Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-04-26
2001-08-07
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S087000, C303SDIG001
Reexamination Certificate
active
06270170
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic actuator preferably used for controlling braking fluid of an anti-lock braking system installed in an automotive vehicle.
In the anti-lock braking system, the hydraulic actuator increases or decreases the hydraulic pressure of each wheel cylinder to prevent the wheel from locking during the braking operation.
FIG. 6
shows a conventional hydraulic actuator disclosed in the U.S. Pat. No. 5,244,262. This actuator comprises two reservoirs
101
and
102
each storing the braking fluid released from a wheel cylinder. Four pressurizing control valves
103
,
106
,
107
and
110
are used for controlling the connection and disconnection between the master cylinder and wheel cylinders. Four depressurizing control valves
104
,
105
,
108
and
109
are used for controlling the connection and disconnection between the wheel cylinder and the reservoirs
101
and
102
. Two plunger pumps
111
and
112
supply the braking fluid to the master cylinder from the reservoirs
101
and
102
, respectively. Two dampers
113
and
114
suppress the pulsation flow of the braking fluid supplied from the pumps
113
and
114
.
The reservoirs
101
and
102
, the pressurizing control valves
103
,
106
,
107
and
110
, the depressurizing control valves
104
,
105
,
108
and
109
, the plunger pumps
111
and
112
, and the dampers
113
and
114
are integrally assembled in a housing
115
.
According to this conventional hydraulic actuator, all of the pressurizing control valves
103
,
106
,
107
and
110
and all of the depressurizing control valves
104
,
105
,
108
and
109
are disposed at a same side with respect to an axial line
116
of the plungers
111
and
112
. The reservoirs
101
and
102
and the dampers
113
and
114
are disposed along a line at the other side with respect to the axial line
116
. This arrangement makes it possible to effectively utilize an available space to a certain degree.
However, a width size of the housing
115
is substantially restricted by the four sequential elements, i.e., reservoirs
101
and
102
and dampers
113
and
114
, arrayed in a line.
FIGS. 7A and 7B
show an improved hydraulic actuator proposed in the U.S. Pat. No. 5,658,056. According to this conventional hydraulic actuator, two reservoirs
121
and
122
are disposed in parallel with two dampers
123
and
124
so that their axes are positioned at four corners of a rectangle. This arrangement is advantageous in reducing the width size of an actuator housing
125
.
SUMMARY OF THE INVENTION
An object of the present invention is to further improve the arrangement of the hydraulic actuator so as to optimize the volumetric efficiency of the actuator housing.
In order to accomplish this and other related objects, one aspect of the present invention provides a hydraulic actuator used in a hydraulically operable system, such as an anti-lock braking system, which is preferably installed in an automotive vehicle. The hydraulic actuator of the present invention comprises a housing. A motor is installed on a first surface of the housing and has a drive shaft normal to the first surface. At least one pump is installed in the housing and driven by the motor for introducing and discharging operation fluid. Two reservoirs are provided in the housing for storing the operation fluid released from a hydraulically operable element, such as a wheel cylinder. Each reservoir has an opening at a second surface of the housing and an axis normal to the second surface. The second surface is different from the first surface on which the motor is disposed. Two dampers are provided in the housing for suppressing pulsation flow of the operation fluid discharged from the pump. Each damper has an opening at a third surface of the housing and an axis normal to the third surface. The third surface is different from the second surface. The third surface is spaced from and faces to the second surface so that the drive shaft of the motor is interposed between the second surface and the third surface.
According to this arrangement, the two dampers are located in an opposed relationship with the two reservoirs with the drive shaft interposed between the dampers and the reservoirs. With this arrangement, it is not necessary to array the reservoirs and the dampers in a line. Thus, it becomes possible to downsize the hydraulic actuator.
Another aspect of the present invention provides a hydraulic actuator comprising a hexahedral housing including first to third surfaces. Each of the two reservoirs has an opening at the second surface of the hexahedral housing and an axis normal to the second surface. The second surface is located next to the first surface. Each of the two dampers has an opening at the third surface of the hexahedral housing and an axis normal to the third surface. The third surface is in an opposed relationship with the second surface.
Another aspect of the present invention provides a hydraulic actuator comprising a housing with first to third surfaces, wherein the second surface with the openings for the two reservoirs is parallel to the third surface with the openings for the two dampers.
According to preferred embodiments, one of the two reservoirs is overlapped with one of the two dampers and the other of the two reservoirs is overlapped with the other of the two dampers when the two reservoirs and the two dampers are seen from a direction normal to the second surface.
Preferably, a distance between axes of the reservoir and the damper which are overlapped each other is shorter than a smaller one of a reservoir diameter and a damper diameter.
Preferably, the axis of the reservoir coincides with the axis of the damper when they are overlapped each other in the direction normal to the second surface.
According to preferred embodiments of the present invention, the housing has a fourth surface facing to the first surface on which the motor is disposed to drive the pump. A plurality of control valves are provided at the fourth surface for controlling the flow of the operation fluid.
When a total of eight control valves are provided, these control valves are arranged in a 2×4 pattern along two lines parallel to the third surface. All of the eight control valves are located at the same side adjacent to the dampers with respect to the drive shaft.
Another aspect of the present invention provides a hydraulic actuator comprising a housing with first to fourth surfaces. The two reservoirs are provided in the housing. Each reservoir has an opening at the second surface of and an axis normal to the second surface. The second surface is different from the first surface on which the motor is disposed for driving the pump. The two dampers are provided in the housing. Each damper has an opening at a third surface of the housing and an axis normal to the third surface. The third surface is different from the second surface. A plurality of control valves are provided at the fourth facing to the first surface. The third surface faces to the second surface so that the drive shaft of the motor is interposed between the two reservoirs and the two dampers. The plurality of control valves are located at the same side adjacent to the dampers with respect to the drive shaft and the pump.
According to the preferred embodiments of the present invention, each damper has a damper chamber recessed from the third surface of the housing and extending in the housing in a direction normal to the third surface. Each reservoir has a reservoir chamber recessed from the second surface of the housing and extending in the housing in a direction normal to the second surface. An axial length of the damper chamber is longer than an axial length of the reservoir chamber.
Another aspect of the present invention provides a hydraulic actuator comprising a hexahedral housing. The motor is installed on a surface of the housing for driving the piston pump. The piston pump reciprocates to perform a predetermined pumping operation. Each of the two reservoirs is disposed i
Isogai Kimiyoshi
Koyama Fumitoshi
Denso Corporation
Oberleitner Robert J.
Pillsbury & Winthrop LLP
Siconolfi Robert A.
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