Fluid-pressure and analogous brake systems – Speed-controlled – With failure responsive means
Reexamination Certificate
2000-11-29
2002-07-30
Rodriguez, Pam (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
With failure responsive means
C303S113300, C303S113400, C303S122090, C303S122110, C303S122130
Reexamination Certificate
active
06425644
ABSTRACT:
This application is based on Japanese Patent Application No. 11-367990 filed Dec. 24, 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 diagnosing device.
2. Discussion of Related Art
JP-A-10-100884 discloses an example of a braking pressure control apparatus including a diagnosing device. The braking pressure control apparatus disclosed in this publication includes (1) a first hydraulic system including a first hydraulic pressure source which is power-operated to pressurize a working fluid and capable of controlling a pressure of the pressurized fluid, for operating a brake with the pressurized fluid delivered from the first hydraulic pressure source, (2) a second hydraulic system including a second hydraulic pressure source in the form of a master cylinder which is operable by an operating force acting on a manually operated brake operating member, to pressurize the working fluid to a pressure corresponding to the operating force, for operating the brake with the pressurized fluid delivered from the master cylinder, (3) a switching device for selectively establishing a first state in which the brake is operated with the pressurized fluid delivered from the first hydraulic pressure source, and a second state in which the brake is operated with the pressurized fluid delivered from the second hydraulic pressure source, and (4) a diagnosing device operable to diagnose the second hydraulic system for any abnormality on the basis of the pressure of the fluid in the master cylinder and the pressure of the fluid in the brake.
In the braking pressure control apparatus disclosed in the publication identified above, the second hydraulic pressure source is adapted to deliver the pressurized fluid on the basis of the operating force of the brake operating member, but the pressure of the pressurized fluid delivered from the second hydraulic pressure source is not higher than a level corresponding to the operating force of the brake operating member. Therefore, the diagnosing device used in this conventional braking pressure control apparatus may suffer from a drawback if the diagnosing device is used for a second hydraulic system which includes a second hydraulic pressure source adapted to deliver the working fluid to a pressure higher than a level corresponding to the operating force of the brake operating member.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a braking pressure control apparatus including a diagnosing device suitable for diagnosing a second hydraulic system which includes a second hydraulic pressure source adapted to pressurize the working fluid to a pressure higher than a level corresponding to the operating force of the brake operating member.
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 pressure control apparatus for a hydraulically operated brake, comprising:
a first hydraulic system including a first hydraulic pressure-source which is power-operated to pressurize a working fluid and capable of controlling a pressure of the pressurized fluid, for operating the brake with the pressurized fluid delivered from the first hydraulic pressure source;
a second hydraulic system including a manually operable brake operating member, and a second hydraulic pressure source which is operable by an operating force acting on the brake operating member, to pressurize the working fluid to a pressure higher than a level corresponding to the operating force, for operating the brake with the pressurized fluid delivered from the second hydraulic pressure source;
a switching device operable to selectively establish a first state in which the brake is operated with the pressurized fluid delivered from the first hydraulic pressure source, and a second state in which the brake is operated with the pressurized fluid delivered from the second hydraulic pressure source; and
a diagnosing device operable to diagnose the second hydraulic system on the basis of a pressure of the fluid in the second hydraulic system.
In the braking pressure control apparatus according to the above mode (1) of this invention, the second hydraulic system provided to pressurize the fluid to a pressure level higher than a level corresponding to the operating force of the brake operating member can be diagnosed for any abnormality, by the diagnosing device on the basis of the fluid pressure in the second hydraulic system. As described in detail with respect to various specific forms or modes of this invention, the time required for diagnosing the second hydraulic system can be significantly reduced. In this respect, it is noted that a difference between the fluid pressure in the second hydraulic pressure source and the fluid pressure in the brake is generally larger than a difference between the fluid pressure in the master cylinder and the fluid pressure in the brake. If the second hydraulic system were diagnosed on the basis of the difference between the fluid pressure in the second hydraulic pressure source and the fluid pressure in the brake, as in the conventional braking pressure control apparatus wherein the second hydraulic system is diagnosed on the basis of the difference between the master cylinder pressure and the fluid pressure in the brake, it would take a longer time for the fluid pressure in the second hydraulic pressure source and the fluid pressure in the brake to become equal to each other. The present braking pressure control apparatus has a further advantage that a hydraulic booster included in the second hydraulic pressure source can be diagnosed. In the conventional braking pressure control apparatus, the hydraulic booster cannot be diagnosed.
The fluid pressure in the second hydraulic system on which the second hydraulic system is diagnosed may include a pressure of the fluid in the second hydraulic pressure source, a pressure of the fluid in a fluid passage connecting the second hydraulic pressure source and a cylinder for the brake, and a pressure in the brake during an operation of the brake with the pressurized fluid delivered from the second hydraulic pressure source.
Abnormalities of the second hydraulic system that can be detected by the diagnosing device include; abnormalities of elements of the second hydraulic system (e.g., an abnormality of the second hydraulic pressure source); and abnormalities of detectors provided to detect the operating states of the above-indicated elements (e.g., an abnormality of a pressure sensor for detecting the fluid pressure in the second hydraulic pressure source). Where the present braking pressure control apparatus is adapted to control the pressure of the fluid pressurized by the first hydraulic pressure source on the basis of the detectors indicated above, these detectors may be considered to be elements of the first hydraulic system. Since those detectors are used to detect the operating states of the elements of the second hydraulic system, however, the detectors are considered to be included in the second hydraulic system, in the present application.
In the above mode (1), the “level corresponding to the operating force” of the manually operable brake operating member is typically a pressure linearly proportional to the operating force of the brak
Kawahata Fumiaki
Miyazaki Tetsuya
Morikawa Hirohiko
Otomo Akihiro
Oliff & Berridg,e PLC
Rodriguez Pam
Toyota Jidosha & Kabushiki Kaisha
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