Piezoelectric valve

Abstract

To provide a compact (miniaturized) piezoelectric valve which can be disassembled and regenerated and solves the problem of air leakage.SOLUTION: The piezoelectric valve includes a main body case that houses the valve seat plate, the plurality of actuators each include a valve body, a piezoelectric element that generates, as a displacement, a driving force required for an operation of the valve body, and a displacement enlarging mechanism that enlarges the displacement of the piezoelectric element and applies the enlarged displacement to the valve body, the main body case includes a gas supply port to which compressed gas is supplied, and a plurality of gas discharge ports that individually discharge the compressed gas supplied from the gas supply port via the plurality of discharge paths of the valve seat plate by separation of the plurality of valve bodies and the plurality of valve seats, the valve seat plate is fixed to the main body case at the valve seat portion and a rear portion on a side to which the plurality of actuators are fixed, and a front surface of the valve seat portion is fixed to an inner surface of the main body case by a pressing force from a direction of the rear portion of the valve seat plate.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a piezoelectric valve that opens and closes by utilizing the displacement of a piezoelectric element. [Background technology]

[0002] Piezoelectric valves that use the displacement of a piezoelectric element to open and close the valve and eject compressed gas are known, for example, as disclosed in Patent Documents 1 and 2. Nozzle devices used in fluid devices such as ejectors in granular material sorters are known, for example, as disclosed in Patent Document 3. Optical sorters equipped with piezoelectric valves are known, for example, as disclosed in Patent Document 4.

[0003] The piezoelectric valve disclosed in Patent Document 1 includes a main case having a gas pressure chamber that receives compressed gas supplied from outside, a plate disposed inside the main case, and an actuator fixed to the plate and disposed inside the main case together with the plate. The main case has an open front, and the plate is provided with a gas discharge channel and a valve seat against which a valve element of an actuator that opens and closes the gas discharge channel abuts. A cover that closes the case opening has a gas discharge opening that communicates with the gas discharge channel of the plate, and is welded and fixed to the front surface of the plate where the gas discharge channel of the plate opens by an annular weld surrounding the gas discharge opening, and is welded and fixed to the tip surface of the case by an annular weld on the outer periphery.

[0004] The piezoelectric valve disclosed in Patent Document 2 includes an actuator that drives a valve element, a valve seat plate that has a valve seat and an exhaust passage that move toward and away from the valve element and that secures the actuator, and a main body case that houses the valve seat plate. The actuator includes a valve element, a piezoelectric element that generates the driving force required to operate the valve element as a displacement, and a displacement amplification mechanism that amplifies the displacement of the piezoelectric element and applies it to the valve element. The main body case includes a gas supply port through which compressed gas is supplied, and a gas exhaust port that exhausts the compressed gas supplied from the gas supply port through the exhaust passage in the valve seat plate by separating the valve element from the valve seat. The valve seat plate is fixed to the main body case with screws at the front portion on the side with the exhaust passage and at the rear portion on the side where the actuator is secured.

[0005] Patent Document 3 discloses a nozzle device comprising a nozzle member, a manifold to which the nozzle member is fixed, and a valve member such as a piezoelectric valve fixed to the manifold.

[0006] Patent Document 4 discloses an optical sorting machine that moves the detection position for the object to be inspected closer to the bottom end of the chute, shortening the flying distance from the bottom end of the chute to the detection position over which the object to be inspected is subjected to air resistance, allowing the object to be optically detected before it deviates from its falling trajectory or changes its posture, thereby achieving high detection accuracy for objects to be inspected falling from the bottom end of the chute. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-8892 [Patent Document 2] Japanese Patent Publication No. 2023-21757 [Patent Document 3] JP 2021-166960 A [Patent Document 4] Japanese Patent Publication No. 2022-124818 Summary of the Invention [Problem to be solved by the invention]

[0008] In Patent Document 1, when mounting a piezoelectric valve on an optical sorter, in order to achieve a specified sorting processing capacity, it was necessary to fit four actuators into the 20 mm wide main body case of the piezoelectric valve and to set the nozzle pitch at 5 mm. Considering the large size of the actuators and the need to meet this requirement, it was physically impossible to adopt a disassembly-based assembly method in which the main body case was thickened and fastened (assembled) with screws. For this reason, the piezoelectric valve in Patent Document 1 was assembled using a welding-based assembly method in which the cover material, valve seat plate, and main body case were laser-welded together.

[0009] However, with the welding assembly method, if any of the actuators (even one of the four) inside the main body case of the piezoelectric valve develops a problem (internal air leakage, air volume outside the standard value, inclusion of moisture or other contaminants, poor insulation, etc.) after the piezoelectric valve is attached to the optical sorter, the piezoelectric valve cannot be disassembled to replace the parts, so the piezoelectric valve cannot be restored and must be discarded. Furthermore, the piezoelectric valve disclosed in Patent Document 1 has a connector on the side of the main body case for supplying power to the piezoelectric element, which poses a problem of increasing the width of the piezoelectric valve.

[0010] To solve the problems of the piezoelectric valve disclosed in Patent Document 1, such as the inability to disassemble and reassemble, and the problem of wiring connector placement, and to meet the requirement of a nozzle pitch of 4 mm and a body case width of 16 mm or less, the piezoelectric valve disclosed in Patent Document 2 has a connector for supplying power to the piezoelectric element at the rear of the body case, a small actuator, and a valve seat plate designed to allow two actuators to be placed opposite each other. This allows for the actuators to be miniaturized and space to be secured within the body case of the piezoelectric valve. The valve seat plate has a screw mounting portion on the valve seat portion of the valve seat plate, allowing it to be attached to the body case with screws. This allows the piezoelectric valve to be disassembled and reassembled when a malfunction or problem occurs.

[0011] However, although the piezoelectric valve disclosed in Patent Document 2 can be disassembled and rebuilt, there is a risk that errors in the dimensional accuracy or distortion of the screw mounting portion provided on the valve seat portion of the valve seat plate and the mounting hole on the main body case during manufacturing of the piezoelectric valve could cause poor assembly of the valve seat portion to the main body case, resulting in air leakage.In addition, the piezoelectric valve disclosed in Patent Document 2 has a problem in that the height dimension of the piezoelectric valve is longer by the length of the screw mounting portion and the screw on the valve seat portion, making it difficult to make the piezoelectric valve compact.

[0012] The manifold used in the nozzle device disclosed in Patent Document 3 is equipped with the piezoelectric valve disclosed in Patent Document 1, so the width of the manifold is longer by the width of the wiring connector. For this reason, when incorporating the nozzle device into an optical sorting machine, there is a problem in that it is difficult to locate the nozzle device in an optimal location for sorting the objects to be inspected due to the optimal position for identifying the objects to be inspected by the optical detection device incorporated into the optical sorting machine and the physical relationship between the size of the optical detection device and the size of the nozzle device.

[0013] In the optical sorting machine disclosed in Patent Document 4, the detection position of the object to be inspected and the position where the air is blown by the ejector nozzle for air separation are separated from each other, which causes problems such as errors in distinguishing between good and defective products by the air blow, or the possibility of good products being caught up in the air blown as defective products.

[0014] In view of the above-mentioned problems, the present invention aims to provide a compact (miniaturized) piezoelectric valve that can be disassembled and regenerated, as well as an optical sorting machine equipped with the piezoelectric valve. [Means for solving the problem]

[0015] One aspect of the present disclosure is an actuator that drives the valve body; a valve seat plate that has a valve seat that comes into contact with and separates from the valve body and a valve seat portion that is provided with a discharge path, and that fixes the actuator; a main body case that houses the valve seat plate, The actuator is The valve body; a piezoelectric element that generates a driving force required for the operation of the valve body as a displacement; a displacement magnifying mechanism that magnifies the displacement of the piezoelectric element and applies it to the valve body, The main body case includes: a gas supply port through which compressed gas is supplied; a gas discharge port that discharges the compressed gas supplied from the gas supply port through the discharge path of the valve seat plate by separating the valve body from the valve seat, the valve seat plate is fixed to the main body case at a rear portion on a side where the valve seat portion and the actuator are fixed, The piezoelectric valve is characterized in that the front surface of the valve seat portion is fixed to the inner surface of the main body case by a pressing force from the direction of the rear portion of the valve seat plate.

[0016] Aspect 2 according to the present disclosure is the main body case is a case that is open at the rear and has the gas exhaust port at the front, The valve seat plate is provided with a lid member that closes the opening on the rear surface of the main body case, The valve seat plate is a piezoelectric valve according to aspect 1, in which the cover material is fixed to the main body case from the rear by screws at the rear portion on the side where the actuator is fixed, the front surface of the valve seat portion is fixed to the main body case by the pressing force of the cover material from the direction of the rear portion of the valve seat plate, and the exhaust path is connected to the gas exhaust port of the main body case.

[0017] Aspect 3 according to the present disclosure is This is a piezoelectric valve according to aspect 2, in which the valve seat portion is fixed to the inner surface of the main body case via a rubber sheet having a through hole corresponding to the discharge path by a pressing force from the direction of the rear portion of the valve seat plate.

[0018] Aspect 4 according to the present disclosure is In the piezoelectric valve according to aspect 3, a recess is provided on the inner surface of the main body case, and the front surface of the valve seat is fitted into the recess.

[0019] Aspect 5 according to the present disclosure is the valve seat portion has a threaded hole; 5. The piezoelectric valve of claim 4, wherein the valve seat is removably attached to the valve seat portion using a screw that is fitted into the screw hole.

[0020] Aspect 6 according to the present disclosure is In the piezoelectric valve of aspect 5, the valve seat is one of a standard valve seat with two single-channel inlets, a first low-pressure valve seat with one single-channel inlet, a second low-pressure valve seat with one single-channel inlet and smaller than the first low-pressure valve seat, a third low-pressure valve seat with one single-channel inlet divided into three small-diameter inlets, and a fourth low-pressure valve seat with one single-channel inlet divided into one small-diameter inlet.

[0021] A seventh aspect of the present disclosure is the cover member is disposed at the rear of the main body case and has a connector for supplying power to the piezoelectric element; One end of the electrode of the connector is electrically connected to the piezoelectric element. 3 is a piezoelectric valve according to embodiment 2.

[0022] Aspect 8 according to the present disclosure is An optical sorting machine comprising: a transport means for dropping an object to be inspected; and an optical detection means for detecting whether the object to be inspected is good or bad at a detection position on a drop trajectory of the object to be inspected that has fallen from the transport means, The piezoelectric valve according to aspect 7 is provided. This optical sorting machine has an air jet position, which uses air jetted from a nozzle via the piezoelectric valve to distinguish whether an object is good or bad, located close to the detection position. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a piezoelectric valve that can be disassembled and regenerated and is compact (miniaturized), and also to provide an optical sorting machine equipped with the piezoelectric valve. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view of a piezoelectric valve. [Figure 2] FIG. 2 is a top view of the piezoelectric valve of FIG. 1. [Figure 3] FIG. 2 is a side view of the piezoelectric valve of FIG. [Figure 4] FIG. 2 is a front view of the piezoelectric valve of FIG. [Figure 5] FIG. 1 is an exploded view of a piezoelectric valve. [Figure 6] FIG. 10 is an enlarged view of a portion where an end of the valve seat plate is fixed inside the main body case. [Figure 7] FIG. 10 is a perspective view of a valve seat plate to which an actuator integrated with a lid is fixed. [Figure 8] FIG. 8 is a perspective view of FIG. 7 rotated 180 degrees up and down around an axis parallel to the paper surface. [Figure 9] FIG. 8 is a front view of the valve seat plate to which the actuator of FIG. 7 is fixed. [Figure 10] FIG. 8 is a side view of the valve seat plate to which the actuator of FIG. 7 is fixed. [Figure 11] FIG. 8 is a bottom view of the valve seat plate of FIG. 7. [Figure 12] 1A and 1B are diagrams illustrating a standard valve seat, the upper diagram being a top view and the lower diagram being a perspective view. [Figure 13] 1A and 1B are diagrams illustrating Example 1 of a low-pressure valve seat, the upper diagram being a top view and the lower diagram being a perspective view. [Figure 14] 10A and 10B are diagrams illustrating Example 2 of a low-pressure valve seat, the upper diagram being a top view and the lower diagram being a perspective view. [Figure 15] 10A and 10B are diagrams illustrating Example 3 of a low-pressure valve seat, the upper diagram being a top view and the lower diagram being a perspective view. [Figure 16] 10A and 10B are diagrams illustrating Example 4 of a low-pressure valve seat, the upper diagram being a top view and the lower diagram being a perspective view. [Figure 17] FIG. 1 is a diagram illustrating an optical sorting machine to which a conventional piezoelectric valve is applied. [Figure 18] 1 is a diagram illustrating an optical sorting machine to which a piezoelectric valve according to an embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a piezoelectric valve. FIG. 2 is a top view of the piezoelectric valve 1 shown in FIG. 1. FIG. 3 is a side view of the piezoelectric valve 1 shown in FIG. 1. FIG. 4 is a front view of the piezoelectric valve 1 shown in FIG. 1. FIG. 5 is an exploded view of the piezoelectric valve 1. FIG. 6 is an enlarged view of the area where the valve seat portion 41 of the valve seat plate 4 is fixed inside the main body case 2.

[0026] In the embodiment of the present invention, the piezoelectric valve 1 includes a main body case 2, an actuator 3, a valve seat plate 4 that is arranged inside the main body case 2 with the actuator 3 fixed thereto, and a cover member 5.

[0027] The main body case 2 is a case that is open at the rear (lower side in FIG. 1). Inside the main body case 2, there is provided a gas pressure chamber that receives a supply of compressed gas from an external compressed gas supply source (not shown). On the front side (upper side in FIG. 1) of the main body case 2, there is provided a connector portion (not shown) for attaching to a manifold (not shown) that has an internal space to which compressed gas is supplied from the compressed gas source. In the optical sorting machine, the manifold is attached to the top surface of the piezoelectric valve 1, but in order to ensure stable attachment of the manifold, the width of the manifold must be the same length as the width W of the piezoelectric valve 1.

[0028] A gas inlet for drawing compressed gas into the main body case 2 and a plurality of gas outlets for discharging the compressed gas are open on the front surface of the connector portion. Furthermore, a gas inlet 21 communicating with the gas inlet of the connector portion, and a plurality of gas outlets 22 communicating with the gas outlet of the connector portion are opened on the front surface of the main body case 2. In Fig. 1, the piezoelectric valve 1 is provided with four gas outlets 22.

[0029] As shown in Fig. 1, a lid member 5 with a connector 51 is attached to the rear surface (the lower side in Fig. 1) of the main body case 2. As shown in Fig. 5, a connector 51 equipped with wiring pins 48 for supplying power to the piezoelectric element 32 is integrally formed with the lid member 5 on the rear surface thereof.

[0030] 7 and 8 are perspective views of the valve seat plate 4 to which the actuator 3 integrated with the cover member 5 is fixed. Fig. 8 is a perspective view of Fig. 7 rotated 180 degrees up and down around an axis parallel to the paper surface.

[0031] Fig. 9 is a front view of the valve seat plate 4 to which the actuator 3 of Fig. 7 is fixed. Fig. 10 is a side view of the valve seat plate 4 to which the actuator 3 of Fig. 7 is fixed. Fig. 11 is a bottom view of the valve seat plate 4 to which the actuator 3 of Fig. 7 is fixed.

[0032] The valve seat plate 4 can accommodate four actuators 3, with two actuators 3 attached to each of the opposing sides. The valve seat plate 4 has a valve seat portion 41 with a substantially square outer shape at one end. Each of the opposing sides of the valve seat portion 41 is provided with a valve seat 42 against which the valve element 35 of the actuator 3 abuts. The valve seat 42 has two channels corresponding to the valve element 35 of each actuator 3.

[0033] As shown in FIG. 6, each valve seat 42 is fastened to the valve seat portion 41 with a screw 71. Because each valve seat 42 is attached to the valve seat portion 41 using the screw 71, each valve seat 42 can be freely attached and detached to the valve seat portion 41 and is replaceable. The valve seat 42 may be provided with one channel corresponding to the valve element 35 of each actuator 3. By making the valve seat 42 detachable, when the piezoelectric valve 1 is applied to an optical sorting machine, it is possible to select a valve seat 42 that matches the size and weight of the objects to be sorted. This allows for optimal air jetting onto the objects to be sorted, enabling highly accurate sorting work.

[0034] As shown in Figures 5 and 6, the front surface of the valve seat portion 41 of the valve seat plate 4 is fixed to the inner surface of the main body case 2 via a rubber sheet 75. The front surface of the valve seat portion 41 is fixed not by screws but by vertical pressure against the inner surface of the main body case 2. The valve seat portion 41 does not have a screw-fastening portion for fixing the valve seat portion 41 to the main body case 2. This makes it possible to reduce the weight of the screw-fastening portion and the weight of the screws from the weight of the piezoelectric valve 1.

[0035] On one side of the valve seat plate 4, mounting portions for the actuator 3 are formed at positions facing both sides of the valve seat portion 41. Also, on the other side of the valve seat plate 4, mounting portions for the actuator 3 are formed at positions facing both sides of the valve seat portion 41.

[0036] As shown in Figure 7, the valve seat portion 41 is formed with four discharge passages 45, one end of which opens to the valve seat surface of each valve seat 42, and the other end of each discharge passage 45 opens to the front surface of the valve seat plate 4 (the upper surface in Figure 7).

[0037] When the front surface of the valve seat portion 41 is fixed to the inner surface of the casing 2 via the rubber sheet 75, each of the four exhaust channels 45 communicates with each of the four gas exhaust ports 22 provided in the casing 2. The rubber sheet 75 has through holes corresponding to the openings of the exhaust channels 45 and the gas exhaust ports 22. The rubber sheet 75 is a member that prevents compressed gas from leaking into the casing 2 from the connection points between the exhaust channels 45 and the gas exhaust ports 22. The valve seat portion 41 is fixed to the inner surface of the casing 2 by a pressing force in the vertical direction, so that compressed gas can be prevented from leaking into the casing 2 from the connection points between the exhaust channels 45 and the gas exhaust ports 22.

[0038] Each actuator 3 is fixed to a corresponding mounting portion of the valve seat plate 4 by a screw 74. The valve bodies 35 of the four actuators 3 are disposed so as to face the corresponding valve seats 42.

[0039] An electrode (not shown) for connecting a lead wire (not shown) of the piezoelectric element 32 in the actuator 3 is provided at a rear position of the valve seat plate 4 (lower position in FIG. 7, upper position in FIG. 8).

[0040] A cover member 5 with a connector 51 that closes the opening at the rear surface of the main case 2 is integrally provided at the rear end of the valve seat plate 4. One end of the wiring pin 48 is connected to the electrode (not shown), and the other end extends outward from the rear surface (the bottom surface in FIG. 7 and the top surface in FIG. 8) of the cover member 5 with the connector 51 attached, forming a connector. The wiring pin 48 is electrically connected to the piezoelectric elements 32, and power is supplied to each piezoelectric element 32 via the wiring pin 48. By arranging the connector 51 at the rear of the main case 2, the width W of the piezoelectric valve 1 can be made smaller than the width of the conventional piezoelectric valve disclosed in Patent Document 1.

[0041] Here, the electrode (not shown) can be covered with an insulating material, for example, an insulating resin material such as silicone, together with one end of the wiring pin 48, in a state where it is connected to the lead wire of the piezoelectric element 32 and the wiring pin 48. If the electrode (not shown) is covered with an insulating material together with one end of the wiring pin 48 in a state where it is connected to the lead wire of the piezoelectric element 32 and the wiring pin 48, then, together with the wiring pin 48 being molded into the valve seat plate 4, it is possible to prevent a short circuit due to water droplets or the like.

[0042] The actuator 3 includes a base 31 fixed to the valve seat plate 4, a piezoelectric element 32 having one end connected to the mounting surface of the base 31 and extending in a first longitudinal direction, and a support part 33 formed integrally with the base 31 and extending alongside the piezoelectric element 32 in a second longitudinal direction intersecting the first longitudinal direction.

[0043] The actuator 3 includes an action portion 34 and a valve body 35. The action portion 34 is connected to the other end of the piezoelectric element 32 and the tip end of the support portion 33, and is displaced in a direction different from the first longitudinal direction and the second longitudinal direction as the piezoelectric element 32 expands and contracts. The valve body 35 is provided on one side of the action portion 34 on the tip side in the direction of displacement, and is driven by the displacement of the action portion 34.

[0044] The base 31 is fixed to the valve seat plate 4 with screws 74 by utilizing the mounting holes on at least the side where the support portion 33 is integrally provided.

[0045] The support portion 33 has a constricted portion 331 in the middle portion extending in the second longitudinal direction, and is fixed to the valve seat plate 4 with screws 74, utilizing mounting holes provided closer to the base portion 31 than the constricted portion 331. Because each actuator 3 is attached to the valve seat plate 4 with the screws 74, if a problem occurs with one of the actuators 3, it is possible to disassemble the piezoelectric valve 1, remove the actuator 3 with the problem from the valve seat plate 4, and replace it with a new actuator 3.

[0046] The actuator 3 is a displacement magnifying mechanism that magnifies the displacement of the piezoelectric element 32 and causes it to act on the valve element 35. The actuator 3 includes a support portion 33 and an action portion 34, and as the piezoelectric element 32 expands and contracts, the action portion 34 is displaced in a displacement direction different from each of the first longitudinal direction and the second longitudinal direction, causing the valve element 35 to move toward and away from the valve seat 42. At this time, by providing a constricted portion 331 in an intermediate portion of the support portion 33 extending in the second longitudinal direction, it is possible to magnify the displacement of the action portion 34 associated with the expansion and contraction of the piezoelectric element 32.

[0047] The base portion 31 and the support portion 33 can be integrally formed by punching out a metal material such as stainless steel including Invar. If the base portion 31 and the support portion 33 are integrally formed by stamping out a metal material, the number of parts can be reduced, and the assembly of the actuator 3 becomes easier.

[0048] The action portion 34 can be made of a lightweight material such as aluminum, etc. Making the action portion 34 from a lightweight material such as aluminum is preferable in terms of displacing the action portion 34. The valve body 35 is made of rubber or the like, preferably a smooth rubber.

[0049] In the actuator 3, the base 31 and the action part 34 can be connected by a compression member 36. The piezoelectric element 32 is easily damaged by a load in the tensile direction, but by connecting the base 31 and the action part 34 by the compression member 36, the piezoelectric element 32 can be compressed in the first longitudinal direction, thereby preventing damage to the piezoelectric element 32.

[0050] FIG. 5 shows an exploded view of the piezoelectric valve 1. The valve seat plate 4 to which the actuator 3 is fixed is inserted into the main body case 2 through the opening on the rear surface of the main body case 2, the opening on the rear surface of the main body case 2 is closed with the cover material 5 with the connector 51 provided on the valve seat plate 4, and the cover material 5 with the connector 51 is assembled by screwing it to the main body case 2 with screws 72.

[0051] The valve seat portion 41 of the valve seat plate 4 does not have a mounting portion with a screw hole used to fix it to the casing 2. The valve seat plate 4 is fixed at the valve seat portion 41 in the front portion on the side having the discharge path 45 by pressing the front surface, where the discharge path 45 opens inside the casing 2, vertically from the rear against the inner surface of the casing 2, so that the discharge path 45 communicates with the gas discharge port 22 of the casing 2. This makes it possible to reduce the weight of the valve seat plate 4 and the length of the discharge path 45, thereby reducing the pressure loss of the compressed gas flowing inside the discharge path 45 due to the path wall.

[0052] A recess 23 having a shape that matches the outer shape of the valve seat 41 may be provided on the inner surface of the upper inner part of the case body 2. The valve seat plate 4 is pressed from the rear so that the front side of the valve seat 41 is fitted into and fixed in place in the recess 23. The depth of the recess 23 may be set as appropriate.

[0053] By fitting and fixing the front part of the valve seat portion 41 into the recessed portion 23, it is possible to prevent the front part of the valve seat plate 4 from shifting sideways when driving the piezoelectric valve 1. By removing the nut portion used to fix the valve seat plate 4 to the inner surface of the main body case 2 from the valve seat plate 4 and pressing the front surface of the valve seat portion 41 against the inner surface of the main body case 2 to create a fitting type, it is possible to reduce the height dimension of the piezoelectric valve 1, reducing the amount of screw attachment work and the number of assembly steps.

[0054] The length of the valve seat plate 4 is set so that when the cover member 5 with the connector 51 is attached to the rear surface of the main body case 2 and fixed with the screws 72, the front surface of the valve seat portion 41 of the valve seat plate 4 presses with a predetermined pressing force against the inner surface of the case of the main body case 2. The length of the valve seat plate 4 may be set by adjusting the height of the valve seat portion 41.

[0055] The front surface of the valve seat portion 41 of the valve seat plate 4 is fixed to the front inner surface of the main body case 2, and the portion where the exhaust path 45 of the valve seat plate 4 and the gas exhaust port 22 of the main body case 2 communicate is sealed with a rubber sheet 75, and the portion where the cover member 5 with the connector 51 formed integrally with the valve seat plate 4 closes the opening on the rear surface of the main body case 2 is sealed with an O-ring 76, thereby preventing gas leakage from the main body case 2. The rubber sheet 75 and the O-ring 76 also prevent liquid droplets from entering from outside the main body case 2.

[0056] When electricity is applied to the piezoelectric element 32 of the actuator 3 in the closed state of the piezoelectric valve 1, the piezoelectric element 32 expands, the operating part 34 is displaced, and the valve body 35 moves away from the valve seat 42 to open the valve. The compressed gas supplied to the main body case 2 from the gas intake port 21 is discharged from the gas exhaust port 22 opening on the front surface of the main body case 2 via the exhaust path 45 formed in the valve seat part 41 of the valve seat plate 4.

[0057] On the other hand, when the piezoelectric valve 1 is de-energized, the piezoelectric element 32 of the actuator 3 contracts, the operating portion 34 is displaced in the opposite direction, and the valve body 35 seats on the valve seat 42 to close the valve.

[0058] The valve seat plate 4 is fixed to the main body case 2 at the front side of the valve seat portion 41 having the discharge path 45 and at the rear side on the side where the actuator 3 is fixed, so the valve seat plate 4 does not swing and come into contact with the inner surface of the main body case 2. Therefore, according to the piezoelectric valve 1 in the embodiment of the present invention, it is possible to prevent damage due to the impact when the valve seat plate 4 comes into contact with the inner surface of the main body case 2, and to prevent malfunction due to contact.

[0059] In the piezoelectric valve 1, the valve seat plate 4 is fixed in place by pressing the front surface of the valve seat 41, which has the discharge path 45, where the discharge path 45 opens into the case of the main body casing 2 vertically from behind against the inner surface of the main body casing 2, and the rear portion on the side where the actuator 3 is fixed, and the cover member 5 with a connector is fixed to the main body casing 2 from behind with screws 72, 72, so the piezoelectric valve 1 can be disassembled by removing the screws 72 from the rear. This makes it possible to investigate the cause of a malfunction in the piezoelectric valve 1 and to repair it.

[0060] The piezoelectric valve 1 has the other end of the wiring pin 48 on the rear surface of the cover material 5 with the connector 51 formed integrally with the valve seat plate 4, so that the connector 51 can be provided at the rear part of the main body case 2. This allows the widthwise dimension W of the piezoelectric valve 1 to be reduced, making it possible to make the valve smaller than conventional piezoelectric valves (see Patent Document 1) in which the connector is provided at the side of the main body case 2.

[0061] In the piezoelectric valve 1, as shown in Figures 1, 3 and 5, the valve seat plate 4 can be fixed to the main body case 2 from both sides by screws 73 at the rear part on the side where the actuator 3 is fixed. If the valve seat plate 4 is fixed to the main body case 2 on both sides with screws 73 at the rear part on the side where the actuator 3 is fixed, the bulge in the width direction of the main body case 2 can be kept small, thereby preventing malfunctions when multiple piezoelectric valves 1 are used in parallel as ejector valves of an optical sorting machine, etc.

[0062] In the above embodiment of the present invention, the valve seat plate 4 is fixed to the case of the main body casing 2 by pressing the front surface where the discharge path 45 opens inside the case of the main body casing 2 from the rear, and the cover material 5 with the connector is fixed to the case of the main body casing 2 from the rear with screws 72, making it possible to disassemble it, and making it possible to investigate the cause of a malfunction and to repair it.

[0063] In the above embodiment of the present invention, the piezoelectric valve 1 is configured so that the valve body 35 is seated on the valve seat 42 when no voltage is applied to the piezoelectric element 32. However, by changing the polarity of the voltage supplied from the drive unit, the valve body 35 can also be spaced apart from the valve seat 42 when no voltage is applied to the piezoelectric element 32.

[0064] In the above embodiment of the present invention, the piezoelectric valve 1 has a valve seat plate 4 with four actuators 3 fixed inside the main case 2, and four gas exhaust ports 22 opening on the front of the main case 2, but this is not limited to this, and a valve seat plate with one or more actuators fixed to the main case 2 can be arranged, and for example, a valve seat plate that can be fitted with two actuators 3 on only one side can also be used.

[0065] When the piezoelectric valve 1 of the above embodiment is applied to an optical sorter that discriminates the quality of grains and the like, it is necessary to set the discharge conditions of the piezoelectric valve according to the raw material to be sorted. The discharge conditions are set as follows: If heavy raw materials are blown with low discharge pressure, they cannot be separated (the blowing force is too small to move and remove defective grains from the falling trajectory of the heavy raw materials). If light materials are blown with high discharge pressure, they cannot be sorted (many good products will be caught in the blowing of defective products from the falling trajectory of the light materials. Also, if the blowing force is too strong, there is a possibility that the good or defective products hit by the blowing force will be damaged. Furthermore, if the blowing force is stronger than necessary, the wind will fly up and soil the optical part). It is necessary to take into consideration that the discharge pressure can be varied by changing the supply voltage, and that the discharge pressure can be varied by changing the supply pressure.

[0066] For this reason, accurate air blast sorting has traditionally been achieved by changing the discharge pressure according to the weight and specific gravity of the raw material being sorted, for example, sesame (light raw material) at a discharge pressure of 10 kpa, rice (heavy raw material) at a discharge pressure of 20 kpa, and almonds (heavy raw material) at a discharge pressure of 30 kpa.

[0067] However, for raw materials (especially small parts) such as chip capacitors, which are even smaller and ultra-lightweight than the sesame seeds (light raw materials), even if the supply voltage and supply pressure are adjusted and the discharge pressure is set as low as possible (1 kPa is the limit), when defective chip capacitors are blown out from the falling trajectory, many good chips are caught in the blast because they are so light, resulting in low yields, making them unsuitable for practical use, and making it difficult to select raw materials.

[0068] Therefore, the present invention provides a piezoelectric valve for an optical sorter that can solve the above problems and accurately sort any type of raw material, including heavy raw materials such as almonds and rice, light raw materials such as sesame seeds, and even ultra-light raw materials such as chip capacitors.

[0069] Figure 6 is an enlarged view of the area where the end of the valve seat plate 4 is fixed inside the main body case 2, and as shown in Figure 6, detachable valve seats 42 are attached to both side surfaces of the valve seat portion 41. Therefore, as the valve seat 42, a standard valve seat and a low-pressure valve seat can be interchangeably attached so that an appropriate valve seat can be installed depending on the type of raw material.

[0070] By installing a low-pressure valve seat, it is now possible to stably output an ultra-low discharge pressure of less than 1 kPa, which was previously unattainable, allowing for the sorting of ultra-lightweight raw materials such as chip capacitors with a high yield. The appropriate air pressure is also achieved, reducing the risk of damage to good or defective products hit by the air pressure. Meanwhile, when the raw material is heavy, such as rice, sorting can be achieved by installing a standard valve seat and setting the same discharge pressure as before.

[0071] FIG. 12 is a diagram illustrating a standard valve seat, which has two inlets 46 per channel 43. FIG. 13 is a diagram illustrating Example 1 of a low-pressure valve seat, which has one inlet 46 per channel 43. FIG. 14 is a diagram illustrating Example 2 of a low-pressure valve seat, which has one inlet 46 per channel 43, which is smaller than Example 1. FIG. 15 is a diagram illustrating Example 3 of a low-pressure valve seat, which has three inlets 46 with small diameters per channel 43. FIG. 16 is a diagram illustrating Example 4 of a low-pressure valve seat, which has one inlet 46 per channel 43 with one small diameter inlet 46. Each valve seat has two channels to correspond to the valve bodies 35 of the two actuators 3. The discharge pressure from the valve seats increases in the order of Example 1 < Example 2 < Example 3 < Example 4. In the piezoelectric valve 1 according to the embodiment of the present invention, the valve seat 42 that is most suitable for the target material can be attached to the valve seat portion 41 by threading the screw 71 into the screw hole 44 .

[0072] As mentioned above, the piezoelectric valve 1 of the above embodiment can have a smaller width dimension W than the piezoelectric valve disclosed in Patent Document 1, and can have a smaller height dimension H than the piezoelectric valve disclosed in Patent Document 2.

[0073] Fig. 17 is a diagram illustrating an optical sorter that applies a piezoelectric valve according to one embodiment of the present invention. As shown in Fig. 17, the optical sorter 100 sorts an object A to be inspected by color, and includes a chute 102 and optical detection means 103. The object A to be inspected is a grain such as rice, wheat, or almond.

[0074] The chute 102 is formed like a gutter with side walls 121 erected on both side edges of a strip-shaped plate 120 of a predetermined width, and is installed at an incline in the longitudinal direction. Objects A to be inspected are continuously supplied to the upper end of the chute 102 in the inclined direction, and these objects A flow down the surface of the strip-shaped plate 120 and drop from the lower end of the chute 102.

[0075] The optical detection means 103 is arranged in a pair, one on the front side and one on the back side, sandwiching the fall trajectory L of the object A to be inspected falling from the chute 102, and each is arranged so as to be at a detection position O on the fall trajectory L.It is equipped with imaging means 130a (front side) and 130b (back side) such as a CCD camera that optically detects the object A to be inspected, illumination means 131a (front side) and 131b (back side) such as an LED light source that illuminates the detection position O, and backgrounds 132a (front side) and 132b (back side) that serve as the background when the object A to be inspected is imaged by the imaging means 130a and 130b.

[0076] An ejector nozzle 104 that selectively ejects air is installed on the rear side of the fall trajectory L, downstream of the detection position O of the optical detection means 103 in the falling direction of the object A to be inspected, with its tip facing the fall trajectory L. The ejector nozzle 104 opens and closes the discharge path for compressed air using a piezoelectric valve 1.

[0077] To select the object A, the object A falling from the bottom end of the chute 102 is illuminated from the front and back sides of the falling trajectory L at the detection position O by the illumination means 131a and 131b, and images are taken by the imaging means 130a and 130b.

[0078] The image data of the inspection object A captured by the imaging means 130a and 130b is sent to the discrimination unit 105 connected to the imaging means 130a and 130b. The discrimination unit 105 compares the signal levels of the image data, such as the amount of light, color components, and shape, with preset thresholds, and discriminates whether the inspection object A in the image data is a defective product or foreign matter, or a normal granular object.

[0079] The discrimination unit 105 is connected to an ejector drive device (not shown) that drives the ejector nozzle 104, and when, for example, an object A that has been discriminated to be a defective product or a foreign object reaches a position facing the tip of the ejector nozzle 104, it sends a removal signal to the ejector drive device. Air is ejected from the ejector nozzle 104, and the object A is blown forward and removed. The other objects A fall along a falling trajectory L and are transported to the next process.

[0080] By combining the piezoelectric valve 1 of the above embodiment with the ejector nozzle 104, the ejector nozzle 104 can be made smaller than conventional ones. Therefore, by applying the ejector nozzle 104 to the optical sorter 100, it can be positioned closer to the optical detection means 103. This shortens the distance between the detection position O of the object A and the air jet position X. The shorter distance from the detection position O to the air jet position X allows air to be jetted before the defective product changes its posture due to air resistance or before the defective product changes its trajectory downward from the parabola due to air resistance. This allows the tip of the ejector nozzle 104 to be closer to the object A, reducing the number of defective product sorting errors and the number of non-defective products that are caught in the process. This improves the sorting accuracy of the optical sorter that determines the quality of the object A, such as grain.

[0081] FIG. 17 shows the arrangement of a conventional ejector nozzle 104. However, by using the piezoelectric valve of the present invention described above, it is possible to make the ejector nozzle 104 smaller, as shown in FIG. 18. This makes it possible to shorten the distance a from the detection position O, and also to shorten the distance b from the object A under test, because air can be sprayed before the object A changes its trajectory downward from the parabola (when it is in a linear state). Furthermore, even if the distance between the bottom end position of the chute 102 and the detection position O is shortened and the total distance from the bottom end position of the chute 102 to the air spray position X is shortened, a manifold (not shown) attached to the piezoelectric valve 1 can be positioned near the air spray position X, thereby further synergistically improving the air spray accuracy. The distance by which the jet position X is brought closer to the detection position O should be set to an appropriately short time, taking into consideration the signal processing capability of the optical detection means 103 and the time required for the opening and closing capability of the piezoelectric valve used in the ejector nozzle 104.

[0082] Although several embodiments of the present invention have been described above, the above-described embodiments of the invention are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention includes equivalents thereof. Furthermore, the components described in the claims and specification may be combined or omitted to the extent that at least part of the above-described problems can be solved or at least part of the effects can be achieved. [Explanation of symbols]

[0083] 1 Piezoelectric valve 2 Main unit case 21 Gas inlet 22 Gas outlet 23 Recess 3 Actuators 32 Piezoelectric element 33 Support part 331 Waist 34 Acting part 35 Valve body 36 Compression member 4 Valve seat plate 41 Valve seat 42 Valve seat 43 channels 44 screw holes 45 Exhaust channel 46 Entrance 48 wiring pins 5 Lid material 51 Connector 71 screws 72 screws 73 screws 74 screws 75 rubber sheet 76 O-ring A. Inspection object L Falling trajectory O Detection position 100 Optical sorting machine 102 shots 103 Optical detection means 104 Ejector nozzle 105 Discrimination part 120 Strip 121 Side wall 122 Vertical grooves 130a, 130b Imaging means 131a,131b Irradiation means 132a, 132b Background

Claims

1. an actuator that drives the valve body; a valve seat plate that has a valve seat that comes into contact with and separates from the valve body and a valve seat portion that is provided with a discharge path, and that fixes the actuator; a main body case that houses the valve seat plate, The actuator is The valve body; a piezoelectric element that generates a driving force required for the operation of the valve body as a displacement; a displacement magnifying mechanism that magnifies the displacement of the piezoelectric element and applies it to the valve body, The main body case includes: a gas supply port through which compressed gas is supplied; a gas discharge port that discharges the compressed gas supplied from the gas supply port through the discharge path of the valve seat plate by separating the valve body from the valve seat, the valve seat plate is fixed to the main body case at a rear portion on a side where the valve seat portion and the actuator are fixed, The front surface of the valve seat portion is fixed to the inner surface of the main body case by a pressing force from the direction of the rear portion of the valve seat plate. A piezoelectric valve characterized by:

2. the main body case is a case that is open at the rear and has the gas exhaust port at the front, The valve seat plate is provided with a lid member that closes the opening on the rear surface of the main body case, The valve seat plate has a rear portion on the side where the actuator is fixed, and the cover is fixed to the main body case from the rear by screws, and the front surface of the valve seat is fixed to the main body case by the pressing force of the cover from the direction of the rear portion of the valve seat plate, and the exhaust path communicates with the gas exhaust port of the main body case.

2. The piezoelectric valve according to claim 1.

3. The valve seat portion is fixed to the inner surface of the main body case via a rubber sheet having a through hole corresponding to the discharge path by a pressing force from the direction of the rear portion of the valve seat plate.

3. The piezoelectric valve according to claim 2.

4. A recess is provided on the inner surface of the main body case, and the front surface of the valve seat is fitted into the recess.

4. The piezoelectric valve according to claim 3.

5. the valve seat portion has a threaded hole; The valve seat is detachably attached to the valve seat portion using a screw that is fitted into the screw hole.

5. The piezoelectric valve according to claim 4.

6. The valve seat is one of a standard valve seat having two inlets for one channel, a first low-pressure valve seat having one inlet for one channel, a second low-pressure valve seat having one inlet for one channel and smaller than the first low-pressure valve seat, a third low-pressure valve seat having three inlets with small diameters for one channel, and a fourth low-pressure valve seat having one inlet for one channel with small diameter.

6. The piezoelectric valve according to claim 5.

7. the cover member is disposed at the rear of the main body case and has a connector for supplying power to the piezoelectric element; One end of the electrode of the connector is electrically connected to the piezoelectric element.

3. The piezoelectric valve according to claim 2.

8. An optical sorting machine comprising: a transport means for dropping an object to be inspected; and an optical detection means for detecting whether the object to be inspected is good or bad at a detection position on a drop trajectory of the object to be inspected that has fallen from the transport means, The piezoelectric valve according to claim 7 is provided. The position of the air jet that jets air from a nozzle via the piezoelectric valve to distinguish whether the object to be inspected is good or bad is located close to the detection position. An optical sorting machine characterized by:

Images