Fluid-pressure and analogous brake systems – Speed-controlled – With failure responsive means
Reexamination Certificate
2001-08-30
2003-09-16
Lavinder, Jack (Department: 3683)
Fluid-pressure and analogous brake systems
Speed-controlled
With failure responsive means
C303S122100, C303S011000
Reexamination Certificate
active
06619762
ABSTRACT:
This application is based on and claims priority under 35 U.S.C. §119 with respect to Japanese Patent Application 2000-261929, filed on Aug. 30, 2000, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
This invention generally relates to a hydraulic brake apparatus for a vehicle. More particularly, the present invention pertains to a hydraulic brake apparatus for the vehicle having an auxiliary hydraulic pressure source for generating a power hydraulic pressure to be used to apply brake pressure to a wheel cylinder associated with a wheel of the vehicle in response to operation of a brake operating member, and a warning mechanism for informing of a failure of an outputted hydraulic pressure generated by the auxiliary hydraulic pressure source.
BACKGROUND OF THE INVENTION
Various types of hydraulic brake apparatus for a vehicle are known. At least some known types of hydraulic brake apparatus include a master cylinder such as a hydraulic pressure generating apparatus for generating a brake pressure in response to operation of a brake operating member, and an auxiliary hydraulic pressure source for generating a power hydraulic pressure. The auxiliary hydraulic pressure source generally includes a hydraulic pump and an accumulator. These hydraulic brake apparatus typically require an adjustment of the power hydraulic pressure generated by the auxiliary hydraulic pressure source and an adequate warning in response to an excessive reduction of the power hydraulic pressure.
For example, U.S. Pat. No. 5,000,520 (corresponding to a Japanese Patent Application published on May 24, 1990 as Toku-Kai-Hei 2 (1990)-136365) discloses a hydraulic brake apparatus in which the power hydraulic pressure varies between 140-180 bar under operation of the auxiliary hydraulic pressure source. The pumping operation of a hydraulic pump is started in response to the reduction of the power hydraulic pressure below a predetermined lower limit and is continued until the power hydraulic pressure reaches an upper limit. A warning signal is generated in response to the reduction of the power hydraulic pressure below a predetermined lowest limit set at 105 bar.
In the apparatus disclosed in the above-mentioned U.S. patent, to operate the hydraulic pump and generate the warning signal when a relay contact fails, an electric circuit arrangement is provided that includes a pressure responsive switch and a relay arrangement for controlling operation of an electric driving motor connected to the hydraulic pump to maintain the power hydraulic pressure within a predetermined range (e.g. 140-180 bar), another pressure responsive switch for generating the warning signal in response to the reduction of the power hydraulic pressure below the predetermined lower limit, and another relay for controlling the operation of the electric driving motor.
In the apparatus described in the above-mentioned U.S. patent, if the hydraulic pump is normally operable, it is able to maintain a driving condition of the hydraulic pump in response to a reduction of the power hydraulic pressure. However, if the capacity of the accumulator is small, the warning signal may be frequently generated during normal operation of the hydraulic pump. Further, the electric circuit arrangement including the two pressure responsive switches and the two relays increases the manufacturing cost associated with the apparatus.
A need thus exists for a hydraulic brake apparatus having an auxiliary hydraulic pressure source for generating a power hydraulic pressure in which, if the hydraulic pump is normally operating, the operation of the hydraulic pump is controlled in response to varying the power hydraulic pressure to generate the power hydraulic pressure without generating frequent warning signals.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a hydraulic brake apparatus for a vehicle includes a reservoir containing brake fluid, a wheel cylinder associated with a road wheel of the vehicle, and an auxiliary hydraulic pressure source for generating a power hydraulic pressure that is used to apply brake pressure to the wheel cylinder in response to a braking requirement. The auxiliary hydraulic pressure source includes a hydraulic pump for increasing the pressure of the brake fluid supplied from the reservoir to generate the power hydraulic pressure. A power hydraulic pressure observing device observes continuously the power hydraulic pressure and generates a signal for controlling operation of the hydraulic pump based on the power hydraulic pressure. A pump operating condition judging mechanism judges whether or not the operating condition of the hydraulic pump satisfies a predetermined operating condition based on the power hydraulic pressure observed by the power hydraulic pressure observing means. A warning mechanism compares the power hydraulic pressure observed by the power hydraulic observing device with a predetermined hydraulic pressure and generates a warning signal indicating a failure of the power hydraulic pressure when the power hydraulic pressure is less than the predetermined hydraulic pressure and the pump operating condition judging mechanism judges that the operating condition of the hydraulic pump does not satisfy with the predetermined operating condition.
The pump operating condition judging mechanism detects a rising tendency of the power hydraulic pressure observed by the power hydraulic pressure observing device, and the pump operating condition judging mechanism judges that the operating condition of the hydraulic pump satisfies the predetermined operating condition when the power hydraulic pressure observed by the power hydraulic pressure observing device shows the rising tendency while the power hydraulic pressure observed by the power hydraulic pressure observing device is less than the predetermined hydraulic pressure.
The pump operating condition judging mechanism detects a rising tendency of the power hydraulic pressure observed by the power hydraulic pressure observing device and detects the starting of driving of the hydraulic pump, and the pump operating condition judging means judges that the operating condition of the hydraulic pump satisfies the predetermined operating condition when the power hydraulic pressure observed by the power hydraulic pressure observing device shows the rising tendency from a zero pressure within a predetermined time period after the driving of the hydraulic pump is started.
The pump operating condition judging mechanism detects a rising tendency of the power hydraulic pressure observed by the power hydraulic pressure observing device, and the pump operating condition judging mechanism judges that the operating condition of the hydraulic pump satisfies the predetermined operating condition when the power hydraulic pressure observed by the power hydraulic pressure observing device shows the rising tendency within the predetermined time period after the power hydraulic pressure observed by the power hydraulic pressure observing device falls below the predetermined hydraulic pressure.
The pump operating condition judging mechanism calculates a changing rate of the power hydraulic pressure observed by the power hydraulic pressure observing device and detects a starting of a driving of the hydraulic pump, and the pump operating condition judging mechanism judges that the operating condition of the hydraulic pump satisfies the predetermined operating condition when the changing rate of the power hydraulic pressure observed by the power hydraulic pressure observing device becomes a positive rate within a predetermined time period after the driving of the hydraulic pump is started.
The pump operating condition judging mechanism calculates a changing rate of the power hydraulic pressure observed by the power hydraulic pressure observing device, and the pump operating condition judging mechanism judges that the operating condition of the hydraulic pump satisfies the predetermined operating condition when the changing rate of the power hydraul
Nishii Michiharu
Nitta Hirofumi
Oishi Masaki
Terazawa Tadashi
Aisin Seiki Kabushiki Kaisha
Burns Doane , Swecker, Mathis LLP
Lavinder Jack
Sicconolfi Robert A.
LandOfFree
Hydraulic brake apparatus for a vehicle does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic brake apparatus for a vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic brake apparatus for a vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3087070