JP2553398B2 - Valve drive mechanism - Google Patents

Description

The present invention relates to a valve mechanism for precisely and automatically controlling the mass flow rate of a fluid.

(B) Conventional technology As shown in the sectional side view of FIG. 5, the valve mechanism for precisely and automatically controlling the mass flow rate of various fluids used in the manufacture of conventional VLSIs has a valve unit 11 and a drive unit. It consists of 51.

The valve portion 11 is a fluid inlet port on one wall of the valve housing 12.
13 and outlet 14 are provided, and the fluid flow rate from the inlet 13 is PCTFE
By vertically moving the valve body 15 made of (polychlorofluoroethylene), the fluid seal portion 16 is opened and closed for control. That is, the valve body 15 is a flat plug. The valve body 15 is pushed up by the spring 17, and the protrusion 18 of the valve body 15 causes the valve diaphragm to move.
It has a mechanism that pushes up the center of 19. Valve housing
12, The valve diaphragm 19 and the inlet and outlet pipes are all made of SUS-316 (stainless steel) so that they can be used safely even with corrosive gases such as fluorine compounds and chlorine compounds. In addition, the valve body 15 is PCTFE,
The valve seat (valve housing) is made of SUS-316 to prevent the generation of particulate dust.

As shown in 51, a piezo driver is used as a drive unit for inducing the vertical movement of the valve body 15. In this case, piezo elements 52, 52, 52 in which a large number of thin piezoelectric elements such as barium titanate are laminated are stacked inside a case 53, and a lower end is sandwiched by a valve pushing piece 54 and an upper end is sandwiched by an adjusting piece 55.

When the mounting seat 56 of the piezo driver 51 and the valve housing 12 are fixed, the maximum DC voltage is applied to the piezo elements 52, 52, 52 to extend them and the push screw 57 is screwed in, and the adjusting piece is inserted via the ball 58. 55, piezo element 52, 52, 52 The valve pushing piece 54 is pushed down, and the tip 59 of the valve pushing piece 54 pushes the central portion of the valve diaphragm 19, so that the valve diaphragm
19 is displaced by δ ₀ , and the valve body 15 is
Close. δ ₀ is at most 0.1 mm.

In this state, if the DC voltage applied to the piezo elements 52, 52, 52 is reduced, the valve body 15 is pushed up by the restoring force of the valve diaphragm 19 and the spring 17, the fluid seal portion 16 opens, and the fluid enters the inlet 13 Exit to exit 14.
Then, the mass flow rate of the outflow fluid is detected by a sensor (not shown), the detected mass flow rate output signal is compared with the flow rate setting signal, and the piezo element 5
The mass flow rate of the fluid can be automatically controlled by automatically controlling the voltage applied to 2, 52 and 52.

(C) INVENTION A problem to be solved piezoelectric element 52,52,52 is longitudinal Suchiinesu s _p =
Even if the tensile or compressive force / displacement is abnormally large, for example, even if the applied voltage is increased to several hundred volt, the displacement is as small as about 0.05 mm, and the force generated when the movement is restricted becomes 100 kg or more. That is, ^{_{s p> 2 × 10 3 kg}} / mm.

Therefore, there is a drawback that the opening of the fluid seal portion 16 is small and the upper limit of the mass flow rate of the fluid that can be controlled is too small.

Further, when the push screw 57 is screwed in and the valve body 15 closes the fluid seal portion 16 to stop the outflow of fluid, the force for pressing the valve body 15 against the fluid seal portion 16 (details will be described later) is about 5 kgf. , Then the piezo elements 52, 52,
The variation Δξ of the length of 52 is s _p ≒ 2 × 10 ³ kgf / mm, and Δ
ξ≈5 / 2 × 10 ³ = 2.5 × 10 ^-3 mm. That is, the amount of adjustment of the push screw 57 is very small, which makes it difficult to adjust.

(D) Means for Solving the Problems The present invention has been made to eliminate the above-mentioned drawbacks.
The feature is that a flat plug valve is used as a valve for controlling the mass flow rate of a fluid, and the outer circumference of a solenoid diaphragm 28 made of a material having high strength and high toughness is attached to the protruding cylindrical portion 29 of a yoke 26 made of a soft magnetic material. And ring 30 and clamp with machine screw 31, solenoid diaphragm
The inner periphery of 28 is sandwiched between a plunger 24 made of a soft magnetic material and a clamp ring 32, clamped by a nut 33 to hold the plunger 24 on the yoke 26, and a guide pin 36 made of a non-magnetic material is fixed on the plunger 24. The magnetic pole 27 made of a soft magnetic material is allowed to slide in a bearing 37 embedded in the magnetic pole 27, and the magnetic pole 27 is made of a soft magnetic material so that the gap length δ ₂ of a magnetic gap 41 between the magnetic pole 27 and the plunger 24 can be adjusted. The solenoid portion 22 is constituted by the coil 43 fixed to the coil 25 and wound around the plunger 24. Thus, the solenoid portion 22 is housed in the case 23 made of a soft magnetic material via the corrugated washer 44, and the position of the solenoid portion 22 in the case 23 can be adjusted by the ring screw 45. It is in.

(E) Action The annular diaphragm that supports the plunger changes the stiffness in the direction of straight movement of the plunger by changing the size of its inner diameter and its thickness while supporting and clamping it.
Sd = force to move the plunger / displacement can be set in a considerably high range. Therefore, the stiffness of the magnetic attraction force when the magnetic air gap of the linear solenoid is near zero is Sm = magnetic attraction force /
Since it is possible to provide an annular diaphragm that is large with respect to the magnetic gap length and smaller than the stiffness Sp of the piezo drive unit, the mass flow rate of the fluid can be reduced by increasing or decreasing the power supplied to the linear solenoid. More control is possible.

Further, since the stiffness S _{d in the} direction of straight movement of the plunger can be made sufficiently smaller than the stiffness s _p of the piezo drive unit, the valve main body 15 for stopping the outflow of fluid is fixed to the fluid seal unit 16.
Even if the pressing force is the same, the adjustment amount of the ring screw 45 is large, so the adjustment can be done easily.

(F) Examples The drawings will be described in detail below.

FIG. 1 is a side sectional view showing an embodiment of a rectilinear solenoid used as a drive unit of the present invention, and FIG. 2 is a side sectional view showing a state in which the drive unit and the valve unit are connected in FIG.

In FIG. 1, reference numeral 21 is a linear solenoid used as a drive unit of the present invention, which is composed of a solenoid unit 22, a case 23 made of a soft magnetic material, a wave washer 44, and a ring screw 45.

Reference numeral 24 is a plunger made of a soft magnetic material, 25 and 26 are yokes made of a soft magnetic material, and 27 is a magnetic pole made of a soft magnetic material that attracts the plunger 24. 28 is, for example, nickel, cobalt, chrome, molybdenum steel (9% Ni, 9% Co, 8% Cr, 4%
Mo, 0.1% Al, 0.4% T _s , 0.01% C balance F ₀ ) was age hardened in air or hydrogen at 480 ° C. for 5 hours to obtain a high strength, high toughness material with a thin thickness t. A solenoid diaphragm is used to cover the outer periphery of the solenoid diaphragm with the protruding cylindrical portion 29 of the yoke 26 and the ring 30.
2a is the outer diameter of the clamp. Further, the inner circumference of the solenoid diaphragm 28 is sandwiched between the plunger 24 and the clamp ring 32, and the nut 33 is screwed into the tip screw portion 34 of the plunger 24 and clamped. 2b is the clamp inner diameter. Thus, the plunger 24 is held at the center, and a magnetic gap 35 is formed between the plunger 24 and the yoke 26. 36
Is fixed to the upper part of the plunger 24 by a guide pin made of a non-magnetic material, and slides in the bearing 37 embedded in the magnetic pole 27. Therefore, the displacement of the plunger 24 is limited only in the vertical direction by the solenoid diaphragm 28 and the guide pin 36. 38 is a thin spacer, which is sandwiched between the yoke 25 and the collar 39 of the magnetic pole 27, and is tightened with a small screw 40. By adjusting the thickness of the spacer 38, the air gap length δ of the magnetic air gap 41 can be adjusted. As a method of adjusting the air gap length δ, although not shown, a structure in which the magnetic pole 27 is screwed into the yoke 25 is also possible. 42 is a bobbin made of insulating material, 43 is a bobbin
A coil wound around the plunger 24 around 42. The solenoid portion 22 is configured as described above.

44 is a corrugated washer, 45 is a ring screw, ring screw
By screwing 45, the solenoid portion 22 deforms the wave washer 44 and is fixed inside the case 23.

46 is a lower protruding portion of the plunger 24, 47 is a mounting seat of the drive unit 21, and 48 is a bottom surface of the mounting seat 47.

FIG. 2 is a side sectional view showing a state in which the valve portion 11 and the driving portion 21 are connected to each other, and 11 to 19 are the same as FIG. 5 and 21 to 48 are the same as FIG.

The valve body 15 has a central part of the valve diaphragm 19 of δ _0.
The fluid seal portion 16 is configured to close when only pushed down.

Is about 0.1 mm at most, but the valve diaphragm 19 is SUS
Since is made of -316 to the strength of SUS-316 as low as about 21 kgf / mm ^2, a variation of this degree, the internal stress of the valve diaphragm 19 exceeds the proportional limit, it would fall within the scope of the plastic deformation . That is, the restoring force of the valve diaphragm 19 must be regarded as non-existent.

The force that pushes up the valve body 15 is given by the spring 17. The spring 17 must also push up the valve body 15 even when the inlet fluid is nearly empty,
Let this power be Fo. On the other hand, when the inlet fluid pressure is p atmosphere, if the force of Fp is required to keep the fluid seal portion 16 closed, the valve body 15 must be constantly pressed with the force of (F ₀ + F _p + α). I have to. The force of (F ₀ + F _p + α) is
The solenoid diaphragm 28 is generated by deforming by δ ₁ as shown in FIG. One of the methods is to drive 21
The mounting seat 47 and the valve housing 12 are fixed to each other, the inlet fluid pressure is set to (p + Δp) atmospheric pressure, the ring screw 45 is screwed in, and the solenoid portion 22 is pushed downward, so that the fluid does not flow out from the fluid outlet 14. Be carried out by checking.

The gap length δ ₂ of the magnetic gap 41 is adjusted to δ ₂ ≈δ ₀ by adjusting the thickness of the spacer 38.

3 and 4 are diagrams for explaining the operation of the valve drive mechanism of the present invention.

The solid line in FIG. 3 is an actual measurement example of F _M measured with the DC applied voltage V _c to the coil 43 as a parameter, the magnetic attraction force F _M of the plunger 24 on the vertical axis, and the air gap length δ of the magnetic air gap 41 on the horizontal axis. is there.

Fig. 4 shows that the outside of the solenoid 22 is fixed and the plunger
In this example, the displacement ξ of the plunger diaphragm 28 when a pushing force Fd is applied to the tip 46 of 24 is plotted on the horizontal axis and Fd is plotted on the vertical axis.

The dotted line in Fig. 3 is a plot of the measured values in Fig. 4 with the displacement directions reversed so that F _{Mo in} Fig. 3 and F _{do in} Fig. 4 are equal.

Δ _{1 on the} plunger diaphragm 28 in FIGS. 3 and 4.
To give the displacement of, the force of (F ₀ + F _p + α)
Must be added to the tip 46 of 24. That is, the valve body 15
Means that the fluid seal portion 16 is pressed by the force of (F ₀ + F _d + α).

If the voltage applied to the coil 43 is V _c1 or less, the plunger 24
Is stationary, but the force that deforms the plunger diaphragm 28 when the applied voltage is increased like V _c1 , V _c2 , V _c3.
The balance point between F _d and the magnetic attraction force F _M moves in the order of A, B, and C, the valve body 15 is pushed up by the spring 17, the fluid seal portion 16 is sequentially opened, and the fluid is at the inlet 13 or the outlet.
Spill to 14. Then, the mass flow rate of the outflowing fluid is detected by a sensor (not shown), the detected mass flow rate output signal is compared with the flow rate setting signal, and the applied voltage to the coil 43 is automatically controlled so that they match each other. Then, the mass flow rate of the fluid can be automatically controlled.

The bottom surface 48 of the case mounting seat 47 is flat.
This is because even if the inlet fluid pressure accidentally rises above the specified value, the valve diaphragm 19 is supported by the bottom surface 48 and does not cause unnecessary deformation.

(G) Effect Although the drawings have been described in detail above, the necessary and sufficient conditions for automatically controlling the fluid flow rate with the valve drive mechanism according to the present invention are as follows.

(1) The magnetic attraction force when the gap length δ of the magnetic gap 41 is zero due to the specified DC input power is F _Mo or more in FIG.

(2) The stiffness sd of the plunger diaphragm 28 is
Greater than the magnetic attraction force stiffness sm.

(3) The internal stress of the plunger diaphragm 28 is within the proportional limit of the material.

The condition (1) can be satisfied depending on the size of the solenoid.

The conditions (2) and (3) can be satisfied by the plunger diaphragm 28 of the present invention, that is, the annular diaphragm.

That is, the stiffener sd of the annular diaphragm and the maximum value σ _max of the internal stress are, for example, by S.TIMOSHENKO, Kenma Kitabatake,
According to Kentaro Katayama, “Material Mechanics,” Vol. 2, P106 Corona Publishing, Eq. (1) and Eq. (2) are given, where E is the Young's modulus of the material, v is the Basson's ratio, and y = b / a.

When load P is applied, σ _max occurs in the circumference In equation (1) sd, the displacement ξ of the annular diaphragm is the thickness t
However, when it is about the same or more, it gradually increases. Therefore σ
_max also becomes larger than the value shown in equation (2), but since there are three types of degrees of freedom that determine the annular diaphragm, a, t, and y, sd is larger than sm and σ _max is within the proportional limit value of the material. It is easy to stop at.

The values of sm and sd according to the examples were as in equation (3).

In addition, the proportional limit value after age hardening of the material of the plunger diaphragm 28, nickel, cobalt, chrome, and molybdenum steel is very large at 200 kgf / mm ² or more, and the plunger diaphragm 28 is displaced to twice the usage limit, and it is tens of tens. No permanent set was observed even after repeated cycles.

The value of equation (3) sd≈33 kgf / mm is sufficiently smaller than the stiffness of the piezo element sp> 2000 kgf / mm, so the movement of the valve body 15 can be made larger than the conventional one. There is an effect that the upper limit of the mass flow rate of the fluid can be increased.

Since sd = 33 kgf / mm, assuming that the force (F _o + F _p + α) that presses the valve body 15 that stops the outflow of fluid against the fluid seal portion 16 is approximately 5 kgf, the displacement δ _{1 of the} solenoid diaphragm 28 Becomes as large as δ ₁ ≅5 / 33 ≅0.15 mm, which has the effect of facilitating adjustment by the ring screw 45.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a rectilinear solenoid used as a valve drive unit of the present invention, and FIG. 2 is a valve unit.
11 is a side sectional view showing a state in which 11 and the driving portion 21 are combined, FIGS. 3 and 4 are views for explaining the operation of the valve driving mechanism of the present invention, and FIG. is there. 11 ... Valve section, 12 ... Valve housing, 13 ... Fluid inlet, 14 ... Fluid outlet, 15 ... Valve main body, 16 ... Fluid seal section, 17 ... Spring, 18 ... Protrusion of valve main body 15, 19 ... Valve diaphragm, 20 ... Drive part, 22 ... Solenoid part, 23 ... Case,
24 ... Plunger, 25, 26 ... Yoke, 27 ... Magnetic pole, 28 ... Plunger diaphragm, 29 ... Projecting cylindrical portion of yoke 26, 30 ...
Ring, 31 ... Machine screw, 32 ... Clamp ring, 33 ... Nut, 34 ... Plunger 24 tip screw part, 35 ... Magnetic gap, 36
... guide pin, 37 ... bearing, 38 ... spacer, 39 ... collar 27 collar, 40 ... machine screw, 41 ... magnetic air gap, 42 ... bobbin, 43 ... coil, 44 ... corrugated washer, 45 ... ring screw, 46 ... plunger Tip, 47 ... Mounting seat for drive unit 21, 48 ... Bottom surface of mounting seat 47
51 ... Piezo driver, 52, 52, 52 ... Piezo element, 53 ... Case, 54 ... Valve pushing piece, 55 ... Adjusting piece, 56 ... Case mounting seat, 57 ... Push screw, 58 ... Ball, 59 ... Valve pushing piece 54 tips

Claims (1)

(57) [Claims] 1. A valve for controlling a mass flow rate of a fluid,
Using a flat plug valve, the outer circumference of the solenoid diaphragm 28 made of a material with high strength and high toughness is sandwiched between the protruding cylindrical portion 29 of the yoke 26 made of soft magnetic material and the ring 30, and a small screw
Clamp with 31 and sandwich the inner circumference of solenoid diaphragm 28 with plunger 24 and clamp ring 32 made of soft magnetic material and clamp with nut 33 to hold plunger 24 on yoke 26. Is fixed so that it can slide in the bearing 37 embedded in the magnetic pole 27 made of a soft magnetic material.
Solenoid portion 22 that is fixed to a yoke 25 made of a soft magnetic material so as to adjust the air gap length δ ₂ of the magnetic air gap 41 between the solenoid air gap 24 and a coil 43 wound around the plunger 24. The corrugated washer is placed in the case 23 made of soft magnetic material.
The valve drive mechanism is characterized in that the valve drive mechanism is configured to be housed via a valve 44, and the position of the solenoid portion 22 in the case 23 can be adjusted by a ring screw 45.