Honda Giken Kogyo Kabushiki Kaisha

Honda Motor Co., Ltd.

Nissin Kogyo Co., Ltd.

Citizen Watch Company, Ltd.

Kabushiki Kaisha Showa Seisakusho

Yasushi Aoki

Kenji Suzuki

Kazuhiro Tagata

Takeshi Ohba

Nobuyoshi Asanuma

Isao Matsuno

Yukihisa Ishii

Atsuo Ohno

Koji Sakai

Hiroshi Nakano

Hiroyuki Matsuo

Iwao Nakamura

Akiharu Kanagawa

Akihiro Tanaka

Hiroshi Yoshioka

Jiro Suzuki

Nobuharu Kuriki

Kouji Sakai

Tomoyuki Itoh

Hisahiro Ito

Ikuo Nonaga

Shinji Yoshikawa

Takashi Takeuchi

Tsunehiko Fukatsu

Takaomi Shirase

Makoto Kikuchi

Eiichiro Tanaka

Masaaki Azuma

Shigeo Tsuchigane

Katsuzo Hirayama

Ryosuke Fujiya

Tsutomu Naitou

Nobuo Mori

In a vehicular brake-by-wire braking system, during a four wheel simultaneous control mode when regeneration cooperative braking is implemented, a pair of electromagnetic isolation control valves and one of normally closed electromagnetic pressure relief valves corresponding to regeneration side left and right wheel brakes and normally closed electromagnetic pressure relief valves corresponding to non-regeneration side left and right wheel brakes are caused to operate to open and close, while the other of the normally closed electromagnetic pressure relief valves corresponding to the regeneration side left and right wheel brakes and the normally closed electromagnetic pressure relief valves corresponding to the non-regeneration side left and right wheel brakes are put in de-energized states in which the valves concerned are kept closed, and all normally open electromagnetic pressure supply valves are put in de-energized states in which the valves concerned are kept opened.

Vehicle regeneration cooperative braking system

A brake control device is provided, which is capable of providing a precise diagnosis on a trouble on a hydraulic pressure valve etc., so as to provide an appropriate output hydraulic pressure corresponding to a stroke amount of a brake pedal. In this device, an electromagnetic valve is provided on a hydraulic pressure passage allowing an auxiliary hydraulic pressure chamber to communicate with an accumulator, and is controlled to open when such a trouble occurs that output hydraulic pressure from the hydraulic pressure valve becomes lower than a predetermined range; and an electromagnetic valve is also provided on a hydraulic pressure passage allowing the auxiliary hydraulic pressure chamber to communicate with a reservoir, and is controlled to open when such a trouble occurs that the output hydraulic pressure from the hydraulic pressure valve becomes insufficiently reduced.

Brake control device

A fluid pressure booster includes: a control piston in which brake operation input acts in an advancing direction, and reaction based on fluid pressure of a booster fluid pressure generation chamber that generates fluid pressure for actuating a master piston acts in a retracting direction; a pressure increasing valve provided between the booster fluid pressure generation chamber and a fluid pressure generation source so as to open at the time of advance of the control piston and close at the time of retraction of the control piston; and a pressure reducing valve provided between a release chamber and the booster fluid pressure generation chamber so as to close at the time of the advance of the control piston and open at the time of the retraction of the control piston. The pressure increasing valve includes first valve means and second valve means that sequentially open according to an increase in the brake operation input, and a seal diameter of the second valve means is larger than that of the first valve means. Thus, it is possible to enhance initial response of the pressure increasing valve, and also enhance response of the pressure increasing valve when a brake operation member is strongly operated.

Fluid pressure booster

A normally closed secondary solenoid opening/closing valveis provided along a secondary branched fluid pipeestablishing a communication between an accumulatorand a reservoirthrough a fluid pressure input side to a fluid pressure output side of a regulator valve, and in the event that a fluid pressure supplied to the regulator valvedecreases down to or lower than a predetermined range due to something abnormal occurring in the accumulator, the state of the secondary solenoid opening/closing valveis changed over from a closed state to an opened state, whereby a residual pressure in the accumulatorand a residual pressure in the output fluid pressure chambercan be released through the reservoirwhich is in communication therewith through an output fluid pipeand the secondary branched fluid pipealong which the secondary opening/closing valveis provided.

Hydraulic brake device

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

A vehicle braking device includes a stroke simulator provided between a control piston of a fluid pressure booster and a brake operation member, wherein the control piston has an inner peripheral surface partially including a tapered surface with a decreasing diameter toward the front. The stroke simulator includes an input member housed in the control piston slidably in an axial direction backward of the tapered surface and connected to the brake operation member, and an elastic body interposed between the input member and the control piston and housed in the control piston. The elastic body has a cylindrical shape so as to be elastically deformed according to an action of an axial compressive force along with an advancing operation of the input member, and prevented from being deformed sequentially from the front by restraint with the tapered surface according to an increase in the axial compressive force. This provides a nonlinear characteristic in a relationship between a brake operation stroke and an operation load, and efficiently provides a hysteresis characteristic.

Vehicle braking device

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 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 an electric vehicle having front wheels braked by regenerative braking and hydraulic braking and rear wheels hydraulically braked, it is possible to check the magnitude of the regenerative braking force easily and accurately, by using a two-axle chassis dynamometer. Assuming that the front wheel braking force F.sub.2 ' detected by the chassis dynamometer is the total braking force C.sub.2 ' of the front and rear wheels, the total braking force C2' is broken down into component forces according to braking force distribution ratio data previously stored in a memory, to calculate a reference regenerative braking force A.sub.2 'D.sub.2 '. Based on the actually detected pedal depressing force A.sub.2 and the distribution ratio data, an imaginary pedal depressing force A.sub.2 ' is calculated that is required to produce a total braking force of the driven wheels and follower wheels equal to the braking force F.sub.2 ', generated by the driven wheels in the actual pedal depressing force A.sub.2. Based on the imaginary pedal depressing force A.sub.2 ' and the distribution ratio data, the imaginary regenerative braking force A.sub.2 'D.sub.2 ' that is produced by the driven wheels in the imaginary pedal depressing force A.sub.2 ', is calculated and then compared with the reference regenerative braking force A.sub.2 'D.sub.2 '.

Method of testing regenerative braking force in electric vehicle

In an electric vehicle in which regenerative braking is performed in preference to hydraulic braking, an uncomfortable vibration generated due to a sudden variation in the load of a motor, is prevented at the start of the regenerative braking. At the start of the braking, the regenerative braking force is gradually increased from a previously set regenerative initial value to a demanded braking force rather than being increased quickly to the demanded braking force, thereby preventing the generation of the vibration. A deficiency in the braking force during this time is compensated for with the hydraulic braking force. When the demanded braking force exceeds a regenerative acceptable value, the regenerative braking force does not exceed the acceptable value, and a deficiency of braking force thereafter is compensated for with the hydraulic braking force.

Brake system for an electric vehicle

An electric pump is turned ON and OFF by a main drive circuit including a negative pressure sensor for detecting a negative pressure in an accumulator, a first relay and a control device, and also turned ON and OFF by a back-up drive circuit including a negative pressure switch for detecting a negative pressure in an accumulator, and a second relay. For a period from the starting of the electric pump by the back-up drive circuit to the stopping of the electric pump by the main drive circuit, there is a period during which the electric pump is being driven only by the back-up drive circuit and a period during which the electric pump is being driven only by the main drive circuit. For each of these periods, a trouble of the main drive circuit and/or the back-up drive circuit can be determined by reference to a check signal indicative of the operational state of the electric pump. Thus, it is possible to reliably detect a trouble with the driving of the electric pump connected to the accumulator.

Electric pump control system

In an electric vehicle capable of being regeneratively braked, driven wheels connected to and driven by a motor are connected to and capable of being regeneratively braked by a brake control unit. When the regenerative braking of the driven wheels is being conducted by the brake control unit, the gear-shifting of an automatic transmission by a motor/AT control unit is prohibited. Thus, the need for continuance or control of the regenerative braking during gear-shifting is eliminated, thereby preventing a reduction in braking force during the gear-shifting and the generation of a shock.

Brake system in electric vehicle

In an electric vehicle capable of regenerative braking of wheels, a differential pressure regulating valve is interposed between a master cylinder for generating a hydraulic braking pressure by operation of a brake operating element and a brake cylinder for a driven wheel. In a first region in which an input hydraulic pressure into the differential pressure regulating valve is equal to or less than a predetermined value, an output hydraulic pressure from the differential pressure regulating valve is maintained at zero, and in a second region in which the input hydraulic pressure exceeds the predetermined value, the output hydraulic pressure is lower than the input hydraulic pressure by the predetermined value. Further, in the first region, a regenerative braking force is determined in proportion to a quantity of operation of the brake operating element, and in the second region, the regenerative braking force is maintained at a constant value irrespective of the quantity of operation of the brake operating element. Thus, the regenerative braking force is preferentially generated at the start of braking, and after the regenerative braking force reaches a limit, a deficiency of braking force can be made up by the hydraulic braking force. Moreover, a sum total of the hydraulic braking force and the regenerative braking force can be proportioned to the quantity of operation of the brake operating element.

Braking system for electric vehicle

In a brake system in an electric vehicle comprising a follower wheel capable of being hydraulically braked by the operation of a brake operating element, and a driving wheel connected to and driven by a motor using a battery as an energy source and capable of being hydraulically braked and regeneratively braked by the operation of the brake operating element, the regenerative braking force for the driving wheel exceeds a theoretic distribution characteristic of the braking forces for the follower and driving wheels at least during an initial braking. Thus, it is possible to sufficiently perform the recovery of the kinetic energy of the vehicle by the regenerative braking to increase the possible travel distance of the vehicle. In addition, at least during an initial braking, the hydraulic braking of the driving wheel and the hydraulic braking of the follower wheel are inhibited, and substantially only the regenerative braking of the driving wheel is performed. Thus, it is possible to recover the kinetic energy of the vehicle without consumption thereof by the hydraulic braking to increase the possible travel distance of the vehicle.

The switchover is mode from a regenerative braking-preference mode in which the braking force for follower and driving wheels are more than a theoretical braking force distribution characteristic for follower and driving wheels, to a usual mode in which a braking force distribution characteristic thereof corresponds to the theoretical braking force distribution characteristic, is carried along an equal braking force line which is the sum of the braking forces for the follower and driving wheels. Thus, the sum total of the braking forces over the entire vehicle is kept constant even if the distribution of the braking forces for the follower and driving wheels is varied and therefore, a smooth braking is possible without a degradation of the steering stability. In addition, the switchover in mode from the regenerative-preference mode to the usual mode is carried out when the time-differentiation value of a wheel speed of the follower wheel or the driving wheel exceeds a predetermined value. Thus, when the friction coefficient of a road surface is large so that a small locking tendency of a wheel may be produced during braking, the regenerative braking-preference mode can be selected, thereby increasing the effect of recovery of energy by the regenerative braking.

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Saitama, Japan

Yasushi Aoki