JP2003207366A - Rotation angle sensor - Google Patents

Abstract

(57) [Problem] To provide a rotation angle sensor that achieves both high performance and low cost, and that reliably switches an angle conversion map. SOLUTION: A magnetic circuit component for generating a magnetic field, and a magnetic flux density detecting unit that relatively rotates in the magnetic field, wherein the magnetic flux density detecting unit is arranged on a rotation center line of the orthogonal magnetic circuit component, An angle conversion map constituted by a second Hall element, in which the rotation angle of the magnetic flux density detector with respect to the magnetic circuit component is set based on the output A of the first Hall element 7, and the output B of the second Hall element An angle conversion map that sets the rotation angle of the magnetic flux density detection unit with respect to the magnetic circuit component based on the magnetic circuit by switching between the angle conversion maps according to the outputs A and B of the first and second Hall elements. In the rotation angle sensor configured to calculate the rotation angle of the magnetic flux density detection unit with respect to the component, each angle conversion map is set so that the range of the rotation angle to be converted overlaps with each other. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved rotation angle sensor.

[0002]

2. Description of the Related Art Conventionally, in order to detect a rotation angle with high accuracy, a resolver type rotation angle sensor using a coil has been generally used. This resolver type rotation angle sensor can endure a surrounding environment where vibration and temperature change greatly and can obtain high detection accuracy, but has a problem that the product cost is high.

As a countermeasure against this, the applicant of the present invention has filed a patent application 20
There is one already filed as 01-127221. This rotation angle sensor includes a case and a rotation shaft that rotate relative to each other, and the first and second Hall elements are fixed to the case as a magnetic flux density detection unit, while a permanent magnet is fixed to the rotation shaft as a magnetic circuit configuration unit. It is something.

This rotation angle sensor uses the hall element to reduce the cost of the product, and
By switching the angle conversion maps according to the outputs of the first and second Hall elements, a high sensor output resolution can be obtained over the entire rotation angle range, and the detection accuracy can be improved.

However, when noise or the like from the surrounding environment is superimposed on the sensor signal, it becomes impossible to switch the angle conversion map, and there is a possibility that a discontinuous portion occurs in the rotation angle information.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a rotation angle sensor that achieves both high performance and low cost, and that can reliably switch the angle conversion map. And

[0007]

A first aspect of the present invention includes a magnetic circuit component that creates a magnetic field and a magnetic flux density detector that relatively rotates in the magnetic field, and a magnetic circuit that intersects the magnetic flux density detector. The first and second Hall elements are arranged on the rotation center line of the component, and the output A of the first Hall element is
An angle conversion map in which the rotation angle of the magnetic flux density detection unit with respect to the magnetic circuit configuration unit is set based on the above, and an angle in which the rotation angle of the magnetic flux density detection unit with respect to the magnetic circuit configuration unit is set based on the output B of the second Hall element. And a conversion map
The angle conversion maps are converted in the rotation angle sensor configured to switch the angle conversion maps according to the outputs A and B of the first and second Hall elements to obtain the rotation angle of the magnetic flux density detection unit with respect to the magnetic circuit configuration unit. It is characterized in that the ranges of rotation angles to be set are set so as to overlap each other.

A second aspect of the invention is characterized in that, in the first aspect, one of the outputs of the first and second Hall elements, which has a larger output change with respect to the rotation angle, is used as a signal for detecting the rotation angle. I decided to do it.

In a third aspect of the present invention, in the first or second aspect of the invention, one of the outputs of the first and second Hall elements, which has a smaller voltage change with respect to the rotation angle, is used to determine the rotation angle region. It was characterized by.

[0010]

According to the first aspect of the present invention, it is possible to avoid that the maps cannot be switched due to noise or the like because the ranges of the rotation angles converted from the angle conversion maps overlap each other. The angle conversion maps can be reliably switched, and it is possible to prevent the occurrence of discontinuous portions in the rotation angle information.

Further, the cost of the product can be reduced by using the Hall element as the magnetic flux density detecting section.

According to the second invention, by detecting the rotation angle by using one of the outputs of the first and second Hall elements, which has a steeper slope, a high sensor output resolution can be obtained over a wide rotation angle range. Therefore, the detection accuracy can be improved.

According to the third aspect of the invention, one of the outputs of the first and second Hall elements, which has a gentle gradient, is used to determine the rotation angle region, and the rotation angle is determined based on the other output of the steep gradient. Can be specified.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, FIG. 1 shows an example of a rotation angle sensor to which the present invention is applied. The rotation angle sensor 1 includes a case and a rotation shaft that rotate relative to each other.
While the second Hall elements 7 and 8 are fixed, the ring magnet 3 is concentrically fixed in the middle of the rotating shaft.

The ring magnet 3 provided as a magnetic circuit component is made of a permanent magnet, and a pair of N and S poles are formed on the rotation center line with the rotation center O sandwiched therebetween by parallel magnetization.

The first and second Hall elements 7 and 8 provided as the magnetic flux density detector output a voltage corresponding to the magnetic flux density, which changes with the relative rotation of the ring magnet 3, as a signal through an electric wire. .

The first and second Hall elements 7 and 8 are arranged on the center lines of the rotation axes orthogonal to each other. That is, the first and second Hall elements 7 and 8 are provided orthogonal to each other.

In the present embodiment, the ring magnet 3 in which the first and second Hall elements 7 and 8 are provided as a magnetic circuit constituent portion.
It is located outside the rotation path of.

FIG. 2 shows how the voltages output from the first and second Hall elements 7 and 8 change according to the rotation angle. Outputs A of the first and second Hall elements 7 and 8,
B has a value corresponding to a sine wave having a phase difference of 90 degrees.

The controller 5 inputs outputs A and B of the first and second Hall elements 7 and 8, and outputs the outputs A and B based on four preset angle conversion maps shown in FIG. The rotation angle is calculated and the calculated rotation angle is output.

The angle conversion maps 1 to 3 are set as shown in FIG. In FIG. 3, the index (map array number) provided on the vertical axis is the A / D of the sensor output.
The conversion value, the horizontal axis is the rotation angle information obtained by converting the map value corresponding to the index, and the line is the line connecting the map values.

The index of the angle conversion map is taken as the output A of the first Hall element 7, and the index of the angle conversion map is taken as the output B of the second Hall element 8. The angle conversion map is provided in the area where the output A of the first hall element 7 rises. The angle conversion map is provided in the area where the output B of the second hall element 8 drops. The angle conversion map is provided in the area where the output A of the first hall element 7 drops. The angle conversion map is provided in the area where the output B of the second hall element 8 rises.

As a result, when the rotation axis of the rotation angle sensor 1 makes one rotation, the angle conversion map is switched in this order, and the outputs A, A of the first and second Hall elements 7, 8 are changed.
B is taken out so that regions having a large gradient are alternately switched. That is, of the outputs A and B of the first and second Hall elements 7 and 8, one having a larger voltage change with respect to the rotation angle is used as the signal for detecting the rotation angle.

By the way, in an actual machine, noise or the like from the surrounding environment may be superimposed on the sensor signal, and as a countermeasure against this, a filter or the like for removing the noise is provided on the hardware side or the software side. However, even if such measures are taken, the noise may not be completely removed, the maps cannot be switched, and there is a possibility that the rotation angle information has a discontinuous portion.

As a countermeasure against this, the present invention sets the ranges of the rotation angle information converted between the adjacent angle conversion maps, and so that they overlap each other. As a result, the lines connecting the map values overlap each other on the vertically extending broken line in FIG.

When the sensor output changes between 0 and 5V, the sensor output of 5V is changed to 10bit (1024bin).
1 bit of A / D converter to convert with resolution
Is calculated by the following formula. 5V ÷ 1024bin = 4.88mV (1) Then, the index is calculated by the following equation. Index = A / D conversion value of sensor output−sensor midpoint value + 300 bin (2) Therefore, the index of the angle conversion maps ~ has an A / D conversion value in the range of ± 300 bin, with the midpoint 2.5 V being 0 bin. To do.

In the angle conversion maps to, the threshold value for determining the setting range of the index is set to ± 300 bin so as to have the area e where the lines connecting the respective map values intersect.

The flow chart of FIG. 4 shows a routine for switching between the angle conversion maps and is executed by the controller 5 at regular intervals.

In this routine, in step 1, the first,
The converted values of the outputs A and B of the second hall elements 7 and 8 are read, and the next discrimination is performed based on the read values. When the converted value of the output A is in the range of ± 300 bin and the converted value of the output B is positive, the map is switched (steps 2, 3 and 4). When the converted value of the output A is within the range of ± 300 bin and the converted value of the output B is minus, the map is switched (steps 2, 3, 5, 6). If it is determined in step 5 that the converted value of the output B is not negative, the process proceeds to step 12 and the current information is continuously adopted. When the converted value of the output B is in the range of ± 300 bin and the converted value of the output A is positive, the map is switched (steps 7, 8 and 9). When the converted value of the output B is within the range of ± 300 bin and the converted value of the output A is negative, the map is switched (steps 7, 8, 10, 11). Note that step 10
When it is determined that the converted value of the output A is not negative, the process proceeds to step 13 and the current information is continuously adopted.

The controller 5 configured as described above
Changes the angle conversion map to, and uses one of the outputs A and B of the first and second Hall elements 7 and 8 having a larger voltage change with respect to the rotation angle as a signal for detecting the rotation angle, so that the entire rotation is performed. High sensor output resolution can be obtained over the angular range, and detection accuracy can be improved.

For example, while the second Hall element 8 makes one rotation, the output B gives the same output at, for example, two points, but the rotation angle is specified by monitoring the output A.

Then, adjacent angle conversion maps,
Since the ranges of the rotation angle information converted between and are overlapped with each other, it is possible to avoid that the maps cannot be switched due to noise or the like.

On the other hand, when there is no overlap area between the adjacent angle conversion maps, as shown in FIG. 5, in the vicinity of the intersection of the lines connecting the map values, noise from the surrounding environment or the like is generated. Overlapping on the sensor signal, the sensor output may exceed the intersection of the lines connecting the map values. In this case, it is impossible to switch the angle conversion map, and there is a problem that a discontinuous portion occurs in the rotation angle information.

As a countermeasure against this, the present invention sets the ranges of the rotation angle information converted between the adjacent angle conversion maps, and so that they overlap each other, so that noise is generated in the sensor output. When the sensor neutral position drifts due to the superposition of or due to the change of the ambient temperature, the angle conversion map can be surely switched, and the discontinuity in the rotation angle information can be prevented from occurring.

As another embodiment, as shown in FIG. 6, a rotation angle sensor 21 is provided with a case 20 and a rotation shaft 2 which rotate relative to each other, and a magnetic flux density detection unit 30 is provided on the case 20 via a support 26. While the first and second Hall elements 27, 28 are fixed, the permanent magnets 24, 25 are attached to the rotating shaft 2 as the magnetic circuit forming portion 31 via the rotor portion 23.
May be fixed.

An electromagnet consisting of a coil may be used as the magnetic circuit component instead of the permanent magnet.

It is obvious that the present invention is not limited to the above-mentioned embodiments and various modifications can be made within the scope of the technical idea thereof.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a rotation angle sensor according to an embodiment of the present invention.

FIG. 2 is a diagram showing the same sensor output characteristic.

FIG. 3 is a diagram similarly showing an angle conversion map.

FIG. 4 is a flowchart showing the same control contents.

FIG. 5 is an explanatory diagram showing how the sensor output changes similarly.

FIG. 6 is a configuration diagram of a rotation angle sensor according to another embodiment.

[Explanation of symbols]

1 Rotation angle sensor 3 Ring magnet (magnetic circuit component) 5 controller 7,8 First and second Hall element (Magnetic flux density detector)

Claims (3)

[Claims] 1. A magnetic circuit forming section for generating a magnetic field, and a magnetic flux density detecting section which relatively rotates in the magnetic field, wherein the magnetic flux density detecting section is arranged on a rotation center line of the magnetic circuit forming section intersecting with the magnetic circuit. 1. An angle conversion map configured by the second Hall element, and setting the rotation angle of the magnetic flux density detection unit with respect to the magnetic circuit configuration unit based on the output A of the first Hall element, and the output B of this second Hall element And an angle conversion map in which a rotation angle of the magnetic flux density detection unit with respect to the magnetic circuit configuration unit is set on the basis of the magnetic circuit configuration unit, and each angle conversion map is switched according to outputs A and B of the first and second Hall elements. In the rotation angle sensor configured to obtain the rotation angle of the magnetic flux density detection unit with respect to, the angle conversion maps are set so that the ranges of the converted rotation angles overlap each other. Rotation angle sensor and said and. 2. The first as a signal for detecting a rotation angle,
The rotation angle sensor according to claim 1, wherein one of the outputs of the second Hall element, which has a larger change in output with respect to the rotation angle, is used. 3. The rotation angle region is determined by using one of the outputs of the first and second Hall elements that has a smaller voltage change with respect to the rotation angle. Rotation angle sensor.