Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-01-29
2001-04-10
Schwartz, Christopher P. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C091S369200, C091S37600A
Reexamination Certificate
active
06213569
ABSTRACT:
SUMMARY OF THE INVENTION
This invention generally relates to a pressure generator. More particularly, the present invention pertains to a pressure generator used in a motor vehicle for generating a braking force.
BACKGROUND OF THE INVENTION
Japanese Unexamined Patent Publication No. Hei.9-123896 discloses a pressure generator that includes a housing in which is formed a pressure chamber, and a power piston disposed inside the pressure chamber for advancing and retreating movement with respect to the housing, with the power piston being provided with a movable wall which divides the pressure chamber into a front chamber connected to a vacuum source and a rear chamber selectively connected to the vacuum source or the atmosphere. A valve housing is attached to the movable wall, and an input member is disposed inside the valve housing for advancing and retreating movement with respect to the valve housing, with the input member being movable by operation of a brake operation. A valve mechanism is disposed inside the valve housing and has a vacuum valve for connecting the rear chamber with the front chamber, corresponding to movement of the input member, and an atmospheric air valve for connecting the rear chamber with the atmosphere, corresponding to movement of the input member. An output member outputs pressure from the pressure generator generated in conjunction with movement of the movable wall, and an auxiliary movable wall is disposed inside the front chamber and is engageable with the output member for advancing and retreating movement. An isolating member is connected with the auxiliary movable wall to form an auxiliary variable pressure chamber between the auxiliary movable wall and the movable wall, and a switching device selectively connects the auxiliary variable pressure chamber with the vacuum source or the atmosphere.
However, in this pressure generator, an auxiliary movable wall and an isolating wall are necessary for forming the auxiliary variable pressure chamber. Consequently, the pressure generator has a large number of parts and suffers from having poor assembly efficiency and high cost.
In light of the foregoing, a need exists for a pressure generator that is not susceptible to the same disadvantages and drawbacks as other known pressure generators such as those described above.
It would thus be desirable to provide a pressure generator having a relatively simple construction and improved assembly efficiency, yet which is not as expensive to produce.
SUMMARY OF THE INVENTION
The present invention provides a pressure generator that includes a housing in which is formed at least one pressure chamber, and a power piston disposed inside the pressure chamber for advancing and retreating movement with respect to the housing. The power piston includes a movable wall and which divides the pressure chamber into a front chamber connected to a vacuum source and a rear chamber selectively connected to the vacuum source or the atmosphere. A valve housing is attached to the movable wall, and an input member is disposed inside the valve housing for advancing and retreating movement with respect to the valve housing upon brake operation. A valve mechanism is disposed inside the valve housing and has a vacuum valve for connecting the rear chamber with the front chamber corresponding to movement of the input member and an atmospheric air valve for connecting the rear chamber with the atmosphere corresponding to movement of the input member. An output member outputs pressure from the pressure generator in conjunction with movement of the movable wall, and an auxiliary movable wall is disposed inside the front chamber for advancing and retreating movement. An auxiliary variable pressure chamber is contained inside the front chamber by the auxiliary movable wall and the movable wall, and a switching device selectively connects the auxiliary variable pressure chamber with the vacuum source or the atmosphere. A cylinder body having a cylinder bore is mounted in the front part of the housing, and a piston adapted to advance and retreat is located in the cylinder bore to form in front of the piston a pressure chamber. The piston is engageable with the output member and moves inside the cylinder bore along with movement of the auxiliary movable wall.
According to another aspect of the invention, a pressure generator includes a housing in which is formed at least one pressure chamber, a partition wall member disposed inside the pressure chamber and dividing the inside of the pressure chamber into a front side pressure chamber and a rear side pressure chamber, and a power piston having a front side movable wall disposed inside the front side pressure chamber for advancing and retreating movement with respect to the housing. The front side movable wall divides the front side pressure chamber into a first front chamber connected to the vacuum source and a first rear chamber selectively connected to the vacuum source or to the atmosphere. The power piston also includes a rear side movable wall disposed inside the rear side pressure chamber for advancing and retreating movement with respect to the housing. The rear side movable wall divides the rear side pressure chamber into a second front chamber connected to the vacuum source and a second rear chamber selectively connected to the vacuum source or to the atmosphere. The power piston further includes a valve housing attached to both of the movable walls. An input member is disposed inside the valve housing for advancing and retreating movement with respect to the valve housing and is movable by brake operation. A valve mechanism is disposed inside the valve housing and has a vacuum valve for connecting both of the rear chambers with both of the front chambers in correspondence with movement of the input member and an atmospheric air valve for connecting both of the rear chambers with the atmosphere in correspondence with movement of the input member. An output member outputs outside the pressure generator a thrust force of the valve housing accompanying movement of the two moving walls, and an auxiliary moving wall is disposed inside the first front chamber for advancing and retreating movement. An auxiliary variable pressure chamber is bounded inside the first front chamber by the auxiliary movable wall and the first movable wall. A switching device selectively connects the auxiliary variable pressure chamber with the vacuum source or the atmosphere. A cylinder body having a cylinder bore is mounted in a front part of the housing and a piston is locates in the cylinder bore. The piston is adapted to move in an advancing and retreating fashion and forms in front of the piston a pressure chamber. The piston is engageable with the output member and is moved inside the cylinder bore along with movement of the auxiliary movable wall.
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patent: 5787789 (1998-08-01), Suzuki
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patent: 5890775 (1999-04-01), Tsubouchi et al.
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patent: 6065388 (2000-05-01), Tsubouchi et al.
patent: 2-274649 (1990-11-01), None
patent: 9-123896 (1997-05-01), None
Aisin Seiki Kabushiki Kaisha
Burns Doane , Swecker, Mathis LLP
Schwartz Christopher P.
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