Electrical junction box

Bus bars to be contained in an electrical junction box are secured to insulation plates without caulking. An electrical junction box contains bus bars in a casing. The bus bars are disposed on an inner surface of the casing. Attaching pieces provided on the bus bars are inserted into and secured to receiving apertures provided in the casing. The attaching piece of each bus bar has a rectangular shape in cross section. Each receiving aperture in the casing is a circular aperture or a rectangular aperture. At least a part of an outer peripheral wall of each attaching piece contacts with an inner peripheral surface of each receiving aperture to restrain the attaching piece from moving in the aperture.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to JP 2008-277470 filed in Japan on Oct. 28, 2008, the disclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The exemplary embodiments are directed to an electrical junction box, and more particularly to a vehicle-mounted electrical junction box that can contain bus bars in a casing so as to readily and precisely position and fix the bus bars in the casing.

2. Background Art

A vehicle-mounted electrical junction box or the like contains circuit members including bus bars in a high-density manner in an interior. Usually, a plurality of bus bars and insulation plates are laminated alternately. Ribs provided on the insulation plates are inserted into caulking apertures to be caulked on the bus bars. A laminated body in which a plurality of the bus bars and insulation plates are integrally secured to one another is held on support portions or frames projecting from an inner surface of a casing. Tabs projecting from the bus bars secured to the insulation plates are inserted into terminal apertures provided in a connector-containing section, a fuse-containing section, or a relay-containing section in the casing. Thus, the bus bars are secured to the insulation plates and the tabs projecting from the bus bars are held in the terminal apertures in the casing.

For example,FIG. 10illustrates a process for producing a wiring plate assembly for electrical junction, which has been disclosed in JP HEI 9 (1997)-284952 A (assigned to the present applicant). As shown inFIG. 10, a bus bar100includes an upright tab101and a dummy tab102bent downward in an opposite direction from the tab101. The dummy tab102is inserted into and secured to a positioning recess111in a lower jig110for lamination. Then, the tab101is inserted into a terminal aperture121in an insulation plate120disposed above the bus bar100.

However, even in the above-described process, the bus bar100is previously provided with caulking apertures at desired positions to secure the bus bar100to the insulation plate120by caulking (see paragraph [0022] in JP HEI 9 (1997)-284952 A). Also, the above-described process requires that the dummy tab102be provided on the bus bar100and the lower jig110for lamination, which must be prepared to receive and hold the dummy tab102.

SUMMARY

Problems that the Invention is to Solve

As described above, heretofore, the bus bars to be contained in the electrical junction box are secured to the insulation plates by caulking. However, in order to hold the bus bars on the insulation plates by caulking, it is necessary to carry out the caulking after many ribs on the insulation plates have been inserted into the caulking apertures in the bus bars. This will increase the number of working steps. Furthermore, the insulation plates that are required to hold the bus bars and the insulation plate must be disposed above or below the bus bars. This will increase a weight and a size of the electrical junction box.

The exemplary embodiments address the above noted problems with an electrical junction box in which bus bars are precisely positioned and held in a casing without caulking the bus bars onto insulation plates.

The electrical junction box has a casing with an inner surface and receiving apertures. Bus bars are disposed on the inner surface of the casing. Attaching pieces disposed on the bus bars are inserted into and secured to the receiving apertures of the casing. Each of the attaching pieces having a rectangular cross-section, each of the receiving apertures being circular or rectangular, and at least a part of an outer peripheral wall of each attaching piece contacting with an inner peripheral surface of each receiving aperture to restrain the attaching piece from moving in the aperture, thereby positioning and holding the bus bars in the casing.

As described above, the electrical junction box according to the exemplary embodiments utilizes the upper wall or the bottom wall of the casing to secure the bus bars. The attaching pieces disposed on the bus bars are directly pressed into the receiving apertures in the upper wall or the bottom wall to utilize the casing itself as a securing member for the bus bars, thereby positioning and holding the bus bars in the casing without caulking the bus bars onto the insulation plate.

Because each attaching piece of each bus bar is rectangular while each receiving aperture is circular or rectangular, and because at least a part of the outer peripheral wall of each attaching piece contacts with an inner peripheral surface of each receiving aperture, it is possible to precisely position and hold the bus bars in the casing.

Thus, it is possible to eliminate or reduce the number of insulation plates used for securing a bus bar.

When each circular aperture in the casing receives each attaching piece of the bus bar having a rectangular shape in cross section, four corners of the attaching piece contacts with the inner peripheral surface of the circular aperture, thereby restraining the attaching piece from moving laterally or longitudinally. Because the rectangular aperture has the same shape as the cross section of the attaching piece, it is possible to restrain rotary movement of the attaching piece.

Thus, the shape of the receiving aperture in the casing can restrain the attaching piece of the bus bar from moving laterally or longitudinally, thereby surely and precisely securing the bus bar to the inner surface of the casing.

If the casing of the electrical junction box includes an upper casing member and a lower casing member, the bus bars are directly secured to either an upper wall of the upper casing member or a bottom wall of the lower casing member or to both casing members in the manner described above.

If the casing of the electrical junction box includes only one casing member, the bus bars are directly secured to a bottom wall of the casing.

Furthermore, if other bus bars, except the bus bars that are directly secured to the inner surface of the casing, are contained in the casing, the other bus bars are not caulked on an insulation plate. In an exemplary embodiment, the other bus bars are provided with a plurality of bent attaching pieces and inserted into and secured to receiving apertures in the insulation plate or are penetrated into openings defined by the insulation plate to project toward the casing so as to be inserted into and secured to receiving apertures in the inner surface of the casing.

Each attaching piece of each of the other bus bars is rectangular as is in the case with the bus bars described above, while each receiving aperture in the insulation plate is circular as in the case with the receiving aperture in the casing.

According to the above structure, it is possible to contain all of the bus bars laminated in multi-layers in the casing without caulking the bus bars onto the insulation plate.

Even if the bus bars are not secured to the upper wall or the lower wall of the casing directly, and the bus bars and insulation plates are laminated alternately, it is possible to reduce or eliminate all of the steps of caulking the bus bars onto the insulation plates by inserting the attaching pieces projecting from the bus bars into the receiving apertures in the inner surface of the casing.

In an exemplary embodiment, the rectangular aperture is provided with opposed inner peripheral surfaces and a rib and the rib is brought into contact with an outer peripheral surface of the attaching piece.

In particular, because the attaching piece is likely to move in a direction perpendicular to a long side of the rectangular aperture in the aperture, if the ribs are provided on the two opposed long sides of the rectangular aperture, it is possible to surely prevent the attaching piece from moving in the direction perpendicular to the long side of the rectangular aperture.

In an exemplary embodiment, a part of each of the bus bars is bent upward to provide a tab terminal adapted to be connected to electrical components, and each of the attaching pieces is bent in the same direction as that of the upward bent tab terminal.

Thus, if the attaching piece projects in the same direction as the tab terminal, it is possible to enhance a precision of positioning the tab terminal.

Because the connector-containing section, fuse-containing section, and relay-containing section are provided on the upper wall of the upper casing member and the bottom wall of the lower casing, if the attaching pieces of the bus bars are directly secured to the receiving apertures in the casing, it is possible to shorten a length of the tab terminal that is bent from each bus bar and projected to each containing section in the casing.

In an exemplary embodiment, the attaching piece to be inserted into and secured to the circular aperture is disposed near the tab terminal.

It is possible to restrain the attaching piece from moving laterally or longitudinally, when the attaching piece is inserted into and secured to the circular aperture. Consequently, it is possible to project the tab terminal in a proper posture from the tab terminal through-hole in the connector-containing section or the like and to enhance alignment of the tab, when the tab terminal is inserted into the tab terminal through-hole.

Effects of the Invention

As described above, in the electrical junction box according to the exemplary embodiments, because the bus bars are directly secured to the inner surface of the casing without caulking the bus bars onto the insulation plate, it is possible to eliminate the steps of caulking the bus bars onto the insulation plate, thereby lowering a cost in production.

In addition, it is possible to eliminate the insulation plate itself for securing the bus bar to be fixed on the casing, thereby decreasing the number of parts, facilitating weight reduction and downsizing of the electrical junction box.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring now to the drawings, embodiments of an electrical junction box will be described below.

An electrical junction box1shown inFIGS. 1A to 1Cis mounted in a motor vehicle.FIG. 1Ais a plan view of a first embodiment of the electrical junction box1.FIG. 1Bis a front elevation view of the electrical junction box1shown inFIG. 1A.FIG. 1Cis a bottom side view of the electrical junction box1shown inFIG. 1A.FIG. 2is a longitudinal section view of the electrical junction box taken along lines II-II inFIG. 1A.

The electrical junction box1includes an upper casing member2and a lower casing member3. The casing members2and3constitute a casing by locking them to each other. In an interior of the casing, bus bars9are directly secured to an inner surface of an upper wall2aof the upper casing member2. A printed board assembly includes an upper layer printed board5and a lower layer printed board7. An insulation plate6is disposed between the upper layer printed board5and the lower layer printed board7. The printed board assembly is disposed between the bus bars9and an insulation plate8.

As shown inFIG. 1A, the upper casing member2is provided on the upper wall2awith a fuse-containing section12, a relay-containing section13, a connector-containing section14, and a fusible-link-containing section15. Peripheral walls of the sections13to15project outward from an outer surface of the upper wall2a. Tab terminal through-holes12a,13a,14a, and15aare provided in the upper wall2athat defines bottom walls of the respective sections13to15. As shown inFIG. 1C, the lower casing member3is also provided on a bottom wall3awith a connector-containing section14.

The bus bars9are attached to the inner surface of the upper wall2aof the upper casing member2. The inner surface of the upper wall2ais formed into a configuration shown inFIG. 3.FIG. 4shows the inner surface of the upper wall2ato which the bus bars9are attached. A reference number16inFIG. 3designates reinforcement ribs.

A plurality of bus bars9(9-1to9-9) are formed by punching out a sheet of a conductive plate along a given pattern and then cutting the punched sheet. The bus bars9are attached to the inner surface of the upper wall2aof the upper casing member2.FIG. 5shows a development plan view of the respective bus bars9-1to9-9.

As shown inFIG. 6, each of the bus bars9(9-1to9-9) includes a main body portion20and a tab terminal24. The main body portion20is disposed horizontally along the upper wall2aof the casing2. The tab terminal24stands upward from the main body portion20so that the tab terminal24penetrates each of tab terminal through-apertures12a,13a,14a, and15ain the fuse-containing section12, relay-containing section13, connector-containing section14, and fusible-link-containing section15. Each tab terminal24includes a tuning fork type tab terminal portion24athat penetrates the tab terminal through-aperture12ain the fuse-containing section12and/or the tab terminal through-aperture13ain the relay-containing section13, and a male tab terminal portion24bthat penetrates the tab terminal through-aperture14ain the connector-containing section14and/or the tab terminal through-aperture15ain the fusible-link-containing section15.

A first attaching piece21and a second attaching piece22that have rectangular shapes in cross section are provided on a peripheral edge of the main body portion20so that the pieces21and22are spaced apart from each other and are directed outward. As shown inFIG. 6, the first and second attaching pieces21and22are provided with projecting ends21aand22aby bending the pieces21and22upward to the same directions by a pressing machine (not shown) to form L-shaped configurations. Similarly, the tab terminal24is bent in the same direction as the bent directions of the first and second attaching pieces21and22.

Although the first and second attaching pieces21and22have substantially the same dimensions in width and thickness and the projecting ends21aand22ahave substantially the same dimensions in height in the first embodiment, these dimensions in width, thickness, and height may be different and they may be set to be desired dimensions, if necessary.

Each of the bus bars9-1to9-4,9-6, and9-8is provided on opposite ends in a longitudinal direction of the main body portion20with a tuning fork type tab terminal24aand a male tab terminal24b. The second attaching piece22is provided near the tuning fork type tab terminal24awhile the first attaching piece21is provided near the male tab terminal24b. The bus bar9-6has two first attaching pieces21and one second attaching piece21, because the whole length and area of the bus bar9-6is greater than those of the other bus bars.

The bus bar9-5is provided on opposite ends in a longitudinal direction of the main body portion20with male tab terminals24b-1and24b-2. The male tab terminal24b-1has dimensions in width and projecting height greater than those of the male tab terminal24b-2. The second attaching piece22is provided near the male tab terminal24b-1while the first attaching piece21is provided near the male tab terminal24b-2.

The bus bar9-7is provided on opposite end sides in a widthwise direction of the main body portion20with a plurality of tuning fork type tab terminals24a. The first and second attaching pieces21and22are provided near the tuning fork type tab terminals24a-1and24a-2that are most spaced apart from each other.

The bus bar9-9is provided on opposite ends in a longitudinal direction of the main body portion20with a tuning fork type tab terminal24aand a male tab terminal24b. The bus bar9-9is different from the other bus bars. That is, the first and second attaching pieces21and22are not provided near the tuning fork type tab terminal24aand male tab terminal24b. Only the second attaching piece22is provided substantially on an intermediate position between the tuning fork type tab terminal24aand the male tab terminal24b, because the dimensions in whole length and projecting height of the bus bar9-9are smaller than those of the other bus bars.

As described above, in an exemplary embodiment, a bus bar having relatively great whole length and/or area out of the bus bars9provided with the tab terminals24on the main body portions20is provided on the opposite ends with the first and second attaching pieces21and22that are spaced apart from each other as far as possible. However, it is not always necessary that the bus bar having relatively small whole length and/or area out of the bus bars9must be provided with both of the first and second attaching pieces21and22. Either attaching piece may be provided on the bus bar.

Accordingly, arranging positions, numbers, dimensions, and the like of the attaching pieces can be altered in accordance with the whole lengths and areas, and configurations of these bus bars, and specifications and internal circuit layouts of the electrical junction box.

On the other hand, the upper casing member2is provided in the upper wall2awith receiving apertures that are open in the inner surface of the wall2a. The receiving apertures include rectangular apertures30that receive and fix the projecting ends21aof the first attaching pieces21of the bus bars9and circular apertures31that receive and fix the projecting ends22aof the second attaching pieces22.

As shown inFIG. 7A, each circular aperture31has an inner diameter that contacts with four corners of the projecting end22aof the second attaching piece22so that the circular aperture31can restrain the projecting end22afrom moving laterally or longitudinally.

As shown inFIG. 7B, each rectangular aperture30has substantially the same configuration as that of the first attaching piece21. The rectangular aperture30is provided on a central position of each long side with ribs30athat are projected inward and opposed to each other so that the aperture30can press the outer surface of the first attaching piece21and restrain the first attaching piece21from moving longitudinally.

When the second attaching piece22is inserted into the circular aperture31, an inserting force will be slightly great on account of contacts with the four corners of the projecting ends22a. However, when the tab terminals24are inserted into the tab terminal through-holes12ato15a, it is possible to project the tab terminals24from the holes in a proper posture, thereby enhancing alignment of the tab terminals24. In an exemplary embodiment, the second attaching piece22to be inserted into the circular aperture31is disposed near the tuning fork type tab terminal24a. The tuning fork type tab terminal24aincludes two clamping pieces H that are provided on central parts with slits S. In the case where the tuning fork type tab terminal24ais inserted into the tab terminal through-hole in an improper posture, for example, when a central axis of the slit S is deviated in the fuse-containing section12and/or the relay-containing section13, the two clamping pieces H cannot be widened outward through the slits S upon fitting the electrical components and a stress caused upon fitting the electrical components will be concentrated into only one of the clamping pieces. Consequently, the clamping pieces will be extremely deformed or will be broken in some cases.

When each first attaching piece21is inserted into each rectangular aperture30, it is possible to restrain the piece21from turning in the aperture30, because the piece21and aperture30are formed into the substantially same shape. If a slight clearance is caused between the first attaching piece21and the rectangular aperture30, there is a possibility that the piece21moves slightly a lateral or longitudinal direction. However, it is possible for the ribs30ato restrain the piece21from moving in at least a widthwise direction in the rectangular aperture30.

In an exemplary embodiment, the first attaching piece21to be inserted into the rectangular aperture30is disposed particularly near the male tab terminal24b. The male tab terminal24bis positioned by the first attaching piece21and rectangular aperture30. However, as described above, there will be a possibility that the male tab terminal24bprojects from the tab terminal through-hole14aor15ain the connector-containing section14or the fusible-link-containing section15with the terminal24bbeing shifted in the through-hole14aor15a. Because the electrical components to be connected to the male tab terminals24bare female connectors or the like that contain female terminals (not shown) in cavities, C-shaped surfaces provided on distal ends of the cavities can correct postures of the male tab terminals24b.

When the first attaching pieces21are inserted into and secured to the rectangular apertures30in the upper casing member2and the second attaching pieces22are inserted into and secured to the circular apertures31in the upper casing member2, it is possible to restrain the bus bars9from turning and moving laterally or longitudinally and to precisely position and hold the bus bars9on the inner surface of the upper wall2aof the upper casing member2. Consequently, it is possible to precisely align the tuning fork type terminal24athat is required for serious alignment.

When the electrical components (not shown) such as relays, fuses, connectors are fitted to the tab terminals24provided on the bus bars9, the bus bars will cause a rotary movement, or a lateral or longitudinal movement. In particular, the tuning fork type tab terminal24awill receive a force for outward widening the clamping pieces H through the central slit S upon fitting the electrical components to the terminal24a. There is a possibility that the bus bars9will cause the lateral or longitudinal movement in accordance with the widening direction. Accordingly, the projecting end22aof each second attaching piece22provided near the tuning fork type tab terminal24ais inserted into and secured to the circular aperture31while the projecting end21aof each first attaching piece21provided near the male tab terminal24bis inserted into and secured to the rectangular aperture31. Thus, it is possible to restrain the respective bus bars9from causing the rotary movement, lateral or longitudinal movement that is generated by a stress upon fitting of the electrical components and to surely position and hold the bus bars9in the upper casing member2.

The insulation plates6and8are contained in the interior of the casing including the upper casing member2, on which the bus bars9are fixed, and the lower casing member3. The insulation plate8is interposed between the bus bars9and the upper layer printed board7while the insulation plate6is interposed between the upper printed board7and the lower layer printed board5.

As described above, the upper layer printed board5is interposed between the bus bars9and the insulation plate6. The insulation plate6serves not to hold the bus bars9but to electrically insulate the printed boards5and7.

Thus, because the bus bars contained in the electrical junction box are directly secured to the inner surface of the upper wall of the upper casing member, it is not necessary to caulk the bus bars onto the insulation plate. The prior art electrical junction box has required such caulking work.

Although the bus bars are fixed on the inner surface of the upper wall of the upper casing member in the first embodiment, the bus bars may be secured to an inner surface of a bottom wall of the lower casing member.

FIG. 8shows a second embodiment of the electrical junction box in accordance with the present invention.

The second embodiment includes bus bars40and41as well as the bus bars9secured to the inner surface of the upper casing member in the first embodiment. These bus bars40and41are not caulked onto the insulation plate but secured to the insulation plate.

The bus bars40and41are laminated through an insulation plate42. An upper layer bus bar40is disposed below the insulation plate45that is disposed below the bus bars9secured to the upper casing member2. A lower layer bus bar41is disposed through the insulation plate42below the bus bar40. An insulation plate43is disposed between the bus bar41and the bottom wall3aof the lower casing member3.

The upper layer bus bar40is provided with attaching pieces40aand40bas in the case of the first and second attaching pieces20and21of the bus bars9. The insulation plate45disposed above the bus bar40is provided with a rectangular aperture45aand a circular aperture46aas in the case of the rectangular aperture31and circular aperture32in the inner wall of the upper casing member2. The attaching pieces40aand40bare inserted into and secured to the rectangular aperture45aand circular aperture46ain the insulation plate45, respectively.

Similarly, the attaching pieces41aand41bprovided on the lower layer bus bar41are inserted into and secured to the rectangular aperture42aand circular aperture42bin the insulation plate42in the insulation plate42, respectively.

Thus, three layers comprising the bus bars40,41and9(the bus bars9is secured to the inner surface of the upper casing member2) are not caulked onto the insulation plates but secured to the interior of the casing.

FIG. 9shows a third embodiment of the electrical junction box in accordance with the present invention.

The third embodiment includes three layers comprising bus bars9,40, and41as is in the case with the second embodiment. First and second attaching pieces40aand40bof the upper layer bus bar40penetrate through-holes45hin an insulation plate45and are inserted into and secured to a rectangular aperture30and a circular aperture31in the inner surface of the upper casing member2.

First and second attaching pieces41aand41bof the lower layer bus bar41project toward a bottom wall3aof a lower casing member3, and are inserted into and secured to a rectangular aperture3cand a circular aperture3din an inner surface of the bottom wall3a.

Thus, three layers comprising the bus bars40,41and9(the bus bars9is secured to the inner surface of the upper casing member2) are not caulked onto the insulation plates but secured to the interior of the casing.

The exemplary embodiments are not limited to the above first to third embodiments. The attaching piece of the bus bar having a rectangular shape in cross section may be inserted into and secured to either a circular aperture or a rectangular aperture in the casing.