JP3473286B2 - Cross-coil pointer meter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pointer instrument that displays information by rotating a pointer and is suitable for use in a meter for automobiles.

[0002]

2. Description of the Related Art Conventionally, a pointer instrument has a coil wound around a rotary magnet integrated with a shaft to which a pointer is attached.
There is a so-called cross-coil type pointer instrument that displays information by rotating a rotating magnet by the action of a magnetic field generated in this coil.

[0003]

The pointer instrument, with some exceptions, is used tilted. Therefore, a load such as a pointer or a shaft is applied to the bearing. Due to this load, when the shaft is rotated, friction torque is generated in the bearing portion, and an instruction error is generated. Also, in the cross coil type pointer instrument,
In order to block the external magnetic field and to efficiently transmit the action of the magnetic field generated in the coil, a cup-shaped shield case made of a soft magnetic material is placed with its bottom surface parallel to the surface of the rotating magnet. Covers. However, this shield case is not intended to reduce the friction torque, and the instruction error due to the friction torque is not reduced.

The present invention has been made in view of the above problems, and it is an object of the present invention to reduce the indication error of the pointer instrument by reducing the friction torque generated in the bearing portion.

[0005]

In order to achieve the above object, the following technical means are adopted. In the invention according to claims 1 to 4, a shaft (3) having a pointer (2) at its tip, a rotary magnet (4) in the form of a circular plate integrally formed with the shaft (3), and a rotary magnet ( In a cross-coil type pointer measuring instrument including a bobbin (61, 62) having a built-in 4) and a coil (5) for rotating the rotating magnet (4), the rotating magnet (4) is an upper magnetic member (8). Lower magnetic member (7)
By sucking up and down in the axial direction of the shaft (3),
It is characterized in that the movement of the shaft (3) in the direction of gravity is suppressed.

As described above, the rotating magnet (4) attracts the magnetic members (7, 8) provided above and below the shaft (3) in the axial direction to suppress the movement of the shaft (3) in the direction of gravity. Therefore, the load of the pointer (2) and the shaft (3) applied to the bearings of the bobbins (61, 62) is reduced, and the friction torque can be reduced. Therefore, the instruction error generated based on the friction torque can be reduced.

According to the second aspect of the invention, the moment generated by the rotating magnet (4) attracting the upper magnetic member (8) and the rotating magnet (4) attracting the lower magnetic member (7). The moment generated by doing so is characterized in that it is balanced in such a magnitude that the moment generated by the load applied to the shaft (3) does not substantially act.

As described above, by balancing the moments generated by the rotating magnet (4) attracting the upper magnetic member (8) and the lower magnetic member (7), a force for holding the balanced moments is obtained. Works. By this force, the moment due to the load applied to the shaft (3) can be substantially prevented from acting. As a result, the same effect as in claim 1 is obtained.

In the third aspect of the present invention, one of the upper magnetic member (8) and the lower magnetic member (7) has a cup shape having a bottom surface parallel to the surface of the rotating magnet (4). The case member and the other plate member, and the upper magnetic member (8) and the lower magnetic member (7) are arranged to substantially seal the bobbins (61, 62). Is characterized by.

As described above, by substantially sealing the bobbins (61, 62) by the upper magnetic member (8) and the lower magnetic member (7), the external magnetic field can be cut off almost completely, and the coil (5) can be cut off. The magnetic field generated in the can be efficiently applied. In the invention according to claim 4, the moment generated by the rotary magnet (4) attracting the upper magnetic member (8) and the moment generated by the rotary magnet (4) attracting the lower magnetic member (7) The combined moment of the generated moments is characterized by causing the shaft (3) to act in the antigravity direction.

In this way, by raising the shaft (3) in the antigravity direction based on the action of the synthetic moment,
The moment due to the load applied to the shaft (3) can be reduced. As a result, the same effect as in claim 1 is obtained. The invention according to claim 5 is characterized in that the upper magnetic member (8) and the lower magnetic member (7) are made of a soft magnetic material.

When the rotating magnet (4) rotates due to the action of the magnetic field generated by the coil (5), a force may be applied due to the residual magnetic force in the opposite direction to the rotating direction, and the rotating movement of the rotating magnet (4) may occur. May not be done smoothly. By the way, in general, a soft magnetic material has a property of generating strong magnetism when approaching a rotating magnet, and rapidly losing its magnetism when moving away from it.
As described above, by using the soft magnetic material for the upper magnetic member (8) and the lower magnetic member (7), the residual magnetic force can be blocked and the rotating magnet (4) can be smoothly rotated.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention shown in the drawings will be described. FIG. 1 is a schematic cross-sectional view of a cross-coil pointer instrument according to an embodiment of the present invention. Further, this drawing is a view in which this pointer measuring instrument is used for a speedometer of an automobile, and is attached to an instrument panel in the vehicle while being inclined as shown in the drawing.

The structure of the pointer instrument of FIG. 1 will be described.
The basic structure of the cross-coil type pointer measuring instrument is the same as that generally known. As shown in FIG. 1, there is a gauge plate 1 provided with a velocity scale, and a pointer shaft of a pointer 2 is arranged in a hole provided in the center of the gauge plate 1, and the pointer 2 is a magnetic material shaft through this hole. It is attached to 3.
A rotor (rotating magnet) 4 is attached to the shaft 3.

The shaft 3 is held by bearing portions 61a, 62a of bobbins 61, 62 made of resin. The bobbins 61 and 62 have an upper bobbin member and a lower bobbin member, and the rotor 4 has an upper bobbin member 6
1 and the lower bobbin member 62 are contained in an internal space formed when they are fixed to each other. Further, four coils 5 are wound around the bobbins 61 and 62 around the rotor 4 in an intersecting manner. Further, a cup-shaped shield case (lower magnetic member) 7 formed of a soft magnetic material (for example, a permalloy-based material) shown in FIG. The surface and the bottom surface a of the shield case 7 are fixed in parallel. A recess 7b is formed on the outer circumference of the shield case 7, and a recess 7b is formed on the lower bobbin member 62.
And the shield case 7 is fixed to the bobbins 61 and 62.

As shown in FIG. 2 (b), a plate (upper magnetic member) 8 made of a soft magnetic material has a circular plate shape, and a hole for inserting the shaft 3 and the bearing portion 61a in the center thereof. 8a is provided. The plate 8 is arranged symmetrically with respect to the rotor 4 on the bottom surface 7 a of the shield case 7. The plate 8 is fixed to the notch 61b formed in the upper bobbin member 61 by light press fitting.

In this embodiment, the soft magnetic material is used for the shield case 7 and the plate 8 in order to make the rotation of the magnet 4 smooth. That is, the magnet 4 may receive a force due to the residual magnetic force in the opposite direction to the direction in which the magnet 4 rotates. In this case, the rotational movement of the magnet 4 may not be performed smoothly. In general, the soft magnetic material has a property of generating strong magnetism when approaching the magnet, and rapidly losing its magnetism when moving away from the magnet. Because of this property, the residual magnetic force can be blocked and the rotation of the magnet 4 can be smoothed.

A hole 7c is formed in the bottom surface 7a of the shield case 7. The coil 5 and the wiring formed on the printed board 9 are electrically connected to each other through the hole 7c. Also, the instrument panel 1 and the upper bobbin member 61 are screw 1
It is fixed at 0. A zero return spring 11 is provided near the tip of the shaft 3. The magnetic action of the rotor 4, the shield case 7, and the plate 8 in this example will be described. FIG. 3A is an explanatory diagram related to the magnetic action on the bottom surface 7a, the plate 8 and the rotor 4 of the pointer instrument in this example. As shown in FIG.
At a distance l ₁ from the shaft 3, the rotor 4 sucks the bottom surface 7a with a suction force F ₁ and the plate 8 with a suction force F ₂ . Further, the distance from the bearing portion 62a to the pointer 3 is l ₂ , and the load W ₁ applied by the pointer 2 is W _{2 the} load applied to the bearing portion 61a by this W ₁ . Here, since the shield case 7 and the plate 8 are arranged at the same distance from the rotor 4, the attraction forces F ₁ and F ₂ are equal.

FIG. 3 (b) shows the rotational moments of these forces.
It is a conceptual diagram regarding. Rotation around the point A
Is occurring. At this time, the rotation mode of left rotation
Ment FL is F₁l₁+ F₂l₁And the right rotation on the paper
Rotational moment FR is F₁l ₁+ F₂l₁+ W₁l₂so
is there. At this time, F₁l₁+ F₂l₁>> W₁l₂No
The force to hold the rotor 4 is large and
If so, the force acts to maintain this balance
Therefore, the rotation moment W₁l₂Does not work
Yes. As a result, the load W applied by the pointer 2₁And this
The movement of the shaft 3 in the direction of weight caused by this is suppressed.
You can As a result, the load W applied to the bearing portion 61a
₂Can be reduced.

In this embodiment, the suction force F ₁ ,
Since F ₂ works to maintain the rotor 4 in a balanced state, even if a force for moving the shaft 3 is applied by the vibration of the vehicle, this force can be suppressed.
The operation of the pointer instrument in this example will be described. Although not shown, a drive mechanism for driving the pointer instrument of this example is composed of a vehicle speed sensor and a drive circuit, and is connected to an ignition switch and a battery. When the ignition switch is turned on, the vehicle speed sensor detects the rotation speed of the output shaft of the vehicle transmission and generates a vehicle speed pulse. Then, the drive circuit controls the drive current to each coil 5 according to the vehicle speed pulse. Based on this drive current,
A magnetic field is generated in each coil 5.

The action of this magnetic field and the magnetic force of the rotor 4 causes the shaft 3 to rotate. When the ignition switch is turned off, the spring force of the zero return spring 11 works to return the shaft 3 to the original position. At this time, since the pointer instrument is used in a tilted state, the weight of the pointer 2 and the shaft 3 becomes the load of the bearing portions 61a and 62a (particularly the load of the bearing portion 62a). Therefore, when the shaft 3 is rotated, a friction torque proportional to the weight of the pointer 2 and the shaft 3, the radius of the shaft 3, the friction coefficient of the bearing portions 61a and 62a, and the angle of inclination is generated in the bearing portion 61a. .

In this example, since the shield case 7 and the plate 8 are formed above and below the rotor 4 in the axial direction as described above, the movement of the shaft 3 in the direction of gravity is suppressed, and the bearing portions 61a, 62a. The load on the pointer 2, the shaft 3 and the like (particularly the bearing portion 61a) is reduced. Therefore, the friction torque is reduced. Therefore, by reducing the friction torque, it is possible to reduce the instruction error generated based on the friction torque. Further, abrasion of the shaft 3 due to friction with the bearing portions 61a and 62a can be prevented. Conventionally, the shield case 7 is provided in order to shield the external magnetic field and to efficiently rotate the rotor 4 by causing the magnetic field generated in the coil 5 to act efficiently.
By providing the plate 8 and the plate 8, the above effect can be more completely exhibited. (Second Embodiment) In the present embodiment, the upper half of the plate 8 in the first embodiment is eliminated and the plate 8 has a semicircular shape. FIG. 4A shows an explanatory diagram relating to the magnetic action in this embodiment. In this case, because of the semicircular shape, the suction force F ₂ is generated only in the downward direction of the shaft 3. Therefore, as shown in FIG. 4B, the combined moment of the rotational moments in the left and right directions of the paper is a positive rotational moment F ₂ l ₁ in the leftward rotational direction, and the shaft 3 is lifted from the bearing portion 61a in the antigravity direction. Move in the direction. This allows
The load applied to the bearing portion 61a is reduced, the friction torque can be reduced, and the instruction error can be reduced. (Other Embodiments) In this example, the invention is applied to a speedometer of an automobile, but it may be applied to an engine speed meter, a water temperature meter, a fuel amount meter, etc. and other than the automobile meter.

Further, although the shield case 7 is cup-shaped in this example, it may be circular plate-shaped like the plate 8, and the plate 8 is cup-shaped so that the upper bobbin member 61 can cover it. Is also good. When the shield case 7 has a circular plate shape like the plate 8, a bobbin 61, 62 and a cylindrical member made of a soft magnetic material are formed around the bobbin 61 to block the external magnetic field as in the conventional case. The effect can be obtained.

Further, although the soft magnetic material is used in this example,
Friction torque can be reduced even with a magnetic material. Although the semicircular plate 8 is used in the second embodiment,
Not limited to this, the same effect can be obtained as long as the rotation moment in the direction of lifting the shaft 3 from the bearing portion 61a is generated. For example, in the area of the plate 8, the area above the shaft 3 is small, and the area below the shaft 3 is large.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pointer instrument according to a first embodiment.

2 (a) is a perspective view of a shield case 7 and FIG. 2 (b) is a perspective view of a plate 8 in the pointer instrument of FIG.

3A is an explanatory diagram showing a magnetic action in the pointer instrument of FIG. 1, and FIG. 3B is a conceptual diagram of a rotation moment in FIG. 3A.

FIG. 4 (a) is an explanatory diagram showing a magnetic action in the pointer instrument of the second embodiment, and FIG. 4 (b) is a conceptual diagram of a rotational moment in (a).

[Explanation of symbols]

2 ... pointer, 3 ... shaft, 4 ... rotor, 5 ... coil, 7
... shield case, 8 ... plate, 61 ... upper bobbin member, 61a ... bearing portion, 62 ... lower bobbin member, 62a
… Bearings.

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01D 11/02 G01R 5/16 G12B 11/02

Claims (5)

(57) [Claims] 1. A rotating shaft (3), a pointer (2) provided at the tip of the shaft (3), and a rotary magnet (4) integrally formed with the shaft (3).
A bobbin (61, 62) that holds the shaft (3) rotatably and has the rotating magnet (4) built-in, and the rotating magnet () that is wound around the outer circumference of the bobbin (61, 62). 4) a coil (5) for rotating, and an upper magnetic member (8) and a lower magnetic member (7) in which the rotating magnet (4) is provided above and below in the axial direction of the shaft (3). Then, the rotating magnet (4) attracts the upper magnetic member (8) and the lower magnetic member (7) vertically in the axial direction of the shaft (3) to move the shaft (3) in the direction of gravity. A cross-coil type pointer instrument characterized in that it is controlled. 2. A moment generated by the rotating magnet (4) attracting the upper magnetic member (8) and a moment generated by the rotating magnet (4) attracting the lower magnetic member (7). The moment to be applied is the shaft (3)
2. The cross-coil pointer instrument according to claim 1, wherein the cross-coil pointer instrument is balanced such that the moment generated by the load applied to it is not substantially applied. 3. One of the upper magnetic member (8) and the lower magnetic member (7) is a cup-shaped case member having a bottom surface parallel to the surface of the rotating magnet (4). The other is configured in a plate shape and is arranged so as to substantially seal the bobbins (61, 62) by the upper magnetic member (8) and the lower magnetic member (7). The cross coil type pointer instrument according to claim 1 or 2. 4. A moment generated by the rotating magnet (4) attracting the upper magnetic member (8) and a moment generated by the rotating magnet (4) attracting the lower magnetic member (7). The cross-coil type pointer instrument according to claim 1, wherein a combined moment of the moments that act causes the shaft (3) to act in an antigravity direction. 5. The cross-coil type according to claim 1, wherein the upper magnetic member (8) and the lower magnetic member (7) are made of a soft magnetic material. Pointer instrument.