JPS63173901A - Rotation angle position detection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] As a method for eliminating the unmeasurable area found in conventional magnetic field leakage type rotation angle position detection devices, a plurality of detection sensors are provided, as well as a peak hold circuit and a switching circuit. A rotational angle position detection device that enables detection by correcting impossible areas.

[Industrial application field]

The present invention relates to an improvement in a magnetic field leakage type rotation angle position detection device.

A rotation angle position detection device (hereinafter commonly referred to as a rotation positioner) is a device that accurately detects the rotation angle of the rotating shaft of a motor or engine. For objects that can convert motion into rotational motion, accurate detection of the motion position is possible.

[Conventional technology]

In fields such as engine design, it is necessary to accurately detect the rotational position of a rotating shaft with respect to time.
) and potentiometer
was used.

In other words, the former is a device that determines the rotational position by measuring the number of light pulses generated by transmitting light from a light emitting diode when a circumferential part equipped with many equally spaced slits rotates. Although the rotation angle can be detected, a complicated mechanism is required to detect the rotation angle position from the reference position when stopping and rotating are repeated.

In addition, the latter method determines the rotational position by measuring the potential difference shown by the slider, but since the rotating part is constantly sliding on a resistor, the slider wears out, which leads to reliability problems. There's a problem.

The inventors have proposed a rotary positioner as a method to solve these problems.

(Patent application 1986-9566, application filed: January 20, 1986
Fig. 4 is a block diagram of this rotary positioner, and Fig. 5 is a diagram showing the relationship between the rotation angle and the sense output voltage.

That is, a permanent magnet 2 such as alnico is attached to one end of a ring-shaped magnetic circuit 1 made of a magnetic material such as iron, and a closed magnetic path is formed in the ring-shaped magnetic circuit 1, with a center portion 3 being the center. It is formed to be rotatable.

In this case, leakage magnetic flux 4 is distributed around the permanent magnet 2 inside and outside of the ring-shaped magnetic circuit 1.

Next, a magnetic field detection sensor 5 such as a magnetoresistive element is fixed at an inner peripheral position of the ring-shaped magnetic circuit as shown in the figure.

The rotary positioner has such a configuration, and the rotation of the ring-shaped magnetic circuit 1 causes the magnetic field detection sensor 5 to cut leakage magnetic flux, thereby generating a sense output proportional to the magnetic flux density.

In this case, even if the ring-shaped magnetic circuit 1 is fixed and the magnetic field detection sensor 5 rotates, the result is the same, but since the magnetic field detection sensor 5 is connected to the peripheral circuit, the ring-shaped magnetic circuit l It is advantageous to have an arrangement in which the

Now, when the ring-shaped magnetic circuit 1 rotates in the direction of the arrow 6, if the magnetic field detection sensor 5 is located at the end face position of the S pole of the permanent magnet 2 as the starting point of rotation, this position is the return point of the leakage magnetic flux. Therefore, the sense output is 0 as shown in Figure 5.
As the rotation angle increases, the sense output voltage increases linearly and reaches its maximum at the N pole end face of the permanent magnet 2 (position 01 in FIG. 5).

Next, when passing between the two poles of the permanent magnet 2, the sense output voltage decreases rapidly and becomes 0 at the end face of the S pole, but because there is a distance between the NS and the NS of the permanent magnet 2, the sense output voltage in FIG. NIA7
It descends obliquely as shown in , and does not descend at right angles as shown by the dashed line 8 .

Therefore, the same value as the sense output voltage generated during the rotation from 0° to θ1 appears between the slight rotations between the rotation angles of 01 and 360°, and the sense output voltage becomes indistinguishable.

This region is called a dead zone, and its existence is a drawback of the leakage magnetic field type rotary positioner, and it is necessary to solve this problem.

[Problem that the invention seeks to solve]

As mentioned above, in the leakage magnetic field type rotary positioner, there is a dead zone corresponding to the length of the permanent magnet attached to the ring-shaped magnetic circuit, but the problem is how to eliminate this zone. .

[Means for solving problems]

The above problem occurs in a magnetic field leakage type rotational angular displacement/position detection device that is equipped with a magnetic field detection sensor inside a rotating ring-shaped magnetic circuit and a peripheral circuit that converts the sense output. A switching circuit for the sense output and a peak hold circuit for the sense output are provided, and as the magnetic circuit rotates, the voltage value is held at the stage when each sense output increases, and the switching circuit holds the voltage at the beginning. This problem can be solved by a rotation angle detecting device that repeatedly superimposes the next sense output voltage on the sense output voltage of the first sense output voltage every rotation of the ring-shaped magnetic circuit.

[Effect]

The present invention has changed from the conventional method of detecting leakage magnetic flux using a single magnetic field detection sensor to using a plurality of magnetic field sensors, and as the sense output voltage increases as the rotation angle increases for each magnetic field sensor, The dead zone is eliminated by repeating the sequential switching and addition one rotation at a time.

Figure 1 shows an example in which two magnetic field detection sensors are used.
First magnetic field detection sensor (hereinafter abbreviated as first sensor) 10
and a second magnetic field detection sensor (hereinafter abbreviated as second sensor) 1
It is assumed that the ring-shaped magnetic circuit 1 is fixed at a symmetrical position 180° apart from the ring-shaped magnetic circuit 1, and rotates in the direction of the arrow.

Here, if the reference position is 0° when the first sensor IO is located at the interface of the S pole of the permanent magnet 2, the sense output is 0 at this position, so the sense output waveform diagram of the first sensor 10 is As shown in Fig. 3(A), θI ~360°,
Dead zones appear at θ2 to 720°, θ to 1080°, and so on.

On the other hand, the sense output of the second sensor 11 is shown in the figure (
It changes as shown in B), and θI ~ 180°.

A dead zone appears between θ2 and 540°.

Therefore, the present invention switches the detection circuit at a position where the sense output of the first sensor 11 is increasing and the sense output of the second sensor 11 becomes 0, and adds it to the previous sense output.
(C) of the same figure shows a change in waveform when only switching is performed.

The present invention holds the highest voltage value at the stage when the output of the first sensor is switched, and adds the output of the second sensor to this voltage value until the end of one rotation.
By adopting this method, the dead zone can be eliminated (see D in the same figure).

Note that it is necessary to clear the detection output after one rotation of the ring-shaped magnetic circuit 1 is completed, but this is done by the clock signal generated every time the ring-shaped magnetic circuit 1 rotates, as shown in the same figure (E). It can be carried out.

In this case, a case has been described in which there are two magnetic field detection sensors, but in the case of three magnetic field detection sensors, they may be arranged with an interval of 120 degrees, and the result is the same.

〔Example〕

FIG. 1 shows a case where two magnetic field detection sensors are used as described above, the magnet 2 is made of alnico, and the ring-shaped magnetic circuit 1 is made of iron.

Here, since the diameter of the ring-shaped magnetic circuit 1 is 501 m and the length of the permanent magnet 2 is 5.5 va, there is a dead zone of approximately 20° when measuring using a single magnetic field detection sensor as in the past. do.

FIG. 2 is a block diagram of a peripheral circuit 9 for implementing the present invention that eliminates the dead zone, and includes a first sensor 10 and a second sensor 10.
The output of the second sensor 11 is switched by driving the switch 13 with a signal from the switch drive circuit 12, and the previous peak voltage value is held by the peak hold circuit 14 shown by the broken line, and the output of the second sensor 11 is held at this voltage value. The outputs are added, and a linear output corrected for the unfavorable zone is obtained from the output terminal 15.

Note that the peak hold is cleared by a clock pulse generated every time the ring-shaped magnetic circuit 1 rotates 360°, and this pulse is transmitted from the sense outputs of the first sensor 10 and the second sensor 11 to the switch drive circuit 12. made by.

〔Effect of the invention〕

As described above, by implementing the present invention, it is possible to eliminate the dead zone, thereby improving the performance of the magnetic field leakage type rotary positioner.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a rotary positioner according to the present invention, FIG. 2 is a block diagram of a peripheral circuit for implementing the present invention, FIG. 3 is a waveform diagram explaining the present invention in detail, and FIG. Figure 5 shows the relationship between the rotation angle and detected voltage of the rotary positioner. In the figure, 1 is a ring-shaped magnetic circuit, 2 is a permanent magnet, 5 is a magnetic field detection sensor, 9 is a peripheral circuit, 10 is a first sensor, 11
12 is a switch drive circuit; and 14 is a peak hold circuit.

Claims (1)

[Claims] A magnetic field leak type rotational angle position detection device comprising a magnetic field detection sensor provided inside a rotating ring-shaped magnetic circuit and a peripheral circuit for converting the sense output, comprising: a plurality of detection sensors; A switching circuit for the sense output and a peak hold circuit for the sense output are provided, and as the magnetic circuit rotates, the voltage value is held at the stage when each sense output increases, and the switching circuit holds the voltage at the beginning. A rotational angle position detection device characterized in that the process of repeatedly superimposing the next sense output voltage on the sense output voltage is repeated every rotation of a ring-shaped magnetic circuit.