Fluid-pressure and analogous brake systems – With pump – Pressure control
Reexamination Certificate
2001-12-26
2003-08-12
Lavinder, Jack (Department: 3683)
Fluid-pressure and analogous brake systems
With pump
Pressure control
C303S116200, C303S015000, C303S115400, C303S116100
Reexamination Certificate
active
06604795
ABSTRACT:
This application is based on Japanese Patent Application No. 2000-402219 filed on Dec. 28, 2000, No. 2000-402220 filed on Dec. 28, 2000, and No. 2001-246366 filed on Aug. 15, 2001, the contents of which are 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-9-511967 discloses a braking system including (a) brake cylinder arranged to operate a brake with a hydraulic pressure, (b) a master cylinder including a pressurizing piston which is operated according to an operation of a manually operable brake operating member, to pressurize a working fluid in a pressurizing chamber formed in front of the pressurizing piston, (c) a high-pressure source in the form of a pressure-control cylinder including a control piston operated according to an operation of an electric motor, and having a control pressure chamber which is formed in front of the control piton and which is connected to the brake cylinder, and (d) a braking-pressure control device operable to control an electric energy to be supplied to the electric motor, for controlling a pressure of the fluid in the control pressure chamber of the pressure control cylinder, to thereby control the fluid pressure in the brake cylinder.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a braking system which provides improvements over a known braking system as disclosed in the above-identified publication, for instance, improved efficiency of utilization of the electric energy and/or reduction of a required amount of consumption of the electric energy in various manners.
The above object may be achieved by a braking system constructed 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) a hydraulically operated brake cylinder for operating a brake, (b) a master cylinder operable according to an operation of a manually operable brake operating member, to pressurize a working fluid, (c) a master-cylinder cut-off valve connected to the master cylinder, (d) a high-pressure source disposed between the master-cylinder cut-off valve and the brake cylinder and operable according to the operation of the brake operating member, to pressurize the fluid, the high-pressure source including a power-operated drive device and a pressure-control cylinder having a control piston which is operable by the power-operated drive device and which partially defines a front control-pressure chamber and a rear pressure chamber on respective front and rear sides thereof, the front control-pressure chamber being connected to the brake cylinder while the rear pressure chamber being held in communication with the master cylinder, and (e) a braking-pressure control device operable to control the power-operated drive device, to thereby control the pressure of the fluid in the brake cylinder.
In the braking system according to the above mode (1) of the present invention, the brake cylinder can be operated with not only the pressure of the fluid pressurized by the high-pressure source, but also the pressure of the fluid which is pressurized by the master cylinder. In other words, the pressurized fluid delivered from the master cylinder can be utilized, in addition to the pressurized fluid delivered from the high-pressure source, to operate the brake cylinder. Accordingly, the high-pressure source can be economically operated with a comparatively small amount of electric energy, and the brake cylinder can be operated to produce a relatively high braking effect. The fluid pressure in the brake cylinder is controlled by the pressure-control cylinder operated by the power-operated drive device under the control of the braking-pressure control device. Further, the rear pressure chamber is connected to the master cylinder such that the rear pressure chamber is normally held in communication with the master cylinder, so that the fluid pressurized by the master cylinder can be utilized to control the fluid pressure in the brake cylinder. In a conventional braking system wherein the fluid pressure in the brake cylinder is controlled by the pressure-control cylinder, the master cylinder is communicated with a stroke simulator but is not utilized to control the fluid pressure in the brake cylinder. In the braking system according to the above mode (1), on the other hand, the pressurized fluid delivered from the master cylinder is used to control the brake cylinder pressure, so that the drive force required to be produced by the power-operated drive device to operate the control piston of the pressure-control cylinder is accordingly reduced
(2) A braking system comprising: (a) a hydraulically operated brake cylinder for operating a brake, (b) a master cylinder operable according to an operation of a manually operable brake operating member, to pressurize a working fluid, (c) a master-cylinder cut-off valve connected to the master cylinder, (d) a high-pressure source disposed between the master-cylinder cut-off valve and the brake cylinder and operable according to the operation of the brake operating member, to pressurize the fluid, the high-pressure source including a power-operated drive device and a pressure-control cylinder having a control piston which is operable by the power-operated drive device and which partially defines a front control-pressure chamber and a rear pressure chamber on respective front and rear sides thereof, the front control-pressure chamber being connected to the brake cylinder while the rear pressure chamber being normally held in communication with the master cylinder, and (e) a braking-pressure control device operable to control the power-operated drive device, to thereby control the pressure of the fluid in the brake cylinder.
The braking system according to the above mode (2) has substantially the same advantage as the braking system according to the above mode (1).
(3) A braking system according to the above mode (2), further comprising a fluid passage connecting the master cylinder and the control-pressure chamber, and wherein the master-cylinder cut-off valve is disposed in the fluid passage, and has an open state in which the master cylinder and the control-pressure chamber are communicated with each other, and a closed state in which the master cylinder and the control-pressure chamber are isolated from each other.
In the braking system according to the above mode (3), the master-cylinder cut-off valve is disposed in the fluid passage connecting the master cylinder and the control-pressure chamber of the pressure-control cylinder. When the master-cylinder cut-off valve is placed in the open state, the master cylinder is communicated with the brake cylinder through the cut-off valve, so that the pressurized fluid delivered from the master cylinder is supplied to the brake cylinder, to operate the brake. When the master-cylinder cut-off valve is placed in the closed state, the control-pressure chamber is isolated from the master cylinder, and the fluid pressurized in the control-pressure chamber is delivered to the brake cylinder, to operate the brake.
(4) A braking system according to the above mode (2) o (3), wherein the braking-pressure control device includes an operation detecting portion operable to detect an operating state of the brake operating member, the braking-pressure contro
Isono Hiroshi
Mizutani Yasuji
Yamamoto Takayuki
Lavinder Jack
Oliff & Berridg,e PLC
Pezzlo Benjamin A
Toyota Jidosha & Kabushiki Kaisha
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