JPH0342514A - Rotation position detector - 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 [Industrial Application Field] The present invention relates to a rotational position detection device, and particularly to a rotational position detection device using a magnetic detection element.

[Prior art] Devices that detect the rotational position of a rotating body without contact have been proposed, and among these devices, devices using magnetic detection elements such as Hall elements are widely used because they are compact and can obtain large output signals. It is being done.

An example thereof is disclosed in US Pat. No. 4,506,217 and is schematically shown in FIG. In the figure, convex portions 11 and four portions (2) as rotation indicators are alternately formed at equal intervals in the circumferential direction on the circumferential surface of a rotary plate 1 attached to a rotating body such as an engine crankshaft. A substrate 6 is disposed so as to face the surface thereof, and magnetic detection elements 2A and 2B are formed on both ends of the substrate 6 in the circumferential direction, respectively. The distance between the magnetic detection elements 2A and 2B is determined by the above-mentioned convex portion 1.
This is approximately half the pitch of 1.

A signal processing circuit 3 is formed in the center of the substrate 6, and the circuit 3 receives the output signals of the magnetic detection elements 2A and 2B and detects whether the difference is positive or negative. Board 6
A magnet body 4 is disposed behind the magnet body 4, and the magnetic field from the magnet body 4 passes through each of the magnetic detection elements 2A and 2B to the rotary plate 1.
It reaches the periphery.

When the rotary plate 1 rotates, the convex portion 11 and the concave portion 12 sequentially pass close to the front position of the substrate 4, but when the convex portion 11 is passing directly in front of the magnetic detection element 2A on the negative side, the magnetic detection element 2A on the other side The four parts 12 pass just in front of the detection element 2B, and since the magnetic flux density is large at a position close to the convex part 11, the output signal of the magnetic detection element 2A has a higher level than that of the magnetic detection element 2B. This difference in level is reversed when the convex portion 11 passing in front of each magnetic detection element 2A, 2B replaces the four portions 12 due to the rotation of the rotary plate 1.

With such a configuration, it is possible to obtain a large element output and also to perform temperature compensation.

[Problems to be Solved by the Invention] By the way, in the conventional rotational position detection device described above, unless the interval between the magnetic detection elements is set to about half the pitch of the convex parts of the rotary plate, the protrusion may occur just in front of one element. When one element passes through the other element, the concave part does not pass directly in front of the other element, and good operation cannot be obtained.

Therefore, when the pitch of the rotating plate convex portions is changed, it is necessary to change the spacing between the magnetic detection elements accordingly, and it is necessary to prepare various substrates depending on the engine type, for example.

In addition, as shown in FIG. 6, if the pitch of the rotating plate convex portions (or concave portions) is not constant, the convex portions (or concave portions) may be located on any of the magnetic sensing elements as shown by the chain line in the figure. Therefore, good operation cannot be expected.

The present invention solves this problem, and even if the pitch of the rotation mark on the rotary plate is not constant or the pitch specification is changed, it is possible to always perform good rotational position detection with the same detection unit. The object of the present invention is to provide a rotary position detection device that is capable of detecting rotational positions.

[Means for Solving the Problems] To explain the present invention in detail, the rotational position detection device includes a pair of tracks 1 extending in parallel in the circumferential direction on the circumferential surface of a rotating plate 1 (FIG. 1) made of a magnetic material. One track 1a has convex portions 11 and concave portions 12 alternately formed at predetermined intervals, and the other track 1b has concave portions 12 corresponding to the convex portions 11 of one track 1a. A convex portion 11 is formed corresponding to the concave portion 12, and magnetic detecting elements 2A, 2B are provided facing each of the tracks 1a, 1b, and these magnetic detecting elements 2A
, 2B is provided with a magnet body 4 that forms a magnetic field that passes through each magnetic detection element 2A, 2B and reaches the circumferential surface of the rotary plate 1, and the difference between the output signals of each magnetic detection element 2A, 2B is A signal detection circuit 3 for detecting positive/negative inversion is provided.

Further, a rotational position detection device having another configuration includes forming N poles 13 and S poles 14 alternately at predetermined intervals on one of the pair of tracks 1a and 1b (FIG. 4) extending in parallel in the circumferential direction, and The other track lb has the above one track 1.
A south pole 14 is formed to correspond to the north pole 13 of a, and a north pole 13 is formed to correspond to the south pole 14, and magnetic detection elements 2A, 2B are formed to face the respective tracks 1a, 1b.
In addition, a signal detection circuit 3 is provided for detecting the reversal of the positive and negative polarity of the difference between the output signals of these magnetic detection elements 2A and 2B.

[Operation] In the device configured as described above, as the rotary plate 1 rotates, the convex portions 11 and concave portions 12 on each track 1a, 1b alternately pass in front of each magnetic detection element 2A, 2B facing thereto. The magnetic detection element 2A through which the convex portion 11 passes
The output signal level of the magnetic detection element 2B through which the fourth section 12 passes is low. When the convex part 11 passes in front of one magnetic detection element 2A, the concave part 12 always passes in front of the other magnetic detection element 2B, and this relationship holds true for the convex part 11 (or four parts). 12> does not change even if the pitch changes, so even if the pitch specifications are changed or the pitch is not constant, a good output signal can always be obtained. The rotational position of the rotary plate 1 is reliably detected.

Instead of the convex portions 11 and four portions 12, N
When the pole 13 and the S pole 14 are formed, the direction of the magnetic field passing through each magnetic detection element 2A, 2B changes alternately, and this also causes the difference in the output signals as the rotary plate l rotates. The polarity of is reversed, and the rotational position of the rotary plate 1 is known.

According to this configuration, the magnet body 4 for forming a magnetic field is not required.

[First Embodiment] In FIG. 1, a circular rotary plate l is connected at its center to, for example, an engine crankshaft and rotates. The circumferential surface of the rotary plate l is divided into upper and lower sections, forming a pair of adjacent tracks la and 1b extending in the circumferential direction.
A has a convex portion 11 having a constant length in the circumferential direction and protruding outward in the radial direction.
The recesses 12 are alternately formed between the projections 11. Further, in the track 1b, concave portions 12 of the same length are formed adjacent to the convex portions ↓1 of the rack 1a, and convex portions 11 of the same length are alternately formed adjacent to the concave portions 12.

A semiconductor substrate 6 is disposed so as to closely face the circumferential surface of the rotary plate 1, and magnetic sensing elements 2 such as Hall elements are disposed on the substrate 6 at upper and lower positions of the surface facing the circumferential surface of the rotary plate 1, respectively.
Tracks A and 2B are formed and face the respective tracks la and lb.

At the center of the board 6 is a signal detection circuit 3 whose details will be described later.
The output signal of the detection circuit 3 is input to an external engine control circuit 5.

A plate-shaped magnet 4 is provided behind the substrate 6, and forms a magnetic field directed toward the outer periphery of the substrate 1 through each of the magnetic detection elements 2A, 2B.

FIG. 2 shows the configuration of the signal detection circuit 3, and a differential amplifier 3 inputs the output signals of the remagnetization detection elements 2A and 2B.
1. a waveform shaping circuit 32 that shapes the output of the amplifier 31;
and an output transistor 33.

In the rotational position detection device having the above configuration, when the rotary plate (2) rotates, the convex portions 11 and the concave portions (2) alternately pass in front of each magnetic detection element 2A, 2B. And magnetic detection element 2A
When the convex part 11 passes in front of the magnetic sensing element 2B, the concave part 12 always passes in front of the magnetic sensing element 2B, and when the concave part 12 passes in front of the magnetic sensing element 2A, the convex part always passes in front of the magnetic sensing element 2B. Section 11 passes.

Since the density of the magnetic flux passing through the magnetic detection element 2A increases when the convex portions 11 are close to each other, the remagnetization detection element 2
The output signal levels of A and 2B are alternately higher, one with respect to the other. Thus, the output of the differential amplifier 31 is alternately reversed in polarity as it passes through the convex portion 11 and the concave portion 12 of the rotary plate, and passes through the waveform shaping circuit 32 to the transistor 33.
Turn it OFF. The output pulse of the transistor 33 is input to the engine control circuit 5, and the engine is controlled based on this rotation information.

According to the above structure, even if the number of installed protrusions 1■ is changed and the pitch changes, the protrusions 11 will always face one of the magnetic detection elements 2A and 2B, and the four parts 2 will always face the other. ,
Reliable rotational position detection is always possible.

[Second Embodiment] In FIG. 3, the lengths of the convex portions 11 of the rotating plate track 1a are not constant, and the lengths of the concave portions 12 of the track 1b adjacent to and corresponding to these convex portions 11 are also different. Even in such a case, when one magnetic sensing element 2A faces the convex part 11, the other magnetic sensing element 2B always faces the concave part 1.
2, it is possible to detect the rotational position reliably as in the first embodiment.

[Third Example] In FIG. 4, the convex portion ■1 and the fourth portion 12 of each of the above embodiments are
Instead, magnetic poles 7) N poles 13 and S poles 14 are alternately formed on each track 1a, 1b on the circumferential surface of the rotary plate 1, and
A south pole 14 of the same length as the track 1b is formed adjacent to the north pole 13 of the track la, and the north pole 13 is adjacent to the south pole 14.

In this structure, when the rotary plate 1 rotates, the N pole 13 and the S pole 14 alternately pass in front of each magnetic detection element 2A, 2B, and as they pass, a magnetic field passes through each magnetic detection element 2A, 2B. The direction of the output signal changes, and the sign of the output signal changes. Thus, the output signal of the differential amplifier 31 (FIG. 2) which calculates the difference between the output signals is reversed in sign each time it passes each magnetic pole 13, 14, and rotation information is obtained.

According to this embodiment, the same effects as those of the above-mentioned embodiments can be obtained, and there is no need to provide the magnet body 4 separately.

[Effects of the Invention] As described above, according to the rotational position detection device of the present invention, even when the pitch specification of the convex portion or four portions as a rotation mark provided on the rotary plate or the pitch of the magnetic poles is changed, the magnetic detection unit remains unchanged. The rotational position can be reliably detected without making any changes, and the rotational position can also be detected satisfactorily even when the pitch of the convex portions, etc. is not constant.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 and 2 show a first embodiment of the present invention.
2 is a circuit diagram of a signal detection circuit, FIGS. 3 and 4 are schematic perspective views of an apparatus showing second and third embodiments of the present invention, and FIGS. 6 shows a conventional example, FIG. 5 is a perspective view of the main part of the device, and FIG. 6 is a schematic side view of the main part of the device. 1...Rotary plates 1a, 1b...Track 11...Convex portion 12...Concave portion 13.14...Magnetic poles 2A, 2B...Magnetic detection element 3...Signal detection circuit 31...・Differential amplifier Part 2 Figure 3

Claims (2)

[Claims] (1) The circumferential surface of a rotary plate made of magnetic material is divided into a pair of tracks extending in parallel in the circumferential direction, one track is formed with convex portions and concave portions alternately at predetermined intervals, and the other track is formed with convex portions and concave portions alternately at predetermined intervals. forming a concave portion corresponding to the convex portion of one of the tracks and a convex portion corresponding to the concave portion;
A magnetic detection element is provided facing each of the tracks, and a magnet body is provided behind each magnetic detection element to form a magnetic field that passes through each magnetic detection element and reaches the circumferential surface of the rotating plate, and each of the magnetic A rotational position detection device characterized by being provided with a signal detection circuit that detects the reversal of the positive and negative polarity of the difference between the output signals of the detection elements. (2) The circumferential surface of the rotary plate is divided into a pair of tracks extending in parallel in the circumferential direction, and N and S poles are formed alternately at predetermined intervals on one track, and on the other track. , a south pole is formed corresponding to the north pole of one of the tracks, and a north pole is formed corresponding to the south pole of one of the tracks, and a magnetic detection element is provided facing each of the tracks, and the output of these magnetic detection elements is formed. A rotational position detection device comprising a signal detection circuit that detects the reversal of the sign difference between signals.