JP2000035445A - Cross-coil type indicating instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the clearance between both bearings supporting a hand spindle as wide as possible while ensuring the flattening by devising a spatial position relationship of the hand spindle to a housing in a cross-coil type indicating instrument. SOLUTION: A lower bobbin 10b of a bobbin 10 has a small-diametrical cylinder 12 extending downward from the middle of its bottom wall, and this small-diametrical cylinder 12 passes through a hole 21a formed in the middle of a bottom wall 21 of a magnetic shield casing 20 so that it protrudes downward. Also, this small-diametrical cylinder 12 has a lower bearing 12a at its lower end: the lower bearing 12a is positioned downward of the bottom wall 21 of the magnetic shield casing 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cross-coil indicating instrument.

[0002]

2. Description of the Related Art Conventionally, a cross-coil type indicating instrument is shown in FIG.
As shown in (a), a hollow bobbin 1 is provided.
The bobbin 1 includes an upper bobbin member 2 and a lower bobbin member 3
The bobbin 1 is accommodated in the magnetic shield casing 4 from the lower bobbin member 3.

On the outer wall of the bobbin 1, a double crossing coil 5 is provided.
Are wound around each other, and a pointer shaft 6 is coaxially inserted into the bobbin 1. And the pointer shaft 6
The upper and lower bearings 2 of the bobbin 1
a, 3a, it is rotatably supported. here,
The lower bearing portion 3a is a lower end 3 of the terminal portion of the bobbin 1.
8 (a) is located higher than b. Further, the disc-shaped magnet 7 is placed inside the hollow portion of the bobbin 1.
The pointer 8 is supported by a pointer shaft 6, and a pointer 8 is supported at the tip of the pointer shaft 6 at its base.

[0004]

In recent years, there has been a demand for a thinned cross-coil indicating instrument. In response to this, the axial distance L between the two bearing portions 2a, 3a is
As shown in FIG. 8 (b), when trying to shorten the cross-coil indicating instrument by shortening it, the two bearings 2a, 3a
The friction torque generated between the shaft and the pointer shaft 6 is larger than that in the case of FIG. As a result, there arises a problem that the indicated hysteresis error included in the indicated value of the pointer supported on the distal end of the pointer shaft 6 increases.

To address this, it is conceivable to increase the magnetic force of the magnet 7 or to increase the drive current flowing through the two crossing coils. However, a problem occurs in that the cost is increased. On the other hand, the present inventor has proposed that both bearings 2
The relationship between the friction torque generated between the a and 3a and the pointer shaft 6 and the axial distance L between the bearing portions 2a and 3a was examined.

The cross-coil indicating instrument shown in FIG.
When the model is expressed as shown in FIG. 5, the frictional load W1 generated between the upper bearing 2a and the pointer shaft 6 and the lower bearing 2
The friction load W2 generated between the pointer b and the pointer shaft 6 is expressed by the following equations 1 and 2, respectively.

[0007]

(Equation 1)

[0008]

(Equation 2) Here, in each of the equations (1) and (2), L represents the axial distance between the bearings 2a and 3a as described above, and Ls
As shown in FIG. 7, the lower bearing 3a and the pointer shaft 6
Represents the distance from the center of gravity of Lm is the lower bearing 3a
And the distance between the center of gravity of the magnet 7. Lp represents an interval between the upper bearing 2a and the center of gravity of the pointer 8. θ
Represents the angle between the pointer shaft 6 and the horizontal direction.

Wm represents the weight of the magnet 7,
Ws represents the weight of the pointer shaft 6, and Wp represents the weight of the pointer 8. Therefore, the friction torque F1 generated on the upper bearing portion 2a based on the friction load W1 and the friction torque F2 generated on the lower bearing portion 2b based on the friction load W2 are expressed by the following equations 3 and 4, respectively. .

[0010]

## EQU3 ## F1 = W1.multidot.r1

[0011]

In the equations (3) and (4), μ represents a friction coefficient between the upper bearing portion 2a or the lower bearing portion 3a and the pointer shaft 6. R1 represents the radius of an intermediate portion of the pointer shaft 6 located in the upper bearing 2a.
Reference numeral 2 denotes a radius of an intermediate portion of the pointer shaft 6 located in the lower bearing portion 3a.

When the above equations (1) to (4) are examined, the friction torques F1 and F2 are substantially determined by the axial distance L between the two bearing portions 2a and 3a. Was found to be almost inversely proportional to Therefore,
In view of the above, the present invention, in the cross-coil type indicator, devises the spatial positional relationship of the pointer shaft with respect to the housing, and secures flattening between the two bearing portions supporting the pointer shaft. The purpose is to make the interval as wide as possible.

[0013]

In order to solve the above-mentioned problems, according to the first, second and third aspects of the present invention, the cross-coil type indicating instrument is a resinous housing, which has an upper wall side in the axial direction and a resin housing. A resin housing (10) provided with both bearing portions (11a, 12a) coaxially and spaced apart from each other on an axial bottom wall side, and a double crossing coil wound around an outer wall of the housing (10). 40) and a pointer shaft rotatably supported in the housing, which is rotatably supported by one of the bearing portions (11a) at an intermediate portion (51) on the distal end side thereof, and has a lower end portion ( The pointer shaft (50) rotatably supported by the other bearing portion (12a) at 52).
A disk-shaped magnet (70) supported at an intermediate portion of the pointer shaft in the housing and rotating together with the pointer shaft; and a pointer supported by a distal end extending from the pointer shaft through the dial (60). It has hands (80, 90) that rotate in conjunction with the shaft and indicate and display instructions on the dial, and a magnetic shield casing (20) that houses the housing from its bottom wall.

The lower bearing of the housing is provided with a through hole (21) formed in the bottom wall of the magnetic shield casing.
a) and projecting outward. Thereby, even if the axial length of the housing is shortened, the axial interval between both bearing portions can be made as wide as possible. Therefore, the friction torque of the upper intermediate portion of the pointer shaft with respect to the bearing portion and the friction torque of the lower end portion of the pointer shaft with respect to the bearing portion can be made as small as possible. As a result, the hysteresis instruction error of the pointer based on the friction torque can be minimized. Further flattening in the axial direction of the cross-coil indicating instrument can be realized while suppressing the distance to the minimum.

Here, according to the invention described in claim 2,
If the upper bearing is located on the upper end surface in the same plane as the upper wall of the housing or below it, the bearing does not protrude upward from the upper wall of the housing. For this reason, the operation and effect of the invention described in claim 1 can be achieved while further ensuring the flattening of the indicating instrument.

According to the third aspect of the present invention, the upper bearing extends from the upper wall of the housing to the dial to the dead space formed around the pointer shaft. As described above, the dead space normally formed around the pointer shaft is effectively utilized, and the upper bearing portion is extended into this dead space. The interval between the parts can be further widened, and as a result, the function and effect of the invention described in claim 1 can be further improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cross-coil type indicating instrument according to the present invention will be described below with reference to FIGS. The cross-coil indicating instrument is used as an instrument for various vehicles such as a vehicle speed meter or an instrument used for general industry. As shown in FIG. 1, the crossed coil type indicating instrument has a hollow resin bobbin 1 as a housing.
0, and the bobbin 10 is
0a and the lower bobbin member 10b. The bobbin 10 is connected to the lower bobbin member 10b.
From the side, it is housed in a magnetic shield casing 20 having a U-shaped cross section, and is fixed to a circuit board 30 together with the magnetic shield casing 20.

Here, the upper bobbin 10a has a small-diameter cylindrical portion 11 extending upward from the center of the upper wall, and the small-diameter cylindrical portion 11 has an upper bearing 11a at its upper end.
have. The upper end surface of the upper bearing portion 11a is located in the same plane as the upper end surface of each flange 14 of the bobbin 10. On the other hand, the lower bobbin 10b includes a small-diameter cylindrical portion 12 extending downward from the center of the bottom wall, and the small-diameter cylindrical portion 12 is provided on the bottom wall 21 of the magnetic shield casing 20.
Through the through hole 21a formed in the center of the circuit board 30 and the through hole 31 of the circuit board 30, and protrudes downward. The small-diameter cylindrical portion 12 has a lower bearing portion 12a at its lower end.
The lower bearing portion 12 a is located below the bottom wall 21 of the magnetic shield casing 20.

In the present embodiment, the magnetic shield casing 20 forms a magnetic circuit together with a magnet 70 described later.
Is formed by molding a soft magnetic material such as permalloy or Ni-Fe alloy by pressing or the like. The outer wall of the large-diameter hollow portion 13 of the bobbin 10 has
0 are wound so as to be positioned in a cross shape with respect to each other, and both cross coils 40 are driven by a drive circuit (not shown) to generate an electromagnetic force.

The pointer shaft 50 is coaxially inserted into the bobbin 10. The pointer shaft 50 is coaxially rotatable at its upper intermediate portion by the bearing 11a of the upper bobbin member 10a. The lower bobbin member 10b is supported at its lower end 52 coaxially and rotatably by the bearing 12a of the lower bobbin member 10b. In addition, the pointer shaft 50 is provided at the tip thereof with the through hole 6 of the dial 60 from the bobbin 10.
1 and extends upward. The dial 60
Are supported by the flanges 14 of the bobbin 10 via appropriate members (not shown).

The magnet 70 is coaxially supported in the large-diameter hollow portion 13 of the bobbin 10 at an intermediate portion of the pointer shaft 50, and the magnet 70 vectorizes each electromagnetic force from the both cross coils 40. The pointer shaft 50 is rotated by receiving the combined electromagnetic force and rotating. The pointer 80 is supported at its base 81 by the distal end of the pointer shaft 50.
Numeral 0 rotates in conjunction with the pointer shaft 50 and indicates an instruction on the dial 60.

In the present embodiment configured as described above, as described above, the upper end surface of the upper bearing portion 11a of the bobbin 10 is located in the same plane as the upper end surface of each flange 14 of the bobbin 10, while Lower bearing 1 of bobbin 10
2 a is located below the bottom wall 21 of the magnetic shield casing 20. For this reason, even if the axial lengths of the bobbin 10 and the magnetic shield casing 20 are reduced, the bobbin 1
The axial distance between the 0 upper bearing portion 11a and the lower bearing portion 12a can be made as wide as possible.

Therefore, the friction torque between the upper intermediate portion 51 of the pointer shaft 50 and the upper bearing portion 11a and the pointer shaft 50
The friction torque of the lower end portion 52 with respect to the lower bearing portion 12a can be reduced as much as possible. As a result, it is possible to further flatten the cross coil type indicating instrument in the axial direction while minimizing the hysteresis indicating error of the pointer 80 due to the friction torque.

Incidentally, in the cross-coil indicating instrument of the present embodiment, how the friction load and the total friction load applied to the upper bearing portion and the lower bearing portion of the bobbin are reduced as compared with the conventional cross-coil indicating instrument. As a result, data as shown in FIG. 2 was obtained. Here, A on the horizontal axis corresponds to the axial thickness of the conventional cross-coil type indicator (the distance between the end face of the upper bearing portion of the bobbin (that is, the flange of the bobbin) and the outer surface of the bottom wall of the magnetic shield casing). ) Is set to 20 mm. B on the horizontal axis represents the case where the thickness in the axial direction of the conventional cross-coil indicating instrument is 10 mm. However, in A and B, the lower bearing of the bobbin is located inside the magnetic shield casing.

Further, C to F on the horizontal axis represent the case where the axial thickness of the crossed coil type indicator of this embodiment is 10 mm. However, in C, D, E and F, the protruding length (hereinafter referred to as Lt) of the outer end surface of the lower bearing portion 12a (corresponding to the lower end surface of the pointer shaft 50) from the outer surface of the bottom wall 21 of the magnetic shield casing 20. Is 2mm,
They are 4 mm, 6 mm and 8 mm (see FIG. 3).

Symbol G is a graph showing the relationship between the total frictional load and A to F, symbol H is a graph showing the relationship between the frictional load of the upper bearing and A to F, and symbol I is shown. 7 is a graph showing the relationship between the friction load of the lower bearing portion and A to F. In addition, each specification of A and B of the conventional cross coil type indicating instrument and the friction load in that case, and each specification of C to F of the cross coil type indicating instrument of this embodiment and the friction load in that case are , As shown in FIG. Here, the friction load means the upper bearing portion 11a
And the respective friction loads of the lower bearing portion 12a or the total friction load thereof.

According to FIG. 2, in the conventional cross-coil type indicating instrument, as can be seen from the graphs G, H, and I, B has a lower total friction load and lower side than the case of A. Each friction load of the bearing portion and the upper bearing portion is increasing.
Therefore, as shown in B, with the protrusion length Lt = 0, simply
It can be seen that merely reducing the axial thickness of the cross-coil indicating instrument causes an increase in the friction torque acting on the bearing portion, and therefore increases the hysteresis indicating error of the pointer.

On the other hand, in the cross-coil indicating instrument of the present embodiment, as Lt is sequentially increased as shown by C to F, the total friction load, the respective friction loads of the lower bearing portion and the upper bearing portion are sequentially increased. is decreasing. Therefore, the protrusion length Lt
By reducing the distance L between the upper bearing portion and the lower bearing portion by reducing the thickness of the cross-coil indicating instrument in the axial direction, a reduction in friction torque acting on the bearing portion can be secured. Therefore, the hysteresis indicating error of the pointer is Lt
It can be seen that it greatly decreases with the increase of.

In the above embodiment, the bobbin 1
The upper end surface of the upper bearing portion 11a is located in the same plane as the upper end surface of each flange 14 of the bobbin 10. However, both bearings for supporting the pointer shaft 50 while ensuring the flatness of the indicating instrument. If the interval between the portions 11a and 12a can be appropriately widened, the upper end surface of the bearing portion 11a is located inside the upper end surface of each flange 14 of the bobbin 10 (in FIG. 1, lower than the upper end surface of each flange 14). Side).

FIG. 4 shows a first modification of the above embodiment. In the first modified example, the light emitting pointer 90 is employed in place of the pointer 80 described in the above embodiment, and the light guide plate 100 is formed by the dial 60 and the upper bobbin member 10a described in the above embodiment. It is sandwiched between. Also, unlike the above embodiment, the upper bearing 11a of the upper bobbin member 10a is positioned higher than the upper end of each flange 14 of the bobbin 10, as shown in FIG. , Extending upward.

The light emitting pointer 90 has a pointer main body 90a and a light-shielding cap 90b. The pointer body 90a
The base 91 is supported by the tip of the pointer shaft 50. The pointer main body 90 a receives light from the light guide plate 100 through the base 91 and emits light as described later, and emits light on the dial 60. Display instructions. The cap 90b is attached to the base 91 of the light emitting pointer 90 so as to cover the base 91 from outside and from above.
Blocks light emitted upward from the base 91. In addition,
The cap 90b is positioned so as to coaxially cover the through hole 61 of the dial 60 from above at the lower end opening.

The light guide plate 100 is provided with a through hole 101 coaxially inserted into an upper intermediate portion of the pointer shaft 50. In the through hole 101, the upper bearing 11a of the upper bobbin member 10a extends. Is out. Here, the light guide plate 100
Is located above the upper end surface of the upper bearing portion 11a. The upper end surface of the upper bearing 11a may be located, for example, in the through hole 61 of the dial 60 above the upper surface of the light guide plate 100.

The through hole 101 of the light guide plate 100 is
As shown in FIG. 4, the through-hole portion 1 is formed in a truncated conical shape so as to diverge downward.
01 reflects upwardly light introduced from a light source (not shown) through its end surface into the light guide plate 100,
The light enters the pointer main body 90a from the base 91 through the through hole 61 of the dial 60. Other configurations are the same as in the above embodiment.

In the first modified example configured as described above, the lower bearing portion 12a of the bobbin 10 is located below the bottom wall 21 of the magnetic shield casing 20, as in the above embodiment. On the other hand, the upper bearing 11a of the bobbin 10 extends into the through hole 101 of the light guide plate 100 located above each flange 14 of the bobbin 10. However, the upper bearing 11a is
The light guide plate 100 extends only into the dead space generated in the through hole 101 because of the adoption of the light guide plate 100, and does not hinder the flattening of the indicating instrument employing the light guide plate 100.

As a result, in the indicating instrument employing the light guide plate 100, the dead space generated in the through-hole portion 101 of the light guide plate 100 is effectively used, so that the indicator is properly flattened and Both bearings 11a, 12a
Can be further widened, and the operation and effect described in the above embodiment can be further improved. 5 and 6
Shows a second modification of the above embodiment.

In the second modification, the upper bearing 11a of the bobbin 10 described in the above embodiment is different from the above embodiment, as shown in FIG. And extends coaxially upward through a through-hole portion 61 of the dial 60 located at the center position. The upper bearing portion 11a does not have to extend upward through the through hole 61 of the dial 60, and the upper end surface of the bearing portion 11a is, for example, the upper end surface of the through hole portion 61 and the two flanges 14a. May be located between the upper end surface of the lens.

However, the pointer 80 described in the above embodiment is used.
As shown in FIG. 6, the base portion 81 is formed wide so that the base portion 81 coaxially covers the through-hole portion 61 of the dial 60 from above. For this reason, the upper end surface of the upper bearing 11a is not seen from above through the base 81 of the pointer 80. Other configurations are the same as in the above embodiment.

In the second modified example configured as described above, the lower bearing portion 12a of the bobbin 10 is located below the bottom wall 21 of the magnetic shield casing 20, as in the above embodiment. On the other hand, the upper bearing 11a of the bobbin 10 extends upward through the through-hole 61 of the dial 60 located above each flange 14 of the bobbin 10. However, the upper bearing portion 11a is
In order to extend 0 upward, it merely extends into the dead space of the through-hole portion 61 formed in the dial 60,
It does not prevent the indicator from flattening.

As a result, as described above, by effectively utilizing the dead space generated in the through-hole portion 61 of the dial 60, the flatness of the indicating instrument can be properly ensured, and the two bearing portions 11a, 12a can be secured. Can be further widened, and the operation and effect described in the above embodiment can be further improved. In the second modified example, the appropriate member described in the above embodiment may be a light guide plate or the like.

In practicing the present invention, the bobbin 10
The projecting length of the lower bearing portion 12a from the bottom wall 21 of the magnetic shield casing 20 may be appropriately changed as necessary.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a cross-coil type indicating instrument according to the present invention.

FIG. 2 shows how the friction load and the total friction load applied to both bearing portions change when the specifications of the conventional cross-coil indicating instrument and the specifications of the cross-coil indicating instrument of the above embodiment are changed. It is a graph shown.

FIG. 3 is a table showing the specifications of a conventional cross-coil indicator for obtaining the measurement data of FIG. 2 and the specifications of the cross-coil indicator in the embodiment.

FIG. 4 is a schematic sectional view showing a first modification of the embodiment.

FIG. 5 is a schematic sectional view showing a second modification of the embodiment.

FIG. 6 is a plan view showing the second modification.

FIG. 7 is a diagram modeling the cross-coil indicating instrument of FIG. 8 (a).

8 (a) is a schematic cross-sectional view of a conventional cross-coil indicating instrument, and FIG. 8 (b) shows the cross-coil indicating instrument of FIG. 8 (a) with the distance between both bearing portions shortened. It is an outline sectional view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Bobbin, 11a ... Upper bearing part, 12a ... Lower bearing part, 20 ... Magnetic shield casing, 21 ... Bottom wall,
21a: through hole, 40: cross coil, 50: pointer shaft,
52: lower end, 70: magnet, 80: pointer, 90 ...
Light emission pointer.

Claims (3)

[Claims] 1. A resin housing having two bearings (11a, 12a) coaxially and spaced apart from each other on an axially upper wall side and an axially bottom wall side thereof. (10) and a double crossing coil (4) wound around the outer wall of the housing.
0), a pointer shaft rotatably supported in the housing, and rotatably supported by one of the bearing portions (11a) at an intermediate portion (51) at the distal end thereof, and a lower end thereof. A pointer shaft (50) rotatably supported by the other bearing portion (12a) at a portion (52); and a pivot supported together with the pointer shaft while being supported by an intermediate portion of the pointer shaft within the housing. Disc-shaped magnet (70)
Pointers (80, 90) supported by a distal end extending from the pointer shaft through the dial (60) and rotated in conjunction with the pointer shaft to indicate and display on the dial; In a cross-coil type indicator including a magnetic shield casing (20) for housing a housing from a bottom wall thereof, the lower bearing of the housing has a through hole (21a) provided in a bottom wall of the magnetic shield casing. A cross-coil type indicating instrument characterized by being positioned so as to protrude outward from the same. 2. The upper bearing portion has an upper end surface,
The cross-coil indicating instrument according to claim 1, wherein the indicating instrument is located in the same plane as the upper wall of the housing or below the same. 3. The intersection according to claim 1, wherein the upper bearing portion extends from a top wall of the housing to the dial to a dead space formed around the pointer shaft. Coil type indicating instrument.