JPH05280916A - Straight line displacement detection device - Google Patents

Abstract

PURPOSE:To obtain a straight line displacement detection device which obtains straight line output within a wide range of straight line displacement of a permanent magnet. CONSTITUTION:In a magnetic detection element 23, a ferromagnetic body magnetic resistance element with a specified pattern is formed on a glass substrate and is molded in a rectangular parallelopiped with an insulation resin. A ceramic substrate 24 mounts the magnetic detection element 23 so that the formation surface (magnet-sensitive surface) of a magnetic resistance element is vertical to the surface of the substrate and is stored and retained within a shield box 26 which is formed in one piece with a connector assembly 25. A rod-shaped permanent magnet 22 is formed in one piece with a shaft 21. The shaft 21 is laid out between a case 20 and the connector assembly 25 so that the permanent magnet 22 allows its longer axis center to be positioned on the extension surface of the magnet-sensitive surface, opposes the magnet detection element 23, and can travel in the direction of longer axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear displacement detecting device for detecting a linear displacement of a permanent magnet as a change in a magnetic flux direction on a magnetically sensitive surface of a magnetic detecting element.

[0002]

21 is a longitudinal sectional view showing a conventional linear displacement detecting device disclosed in, for example, Japanese Utility Model Publication No. 2-36089, and FIG. 22 is a transverse sectional view corresponding to FIG. In the figure, reference numeral 1 is a case body, and a shaft rod 3 in the form of a straight rod connected to an object to be measured is slidably inserted and assembled into a shaft hole formed in both end plates 2. Reference numeral 4 denotes a lid plate fitted and fixed in an opening portion of the upper surface of the case body 1. A pair of magnetic detection elements 6a, 6 is provided on the inner surface of the case body 1 with an insulating plate 5 interposed therebetween.
The element plate 7 having b is fixed, and two straight rod-shaped guide rods 8 are fixed in parallel between the leg plate pieces 4a located in the case body 1 so as to be suspended from the front and rear ends thereof. ing.

Reference numeral 9 is a permanent magnet 10 having a rectangular magnetic pole surface.
Is fixed and is slidably assembled to the two guide rods 8, and 11 is the case body 1 of the shaft rod 3.
A boss that is fixed to a suitable place inside
Reference numeral 12 is a coupling having a U-shaped cross section, which is rotatably mounted on the boss 11, and has a slider 9 between the upper ends of both ends.
Is fixed. Therefore, the slider 9 is connected to the shaft rod 3 via the coupling 12 and the boss 11, and when the shaft rod 3 is displaced, the slider 9, that is, the permanent magnet 10 fixed to the slider 9 is also guided. It will be linearly displaced along 8. Reference numeral 13 is a return spring that is fitted to the shaft rod 3 by elastically contacting the boss 11 at one end and the end plate 2 at the other end.

Here, the arrangement structure of the magnetic detection elements 6a and 6b and the permanent magnet 10 will be described with reference to FIG. The permanent magnet 10 fixed to the slider 9 has its one magnetic pole surface located on the upper surface of the slider 9, while the magnetic detection elements 6a and 6b respectively have their magnetic sensitive surfaces located on the lower surface of the element plate 7. As a result, the permanent magnet 10 and the magnetic detection elements 6a and 6b are configured such that their magnetic pole surfaces and magnetic sensitive surfaces face each other in parallel, and the permanent magnet 10 moves linearly while maintaining this parallel posture. There is. Furthermore, the permanent magnet 10
Is greater than 0 ° on the long side with respect to the displacement direction.
The magnetic detection elements 6a and 6b are mounted on the slider 9 in a posture inclined by an angle smaller than 0 °, and the magnetic detection elements 6a and 6b are also fixed to the permanent magnet 10.
The permanent magnet 10 is arranged and fixed in a posture inclined at the same angle with respect to the displacement direction.

Next, the operation of the above-mentioned conventional linear displacement detecting device will be described. When the object to be measured is connected to the shaft rod 3, the shaft rod 3 is linearly displaced by the displacement of the object to be measured. The linear displacement of the shaft rod 3 causes the slider 9, that is, the permanent magnet 10 to linearly move via the boss 11 and the coupling 12.
Therefore, as shown in FIG.
When the permanent magnet 10 is linearly moved in the direction of the arrow A from the state where the entire magnetic sensitive surface of the permanent magnet 10 faces the magnetic pole surface of the permanent magnet 10, the magnetic sensitive surface of the magnetic detection element 6a facing the magnetic pole surface of the permanent magnet 10 moves. Area decreases, and the area of the magnetic sensitive surface of the magnetic detection element 6b increases. Further, as shown in FIG. 24B, the permanent magnet 1 is moved in the direction of arrow B from the state in which the entire magnetic sensing surface of the magnetic detection element 6b is located opposite to the magnetic pole surface of the permanent magnet 10.
When 0 is linearly moved, the area of the magnetic sensitive surface of the magnetic detection element 6b facing the magnetic pole surface of the permanent magnet 10 decreases, and the area of the magnetic sensitive surface of the magnetic detection element 6a increases.

Therefore, due to the linear movement of the permanent magnet 10, the entire magnetic sensitive surface of the magnetic detecting element 6a is positioned opposite to the magnetic pole surface of the permanent magnet 10, and the entire magnetic sensitive surface of the magnetic detecting element 6b is changed to the permanent magnet. It changes up to the state in which the magnetic pole surface of 10 is located opposite.

As described above, in the conventional linear displacement detecting device, the change in the areas of the magnetic sensitive surfaces of the magnetic detecting elements 6a and 6b made of the magnetoresistive material, which face the magnetic pole surface of the permanent magnet 10, that is, the sense. A linear displacement of the permanent magnet 10 is detected by detecting a change in resistance value due to a change in a magnetic field passing vertically through a magnetic surface, and the permanent magnet 10 is arranged at an angle θ with respect to the displacement direction. If the width L of the elements 6a and 6b is L, a linear output characteristic can be obtained by the linear displacement of the permanent magnet 10 of L / sin θ.

[0008]

As described above, the conventional linear displacement detecting device is arranged such that the rectangular magnetic pole surface of the permanent magnet 10 and the rectangular magnetic sensitive surfaces of the magnetic detecting elements 6a and 6b face each other. Since the permanent magnet 10 and the magnetic detection elements 6a and 6b are arranged so as to be inclined at the same angle with respect to the displacement direction of the permanent magnet 10, the permanent magnet 10 capable of obtaining a linear output characteristic.
There was a problem that the detection linear displacement range of was narrow.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a linear displacement detecting device which can obtain a linear output characteristic in a wide detection linear displacement range. Another object of the present invention is to obtain a linear displacement detection device that can obtain a stable linear output by setting the shape of the permanent magnet and the distance between the permanent magnet and the magnetoresistive element.

A further object of the present invention is to obtain a linear displacement detecting device capable of ensuring airtightness by completely separating the fixing / accommodating region of the circuit board and the operating region of the shaft. Another object of the present invention is to obtain a linear displacement detection device capable of suppressing output fluctuations by configuring the permanent magnet so as to be movable on the central axis of the opening of the device to be detected. A further object of the present invention is to provide a linear displacement detection device that can easily perform circuit trimming according to the actual use state and can improve the assembly work.

[0011]

A linear displacement detecting device according to a first aspect of the present invention includes a magnetic detecting element having a magnetic sensitive surface formed of a ferromagnetic magnetoresistive element formed in a predetermined pattern, and A rod-shaped permanent magnet, which is arranged so as to face the magnetic detection element so that its major axis lies on the extension surface of the magnetically sensitive surface and is movable in the major axis direction, and has both end surfaces as magnetic pole surfaces. is there.

Further, the linear displacement detecting device according to the second invention of the present invention is such that the magnetic detecting device is located in a region where the equipotential distribution line of the magnetic field of the permanent magnet coincides with the direction of the magnetic field vector. Is provided.

Further, in the linear displacement detecting device according to the third aspect of the present invention, the magnetic piece is arranged on the magnetic pole surface of the permanent magnet. Further, in the linear displacement detection device according to the fourth aspect of the present invention, the ferromagnetic magnetoresistive element is formed in a pattern in which the comb-teeth pattern is symmetrically arranged in a V shape.

Further, in the linear displacement detecting device according to the fifth aspect of the present invention, the shape of the permanent magnet and the permanent magnet and the magnetoresistive element are set so that the saturation magnetic field is always applied to the ferromagnetic magnetoresistive element. The distance is set. Also,
In the linear displacement detecting device according to the sixth aspect of the present invention, the change in the magnetic flux angle across the magnetosensitive surface of the ferromagnetic magnetoresistive element in parallel is 6 ± 3 deg / mm with respect to the displacement of the permanent magnet in the long axis direction. The shape of the permanent magnet and the distance between the permanent magnet and the magnetoresistive element are set so that

Further, a linear displacement detecting device according to a seventh aspect of the present invention is a shaft for linear displacement detection including a fixed / accommodating area of a circuit board on which a ferromagnetic magnetoresistive element is mounted and a permanent magnet. The case body of the product is configured so as to be completely isolated from the operation area. The linear displacement detection device according to an eighth aspect of the present invention is the first aspect of the present invention.
When the linear displacement detection device described is mounted in the ferromagnetic opening of the non-detection device, the product is configured so as to displace the permanent magnet on the central axis of the opening.

Further, a linear displacement detecting device according to a ninth aspect of the present invention is a linear displacement detecting device according to claim 1, wherein the permanent magnet is a symmetrical ferromagnetic body with a permanent magnet as a central axis and a predetermined distance from the permanent magnet. It has a magnetic shield installed. The linear displacement detection device according to the tenth aspect of the present invention has a connector assembly for mounting a circuit board inserted and fixed in a case having an opening.

Furthermore, the eleventh aspect of the present invention is a linear displacement detecting device in which the connector assembly is provided with a guide portion for guiding and moving the permanent magnet in the longitudinal direction thereof. Further, the linear displacement detection device according to the twelfth aspect of the present invention is one in which a shield box that shields electromagnetic waves is integrally formed with the connector assembly.

[0018]

According to the first aspect of the present invention, a ferromagnetic magnetoresistive element is used, and a rod-shaped permanent magnet is provided so as to face the magnetic detecting element so that the major axis lies on the extension surface of the magnetic sensitive surface. Since they are arranged, the magnetic field of the permanent magnet flows so as to cross the magnetic sensitive surface in parallel, and when the permanent magnet is displaced in the long axis direction, the magnetic flux direction crossing the magnetic sensitive surface in parallel changes, and this magnetic flux direction changes. Causes a change in the resistance value of the ferromagnetic substance magnetic detection element, and the linear displacement of the permanent magnet is detected.

According to the second aspect of the present invention,
Since the permanent magnet is arranged so that the magnetic detection element is located in a region where the magnetic field equipotential distribution line of the permanent magnet and the direction of the magnetic field vector coincide, the magnetic detection element is arranged at the central portion of the permanent magnet. The magnetic field generated in the vicinity of the side surface is out of the distorted region of the equipotential distribution, and the deterioration of the detection performance of the magnetic sensor due to this strain is suppressed.

Further, in the third aspect of the present invention, since the magnetic material piece is arranged on the magnetic pole surface of the permanent magnet,
The amount of protrusion of the magnetic substance from the side surface of the permanent magnet causes the region of strain of the magnetic field equipotential distribution line to shift, and the amount of protrusion of the magnetic substance piece is controlled to adjust the amount of shift of the strain region.

In the fourth invention of the present invention,
Since the ferromagnetic magnetoresistive element is formed in a pattern in which the comb-shaped pattern is symmetrically arranged in a V shape, the sensitivity to a change in the magnetic flux direction across the magnetically sensitive surface of the magnetic detection element is increased.

Further, in the fifth aspect of the present invention, since the shape of the permanent magnet and the distance between the permanent magnet and the magnetoresistive element are set in consideration of the stability of the output, the place where the magnetic field becomes the weakest. The magnetic flux density at (the magnet midpoint) can be set to the saturation magnetic field of the magnetoresistive element (generally 100 G or more).

In the sixth aspect of the present invention,
Since the shape of the permanent magnet and the distance between the permanent magnet and the magnetoresistive element are set in consideration of linearity, the change in magnetic flux per unit stroke of the permanent magnet is suppressed to 6 ± 3 deg / mm.

Further, according to the seventh aspect of the present invention, since the fixing / accommodating area of the circuit board and the operating area of the shaft are completely separated from each other, water, oil and the like flowing into the operating area of the shaft are removed. Does not flow into the fixed / storage area of the circuit board.

In the eighth aspect of the present invention,
Since the permanent magnet is configured to be movable on the central axis of the opening of the device to be detected, the output fluctuation due to the influence of the ferromagnetic material opening of the device to be detected is suppressed to the minimum.

Further, in the ninth aspect of the present invention, since the magnetic shield which is a symmetrical ferromagnetic body is set with a permanent magnet as a central axis and a predetermined distance apart from the central magnet, an external ferromagnetic body and an external ferromagnetic body are provided. Output fluctuation due to magnetic field is almost completely suppressed.

According to the tenth aspect of the present invention, the circuit board can be mounted on the connector assembly, and then the connector assembly can be fitted and fixed in the opening of the case for assembly, thereby improving the assembly workability. ..

Further, in the eleventh aspect of the present invention, by incorporating a permanent magnet in the guide portion provided in the connector assembly, the actual use state is realized with the circuit board and the like exposed.

In the twelfth aspect of the present invention, the shield box is integrated with the connector assembly to reduce the number of assembly parts.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. Example 1. The first embodiment is an embodiment of the linear displacement detecting device according to the first invention of the present invention. 1 is a front view of a linear displacement detector showing Embodiment 1 of the present invention, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. 2, and FIG. 1 is an exploded perspective view, and FIG. 5 is a plan view showing an embodiment of a magnetoresistive pattern of the magnetic detection element in FIG.

In the figure, reference numeral 20 designates a case molded of, for example, polybutylene terephthalate resin, which has a shaft hole 20a at one end and an opening 20b at the other end. Reference numeral 21 is a rod-shaped permanent magnet 2 having both end faces as magnetic pole faces.
2 is an integrally molded shaft, 23 is a magnetic detection element,
For example, a magnetoresistive element 23a, which is a ferromagnetic magnetoresistive element made of NiFe which is a ferromagnetic magnetoresistive material having a magnetoresistive pattern in which comb-shaped patterns are orthogonal to each other, is formed on the surface of a glass substrate. Then, the surface of the glass substrate on which the magnetoresistive element 23a is formed is a magnetically sensitive surface 23b.

Although not shown, 24 is a ceramic substrate as a circuit substrate on which wiring patterns are formed and various electronic components are mounted, and the magnetic detection element 23 is mounted so that the magnetic sensitive surface 23b is perpendicular to the substrate surface. Has been done. Reference numeral 25 denotes a connector assembly molded of, for example, polybutylene terephthalate resin, which is integrally formed with a guide portion 25a for slidingly guiding the shaft 21, and a copper shield box 26 for shielding electromagnetic waves, a feedthrough capacitor 27, and this feedthrough. A terminal 28 which is soldered to the capacitor 27 and takes out the output of the magnetic detection element 23 is integrated. Reference numeral 29 is a spring that is contracted between the shaft 21 and the connector assembly 25 and restricts the linear displacement operation of the shaft 21.

Here, the assembly of the linear displacement detector of the first embodiment will be described. First, the ceramic substrate 24 on which the magnetic detection element 23 is mounted is mounted in the shield box 26 integrated with the connector assembly 25,
After that, the shield box 26a made of copper is used to shield the shield box 26.
Seal the opening. Next, the connector assembly 25 is inserted and fixed in the case 20 through the opening 20b with the shaft 21 set in the guide portion 25a together with the spring 29.

In the linear displacement detecting device thus assembled, the shaft 21 in which the rod-shaped permanent magnet 22 is integrated
Is slidably guided by the guide portion 25a and linearly movable, and the permanent magnet 22 faces the magnetic detection element 23 and its long axis is located on the extension surface of the magnetic sensing surface 23b. Therefore, the magnetic field generated by the permanent magnet 22 crosses the magnetic sensitive surface 23b of the magnetic detection element 23 in parallel.

Next, the operation of the linear displacement detector of the first embodiment will be described. The shaft 21 connected to the device to be detected (not shown) slides by being guided by the guide portion 25a of the connector assembly 25 in association with the displacement of the device to be detected against the urging force of the spring 29, and is permanently moved. The magnet 22 is linearly displaced in the long axis direction. Therefore, the permanent magnet 22 integrated with the shaft 21 is also linearly displaced in the long axis direction in association with the displacement of the detected device. Due to the linear displacement of the permanent magnet 22, the magnetic flux direction that crosses the magnetic sensitive surface 23b of the magnetic detection element 23 in parallel changes, and the magnetic resistance pattern of the magnetic resistance element 23a changes according to the change in the magnetic flux direction that crosses the magnetic sensitive surface 23b. The respective resistance values of the orthogonal comb-tooth-shaped patterns constituting the above are changed, and the voltage corresponding to the linear displacement of the permanent magnet 22 is output. The output voltage from the magnetic detection element 23 is amplified and output to an external device (not shown) via the terminal 28 to detect the displacement of the detected device.

As shown in the waveform A of FIG. 6, the output voltage waveform has a linear output in a wider linear displacement range of the permanent magnet 22 than the sinusoidal output waveform C.
At this time, electromagnetic waves from the outside are shielded by the shield box 26 and the shield plate 26a which are provided so as to surround the ceramic substrate 24 on which the magnetic detection element 23 is mounted, so that the circuit element mounted on the ceramic substrate 24 malfunctions. Is prevented.

According to the first embodiment configured as described above,
A rod-shaped member facing the magnetic detection element 23 so that its major axis lies on an extension surface of the magnetic sensitive surface 23b of the magnetic detection element 23 using the magnetic resistance element 23a made of NiFe which is a ferromagnetic magnetic resistance material. Since the permanent magnet 22 is disposed, the effect that the linear displacement range in the long axis direction of the permanent magnet 22 where the output voltage of the magnetic detection element 23 becomes a linear output can be widened.

Example 2. The second embodiment is an embodiment of the linear displacement detecting device according to the second invention of the present invention. As shown in FIG. 7, the potential of the magnetic field generated by the rod-shaped permanent magnet 22 has a distribution having a strain 30 near the center of the permanent magnet 22. On the other hand, the magnetic field vector of the permanent magnet 22 flows from the N pole toward the S pole as shown in FIG. In the second embodiment, the magnetic detection element 23 is arranged in a region where the equipotential distribution line of the magnetic field of the permanent magnet 22 and the direction of the magnetic field vector match.

According to the second embodiment configured as described above,
The magnetic detection element 23 has a distortion 3 of the equipotential distribution of the magnetic field.
Since the magnetic field of the permanent magnet 22 that crosses the magnetically sensitive surface 23b of the magnetic detection element 23 coincides with the equipotential distribution line of the magnetic field and the magnetic field vector, the permanent magnet 22 is arranged outside the region of 0. The influence of the distortion 30 of the equipotential distribution of the magnetic field on the change in the resistance value of the magnetic resistance element 23a corresponding to the linear displacement is suppressed, the detection sensitivity of the magnetic detection element 23 is improved, and the output voltage of the magnetic detection element 23 is linear. The effect that the linear displacement range of the permanent magnet 22 as the output in the long axis direction can be made wider can be obtained.

Example 3. The third embodiment is an embodiment of the linear displacement detecting device according to the third invention of the present invention. FIG. 9 is an equipotential distribution diagram of a magnetic field in the linear displacement detecting device showing the third embodiment of the present invention. In the figure, 3
Reference numeral 1 denotes an iron piece that is a magnetic piece that is arranged on each of the magnetic pole surfaces at both ends of the permanent magnet 22 so that the ends thereof protrude toward the side surface of the permanent magnet 22. In the third embodiment, the permanent magnet 2
The iron pieces 31 are arranged on each of the magnetic pole surfaces at both ends of 2. Here, the equipotential distribution of the magnetic field generated by the permanent magnet 22 changes depending on the arrangement of the iron piece 31, as shown in FIG.
Is controlled by the amount of protrusion of the iron piece 31 to the side surface side of the permanent magnet 22.

According to the third embodiment configured as described above,
Since the iron pieces 31 are disposed on the magnetic pole surfaces at both ends of the permanent magnet 22, the amount of protrusion of the iron piece 31 toward the side surface of the permanent magnet 22 can be adjusted to shift the equipotential distribution of the magnetic field. It is possible to easily adjust the magnetic detection element 23 so that the magnetic detection element 23 and the detection element 23 have an appropriate positional relationship, that is, the magnetic field vector and the equipotential distribution line of the magnetic field match each other.

Example 4. The fourth embodiment is an embodiment of the linear displacement detecting device according to the fourth invention of the present invention. In the fourth embodiment, as shown in FIG.
The magnetoresistive pattern of the magnetoresistive element 23a is a pattern in which a comb-shaped pattern is symmetrically arranged in a V shape. Here, when the linear displacement in the long axis direction of the permanent magnet 22 is detected by the magnetic detection element 23, the output voltage waveform thereof is within a wider linear displacement range of the permanent magnet 22 than the output voltage waveform in the first embodiment. Linear output is obtained, and when the comb-teeth pattern forming the magnetoresistive pattern is formed with θ = 90 ° as shown by the waveform B in FIG. 6, the linear displacement range of the permanent magnet 22 where linear output is obtained is Particularly wide range of results were obtained.

According to the fourth embodiment thus constructed,
Since the magnetic resistance pattern of the magnetic resistance element 23a of the magnetic detection element 23 is a pattern in which the comb-teeth pattern is symmetrically formed in a V shape, the linear displacement range of the permanent magnet 22 that can obtain a linear output is wider. The effect that can be obtained is obtained.

Example 5. The fifth embodiment is an embodiment of the linear displacement detecting device according to the fifth invention of the present invention. Generally, the resistance change rate (△
R / R) has the characteristics shown in FIG. 11, and is extremely sensitive to the applied magnetic field in the region where the applied magnetic field is about 100 G or less. On the other hand, in the region of 100 G or more, the resistance change rate is almost saturated, and the resistance change rate can be changed only by changing the direction of the applied magnetic field. That is, the applied magnetic field 100
Below G, the resistance change rate changes in both the magnetic field strength and the magnetic field direction, making it unstable, and above 100 G of applied magnetic field, the resistance change rate changes only by the change in the magnetic field direction, and is stable.

By the way, in the linear displacement detection device described in the first embodiment, in order to stabilize its output, the place where the magnetic field applied to the magnetoresistive element becomes the weakest (the magnet middle point).
It is desirable to set the magnetic flux density at 100 G or more.

Since the magnitude of this magnetic flux density is greatly influenced by the distance between the magnetoresistive element and the permanent magnet as shown in FIG. 12 and the magnet diameter / magnet length (D / l) as shown in FIG. It is necessary to shorten the distance between the magnetoresistive element and the permanent magnet and set the magnet diameter / magnet length (D / l) to a certain value or more. By doing so, the output of the linear displacement detection device described in the first embodiment is stabilized. Note that the configuration in which the applied magnetic field is 100 G or more can be configured by strengthening the magnetic force of the permanent magnet in addition to the above.

Example 6. The sixth embodiment is an embodiment of the linear displacement detecting device according to the sixth invention of the present invention. In the linear displacement detection device described in the first embodiment, in order to improve the linearity of the analog output voltage, that is, to suppress the undulation when compared with an ideal gradient straight line, the change in magnetic flux per unit stroke of the permanent magnet is changed. Magnet diameter / magnet length (D / l) ratio and magnetoresistive element to be 6 ± 3 deg / mm
It is desirable to set the distance between permanent magnets. 6 ± 3deg
/ Mm means that the angle change of the magnetic flux is 6 ° when the permanent magnet moves 1 mm.
This means ± 3 °.

The change in the magnetic flux angle with respect to the magnet diameter / magnet length (D / l) has the relationship shown in FIG. 14, and when the distance between the magnetoresistive element and the permanent magnet is increased (D /
l) becomes larger and smaller (D / l) has the same effect. By doing so, the linearity of the analog output voltage of the linear displacement detection device described in the first embodiment is ensured. Here, there is a very close relationship between the contents of the sixth embodiment and the contents of the fifth embodiment, and the magnet diameter / magnet length (D / l) and the magnetoresistive element to the permanent magnet are satisfied so as to satisfy both. It is necessary to set the distance and.

Example 7. The seventh embodiment is an embodiment of the linear displacement detecting device according to the seventh invention of the present invention. Embodiment 7 FIG. 15 is a sectional view of a linear displacement detector showing Embodiment 7 of the invention. In the figure, 32 is a case body in which the fixing / accommodating space 32A of the circuit board 24 and the operating space 32B of the shaft 21 are completely separated by a mold wall 32a, and the case 20 and the connector assembly 25 of the first embodiment are separated from each other. It is constructed as an aggregate. Reference numeral 33 is a cover A for hermetically sealing the space 32A of the case body 32, and the circuit board 24 having the magnetic detection element 23 is provided with the space 32A
After being stored and fixed in the case, it is fixed to the case body 32 by adhesion. Reference numeral 34 covers the space 32B of the case body 32 and the shaft 2
The cover B having one through hole 34a is adhered to the case body 32 to prevent the shaft 21 from falling off.

As described above, when the fixing / accommodating space 32A of the circuit board 24 is completely separated from the operating space 32B of the shaft 21 by the mold wall 32a, the space 32B is formed along the shaft 21 from the through hole 34a of the cover B34. Water, oil, etc. that enter the space 3
2B and pressure fluctuations generated in the operating space 32B reach the space 32B, so that the circuit board 24 of the fixing / accommodating space 32A is not particularly affected and the airtightness of the product is ensured. To be done.

Example 8. The eighth embodiment is an embodiment of the linear displacement detecting device according to the eighth invention of the present invention. 16 is a sectional view showing a state in which the linear displacement detection device according to the eighth invention of the present invention is mounted on an EGR valve, FIG. 17 is a sectional view taken along line XVII-XVII of FIG. 16, and FIG. FIG. 19 is a diagram for explaining the principle, and FIG. 19 is a diagram showing a variation state of the output voltage in FIG. In the figure, those parts which are the same as or correspond to those of the seventh embodiment are designated by the same reference numerals, and description thereof will be omitted.

In the figure, 35 is a mounting flange formed on the case body 32, and 36 is an insertion cylinder portion formed on the case body 32 so as to project from the mounting flange 35. The permanent magnet 22 moves on the center line 37. Shaft 21
Is installed. Reference numeral 38 denotes an EGR valve which is a device to be detected, and has an attachment flange 38a and an opening 38b made of a ferromagnetic material such as iron for attaching the device. Three
Negative pressure chamber 9 is connected to the negative pressure generated in the engine (not shown). Reference numeral 40 denotes a rod, which is operated according to the negative pressure in the negative pressure chamber 39 to open and close the valve 41.

As described above, the insertion tube portion 36 is inserted into the opening portion 38b.
When the present apparatus is mounted on the EGR valve 38 by inserting the mounting flanges 35 and 38a into the mounting flange 38a and the center of the mounting flange 38a and the center line 37 of the opening 38b, as shown in FIGS. Because it will be displaced linearly,
The influence of the mounting flange 38a of the ferromagnetic material (iron or the like) is minimized, and the output fluctuation can be suppressed to the minimum.

In FIG. 18, the distance z between the permanent magnet 22 and the mounting flange 38a is increased, and the opening 38b
Although it is effective in suppressing the output fluctuation by increasing the diameter y, there is a limit to downsizing. FIG. 19 shows an example of the output waveform when z = 0 and y = constant. When the permanent magnet 22 is eccentric with respect to the center line 37 of the opening 38b (a), the output fluctuation becomes large, and when it is on the center line 37 (b), the output fluctuation is largely suppressed. I understand.

In this device, the linear displacement of the rod 40, which is attached to the EGR valve 38 and linearly displaced according to the negative pressure in the negative pressure chamber 39, is taken out by the shaft 21, and the permanent magnet 22 is removed. By linearly displacing with respect to the magnetic detection element 23, the direction of the applied magnetic field changes, and by obtaining an analog output, it is used as an opening sensor of the EGR valve 38.

Example 9. The ninth embodiment is an embodiment of the linear displacement detecting device according to the ninth invention of the present invention. Since the linear displacement detectors of the above-described first to eighth embodiments use the permanent magnet 22, the influence of the external magnetic field and the ferromagnetic material (for example, the mounting flange 38a of the EGR valve 38 of the eighth embodiment) is completely eliminated. Therefore, a magnetic shield made of a ferromagnetic material is required.

In particular, according to this linear displacement detecting device, as shown in FIG. 20, by disposing the magnetic shield 42 which is a cylindrical ferromagnetic body with the rod-shaped permanent magnet 22 as the center, the magnetic shield 42 is eliminated. The difference between the output voltage when the magnetic shield 42 is present and the output voltage when the magnetic shield 42 is present can be minimized, and the output fluctuation due to the external ferromagnetic material and the external magnetic field can be almost completely eliminated.

Example 10. The tenth embodiment is an embodiment of the linear displacement detecting device according to the tenth invention of the present invention. Since the structure of the tenth embodiment is the same as that of the first embodiment shown in FIGS. 1 to 4, the same reference numerals are used and the description thereof is omitted.

That is, according to the tenth embodiment, the case 2
Since the connector assembly 25 is inserted into and fixed to the opening 0b of 0 to seal the opening 20b, the case body of the linear displacement detection device is configured.
It is easy to attach the parts such as 4 and the workability of assembling is improved.

Example 11. The eleventh embodiment is an embodiment of the linear displacement detecting device according to the eleventh invention of the present invention. Since the structure of the eleventh embodiment is the same as that of the first embodiment shown in FIGS. 1 to 4, the same reference numerals are used and the description thereof is omitted.

That is, according to the eleventh embodiment, since the connector assembly 25 is provided with the guide portion 25a for slidingly guiding the shaft 21 integrally formed with the permanent magnet 22,
By simply incorporating the shaft 21 in the guide portion 25a without fitting and fixing the connector assembly 25 in the case 20, the displacement of the shaft 21 can be realized as it is, and the circuit can be trimmed with high accuracy according to the actual use state. The effect is obtained.

In the eleventh embodiment, the guide portion 25
Although a is made of the same material as the connector assembly 25, the guide portion 25a may be made of a copper or iron bearing material and integrated when the connector assembly 25 is molded. Has the same effect.

Example 12 The twelfth embodiment is an embodiment of the linear displacement detecting device according to the twelfth invention of the present invention. The structure of the twelfth embodiment is the same as that of the first embodiment shown in FIGS.

That is, according to the twelfth embodiment, since the shield box 26 is integrally formed with the connector assembly 25, there is no need to fix the shield box 26 with a screw or an adhesive, and the assemblability is improved and The shield box 26 is built in the case 20 and is not exposed to the outside, and the appearance is improved.

[0065]

Since the present invention is configured as described above, it has the following effects. According to the first aspect of the present invention, a magnetic detection element having a magnetic sensitive surface formed of a ferromagnetic magnetoresistive element formed in a predetermined pattern, and a long axis center on an extension surface of the magnetic sensitive surface. As described above, since the rod-shaped permanent magnet is provided so as to face the magnetic detection element and be movable in the long axis direction and have both end faces as magnetic pole surfaces, a wide straight line in the long axis direction of the permanent magnet. A linear output can be obtained in the displacement range.

According to the second aspect of the present invention, the permanent magnet is arranged so that the magnetic detecting element is located in a region where the magnetic field equipotential distribution line of the permanent magnet and the direction of the magnetic field vector coincide with each other. Therefore, the detection sensitivity of the magnetic detection element is improved, and the linear displacement range in the long axis direction of the permanent magnet that can obtain a linear output can be made wider.

Furthermore, according to the third aspect of the present invention,
Since the magnetic piece is disposed on the magnetic pole surface of the permanent magnet, the permanent magnet and the magnetic detection element can be easily adjusted to have an appropriate positional relationship.

Further, according to the fourth aspect of the present invention, since the ferromagnetic magnetoresistive element is formed in a pattern in which the comb-teeth pattern is symmetrically arranged in a V shape, magnetic detection is performed. The detection sensitivity of the element is improved, and the linear displacement range of the permanent magnet that can obtain a linear output in the long axis direction can be made wider.

Furthermore, according to the fifth aspect of the present invention,
Since the shape of the permanent magnet and the distance between the permanent magnet and the magnetoresistive element are set, stable output can be obtained. Also,
According to the sixth aspect of the present invention, since the shape of the permanent magnet and the distance between the permanent magnet and the magnetoresistive element are set,
A stable linear output can be obtained.

Furthermore, according to the seventh aspect of the present invention,
Since the fixing / accommodating area of the circuit board and the operating area of the shaft are completely separated, airtightness can be secured. According to the eighth aspect of the present invention, since the permanent magnet is configured to be movable on the central axis of the opening of the device to be detected, the output fluctuation due to the influence of the ferromagnetic material opening of the device to be detected is suppressed. Can be suppressed.

Further, according to the ninth invention of the present invention,
Since the magnetic shield, which is a symmetric ferromagnetic material, is installed at a predetermined distance from the permanent magnet as the central axis, the output fluctuation due to the external ferromagnetic material and the external magnetic field can be suppressed almost completely. According to the tenth aspect of the present invention,
Since the connector assembly is fitted and fixed in the opening of the case to seal the opening, the assembly workability can be improved.

Further, according to the eleventh aspect of the present invention, since the connector assembly is provided with the guide portion for guiding and moving the permanent magnet in the major axis direction thereof, the connector assembly is simply fitted into the case without being fixed. By incorporating the shaft in the guide part, the displacement of the shaft can be realized as it is, and the trimming of the circuit can be performed with high accuracy according to the actual use condition. According to the twelfth aspect of the present invention, since the shield box that shields electromagnetic waves is integrally formed with the connector assembly, there is no need to hold the shield box with screws, adhesives, etc., and assembly workability is improved. it can.

[Brief description of drawings]

FIG. 1 is a front view of a linear displacement detection device showing a first embodiment of the present invention.

2 is a cross-sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

4 is an exploded perspective view of FIG. 1. FIG.

5 is a plan view showing an example of a magnetoresistive pattern of the magnetic detection element in FIG. 1. FIG.

FIG. 6 is a graph showing the relationship between the linear displacement of the permanent magnet and the output voltage in Example 1 of the present invention.

FIG. 7 is an equipotential distribution diagram of a magnetic field in the linear displacement detection device showing the second embodiment of the present invention.

FIG. 8 is a state diagram of magnetic field vectors in FIG.

FIG. 9 is an equipotential distribution diagram of a magnetic field in the linear displacement detection device showing the third embodiment of the present invention.

FIG. 10 is a plan view of an example of a magnetoresistive pattern of a magnetic detecting element in a linear displacement detecting device showing Example 4 of the invention.

FIG. 11 is a diagram of applied magnetic field characteristics of a magnetoresistive element in a linear displacement detection device showing Embodiment 5 of the invention.

12 is a diagram showing the magnitude of magnetic flux density with respect to the stroke position in FIG.

FIG. 13: Magnet diameter / magnet length (D / l) in FIG.
It is a figure which shows the magnitude | size of the magnetic flux density with respect to.

FIG. 14 is a diagram showing changes in magnetic flux angle with respect to magnet diameter / magnet length (D / l) in the linear displacement detection device showing the sixth embodiment of the present invention.

FIG. 15 is a sectional view of a linear displacement detection device showing a seventh embodiment of the present invention.

FIG. 16 is a sectional view of a linear displacement detecting device showing an eighth embodiment of the present invention.

17 is a cross-sectional view taken along the line XVII-XVII of FIG.

FIG. 18 is a diagram for explaining the principle of Embodiment 8 of the present invention.

19 is a diagram showing a variation state of the output voltage in FIG.

FIG. 20 is a schematic diagram of a linear displacement detection device showing a ninth embodiment of the present invention.

FIG. 21 is a vertical sectional view showing a conventional linear displacement detection device.

22 is a cross-sectional view corresponding to FIG.

23 is a plan view showing the arrangement of permanent magnets in FIG. 21. FIG.

24A and 24B are plan views for explaining the operation of the linear displacement detection device in FIG. 21, respectively.

[Explanation of symbols]

 20 Case 20b Opening 21 Shaft 22 Permanent Magnet 23 Magnetic Detecting Element 23a Magnetic Resistance Element 23b Magnetic Sensitive Surface 24 Ceramic Substrate 25 Connector Assembly 25a Guide Part 26 Shield Box 31 Iron Piece 32 Case Body 32A Fixing / Storing Space 32B Operating Space 32a Mold Wall 38 EGR valve 38a Mounting flange 38b Opening 39 Negative pressure chamber 40 Rod 42 Magnetic shield

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Yokotani 6 Sadamoto-cho, Himeji City Mitsubishi Electric Engineer Ring Co., Ltd. Himeji Plant

Claims (12)

[Claims] 1. A magnetic detection element having a magnetically sensitive surface formed of a ferromagnetic magnetoresistive element formed in a predetermined pattern, and the magnetic detection element such that a major axis lies on an extension surface of the magnetically sensitive surface. And a rod-shaped permanent magnet that is disposed so as to be movable in the long axis direction and has both end faces as magnetic pole surfaces, and that displaces the permanent magnet in the long axis direction in parallel with the magnetic sensitive surface. A linear displacement detection device characterized by detecting as a change in the direction of a magnetic flux that crosses. 2. The linear displacement according to claim 1, wherein the permanent magnet is arranged such that the magnetic detection element is located in a region where the equipotential distribution line of the magnetic field of the permanent magnet and the direction of the magnetic field vector coincide with each other. Detection device. 3. The linear displacement detecting device according to claim 1, wherein a magnetic piece is arranged on the magnetic pole surface of the permanent magnet. 4. The linear displacement detection device according to claim 1, wherein the ferromagnetic magnetoresistive element is formed in a pattern in which a comb-shaped pattern is symmetrically arranged in a V shape. 5. The straight line according to claim 1, wherein the shape of the permanent magnet and the distance between the permanent magnet and the magnetoresistive element are set so that a saturation magnetic field is always applied to the ferromagnetic magnetoresistive element. Displacement detection device. 6. The shape of the permanent magnet and the permanent magnet so that the change of the magnetic flux angle across the magnetic sensitive surface of the ferromagnetic magnetoresistive element in parallel is 6 ± 3 deg / mm with respect to the displacement of the permanent magnet in the long axis direction. The linear displacement detection device according to claim 1, wherein a distance between the magnet and the magnetoresistive element is set. 7. A circuit board on which a ferromagnetic magnetoresistive element is mounted and a fixed / accommodating area thereof are completely separated from an operating area of a shaft including a permanent magnet for detecting linear displacement.
The linear displacement detection device according to claim 1, wherein a case body of the product is configured. 8. The product is configured so that, when the linear displacement detection device according to claim 1 is mounted in a ferromagnetic material opening of a device to be detected, the permanent magnet is displaced on the central axis of the opening. A linear displacement detection device. 9. The linear displacement detection device according to claim 1, wherein a magnetic shield, which is a symmetrical ferromagnetic body, is installed at a predetermined distance from the permanent magnet as a central axis. . 10. A case having an opening, a magnetic detection element having a magnetically sensitive surface formed of a ferromagnetic magnetoresistive element formed in a predetermined pattern, and the magnetic detection element is mounted and housed in the case. Circuit board, a rod-shaped permanent magnet disposed in the case so as to be movable in the long axis direction, and a connector assembly for mounting the circuit board. The case is fitted with the connector assembly. A linear displacement detection device, characterized in that it is fixed to seal the opening. 11. The linear displacement detection device according to claim 10, wherein a guide portion for guiding and moving the permanent magnet in the major axis direction is formed in the connector assembly. 12. The linear displacement detection device according to claim 10, wherein a shield box for shielding electromagnetic waves is integrally formed with the connector assembly.