JPS5932930Y2 - Mounting structure of cross-wire type instrument - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a cross-wire type meter used as a tachometer or speedometer for vehicles such as automobiles and motorcycles, and ships.

[Conventional technology]

A crossed wire ring type instrument having at least a multi-phase crossed coil that generates a composite magnetic field whose magnetic field direction changes in accordance with changes in the measured quantity, and a rotating magnet under the action of the magnetic field of this coil is known, for example, from the Utility Model No. 53 It is disclosed in the publication No.-62380.

That is, as shown in FIG.
It consists of a meter body 2 housed in a case 3 and a circuit board 5 on which electronic components 4 are arranged.

The instrument body 2 includes a bobbin 23 made of synthetic resin and containing a rotating shaft with a pointer attached thereto and a fixed rotating magnet (not shown), and wires wound in a perpendicular manner to surround the bobbin 23. It is separated from the two-phase coils 21 and 22.

The case 3 is made of iron and has a U-shaped cross section with an open front, and protects the instrument body 2 from the influence of surrounding magnetic fields.

The electronic component 4 consists of a resistor 41, a transistor 42, etc., which applies a signal, such as a voltage, to the coil 21, 22 in response to a change in the measured quantity, and a heat sink 43 made of, for example, aluminum, which has a good heat dissipation effect, as a countermeasure against the heat of the transistor 42. The case 3 is also soldered onto a hard circuit board 5 such as a Bakelite board or a glass epoxy board.
The instrument body 2 stored in the instrument body 2 is placed thereon, and the instrument body 2 is mounted by fixing it with bolts 6 and nuts 7.

In such a configuration, the coils 21 and 22'X$4I
Coil 2 that applies a voltage that changes according to changes in I quantity
A composite magnetic field is generated by 1.22, and the rotating magnet in the bobbin 23 is oriented in the direction of the composite magnetic field, and the rotating shaft rotates.Therefore, the pointer rotates and indicates the measured value in correspondence with the dial. It is supposed to be done.

[Problem that the invention attempts to solve]

This type of instrument requires a large amount of coils 21 and 22 to be wound around the bobbin 23, and the instrument is thicker and taller than other electric instruments such as moving coil instruments and moving iron instruments. In order to solve this problem, it is possible to create a bobbin 3 with a smaller thickness and larger winding surface area, but it is limited by the height of the heat sink 43 and it is difficult to make the instrument 1 thin There was a limit.

That is, the surface area of the heat dissipation plate 43 is determined according to the transistor 42 that requires heat dissipation measures, but in order to reduce the height, the width must be increased;
Since other electronic components 4 are densely arranged on the circuit board 5, it is difficult to secure a sufficiently large space exclusively for the heat sink 43, and therefore there is a limit to reducing the height of the heat sink 43. However, it was difficult to make the instrument 1 thinner.

[Means for solving problems]

This invention aims to solve the problems of the conventional example, and consists of a bobbin with a built-in rotating magnet fixed to a rotating shaft on which a pointer is attached, and a bobbin wound with intersecting coils. In the cross wire type meter, which is composed of a case for housing the meter body, and a circuit board on which electronic components for applying signals to the meter body are arranged, a cutout having approximately the same shape as the outer circumferential shape of the case is provided. A cutout is provided, and the case is fitted into the cutout, and the circuit board is arranged so as to be located in the middle part of the case in the thickness direction, and a base that comes into contact with the upper surface of the circuit board and an upper half of the case are arranged. a metal heat sink for electronic components, which is integrally provided with a side wall portion that covers the upper end of the case and a locking portion that holds the upper end of the case; a base portion that abuts the lower surface of the circuit board; and a lower half portion of the case. The case and the circuit board are sandwiched and held in a sandwich-like manner by a synthetic resin holding member integrally provided with a covering side wall portion and a locking portion for holding the lower end of the case.

〔Example〕

Figures 2 and 3 show examples of the cross-ring type meter according to this invention, and the same or equivalent parts as in the conventional example in Figure 1 are given the same reference numerals, and detailed explanation thereof will be omitted. .

The case 3 that houses the instrument body 2 has a recess 3a formed in the bottom surface, which is the lower end.

The circuit board 5 is formed with a notch 5a having substantially the same shape as the outer circumferential shape of the case 3, and the case 3 is fitted into the notch 5a and is located at the middle part of the case 3 in the thickness direction. It is arranged like this.

The heat sink 43 is made of aluminum and integrally has a flange-shaped base 43a, a cylindrical side wall 43b, and a locking part 43c.The base 43a is in surface contact with the top surface of the circuit board 5, and the side wall 43b covers the upper half of the case 3, and the upper end of the side wall portion 43b is bent radially inward to form a locking portion 43c that holds the upper end of the case 3.

The holding member 8 is made of synthetic resin and integrally has a flange-shaped base 8a, a cylindrical side wall 8b, and a locking part 8c.The base 8a is in surface contact with the lower surface of the circuit board 5, and the side wall The part 8b covers the lower half of the case 3, and the claw-like locking part 8c formed at the lower end of the side wall part 8b engages the recess 3 of the case 3.
a is held in contact with it.

Then, the base 43a of the heat sink 43, the circuit board 5, and the base 8a of the holding member 8 are fixed together using synthetic resin bolts 9.

That is, the case 3 and the circuit board 5 are held in a sandwich-like manner by the heat sink 43 and the holding member 8.

Note that the shapes of the side wall portion 43b of the heat dissipation plate 43 and the side wall portion 8b of the holding member 8 are not limited to the cylindrical shape, but may be semi-cylindrical shapes that do not cover the entire outer circumferences of the upper and lower halves of the case 3, respectively. It is sufficient if the shape is thin and at least the case 3 does not come out easily.

[Effect of idea]

According to this invention, the thickness of the bobbin can be reduced without being restricted by the height of the heat sink, and the thickness of the instrument body can be reduced, thereby realizing a thinner instrument.

This is suitable not only for tachometers and speedometers for vehicles, but also for portable ammeters, voltmeters, and other various meters.

Further, since the heat sink can obtain a larger surface area than the conventional one, the heat dissipation effect of the electronic components can be enhanced, and there is no sacrifice at all as the instrument becomes thinner.

Furthermore, the heat sink presses the top edge of the case, and the holding member presses the bottom edge of the case, and also clamps the circuit board, resulting in a structure that is extremely resistant to external vibrations, and has great practical value. It is.

[Brief explanation of drawings]

Fig. 1 is a side view with a part cut away of a conventional cross-wire type meter, and Figures 2 and 3 are side views with a part cut away of an embodiment of the cross-wire type meter according to this invention. , is a front view. 1... Cross wire ring type instrument, 2... Instrument body, 3...
Case 4... Electronic components, 43... Heat sink, 5...
- Circuit board, 8... Holding member, 9... Screw.

Claims (1)

[Scope of utility model registration request] A meter body consisting of a bobbin with a built-in rotating magnet fixed to a rotating shaft equipped with a pointer and wound with intersecting coils, a case that houses the meter body, and electronic components that apply signals to the meter body are arranged. In a cross-wire type meter comprising a circuit board, a notch portion having approximately the same shape as the outer circumferential shape of the case is provided, and the case is fitted to the notch portion, and a middle portion of the case in the thickness direction is provided. The circuit board is arranged such that the circuit board is located at the upper surface of the circuit board, and a base part that contacts the upper surface of the circuit board, a side wall part that covers the upper half of the case, and a locking part that holds the upper end of the case are integrally provided. A composite structure that integrally includes a metal heat sink for electronic components, a base portion that contacts the lower surface of the circuit board, a side wall portion that covers the lower half of the case, and a locking portion that holds the lower end of the case. 1. A mounting structure for a cross-ring type instrument, characterized in that the case and the circuit board are held in a sandwich-like manner by a holding member made of resin.