JP3375882B2 - Thermal fuse device with ground function - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an improvement of the thermal fuse equipment provided in the electric circuit board, in particular, Ru <br/> relates to a thermal fuse equipment having a temporary fixing function to the electric circuit board .

[0002]

2. Description of the Related Art For example, an air conditioner for an automobile is provided with an electric circuit board on which a plurality of resistor patterns having a predetermined resistance value are formed in order to control the rotational speed of a motor for rotationally driving a blower fan. A blower control device is built in. In the blower control device, the level of electric power supplied to the motor is changed stepwise by changing the total resistance value, and the motor is switched between high speed rotation, medium speed rotation and low speed rotation. In this type of air blow control device,
On the way of the resistor pattern on the electric circuit board, there is provided a thermal fuse device including a thermal fuse unit that interrupts electrical conduction when the temperature exceeds a predetermined temperature.

FIG. 7A shows a conventional thermal fuse device.
There is one as shown in (B). The thermal fuse device 10 has a thermal fuse portion 14 that bridges a conduction breaker portion 13 provided between a first terminal 11 and a second terminal 12 that form a part of a resistor pattern. Thermal fuse part 1
Reference numeral 4 is formed by bending a material having elasticity so as to have a semicircular arc shape portion. The tip 14a of the thermal fuse portion 14 has a molten metal 15 that melts when the temperature exceeds a predetermined temperature.
Is adhered onto the first terminal 11, and the base end 14b is adhered onto the second terminal 12 by solder 16 having a melting point higher than that of the molten metal 15. The base end 14b is provided with a leg portion 14c to be inserted into a through hole 18 formed in the electric circuit board 17, and the base end 14b is fixed by caulking the leg portion 14c protruding from the back surface of the electric circuit board 17. It is fixed to the electric circuit board 17.

When an overcurrent flows between the first and second terminals 11 and 12 through the temperature fuse unit 14 due to a motor lock or the like and the temperature fuse unit 14 reaches a predetermined temperature or higher, the temperature fuse device 10 operates. Then, the power supply to the motor is forcibly cut off to protect the motor. That is, when the temperature exceeds the predetermined temperature and the molten metal 15 melts, the tip portion 14a of the temperature fuse portion 14 is separated from the first terminal 11 by the elastic force as shown by the phantom line, and the first terminal 11 and the second terminal 11 The electrical continuity with 12 is cut off.

By the way, a plurality of electronic elements are provided on the electric circuit board 17. However, in order to take measures against static electricity of these electronic elements and against electric wave noise, the electronic elements and the shield plate are the GND of the electric circuit board. Electrically connected to and grounded.

[0006]

However, in the conventional thermal fuse device 10, the thermal fuse section 14 is used.
When attaching the to the electric circuit board 17, it is necessary to insert the leg portion 14c of the thermal fuse portion 14 into the through hole 18 of the electric circuit board 17 and then caulk the protruding leg portion 14c. Thermal fuse part 1 for 17
4 is not easy to install.

In addition, the base end 14b of the thermal fuse portion 14
It is necessary to project the leg portion 14c on the base plate and to form the through hole 18 for inserting the leg portion 14c in the electric circuit board 17, so that the working operation of the thermal fuse portion 14 and the board 17 is complicated. . In particular, it is difficult to form the through holes 18 of the substrate 17 by press working and it is necessary to use drilling, so the working operation of the substrate 17 is extremely complicated.

Further, a component is required for grounding the electronic element and the shield plate, and mounting of this component is also complicated.

The present invention has been made in order to solve the problems associated with the prior art described above, and facilitates mounting of the thermal fuse section on the electric circuit board and simplifies the processing of the thermal fuse section and the electric circuit board. and purpose thereof is to provide a thermal fuse device to obtain achieving reduction.

[0010]

Further, the purpose thereof is to provide a thermal fuse device having a grounding function capable of achieving a reduction in the number of parts.

[0012]

[Object to A in order to achieve the above Symbol purposes the present invention is a thermal fuse device provided in the electric circuit board, and a temperature fuse portion that blocks electrical conduction becomes more than a predetermined temperature, For grounded parts that require grounding
At least one grounding portion in contact with said electrical circuit board
A clip with a U-shaped spring shape that can be freely sandwiched between the edges of the plate.
And a thermal fuse portion,
Molten gold on the first terminal that forms part of the electric circuit on the board
Continuation with the tip that can be adhered by a metal and the clip part
Provided with a conduction cutoff portion between the first terminal and the first terminal.
And a base end that can be adhered to the second terminal that is abraded.
The base part can contact the grounded component on the tip side.
The contact point, and
Is connected to the thermal fuse section and the earth section.
And the clip part is made by bending elastic material.
A ground characterized by being integrally formed by processing
It is a thermal fuse device with a function .

[0013]

[0014]

Here, the grounded component to be grounded is a heat sink fixed to an electronic element or a shield plate for shielding radio waves.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a fan motor unit partially cut away, which includes an electric circuit board on which a temperature fuse device having a grounding function according to the present invention is attached.
1 is an enlarged view showing a main part of FIG. 1, FIG. 3 is a view taken in the direction of arrow A in FIG. 2, and FIG. 4 is a perspective view showing a thermal fuse device having a grounding function shown in FIGS. .

The fan motor unit 20 shown in FIG.
A unit casing 23 composed of an upper case 21 and a lower case 22, a motor 24 for rotationally driving a centrifugal multi-blade fan (not shown), and a fan control mounted in the unit casing 23 and controlling the rotation speed of the motor 24. Electric circuit board 2 of amplifier 25
6 and.

On the electric circuit board 26, a plurality of electronic elements for controlling the rotation speed of the motor 24, electric parts, and a temperature fuse device are provided. As an electronic element, for example,
MOS field effect transistor (MOS FET) 27
There is. In order to efficiently radiate Joule heat generated in each transistor 27, a heat sink 28 made of aluminum is attached to the side surface of each transistor 27. The radiation fins 29 formed on the upper surface of the heat sink 28 are exposed to the outside of the unit casing 23. The heat sink 28 is not directly fixed to the electric circuit board 26,
It is supported only by the transistors 27 attached to the electric circuit board 26.

A metal shield plate 30 is attached to the inner surface of the bottom of the lower case 22 so as to cover the lower surface of the electric circuit board 26 in order to prevent radio noise.

The thermal fuse device 40 of the present embodiment has a grounding function, and as shown in FIGS. 2 to 4, a thermal fuse section 41 that cuts off electrical continuity when the temperature exceeds a predetermined temperature, and a grounding fuse. And the two ground parts 42 and 43 that come into contact with the grounded parts 28 and 30 that require the electric circuit board 2
6 has a clip portion 45 which can be freely sandwiched between the edge portions 44. The temperature fuse portion 41, the two ground portions 42 and 43, and the clip portion 45 are integrally formed by bending an elastic material (for example, phosphor bronze for spring). Heat sink 28 and shield plate 3
0 corresponds to the grounded component.

More specifically, the thermal fuse section 41
Is a first terminal 51 and a second terminal 52 that form a part of an electric circuit.
It has a semi-arcuate shape that bridges the conduction blocking portion 53 provided between and. The tip 41a of the temperature fuse portion 41 is
It is adhered onto the first terminal 51 by the molten metal 15 and the base end 4
1b is a solder 16 having a melting point higher than that of the molten metal 15.
Alternatively, it is adhered onto the second terminal 52 with an adhesive. The second terminal 52 forms a part of the GND circuit 54.

The clip portion 45 is provided continuously to the base end 41b of the thermal fuse portion 41 and has a U-shaped spring shape. Entrance size L of the clip portion 45 (see FIG. 5 (A))
Is set to a size smaller than the substrate thickness. However, the inlet dimension L is set to have a gripping force such that the insertion force into the substrate 26 does not become too large and is not easily dropped. It should be noted that the edge portion 44 of the substrate 26 is provided with a recess 55 for positioning the clip portion 45. The recess 55 can be processed at the same time when the substrate 26 is punched out by a press, and the processing of the substrate 26 can be simplified.

The grounding portions 42 and 43 shown in FIG.
6 of the first ground portion 42 that curves and extends upward in FIG.
And a second ground portion 43 that curves and extends downward in the drawing of the substrate 26. Contact portion 42a of the first ground portion 42
Elastically contacts the lower surface of the heat sink 28 to ground the static electricity of the heat sink 28. on the other hand,
The contact portion 43a of the second ground portion 43 elastically contacts the upper surface of the shield plate 30 to ground the shield plate 30.

A slit 46 is formed from the substantially central portion of each earthing portion 42, 43 to the tip of the earthing portion 42, 43 to divide it into two parts.
The contact portions 42a and 43a contacting the heat sink 28 or the shield plate 30 are R-shaped so as to make line contact. With such a shape, the ground portion 4
The reliable contact between the heat sinks 28 and 43 and the heat sink 28 and the shield plate 30 can be secured, and the reliability can be improved.

A procedure for fixing the temperature fuse device 40 having a grounding function to the electric circuit board 26 will be described with reference to FIG. First, as shown in FIG. 5 (A), the clip portion 45 of the thermal fuse device 40 is aligned with the recess 55 of the substrate 26, and the first ground portion 42 is slightly pushed down from the unloaded state shown by the phantom line while the clip is clipped. The portion 45 to the recess 55
Insert from the side. Since the clip portion 45 compresses the substrate 26 by the function of the U-shaped spring, the entire thermal fuse device 40 is temporarily fixed to the substrate 26. Also,
Since the clip portion 45 is located in the recess 55, the temperature fuse device 40 as a whole will not be displaced even in the temporarily fixed state. As described above, with a simple structure, the thermal fuse portion 41 can be easily attached to the electric circuit board 26.

When the pushing down of the first grounding portion 42 is released, as shown in FIG. 5 (B), due to the spring property of the first grounding portion 42 itself, the contact portion 42a has an appropriate pressure on the lower surface of the heat sink 28. Make sure contact under.

Thereafter, as shown in FIG. 5C, the tip 41a of the thermal fuse portion 41 is adhered onto the first terminal 51 by the molten metal 15, and the base end 41b is adhered to the second terminal by the solder 16.
When the thermal fuse device 40 is bonded onto the terminal 52, the fixing of the thermal fuse device 40 to the electric circuit board 26 is completed.

Referring to FIG. 2, the electric circuit board 26 to which the thermal fuse device 40 is fixed is attached to the unit casing 23.
When placed on the inner positioning boss 56, the second ground portion 4
3 is slightly pushed up from the unloaded state shown by the phantom line, and due to the spring property of the second ground portion 43 itself, the contact portion 43a surely contacts the upper surface of the shield plate 30 under proper pressure.

The operation of this embodiment will be described. Motor 24
When an overcurrent flows between the first and second terminals 51 and 52 via the temperature fuse portion 41 due to a lock or the like, the temperature fuse portion 41 becomes a predetermined temperature or higher and the molten metal 15 is melted,
Due to the elasticity of the thermal fuse portion 41 itself, the tip 41a thereof is separated from the first terminal 51. This makes the first
The electrical continuity between the terminal 51 and the second terminal 52 is cut off, and the motor 24 is protected.

Further, since the static electricity of the heat sink 28 is removed via the first ground portion 42, the heat sink 28
It is possible to prevent the operation of the transistor 27 from becoming unstable or from being damaged by static electricity from the device. Further, since the shield plate 30 is grounded via the second ground portion 43, the generation of radio noise is prevented.

As described above, in the present embodiment, the thermal fuse unit 41 and the grounding units 42 and 43 are integrated into the thermal fuse unit 40 having a grounding function, so that the heat sink contacting the electronic element 27 is in contact. It is not necessary to manufacture separate and independent parts for grounding the shield plate 28 and the shield plate 30, and the work can be simplified and the cost can be reduced by reducing the number of parts.

Further, since the clip portion 45 having a spring property is inserted into the board 26 to sandwich the board 26, the temperature fuse portion 41 for the electric circuit board 26 is formed.
Also, the mounting of the ground portions 42, 43 can be facilitated.

Further, since the temperature fuse device 40 having a grounding function can be temporarily fixed, the soldering of the temperature fuse portion 41 to the base end 41b of the automatic soldering line can be performed simultaneously with the soldering of other parts. .
For this reason, the end 41 of the thermal fuse portion 41 made of the molten metal 15
Since it is only necessary to bond a in another processing line, it is possible to shorten the time required to fix the thermal fuse device 40.

FIG. 6 is a diagram showing a main part of the second embodiment of the present invention. The second embodiment is different from the first embodiment in that the shape of the first ground portion 62 is modified.

The electric circuit board 26 shown in the first embodiment is
Before mounting the thermal fuse device 40 having a ground function, the heat sink 28 is already supported above the substrate 26 via the transistors 27.

Therefore, in the second embodiment, the first ground portion 6
The shape of 2 is a temperature fuse device 60 with a grounding function.
It is designed to be convex on the front side along the insertion direction of. With such a shape, as the clip portion 45 is inserted into the recess 55, the first grounding portion 62 does not have to be pushed down and the first grounding portion 62 can be attached to the upper surface of the substrate 26 and heat sink 28.
It is inserted smoothly into the gap between the lower surface and
The second contact portion 62a surely contacts the lower surface of the heat sink 28.

In the first and second embodiments, the temperature fuse unit 41 and the ground units 42 (62) and 43 are integrated with the clip unit 45, and the temperature fuse devices 40 and 60 having the ground function are explained. The invention is not limited to this case. For example, a temperature fuse device having a temperature fuse unit and a clip unit and having only a temperature fuse function, or a grounding device having a ground unit and a clip unit and having only a ground function may be used.

In addition, two grounding portions are provided for exhibiting a grounding function.
Although the case where the individual pieces are provided is shown, at least one ground portion may be provided. Further, it is not necessary to extend the ground portion in parallel with the inserting direction of the clip portion, and it can be freely determined according to the arrangement position of the grounded component. For example, the ground portion can be extended in a direction orthogonal to the inserting direction or in an oblique direction. Further, although the case where the ground portions are respectively extended above and below the clip portion is illustrated, it is possible to extend a plurality of ground portions to either one of the top and bottom.

Further, the grounded component is the heat sink 28.
Needless to say, it is not limited to the shield plate 30.

[0041]

As described above, according to the invention as set forth in any one of claims 1 to 7 , the mounting of the temperature fuse portion on the electric circuit board is facilitated and the temperature fuse portion and the electric circuit are facilitated. It is possible to provide a thermal fuse device capable of simplifying the processing of the substrate.

[0042]

Further, according to the invention described in any one of claims 1 to 7 , it is possible to provide a temperature fuse device having a grounding function capable of reducing the number of parts.

According to the second aspect of the present invention, since the static electricity of the heat sink is removed, it is possible to prevent the operation of the electronic element from becoming unstable or failing due to the static electricity from the heat sink.

According to the third aspect of the present invention, the shield plate can be easily grounded and the generation of radio noise can be prevented. Further, according to the invention described in any one of claims 8 to 11 , it is possible to provide an electric circuit board to which the temperature fuse device according to the present invention is applied.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a fan motor unit including an electric circuit board to which a temperature fuse device having a grounding function according to the present invention is attached.

FIG. 2 is an enlarged view showing a main part of FIG.

FIG. 3 is a view on arrow A of FIG.

FIG. 4 is a perspective view showing a thermal fuse device having a grounding function shown in FIGS.

5 (A) to 5 (C) are views for explaining a procedure for fixing the temperature fuse device having a grounding function to an electric circuit board.

FIG. 6 is a diagram showing a main part of a second embodiment of the present invention.

7A and 7B are views showing a conventional thermal fuse device.

[Explanation of symbols]

26 ... Electric circuit board 27 ... Electronic element 28 ... Heat sink (grounded component) 30 ... Shield plate (grounded component) 40 ... Thermal fuse device 41 ... Thermal fuse section 42, 43, 62 ... Ground section 44 ... Edge of electric circuit board 45 ... Clip section

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-298058 (JP, A) JP-A-4-107981 (JP, A) JP-A-6-20575 (JP, A) JP-A-1- 194396 (JP, A) JP 10-302607 (JP, A) Actually open 5-1147 (JP, U) Actually open 62-104409 (JP, U) Actually open 52-100556 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01H 37/76

Claims (11)

(57) [Claims] 1. A thermal fuse device provided on an electric circuit board (26), wherein a thermal fuse section (41) that interrupts electrical continuity at a predetermined temperature or higher and a grounded component (28, 30) that requires grounding. ) And at least one grounding part (42, 43, 62), and a clip part (45) having a U-spring shape that can be sandwiched between the edges (44) of the electric circuit board (26). The temperature fuse unit (41) is connected to the electric circuit board (2).
The tip (41a) which can be adhered by the molten metal (15) on the first terminal (51) forming a part of the electric circuit in 6).
And a second terminal (52) continuously provided to the clip portion (45) and having a conduction cutoff portion (53) between the first terminal (51) and the clip portion (45). Base (41
b), the ground portion (42, 43, 62) has a contact portion (42a, 43a, 62a) capable of contacting the grounded component (28, 30) at the tip side, and the base end Side is connected to the clip part (45), the temperature fuse part (41), the earth part (42, 4)
3, 62) and the clip part (45) are integrally formed by bending an elastic material, and have a grounding function. 2. The thermal fuse device according to claim 1, wherein the grounded component to be grounded is a heat sink (28) fixed to an electronic element (27). 3. The thermal fuse device according to claim 1, wherein the grounded component requiring grounding is a shield plate (30) for shielding radio waves. 4. The size of the entrance of the clip portion (45) is
The thermal fuse device according to claim 1, wherein the thermal fuse device is set to have a size smaller than the thickness of the electric circuit board (26). 5. The tip of the ground portion (42, 43) is
The thermal fuse device according to any one of claims 1 to 4, wherein the thermal fuse device is divided into two parts. 6. The contact portion of the ground portion (42, 43) which comes into contact with the grounded component (28, 30) is R-shaped, wherein the contact portion is R-shaped. Thermal fuse device according to. 7. The grounding portion (42, 43) is a first grounding portion (4) extending above the electric circuit board (26).
2) and a second extending below the electric circuit board (26)
A ground part (43) is provided.
7. The thermal fuse device according to any one of 6 to 6. 8. An electric circuit board provided with the thermal fuse device according to claim 1. 9. The first end (41a) of the thermal fuse portion (41) is formed by the molten metal (15) to form the first portion.
The thermal fuse part (4) is bonded on the terminal (51).
9. The base end (41b) of 1) is bonded onto the second terminal (52) by a solder (16) having a higher melting point than the molten metal (15).
The electric circuit board according to. 10. The tip (41a) of the thermal fuse section (41) is adhered onto the first terminal (51) by a molten metal (15), and the thermal fuse section (41) is bonded.
The base end (41b) of the second terminal (52) is larger than the molten metal (15) by the solder (16) having a larger projected area when viewed in the extension direction of the axis perpendicular to the electric circuit board (26). 9.) The electric circuit board according to claim 8, which is adhered on. 11. The edge (44) according to claim 8, characterized in that a recess (55) for positioning the clip (45) is provided in the edge (44). Electric circuit board.