JPS5930616Y2 - Rotating machine position detector - Google Patents

Description

[Detailed description of the invention] The present invention relates to a position detector for a rotating machine that detects the position or speed of a rotor of a rotating machine using a magnet and a magnetically sensitive element.
In particular, the present invention relates to a position detector disposed near a coil end of a stator to cut off leakage magnetic flux from the coil end.

Position detectors used as distributors and motor speed detectors in brushless DC machines are equipped with a magnet mounted on the rotor itself or a rotating disk integrated with the rotor, and placed facing the axis of rotation of the magnet. At least one magnetically sensitive element (magnetic variable resistance element, Hall element, etc.) is provided in the stator or rotating machine casing, and the rotational position or speed of the rotor is detected from the output signal phase and frequency of the magnetically sensitive element.

Here, in the case of a position detector in which a magnet is provided in the rotor and a magnetically sensitive element is provided in the stator, it is not necessary to provide a rotating disk for position detection on the rotating machine, and it can be used for rotating machines where space is limited. This is convenient for improving existing rotating machines.

However, since the magnetically sensitive element is placed near the coil end of the stator, the magnetically sensitive element senses the leakage magnetic flux from the coil end and incorrectly detects the position, resulting in unstable speed control and brush strokes. In a DC machine without this, a false ignition signal will destroy the switching element.

The present invention features a structure in which a magnet is installed in the rotor and a magnetically sensitive element is placed near the stator coil end in the position detector, which can cut off leakage magnetic flux from the coil end, making reliable position detection possible. The purpose is to provide

Figure 1 shows an embodiment of the present invention, which is an axial air gap motor (
This is the case when applied to a flat type motor).

A stator 3 having radial slots is provided on the side surface of a rotor 2 integrally provided with a shaft 1, and a winding 4 is housed in the stator 3.

5 is a thrust bearing. In such a motor, in order to detect the position or speed of the rotor 2, a magnet 6 is embedded in the side surface of the rotor 2, and a non-magnetic support is placed on the stator 3 side to face the rotation trajectory of the magnet 6. Magnetically sensitive element 8 is arranged by member 7 .

Here, the support member 7 and the coil end portion 4 of the stator winding 4
A magnetic shield 9 made of a magnetic material such as a silicon steel plate is interposed between the coil end and the magnetic element 8 to block leakage magnetic flux from the coil end toward the magnetically sensitive element 8.

This magnetic shield 9 has a shape that covers the coil end 4A near where the magnetically sensitive element 8 is located, and is divided into an appropriate number of pieces as shown in FIG. 2 to reduce eddy current loss due to leakage magnetic flux. This prevents the magnetically sensitive element 8 from overheating.

Note that the magnetic shield 9 is usually a coil end 4A.
Since the shape of the magnetic element 8 becomes complicated, the leakage magnetic field distribution also becomes complicated. Therefore, for a good magnetic shield, it is preferable to have a shape that covers the outside of the coil end, instead of interposing it only on the back surface of the magnetically sensitive element 8.

Further, the number of divisions of the magnetic shield 9 must be designed to be an appropriate number or more depending on the rotating machine to which it is applied, as shown in FIG. 3, which shows the relationship with temperature rise.

By providing such a magnetic shield, even when a position detector using magnetism is installed near the coil end, leakage magnetic flux from the coil end can be prevented from being sensitive to the magnetic element, and the magnet and the magnetic element can be prevented. Magnetic silt has a favorable effect on forming a magnetic path between the two.

In addition, although the example shows the case where it is applied to a flat type motor, when it is applied to a normal cylindrical rotating machine, the magnet is installed on the side surface near the gap of the rotor, and the magnet is installed near the stator coil end on the side where the magnet is installed. The same effect can be obtained by providing a magnetically sensitive element through a magnetic shield.

As described above, the position detector according to the present invention has the effect of preventing malfunctions in position detection due to leakage magnetic flux from the coil end when a magnetically sensitive element is provided near the coil end in a rotating machine that is aimed at miniaturization. .

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view showing an embodiment of the present invention, FIG. 2 is a perspective view of the magnetic shield in FIG. 1, and FIG. 3 is a diagram illustrating temperature rise characteristics with respect to the number of divisions of the magnetic shield. 2...Rotor, 3...Stator, 4...
... Coil, 4A ... Coil end, 6.
...Magnet, 8...Magnetic sensitive element, 9
...Magnetic shield.

Claims (1)

[Scope of utility model registration request] In a position detector in which a magnet is provided on the rotor of a rotating machine, and a magnetically sensitive element is provided on the stator facing the rotation locus of the magnet, the magnetically sensitive element is arranged on a non-magnetic support member, and the magnetically sensitive element is arranged on a non-magnetic support member. A magnetic shield plate divided into a plurality of parts is interposed between the coil end of the stator winding and the coil end to cover the coil end and cut off leakage magnetic flux from the coil end toward the magnetically sensitive element. position detector for rotating machines