Seal structure for electronic control device

#The present invention relates to a seal structure for an electronic control device, which is favorable for an engine control unit or an automatic transmission control unit.

#As an example of the seal structure for the electronic control device, it is disclosed in Japanese Patent Provisional Publication No. 2009-070855 (hereinafter is referred to as “JP2009-070855”). In JP2009-070855, the seal structure of a so-called connector-side-mounted type of electronic control device, in which a part of the connector fixed to one side of a circuit board is exposed to an outside of a casing from a window of the casing, is disclosed. Both upper and lower surfaces of the connector are sandwiched between and by a pair of connector sandwiching members of the casing from width direction of the circuit board. A casing seal portion, which is filled with a sealing material, is provided at a fitting surface portion between periphery edge portions of the pair of connector sandwiching members. Likewise, a connector seal portion, which is filled with the sealing material, is provided at a fitting surface portion between an outer peripheral surface of the connector and an inner peripheral surface of the casing. The casing seal portion is formed by a seal groove and a protruding line which are provided respectively at one side and the other side of the pair of connector sandwiching members, also the connector seal portion is formed by a seal groove and a protruding line which are provided respectively at one side and the other side of the connector and the casing so as to secure a predetermined seal length (also called a leak path). A U-shaped gap, whose cross section is U-shape, formed between these seal groove and protruding line is filled with the sealing material.

#In JP2009-070855, in the case of the seal structure for the electronic control device in which a part of the connector is exposed to the outside of the casing, in order to ensure sealing performance of an inside of the casing, besides providing the casing seal portion at the periphery edge portions of the connector sandwiching members, the connector seal portion is provided also at a circumference of the connector. Then, these casing seal portion and connector seal portion are united or merged with each other at a part where the both connector sandwiching members are fitted together at the circumference of the connector. In this case, however, since a seal structure of this merged part is a so-called three-way seal structure in which the two seal portions, both of which are an endless extending ring-shaped seal portion, meet or cross at this merged part, it is difficult to ensure the sealing performance.

#FIG. 1 is a perspective exploded view of an electronic control device that employs a seal structure of an embodiment of the present invention.

#FIG. 2 is a sectional view showing the seal structure of a connector part, of the embodiment.

#FIG. 3 is a perspective view showing the seal structure of the connector part, with a cover removed, of the embodiment.

#According to the present invention, besides providing a normal seal groove and a normal protruding line, an auxiliary seal groove and an auxiliary protruding line are provided at a merged part where two seal portions meet, and a gap between these auxiliary seal groove and auxiliary protruding line is filled with a sealant. It is therefore possible to secure an equivalent seal length by the same quantity of sealant as that of a normal seal portion, and decrease of the sealing performance of this merged part can be suppressed or avoided.

#Embodiments of a seal structure for the electronic control device of the present invention will now be explained below with reference to the drawings.

#In the following description, a case where the seal structure for the electronic control device is employed in an engine control unit of a vehicle will be explained in detail.