The present invention relates to a hydraulic actuator for a vehicle. More particularly, the present invention relates to a reversible hydraulic pump assembly for torque control in hydraulic vehicle systems.
Hydraulic actuators are normally used in vehicles for actuating various types of systems, such as AWD couplings and gear shifts.
In EP2310709 an electrical axial piston pump is described, having a centrifugal valve device that allows it to control the pressure output. This device can control one system, for example an AWD coupling, with lower hysteresis than if the same coupling should be controlled with proportional solenoid valves. Further, the centrifugal valve device does not require a micro filter. For applications involving two couplings or one coupling and one gear shift the described axial piston pump must be provided with additional electrical shift valves.
In order to reduce complexity, weight and costs it would be desired to provide an improved hydraulic pump assembly for use in vehicle applications, and preferably such applications having two couplings or one coupling and one gear shift.
An object of the present invention is to provide a hydraulic pump assembly in combination with a bidirectional control.
According to various aspects of the present invention, a hydraulic pump assembly is provided in accordance with the features set forth in the independent claim. Preferred embodiments are defined by the appended dependent claims.
Embodiments of the invention will be described in the following; reference being made it the appended drawings which illustrate non-limiting examples of how the inventive concept can be reduced into practice.
By adding two input check valves 110, 112 and two output check valves 114, 116 the direction of the flow is dependant on the motor direction of rotation. As can be seen in
When the motor 102 is rotating in a first direction, hydraulic fluid will be drawn from the reservoir 122 via the first input check valve 110, through the pump 104, to the second port 120. The first output check valve 114 is in fluid connection with the overflow valve 108.
When the motor 102 is rotating in the opposite direction, hydraulic fluid will be drawn from the reservoir 122 via the second input check valve 112, through the pump 104, to the first port 118. The second output check valve 116 is in fluid connection with the overflow valve 108.
A third port 124 may also be provided. The third port 124 could be used in combination with one of the first port 118 or second port 120 or together with both the first and second ports 118, 120. Pressure from the third port 124 will be independent of direction of rotation of the motor 102.
Now turning to
Action is preferably also taken to make the first and second ports 118, 120 more symmetrical in a washer plate of the pump assembly 100.
An alternative use could be to use the third port 124 in combination with one of the first or second port 118, 120, or together with both the first and second port 118, 120. Pressure from the third port 124 will be independent of direction of rotation.
It will be appreciated that the embodiments described in the foregoing may be combined without departing from the scope as defined by the appended patent claims.
Although the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the invention is limited only by the accompanying claims and, other embodiments than the specific above are equally possible within the scope of these appended claims.
Number | Date | Country | Kind |
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1450111-8 | Jan 2014 | SE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2015/052024 | 1/31/2015 | WO | 00 |