JP2019167975A - Fluid control valve and shutoff device using the same - Google Patents

Abstract

To provide a fluid control valve performing position detection by slanting MR sensors in a circumferential direction of a magnet.SOLUTION: A fluid control valve includes: a valve body 13 opening or closing a flow path; a magnet 23 fixed to the valve body 13 so that an S pole 24 and an N pole 25 may be in a moving direction of the valve body 13; a two-pole detection type hole IC 30 for the S pole and the N pole which is located on a side in the moving direction of the magnet 23; and an actuator 2 driving the valve body 13. When magneto-sensitive parts of MR sensors 31, 30 are disposed so as to apply a magnet flux density in an axial direction of the magnet 23 and to be slant in the circumferential direction of the magnet 23, and the MR sensor 31 or an MR sensor 32 detects an operation magnetic flux density or more, the MR sensor 31 or the MR sensor 32 is close to the magnet 23 and thereby the position of the valve body 13 can be determined and recognized.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fluid control valve. More specifically, the present invention relates to a fluid control valve capable of detecting the position of a valve body.

  Patent Document 1 discloses a fluid control valve. The fluid control valve includes a stepping motor that is an electric motor, a conversion unit that is locked to the rotation shaft of the stepping motor and converts rotation of the rotation shaft into a linear motion, and a valve body that is locked to the conversion unit and opens and closes the flow path. And a valve body position detecting means. As the valve body position detecting means, a magnet provided at one end of the valve body, a valve-opening magnetic detection element for detecting an open state of the valve body disposed on the outer surface of the flow path, and a closed state of the valve body are detected. A configuration with a magnetic detection element for valve closing is disclosed.

JP 2001-141094 A

  However, in the conventional configuration, the valve body is moved by the converting means for converting the rotation of the rotation shaft of the stepping motor into the linear motion to open and close the flow path. However, the orientation of the N pole and the S pole of the magnet, their arrangement, the characteristics of the magnetic detection element, and specific examples thereof are not disclosed.

  In general, an MR sensor using a magnetoresistive effect is often used as the magnetic detection element, and is arranged in the vicinity of the magnet on the outer surface of the flow path (parallel to the circumferential direction of the magnet) and in parallel with the upper surface inside the MR sensor. It arrange | positions so that an axial (magnet movement) direction magnetic flux density may be applied to the operating magnetic field direction of a magnetic sensing part.

  Further, the magnet is fixed to the valve body so that the S pole and the N pole are in the moving direction of the valve body. FIG. 12 shows the result of measuring the magnetic flux density in the axial direction with a gauss meter when the magnet is moved up and down about 8 mm with reference to the magnetic sensing part of the MR sensor. For example, the MR sensor detects an operating magnetic flux density of 2.5 mT or more, and does not detect an operating magnetic flux density below 0.5 mT. However, the MR sensor may or may not detect the operating magnetic flux density in the range of 0.5 mT to 2.5 mT. Furthermore, the MR sensor detects whether the magnetic flux density is positive or negative (magnetic flux densities of the S pole and the N pole).

  For these reasons, as shown in FIG. 12, when the magnet moves 4 mm or more from the side of the MR sensor, the magnetic field direction is reversed, and the MR sensor again detects -0.5 mT or less as the operating magnetic flux density. is there. Therefore, the MR sensor has a problem that the magnetic flux density is detected twice when the magnet is close and when it is separated. That is, even if the MR sensor detects the operating magnetic flux density, it cannot be determined whether the magnet is close or separated. Therefore, the MR sensor is difficult to use for position detection of several millimeters.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a fluid control valve that can detect the position of a valve body by attaching an MR sensor so as to be inclined with respect to the circumferential direction of a magnet.

  In order to solve the above-described conventional problems, a valve body for opening and closing the flow path of the present invention, a magnet fixed to the valve body so that the S pole and the N pole are in the moving direction of the valve body, An MR sensor using a magnetoresistive effect close to the magnet after movement and an actuator for driving the valve body are provided, and the magnetic sensing portion of the MR sensor is adapted to apply the magnetic flux density in the axial direction of the magnet. When the MR sensor detects an operating magnetic flux density or more with an inclination with respect to the direction, the MR sensor and the magnet are close to each other, and the position of the valve body can be determined.

  The MR sensor detects the magnetic flux density applied in the direction of the operating magnetic field, but has a feature (logic circuit) that does not detect the magnetic flux density applied so as to cross obliquely with respect to the direction of the operating magnetic field. When the magnet is separated from the MR sensor, the MR sensor is located in a region where the magnetic lines of force formed by the magnet (the tangent is the direction of the magnetic field at that point) bends when entering and exiting the flow path. Since the MR sensor is inclined with respect to the circumferential direction of the magnet, the applied magnetic field direction of the magnetosensitive part of the MR sensor crosses obliquely with respect to the operating magnetic field direction. Not detected.

  On the other hand, when the MR sensor detects that the applied magnetic flux density is equal to or higher than the operating magnetic flux density, the MR sensor and the magnet are close to each other, and the position of the valve body can be determined.

  According to the fluid control valve of the present invention, there is an effect that the position of the valve body can be detected by attaching the MR sensor so as to be inclined with respect to the circumferential direction of the magnet.

The figure which shows the valve open state of schematic structure of the fluid control valve concerning embodiment The figure which shows the valve closing state of the fluid control valve concerning embodiment FIG. 3 is a partial cross-sectional view of a main part of a fluid control valve according to an embodiment The perspective view which shows the state which wired the MR sensor concerning embodiment to a board | substrate External view of fluid control valve according to embodiment (A) The perspective view of the actuator of the fluid control valve concerning embodiment, and a fluid control part, (b) The perspective view except the valve rubber of the valve body concerning embodiment The figure which shows the structure and principle of the magnetosensitive part (magnetoresistance element) of MR sensor concerning embodiment (A) Enlarged view of essential parts of the valve rubber receiver, magnet, flow path, and MR sensor of the fluid control valve according to the embodiment, (b) Valve rubber receiver of the fluid control valve according to the embodiment in the valve closed state , Magnet, flow path, enlarged view of main part of MR sensor The figure which shows the measurement result of the magnetic flux density by the magnet movement in the attachment angle of 45 degrees of MR sensor of the fluid control valve concerning embodiment The figure which shows the range of the allowable operating magnetic field direction by the attachment angle and magnet movement of MR sensor concerning embodiment The figure which shows the measurement result of the magnetic flux density by the magnet movement in the attachment angle of 90 degrees of MR sensor of the fluid control valve concerning embodiment The figure which shows the measurement result of the axial direction magnetic flux density by the magnet movement in the attachment angle of 0 degree of MR sensor of the fluid control valve concerning embodiment Block diagram of blocking device according to the present embodiment

A first aspect of the present invention is a valve body that opens and closes a flow path, a magnet that is fixed to the valve body such that an S pole and an N pole are in the moving direction of the valve body, and the magnet after the movement of the valve body An MR sensor using a magnetoresistive effect close to the actuator, and an actuator for driving the valve body, so as to apply the magnetic flux density in the axial direction of the magnet to the magnetic sensing portion of the MR sensor, and When the MR sensor detects an operating magnetic flux density or more, the MR sensor and the magnet are close to each other, and the position of the valve body can be determined.

  Accordingly, when the actuator is driven to move the valve body, the magnet also moves together with the valve body. The MR sensor detects the applied magnetic flux density in the direction of the operating magnetic field, but does not detect the applied magnetic flux density so as to cross obliquely with respect to the operating magnetic field direction (logic circuit). When the magnet is separated from the MR sensor, the MR sensor is located in a region where the magnetic field lines formed by the magnet bend when entering and exiting the flow path. Since the MR sensor is inclined with respect to the circumferential direction of the magnet, the applied magnetic field direction of the magnetosensitive portion of the MR sensor is opposite to the positive and negative directions, but the MR sensor crosses obliquely with respect to the operating magnetic field direction. Even if the applied magnetic flux density is strong, it is not detected.

  On the other hand, when the MR sensor detects that the applied magnetic flux density is equal to or higher than the operating magnetic flux density, the MR sensor and the magnet are close to each other, and the position of the valve body can be determined. At this time, the applied magnetic flux density is the axial magnetic flux density. That is, the MR sensor inclined with respect to the circumferential direction of the magnet can detect the position of the valve body.

  In a second aspect of the invention, in particular, in the first aspect of the invention, the apparatus includes a substrate on which the MR sensor is mounted, the MR sensor is disposed in the vicinity of an outer edge of the substrate, the outer edge of the substrate is brought close to the flow path, and By arranging the flow path, the MR sensor, and the substrate in this order, the MR sensor is brought close to the flow path, and the distance between the MR sensor and the magnet is shortened by the thickness of the substrate. A strong axial magnetic flux density is applied to improve sensitivity.

  According to a third aspect of the invention, in the first aspect of the invention, when the magnet is separated from the MR sensor by inclining the magnetically sensitive portion of the MR sensor by 30 to 60 degrees with respect to the circumferential direction of the magnet, the MR sensor Since the applied magnetic field direction of the magnetic sensing part is inclined with respect to the operating magnetic field direction, the magnetic flux density applied by the MR sensor is not detected. When the magnetic sensing part of the MR sensor is tilted by more than 60 ° with respect to the circumferential direction of the magnet, even if the magnet is slightly separated from the MR sensor, the magnetic field lines formed by the magnet enter and exit the flow path. It is located in an area that bends very strongly. For this reason, since the applied magnetic field direction of the magnetosensitive part of the MR sensor crosses obliquely with respect to the operating magnetic field direction only by moving the magnet around 0.5 mm to 1 mm from the position where the MR sensor and the magnet are close to each other, the MR sensor Does not detect even if the applied magnetic flux density is strong. Therefore, when the position of the MR sensor or the magnet varies, even if the MR sensor and the magnet are close to each other, the magnetic flux density applied by the MR sensor cannot be detected, and the position of the valve may be erroneously detected.

  According to a fourth aspect of the present invention, in particular, the fluid control valve according to any one of the first to third aspects, the drive circuit of the fluid control valve, and the valve body position detection for detecting the position of the valve body by a signal from the MR sensor. The valve body position detection circuit is a shut-off device that stops detection of the position of the valve body by the MR sensor while the actuator is being driven, and is generated by an actuator that moves the valve body. To avoid adverse effects such as magnetic field and noise. In other words, the MR sensor determines and confirms whether the valve body is open or closed.

  According to a fifth aspect of the invention, in particular, in the fourth aspect of the invention, the fluid control valve includes two MR sensors for detecting the valve closed position of the valve body and for detecting the valve open position. When both MR sensors cannot detect more than the operating magnetic flux density, the two MR sensors determine whether the valve body is closed or open and the failure is detected by determining that the fluid control valve is failed. it can.

(Embodiment)
FIG. 1 is a diagram illustrating an example of a schematic configuration of a fluid control valve according to an embodiment in a valve open state, excluding a substrate. FIG. 2 is a view showing a valve closed state except for the substrate of the fluid control valve. FIG.
It is a principal part fragmentary sectional view which shows the fluid control valve. FIG. 4 is a perspective view showing a state in which the MR sensor is wired to the substrate. FIG. 5 is an external view of the fluid control valve. FIG. 6A is a perspective view of the actuator and fluid control unit of the fluid control valve, and FIG. 6B is a perspective view of the valve body excluding the valve rubber. Hereinafter, the fluid control valve of the present embodiment will be described with reference to FIGS.

  As illustrated in FIGS. 1 to 6, the fluid control valve 1 includes an actuator 2, a fluid control unit 3, and a flow path 4. The actuator 2 is a stepping motor that is an electric motor, and includes a stator 6 having a coil 5, and a rotor 7 and a base 8 that are rotated by excitation by energization of the coil 5. The rotor 7 has a cylindrical shape, and is composed of a resin bush 11 that integrally molds a magnet 9 on the outside and a rotating shaft 10 on the inside. The base 8 forms four comb-shaped upper rotation suppression plates 12 protruding downward.

  The fluid control unit 3 includes a valve body 13 made of polyacetal resin (POM) and conversion means 14. The valve body 13 includes a valve rubber receiver 15, a valve rubber 16, and a spring 17. Further, the valve body 13 is moved between an open state of the valve and a closed state of the valve by the actuator 2. In this embodiment, the moving path is set to 6 mm.

  The valve rubber receiver 15 includes a cylindrical portion 20 in which a short female screw 19 having a screw pitch of 1 to 2 that is locked to a male screw 18 formed at the tip of the rotary shaft 10 is formed inside, a disk 21 that attaches the valve rubber 16 to the lower surface, It is formed of four comb-like lower rotation suppression plates 22 protruding from the disk 21 toward the base 8 (upward). In addition, a magnet 23 serving as a marker is fixed to the upper surface of the disc 21 and in contact with the outer peripheral edge by a resin spring (adhesion, press-fitting, or the like). In this embodiment, the magnet 23 is a cylinder Φ4.0 × t1.5, made of neodymium, and magnetized in the thickness direction, so that the upper side is the S pole 24 and the lower side (the disk 21 side) is the N pole 25. is doing.

  The spring 17 is slidably provided in a compressible direction between the base 8 and the valve rubber receiver 15 and biases the valve rubber receiver 15 and the valve rubber 16. The conversion means 14 is configured by fitting the upper rotation suppression plate 12 and the lower rotation suppression plate 22 together.

  The flow path 4 is made of resin and has an L-shaped hollow cylinder, and has an inlet 26, a valve seat 27, an outlet 28, and an actuator insertion port 29. The actuator 2 is disposed in the actuator insertion port 29.

  The MR sensor 31 for opening the valve and the MR sensor 32 for closing the valve are arranged so that the magnetically sensitive portion is inclined with respect to the circumferential direction of the magnet 23 so as to apply the magnetic flux density in the axial direction of the magnet 23. A specific arrangement configuration will be described next.

  The valve opening MR sensor 31 and the valve closing MR sensor 32 are mounted on a substrate 33, and the substrate 33 is fixed to the MR sensor mounting portion 30, so that the positional relationship with the magnetic field of the magnet 23 is in a predetermined state. It is trying to become.

  As shown in FIG. 3, the MR sensor mounting portion 30 is inclined by 45 ° from the outer surface 4a of the flow path 4 near the magnet 23 to the tangent line of the outer surface 4a (same as the circumferential direction of the magnet 23 in this embodiment). And projecting.

  As shown in FIG. 4, the substrate 33 has four positioning holes 34 opened at the four corners, and the valve opening MR sensor 31 and the valve closing MR sensor 32 are arranged so as to be closest to the magnet 23. In the vicinity of the outer edge 33a of 33 (for example, around 0.5 mm), the valve body is disposed at an interval corresponding to the moving distance (6 mm, which will be described later) when the valve is opened and closed.

  The substrate 33 has a positioning hole so that the MR sensor 31 for opening the valve is close to the magnet 23 positioned when the valve is open, and the MR sensor 32 for closing the valve is close to the magnet 23 positioned when the valve is closed. 34 is positioned and attached by four positioning pins 35 protruding from the MR sensor attachment portion 30. At that time, the outer edge 33 a of the substrate 33 is pressed against the outer surface 4 a of the flow path 4, and the positioning pins 35 are positioned so that the flow path 4, the valve opening MR sensor 31, the valve closing MR sensor 32, and the substrate 33 are in this order. The hole 34 is inserted.

  The center of the applied magnetic field direction of the valve opening MR sensor 31 and the valve closing MR sensor 32 is located on a straight line (A) passing through the center of the rotating shaft 10 and the magnet 23, and a straight line (B ) Is in a positional relationship offset from the center of the magnet 23.

  With this configuration, the MR sensor 31 for valve opening and the MR sensor 32 for valve closing are brought close to the flow path 4, and the MR sensor 31 for valve opening, the MR sensor 32 for valve closing, and the magnet 23 are equal to the thickness of the substrate 33. Therefore, a strong axial magnetic flux density is applied to the magnetic sensing portions of the valve opening MR sensor 31 and the valve closing MR sensor 32, and the sensitivity is improved.

  Next, the MR sensor will be described in detail. The MR sensor performs ON / OFF operation with respect to the strength of the magnetic field of the S or N pole of the magnet. As a specific example, the MR sensor is manufactured by Murata Manufacturing Co., Ltd. MRMS501A-001A (W1.45 × D1.45 × H0.55): the direction of the operating magnetic field is the direction across the magnetic sensing part (electromagnetic resistance element). The operating magnetic flux density is ON (absolute value) 2.5 mT, the operating magnetic flux density is OFF 0.5 mT (absolute value), and the designed magnetic flux density is around 5 mT (manufacturer recommended).

  The operating magnetic flux density ON is a threshold value for turning on the MR sensor, and the operating magnetic flux density OFF is a threshold value for turning off the MR sensor. Note that the range of 0.5 mT to 2.5 mT outputs both ON and OFF. In addition, MR sensors include MR EZMP manufactured by Panasonic Corporation. On the other hand, in the Hall IC (Hall effect) which is one of the magnetic sensors, the direction of the operating magnetic field is a direction penetrating the magnetic sensitive part and is different from that of the MR sensor.

  FIG. 7 shows the configuration and principle of the magnetosensitive part of the MR sensor (Murata Manufacturing Co., Ltd. MRMS501A-001A). The magnetosensitive part of the MR sensor comprises four magnetoresistive elements R1, R2, R3, R4 in a Wheatstone bridge, and is supplied with electric power Vcc. When a magnetic field is applied to the magnetoresistive elements R1 and R2 at a perpendicular angle, the resistance value decreases. At the same time, since the magnetic field is applied in parallel to the magnetoresistive elements R3 and R4, the resistance value does not change.

  The magnetosensitive part of the MR sensor is divided into magnetoresistive elements R1 and R2 whose resistance value decreases and magnetoresistive elements R3 and R4 whose resistance value does not change when a magnetic field is applied from the outside in the designated operating magnetic field direction. A potential difference between points a and b occurs. Using this potential difference, the MR sensor outputs ON / OFF by a comparator. When a magnetic field is applied obliquely with respect to the direction of the operating magnetic field, the resistance values of the four magnetoresistive elements R1, R2, R3, and R4 are reduced, and the potential difference between the points a and b is also reduced. That is, even if a strong magnetic field is applied obliquely with respect to the direction of the operating magnetic field, the MR sensor outputs OFF.

  Specifically, the MR sensor can detect a magnetic field applied with an inclination of about −15 ° to 15 ° with respect to the direction of the operating magnetic field. Since the resistance of the magnetoresistive elements R1 and R2 changes regardless of whether the operating magnetic field direction is positive or negative, the S pole or N pole of the magnet 23 may be arranged in either direction of movement. That is, the MR sensor can detect a magnetic field that is reversed and applied to about 165 ° to 195 ° (−165 ° to −195 °) with respect to the direction of the operating magnetic field.

  About the fluid control valve 1 comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, the gas (open arrow) enters the flow path 4 from the inlet 26, passes through the valve seat 27 from the valve body 13 side, and flows out from the outlet 28. This will be described with reference to FIG. Note that the arrows in FIG. 8 indicate lines of magnetic force from the N pole 25 to the S pole 24.

  As shown in FIG. 8 (a), since the magnet 23 is positioned directly beside the valve opening MR sensor 31, the magnetic field lines cross the magnetic sensing part of the valve opening MR sensor 31 in the direction of the operating magnetic field. On the other hand, since the magnet 23 is located 6 mm above the valve closing MR sensor 32, the magnetic lines of force bending outward from the flow path 4 cause the magnetic sensing portion of the valve closing MR sensor 32 to be inclined with respect to the operating magnetic field direction. Crossing.

  FIG. 9 shows the result of measuring the magnetic flux density with a gauss meter when the mounting angle of the MR sensor is 45 ° (relative to the circumferential direction of the magnet 23).

  As shown in FIG. 9, in the valve open state, a magnetic flux density of about 10 mT, which is equal to or higher than the operating magnetic flux density ON, is applied to the magnetic sensing part (magnet position 0 mm) of the valve opening MR sensor 31. On the other hand, a magnetic flux density of about −2 mT is applied to the magnetic sensing part (magnet position −6 mm) of the valve closing MR sensor 32, but the applied magnetic field direction is about −150 ° with respect to the operating magnetic field direction. The MR sensor 32 for valve closing cannot detect the applied magnetic flux density of −2 mT. The applied magnetic field direction is calculated from the axial direction magnetic flux density and the 45 ° direction magnetic flux density (90 ° with respect to the axial direction and crossing the magnetosensitive portion of the MR sensor).

  FIG. 13 is a block diagram showing an example of a shut-off device using the fluid control valve 1. The fluid control valve 1, the drive circuit 41 for driving the actuator 2, the valve opening MR sensor 31, and the valve closing MR sensor The control part 40 provided with the valve body position detection circuit 42 which detects the position of the valve body 13 from 32 signals.

  Therefore, in order to confirm the position of the valve body 13, when the control unit 40 issues an instruction and power is supplied to the valve opening MR sensor 31 and the valve closing MR sensor 32, the comparator opens the MR sensor 31 for valve opening. The output is ON, and the output of the valve closing MR sensor 32 is OFF. From this, it can be determined that the valve body 13 is in the valve open state.

  On the other hand, the valve closed state of the valve body 13 of FIG. 2 in which gas is blocked by the valve rubber 16 will be described with reference to FIG.

  As shown in FIG. 8B, since the magnet 23 is positioned directly beside the valve closing MR sensor 32, the magnetic lines of force cross the magnetic sensing part of the valve closing MR sensor 32 in the operating magnetic field direction. On the other hand, since the magnet 23 is positioned 6 mm below the MR sensor 31 for opening the valve, the magnetic lines of force bending from the outside of the flow path 4 to the inside of the MR sensor 31 for opening the valve are inclined with respect to the direction of the operating magnetic field. Crossing.

  As shown in FIG. 9, in the valve closed state, a magnetic flux density of about 10 mT, which is equal to or higher than the operating magnetic flux density ON, is applied to the magnetic sensing part of the valve closing MR sensor 32. On the other hand, a magnetic flux density of about −2 mT is applied to the magnetic sensing part of the valve opening MR sensor 31, but the applied magnetic field direction is about 150 ° with respect to the operating magnetic field direction. The applied magnetic flux density cannot be detected.

Therefore, in order to confirm the position of the valve body 13, when the control unit 40 issues an instruction and power is supplied to the valve opening MR sensor 31 and the valve closing MR sensor 32, the comparator opens the MR sensor 31 for valve opening. The output is OFF, and the output of the valve closing MR sensor 32 is ON. From this, it can be determined that the valve body 13 is in the valve closed state. In the fluid control valve 1, the valve opening MR sensor 31 and the valve closing MR sensor 32 can detect and confirm the position of the valve body 13 in this manner.

  Thereafter, until the actuator 2 is driven or the valve opening MR sensor 31 determines that the valve element 13 is in the valve open state, power supply to a device (not shown) such as a flow velocity measurement is stopped. That is, since no gas is flowing, it is not necessary to supply power to other devices such as flow velocity measurement, and energy saving can be achieved.

  By the way, in order to confirm the position of the valve body 13, when the control unit 40 gives an instruction and power is supplied to the valve opening MR sensor 31 and the valve closing MR sensor 32, the comparator opens the valve opening MR sensor 31 and the valve. When both the outputs of the closing MR sensor 32 are ON or OFF, it can be determined that the fluid control valve 1 is out of order, and subsequently an alarm such as display or sound can be given.

  FIG. 10 shows the allowable operating magnetic field direction range (−15 ° to 15 °) depending on the MR sensor mounting angle and magnet movement. The allowable operating magnetic field direction is a direction in which the magnetic field applied by the MR sensor can be detected. Specifically, the magnet is moved at each mounting angle of the MR sensor, and the applied magnetic field direction is determined from the magnetic flux density in both the axial direction and the mounting angle direction (90 ° with respect to the axial direction and crossing the magnetosensitive part of the MR sensor). The range in which the applied magnetic field direction is −15 ° to 15 ° was determined as the allowable operating magnetic field direction range. When the mounting angle of the MR sensor is in the range of 30 ° to 60 °, the allowable operating magnetic field direction range can be secured ± 2 mm or more.

  If the mounting angle of the MR sensor (MR sensor mounting portion 30) exceeds 60 °, the allowable operating magnetic field direction range becomes narrow and position detection by the MR sensor becomes difficult. For example, FIG. 11 shows the result of measuring the magnetic flux density with a gauss meter when the mounting angle of the MR sensor is 90 ° (perpendicular to the outer surface of the flow path 4). As shown in FIG. 11, the applied magnetic field direction calculated from both the magnetic flux density in the axial direction and the mounting angle direction (in this case, the radial direction) changes rapidly even if the magnet 23 is moved slightly. This is because the radial magnetic flux density changes abruptly. As a result, there is a problem that the allowable operating magnetic field direction range is as narrow as ± 0.5 mm. Even if the dimensions of the flow path 4 are the same, when the MR sensor mounting angle is increased, the distances between the valve opening MR sensor 31, the valve closing MR sensor 32, and the magnet 23 are increased. There is a problem of being as small as 7 mT.

  Conversely, when the mounting angle of the MR sensor (MR sensor mounting portion 30) is less than 30 °, as shown in FIG. 10, the operating magnetic field direction range can be secured ± 3 mm or more. However, as described in the problem to be solved by the invention, according to FIG. 12, when the magnet 23 moves beyond 4 mm, the direction of the applied magnetic field is reversed by 180 °, and the MR sensor again sets the operating magnetic flux density ON. It will be detected. As a result, the mounting angle of the MR sensor cannot be less than 30 °. Even if the dimensions of the flow path 4 are the same, when the MR sensor mounting angle is reduced, the distance between the valve opening MR sensor 31, the valve closing MR sensor 32, and the magnet 23 is short, so that the peak of the axial magnetic flux density is increased. The feature of being as large as 12mT cannot be used.

As a result, the optimum mounting angle of the MR sensor is in the range of 30 ° to 60 °. In other words, if the mounting angle of the MR sensor is less than 30 °, almost the magnetic flux density is applied to the magnetic sensing portion of the MR sensor, so that the magnet 23 is close to the MR sensor and separated from the MR sensor. There is a problem that the operating magnetic flux density ON is detected twice. Further, if the mounting angle of the MR sensor exceeds 60 °, the applied magnetic field direction also changes significantly due to the effect of a sudden change in the radial magnetic flux density with a slight movement of the magnet 23. For this reason, there is a problem that the MR sensor cannot detect the magnetic flux density due to variations in the position of the MR sensor or the magnet. In short, it is possible to arrange the MR sensor in the range of the mounting angle of 30 ° to 60 °. Even if the magnet 23 is separated, the magnetic field lines obliquely cross the MR sensor's magnetic sensing portion at an optimum angle with respect to the operating magnetic field direction. It will be.

  Next, when the control unit 40 drives the actuator 2, the rotary shaft 10 rotates and the rotational force is transmitted to the valve body 13 through the male screw 18 and the female screw 19. Next, due to the contact between the upper rotation suppression plate 12 and the lower rotation suppression plate 22, the valve body 13 is restrained from rotating, and moves straight 6 mm to the valve open state or the valve closed state. The magnetic sensing portions of the valve opening MR sensor 31 and the valve closing MR sensor 32 are affected by the magnetic field generated by the actuator 2, noise, and the like. That is, while the actuator 2 is being driven, it is meaningless to use the valve opening MR sensor 31 and the valve closing MR sensor 32, and therefore the position detection of the valve body 13 is stopped. In short, the valve opening MR sensor 31 and the valve closing MR sensor 32 are for confirming a valve open state or a valve closed state.

  On the other hand, in order to expand the allowable operating magnetic field direction range, it is effective to increase the thickness of the magnet 23. However, the magnet 23 is unnecessarily large, and there is a problem that it is difficult to fix the magnet 23 to the valve body 13.

  Further, the position of the valve body 13 is regulated by the base 8 in the valve open state, and the position of the valve body 13 is regulated by the valve seat 27 in the valve closed state. Therefore, since the position variation of the valve body 13 is restricted, the position variation of the magnet 23 is suppressed. Therefore, the valve opening MR sensor 31 is disposed above the magnet 23 (for example, 1 mm) in the valve open state, and the valve closed state. The valve closing MR sensor 32 is disposed below the magnet 23 (for example, 1 mm). That is, if the MR sensor is shifted from the magnet 23 in advance so that the peak of the axial magnetic flux density can be detected immediately after the magnet 23 moves (for example, 1 mm movement), the allowable operating magnetic field direction range can be used effectively. Accordingly, the magnet 23 can be made thinner.

  In the present embodiment, a cylindrical neodymium magnet is used as the magnet 23. However, if the distance between the magnetism sensing portion of the valve opening MR sensor 31 and the valve closing MR sensor 32 and the magnet is short, a summer coke having a low magnetic force is used. A magnet or a ferrite magnet may be used. In short, the material and shape of the magnet 23 are not limited as long as the magnetic sensing portions of the valve opening MR sensor 31 and the valve closing MR sensor 32 exceed the operating magnetic flux density ON. The MR sensor mounting portion 30 is formed of a single plate, but the valve opening MR sensor 31 and the valve closing MR sensor 32 are inclined at an arbitrary angle with respect to the circumferential direction of the magnet 23, for example, 45 °. There is no problem even if only two locations around the positioning pin 35 are provided.

  In addition, information on the magnetic flux density detected by the valve opening MR sensor 31 and the valve closing MR sensor 32 is sent to and processed by some control unit, but the subject that performs the processing is not particularly limited. For example, when a control unit that controls the actuator 2 is provided, the control unit may have a function of processing such information. Or the control part for detecting the position of the valve body 13 may be provided separately from the control part. Moreover, the fluid control valve 1 of Embodiment 1 does not necessarily need to be provided with the control part.

  The above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention. In particular, the fluid control valve can be mounted in any direction other than vertical, such as horizontal, diagonal, and mounting directions.

  The fluid control valve of the present invention is useful for detecting the position of the valve body by attaching the MR sensor so as to be inclined with respect to the circumferential direction of the magnet.

DESCRIPTION OF SYMBOLS 1 Fluid control valve 2 Actuator 4 Flow path 13 Valve body 23 Magnet 24 S pole 25 N pole 31 MR sensor for valve opening 32 MR sensor for valve closing 33 Board | substrate 41 Drive circuit 42 Valve body position detection circuit

Claims (5)

A valve body for opening and closing the flow path;
A magnet fixed to the valve body such that the S pole and the N pole are in the moving direction of the valve body;
An MR sensor using a magnetoresistive effect close to the magnet after the valve body has moved,
An actuator for driving the valve body,
When the MR sensor detects an operating magnetic flux density or more by arranging the magnetic sensing part of the MR sensor so as to apply the magnetic flux density in the axial direction of the magnet and tilting with respect to the circumferential direction of the magnet, A fluid control valve in which the MR sensor and the magnet are close to each other and the position of the valve body can be determined. A substrate on which the MR sensor is mounted; the MR sensor is disposed in the vicinity of the outer edge of the substrate; the outer edge of the substrate is disposed close to the flow path; and the flow path, the MR sensor, and the substrate are disposed in this order. The fluid control valve according to claim 1. 2. The fluid control valve according to claim 1, wherein the magnetosensitive part of the MR sensor is inclined by 30 ° to 60 ° with respect to a circumferential direction of the magnet. The fluid control valve according to any one of claims 1 to 3, a drive circuit for the fluid control valve, and a valve body position detection circuit that detects the position of the valve body by a signal from the MR sensor, The valve body position detection circuit stops the position detection of the valve body by the MR sensor while the actuator is driven. The fluid control valve includes two MR sensors for detecting a valve closing position and a valve opening position of the valve body,
The shut-off device according to claim 4, wherein the valve body position detection circuit determines that the fluid control valve is in failure when both MR sensors cannot detect an operating magnetic flux density or more.