Piezoelectric actuator, valve, and flow rate control device

Abstract

A piezoelectric actuator according to the present invention comprises: a piezoelectric element; a cap that is provided so as to cover the upper end portion of the piezoelectric element; a through hole that is formed in the cap and includes a screw hole; an adjustment screw that is screwed into the screw hole; a lock nut that is screwed onto the adjustment screw; two recessed grooves that are formed on each among a pair of side surfaces in the width direction orthogonal to the longitudinal direction of the cap in a plan view; and two cables respectively and entirely accommodated in the two recessed grooves so as to be electrically connected to the piezoelectric element. The two recessed grooves are formed so as to not be arranged on a straight line that passes through the center of the screw hole and extends along the width direction in the plan view.

Description

Piezoelectric Actuator, Valve and Flow Control Device

[0001] The present invention relates to a piezoelectric actuator, a valve and a flow control device.

[0002] JP 6799859B discloses a valve including a piezoelectric actuator, and a flow control device including the valve.

[0003] However, in the piezoelectric actuator described in Patent Document 1, the pair of recessed grooves formed on the pair of lateral side surfaces in the width direction of the cap covering the upper end portion of the piezoelectric element are arranged on a straight line that passes through the center of the circular hole formed in the cap and extends along the width direction. Therefore, the depth of the recessed grooves cannot be increased, and the cable accommodated in the recessed grooves protrudes from the recessed grooves. As a result, the cable comes into contact with the case of the flow control device provided on the outer peripheral side of the cap, so frictional resistance is generated (or increased) when the valve is opened and closed. The generation (or increase) of such frictional resistance adversely affects the control of the fluid flow rate of the valve. As a result, there is a possibility that the fluid flow rate of the valve cannot be controlled with high accuracy.

[0004] Furthermore, in the piezoelectric actuator described in Patent Document 1, as described above, the pair of recessed grooves are arranged on a straight line that passes through the center of the circular hole and extends along the width direction. Therefore, sufficient reduction in the width-direction thickness of the cap (piezoelectric actuator, valve or flow control device) cannot be achieved.

[0005] Accordingly, the present invention has been made focusing on this problem, and an object of the present invention is to provide a piezoelectric actuator, a valve, and a flow control device that can achieve reduction in width-direction thickness and accurately control a fluid flow rate.

[0006] According to one aspect of the present invention, a piezoelectric actuator for use in a valve is provided, comprising: a piezoelectric element; a cap provided to cover the upper end of the piezoelectric element; a hole formed in the cap having a screw hole; an adjustment screw screwed into the screw hole; two grooves formed on each of a pair of sides in the width direction perpendicular to the longitudinal direction of the cap in a plan view; and two cables, in a plan view, entirely housed in each of the two grooves so as to be electrically connected to the piezoelectric element, wherein the two grooves are formed such that, in a plan view, they do not pass through the center of the screw hole and are not aligned on a straight line extending along the width direction.

[0007] According to this embodiment, the fluid flow rate of the valve can be controlled accurately while reducing the width of the cap (piezoelectric actuator, valve, or flow control device).

[0008] Figure 1 is a cross-sectional view showing a flow control device according to this embodiment. Figure 2 is a front view showing a piezoelectric actuator of a valve constituting the flow control device. Figure 3 is a plan view showing the piezoelectric actuator. Figure 4 is a perspective view showing a cap constituting the piezoelectric actuator. Figure 5 is a plan view showing a cap constituting the piezoelectric actuator. Figure 6 is a bottom view showing a cap constituting the piezoelectric actuator. Figure 7 is a plan view showing a cap according to a first modified example. Figure 8 is a plan view showing a cap according to a second modified example.

[0009] Hereinafter, embodiments of the present invention (hereinafter referred to as "these embodiments") will be described with reference to the attached drawings. Throughout this specification, the same elements will be denoted by the same reference numerals.

[0010] (Configuration of the flow control device) First, the flow control device 100 according to this embodiment will be described with reference to Figure 1.

[0011] Figure 1 is a cross-sectional view showing the flow rate control device 100 according to this embodiment. Note that some components are not shown in cross-sectional view in Figure 1.

[0012] As shown in Figure 1, the flow rate control device 100 according to this embodiment is a flow rate control device used in a fluid supply unit that serves as a fluid supply means for supplying process gas or the like as a fluid from a fluid supply source (not shown) to semiconductor manufacturing equipment (CVD equipment, sputtering equipment, etching equipment, etc.) (not shown).

[0013] As shown in Figure 1, the flow control device 100 comprises a valve 1, an orifice 3 (specifically, a gasket-type orifice) interposed in the flow path 11a of a flow path forming block 11 (described later) of the valve 1, an upstream pressure detector 4 for detecting the pressure in the flow path 11a upstream of the orifice 3, an inlet-side block 6 connected to the flow path forming block 11 by fixing bolts via a sealing gasket 5 and having an inlet-side flow path 61 communicating with the flow path forming block 11 upstream of the flow path forming block 11, an outlet-side block 7 connected to the flow path forming block 11 by fixing bolts and having an outlet-side flow path 71 communicating with the flow path 11a downstream of the flow path forming block 11, and provided with a downstream pressure detector 8 for detecting the pressure in the outlet-side flow path 71, a case 9 housing a piezoelectric actuator 2 (described later) of the valve 1, and a control unit (not shown) for controlling the opening and closing of the valve 1 based on the detected values ​​of each pressure detector 4, 8.

[0014] Note that the orifice 3, pressure detector 4, inlet-side block 6, outlet-side block 7, pressure detector 8, and control unit are the same as those described in Patent Document 1, so their descriptions will be omitted. In this embodiment, the case 9 is provided to cover only the piezoelectric actuator 2, but it is not limited to this, and for example, it may be provided to cover from the left side of the inlet-side flow path 61 of the inlet-side block 6 to the right side of the pressure detector 8.

[0015] As shown in Figure 1, the valve 1 comprises a flow path forming block 11 in which a flow path 11a is formed, a piezoelectric actuator 2 attached to the flow path forming block 11 by fixing bolts, an output section 12 which also serves as the output section of the piezoelectric actuator 2 described later, a diaphragm retainer 13 provided at the lower end of the output section 12, and a diaphragm 14 as a valve body that opens and closes the flow path 11a of the flow path forming block 11 by operating the output section 12 to which the diaphragm retainer 13 is provided.

[0016] (Configuration of the piezoelectric actuator) Next, the piezoelectric actuator 2 will be described with reference to Figures 1 to 3.

[0017] Figure 2 is a front view showing the piezoelectric actuator 2. Figure 3 is a top view showing the piezoelectric actuator. Note that the fixing screws 25 and cables are not shown in Figures 2 and 3.

[0018] As shown in Figures 1 to 3, the piezoelectric actuator 2 according to this embodiment includes a piezoelectric element 20 stacked in a columnar shape (specifically, a cylindrical shape), two cables (not shown) that electrically connect a voltage supply source and the piezoelectric element 20 and apply voltage from the voltage supply source (not shown) to the piezoelectric element 20, a lower support member 21 that supports the piezoelectric element 20 and extends on both sides of the piezoelectric element 20, a plate-shaped (disc-shaped) pressing member 22 that presses the piezoelectric element 20 from above, a pair of displacement transmission members 23 that extend along both sides of the piezoelectric element 20, intersect the lower support member 21 so as to be vertically movable and transmit the displacement due to the piezoelectric effect of the piezoelectric element 20, and a member that connects the upper ends of the pair of displacement transmission members 23 and covers the upper end of the piezoelectric element 20. The device comprises a cap 24 provided therein, a fixing screw 25 (see Figure 1) for fixing the cap 24 to the upper end of a pair of displacement transmission members 23, an adjustment screw 26 that is screwed onto the cap 24 and can adjust the relative height position of the pair of displacement transmission members 23 with respect to the pressing member 22 by screwing it onto the cap 24 and pressing the pressing member 22, a lock nut 27 that is screwed onto the adjustment screw 26 and locks the adjustment screw 26 onto the cap 24, an output unit 12 that is engaged with the pair of displacement transmission members 23 below the lower support member 21 and connects the lower ends of both displacement transmission members 23, an elastic body 28 interposed between the lower support member 21 and the output unit 12 and biasing the output unit 12 downward, and a bonnet 29 to which the lower support member 21 is fixed.

[0019] The piezoelectric actuator 2 is installed on the flow path forming block 11 by fixing the lower support member 21 and the bonnet 29 to the flow path forming block 11 with fixing bolts.

[0020] As shown in Figures 1 and 2, the pressing member 22 is positioned vertically between the piezoelectric element 20 and the plate portion 241 of the cap 24 (see Figures 4 and 5), which will be described later. A pair of notches 221 are formed in the pressing member 22.

[0021] Note that the piezoelectric element 20, lower support member 21, pressing member 22, displacement transmission member 23, fixing screw 25, adjustment screw 26, lock nut 27, elastic body 28, and bonnet 29 are the same as those described in Patent Document 1, so their descriptions are omitted.

[0022] (Key parts of the piezoelectric actuator) Next, the cap 24, which is a key part of the piezoelectric actuator 2, will be described in detail with reference to Figures 1 to 5.

[0023] Figure 4 is a perspective view showing the cap 24. Figure 5 is a plan view showing the cap 24. Figure 6 is a bottom view showing the cap 24.

[0024] As shown in Figures 1 to 6, the cap 24 comprises a plate portion (specifically, a flat plate portion) 241 having a pair of side surfaces 241a (specifically, side planes) extending along the longitudinal direction, and a pair of arcuate wall portions 242 provided at both ends of the plate portion 241. Each arcuate wall portion 242 has a perforation 242a through which a fixing screw 25 can pass.

[0025] As shown in Figures 4 to 6, a through hole 241c is formed in the center of the plate portion 241, through which an adjustment screw 26 can pass. In this embodiment, the through hole 241c is composed of a large-diameter circular hole 241d formed recessed from the upper surface, which is one side of the plate portion 241, and a small-diameter circular hole 241e formed recessed from the lower surface, which is the other side of the plate portion 241, as a screw hole. However, it is not limited to this, and for example, it may be composed only of a screw hole that engages with the adjustment screw 26.

[0026] The large-diameter circular hole 241d and the small-diameter circular hole 241e are formed coaxially so as to communicate with each other. The large-diameter circular hole 241d does not have an internal thread, while the small-diameter circular hole 241e has an internal thread. As a result, an adjustment screw 26 is screwed into the internal thread of the small-diameter circular hole 241e. A lock nut 27 is then screwed onto the adjustment screw 26.

[0027] Each of the pair of side surfaces 241a of the plate portion 241 has two grooves 241f formed therein. At least a portion of each groove 241f is exposed in a plan view from the lock nut 27 that is screwed onto the adjustment screw 26. Two cables that apply voltage to the piezoelectric element 20 pass through the plate portion 241 so that in a plan view, their entirety is housed within the two grooves 241f.

[0028] The two grooves 241f are formed such that, in a plan view, they are not aligned on a straight line that passes through the center of the small-diameter circular hole 241e and extends along the width direction (hereinafter also simply referred to as the width direction) perpendicular to the longitudinal direction. This makes it possible to reduce the distance between the two grooves 241f in the width direction without increasing the width dimension of the cap 24 (piezoelectric actuator 2, valve 1, and flow control device 100), and to form deeper grooves 241f. As a result, it is possible to prevent the cable from protruding from the groove 241f in which it is housed.

[0029] In this embodiment, the two grooves 241f are positioned on one side of the through hole 241c in the longitudinal direction (specifically, on the right side in Figure 3) so as to be aligned along the width direction in a plan view. This allows the two grooves 241f to be formed together in one location.

[0030] As shown in Figure 3, the lock nut 27 screwed onto the adjustment screw 26 and the groove 241f are formed so that a portion of them overlaps in both the width direction and the longitudinal direction. This allows for a smaller width dimension of the cap 24 and a deeper groove 241f compared to a configuration where the lock nut 27 and the groove 241f do not overlap in both the width direction and the longitudinal direction, thereby preventing the cable from protruding from the groove 241f in which it is housed. As a result, contact between the portion of the cable that penetrates the plate portion 241 and the case 9 of the flow control device 100 (specifically, the wall surface of the case 9 facing the groove 241f) provided on the outside of the cap 24, and frictional resistance when opening and closing the valve 1 due to such contact can be avoided, enabling precise control of the fluid flow rate of the valve 1.

[0031] As described above, the two grooves 241f are formed so that, in a plan view, they do not pass through the center of the small-diameter circular hole 241e and are not aligned on a straight line extending along the width direction. Therefore, without increasing the width dimension of the cap 24, the distance between the two grooves 241f in the width direction can be reduced, and the grooves 241f can be made deeper. As a result, in this embodiment, the lock nut 27 protrudes from the pair of side surfaces 241a in a plan view. This makes it possible to make the cap 24 (piezoelectric actuator 2, valve 1, and flow control device 100) thinner in the width direction compared to a configuration in which the lock nut 27 does not protrude from the pair of side surfaces 241a.

[0032] As shown in Figure 5, the two grooves 241f and the through hole 241c (specifically, the large-diameter circular hole 241d) are formed so that a portion of them overlaps along both the width and longitudinal directions. This allows for a smaller width dimension of the cap 24 and a deeper groove 241f compared to a configuration where the two grooves 241f and the through hole 241c do not overlap along both the width and longitudinal directions, thereby preventing the cable from protruding from the groove 241f in which it is housed. As a result, contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and frictional resistance during opening and closing of the valve 1 due to such contact, can be avoided, enabling precise control of the fluid flow rate of the valve 1.

[0033] As shown in Figure 5, the groove 241f is not a semicircular shape surrounding half of the cable's outer circumference, nor an arc shape surrounding a small portion of the cable's outer circumference (i.e., less than half of the cable's outer circumference), but rather a C-shape surrounding most of the cable's outer circumference (i.e., more than half of the cable's outer circumference) in a plan view.

[0034] As a result, the groove 241f can be formed deeper than in a configuration where the groove 241f surrounds less than half of the outer circumference of the cable, thus further suppressing the cable from protruding from the groove 241f in which it is housed. Consequently, contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and frictional resistance during opening and closing of the valve 1 due to such contact, can be better avoided, and the fluid flow rate of the valve 1 can be controlled with greater precision.

[0035] Furthermore, in a plan view, it is preferable that the width H of the opening in the groove 241f, as shown in Figure 5, is smaller than the diameter of the cable. This prevents the cable from slipping out of the groove 241f.

[0036] Furthermore, as shown in Figure 6, the groove 241f is formed in a deformed C-shape that extends along the longitudinal direction when viewed from the bottom. The deformed C-shape of the groove 241f includes both a first region A1 that overlaps with the undeformed C-shape (i.e., the C-shape in plan view) and a second region A2 that does not overlap with the undeformed C-shape.

[0037] The second region A2 and the small-diameter circular hole 241e are formed so that a portion of them overlap along the longitudinal direction. The second region A2 and the notch 221 of the pressing member 22 are formed so that a portion of them overlap in a plan view or a bottom view. The first region A1 and the notch 221 are formed so that they do not overlap in a plan view or a bottom view. The notch 221 and the connection point 201, which is electrically connected to the cable of the piezoelectric element 20, are formed so that they overlap in a plan view or a bottom view. In other words, the portion of the upper end surface of the piezoelectric element 20 that is not covered by the pressing member 22 (i.e., the portion of the upper end surface of the piezoelectric element 20 that is exposed from the notch 221 of the pressing member 22 in a plan view) is the connection point 201 that is electrically connected to the cable. As a result, the first region A1 and the connection point 201 are formed so that they do not overlap in a plan view or a bottom view. Furthermore, the lock nut 27 is provided such that, in a plan view or a bottom view, a portion of it overlaps with the second region A2, the notch 221, and the connection point 201.

[0038] The second region A2 has a guide surface 241g for guiding the cable that has passed through the plate portion 241 to the notch 221. In this embodiment, the guide surface 241g is formed as an inclined surface when viewed from the front, but is not limited to this, and may be formed as a curved surface, for example.

[0039] By forming such a guide surface 241g in the second region A2, the cable passing through the plate portion 241 can be guided to the notch 221 which does not overlap with the first region A1 when viewed from below, so that the cable can be easily bent and passed through the pressing member 22 to be accommodated in the notch 221. Then, each cable electrically connected to the voltage supply source is bent and passes through the plate portion 241 and the pressing member 22 in sequence, passing through each groove 241f and each notch 221 in sequence, and is electrically connected to the piezoelectric element 20.

[0040] Since the pressing member 22 does not need to have a screw hole for screwing in with the adjustment screw 26, the pair of notches 221 can be formed as deep as the groove 241f, preventing the cable from protruding from the notch 221 in which it is housed. As a result, contact between the portion of the cable that passes through the pressing member 22 and the case 9, and frictional resistance when opening and closing the valve 1 due to such contact can be better avoided, allowing for more precise control of the fluid flow rate of the valve 1.

[0041] In this embodiment, the groove 241f is formed as a C-shaped groove in a plan view, but it is not limited to this, and may be formed as a U-shaped groove, for example. Even in this case, it is sufficient that the cable is entirely housed in the U-shaped groove 241f in a plan view.

[0042] (Modified Caps) Next, the cap 24 according to each modified form will be described with reference to Figures 7 to 8. In each modified form, points that are the same as the embodiments described above will be omitted, and the points that differ from the embodiments described above will be explained in detail.

[0043] Figure 7 is a plan view showing the cap 24 according to the first modified example. Figure 8 is a plan view showing the cap 24 according to the second modified example.

[0044] In the above-described embodiment, in plan view, the distance d1 in the width direction between the opening of the recessed groove 241f and the bottom of the recessed groove 241f is formed to be smaller than the distance d2 in the width direction between the bottom of one recessed groove 241f and the bottom of the other recessed groove 241f. However, the present invention is not limited to this. For example, as shown in FIG. 7, the distance d1 may be formed to be larger than the distance d2 in the width direction between the bottom of one recessed groove 241f and the bottom of the other recessed groove 241f.

[0045] In this case, the recessed groove 241f can be formed deeper, so that compared with the configuration in which the distance d1 in the width direction between the opening of the recessed groove 241f and the bottom of the recessed groove 241f is formed smaller than the distance d2 in the width direction between the bottom of one recessed groove 241f and the bottom of the other recessed groove 241f, it is possible to further suppress the cable from protruding out of the recessed groove 241f accommodating the cable. As a result, contact between the portion of the cable penetrating through the plate portion 241 and the case 9, and frictional resistance when opening and closing the valve 1 caused by such contact can be further avoided, and the fluid flow rate of the valve 1 can be controlled with higher accuracy.

[0046] In the above-described embodiment, the two recessed grooves 241f are arranged along the width direction, but the present invention is not limited to this. As shown in FIG. 8, one recessed groove 241f may be located on one side (specifically, the left side) in the longitudinal direction relative to the through hole 241c, and the other recessed groove 241f may be located on the other side (specifically, the right side) in the longitudinal direction relative to the through hole 241c.

[0047] In this case, the degree of freedom in forming the two recessed grooves 241f can be improved, and compared with the configuration in which the two recessed grooves 241f are collectively formed at one position, the reduction in the strength of the entire cap 24 caused by the formation of the two recessed grooves 241f can be suppressed.

[0048] (Functions and Effects) Next, the functions and effects of the above-described embodiment and modified examples will be described.

[0049] The piezoelectric actuator 2 according to the above embodiment is used in a valve 1 and comprises a piezoelectric element 20, a cap 24 provided to cover the upper end of the piezoelectric element 20, a through hole 241c formed in the cap 24 having a small diameter circular hole 241e, an adjustment screw 26 screwed into the small diameter circular hole 241e, two grooves 241f formed on each of a pair of sides in the width direction perpendicular to the longitudinal direction of the cap 24 in a plan view, and two cables, in a plan view, entirely housed in each of the two grooves 241f so as to be electrically connected to the piezoelectric element 20, wherein the two grooves 241f are formed so as not to be aligned on a straight line that passes through the center of the small diameter circular hole 241e and extends along the width direction in a plan view.

[0050] The valve 1 according to the above-described embodiment includes a piezoelectric actuator 2 according to the above-described embodiment.

[0051] The flow control device 100 according to the above-described embodiment includes the valve 1 according to the above-described embodiment.

[0052] With these configurations, compared to a configuration in which the two grooves 241f pass through the center of the small-diameter circular hole 241e and are arranged on a straight line extending along the width direction, the distance between the two grooves 241f in the width direction can be reduced without increasing the width dimension of the cap 24 (piezoelectric actuator 2, valve 1, and flow control device 100), and the grooves 241f can be made deeper. As a result, it is possible to prevent the cable from protruding from the groove 241f in which it is housed. Furthermore, it is possible to avoid contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and to avoid frictional resistance when opening and closing the valve 1 due to such contact, thereby enabling precise control of the fluid flow rate of the valve 1.

[0053] Furthermore, in the above-described embodiment, the piezoelectric actuator 2 further includes a lock nut 27 screwed onto the adjustment screw 26, and the lock nut 27 and the groove 241f are formed so that a portion of them overlap along the width direction.

[0054] With this configuration, compared to a configuration in which the lock nut 27 and the groove 241f are formed so as not to overlap along the width direction, the width dimension of the cap 24 can be reduced and the groove 241f can be made deeper, thereby preventing the cable from protruding from the groove 241f in which it is housed. As a result, contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and frictional resistance when opening and closing the valve 1 due to such contact can be avoided, and the fluid flow rate of the valve 1 can be controlled with precision.

[0055] Furthermore, in the embodiment described above, the two grooves 241f are arranged along the width direction and are located on one or the other longitudinal side of the through hole 241c in a plan view.

[0056] This configuration allows two grooves 241f to be formed together in one location.

[0057] Furthermore, in the second modified example described above, one groove 241f is located on one longitudinal side (specifically, the left side) of the through hole 241c, while the other groove 241f is located on the other longitudinal side (specifically, the right side) of the through hole 241c.

[0058] This configuration improves the degree of freedom in forming the two grooves 241f, and also suppresses the reduction in the overall strength of the cap 24 due to the formation of the two grooves 241f, compared to a configuration in which the two grooves 241f are formed together in one place.

[0059] Furthermore, in the embodiment described above, the lock nut 27 and the groove 241f are formed so that a portion of them overlaps along the longitudinal direction.

[0060] With this configuration, compared to a configuration in which the lock nut 27 and the groove 241f are formed so as not to overlap along the longitudinal direction, the groove 241f can be made deeper, thus preventing the cable from protruding from the groove 241f in which it is housed. As a result, contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and frictional resistance when opening and closing the valve 1 due to such contact can be avoided, and the fluid flow rate of the valve 1 can be controlled with precision.

[0061] Furthermore, in the embodiment described above, the through hole 241c and the groove 241f are formed so that a portion of them overlaps along the longitudinal direction.

[0062] With this configuration, compared to a configuration in which the two grooves 241f and the through hole 241c are formed so as not to overlap along the longitudinal direction, the grooves 241f can be made deeper, thus preventing the cable from protruding from the grooves 241f in which it is housed. As a result, contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and frictional resistance when opening and closing the valve 1 due to such contact can be avoided, and the fluid flow rate of the valve 1 can be controlled with precision.

[0063] Furthermore, in the embodiment described above, the lock nut 27 protrudes from a pair of side surfaces 241a in a plan view.

[0064] With this configuration, the cap 24 (piezoelectric actuator 2, valve 1, and flow control device 100) can be made thinner in the width direction compared to a configuration in which the lock nut 27 does not protrude from the pair of side surfaces 241a.

[0065] Furthermore, in the embodiment described above, the through hole 241c and the groove 241f are formed so that a portion of them overlaps along the width direction.

[0066] With this configuration, compared to a configuration in which the two grooves 241f and the through hole 241c are formed so as not to overlap along the width direction, the width dimension of the cap 24 can be reduced and the grooves 241f can be made deeper, thereby preventing the cable from protruding from the grooves 241f in which it is housed. As a result, contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and frictional resistance when opening and closing the valve 1 due to such contact can be avoided, and the fluid flow rate of the valve 1 can be controlled with precision.

[0067] Furthermore, in the embodiment described above, the groove 241f surrounds most of the outer circumference of the cable in a plan view.

[0068] With this configuration, the groove 241f can be formed deeper than in a configuration where the groove 241f surrounds less than half of the outer circumference of the cable, thus further suppressing the cable from protruding from the groove 241f in which it is housed. As a result, contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and frictional resistance when opening and closing the valve 1 due to such contact can be better avoided, and the fluid flow rate of the valve 1 can be controlled with greater precision.

[0069] Furthermore, in the embodiment described above, the groove 241f has an opening width H smaller than the diameter of the cable when viewed from above.

[0070] This configuration prevents the cable from coming out of the groove 241f.

[0071] Furthermore, in the first modified example described above, in a plan view, the distance d1 in the width direction between the opening of the groove 241f and the bottom of the groove 241f is greater than the distance d2 in the width direction between the bottom of one groove 241f and the bottom of the other groove 241f.

[0072] With this configuration, the grooves 241f can be formed deeper, so that the cable does not protrude from the grooves 241f that house it, compared to a configuration in which the widthwise distance d1 between the opening of the grooves 241f and the bottom of the grooves 241f is smaller than the widthwise distance d2 between the bottom of one groove 241f and the bottom of the other groove 241f. As a result, contact between the portion of the cable that penetrates the plate portion 241 and the case 9, and frictional resistance when opening and closing the valve 1 due to such contact can be further avoided, and the fluid flow rate of the valve 1 can be controlled with even greater precision.

[0073] Although this embodiment and its modifications have been described above, the above-described embodiment and modifications only represent a part of the application of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above-described embodiment and modifications.

[0074] This application claims priority based on Japanese Patent Application No. 2025-40753, filed with the Japan Patent Office on 13 March 2025, and all contents of that application are incorporated herein by reference.

[0075] 1 Valve 2 Actuator 20 Piezoelectric element 24 Cap 26 Adjustment screw 27 Lock nut 241c Through hole (hole) 241e Small diameter circular hole (threaded hole) 241f Groove

Claims

1. A piezoelectric actuator for use in a valve, comprising: a piezoelectric element; a cap provided to cover the upper end of the piezoelectric element; a hole formed in the cap having a screw hole; an adjustment screw screwed into the screw hole; two grooves formed on each of a pair of sides in the width direction perpendicular to the longitudinal direction of the cap in a plan view; and two cables, in a plan view, entirely housed in each of the two grooves so as to be electrically connected to the piezoelectric element, wherein the two grooves are formed so as not to be aligned on a straight line passing through the center of the screw hole and extending along the width direction in a plan view.

2. The piezoelectric actuator according to claim 1, further comprising a lock nut screwed onto the adjustment screw, wherein the lock nut and the groove are formed to overlap in part along the width direction.

3. The piezoelectric actuator according to claim 2, wherein the two grooves are arranged along the width direction and are located on one or the other side of the longitudinal direction relative to the hole in a plan view.

4. In a plan view, one of the grooves is located on one side of the hole in the longitudinal direction, and the other groove is located on the other side of the hole in the longitudinal direction, as described in claim 2.

5. The piezoelectric actuator according to claim 2, wherein the hole and the groove are formed such that a portion of them overlaps along the longitudinal direction.

6. The piezoelectric actuator according to claim 1, wherein the hole and the groove are formed such that a portion of them overlaps along the width direction.

7. The piezoelectric actuator according to claim 1, wherein the groove surrounds most of the outer circumference of the cable in a plan view.

8. The piezoelectric actuator according to claim 1, wherein, in a plan view, the width of the opening of the groove is smaller than the diameter of the cable.

9. In a plan view, the distance in the width direction between the opening of the groove and the bottom of the groove is greater than the distance in the width direction between the bottom of one groove and the bottom of the other groove, the piezoelectric actuator according to claim 1.

10. A valve comprising a piezoelectric actuator according to any one of claims 1 to 9.

11. A flow control device comprising the valve described in claim 10.

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