JP5865284B2 - Electronic control unit - Google Patents

Description

  The present invention relates to an electronic control unit (ECU) that electrically controls activation of an airbag installed in a vehicle as a safety device, for example.

  The airbag device protects an occupant from an impact at the time of collision by ejecting gas at the time of collision and deploying the airbag. The airbag device is electrically controlled for activation by an electronic control unit.

  As shown in FIG. 8, this electronic control unit has an electronic circuit board 3 attached with a connector 2 connected to a wire harness attached to a housing 1 together with a back cover 4, and the electronic circuit board 3 is attached to the housing 1 and the back cover 4. It is configured to be isolated from the outside.

  The electronic control unit is attached to the vehicle, for example, by a flange portion 4a in which the back cover 4 protrudes outward so as to be exposed from the housing 1.

  The electronic circuit board includes a control circuit that outputs a control signal for deploying the airbag when it is determined that the vehicle has collided based on the acceleration or deceleration detected by the sensor.

  Incidentally, water droplets generated by condensation or the like may fall on the electronic control unit. Even in such a case, for example, Patent Document 1 proposes a structure that prevents the water droplets from entering the housing and damaging the electronic circuit board.

  Patent Document 1 discloses a water droplet in the housing without deteriorating workability at the time of connector connection by devising a ridge covering the upper part of the connector attached to the housing and a side wall of the housing continuous to the ridge. It is described that the intrusion is prevented.

  However, the water drops fall not only on the top surface of the housing constituting the electronic control unit but also on the flange portion of the back cover. Among these, when the water droplet 5a collected on the top surface 1a of the housing 1 exceeds a certain amount, it flows down on the flange portion 4a of the back cover 4 through the vertical wall outer surface 1b of the housing 1 as shown in FIG. .

  When the water droplet 5a flows down on the flange portion 4a of the back cover 4, an external force is applied to the water droplet 5b collected on the flange portion 4a. As a result, a part of the water droplet 5b collected on the flange portion 4a becomes part of the housing 1 and the back cover. 4 is pushed into the housing 1 through the gap d1 (see FIG. 10) and enters.

  The infiltrated water drops enter the mating surface of the back cover 4 and the electronic circuit board 3 as shown by a thick arrow in FIG. 10, and further enter the inside of the housing 1 by capillary action. If the water droplets that have entered the interior contain salt, the salt crystal remains on the electronic circuit board 3 after the water has evaporated.

  When the infiltration of water droplets into the housing is repeated, the salt crystal grows and damages the electronic circuit board and the elements mounted on the electronic circuit board. As described above, the structure proposed in Patent Document 1 cannot solve the intrusion of water droplets that may damage the electronic circuit board and the elements mounted on the electronic circuit board.

Japanese Patent No. 4588690

  The problem to be solved by the present invention is that, when a flange portion for mounting on a vehicle is formed on the back cover, in the structure proposed in Patent Document 1, water droplets collected on the flange portion of the back cover, It is a point that it cannot respond to the intrusion from the gap between the housing and the back cover.

  The electronic control unit of the present invention effectively prevents water droplets from entering the housing through the gap between the flange portion of the housing and the back cover of the electronic control unit in which the flange portion for mounting on the vehicle is formed on the back cover. The purpose is to do.

That is, the electronic control unit of the present invention is
An electronic circuit board incorporating a control circuit for outputting a control signal;
A connector attached to the electronic circuit board;
A frame that surrounds the periphery, and a back cover that includes a flange that extends outward from the frame to be attached to the vehicle;
A first vertical wall having an opening for disposing the connector; a second vertical wall located at a position facing the first vertical wall; and attaching the electronic circuit board together with the back cover, A box-shaped housing for isolating the mounted electronic circuit board from the outside;
An electronic control unit comprising:
When the electronic control unit is attached to the housing together with the electronic circuit board and the back cover, a gap is formed between the second vertical wall and the flange portion of the back cover ,
The most important feature is that a groove extending in the width direction of the back cover is provided in the frame portion obtained by extending the flange portion of the back cover on the side having the gap .

  In the present invention, since a groove extending in the width direction of the back cover is provided in the frame portion obtained by extending the flange portion of the back cover, water droplets that have flowed down to the flange portion of the back cover try to enter the housing by capillary action. Shut off.

  The groove may be a vertical groove having a depth in the thickness direction of the back cover or a horizontal groove having a depth in the depth direction of the back cover.

  In the present invention, the width direction of the back cover means a direction parallel to the first and second vertical walls of the housing when the electronic control unit is viewed from the plane direction. Further, the depth direction of the back cover means a direction orthogonal to the first and second vertical walls of the housing when viewed from the same direction as described above. The thickness direction of the back cover refers to a direction from the back cover toward the top surface of the housing in a state where the back cover is attached to the housing.

  In the present invention, a groove extending in the width direction of the back cover is provided in the frame part obtained by extending the flange part of the back cover, so that water droplets that have flowed down to the flange part of the back cover try to enter the housing by capillary action. Can be effectively prevented from entering water droplets into the housing.

It is the figure which showed the electronic control unit of this invention, (a) is the disassembled perspective view seen from the connector side, (b) is the perspective view seen from the top | upper surface direction of the non-connector side, (c) is from the anti-connector side. FIG. It is a figure explaining the state from which the water droplet which flowed down to the flange part of the back cover in the 1st example of this invention is discharged | emitted. It is a figure similar to FIG. 2 in the 2nd example of this invention. It is a figure explaining the other space part which exposes the edge part of a groove | channel in the electronic control unit of this invention, (a) is the perspective view which looked at the back cover from the back side, (b) is the A section enlarged view of (a). (C) is the B section enlarged view of (b). It is the figure which showed the crystal | crystallization of the salt which generate | occur | produced after performing the salt spray test with respect to the 1st example of the electronic control unit of this invention, (a) removes a back cover from an electronic control unit, and shows an electronic circuit board part. An exposed view, (b) is a view of the removed back cover as viewed from the inside of the housing. It is the same figure as FIG. 5 which showed the crystal | crystallization of the salt which generate | occur | produced after performing the salt spray test with respect to the 2nd example of the electronic control unit of this invention. It is the same figure as FIG. 5 which showed the crystal | crystallization of the salt which generate | occur | produced after performing the salt spray test with respect to the conventional electronic control unit which does not provide a groove | channel. It is the figure which showed the conventional electronic control unit, (a) is the perspective view seen from the top | upper surface side, (b) is the figure which cut and showed the (a) figure by center part. In the conventional electronic control unit, it is the figure explaining the state of the water droplet which flows into the flange part of a back cover from the top | upper surface of a housing. In the conventional electronic control unit, it is the figure explaining the state in which the water droplet which flowed down to the flange part of a back cover penetrate | invades in a housing.

  The present invention has been made for the purpose of effectively preventing water droplets from entering the housing from the gap between the flange portion of the housing and the back cover.

  And the objective was implement | achieved by providing the groove | channel extended in the width direction of a back cover in the frame part which extended the flange part of the back cover.

Hereinafter, an embodiment for carrying out the present invention will be described with reference to FIGS.
Reference numeral 1 denotes a resin housing, for example, which is formed in a box shape in which a bottom wall 1c for attaching a metal back cover 4 and a first vertical wall 1d for arranging the connector 2 are opened. In the present invention, for example, screw holes for integrally attaching the electronic circuit board 3 and the back cover 4 are provided in substantially four corners of the bottom wall 1c of the housing 1 in the step portion 1e.

  3 is an electronic circuit board on which, for example, a sensor or an electronic device is mounted. When it is determined that the vehicle has collided based on the acceleration or deceleration detected by the sensor, a control signal is output to deploy the airbag. The circuit is built in.

  The connector 2 is attached to one end of the electronic circuit board 3 so that the connection surface 2a to the wire harness faces outward. The electronic circuit board 3 with the connector 2 attached is integrally attached to the inside of the housing 1 together with the back cover 4 in a state of being arranged in the frame portion 4b surrounding the back cover 4 and isolated from the outside. Is done.

  Thus, the electronic control unit in a state in which the electronic circuit board 3 is surrounded by the housing 1 and the back cover 4 and is isolated from the outside is extended outward from the frame portion 4 b of the back cover 4 so as to be exposed from the housing 1. It is attached to the vehicle by the flange portion 4a. The flange portion 4a is provided in a total of three places, for example, one place on the first vertical wall 1d side of the housing 1 and two places on the second vertical wall 1f side facing the first vertical wall 1d.

  In the state of being attached to the vehicle, when the water droplets flow down from the top surface 1a of the housing 1 onto the water droplets collected on the flange portion 4a exposed outward from the second vertical wall 1f, a part of the water droplets is second. It enters the housing 1 through the gap d1 between the vertical wall 1f and the flange portion 4a.

  Therefore, in the present invention, the frame cover 4b of the back cover 4 with the flange part 4a extended, the back cover parallel to the first and second vertical walls 1d and 1f of the housing 1 when the electronic control unit is viewed from the plane. Four grooves extending in the width direction are provided.

  For example, FIGS. 1 and 2 show a longitudinal groove 6 a having a depth in the thickness direction of the back cover 4 from the back cover 4 toward the top surface 1 a of the housing 1. 3 shows a lateral groove 6b having a depth in the depth direction of the back cover 4 perpendicular to the first and second vertical walls 1d and 1f of the housing 1 when the electronic control unit is viewed from the top.

  By providing such grooves 6a and 6b, it is possible to block the water droplets 5b flowing down to the flange portion 4a of the back cover 4 from entering the inside of the housing 1 by capillary action (FIGS. 2 and 3). reference).

  At this time, if the end portions of the grooves 6a and 6b are exposed in the space portion S between the housing 1 and the back cover 4, water droplets that have entered through the gap d1 between the housing 1 and the back cover 4 are transferred to the space portion S. Therefore, it is possible to prevent water droplets from entering the housing 1 more effectively.

  The space portion S may be a stepped portion 4c provided on the back cover 4 in order to integrally attach the electronic circuit board 3, the housing 1, and the back cover 4 (see FIG. 4). The step 4 c is provided at a position corresponding to the step 1 e of the housing 1. In this step part 4c, the inside of the housing 1 is exposed, and the end parts of the groove parts 6a and 6b can be exposed.

  When the vertical groove 6 a shown in FIG. 2 is employed, the deepest portion may be formed so as to be lower than the flange portion 4 a of the back cover 4. By doing so, the water can be drained more effectively.

  FIG. 5 shows the result of the salt spray test performed on the electronic control unit of the present invention provided with the longitudinal groove 6a shown in FIG. 2, and the salt water was applied to the electronic control unit of the present invention provided with the lateral groove 6b shown in FIG. The result of the spray test is shown in FIG. (A) The figure shows what removed the back cover 4 from the electronic control unit to expose the electronic circuit board 3, and (b) shows the removed back cover 4 from the inside of the housing 1. . Moreover, the result of having performed the salt spray test with respect to the electronic control unit which does not provide a groove | channel is shown in FIG.

  In the case of the present invention provided with a groove, as shown in FIGS. 5 and 6B, no salt crystals are seen in the frame portion 4b of the back cover 4, so that electronic components are mounted. Also on the surface of the electronic circuit board 3, no salt crystals were generated as shown in FIGS.

  On the other hand, in the conventional case where no groove is provided, as shown in FIG. 7B, salt crystals 7 were seen in the frame portion 4b of the back cover 4 with the flange 4a extended. As shown in FIG. 7A, the region where the salt crystals 7 are generated extends not only to the periphery of the electronic circuit board 3 on which the electronic components are mounted, but also to the mounting area of the electronic components.

  The present invention is not limited to the above examples, and the embodiments may be appropriately changed as long as they are included in the scope of the technical idea described in each claim.

  That is, the electronic control unit described above is a preferable example of the present invention, and other embodiments can be implemented or performed by various methods. In particular, the present invention is not limited to the detailed shape, size, configuration, and the like of the components shown in the accompanying drawings unless otherwise specified in the present specification. In addition, expressions and terms used in the present specification are for the purpose of explanation, and are not limited thereto unless specifically limited.

  For example, the housing 1 is not limited to resin but may be made of metal. Further, both ends of the grooves 6a and 6b may not be exposed at the space portion S between the housing 1 and the back cover 4, but only one of the ends may be exposed.

  In the above example, the vertical groove 6a or the horizontal groove 6b is provided, but both the vertical groove 6a and the horizontal groove 6b may be provided.

  The electronic control unit of the present invention described above is not limited to the one that controls the activation of the airbag deployment, but is effective for any device that controls the engine and the power steering.

DESCRIPTION OF SYMBOLS 1 Housing 1a Top surface 1b Vertical wall outer surface 1c Bottom wall 1d 1st vertical wall 1f 2nd vertical wall 2 Connector 2a Connection surface 3 Electronic circuit board 4 Back cover 4a Flange part 4b Frame part 6a Vertical groove 6b Horizontal groove d1 2nd vertical wall Between the flange and the flange part S The space between the housing and the back cover

Claims (5)

An electronic circuit board incorporating a control circuit for outputting a control signal;
A connector attached to the electronic circuit board;
A frame that surrounds the periphery, and a back cover that includes a flange that extends outward from the frame to be attached to the vehicle;
A first vertical wall having an opening for disposing the connector; a second vertical wall located at a position facing the first vertical wall; and attaching the electronic circuit board together with the back cover, A box-shaped housing for isolating the mounted electronic circuit board from the outside;
An electronic control unit comprising:
When the electronic control unit is attached to the housing together with the electronic circuit board and the back cover, a gap is formed between the second vertical wall and the flange portion of the back cover ,
An electronic control unit, wherein a groove extending in a width direction of the back cover is provided in the frame portion obtained by extending the flange portion of the back cover on the side having the gap .   The electronic control unit according to claim 1, wherein the groove is a vertical groove having a depth in a thickness direction of the back cover.   The electronic control unit according to claim 2, wherein a deepest portion of the vertical groove is located at a position lower than a flange portion of the back cover.   The electronic control unit according to claim 1, wherein the groove is a lateral groove having a depth in a depth direction of the back cover.   The electronic control unit according to claim 1, wherein an end portion of the groove on the back cover is exposed in a space portion between the housing and the back cover.

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