Motors: expansible chamber type – Working member position feedback to motive fluid control – Plural input signal means for single motor valve
Reexamination Certificate
1999-03-22
2001-01-09
Lopez, F. Daniel (Department: 3745)
Motors: expansible chamber type
Working member position feedback to motive fluid control
Plural input signal means for single motor valve
Reexamination Certificate
active
06170382
ABSTRACT:
This application corresponds to and claims priority under 35 U.S.C. § 119 with respect to Japanese Application No. 10(1998)-71722 filed on Mar. 20, 1998, Japanese Application No. 10(1998)-71725 filed on Mar. 20, 1998 and Japanese Application No. 10(1998)-71726 filed on Mar. 20, 1998, the entire content of each of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention generally relates to a vehicle brake apparatus component. More particularly, the present invention pertains to a negative-pressure booster for an automobile.
BACKGROUND OF THE INVENTION
A known type of negative-pressure booster is disclosed in SAE 950760 and includes a housing in which is formed at least one pressure space and a movable wall provided in the housing for advancing and retreating movement with respect to the housing. The movable wall divides the pressure space inside the housing into a front chamber that is adapted to communicate with a negative-pressure source and a rear chamber that is adapted to selectively communicate with the front chamber or atmosphere. A power piston is connected to the movable wall, and an input member is provided inside the power piston for advancing and retreating movement with respect to the power piston. An air valve seat is provided in the power piston for advancing and retreating movement together with the input member. A negative-pressure valve seat is provided in the power piston. A control valve has an air sealing portion capable of contacting and separating from the air valve seat for isolating the rear chamber from the atmosphere by coming into contact with the air valve seat and for causing the rear chamber to communicate with the atmosphere as a result of being separated from the air valve seat. A negative-pressure sealing portion is capable of contacting and separating from the negative-pressure valve seat for isolating the rear chamber from the front chamber by coming into contact with the negative-pressure valve seat and for causing the rear chamber to communicate with the front chamber by being separated from the negative-pressure valve seat. An output member outputs outside the booster an advancing force of the power piston that is generated in association with movement of the movable wall and a reaction member transmits the advancing force of the power piston and an input that is applied to the input member to the output member. The reaction member also applies a reaction force corresponding in magnitude to the output of the output member to the input member to cause the input member to retreat. An actuator causes the rear chamber to communicate with the atmosphere by separating the air sealing portion from the air valve seat. The known negative-pressure booster is further provided with a detecting device for detecting the volume of separation between the air valve seat and the air sealing portion, and the actuator is caused to operate in accordance with the detection result of the detecting device.
However, the presence of the detecting device which detects the volume of separation between the air valve seat and the air sealing portion necessarily increases the cost and complexity of the negative-pressure booster.
In light of the foregoing, a need exists for a negative-pressure booster having a relatively simple construction while at the same time being relatively low in cost.
SUMMARY OF THE INVENTION
In light of the foregoing, the present invention provides a negative-pressure booster that includes a housing in which is formed at least one pressure space, a movable wall provided in the housing so as to be able to advance and retreat with respect to the housing, and dividing the pressure space into a front chamber adapted to communicate with a negative-pressure source and a rear chamber adapted to be selectively communicated with the front chamber or the atmosphere, a power piston connected to the movable wall, an input member provided inside the power piston for advancing and retreating with respect to the power piston, and a valve mechanism for allowing the rear chamber to communicate with the front chamber or the atmosphere in accordance with the movement of the input member. An output member outputs outside the booster an advancing force of the power piston that is generated in association with movement of the movable wall, and a reaction force member transmits the advancing force of the power piston and the input applied to the input member to the output member while also applying a reaction force corresponding in magnitude to the output of the output member to the input member to cause the input member to retreat. An actuator allows the rear chamber to communicate with the atmosphere by causing the valve mechanism to operate, and an engagement member is capable of engaging the input member for allowing retreating movement of the input member by being deformed elastically when the input member receives the reaction force from the reaction force member in association with operation of the actuator. The retreat of the input member receiving the reaction force from the reaction force member in association with the operation of the actuator causes the valve mechanism to operate to thereby allow the rear chamber to be isolated from the atmosphere. The adjustment of the driving force of the actuator makes the output of the output member adjustable.
In the negative-pressure booster of the present invention, because the adjustment of the driving force of the actuator makes the output of the output member adjustable, the output can be produced so as to be more suitable for each situation. Therefore, unlike other known negative-pressure boosters, no detecting means for detecting the volume of the separation between the air valve seat and the air sealing portion is needed. This enables a relatively simple and cost effective construction of the booster. That is, a negative-pressure booster can be produced that is simpler in construction and lower is cost.
It is preferable that the valve mechanism include an air valve seat that can advance and retreat together with the input member, a negative-pressure valve seat provided in the power piston, an air sealing portion that is able to contact and be separated from the air valve seat for isolating the rear chamber from the atmosphere when it comes into contact with the air valve seat and causes the rear chamber to communicate with the air when it is separated from the air valve seat, and a negative-pressure sealing portion that can contact and be separated from the negative-pressure valve seat for isolating the rear chamber from the front chamber when it comes into contact with the negative-pressure valve seat and for causing the rear chamber to communicate with the front chamber when it is separated from the negative-pressure valve seat. The actuator allows the rear chamber to communicate with the atmosphere by separating the air sealing portion from the air valve seat, and the retreat of the input member receiving the reaction force from the reaction force member in association with the operation of the actuator causes the air sealing portion to come into contact with the air valve seat to thereby allow the rear chamber to be isolated from the atmosphere. Because the actuator allows the rear chamber to communicate with the atmosphere by separating the air sealing portion from the air valve seat, an improved valve mechanism is achieved.
The air valve seat is preferably provided in the input member and advances and retreats together with the input member. Also, the booster further includes a control valve having the air sealing portion and the negative-pressure sealing portion formed in an integral manner, and a valve seat member that is provided so as to be able to advance and retreat with respect to the power piston, while also advancing and retreating independently of the movement of the input member, and isolating the rear chamber from the front chamber by coming into contact with the negative sealing portion of the control valve. The actuator allow the rear chamber to communicate
Miwa Akihiko
Tsubouchi Kaoru
Aisin Seiki Kabushiki Kaisha
Burns Doane , Swecker, Mathis LLP
Lopez F. Daniel
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