JP6857579B2 - Displacement detection device and calibration method for displacement detection device - Google Patents

Description

The present invention relates to a displacement detecting device for detecting a displacement amount of a member and a method for calibrating the displacement detecting device.

Patent Document 1 discloses a displacement detection device including a magnet that moves according to the displacement of an object to be measured and a magnetic sensor provided so as to face the magnet. In this displacement detection device, the position of the magnet changes according to the displacement of the object to be measured, and the direction and magnitude of the magnetic flux passing through the magnetic sensor changes as the position of the magnet changes. Therefore, the output value of the magnetic sensor The amount of displacement of the object to be measured can be specified based on.

Japanese Unexamined Patent Publication No. 2016-11833

Generally, in a displacement detection device using a magnetic sensor, the magnetic flux passing through the magnetic sensor changes non-linearly with respect to the displacement of the object to be measured, that is, the displacement of the magnet, so that the output of the magnetic sensor is also the object to be measured. It changes non-linearly with respect to displacement. Therefore, in order to change the output value of the magnetic sensor linearly with respect to the displacement of the object to be measured, the output value of the magnetic sensor with respect to the displacement amount of the object to be measured in the displacement detectable range is grasped in advance, and the output of the magnetic sensor is obtained. Calibration must be done to set a correction map that corrects the values linearly.

Since the output value of the magnetic sensor changes according to a slight change in the distance between the magnetic sensor and the magnet, when the above-mentioned calibration is performed in the displacement detection device described in Patent Document 1, the magnetic sensor in the radial direction is used. Ideally, the magnet should be moved in the axial direction while keeping the distance from the magnet constant. However, in the displacement detection device described in Patent Document 1, since the magnet is attached to a member that is cantilevered and supported by the casing, it is structurally difficult to perform calibration without eccentricizing the magnet from the axis at all. is there.

That is, when the calibration is actually performed, the magnet may be eccentric to some extent either toward or away from the magnetic sensor. The correction map set in the state where the magnet is eccentric in this way causes a deviation from the ideal correction map set in the state where the magnet is not eccentric at all. Therefore, the displacement amount obtained by correcting with this correction map may have an error with respect to the actual displacement amount. For example, if calibration is performed with the magnet eccentric in the direction closer to the magnetic sensor and then the displacement amount is detected with the magnet eccentric in the direction away from the magnetic sensor, it is corrected by the correction map. The obtained displacement amount will have a relatively large error with respect to the actual displacement amount.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the detection error of the displacement detection device.

The first invention was measured when the output correction unit that corrects the output value of the magnetic sensor displaced the displacement member in the displacement direction while the displacement member was tilted in the direction in which the magnet and the magnetic sensor approached each other. The first output value of the magnetic sensor and the second output value of the magnetic sensor measured when the displacement member is displaced in the displacement direction while the displacement member is tilted in the direction in which the magnet and the magnetic sensor are separated from each other. It has a correction map set based on the correction map, and is characterized in that the output value of the magnetic sensor is corrected so as to change linearly with respect to the displacement amount of the displacement member based on the correction map.

In the first invention, the displacement member is tilted with respect to the support member, and the magnetic sensor is measured in two states, one in which the magnet and the magnetic sensor are close to each other and the other in which the magnet and the magnetic sensor are separated from each other. The correction map is set based on the output value. Since the correction map set in this way is close to the ideal correction map set when the magnet moves on the axis of the support member, the displacement amount detected by the displacement detection device and the actual correction map are obtained. It is possible to reduce the error with the displacement amount of.

In the second invention, the correction map is a difference between the average output value, which is the average value of the first output value and the second output value, and the reference output value, which changes linearly with respect to the displacement amount of the displacement member. It is characterized in that it is set based on.

In the second invention, the correction map setting is such that the output value of the magnetic sensor measured in a state where the displacement member is tilted in the direction in which the magnet and the magnetic sensor are close to each other and the displacement in the direction in which the magnet and the magnetic sensor are separated from each other. It is performed based on the output value of the magnetic sensor measured in a state where the member is tilted and the average output value which is the average value of. Since the average output value is almost equal to the output value of the magnetic sensor measured when the axis of the displacement member and the axis of the support member are aligned, the correction map set based on the average output value is a magnet. Is close to the ideal correction map set when is moved on the axis of the support member. As a result, it is possible to reduce the error between the displacement amount detected by the displacement detection device and the actual displacement amount.

The third invention is characterized in that the magnetic sensor is a Hall element whose output value changes according to the angle of the passing magnetic flux.

In the third invention, a Hall element is used as the magnetic sensor. Since the output value of the Hall element changes responsively to the change of the magnetic flux that changes according to the movement of the magnet, the displacement of the displacement member can be detected accurately based on the output value of the Hall element.

In the fourth invention, in a state where the displacement member is tilted in the direction in which the magnet and the magnetic sensor are close to each other, the displacement member is displaced in the displacement direction to measure the first output value of the magnetic sensor, and the magnet and the magnetic sensor are mutually attached. When the displacement member is tilted in the direction away from the displacement member, the displacement member is displaced in the displacement direction to measure the second output value of the magnetic sensor, and the output value of the magnetic sensor is changed linearly with respect to the displacement amount of the displacement member. It is characterized in that the correction map to be corrected to is set based on the first output value and the second output value.

In the fourth invention, the displacement member is tilted with respect to the support member, and the magnetic sensor is measured in two states, one in which the magnet and the magnetic sensor are close to each other and the other in which the magnet and the magnetic sensor are separated from each other. The correction map is set based on the output value. Since the correction map set in this way is close to the ideal correction map set when the magnet moves on the axis of the support member, the displacement amount detected by the displacement detection device and the actual correction map are obtained. It is possible to reduce the error with the displacement amount of.

According to the present invention, the detection error of the displacement detection device can be reduced.

It is sectional drawing of the displacement detection apparatus which concerns on embodiment of this invention. It is a graph which shows the output of the magnetic sensor of the displacement detection device which concerns on embodiment of this invention. It is a graph which shows the correction value which corrects the output value of the magnetic sensor of the displacement detection device which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The displacement detection device 100 according to the embodiment of the present invention is attached to a valve device including a valve body such as a spool valve, and detects the displacement amount (stroke amount) of the valve body. Hereinafter, the displacement detection device 100 will be described with reference to FIG.

The displacement detection device 100 includes a rod member 22 as a displacement member that displaces following the valve body of the valve device that is a displacement detection target member, and a magnet 24 that is arranged on one end side of the rod member 22 and displaces together with the rod member 22. A casing 12 as a support member that reciprocally supports the rod member 22 in the displacement direction, and a spring 27 as an urging member that is arranged in the casing 12 and urges the rod member 22 toward the displacement detection target member. And a magnetic detector 32 arranged on the casing 12 so as to face the magnet 24 in a direction orthogonal to the displacement direction of the magnet 24.

The casing 12 is a bottomed tubular member formed of a non-magnetic material such as brass, and is formed inside the cylindrical cylindrical portion 12a, the bottom portion 12b provided on one end side of the cylindrical portion 12a, and the cylindrical portion 12a. It has a casing 12c and a housing portion 12c. The magnetic detection unit 32 is arranged in the cylindrical portion 12a, and a part of the rod member 22 in which the magnet 24 is arranged together with the magnet 24 is accommodated in the accommodating portion 12c. Further, a through hole 12d through which the rod member 22 is inserted is formed in the bottom portion 12b.

Bush 18s that slidably support the rod member 22 are provided in the through holes 12d at two positions separated in the axial direction. By providing bushes 18 for supporting the rod member 22 at two places, the axis of the rod member 22 cantilevered and supported by the casing 12 is tilted with respect to the axis O of the casing 12, which is the axis of the through hole 12d. This can be suppressed to some extent. The bush 18 may be provided at one place, in which case the axial length of the casing 12 can be shortened.

The rod member 22 is formed at the shaft portion 22a slidably supported by the casing 12 via the bush 18, the hemispherical contact portion 22b formed at the tip of the shaft portion 22a, and the base end of the shaft portion 22a. It has a flange portion 22c and which is accommodated in the accommodating portion 12c. Further, the flange portion 22c is provided with a holding portion 22d extending on the opposite side of the shaft portion 22a coaxially with the shaft portion 22a. In terms of design, the rod member 22 is supported by the casing 12 so that the axis of the rod member 22 and the axis O of the casing 12 are arranged coaxially.

The rod member 22 is made of a non-magnetic material like the casing 12, but is made of austenitic stainless steel or the like having a certain degree of hardness because a valve body such as a spool valve comes into contact with the contact portion 22b. Is preferable. The outer diameter of the flange portion 22c is set smaller than the inner diameter of the accommodating portion 12c so that the outer edge of the flange portion 22c does not come into contact with the cylindrical portion 12a even when the rod member 22 is tilted with respect to the casing 12. Has been done.

The magnet 24 is formed in a tubular shape, and is arranged on the outer periphery of the holding portion 22d so that the N pole 24a and the S pole 24b are aligned in the axial direction of the holding portion 22d. Further, the magnet 24 is assembled to the holding portion 22d so that the axis of the magnet 24 coincides with the axis of the rod member 22. That is, the outer peripheral surface of the magnet 24 and the outer peripheral surface of the holding portion 22d are concentric.

The magnet 24 is fixed to the holding portion 22d by engaging the C-shaped retaining ring 26 to the holding portion 22d. Further, a cushioning material 25 formed of an elastically deformable member is provided between the magnet 24 and the retaining ring 26. Therefore, when the magnet 24 is assembled to the holding portion 22d, the cushioning material 25 is deformed, and the magnet 24 is pressed against the flange portion 22c by the restoring force of the cushioning material 25. Therefore, the magnet 24 is fixed at a predetermined position with respect to the rod member 22 without having any play in the axial direction. Further, since the force acting on the magnet 24 during assembly is absorbed by the cushioning material 25, it is possible to prevent the magnet 24 from being damaged when the magnet 24 is assembled to the rod member 22.

The lid member 14 is inserted and fixed to the open end of the accommodating portion 12c in a state where the magnet 24 and a part of the rod member 22 to which the magnet 24 is assembled are accommodated in the accommodating portion 12c. Like the casing 12, the lid member 14 is made of a non-magnetic material such as brass. A seal member (not shown) is provided between the lid member 14 and the accommodating portion 12c, and the seal member blocks communication between the inside and the outside of the accommodating portion 12c. As a fixing method of the lid member 14, a general fixing method such as press fitting or screwing is used. Further, the lid member 14 may be pressed and fixed to the casing 12 by assembling a member different from the lid member 14 to the casing 12.

The spring 27 is a coil spring made of a non-magnetic material such as austenitic stainless steel, and is assembled between the flange portion 22c and the lid member 14 in a compressed state. Therefore, when the contact portion 22b is in contact with the displacement detection target member, the rod member 22 is pressed toward the displacement detection target member by the urging force of the spring 27, and the contact portion 22b and the displacement detection target member are brought into contact with each other. It is prevented from leaving. That is, by providing the spring 27, the rod member 22 can be displaced following the displacement detection target member. When the displacement detection target member is not in contact with the contact portion 22b, the rod member 22 is pressed by the urging force of the spring 27, and the flange portion 22c is in contact with the bottom portion 12b.

The magnetic detector 32 includes a Hall element 32a as a magnetic sensor that outputs an output value according to a change in the magnetic field due to the displacement of the magnet 24, and a correction circuit 32b as an output correction unit that corrects the output value of the Hall element 32a. Has. The magnetic detector 32 is assembled to the substrate 34, and is assembled to the cylindrical portion 12a via the substrate 34.

Specifically, the cylindrical portion 12a has a fixing hole 12e that opens on the outer peripheral surface of the cylindrical portion 12a and is formed toward the accommodating portion 12c, and an accommodating hole that is further formed from the fixing hole 12e toward the accommodating portion 12c. 12f is provided, and the Hall element 32a is accommodated in the accommodating hole 12f by fixing the substrate 34 to the step portion connecting the fixing hole 12e and the accommodating hole 12f. In addition to the correction circuit 32b, the magnetic detector 32 has an output value processing circuit (not shown) such as an amplifier circuit that amplifies the output value of the Hall element 32a and an offset circuit that offsets the output value of the Hall element 32a.

The Hall element 32a detects the magnetic field generated by the magnet 24 by utilizing the Hall effect, and in the displacement detection device 100, the Hall element 32a has a type of hole whose output value changes according to the angle of the magnetic flux passing through the Hall element 32a. The element 32a is used. Since the angle of the magnetic flux passing through the Hall element 32a changes as the magnet 24 moves in the axial direction, the output value of the Hall element 32a changes responsively according to the movement of the magnet 24. .. That is, based on the output value of the Hall element 32a, the displacement of the rod member 22, that is, the displacement of the displacement detection target member that abuts on the rod member 22 can be detected with high accuracy.

The Hall element 32a is not limited to a form in which the output value changes according to the angle of the magnetic flux, and the magnitude of the magnetic flux passing through the Hall element 32a in a predetermined direction, for example, in a direction orthogonal to the displacement direction of the magnet 24. The output value may change according to the passing direction. The magnetic sensor is not limited to the Hall element 32a, and may be any magnetic sensor as long as it can output an output value according to a change in the magnetic field due to the displacement of the magnet 24. (MR element) or coil may be used.

The correction circuit 32b stores a correction map set by a calibration method described later, and the correction circuit 32b linearly sets the output value of the Hall element 32a with respect to the displacement amount of the rod member 22 based on the correction map. Correct so that it changes to. The corrected correction output value is output to the outside as a detection value of the displacement detection device 100. The correction circuit 32b and other output value processing circuits are provided on the substrate 34 together with the Hall element 32a. Instead, these circuits are provided outside the displacement detection device 100 separately from the Hall element 32a. It may be provided. Further, the Hall element 32a and the correction circuit 32b may be formed on one chip.

With the magnetic detector 32 arranged in the fixing hole 12e, a cylindrical magnetic shield 16 is assembled on the outer periphery of the cylindrical portion 12a so as to cover the fixing hole 12e. The magnetic shield 16 is formed of a magnetic material and suppresses the influence of magnetism outside the displacement detection device 100 on the Hall element 32a. Further, a notch (not shown) is formed in the magnetic shield 16, and a lead wire (not shown) connecting the controller (not shown) that controls the operation of the valve body or the like as the displacement detection target member and the magnetic detector 32 through the notch is formed. Be laid out.

Next, a method of calibrating the displacement detection device 100 will be described with reference to FIGS. 1 to 3. Here, the calibration of the displacement detection device 100 is to measure the output value of the Hall element 32a with respect to the displacement amount of the displacement detection target member, calculate the deviation between the measured output value and the reference output value, and measure the output. It means to set a correction value for correcting the value to the reference output value. Calculations and the like related to calibration are executed in the correction circuit 32b.

Here, since the output value of the Hall element 32a changes according to a slight change in the distance between the Hall element 32a and the magnet 24, in order to perform accurate calibration in the displacement detection device 100 having the above configuration, it is necessary to perform accurate calibration. Ideally, the magnet 24 is moved together with the rod member 22 in the axial direction while the distance between the Hall element 32a and the magnet 24 in the radial direction is always constant. However, in the displacement detection device 100, since the rod member 22 to which the magnet 24 is attached is cantilevered and supported by the casing 12, the magnet 24 is structurally calibrated without being eccentric from the axial center O of the casing 12. That is difficult.

That is, when actually performing the calibration, the magnet 24 is eccentric to some extent in the direction toward or away from the Hall element 32a. The correction value set in the state where the magnet 24 is eccentric in this way causes a deviation from the ideal correction value set when the magnet 24 moves on the axis O of the casing 12. Therefore, the displacement amount calculated based on the correction map set in a state where the magnet 24 is eccentric in any direction may have an error with respect to the actual displacement amount.

Further, for example, after the correction value is set in a state where the magnet 24 is eccentric in the direction approaching the Hall element 32a, the displacement amount is detected in a state where the magnet 24 is eccentric in the direction away from the Hall element 32a. In this case, the set correction map is deviated from the ideal correction map, and the magnet 24 and the Hall element 32a are in the state where the correction map is set and the state where the displacement amount is detected. The intervals will be very different. Therefore, the displacement amount calculated based on the correction map set in this way has a relatively large error with respect to the actual displacement amount.

Therefore, in the present embodiment, in order to reduce such an error, when the displacement detection device 100 is calibrated, the rod member 22 is intentionally tilted with respect to the casing 12, and the magnet 24 and the Hall element 32a are arranged. Measured in two states facing each other, that is, the state in which the magnet 24 and the Hall element 32a are closest to each other, that is, the state in which the change in the magnetic flux passing through the Hall element 32a is relatively large and the state in which the change in the magnetic flux passing through the Hall element 32a is relatively small. The correction value is set based on the output value of the Hall element 32a.

Specifically, as shown in FIG. 1, when calibrating the displacement detection device 100, a columnar calibration jig 50 having an inclined surface 50a at the tip that contacts the contact portion 22b of the rod member 22 is used. Used. The calibration jig 50 is connected to a displacement meter whose base end side is not shown, and the displacement amount of the calibration jig 50 is displayed on the displacement meter.

The displacement detection device 100 is calibrated by moving the calibration jig 50 having the above shape along the direction indicated by the arrow A in FIG. 1, that is, along the axial direction of the rod member 22.

Specifically, first, as shown in FIG. 1, the calibration jig is in a state where the vertical line P of the inclined surface 50a of the calibration jig 50 faces the side opposite to the Hall element 32a from the axial center O of the casing 12. Move 50 in the direction indicated by arrow A. At this time, the rod member 22 is displaced in the direction indicated by the arrow B on the contact portion 22b side that abuts on the inclined surface 50a with the portion supported by the casing 12 as a fulcrum, and the holding portion 22d side on which the magnet 24 is provided is the arrow C. The rod member 22 is tilted most toward each other in the direction indicated by the above, that is, the magnet 24 and the Hall element 32a are tilted toward each other. In other words, the approaching side inclined state means that the rod member 22 is in one direction from the state where the axis of the rod member 22 and the axis O of the casing 12 are aligned, that is, in the direction in which the magnet 24 and the Hall element 32a are close to each other. Is inclined, and it can be said that the change in the magnetic flux passing through the Hall element 32a is relatively large.

In this approaching side tilted state, the calibration jig 50 is displaced over the displacement detectable range of the displacement detection device 100, and the Hall element 32a approaches as the first output value with respect to the displacement amount of the displacement detection target member (calibration jig 50). The side output value is measured. As shown in FIG. 2, the measured approach side output value is linearly shown as an approach side output line. Since the angle of the magnetic flux passing through the Hall element 32a changes non-linearly according to the displacement of the magnet 24, the approaching output line changes non-linearly with respect to the displacement of the displacement detection target member.

Subsequently, the calibration jig 50 is rotated by 180 °, and the calibration jig 50 is indicated by an arrow A in a state where the perpendicular line P of the inclined surface 50a of the calibration jig 50 faces the Hall element 32a side with respect to the axial center O of the casing 12. Move in the indicated direction. At this time, the rod member 22 is held so that the contact portion 22b side in contact with the inclined surface 50a is displaced in the direction opposite to the direction indicated by the arrow B with the portion supported by the casing 12 as a fulcrum, and the magnet 24 is provided. The portion 22d side is displaced in the direction opposite to the direction indicated by the arrow C, that is, the rod member 22 is tilted most in the direction in which the magnet 24 and the hole element 32a are separated from each other. In other words, the separated side inclined state means that the rod member 22 is in the other direction from the state where the axis of the rod member 22 and the axis O of the casing 12 are aligned, that is, in the direction in which the magnet 24 and the Hall element 32a are separated from each other. Is inclined, and it can be said that the change in the magnetic flux passing through the Hall element 32a is relatively small.

Even in this separated-side tilted state, the calibration jig 50 is displaced over the displacement-detectable range of the displacement detection device 100, and the Hall element with respect to the displacement amount of the displacement-detected member (calibration jig 50) is displaced in the same manner as in the approach-side tilted state. The separation side output value as the second output value of 32a is measured. As shown in FIG. 2, the measured distance-side output value is linearly shown as a distance-side output line. Like the approaching output line, the separating side output line changes non-linearly with respect to the displacement of the displacement detection target member.

Subsequently, the average output value, which is the average value of the approach side output value and the distance side output value, is calculated, and the correction value for correcting the average output value to the reference output value is set.

Here, the average output value is the approach side output value measured in a state where the rod member 22 is tilted in the direction in which the magnet 24 and the Hall element 32a are close to each other, and the rod in the direction in which the magnet 24 and the Hall element 32a are separated from each other. It is an average value of the separated side output value measured in a state where the member 22 is tilted. That is, the average output value is substantially equal to the output value of the Hall element 32a measured in a state where the inclination of the rod member 22 is in the middle, that is, in a state where the axis of the rod member 22 and the axis O of the casing 12 coincide with each other. It can be said that. Therefore, the correction value set based on the average output value is close to the ideal correction value.

As shown in FIG. 2, the average output value is linearly shown as an average output line. The average output line, like the approach side output line and the distance side output line, changes non-linearly with respect to the displacement of the displacement detection target member.

The reference output value is a value that changes linearly with respect to the displacement of the displacement detection target member, may have a preset inclination, or is a straight line between the minimum value and the maximum value of the average output value. It may be tied to the target. The reference output value is shown as a linear reference output line as shown in FIG.

The correction value is calculated by subtracting the average output value from the reference output value for the same displacement amount. For example, in FIG. 2, when the average output value is Y1 and the reference output value is Y2 for an arbitrary displacement amount X1, the correction value is (Y2-Y1). Then, as shown in FIG. 3, this correction value (Y2-Y1) becomes a correction value when the output value of the Hall element 32a becomes Y1.

As shown in FIG. 3, the correction values calculated in this way are different values depending on the output value of the Hall element 32a. Therefore, the correction value set for each output value of the Hall element 32a is stored in the correction circuit 32b as a correction map.

A series of calibrations is completed when the correction map is stored in the correction circuit 32b. After the calibration is completed, when the displacement of the displacement detection target member is detected by the displacement detection device 100, the correction value set as described above is added to the output value of the Hall element 32a. It is output as a detection value from the displacement detection device 100. For example, as shown in FIG. 3, when the output value of the Hall element 32a is Y1, Y2, which is the value obtained by adding the correction value (Y2-Y1) to Y1, is output as a detection value from the displacement detection device 100. To.

According to the above embodiment, the following effects are obtained.

In the displacement detection device 100, the correction map is set by the output value of the Hall element 32a measured in a state where the rod member 22 is tilted in the direction in which the magnet 24 and the Hall element 32a approach each other, and the magnet 24 and the Hall element 32a. Is performed based on the output value of the Hall element 32a measured in a state where the rod members 22 are tilted in the direction away from each other and the average output value which is the average value of the Hall elements 32a. Here, the average output value is substantially equal to the output value of the Hall element 32a measured in a state where the inclination of the rod member 22 is in the middle, that is, in a state where the axis of the rod member 22 and the axis O of the casing 12 coincide with each other. It can be said that they are equal. That is, it can be said that the correction map set based on the average output value is close to the ideal correction map set when the magnet 24 moves on the axis O of the casing 12.

The correction map set in the displacement detection device 100 in this way is compared with the correction map set based on the output value of the Hall element 32a measured in a state where the eccentric direction of the magnet 24 is unknown, and is an ideal correction. It will be close to the map. Therefore, if the value detected by the Hall element 32a is corrected by the correction map set based on the average output value and the displacement amount is calculated, the error between the displacement amount detected by the displacement detection device 100 and the actual displacement amount is calculated. Can be reduced.

The configuration, operation, and effect of the embodiment of the present invention configured as described above will be collectively described.

The displacement detection device 100 reciprocates the rod member 22 that displaces following the member subject to displacement detection, the magnet 24 that is arranged on one end side of the rod member 22 and displaces together with the rod member 22, and the rod member 22 in the displacement direction. A casing 12 that freely supports the magnet 24 and a magnetic detection unit 32 that is arranged on the casing 12 so as to face the magnet 24 in a direction orthogonal to the displacement direction of the magnet 24. The magnetic detection unit 32 displaces the magnet 24. It has a Hall element 32a that outputs an output value according to a change in the magnetic field accompanying the change in the magnetic field, and a correction circuit 32b that corrects the output value of the Hall element 32a. The approach side output value of the hole element 32a measured when the rod member 22 is displaced in the displacement direction while the rod member 22 is most tilted in the approaching direction, and the rod in the direction in which the magnet 24 and the hole element 32a are separated from each other. It has a correction map set based on the separated side output value of the hole element 32a measured when the rod member 22 is displaced in the displacement direction in the state where the member 22 is most tilted, and is based on the correction map. It is characterized in that the output value of the hole element 32a is corrected so as to change linearly with respect to the displacement amount of the rod member 22.

In this configuration, the rod member 22 is intentionally tilted with respect to the casing 12, and the state in which the magnet 24 and the Hall element 32a are closest to each other and the state in which the magnet 24 and the Hall element 32a are closest to each other are opposed to each other. The correction map is set based on the output values of the Hall element 32a measured in one state, that is, the state in which the change in the magnetic flux passing through the Hall element 32a is relatively large and the state in which the change in the magnetic flux passing through the Hall element 32a is relatively large and relatively small.

The correction map set based on the output value of the Hall element 32a measured in the two opposing states is based on the output value of the Hall element 32a measured in the state where the eccentric direction of the magnet 24 is unknown. Compared with the set correction map, the magnet 24 is closer to the ideal correction map set when the magnet 24 moves on the axis O of the casing 12. Therefore, if the value detected by the Hall element 32a is corrected by the correction map set based on the output values of the Hall element 32a measured in the two opposing states and the displacement amount is calculated, the displacement detection device 100 detects the value. It is possible to reduce the error between the displacement amount and the actual displacement amount.

Further, even when the displacement amount is detected by the displacement detection device 100 in a state of being eccentric in the direction in which the magnet 24 approaches the Hall element 32a or in the direction away from the Hall element 32a, the displacement detection device 100 is set. The correction map is close to the ideal correction map set when the magnet 24 moves on the axis O of the casing 12. Therefore, if the value detected by the Hall element 32a is corrected by the set correction map and the displacement amount is calculated, the error between the displacement amount detected by the displacement detection device 100 and the actual displacement amount can be suppressed. it can.

Further, in this configuration, the correction map is set based on the output value of the Hall element 32a obtained by only two measurements. Therefore, since it is not necessary to measure the output value of the Hall element 32a many times in order to set the correction map, the time spent for calibration can be shortened.

Further, the correction map is set based on the difference between the average output value which is the average value of the approach side output value and the distance side output value and the reference output value which changes linearly with respect to the displacement amount of the rod member 22. It is characterized by being done.

In this configuration, the correction map is set by setting the output value of the Hall element 32a measured in a state where the rod member 22 is tilted in the direction in which the magnet 24 and the Hall element 32a approach each other, and the magnet 24 and the Hall element 32a mutually. This is performed based on the output value of the Hall element 32a measured in a state where the rod member 22 is tilted in the direction of separation and the average output value which is the average value of the Hall element 32a.

It can be said that the average output value is substantially equal to the output value of the Hall element 32a measured in a state where the inclination of the rod member 22 is in the middle, that is, when the axis of the rod member 22 and the axis O of the casing 12 coincide with each other. .. That is, it can be said that the correction map set based on the average output value is close to the ideal correction map set when the magnet 24 moves on the axis O of the casing 12.

The correction map set based on the average output value in this way is compared with the correction map set based on the output value of the Hall element 32a measured in a state where the eccentric direction of the magnet 24 is unknown. It is close to the ideal correction map set when the casing 12 is moved on the axis O. Therefore, if the value detected by the Hall element 32a is corrected by the correction map set based on the average output value and the displacement amount is calculated, the error between the displacement amount detected by the displacement detection device 100 and the actual displacement amount is calculated. Can be reduced.

Further, the Hall element 32a is used as the magnetic sensor, and the Hall element 32a is characterized in that the output value changes according to the angle of the magnetic flux passing through the Hall element 32a.

In this configuration, the Hall element 32a is used as the magnetic sensor. The output value of the Hall element 32a changes responsively in response to a change in the magnetic field that changes in response to the movement of the magnet 24. Therefore, based on the output value of the Hall element 32a, the displacement of the rod member 22, that is, the displacement of the displacement detection target member that abuts on the rod member 22 can be accurately detected.

Further, when a Hall element 32a whose output value changes according to the angle of the magnetic flux passing through the Hall element 32a is adopted, the angle of the magnetic flux passing through the Hall element 32a is such that the magnet 24 moves in the axial direction. Therefore, the output value of the Hall element 32a changes more responsively according to the movement of the magnet 24. Therefore, based on the output value of the Hall element 32a, the displacement of the rod member 22, that is, the displacement of the displacement detection target member that abuts on the rod member 22, can be detected more accurately.

Further, a rod member 22 that displaces following the member to be detected for displacement, a magnet 24 arranged on one end side of the rod member 22, a casing 12 that reciprocally supports the rod member 22 in the displacement direction, and a magnet 24. Hall element 32a, which is arranged on the casing 12 so as to face the magnet 24 in a direction orthogonal to the displacement direction of the magnet 24 and outputs an output value according to a change in the magnetic field due to the displacement of the magnet 24, and corrects the output value of the hole element 32a. In the calibration method of the displacement detection device 100 including the correction circuit 32b for correction based on the map, the rod member 22 is displaced in the displacement direction when the rod member 22 is most tilted in the direction in which the magnet 24 and the hole element 32a are closest to each other. The hole element 32a is displaced to measure the output value on the approaching side, and the rod member 22 is displaced in the displacement direction in a state where the rod member 22 is most tilted in the direction in which the magnet 24 and the hole element 32a are separated from each other. A correction map is set based on the approaching side output value and the separating side output value, which measures the separated side output value and corrects the output value of the Hall element 32a so as to change linearly with respect to the displacement amount of the rod member 22. It is characterized by that.

In this configuration, the rod member 22 is intentionally tilted with respect to the casing 12, and the state in which the magnet 24 and the Hall element 32a are closest to each other and the state in which the magnet 24 and the Hall element 32a are closest to each other are opposed to each other. The correction map is set based on the output values of the Hall element 32a measured in one state, that is, the state in which the change in the magnetic flux passing through the Hall element 32a is relatively large and the state in which the change in the magnetic flux passing through the Hall element 32a is relatively large and relatively small.

The correction map set based on the output value of the Hall element 32a measured in the two opposing states is based on the output value of the Hall element 32a measured in the state where the eccentric direction of the magnet 24 is unknown. Compared with the set correction map, the magnet 24 is closer to the ideal correction map set when the magnet 24 moves on the axis O of the casing 12. Therefore, if the value detected by the Hall element 32a is corrected by the correction map set based on the output values of the Hall element 32a measured in the two opposing states and the displacement amount is calculated, the displacement detection device 100 detects the value. It is possible to reduce the error between the displacement amount and the actual displacement amount.

Further, even when the displacement amount is detected by the displacement detection device 100 in a state of being eccentric in the direction in which the magnet 24 approaches the Hall element 32a or in the direction away from the Hall element 32a, the displacement detection device 100 is set. The correction map is close to the ideal correction map set when the magnet 24 moves on the axis O of the casing 12. Therefore, if the value detected by the Hall element 32a is corrected by the set correction map and the displacement amount is calculated, the error between the displacement amount detected by the displacement detection device 100 and the actual displacement amount can be suppressed. it can.

Further, in this configuration, the correction map is set based on the output value of the Hall element 32a obtained by only two measurements. Therefore, since it is not necessary to measure the output value of the Hall element 32a many times in order to set the correction map, the time spent for calibration can be shortened.

Further, in the calibration method of the displacement detection device 100, the average output value is calculated by averaging the approach side output value and the distance side output value, and the average output value and the displacement amount of the rod member 22 are linearly changed. It is characterized in that a correction map is set based on the difference between the reference output value to be measured and the difference.

In this configuration, the correction map is set by setting the output value of the Hall element 32a measured in a state where the rod member 22 is tilted in the direction in which the magnet 24 and the Hall element 32a approach each other, and the magnet 24 and the Hall element 32a mutually. This is performed based on the output value of the Hall element 32a measured in a state where the rod member 22 is tilted in the direction of separation and the average output value which is the average value of the Hall element 32a.

It can be said that the average output value is substantially equal to the output value of the Hall element 32a measured in a state where the inclination of the rod member 22 is in the middle, that is, when the axis of the rod member 22 and the axis O of the casing 12 coincide with each other. .. That is, it can be said that the correction map set based on the average output value is close to the ideal correction map set when the magnet 24 moves on the axis O of the casing 12.

The correction map set based on the average output value in this way is compared with the correction map set based on the output value of the Hall element 32a measured in a state where the eccentric direction of the magnet 24 is unknown. It is close to the ideal correction map set when the casing 12 is moved on the axis O. Therefore, if the value detected by the Hall element 32a is corrected by the correction map set based on the average output value and the displacement amount is calculated, the error between the displacement amount detected by the displacement detection device 100 and the actual displacement amount is calculated. Can be reduced.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. Absent.

100 ... displacement detection device, 12 ... casing (support member), 22 ... rod member (displacement member), 24 ... magnet, 27 ... spring, 32 ... magnetic detector, 32a ... Hall element (magnetic sensor), 32b ... Correction circuit (output correction unit), 50 ... Calibration jig

Claims (4)

Displacement members that displace following the displacement detection target member, and
A magnet that is placed on one end side of the displacement member and displaces with the displacement member,
A support member that reciprocates the displacement member in the displacement direction,
A magnetic detector arranged on the support member so as to face the magnet.
The magnetic detector includes a magnetic sensor that outputs an output value according to a change in a magnetic field accompanying a displacement of the magnet, and an output correction unit that corrects the output value of the magnetic sensor.
The output correction unit is the first output value of the magnetic sensor measured when the displacement member is displaced in the displacement direction while the displacement member is tilted in a direction in which the magnet and the magnetic sensor approach each other. Based on the second output value of the magnetic sensor measured when the displacement member is displaced in the displacement direction while the displacement member is tilted in a direction in which the magnet and the magnetic sensor are separated from each other. The displacement detection device has a correction map set in the above direction, and corrects the output value of the magnetic sensor so as to linearly change with respect to the displacement amount of the displacement member based on the correction map. .. The correction map is based on the difference between the average output value, which is the average value of the first output value and the second output value, and the reference output value, which changes linearly with respect to the displacement amount of the displacement member. The displacement detection device according to claim 1, wherein the displacement detection device is set. The displacement detection device according to claim 1 or 2, wherein the magnetic sensor is a Hall element whose output value changes according to an angle of a passing magnetic flux. A displacement member that displaces following the displacement detection target member, a magnet that is arranged on one end side of the displacement member, and a support member that reciprocally supports the displacement member in the displacement direction so as to face the magnet. A magnetic sensor arranged on the support member and outputting an output value according to a change in the magnetic field due to the displacement of the magnet, and an output correction unit for correcting the output value of the magnetic sensor based on a correction map. This is a method of calibrating the displacement detector.
In a state where the displacement member is tilted in a direction in which the magnet and the magnetic sensor are close to each other, the displacement member is displaced in the displacement direction and the first output value of the magnetic sensor is measured.
In a state where the displacement member is tilted in a direction in which the magnet and the magnetic sensor are separated from each other, the displacement member is displaced in the displacement direction and the second output value of the magnetic sensor is measured.
The feature is that the correction map for correcting the output value of the magnetic sensor so as to change linearly with respect to the displacement amount of the displacement member is set based on the first output value and the second output value. How to calibrate the displacement detector.

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