JPS62177380A - Diaphragm type pilot operated switching valve with pressure limiting mechanism - Google Patents

Abstract

PURPOSE:To reliably switch passages by giving snap action to a pump for communicating a pilot pressure passage alternatively with a pilot pressure introducing passage or with an atmospheric pressure introducing passage. CONSTITUTION:A pilot pressure passage 42, a pilot pressure introducing passage 61 and an atmospheric pressure introducing passage 63 are opened to a control chamber 117. A plunger 112 forces a valve seat 123 to close the pilot pressure introducing passage 61 by a compression spring 125 until the pilot pressure reaches a designated value. When the pilot pressure increases, the plunger 112 starts rising to reach the rising end. Accordingly, the pilot pressure and the atmospheric pressure can be switched to a diaphragm instantaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention provides a method for controlling M
The present invention relates to a pilot-operated on-off valve that opens and closes a Wi flow path, and particularly relates to an on-off valve equipped with a pressure limiting mechanism that adjusts its discharge pressure.

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

Figures 6 to 8 show one of the directional control valves and its pressure limiting mechanism disclosed in this U.S. patent. First, based on these figures, we will explain the operating principle of this valve. explain.

This on-off valve has a flow path block 2o separated by a diaphragm 11 which also serves as a gasket, and a control block 40, and an on-off valve section 21 is provided in this flow path block 20. The flow path block 20 includes a pressure fluid source (combrera 0
) Supply port 22 that receives pressure fluid (pressurized air) from P
Then, the discharge port 23 opens, and this load port 23 penetrates to the control block 40 side. The supply port 2 is located on the outer periphery of the end of the load port 23 on the control block 40 side.
2 and open to the control block 40 side.
4 is located.

The end of the load port 23 on the control block 4o side is cut down slightly forward of the flat diaphragm 1, and its peripheral edge forms a valve seat 23s that approaches and separates from the diaphragm 11. . 12 is a grid (mesh body) 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 of the diaphragm 11;
It is.

A pilot pressure introduction path 28 is bored in the center of the supply port 22 of the flow path flock 20 so as to directly face the flow direction of the pressure fluid from the pressure fluid source P. It communicates with the control chamber 52 of the pilot switching valve 50 through a small hole, a pilot pressure introduction path 41 on the control block 40 side, and a pilot pressure introduction path 51 branched from this introduction path, and is also branched from the introduction path 41. Pressure limiting mechanism 6 via pilot pressure introduction path 61
It communicates with the control room 62 of 0. Pilot pressure introduction path 2
The pressure exerted on 8 will be slightly higher than the pressure of the pressure fluid at supply port 22 due to the laws of fluid mechanics. In this example, this pressure is used as a pilot pressure.

A pilot pressure passage 42 is bored in the control block 40 so as to correspond to the center position of the load port 23 , and this pilot pressure passage 42 communicates with a control chamber 62 of the pressure limiting mechanism 60 . The control chamber 62 also includes a pressure reversal path 63 vertically facing the pilot pressure introduction path 61.
This pressure reversal path 63 is connected to the pilot switching valve 50.
It passes through the control room 52.

Further, an atmospheric air introduction passage 53 opens in the control chamber 52 and vertically faces the pilot pressure introduction passage 51 . The pilot switching valve 50 is for setting the inside of the control chamber 52 to pilot pressure or atmospheric pressure, and the pilot pressure introduction path 51
The protruding portion of the atmospheric air introduction passage 53 into the control chamber 52 is connected to the valve seat 5.
1s, 53s, and the valve seats 51s, 53s or the valve bodies 51v, 53v provided on the front and back of one end of the valve arm 54.
It is selectively opened and closed by That is, the valve arm 54 is swingable around its middle portion, and has the valve bodies 51v and 53v at one end, and the solenoid 5 at the other end.
5 is connected to a plunger 56 that moves up and down. This plunger 56 is located at the protruding 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 removed from the valve seat 53s. On the other hand, when the solenoid 55 is energized, the plunger 56 is pulled, and the valve body 53v is moved to the valve seat 5.
3s is closed, and the valve body 51v opens the valve seat 51s.The end of the pilot pressure passage 42 on the flow passage block 20 side forms a smooth circular arc surface 42a extending to the annular passage 24.

The pressure limiting mechanism 60 has a similar structure to the pilot switching valve 50, and the protruding portions of the pilot pressure introducing path 61 and the pressure reversing path 63 into the control chamber 62 are connected to the valve seats 61s and 6.
3s, and these valve seats 61s and 63s are selectively opened and closed by valve bodies 61v and 63v provided on the front and back sides of one end of the valve arm 64. That is, the valve arm 64 is swingable around its middle portion, and has the valve bodies 61v, 63v on the front and back sides of one end thereof.

The difference between the pressure limiting mechanism 60 and the pilot switching valve 5° is the driving force of the valve arm 64. The other end of the valve arm 64 is connected to a plunger 65 that contacts the diaphragm 1 and moves up and down in response to the movement of the diaphragm 1. , and is sandwiched between the pressure adjustment spring 66. A pressure detection chamber 67 is provided in the flow path block 20 directly below the plunger 65 with the diaphragm 11 in between, and the pressure detection chamber 67 communicates with the load port 23 through a discharge pressure introduction path 68 . The spring force of the pressure adjustment spring 66 is controlled by the adjustment screw 6 screwed into the control block 40.
9 can be adjusted.

According to the on-off valve equipped with the above pressure limiting mechanism, the opening and closing between the supply port 22 and the load port 23, and the opening and closing between the supply port 22 and the load port 23 are possible.
The pressure taken out from 3 can be adjusted (depressurized). In other words, 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
2, atmospheric pressure is introduced through the atmospheric air introduction path 53.

Therefore, the pilot pressure passage 42 also becomes atmospheric pressure via the pressure reversal 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 deforms the diaphragm 1 along the arcuate surface 42a as shown in the figure to open a passage between the supply port 22 and the load port 23. Pressure fluid flows into the load port 23.

On the other hand, when the solenoid 557ali571 is magnetized, the valve body 53v is seated on the valve seat 53s as shown in FIG. Pilot pressure is led through .41 and 51&. For this reason, pilot pressure is guided to the pilot pressure passage 42 via the pressure reversal passage 63 and the control chamber 62, and the diaphragm 11 receives this pilot pressure and deforms toward the flow passage block 20 and seats on the valve seat 233. The flow path between the supply port 22 and the load port 23 is then closed.

When the valve is opened as shown in FIG. 6, if the pressure on the load port 23 side exceeds a certain value, the pressure on the load port 23 is guided to the pressure detection chamber 67 via the discharge pressure introduction path 68, so the diaphragm 11 deforms toward the control block 4o and pushes up the plunger 65. Then, the valve arm 64 swings, causing the valve body 63v'a to be seated on the valve seat 63s, and at the same time, disengaging the valve body 61v from the valve seat 61s. As a result, pilot pressure is introduced into the control chamber 62 via the pilot pressure introduction passages 41 and 61, so that the diaphragm 11 is in contact with the valve seat 23 s ILl as in the state shown in FIG.
: Seating down and closing the flow path, the diaphragm 11 returns to its original position and returns to the state shown in FIG. 6. That is, the flow path between the supply port 22 and the load port 23 is opened.

As a result of the above-described operations being performed in response to pressure fluctuations within the pressure detection chamber 67, the discharge pressure of the pressure fluid source P can be limited and the pressure fluid can be taken out from the load port 23. The discharge pressure can be adjusted by adjusting the threading position M of the adjusting screw 69.
The compression acting on can be adjusted by adjusting the force of the spring 66.

The on-off valve with the above operating principle has no sliding parts,
Therefore, it has excellent features such as not requiring lubrication, allowing a large flow rate to flow, having good workability without requiring precision machining, and being able to be miniaturized by integrating a pressure limiting mechanism. However, at a more ideal pressure limit! Although it is ideal to open and close the pilot pressure introduction path 61 and the pressure reversal path 63 in a snap manner, that is, in an on/off manner, it is difficult to obtain this operating characteristic with the pressure limiting mechanism 60. Met. Furthermore, since there is a large gap between the plunger 65 and the plunger chamber 70 that houses it, when the pressure inside the pressure detection chamber 67 becomes high pressure, the diaphragm 1 will move into this gap as shown by the chain line in FIG. As a result, the diaphragm 11 may become fatigued and damaged in a short period of time.

``Object of the Invention'' The present invention solves this problem and uses a pressure limiting mechanism that sensitively operates depending on fluctuations in discharge pressure when the flow path is open. The purpose of the present invention is to obtain a pressure limiting mechanism that can alternately and reliably apply pressure. Moreover, the present invention
The object of the present invention is to obtain a pressure limiting mechanism that is operated directly by the pressure on the load port side without using a diaphragm stretched between a flow path block and a control block.

"Summary of the Invention" The pressure limiting mechanism of the present invention includes: a valve body; a plunger disposed movably in the axial direction within the valve body;
at least a pair of diaphragms extending between the plunger and the valve body and defining a control chamber and a pilot pressure chamber communicating with the load port; the pilot pressure passage communicating with the control chamber; Similarly, in the control room, there are provided a pilot pressure introduction passage and an atmospheric pressure introduction passage whose opening ends are opened in opposite directions to each other with respect to the axial direction of the plunger; a valve seat installed in the plunger that selectively opens and closes the opening end of the atmospheric pressure introduction path to the control chamber; and a spring means that biases the plunger in a direction against the pressure of the pilot pressure chamber. It is configured.

"Embodiments of the Invention" The present invention will be described below with reference to illustrated embodiments. 1 to 5 show embodiments of the pressure limiting mechanism according to the present invention, and the same elements as those explained in FIGS. 6 and 7 are given the same reference numerals. A plunger 112 is disposed on the shaft of the cylindrical valve body 111. Three diaphragms 113.1]4.1]5 are stretched between the outer circumference of the plunger]12 and the inner circumference of the valve body 111, with the axial force of the plunger 112 being different in position N from -□. A pilot pressure chamber 116 is defined below the lowest diaphragm 113 in FIGS. 1 to 3, and a control chamber 117 is defined by the diaphragms 114 and 115.
is defined. These diaphragms 113.11
4, ]15 have their inner ends fixed to the plunger 112 and move as the plunger 112 moves, and their outer ends are fixed to the valve body 1]1. The pressure of the load port 23 is introduced into the pilot pressure chamber 116 via the discharge pressure introduction path 68 (see FIGS. 6 and 7).

The control chamber 117 of the valve body 11 includes the pilot pressure passage 42 (see FIG. 4) and the pilot pressure introduction passage 6.
1 and a pressure reversal path (atmospheric pressure introduction path) 63 are open. The pilot pressure passage 42 is a simple valve body 111
However, the pilot pressure introduction passage 61 and the pressure reversal passage 63 are formed as radial passages 61a, 63a, and axial passages 61b, 63 at their tips, respectively.
tl and has an abbreviated shape. The axial passages 61b and 63b are open in different directions and face valve seats 123 and 124 provided in the plunger 112, respectively. Valve seat 12
3 and 124 correspond to the moving position of the plunger 112,
The axial passages 61b and 63b'A are opened or closed.

Note that pilot pressure or atmospheric pressure is selectively guided to the pressure reversal path 63 in accordance with @ demagnetization of the solenoid 55 of the pilot switching valve 50 as described above, but when the pressure limiting mechanism 60 operates, it is necessary to Since the atmospheric pressure is guided,
In the billing section, it is described as an "atmospheric pressure introduction path."

The plunger 112 is operated by a compression spring 125 inserted between the end opposite to the pilot pressure chamber 116 and a spring tensioning spring 126 until the pilot pressure applied to the pilot pressure chamber 116 reaches a certain value. , the valve seat 123 is always forced into the axial passage 61b to close the pilot pressure introduction passage 61, and the pressure reversal passage 63 is connected to the control chamber 11.
7 is connected. The force exerted on the plunger 112 by the compression spring 125 can be adjusted by changing the screwing position of the adjustment screw 126 to the flow path block 40 (fixed portion).

Note that the total opening end area 81 of the axial inner passage gslb and the total opening end area 32 of the axial passage 63b ensure snap action according to the pressure (difference) between the pilot pressure introduction path 61 and the pressure reversal path 63. A difference can be made for this purpose. In this embodiment, Sl>82.

When the solenoid 55 of the pilot switching valve 50 is on, the on-off valve equipped with the pressure limiting mechanism 60 configured as described above:
As mentioned above, the pilot pressure passage 42 includes a pressure reversal passage (
Since pilot pressure is applied via the atmospheric pressure introduction path) 63 and the control chamber 117, the diaphragm 11
s and close the flow path. Therefore, the pressure in the load port 23 will not increase, and the plunger 12 will not be displaced.

On the other hand, when the solenoid 55 of the pilot switching valve 50 is turned off, 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 therefore the C supply port 22. Load port 23 A dark passage opens.

During this time, in the valve state, the pressure on the load port 23 side increases, and when this pressure applied to the pilot pressure chamber 116 via the discharge pressure introduction path 68 overcomes the force of the compression spring 125, the plunger 1]2 moves as shown in FIG. It begins to rise as shown in
The valve seat 123 is separated from the axial passage 61b. Then, the pressure fluid in the pilot pressure introduction path 6 flows into the control chamber 1 through the axial passage 61b. At this time, the pressure (atmospheric pressure) in the pressure reversal passage 63 is acting on the plunger 12, or the pressure in the pilot pressure passage 61 is higher than the pressure in the pressure reversal passage 63, and the total opening end area 81 of the axial passage 61b is , since the total open end area 82 of the axial passage 63b is set as Sl>S2, the plunger 112
The axial force exerted on the axial passage 61b is larger than the upward force caused by the axial passage 61b. Therefore, the plunger 112 instantaneously reaches the rising end. That is, as shown in FIG. 3, the valve seat] 23 is the axial passage 611)! Open the valve seat]
24 closes the axial passage 63b%, and this time the pilot pressure from the pilot pressure introduction passage 61 or the pilot pressure passage 42
Therefore, the diaphragm 11 is seated on the valve seat 23s, and the space between the supply port 22 and the load port 23 is closed. In this state, the plunger 112 has an axial passage 61b.
It is stable because the rising force due to the pressure from the pilot pressure chamber 116 (
Even if the applied pilot pressure drops slightly, there is no risk that the plunger 1]2 will fall and switch the flow path in the opposite direction6.
FIG. 5 is a schematic graph showing the relationship between the pilot pressure and the stroke of the plunger 112, which provides the operational characteristics of such a snap action. The starting pressure of the plunger 112 can be adjusted by adjusting the compression spring force using the adjusting screw 126.

As a result of closing between the supply port 22 and the load port 23, when the pressure inside the load port 23 drops sufficiently, the plunger 12 reaches the lowering end and returns to the state shown in FIG.
Atmospheric pressure is introduced into 7. Therefore, pilot pressure passage 4
2 becomes atmospheric pressure, the diaphragm 11 deforms into the arcuate surface 42a, and the supply port 22 and the load port 23 communicate with each other.

Since the above operation is performed by fluctuations in the pressure within 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 constructed by combining these on-off valves. The present invention is naturally applicable to these directional valves as well.

Note that the diaphragms 113 and 114 in the above embodiment can theoretically be used as a single diaphragm, but if they are used as a single diaphragm, fluctuations in the pressure difference between the pilot pressure chamber 116 and the control chamber 117 The life of the diaphragm is significantly shortened as it is repeatedly bent in opposite directions by the diaphragm. On the other hand, if the pilot pressure chamber 116 and the control chamber 117 are defined by separate diaphragms 1] 3,114 as in this embodiment, sufficient durability can be obtained without such problems.

"Effects of the Invention" As described above, according to the present invention, depending on the movement position,
The plunger that selectively communicates the pilot pressure passage with either the pilot pressure introduction passage or the atmospheric pressure introduction passage receives the pressure on the load port side and gives a snap action, allowing the flow passage to be switched instantaneously. Therefore, for the diaphragm that opens and closes between the supply port and the load port,
Pilot pressure and atmospheric pressure can be switched and applied instantly. Therefore, the flow path can be opened and closed instantaneously by the diaphragm, and more ideal pressure limiting characteristics can be obtained. In addition, the present invention directly applies the pressure on the load port side to the diaphragm on the plunger side without using a diaphragm stretched between the flow path block and the control block, so the durability of the diaphragm on the on-off valve body side is improved. There is no risk of damage.

[Brief explanation of drawings]

1 to 3 are sectional views showing embodiments of the pressure limiting mechanism of the present invention in different operating states; FIG. 4 is a sectional view taken along line IV-IV in FIG. 1; and FIG. 5 is a sectional view of the plunger. FIG. 6 is a graph showing the operating characteristics of U.S. Pat. No. 4,540.
020 is a longitudinal sectional view showing a one-open/closed well taken out from a directional control valve equipped with a pressure limiting mechanism proposed in No. 020, FIG. 6th
It is a sectional view taken along the line ■-■ in the figure. 11...Diaphragm, 2o...Flow path block, 2
1... Opening/closing valve part, 22... Supply port, 23...
Load port, 23s... valve seat, 24... annular passage,
28.41.51, pilot pressure introduction path 61...pilot pressure introduction path, 40...control block, 42...
Pilot pressure passage, 50...Pilot switching valve, 6o
... Pressure limiting mechanism, 62 ... Control room, pilot pressure introduction path 61v, 63v ... Valve body, 63 ... Pressure reversal path (atmospheric pressure introduction path), 111 ... Valve body, 11
2...Plunger, 113.114.115...Diaphragm, 116...Pilot pressure chamber, 117.
...Control room, 123.124...Valve seat. Patent applicant: Fujikura Rubber Industries Co., Ltd. Agent: Kunio Miura Shigeru Matsui Figure 2 Figure 3 Figure 4 Reaction force of pilot press 16 Figure 5 Figure 7

Claims (3)

[Claims] (1) A diaphragm is sandwiched between a flow path block and a control block, and a supply port and a load port to be opened and closed are provided in the flow path block, and the supply port and load port are opened to the control block side. so that the two ports can be directly opened and closed by the diaphragm, and on the other hand, a pilot pressure passage is formed on the control block side for applying pilot pressure to the diaphragm from the surface opposite to the flow path block, Furthermore, when the supply port and the load port are communicated by the pilot switching valve that selectively applies pilot pressure or atmospheric pressure to this pilot pressure passage, and the pilot switching valve , a diaphragm type pilot operated on-off valve having a pressure limiting mechanism that selectively applies pilot pressure or atmospheric pressure to the pilot pressure passage, wherein the pressure limiting mechanism includes: a valve body; a movably disposed plunger; at least a pair of diaphragms extending between the plunger and the valve body and defining a control chamber and a pilot pressure chamber communicating with the load port; The pilot pressure passage communicates with the pilot pressure passage; and a pilot pressure introduction passage and an atmospheric pressure introduction passage, which are also opened in the control chamber with their opening ends facing opposite to each other with respect to the axial direction of the plunger; a valve seat provided on the plunger that selectively opens and closes the opening ends of the pilot pressure introduction path and the atmospheric pressure introduction path to the control chamber; A diaphragm-type pilot-operated on-off valve equipped with a pressure limiting mechanism characterized by comprising a biasing spring means. (2) In claim 1, the opening area of the opening ends of the pilot pressure introduction path and the atmospheric pressure introduction path in the control chamber is determined when the plunger starts moving due to the pressure of the load port applied to the pilot pressure chamber. , a diaphragm type pilot-operated on-off valve equipped with a pressure limiting mechanism that takes into account the pressure difference between the two introduction passages and causes movement in the same direction as the pressure difference. (3) In claim 1 or 2, the pilot pressure chamber within the valve body is separate from a pair of diaphragms that define a control chamber and are stretched between the plunger and the valve body. A diaphragm-type pilot operated on-off valve with a pressure limiting mechanism defined by a third diaphragm.