Waterproof box and electrical junction box having the same

The waterproof box includes a body case and a cover mounted to the body case by making a hook portion at one end of the cover engaged with a projection at one end of the body case and rotatably moving the cover around the hook portion. The one end of the respective body case and the cover has a double-walled structure having an outer wall and an inner wall. With the cover mounted to the body case, the outer wall of the body case is located inside the outer wall of the cover, the inner wall of the cover is located inside the outer wall of the body case, the inner wall of the body case is located inside the inner wall of the cover, and the outer wall of the body case and the inner wall of the cover are arranged with a space between each other.

This application is on the basis of Japanese Patent Application No. 2011-169422, the contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a waterproof box used for example in an electrical junction box mounted to a motor vehicle.

BACKGROUND ART

A motor vehicle is mounted with various electronic equipments. An electrical junction box is provided at a suitable location in the motor vehicle to supply electricity and transmit signals to those electronic equipments mounted in the motor vehicle. The term “electrical junction box” used herein collectively means a junction block or box, a fuse block or box and a relay block or box.

This electrical junction box utilizes a waterproof box for preventing water from entering inside the electrical junction box during driving in the rain or during car washing.FIG. 9shows a cross-sectional perspective view of a conventional waterproof box used in a conventional electrical junction box (refer for example to Japan Patent Application Publication No. 2010-130705).

A conventional waterproof box201shown inFIG. 9includes a body case203and a cover202mounted to the body case203so as to cover an opening of the body case203. The body case203includes a rectangular frame-like peripheral wall230. The cover202includes a rectangular upper wall223and a rectangular frame-like peripheral wall220extending perpendicularly from an outer periphery of the upper wall223. This peripheral wall220is provided with a water proof groove portion204formed at a tip end of the peripheral wall220into which a tip end of the peripheral wall230of the body case203is inserted. This waterproof groove portion204is composed of an outer wall221positioned outside of the tip end of the peripheral wall230and an inner wall222positioned inside of the tip end of the peripheral wall230.

In such manner, with the tip end of the peripheral wall230of the body case203inserted into the waterproof groove portion204of the cover202, the waterproof box201prevents water from entering inside from between the body case203and the cover202without using a packing.

Furthermore, although it is not shown inFIG. 9, the waterproof box201includes an engagement portion formed at one end202aof the cover202, and an engagement mating portion formed at one end203aof the body case203with which the engagement portion is engaged. Furthermore, there is provided a lock portion formed at the other end202bof the cover202and a lock receiving portion formed at the other end203bof the body case203and at which the lock portion is locked. When mounting the cover202to the body case203, firstly the engagement portion of the cover202is engaged with the engagement mating portion of the body case203, followed by rotatably moving the cover202around the engagement portion as a rotation center and make the lock portion locked at the lock receiving portion, thereby mounting the cover202to the body case203.

In the above-described waterproof box201, the length of the inner wall222adjacent to the one end202ais formed shorter than the length of the inner wall222adjacent to the other end202bin order to prevent the inner wall222of the waterproof groove portion204from hitting on the peripheral wall230of the body case203when rotatably moving the cover202around the engagement portion.

The electrical junction box having the waterproof box201described above has following drawback. That is, depending on a mounting situation of the electrical junction box on the motor vehicle, water may forcefully splatter onto the cover202adjacent to the one end202a, and in this case, the length of the inner wall222adjacent to the one end202ais not sufficient to prevent water from entering into the waterproof box.

SUMMARY OF INVENTION

In view of the above-described drawback, it is an object of the present invention to provide a waterproof box having improved waterproof property without using a packing, as well as to provide an electrical junction box having the waterproof box with improved waterproof property.

In order to achieve the above-described object, the present invention provides, according to a first aspect, a waterproof box having a body case and a cover mounted to the body case so as to cover an opening of the body case, wherein the cover is mounted to the body case by firstly making an engagement portion located at one end of the cover engaged with an engagement mating portion located at one end of the body case and then rotatably moving the cover around the engagement portion so that the cover is mounted to the body case, wherein each of the one end of the body case and the one end of the cover has a double-walled structure composed of an outer wall and an inner wall, and wherein with the cover mounted to the body case, the outer wall of the body case is located on inner side of the outer wall of the cover, the inner wall of the cover is located on inner side of the outer wall of the body case, the inner wall of the body case is located on inner side of the inner wall of the cover, and the outer wall of the body case and the inner wall of the cover are arranged with a space between each other.

Furthermore, according to a second aspect of the present invention, the waterproof box described above may further include a protrusion formed on an inner wall of the body case, the protrusion being arranged such that a tip end of the inner wall of the cover abuts on the protrusion.

Furthermore, according to a third aspect of the present invention, at least a portion of the inner wall of the cover may be arranged in contact with or adjacent to the inner wall of the body case in an overlapped fashion.

Furthermore, according to a fourth aspect of the present invention, there is provided an electrical junction box having the waterproof box according to any one of the first to third aspects described above.

According to the first aspect of the present invention described above, each of the one end of the body case and the one end of the cover has a double-walled structure composed of an outer wall and an inner wall, and with the cover mounted to the body case, the outer wall of the body case is located on inner side of the outer wall of the cover, the inner wall of the cover is located on inner side of the outer wall of the body case, the inner wall of the body case is located on inner side of the inner wall of the cover, and the outer wall of the body case and the inner wall of the cover are arranged with a space between each other. Consequently, there is provided a sufficient distance between the engagement portion as a rotation center and the inner wall of the cover. Thus, even with the inner wall of the cover being long, it is possible to prevent the inner wall of the cover hitting on the outer wall of the body case during the rotatable movement of the cover. Furthermore, when water has entered into a space between the outer wall of the body case and the inner wall of the cover, the inner wall of the body case located further inside can stop the water. Thus, a waterproof box having improved waterproof property can be provided without using a packing.

According to the second aspect of the present invention described above, the protrusion provided at the inner wall of the body case can prevent water from entering in to a space between the inner wall of the body case and the inner wall of the cover, thereby further improving the waterproof property of the waterproof box.

According to the third aspect of the present invention described above, at least a portion of the inner wall of the cover is arranged in contact with or adjacent to the inner wall of the body case in an overlapped fashion. Consequently, it is able to prevent water from entering into a space between the inner wall of the body case and the inner wall of the cover, thereby further improving the waterproof property of the waterproof box.

According to the fourth aspect of the present invention described above, an electrical junction box having improved waterproof property can be provided at low cost by employing the waterproof box according to any one of the first to third aspects described above.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

First Exemplary Embodiment

In the following, an electrical junction box having a waterproof box according to a first exemplary embodiment of the present invention is explained in reference withFIGS. 1 through 7. The electrical junction box10according to the present invention may be mounted to a motor vehicle for supplying electricity and transmitting signals to various electronic equipments mounted in the motor vehicle.

As shown inFIGS. 1 and 2, the electrical junction box10may include a waterproof box1, a cassette block5made of synthetic resin and mounted in the waterproof box1and a plurality of electronic components mounted to the cassette block5.

The waterproof box1may include a body case3, an upper cover2(corresponds to a cover described in claims) mounted to the body case3so as to cover an upper opening30aof the body case3, and a lower cover4mounted to the body case3so as to cover a lower opening30bof the body case3. Each of the body case3, the upper cover2and the lower cover4may be made of insulating synthetic resin and formed by well-known injection molding.

The body case3may include a frame-like peripheral wall39having an upper opening30aat an upper face and a lower opening30bat a lower face, a partition wall38(refer toFIG. 2) which divides a space inside of the peripheral wall39, a bracket11extending from one end3aof the peripheral wall39and arranged to be fixed using a bolt to a vehicle body panel and such, a pair of plate-like projections7projecting from the one end3aof the peripheral wall39, a lock receiving portion9provided at the other end3bof the peripheral wall39at which a lock portion8of the upper cover2is locked, and a lock receiving portion37provided at an outer face of the peripheral wall39at which a lock portion47of the lower cover4is locked.

The upper cover2may include a rectangular upper wall28, a rectangular frame-like peripheral wall29extending perpendicularly from an outer periphery of the upper wall28, a pair of hook portions6(corresponds to an engagement portion described in claims) extending from one end2aof the peripheral wall29and arranged to engage with the projection7(corresponds to an engagement mating portion described in claims), and the lock portion8arranged at the other end2bof the peripheral wall29. As shown inFIG. 4, the hook portion6extends from an outer surface of the peripheral wall29and is formed into a frame-like shape so that the projection7can be positioned inside the hook portion6. More specifically, the hook portion6extends from the outer surface of the peripheral wall29in a direction perpendicular to the outer surface of the peripheral wall29, bends at a right angle in the middle and extends parallel to the outer surface of the peripheral wall29.

As shown inFIG. 5, the lower cover4may include a bottom wall, a peripheral wall49, a protrusion48projecting from an outer surface of the peripheral wall49and the lock portion47arranged at the outer surface of the peripheral wall49.

When mounting the upper cover2to the body case3as shown inFIG. 6, firstly the hook portion6formed at the one end2aof the upper cover2is engaged with or fitted to the projection7formed at the one end3aof the body case3. Then, the upper cover2is rotatably moved around the hook portion6as a rotation center, and the lock portion8formed at the other end2bof the upper cover2is pushed into the lock receiving portion9formed at the other end3bof the body case3, thereby mounting the upper cover2to the body case3.

When mounting the lower cover4to the body case3, the lower cover4and the body case3are moved towards each other along a depth direction of the body case3, followed by pushing the lock portion47of the lower cover4into the lock receiving portion37of the body case3, thereby mounting the lower cover4to the body case3.

Next, a waterproof structure of the waterproof box1is explained.

In order to improve the waterproof property of the waterproof box1, the peripheral wall39of the body case3may have, across the entire circumference, a double-walled structure composed of an outer wall31and an inner wall32. Similarly, the peripheral wall29of the upper cover2may also have a double-walled structure composed of an outer wall21and an inner wall22across the entire circumference. Under a situation where the upper cover2is mounted to the body case3, the outer wall31of the body case3is located on the inner side of the outer wall21of the upper cover2, the inner wall22of the upper cover2is located on the inner side of the outer wall31of the body case3, the inner wall32of the body case3is located on the inner side of the inner wall22of the upper cover2, and the outer wall31of the body case3and the inner wall22of the upper cover2are arranged with a space between each other. The length of the inner wall22of the upper cover2adjacent to the one end2amay be formed equal to the length of the inner wall22of the upper cover2adjacent to the other end2b. Furthermore, a tip end of the outer wall21of the upper cover2and an upper end of the outer wall31of the body case3may be formed into a stepped shape which abuts on or fits with respect to each other.

As described herein, in the present invention, the peripheral wall29,39may have a double-walled structure across the entire circumference. However, in an alternative embodiment, only one of the one end3aof the body case3and the one end2aof the upper cover2may have a double-walled structure. That is, in the present invention, at least one of the one end3aof the body case3and the one end2aof the upper cover2may have a double-walled structure.

As described above, the upper cover2is mounted to the body case3by rotatably moving the upper cover2around the hook portion6as a rotation center. In order to prevent the inner wall22of the upper cover2adjacent to the one end2afrom hitting on the outer wall31of the body case3during the rotatable movement of the upper cover, the space between the outer wall21and the inner wall22of the upper cover2adjacent to the one end2amay be formed larger than the space between the outer wall21and the inner wall22of the upper cover2adjacent to the other end2b. Referring toFIG. 6, the dotted line D shows a trajectory of the rotatable movement of a tip end of the inner wall22of the upper cover2. That is, in the present invention, in order to ensure a sufficient length of the inner wall22adjacent to the one end2awhich is adjacent to the rotation center to improve waterproof property, the space between the outer wall21and the inner wall22adjacent to the one end2ais formed large, so that the inner wall22is distanced from the hook portion6(the rotation center). In such manner, by providing the inner wall22having the sufficient length, the flow of water entered from between the outer wall21of the upper cover2and the outer wall31of the body case3can be direct in a downward direction. Furthermore, if, by any chance, water has entered into the space between the outer wall31of the body case3and the inner wall22of the upper cover2, the inner wall32of the body case3which is provided further inside of the body case3can prevent the water from entering deeper inside. Consequently, the electronic components can be protected from being affected by water.

Furthermore, the waterproof box1may be provided with the aforementioned bracket11formed at the one end3aof the body case3, rising possibility of water concentrating in a circled portion C shown inFIGS. 3 and 4. Thus, in order to improve the waterproof property especially at the circled portion C located between the inner walls22and32, the present invention is arranged such that a portion of the inner wall22of the upper cover2located in the circled portion C is formed close to the inner wall32of the body case3in an overlapped fashion. In this exemplary embodiment, as shown inFIG. 3, a portion of the inner wall32of the body case3located in the circled portion C is arranged closer to the outer wall31compared to the other portion, while the upper cover2has a flat shape.

Furthermore, in the present invention, at least a portion of the inner wall22of the upper cover2may be formed in contact with the inner wall32of the body case3in an overlapped fashion. As used herein, the expression “close to” and variation thereof means that the inner wall22and the inner wall32are arranged with a small space between each other, wherein the expression of “small space” is defined by a space smaller than the thickness of the inner wall22,32. A skilled person in the art may suitably select whether to arrange the inner wall22to be close to or to be continuous with the inner wall32according to the purpose of use or desired level of waterproof property of the waterproof box1.

Furthermore, as shown inFIG. 5, the body case3may be provided with a retainer wall33arranged so that a tip end of the peripheral wall49of the lower cover4is sandwiched and retained between the retainer wall33and the outer wall31. This retainer wall33may extend from the inner surface of the outer wall31towards the lower cover4. Furthermore, the retainer wall33may include a slant face35extending from the upper cover2towards the lower cover4as the slant face35approaches from the outer wall31towards the inner wall32. A bottom end of the outer wall31of the body case3is arranged to abut on the protrusion48formed on the lower cover4.

The following will explain water entry pathway in the waterproof box1in reference withFIG. 7. InFIG. 7, indicated arrows show a water flow direction. The waterproof box1is structured to prevent water from entering into the waterproof box1by the stepped shape formed at both of the tip end of the outer wall21of the upper cover2and the upper end of the outer wall31of the body case3; however, even if, by any chance, water has entered through a space between the outer walls21and31, the water is directed to flow through a space between the outer wall31and the inner wall22provided ahead and smoothly discharged towards the lower cover4. Moreover, even if water forcefully flows through a space between the outer wall31and the inner wall22, the slant face35formed on the retainer wall33can prevent the water from plashing towards the upper cover2, i.e. towards right above. Thus, the water flows between the retainer wall33and the inner wall32and discharged towards the lower cover4. The water which is discharged towards the lower cover4is then discharged out of the waterproof box1through a drainage hole (not shown). Moreover, the waterproof box1is structured to prevent water from entering into the waterproof box1by the protrusion48formed on the lower cover4and by the retainer wall33formed on the body case3; however, even if, by any chance, water has entered through a space between the outer wall31and the peripheral wall49and through a space between the retainer wall33and the peripheral wall49, the water is directed to flow between the peripheral wall49and the inner wall32and discharged out of the waterproof box1through the drainage hole of the lower cover4.

As described above, the present invention can improve waterproof performance without using a packing, thereby providing the electrical junction box10at low cost.

Second Exemplary Embodiment

The following will explain an electrical junction box having a waterproof box according to a second exemplary embodiment of the present invention in reference withFIG. 8. InFIG. 8, the same element as the first exemplary embodiment described above is indicated by the same reference sign to eliminate explanation.

As shown inFIG. 8, an electrical junction box10′ according to this exemplary embodiment may include a waterproof case1′ having a protrusion34formed on an inner wall32of a body case3′ and on which a tip end of an inner wall22of an upper cover2abuts. The structure of the waterproof box1′ is identical to that of the above-described waterproof box1except that the protrusion34is added.

According to the waterproof case1′, even if water, which has passed through a space between an outer wall31of the body case3′ and the inner wall22of the upper cover2, is impinged on a slant face35of a retainer wall33of the body case3′ and splattered towards the inner walls22,32, i.e. towards obliquely upward, the protrusion34which is arranged to block an entrance between the inner walls22and32can prevent the splattered water from entering into a space between the inner walls22and32. Consequently, the electronic components can be protected from being affected by the water.

According to the first and second exemplary embodiments described herein, the waterproof box is utilized in the electrical junction box; however, the waterproof box according to the present invention may also be utilized in a device other than the electrical junction box.

The exemplary embodiments described herein are only representative embodiments of the present invention and are not intended to limit the present invention. That is, the shown embodiments can be modified or changed in various ways without departing from the spirit and scope of the present invention.

REFERENCE SIGNS LIST