JPH0454493Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pilot-type current-controlled pressure reducing valve that reduces the pressure in an outlet passage to a constant pressure.

[Prior Art] This type of current-controlled pressure reducing valve has conventionally been constructed as illustrated in FIG.
The inlet passage 1b is slidably inserted in the axial direction within the inlet passage 1b.
A spool 2 that can communicate with and shut off the outlet passage 1c.
, an operating surface 2a formed at one end of the spool 2 (lower end in the figure) that slides the spool 2 toward the other end in response to the pressure in the outlet passage 1c, and an exit passage formed at the other end of the spool 2 through the throttle 2b. It has a pressure chamber Ro that communicates with 1c, and a spring 3 that is built into the pressure chamber Ro and biases the spool 2 toward one end. Further, the current-controlled pilot relief valve 4, which controls the pressure in the pressure chamber Ro in accordance with the current value for energizing, is equipped with a poppet valve body 4a, and is connected to a pilot passage 4b after the throttle 2b that guides fluid to the poppet valve body 4a. is provided with a second diaphragm 5.

In such a conventional current-controlled pressure reducing valve, the pressure in the outlet passage 1c rises, and the pressure in the pressure chamber Ro communicating through the throttle 2b also rises.
The pressure in Ro is current controlled pilot relief valve 4
When the value (relief pressure) exceeds the value set in , the relief valve 4 opens and fluid flows through the throttle 2b, creating a pressure difference between both ends of the spool 2.
moves against the spring 3. Therefore, the space between the inlet passage 1b and the outlet passage 1c is narrowed, resulting in a pressure drop, and the pressure in the outlet passage 1c is adjusted to be reduced according to the relief pressure.

[Problems to be Solved by the Invention] However, in the conventional current-controlled pressure reducing valve, the lowest pressure in the outlet passage 1c that can be adjusted for pressure reduction is when the relief pressure of the current-controlled pilot relief valve 4 is zero. Incidentally, in order for the spool 2 to move, the operating surface 2e at one end must receive enough pressure within the outlet passage 1c to move against the spring force of the spring 3. However, the spring constant and mounting load of the spring 3 cannot be extremely small due to the need to ensure operational response and operational stability of the pressure reducing valve. In addition, for the purpose of operational stability, a throttle 2b that guides fluid to the poppet valve body 4a of the current-controlled pilot relief valve 4 is provided.
By providing a second throttle 5 in the rear pilot passage 4b and creating a throttle state close to that of the throttle 2b, the spool 2 is prevented from axially moving due to pressure fluctuations in the pressure chamber Ro due to axial vibration of the poppet valve body 4a. This suppresses an oscillation phenomenon in which the pressure in the outlet passage 1c repeatedly fluctuates up and down due to vibration in the direction. Due to the acting force of the second throttle 5 of the pilot passage 4b and the spring 3, even if the relief pressure of the current-controlled pilot relief valve 4 is zero, the minimum pressure that can be adjusted to reduce the pressure inside the outlet passage 1c is normally maintained. The reality is that it cannot be lowered below 20Kgf/cm ² .

[Means for solving the problem] This invention was made in view of the actual situation,
A spool that is slidably inserted into the inner hole of the valve body in the axial direction and can disconnect communication between the inlet passage and the outlet passage; a plunger which is arranged coaxially with the valve body at a predetermined distance from the other end of the spool and is slidably fitted in the axial direction to form a pressure chamber at the other end; , a spring that is interposed in a free state between the plunger and the spool and is compressed when the distance between the two falls below a set value; and a spring that is applied to the pressure chamber from the inlet passage through the pilot pressure reducing valve and the throttle. The configuration includes a current-controlled pilot relief valve that controls pressure according to the current value.

[Operation of the invention] In the current-controlled pressure reducing valve according to the invention configured as described above, the inlet passage is connected to a fluid pressure source, the outlet passage is connected to a suitable actuator, and high-pressure fluid is introduced into the inlet passage. When the current-controlled pilot relief valve is energized and given an arbitrary current value, the pressure in the pressure chamber is controlled to a value corresponding to the current value that is energized to the current-controlled pilot relief valve, and this control pressure causes the plunger to be directed toward one end. The spring force is adjusted between the spool and the plunger, and the spool moves to a position where the spring force and the force exerted by the pressure inside the outlet passage applied to the working surface of one end are balanced. Therefore, it is possible to generate a pressure in the outlet passage according to the value of the current applied to the current-controlled pilot relief valve. In addition, pressure fluctuations in the pressure chamber due to the operation of the current-controlled pilot relief valve are transmitted to the spool via the plunger and spring, so axial vibration of the spool due to pressure fluctuations is suppressed, and the pressure in the outlet passage is reduced. The oscillation phenomenon in which the voltage repeatedly fluctuates up and down is suppressed. Moreover, since pressure is applied to the pressure chamber from the inlet passage through the pilot pressure reducing valve and the throttle, the flow rate passing through the throttle is kept constant even if the pressure in the inlet passage changes.

By the way, in the current-controlled pressure reducing valve according to the present invention, if the power supply to the current-controlled pilot relief valve is cut off, the pressure in the pressure chamber becomes almost zero, the plunger is no longer pushed, and the spool moves between the inlet passage and the outlet passage. Even if you move to the blocking position,
In the free state, the spring force of the interposed spring can remain approximately zero, and the pressure within the outlet passage can be approximately zero.

[Example] An example of the present invention will be described below based on the drawings.

FIG. 1 shows a current-controlled pressure reducing valve according to the present invention,
Further, FIG. 3 shows the same pressure reducing valve with symbols, and in the same pressure reducing valve, the valve body 10 is provided with a stepped inner hole 11 for accommodating a spool 20, a plunger 30, and a spring 40, as well as an inlet passage 12 and an outlet passage. It is equipped with a passage 13 and a pilot passage 14, and a nozzle 50 as a throttle is installed in the pilot passage 14 to set the flow rate flowing through the passage 14, and to adjust the same flow rate to the pressure in the inlet passage 12. Pilot pressure reducing valve 60 to maintain constant pressure even if it changes
is interposed. Further, a current-controlled pilot relief valve 70 is assembled to the valve body 10.

The spool 20 has a communication hole 20a and a small hole 20b in its axis, and has a communication hole 20a and a small hole 20b in its lower end as shown in FIG.
c, and is fitted into the lower end of the inner hole 11 so as to be slidable in the axial direction, and forms a passage 15 that communicates with the inlet passage 12 and the outlet passage 13 at the intermediate part 20d, and the lower end shown in the figure The communication hole 20 at the working surface 20e of
c is adapted to receive the pressure in the outlet passage 13 applied through the passage 15, and when it is slid toward the upper end shown, it constricts the passage 15 and creates a pressure drop.
Note that the upper end of the communication hole 20a in the drawing is the spring 40.
The chamber R1 communicates with a drain hole 19 (see FIG. 3) provided in the valve body 10.

The plunger 30 is disposed coaxially at the upper side of the spool 20 in the first drawing, separated by a predetermined distance, and is assembled in the upper part of the inner hole 11 so as to be slidable in the axial direction, and has a pressure chamber R2 at the upper end. When the pressure in the pressure chamber R2 is approximately zero, the plunger 3
0 at the illustrated position (return position) by a spring 31 with a small spring force. Note that the return position of the plunger 30 can be adjusted using an adjustment screw 32. In addition, a chamber R3 housing the spring 31 is
communicates with the drain hole 19 as shown in FIG.

The spring 40 is interposed in a free state between the plunger 30 and the spool 20, and its lower end as shown in FIG. It abuts on a slidably assembled retainer 41. The retainer 41 is the stepped portion 30b of the plunger 30.
When the distance between the plunger 30 and the spool 20 becomes equal to or less than a set value, the spring 40 comes into contact with the stepped portion 30b and compresses the spring 40.

The current-controlled pilot relief valve 70 is connected to the pressure chamber R2 through the pilot pressure reducing valve 60 and the nozzle 50.
An electromagnetic motor having a movable core 71, a coil 72, and fixed cores 73 and 74 integrally equipped with a pin 71a, and a pin 71a of the movable core 71. The poppet 75 pushed by the poppet 7
5 is configured by a valve seat 76 on which the valve seat 5 is seated. Note that the electromagnetic motor can increase the acting force (downward force in FIG. 1) at each position of the movable iron core 71 almost equally as the current value flowing through the coil 72 increases, and can also move in the direction of the acting force. It has a characteristic that the acting force decreases as the iron core 71 changes, and it is known as
This is known from the publication No.-30128.

As shown in FIG. 2, the pilot pressure reducing valve 60 includes a spool 61 that is assembled to be slidable in the axial direction within the inner hole 16 provided in the valve body 10, and a spring that biases the spool 61 downward in the figure. 62, its inlet 63 communicates with the inlet passage 12, its outlet 64 communicates with the nozzle 50, and its outlet 65 communicates with the drain hole 19.
is connected to. Note that reference numeral 17 in FIG. 2 indicates a communication hole for communicating the outlet of the current-controlled pilot relief valve 70 with the drain hole 19.
(See Figure 3) In the current-controlled pressure reducing valve configured as described above, the inlet passage 12 is connected to a fluid pressure source and the outlet passage 1 is connected to the fluid pressure source.
3 to a suitable actuator to open the inlet passage 1.
When high-pressure fluid is introduced into 2 and the coil 72 of the current-controlled pilot relief valve 70 is energized to give an arbitrary current value, the pressure chamber R changes to a value corresponding to the current value energized to the current-controlled pilot relief valve 70.
2 internal pressure is controlled, and the plunger 30 is pushed toward the lower end against the spring 31 by this control pressure, and the spring force of the spring 40 is adjusted between the spool 20 and the plunger 30. The spool 20 moves to a position where the force and the acting force due to the internal pressure of the outlet passage 13 received on the lower end acting surface 20e are balanced. Therefore, it is possible to generate a pressure in the outlet passage 13 according to the current value applied to the coil 72 of the current-controlled pilot relief valve 70. Moreover, since the pressure fluctuations in the pressure chamber R2 due to the operation of the current-controlled pilot relief valve 70 are transmitted to the spool 20 via the plunger 30 and the spring 40, the oscillation phenomenon in which the pressure in the outlet passage 13 repeatedly fluctuates up and down is suppressed. . Furthermore, since pressure is applied from the inlet passage 12 to the pressure chamber R2 through the pilot pressure reducing valve 60 and the nozzle 50, even if the pressure in the inlet passage 12 changes, the nozzle 5
The flow rate passing through 0 is kept constant.

By the way, in the same current-controlled pressure reducing valve, if the power supply to the coil 72 of the current-controlled pilot relief valve 70 is cut off, the pressure in the pressure chamber R2 becomes almost zero and the plunger 30 is no longer pushed.
The plunger 30 is returned to the illustrated position by the force of the spring 31. For this reason, spool 2
Even if the spring 40 moves upward to the position where the passage 15 is most constricted, the spring force of the spring 40 inserted in the free state can remain almost zero, and the pressure inside the outlet passage 13 can be made almost zero. .

In the above implementation, the present invention was implemented by providing the communication hole 20a and the small hole 20b in the spool 20 in order to stabilize the decompression performance.
Since the spring force of 0 and the acting force due to the internal pressure of the outlet passage 13 received by the lower end acting surface 20e are balanced, the above-mentioned implementation is possible even if the present invention is implemented without providing the communication hole 20a and the small hole 20b. It is possible to obtain substantially the same operation as in the example. In addition, the present invention was implemented by providing a spring 31 so that the weight of the plunger 30 would not act on the spring 40 when the current to the coil 72 of the current-controlled pilot relief valve 70 was cut off.
If the dead weight of the spring 40 is small and the pressure in the outlet passage 13 is not affected much even if it acts on the spring 40, substantially the same operation as in the above embodiment can be obtained even if the present invention is implemented without the spring 31. is possible.

[Effects of the invention] As is clear from the above explanation, according to the current-controlled pressure reducing valve according to the present invention, the pressure in the pressure chamber can be reduced to almost zero by cutting off the electricity to the current-controlled pilot relief valve. Even if the spool moves to a position where it blocks the inlet passage and the outlet passage, the spring force of the interposed spring can remain almost zero in the free state, and the current-controlled pressure reducing valve can reduce the pressure. The minimum pressure in the adjustable outlet passage can be increased to almost zero, and the current-controlled pressure reducing valve can be used in locations where it could not be used conventionally, and the range of use of the current-controlled pressure reducing valve can be expanded. In addition, since the pressure fluctuations in the pressure chamber caused by the operation of the current-controlled pilot relief valve are transmitted to the spool via the plunger and spring, the best spring is used to prevent vertical fluctuations in the pressure in the outlet passage. A current-controlled pressure reducing valve without repeated oscillation phenomena can be realized. In addition, pressure is applied to the pressure chamber from the inlet passage through the pilot pressure reducing valve and the throttle, so that even if the pressure in the inlet passage changes, the flow rate passing through the throttle remains constant. Unnecessary operation of the relief valve is suppressed, and good operational stability is obtained.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing one embodiment of the current-controlled pressure reducing valve according to the present invention, Fig. 2 is a cross-sectional view taken along the - line in Fig. 1, and Fig. 3 is a cross-sectional view showing an embodiment of the current-controlled pressure reducing valve shown in Fig. 1. Figure 4, which is indicated by symbols, is a sectional view showing an example of a conventional current-controlled pressure reducing valve. Explanation of symbols, 10...Valve body, 11...Inner hole,
12...Entrance passage, 13...Exit passage, 14...
Pilot passage, 15... Passage, 20... Spool, 20d... Middle part, 20e... Working surface, 30
...Plunger, 40...Spring, 50...
Nozzle (restriction), 60...Pilot pressure reducing valve, 7
0...Current control pilot relief valve, R2...
pressure chamber.

Claims (1)

[Scope of utility model registration request] A spool that is slidably inserted into the inner hole of the valve body in the axial direction and can disconnect communication between the inlet passage and the outlet passage; a plunger which is arranged coaxially with the valve body at a predetermined distance from the other end of the spool and is slidably fitted in the axial direction to form a pressure chamber at the other end; , a spring that is interposed in a free state between the plunger and the spool and is compressed when the distance between the two falls below a set value; and a spring that is applied to the pressure chamber from the inlet passage through the pilot pressure reducing valve and the throttle. A current-controlled pressure reducing valve comprising a current-controlled pilot relief valve that controls pressure according to a current value.