Brakes – Operators – Fluid pressure
Reexamination Certificate
1999-04-20
2001-03-06
Butler, Douglas C. (Department: 3613)
Brakes
Operators
Fluid pressure
C303S113200, C303S119100, C303S116100
Reexamination Certificate
active
06196365
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a braking hydraulic pressure control apparatus for a vehicle and, more particularly, to an apparatus which is capable of anti-lock brake control and traction control over driving-wheel brakes.
2. Background Description
A braking hydraulic pressure control apparatus of the sort mentioned above is discussed in Japanese Patent Publication No. Hei. 5-65388.
In such a braking hydraulic pressure control apparatus, a switching valve means is actuated during normal braking operation. During normal braking operations and in the anti-lock brake control mode, a hydraulic passage connected to the discharge port of a pump is connected to a master cylinder, and an open passage connected to an inlet port of the pump is shut off from the master cylinder. When driving-wheel traction control is carried out, the switching valve means is actuated so that the open passage is connected to the master cylinder and the hydraulic passage is shut off from the master cylinder.
Prior to filling the master cylinder with brake fluid, a vacuum is drawn from the master cylinder side in order to remove air from the system. A three-port, two-position electromagnetic switching valve capable of switching between the following two positions has been employed as a switching valve means in the prior art. In the first position, the master cylinder is connected to the hydraulic passage, but is shut off from the open passage. In the second position, the master cylinder is connected to the open passage, but is shut off from the hydraulic passage. Consequently, in order to draw a vacuum, the three-port, two-position electromagnetic switching valve needs to be switched in two stages. In other words, a first vacuum is drawn when the three-port, two-position electromagnetic switching valve is positioned so that the master cylinder is connected to the hydraulic passage, but shut off from the open passage. Air can then be removed from the hydraulic pressure system between the driving- wheel brake and the master cylinder, and between the discharge port of the pump and the master cylinder. The three-port, two-position electromagnetic switching valve is then switched so that the master cylinder is connected to the open passage, but shut off from the hydraulic passage. A second vacuum is drawn from the hydraulic pressure system among the inlet port of the pump, the reservoir and the master cylinder. Although air can be sufficiently removed from the described braking control apparatus, the equipment utilized to remove the air tends to be complex because the valve position of the three-port, two-position electromagnetic switching valve has to be moved when removing air.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a braking hydraulic pressure control apparatus for a vehicle that provides traction control for the driving-wheels.
Another object of the present invention is to improve the way in which air is removed from the hydraulic pressure system.
Another object of the invention is to allow the use of simpler air-removing equipment during the air-removal process.
According to the invention, there is provided a braking hydraulic pressure control apparatus for a vehicle comprising a switching valve means capable of switching between communicating and shut-off states between a master cylinder and hydraulic passages, and between communicating and shut-off states between the master cylinder and open passages. A driving-wheel control valve means is provided for controlling hydraulic pressure in driving-wheel brakes by switching between communicating and shut-off states between the hydraulic passages and the respective driving-wheel brakes, between communicating and shut-off states between the driving-wheel brakes and reservoirs, and between communicating and shut-off states between pumps whose inlet ports are connected to the respective reservoirs and whose discharge ports are connected to the respective hydraulic passages. The open passages are connected to the inlet ports of the respective pumps. The switching valve means include opened-type electromagnetic valves positioned between the master cylinder and the hydraulic passages, and closed-type electromagnetic valves positioned between the master cylinder and the open passages, respectively.
When the work of removing air is done by drawing a vacuum in the direction of the master cylinder prior to the filling of brake fluid, the closed-type electromagnetic valves are excited and opened. A connection is therefore established between the front wheel brake and the master cylinder; between the discharge port of the pump and the master cylinder; and among the inlet port of the pump, the reservoir and the master cylinder. Therefore, removal of air can be made at a time by drawing a vacuum in the hydraulic pressure system related to the driving-wheel brake, thus improving the ability to remove air from the system. Moreover, the air-removing equipment can also be simplified because it is unnecessary to switch the operation of the switching valve means during the air-removing work.
The invention is also characterized by including a driven-wheel control valve means for controlling hydraulic pressure in driven-wheel brakes by switching between communicating and shut-off states between the master cylinder and the driven-wheel brakes, and between communicating and shut-off states between the driven-wheel brakes and the respective reservoirs. Having this control valve means also improves the ability to remove air from the system since air can be removed from the hydraulic pressure system related to the driven-wheel brake simultaneously when air is removed from the hydraulic pressure system related to the driving-wheel brake.
REFERENCES:
patent: 4989924 (1991-02-01), Toda et al.
patent: 5026127 (1991-06-01), Arikawa
patent: 5156448 (1992-10-01), Kirstein
patent: 5169214 (1992-12-01), Holzman et al.
patent: 5205623 (1993-04-01), Holzmann et al.
patent: 5275476 (1994-01-01), Maisch
patent: 5549366 (1996-08-01), Toda et al.
patent: 5961188 (1999-10-01), Sawada
patent: 6056370 (2000-05-01), Okuya et al.
patent: 4365660 (1992-12-01), None
patent: 5-65388 (1993-09-01), None
patent: 0016267 (2000-01-01), None
Butler Douglas C.
McGuireWoods LLP
Nissin Kogyo Co. Ltd.
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