GB2369076A

GB2369076A - Electric wire cutting structure

Info

Publication number: GB2369076A
Application number: GB0126545A
Authority: GB
Inventors: Takayoshi Minoura
Original assignee: Yazaki Corp
Current assignee: Yazaki Corp
Priority date: 2000-11-06
Filing date: 2001-11-05
Publication date: 2002-05-22
Anticipated expiration: 2021-11-05
Also published as: GB0126545D0; DE10154372A1; JP3901446B2; GB2369076B; DE10154372B4; JP2002142329A

Abstract

An electric wire cutting structure for a junction box 20 includes a wiring sheet having a hole and an electric wire 26 bridged across the hole, the hole having a first opening 11a, a second opening 11b that is greater than the first opening, and a frame 13 defining the first and second openings. The structure also includes a die supporting the electric wire bridged across the hole, a punch 30 driven into the first opening to cut off the electric wire, and a stripper 31 inserted in the second opening, for regulating the motion of the punch. The size of the stripper is greater than the first opening and smaller than the second opening.

Description

ELECTRIC WIRE CUTTING STRUCTURE FOR JUNCTION BOX,

METHOD FOR CUTTING ELECTRIC WIRE, WIRING SHEET FABRICATED BY

THIS METHOD, AND JUNCTION BOX USING THE WIRING SHEET

5 BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a structure and a method for cutting electric wires arranged on a wired sheet accommodated in an electric junction box.

10 2. Description of the Related Art

a junction box or a junction block, many winding wires are arranged on a plastic sheet in order to electrically connect busbar circuits located on the opposite side of the plastic sheet. Since it is inefficient and troublesome to put wires one by one on the plastic sheet, continuous wiring with a single stroke is proposed. The continuous 16 electric wire drawn on the plastic sheet with a single stroke is then cut off at predetermined positions and divided into multiple sections.

FIG. 1 illustrates how the continuous wire is cut off with a conventional technique. As illustrated in FIG 1A, a cutting hole 102, which has an opening 102a and a frame 102b, is formed in advance at a predetermined position in the plastic sheet (or 20 wiring sheet) 101. The electric wire 103 is bridged across the hole 102 on top of the frame 102b.

The wiring sheet 101 is then placed on the dice 104 so that the wire 103 faces downward and is supported by the top face of the dice 104, as illustrated in FIG. 1B.

Then, the punch 104a is driven into the hole 102, and the wire 103 is cut by the edge of 25 the punch 104a. In order to prevent the wire 103 from shifting or moving during the punching operation, a stripper 104b is fit into the opening 102a to hold down the electric wire 103 against the dice 104. The stripper 104b receives the punch 104a, and

the punch 104a moves inside the stripper 104b. After the wire 103 is cut, the dice 104, the punch 104a, and the stripper 104b are removed.

FIG. 2 illustrates the electric wire 103 that has been cut by the punch 104a. As illustrated in FIG 2A, the electric wire 103 has a separation gap across the hole 102, 5 which corresponds to the width W1 of the punch 104a (FIG 1B).

With the conventional technique shown in FIG 1, the stripper 104b is completely fit into the hole 102 so that the bottom face of the stripper 104b holds down the electric wire 103 directly against the dice 104. To this end, the width W2 of the cutting hole 102 (FIG. 1B) has to be set large enough to receive the stripper 104b. Since the width W3 of 10 the stripper 104b is greater than the width W1 of the punch 104a, the size of the opening 102a of the cutting hole becomes inevitably large.

As illustrated in FIG 2B, the cut end 103a of the electric wire 103 projects over the opening 102a of the cutting hole 102 by a length X1. Length X1 is the summation of the thickness "a" of the stripper 104b and the space "b" between the outer face of the 15 stripper 4b and inner face of the hole 102 (X1 = a + b). This means that the projection amount of the cut end 103a is relatively large.

If a force happens to be applied to the cut end 103b during the assembling of the junction block, the cut end 103a may dip into the opening 102a and the tip of the cut end 103 may come closer to or directly touch a bus bar 5 located on the opposite side of 20 the wiring sheet 101, as illustrated in FIG. 2C, causing undesirable short-circuit.

SUMMARY OF THE INVENTION

The present invention was conceived to overcome the above-mentioned problem 25 in the prior technique, and to provide an improved structure and method for cutting a continuous electric wire arranged on a wiring sheet, which can keep the cut-end of the wire away from the bus bar circuits in a junction box.

In one aspect of the invention, an electric wire cutting structure for a junction box includes a wiring sheet having a hole and an electric wire bridged across the hole, the hole having a first opening, a second opening that is greater in size than the first opening, and a frame defining the first and second openings. The structure also includes 5 a dice supporting the electric wire bridged across the hole, a punch driven into the first opening to cut off the electric wire, and a stripper inserted in the second opening for regulating the motion of the punch. The size of the stripper is greater than the first opening and smaller than the second opening.

The frame has a first wall that defines the first opening and receives the electric 10 wire, and a second wall that defines the second opening. The first wall of the frame holds down the electric wire against the dice when the punch is driven into the first opening. In another aspect of the invention, a wiring sheet used in a junction box is provided. The wiring sheet is made of, for example, a plastic sheet, and has a hole at a 15 predetermined position, and an elastic wire arranged on the sheet. The hole has a first opening, a second opening that is larger than the first opening, and a frame defining the first and second openings. The electric wire is separated by a gap Predetermined distance at the hole.

In still another aspect of the invention, a junction box is provided. The junction 20 box includes a main cover, a circuit board covered with the main cover and having a circuit on a first face, a wiring sheet attached to a second face of the circuit board for electrically connecting the circuit, and a base (or an under cover) for supporting the wiring sheet and the circuit board. The wiring sheet has an electric wire arranged thereon and a hole with a first opening and a second opening that is larger than the first 25 opening. The electric wire is separated at a predetermined gap at the hole.

In yet another aspect of the invention, a method for cutting an electric wire for junction box is provided. In this method, a wiring sheet having a hole and an electric

wire bridged across the hole is prepared. The hole has a first opening, a second opening that is greater than the first opening, and a frame with a first wall that defines the first opening and receives the electric wire. The wiring sheet is placed on a dice so that the first wall of the frame holds down the electric wire against the dice. A stripper having a 5 hollow is inserted into the second opening. The stripper has a size greater than the first opening and smaller than the second opening. A punch is inserted in the hollow of the stripper, and is driven into the first opening to cut the electric wire bridged across the hole. BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages will be apparent from the following detailed description of the invention in conjunction with the attached drawings, in which:

FIG 1A illustrates a conventional wiring sheet, and FIG 1B illustrates in a cross-sectional view how the electric wire is cut using the conventional technique; 15 FIG. 2 illustrates the electric wire that has been cut out on the wiring sheet with the conventional technique; FIG 3 is a cross-sectional view of the electric wire cutting structure according to an embodiment of the invention; FIG 4 is a plane view of the major part of the electric wire cutting structure; 20 FIG. 5 is a cross- sectional view of the electric wire placed on the wiring sheet in a junction box; FIG 6 is an exploded perspective view an electric junction box, to which the present invention is applied; and FIG 7 is a bottom view of a wiring sheet, to which the present invention is 25 applied.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in detail with reference to the attached drawings. FIG 3 illustrates an electric wire cutting structure 10 according to an embodiment 5 of the invention. The electric wire cutting structure 10 includes a wiring sheet 22, a dice 32, a punch 30, and a stripper 31. The wiring sheet 22 has a hole 11 and an electric wire 26 arranged on one surface 22b of the sheet 22. The hole 11 has a first opening 11a, a second opening 11b that is greater than the first opening 11a, and a frame 13 that defines the first and second openings 11a and 11b. To be more precise, the frame 13 has 10a first wall 13a that defines the first opening 11a, and a second wall (side wall) 13b that defines the second opening 11b. The frame has a height "h" from the surface 22b of the wiring sheet 22, and has a stepped opening consisting of the first opening 11a and the second opening 11b that communicates with the first opening 11a and is larger than the first opening 11a.

15The stripper 31 is larger than the first opening 11a and smaller than the second opening 11b, and therefore, it is received in the second opening 11b. The punch 30 is, for example, cylindrical, and has a diameter that is almost the same as or a slightly smaller than the width of the first opening 11a, so that it can move through the first opening 11a. The punch 30 may be square, and in such a case, the punch is almost the 20 same size or Tightly smaller than the size of the first opening. The dice supports the electric wire 26 bridged across the hole 11.

In the cutting operation, the wiring sheet 22 is placed on the dice 32 so that the electric wire 26 faces down. In this state, the first wall 13a of the frame 13 holds down the electric wire 26 against the dice 32. Then, the stripper 31, which has a hollow (not 25 shown) for receiving the punch 30, is inserted into the second opening 11b. Since the size of the stripper 31 is greater than that of the first opening 11a, as indicated by the symbol "W" in FIG. 3, the bottom of the stripper 31 abuts against the first wall 13a

inside the hole 11. Accordingly, the stripper 31 also holds down the electric wire 26 against the dice 32 via the frame 13 of the hole 11.

The punch 30 is driven into the first opening 11a, as indicated by the arrow in FIG 3, and the electric wire 26 is cut off by the cutting edge 30a of the punch 30. Preferably.

5 the horizontal cross-sectional area of the punch 30 is almost the same as or slightly smaller than the first opening 11a. In the example shown in FIG 3, there is a small space b between the punch 30 and the first opening 11a.

During the cutting operation, the stripper 31 regulates the motion of the punch 30, while securely holding the electric wire 26 between the frame 13 and the dice 32. In the 10 embodiment, the weight of the stripper 31 is added to the frame 13 of the hole 11, and the electric wire 26 is cut in a reliable manner.

When the electric wire 26 is cut, the punch 30, the stripper 31, and the dice 32 are removed. Before the cutting, the electric wire 26 is bridged across the hole 11, with part of 15 the wire 26 contacting with the first wall 13a of the frame 13. Once the punch 30 punches through the electric wire 26, the electric wire 26 has a separation gap W1, which corresponds to the width W1 of the punch 30.

FIG 4 is a plane view of the wiring sheet 22, in which the electric wire 26 has been cut via the hole 11. The wiring sheet 22 has a hole 11 and an electric wire 26 20 arranged on the wiring sheet 22 and separated at a predetermined gap W1 at the opening A. The hole 11 has a first opening 11a, a second opening 11b (FIG. 3) that is larger than the first opening, and a frame 13 defining the first and second openings 11a and 11b.

By using the punch 30 whose diameter is almost the same as or a slightly smaller than the width of the first opening 11a, while holding the electric wire 26 by the stripper 25 31 in the second opening 11b, the cut end 26a of the electric wire 26 substantially aligns with the edge 13c of the frame 13. Alternatively, the cut end 26a projects by length X2 from the edge 13c of the frame 13, which corresponds to the space b shown in FIG 3.

The projection length X2 is independent of the thickness of the stripper 31, unlike the conventional technique, because the stripper 31 is received in the second opening 11b. The projection length X2 is defined only by the space "b" between the first opening 11a and the outer face of the punch 30. The size of the punch 30 can be 5 made as close to the size of the first opening 11a as possible as long as the motion of the punch 30 is assured. Consequently, the amount of projection of the electric wire 26 from the frame 13 into the aperture A is greatly reduced, as compared with the conventional technique. In this example, the hole 11 is made square, with the first and second openings JO 11a, 11b and the frame 13 also being square. However, hole 11 may be of any shape, such as a rectangle or a round. In such cases, the stripper 31 and the punch 30 may have the similar shapes to the hole 11, or alternatively, the punch 30 may have any shape. as long as its diameter or the width is almost the same as or a slightly smaller than the diameter or the width of the first opening.

16 FIG 5 illustrates the wiring sheet 22 assembled with the circuit board 21 having circuit element (such as a bus bar) 21a on it. The wiring sheet 22 is attached to the circuit board 21 so that the other surface 22a faces the circuit 21a. Since the amount of projection X2 of the cut end 26a of the electric wire 26 is very small, the distance L from the circuit element (or the bus bar) 21a to the cut end 26a of the wire 26 is 20 sufficiently greater than the projection X2. With this structure, even if a large force is applied to the electric wire 26 during the assembling of a junction box, the cut end 26a is prevented from coming close to the bus bar 21a. Accordingly, undesirable short circuit can be efficiently prevented.

FIG 6 is an exploded perspective view of a junction box (or a junction block! 20, 25 and FIG 7 illustrates the wiring sheet 22 used in the junction box 20 shown in FIG 6.

The junction box 20 includes a main cover 23, a circuit board 21covered by the main cover 23, a wiring sheet 22 on which an electric wire 27 is arranged, and a base (or a

under cover) 24 for supporting the wiring sheet 22 and the circuit board 21. The circuit board 21 has a top face on which a circuit element (such as a bus bar) 21a is mounted, and a rear face. The wiring sheet 22 is attached to the rear face of the circuit board 21 so that the electric wire 27 is located opposite to the circuit element 21a.

5 The wiring sheet 22 has a hole 11, and the electric wire 26 is separated by a predetermined gap at the hole 11, as illustrated in FIG 7. As has been described, the hole 11 has a first opening 11a and a second opening 11b that is larger than the first opening, and a frame 13 defining the first and second openings 11a and 11b.

The under cover 24 has locks 24b formed on the side face 24a. The main cover 23 10 has pieces (not shown) inside the sidewall 23a, which receives the locks 24b when the main cover 23 is placed on the under cover 24.

The main cover 23 has connectors, such as fuse cavities 23b for receiving fuses 25 or relay cavities 23c on its top face. The wiring sheet 22 is attached to the rear face of the circuit board 21 via an insulator 21b so that the electric wire 26 is positioned 15 opposite to the bus bar 21a. The assembly of the circuit board 21 and the wiring sheet 22 shown in FIG 5 is an upside-down picture of FIG 6 for purposes of explanation.

The wiring sheet 22 illustrated in FIG 7 has holes 11 that are formed in advance at predetermined positions. An electric wire 27 is then drawn with a single stroke so as to be bridged over the hole 11. Then, the electric wire 27 is cut at the hole 11, as 20 illustrated above with reference to FIG 3. Accordingly, the junction box 20 accommodates the wiring sheet 20, in which the electric wire 27 is divided into multiple sections, each section containing many electric wires 26.

As has been described above, the electric wire cutting structure allows the electric wire arranged on the wiring sheet to be cut in a precise and reliable manner because 25 both the frame and the stripper securely hold down the electric Dire against the dice.

In addition, the stepped opening of the hole, which consists of a first opening and a second opening that is larger than the first opening, allows the electric wire to be cut

with little projection into the hole.

Since the projection of the electric wire into the hole is very small, the distance from the bus bar formed on the circuit board to the end of the electric wire is much greater than the projection. This arrangement can efficiently prevent short circuit of the 5 junction box.

Although the invention has been described based on the preferred embodiment, the invention is not limited to this example and many changes and substitutions are possible without departing from the scope of the invention.

In the present specification "comprises" means "includes or consists of"

10 and "comprising" means "including or consisting of".

The features disclosed in the foregoing description, or the following

claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

WHAT IS CLAIMED IS:

1. An electric wire cutting structure for a junction box comprising: a wiring sheet having a hole and an electric wire bridged across the hole, the 6 hole having a first opening, a second opening that is greater than the first opening, and a frame defining the first and second openings; a dice supporting the electric wire bridged across the hole; a punch driven into the first opening to cut the electric wire; and a stripper inserted in the second opening and for regulating the motion of the 10 punch, the size of the stripper being greater than the first opening and smaller than the second opening.

2. The electric wire cutting structure of claim 1, wherein the frame has a first wall that defines the first opening and receives the electric wire, and a second wall that defines 15 the second opening.

3. The electric wire cutting structure of claim 2, wherein the first wall of the frame holds down the electric wire against the dice when the punch is driven into the first opening. 4. The electric wire cutting structure of claim 1, wherein the size of the punch is almost the same as or a slightly smaller than the first opening.

5. A wiring sheet used in a junction box comprising: 25 a hole having a first opening, a second opening that is larger than the first opening, and a frame defining the first and second openings; and an electric wire arranged on the wiring sheet and separated by a gap of a

predetermined distance at the hole.

6. The wiring sheet of claim 5, wherein the separation gap of the electric wire is almost the same as or slightly smaller than a width of the first opening.

7. The wiring sheet of claim S. wherein the frame has a first wall defining the first opening, and the electric wire has an end positioned on the first wall of the frame with little projection into the first opening.

10 8. Ajunction box comprising: a main cover; a circuit board covered with the main cover, the circuit board having a first face on which circuits are formed and a second face opposite to the first face; a wiring sheet attached to the second face of the circuit board for electrically 15 connecting the circuits, the wiring sheet having an electric wire arranged thereon and a hole formed in the sheet, the hole having a first opening and a second opening that is larger than the first opening, the electric wire being separated at a predetermined gap at the hole; and a base for supporting the wiring sheet and the circuit board.

9. The junction box of claim 8, wherein the electric wire has a slight projection into the first opening, and a distance between the first opening and the circuit board is substantially greater than the projection.

25 10. The junction box of claim 8, wherein the gap is almost the same as or a slightly smaller than the width of the first opening.

11. The junction box of claim 8, wherein the wiring sheet and a hole are made of an insulator.

12. A method for cutting an electric wire for junction box, comprising the steps of: preparing a wiring sheet that has a hole and an electric wire bridged across the hole, the hole having a first opening, a second opening that is greater in size than the first opening, and a frame, the frame having a first wall that defines the first opening and receives the electric wire; placing the wiring sheet on a dice so that the electric wire is held down by the first wall of the frame against the dice; inserting a stripper into the second opening, the stripper having a size greater than the first opening and smaller than the second opening; and driving a punch into the first opening to cut the electric wire bridged across the hole.

13. A wiring sheet having two major surfaces and an aperture formed therethrough, the aperture having a lip overhanging at least opposed sides of the aperture, the lip providing a support surface for a wire to be located thereon.

14. A wiring sheet according to Claim 13, wherein the lip is supported on a

projection. 15. A structure for cutting an electric wire, the structure comprising: a wiring sheet according to Claim 13 or 14; a die for supporting a wire against the lip of the wiring sheet; and a punch for passing through the aperture and cutting the wire.

16. A structure according to Claim 15, further comprising a brace for pressing against the lip.

17. A structure according to Claim 16, wherein the brace has a hole therethrough, the punch being arranged to pass through the hole prior to passing through the aperture.

18. A structure according to anyone of Claims 15 to 17, wherein the die comprises a pit, the punch being arranged to be received in the pit after passing through the aperture.

19. A circuit board having a first face on which electric circuits are formed, a wiring sheet according to Claim 13 or 14 being attached to a second face of the circuit board for electrically connecting at least some of the circuits to each other. 20. A junction box comprising a circuit board according to Claim 19.

21. A junction box according to Claim 20, further comprising a cover for covering the circuit board and a base for supporting the circuit board.

22. A method of cutting a wire, the method comprising steps of: providing a wiring sheet having two main surfaces and an aperture formed therethrough, the aperture having a lip overhanging at least at both sides of the aperture, the lip providing a support surface for a wire to be located thereon; supporting a wire against the lip, providing a punch; and

passing the punch through the aperture, thereby cutting the wire.

23. A method according to Claim 22, further comprising the steps of: providing a brace; and pressing the brace against the lip.

24. A method according to Claim 23, further comprising the steps of: forming a hole through the brace, and passing the punch through the hole prior to passing the punch through the aperture.

25. A method according to anyone of Claims 22 to 24, further comprising the step of providing a die, wherein the step of supporting a wire against the lip comprises supporting the wire against the lip with the die.

26. A method according to Claim 25, further comprising the steps of: forming a pit in the die, and receiving the punch in the pit after the passing the punch through the aperture. 27. A structure substantially as hereinbefore described, with reference to Figures 3 to 7 of the accompanying drawings.

28. A method substantially as hereinbefore described, with reference to Figures 3 to 7 of the accompanying drawings.

29. Any novel feature or combination of features disclosed herein.