JPH0617043Y2 - Direction sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an azimuth sensor having a magnet that rotates to follow the geomagnetic direction.

[Conventional technology]

2. Description of the Related Art Conventionally, as this type of azimuth sensor, an azimuth meter whose bottom view is shown in FIG. 4 and whose structure is shown in FIG. 5 has been used. That is, FIG. 5 is a cross-sectional view taken along the line VV in FIG. 4, in which the rotor shaft 1-2 is fixed through the center of the magnet (permanent magnet) disk 1-1 so as to form a movable magnet. Have one. This movable magnet 1
It is arranged inside a coil bobbin composed of an upper frame 2 in which the bearing 2a is press-fitted and a lower frame 3 in which the bearing 3a is press-fitted, and is disposed in the bearing 2a of the upper frame 2 and the bearing 3a of the lower frame 3. By inserting and inserting one end and the other end of the rotor shaft 1-2, the rotor shaft 1-2 rotates following the geomagnetic direction. Then, the lower frame 3 is provided with an oil reservoir 3b to be filled with working oil, and the movable magnet 1 is braked by the viscosity of this working oil.

[Problems to be solved by the device]

However, according to the orientation sensor having such a structure,
Since the braking force of the movable magnet 1 is obtained by the viscosity of the hydraulic oil, the following problems occur.

That is, (1) the viscosity of hydraulic fluid has a large temperature dependency, and therefore the braking temperature characteristic is poor.

(2) In order to obtain the braking force due to the viscosity of the hydraulic oil, mechanical hysteresis is inevitably generated in the state of the minimum driving force (6th
See figure).

(3) Since the driving force generated by the small magnetism of 0.3GAUSS is braked, the viscosity is extremely low and the amount is very small, making it difficult to control the amount of hydraulic oil injected.

[Means for Solving the Problems]

The present invention has been made in order to solve such a problem, and is provided with a braking cup made of a non-magnetic conductive member so as to surround and surround the permanent magnet magnet.

[Action]

Therefore, according to the present invention, when the permanent magnet magnet rotates, an eddy current is generated in the braking cup made of the non-magnetic conductive member.

〔Example〕

Hereinafter, the orientation sensor according to the present invention will be described in detail based on embodiments.

FIG. 2 is a bottom view of this azimuth sensor, and FIG. 1 is a sectional view taken along line I-I showing its structure. In these figures, the same reference numerals as those in FIGS. 4 and 5 indicate the same components, and the description thereof will be omitted. In this embodiment, the difference from the conventional orientation sensor is that inside the coil bobbin,
The magnet disk 1-1 is surrounded by a braking cup 4 made of a non-magnetic conductive member, and the oil reservoir chamber 3b is removed from the lower frame 3 to form a lower frame 3 '. . The braking cup 4 is fixed to the lower frame 3'and the braking cup 4
The upper frame 2 is slightly modified in shape to form the upper frame 2 '.

FIG. 3 is a circuit diagram showing an azimuth meter configured by using this azimuth sensor 10. Although not shown in FIG. 1,
Hall elements 5-1 and 5-2 are arranged facing each other with a phase difference of 90 ° on the outer peripheral surface of the magnet disk 1-1. That is, the magnet disc 1-1 is magnetized so that the strength of the magnetic field around the magnet disc becomes sinusoidal, and the magnetic pole position of this magnet disc 1-1 is determined by the Hall elements 5-1 and 5-2. It is supposed to be detected. Then, the magnetic pole position detection signals obtained from the Hall elements 5-1 and 5-2 are given to the amplifier circuit 11 at the next stage, and the amplified current corresponding to the given magnetic pole position detection signal is supplied to the cross coil type display 12. By flowing the X-axis direction coil 121 and the Y-axis direction coil 122, a magnetic flux corresponding to the amplified current is generated in the coils 121 and 122, and the rotation angle of the magnet rotor 123 is determined by this magnetic flux. That is, by rotatably supporting the magnet rotor 123 in the magnetic field formed by the coils 121 and 122, the geomagnetic direction acting on the magnet disc 1-1 is displayed on the display 12 based on the rotation angle of the magnet rotor 123.
It is supposed to be reproduced accurately in.

The coils 6-1 and 6-2 wound around the coil bobbin in the direction sensor 10 are correction coils used to correct the residual magnetic field when the direction sensor 10 is arranged in a vehicle or the like. Yes, the coils 6-1 and 6-2 are set to 9 in the X-axis direction and the Y-axis direction of the direction sensor 10, respectively.
I am wearing it at a crossing angle of 0 °. That is, when the vehicle residual magnetic field H ′ is applied to the azimuth sensor 10, a magnetic field whose absolute value is equal to and opposite in direction to the vehicle residual magnetic field H ′ is reversed by operating the variable resistors 13 and 14.
Is generated via the magnetic field, so that the vehicle residual magnetic field H'can be canceled.

Here, assume that the movable magnet 1 of the orientation sensor 10 rotates following the geomagnetism. When the movable magnet 1 rotates, that is, the magnet disc 1-1
When rotates, an eddy current flows in the braking cup 4 surrounding the magnet disc 1-1. A magnetic field is generated around the braking cup 4 by this eddy current, and a force that impedes the rotational movement of the magnetic disk 1-1 is generated by this magnetic field. That is, the movable magnet 1 is braked by this force.

This braking force is generated in proportion to the rotational speed (peripheral speed) of the movable magnet 1, and the higher the peripheral speed, the greater the braking force. That is, since the eddy current does not occur in the braking cup 4 when the peripheral speed is zero, the braking force does not act on the movable magnet 1, and therefore the conventional mechanical hysteresis occurs in the state of the minimum driving force. Never. Further, since the hydraulic oil is not used as a means for obtaining the braking force, there is no temperature dependence due to the viscosity of the hydraulic oil, the braking performance is good, and a very small amount of hydraulic oil is injected. Eliminates difficult management.

[Effect of device]

As described above, according to the orientation sensor of the present invention,
Since a braking cup made of a non-magnetic conductive member is provided so as to surround and surround the permanent magnet,
When the permanent magnet magnet rotates, an eddy current is generated in the braking cup made of a non-magnetic conductive member, and the magnetic field generated by this eddy current brakes the permanent magnet magnet. Therefore, when the peripheral speed of the permanent magnet magnet is zero, the braking force does not act on the permanent magnet magnet, and therefore hysteresis does not occur in the state of the minimum driving force. Further, since the hydraulic oil is not used, there is no temperature dependence due to its viscosity and the braking performance is good, and it is not necessary to perform difficult management such as injecting a very small amount of hydraulic oil with an extremely low viscosity.

[Brief description of drawings]

1 is a sectional view taken along the line I-I in FIG. 2, FIG. 2 is a bottom view showing an embodiment of the orientation sensor according to the present invention, and FIG. 3 is an orientation meter constructed by using this orientation sensor. circuit diagram,
FIG. 4 is a bottom view showing a conventional direction sensor, and FIG. 5 is a bottom view.
FIG. 6 is a cross-sectional view taken along the line VV in the figure, and FIG. 6 is a hysteresis characteristic diagram when the 90 ° azimuth sensor is rotated. 1 ... Movable magnet, 1-1 ... Magnet disk, 2 '
... upper frame, 3 '... lower frame, 4 ... braking cup.

Claims (1)

[Scope of utility model registration request] 1. A direction sensor comprising a permanent magnet magnet that rotates in the direction of the earth's magnetic field. A braking cup made of a non-magnetic conductive member so as to surround and surround the permanent magnet magnet. An azimuth sensor characterized by being provided.