JP7453134B2 - flow control valve - Google Patents

Description

A driving device, a rod that is moved by the operation of the driving device, and a needle valve body that is connected to the rod and moves forward and backward relative to the annular valve seat as the rod moves, the needle valve body moving relative to the annular valve seat. The present invention relates to a flow control valve that controls the flow rate of a control fluid by adjusting the opening degree.

A cleaning solution prepared by diluting a chemical solution (eg, hydrochloric acid, ammonia, hydrofluoric acid, etc.) is used for cleaning wafers during the semiconductor manufacturing process. In order to manage the concentration of a chemical solution, the flow rate of the chemical solution is controlled, and a needle valve disclosed in Patent Document 1, for example, is known as a flow control valve that performs this flow rate control.

This needle valve includes a drive device (motor 110 disclosed in Patent Document 1), a rod (rod 60 disclosed in Patent Document 1) that moves directly by the operation of the drive device, and a needle connected to the tip of the rod. A valve body (valve body 41 disclosed in Patent Document 1). Further, the rod is inserted through a guide portion (first accommodating portion 31 disclosed in Patent Document 1), and the linear motion of the rod is guided by the guide portion. Then, the needle valve body moves forward and backward with respect to the annular valve seat (valve seat portion 24 disclosed in Patent Document 1) by the direct movement of the rod.

Such a needle valve controls the flow rate of the control fluid by adjusting the opening degree of the needle valve body with respect to the annular valve seat. For example, when controlling the chemical liquid to a predetermined minute flow rate (for example, 1 to 10 ml/min), the opening degree of the needle valve body with respect to the annular valve seat should be set so that the gap between the needle valve body and the annular valve seat is several tens of μm. The opening is adjusted to the following minute opening.

Patent No. 5150009

Ideally, the needle valve as described above should have the center axis of the needle valve body and the center axis of the annular valve seat coaxial, and the opening degree should be adjusted to control the control fluid to a predetermined minute flow rate. When the opening is adjusted to a minute degree, it is desirable that a uniform gap be formed between the needle valve body and the annular valve seat around the entire circumference of the needle valve body. However, in reality, due to manufacturing tolerances and the like, a slight positional deviation occurs between the central axis of the needle valve body and the central axis of the annular valve seat in the radial direction of the annular valve seat. If this happens, when the opening is adjusted to a minute opening, a uniform gap will not be formed between the needle valve body and the annular valve seat around the entire circumference, and a portion of the needle valve body will come into contact with the annular valve seat (i.e., There is a risk of hitting. Needle valves repeatedly adjust minute openings while controlling flow rate, so if uneven contact occurs on the needle valve body, the uneven contact area will rub against the annular valve seat, causing uneven contact. There is a risk of abrasion occurring where the parts are worn.

In particular, conventional needle valves are prone to wear as described above. This is because the gap between the rod and the guide portion is set as small as possible in order to ensure the straightness of the rod and to prevent the axis of the needle valve body from wobbling due to fluid pressure. By making the gap between the rod and the guide part as small as possible, the thrust of the motor (approximately 50N or more) that attempts to operate the rod and needle valve body cannot escape and is loaded onto the spot where it hits the rod and the needle valve body. Ru. In this case, the contact pressure caused by the annular valve seat against the needle valve body becomes excessive, and the above-mentioned wear is likely to occur.

When wear occurs on the needle valve body as described above, there is a possibility that the wear powder may be mixed into the chemical solution as particles. If particles get mixed into the chemical solution, the particles will get mixed into the wafer cleaning solution.

Moreover, the magnitude of the wear increases depending on the amount of positional deviation between the center axis of the needle valve body and the center axis of the annular valve seat, and there is a risk that the shape of the needle valve body will be significantly deformed. In this case, even if the needle valve is adjusted to the same opening degree, the flow rate of the chemical solution will change before and after the needle valve body wears out, and the concentration of the chemical solution in the wafer cleaning solution may vary.

Contamination of particles in the cleaning liquid and fluctuations in the concentration of the chemical solution may lead to manufacturing defects in wafers and adversely affect semiconductor manufacturing efficiency.

The present invention has been made in view of the above problems, and provides a flow control valve that can suppress the occurrence of wear even when the needle valve body makes uneven contact with the annular valve seat. With the goal.

In order to solve the above problems, the flow control valve of the present invention has the following configuration.
(1) An annular valve with a needle valve element, comprising a drive device, a rod that is moved by the operation of the drive device, and a needle valve body that is connected to the rod and moves forward and backward with respect to the annular valve seat as the rod moves. A flow control valve that controls the flow rate of a controlled fluid by adjusting the opening degree with respect to a seat is provided with a guide part through which a rod is inserted with a gap and guides movement of the rod, and the rod is inserted into the guide part. An annular elastic body is provided on the outer circumferential surface of the inserted part, and the rod is slidably held relative to the guide part, and the rod is attached to the annular valve seat with the elastic body as a fulcrum at least through a gap. It has a degree of freedom that can be tilted with respect to the central axis, and the opening degree is adjusted to a minute degree in order to control the control fluid to a predetermined minute flow rate, and the needle valve body makes one-sided contact with the annular valve seat. In this case, the degree of freedom allows the rod to incline, thereby relieving the contact pressure applied to the needle valve body due to one-sided contact.

According to the flow control valve described in (1), the rod is inserted through the guide portion with a gap, and the rod has at least a degree of freedom that allows it to be tilted with respect to the central axis of the annular valve seat due to the gap. There is. Due to this degree of freedom, the opening degree can be adjusted to a minute opening in order to control the control fluid to a predetermined minute flow rate, and even if the needle valve body makes one-sided contact with the annular valve seat, the rod will not tilt. can. If the rod can be tilted, even if uneven contact occurs, it will be possible to release the thrust of the drive device that operates the rod and needle valve element, and the uneven impact will reduce the load from the annular valve seat to the needle valve element. contact pressure is relieved. Therefore, even if the needle valve body makes partial contact with the annular valve seat, it is possible to suppress the occurrence of wear.

If the occurrence of wear can be suppressed, the generation of wear powder can be suppressed, and, for example, it is possible to prevent particles from being mixed into a control fluid such as a chemical solution. Furthermore, conventionally, when the needle valve body becomes deformed due to wear, even if the needle valve body is adjusted to the same opening degree, the flow rate of the chemical solution changes before and after the needle valve body wears out. However, if the occurrence of wear can be suppressed, this risk can also be reduced. Preventing particles from entering the chemical solution and reducing the possibility of fluctuations in the concentration of the chemical solution can prevent the occurrence of manufacturing defects in wafers.

Note that the fact that the rod can be tilted means that the axis of the needle valve body may shift due to fluid pressure, which may have an adverse effect on flow control. However, through experiments, the applicant has found that the It was confirmed that the flow control valve can perform fluid control with the same accuracy as conventional flow control valves.

(2) In the flow control valve described in (1), when the needle valve body makes one-sided contact with the annular valve seat, the inclination of the rod due to the degree of freedom shall be within the range of 2 degrees or more and 6 degrees or less. , is characterized by.

According to the flow control valve described in (2), even if the needle valve body makes partial contact with the annular valve seat, it is possible to suppress the occurrence of wear. For example, if the needle valve body makes one-sided contact with the annular valve seat and the inclination of the rod is less than 2 degrees (for example, 1 degree), the thrust of the drive device cannot be released completely, and the needle valve body makes one-sided contact with the annular valve seat 24. The contact pressure applied to the needle valve body may cause wear to the needle valve body. Furthermore, if the needle valve body is tilted at an angle greater than 6 degrees, the movement of the needle valve body due to the fluid pressure (90 kPa) will be excessive, which may cause vibrations and abnormal noises. Therefore, it is desirable that the inclination of the rod due to the degree of freedom is within a range of 2 degrees or more and 6 degrees or less.

(3) In the flow control valve according to (1) or (2), the drive device is a motor having a drive shaft, and the drive shaft includes a feed screw that converts rotational motion of the drive shaft into direct motion. The members are connected, the rod is screwed onto the feed screw member with play, and the degree of freedom is ensured by the gap and play.

According to the flow control valve described in (3), the rod is movable by the feed screw member converting the rotational motion of the drive shaft into a direct motion motion. The rod is screwed onto the feed screw member with some play. In other words, due to the play, the rod is coupled to the feed screw member with a degree of freedom. Therefore, the degree of freedom in which the rod can tilt with respect to the central axis of the annular valve seat is ensured by the degree of freedom due to the gap between the rod and the guide portion and the degree of freedom due to the above-mentioned play. By ensuring the degree of freedom that allows the rod to tilt relative to the central axis of the annular valve seat, it is possible to suppress the occurrence of wear even if the needle valve body hits the annular valve seat unevenly. It is.

According to the flow control valve of the present invention, even if the needle valve body makes partial contact with the annular valve seat, it is possible to suppress the occurrence of wear.

It is a sectional view of a flow control valve (needle valve) concerning this embodiment. 2 is a partially enlarged view of part A in FIG. 1, in which a radial positional deviation of the annular valve seat occurs between the center axis of the needle valve body and the center axis of the annular valve seat, and the needle valve body is aligned with the annular valve seat. It is a diagram showing a state where there is a one-sided hit. It is a graph showing the average value after the 5000th cycle regarding the number of particles of the needle valve according to the present embodiment and the conventional product. It is a graph comparing the relationship between the number of steps of the motor (opening degree of the needle valve body) and the Cv value in the needle valve according to the present embodiment and a conventional product. This is an enlarged graph from step number 380 to step number 400 in FIG. 4. (a) is a diagram showing a test circuit for evaluating the degree of wear on the needle valve body. (b) is a diagram showing the operation sequence of the needle valve to be evaluated.

Embodiments of the flow control valve according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of a flow control valve (needle valve) according to this embodiment. FIG. 2 is a partially enlarged view of part A in FIG. , is a diagram showing a state in which the needle valve body 41 is in partial contact with the annular valve seat 24.

The flow rate control valve according to this embodiment is, for example, a needle valve 1 that adjusts the flow rate of a chemical solution (an example of a control fluid) used as a cleaning liquid in a semiconductor manufacturing process. The chemical liquid is, for example, hydrochloric acid, ammonia, hydrofluoric acid, etc., and its flow rate is controlled by the needle valve 1 to a predetermined minute flow rate (for example, 1 to 10 ml/min). The chemical solution controlled at a minute flow rate is then diluted and used as a wafer cleaning solution.

The needle valve 1 includes a valve body 20 and a drive section 30. The valve body 20 is formed by injection molding or cutting, and its material is a fluororesin with excellent chemical resistance (for example, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA) or polytetrafluorocarbon resin). ethylene (PTFE)).

The valve body 20 includes an input port 25 through which the chemical liquid flows in, and an output port 26 through which the chemical liquid flows out. The valve body 20 also has an input side flow path 21 connected to the input port 25, an output side flow path 23 connected to the output port 26, and the input side flow path 21 and the output side flow path 23. and a valve chamber 22 that connects the valve chamber and the valve chamber. The valve chamber 22 is formed as a cylindrical space that opens at the end surface of the valve body 20 on the drive unit 30 side (the upper end surface in FIG. 1), into which a chemical liquid at a predetermined pressure input from the input port 25 flows. Ru. Further, the valve body 20 includes an annular valve seat 24 at a connecting portion between the input side flow path 21 and the valve chamber 22 .

A drive unit 30 is fixed to an upper end surface of the valve body 20 where the valve chamber 22 opens. The drive unit 30 includes a first cylinder member 120, a second cylinder member 50, and a motor 110 (an example of a drive device) stacked on top of each other, and includes a feed screw member 80, a rod 60, has.

The first cylinder member 120 is formed into a cylindrical shape by injection molding or cutting, and its material is, for example, resin such as PP, PPS, PEEK, or PVDF. A first accommodating portion 124, which is a cylindrical space, is bored in the end surface of the first cylinder member 120 on the second cylinder member 50 side (the upper end surface in FIG. 1). Furthermore, the first cylinder member 120 is formed with a cylindrical guide portion 121 that passes through the first housing portion 124 and the end surface on the valve body 20 side. The guide portion 121 is formed such that the center axis of the guide portion 121 substantially coincides with the center axis of the valve chamber 22 .

A second cylinder member 50 is coupled to the upper end surface of the first cylinder member 120. The second cylinder member 50 is formed by injection molding or cutting, and its material is, for example, resin such as PP, PPS, PEEK, or PVDF. The second cylinder member 50 is a cylindrical space that extends from the end surface on the motor 110 side (upper end surface in FIG. 1) to the end surface on the first cylinder member 120 side (lower end surface in FIG. 1). It has a housing part 55. The second accommodating portion 55 and the first accommodating portion 124 of the first cylinder member 120 communicate with each other, and their central axes substantially coincide with the central axis of the guide portion 121 . Further, at the end (lower end) of the second accommodating portion 55 on the first cylinder member 120 side, an annular projecting portion 51 is provided by an inner circumferential surface projecting inward. This projecting portion 51 forms a boundary between the first accommodating portion 124 and the second accommodating portion 55.

A motor 110 (for example, a stepping motor) is fixed to the upper end surface of the second cylinder member 50. The motor 110 includes a drive shaft 111. The drive shaft 111 is inserted into the second accommodating portion 55 of the second cylinder member 50, and an engagement member 90 formed in the shape of a rectangular parallelepiped made of stainless steel, for example, is coupled to its tip. Note that both end surfaces of the engaging member 90 in the left-right direction in FIG. 1 are parallel to each other.

Further, the motor 110 includes a drive circuit 112. The drive circuit 112 is connected to a control circuit (not shown) included in the needle valve 1 via a signal line 132, and the amount of rotation (number of steps) of the drive shaft 111 output from the control circuit is controlled via the signal line 132. The signal is input to the drive circuit 112. The drive circuit 112 then controls the amount of rotation of the drive shaft 111 based on the input step number. Note that the number of steps is set by the control circuit based on a command input to the control circuit from an external control device (not shown).

A feed screw member 80 is housed in the second housing portion 55 of the second cylinder member 50 below the motor 110 . The feed screw member 80 is made of, for example, stainless steel.

A groove portion 83 is bored in the end surface (upper end surface in the figure) of the feed screw member 80 on the motor 110 side. The inner surfaces of both ends of the groove portion 83 in the left-right direction in the figure are parallel to each other. The width of the groove portion 83 is slightly larger than the width of the engaging member 90 coupled to the drive shaft 111 of the motor 110, and the groove portion 83 has a center axis of the drive shaft 111 and the center of the feed screw member 80. The engaging member 90 is inserted with the axes substantially aligned. Thereby, the engaging member 90 and the feed screw member 80 can move relative to each other in the axial direction of the drive shaft 111, and can transmit the rotational force of the motor 110 to the feed screw member 80. The feed screw member 80 to which the rotational force of the motor 110 is transmitted is rotated about the central axis CL4 of the drive shaft 111. Note that since a radial bearing 76 is provided between the feed screw member 80 and the overhanging portion 51, the radial bearing 76 regulates the rotation axis of the feed screw member 80 and also ensures smooth rotation. has been done. Further, a male threaded portion 82 having a male thread is provided protruding from the end surface of the feed screw member 80 on the opposite side from the motor 110 (lower end surface in FIG. 1).

A rod 60 is accommodated below the feed screw member 80 and extends between the guide portion 121 and the first housing portion 124 and is screwed onto the male threaded portion 82 of the feed screw member 80 . The rod 60 is formed into a cylindrical shape by injection molding or cutting, and its material is, for example, resin such as PP, PPS, PEEK, or PVDF.

The rod 60 includes a first rod part 61 inserted through the guide part 121 with a gap therebetween, and a second rod part 62 housed in the first housing part 124 . The diameter of the second rod portion 62 is larger than the diameter of the first rod portion 61.

The first rod portion 61 is inserted through the guide portion 121, so that the rod 60 is guided by the guide portion 121 and is movable in its axial direction. Note that the second rod portion 62 of the rod 60 is provided with a pin 72 extending in the outer diameter direction, and since this pin 72 is inserted into the groove 122 of the first cylinder member 120, the rod 60 is Rotation about the central axis CL1 is restricted.

Further, an annular groove 65 is provided on the outer peripheral surface of the first rod portion 61, and an O-ring 77 (an example of an elastic body) is fitted into the groove 65 as a sealing member. The O-ring 77 provides a seal between the inner circumferential surface of the guide section 121 and the outer circumferential surface of the first rod section 61, and allows the rod 60 to slide smoothly on the guide section 121.

Further, the O-ring 77 acts as a fulcrum when the rod 60 is inclined with respect to the central axis CL2 of the annular valve seat 24. This inclination refers to the degree of freedom that the rod 60 has because the first rod portion 61 is inserted through the guide portion 121 with a gap. For example, as shown in FIG. 2, the rod 60 can be tilted within the guide portion 121 with respect to the central axis CL2 of the annular valve seat 24 using the O-ring 77 as a fulcrum. Note that a sufficient gap is set between the outer circumferential surface of the second rod portion 62 and the inner circumferential surface of the first accommodating portion 124, so that the outer circumferential surface of the second rod portion 62 and the inner circumferential surface of the first accommodating portion 124 are This prevents the rod 60 from interfering with the surrounding surface and preventing the rod 60 from tilting.

One end of a spring 71 (the lower end in FIG. 1) is in contact with the end surface of the second rod portion 62 on the motor 110 side. Further, the other end (the upper end in FIG. 1) of the spring 7 1 is in contact with the projecting portion 51 . The spring 71 applies an elastic force to the rod 60 and the overhang 51, and moves the rod 60 in the direction in which the rod 60 moves away from the overhang 51, that is, in the direction in which the needle valve body 41 approaches the annular valve seat 24. It is energizing.

On the end surface of the rod 60 on the motor 110 side, a female threaded portion 64 with a female thread cut on the inner periphery is bored in the axial direction of the rod 60, and this female threaded portion 64 connects to the male threaded portion 82 of the feed screw member 80. By meshing with each other, the rod 60 is screwed onto the feed screw member 80 with some play. Accordingly, when the feed screw member 80 is rotated by the motor 110, the rod 60 is screw-fed and can be moved in the vertical direction in the figure. Note that since play is provided between the female threaded portion 64 and the male threaded portion 82 for the above-mentioned screwing, the rod 60 has a degree of freedom that allows it to tilt with respect to the central axis of the feed screw member 80. ing. This degree of freedom prevents the feed screw member 80 from interfering with the inclination of the rod 60 within the guide portion 121.

A needle valve body 41 is connected to the end of the rod 60 on the valve body 20 side, and as shown in FIG. 1, the central axis CL1 of the rod 60 and the central axis CL3 of the needle valve body 41 are aligned. . The needle valve body 41 is formed into a cylindrical shape by injection molding or cutting, and is made of a fluororesin (for example, polytetrafluoroethylene (PTFE) or tetrafluorocarbon resin with excellent sliding properties and chemical resistance). It is an ethylene/perfluoroalkyl vinyl ether copolymer (PFA).

A thin film portion 42 is provided on the outer peripheral edge of the needle valve body 41. The thin film portion 42 divides the valve chamber 22 into a space in the guide portion 121 and a space on the annular valve seat 24 side, and prevents liquid within the valve chamber 22 from flowing into the guide portion 121. Further, an annular fixing part 43 is provided on the outer peripheral edge of the thin film part 42, and when this fixing part 43 is held between the valve body 20 and the first cylinder member 120, the needle valve body 41 is fixed. Fixed. Furthermore, the needle valve body 41 includes a diameter-reducing portion 41a that reduces the diameter of the needle valve body 41 toward the end opposite to the rod 60 side. This reduced diameter portion 41a is located so as to face the annular valve seat 24 of the valve body 20.

The central axis CL3 of the needle valve body 41 and the central axis CL2 of the annular valve seat 24 are preferably located coaxially, as shown in FIG. 1, but due to manufacturing tolerances, the central axis CL3 of the needle valve body 41 Between CL3 and the center axis CL2 of the annular valve seat 24, a minute positional deviation (for example, about a few tenths of a millimeter) may occur in the radial direction of the annular valve seat 24. At this time, the gap between the first rod part 61 of the rod 60 and the guide part 121 described above is the maximum positional deviation amount between the central axis CL3 of the needle valve body 41 and the central axis CL2 of the annular valve seat 24, which can be considered due to manufacturing tolerances. is set larger than . In other words, the gap between the first rod part 61 and the guide part 121 is set to a value ((D12-D11)/2) that is half the value obtained by subtracting the diameter D11 of the first rod part 61 from the inner diameter D12 of the guide part 121. This means that the gap is set larger than the maximum positional deviation amount.

The needle valve 1 as described above operates as follows. The needle valve 1 shown in FIG. 1 is in a state where the degree of opening of the needle valve body 41 with respect to the annular valve seat 24 (hereinafter simply referred to as the degree of opening) is minimized, that is, the needle valve body 41 is in contact with the annular valve seat 24. The valve is in the closed state. The operation of increasing the opening degree from this valve closed state will be explained.

The drive shaft 111 of the motor 110 is controlled based on the number of steps input to the drive circuit 112, as described above. When the drive shaft 111 is rotated about the central axis CL4 in the direction of arrow X in FIG. do. The rotation of the feed screw member 80 is, in other words, the rotation of the male threaded portion 82, and as the male threaded portion 82 is rotated in the direction of arrow The screw is fed in the direction toward which it approaches. That is, the rod 60 moves upward in FIG. 1, and the rod 60 and the feed screw member 80 approach each other. As the rod 60 moves upward, the needle valve body 41 moves in a direction away from the annular valve seat 24. Therefore, the distance between the annular valve seat 24 and the needle valve body 41, that is, the opening degree, is adjusted, and the flow rate of the chemical liquid flowing into the output side flow path 23 is adjusted. In addition, since the engaging member 90 and the feed screw member 80 can move relative to each other in the axial direction of the drive shaft 111, when the rod 60 is screw fed, the reaction of the force is exerted on the drive shaft 111. Acting in the axial direction is suppressed.

Next, the operation of reducing the opening degree of the needle valve 1 will be explained.

The drive shaft 111 of the motor 110 is controlled based on the number of steps input to the drive circuit 112, as in the case of increasing the opening degree. When the drive shaft 111 is rotated about the central axis CL4 in the direction of the arrow Y in FIG. Rotate in the Y direction. In this case, the female threaded portion 64 of the rod 60 that is engaged with the male threaded portion 82 is threaded in a direction away from the drive shaft 111 . That is, the rod 60 moves downward in FIG. 1, and the rod 60 and the feed screw member 80 are separated. As the rod 60 moves downward, the needle valve body 41 moves in a direction closer to the annular valve seat 24. Therefore, the distance between the annular valve seat 24 and the needle valve body 41, that is, the opening degree, is adjusted, and the flow rate of the chemical liquid flowing into the output side flow path 23 is adjusted.

When adjusting the opening degree, the rotational position of the drive shaft 111 is precisely controlled based on the number of steps of the motor 110, so the needle valve 1 can precisely control the opening degree with an accuracy of several μm. can. For example, when controlling the chemical liquid to a predetermined minute flow rate (for example, 1 to 10 ml/min), the opening degree of the needle valve body 41 with respect to the annular valve seat 24 is determined by the gap between the needle valve body 41 and the annular valve seat 24. is adjusted to a minute opening of several tens of μm or less.

When adjusted to such a minute opening degree, the central axis CL3 of the needle valve body 41 and the central axis CL2 of the annular valve seat 24 are located coaxially, and the diameter-reduced portion 41a of the needle valve body 41 is It is desirable that a uniform gap be formed between the annular valve seat 24 and the annular valve seat 24 over the entire circumference. However, in reality, due to manufacturing tolerances, etc., there is a slight difference (for example, 0 comma number (on the order of mm) may occur. In this case, when the opening degree is adjusted to a small degree, a uniform gap is not formed between the reduced diameter part 41a and the annular valve seat 24 around the entire circumference, and a part of the reduced diameter part 41a meets the annular valve seat 24. There is a risk of contact (that is, uneven contact). Since the needle valve 1 repeatedly makes small adjustments to the opening degree while controlling the flow rate, when uneven contact occurs, the area where the uneven contact occurs will rub against the annular valve seat 24, causing uneven contact. There is a risk of wear occurring where the

However, the needle valve 1 according to the present embodiment can suppress the occurrence of wear even when the needle valve body 41 hits the annular valve seat 24 unevenly. This will be explained in detail below.

Since there is a gap between the first rod part 61 and the guide part 121 and a play between the female thread part 64 and the male thread part 82, the rod 60 has a degree of freedom that allows it to tilt with respect to the central axis CL2 of the annular valve seat 24. We are prepared. Since the rod 60 has a degree of freedom, if the above-mentioned uneven contact occurs on the needle valve body 41, as shown in FIG. can be tilted against. When tilted, the inclination angle θ of the central axis CL1 of the rod 60 with respect to the central axis CL2 of the annular valve seat 24 is preferably 2 degrees or more and 6 degrees or less, and preferably 3 degrees or more and 5 degrees or less. Even more desirable. This inclination angle θ determines the gap between the first rod portion 61 and the guide portion 121 of the rod 60, and the maximum positional deviation between the central axis CL3 of the needle valve body 41 and the central axis CL2 of the annular valve seat 24, which can be considered due to manufacturing tolerances. This is ensured by setting it larger than the amount.

By inclining the rod 60 and the needle valve body 41 with respect to the center axis CL2 of the annular valve seat 24, it becomes possible to release the thrust of the motor 110 that tries to operate the rod 60 and the needle valve body 41, and one side Due to the contact, the contact pressure applied from the annular valve seat 24 to the needle valve body 41 is relieved. If the degree of freedom of the rod 60 is very small and the inclination angle θ is very small (1 degree or less), or if the rod 60 has no degree of freedom and cannot be tilted, it may be caused by uneven contact. The contact pressure applied from the annular valve seat 24 to the needle valve body 41 is considered to be 50 N or more due to the thrust of the motor 110, but due to the inclination of the rod 60, the contact pressure is applied to the elastically deformed thin film portion 42. The reaction force is reduced to approximately 2 to 3 N. As described above, if the contact pressure can be reduced to about the reaction force of the thin film portion 42, even if uneven contact occurs, since the needle valve body 41 is made of a fluororesin with high sliding properties. It is possible to prevent wear caused by friction between the needle valve body 41 and the annular valve seat 24.

Below, the results of a comparative evaluation of the degree of wear on the needle valve body between the needle valve 1 according to the present embodiment and a conventional needle valve will be described. The conventional needle valves are conventional product A and conventional product B (see FIG. 3). Conventional product A is a needle valve in which the degree of freedom of the rod is very small and the inclination angle θ is very small (1 degree or less). Conventional product B is a needle valve that has no flexibility due to the rod being rigidly fixed and cannot be tilted.

In order to evaluate the degree of wear on the needle valve body, a test circuit shown in FIG. 6(a) was used. This test circuit is configured as follows. Starting from the upstream ultrapure water supply source 200, there are a pump 201 for supplying ultrapure water from the ultrapure water supply source 200 to the test circuit, and a flow rate control device 202 for controlling the flow rate of ultrapure water to 250 ml/min. and a filter 203 that filters particles of 10 nm or more are connected in series. Further, on the downstream side of the filter 203, a needle valve 204A (sample 1) and a needle valve 204B (sample 2) to be evaluated are connected in parallel. Note that the needle valve 204A and the needle valve 204B are the same needle valve. For example, when evaluating needle valve 1, needle valve 204A and needle valve 204B are both needle valve 1, and when evaluating conventional product A, both needle valve 204A and needle valve 204B are This is conventional product A. A liquid particle counter (LPC) 205 is connected to the downstream side of the needle valves 204A and 204B, and detects particles with a size of 40 nm or more contained in the ultrapure water that has passed through the needle valves 204A and 204B. It is now detectable. A flow rate control device 206 is connected to the LPC 205 and controls the flow rate of ultrapure water discharged from the LPC 205 to 5 ml/min.

Using the above test circuit and supplying ultrapure water, the needle valve 204A (sample 1) and the needle valve 204B (sample 2) are operated for one cycle every 2 seconds as shown in FIG. 6(b). (The valve opening operation is performed for 1 second and the valve closing action is performed for 1 second), and the degree of wear on the needle valve body 41 is determined based on the number of particles detected by the submerged particle counter 205. In other words, the larger the number of particles detected by the liquid particle counter 205, the more wear has occurred on the needle valve element 41, and the smaller the number of particles, the more it is judged that the wear on the needle valve element 41 is suppressed. . Note that the term "valve closed" shown in FIG. 6(b) does not mean a completely closed state in which the diameter-reduced portion 41a of the needle valve body 41 is in contact with the annular valve seat 24; This means a state in which the gap between the valve body 41 and the annular valve seat 24 is adjusted to a minute opening of several tens of micrometers or less, and the flow rate of ultrapure water is controlled to a minute flow rate of 4 ml/min. Further, the wording "valve open" in FIG. 6(b) means a fully open valve state in which the needle valve body 41 is at the upper limit position.

As a result of testing under the above conditions, the needle valve 1 detected only a few particles about every 5000 cycles from the start of operation (0 cycle) to 30000 cycles.

In addition, with conventional product A, 5 to 10 particles were detected more frequently than needle valve 1 from the start of operation (cycle 0) to 30,000 cycles, and in addition, particles were detected several times every 5,000 cycles. , more than 10 or 20 particles were detected.

Furthermore, with conventional product B, 5 or more particles are almost always detected from the start of operation (0 cycle) to 30,000 cycles, and cases of exceeding 30, 40, and 50 particles have also been confirmed. Ta.

FIG. 3 is a graph showing the average number of particles of the needle valve 1 according to the present embodiment and the conventional products A and B after the 5000th cycle. From this graph, it can be seen that the needle valve 1 has an average value of less than 1, the conventional product A has an average of about 2, and the conventional product B has an average of about 16. The number of needle valves 1 is less than half that of conventional product A, and one-sixteenth of the number of needle valves 1 compared to conventional product B. It can be seen that it is much more suppressed than product B.

From the above test results, it can be seen that the lower the degree of freedom of the rod, the greater the number of particles detected. This occurs when the gap between the needle valve body and the annular valve seat is adjusted to a minute opening of several tens of μm or less in needle valve 1, conventional product A, and conventional product B (i.e., as shown in FIG. 6(b)). This is because the lower the degree of freedom of the rod, the more likely the needle valve body is to wear out due to uneven contact.

That is, since the needle valve 1 has a degree of freedom that allows the rod 60 to tilt with respect to the central axis CL2 of the annular valve seat 24, the thrust of the motor 110 that attempts to operate the rod 60 and the needle valve body 41 The contact pressure applied from the annular valve seat 24 to the needle valve body 41 due to the uneven contact is alleviated, and wear of the needle valve body 41 is suppressed. On the other hand, in the conventional product A, since the degree of freedom of the rod is smaller than that of the needle valve 1, the thrust of the motor 110 cannot be completely released, and it is considered that wear occurs on the needle valve body due to uneven contact. In addition, in conventional product B, since the rod does not have a degree of freedom, the thrust force of the motor 110 is applied to the part where the needle valve body partially hits, and it is thought that more wear than in conventional product A occurs.

The degree of freedom of the rod in Conventional Product A and Conventional Product B is reduced in order to improve the straightness of the rod, and to prevent the central axes of the rod and needle valve body from wobbling due to fluid pressure. The purpose is to This is because it was thought that if the central axes of the rod and the needle valve body deviate due to fluid pressure, this would have an adverse effect on flow control. In this case, since the needle valve 1 according to the present embodiment has a degree of freedom in which the rod 60 can be tilted, the central axes of the rod 60 and the needle valve body 41 are deviated due to fluid pressure, which adversely affects flow control. There is concern that there is. However, the applicant has confirmed through experiments that the needle valve 1 can perform fluid control with the same accuracy as a conventional needle valve.

FIG. 4 is a graph comparing the relationship between the number of steps of the motor (opening degree of the needle valve body) and the Cv value between the needle valve 1 according to the present embodiment and the conventional product A. This graph shows the Cv value from a completely valve open state (step number 0) to a completely valve closed state (step number 400). Looking at this graph, it can be seen that needle valve 1 smoothly moves from the fully open state (step number 0) to the completely valve closed state (step number 400) with the same linearity as conventional product A. It can be seen that the value is decreasing.

FIG. 5 is an enlarged graph from step number 380 to step number 400 in FIG. Looking at this graph, it can be seen that needle valve 1 has the same linearity as conventional product A even when the needle valve body is controlled to a minute opening from step number 380 to step number 400. , it can be seen that the Cv value is decreasing smoothly.

As described above, the needle valve 1 has the same linearity as the conventional product A from the fully open state (step number 0) to the completely closed state (step number 400) without any disturbance in the Cv value. Since the Cv value decreases smoothly, it can be said that the needle valve 1 can perform fluid control with the same accuracy as the conventional needle valve.

As explained above, according to the flow control valve (needle valve 1) of this embodiment,
(1) A drive device (for example, motor 110), a rod 60 that is moved by the operation of the drive device, and a needle valve body 41 that is connected to the rod 60 and moves forward and backward with respect to the annular valve seat 24 as the rod 60 moves. In a flow control valve (needle valve 1) that controls the flow rate of a control fluid (for example, a chemical solution) by adjusting the opening degree of the needle valve body 41 with respect to the annular valve seat 24, the rod 60 is provided with a gap. ((D12-D11)/2) and includes a guide part 121 that guides the movement of the rod 60. The rod 60 is provided with a body (for example, an O-ring 77) and is slidably held with respect to the guide portion 121, and the rod 60 is attached to the annular valve seat with the elastic body (the O-ring 77) as a fulcrum at least through a gap. 24 has a degree of freedom that can be tilted with respect to the central axis CL2, the opening degree is adjusted to a minute opening degree in order to control the control fluid to a predetermined minute flow rate, and the needle valve body 41 is attached to the annular valve seat 24. On the other hand, when there is a partial contact, the rod 60 is inclined due to the degree of freedom, so that the contact pressure applied to the needle valve body 41 due to the partial contact is alleviated.

According to the flow control valve (needle valve 1) described in (1), the rod 60 is inserted through the guide portion 121 with a gap, and at least the gap allows the rod 60 to be aligned with the center axis CL2 of the annular valve seat 24. It has a degree of freedom that allows it to be tilted. Due to this degree of freedom, the opening degree is adjusted to a minute degree in order to control the control fluid to a predetermined minute flow rate, and even if the needle valve body 41 hits the annular valve seat 24 unevenly, the rod 60 is tilted. can do. If the rod 60 can be tilted, even if uneven contact occurs, it will be possible to release the thrust of the driving device that operates the rod 60 and the needle valve body 41, and the uneven contact will cause the needle to move away from the annular valve seat 24. The contact pressure applied to the valve body 41 is relieved. Therefore, even if the needle valve body 41 hits the annular valve seat 24 unevenly, it is possible to suppress the occurrence of wear.

If the occurrence of wear can be suppressed, the generation of wear powder can be suppressed, and, for example, it is possible to prevent particles from being mixed into a control fluid such as a chemical solution. Furthermore, in the past, even if the needle valve element was adjusted to the same opening degree, the flow rate of the chemical solution would change before and after the needle valve element wore out, which could cause the concentration of the chemical solution to fluctuate. However, if the occurrence of wear can be suppressed, this risk will also be reduced. Preventing particles from entering the chemical solution and reducing the possibility of fluctuations in the concentration of the chemical solution can prevent the occurrence of manufacturing defects in wafers.

It should be noted that the fact that the rod 60 can be tilted means that the axis of the needle valve body 41 is deviated by the fluid pressure, which is considered to have an adverse effect on flow control. It has been confirmed that the described flow control valve (needle valve 1) can perform fluid control with the same accuracy as a conventional flow control valve.

(2) In the flow control valve (needle valve 1) described in (1), when the needle valve body 41 makes partial contact with the annular valve seat 24, the inclination of the rod 60 due to the degree of freedom is 2 degrees or more 6 It is characterized by being within a range of less than 1 degree.

According to the flow control valve (needle valve 1) described in (2), even if the needle valve body 41 hits the annular valve seat 24 unevenly, it is possible to suppress the occurrence of wear. For example, as in the above-mentioned conventional product A, if the needle valve body 41 makes partial contact with the annular valve seat 24 and the inclination of the rod 60 is less than 2 degrees (for example, 1 degree), the thrust of the drive device will be released. There is a risk that the needle valve element 41 will wear out due to the contact pressure applied to the needle valve element 41. Further, if the needle valve body 41 is tilted at an angle larger than 6 degrees, the movement of the needle valve body 41 due to the fluid pressure (90 kPa) becomes excessive, which may cause vibrations and abnormal noises. Therefore, it is desirable that the inclination of the rod 60 due to the degree of freedom is within a range of 2 degrees or more and 6 degrees or less.

(3) In the flow control valve (needle valve 1) described in (1) or (2), the drive device is a motor 110 having a drive shaft 111; The rod 60 is connected to a feed screw member 80 that converts the motion into a linear motion, and the rod 60 is screwed to the feed screw member 80 with play, and the degree of freedom is ensured by the gap and play. , is characterized by.

According to the flow control valve (needle valve 1) described in (3), the rod 60 is movable by the feed screw member 80 converting the rotational motion of the drive shaft 111 into a direct motion motion. The rod 60 is screwed onto the feed screw member 80 with some play. In other words, due to the play, the rod 60 is coupled to the feed screw member 80 with a degree of freedom. Therefore, the degree of freedom in which the rod 60 can tilt with respect to the central axis CL2 of the annular valve seat 24 is ensured by the degree of freedom due to the gap between the rod 60 and the guide portion 121 and the degree of freedom due to the above-mentioned play. . Since the degree of freedom that allows the rod 60 to tilt relative to the central axis CL2 of the annular valve seat 24 is ensured, even if the needle valve body 41 hits the annular valve seat 24 unevenly, wear will not occur. It is possible to suppress the

Note that the above embodiments are merely illustrative and do not limit the present invention in any way. Therefore, it goes without saying that various improvements and modifications can be made to the present invention without departing from the spirit thereof. For example, in the above embodiment, the motor 110 is illustrated as the drive device, but the drive device is not limited to this, and the drive device can be manually operated with a handle or the like, and the flow control valve is a manual valve. It's good as well.

Moreover, although the O-ring 77 is illustrated as an annular elastic body, a sealing member such as a Y-shaped packing or a square-shaped packing may also be used. Furthermore, the annular elastic body is not limited to a member whose purpose is to seal between the rod 60 and the guide part 121, but to hold the rod 60 slidably with respect to the guide part 121. It is also possible to use a member whose sole purpose is to do so.

Furthermore, although a diluted chemical solution is exemplified as the control fluid, it is also possible to control a chemical solution that is not used for dilution (for example, an organic solvent for drying wafers (for example, isopropyl alcohol)).

1 Needle valve (an example of a flow control valve)
24 Annular valve seat 41 Needle valve body 60 Rod 77 O-ring (an example of elastic body)
110 Motor (an example of a drive device)
121 Guide part CL2 Center axis of annular valve seat

Claims (3)

A driving device, a rod that is moved by the operation of the driving device, and a needle valve body that is connected to the rod and moves forward and backward with respect to an annular valve seat by the movement of the rod, In a flow control valve that controls the flow rate of a control fluid by adjusting the opening degree with respect to an annular valve seat,
The rod is inserted through the rod with a gap, and includes a guide portion that guides movement of the rod;
The rod includes an annular elastic body on the outer circumferential surface of a portion inserted into the guide portion, and is slidably held with respect to the guide portion;
The rod has a degree of freedom that allows the rod to tilt with respect to the central axis of the annular valve seat with the elastic body as a fulcrum, due to at least the gap;
In order to control the control fluid to a predetermined minute flow rate, the opening degree is adjusted to a minute opening degree, and when the needle valve body makes partial contact with the annular valve seat, the degree of freedom allows the rod to is inclined, thereby relieving the contact pressure applied to the needle valve body due to the uneven contact;
A flow control valve featuring: The flow control valve according to claim 1,
When the needle valve body makes one-sided contact with the annular valve seat, the inclination of the rod due to the degree of freedom is within a range of 2 degrees or more and 6 degrees or less;
A flow control valve featuring: The flow control valve according to claim 1 or 2,
The drive device is a motor having a drive shaft;
A feed screw member is connected to the drive shaft, and the feed screw member converts rotational motion of the drive shaft into linear motion;
the rod is screwed onto the feed screw member with play;
the degree of freedom is ensured by the gap and the play;
A flow control valve featuring:

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