JP2687602B2 - Rotational position detector - Google Patents

Description

The present invention relates to a rotational position detecting device, and more particularly to a rotational position detecting device using a magnetic detecting element.

[Prior Art] A device for detecting the rotational position of a rotating body without contact has been proposed. Among them, a device using a magnetic detection element such as a Hall element is often used because of its compactness and large output signal. Is being done.

One example is disclosed in US Pat. No. 4,506,217,
Its outline is shown in FIG. In the figure, on a peripheral surface of a rotary plate 1 mounted on a rotating body such as an engine crankshaft, a convex portion 11 and a concave portion 12 as rotational markers are arranged at equal intervals in the circumferential direction.
Are alternately formed. On the other hand, the substrate 6 is disposed so as to face the peripheral surface, and the magnetic detection elements 2A and 2B are formed on both ends of the substrate 6 in the circumferential direction. The distance between the magnetic detection elements 2A and 2B is about half the pitch of the convex portions 11.

A signal processing circuit 3 is formed in the central portion of the substrate 6, and the circuit 3 inputs the output signals of the magnetic detection elements 2A and 2B and detects whether the difference is positive or negative. A magnet body 4 is arranged behind the substrate 6, and a magnetic field from the magnet body 4 reaches the peripheral surface of the rotary plate 1 through the magnetic detection elements 2A and 2B.

When the rotary plate 1 is rotated, the convex portions 11 and the concave portions 12 are moved to the substrate 4
One of the magnetic detection elements
When the convex portion 11 is passing just before 2A, the concave portion 12 is passing just before the other magnetic detecting element 2B, and since the magnetic flux density is large at a position near the convex portion 11, the output of the magnetic detecting element 2A. The signal has a higher level than that of the magnetic detection element 2B. This difference in level is caused by the rotation of the rotary plate 1 by each magnetic detection element 2
When the convex portion 11 and the concave portion 12 passing just before A and 2B are replaced,
Invert.

With such a configuration, a large element output can be obtained and temperature compensation can be performed.

[Problems to be Solved by the Invention] By the way, in the above-described conventional rotational position detecting device, unless the interval between the magnetic detecting elements is set to about half the pitch of the convex portions of the rotating plate, the element immediately before one of the elements is convex. When the part passes, the concave part does not pass immediately before the other element, and good operation cannot be obtained. Therefore, when the pitch of the convex portions of the rotating plate is changed, it is necessary to change the gap between the magnetic detection elements accordingly, and it is necessary to prepare various substrates according to the engine type, for example.

Further, as shown in FIG. 6, the convex portion (or concave portion) of the rotary plate
If the pitch is not constant, convex portions (or concave portions) may be located on any of the magnetic detection elements as shown by the chain line in the figure, and good operation cannot be expected.

The present invention is to solve such a problem, and even if the pitch of the rotation indicator of the rotating plate is not constant, or even if the pitch specification is changed, it is possible to always perform good rotation position detection with the same detection unit. An object is to provide a possible rotational position detecting device.

[Means for Solving the Problems] To explain the configuration of the present invention, a rotational position detecting device includes a pair of tracks 1a extending in the circumferential direction in parallel on the peripheral surface of a rotating plate 1 (FIG. 1) made of a magnetic material. , 1b, one track 1a alternately forms a convex portion 11 and a concave portion 12 at a predetermined interval, the other track 1b, the concave portion 12 corresponding to the convex portion 11 of the one track 1a, The convex portions 11 are formed corresponding to the concave portions 12, and the magnetic detection elements 2A and 2B are provided so as to face the respective tracks 1a and 1b, and the magnetic detection elements 2A and 2B are provided behind the magnetic detection elements. 2A,
A magnet body 4 that forms a magnetic field that passes through 2B and reaches the peripheral surface of the rotating plate 1 and a signal detection circuit 3 that detects positive / negative inversion of a difference between output signals of the magnetic detection elements 2A2B. Is.

Further, the rotational position detecting device having another configuration forms N poles 13 and S poles 14 alternately at a predetermined interval on one of the pair of tracks 1a, 1b (FIG. 4) extending in parallel in the circumferential direction, and
The other track 1b has the north pole 13 of the one track 1a.
Corresponding to S pole 14 and S pole 14 corresponding to N pole 13
And magnetic detection elements 2A and 2B are provided so as to face the tracks 1a and 1b, respectively, and a signal detection circuit 3 that detects the inversion of the difference between the output signals of these magnetic detection elements 2A and 2B is detected. It is provided.

[Operation] In the device having the above-described configuration, as the rotary plate 1 rotates, the convex portions 11 and the concave portions 12 on the tracks 1a and 1b alternately pass in front of the magnetic detection elements 2A and 2B, which face the convex portions 11 and the concave portions 12, respectively. However, the output signal level of the magnetic detection element 2A passing through the convex portion 11 is high, and the output signal level of the magnetic detection element 2B passing through the concave portion 12 is low. When the convex portion 11 passes in front of the one magnetic detection element 2A, the concave portion 12 always passes in front of the other magnetic detection element 2B.
It does not change even if the pitch of 11 (or recess 12) changes, and therefore, a good output signal is always obtained even when the pitch specification is changed or the pitch is not constant, and the positive / negative inversion of the difference between the signals is obtained. The rotation position of the rotary plate 1 is reliably detected by the detection.

Instead of the convex portion 11 and the concave portion 12, an N pole is formed on the peripheral surface of the rotating plate 1.
When 13 and S pole 14 are formed, each magnetic detection element 2A, 2B
The direction of the magnetic field that passes through is alternately changed, and the positive / negative of the difference between the output signals is inverted with the rotation of the rotary plate 1, and the rotational position of the rotary plate 1 is known. According to this structure, the magnet body 4 for forming the magnetic field is not required.

[First Embodiment] In FIG. 1, a circular rotary plate 1 is connected to a center, for example, an engine crankshaft (not shown) to rotate. The peripheral surface of the rotary plate 1 is divided into upper and lower parts to form a pair of adjacent tracks 1a, 1b extending in the circumferential direction. The track 1a has a convex portion of a constant circumferential length protruding outward in the radial direction. 11, and concave portions 12 are alternately formed between the convex portions 11. Also,
On the track 1b, the recesses 12 of the same length are formed adjacent to the projections 11 of the track 1a, and the projections 11 of the same length are formed adjacent to the recesses 12 alternately.

The semiconductor substrate 6 is made to face the peripheral surface of the rotating plate 1 closely.
Are arranged on the substrate 6 at the upper and lower positions of the surface facing the peripheral surface of the rotary plate 1, and magnetic detection elements such as Hall elements are provided.
2A and 2B are formed to face the tracks 1a and 1b.

A signal detection circuit 3 whose details will be described later is formed in the central portion of the substrate 6, and the output signal of the detection circuit 3 is input to an external engine control circuit 5.

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

FIG. 2 shows the configuration of the signal detection circuit 3, which is a differential amplifier 31 for receiving the output signals of the magnetic detection elements 2A and 2B.
It is composed of a waveform shaping circuit 32 for shaping the output of the amplifier 31, and an output transistor 33.

In the rotational position detecting device having the above-mentioned configuration, when the rotary plate 1 rotates, the convex portion 11 and the concave portion are provided immediately in front of the magnetic detection elements 2A and 2B.
12 passes alternately. When the convex portion 11 passes in front of the magnetic detection element 2A, the concave portion is always in front of the magnetic detection element 2B.
When the concave portion 12 passes in front of the magnetic detection element 2A, the convex portion 11 always passes in front of the magnetic detection element 2B.

Since the density of the magnetic flux passing through the magnetic detection element 2A becomes large when the convex portions 11 are close to each other, both the magnetic detection elements 2A,
The output signal level of 2B is alternately higher one than the other. Then, the output of the differential amplifier 31 is alternately inverted between positive and negative as it passes through the convex portion 11 and the concave portion 12 of the rotary plate, and the transistor 33 is turned on and off via the waveform shaping circuit 32.
The output pulse of the transistor 33 is input to the engine control circuit 5, and engine control or the like is performed based on this rotation information.

According to the above structure, even if the number of the convex portions 11 is changed and the pitch thereof is changed, the convex portions 11 face one of the magnetic detection elements 2A and 2B, and the concave portion 12 always faces the other, so that the magnetic sensing elements 2A and 2B always face each other. Reliable rotational position detection is possible.

[Second Embodiment] In FIG. 3, the lengths of the projections 11 of the rotary plate track 1a are not constant, and the tracks 1b adjacent to the projections 11 are adjacent to each other.
The lengths of the recesses 12 of the are also different. Even in such a case, when one of the magnetic detection elements 2A faces the convex portion 11, the other magnetic detection element 2B always faces the concave portion 12, and therefore, as in the first embodiment, a reliable result is obtained. The rotational position can be detected.

[Third Embodiment] In FIG. 4, in place of the convex portion 11 and the concave portion 12 of the above-mentioned respective embodiments, the N pole of the magnetic pole is arranged on each track 1a, 1b on the peripheral surface of the rotating plate 1.
13 and S pole 14 are formed alternately, and N of track 1a is formed.
An S pole 14 of the same length is formed adjacent to the track 1b on the pole 13
An N pole 13 is formed adjacent to 14 on the pole.

In such a structure, when the rotary plate 1 rotates, the N pole 13 and the S pole 14 alternately pass in front of the magnetic detection elements 2A and 2B,
Along with this passage, the direction of the magnetic field passing through the magnetic detection elements 2A and 2B changes, and the positive / negative of the output signal changes. Therefore, the differential amplifier 31 (second
The positive and negative signs of the output signal shown in the figure) are inverted each time the magnetic poles 13 and 14 pass, and rotation information is obtained.

According to this embodiment, the same effects as those of the above-described embodiments are obtained, and it is not necessary to separately provide the magnet body 4.

[Effects of the Invention] As described above, according to the rotational position detection device of the present invention, even when the pitch specifications of the convex portions or concave portions or the magnetic poles as the rotation markers provided on the rotary plate are changed, the magnetic detection portion is changed. It is possible to reliably detect the rotational position without making any changes.
Further, even when the pitch of the convex portions or the like is not constant, the rotational position can be detected well.

[Brief description of the drawings]

1 and 2 show a first embodiment of the present invention.
FIG. 1 is a schematic perspective view of the device, FIG. 2 is a circuit diagram of a signal detection circuit, and FIGS. 3 and 4 are schematic perspective views of the device showing second and third embodiments of the present invention, FIG. Sixth
FIG. 5 shows a conventional example, FIG. 5 is a perspective view of the main part of the apparatus, and FIG. 6 is a schematic side view of the main part of the apparatus. 1 ... Rotating plate 1a, 1b ... Track 11 ... Convex part 12 ... Recessed part 13, 14 ... Magnetic pole 2A, 2B ... Magnetic detection element 3 ... Signal detection circuit 31 ... Differential amplifier 4 ... Magnet body

Claims (2)

(57) [Claims] 1. A peripheral surface of a rotating plate made of a magnetic material is divided into a pair of tracks extending in the circumferential direction in parallel, and a convex portion and a concave portion are alternately formed at a predetermined interval on one of the tracks.
On the other track, a concave portion is formed so as to correspond to the convex portion of the one track, a convex portion is formed so as to correspond to the concave portion, and a magnetic detection element is provided so as to face each of the above tracks, and these magnetic detections are performed. Behind the element, a magnetic body that forms a magnetic field that passes through each magnetic detection element and reaches the peripheral surface of the rotating plate is provided, and a signal detection circuit that detects positive / negative inversion of the difference between the output signals of the magnetic detection elements is provided. A rotational position detecting device provided. 2. A peripheral surface of a rotating plate is divided into a pair of tracks extending in a circumferential direction in parallel, and one track has N poles and S poles of magnetic poles alternately formed at a predetermined interval, and the other track. Are formed with S poles corresponding to the N poles of the one track and N poles corresponding to the S poles, respectively, and magnetic detection elements are provided facing the respective tracks, and these magnetic detection elements are provided. The rotational position detecting device is provided with a signal detection circuit for detecting positive / negative inversion of the difference between the output signals of.