JP2015001257A - Hydraulic control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wear of a bore inner wall due to eccentric pressure distribution of a hydraulic control valve.SOLUTION: A hydraulic control valve 1 opens/closes a groove 13 formed on an inner wall of a bore 3 in communication with an output port 12 by sliding a second land 21 of a spool 20, so as to control a flow rate of hydraulic oil from an input port 10 to the output port 12. The second land 21 is divided into an adjustment land part 22 for changing an opening amount of the groove 13 in a ring-like notch space r, and a seal land part 24. The adjustment land part 22 has axial length smaller than axial width of the groove 13, and the notch space r forms a relaxation chamber R2 on a rear side of the adjustment land part 22 together with the groove 13. The hydraulic oil directed to the output port 12 through an opening between the groove 13 and the adjustment land part 22 moderately flow by the relaxation chamber R2, and therefore, it is difficult to cause pressure eccentric distribution. A spool is not pressed in a specific direction in the pressure eccentric distribution, and therefore, wear of the inner wall of the bore 3 is prevented.

Description

  The present invention relates to a hydraulic control valve used for control, for example, adjusting an operating pressure to a predetermined constant value.

This type of hydraulic control valve has a structure as shown in FIG. 2, for example.
That is, the hydraulic control valve 1 ′ is configured by forming a bore 3 in the valve body 2 in a cylindrical shape and inserting a spool 4 in the bore 3 so as to be movable in the axial direction.
The spool 4 includes a large-diameter first land 5, a small-diameter portion 6, a large-diameter second land 7 and a spring guide 8 in order from the right end in the drawing. A coil spring 9 disposed along the spring guide 8 pushes the second land 7 and biases the spool 4 in the right direction.
The valve body 2 is provided with an input port 10 and an output port 12 through which hydraulic oil is introduced in association with the small diameter portion 6, and a solenoid that regulates the pilot pressure against the coil spring 9 in the first land 5. A solenoid pressure port 14 for applying pressure is provided.

The input port 10, the output port 12, and the solenoid pressure port 14 open in the same direction in the circumferential direction of the bore 3 and are opened in the axial direction. The bore 3 is connected to the ports 10, 12, and 14 and extends around the entire circumference. Grooves 11, 13, and 15 are formed.
A space in the valve body 2 in which the coil spring 9 is disposed communicates with the atmosphere.
In the figure, reference numeral 7 ′ denotes a minute groove formed on the outer peripheral surface of the second land 7 for holding the spool 4 so as to be centered by the hydraulic oil that has entered between the second land 7 and the inner wall surface of the bore 3. It is.

The operating pressure is adjusted by changing the opening amount of the output port by the second land 7 according to the balance between the urging force by the solenoid pressure and the urging force by the coil spring 9. In the case of adjusting the pressure, the operating pressure of the input port 10 is used as the solenoid pressure.
Normally, the input port 10 opens and communicates with the input working pressure chamber R1 surrounding the small diameter portion 6, while the second land 7 having a step with the small diameter portion 6 closes the groove 13 to close the input working pressure chamber R1. And the output port 12 are blocked. Next, when the solenoid pressure increases to a predetermined pressure or higher, the spool 4 moves to the left in the figure against the biasing force of the coil spring 9, and the gap between the groove 13 and the input working pressure chamber R1 is opened. The input port 10 is in communication. As a result, the hydraulic oil in the input port 10 passes through the input hydraulic pressure chamber R1 and flows out to the output port 12 in accordance with the opening amount of the groove 13, and the hydraulic pressure is reduced. As a result, when the hydraulic pressure decreases, the solenoid pressure also decreases. Thus, the spool 4 is returned by the coil spring 9 and the gap between the input port 10 and the output port 12 is blocked by the second land 7 of the spool 4.
In this way, the pressure of the hydraulic oil in the hydraulic circuit is controlled to a constant predetermined pressure.
A similar hydraulic control valve is also disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-293701.

JP 2004-293701 A

However, it has been discovered that the inner wall surface of the bore 3 is worn during inspection in the process of using the hydraulic control valve 1 ′.
This wear is generated in a portion where the second land 7 that opens and closes the output port 12 is in sliding contact with the output port 12 in the same direction as the output port 12 in the circumferential direction of the bore 3.
In order to investigate this cause, the flow of the hydraulic oil in the bore 3 when the output port 12 is opened was examined. As a result, the flow of the hydraulic oil changed sharply due to the narrow flow path of the hydraulic oil, resulting in high pressure and low pressure regions. Turned out to be.

That is, FIG. 3 is an enlarged velocity diagram showing the flow of hydraulic oil in a cross section perpendicular to the axis of the bore 3 in the groove 13 of the output port 12.
At the beginning of the opening of the output port 12 (groove 13), the hydraulic oil in the input working pressure chamber R1 flows into the groove 13 from the opening between the groove 13 and the second land 7 (see the arrow in FIG. 2). In the separated portion A, the hydraulic oil collides with the bottom wall of the groove 13 due to a dead end and locally becomes high pressure. On the other hand, the hydraulic oil that has entered the part B near the output port 12 is not obstructed and has a high speed, so the pressure is locally low. Then, part of the hydraulic oil that has entered the B portion also flows in the circumferential direction in the groove 13, collides with the flow from the B portion at the C portion that is intermediate between the A portion and the B portion, and becomes high pressure here.
As a result, the spool 4 (second land 7) is pushed to the output port 12 side (downward in the figure) due to the pressure difference between the B part and the A and C parts, so that it is adjacent to the output port 12 in the axial direction of the bore 3. It is determined that the inner wall surface of the part is worn by friction with the second land 7.

  Accordingly, in view of the above-described conventional problems, an object of the present invention is to provide a hydraulic control valve that suppresses pressure uneven distribution around a spool in a groove of an output port and prevents wear of a bore inner wall surface.

Therefore, in the present invention, a spool is disposed in a bore formed in a valve body having a hydraulic oil input port and an output port so as to be movable in the axial direction, and the displacement between the input port and the output port is determined by the axial displacement of the spool. In the hydraulic control valve that controls the flow rate of
The output port is connected to the groove formed on the inner wall surface of the bore,
The spool is provided with a land having a step between adjacent small diameter portions in the axial direction, and the land controls the flow rate by changing the opening amount on one end side in the axial direction of the groove by the displacement in the axial direction. ,
In the land, the adjustment land portion for changing the opening amount is left with an axial length smaller than the axial width of the groove, and a space communicating with the groove is formed by notching an adjacent portion.

  According to the present invention, a large volume chamber composed of a notch space and a groove is formed on the back side of the adjustment land portion, and the hydraulic oil that passes through the opening between the groove and the adjustment land portion toward the output port gently Since it flows, there is no uneven distribution of pressure around the spool, thus preventing wear on the bore inner wall surface.

It is sectional drawing which shows the structure of embodiment. It is sectional drawing which shows a prior art example. It is a velocity diagram which shows the flow of the hydraulic fluid in the groove | channel of the output port of a prior art example.

Embodiments of the present invention will be described below.
FIG. 1 is a cross-sectional view showing an embodiment. Since the hydraulic control valve 1 according to the embodiment differs from the conventional example only in the spool, the other components are denoted by the same reference numerals as those of the conventional example, and redundant description is omitted. FIG. 1 shows a state in which the spool moves to the left in the figure and the output port starts to open.
The spool 20 disposed in the bore 3 of the valve body 2 so as to be movable in the axial direction has a first land 5, a small diameter portion 6, a second land 21 and a spring guide 8 sequentially from one end as in the conventional example. The two lands 21 have a predetermined portion cut out in a ring shape in the circumferential direction, leaving a small-diameter portion 23, and an adjustment land portion directly related to opening / closing of the output port 12 (groove 13) with one end thereof facing the first land 5. The other end side is a seal land portion 24 that is oil-tight between the output port 12 and the atmosphere side where the coil spring 9 is disposed. The adjustment land portion 22 and the seal land portion 24 have the same large diameter as that of the first land 5.

The thickness (axial length) of the adjustment land portion 22 is smaller than the width (axial length) of the groove 13 of the output port 12, and therefore the notch space r between the adjustment land portion 22 and the seal land portion 24 is a groove. 13 and cooperate to form a wide relaxation chamber R2.
Since the adjustment land portion 22 and the seal land portion 24 have the same diameter, even if the hydraulic pressure is guided to the relaxation chamber R2 between the adjustment land portion 22 and the seal land portion 24, the forces applied to both lands are balanced and no axial force is generated on the spool 20.

  The adjustment land portion 22 may be thin as long as rigidity against hydraulic pressure is ensured. When the spool 20 is made of metal and inserted into the bore 3 having a hole diameter of 16 mm, for example, 2.5 mm is sufficient. The volume of the relaxation chamber R2 is preferably as large as possible. Therefore, it is preferable that the axial length of the notch space r is as long as possible. As shown in FIG. 1, it is desirable that the seal land portion 24 does not enter the width of the groove 13 as the distance from the back surface of the groove 13 to the end opposite to the opening side of the groove 13. Further, it is preferable that the notch space r has a large depth in the radial direction. However, since the diameter of the small diameter portion 23 is the same as that of the small diameter portion 6, the rigidity of the entire spool due to the small diameter portion is not affected.

  Unlike the case where only the groove 13 is used, the working oil that passes from the input working pressure chamber R1 through the opening between the groove 13 and the adjusting land portion 22 toward the output port locally has a dead end shape. Since there is a large-volume relaxation chamber R2 on the back side, it flows uniformly and smoothly over the entire circumference, and gently moves toward the output port 12 in the relaxation chamber R2. Accordingly, the uneven distribution of pressure does not easily occur around the spool 20.

In the present embodiment, the groove 13 corresponds to a groove in the invention, the second land 21 corresponds to a land, and the small diameter portion 6 corresponds to a first small diameter portion.
Further, the notch space r corresponds to a space communicating with the groove, and the small diameter portion 23 corresponds to a second small diameter portion left in the axial center portion of the space.

  The embodiment is configured as described above, and a spool 20 having a second land is disposed in a bore 3 formed in a valve body 2 having an input port 10 and an output port 12 for hydraulic oil so as to be movable in the axial direction. The output port 12 is connected to a groove 13 formed on the inner wall surface of the bore 3, and the opening amount of one end side of the second land 21 of the spool 20 is changed at one end side in the axial direction of the groove 13 due to axial displacement. In the hydraulic control valve 1 for controlling the flow rate between the input port 10 and the output port 12, the second land 21 has an adjustment land portion 22 for changing the opening amount at one end, which is smaller than the axial width of the groove 13. Since the adjacent portion of the adjustment land portion 22 is set as the notch space r communicating with the groove 13 so as to remain in the axial length, the notch space r and the groove 1 are provided on the back side of the adjustment land portion 22. Is formed, and the hydraulic fluid that passes through the opening between the groove 13 and the adjustment land portion 22 and flows toward the output port 12 flows gently. 3. Wear of the inner wall surface is prevented. (Effects corresponding to claim 1)

In particular, the notch space r has a ring shape over the entire circumference of the second land 21, and its axial length is from the other axial end of the adjustment land portion 22 to the other axial end of the groove 13 when the groove 13 starts to open. Since the seal land 24 protrudes into the width of the groove 13 and does not obstruct the flow of the hydraulic oil, the hydraulic oil flows uniformly and smoothly over the entire circumference, and the pressure uneven distribution Ensure prevention. (Effects corresponding to claim 2)
Since the small diameter portion 23 left in the axial center portion of the notch space r has the same diameter as the small diameter portion 6, it does not have a particularly small diameter compared to other portions of the spool, and the rigidity of the entire spool. Is secured. (Effects corresponding to claim 3)

The embodiment has been described by taking as an example a hydraulic control valve in which the operation oil is appropriately discharged from the input port to the output port and the operating pressure is adjusted to a predetermined constant value. However, the present invention is not limited to this, and can be applied to hydraulic control valves for various purposes such as adjusting the supply of hydraulic oil.
Further, in the embodiment, the spool is displaced by the solenoid pressure, but there is no limitation on the drive mechanism such as one driven by a solenoid.

DESCRIPTION OF SYMBOLS 1 Hydraulic control valve 2 Valve body 3 Bore 5 1st land 6 Small diameter part 8 Spring guide 9 Coil spring 10 Input port 11, 13, 15 Groove 12 Output port 14 Solenoid pressure port 20 Spool 21 2nd land 22 Adjustment land part 23 Small diameter Section 24 Seal land section R1 Input working pressure chamber R2 Relaxation chamber r Notch space

Claims (3)

A spool having a land that is movable in the axial direction is arranged in a bore formed in a valve body having an input port and an output port for hydraulic oil, and the flow rate between the input port and the output port is reduced by the axial displacement of the spool. In the hydraulic control valve to control,
The output port is connected to a groove formed on the inner wall surface of the bore,
The spool is configured to control the flow rate by changing an opening amount of one end side of the land on one end side in the axial direction of the groove by an axial displacement.
The land communicates with the groove by notching an adjacent portion of the adjustment land portion so that an adjustment land portion that changes the opening amount at one end in the axial direction is left with an axial length smaller than the axial width of the groove. A hydraulic control valve characterized by forming a space to perform.   The space is in a ring shape over the entire circumference of the land, and its axial length is at least greater than the distance from the other axial end of the adjustment land portion to the other axial end of the groove when the groove starts to open. The hydraulic control valve according to claim 1, wherein the hydraulic control valve is set. The spool has a first small diameter portion extending from the one end side of the land,
3. The hydraulic control valve according to claim 2, wherein the second small diameter portion left in the axial center portion of the space has the same diameter as the first small diameter portion.

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