The present invention relates to a hydraulic valve incorporating a sensor assembly for sensing a position of the valve spool.
Mobile equipment may include a valve assembly for controlling one or more functions. The valve assembly may include a single valve or may include a number of valves. A valve assembly with multiple valves is often referred to as a sectional valve. The valve assembly controls the fluid supplied to and received from one or more actuators used for performing defined functions. For example, a valve assembly may be used for controlling the movement of a bucket of a wheel loader. Valve assemblies may be manually actuatable or electrically actuatable, such as with a solenoid.
Commonly, valve assemblies include spool valves. A spool valve has a spool that is moveable relative to a valve body for controlling the flow of fluid through the valve. In certain applications, it is desirable to know a position of the spool relative to the valve body.
U.S. Pat. No. 6,152,172 discloses a spool position sensor for a hydraulic control valve. The spool position sensor of this patent includes a coupling that is fixed to an end of the spool of the valve. A magnet is fixed within the coupling and moves with movement of the spool past a Hall effect sensor fixed relative to the valve body for providing an indication of the position of the spool.
The present invention relates to a hydraulic valve. The hydraulic valve comprises a valve body, a valve spool that is movable relative to the valve body for controlling fluid flow through the valve body, and a spool return assembly for biasing the valve spool into a centered position relative to the valve body. The hydraulic valve further includes a position sensor assembly having a sensor portion affixed relative to the valve body and a movable portion that is movable relative to the sensor portion in response to movement of the valve spool. The sensor portion is responsive to a position of the movable portion for outputting a signal indicative of the position of the valve spool relative to the valve body. The movable portion of the position sensor assembly is biased into engagement with one of the spool and the spool return assembly.
The foregoing and other features of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which:
The valve 10 illustrated in
The spool 28 extends through the spool bore 44 of the valve body 26 and is moveable relative to the valve body for controlling actuation of actuator 20. The spool 28 illustrated in
When the spool 28 is actuated rightward relative to the valve body 26 into the position shown in
Similarly, when the spool 28 is actuated leftward into the position shown in
A coupling 76 is attached to one end of the spool 28 illustrated in
A spool return assembly 80 is affixed to the end of the spool 28 opposite the coupling 76. The spool return assembly 80 includes first and second spring collars 82 and 84, respectively, a helical spring 86, and a spool screw 88. The helical spring 86 is interposed between the first and second spring collars 82 and 84. The spool screw 88 extends through the first and second spring collars 82 and 84 and the center of the helical spring 86 to affix the spring collars and the spring to the end of the spool 28.
The spool return assembly 80 is located within an enclosure 92 that is affixed to the valve body 26. The spool return assembly 80 tends to bias the spool 28 into the centered position of
A grommet check 98, which may be formed from a nitrile material, extends through a hole in the enclosure and acts as a vent. The grommet check 98 prevents the housing 14 from becoming pressurized if the seals around the spool 28 fail and leak oil into the enclosure 92. The grommet check 98 is designed to open at one psi internal pressure.
The enclosure 92 also includes an extension 100 that includes an elongated cavity 102 and a sensor chamber 104 that is located radially outwardly of the elongated cavity. The elongated cavity terminates at an end wall 108 of the extension 100. A cover 106 is attachable to the enclosure 92 for closing the sensor chamber 104.
The valve 10 also includes a position sensor assembly 110. The position sensor assembly 110 includes a sensor portion 112 and a movable portion 114. In the illustrated embodiment, the sensor portion 112 is fixed relative to the valve body 26. As best shown in
With reference to
The movable portion 114 also includes a permanent magnet 134. The permanent magnet 134 is sized to be easily dropped into the cavity 130 of the glide member 120. A spring 136 extends into cavity 130 to bias magnet 134 against the partition portion 126 of the glide portion. A spring 138 extends into cavity 128 and seats against the partition portion 126. Spring 136 has a lower spring constant than spring 138 so that spring 136 compresses prior to spring 138. Spring 136 is non-ferrous. In one embodiment of the invention, spring 136 is formed from beryllium copper. Spring 138 is formed from 302 stainless steel for corrosion resistance.
The movable portion 114 is received in the elongated cavity 102 of the extension 100 of the enclosure 92. When received in the elongated cavity 102, spring 136 abuts against the end wall 108 of the extension 100. When the enclosure 92 is affixed relative to the valve body 26 in the position illustrated in
When the spool 28 of the valve 10 is moved rightward from the position illustrated in
When the spool 28 of the valve 10 is moved leftward from the position illustrated in
The position sensor assembly 110 is advantage over other known position sensors for many reasons. The position sensor assembly 110 requires no modification of the spool return mechanism 80 as no portion of the position sensor assembly 110 is affixed to the spool 28 or to the spool return mechanism. Since no modifications to the spool return mechanism 80 are required, the position sensor assembly 110 may be added to valves in the field without the need for field modifications of the valves. Such modification or retrofitting of field units may be done by simply removing the existing end cap of the valve and replacing it with the position sensor assembly 110.
Additionally, since the position sensor assembly 110 does not require any physical attachment to the valve spool 28 or spool return assembly 80, the position sensor assembly 110 does not require any special alignment to the valve spool 28 or valve housing 26. For example, prior art position sensors having a portion affixed to the valve spool require that the affixed portion moves along the axis of the valve spool. As a result, the prior art position sensors must be physically aligned relative to the valve body to allow this movement along the axis of the valve spool. The position sensor assembly 110 of the present invention does not require such alignment. As illustrated in
From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.
This application claims priority of U.S. Provisional Application No. 60/891,795 filed Feb. 27, 2007 and entitled “Hydraulic Control Valve Spool Position Sensor Assembly”, which is hereby incorporated herein by reference
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5926018 | Jones | Jul 1999 | A |
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6789570 | Beyrak et al. | Sep 2004 | B2 |
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Number | Date | Country |
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20070076750 | Jul 2007 | WO |
Number | Date | Country | |
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20080202608 A1 | Aug 2008 | US |
Number | Date | Country | |
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60891795 | Feb 2007 | US |