Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
2000-10-03
2002-03-12
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S114100, C303S114300, C303S014000, C303S122090, C303S122130, C303S116100, C303S003000, C303S010000, C303S152000, C303S115100, C303SDIG001, C188S358000
Reexamination Certificate
active
06354672
ABSTRACT:
This application is based on Japanese Patent Application No. 11-288270 filed Oct. 8, 2000, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a braking system.
2. Discussion of Related Art
JP-A-5-65060 discloses an example of a braking system, which includes (1) a brake cylinder, (2) a master cylinder operable by a brake operating member, for mechanically pressurizing a working fluid such that the pressure of the pressurized fluid corresponds to an operating force acting on the brake operating member, (3) a power-operated hydraulic pressure source operable with an electric energy supplied thereto, for generating a braking force corresponding the operating force of the brake operating member, and (4) a fluid-communication switching device for fluid communication of the brake cylinder with the power-operated hydraulic pressure source when the power-operated hydraulic pressure source is normal, and with the master cylinder when the power-operated hydraulic pressure source is defective. In this braking system, the power-operated hydraulic pressure source is arranged such that the pressure of the fluid pressurized by the power-operated hydraulic pressure source is higher than that of the fluid pressurized by the master cylinder. Accordingly, when the brake cylinder which has been held in communication with the power-operated hydraulic pressure source is brought into communication with the master cylinder upon detection of a defect of the power-operated hydraulic pressure source, the braking force corresponding to a given operating force of the brake operating member varies unexpectedly to the operator of an automotive vehicle on which the braking system is provided.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a braking system which is arranged to minimize a change in the braking force which is unexpected to the vehicle operator.
The above object may be achieved according to any one of the following modes of the present invention, each of which is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate and clarify possible combinations of elements or technical features. It is to be understood that the present invention is not limited to the technical features or any combinations thereof which will be described for illustrative purpose only. It is to be further understood that a plurality of elements or features included in any one of the following modes of the invention are not necessarily provided all together, and that the invention may be embodied without some of the elements or features described with respect to the same mode.
(1) A braking system comprising:
a brake cylinder;
a first hydraulic pressure source including a first pump device operable to pressurize a working fluid;
a second hydraulic pressure source operable in response to an operation of a brake operating member, to pressurize the fluid to a pressure higher than a value corresponding to an operating force acting on the brake operating member;
a brake-cylinder-pressure control device operable when the brake cylinder is disconnected from the second hydraulic pressure source, to control the pressure of the fluid pressurized by the first hydraulic pressure source, for thereby controlling a pressure of the fluid in the brake cylinder to a value determined on the basis of the operating force; and
an emergency communication device operable when at least one of the brake-cylinder-pressure control device and the first pump device fails to normally function, to hold the brake cylinder in communication with the second hydraulic pressure source.
When the brake operating member is operated in the braking system according to the above mode (1) of this invention, the pressure of the fluid pressurized by the first hydraulic pressure is controlled by the brake-cylinder-pressure control device while the brake cylinder is disconnected from the second hydraulic pressure source, such that the fluid pressure in the brake cylinder is controlled to a value determined by the operating force of the brake operating member. The brake-cylinder-pressure control device may be adapted to control the first pump device of the first hydraulic pressure source, to thereby control the fluid pressure in the brake cylinder. Alternatively, the brake-cylinder-pressure control device may include a solenoid-operated control valve for controlling the fluid pressure in the brake cylinder, and a control-valve control device for controlling the solenoid-operated control valve.
Where at least one of the brake-cylinder-pressure control device and the first pump device of the first hydraulic pressure source fails to normally function, the brake cylinder is brought into fluid communication with the second hydraulic pressure source. When the brake operating member is operated, the second hydraulic pressure source pressurizes the fluid to a pressure higher than a value corresponding to the operating force of the brake operating member, and the thus pressurized fluid is delivered to the brake cylinder. Thus, the fluid pressure in the brake cylinder can be made higher in the present braking system than in a braking system in which the second hydraulic pressure source pressurizes the fluid to a pressure value corresponding to the operating force of the brake operating member. This arrangement is effective to reduce the amount of unexpected change of the braking force corresponding to a given amount of operating force of the brake operating member, which unexpected change takes place due to a defect of the brake-cylinder-pressure control device and/or the first pump device.
The first pump device fails to normally function when there is any one of defects such as: a defect (e.g., excessive voltage drop) of the electric power source provided to supply the first pump device with an electric energy; a defect of an electric motor of the first pump device; a defect of a control device (including a driver circuit, and a computer) for controlling the electric motor; and a defect of any sensor for detecting the operating state (e.g., rotating speed) of the electric motor. Where the brake-cylinder-pressure control device includes a solenoid-operated control valve and a control-valve control device for controlling the control valve, the brake-cylinder-pressure control device fails to normally function when there is any one of defects such as: a defect of a solenoid-operated control valve; a defect of an electric power source used to control the control valve; a defect of the control-valve control device; and a defect of any sensor used for controlling the control valve to control the fluid pressure in the brake cylinder. Where the brake-cylinder-pressure control device includes a controller adapted to control the first pump device of the first hydraulic pressure source so as to control the fluid pressure in the brake cylinder, the brake-cylinder-pressure control device fails to normally function when there is any one of defects such as: a defect of the controller; and a defect of any sensor used to control the first pump device.
(2) A braking system according to the above mode (1), wherein the second hydraulic pressure source includes at least one of a booster for boosting the operating force of the brake operating member, and a pressure-increasing device for increasing the pressure of the fluid pressurized when the brake operating member is operated, the braking system further comprising an energy storing portion for storing an energy to be used to operate at least one of the booster and the pressure-increasing device.
In the braking system according to the above mode (2) wherein the energy storing portion is provided, the pressure-increasing device and/or the booster of the second hydraulic pressure source can be operated by the energy stored in the energy storing portion, even if the braking system becomes unable to generate an energy due to an electrical failure, for instance. Thus, the pre
Kawahata Fumiaki
Miyazaki Tetsuya
Nakamura Eiji
Otomo Akihiro
Toda Hiroshi
Butler Douglas C.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
LandOfFree
Braking system wherein brake cylinder is communicated with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Braking system wherein brake cylinder is communicated with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Braking system wherein brake cylinder is communicated with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2868143