JP4583974B2 - Needle valve - Google Patents

Description

The present invention relates to a flow rate adjustable needle valve fitted with flow meters, in particular, it relates to a needle valve that enables flow control to meet the linear flow characteristics.

  Normally, this type of valve is a valve that performs flow control by sequentially changing the opening area of the flow between the valve body and the valve seat by raising and lowering the valve body, and various fields including semiconductor and liquid crystal manufacturing fields. Used in. In this type of valve, it is particularly important to secure a stable flow rate corresponding to the lift amount of the valve body. For example, in Japanese Utility Model Publication No. 6-83946, the inlet side of the flow hole of the valve seat is a tapered portion. A needle valve that is formed to prevent a decrease in flow rate when the valve body is fully open is disclosed.

By the way, since a flow meter for measuring the flow rate is prepared separately from the valve, the conventional technology, such as Japanese Utility Model Publication No. 6-83946, does not take into account the total flow characteristics obtained by combining the flow meter and the valve. For this reason, when a flow meter is attached to the valve, the overall flow characteristics deteriorate, causing problems such as inability to stably adjust the flow rate. To solve this problem, the flow rate controller is used to compare the measured flow rate detected by the flow meter with the set flow rate, feedback control of the valve opening adjustment, and automatically adjust the measured flow rate to match the set flow rate. It is possible to correct it.
Japanese Utility Model Publication No. 6-83946

  However, even if the above-mentioned flow controller is used, it is necessary to accurately understand how the installation of the flow meter will affect the overall flow characteristics including the valve. The flow rate characteristic cannot be changed to a desired flow rate characteristic, and stable flow rate adjustment cannot be realized.

  The present invention has been developed as a result of diligent research in view of the above-mentioned problems, and the object of the present invention is to provide a linear flow rate characteristic even if the valve is equipped with a flow meter. It is an object of the present invention to provide a needle valve that satisfies the requirements and enables stable flow rate control, as well as downsizing and cost reduction of the entire apparatus including the flow meter.

In order to achieve the above object, according to the present invention , in a needle valve equipped with a flow meter, the maximum opening area of the valve seat and the flow passage area of the inlet of the valve main body are linear flow characteristics in the control of the valve alone. The needle valve is set to satisfy the area ratio, and the maximum Cv ₁ value of the valve unit and the Cv ₂ value of the flow meter unit are set to the Cv value ratio in which the total flow rate characteristic of the valve including the flow meter is a linear flow rate characteristic. is there.

According to the present invention, even a valve equipped with a flow meter satisfies linear flow characteristics and enables stable flow control . For example, control devices in various fields including a semiconductor pure water supply control device to provide a needle valve that can be applied to, with, the size of the entire apparatus including the flow meter and the cost reduction of becomes available.

  Hereinafter, an embodiment of a needle valve according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of a needle valve based on the principle of the present invention. In FIG. 1, a flow meter M is attached to the primary side of the needle valve via a fixing member such as a bolt. The flow meter M has its tip end inserted and fixed in the inlet 2 of the valve body 1 and is integrated with the valve body 1. Therefore, since it is not necessary to connect a separate pipe or joint between the needle valve and the flow meter M, it is possible to obtain a needle valve with a flow meter that is reduced in size and cost. In the figure, 3 is an outlet located on the secondary side of the valve body 1, and 4 in the figure is a valve chamber provided in the flow path of the outlets 2 and 3. The flow meter M may be attached to the secondary side of the needle valve, but is preferably attached to the primary side of the needle valve so as not to be affected by the turbulent fluid after the needle valve flows down.

  In the figure, reference numeral 5 denotes an annular valve seat portion (made of metal in this example) mounted in the valve chamber 4, and an inclined surface extending upward is formed at the valve port of the valve seat portion 5. . In the figure, reference numeral 6 denotes a needle (made of metal in this example) seated on the valve seat portion 5, and a tapered surface is formed on the outer peripheral portion of the needle 6. An outer peripheral groove 7 is provided above the tapered surface, and an O-ring 8 that seals between the needle 6 and the valve seat portion 5 at the time of seating is mounted. The outer peripheral groove 7 shown in this example is formed with a gap that expands the primary side, and the O-ring contact surface side is an arcuate surface that exhibits a radius that can substantially match the radius of the O-ring 8. The structure prevents the O-ring 8 from popping out when opened. Of course, the shape and structure of the valve seat 5 and the needle 6 are not limited to this.

In FIG. 1, the needle 6 is at the top of the moving range for flow rate control, and is in a fully open state where the flow rate through the valve is the largest. In this fully open state, the opening area formed between the outer peripheral tapered surface of the needle 6 and the minimum diameter inclined surface of the valve seat portion 5 (in this example, the cylindrical reduced diameter portion 5a) is set to the maximum of the valve seat portion 5. When the opening area A1 is set, the maximum opening area A1 and the flow path area A2 of the inlet 2 are set to an area ratio that satisfies a linear flow rate characteristic in the control of the single valve, and will be described later. The maximum Cv ₁ value of the single valve having an area ratio and the Cv ₂ value of the flow meter M are set to a Cv value ratio at which the total flow characteristic of the valve + flow meter becomes a linear flow characteristic, as will be described later.

  In the figure, 9 is a shaft mounting hole provided in communication with the valve chamber 4, and 10 in the figure is a shaft portion of the needle 6. In the figure, 11 is an O-ring inserted into the shaft portion 10 of the needle 6, 12 in the figure is a mounting groove of the O-ring 11, and 13 and 14 in the figure are cylindrical bodies (shaft assemblies) to be axially mounted. And a holding body (shaft assembly). The cylindrical body 13 (made of resin in this example) is provided with a cylindrical protrusion 13a, and a shaft portion insertion hole 13b is formed therein. On the other hand, the holding body 14 (made of resin in this example) is provided with a fitting groove 14a for fitting the projection 13a of the cylindrical body 13, and the shaft part is inserted through the fitting groove 14a. A hole 14b is formed. When the protrusion 13 a provided on the cylindrical body 13 is fitted into the fitting groove 14 a provided on the holding body 14, a mounting groove 12 for mounting the O-ring 11 is formed between the cylindrical body 13 and the holding body 14. The This shaft seal structure is an example, and is not limited to this.

  In the figure, 15 is a coil spring, 16 in the figure is a washer provided on the shaft portion 10, and 17 in the figure is a cylindrical bush. Although not shown, the valve body 1 and the bush 17 are provided with a communication hole that communicates with the outside. In the figure, 18 is a direct-acting electric motor (stepping motor), 19 in the figure is an output shaft of the electric motor 18, and 20 in the figure is an actuator incorporating the electric motor 18.

  FIG. 2 is an exploded perspective view of the needle valve in FIG. 1. The assembly procedure will be described with reference to FIG. 1. First, a seal ring 21 is mounted from a shaft mounting hole 9 formed in communication with the annular valve chamber 4. The annular valve seat 5 is inserted into the valve body 1 and disposed on the step portion 1 a provided on the inflow side of the valve chamber 4. At this time, the annular valve seat 5 is mounted in the annular valve chamber 4 with an appropriate gap in the centrifugal direction. A seal ring 22 that seals between the holding body 14 and the shaft mounting hole 9 is disposed.

  Subsequently, an O-ring 8 is attached to the outer circumferential groove 7 provided in the needle 6. After the cylindrical body (shaft assembly) 13 is mounted on the shaft portion 10 of the needle 6, the O-ring 11 is inserted, and the holding body (shaft assembly) 14 is mounted with the O-ring 11 interposed. Shaft. As shown in FIG. 1, when the protrusion 13 a provided on the cylindrical body 13 is fitted in the fitting groove 14 a provided on the holding body 14, the O-ring 11 is mounted between the cylindrical body 13 and the holding body 14. A mounting groove 12 is formed. Therefore, unlike the conventional case, it is not necessary to integrally process the groove for mounting the O-ring on the stem or the shaft mounting portion, so that excellent shaft sealing performance is realized even with a small-sized valve, and the O-ring position Since the O-ring 11 is attached to a portion not accompanied by the movement, the durability is far superior to the conventional structure in which the O-ring is attached to the stem. In addition, the O-ring 11 inserted into the shaft portion 10 of the needle 6 is mounted in the mounting groove 12 if the protrusion 13a of the cylindrical body 13 and the fitting groove 14a of the holding body 14 are fitted. Thus, an excellent sealing function can be effectively exhibited.

  A cylindrical body (shaft assembly) 13 assembled with the holding body (shaft assembly) 14 is inserted into the valve chamber 4 to press the upper end surface of the annular valve seat 5, while One end of a spring 15 that urges and urges the spring is attached to the upper portion, and the other end of the spring 15 is locked to a washer 16 provided on the shaft portion 10 to return to the old position by the elastic force of the spring 15. Since the structure is adopted, the up and down movement of the needle 6 can immediately follow the drive of the electric motor 18 without being affected by the backlash of the direct acting electric motor 18, and accurate flow path control can be realized. . In addition, the shaft portion 10 of the needle 6 and the output shaft 19 of the direct acting electric motor 18 are separate from each other, and a structure that does not cause misalignment is realized.

  Further, in the needle valve shown in this example, a holding body 14 is assembled to the shaft portion 10 via a cylindrical body 13 and an O-ring 11, and a spring 15 for elastically energizing is provided on the upper portion of the holding body 14. One end is attached, and the other end of the spring 15 is engaged with a washer 16 provided on the shaft portion 10 to constitute a unit. In FIG. 2, an O-ring 8, a needle 6, a cylinder body is formed from the lower side. 13, O-ring 11, holding body 14, spring 15, washer 16, and split ring 16 a are made into a series of temporary assembled states, and can be assembled from this temporarily assembled state, thereby realizing excellent ease of assembly. .

  As described above, the unit in the temporarily assembled state is inserted into the valve body 1 from the shaft mounting hole 9 formed in communication with the valve chamber 4 and is positioned on the upper surface of the annular valve seat 5. A cylindrical bushing 17 is inserted and positioned on the upper surface of the holding body 14. Since the valve body 1 and the bush 17 are provided with a communication hole (not shown) that communicates with the outside, when the unit is inserted into the valve body 1, the gas in the valve body 1 is discharged from the communication hole, so that smooth installation is possible. It is possible to enter.

  Subsequently, the annular valve seat 5 is adjusted through the needle 6 in the centrifugal direction by the pushing-down operation of the shaft portion 10 to perform alignment. In this example, the diameter-enlarged portion of the tapered surface of the needle 6 is configured to align while pressing a part of the diameter-reduced portion of the inclined surface of the annular valve seat 5, and the shaft portion 10 has a plurality of push-down operations. Further, in this example, the shaft portion 10 employs a structure in which the spring portion 15 returns to the old position by the elastic force of the spring 15, so that a plurality of push-down operations are easy. As a means for depressing, in addition to manual operation, an actuator mounted on the valve body 1 or a separate device may be used.

  When the alignment of the annular valve seat 5 is completed, the housing 20a of the actuator 20 is fixed to the valve body 1 using mounting parts such as bolts. Thereby, the cylindrical body 13 and the holding body 14 which are shaft bodies are pressed via the bush 17, and the annular valve seat 5 is also fixed to the valve body 1. In this example, when the installation of the actuator 20 is completed, the axis of the needle 6 and the axis of the annular valve seat 5 are in alignment. In addition, by fixing the housing 20a of the actuator 20 to the valve body 1 in a state where the shaft portion 10 is pushed down, the annular valve seat 5 can be fixed to the valve body 1 while being kept aligned.

  When the assembly is completed, the annular valve seat 5 is firmly fixed in the valve chamber 4, so that the centering and fixing state is reliably maintained unless the casing 20a of the actuator 20 is removed. Thus, since the alignment of the annular valve seat 5 is completed when the needle valve is assembled, the sliding resistance associated with the alignment of the valve seat / valve body during the valve operation is suppressed, and the shaft portion 10 is made thinner. (In this example, about φ3 mm), the actuator can have a small output, the entire valve can be made more compact, and the amount of fluid staying inside the valve can be reduced.

Through the diligent research of the inventor of the present application, the flow rate characteristics of the valve having the flow meter M attached to the primary side are as follows. The maximum Cv ₁ value and the Cv ₂ value of the flow meter M were found to be determined. In order to prove this, the following tests were conducted. The allowable range of the linear flow rate characteristic is based on JIS B 2005-2-4. In the “valve lift amount-capacity coefficient (Cv value) characteristic graph” described later, the “maximum inclination of the slope” of the flow rate characteristic of the test sample is shown. However, the range was less than twice the slope of the ideal linear characteristic.

  The "maximum inclination of inclination" here refers to the ideal linear characteristic (inclination of the straight line connecting each adjacent measurement value in the "valve lift amount-capacity coefficient (Cv value) characteristic graph" of the specimen. This is the ratio of the slope of the straight line between the measured values that makes the largest difference to the slope of the ideal straight line with respect to the characteristic in which the Cv values at the maximum and minimum opening of the control range are connected by a straight line. For example, in FIG. In FIG. 1, the measurement value having the largest difference with respect to the ideal linear characteristic is the HG section, and the slope thereof is 0.0016667. Since the slope of the ideal linear characteristic (HA section) is 0.160619, the maximum bias of the slope is slope of HA section / slope of HG section = 96.37.

(Test 1)
Realization of linear characteristics with a single valve:
In order to achieve a linear flow rate characteristic with a valve and a flow meter, it is first necessary to realize a linear flow rate characteristic with a single valve. In this test, a valve with a nominal diameter of 10A was used. As a general rule, the flow area A2 of the primary inlet of the valve was kept constant, and the maximum opening area A1 of the valve seat portion was changed to obtain the value of the opening area ratio A2 / A1. Five types of specimens with different numbers 1-No. 5 was prepared and the flow characteristic test was conducted. The specimen No. In No. 4, the value of the flow path area A2 was also changed, and the opening area ratio was adjusted. The test results are shown in Table 1, and the flow rate characteristic data for each opening area ratio is shown in FIG.

  From the results of this test, no. 1-No. For “3”, the “maximum bias of inclination” is larger than 2, and no linear characteristic is obtained. On the other hand, no. 4 and no. No. 5 is a linear flow rate characteristic in which the “maximum inclination of inclination” is 2 or less, and an equal increment of the lift amount causes an equal increment of the Cv value over the entire movement range from the start of lift of the valve body to the maximum. Has been obtained.

  FIG. 4 shows the “maximum inclination of inclination” with respect to the aperture area ratio based on the data in Table 1 and FIG. Specimen No. Although the “maximum deviation of inclination” of 5 is less than 2 and linear characteristics are obtained, the opening area ratio (A2 / A1) is larger than the opening area ratio (15.4) corresponding to a drop of one step in the diameter. Therefore, the size (nominal diameter) of the valve is excessive with respect to the actual flow rate. Therefore, the sample No. If it is 4, the linear flow rate characteristic can be obtained without the size of the valve becoming excessive.

  Next, the area ratio between the flow path area A2 of the inlet corresponding to the “maximum deviation of inclination” upper limit 2 and the maximum opening area A1 of the valve seat, that is, the minimum opening area ratio is about 3.5 from FIG. By setting the maximum opening area A1 of the valve seat portion and the flow passage area A2 of the inlet so as to exceed this ratio, it is possible to perform control satisfying the linear characteristics as a single valve. On the other hand, although the linear characteristic is satisfied, as described above, the setting of the opening area ratio that reduces the Cv value to a value corresponding to a drop in the pipe diameter by one step (for example, the diameter is reduced from 10A to 8A) is a valve. The actual flow rate with respect to is extremely small and the size of the valve becomes excessive. The opening area ratio corresponding to one drop, that is, the maximum opening area ratio is calculated as follows as an example of reducing the aperture from 10A to 8A.

Since the opening area ratio of one drop is (10 ÷ 8) ² = 1.56, the maximum opening area ratio is 3.5 (minimum opening area ratio) × 1.56 = 5.46. Therefore, in a valve having a nominal diameter of 10A with a flow meter attached to the primary side, the area ratio (A2 / A1) between the maximum opening area A1 of the valve seat and the flow passage area A2 of the inlet is 3.5 to 5.5. By setting to, a linear flow rate characteristic can be obtained without the valve size becoming excessive. According to the needle valve of the present embodiment, the setting of the maximum opening area A1 of the valve seat portion can be changed by exchanging the valve seat portion 5 and the needle 6, so that the area ratio (A2 / A1) Can be easily adjusted.

(Test 2)
Realization of linear characteristics with valve + flow meter:
In this test, a valve with a nominal diameter of 10A was used, and three types of specimens with different Cv value ratios between the valve unit and the flow meter unit. 4 (1) -No. 4 (3) was created and a flow characteristic test was performed. The test results are shown in Table 2, and the flow rate characteristic data for each Cv value ratio is shown in FIG. In this example, evaluation was performed by simply calculating the combined Cv value of the valve and the flow meter by the following formula.

a formula

  From the results of this test, no. 4 (1) and no. In 4 (2), the “maximum deviation of inclination” is 2 or less, and the lift amount equal increment over the entire moving range from the start of lift of the valve body to the maximum is a linear in which the Cv value equal increment is generated. Flow characteristics are obtained. On the other hand, no. In 4 (3), the “maximum inclination of inclination” is larger than 2, and no linear characteristic is obtained.

  FIG. 6 shows the “maximum inclination of inclination” with respect to the Cv value ratio between the single valve and the single flowmeter based on the data in Table 2 and FIG. Specimen No. The Cv value of 4 (3) is the specimen No. 4 (2), which is about 20% lower than the maximum (refer to the Cv value at the maximum lift amount of 4.8 mm). May be selected as appropriate so that an appropriate flow rate characteristic can be obtained within a range of “maximum deviation of 2” or less.

As is clear from the results of tests 1 and 2 described above, the flow characteristics of the needle valve provided with the flow meter on the primary side are the maximum opening area A1 of the valve seat and the flow path area A2 of the primary inlet. And the ratio of the maximum Cv ₁ value of this single valve unit to the Cv ₂ value of the flow meter, and it is possible to realize control satisfying the linear flow rate characteristic in the valve with flow meter. Specifically, in a valve having a nominal diameter of 10A with a flow meter attached to the primary side, the area ratio (A2 / A1) between the maximum opening area A1 of the valve seat and the flow path area A2 of the inlet is 3.5 to In addition to setting to 5.5, by setting the Cv value ratio (Cv ₁ : Cv ₂ ) between the valve unit and the flow meter unit to 1: 2.5 to 1: 4, In the combined flow characteristics, the “maximum inclination of inclination” can be suppressed to less than twice the inclination of the ideal linear characteristics, and the flow rate of the needle valve with flowmeter is based on accurate and stable linear characteristics. Can be controlled.

The needle valve according to the present invention can be applied as a regulating valve for adjusting the flow rate in various fields such as a semiconductor manufacturing apparatus, a liquid crystal manufacturing apparatus, and a chemical food plant. For example, a cooling medium, pure water, or a chemical solution delivery, or in other fields, in particular, even in applications that need to control the precise minute flow rate, to realize highly accurate micro flow rate control and a fully blocking, moreover, realizes the control that meets the linear flow characteristics It is possible to provide as a compact needle valve.

It is sectional drawing which showed an example of the needle valve in this invention. FIG. 2 is an exploded perspective view of the needle valve in FIG. 1. It is the graph which showed the flow rate characteristic data according to opening area ratio in the valve | bulb single body of this invention. It is the graph which showed the relationship between the opening area ratio in FIG. 3, and the maximum deviation of inclination. It is the graph which showed the flow characteristic data according to Cv value ratio in the valve | bulb + flowmeter of this invention. 6 is a graph showing the relationship between the Cv value ratio and the maximum deviation in slope in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Valve body 2 Inlet 5 Valve seat part A1 Maximum opening area of valve seat A2 Flow path area of inlet M Flow meter

Claims (1)

In a needle valve equipped with a flow meter, the maximum opening area of the valve seat and the flow passage area of the inlet of the valve body are set to an area ratio that satisfies the linear flow characteristics in the control of the valve alone, and A needle valve characterized in that the maximum Cv ₁ value and the Cv ₂ value of the single flowmeter are set to a Cv value ratio in which the total flow characteristic of the valve including the flowmeter is a linear flow characteristic .

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