JPH068672B2 - Diaphragm type pilot operated on-off valve with pressure limiting mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pilot operated on-off valve that directly opens and closes a flow path by a pilot pressure exerted on a diaphragm, and more particularly to an on-off valve including a pressure limiting mechanism that adjusts its discharge pressure.

"Prior Art and its Problems" A basic structure of a pilot operated on-off valve provided with a pressure limiting mechanism of this type is proposed by U.S. Pat. No. 4,540,020.
This U.S. patent directly proposes a directional control valve that switches the flow path, but the directional control valve is formed by closing one valve and opening the other, and opening and closing the valve. It consists of a combination of valves.

FIGS. 6 to 8 show one of the directional control valves disclosed in this U.S. Pat. explain.

This on-off valve has a flow path block 20 and a control block 40 that are divided by a diaphragm 11 that also serves as a gasket, and an on-off valve section 21 is provided in this flow path block 20. The channel block 20 has a supply port 2 for receiving a pressure fluid (pressurized air) from a pressure fluid source (compressor) P.
2 and the discharge port 23 are opened, and the load port 23 penetrates to the control block 40 side. An annular passage 24, which communicates with the supply port 22 and is open to the control block 40 side, is located on the outer periphery of the end of the load port 23 on the control block 40 side.

The end portion of the load port 23 on the control block 40 side is cut down so as to be slightly separated from the diaphragm 11 in a planar state, and the peripheral edge thereof constitutes a valve seat 23s that comes in contact with and separates from the diaphragm 11. Reference numeral 12 is a grid (mesh) that prevents the diaphragm 11 from being deformed into the load port 23 and the annular passage 24 due to the pressure difference between the front and back sides.
Is.

A pilot pressure introducing passage 28 is bored in the center of the supply port 22 of the flow passage block 20 so as to face the flow direction of the pressure fluid from the pressure fluid source P, and the pilot pressure introducing passage 28 is formed in the diaphragm 11. Through the small hole, the pilot pressure introduction path 41 on the control block 40 side, and the pilot pressure introduction path 51 branched from this introduction path, and communicated with the control chamber 52 of the pilot switching valve 50, and branched from the introduction path 41. Pressure limiting mechanism 6 via pilot pressure introducing passage 61
0 to the control room 62. Pilot pressure introduction path 2
The pressure exerted on 8 is slightly higher than the pressure of the pressure fluid at the supply port 22 according to the law of fluid dynamics. In this example, this pressure is used as the pilot pressure.

The control block 40 is provided with a pilot pressure passage 42 corresponding to the center position of the load port 23, and the pilot pressure passage 42 communicates with the control chamber 62 of the pressure limiting mechanism 60. The control chamber 62 is vertically opposed to the pilot pressure introducing passage 61, and the pressure reversing passage 63 is provided.
Is opened, and this pressure reversal path 63 is connected to the pilot switching valve 50.
Of the control room 52.

Further, an atmosphere introduction passage 53 is opened in the control chamber 52 so as to face the pilot pressure introduction passage 51 vertically. The pilot switching valve 50 is for setting the pilot pressure or the atmospheric pressure in the control chamber 52, and uses the pilot pressure introducing passage 51.
The protruding portion of the air introduction path 53 and the atmosphere introduction path 53 into the control chamber 52 is
1s and 53s, and these valve seats 51s and 53s are valve bodies 51v and 53v provided on the front and back of one end of the valve arm 54.
It is opened and closed by selecting. That is, the valve arm 54
Is swingable around its intermediate portion, has the valve elements 51v and 53v at one end, and the other end is connected to a plunger 56 that moves up and down by a solenoid 55. The plunger 56 is located at the projecting end by the force of the compression spring 57 when the solenoid 55 is demagnetized, and at this time, the valve body 51v is seated on the valve seat 51s and the valve body 53v is separated from the valve seat 53s. On the other hand, when the solenoid 55 is excited, the plunger 56 is pulled, the valve body 53v closes the valve seat 53s, and the valve body 51v opens the valve seat 51s. The end portion of the pilot pressure passage 42 on the flow passage block 20 side has a smooth arc surface 42 a that extends to the annular passage 24.

The pressure limiting mechanism 60 has a structure similar to that of the pilot switching valve 50, and the protruding portions of the pilot pressure introducing passage 61 and the pressure reversing passage 63 into the control chamber 62 have valve seats 61s, 6s.
The valve seats 61s and 63s are selectively opened and closed by the valve bodies 61v and 63v provided on the front and back of one end of the valve arm 64. That is, the valve arm 64 is swingable around its middle portion, and has the valve elements 61v and 63v on one side of the valve body.

The pressure limiting mechanism 60 is different from the pilot switching valve 50 in the driving force of the valve arm 64, and the other end of the valve arm 64 is in contact with the diaphragm 11 and moves vertically according to the movement of the diaphragm 65. It is sandwiched between the springs 66. A pressure detection chamber 67 is provided in the flow passage block 20 immediately below the plunger 65 with the diaphragm 11 sandwiched between the pressure detection chamber 67 and the load port 23 via a discharge pressure introduction passage 68. Pressure adjusting spring 66
The spring force of the adjusting screw 6 screwed into the limiting block 40
It can be adjusted by 9.

According to the opening / closing valve having the above pressure limiting mechanism, the opening / closing between the supply port 22 and the load port 23 and the load port 2
The pressure extracted from 3 can be adjusted (reduced pressure). That is, when the solenoid 55 is demagnetized,
As shown in FIG. 6, since the valve body 51v is seated on the valve seat 51s and the valve body 53v is separated from the valve seat 53s, the control chamber 5
Atmospheric pressure is introduced into 2 via the air introduction passage 53. Therefore, the pilot pressure passage 42 also becomes atmospheric pressure via the pressure inversion passage 63 and the control chamber 62. Therefore, since the back surface of the diaphragm 11 is at atmospheric pressure, the discharge pressure of the pressure fluid source P causes the diaphragm 11 to deform along the arc surface 42a and open the passage between the supply port 22 and the load port 23 as shown in FIG. The fluid flows to the load port 23.

On the other hand, when the solenoid 55 is excited, the valve body 53v is seated on the valve seat 53s and the valve body 51v is separated from the valve seat 51s as shown in FIG. Pilot pressure is introduced via 28, 41 and 51. Therefore, the pressure inversion path 63 and the control chamber 6
Pilot pressure is guided to the pilot pressure passage 42 via 2, and the diaphragm 11 is deformed toward the flow path block 20 side by receiving this pilot pressure, and is seated on the valve seat 23s and between the supply port 22 and the load port 23. Close the flow path.

When the pressure on the load port 23 side exceeds a certain value when the valve shown in FIG. 6 is opened, the pressure on the load port 23 is guided to the pressure detection chamber 67 via the discharge pressure introducing passage 68, and therefore the diaphragm. 11 is deformed to the control block 40 side and pushes up the plunger 65. Then, the valve arm 64 swings to seat the valve body 63v on the valve seat 63s, and simultaneously separates the valve body 61v from the valve seat 61s. As a result, the pilot pressure is introduced into the control chamber 62 via the pilot pressure introducing passages 41 and 61, so that the diaphragm 11 is seated on the valve seat 23s to close the flow passage, as in the state shown in FIG. Become. When the pressure on the load port 23 side decreases as a result of closing the flow path, the pressure inside the pressure detection chamber 67 also decreases, the diaphragm 11 returns to its original position, and the state shown in FIG. 6 is restored. That is, the flow path between the supply port 22 and the load port 23 opens.

As a result of the above operation being performed according to the pressure fluctuation in the pressure detection chamber 67, the discharge pressure of the pressure fluid source P can be limited and taken out from the load port 23. The discharge pressure is adjusted by adjusting the screwing position of the adjusting screw 69.
It can be adjusted by adjusting the force of the compression spring 66 acting on the.

The on-off valve with the above operating principle has no sliding part,
Therefore, there are excellent features such as no need for lubrication, a large flow rate, no need for precision machining, good workability, and the ability to incorporate a pressure limiting mechanism into a single unit, which enables size reduction. However, in order to obtain a more ideal pressure limiting characteristic, it is ideal to open and close the pilot pressure introducing passage 61 and the pressure reversing passage 63 in a snap manner, that is, in an on-off manner. It was difficult to obtain operating characteristics. Further, since there is a large gap between the plunger 65 and the plunger chamber 70 that houses the plunger 65, when the pressure in the pressure detection chamber 67 becomes high, the diaphragm 1
As shown by the chain line in FIG. 6, the deformation of No. 1 into the gap is large, and as a result, the diaphragm 11 may be fatigued and damaged in a short time.

“Object of the Invention” The present invention solves this problem, and in the flow path open state, a pressure limiting mechanism that operates sensitively to changes in discharge pressure, that is, changes in discharge pressure cause pilot pressure and atmospheric pressure in the diaphragm. It is an object of the present invention to obtain a pressure limiting mechanism capable of exerting alternately and reliably. Another object of the present invention is to obtain a pressure limiting mechanism that operates directly by the pressure on the load port side without using a diaphragm stretched between the flow path block and the control block.

[Summary of the Invention] A pressure limiting mechanism of the present invention includes a valve body; a plunger disposed in the valve body so as to be movable in the axial direction without contacting the valve body; central portions of the plunger and the valve body, respectively. A control chamber defined by a pair of diaphragms whose peripheral portions are fixed and spaced apart in the axial direction of the plunger; a pilot pressure chamber provided in the valve body that communicates with the load port and applies pilot pressure to the plunger; control A pilot pressure passage communicating with the chamber; a pilot pressure introduction passage and an atmospheric pressure introduction passage that are opened in the control chamber in parallel with the axial direction of the plunger, with their open ends facing in opposite directions; at the moving position of the plunger According to
A pair of valve seats provided on the plunger for selectively opening and closing the open ends of the pilot pressure introducing passage and the atmospheric pressure introducing passage to the control chamber; and urging the plunger in a direction against the pressure of the pilot pressure chamber. Spring means for

"Examples of the Invention" The present invention will be described below with reference to illustrated examples. 1 to 5 show an embodiment of the pressure limiting mechanism according to the present invention, and the same elements as those described in FIGS. 6 and 7 are designated by the same reference numerals. A plunger 112 is arranged on the shaft portion of the tubular valve body 111. Between the outer circumference of the plunger 112 and the inner circumference of the valve body 111, three diaphragms 113, 114, 115 are stretched at different positions in the axial direction of the plunger 112, as shown in FIG. A pilot pressure chamber 116 is defined below the lowermost diaphragm 113 in FIG. 3, and the diaphragms 114 and 115 define a control chamber 117.
Is defined. These diaphragms 113, 11
4, 115 have inner ends fixed to the plunger 112, and move with the movement of the plunger 112.
The outer end is fixed to the valve body 111. The pressure of the load port 23 is introduced into the pilot pressure chamber 116 via the discharge pressure introducing passage 68 (see FIGS. 6 and 7).

In the control chamber 117 of the valve body 111, the pilot pressure passage 42 (see FIG. 4) and the pilot pressure introduction passage 6 are provided.
1 and a pressure reversal path (atmospheric pressure introduction path) 63 are open. The pilot pressure passage 42 has a simple valve body 11
The pilot pressure introducing passage 61 and the pressure reversing passage 63 are formed as radial passages 61a, 63a and axial passages 61b, 6 at their tips, respectively.
It has 3b and is substantially L-shaped. The axial passages 61b and 63b are opened in different directions, and face the valve seats 123 and 124 provided on the plunger 112, respectively. Valve seat 1
23 and 124 open or close the axial passages 61b and 63b depending on the moving position of the plunger 112.

It should be noted that the pilot pressure or the atmospheric pressure is selectively introduced to the pressure reversal passage 63 in accordance with the excitation / demagnetization of the solenoid 55 of the pilot switching valve 50 as described above. Since the atmospheric pressure is guided,
In the claims, it is expressed as "atmospheric pressure introduction path".

In the plunger 112, the compression spring 125 inserted between the end portion on the side opposite to the pilot pressure chamber 116 and the spring force tensioning screw 126 causes the pilot pressure applied to the pilot pressure chamber 116 to reach a constant value. The valve seat 123 is always in elastic contact with the axial passage 61b to close the pilot pressure introducing passage 61, and the pressure reversing passage 63 is connected to the control chamber 117.
Is in communication with. The force exerted on the plunger 112 by the compression spring 125 can be adjusted by changing the screwing position of the flow path block 40 (fixed portion) of the adjusting screw 126.

The total opening end area S1 of the axial passage 61b and the total opening end area S2 of the axial passage 63b are the same as the pilot pressure introducing passage 6
Depending on the pressure (difference) between 1 and the pressure reversal passage 63, a difference can be provided to ensure the snap action. In this embodiment, S1> S2.

The on-off valve provided with the main pressure limiting mechanism 60 having the above-described structure is provided when the solenoid 55 of the pilot switching valve 50 is on.
As described above, the pilot pressure is applied to the pilot pressure passage 42 through the pressure reversal passage (atmospheric pressure introduction passage) 63 and the control chamber 117.
Seat on 3s to close the flow path. Therefore, the pressure of the load port 23 does not rise and the plunger 12 does not displace.

On the other hand, when the solenoid 55 of the pilot switching valve 50 is turned off, the atmospheric pressure is introduced into the pressure reversal passage 63, so that this is introduced from the control chamber 117 to the pilot pressure passage 42, and thus the supply port 22 and the load. The passage between ports 23 opens.

In this valve open state, the pressure on the load port 23 side rises, and when this pressure exerted on the pilot pressure chamber 116 via the discharge pressure introducing passage 68 overcomes the force of the compression spring 125, the plunger 112 moves to the state shown in FIG. As shown, the valve seat 123 starts to rise, and separates from the axial passage 61b. Then, the pressure fluid in the pilot pressure introducing passage 61 flows into the control chamber 117 via the axial passage 61b. At this time, the pressure (atmospheric pressure) in the pressure inversion path 63 is equal to
The pressure in the pilot pressure passage 61 is higher than the pressure in the pressure inversion passage 63, and the axial passage 61b
Since the total opening end area S1 of the above and the total opening end area S2 of the axial passage 63b are S1> S2, the axial force exerted on the plunger 112 is larger than the ascending force by the axial passage 61b. Therefore, the plunger 112 instantly reaches the rising end. That is, as shown in FIG. 3, the valve seat 1
23 opens the axial passage 61b and the valve seat 124 closes the axial passage 63b.
Since the pilot pressure from 1 is applied to the pilot pressure passage 42, the diaphragm 11 is seated on the valve seat 23s,
The connection between the supply port 22 and the load port 23 is closed. In this state, the upward force due to the pressure from the axial passage 61b is exerted on the plunger 112, so that it is stable. Therefore, even if the pilot pressure exerted on the pilot pressure chamber 116 is slightly lowered, the plunger 11
There is no possibility that 2 will descend and switch the flow path in reverse. FIG. 5 is a schematic graph showing the relationship between the pilot pressure and the stroke of the plunger 112, and such snap action operation characteristics can be obtained. The operation starting pressure of the plunger 112 can be adjusted by adjusting the compression spring force by the adjusting screw 126.

As a result of closing the space between the supply port 22 and the load port 23, when the pressure in the load port 23 is sufficiently reduced, the plunger 12 reaches the lower end and returns to the state of FIG.
Atmospheric pressure is introduced at 17. Therefore, the pilot pressure passage 42 becomes the atmospheric pressure, and the diaphragm 11 becomes the arc surface 42a.
The inside is deformed and the supply port 22 and the load port 23 communicate with each other.

Since the above operation is performed by the fluctuation of the pressure in the load port 23, the fluid pressure taken out from the load port 23 can be limited.

Although the present invention has been described above as the simplest on-off valve, various directional switching valves can be configured by combining these on-off valves. The present invention is naturally applicable to these directional control valves.

The diaphragms 113 and 114 in the above embodiment
Theoretically, it is possible to combine them into a single diaphragm, but with a single diaphragm, it is repeatedly bent in the opposite direction due to fluctuations in the pressure difference between the pilot pressure chamber 116 and the control chamber 117. Therefore, the life of the diaphragm is significantly shortened. On the other hand, if the pilot pressure chamber 116 and the control chamber 117 are defined by different diaphragms 113 and 114 as in the present embodiment, sufficient durability can be obtained without such a problem.

"Effect of the Invention" As described above, according to the present invention, according to the moving position,
A plunger that selectively connects the pilot pressure passage to either the pilot pressure introduction passage or the atmospheric pressure introduction passage is given a snap action in response to the pressure on the load port side so that the passage can be switched instantaneously. Therefore, for the diaphragm that opens and closes between the supply port and the load port,
The pilot pressure and the atmospheric pressure can be instantaneously switched and applied. Therefore, it is possible to instantly open and close the flow path by the diaphragm to obtain a more ideal pressure limiting characteristic. Further, according to the present invention, the pressure on the load port side is directly exerted on the diaphragm on the plunger side without using the diaphragm stretched between the flow path block and the control block. There is no danger of damage.

[Brief description of drawings]

1 to 3 are sectional views showing an embodiment of a pressure limiting mechanism of the present invention in different operating states, FIG. 4 is a sectional view taken along line IV-IV of FIG. 1, and FIG. 5 is a plunger. FIG. 6 is a longitudinal sectional view showing one open / close valve taken out from a directional control valve provided with a pressure limiting mechanism proposed in US Pat. No. 4,540,020, and FIG. 7 is FIG. 8 is a vertical cross-sectional view in an operating state different from that shown in FIG.
It is sectional drawing which follows the II line. 11 ... Diaphragm, 20 ... Flow path block, 21 ... Open / close valve section, 22 ... Supply port, 23 ... Load port, 23s ...
Valve seat, 24 ... Annular passage, 28, 41, 51, pilot pressure introducing passage 61 ... Pilot pressure introducing passage, 40 ... Control block, 42 ... Pilot pressure passage, 50 ... Pilot switching valve, 60 ... Pressure limiting mechanism, 62 ... Control chamber, pilot pressure introducing passages 61v, 63v ... Valve body, 63 ... Pressure reversing passage (atmospheric pressure introducing passage), 111 ... Valve body, 112 ... Plunger, 113, 114, 115 ... Diaphragm, 116 ...
Pilot pressure chamber, 117 ... Control chamber, 123, 124 ...
Valve seat.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Kojima 1-34-19 Ohara, Setagaya-ku, Tokyo (56) Reference JP-A-61-157880 (JP, A) ) Actually open 50-38528 (JP, U) Actually open 56-158564 (JP, U) Actually open 38-21470 (JP, Y1)

Claims (3)

[Claims] 1. A diaphragm is sandwiched between a flow path block and a control block, a supply port and a load port to be opened and closed are provided in the flow path block, and the supply port and the load port are connected to the control block side. It is possible to directly open and close between both ports by the diaphragm, while forming a pilot pressure passage on the control block side for exerting pilot pressure on the diaphragm from the surface opposite to the flow passage block. In addition, when the pilot switching valve that selectively operates the pilot pressure and atmospheric pressure on this pilot pressure passage and the communication between the supply port and the load port by this pilot switching valve, the pressure on the load port side is small or large. A die having a pressure limiting mechanism for selectively operating pilot pressure or atmospheric pressure in the pilot pressure passage according to In a ram-type pilot operated on-off valve, the pressure limiting mechanism includes a valve body; a plunger disposed inside the valve body so as to be movable in the axial direction without contacting the valve body; and the center of the plunger and the valve body, respectively. Control chamber defined by a pair of diaphragms that are fixed to a peripheral portion and a peripheral portion and are separated from each other in the axial direction of the plunger; and a pilot pressure chamber provided in the valve body that communicates with the load port and applies the pilot pressure to the plunger. And a pilot pressure passage communicating with the control chamber; and a pilot pressure introduction passage and an atmospheric pressure introduction passage that are opened in the control chamber in the opposite directions parallel to the axial direction of the plunger. ; Open ends of the pilot pressure introducing passage and the atmospheric pressure introducing passage to the control chamber depending on the moving position of the plunger. A pair of valve seats fixedly provided to the plunger for selectively opening and closing; spring means for urging the plunger in a direction against the pressure of the pilot pressure chamber; Diaphragm pilot operated on-off valve with pressure limiting mechanism. 2. The opening area of the opening end in the control chamber of the pilot pressure introducing passage and the atmospheric pressure introducing passage according to claim 1, the plunger starts to move due to the pressure of the load port exerted on the pilot pressure chamber. Then, a diaphragm type pilot operated on-off valve having a pressure limiting mechanism having a difference so as to cause a movement in the same direction in consideration of the pressure difference between the two introduction paths. 3. The pressure limiting device according to claim 1 or 2, wherein the pilot pressure chamber in the valve body is defined by a third diaphragm stretched between the plunger and the valve body. A diaphragm type pilot operated on-off valve with a mechanism.