JPH0755509A - Measuring instrument for vehicle - Google Patents

Abstract

PURPOSE:To fit a voltage dropping resistor to a case without any protective cover. CONSTITUTION:A measuring instrument for vehicle is provided with internal machines 50a and 50B, a case 40 for housing the machines 50A and 50B, and a resistor 20 which adjusts the voltages respectively applied across the machines 50A and 50B to prescribed values and the resistor 20 is electrically connected to printed boards 30 put on the lower surface of the case 40 and, at the same time, protruded into a recessed section 42 formed on the bottom of the case 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle instrument and, more particularly, to a mounting structure for a resistor provided in the vehicle instrument.

[0002]

2. Description of the Related Art In recent years, an electric type instrument such as a speedometer, a tachometer (tachometer), a water temperature gauge, a fuel gauge and the like (internal unit) applied to a vehicle is often a 12V type applied voltage. Has been done. Therefore, for example, in a vehicle such as a truck, the power supply voltage input from the vehicle is 24V, and therefore it is necessary to reduce this voltage to 12V before use. Usually, a resistor is used to reduce the voltage of 24V to 12V, and the power supply voltage is reduced to a predetermined value by the voltage drop of this resistor.
The voltage has been lowered to V. FIG. 4 shows this power supply circuit. In FIG. 4, the 24V power supply voltage supplied from the vehicle via the ignition switch 1 is stepped down to 12V by the step-down resistor 2 and the instrument (internal unit) 3 is applied. A cement resistor or the like is used as the step-down resistor 2. Here, the variable resistor 4 is a variable resistor for adjusting the pointer position of the instruments.

On the other hand, an inexpensive flexible printed circuit board (FPC) has been adopted in place of the rigid printed circuit board (RPC) for electrical conduction between these internal units and the external detection element. When this flexible printed circuit board (FPC) is adopted, it is necessary to directly solder and connect a heavy and large step-down resistor, such as a cement resistor, to the land part of the flexible printed circuit board.
Since it is impossible for the flexible printed circuit board in terms of strength, it was considered to use a tapping screw to attach a resistor as shown in FIG.

That is, FIG. 3 shows a conventional mounting structure for a step-down resistor. In FIG. 3, a speedometer, a tachometer, a water temperature gauge, and a water temperature gauge are provided inside a case 40 of the vehicle instrument 10. Inner units 50A and 50B such as fuel gauges are housed and fixed, and a dial plate 51 is provided on the front faces of the inner units 50A and 50B. The output shafts 52A and 52B of the inner units 50A and 50B have pointers 53A and 53, respectively.
B is attached.

A flexible printed circuit board 30 is provided on the back surface of the bottom of the case 40. The lead portion of the resistor 20 is arranged so that the wiring of the flexible printed circuit board 30 and the step-down resistor 20 are electrically connected. 21A, 21B
Is placed on the upper surface of the flexible printed circuit board 30, and tapping screws 22A and 22B are fitted into the boss portions 41A and 41B to fix the resistor 20 and the flexible printed circuit board 30 to the back surface of the bottom of the case 40. Internal machine 50
A and 50B and the flexible printed circuit board 30 are fixed to each other by screws 54A, 54B, 54C and 54D. When the resistor 20 generates heat, the resistor 2
Since the surface temperature of 0 rises to about 100 ° C. or higher, a protective cover 60 is attached to the outer surface of the resistor 20 to prevent the hand, vehicle harness, and other parts from touching the resistor 20.

[0006]

However, when the resistor is attached to the case as described above, in order to prevent the hand, the vehicle harness and other parts from touching the resistor,
It is necessary to attach the protective cover to the outside of the case, which increases the number of parts and increases the cost. Further, when the protective cover is provided, there is a problem that an extra space is required between the instrument and vehicle parts. Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a vehicle instrument in which a resistor is mounted without a protective cover.

[0007]

A structural feature of the present invention is for a vehicle having an internal unit, a case for accommodating the internal unit, and a resistor for applying a predetermined voltage to the internal unit. In the instrument, the printed circuit board arranged on the back surface of the bottom of the case is electrically connected to the resistor, and the resistor is projected into the recess formed in the bottom of the case.

[0008]

In the present invention configured as described above, since the resistor is disposed so as to project into the recess formed in the bottom of the case, it is not necessary to attach a protective cover, and therefore, the component The number of points is reduced, so that the cost is reduced, and it is not necessary to provide an extra space with the vehicle parts, which is a space saving effect.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an embodiment of the present invention. In FIG. 1, inside the case 40 of the vehicle instrument 10,
Inner units 50A, 50B such as a speedometer, a tachometer (tachometer), a water temperature meter, and a fuel gauge are housed and fixed.
A dial 51 made of synthetic resin, for example, polycarbonate (PC) is provided on the front surfaces of A and 50B. Further, the output shafts 52A, 5A of the inner units 50A, 50B, respectively.
Hands 53A and 53B are attached to 2B, and a cover 42 made of a transparent synthetic resin, for example, a transparent acrylic resin is provided on the dial plate 51.

Synthetic resin such as polypropylene (PP)
At the bottom of the case 40 made of bosses 41A, 41B
And a recess 42 are provided, and the bosses 41A, 4
1B is provided to insert tapping screws 22A and 22B, which will be described later, and this recess 42 is provided to dispose a step-down resistor 20 described later.
Further, the bottom of the recess 42 is provided with a plurality of holes 43 for radiating heat when the step-down resistor 20 generates heat. Here, the step-down resistor 20 is composed of a cement resistor of about 5 to 10 W and the like, and at the bottom thereof, lead portions 21A and 21B made of metal and having an L-shaped cross section are provided.

Flexible printed circuit (FPC) 30
Has a hole 32 (see FIG. 2) into which the step-down resistor 20 is inserted. The flexible printed circuit board 30 is arranged on the back surface of the bottom of the case 40, and the wiring of the flexible printed circuit board 30 is provided. (Not shown) so that the step-down resistor 20 is electrically connected to the step-down resistor 20.
The hole 32 provided in the flexible printed circuit board 30
And the lead portion 21 of the step-down resistor 20 while being arranged so as to project into the recess 42 provided at the bottom of the case 40.
A and 21B are placed on the upper surface of the flexible printed circuit board 30, and tapping screws 22A and 22B are attached to the boss portion 41A,
41B, and the step-down resistor 20 and the flexible printed circuit board 30 are fixed to the back surface of the bottom of the case 40.

The internal units 50A and 50B and the flexible printed circuit board 30 are provided with screws 54A, 54B, 54C and 5 respectively.
It is fixed by 4D. At the time of this fixing, the land portion (not shown) for connecting the internal unit provided on the flexible printed circuit board 30 and the connection portion (not shown) provided in the internal units 50A, 50B are screwed by screws 54A, 54B, It is electrically connected by 54C and 54D.

Hereinafter, a method of mounting the step-down resistor 20 in the case 40 will be described with reference to FIG. 2. FIG. 2 is a perspective view of an essential part showing a method of mounting the step-down resistor according to the embodiment of the present invention. 2, the flexible printed circuit board 3 is provided with a hole 32 into which the step-down resistor 20 is inserted, copper foil lands 31A and 31B, and wiring (not shown).
0 is arranged on the bottom rear surface of the case 40. Then, in order to electrically connect the land portion (not shown) for connecting the internal unit provided on the flexible printed circuit board 30 and the connection portion (not shown) provided inside the internal units 50A and 50B, The inner units 50A and 50B and the flexible printed circuit board 30 are fixed to each other with screws 54A, 54B, 54C and 54D.

After that, the step-down resistor 20 provided with lead portions 21A and 21B having L-shaped cross sections having screw holes 23A and 23B at the ends thereof is provided in the hole portion 32 provided in the flexible printed circuit board 30 and the case 40. The step-down resistor 20 is arranged so as to project into the recess 42 provided at the bottom.
The lead holes 21A and 21B are screw-holes 23A and 23B and the copper foil land portions 31A and 31B are screw-holes 33A and 33B are aligned and placed on the upper surface of the flexible printed circuit board 30. Then tapping screws 22A, 22B
The screw holes 23A and 23B of the lead portions 21A and 21B and the screw holes 33A and 33B of the copper foil land portions 31A and 31B.
And the bosses 41A and 41B provided on the bottom of the case 40, and the step-down resistor 20 and the flexible printed circuit board 30 are fixed to the back surface of the bottom of the case 40.

To explain the effect of the above-mentioned embodiment, the step-down resistor 20 is disposed so as to project into the recess 42 formed in the bottom of the case 40, so that it is not necessary to attach a protective cover, so that the parts are Since the number of points is reduced, the cost is also reduced, and it is not necessary to provide an extra space with the vehicle parts, which leads to an effect of saving space.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of FIG.

FIG. 3 is a cross-sectional view showing a conventional resistance mounting structure.

FIG. 4 is a diagram showing a power supply circuit.

[Explanation of symbols]

10 ... Vehicle instrument, 20 ... Resistance, 22A, 22B ... Tapping screw, 40 ... Case, 42 ... Recess, 50A, 50
B: Internal unit (instrument), 51 ... Dial, 53A, 53B ... Pointer

Claims (1)

[Claims] 1. An inner unit and a case for accommodating the inner unit,
In a vehicle instrument having a resistance that makes a voltage applied to the internal unit a predetermined voltage, a printed circuit board arranged on the bottom rear surface of the case and the resistance are electrically connected, and the resistance is A vehicle instrument characterized by being projected into a recess formed in the bottom of a case.