JPH0131125B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position detection mechanism used to measure a moving position in a linear motion or an angular position in a rotational motion, and in particular a position detection mechanism using two magnetic sensing elements. The present invention relates to a position detection mechanism that can perform a plurality of position detection judgments.

[Conventional technology]

It is necessary to detect the movement position and angular position of linear motion elements such as machine tools and rotational motion elements such as the crankshaft of internal combustion engines. For this reason,
2. Description of the Related Art Mechanisms (sensors) that detect moving positions and angular positions using magnetism have been used in the past, and these have a structure that combines a magnetic material and a magnetic sensing element such as a Hall element.

An example of a conventional position detection mechanism is shown in FIG.
Proposals similar to the structure shown in FIG. 1 include, for example, Japanese Patent Application No. 137222/1988, which the applicant previously filed, and Japanese Utility Model Application No. 51797/1983 as prior art;
There is Utility Model Publication No. 55-51798.

In this configuration, cube-shaped blocks 2 are protruded from the upper surface of the detection body 1 at regular intervals, and above the blocks 2, a U-shaped magnet 3 has both end faces facing the block 2. . This magnet 3
A magnetically sensitive element 4 is fixed to the N end face of the block 2, and the S end face and the magnetically sensitive element 4 are spaced apart from the top surface of the block 2 by a clearance D. In this configuration, when the detection object 1 moves in a linear direction, each block 2 crosses the magnetic flux of the magnet 3 every time it passes the end face of the magnet 3, causing a change in the density of the magnetic flux passing through the magnetic sensing element 4. The magnetic sensing element 4 converts this change in magnetic flux density into a change in current, thereby making it possible to detect the position of the block 2, that is, the moving position of the detection object 1.

In addition, as a detection mechanism combining a Hall element or a detection coil with a magnet, Japanese Patent Application Laid-Open No. 52-65806,
There is Japanese Unexamined Patent Publication No. 159371/1983.

[Problem to be solved by the invention]

However, even if the magnetic force of the magnet 3 is constant, the level of magnetic flux density detected by the magnetically sensitive element 4 changes depending on the interval of the clearance D. The processing accuracy must be increased so that the distance between the magnetic sensing element 4 and the detection object 1 does not change. Also, in general,
Since the sensitivity of the magnetic sensing element 4 has a characteristic that varies greatly depending on its temperature, its output level will vary depending on the ambient temperature of the detection mechanism.
FIG. 2 shows how the detection level of the magnetic sensing element 4 fluctuates due to changes in the clearance D and temperature. In this way, the magnetic sensing element 4
Since the detection level varies, the slice level setting value that serves as the criterion for discrimination must be set only within the narrow range shown by l in the figure, and if the slice level is set incorrectly, proper level judgment will not be possible. It is what it is. For this reason, detection was sometimes impossible under detection conditions that caused large temperature changes or clearance changes. Furthermore, in position detection, it is necessary to detect a relative position and a reference position, but in the conventional configuration, the position of block 2 can only be detected as an electrical signal, and multiple detection signals cannot be output. It was hot.

In view of the above-mentioned drawbacks, the present invention provides position detection in which a plurality of magnetic sensing elements are arranged with their magnetic sensing directions different from each other, and a plurality of position judgments can be made by combining the directions of magnetic flux passing through the magnetic sensing elements. It provides a mechanism.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a position detecting mechanism comprising a magnetic detecting section combining a magnet and a magnetic sensing element, and a detecting body fixed to a block made of a soft magnetic material. The part is formed into an E-shape consisting of three protrusions, and one protrusion on both sides of the three protrusions has an S pole and the other protrusion has an N pole, and the central protrusion of the three protrusions has an S pole and an N pole. A first magnetic sensing element is disposed at the tip of the surface facing the detection object, and the first magnetic sensing element is disposed on the side surface of the central protrusion or between the central protrusion and either of the protrusions on both sides. A second magnetic sensing element having a magnetic sensing direction different from that of the magnetic sensing element is disposed, and the blocks fixed to the detection body are arranged at predetermined intervals orthogonal to the moving direction of the detection body. The block is composed of a first block equal to the width of the detection object, and second and third blocks shorter than the width of the detection object and longer than half the width of the detection object, and one end of the second block is fixed to one side of the detection body, the other end of the third block is located on the other side of the detection body, the first magnetic sensing element and the second magnetic sensing element of the magnetic detection section; Based on the respective positional relationships of the detection object with the first block, second block, and third block,
The position of the detection object is determined based on whether the magnetic flux passes through the first magnetic sensing element and the second magnetic sensing element.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 schematically shows the position detection mechanism of the present invention.
1 and a magnetic detection section 12.
The detection body 11 is made of a soft magnetic material such as iron or silicon steel, and a plurality of first blocks 13 and second blocks of different shapes made of the same material are formed on the top surface of the detection body 11. Block 14, third block 1
5 are arranged and fixed in order at intervals. The widths a, c, and e of each of the first, second, and third blocks 13, 14, and 15 are the same, respectively, and each of the first, second, and third blocks 13, 14, and 15 has the same width. They are arranged at intervals b, d, and f that are the same as their widths a, c, and e. Further, the length h of the first block 13 is the same as the width g of the detection object 11, but the lengths i and j of the second and third blocks 14 and 15 are the same as the width g of the detection object 11.
Each of the first, second, and third blocks 13, 14, and 15 is arranged with its axis perpendicular to the moving direction of the detection body 11, They are positioned so that they are parallel to each other. The first block 13 is the detection object 1.
1, one end of the second block 14 is located on one side of the detection object 11, and one end of the third block 15 is located on one side of the detection object 11.
It is located on the other side, so that the first
The second and third blocks 13, 14, 15 are arranged like stepping stones.

Next, the magnetic detection unit 12 includes a magnet 16 made of a hard magnetic material such as alnico or rare earth, two first magnetic sensing elements 17 such as a Hall element, a Hall IC, a magnetoresistive element, and a second magnetic sensing element. It is composed of elements 18. The magnet 16 has an E-shaped side surface, and has an N pole and an S pole at both ends of the E shape.
It is magnetized to have polarity. and,
A first magnetically sensitive element 17 and a second magnetically sensitive element 18 are fixed to the center tip and side surfaces of the E-shape, and the magnet 1
The N pole, S pole of No. 6, and each tip of the first magnetic sensing element 17 are formed to be on the same plane. This magnet 16
The length of the magnet 16 is approximately the same as or larger than the width of the detection body 11, and its N and S poles are located on the sides of the detection body 11.
The axis of the detector is positioned perpendicular to the direction of movement of the detection object 11, and the tips of the N and S poles are spaced a little apart from the upper surfaces of the first, second, and third blocks 13, 14, and 15, respectively. There is. FIG. 4 shows this magnetic detection section 12 viewed from the side.
In this case, the magnetically sensitive directions S and T of the two first magnetically sensitive elements 17 and the second magnetically sensitive element 18 are arranged such that their axes are perpendicular to each other.

Next, FIG. 5 shows a processing circuit for signals from the first magnetically sensitive element 17 and the second magnetically sensitive element 18 in this embodiment. A control current is applied to the first magneto-sensitive element 17, and a pair of electrodes provided perpendicularly to the direction to which this direct current is applied are connected to resistors 20 and 2, respectively.
1 to a differential amplifier 22. A grounded resistor 23 is connected to the positive input terminal of the differential amplifier 22, and a resistor 24 is interposed between the negative input terminal and the output of the differential amplifier 22. is connected to two comparators 25 and 26. The comparators 25 and 26 have resistors 27 and 2.
A reference voltage from a voltage divider circuit consisting of 8 and 29 is applied, and the outputs X and Y of comparators 25 and 26 serve as detection signals, and each of them is connected to a NOR gate 30.
is being entered. Further, a control current is applied to the magneto-sensitive element 18, and a differential amplifier 33 is connected to a pair of electrodes provided in a direction perpendicular to the direction to which this direct current is applied, via resistors 31 and 32. A grounded resistor 34 is connected to the positive input terminal of the differential amplifier 33, and a resistor 35 is interposed between the output of the differential amplifier 33 and the negative input terminal. The output of the differential amplifier 33 is connected to the negative input of a comparator 36, and a voltage divided by resistors 37 and 38 is applied to the positive input of the comparator 36. The output of this comparator 36 is input to the NOR gate 30,
The output Z of the NOR gate 30 becomes an output signal.

Next, the operation of this embodiment will be explained.

In FIG. 3, the magnetic detection unit 12 is held at a distance from the detection body 11 by means not shown, and the detection body 11 can freely move in the straight direction indicated by the arrow in the figure, and the magnet 16 N poles,
The S pole and the first magnetic sensing element 17 alternately approach and separate from the first, second and third blocks 13, 14 and 15, respectively. The approach of the N pole, S pole, and first magnetic sensing element 17 is such that in the first block 13, the N pole, S pole, and the first magnetic sensing element 17 all approach each other, and in the second block 14, the N pole, the S pole, and the first magnetic sensing element 17 all approach each other. , the S pole and the first
In the third block 15, the N pole and the first magnetic sensing element 17 approach each other. This first, second and third block 1
Since 3, 14, and 15 are formed of a soft magnetic material, the direction in which the magnetic flux flows can be switched. FIG. 6 shows changes in the flow of magnetic flux. In FIG.
14 and 15, and the magnetic flux is N
The magnetic flux flows from the pole to the S pole and does not penetrate the first magnetically sensitive element 17 , but some of the leaked magnetic flux passes through the second magnetically sensitive element 18 . In Figure 6 B, S
The second block 14 is close to the pole and the first magnetically sensitive element 17, and the magnetic flux that has passed through the first magnetically sensitive element 17 passes through the second block 14 and is absorbed by the S pole. Therefore, the magnetic flux does not pass through the second magnetically sensitive element 18. FIG. 6C shows a state in which the third block 15 approaches the N pole and the first magnetic sensing element 17, and the magnetic flux passes from the N pole through the third block 15 and penetrates the first magnetic sensing element 17. Therefore, the magnetic flux does not pass through the second magnetically sensitive element 18. Also,
In FIG. 6D, the first block 13 is close to the N pole, the S pole, and the first magnetic sensing element 17, and the magnetic flux passes through the first block 13 from the N pole and is absorbed by the S pole. Therefore, magnetic flux does not penetrate through the first magnetically sensitive element 17 and the second magnetically sensitive element 18. The fluctuations in the magnetic flux penetrating the first magnetic sensing element 17 and the second magnetic sensing element 18 in the four states of FIG. 6 are shown in the upper row of FIG. 1 indicates the case where the magnetic flux penetrates, and the symbol indicates the case where the magnetic flux penetrates in the forward direction and the reverse direction. Then, the output signal X due to the magnetic flux passing through the first magnetically sensitive element 17 and the second magnetically sensitive element 18,
Changes in Y and Z are shown in the middle lower part of FIG. 7, and are electrically output as high level H and low level L signals. The position of the detection object 11 can be determined by the combination of the output signals X, Y, and Z.
For example, the first block 13 can be used as a reference position to determine the relative position, and the second and third blocks 14 and 15 can be used to determine the relative position.

FIG. 8 shows a modification of the configuration of the magnetic detection section 12. In A in the figure, the second magnetic sensing element 18 is connected to the magnet 1.
It is fixed to the N-pole side side of 6.
The magnetically sensitive element 18 is located between the north end and the center protrusion, and the second magnetically sensitive element 18 in C in the figure is fixed to the S pole side side of the center protrusion, and in D in the figure The second magnetic sensing element 18 is located between the south pole and the central protrusion, and in the figure (E), the second magnetic sensing element 18 is fixed to the side surface of the south pole.

〔Effect of the invention〕

Since the present invention is configured as described above, the variation in the direction of magnetic flux can be detected by two magnetic sensing elements, and the position of the detected object can be determined by a combination of the detection outputs. It is possible to distinguish and detect more than one position, for example, a reference position, a relative position, etc.

In addition, since the position of the sensing object is detected based on whether or not the magnetic flux passes through the magnetic sensing element, it is not affected by clearance errors between the magnetic sensing part and the sensing object, changes in characteristics due to temperature of the magnetic sensing element, etc. ,
Accurate discrimination can be made.

[Brief explanation of drawings]

Fig. 1 is a principle diagram showing a conventional position detection mechanism, Fig. 2 is a graph showing changes in its magnetically sensitive output, Fig. 3 is a perspective view showing an embodiment of the present invention, and Fig. 4 is a magnetic A side view showing the detection unit, Fig. 5 is a signal processing circuit similar to the above, Fig. 6 is an explanatory diagram showing changes in magnetic flux, and Fig. 7 is a truth diagram showing changes in magnetic flux penetrating the magnetic sensing element and changes in the output signal. The table and FIG. 8 are plan views showing other embodiments of the magnetic detection section. 11... Detection object, 12... Magnetic detection section, 13,
14, 15...Block, 16...Magnet, 17...
...first magnetically sensitive element, 18...second magnetically sensitive element.

Claims (1)

[Claims] 1. A magnetic detection unit that combines a magnet and a magnetic sensing element;
In a position detection mechanism consisting of a detection body fixed to a block made of a soft magnetic material, the magnetic detection part has an E-shaped shape consisting of three protrusions, and one protrusion on both sides of the three protrusions. An S pole is placed on one protrusion and a N pole is placed on the other protrusion, and a first magneto-sensitive element is placed on the tip of the surface facing the detection body of the central protrusion of the three protrusions. side or
A second magnetically sensitive element having a magnetic sensing direction different from that of the first magnetically sensitive element is disposed between the central protrusion and either of the protrusions on both sides, and The fixed blocks are arranged at predetermined intervals orthogonal to the moving direction of the detecting body, and the blocks are arranged in a first block having a width equal to the width of the detecting body.
and second and third blocks shorter than the width of the detecting body and longer than half the width of the detecting body, one end of the second block being fixed to one side of the detecting body, and the third block being fixed to one side of the detecting body. The other end is located on the other side of the detecting body, and the first magnetically sensitive element and the second magnetically sensitive element of the magnetic detection section, the first block, and the second magnetically sensitive element of the detecting body are connected to each other.
Based on the respective positional relationships with the first magnetic sensing element and the third block, the magnetic flux is
A position detection mechanism characterized in that the position of the detection object is determined based on whether or not it passes through a second magnetic sensing element.