Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
2000-09-29
2002-02-12
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S113100, C303S115100, C303S162000, C303S119200, C303SDIG004
Reexamination Certificate
active
06345869
ABSTRACT:
This application is based on Japanese Patent Application Nos. 11-282602 filed Oct. 4, 1999 and 11-312629 filed Nov. 2, 1999, 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 pressure control apparatus including a pressurizing device in a braking system.
2. Discussion of Related Art
Japanese Patent Application No. 11-123604 which was filed by the assignee of the present application and which has not been published discloses an example of such a braking pressure control apparatus equipped with a pressurizing device. The braking pressure control apparatus disclosed in this application includes (1) a pressurizing device operable to pressurize a working fluid and control the pressure of the pressurized fluid to a desired value, (2) a plurality of pressure control valve devices each of which is disposed between the pressurizing device and at least one of a plurality of brake cylinders in the braking system and is operable to control flows of the fluid between the pressurizing device and the corresponding at least one brake cylinder, for thereby regulating the fluid pressure in each of the corresponding at least one brake cylinder, and (3) a pressurizing-device control device for controlling the pressurizing device to control the pressure of the fluid pressurized by the pressurizing device according to an operating state of a brake operating member. In the braking pressure control apparatus disclosed in the above-identified application, the pressure of the fluid delivered from the pressurizing device is controlled according to the operating state of the brake operating member, and each pressure control valve device is controlled to control the fluid pressure in each of the corresponding at least one brake cylinder in an anti-lock pressure control fashion, for example, such that the slipping state of each of a plurality of vehicle wheels corresponding to the respective brake cylinders is kept optimum.
According to the braking pressure control apparatus disclosed in the above-identified application, the pressurizing device is controlled according to the operating state of the brake operating member, irrespective of the operating states of the individual pressure control valve devices. However, it was found that the pressure of the pressurized fluid delivered from the pressuring device is influenced by the flows of the fluid through each pressure control valve device.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a braking pressure control apparatus wherein the pressure of the pressurized fluid delivered from the pressurizing device is less likely to be influenced by the fluid flows through the pressure control valve devices.
The above object may be achieved according to any one of the following modes or forms 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 pressure control apparatus for a braking system having a plurality of brake cylinders, comprising:
a pressurizing device capable of pressurizing a working fluid and controlling a pressure of the pressurized fluid;
a plurality of pressure control valve devices each of which is disposed between the pressurizing device and at least one of the plurality of brake cylinders and is operable to control flows of the fluid between the pressurizing device and the corresponding at least one brake cylinder, for thereby regulating the fluid pressure in the corresponding at least one brake cylinder; and
a pressurizing-device control device operable to control the pressurizing device for controlling an output pressure of the pressurizing device, on the basis of an operating state of each pressure control valve device, which operating state determines a state of flow of the fluid between said pressurizing device and the corresponding at least one brake cylinder.
In the braking pressure control apparatus constructed according to the above mode (1) of this invention, the pressurizing-device control device is adapted to control the pressurizing device for controlling the output pressure of the pressurizing device, on the basis of the state of flow of the fluid through each of the pressure control valve devices between the pressurizing device and the corresponding at least one brake cylinder, so that the undesirable influence of the fluid flow between the pressurizing device and the wheel brake cylinder or cylinders on the output pressure of the pressurizing device can be reduced.
Where each pressure control valve device has a fluid-supply state for supplying the pressurized fluid from the pressurizing device to the corresponding brake cylinder or cylinders, and a closed state for inhibiting the supply of the pressurizing fluid from the pressurizing device to the brake cylinder or cylinders, for instance, the pressurizing-device control device may be arranged to control the pressuring device in different manners in the open and closed states of the pressure control valve device, respectively, or in one of different manners which is selected according to a switching operation of the pressure control valve device between the fluid-supply and closed states.
Where each pressure control valve device has a fluid-discharge state for discharging the pressurized fluid from the brake cylinder or cylinders back to the pressurizing device, and a closed state for inhibiting the discharge flow of the pressurized fluid from the brake cylinder or cylinders to the pressurizing device, for instance, the pressurizing-device control device may be arranged to control the pressurizing device in different manners in the fluid-discharge state and the closed state, respectively, or in one of different manners which is selected according to a switching operation of the pressure control valve device between the fluid-discharge and closed states.
Where each pressure control valve device is capable of changing the amounts of the fluid that are supplied to and discharged from each brake cylinder, the pressurizing-device control device may control the pressurizing device in different manners depending upon the amounts of supply and discharge of the fluid to and from each brake cylinder.
The fluid flow through each pressure control valve device has a particularly large influence on the output pressure of the pressurizing device when the pressurizing device is placed in a constant or substantially constant operating state. When the operating state of the pressurizing device is held constant, the output pressure of the pressurizing device is usually held substantially constant. If the pressure control valve device is switched from the closed state to the fluid-supply state while the output pressure of the pressurizing device is held substantially constant, the output pressure is reduced. By controlling the pressurizing device so as to increase its output pressure upon switching of the pressure control valve device from the closed state to the fluid-supply state, therefore, the reduction of the output pressure due to the switching of the pressure control valve device to the fluid-supply state can be reduced. By controlling the pressurizing device so as to reduce its output pressure upon switching of the pressure control valve device from the closed state to the fluid-discharge state, the increase of the output pressure due to the switching of the pressure control valve device to the fluid-discharg
Matsuo Yoshiaki
Motoyoshi Kiyotaka
Butler Douglas C.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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