JP2740342B2 - Flow control valve and mass flow controller for high temperature range and laminated displacement element for high temperature range - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control valve frequently used for precisely controlling a gas flow rate in, for example, a semiconductor industry, and particularly relates to a drive source for a stacked displacement element. The present invention relates to a flow control valve and a mass flow controller for a high temperature range suitable for use in a temperature range higher than room temperature, and a stacked displacement element for a high temperature range suitable for these uses.

[Conventional technology]

2. Description of the Related Art As a conventional flow control valve using a laminated displacement element as a drive source, for example, there is a flow control valve disclosed in Japanese Patent Application Laid-Open No. 61-127983.

FIG. 9 is a longitudinal sectional view of a main part showing an example of the flow control valve, which is a so-called normally open type. In FIG. 9, reference numeral 11 denotes a main body, which is formed in a block shape from a structural material such as stainless steel and has a valve chamber 12 which opens upward, an inflow channel 13 and an outflow channel which communicate with the valve chamber 12. Provided at 14. 15 is a valve seat,
A valve port 16 is provided below the valve chamber 12 and communicates with the outflow channel 14. Next, reference numeral 17 denotes a diaphragm, which is formed of a metal material in a thin plate shape, is provided so as to seal the upper part of the valve chamber 12, and a valve body 18 is integrally fixed to the lower surface thereof so as to face the valve port 16. Next, reference numeral 19 denotes a housing, which is formed of a material similar to that of the main body 11 into a hollow cylindrical shape, and is fixed above the main body 11 via a presser foot 20 so as to seal the valve chamber 12. 21 is a laminated displacement element having a valve stem at the lower end.
22 is fixed with an adhesive or the like, and the valve stem 22 is mounted in the housing 19 so as to contact the diaphragm 17 or
Alternatively, it is mounted in the housing 19 so that the valve stem 22 is fixed to the diaphragm 17 using an adhesive or the like. Reference numeral 23 denotes an opening adjusting screw which is screwed to the upper end of the housing 19 so that the lower end thereof comes into contact with the laminated displacement element 21.

With the above configuration, a predetermined gap is secured between the valve seat 15 and the valve element 18. Therefore, fluid such as gas flows from the inflow channel 13 to the outflow channel 14 through the valve chamber 21 and the valve port 16. Flows. Next, when a DC voltage is applied to the laminated displacement element 21, it expands in the laminating direction. Therefore, the valve stem 22 is pushed down, and the valve element 18 is further displaced downward. As a result, the gap between the valve element 18 and the valve seat 15, that is, the opening of the valve port 16 is reduced. On the other hand, when the DC voltage applied to the multilayer displacement element 21 is removed, the multilayer displacement element 21 contracts by the extension due to the voltage application. Therefore, the valve element 18 returns to the original position by the restoring force of the diaphragm 17, and the opening of the valve port 16 also returns to the original state. As described above, the opening of the valve port 16 can be adjusted by the DC voltage applied to the laminated displacement element 21, and as a result, the flow rate of the fluid such as gas from the outflow passage 14 can be controlled. is there.

Next, the laminated displacement element used in the flow control valve will be described.

Recently, as a stacked displacement element, for example, Japanese Patent Publication No. 59-32040
As described in the official gazette, a binder is added to the raw material powder,
A kneaded paste-like piezoelectric ceramic material is formed into a thin plate having a predetermined thickness, and a conductive material such as silver-palladium is applied to one or both surfaces of the thin plate to form internal electrodes. A multilayer chip capacitor structure type in which a plurality of sheets are laminated, pressure-bonded, processed into a predetermined shape, and then fired to be ceramicized, and external electrodes are formed on both side surfaces of the laminate has been put to practical use. The stacked displacement element having the above-described configuration has advantages such as excellent adhesion between a thin plate made of a piezoelectric ceramic material and an internal electrode, and extremely little deterioration over a long period of time.

FIG. 10 shows an example of the configuration of the above-mentioned stacked displacement element, which is called a so-called alternating electrode type. In Fig. 10, 31
Is a thin plate, made of a piezoelectric ceramic material, and laminated by alternately sandwiching positive and negative internal electrodes 32a and 32b.
To form The internal electrodes 32a and 32b are formed so that one edge portion protrudes or is exposed to the outside. The internal electrodes 32a and 32b are connected to the external electrodes 33a and 33b, respectively, extending in the laminating direction. Connecting.

With the above configuration, when positive and negative voltages are applied to the external electrodes 33a and 33b, an electric field is generated between the internal electrodes 32a and 32b,
The thin plate 31 is displaced by extending in the thickness direction due to the longitudinal effect of the piezoelectric ceramic material.

Next, what is shown in FIG. 11 is another example of a laminated displacement element, which is a so-called full-surface electrode type in which the piezoelectric displacement efficiency is improved (for example, see Japanese Patent Application Laid-Open No. 58-196068). .
In FIG. 11, the same parts are denoted by the same reference numerals as in FIG. 10, but the internal electrodes 32a and 32b are formed so as to cover the entire surface of the thin plate 31, and the required number of sheets are laminated in the same manner as described above. Next, on one side surface of the laminated body 35 formed as described above, a coating 34 made of an insulating material is provided at every other edge (for example, only on the internal electrode 32b) at the edges of the internal electrodes 32a and 32b. External electrode 32a made of conductive material from above
Is adhered. On the other hand, on the other side surface of the laminate 35, the coating 34 is provided on the edge of the internal electrode (for example, 32a) where the coating 34 is not provided in the same manner as described above, and the external electrode 33b
Is applied. The operation of the above configuration is
The same as in FIG.

[Problems to be solved by the invention]

In the conventional flow control valve shown in FIG.
A valve element 18 exists in the valve chamber 12 through which gas flows.
Is configured to control the flow rate by moving into and out of a valve port 16 provided in a valve seat 15. The valve element 18 contacts the end of the valve port 16 when the gas flow is shut off, and slides on the end of the valve port 16 and the inner peripheral surface when controlling the flow rate.
There is a problem that metal powder generated by abrasion is mixed into the gas. Also, when the secondary side of the valve has a negative pressure, the inside of the valve chamber 12 also has a negative pressure at the same time, and the diaphragm 17 is pulled downward. As a result, when the valve stem 22 and the diaphragm 17 are fixed, a large tensile load is applied to the laminated displacement element 21. The laminated displacement element 21 is generally strong against a load in the compression direction, but weak against a load in the tension direction.
In such an embodiment, the durability is significantly deteriorated. Therefore, with the above structure, the life and reliability of the stacked displacement element 21 are reduced, and at the same time, the driving durability of the valve is also deteriorated. Although not shown, in the normally closed type flow control valve, the frequency of contact and sliding between the valve element 18 and the valve port 16 is much higher than that of the normally open type, so that the flow control valve may be worn. The amount of generated metal powder is also large, and the above problem becomes more serious.

In order to solve the above problem, the present applicant has already filed an application for a flow control valve in which the valve element 18 is omitted and the diaphragm 17 is formed so as to be able to be brought into and out of contact with the valve seat 15 (see, for example, Japanese Patent Application No. Hei 10-26138). No. 1-94492).

FIG. 1 is a longitudinal sectional view of a main part showing the flow control valve, and the same parts are denoted by the same reference numerals as in FIG. In FIG. 1, reference numeral 26 denotes a diaphragm retainer which is sandwiched between the housing 19 and the main body 11 to fix the diaphragm 17 thereto. A compression coil spring 27 is interposed between the valve stem 22 and the diaphragm retainer 26 so as to press the valve stem 22 upward.

With the above configuration, a predetermined distance is ensured between the valve seat 15 and the diaphragm 17, so that the inflow passage 13 is connected to the valve port 16.
The gas flows into the outflow channel 14 via the valve chamber 12. Then, when a DC voltage is applied to the laminated displacement element 21 so as to extend in the laminating direction, the central portion of the diaphragm 17 is pushed downward through the valve rod 22 against the repulsive force of the compression coil spring 27, and the diaphragm 17 is Since the distance from the valve seat 15 is reduced, that is, the opening of the valve port 16 is reduced, the gas flow rate can be reduced. When the voltage applied to the laminated displacement element 21 is released, the valve stem 22 returns to the original position by the restoring force of the compression coil spring 27, and the diaphragm 17 also returns to the original position.
According to this structure, the secondary side has a negative pressure and the diaphragm 17
Even if the force of pulling downward is increased, the compression coil spring 27 acts as a reaction force, and the tensile load on the laminated displacement element 21 is reduced, so that its life and reliability can be secured. Accordingly, the flow rate of the gas can be controlled in the same manner as in FIG.

1, the diaphragm 17 only comes into contact with and separates from the valve seat 15, and there is no sliding action between the two. Therefore, metal powder due to abrasion as shown in FIG. Since no gas is generated and the compression coil spring 27 is also provided outside the gas flow path, no metal powder is generated by its operation, and therefore, the metal powder does not mix with the gas.
However, the displacement amount of the laminated displacement element 21 used in the conventional flow control valve has a length of 40 in the lamination direction.
mm is only about 30 to 40 μm. Since the gas flow rate in this type of piezoelectric valve is determined by the gap size between the valve seat 15 and the diaphragm 17, only a very small flow rate can be secured depending on the displacement amount. Therefore, in order to realize a piezoelectric valve having a large flow rate, it is necessary to increase the number of laminations of the thin plates 31 and the internal electrodes 32a and 32b constituting the laminated displacement element 21, and the piezoelectric valve becomes inevitably large in size. There is a problem that the occupied space is increased. For this reason, the conventional piezoelectric valve is limited to a valve for a small flow rate, and is not suitable for a valve for a large flow rate. When used for a large flow rate or for a wide range of flow rate control, several piezoelectric valves are required, which not only increases the occupied space or the occupied floor area, but also causes maintenance, inspection and management. Is also complicated.

In recent years, in the field of semiconductor manufacturing, the use of a higher-purity, higher-temperature reaction gas has been studied, and therefore, it has been demanded that the equipment be able to withstand high temperatures.
However, when the above conventional flow control valve is used in a high temperature range, for example, 100 ° C or higher, a thin plate
Since the displacement and the capacitance of the electromechanical conversion material forming 31 greatly change with temperature, there is a problem that a predetermined function cannot be exhibited. That is, for example because the commonly used Curie temperature of the electromechanical conversion material (temperature at which loss of piezoelectric properties) is around 0.99 ° C., the piezoelectric strain constant d ₃₃ when the temperature of the element exceeds 100 ° C. decreases abruptly In addition, there is a problem that the amount of displacement is drastically reduced, and a predetermined amount of displacement cannot be secured. In particular, in recent years, the use of the flow control valve has been expanded to a high temperature range around 200 ° C, and stricter specifications than before have been required.
There is a strong demand for a flow control valve having a stable control function regardless of the specified ambient temperature.

Also, the external electrodes 33a, 33b
This leads to inconveniences such as poor conduction due to melting of the solder 37 connecting the lead 36 and the lead wire 36. Further, for example, in order to prevent dielectric breakdown and improve strength in a high-humidity atmosphere, a device provided with a coating made of an epoxy resin material (epoxy-aromatic diamine, polyamine, nylon, and aliphatic amine) on the surface of the device. In addition, there is a problem in that the film is melted or peeled off, thereby impairing the function of the element.

The present invention solves the above-mentioned problems in the prior art, and can secure characteristics such as displacement and capacitance to a predetermined level even at a high use atmosphere temperature, and have stability. It is another object of the present invention to provide a high-temperature range flow control valve having high reliability.

Another object of the present invention is to provide a mass flow controller using the above-mentioned high temperature range flow control valve.

The invention further holds a value of piezoelectric strain constant d ₃₃ becomes sufficiently large even when used in high temperature atmosphere, without causing a conduction failure and other disadvantages, for high-temperature range capable of stably generating a predetermined displacement An object is to provide a stacked displacement element.

[Means for solving the problem]

In order to achieve the above object, according to a first aspect of the present invention, there is provided a body provided with a valve chamber having an open end and an inflow channel and an outflow channel formed so that one end communicates with the valve chamber and the other end is opened. A valve seat provided at an end of the inflow passage or the outflow passage that communicates with the valve chamber; a thin diaphragm made of a metal material provided to seal an open end of the valve chamber; In a flow control valve having a housing arranged at an open end and a laminated displacement element provided in the housing, the laminated displacement element is composed of PbO 61 to 66% by weight, SrCO ₃ 2
_{~5%, TiO 2 10.5~12%,} ZrO 2 20~22%, Sb 2 O 3 0.1~2.0%
Consists of a composition, formed in a temperature range above 100 ° C. by an electromechanical converter material, such as a piezoelectric strain constant d ₃₃ is 645 × 10 ^-12 m / v or more of the maximum value, those of the diaphragm to said valve seat A technical means was adopted in which it is configured to be driven so that it can be freely connected and detached.

Next, in the second invention, the first electromechanical conversion material to the invention of the piezoelectric strain constant d ₃₃ is stacked displacement element at a temperature in a temperature region near to the maximum value of providing a heating means to operate, Technical means were added.

According to a third aspect of the present invention, a flow control valve for controlling a flow rate of a fluid, and a flow rate of the fluid flowing in a sensor flow path provided in a bypass manner in an inflow or outflow flow path of the flow control valve is detected. A mass flow controller having a flow sensor to be controlled and control means for controlling the flow control valve in accordance with the output of the flow sensor, wherein the flow control valve is connected to a valve chamber having an open end and one end to the valve chamber. A main body provided with an inflow channel and an outflow channel formed to have open ends, a valve seat provided at an end communicating with the valve chamber of the inflow channel or the outflow channel, and an open end of the valve chamber. A thin plate-shaped diaphragm made of a metal material provided so as to be hermetically sealed, a housing arranged at an opening end of a valve chamber of the main body,
A laminated displacement element is provided in the housing and presses the diaphragm toward the valve seat. The laminated displacement element is composed of PbO 61-66% by weight and SrC
_{O 3 2~5%, TiO 2 10.5~12} %, ZrO 2 20~22%, Sb 2 O 3 0.1~2.
Becomes 0% of the composition, at a temperature range above 100 ° C. to form the electromechanical transducer material, such as a piezoelectric strain constant d ₃₃ is 645 × 10 ^-12 m / v or more of the maximum value, the valve seat the diaphragm A technical means is adopted in which it is configured to be driven so as to be able to come into and out of contact with.

Further, in the fourth invention, a laminate is formed by alternately laminating a plurality of thin plates made of an electromechanical conversion material and internal electrodes made of a conductive material, and the internal electrode and one layer are formed on side surfaces of the laminate. In a laminated displacement element having a pair of external electrodes connected every other
By weight ratio, PbO 61-66%, SrCO ₃ 2-5%, TiO ₂ 10.5-12%, Z
_{rO 2 20~22%, Sb 2 O} 3 consists of 0.1% to 2.0% of the composition, a material of a piezoelectric strain constant d ₃₃ is 645 × 10 ^-12 m / v or more of the maximum value in the temperature range above 100 ° C. Technical means of doing so.

In the fifth invention, a technical means of providing a coating made of a heat-resistant insulating resin material on the surface of the laminate is added to the fourth invention.

In the sixth invention, the fourth invention or the fifth invention
In addition to the invention, the technical means of connecting a lead wire to an external electrode using a solder having a liquidus temperature of 200 ° C. or higher has been added.

(Operation)

With the above configuration, in the first to third aspects of the present invention, the diaphragm can be brought into and out of contact with the valve seat so that the flow rate can be controlled, and the flow control valve can be controlled even in a temperature range higher than room temperature. Alternatively, a predetermined function as a mass flow controller can be sufficiently exhibited.

Further, in the fourth to sixth aspects of the present invention, even in a temperature range higher than room temperature, stable operation is ensured while ensuring a predetermined displacement as a stacked displacement element without causing conduction failure and other inconveniences. You can do it.

〔Example〕

2 (a) to 2 (d) are perspective views each showing an example of a laminated body constituting the laminated displacement element according to the embodiment of the present invention. First, in FIG. 2A, the thin plate 31 is formed as follows. The raw material composed of PbO, SrCO ₃ , TiO ₂ , ZrO ₂ , and Sb ₂ O ₃ is the first such that Pb _x , Sr _1-x Zr _y Ti _1-y O ₃ + Zwt% Sb ₂ O ₃ in the chemical composition formula. Mix as shown in the table. No. 6 has been widely used as a piezoelectric material for multilayer displacement elements.
5Pb (Ni1 / 3Nb2 / 3) O ₃ -0.35PbTiO ₃ -0.15PbZrO ₃ is shown.

In general, a flow control valve is required to have a large displacement amount of a stacked displacement element as a driving source.
It is necessary that the piezoelectric strain constant d ₃₃ of the piezoelectric material used for this is the large therefore. Note piezoelectric constant d ₃₃ is calculated from the following equation.

In the above equation, the elastic compliance ＳS ^E ₃₃あ り is approximately 15 × 10 ^-12 m ² / N for piezoelectric ceramics, and the electromechanical coupling coefficient K ₃₃ is limited to about 0.6 to 0.7 for conventional materials. From the Curie temperature of normal piezoelectric ceramics
By lowering the tc, it was taken a means for increasing the piezoelectric strain constant d ₃₃ by increasing the ▼ dielectric constant ▲ epsilon ^E ₃₃ in the vicinity of room temperature.

After mixing the above raw materials in a ball mill for 24 hours,
Calcinate for hours. After pulverizing the calcined powder, polyvinyl butyral is added to the calcined powder, dispersed in trichlene to form a slurry, and this mixed material is formed into a thin sheet 31 having a thickness of 100 μm by a doctor blade method. Next, a platinum conductive paste or a silver-palladium paste for forming the internal electrodes 32a and 32b is screen-printed on the entire surface of the thin plate 31. The internal electrodes 32a formed as described above,
After alternately laminating, for example, 100 thin plates 31 each having 32b and crimping them, they are cut into a predetermined size and shape to form a laminate, debindered at 500 ° C, and 1 to 5 at 1050 to 1200 ° C in oxygen. After sintering for a time, the laminate is cut into a predetermined size to form a laminate 35.
The dimensions of the laminate 35 are, for example, 5 × 5 × 10 l (m) or 10 × 10 × 10 l (mm). Next, coatings 37a and 37b made of an insulating material are applied to adjacent side surfaces of the laminate
a, 32b. In FIG. 2 (b), 3
8a and 38b are grooves, for example, coated with a dicer or the like.
It is engraved at a position corresponding to the internal electrodes 32a and 32b of 37b. Second
In FIG. (C), external electrodes 33a and 33b are coated on coatings 37a and 37b.
If provided so as to cross the grooves 38a and 38b, the external electrodes 33
a, 33b and the internal electrodes 32a, 32b can be connected to each other. Next, the external electrodes 33a and 33b are connected to the voltage supply lead wires via solder (both not shown). The solder consists of a weight ratio of Sn25% and Pb75%, Use 260 ° C. Next, in FIG. 2 (d), reference numeral 39 denotes a film, and a polyimide resin is provided on the surface of the laminate 35 including external electrodes and solder (both not shown) by a flow dipping method or an electrostatic coating method. The results obtained by applying a polarization of 1.5 kV / mm to the laminated body 35 formed as described above and measuring the characteristics are also shown in the table. No. 6 relates to a comparative example, which is a laminate formed of a conventionally used material.

As is clear from the table, while the Curie temperature of the conventional material No. 6 is 145 ° C., the Pb _x Sr _{1 -x} Zr as shown in Nos. 1 to 5 of the piezoelectric material of the present invention. _y TiO _1-y O ₃
+ Zwt% Sb ₂ O ₃ system ones, since the electromechanical coupling coefficient K ₃₃ indicates an extremely large consisting value around 0.8, the Curie temperature Tc
It can be maintained at a relatively high temperature of 180 ° C or higher, and therefore can be used even in a high temperature range of 150 ° C or higher.

FIG. 3 is a diagram showing the relationship between the temperature and the generated displacement, and the numbers in the figure correspond to the numbers in the above table. Note displacement generated in FIG. 3 (proportional to the piezoelectric strain constant d ₃₃₎ is the applied voltage 1
It is for 50V. As is clear from FIG.
In No. 6, which is a comparative example, the generated displacement decreases with an increase in temperature, and the decrease sharply increases particularly when the temperature exceeds 100 ° C. On the other hand, in Nos. 1 to 5 corresponding to the present invention, the displacement (that is, the piezoelectric strain constant
d ₃₃₎ is increased, the piezoelectric strain constant d ₃₃ in the temperature range above 100 ° C. is shows a 645 × 10 ^-12 m / v or more of the maximum value, it can be operated by the generated displacement 13～15Myuemu.

When the laminate having the above-described structure was subjected to a driving test under a condition of 150 V and 10 Hz for 1000 hours in a high-temperature atmosphere of 150 ° C., the displacement generated in each of the 100 test pieces, the functional deterioration of the electromechanical conversion material, and the conduction were reduced. It was confirmed that there were no defects. On the other hand, when the laminated displacement element having the structure shown in FIGS. 10 and 11 is used for, for example, an actuator for a fluid control valve or an actuator for a fuel injection valve for an automobile used in a high-temperature atmosphere, the thin plate 31 is used. Deterioration of the function of the formed electromechanical conversion material occurs. This is because the piezoelectric strain constant sharply decreases as described above.

Next, four laminated bodies (5 × 5 × 10 l (mm)) were laminated via a polyimide adhesive to form a laminated displacement element having a length of 40 mm, and the flow control valve shown in FIG. The temperature dependence of the flow rate was measured. In this case using the N ₂ gas as the fluid, and the contact outer diameter of the diaphragm 17 of the valve seat 15 2.2 mm, the inner diameter of the valve port 16 and 2.0 mm. That is, first, a direct current of 150 V is applied to the laminated displacement element 21, and while the N ₂ gas is flowing (differential pressure: 3 kg / cm ² ), the opening adjustment screw 23 is screwed downward, and the diaphragm 17 is moved through the valve rod 22. It is brought into contact with the valve seat 15 and adjusted so that the flow rate of the N ₂ gas becomes zero. Next, when the application of the DC voltage to the multilayer displacement element 21 is released,
Since the compression coil spring 27 pushes up the valve rod 22 by the repulsive force, the diaphragm 17 is separated upward from the valve seat 15 and the valve port 16 is opened. At this time, the N ₂ gas flow rate shows the maximum value.

FIG. 4 is a diagram showing the relationship between the temperature and the maximum flow rate, and the numbers in the figure correspond to those in FIG.
As is clear from FIG. 4, the maximum flow rate increases with increasing temperature in all cases, and shows the maximum value in a high temperature region of 130 to 180 ° C. That is, the diaphragm shown in FIG.
17 shows that the stroke increases in the high temperature region. This is due to the large displacement of the laminated displacement element 21 and the maximum value in the high temperature region, and is due to the temperature dependence of the generated displacement shown in FIG. Such characteristics cannot be obtained at all using a conventional piezoelectric material, and the above characteristics are effective for a valve for controlling the flow rate of an organic metal gas. That is, since the organometallic gas has a high boiling point (for example, dimethylzinc 44 ° C, tetramethyltin 78 ° C, triethylgallium 142.6 ° C, etc.), it is necessary to heat and keep the supply piping system, and the flow control valve is necessarily high temperature Used in state.

FIG. 5 is a diagram showing the relationship between the temperature of the organometallic gas and the vapor pressure. The organic metal gas flows in the pipe by the vapor pressure, but as shown in FIG. 5, the vapor pressure of each organic metal gas increases depending on the temperature. As the vapor pressure increases, the gas flow rate also increases. However, in the conventional type in which the displacement tends to decrease as the temperature increases, for example, the stroke of the diaphragm 17 in FIG. Therefore, for example, a sufficient amount of gas cannot be supplied at the time of film formation by reduced pressure CVD or the like. As a result, there are problems that the film formation time becomes longer, mass production becomes difficult, and impurities may be mixed.

FIG. 6 is a configuration diagram of a main part showing another embodiment of the present invention, and is an example of a mass flow controller for controlling the above-mentioned organometallic gas. In FIG. 6, reference numeral 40 denotes a flow control valve, which has, for example, the configuration shown in FIG. 1, and a driving type laminated displacement element 21 made of the material shown in No. 3 in the above table is used. Reference numerals 41 and 42 denote an inflow channel and an outflow channel, respectively, through which fluid flows in the direction of the arrow. Reference numeral 43 denotes a flow sensor, which is connected to the inflow channel 41 in, for example, a U-shape, and is formed so that the fluid flow in the inflow channel 41 is, for example, 10%. A measurement element 44 is wound around the flow sensor 43 and is electrically connected to the bridge circuit 45. Then 46,47,4
Reference numerals 8 and 49 denote an amplification circuit, a phase compensation circuit, a comparison circuit, and a drive circuit, respectively, which are connected in series to the bridge circuit 45 so as to be able to sequentially transmit output signals of the bridge circuit 45. 50
Is a setting signal output unit, which is connected to the comparison circuit 48. The output voltage of the drive circuit 49 is formed so as to be able to be input to the laminated displacement element 40a constituting the flow control valve 40.

With the above configuration, for example, 0 to 0
When a 5V signal is input to the comparison circuit 48, a DC voltage corresponding to this signal is applied via the drive circuit 49 to the stacked displacement element 40a.
Therefore, the valve port 16 is opened as shown in FIG. 1 and the fluid can be circulated as shown by the arrow in FIG. The output signal of the bridge circuit 45 connected to the measuring element 44 wound around the flow sensor 43 is obtained by amplifying the flow rate of the fluid.
The signal is output to the output unit 50a via the phase compensation circuit 47 and can be measured from this signal. Since this signal is also output to the comparison circuit 48, the opening of the flow control valve 40 is controlled via the drive circuit 49 by comparison with the setting signal.

FIG. 7 is a diagram showing the relationship between the set voltage and the control flow rate, in which the flow rate of triethylgallium gas (TEG) is controlled by the mass flow controller as shown in FIG. In this case, the mass flow controller was heated to 160 ° C., and the gas differential pressure was set as the vapor pressure of TEG. As is clear from FIG. 7, it is shown that the set voltage and the control flow rate are completely proportional. Further, since the stroke of the diaphragm (reference numeral 17 in FIG. 1) of the flow control valve constituting the mass flow controller can be increased, clogging and adhesion of dirt can be prevented, and sufficiently large even at a low differential pressure. The flow rate can be obtained.

FIG. 8 is an explanatory view of a main part schematically showing a reduced pressure CVD apparatus according to still another embodiment of the present invention. In FIG. 8, 51
Is a heating chamber, TEOS (tetraethoxysilane)
To accommodate. Reference numeral 52 denotes a heater, which is provided so as to surround the heating chamber 51. 53 is a reaction furnace, and the primary side 53a
The heating chamber 51 is connected via a mass flow controller 54 having the structure shown in FIG. 6, and a rotary pump (not shown) is connected to the secondary side 53b. Note that all piping systems (including the mass flow controller 54) from the heating chamber 51 to the reaction furnace 53 were heated to 150 ° C.

With the above configuration, a glass substrate is placed in the reaction furnace 53, heated to 300 ° C., and the secondary side 53b of the reaction furnace 53 is depressurized to 10 ⁻³ Torr by a rotary pump (not shown). An SiO ₂ film was formed. For comparison, Table 2 shows the results of performing the same film formation as above using a conventional mass flow controller.

As is clear from Table 2, when a conventional product is used as the mass flow controller 54 in FIG. 8, the operating temperature is 80 ° C. due to the characteristics of the piezoelectric element as the drive source.
Is the limit, vapor pressure is 40mmHg, and maximum flow rate is 300cc
The gas can only flow per minute. On the other hand, when the mass flow controller of the present invention is used, 150
The maximum flow rate was 2500 cc / min against the steam pressure raised to 450 mmHg because the valve stroke reached the maximum value near this temperature. As a result of the above, the film forming speed was 7 to 8 μm in the product of the present invention, compared with 2-3 μm / hour in the conventional product.
Large values of μm / hour were obtained.

In this embodiment, an example in which the entire flow control valve is heated has been described. However, only the stacked displacement element may be heated by a heating means such as an electric heating coil or a surface heater. The heating means may use the heat of the fluid itself. The flow control valve may be not only a normally open type but also a normally closed type, and the target fluid may be a liquid as well as a gas, and can be applied to a low temperature fluid and a normal temperature fluid in addition to a high temperature fluid. .
Next, the stacked displacement element is not limited to the full electrode type element shown in FIGS. 2 and 11, but may be a so-called alternating electrode type element.
Also, the present invention is naturally applicable to a device in which internal electrodes are provided on both surfaces of a thin plate and stacked or bonded. The planar projection shape of the thin plate and the internal electrode can be a square, a circle, an ellipse, and other geometric shapes in addition to the rectangle. Alternatively, in order to obtain a larger displacement, it is possible to use a plurality of the elements by bonding them with a heat-resistant adhesive. Further, the present invention can be applied to a type in which lead wires are omitted and lead members are fixed to the upper and lower end surfaces of the laminate. In the above embodiment, an example in which the screen printing method is used as the means for forming the internal electrode and the external electrode has been described. It is. In yet above embodiment, the maximum generated displacement at 0.99 ° C. vicinity as an electromechanical converter material, i.e., shows the case the piezoelectric strain constant d ₃₃ is a material that shows a maximum value, by selecting the composition, up to 250 ° C. The one that shows the maximum value at other temperatures can also be used, and can be appropriately selected in consideration of the operating temperature of the stacked displacement element.

In this embodiment, an example in which a polyimide resin is used as the heat-resistant resin has been described. However, other resins having a heat resistance of 200 ° C. or more, such as epoxy phenol, epoxy novolak, silicone, modified silicone, poly Of course, benzimidazole, fluororesin and the like are also applicable.

〔The invention's effect〕

The flow rate control valve for a high temperature range and the mass flow controller using the same according to the present invention have the above-described configuration and operation. Therefore, for example, even when an organic metal gas having a boiling point of 50 to 150 ° C. for holding the piezoelectric strain constant d ₃₃ becomes large enough values of the material of the element, the stroke of the diaphragm is large, it is possible to obtain a sufficient flow rate. Further, there is no clogging and contamination of the valve seat and the diaphragm by the fluid, and the reliability can be greatly improved. Note that only the stacked displacement element is heated to obtain the piezoelectric strain constant.
If brought into operation at d ₃₃ is 100 ° C. over a temperature region showing a maximum value of more than 645 × 10 ^-12 m / v, since the diaphragm stroke consisting large normal temperature or low temperature is obtained, the low temperature and room temperature as the target fluid that The present invention is also applicable to the present invention, and has an effect that the use can be expanded.

Further, since the laminated displacement element for high temperature region of the present invention has the configuration and operation as described above, even when used in a high temperature atmosphere such as 100 to 250 ° C., the piezoelectric strain constant d _{33 is obtained.}
Can maintain a sufficiently large value, can stably generate a predetermined displacement without causing conduction failure and other inconveniences, greatly improve the reliability of the stacked displacement element, and There is an effect that can be expanded.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an essential part showing an embodiment of the present invention, and FIGS. 2 (a) to 2 (d) are perspective views each showing an example of a laminated body constituting a laminated displacement element in an embodiment of the present invention. , FIG. 3 is a diagram showing the relationship between the temperature and the generated displacement, FIG. 4 is a diagram showing the relationship between the temperature and the maximum flow rate, FIG. 5 is a diagram showing the relationship between the temperature of the organometallic gas and the vapor pressure, FIG. 6 is a diagram showing a main part of another embodiment of the present invention, FIG. 7 is a diagram showing a relationship between a set voltage and a control flow rate, and FIG. 8 is a low-pressure CVD apparatus in still another embodiment of the present invention. 9 is a longitudinal sectional view schematically showing a conventional flow control valve, and FIGS. 10 and 11 are side views each schematically showing an example of a conventional laminated displacement element. FIG. 11: body, 15: valve seat, 17: diaphragm, 21: laminated displacement element,
31: thin plate, 35: laminate, 39: coating, 40: flow control valve, 54: mass flow controller.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahiro Sometsugi 5200 Sankajiri, Kumagaya-shi, Saitama Hitachi Metals, Ltd. Magnetic Materials Research Laboratory (56) References JP-A-48-46900 (JP, A) JP-A-63 −266706 (JP, A) Actually open 1-77175 (JP, U)

Claims (6)

(57) [Claims] A body provided with a valve chamber having an open end, an inflow channel and an outflow channel formed with one end communicating with the valve chamber and having the other end opened; A valve seat provided at an end communicating with the valve chamber, a thin diaphragm made of a metal material provided so as to seal an opening end of the valve chamber, a housing disposed at an opening end of the valve chamber of the main body, In the flow control valve having the stacked displacement element provided in the housing, the stacked displacement element is PbO61
~ 66%, SrCO _{3 2} ~ 5%, TiO ₂ 10.5 ~ 12%, ZrO ₂ 20 ~ 22%, Sb
₂ O ₃ consists of 0.1% to 2.0% of the composition, formed at 100 ° C. or higher temperature range by an electromechanical converter material, such as a piezoelectric strain constant d ₃₃ is 645 × 10 ^-12 m / v or more of the maximum value, the A flow control valve for a high temperature range, wherein the diaphragm is configured to be driven to come into contact with and detach from the valve seat. 2. A method according to claim piezoelectric strain constant d ₃₃ of the electromechanical conversion material temperature multilayer displacement element temperature region near showing the maximum value, characterized in that a heating means to operate (1) The flow control valve for high temperature range as described. 3. A flow control valve for controlling a flow rate of a fluid,
A flow sensor for detecting a flow rate of a fluid flowing in a sensor flow path provided in an inflow passage or an outflow passage of the flow control valve in a bypass manner, and the flow control valve according to an output of the flow sensor; A mass flow controller having control means for controlling the flow rate control valve, wherein the flow control valve is provided with a valve chamber having an open end and an inflow channel and an outflow channel formed so that one end communicates with the valve chamber and the other end is opened. A valve seat provided at an end of the inflow channel or the outflow channel communicating with the valve chamber; a thin diaphragm made of a metal material provided to seal an open end of the valve chamber; And a laminated displacement element provided in the housing for pressing the diaphragm toward the valve seat, and the laminated displacement element is weighted. _{Ratio, PbO61~66%, SrCO 3 2~5%} ,
_{TiO 2 10.5~12%, ZrO 2 20~22} %, Sb 2 O 3 consists of 0.1% to 2.0% of the composition, the piezoelectric strain constant d ₃₃ in the temperature range above 100 ° C.
A mass flow controller formed of an electromechanical conversion material having a maximum value of 645 × 10 ⁻¹² m / v or more, and configured to drive the diaphragm so as to be capable of coming into and out of contact with the valve seat. . 4. A laminate is formed by alternately laminating a plurality of thin plates made of an electromechanical conversion material and internal electrodes made of a conductive material, and connecting the internal electrodes to every other layer on the side surface of the laminate. In a laminated displacement element provided with a pair of external electrodes, the weight ratio of PbO61 ~
66%, SrCO ₃ 2-5%, TiO ₂ 10.5-12%, ZrO ₂ 20-22%, Sb ₂ O
₃ consists 0.1% to 2.0% of the composition, laminating the high temperature zone, characterized in that the piezoelectric strain constant d ₃₃ in the temperature range above 100 ° C. has a material showing a 645 × 10 ^-12 m / v or more of the maximum value Type displacement element. 5. A high temperature range laminated displacement element according to claim 4, wherein a coating made of a heat-resistant insulating resin material is provided on the surface of the laminated body. 6. A lead wire connected to an external electrode by a solder having a liquidus temperature of 200 ° C. or higher.
Or, the stacked displacement element for a high temperature range according to (5).