JP2789756B2 - Moving magnet type analog indicating instrument - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an analog indicating instrument, and more particularly to a movable magnet type analog indicating instrument such as a cross-coil indicating instrument.

(Prior Art) Conventionally, in this type of movable magnet type analog indicating instrument, as shown in, for example, Japanese Utility Model Publication No. 56-55655, a pointer shaft is rotatably coaxially rotatable in a cylindrical bobbin. An electromagnetic coil is wound around the outer wall of the bobbin, and a rotating magnet made of a disk-shaped permanent magnet is coaxially supported at an intermediate portion of the pointer shaft in the bobbin, and a character is formed from the bobbin. A pointer is pivotally supported at the tip of the pointer shaft extending through the center of the plate, and a disc-shaped permanent magnet for return to zero is fitted in a circular recess formed in the outer surface of the bottom wall of the bobbin. Then, the rotating magnet and the pointer shaft rotate in response to the combined electromagnetic force generated from the electromagnetic coil based on the inflow current corresponding to the analog input, and the analog input is instructed by the pointer, and the analog input becomes zero. When the rotating magnet is the magnetomotive force of the return-to-zero permanent magnet. Related at and returns to the original rotational position of are then returned to zero indication position the pointer over the pointer shaft.

(Problems to be Solved by the Invention) In such a configuration, the above-described permanent magnet for zero return is usually formed of a synthetic resin magnetic material such as a synthetic rubber magnetic material. A magnet is provided for preventing the bottom wall of the bobbin from being detached from the concave portion.
It is fitted into the recess by press fitting. Therefore, the permanent magnet for zero return is accommodated in the concave portion from the outer peripheral surface toward the central portion so as to be compressed by the inner peripheral surface of the concave portion. For this reason, a distortion such as the central portion of the permanent magnet for resetting protruding outward occurs, and as a result, an error occurs in a magnetic relative position of the permanent magnet for resetting with respect to the rotary magnet, and an error occurs. Return to the original rotation position, that is, the return of the pointer to the zero pointing position becomes unstable, resulting in a decrease in the zero pointing return accuracy.

Therefore, in order to cope with such a problem, the present invention intends to always return the indicated value to the original indicated value accurately with no input in the movable magnet type analog indicating instrument.

(Means for Solving the Problems) In order to solve such problems, the structural features of the present invention include a rotating shaft rotatably supported coaxially in a cylindrical bobbin and a bobbin wound around the bobbin. An electromagnetic coil that generates an electromagnetic force according to the inflow current according to the analog input, and a movable magnet that includes a permanent magnet that is coaxially fixed to the rotating shaft in the bobbin and that rotates according to the electromagnetic force, Instruction means for instructing the analog input in accordance with the rotation of the rotating shaft accompanying the rotation of the movable magnet, and return means for returning the movable magnet to the original rotation position when the electromagnetic force disappears. In the analog indicating instrument, the return means includes an annular recess formed in an axial outer wall portion of the bobbin necessary for returning the movable magnet to the original rotation position, and an annular fixing member made of elastic permanent magnet material. And a magnet The fixed magnet is fixed in the recess so that the hollow portion is fitted into the central projection of the recess by press fitting, and the outer peripheral portion is opposed to the inner peripheral portion of the recess via an annular gap. That is to be done.

(Effects) In the present invention configured as described above, the hollow portion of the fixed magnet fixed in the annular recess of the bobbin is fitted into the central projection of the annular recess by press fitting, and Since the outer peripheral portion of the fixed magnet is opposed to the inner peripheral portion of the annular recess through an annular gap, the hollow portion of the fixed magnet spreads uniformly in the radial direction, and the outer peripheral portion of the fixed magnet has the concave portion. Is maintained in a non-contact state with the inner peripheral portion of. Therefore, the fixed magnet does not protrude outward,
It exists in the recess while maintaining its substantially original shape. As a result, no error occurs in the magnetic relative position between the fixed magnet and the rotating magnet. Therefore, the return of the movable magnet and the rotating shaft to the respective original rotating positions can always be accurately achieved in a stable state.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-coil analog indicating instrument to which the present invention is applied. This analog indicating instrument has a substantially cylindrical casing 10, and this casing 10 is formed by coaxially fitting a pair of casing members 10A and 10B. In this casing 10, a pointer shaft 20 has its proximal end 21 fitted into the central cylindrical portion 11 of the casing member 10A via a steel ball 11a, and its distal end 22 attached to the central cylindrical portion of the casing member 10B. It is fitted in the part 12 and is rotatably mounted coaxially. In the hollow portion 13 of the casing 10, a columnar permanent magnet 30 made of a synthetic resin magnetic material is coaxially supported by an intermediate portion of the pointer shaft 20. Note that silicone oil is sealed in the hollow portion 13 of the casing 10.

The casing 10 also serves as a bobbin, and a pair of electromagnetic coils 40 and 50 are wound around the outer wall of the casing 10 in a crossed manner. The respective electromagnetic coils 40, 50 are supplied with respective currents corresponding to the analog inputs through the respective inflow terminals 41, 51 to generate a combined electromagnetic force. This means that the permanent magnet 30 rotates by an angle corresponding to the analog input in accordance with the combined electromagnetic force of the magnetomotive force from each of the electromagnetic coils 40 and 50 and the magnetomotive force of the permanent magnet 60 described later. means.

Next, the configuration of the main part of the present invention will be described. An annular recess 16 is formed in the outer wall 15 on one side of the casing 10, and the recess 16 has a circular shape made of a synthetic rubber magnetic material. An annular zero-return permanent magnet 60 is housed by coaxially fitting the hollow portion 61 into the cylindrical central portion 16a of the recess 16 by press fitting. In such a case, the inner diameter of the permanent magnet 60 is
, And the outer diameter of the permanent magnet 60 is smaller than the inner diameter of the recess 16. It should be noted that a scale plate (not shown) is attached to the casing member 10B so that the leading end of the pointer shaft 20 extends coaxially outward through the central portion thereof. A pointer (not shown) is pivotally supported at the tip of the pointer shaft 20 to indicate an analog input.

In the present embodiment configured as described above, in a state where power is supplied to the analog indicating instrument, the two electromagnetic coils 40 and 50 are
When each current corresponding to the analog input is supplied and a combined electromagnetic force is generated, the permanent magnet 30
The pointer rotates in accordance with the relationship between the combined electromagnetic force of 40 and 50 and the magnetomotive force of the permanent magnet 60, whereby the pointer shaft 20 rotates and the pointer indicates analog input.

In this state, when the analog input is lost and the combined electromagnetic force from the two electromagnetic coils 40 and 50 disappears, the permanent magnet 30 rotates together with the pointer shaft 20 in accordance with the relationship between the magnetomotive force and the magnetomotive force of the permanent magnet 60. To return to the original rotational position, and the pointer indicates the zero indicated value. In such a case, as described above, the permanent magnet stored in the recess 16 of the casing 10
The hollow portion 61 of the recess 60 is coaxially fitted into the cylindrical central portion 16a of the recess 16 by press-fitting, and the outer diameter of the permanent magnet 60 is
Since it is slightly smaller than the inside diameter of 16
The hollow part 61 of the permanent magnet spreads evenly in the radial direction
The outer peripheral portion of 60 is maintained in a non-contact state with the inner peripheral surface portion of recess 16. Therefore, the permanent magnet 60 is housed in the recess 16 while maintaining its original shape without protruding outward. As a result, no error occurs in the magnetic relative position between the permanent magnet 60 and the permanent magnet 30. Therefore, the return of the permanent magnet 30 and the pointer shaft 20 to each of the original rotational positions can always be accurately achieved without becoming unstable.

In implementing the present invention, as described in the above embodiment, the annular recess 16 is not limited to a single one, but a plurality of recesses 16,. Perforations may be made at equal angular intervals along the circumferential direction. In such a case, the permanent magnet 60 is selectively fitted into any of the plurality of recesses 16,. be able to. This means that the degree of freedom of the mounting position of the permanent magnet 60 is increased. Therefore, the original return position of the pointer can be freely selected.

Further, in practicing the present invention, the present invention is not limited to an analog pointer instrument provided with a pointer, but may be applied to an analog indicator instrument of a type in which a steering angle is indicated by a turning plate, such as a vehicle steering angle indicating instrument. You may apply and implement this invention.

[Brief description of the drawings]

FIG. 1 is a partially broken side view showing an embodiment of the present invention,
2 is a front view of the same. Explanation of reference numerals 10 …… Casing, 15 …… one side outer wall, 16 …… Recess, 16a
…… Cylindrical center part, 20 …… Pointer shaft, 30,60 …… Permanent magnet, 40,50 …… Electromagnetic coil.

Claims (1)

(57) [Claims] A rotary shaft rotatably supported coaxially in a cylindrical bobbin; an electromagnetic coil wound around the bobbin to generate an electromagnetic force according to an inflow current according to an analog input; A movable magnet consisting of a permanent magnet fixed coaxially to the rotating shaft in the bobbin and rotating in accordance with the electromagnetic force; and An analog indicating instrument comprising: an instructing means for instructing an analog input; and a return means for returning the movable magnet to the original rotational position when the electromagnetic force disappears, wherein the return means moves the movable magnet to the original rotational position. And an annular recess formed in the axial outer wall portion of the bobbin necessary for returning the bobbin, and an annular fixed magnet made of a resilient permanent magnet material. Press fit into the central projection of the Moni, the outer peripheral portion so as to face via the annular gap to the inner peripheral portion of the recess, movable magnet type analog indicating instrument, characterized in that it has to be fixed in said recess.