JP2003260992A - Electric circuit protective device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric circuit protective device having a first resin case and capable of grounding a substrate without interposing a connector for connecting a vehicle wire harness. <P>SOLUTION: This electric circuit protective device 1 is provided with the first case 2 having a vehicle mounting part 20 fixed to a vehicle body, a second case 3 for sectioning a storage chamber 40 between the second case 3 and the first case 2, the substrate 4 arranged in the storage chamber 40 and having an electric circuit, and the connector 5 for electrically connecting the electric circuit and external equipment. The first case 2 is made of resin. A grounding conductive path is formed by a grounding member 6 between the substrate 4 and the vehicle body. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric circuit protection device used for fixing and protecting an electric circuit.

[0002]

2. Description of the Related Art Electric circuit protection devices are used, for example, to protect electric circuits for airbags. FIG. 8 shows an exploded view of an electric circuit protection device that houses an electric circuit for an airbag.
As shown in the figure, the electric circuit protection device 100 includes a first case 101, a second case 102, a board 103, and a connector 1.
It consists of 04.

The first case 101 is made of metal and has a box-like shape that opens upward. The first case 101 includes a vehicle mounting portion 105, a connector window 106, and a screw mounting seat 10.
Have 7 and. The vehicle mounting portion 105 is provided so as to project outward from the side walls of the first case 101 which face each other. A vehicle mounting hole 108 is formed in the vehicle mounting portion 105. The connector window 106 is formed by cutting a side wall of the first case 101 from the upper end in a U-shape. The screw mounting seats 107 are provided so as to project upward from the four corners of the bottom wall of the first case 101. Screw mounting seat 107
A screw mounting hole 109 is formed on the upper surface of the.

The second case 102 is made of metal and has a rectangular plate shape. The second case 102 is arranged above the first case 101. And the first case 10
A storage chamber 112 is defined by the first case 1 and the second case 102. The second case 102 has a step portion 110. The step portions 110 are formed at the four corners of the second case 102. A screw through hole 111 is formed in the step portion 110.

The substrate 103 has a rectangular plate shape.
The substrate 103 is arranged in the storage chamber 112. Board 1
On 03, an electric circuit for an airbag (not shown) is mounted. Screw through holes 113 are formed at four corners of the substrate 103. The connector 104 is made of resin and has a rectangular tubular shape. The connector 104 is soldered and screwed to the substrate 103.

To assemble the electric circuit protection device 100, first, the connector 104 is screwed to the board 103, then the connector 104 is soldered to the board 103, and then the male screw 114 is inserted from above from the screw through hole 111 and the screw through hole. 113
And the male screw 114 and finally the screw mounting hole 109.
It is done by screwing on.

To mount the electric circuit protection device 100 on the vehicle body, first, the stay portion (not shown) of the vehicle body is brought into contact with the upper surface of the vehicle mounting portion 105, and then the male screw 1
This is done by penetrating the vehicle mounting hole 108 from below and finally screwing the male screw 115 into the device mounting hole (not shown) of the stay portion.

[0008]

However, both the first case 101 and the second case 102 of the conventional electric circuit protection device 100 are made of metal. If both cases are made of metal, it is difficult to give the cases a predetermined shape. In addition, the raw material cost becomes high. Therefore, the manufacturing cost of the electric circuit protection device 100 increases. If both cases are made of metal, the electric circuit protection device 100 becomes heavy.

Here, in order to reduce the manufacturing cost of the electric circuit protection device 100 and reduce the weight of the electric circuit protection device 100, the first case 101 and the second case 102 may be made of resin. However, conventionally, the substrate 103 and the vehicle body are electrically connected via the first case 101. That is, a conduction path of the board 103 → first case 101 → vehicle body is secured. The substrate 103 is grounded by this conduction path. This earth is an external electrical noise (electromagnetic wave, static electricity, IG pulse)
It is intended to protect the air bag electrical circuit from and to provide redundancy of the electrical circuit ground.

Therefore, if the first case 101 is made of resin, the conduction path from the substrate 103 to the vehicle body is blocked by the first case 101. Then, there arises a problem that the substrate 103 cannot be grounded.

The electric circuit protection device of the present invention has been completed in view of the above problems. Therefore, the present invention
An object of the present invention is to provide an electric circuit protection device which has a first case made of resin and can ground the substrate.

[0012]

(1) In order to solve the above problems, an electric circuit protection device of the present invention is provided between a first case having a vehicle mounting portion fixed to a vehicle body and a first case. An electric circuit protection device comprising: a second case for partitioning a storage chamber, a substrate arranged in the storage chamber and having an electric circuit, and a connector for electrically connecting the electric circuit and an external device. The case is made of resin and is characterized in that a ground conduction path is formed between the substrate and the vehicle body.

The first case of the electric circuit protection device of the present invention is made of resin. When the first case is made of resin, it is easy to give the case a predetermined shape. Also, the raw material cost is reduced. Therefore, the manufacturing cost of the electric circuit protection device of the present invention is low. Further, since the first case is made of resin, the electric circuit protection device of the present invention is lightweight. Further, the electric circuit protection device of the present invention has a ground conduction path that electrically connects the substrate and the vehicle body. Therefore, although the first case is made of resin, the electric circuit can be protected from external electric noise.

(2) Preferably, in the above configuration (1), the connector is formed integrally with the first case. If the first case is made of resin, it is easy to integrally form the connector with the first case. If the connector and the first case are integrated, the number of parts is reduced accordingly. Further, the step of screwing the connector to the board at the time of assembly is unnecessary. Therefore, the manufacturing cost can be further reduced.

(3) Preferably, in the configuration of (1) above, the first case has a first engaging portion, the second case is made of resin, and the second engaging portion engages with the first engaging portion. It is better to have a section.

In this structure, not only the first case but also the second case is made of resin. Therefore, the manufacturing cost can be further reduced and the weight can be further reduced. Also,
The first case and the second case are assembled by engaging the first engaging portion and the second engaging portion. Therefore, it is not necessary to screw the first case and the second case together during assembly. Therefore, according to this configuration, the number of parts can be further reduced. Also, the assembly becomes easy.

(4) Preferably, in the above configuration (1), the earth conduction path is embedded in the first case, has one end extending to the vehicle mounting portion, and the other end having a substrate contact portion. It is preferable that the substrate has a grounding member contact portion with which the substrate contact portion contacts.

The earth conduction path of this structure is formed by an earth member. The ground member is embedded in the first case. One end of the ground member extends to the vehicle mounting portion. Then, it is electrically connected to the vehicle body.
Further, a substrate contact portion is arranged at the other end of the ground member. On the other hand, the ground member contact portion with which the substrate contact portion contacts is arranged on the substrate.

The grounding member of this construction is embedded in the first case. That is, the earth member is firmly fixed to the first case. Therefore, even if the electric circuit protection device swings, there is little risk that the ground member and the substrate, or the ground member and the vehicle body will not be electrically connected. Therefore, according to this configuration, it is possible to more reliably ensure the ground conduction path.

(5) Preferably, in the above configuration (4), the board contact portion is a board engagement piece, and the ground member contact portion is inserted and locked with the board engagement piece. It is better to have a structure that is an engagement hole for a ground member.

In other words, in this configuration, the board and the ground member are electrically connected by locking the board engaging piece in the ground member engaging hole. Further, the substrate is fixed to the first case via the earth member. According to this configuration, it is possible to secure the continuity of the board and fix the board only by the board engagement piece and the ground member engagement hole. For this reason,
Further, the number of parts can be reduced. Moreover, the assembly becomes easier.

(6) In the configuration of (4) above, preferably, the substrate contact portion is a female screw cylinder, the ground member contact portion is a ground member screw hole in series with the female screw cylinder, and It is better to have a connecting male screw that penetrates the ground member screw hole and is screwed to the female screw cylinder.

That is, in this structure, the substrate and the ground member are screwed together to electrically connect the substrate and the ground member. Further, the substrate is fixed to the first case via the earth member. According to this configuration, the substrate and the ground member are screwed together. Therefore, the contact state of both members can be kept good. Therefore,
It is possible to secure the conduction more reliably. Further, since the substrate is firmly fixed by the screwing, the substrate is less likely to swing with respect to the first case.

(7) Preferably, in the above configuration (4), the vehicle mounting portion and the board contact portion are arranged in close proximity to each other. That is, in this configuration, a relatively short ground member is embedded in the first case. When the ground member is short, the possibility that the conduction will be interrupted is reduced accordingly. Further, the electric resistance in the earth conduction path is also reduced. Therefore, the ground conduction path can be secured more reliably.

(8) Preferably, in the above configuration (1), the second case is made of metal, and the second case forms at least a part of the ground conduction path.

According to this structure, the second case itself forms at least a part of the ground conduction path. For this reason,
A relatively wide path cross-sectional area can be secured. Therefore, according to this configuration, it is possible to more reliably ensure the ground conduction path.

(9) Preferably, in the above configuration (8), the earth conducting path is embedded in the first case, has one end extending to the vehicle mounting portion, and the other end having a frame portion. And a second case that is inscribed in the frame portion, and the substrate preferably has a second case contact portion that contacts the second case.

The earth conducting path of this structure is composed of the second case and the earth frame. The second case is inscribed in the earth frame. Therefore, a relatively wide contact area can be secured. Therefore, according to this configuration, it is possible to more reliably ensure the ground conduction path.

(10) Preferably, in the above configuration (8), the ground conduction path is formed by the second case having a mounting portion contact portion that contacts the vehicle mounting portion,
It is preferable that the substrate has a second case contact portion that contacts the second case.

The earth conduction path of this structure is formed only from the second case. Therefore, it is not necessary to separately arrange a member for ensuring conduction. According to this configuration,
Further, the number of parts can be reduced. Also, the assembly becomes easy. In addition, the ground conduction path can be secured more reliably.

(11) Preferably, in any one of the configurations (1) to (10), the electric circuit is an air bag electric circuit having an acceleration detecting means for detecting a collision acceleration of the vehicle, and the substrate is It is better to have a structure in which at least one of the first case and the second case is screwed.

That is, this configuration uses the electric circuit protection device of the present invention for controlling an airbag. Further, the substrate is screwed to at least one of the first case and the second case.

The electric circuit for the air bag is provided with acceleration detecting means for detecting the acceleration of the vehicle and converting it into an electric signal. In order for the acceleration detecting means to ensure a predetermined detection accuracy, it is necessary to transmit the acceleration of the vehicle from the vehicle body to the acceleration detecting means as accurately as possible. Therefore, it is preferable that the substrate is firmly fixed in the storage chamber. In this regard, in this configuration, the substrate is screwed to the first case or the second case. Therefore, according to this configuration, it is easy to ensure the detection accuracy of the acceleration detection means.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an electric circuit protection device of the present invention will be described below. The embodiments described below all embody the electric circuit protection device of the present invention for controlling an airbag.

(1) First Embodiment First, the configuration of the electric circuit protection device of this embodiment will be described. The electric circuit protection device of this embodiment is arranged in a center tunnel on the vehicle floor. FIG. 1 shows an exploded view of the electric circuit protection device of this embodiment. As shown in the figure,
The electric circuit protection device 1 includes a first case 2, a second case 3, a board 4, a connector 5 and a ground member 6. In addition,
The ground member 6 is embedded in the first case 2 by insert molding, but is shown by a solid line for convenience of explanation. Further, members arranged inside the first case 2 are indicated by dotted lines.

The first case 2 is made of polybutylene terephthalate (PBT), and has the shape of a rectangular parallelepiped box that opens upward. In the first case 2, the vehicle mounting portion 20 and the ground member holding column 21 are integrally formed. The vehicle mounting portion 20 is provided so as to project outward from side walls of the first case 2 that face each other. That is, the vehicle mounting portion 2
Two 0s are arranged in total. Further, the two vehicle mounting portions 20 are arranged substantially at diagonal positions. A vehicle mounting hole 22 is formed in the vehicle mounting portion 20. A first engaging hole 23 is formed in each of the two side walls of the first case 2 having the vehicle mounting portion 20. The first engagement hole 23
Are included in the first engaging portion of the present invention. First engagement hole 23
Are perforated on each side wall. That is,
A total of four first engaging holes 23 are arranged. The ground member holding column 21 has a prismatic shape. The ground member holding columns 21 are provided so as to project upward from the four corners of the bottom wall of the first case 2. That is, the earth member holding column 21 is
There are four in total.

The earth member 6 is made of brass. The grounding members 6 are arranged on the two side walls of the first case 2 having the vehicle mounting portion 20 so as to face each other. That is, a total of two ground members 6 are arranged. Earth member 6
Is composed of a frame portion 60, a connecting portion 61, and a ring portion 62. Of these, the frame portion 60 has a U-shape with its tip bent upward. The frame portion 60 is arranged so that its tip end faces the inside of the first case 2. Specifically, the frame portion 60 is embedded in the side wall of the first case 2 and the two ground member holding columns 21 adjacent to the side wall. A board engaging piece 63 is provided upright on the bent upper end of the frame portion 60. The ring portion 62 is embedded in the vehicle mounting portion 20. Ring part 6
2 is exposed on the inner peripheral side of the vehicle mounting hole 22. The connecting portion 61 has an L shape. The connecting portion 61 is embedded in the side wall of the first case 2 and the vehicle mounting portion 20. Then, the frame portion 60 and the ring portion 62 are bent and connected.

The connector 5 is made of PBT and has a rectangular tubular shape. The connector 5 is provided so as to project outward from the side wall of the first case 2. The connector 5 is formed integrally with the first case 2. The connector 5 is connected to a mating connector (not shown) by a plurality of connector pins (not shown). The connector 5 is electrically connected to a battery, an airbag, a warning light of a meter panel, or the like via the mating connector.

The second case 3 is made of PBT and has a rectangular plate shape. The second case 3 is arranged above the first case 2. A storage chamber 40 is defined by the first case 2 and the second case 3. The second case 3 is integrally formed with a second engaging claw 30.
The second engaging claw 30 is included in the second engaging portion of the present invention. The second engagement claw 30 is arranged at a position facing the first engagement hole 23 in the vertical direction. That is, two second engaging claws 30 are arranged on each of two opposite sides of the second case 3.

The substrate 4 has a rectangular plate shape. The substrate 4 is arranged in the storage chamber 40. An electric circuit for an airbag (not shown) is mounted on the substrate 4. Further, acceleration detection means (not shown) is arranged in the electric circuit for the airbag. Grounding member engaging holes 41 are formed at the four corners of the substrate 4. Further, a U-shaped cutout portion 42 is formed on the substrate 4. The cutout portion 42 is arranged at a position facing the second engaging claw 30 in the vertical direction. That is, two notches 42 are arranged on each of two opposite sides of the second case 3.

Next, a method of assembling the electric circuit protection device of this embodiment will be described. In assembly, first, the substrate 4 is fixed to the first case 2. FIG. 2 shows an exploded view of the state where the substrate is fixed to the first case. In particular,
As shown in the drawing, the tin-plated board engaging piece 63 is penetrated from below into the earth member engaging hole 41. Then, the upper end of the board engagement piece 63 is projected above the board 4. Then, this protruding portion is bent inward or outward and soldered to the GND of the substrate 4. Further, the connector 5 and the electric circuit for the airbag are soldered. In this way, the substrate 4 is fixed to the first case 2. At the same time, the earth member and the substrate 4 are brought into contact with each other.
In the assembly, next, the first case 2 and the second case 3
To fix. Specifically, as shown in the drawing, the second engaging claw 30 is passed through the cutout portion 42. Then, the second engagement claw 30 is locked in the first engagement hole. In this way, the second case 3 is fixed to the first case 2.

Next, a method of mounting the electric circuit protection device of this embodiment on the vehicle body will be described. In the mounting, first, the stay portion (not shown) of the vehicle body is brought into contact with the upper surface of the vehicle mounting portion 20. Next, the male screw 7 is passed through the ring portion 62 from below. Finally, the male screw 7 is screwed into the device mounting hole (not shown) of the stay portion.

Next, the earth conduction path of the electric circuit protection device of this embodiment will be described. Returning to FIG. 1, the earth conduction path of the present embodiment is formed by the earth member 6. As described above, the earth member 6 and the substrate 4 are
The board engaging pieces 63 are inserted into the grounding member engaging holes 41 and locked to be electrically connected. Also,
The ground member 6 and the vehicle body are electrically connected by the inner peripheral surface of the ring portion 62 contacting the outer peripheral surface of the male screw 7. That is, the ground current is the ground member engaging hole 41 → the board engaging piece 63 → the frame portion 60 → the connecting portion 61 → the ring portion 62 → the male screw 7 or the ground member engaging hole 41 → the board engaging piece 63. → frame part 60 → connecting part 6
It flows in the order of 1 → ring portion 62. In this way, in the present embodiment, the earth member 6 forms the earth conduction path.

Next, the effect of the electric circuit protection device of this embodiment will be described. First case 2 and second case 3
Is made of PBT. Therefore, the manufacturing cost of the electric circuit protection device 1 of the present embodiment is low. Further, the electric circuit protection device 1 is lightweight.

In the electric circuit protection device 1, a grounding path is secured by the grounding member 6. Therefore, the electric circuit for the airbag can be protected from electromagnetic noise.

The connector 5 is integrally formed with the first case 2. Therefore, the number of parts of the electric circuit protection device 1 is small. Also, at the time of assembly, the connector 5
A separate assembling step is unnecessary by, for example, screwing. Also in this respect, the manufacturing cost of the electric circuit protection device 1 is low.

By engaging the second case 3 with the first case 2 and the second engaging claw 30 with the first engaging hole 23,
Fixed. Therefore, it is not necessary to screw the first case 3 and the second case 3 together during assembly. Also in this respect, the number of parts of the electric circuit protection device 1 is small.
In addition, it is easy to assemble because no screws are required.

The ground member 6 is embedded in the first case 2. That is, the ground member 6 is firmly fixed to the first case 2. Therefore, there is little risk that the ground member 6 and the substrate 4 or the ground member 6 and the vehicle body will be electrically disconnected.

Further, the board engaging piece 63 is locked in the earth member engaging hole 41. The substrate 4 is electrically connected to the ground member 6. At the same time, the substrate 4 is fixed to the first case 2 via the earth member 6. That is, the electrical connection of the board 4 is secured and fixed only by the board engaging piece 63 and the earth member engaging hole 41. Also in this respect, the number of parts of the electric circuit protection device 1 is small. Moreover, the assembly is easy.

The second engaging claw 30 penetrates the notch 42 in the vertical direction and is locked in the first engaging hole 23. Therefore, the horizontal swing of the substrate 4 can be suppressed. Therefore, the substrate 4 does not easily swing in the storage chamber 40, and it is easy to ensure the detection accuracy of the acceleration detection means.

(2) Second Embodiment The difference between this embodiment and the first embodiment is that the vehicle mounting portion is arranged substantially at the center of the side wall of the first case. In addition, the substrate is fixed to the first case by screwing. Also, the grounding member engagement hole on the substrate,
This is that the board engaging pieces are not arranged on the grounding member. In addition, the first engagement hole is arranged above the substrate, and accordingly, the concave portion is not arranged in the substrate. Therefore, only the differences will be described here.

First, differences in the configuration of the electric circuit protection device of this embodiment will be described. FIG. 3 shows an exploded view of the electric circuit protection device of this embodiment. The members corresponding to those in FIG. 1 are indicated by the same symbols.

In the first case 2, the first engaging hole 23
However, it is arranged at a fixed position of the substrate 4, that is, above the upper surface of the earth member holding column 21. In addition, the vehicle mounting portion 2
0 is arranged almost at the center of the side wall of the first case 2.
Further, of the four ground member holding columns 21, two screw members 24 are embedded in the two ground member holding columns 21 at diagonal positions. The screw seat 24 is made of metal and has a cylindrical shape.

In the earth member 6, the ring portion 62
Is embedded in the vehicle mounting portion 20. Ring part 62
Has a short axial length. Therefore, the ring portion 6
No. 2 does not extend below the inner circumference of the vehicle mounting hole 22.
Further, a portion of the connecting portion 61 exposed on the upper surface of the vehicle mounting portion 20 is formed relatively wide. The frame portion 60 has an L shape. Frame part 60
Is embedded in the side wall of the first case 2 and the ground member holding column 21 that does not have the screw seat 24 among the two ground member holding columns 21 adjacent to the side wall. At the bent upper end of the frame portion 60, the conical substrate contact portion 6 is formed.
4 are erected.

In the substrate 4, two screw through holes 43
Are pierced vertically. The screw through holes 43 are arranged at two diagonal corners of the four corners of the substrate 4. The screw seat 24 and the screw through hole 43 are vertically connected in series. A ground member contact portion (not shown) is arranged on the lower surface of the substrate 4.

Next, a method of assembling the electric circuit protection device of this embodiment will be described. In assembly, first, the male screw 70 is passed through the screw through hole 43 from above,
The substrate 4 is fixed to the first case 2 by being screwed onto the screw seat 24. At this time, at the same time, the tin-plated substrate contact portion 64 is soldered to the ground member contact portion arranged on the substrate 4. Further, the connector 5 and the electric circuit for the airbag are soldered. Then, by engaging the second engaging claw 30 with the first engaging hole 23,
The second case 3 is fixed to the first case 2.

Next, a method of mounting the electric circuit protection device of this embodiment on the vehicle body will be described. In the mounting, first, the stay portion (not shown) of the vehicle body is brought into contact with the upper surface of the vehicle mounting portion 20. Next, the male screw 7 is passed through the ring portion 62 from below. Then, the male screw 7 is screwed into the device mounting hole (not shown) of the stay portion.

Next, the earth conduction path of the electric circuit protection device of this embodiment will be described. The earth conduction path of the present embodiment is formed by the earth member 6. The ground member 6 and the substrate 4 are electrically connected by the contact portion 64 for the substrate contacting the contact portion for the ground member.
Further, the ground member 6 and the vehicle body are electrically connected by the upper surface of the ring portion 62 and the upper surface of the connecting portion 61 contacting the stay portion. That is, the ground current is
Contact part for grounding member → contact part 64 for substrate → frame part 6
It flows in the order of 0 → connecting portion 61 / ring portion 62 → stay portion. In this way, in the present embodiment, the earth member 6 forms the earth conduction path.

Next, the effect peculiar to the electric circuit protection device of this embodiment will be described. The substrate 4 is screwed to the first case 2. That is, the substrate 4 is firmly fixed to the storage chamber 40. Therefore, according to this embodiment, it is easy to ensure the detection accuracy of the acceleration detection means.
Further, a portion of the connecting portion 61 exposed on the upper surface of the vehicle mounting portion 20 is formed relatively wide. Therefore, the contact area between the ground member 6 and the stay portion is large. The first engagement hole 23 is arranged above the fixed position of the substrate 4. Therefore, it is not necessary to separately form a concave portion on the substrate 4.

(3) Third Embodiment The difference between this embodiment and the first embodiment is that a screw hole for a ground member is arranged on the substrate and a female screw cylinder is arranged on the ground member. Therefore, only the differences will be described here.

First, differences in the configuration of the electric circuit protection device of this embodiment will be described. FIG. 4 shows an exploded view of the electric circuit protection device of this embodiment. The members corresponding to those in FIG. 1 are indicated by the same symbols.

The earth member 6 includes a ring portion 62 and a connecting portion 6.
1, a frame portion 60, and a female screw cylinder 65. In the ground member 6, the ring portion 62 is embedded in the vehicle mounting portion 20. The ring portion 62 has a short axial length. For this reason, the ring portion 62 does not extend downward to the inner peripheral side of the vehicle mounting hole 22. Further, a portion of the connecting portion 61 exposed on the upper surface of the vehicle mounting portion 20 is formed relatively wide. The frame portion 60 has an L shape. The frame portion 60 first extends downward in the side wall of the first case 2 from the connecting portion 61. continue,
The frame portion 60 projects inward from the side wall of the first case 2. At the protruding end of the frame portion 60, the screw through hole 6
6 are arranged. Below the screw through hole 66, a cylindrical female screw cylinder 65 made of brass is arranged adjacently. The female screw cylinder 65 is embedded in the ground member holding column 21.

Two ground member screw holes 44 are formed in the substrate 4 in the vertical direction. The ground member screw holes 44 are arranged at two diagonal corners of the four corners of the substrate 4. The female screw cylinder 65, the screw through hole 66, and the ground member screw hole 44 are vertically connected in series.

Next, a method of assembling the electric circuit protection device of this embodiment will be described. In the assembling, first, the joining male screw 71 is attached from above to the ground member screw hole 44
The substrate 4 is fixed to the first case 2 by penetrating through the screw through hole 66 and screwing into the female screw cylinder 65. At this time, simultaneously, the ground member screw hole 44 and the screw through hole 6
6 and the female screw cylinder 65 are brought into contact with each other. Further, the connector 5 and the electric circuit for the airbag are soldered. Then, the second case 3 is fixed to the first case 2 by locking the second engagement claw 30 in the first engagement hole 23.

Next, a method of mounting the electric circuit protection device of this embodiment on the vehicle body will be described. In the mounting, first, the stay portion (not shown) of the vehicle body is brought into contact with the upper surface of the vehicle mounting portion 20. Next, the male screw 7 is passed through the ring portion 62 from below. Then, the male screw 7 is screwed into the device mounting hole (not shown) of the stay portion.

Next, the earth conduction path of the electric circuit protection device of this embodiment will be described. The earth conduction path of the present embodiment is formed by the earth member 6. The grounding member 6 and the board 4 are formed of the female screw cylinder 65 and the screw through hole 6
When 6 contacts the screw hole 44 for the ground member, they are electrically connected. Further, the ground member 6 and the vehicle body are electrically connected by the upper surface of the ring portion 62 and the upper surface of the connecting portion 61 contacting the stay portion. That is, the ground current is the ground member screw hole 44 → screw through hole 66 / female screw cylinder 65 → frame portion 60 → connecting portion 6
1. Flow in the order of the ring portion 62 and the stay portion. In this way, in the present embodiment, the earth member 6 forms the earth conduction path.

Next, effects peculiar to the electric circuit protection device of this embodiment will be described. The substrate 4 is screwed to the first case 2. The substrate 4 is firmly fixed by this screwing. Therefore, according to this embodiment, it is easy to ensure the detection accuracy of the acceleration detection means. In addition, the screw connection secures the continuity of the substrate 4. That is, the fixing and the ensuring of continuity are achieved by the joining male screw 7
1 and a female screw cylinder. Therefore, according to this embodiment, the number of parts can be reduced. Further, when screwed, the ground member screw hole 44, the screw through hole 66, and the female screw cylinder 65 are pressed against each other. Therefore, these members are less likely to be separated from each other. Also,
The screw through hole 66 and the ring portion 62 are arranged close to each other. For this reason, according to the present embodiment, there is little risk of interruption of conduction. Further, the electric resistance in the earth conduction path is also small. Further, the grounding member 6 can be easily embedded in the first case 2.

(4) Fourth Embodiment The difference between this embodiment and the third embodiment is that the second case made of metal is provided. In addition, the vehicle mounting portion projects in the same direction as the connector. Therefore, only the differences will be described here.

First, differences in the configuration of the electric circuit protection device of this embodiment will be described. FIG. 5 shows an exploded view of the electric circuit protection device of this embodiment. The members corresponding to those in FIG. 4 are indicated by the same symbols.

In the first case 2, one of the two vehicle mounting portions 20 is juxtaposed with the connector 5. Further, a screw seat 25 is embedded in two of the four earth member holding columns 21 which are diagonally located. Screw seat 25
Is made of metal and has a cylindrical shape.

The earth member 6 includes a ring portion 62 and a connecting portion 6.
1, a frame portion 60, and a female screw cylinder 65. The ring portion 62 is exposed from the inner peripheral surface of the vehicle mounting hole 22.
The connecting portion 61 and the frame portion 60 are connected in an L shape. The frame portion 60 first extends downward in the side wall of the first case 2 from the connecting portion 61. Subsequently, the frame portion 60 projects inward from the side wall of the first case 2 and extends into the two ground member holding columns 21 having no screw seat 25. A female screw cylinder 65 is arranged at the protruding end of the frame portion 60. That is, the female screw cylinder 65 is embedded in the ground member holding column 21.

The substrate 4 has a rectangular plate shape. Screw through holes 45 are formed in the four corners of the substrate 4. That is, a total of four screw through holes 45 are arranged. The second case 3 is made of metal and has a rectangular plate shape.
The second case 3 has a step portion 31. The step portions 31 are formed at the four corners of the second case 3. That is, a total of four step portions 31 are arranged. A screw through hole 32 is formed in the step portion 31. This screw through hole 32
The screw through hole 45 and the screw seat 25 or the female screw cylinder 65 are vertically connected in series.

Next, a method of assembling the electric circuit protection device of this embodiment will be described. In the assembling, the male screw 72 is passed through the screw through hole 32 and the screw through hole 45 from above and screwed to the screw seat 25 or the female screw cylinder 65. Then, the second case 3 and the substrate 4 are connected to the first case 2
Fixed to. Further, the connector 5 and the electric circuit for the airbag are soldered.

Next, a method of mounting the electric circuit protection device of this embodiment on the vehicle body will be described. In the mounting, first, the stay portion (not shown) of the vehicle body is brought into contact with the upper surface of the vehicle mounting portion 20. Next, the male screw 7 is passed through the ring portion 62 from below. Then, the male screw 7 is screwed into the device mounting hole (not shown) of the stay portion.

Next, the earth conduction path of the electric circuit protection device of this embodiment will be described. The earth conduction path of the present embodiment is formed by the earth member 6. Board 4
The ground member 6 and the ground member 6 are electrically connected by screwing the screw through hole 45 and the female screw cylinder 65. Further, the earth member 6 and the vehicle body are connected to each other by the ring portion 6
2 and the device mounting hole are electrically connected by being screwed. That is, the ground current is the screw through hole 45 → female screw cylinder 65 → frame portion 60 → connection portion 61 →
It flows in the order of the ring portion 62 and the stay portion. In this way, in the present embodiment, the earth member 6 forms the earth conduction path.

Next, effects peculiar to the electric circuit protection device of this embodiment will be described. Substrate 4 and second case 3
Is fastened to the first case 2 by a single male screw 72. Therefore, the number of assembling steps can be reduced. Further, the female screw cylinder 65 and the ring portion 62 are arranged close to each other. For this reason, according to the present embodiment, there is little risk of interruption of conduction. Further, the electric resistance in the earth conduction path is also small. Further, the grounding member 6 can be easily embedded in the first case 2.

(5) Fifth Embodiment The difference between this embodiment and the first embodiment is that the second case made of metal and the earth frame form an earth conduction path. Therefore, only the differences will be described here.

First, differences in the configuration of the electric circuit protection device of this embodiment will be described. FIG. 6 shows an exploded view of the electric circuit protection device of this embodiment. The members corresponding to those in FIG. 1 are indicated by the same symbols.

Four earth member holding columns 2 of the first case 2
1, a screw seat 25 is embedded. The screw seat 25 is
It is made of metal and has a cylindrical shape. The earth frame 8 is
It is made of brass and has a ring portion 82, a connecting portion 81 and a frame body portion 80.
Consists of. The ring portion 82 is embedded in the vehicle mounting portion 20. The ring portion 82 has a short axial length. The frame body portion 80 has a square shape. Frame body 80
Are arranged along the inner surface of the side wall of the first case 2.
The frame body portion 80 is exposed from the inner surface of the first case 2. The connecting portion 81 has a prismatic shape. Connecting part 8
1 connects the ring portion 82 and the frame body portion 80.

The substrate 4 has a rectangular plate shape. Screw through holes 45 are formed in the four corners of the substrate 4. That is, a total of four screw through holes 45 are arranged. A second case contact portion 46 is arranged around each screw through hole 45.

The second case 3 is made of metal and has a rectangular plate shape. The second case 3 has a step portion 31.
The step portions 31 are formed at the four corners of the second case 3.
That is, a total of four step portions 31 are arranged. A screw through hole 32 is formed in the step portion 31. The screw through hole 32, the screw through hole 45, and the screw seat 2
5 is in series in the vertical direction.

Next, a method of assembling the electric circuit protection device of this embodiment will be described. In the assembling, the male screw 72 is passed through the screw through hole 32 and the screw through hole 45 from above and screwed to the screw seat 25. Then, the second case 3 and the substrate 4 are fixed to the first case 2. At the same time, the step portion 31 is pressed against the second case contact portion 46. At the same time, the connector 5 and the electric circuit for the airbag are soldered.

Next, a method of mounting the electric circuit protection device of this embodiment on the vehicle body will be described. In the mounting, first, the stay portion (not shown) of the vehicle body is brought into contact with the upper surface of the vehicle mounting portion 20. Next, the male screw 7 is passed through the ring portion 82 from below. Then, the male screw 7 is screwed into the device mounting hole (not shown) of the stay portion.

Next, the earth conduction path of the electric circuit protection device of this embodiment will be described. The earth conduction path of the present embodiment is formed by the earth frame 8 and the second case 3. The board 4 and the second case 3 are electrically connected by the second case contact portion 46 coming into contact with the step portion 31. Further, the second case 3 and the earth frame body 8 are electrically connected by the side wall 33 of the second case 3 being inscribed in the frame body portion 80. Also, the earth frame 8
The upper surface of the ring portion 82 and the connecting portion 81
The upper surface is in electrical contact with the stay portion. That is, the ground current is the second case contact portion 46 → step portion 31 → side wall 33 → frame body portion 80 → coupling portion 81.
-The flow flows in the order of the ring portion 82 and the stay portion. Thus, in the present embodiment, the earth frame body 8 and the second case 3 form an earth conduction path.

Next, the effect peculiar to the electric circuit protection device of this embodiment will be described. Substrate 4 and second case 3
Are screwed to the first case 2 with a single male screw 72. Therefore, the number of assembling steps can be reduced.
Further, since the second case 3 is a part of the ground conduction path, a relatively wide path cross-sectional area can be secured.
The board 4 and the second case 3 are electrically connected by the second case contact portion 46 coming into contact with the step portion 31. Therefore, a relatively wide contact area can be secured. The second case 3 and the earth frame body 8 are electrically connected by the side wall 33 coming into contact with the frame body portion 80. Also in this respect, a relatively wide contact area can be secured.

(6) Sixth Embodiment The difference between this embodiment and the fifth embodiment is that the ground conduction path is formed only by the second case. Therefore, only the differences will be described here.

First, differences in the configuration of the electric circuit protection device of this embodiment will be described. FIG. 7 shows an exploded view of the electric circuit protection device of this embodiment. The members corresponding to those in FIG. 6 are indicated by the same symbols.

The second case 3 is provided with a mounting portion contact portion 34. A screw through hole 35 is formed in the mounting portion contact portion 34. The screw through hole 35 is vertically connected in series with the vehicle mounting hole 22. The vehicle mounting portion 20 is provided with a recess 26 that is symmetrical in shape to the mounting portion contact portion 34.

Next, a method of assembling the electric circuit protection device of this embodiment will be described. In the assembling, the male screw 72 is passed through the screw through hole 32 and the screw through hole 45 from above and screwed to the screw seat 25. Then, the second case 3 and the substrate 4 are fixed to the first case 2. At the same time, the step portion 31 is pressed against the second case contact portion 47. At the same time, the attachment contact portion 34 is inserted into the recess 26. At the same time, the connector 5 and the electric circuit for the airbag are soldered.

Next, a method of mounting the electric circuit protection device of this embodiment on the vehicle body will be described. In the mounting, first, the stay portion (not shown) of the vehicle body is brought into contact with the upper surface of the vehicle mounting portion 20. Next, the male screw 7 is passed through the vehicle mounting hole 22 and the screw through hole 35 from below.
Then, the male screw 7 is screwed into the device mounting hole (not shown) of the stay portion.

Next, the earth conduction path of the electric circuit protection device of this embodiment will be described. The earth conduction path of the present embodiment is formed only by the second case 3. The board 4 and the second case 3 are electrically connected by the second case contact portion 47 coming into contact with the step portion 31. Further, the second case 3 and the vehicle body are electrically connected by the upper surface of the attachment portion contact portion 34 contacting the stay portion. That is, the ground current is the second case contact portion 47 → step portion 31 → mounting portion contact portion 34 →
It flows in the order of the stay section. In this way, in the present embodiment, the second case 3 forms a ground conduction path.

Next, the effect peculiar to the electric circuit protection device of this embodiment will be described. The ground conduction path is formed only by the second case 3. Therefore, it is not necessary to separately arrange a member for ensuring conduction. Therefore, according to this embodiment, the number of parts can be reduced. Also, the assembly becomes easy.

(7) Others The embodiments of the present invention have been described above. However, the embodiment is not particularly limited to the above embodiment. It can also be implemented in various modifications and improvements that can be made by those skilled in the art. For example, in the above embodiment, the second case has a plate shape, but the second case may have a box shape. Further, in the above embodiment, the second case is arranged on the first case, but it may be upside down. Further, in the above embodiment, the first case and the connector are made of PBT, but the materials of the first case and the connector are not particularly limited as long as they are resin. Further, in the above embodiment, the earth member and the earth frame body are formed of brass, but the materials of the earth member and the earth frame body are not particularly limited. Other metals may be used. Also,
It may be a conductive resin. Further, in the above-described embodiment, the ground member or the ground frame body is embedded in the first case by insert molding. However, for example,
First, the recess may be formed at the time of molding the first case, and the ground member or the ground frame body may be press-fitted into this recess after the molding of the first case. Further, in the above embodiment, two vehicle mounting portions are arranged, but the number of vehicle mounting portions arranged is not particularly limited. Further, in the above embodiment, the connector and the electric circuit for the air bag, the engagement piece for the substrate and the substrate, or the contact portion for the substrate and the contact portion for the ground member are connected by soldering. However, these members may be connected by the biasing force of the spring, for example. By doing so, soldering is not necessary, and the assembling is easy.

[0094]

According to the present invention, it is possible to provide an electric circuit protection device having a first case made of resin and capable of grounding a substrate without a vehicle wire harness connecting connector.

[Brief description of drawings]

FIG. 1 is an exploded view of an electric circuit protection device according to a first embodiment.

FIG. 2 is an exploded view of the electric circuit protection device according to the first embodiment with a substrate fixed to a first case.

FIG. 3 is an exploded view of an electric circuit protection device according to a second embodiment.

FIG. 4 is an exploded view of an electric circuit protection device according to a third embodiment.

FIG. 5 is an exploded view of an electric circuit protection device according to a fourth embodiment.

FIG. 6 is an exploded view of an electric circuit protection device according to a fifth embodiment.

FIG. 7 is an exploded view of an electric circuit protection device according to a sixth embodiment.

FIG. 8 is an exploded view of a conventional electric circuit protection device.

[Explanation of symbols]

1: Electrical circuit protection device, 2: First case, 20: Vehicle mounting portion, 21: Ground member holding column, 22: Vehicle mounting hole, 2
3: first engaging hole (first engaging portion), 24: screw seat, 25:
Screw seat, 26: concave part, 3: second case, 30: second engaging claw (second engaging part), 31: step, 32: screw through hole, 3
3: side wall, 34: contact portion for mounting portion, 35: screw through hole,
4: substrate, 40: storage chamber, 41: ground member engaging hole,
42: notch part, 43: screw through hole, 44: ground member screw hole, 45: screw through hole, 46: second case contact part, 47: second case contact part, 5: connector, 6:
Ground member, 60: frame part, 61: connecting part, 62:
Ring portion, 63: board engaging piece, 64: board contact portion,
65: Female screw cylinder, 66: Screw through hole, 7: Male screw, 7
0: Male screw, 71: Joined male screw, 72: Male screw, 8: Earth member, 80: Frame part, 81: Connection part, 82: Ring part.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuyoshi Shimizu             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO (72) Inventor Keisuke Imai             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 3D054 EE47 FF16

Claims (11)

[Claims] 1. A first case having a vehicle mounting portion fixed to a vehicle body, a second case partitioning a storage chamber between the first case and a board having an electric circuit arranged in the storage chamber. And a connector for electrically connecting the electric circuit and an external device, wherein the first case is made of resin, and a ground is provided between the substrate and the vehicle body. An electrical circuit protection device, characterized in that a conduction path is formed. 2. The electric circuit protection device according to claim 1, wherein the connector is formed integrally with the first case. 3. The first case has a first engaging portion, the second case is made of resin, and has a second engaging portion that engages with the first engaging portion. Electrical circuit protection device. 4. The grounding conductive path is formed by a grounding member that is embedded in the first case and has one end extending to the vehicle mounting portion and the other end having a substrate contact portion, and the substrate is The electric circuit protection device according to claim 1, further comprising a ground member contact portion with which the substrate contact portion contacts. 5. The board contact portion is a board engagement piece, and the ground member contact portion is a ground member engagement hole into which the board engagement piece is inserted and locked. Item 4. The electric circuit protection device according to item 4. 6. The board contact portion is a female screw cylinder, the ground member contact portion is a ground member screw hole in series with the female screw cylinder, and further penetrates the ground member screw hole. The electrical circuit protection device according to claim 4, wherein the electrical circuit protection device has a joining male screw screwed to the female screw cylinder. 7. The electric circuit protection device according to claim 4, wherein the vehicle mounting portion and the board contact portion are arranged close to each other. 8. The electric circuit protection device according to claim 1, wherein the second case is made of metal, and the second case forms at least a part of the ground conduction path. 9. The earth conducting path is embedded in the first case, has one end extending to the vehicle mounting portion and the other end having a frame body portion, and is inscribed in the frame body portion. The electric circuit protection device according to claim 8, wherein the electric circuit protection device is formed by a second case, and the substrate has a second case contact portion that contacts the second case. 10. The ground conducting path is formed by the second case having a mounting portion contact portion that contacts the vehicle mounting portion, and the substrate is a second case contact portion that contacts the second case. 9. The electric circuit protection device according to claim 8, which comprises: 11. The electric circuit is an electric circuit for an airbag having acceleration detection means for detecting a collision acceleration of a vehicle, and the substrate is screwed to at least one of the first case and the second case. The electric circuit protection device according to any one of claims 1 to 10.