JPS641804B2 - - Google Patents

Description

[Detailed description of the invention] The present invention reduces primary pressure to create secondary pressure,
This invention relates to a pressure control valve that stabilizes this secondary pressure.

A conventional pressure control valve of this type is a constant secondary pressure type three-port pressure reducing valve 1 as shown in FIG. This pressure reducing valve 1 is a type of pressure control valve that controls the pressure by the corner of the spool land, and this pressure control valve has a spreading flow with a positive damping length and a negative damping This creates a narrowing flow with a long length.

That is, as shown in FIG. 2, a constant secondary pressure type three-port pressure reducing body 1 is used as a pilot valve for a guide valve 2. This pressure reducing body 1 is a first pressure control part 5 formed around the right corner of the land 4 of the spool 3.
A primary port 6 and a secondary port 7 are formed by separating them, and a secondary port 7 and a tank port 9 are formed by separating a second pressure control part 8 formed around the left corner of the land 4. ing.

Also, the pilot chamber 1 at the left end of the spool 3
When the secondary pressure (P ₂ ) acting on _the Secondary pressure (P ₂ ) is spring 1
If the force becomes too large than 1 force, the second pressure control section 8
The secondary pressure (P ₂ ) is increased by increasing the opening degree of the spring 1 and decreasing the value of the secondary pressure (P ₂ ).
The force is maintained at the same value as 1 force.

In the above case, the fluid passing through the first pressure control section 5 flows out from the center of the spool 3 while spreading out in the same centrifugal direction, resulting in a so-called spreading flow. Since the fluid flows out from the periphery of the spool 3 in a concentric direction in a symmetrical state to that described above, the flow is narrowed.

In these two types of flow, the narrowing flow has a negative damping length and generates energy that increases the vibrations of the spool 3 compared to the widening flow having a positive damping length. This causes the problem of making the spool 3 extremely unstable and generating noise due to vibration.

In addition, this type of pressure control valve is used as the flow rate adjustment guide valve 2.
When used as a pilot valve, the instability of the spool 3 due to the narrowing flow as described above causes fluctuations in the secondary pressure, which results in the spool 12 in the guide valve 2 becoming unstable and the flow rate to the actuator 13 fluctuating. This is accompanied by other disadvantages. Furthermore, since the secondary pressure (P ₂ ) is only released from the second pressure control section 8 to the tank, there is a drawback that the larger the guide valve 2 becomes, the worse the return response of the spool 12 becomes.

The present invention was invented in view of the above points, and an object of the present invention is to stabilize the spool by making the first pressure control section and the second pressure control section expand and flow, thereby reducing noise caused by vibration of the spool. In addition to preventing the occurrence of secondary pressure fluctuations, it stabilizes the operation of the guide valve that uses the secondary pressure, and also allows the guide valve to return quickly by releasing the secondary pressure from the 2nd line to the tank. The present invention provides a pressure control valve.

The technical means of the present invention for solving this technical problem is to provide a secondary port 25 in the valve chamber 15 of the housing 14.
And, primary ports 23 are installed on both sides of this secondary port 25.
While opening the tank port 27, the spool 16 is inserted into the valve chamber 15, and the spool 16 is opened.
Three lands 20, 21, 22 are provided in the spool 16, and first and second annular grooves 40, 41 are formed between these lands, and a pilot chamber 17 is formed at the end of the spool 16. Annular groove 40
A first pressure control section 28 for a widening flow formed by the housing 14 and one end corner of the intermediate land 21 is interposed in the supply path for supplying fluid from the primary port 23 to the secondary port 25 via. Further, a second pressure control section 29 for a spreading flow formed by the housing 14 and one end corner of the first land 20 is interposed in the discharge path for discharging the fluid from the pilot chamber 17 to the tank port 27. At the same time, the secondary port 25 and the pilot chamber 17 are communicated with each other through a passage 30, and a proportional solenoid 35 serving as a pressure adjustment element is provided on the side of the spool 16 opposite to the pilot chamber. Room 1
The fluid pressure of the secondary port 25 acting on the pressure control portions 28, 2 is
9 to maintain the pressure of the secondary port 25 constant, while controlling the pressure of the secondary port 2 of the intermediate land 21.
When the proportional solenoid 35 is energized, the area between the secondary port 25 and the tank port 27 is closed, and when the proportional solenoid 35 is deenergized, the amount of wrap (L ₃ ) for 25
This is a pressure control valve that opens the secondary port 25 and releases the fluid from the secondary port 25 to the tank port 27.

According to the technical means of the present invention, in the first pressure control section, the flow is widening as in the conventional example, and especially in the second pressure control section, where the flow was narrowing in the past, the flow is also widening, making the spool unstable. This eliminates the narrowing flow caused by the spool, thereby stabilizing the spool, preventing the generation of noise due to vibration of the spool, and improving the accuracy of the secondary pressure.

Also, when the proportional solenoid is energized, the space between the secondary port and the tank port is closed, and the first and second pressure control sections control the pressure of the secondary port to a value corresponding to the suction force of the proportional solenoid. When the secondary port is demagnetized, the secondary port is opened at the other end of the intermediate land, and the secondary port and the tank port are communicated with each other through a total of two connecting paths, this communication path and the second pressure control section. The fluid in the secondary port is released to the tank, and the guide valve is operated to return with high response.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The pressure control valve shown in FIG.
A pilot chamber 17 is formed at the left end of a spool 16 which is slidably provided in a valve chamber 15 formed inside, and a proportional solenoid 35 is provided at the right end as a pressure regulating element.

The spool 16 is provided with a total of three lands 20, 21, 22 at its substantially middle portion and both ends, and first and second annular grooves 40, 41 are formed between these lands. A primary port 23 is formed between the middle land 21 (intermediate land) and the right end land 22 (second land), and a secondary port 25 is formed in the large diameter chamber 24 formed around the intermediate land 21. , a tank port 27 is formed in a large diameter chamber 26 formed around the left end land 20 (first land).

Furthermore, a first pressure control section 28 is formed around the right corner of the intermediate land 21 between the primary port 23 and the secondary port 25, while a first pressure control section 28 is formed around the right corner of the intermediate land 21 between the pilot chamber 17 and the tank port 27. A second pressure control section 29 is formed around the left corner of the first land 20.

Further, the dimension (L ₁ ) from end to end of both lands 20, 21 and the dimension (L ₂ ) from the right end of the large diameter chamber 24 on the right side to the left end of the large diameter chamber 26 on the left side are made the same, The first and second pressure control sections 28 and 29 are configured to open and close alternately. Furthermore, a predetermined amount (L ₃ ) of intermediate land 21 is provided between both large diameter chambers 24 and 26.
The two large-diameter chambers 24 and 26 are isolated by overlapping each other.

Due to this overlap of the intermediate land 21, the two large diameter chambers 24 and 26 are normally cut off, and when the first pressure control section 28 is closed by rightward movement of the spool 16 and the second pressure control section 29 is wide open,
The left end of the intermediate land 21 opens the large diameter chamber 24 and communicates with the large diameter chamber 26.

That is, when the proportional solenoid 35 is demagnetized, the second pressure control section 29 is opened, and after this opening, the secondary port 25 is opened on the left end side of the intermediate land 21, and the fluid in the secondary port 25 is transferred to the tank port 2.
The amount of wrap (L ₃ ) of the intermediate land 21 with respect to the secondary port 25 is set in such a manner that it is open to the secondary port 25.

On the other hand, a throttle 31 is interposed in a passage 30 that communicates the secondary port 25 and the pilot chamber 17.

The proportional solenoid 35 has a characteristic of generating an attractive force proportional to the applied current value, and causes this attractive force to act on the spool 16 via the movable iron core 36. The suction force corresponds to the pressing force due to the product of the pressure receiving area at the left end of the spool 16 and the secondary pressure (P ₂ ).
The secondary pressure (P ₂ ) is set proportional to the suction force of the proportional solenoid 35. In other words, the secondary pressure (P ₂ )
is always proportional to the current value applied to the proportional solenoid 35.

In FIG. 1, numeral 33 represents a flow rate regulating guide valve connected to the secondary port 25, and numeral 34 represents an actuator connected to this guide valve 33.

The illustrated embodiment is configured as described above,
The action will be explained below.

When an applied current is applied to the proportional solenoid 35 in FIG.
is moved to the left by the suction force to close the second pressure control section 29 and open the first pressure control section 28.

Therefore, a spreading flow as shown by the arrow occurs in the first pressure control section 28 from the primary port 23 to the secondary port 25, increasing the secondary pressure (P ₂ ). When this secondary pressure (P ₂ ) becomes larger than the suction force of the proportional solenoid 35, the spool 16 moves to the right, contrary to the above, and the first pressure control section 2
8 is closed and the second pressure control section 29 is opened.

Therefore, in the second pressure control section 29, a spreading flow as shown by the arrow is generated from the pilot chamber 17 toward the tank port 27, reducing the secondary pressure (P ₂ ). As a result, the spool 16 stands still so that the secondary pressure (P ₂ ) and the suction force of the proportional solenoid 35 are balanced.

Ideally, _{the relationship between dimension L 1 and dimension L 2 in FIG .} , dimension L ₁ than dimension L ₂
It is desirable to make it slightly larger.

However, if the difference between the length of _L1 and the length of _L2 is too large, the width of the dead zone will increase according to the amount of overlap, and the response will decrease accordingly.
It is also not preferable to make the difference between L ₁ and L ₂ too large. However, when the viscosity of the fluid increases or the flow rate increases, L ₁ <L ₂ is also possible.

Therefore, when the spool 16 is stationary, the difference between the amount of leakage from the annular gap around the first pressure control section 28 and the amount of leakage from the annular gap around the second pressure control section 29 Secondary port 25
A predetermined reduced pressure is obtained.

In this case, there is a leak corresponding to the amount of overlap (L ₃ ) at the overlap portion between the two large-diameter chambers 24, 26 and the intermediate land 21, but the amount of leakage at the overlap portion is negligible. The overlap part will not open during control.

As described above, the fluid in both the first pressure control section 28 and the second pressure control section 29 is a spreading flow with a positive attenuation length, and as a result, the spool 16 is stabilized.

In FIG. 1, when the secondary pressure (P ₂ ) acting on the pilot chamber 17 becomes greater than the suction force of the proportional solenoid 35 and the spool 16 is moved to the right by the secondary pressure (P ₂ ), the passage A constriction 31 provided within 30 provides resistance to the flow from the secondary port 25 in the direction of the pilot chamber 17 and reduces the rate of displacement of the spool 16.

Contrary to the above, in FIG. 1, the suction force of the proportional solenoid 35 is greater than the secondary pressure (P ₂ ) acting on the pilot chamber 17, and when the spool 16 is moved to the left, the
The throttle 31 acts as a resistance to the fluid that is pushed back toward the secondary port 25, reducing the displacement speed of the spool 16.

In this way, the throttle 31 reduces the displacement speed of the spool 16 during control action and reduces the inertial force of the spool 16, so the installation of the throttle 31 stabilizes the spool 16.

By the way, the guide valve 33 operated by the pressure control valve causes particles contained in the fluid to get stuck in the clearance of the peripheral surface of the land of the spool 12, so the guide valve 33 applies vibration to the spool to prevent the spool from sticking. Consideration must be given to In this regard, in the present invention, the sticking phenomenon of the guide valve 33 can be eliminated by applying an electrical dither to the spool 16 using the proportional solenoid 35 to vary the secondary pressure little by little. In particular, if the idea of solving the sticking phenomenon by adding an electric dither using a solenoid to a pressure control valve that inherently has an unstable spool like the conventional product, the pressure control valve itself becomes extremely unstable and becomes stuck. Even if the phenomenon is resolved, the accuracy of the secondary pressure will decrease, but since the present invention stabilizes the spool 16 in advance by spreading flows in both pressure control sections 28 and 29, the spool 16 is not as unstable as the conventional product. It is possible to eliminate the sticking phenomenon of the guide valve 33 by using an electric dither without making it stable.

When the proportional solenoid 35 is demagnetized from the secondary pressure (P ₂ ) control state as described above, the spool 16
moves to the right due to the pressure in the pilot chamber 17. This rightward movement of the spool 16 closes the first pressure control section 28 and opens the second pressure control section 29, and then the large diameter chamber 24 communicates with the large diameter chamber 26. As a result, the secondary port 25 and the tank port 27 communicate with each other via the second pressure control section 29 and around the left corner of the intermediate land 21 as shown by the solid line arrow and the dotted line arrow, respectively.

Therefore, the fluid in the secondary port 25 is released from the two lines to the tank, and the pressure in the secondary port 25 drops rapidly. As a result, the spool 12 of the guide valve 33 connected to the secondary port 25 quickly returns to its original position, compared to the conventional product shown in FIG. The return response of the guide valve 33 is quick. In particular, the larger the guide valve 33 is, the larger the discharge flow rate from the secondary port to the tank port is, so the effect of discharging fluid from the two lines is great. Furthermore, since the discharge flow capacity has been increased despite the small size, it can be used as a common pressure control valve regardless of the size of the guide valve, expanding the range of use.

As described in detail above, the present invention provides the primary port 23
The secondary pressure is controlled by a first pressure control section 28 that makes the flow from the secondary port 25 to the tank port 27 a spreading flow, and a second pressure control section 29 that makes the flow from the secondary port 25 to the tank port 27 a spreading flow. As a result of this, it is possible to prevent the generation of noise due to spool vibration, and the effect of stabilizing the operation of the guide valve is achieved by reducing fluctuations in the secondary pressure.

Further, the secondary port 25 of the intermediate land 21 configured separately from the first land 20 of the second pressure control section 29
The amount of wrap (L ₃ ) for the proportional solenoid 3
When 5 is energized, the space between the secondary port 25 and the tank port 27 is closed, and when it is demagnetized, the secondary port 25 is opened at the other end of the intermediate land 21, and the fluid in the secondary port 25 is transferred to the tank. port 2
7, and when the proportional solenoid 35 is demagnetized, the fluid on the secondary side is sent to the tank from two systems: the second pressure control part 26 and the secondary port 25 opened by the intermediate land 21. We measured the capacity increase of the discharge flow rate each time the valve was opened.
Compared to the conventional product shown in FIG. 2, the flow rate discharge from the secondary port is rapid, the guide valve can be returned to its original state at high speed, and the guide valve can be operated with high response. Furthermore, since the discharge flow rate capacity has been increased despite the small size, it can be used as a common pressure control valve regardless of the size of the guide valve, which has the effect of expanding the range of use.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional example. 14...Housing, 15...Valve chamber, 16...
Spool, 20, 21, 22...Land, 23...
...Primary port, 25...Secondary port, 27...Tank port, 28...First pressure control section, 29...
Second pressure control section, 30... passage, 35... proportional solenoid, 40, 41... annular groove.

Claims (1)

[Claims] 1 Secondary port 25 in valve chamber 15 of housing 14
And, primary ports 23 are installed on both sides of this secondary port 25.
While opening the tank port 27, the spool 16 is inserted into the valve chamber 15, and the spool 16 is opened.
Three lands 20, 21, 22 are provided in the spool 16, and first and second annular grooves 40, 41 are formed between these lands, and a pilot chamber 17 is formed at the end of the spool 16. Annular groove 40
A first pressure control section 28 for a widening flow formed by the housing 14 and one end corner of the intermediate land 21 is interposed in the supply path for supplying fluid from the primary port 23 to the secondary port 25 via. Further, a second pressure control section 29 for a spreading flow formed by the housing 14 and one end corner of the first land 20 is interposed in the discharge path for discharging the fluid from the pilot chamber 17 to the tank port 27. At the same time, the secondary port 25 and the pilot chamber 17 are communicated with each other through a passage 30, and a proportional solenoid 35 serving as a pressure adjustment element is provided on the side of the spool 16 opposite to the pilot chamber. Room 1
The fluid pressure of the secondary port 25 acting on the pressure control portions 28, 2 is
9 to maintain the pressure of the secondary port 25 constant, while controlling the pressure of the secondary port 2 of the intermediate land 21.
When the proportional solenoid 35 is energized, the area between the secondary port 25 and the tank port 27 is closed, and when the proportional solenoid 35 is deenergized, the amount of wrap (L ₃ ) with respect to 25
A pressure control valve characterized in that the pressure control valve is configured such that the secondary port 25 is opened and the fluid in the secondary port 25 is released to the tank port 27.