JP2013032846A - Spool valve with reduced cavitation damage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spool valve with reduced cavitation damage.SOLUTION: The spool valve 10 includes a valve spool 22 having a circumferential-shaped control edge. The spool valve further includes a means 50 for applying an intermittently or continuously rotation to the valve spool 22. A part of the control edge, which is subjected to interaction with a port 32 for controlling a fluid flow, is uniformly distributed in a circumferential region of the control edge.

Description

  The present invention relates to a spool valve, and more particularly to a spool valve having a control edge portion that can be used as a control valve or a pilot valve.

Background of the Invention

  Control valves are well known, and specifically, directional control valves having a spool in the longitudinal direction are widely used. Such valves have multiple connection ports for pumps, tanks, and consumer equipment. The plurality of ports are arranged to be offset laterally or radially with respect to the axis of the spool. The control edge of the spool land (shaft clearance) interacts with the edge of the port to control fluid flow. In many cases, these control valves provide a relatively narrow flow path between the edge of the port and the control edge of the land, near its (closed) center position, for the majority of its operating period. Since it is maintained, a very large flow rate change and a rapid pressure drop occur, and cavitation occurs. The control edge is frequently damaged by this cavitation. This is due to cavitation erosion, which causes the valve to fail early. Damage occurs in the spool portion directly adjacent to the port opening in the valve housing.

  Against this background, the object of the present invention is to overcome or at least reduce the above-mentioned drawbacks.

  A spool valve comprising a valve spool having a circumferential control edge, provided with means for imparting intermittent or continuous rotation to the valve spool, thereby providing a port for controlling fluid flow This is accomplished by ensuring that the portion of the control edge that is exposed to the interaction is evenly distributed in the circumferential region of the control edge.

  By introducing frequent arbitrary or non-random rotation or continuous rotation of the valve spool, the wear load is distributed in the circumferential area of the spool, thereby extending the overall life of the spool valve. be able to. Uniformly distributing cavitation damage is a level of local cavitation damage compared to conventional structures having valve spools that do not rotate to distribute control edge wear in the circumferential region of the control edge. It means slowing down to reach a level that must not be exceeded for proper operation of the spool valve.

  This rotation can be implemented in several ways:

  The valve spool can be continuously driven by a dedicated electric motor, for example.

  The valve spool can be continuously driven by hydraulic pressure, for example.

  The valve spool is allowed to rotate freely, for example, so that the wings or blades that are processed into the spool itself or attached to the spool generate a rotational force each time the valve is opened or continuously. Also good.

  Preferably, intermittent or continuous rotation of the valve spool causes the circumferential portions of the at least one control edge to interact with the one or more high pressure ports during operation of the spool valve. Be exposed in the same way.

  The rotation imparting means may include a blade or wing connected to the valve spool, and a flowing hydraulic fluid acting on the blade or wing. The vanes or wings may be inseparable from the valve spool and can be driven by the flow to the tank.

  Alternatively, the rotation imparting means may include an impeller coupled to the valve spool and a flow of hydraulic fluid acting on the impeller.

  The valve spool may further include a rotary hydraulic damper for limiting the rotation speed of the valve spool.

  A method for reducing the influence of damage to the control edge caused by cavitation caused by a part of the circumferential area of the circumferential control edge in the spool of the spool valve interacting with the port, Including rotating the valve spool intermittently or continuously so that the position of the circumferential portion that interacts with the port at the control edge constantly changes during operation of the spool valve; This is also achieved by providing a method.

  Further objects, features, advantages and characteristics of the spool valve and method according to the present invention will become apparent from the detailed description.

In the following detailed part of the description, the invention will be described in more detail with reference to the exemplary embodiments shown in the drawings.
2 is a schematic cross-sectional view of a spool valve according to an exemplary embodiment. FIG. FIG. 2 is a detailed view of a valve spool land of the valve shown in FIG. 1. FIG. 2 is a first sectional view of the spool valve of FIG. 1. FIG. 3 is a second sectional view of the spool valve of FIG. 1. 6 is a schematic cross-sectional view of a spool valve according to another exemplary embodiment. FIG. 6 is a schematic cross-sectional view of a spool valve according to yet another exemplary embodiment. FIG. It is sectional drawing of the spool valve of FIG. FIG. 7 is another cross-sectional view of the spool valve of FIG. 6.

Detailed Description of the Preferred Embodiment

  1-4 show a hydraulic spool valve 10 according to an exemplary embodiment. The spool valve 10 is a closed center control valve in the exemplary embodiment.

  Spool valve 20 includes a valve housing 20 having high pressure fluid supply ports 32 and 33, which are configured to receive high pressure fluid from a suitable source (not shown) such as a high pressure pump.

  The valve housing 20 is provided with a hole-like space 24 that extends in the axial direction and accommodates the spool, and the valve spool 22 is disposed in this space.

  The valve spool 22 is mounted such that rotational movement within the bore 24 and axial movement along the longitudinal axis of the bore are possible or permitted. The axial movement of the valve spool 22 is obtained by the action of a solenoid 50 attached to one end of the valve housing 20. An electronic control unit 55 is connected to the solenoid 50. A position sensor for determining the axial position of the valve spool 22 is also provided. The string spring 37 urges the valve spool 22 toward the solenoid 50 side.

  The valve spool 22 is provided with two lands 25 and 26. The land 26 is provided with two control edge portions 23 that interact with the high pressure ports 33, 34 and 35.

  The high pressure ports 34 and 35 are connected to the high pressure port 33 through the channel 31. The control edge portion 23 is provided over the entire circumference of the land 26. However, as can be clearly understood from FIG. 3, only a part of the circumferential area of the control edge portion 23 interacts with the high-pressure ports 33, 34, and 35 at a certain moment. In this embodiment, since there are three high-pressure ports that interact with the control edge 23 of the land 26, the circumferential portion of the control edge 23 that interacts with the port at a certain moment is relatively wide. However, in another embodiment, one control edge has only one high pressure port (not two or three as in FIG. 3), and the portion of the control edge that interacts with the high pressure port is also one. There are only places. In such an embodiment, only a small portion of the circumferential area of the control edge 23 interacts with the high pressure port at any given moment. Such an embodiment has the advantage that a small flow rate can be controlled more precisely because the flow passage area can be reduced even if the valve spool opening stroke is the same.

  The land 25 is provided with a control edge portion just like the land 26, and the control edge portion of the land 25 has three high-pressure ports (ports 32 as well as the land 26 interacts with three high-pressure ports). And the other two ports not shown).

  Port 28 is connected to a consumer and ports 39 and 30 are connected to a tank.

  The impeller 40 is attached between the land 25 and the land 26 in the valve spool 22. The impeller is driven by the fluid flowing to the port 28, that is, the impeller is driven by the flow to the consumer device, and the valve shaft 22 rotates. Since the valve shaft rotates only when the spool valve 20 is opened, the rotation of the shaft is intermittent.

  Due to the interaction between the pressure ports 32, 33, 34, and 35 and the control edge portion 23, cavitation damage may occur in the control edge portion 23 and a region close to the control edge portion 23.

  During operation, the position of the valve spool 22 is controlled by the solenoid 50. When the solenoid 50 is activated to push out the valve spool 22 (to the left in the figure), the pressure port 33 is connected to the port 30 and the pressure port 32 is connected to the port 28. When the solenoid 50 is actuated to pull the valve spool 22 in the right direction in the figure, the pressure port 33 is connected to the port 28 and the pressure port 32 is connected to the port 29. Various types of consumer equipment could be connected to ports 28, 29, 30. The spool valve 10 can be used as a pilot valve for controlling a larger hydraulic (servo) valve. This kind of movement of the valve spool 22 is kept around its center position for most of the time, and sometimes opens greatly. Thus, the spool valve 10 controls a small flow rate for most of the time in this type of operation.

  The rotation of the valve spool 22 exposes each circumferential portion of the control edge 23 to the same interaction with the high pressure port. The valve spool must be replaced if the cavitation damage is partially exceeded. However, cavitation damage caused by exposure of the control edge to the interaction with the high pressure port is distributed over the entire range of the control edge so that the cavitation damage of each part of the control edge exceeds the allowable maximum level. Takes time and extends the life of the valve spool.

  FIG. 5 shows another embodiment of the spool valve 10. This embodiment is essentially the same as the embodiment of FIGS. 1-4 except that rotation is imparted by two solenoids 50 and 60 that provide both translational and rotational movement of the valve spool 22. An electronic control unit 65 is connected to the solenoid 60. In this embodiment, one of the solenoids 50 and 60 is provided with an axial position sensor, and may also be provided with a rotational position sensor.

  When the valve spool 22 must move to the solenoid 50 side, the solenoid 50 is actuated to pull the valve spool 22 and simultaneously rotate the valve spool in one direction at a predetermined angle. Simultaneous translation and rotation can be achieved, for example, by using a solenoid with a tilt anchor. When the valve spool 22 moves to the solenoid 60 side, the solenoid 60 is actuated to pull the valve spool 22 and simultaneously rotate the valve spool in the same direction at a predetermined angle. In this manner, the valve spool 22 rotates at a predetermined angle in the same direction by each operation of the solenoids 50 and 60.

  6 to 8 show another embodiment. These embodiments are essentially the same as the embodiment of FIG. 1 except that the valve spool 22 has additional lands 42 and 43 that serve to isolate the impeller 40 from other parts of the hole 22. . The impeller 40 is attached to the valve spool 22 for rotation during operation of the spool valve 10. The impeller 40 is driven by the pressure fluid from the pressure port 38 and the return fluid is discharged to the tank via the port 39. The pressure and flow to the pressure port 38 is limited so that the amount of hydraulic oil used to rotate the shaft is not excessive. Alternatively, the rotation can be driven by the flow to the tank.

  In operation, hydraulic fluid that flows in via pressure port 38 drives impeller 40 and exits impeller chamber via port 39. The flow of hydraulic fluid to the impeller can be continuous or intermittent (depending on the flow of fluid into port 38).

  The lands 44 and 45 serve to isolate the rotary damper from other parts of the hole 22. The rotary damper includes a vane 47 attached to the valve spool 22. Three ribs 46 are provided in the damper chamber 48 in which the blades 47 rotate. The pressure port 41 controls the damper chamber 48 to be filled with hydraulic oil or other suitable damper fluid. The rotation damper suppresses the rotation speed of the spool valve 22 so that the rotation speed of the spool valve 22 does not become so fast as to cause an adverse effect.

  The embodiment of FIG. 1 can also be combined with a rotating damper as needed.

  According to another embodiment, rotation of the valve spool is obtained using an electric motor coupled to the valve spool.

  According to yet another embodiment, the rotation of the valve spool is obtained using any hydraulic motor coupled to the valve spool.

  Other embodiments include vanes that are driven by pressure fluid only when the valve is open.

  The teachings herein have a number of advantages. Different embodiments or implementations may provide one or more of the following advantages. It should be noted that this is not a comprehensive list and that there may be other benefits not described herein.

  One advantage of the teachings herein is that spool valves can be made that have only one port on the circumference of the valve spool. As a result, the flow path area can be reduced even with the same opening stroke, so that a small flow can be controlled well.

  The embodiment described above has been described with reference to a closed center control valve. However, the present invention is applicable to any other type of spool valve that includes a control edge that is exposed to cavitation.

  Features described in the foregoing description may be used in combinations other than those explicitly described.

  The term “comprising”, used in the claims, does not exclude other elements or steps. The singular terms used in the claims do not exclude the plural.

  Any reference signs used in the claims shall not be construed as limiting the scope.

  While the above description has attempted to note features of the teachings herein that are considered to be particularly important, no matter what patentable features or combinations of features are referenced and / or illustrated herein, It is to be understood that the Applicant claims protection regardless of whether or not particular emphasis has been given.

  Although the present invention has been described in detail for purposes of illustration, such details are for that purpose only and those skilled in the art will make changes to the details without departing from the scope of the invention. Please understand that it is possible.

Claims (8)

In a hydraulic system having a hydraulically controlled device, a spool valve (10) for controlling the flow of high pressure hydraulic oil,
The spool valve (10) includes an axially extending hole (24), a valve housing (20) provided with a hole (24) for receiving the valve spool (22), and the spool valve (10). Rotation imparting means (40, 50, 60) for causing intermittent or continuous rotation of the valve spool (22) during operation;
The valve spool (22) is received in the hole (24) such that rotational movement within the hole (24) and axial movement along the longitudinal axis of the hole (24) are possible;
The valve spool (22) is provided with at least two lands (25, 26), and each of the two lands is provided with at least one circumferential control edge (23). ) Is formed by two faces of the land that are perpendicular to the control edge portion,
The hole (24) is provided with at least one high-pressure port (32, 33, 34, 35), each of which is provided with at least one control edge,
The at least one circumferential control edge (23) interacts with the at least one control edge of the high pressure port at a portion along its circumference;
The rotation by the rotation imparting means (40, 50, 60) is such that during the operation of the spool valve (10), individual portions of the peripheral region of the at least one circumferential control edge (23) are at least the By being equally exposed to interaction with one high-pressure port (32, 33, 34, 35), the at least one circumferential control edge (23) is damaged by cavitation. Disperse in the circumferential region of the control edge (23),
Spool valve (10).   The spool valve (10) according to claim 1, wherein the rotation imparting means (40) comprises vanes or wings connected to the valve spool (22).   2. The spool valve according to claim 1, wherein the rotation applying means includes an impeller coupled to the valve spool and a hydraulic fluid that flows to the impeller. 10).   The spool valve (10) according to claim 1 or 3, further comprising a rotary damper (46, 47) for limiting the rotational speed of the valve spool (22).   The spool valve (10) according to claim 1, wherein the rotation imparting means comprises a solenoid (50, 60), an electric motor, or a hydraulic motor.   It further comprises at least one port (32, 33) that interacts with said control edge (23), said at least one port (32, 33) being said circumference of said control edge (23) at any moment. Interacting with only a part of the area, the intermittent or continuous rotation of the valve spool (22) causes the control edge (23) to interact with the at least one port (32, 33). The spool valve (10) according to claim 1, wherein the range to which each part is exposed is distributed over the entire circumference of the control edge (23).   The spool valve (10) according to claim 1, wherein the rotation imparting means is driven by a flow to the tank. In a hydraulic system having a hydraulically controlled device, damage to the spool valve (10) for controlling the flow of high pressure hydraulic oil due to cavitation of the circumferential control edge (23) of the valve spool (22) A way to reduce the impact,
The valve spool (22) is provided with at least two lands (25, 26), and each of the two lands is provided with at least one circumferential control edge (23). ) Is formed by two faces of the land that are perpendicular to the control edge portion,
The hole (24) for receiving the valve spool (22) is provided with at least one high-pressure port (32, 33, 34, 35), each of which is provided with at least one control edge. ,
The at least one circumferential control edge (23) interacts with the at least one control edge of the high pressure port at a portion along its circumference;
The cavitation is caused by the peripheral region of the circumferential control edge (23) interacting with the high pressure port (32, 33, 34, 35),
The method includes intermittently or continuously rotating the valve spool, which causes the position of the portion interacting with the high pressure port in the peripheral region of the circumferential control edge (23). , Constantly changing during the operation of the spool valve (10), whereby the change causes individual portions of the circumferential area of the circumferential control edge (23) to move to the at least one high pressure port (32, 33, 34, 35) is equally exposed to the interaction with the cavitation of the at least one circumferential control edge (23). Distributed in the region,
Method.

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