device is arranged to limit the PID calculation value within a predetermined limit value. Thus, it is possible to enhance the control followability in carrying out the control of a braking pressure based on the PID calculation.

An antilock brake control system in a vehicle is designed to retard the pressure increasing timing in one of front and rear wheel braking liquid pressure regulating devices which corresponds to a wheel having a smaller load share, until the wheel speed of such wheel is started to be reduced while following an actual vehicle speed after being restored to near the actual vehicle speed, when both of front and rear wheels are in antilock brake-controlled state. In this antilock brake control system, when the vehicle deceleration calculated based on a presumed vehicle speed is equal to or lower than a preset deceleration during retarding of the pressure increasing timing in a condition in which both of front and rear wheel brakes are in antilock brake controlled state, the braking liquid pressure control mode is switched over to a maintaining mode, but when the vehicle deceleration is higher than the preset deceleration, the control mode is switched over to a reducing mode, thereby controlling one of the front and rear wheel braking liquid pressure regulating devices which corresponds to the wheel having the smaller load share. Thus, when both of the front and rear wheels are in the antilock brake controlled states, a very accurate presumed vehicle speed can be calculated and moreover, the decrease in total braking force can be inhibited to the utmost.

Antilock brake control system in vehicle

An antilock brake control system in a vehicle includes a PID calculating device for carrying out a PID calculation based on a deviation between a target slip rate determined based on a presumed vehicle speed and a slip rate, so that the operation of braking fluid pressure regulating device is controlled based on the result of the calculation in the PID calculating device. In the antilock brake control system, a braking pressure control mode is decided based on the result of comparison of a PID calculation value calculated in the PID calculating device with a predetermined threshold value, so that the operation of braking fluid pressure regulating device is controlled in such control mode. When the amount of variation in PID calculation value within a predetermined time exceeds a predetermined value, a control mode different from a control mode decided from a current PID calculation value is selected. Thus, the occurrence of an excessive control and a control delay can be prevented and moreover, the control of the braking pressure can be performed in a simple structure enabling the use of an inexpensive on-off operated solenoid valve.

A master cylinder apparatus for a vehicle is adapted to be attached to a bar type steering handle. This master cylinder apparatus comprises a master cylinder attached directly or via a bracket to the bar type steering handle, an operating level pivoted on the bracket or a lever bracket of the master cylinder by means of a support shaft, an adjust bolt provided thrustable forward and backward to the operating lever, and a push rod having one end abutting on the rear end of a piston in the master cylinder and the other end pivoted on a free end of the adjust bolt. The forward/backward thrusting movement of the adjust bolt alters the distance between the support shaft and the point of action of the operating lever to the push rod, thereby changing the lever ratio of the operating lever to provide the operational feeling desired by a rider.

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Nagano, Japan

Isao Matsuno