JP2000046513A - Rotation sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized rotation sensor which can be used even when the upper-limit temperature of the working environment is high. SOLUTION: When permanent magnets 8a and 8b rotate together with a rotating shaft 5, Hall elements 10a and 10b detect the magnetic fluxes of the magnets 8a and 8b. Since S poles and N poles are alternately arranged on the magnets 8a and 8b along the circumferential directions of the magnets 8a and 8b, the Hall elements 10a and 10b detect the poles and the detected values of the elements 10a and 10b are amplified by means of amplifiers. The amplified detected values and a threshold S are inputted to a comparator and the compared results are fetched as pulse signals. The angle of rotation and, furthermore, number of revolutions of the rotating shaft 5 can be obtained by counting the pulse signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rotation sensor,
It is suitable for use in a permanent magnet synchronous motor controlled by two or more types of rotation pulses.

[0002]

2. Description of the Related Art A rotary machine is provided with a rotation sensor for detecting a rotation speed. As a rotating machine, there is a permanent magnet type synchronous motor (hereinafter simply referred to as a PM motor) controlled by two or more types of rotation pulses. An optical rotary encoder is used as a rotation sensor of the PM motor.

[0003] As the rotary encoder, a single-shaft type PM motor having a structure attached to a shaft end on the opposite side is used, and a double-shafted PM motor having an annular shape surrounding the shaft is used.

[0004]

However, the rotary encoder has a problem that the guaranteed temperature is 85 ° C. and the upper limit temperature of the use environment is low. In addition, since the PM motor for EV detects the position of the magnetic pole and controls the motor current in accordance with the position signal, two types of rotation pulses are required, and an encoder is provided to detect this integrally. And to enlarge.

[0005] In particular, a flat type PM motor which is installed between an engine and a transmission to provide torque assist cannot use a rotary encoder because the ambient temperature is about 120 ° C and miniaturization is required. For this reason, a rotation sensor built into the engine or the transmission is diverted, but there are difficulties in detecting the zero rotation at the start and the rotation speed at the high speed.

Therefore, an object of the present invention is to provide a rotation sensor that solves the above problem.

[0007]

According to a first aspect of the present invention, there is provided a rotation sensor comprising a ring-shaped permanent magnet provided on a rotating body, an axial center of the rotating body and an axial center of the permanent magnet. Are attached in a state where they match, a permanent magnet is formed with alternately different magnetic poles in the circumferential direction, and a magnetic flux detector that detects a change in magnetic flux as a pulse is fixed at a position facing the permanent magnet,
A pulse detection circuit for calculating the rotation angle of the rotating body from the detected pulse is connected to a magnetic flux detector.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotation sensor according to the present invention will be described below.

(A) Embodiment 1 In this embodiment, the present invention is applied to a rotating machine. As shown in FIG. 1, a rotating shaft 5 is rotatably provided via bearings 4 and 4 in a case constituted by a pair of end plates 1 and 2 and a frame 3. A rotor 6 is attached to the rotating shaft 5, and a stator 7 surrounding the rotor 6 is attached to the inner peripheral surface of the frame 3.

As shown in the figure, ring-shaped permanent magnets 8a and 8b are fixed to the right end face of the rotor 6 with a part thereof embedded. On the other hand, Hall elements 10a and 10b as magnetic flux detectors are mounted on the inner side of the end plate 2 via a substantially U-shaped mounting member 9. Hall element 10a is a permanent magnet 8a
The Hall element 10b is opposed to the permanent magnet 8b from the side. As shown in FIG. 2A, the permanent magnet 8a is for a multi-pulse in which 17 S poles and N poles are alternately magnetized on the side surfaces of the ring, and the permanent magnet 8b has S poles and N poles alternately. Four small pulses are magnetized on the side of the ring.

The Hall elements 10a and 10b are connected to a pulse detection circuit 14 as shown in FIG. In FIG.
11 is a power supply, 12 is an amplifier, and 13 is a comparator.

Next, the operation of the rotation sensor will be described. In FIG. 1, when the permanent magnets 8a and 8b rotate together with the rotating shaft 5, the Hall elements 10a and 10b
The magnetic fluxes a and 8b are detected. Since the permanent magnets 8a, 8b are alternately arranged along the circumferential direction with S, N, S, N..., The Hall elements 10a, 10b detect this,
The detected value is amplified by the amplifier 12. Then, by inputting the amplified detection value and the threshold value S to the comparator 13, it can be extracted as a pulse signal. By counting the pulse signals, the rotation angle of the rotating shaft 5 and further the number of rotations can be obtained.

(B) Second Embodiment Next, a second embodiment is shown in FIG. In this embodiment,
Instead of the permanent magnets 8a and 8b, permanent magnets 8 having the same outer diameter are used.
c and 8d are fixed to the rotor 6. In the magnetization method, the permanent magnet 8c has the same number of magnetic poles on the outer peripheral surface of the ring as the permanent magnet 8a, and the permanent magnet 8d has the same number of magnetic poles on the outer peripheral surface of the ring as the permanent magnet 8b. It was done.

In such a rotation sensor, the permanent magnets 8c and 8
Since the outer periphery of d cannot be fixed, the configuration of the first embodiment is more advantageous in a high-speed rotating machine in consideration of the centrifugal resistance.

The other configuration and operation are the same as those of the first embodiment, and the description is omitted.

In the first and second embodiments, two types of permanent magnets, one for multi-pulses and one for small pulses, are provided. However, three or more permanent magnets may be provided. Fig. 2
As shown in FIG. 2A, instead of S, N, S, N.
As shown in (b), N, neutral, N, neutral,.
The pole may not be provided, or S, neutral,
It is also possible to adopt a system in which no N pole is provided, such as S or neutral.

[0017]

As can be seen from the above description, claim 1
According to the rotation sensor according to the above, since the ring-shaped permanent magnet and the magnetic flux detector are combined, the size can be reduced. Further, by changing the number of magnetic poles to be magnetized, two or more types of pulse detection can be easily performed. Furthermore, the upper limit temperature of the use environment can be increased as compared with the rotary encoder. Particularly, a flat type PM motor which is installed between an engine and a transmission to perform torque assist is useful because the mounting space is small and the upper limit temperature is high.

In addition, by attaching a ring-shaped permanent magnet to the rotor of the rotating machine, the rotation sensor can be attached to either a single-axis or double-axis rotating machine.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a rotating machine showing a first embodiment of a rotation sensor according to the present invention.

FIG. 2 is a front view of a permanent magnet incorporated in the rotating machine.

FIG. 3 is a configuration diagram of a pulse detection circuit in the rotation sensor according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a rotating machine showing a rotation sensor according to a second embodiment of the present invention;

[Explanation of symbols]

 6 rotor 8a-8d permanent magnet 10a-10d Hall element 14 pulse detection circuit

Continued on the front page (72) Inventor Koji Nagata 2-1-1-17 Osaki, Shinagawa-ku, Tokyo F-term in Meidensha Co., Ltd. (Reference) 2F063 AA35 BA30 CA10 DA01 DA04 DB07 DC08 DD05 GA52 GA71 LA11 LA23 2F077 AA28 NN24 PP12 QQ07 TT35

Claims (1)

[Claims] 1. A ring-shaped permanent magnet is attached to a rotating body in a state where the axis of the rotating body and the axis of the permanent magnet match.
The permanent magnet has magnetic poles that are alternately formed in the circumferential direction, and a magnetic flux detector that detects a change in magnetic flux as a pulse is fixed at a position facing the permanent magnet, and the rotation angle of the rotating body is determined from the detected pulse. A rotation sensor, wherein a pulse detection circuit to be calculated is connected to a magnetic flux detector.