The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2002-125371, filed on Apr. 26, 2002. The contents of that application are incorporated herein by reference in their entirety.
1. Field of the Invention
The invention relates to a pump apparatus for various fluid devices, for example a fluid pressure power steering apparatus. Especially, the invention relates to a bypass path, formed between a flow control valve and a suction portion of the pump apparatus, and a dividing wall formed opposite to an end portion of the bypass path to suck operation fluid.
2. Description of the Related Art
It is typically known a vane pump apparatus for a fluid pump apparatus using for a fluid pressure power steering apparatus. A vane pump apparatus is, for example, disclosed in the U.S. Pat. No. 6,299,418. The typically known vane pump apparatus has a flow control valve 10 to return as excess fluid to the pump a part of discharged fluid from a pump unit discharging operation fluid to the power steering apparatus in order to send constant volume of operation fluid to the power steering apparatus. Such flow control valve is disclosed in Japanese Utility Model laid-open publication No.05-096483 and said U.S. Pat. No. 6,299,418.
The typically known vane pump apparatus is shown in
In the typically known vane pump apparatus, as shown in
In view of the previously mentioned circumstances, it is an object of the present invention to provide a pump apparatus reducing a vibration and a noise in an operation of the pump apparatus.
It is further object of the present invention to provide a vane pump apparatus reducing a manufacturing cost by using common parts.
In order to achieve the above and other objects, the present invention provides a pump apparatus comprising at least a flow control valve, a bypass path, a dividing wall and a pair of suction paths. The flow control valve discharges constant volume of operation fluid to a fluid apparatus by returning a part of discharged fluid from the pump apparatus as excess fluid to a suction portion of the pump apparatus, and the flow control valve has a bypass hole discharging said excess fluid in a “deviated slanting way”. The “deviated slantine way” is defined as the direction of the flow of excess fluid through the bypass hole, which is oblique to the length, or central axis, of the bypass hole such that the discharged fluid is discharged to an incident side of the bypass passage. The dividing wall formed opposite to the bypass path distributes operation fluid to said pair of suction paths. An end portion of the bypass path defines a pair of opening portions of the suction paths at the dividing wall. A cross sectional area of one of said opening portions on the incident side of the bypass path is smaller than a cross sectional area of the other of said opening portions on an opposite side, the incident side of the bypass path.
The pump apparatus can make equivalent volume of the sucked operation fluid distributed at left and right suction path. The area formed in said one of opening portions on the incident side of the bypass pass is smaller than the area of the other of said opening portions on an opposite side, the incident side of the bypass path, such that distributed volume of operation fluid in the bypass path is intended to be divided more to the area with a larger area because of an area difference so that each volume a time of said operation fluid flowing in each of left and right suction paths is substantially equivalent in order to eliminate insufficiency of flowing volume of operation fluid to the other suction path based on the discharged slanting way. Therefore the invention improves to reduce vibration and noise at the operation of this pump apparatus.
The other aspect of the invention is that a first width of a cross section of said bypass path measured from the side of the bypass passage incident to the discharge of said excess fluid and the opposite side of the bypass path is larger than a second width of said cross section of said bypass path measured in a direction transverse to said first width; and a length of a first side wall of said bypass path which is incident to the discharge of said excess fluid is longer than a second length of a side wall of said bypass path not incident to the discharge of said excess fluid. Therefore, said two areas are adjusted by changing the length of the side walls to keep the equivalent volume of said operation fluid when the direction of deviated slanting way of discharged excess fluid is changed. Thereby, it is easy to keep the equivalency to make it possible be a common use and a common part of the pump apparatus in order to reduce a manufacturing cost.
Various other objects, features and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description of the preferred embodiments when considered in connection with the accompanying drawings, in which:
A preferred embodiment of a pump apparatus according to the aforementioned invention will be described referring to
The flow control valve 2 consists of a valve housing 29 being a part of the housing 99 of the vane pump unit 1. The flow control valve 2 further consists of a throttle 24 to control the volume of the operation fluid to said fluid apparatus through an output port 25 and a spool 22 operated by a differential pressure between upper and downward stream of the throttle 24. There is a bypass hole 21 in the valve housing 29 between the throttle 24 and a head of the spool 22 to return said excess fluid to the vane pump unit 1. A bypass path 11 is formed in the housing 99 to be connected with the bypass hole 21 to flow said excess fluid to suction paths 19, 19′, as shown in
Referring to
As shown in
An operation of the preferred embodiment of the invention is now described hereinafter.
When the vane pump unit 1 operates to discharge operation fluid, the discharged fluid is introduced to the throttle 24 through the introducing path 12 and the introducing port 122. A part of discharged fluid is discharged as excess fluid through the clearance between the head of the spool 22 and the bypass hole 21. Assisted by being discharged as excess fluid, said operation fluid is sucked from the reservoir 5 to the bypass path 11 through opening portion 155. A discharged direction of operation fluid including excess fluid and sucked fluid is a direction of the deviated slanting way as shown by an arrow in FIG. 3. Therefore, larger volume of said operation fluid is intended to be flown with assisted power in the direction of the deviated slanting way at the end portion 119, 119′. However in the embodiment of the invention with the area D formed in said one of opening portions in the side of the deviated slanting way and with the area D′ opposite to the area D, the area D is smaller than the area D′. Therefore, said flowing volume of operation fluid in the bypass path 11 is intended to be divided more to the area D′ with weaker flowing of operation fluid and with a larger area because of an area difference so that each volume a time of said operation fluid flowing in each of left and right suction paths 19, 19′ is substantially equivalent in order to eliminate insufficiency of flowing volume of operation fluid to the right suction path 19′ with the weaker flowing of operation fluid based on the discharged slanting way. As a result, said volume of the operation fluid at the suction port 199, 199′ is substantially equivalent. Therefore the embodiment of the invention improves to reduce sound pressure at the operation of this pump apparatus.
The areas D, D′ are adjusted by changing the length of the side walls 111, 111′ to make the equivalency of said operation fluid. When a position of the output port 25 is changed by a specification change to alter the direction of discharged excess fluid, it can be adjusted corresponding to the change by altering the length of the side walls 111, 111′, that is to say only change of a design of the housing 99. Therefore, there is no need to change a design of the cover 98 equipped with the suction path 19, 19′ to make it possible be a common use and a common part in order to reduce a manufacturing cost.
In the pump apparatus according to the present invention, because the area formed in one of opening portions of the pair of suction paths in the incident side of the bypass path with stronger flowing of operation fluid is smaller than the area of the other of said opening portions in the opposite side of the bypass path, distributed volume a time of operation fluid in the bypass path is substantially equivalent to eliminate insufficiency of flowing volume of operation fluid to the other suction path based on the discharged slanting way. Therefore the invention can make the equivalent delivery to perform a smooth operation of the pump apparatus by reducing vibration and noise.
Further in the pump apparatus according to the present invention, a first width AA of a cross section of the bypass path, measured from the side of the bypass passage incident to the discharge of said excess fluid and the opposite side of the bypass path, is larger than a second width BB of the cross section of said bypass path, measured in a direction transverse to said first width. A length of a first side wall of said bypass path which is incident to the discharge of said excess fluid is longer than a second length of a side wall of said bypass path not incident to the discharge of said excess fluid. Therefore, said two areas are adjusted by changing the length of the side walls to keep the equivalent volume of said operation fluid when the direction of deviated slanting way of discharged excess fluid is changed. Thereby, it is easy to keep the equivalency. And the cover with the dividing wall and the opening portions of suction paths is common in changing of the specification of the flow control valve to reduce a manufacturing cost.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.
Number | Date | Country | Kind |
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2002-125371 | Apr 2002 | JP | national |
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0 505 033 | Sep 1992 | EP |
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Number | Date | Country | |
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20030202888 A1 | Oct 2003 | US |