JPH0341682B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a non-bleed type pilot relay suitable for use, for example, as an amplifier for various pneumatic instruments.

[Conventional technology]

In general, non-bleed type pilot relays (pilot valves) have low air consumption, and
It has characteristics such as large exhaust capacity, but on the other hand, there is a dead spot in the flow characteristics between supply and exhaust capacity and pneumatic output, and a dead band in the pressure characteristics between pneumatic input and pneumatic output. This has the disadvantage that a so-called dead zone occurs, and when this is applied to a pneumatic instrument, its operational stability is impaired.

To briefly explain this using a conventional example shown in FIG. 4, a non-bleed type pilot relay, generally designated by reference numeral 1, has a supply pressure chamber 3, an output chamber 4, an atmosphere communication chamber 5 and It has an input chamber 6, and among these chambers, the supply pressure chamber 3 and the output chamber 4 communicate with each other through a through hole 8 bored in an internal partition wall 7, and the output chamber 4 communicates with the atmosphere. The chamber 5 is defined by a lower diaphragm 9, and the atmospheric communication chamber 5 and the input chamber 6 are defined by an upper diaphragm 10. An opening 11 is formed in the center of the lower diaphragm 9, and this opening 11 is connected to the upper and lower diaphragms 10,
A hole 12a is opened into a cylindrical body 12 which is interposed between the cylindrical body 9 and connects these bodies, and which is further bored on the side of the cylindrical body 12. A hole 12a is opened into the atmosphere communication chamber 5.

13 and 14 are valve bodies that open and close the opening 11 of the lower diaphragm 9 and the through hole 8 of the partition wall 7;
These valve bodies 13 and 14 are provided at both ends of a valve shaft 15 that passes through the through hole 8 and are integrally connected to each other to constitute a plunger valve, and are arranged in the output chamber 4. bias spring 1
6, it is normally biased in the closing direction (upward in the figure). In the figure, Psup is the supply air pressure introduced into the supply pressure chamber 3 through the intake port 17, and Pin is the nozzle flapper mechanism of a pneumatic instrument, etc., which is introduced into the input chamber 6 through the input port 18. Air pressure input such as nozzle back pressure obtained by
Pout is the air pressure output output from the output chamber 4 through the output port 19, and Pa is the atmospheric pressure at which the exhaust port 5a of the atmospheric communication chamber 5 is open.

In such a configuration, when the air pressure input Pin input to the input chamber 6 increases, the upper diaphragm 10 is pressed downward, which causes the lower diaphragm 9 to descend via the cylinder 12, and as a result, the opening is closed. The exhaust valve constituted by the valve seat 11a on the side edge of the partition wall 7 and the seating portion 13a of the valve body 13 is closed, while the valve seat 8a on the side edge of the through hole 8 of the partition wall 7 and the valve body 14 are closed. The intake valve constituted by the seating portion 14a is opened, and the supply air pressure Psup is outputted as the air pressure output Pout via the supply pressure chamber 6 and the output chamber 5.

Further, when the air pressure input Pin to the input chamber 6 is reduced, the upper diaphragm 10 returns upward, and furthermore, the valve body 13 constituting the plunger valve,
14 is moved upward by the urging force of the bias spring 16, the aforementioned intake valve is closed, and the exhaust valve is opened, and the air pressure on the output port 19 side of this pilot relay passes through this exhaust valve and is released to the atmosphere. As a result, the air pressure output Pout is also reduced. Therefore, in the non-bleed type pilot relay 1 having such a configuration, it is possible to obtain a pneumatic pressure output Pout proportional to the pneumatic pressure input Pin.

[Problem that the invention seeks to solve]

By the way, while this type of conventional non-bleed type pilot relay 1 has the advantages of a simple structure, low air consumption, and large supply and exhaust capacity, the above-mentioned supply pressure chamber 3 , corresponds to the air pressure input Pin by the pressure difference between the supply air pressure Psup that acts on the valve body 14 from both sides when the intake valve that opens and closes the output chamber 4 is closed and when the valve is opened, and the air pressure output Pout. The opening of the valve,
A force that prevents the valve from closing acts, and as a result, in the flow rate characteristics due to supply and exhaust capacity and pneumatic output shown in Figure 2 a and b, and the pressure characteristics due to air pressure input and pneumatic pressure output, the broken line in the figure changes. As is clear from the characteristic curves shown, dead spots δ and dead bands ε occur where it is not possible to obtain pneumatic output Pout proportional to supply and exhaust capacity QS and QE, and pneumatic output Pout proportional to pneumatic input Pin. .

To explain this in detail, in FIG. 4, the opening area of the through hole 8 formed in the internal partition wall 7 is A _S ,
The diameter of the valve stem 15 is A _P , and the atmospheric communication chamber 5
The opening area of the opening 11 communicating with the side is Ae,
When the valve body 14 is seated on the seating part 14a at equilibrium, the force F acting on the valve body 14 due to the pressure difference is F=A _S · Ps - (A _S - A _P ) Po + ( Ae−A _P ) Po+kxo=A _S・Ps−(A _S −Ae) Po+kxo However, Ps is the supply air pressure Psup Po is the air pressure output Pout xo is the shift from the free length of the bias spring 16 k is the spring constant Here, Ae is designed to be approximately equal to (A _S − A _P ) in order to balance the supply capacity and exhaust capacity. Therefore, the above-mentioned formula is: F= _AS ·Ps−A _P ·Po+kxo (1) Note that kxo is small enough to be ignored.

The dead spot ΔP in FIG. 2a mentioned above is given by ΔP=F/Ao (2). Here, Ao is the effective area of the lower diaphragm 9 in the case of flow rate characteristics (the upper diaphragm 10 side in the case of pressure characteristics).

From equations (1) and (2) above, ΔP=(A _S・Ps−A _P・Po)/Ao...(3) is derived.

When Po changes in the range of 0 to Ps in equation (1) above, equation (1) consists of a term proportional to Ps and a term proportional to Po, so F and Pout in Figure 3 As shown by the broken line in the figure, the characteristics of F
As a result, dead spots δ and dead bands ε were generated over large ranges as shown in FIGS. 2a and 2b.

Therefore, when a non-bleed type pilot relay 1 that generates dead spots δ and dead bands ε over such a large range is used to construct a feedback control loop for a pneumatic instrument, the presence of the dead spots and dead bands of the pilot relay 1 causes It is unavoidable that the operation of the entire system tends to become unstable and its operation is unreliable, and it is necessary to take some measures to solve these problems.

[Means to solve the problem]

In order to meet such demands, the non-bleed type pilot relay according to the present invention has plunger valves that control the opening and closing of the pneumatic passage formed inside the relay, which are arranged at predetermined intervals on a valve shaft having the same diameter. The valve body is composed of two valve bodies, each facing the valve seat on the side edge of the through hole of the internal partition wall, which is formed with the same opening area to form a double seat structure. This is what I did.

[Effect]

According to the present invention, problems caused by pressure differences from both sides of a plunger valve, that is, forces in a direction that impede valve operation, can be prevented by installing two valve bodies and a through hole with an equal opening area that is opened and closed by the valve bodies in parallel. This essentially eliminates the problem of flow rate and
Dead spots, which had been considered a problem in terms of pressure characteristics,
It has become possible to eliminate the dead band and improve operational reliability, making it possible to take advantage of the original features such as low air consumption and large supply and exhaust capacity. It is what it is.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

Fig. 1 shows an embodiment of a non-bleed type pilot relay according to the present invention, and in the figure, the same or corresponding parts as in Fig. 3 described above are given the same numbers and their explanations are omitted. do.

Now, according to the present invention, in the non-bleed type pilot relay 1 having the above-described configuration, a pressure chamber 3 is formed between the supply pressure chamber 3 into which the supply air pressure Psup is introduced and the output chamber 4 from which the air pressure output Pout is derived. As the intake valve 20 using a plunger valve, a second intake valve 20B consisting of another valve body 21 and a valve seat (22a) is newly added, and this intake valve 20 (20A, 20B) has a double seat structure. It is characterized by the fact that it is made to do so.

That is, in this embodiment, the air pressure passages (3, 4) that connect the air intake port 17 and the output port 19 are newly connected to the air intake port 17 side from the supply pressure chamber 3 to the output port 1.
Output chamber 23 and second pneumatic passage 24 leading to 9
, and a second through hole 22 having an opening area equal to that of the through hole 8 is connected to the second internal partition wall 25 provided opposite the internal partition wall 7 midway through the through hole 8 . A valve shaft 15 is formed so as to be located coaxially with the plunger valve, and has a side edge thereof as a valve seat 22a, and a second valve body 21 opposite thereto, which is formed to have the same diameter as the plunger valve. It is arranged in parallel with the valve body 14 on the top.

Here, what should be noted is that the above-mentioned intake valve 2
By setting the opening area (AS1 = AS2) of each port (through hole 8, 22) constituting 0 (20A, 20b) to be equal, the conventional problems of dead spots and dead bands are eliminated, and the second This results in the flow rate and pressure characteristics shown by the solid lines in Figures a and b.

To explain this in detail, in FIG. 1, the opening areas of the through holes 8, 22 formed in the internal partition walls 7, 25 are AS1, AS2, and the diameter dimension of each valve shaft 15 facing the inside thereof is A _P1 , A _P2 , and the opening area of the opening 11 communicating with the atmosphere communication chamber 5 side is Ae, and when the valve bodies 14 and 22 are in equilibrium, the seating parts 14a and 2
2a, when the valve body 14, 2
2, the force F that acts to prevent valve operation due to the pressure difference on both sides is F = (A _S1 − Ap2) Ps − (A _S2 − A _P2 ) Ps + A _S2・Po + (A
e−A _P1 )Po−(A _S1 −A _P1 ) Po+kxo=(A _S1 −A _S2 )Ps+(A _S2 −A _S1 +Ae)P
o＋kxo……(4).

Now, as mentioned above, since the diameter dimensions of the valve stems 15 are equal, if A _S1 =A _S2 , then F=O.Ps+Ae.Po (5).

Here, assuming that the supply and exhaust capacities are the same as those of the conventional example shown in Fig. 4, and that the supply and exhaust are balanced, A _S1 and A _S2 are (1/2)・A _S , and Ae is the conventional example. and A _P1 , A _P2 {hereinafter referred to as A _P1 }
It is necessary to set (1/2)・A _P.

Considering these conditions and converting the above equation (5), F=0・Ps+2(A _S1 −A _P1 ) Po=0・Ps+2 {(1/2)・A _S −(1/2)・A _P }Po =0・Ps+(A _S −A _P )Po ...(6), and this equation (6) has only a term proportional to Po, and is different from equation (1) explained in the conventional example above. is different, and there is no term proportional to Ps.

Therefore, according to the present invention, in the above-mentioned equation (6), the characteristics of F and Pout shown in FIG. When changing within the range, F is sufficiently smaller than that of the conventional example shown by the broken line in the same figure (same when Po is equal to Ps), and the dead spot δ and dead band ε are reduced compared to the conventional example. is possible. This will become clear from the comparison between the conventional example shown in broken lines and the inventive example shown in solid lines in FIGS. 2a and 2b.

According to the configuration using the intake valves 20 (20A, 20B) with such a double seat structure, it is possible to reduce as much as possible the dead spots and dead bands that have been a problem in the past.
This minimizes the force acting on the plunger valve as a whole that would disturb valve operation, ensures the most appropriate valve opening/closing operation possible, and improves operational reliability. It is possible to demonstrate performance.

Note that the present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each part may be modified and changed as appropriate.

〔Effect of the invention〕

As explained above, according to the non-bleed type pilot relay according to the present invention, the plunger valves for controlling the opening and closing of the pneumatic passage formed inside the relay are arranged in parallel at a predetermined interval on the valve shafts having the same diameter. It is composed of two valve bodies, and these are arranged opposite to the valve seats on the side edges of the through-hole of the internal partition wall, which are formed with the same opening area and have a double seat structure. Despite its simple and inexpensive configuration, it has reduced the dead spots and dead bands that were problematic in terms of flow rate and pressure characteristics in conventional valve devices, and the plunger valve, which had been problematic in operation, has been improved in response to input. It is possible to operate smoothly and stably, and this makes it possible to take advantage of the original characteristics of low air consumption and large supply and exhaust capacity, which has various advantages. It has a positive effect.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view showing an embodiment of a non-bleed type pilot relay according to the present invention, and Figs. 2 a and b show flow characteristics of supply and exhaust capacities and pneumatic output, and pressures of pneumatic input and pneumatic output. Figure 3 is a characteristic diagram showing the characteristics in comparison with the conventional example, Figure 3 is a characteristic diagram showing the relationship between the force acting on the valve body and the valve output in comparison with the conventional example, and Figure 4 is a schematic sectional view showing the conventional example. be. 1...Non-bleed type pilot relay, 2...
... Valve body, 3 ... Supply pressure chamber, 4 ... Output chamber, 5
...Atmosphere communication chamber, 6...Input chamber, 7...First internal partition wall, 8...Through hole, 8a...First valve seat,
9, 10...Diaphragm, 11...Exhaust side opening, 12...Cylinder body, 13, 14...Valve body (plunger valve), 15...Valve stem, 16...Bias spring, 17...Intake port, 18...Input port, 19
... Output port, 20 (20A, 20B) ... Intake valve, 21 ... Second valve body, 22 ... Second through hole, 22a ... Second valve seat, 23 ... Second output Chamber, 24... second pneumatic passage, 25... second internal partition wall.

Claims (1)

[Claims] 1. A plunger valve is installed inside the valve seat and has a valve body seated on the side edge of a through hole in an internal partition wall provided in the middle of a pneumatic passage that communicates an intake port and an output port. In a non-bleed type pilot relay in which a pressure corresponding to an input acting on a head portion is used as an acting force for opening and closing a valve, a second pneumatic passage is provided from the intake port side of the pneumatic passage to the output port, and A second through hole having an opening area equal to that of the through hole is formed in a second internal partition wall provided halfway there to face the internal partition wall so as to be located coaxially with the through hole. A non-bleed type pilot, characterized in that a second valve body whose side edge serves as a valve seat is provided on a valve shaft having the same diameter as the plunger valve, in parallel with the valve body. relay.