JP4437067B2 - Non-contact Hall effect angular position sensor - Google Patents

Description

  The present invention relates to a contactless angular position sensor.

  The object of the present invention is to provide an angular position sensor which is accurate, robust and can be realized relatively inexpensively.

  This problem is solved by the angular position sensor according to the present invention.

The angular position sensor of the present invention includes a ferromagnetic ring having an axis, a magnetic source, a Hall effect cell, and a magnetic flux guide.
The magnetic source is disposed substantially in the center of the ring and generates a magnetic field in a magnetization direction perpendicular to the axis of the ring;
The Hall effect cell is arranged radially inside the ring and passing through the center of the ring and perpendicular to the magnetization direction and the axis of the ring, the Hall effect cell measures the radial magnetic field. ,
The magnetic flux guide is made of a ferromagnetic material, and is inserted between the magnetic source and the Hall effect cell, and the magnetic flux guide is rotatable about the magnetic source passing through the axis of the ring.

  This sensor is very robust because there is no contact between the elements forming this angular position sensor. This sensor exhibits good linearity between the change in voltage generated by the Hall effect cell and the angular displacement of the flux guide relative to the magnetic source, Hall effect cell and ring.

  In accordance with the present invention, the flux guide has the shape of an angular sector of the tube to improve linearity.

  The angular sector is preferably in the range of 120 ° to 150 °. By reducing the angular sector to 120 ° or less, the range of linearity of the angular position sensor is narrowed. However, increasing the sector to 150 ° or more does not further increase the linearity range of the angular position sensor. The linearity range can only slightly exceed 120 °.

  According to another configuration of the invention, the magnetic source is a parallelepiped permanent magnet. Therefore, the deviation from linearity can be maintained at several ‰ over 100 °.

  As a variant, the magnetic source is a circular cross-section cylindrical permanent magnet, which is arranged concentrically with respect to the ring. Although the inherent deviation from linearity is greater than in the previous embodiment, linearity can be significantly improved by applying sinusoidal correction.

  As shown, the angular position sensor 5 has four elements. That is, the magnetic source 1, the Hall effect cell 2, the ring 3, and the angular sector 4 forming the magnetic flux guide.

  The ring 3 and sector 4 must be highly permeable and ferromagnetic in order to facilitate the flux guiding action. These are advantageously made from pure iron in order to reduce the hysteresis effect.

  The ring 3 is circular and has an axis 8. The cross section of the ring is basically rectangular.

  The magnetic source 1 shown in FIG. 1 consists of a permanent magnet and is arranged at the center of the ring 3. The magnetization direction 6 of the magnetic source is oriented in the diameter direction of the ring. The magnet 1 and the ring 3 are fixed to each other.

  The Hall effect cells 2 are arranged along the radius of the ring and are oriented perpendicular to the magnetization direction 6. The Hall effect cell detects a radial magnetic field approaching the ring 3 and is fixed with respect to the ring. The output voltage from the cell 2 is proportional to the magnetic flux passing through it.

  Sector 4 is arranged between magnet 1 and cell 2. The sector extends beyond an angle of about 140 ° and is rotatable about the axis of the ring 3 with respect to the other elements. The sector extends radially between two cylindrical radial surfaces and has the shape of a portion of the tube.

  The sector 4 guides the magnetic flux from the magnet 1 toward the ring 3. The amount of magnetic flux that the sector captures depends on its location.

  FIG. 2 shows the center position of sector 4. That is, the center of the sector is on the radius 7. At this position, the sector forms a magnetic short between the two poles of the magnet. That is, very little magnetic flux passes through the ring, and the magnetic flux observed by the cell 2 is zero.

  FIG. 3 shows an intermediate position where the sector has been rotated by 30 °. Sector 4 captures a portion of the magnetic flux formed by magnet 1 and directs it evenly to ring 3. Cell 2 observes moderate magnetic flux.

  As sector 4 rotates continuously, the magnetic field scanned by cell 2 increases linearly. The sector covers one of the poles much larger and therefore captures more magnetic flux. In the position shown in FIG. 4, the sector covers substantially all of the poles, so the magnetic flux scanned by cell 2 is maximum. Here, sector 4 is rotated by 70 °.

  Since the magnetic flux is uniform between the sector and the ring, the position of the cell 2 does not have to be very accurate.

  The embodiment of FIG. 5 differs from the embodiment of FIG. 1 in that the magnetic source comprises a disk-shaped cylindrical magnet 1 and is arranged concentrically at the center of the ring 3. The magnet is magnetized along the same magnetization direction 6. The change of the signal generated by the cell 2 is here sinusoidal. When the sine wave component is removed, signal linearity equivalent to that of the embodiment shown in FIG. 1 is achieved with the same rotational amplitude.

  The present invention is not limited to the above embodiments. Electromagnets can also be used as magnetic sources instead of permanent magnets.

It is a perspective view of the angular position sensor by this invention.

It is a figure which shows the magnetic flux line of the angle position sensor in a different position.

It is a figure which shows the magnetic flux line of the angle position sensor in a different position.

It is a figure which shows the magnetic flux line of the angle position sensor in a different position.

It is a top view of another Example.

Claims (5)

An angular position sensor (5) having a ferromagnetic ring (3) with an axis (8), a magnetic source (1), a Hall effect cell (2), and a magnetic flux guide (4),
The magnetic source (1) is arranged substantially in the center of the ring (3) and generates a magnetic field in a magnetization direction (6) perpendicular to the axis (8) of the ring (3);
The Hall effect cell (2) is arranged inside the ring (3) in the radial direction (7) passing through the center of the ring, and the magnetization direction (6) and the axis (8) of the ring (3) The Hall effect cell (2) measures the radial magnetic field,
The flux guide (4) includes a magnetic source (1) is inserted between the Hall-effect cell (2), the flux guide is rotatable about the magnetic source passing through the axis of the ring,
An angular position sensor characterized by the above.   2. The angular position sensor according to claim 1, wherein the magnetic flux guide (4) has the shape of an angular sector of the tube.   The angular position sensor of claim 2, wherein the angular sector is in the range of 120 ° to 150 °. Magnetic source (1) is a permanent magnet parallel hexagonal body, the angular position sensor of any one of claims 1 to 3.   The angular position sensor according to any one of claims 1 to 3, wherein the magnetic source (1) is a cylindrical permanent magnet having a circular cross section and is arranged concentrically with respect to the ring (3).

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