JPH067243Y2 - Direction switching valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] In the present invention, a main valve is switched to a plurality of positions by switching control of a pilot valve for supplying and exhausting, and a direction in which a fluid supply direction is switched by this switching arrangement. It relates to a switching valve.

[Prior Art] This type of directional control valve is disclosed in Japanese Patent Publication No. 57-59469, Japanese Utility Model Publication No. 62-37028 and Japanese Utility Model Publication 1-79.
No. 01 publication.

In the conventional device of Japanese Utility Model Publication No. 62-37028, switching is arranged from a neutral position to a working fluid supply position by supplying pilot fluid against the return spring, and the main valve is moved to the neutral position by the return spring as the pilot fluid is exhausted. It is designed to return to.

Japanese Patent Publication No. 57-59469 and Japanese Utility Model Publication 1-7901
In the conventional device of the publication, fluid pressure acting through the auxiliary piston is added to the action of the return spring for the main valve to improve the quick return response to the neutral position of the main valve.

[Problems to be Solved by the Invention] However, in Japanese Utility Model Publication No. 62-37028, it is necessary to set the spring characteristic of the return spring in consideration of the frictional force in the seal ring for sealing the main valve, so that the neutral position is not changed. A strong spring characteristic is required to achieve a high speed of return. If the spring characteristic is made strong, the pilot pressure must be increased in order to quickly switch and arrange the main valve from the neutral position to the working fluid supply position, but this increase in pressure increases the static friction force in the seal ring. Therefore, when the main valve is left at the working fluid supply position for a long time, the static frictional force of the seal ring due to the pilot pressure increases, and the reliability of returning to the neutral position decreases.

Japanese Patent Publication No. 57-59469 and Japanese Utility Model Publication 1-7901
In the conventional device disclosed in Japanese Patent Publication No. 62-37028, the addition of the fluid pressure action via the auxiliary piston supplements the neutral return action of the pressure spring, and the neutral position return response is faster than the conventional device disclosed in Japanese Utility Model Publication No. 62-37028. Good. However, since the same pressure as the pilot pressure acts on the auxiliary piston when switching from the neutral position to the working fluid supply position, the pressure receiving area of the main valve (that is, the diameter of the main piston) with respect to the pilot pressure is calculated as follows: , The diameter of the auxiliary piston). In order to improve the quick response of the main valve, it is necessary to increase this diameter difference or increase the pilot pressure. Increasing the diameter difference inevitably increases the size of the entire device, and the auxiliary piston mechanism complicates the device.

An object of the present invention is to provide a directional control valve capable of improving the responsiveness of directional control while avoiding complication, increase in size and high pilot pressure.

[Means for Solving the Problem] Therefore, in the present invention, a back pressure region is provided corresponding to the pilot pressure chamber that causes the pilot fluid supplied by the switching supply operation of the pilot valve to act on the main valve. The exhaust port of the pilot valve was connected by a back pressure passage, and an exhaust passage having a throttling action was connected on the back pressure passage.

[Operation] When the pilot valve is switched from the supply state to the exhaust state, the pilot pressure chamber communicates with the back pressure region, and the fluid in the pilot pressure chamber flows into the back pressure passage via the pilot valve. The high-pressure fluid that has flowed into the back pressure passage is divided into the exhaust passage and the back pressure region, but the back pressure corresponding to the degree of throttling of the exhaust passage acts on the main valve as a biasing force from the working fluid supply position side toward the neutral position side. To do. Therefore, by appropriately setting the throttling action of the exhaust passage, the pressure in the back pressure region can be instantly increased and immediately reduced, and the main valve at the working fluid supply position has an instantaneous backup restoring force. As soon as it works, the back pressure in the back pressure area is immediately released. This allows the main valve to quickly return to the neutral position, increasing the reliability of returning to the neutral position after being left for a long time. This quick return to the neutral position can suppress the strengthening of the spring characteristics of the return spring,
Moreover, since the back pressure in the back pressure region is released in the neutral state, the pilot pressure for switching from the neutral position to the working fluid supply position can be lowered.

[Embodiment] An embodiment embodying the present invention will be described below with reference to FIGS.

A piston housing 3 is joined and fixed to one end of a valve housing 2 that slidably accommodates the spool valve 1, and a first piston 4 is slidably fitted and accommodated in the piston housing 3 and at the same time, the piston 4
A V-shaped seal 5 is fitted on the peripheral surface of the. Piston 4
The storage chamber is divided into a pilot chamber P ₁ and respiration chamber S ₁ by the piston 4, together with the pilot port l ₁ is connected to the pilot pressure chamber P _1, respiration chamber S ₁ is via the respiratory port 3a Communicating with the atmosphere.

A spring housing 6 is joined and fixed to the other end of the valve housing 2, and a pair of collars 7 and 8 are slidably opposed and fitted to the end of the spool valve 1 protruding into the spring housing 6. A return spring 9 is interposed between the collars 7 and 8. The collar 7 is always in contact with the inner end surface 6a of the spring housing 6 by the action of the return spring 9, and the other collar 8 is the end surface 2 of the valve housing 2.
Contact a. When the collars 7 and 8 are in contact with the end surfaces 6a and 2a, the spool valve 1 communicates with the input port 2b on the valve housing 2 and the output ports 2c ₁ and 2c ₂ , and the input port 2b and the exhaust port 2d ₁ . It is placed in a neutral position that blocks communication with 2d ₂ .

A piston housing 10 is joined and fixed to the spring housing 6, a second piston 11 is slidably fitted and housed in the piston housing 10, and a V-shaped seal 12 is fitted on the circumferential surface of the piston 11. Has been. Receiving chamber of the piston 11 is divided into a pilot chamber P ₂ and respiration chamber S ₂ by the piston 11, together with the pilot port l ₂ is connected to the pilot pressure chamber P _2, respiration chamber S ₂ is breathing port 10a Through the atmosphere. Further, a space in the spring housing 6 communicates with the breathing port 10a.

Pilot ports l ₃ and l ₄ are branched and connected to an input port 2b on the valve housing 2, and a pilot valve 13 composed of an electromagnetic three-way valve is interposed between the pilot ports l ₁ and l ₃ and the pilot port l ₃ and l ₄ are connected. Port l ₂ ,
l ₄ Similar pilot valve to between 14 is interposed.
The input port 13a of the pilot valve 13 is connected to the pilot port l ₃ , and the output port 13b of the pilot valve 13 is connected to the pilot port l ₁ . Further, the input port 14a of the pilot valve 14 is connected to the pilot port _{l 4,} the output port 1 of the pilot valve 14
4b is connected to the pilot port l ₂ .

Exhaust ports 13c and 14c of both pilot valves 13 and 14
Are connected by a back pressure line L, an exhaust line La is branched and connected in the middle of the back pressure line L, and the exhaust line L
A needle valve 15 is attached to the tip of a.

In FIG. 1, both pilot valves 13 and 14 are in a demagnetized state, the pilot ports l ₁ and l ₃ and the pilot ports l ₂ and l ₄ are cut off, and the pilot ports l ₁ and l ₂ are It communicates with the atmosphere via the back pressure line L and the exhaust line La. Therefore, the collars 7 and 8 come into contact with the end faces 6a and 2a by the action of the return spring 9, and the spool valve 1 is arranged and held in the neutral position.

When energizing the pilot valve 13 communicates the input port 13a and output port 13b includes a pilot port l ₃ and the pilot port l ₁ is communicated. By this communication, the working fluid supplied from the input port 2b on the valve housing 2 flows into the pilot pressure chamber P ₁ , and the spool valve 1 is moved to the left as shown in FIG. As a result, the input port 2b and the output port 2 of the valve housing 2 are
The working fluid communicates with c ₁ and the working fluid supplied from the input port 2b is output from the output port 2c ₁ .

When exciting the other pilot valve 14 instead of energizing the pilot valve 13 communicates with the input port 14a and output port 14b includes a pilot port l ₄ and the pilot port l ₂ are communicated. The communication by the working fluid supplied from the input port 2b flows into the pilot pressure chamber P _2, the spool valve 1 as shown in FIG. 4 is moved disposed to the right. Thereby, the input port 2b and the output port 2c
₂ and the working fluid supplied from the input port 2b is output from the output port 2c ₂ .

When the spool valve 1 is deenergized the pilot valve 13 from the state of FIG. 2 which is arranged to the operating fluid supply position of the left, along with the pilot port l _1, l ₃ is cut off as shown in FIG. 3, the pilot The port l ₁ and the back pressure line L communicate with _{each other} , and the fluid in the pilot pressure chamber P ₁ flows into the back pressure line L. Fluid flowing into the back pressure line L is diverted to the pilot valve 14 side and the exhaust pipe La side, the fluid diverted to the pilot valve 14 side exhaust port 14c of the pilot valve 14, the output port 14b and the pilot port l ₂ It flows into the pilot pressure chamber P ₂ via. Therefore, the spool valve 1 in the left-hand working fluid supply position is acted on by the spring force of the return spring 9 via the collar 8 and the back pressure of the fluid flowing into the pilot pressure chamber P ₂ via the piston 11, and The valve 1 returns to the neutral position shown in FIG. That is, the pilot pressure chamber P ₂
Is a back pressure region for the pilot pressure chamber P ₁ .

If the pilot valve 14 is demagnetized from the state shown in FIG. 4 in which the spool valve 1 is located at the working fluid supply position to the right, the pilot ports l ₂ and l ₄ are shut off as shown in FIG. The port ₁₂ and the back pressure pipe L communicate with each other, and the fluid in the pilot pressure chamber P ₂ flows into the back pressure pipe L. Fluid flowing into the back pressure line L is diverted to the pilot valve 13 side and the exhaust pipe La side, the fluid diverted to the pilot valve 13 side exhaust port 13c of the pilot valve 13, the output port 13b and the pilot port l ₁ It flows into the pilot pressure chamber P ₁ via. Therefore, the spool valve 1 in the right working fluid supply position is acted on by the spring force of the return spring 9 via the collar 7 and the back pressure of the fluid flowing into the pilot pressure chamber P ₁ via the piston 4. Valve 1 is first
Return to the neutral position in the figure. That is, the pilot pressure chamber P ₁ becomes a back pressure region with respect to the pilot pressure chamber P ₂ .

The magnitude of the back pressure and the exhaust time in the pilot pressure chamber P ₁ or P ₂ are adjusted by the degree of throttling of the needle valve 15, and the magnitude of the back pressure for the piston 11 or 4 is set by appropriately setting the degree of throttling of the needle valve 15. It is possible to achieve a momentary back pressure action while securing the appropriateness. Therefore, while increasing the pressure in the back pressure area instantaneously,
It can be immediately lowered, and a momentary backup restoring force acts on the spool valve 1 in the working fluid supply position. As a result, the spool valve 1 quickly returns to the neutral position, and the back pressure in the back pressure region is immediately released. The quickness of the return to the neutral position makes it possible to reduce the spring characteristics of the return spring 9, and since the back pressure in the back pressure region is released in the neutral state, the pilot for switching from the neutral position to the working fluid supply position The pressure can be set to low pressure. Since the back pressure acts on the entire pressure receiving area of the pistons 11 and 4, the backup restoring action by the back pressure is very efficient.

When the spool valve 1 is left at the working fluid supply position for a long period of time, the pressure in the pilot pressure chambers P ₁ and P ₂ increases the static friction force in the V-shaped seals 5 and 12, and the pilot pressure chambers P ₁ and P 2 _When the pressure of ₂ is high, the reliability of returning to the neutral position after being left for a long time decreases. However, by reducing the spring characteristics of the return spring 9, the pilot pressure for disposing the spool valve 1 from the neutral position to the working fluid supply position can be lowered, and the reliability of returning to the neutral position after being left for a long time is high.

Also, by avoiding the increase in size of the return spring 9, it is possible to avoid increasing the size of the entire apparatus.

Further, in this embodiment, since the auxiliary piston is not used unlike the conventional devices of Japanese Patent Publication No. 57-59469 and Japanese Utility Model Publication No. 1-7901, the structure can be simplified and the cost can be reduced.

In this embodiment, due to the left-right symmetry of both pilot pressure chambers P ₁ and P ₂ , which are also the back pressure region, there is very little variation in the return from the left and right working fluid supply positions to the neutral position, but the pilot valve is placed on one side. Even when the exhaust passage lengths are different as in the case of shifting, it is possible to reduce variations in the return time to the neutral position by appropriately setting the degree of throttling of the needle valve 15. Further, instead of making the pilot pressure chamber and the back pressure region correspond to each other via the spool valve 1 and the pistons 4 and 11, the pilot pressure chamber and the back pressure region may be made to directly correspond to each other only via the piston. Therefore, only one piston is required.

Of course, the present invention is not limited to the above-described embodiment. For example, as shown in FIGS.
It is also possible to apply the present invention to a direction switching valve which is arranged to switch to the working fluid supply position shown in the figure. In this embodiment, a piston housing 10 for accommodating the piston 17 is directly joined and fixed to the valve housing 2, and a return spring 9 is provided between the piston housing 10 and the piston 17.
Is intervening. When the pilot valve 13 is demagnetized from the working fluid supply state shown in FIG. 7, the fluid in the pilot pressure chamber P ₁ is discharged from the needle valve 15 and flows into the back pressure region P ₃ . As a result, the same effect as the above embodiment can be obtained.

In this embodiment has a valve housing 2 is used in the embodiment, the output port 2c _2, although blind plug 18, 19, 20 to the exhaust port 2d ₂ and the pilot port _{l 4} is fitted, the output port 2c Of course, it is also possible to use a valve housing without ₂ , exhaust port 2d ₂ and pilot port l ₄ .

Further, in the present invention, it is possible to adopt an embodiment in which an exhaust passage for providing a constant throttling action is adopted.

[Advantage of the Invention] As described in detail above, the present invention provides a back pressure region corresponding to the pilot pressure chamber that causes the pilot fluid supplied by switching the supply of the pilot valve to act on the main valve. Since the exhaust port of the valve is connected by the back pressure passage and the exhaust passage with the throttling action is connected on the back pressure passage, the fluid pressure discharged from the pilot pressure chamber at the time of neutral return is the backup return force. Acts on the main valve as
As a result, there is an excellent effect that the responsiveness of the direction change can be improved while avoiding the complication of the mechanism, the increase in size, and the increase in pilot pressure.

[Brief description of drawings]

1 to 5 show an embodiment embodying the present invention.
The drawing is a vertical cross-sectional view showing a neutral state, FIG. 2 is a vertical cross-sectional view showing one working fluid supply state, FIG. 3 is a vertical cross-sectional view showing a state where neutral return is started from FIG. 2, and FIG. 5 is a vertical cross-sectional view showing the working fluid supply state of FIG. 5, FIG. 5 is a vertical cross-sectional view showing a state in which neutral return is started from FIG. 4, FIGS. 6 and 7 show another example, and FIG. FIG. 7 is a vertical sectional view showing a working fluid supply state. Spool valve 1 as main valve, return spring 9, pilot valves 13 and 14, pilot pressure chambers P ₁ and P also serving as back pressure regions
₂ , back pressure line L, exhaust line La.

Claims (1)

[Scope of utility model registration request] 1. A main valve (1) is switched to a working fluid supply position against a return spring (9) by a switching supply operation of a pilot valve (13, 14), and a pilot valve (13, 14) In the direction switching valve in which the main valve (1) is switched to the neutral position by the action of the return spring (9) by the switching exhaust operation, the pilot valve (13,
14) The back pressure region (P ₂ , P ₁ ) is provided corresponding to the pilot pressure chambers (P ₁ , P ₂ ) that act on the main valve (1) with the pilot fluid supplied by the switching supply operation of Region (P ₂ , P ₁ ) and pilot valve (13, ₁ )
The exhaust port (13c, 14c) of 4) is connected by a back pressure passage (L), and an exhaust passage (La) having a throttling action is connected on the back pressure passage (L). Directional switching valve.