Electrical connection box

Abstract: In an electrical connection box (K1) including an internal circuit in which a plurality of pressing contact terminals (5, 6) are brought into pressing contact with a wire (W1) and input-output terminal portions (5a, 6a) of the pressing contact terminals (5, 6) are connected to external circuits, respectively; wherein the wire (W1) includes an electrically operative portion (a) between one (5) of the pressing contact terminals (5, 6) connected to an external electrical heating element such as a relay, a fuse (7) or the like and another one (6) of the pressing contact terminals (5, 6); the improvement comprising: the electrically operative portion (a) being shifted from a course (X) connecting the one (5) of the pressing contact terminals (5, 6) and the another one (6) of the pressing contact terminals (5, 6) at a minimum distance to a region (Y) having low wiring density so as to be lengthened in a wiring path of the wire (W1).

Description: BACKGROUND OF THE INVENTION The present invention generally relates to electrical connection boxes in which an internal circuit is constituted by a wire and pressing contact terminals brought into pressing contact with the wire and more particularly, to an electrical connection box in which heat dissipation of a wire connected to external electrical heating elements such as a relay and a fuse is facilitated such that quantity of electric current flowing through the wire is increased. Conventionally, in order to easily cope with changes of design of an internal circuit of an electrical connection box in which electric circuits including a number of fuses, relays, etc. are arranged in a concentrated manner such that branch connection of wiring harnesses is performed reasonably, such an arrangement has been provided in which a wire is laid in the electrical connection box and is connected to external input-output terminals by pressing contact terminals in place of bus bars formed by blanking electrically conductive plates. An example of a known connection box is disclosed in EP-A-0 044 636. In another known electrical connection box shown in Fig. 1, a wire W is laid on an insulating plate 3 disposed in a casing of the electrical connection box, which is constituted by an upper casing 1 and a lower casing 2 and pressing contact terminals 5 and 6 are brought into pressing contact with the wire W. A tab 5a of the pressing contact terminal 5, which acts as an input-output terminal portion, is projected out of a terminal hole formed on a bottom wall of a fuse receiver 1a protruding from an upper face of the upper casing 1 and is connected, as shown in Fig. 2, to a terminal 8 of a fuse 7, which is fitted into a bore of the fuse receiver la. In addition to the fuse receiver la, a relay receiver and a connector receiver are provided on the upper face of the upper casing 1 and tabs 6a of tabs 6 brought into pressing contact with the wire W are projected into the relay receiver and the connector receiver so as to be connected to relays and contact bonding terminals connected to electric devices. In case components connected to the wire W of the internal circuit through the pressing contact terminals are electrical heating elements such as the fuse 7 and the relay as described above, heat is transferred to the tabs 5a and 6a of the pressing contact terminals 5 and 6, which are brought into contact with the terminal 8, etc. and is further transferred from the pressing contact terminals 5 and 6 to the wire W, so that the wire W undergoes thermal influence. Usually, an electrically operative portion a of the wire W, which is interposed between the pressing contact terminals 5 and 6 at input and output sides, respectively, is set to a shortest distance, while an electrically inoperative portion b of the wire W other than the electrically operative portion a is cut off in the vicinity of spots of connection between the wire W and the pressing contact terminals 5 and 6 such that the wire W is shortened. If the wire W is shortened as described above, heat dissipation from the wire W is small, so that temperature of the electrically operative portion a rises readily and thus, quantity of electric current capable of flowing through the wire W is lessened. As a result, such a problem arises that circuit configuration becomes complicated due to, for example, the need for division of the internal circuit. Furthermore, if the wire W is heated by the electrical heating elements connected to the wire W, such an inconvenience is incurred that temperature of whole interior of the electrical connection box also rises. Meanwhile, in case an internal circuit of an electrical connection box is constituted by conventional bus bars, heat dissipation is performed by the bus bars each having a large area. However, in case the internal circuit of the electrical connection box is constituted by a wire and pressing contact terminals, heat dissipation area of a known pressing contact terminal T is small as shown in Fig. 3. Therefore, if heat is produced by contact resistance at a pressing contact portion of the known pressing contact terminal T, which is brought into pressing contact with the wire W, heat is accumulated in the known pressing contact terminal T so as to set the known pressing contact terminal T to high-temperature state. As a result, such a drawback may be encountered that since creep is produced at a blade B disposed at an inner periphery of a slot portion S of the known pressing contact terminal T, performance of the known pressing contact terminal T is apt to deteriorate. Furthermore, in the case of a wire used for a large-current circuit such as a power circuit connected to fuses or relays and a through-circuit, heat produced by the fuses or relays is transferred to the wire and thus, temperature of the wire readily rises undesirably. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide, with a view to eliminating the above mentioned drawbacks of conventional electrical connection boxes, an electrical connection box in which by facilitating heat dissipation of a wire connected, via pressing contact terminals, to external electrical heating elements such as a relay and a fuse, not only a large quantity of electric current can flow through the wire but rise of temperature of interior of the electrical connection box is restrained. This object is achieved with the features indicated in claim 1. EP-A-0 703 117, which forms prior art pursuant to Article 54 (3) EPC, discloses an electrical connection box including an internal circuit in which a plurality of pressing contact terminals are brought into pressing contact with a wire and input-output terminal portions of the pressing contact terminals are connected to external circuits, respectively; wherein the wire includes an electrically operative portion between a first one of the pressing contact terminals, connected to an external electrical heating element such as a relay, a fuse or the like, and another one of the pressing contact terminals, and an electrically inoperative portion serving as a heat dissipation section; and wherein the first pressing contact terminal has a plurality of pressing contact portions, one of the pressing contact portions is connected to the electrically operative portion through pressing contact, while another one of the pressing contact portions is connected to an electrically inoperative portion through pressing contact. The electrical connection box according to the invention has the further feature that the electrically inoperative portion forms a loop at the first pressing contact terminal. BRIEF DESCRIPTION OF THE DRAWINGS These objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: Fig. 1 is a fragmentary sectional view of a prior art electrical connection box (already referred to) ; Fig. 2 is a perspective view showing connection between a pressing contact terminal and a fuse in the prior art electrical connection box of Fig. 1 (already referred to) ; Fig. 3 is a perspective view of a prior art pressing contact terminal (already referred to) ; Fig. 4 is a schematic view showing whole configuration of an internal circuit of electrical connection boxes according to first to fourth embodiments of the present invention; Fig. 5 is a perspective view showing connection between a pressing contact terminal and a fuse in the electrical connection box according to the present invention ; DETAILED DESCRIPTION OF THE INVENTION Fig. 4 shows an internal circuit of an electrical connection box K3 according to the present invention. In the electrical connection box K3 shown in Figs. 5, a wire is laid in the same manner as prior art of Fig. 1. Therefore, laying of the wire in the electrical connection box is described with reference to Fig. 1, hereinafter. Pressing contact terminals 5 and 6 are connected, through pressing contact, to a wire W laid preliminarily on an insulating plate 3 so as to form the internal circuit. Then, the insulating plate 3 preliminarily assembled with the wire W and the pressing contact terminals 5 and 6 is accommodated in an upper casing 1 and a lower casing 2 such that the electrical connection box K3 is assembled. At this time, tabs 5a and 6a of the pressing contact terminals 5 and 6, which act as input-output terminal portions of the pressing contact terminals 5 and 6, respectively, are projected into a relay receiver la, a fuse receiver and a connector receiver which protrude from an upper face of the upper casing 1 so as to be connected not only to external electrical heating elements such as a relay and a fuse but to a connector fitted into the connector receiver and leading to a load circuit. As shown in Figs. 1, 2 and 5, the tab 6a of the pressing contact terminal 6, which acts as the input-output terminal portion of the pressing contact terminal 6, is formed into a flat platelike shape and is inserted into a terminal receiving slit of a connector so as to be connected to a contact bonding terminal contact bonded to a distal end of a wire. Thus, the pressing contact terminal 6 mainly functions as a pressing contact terminal at an output side. On the other hand, the tab 5a of the pressing contact terminal 5 is folded down into a U-shaped form and a terminal receiving groove 5c extends from an upper end of the tab 5a downwardly and a terminal 8 of a fuse 7 or a terminal of a relay (not shown) is inserted into the terminal receiving groove 5c so as to be connected to the pressing contact terminal. Hence, the pressing contact terminal 5 mainly functions as a pressing contact terminal at an input side. In the electrical connection box K3 in which the internal circuit is constituted by the wire W and the pressing contact terminals 5 and 6 brought into pressing contact with the wire W as described above, heat dissipation of wires W1 to W5 each of which is connected to the fuse 7 through the pressing contact terminal 5 at the input side and the connector of the load circuit via the pressing contact terminal 6 at the output side as shown in Fig. 4 is facilitated. In the wire W4 of the electrical connection box K3 shown in Fig. 5, a pressing contact terminal 5' which is connected to the terminal 8 of the fuse 7 has two pressing contact portions, i.e., first and second pressing contact portions 5b' and 5d'. One of the first and second pressing contact portion 5b' and 5d' is brought into pressing contact with an electrically operative portion a, while the other of the first and second pressing contact portion 5b' and 5d' is brought into pressing contact with an electrically inoperative portion b. Namely, the first pressing contact portion 5b' extends continuously from a lower portion of a tab 5a' of the pressing contact terminal 5' and the second pressing contact portion 5d' is bent orthogonally from the first pressing contact portion 5b'. Slots 5e' and 5f' are, respectively, formed at the first and second pressing contact portions 5b' and 5d' and a pressing contact blade is, in turn, formed at a periphery edge of each of the slots 5e' and 5f'. After the electrically operative portion a of the wire W4 has been connected to the second pressing contact portion 5d' through pressing contact, the electrically inoperative portion b is extended from the electrically operative portion a. As shown in Fig. 5, the electrically inoperative portion b is curved arcuately and a distal end of the electrically inoperative portion b is brought into pressing contact with the first pressing contact portion 5b'. By providing the electrically inoperative portion b extending over a long distance, heat dissipation can be facilitated from this long electrically inoperative portion b. In addition, since heat from the terminal 8 of the fuse 7 is transferred to both the electrically operative portion a and the electrically inoperative portion b, quantity of heat transferred from the fuse 7 to the electrically operative portion a can be reduced accordingly. By this double heat dissipation effect, thermal influence exerted upon the electrically operative portion a can lessened. Furthermore, since the electrically operative portion b can be laid orthogonally to the second pressing contact portion 5d' for the electrically operative portion a, the electrically operative portion b can be provided without interfering with the electrically operative portion a.

Claims: Electrical connection box (K3) including an internal circuit in which a plurality of pressing contact terminals (5', 6) are brought into pressing contact with a wire (W4) and input-output terminal portions (5a', 6a) of the pressing contact terminals (5', 6) are connected to external circuits, respectively; wherein the wire (W4) includes an electrically operative portion (a) between a first one (5') of the pressing contact terminals, connected to an external electrical heating element such as a relay, a fuse (7) or the like, and another one (6) of the pressing contact terminals, and an electrically inoperative portion (b) extended from the electrically operative portion (a) and serving as a heat dissipation section; and wherein the first pressing contact terminal (5') has a plurality of pressing contact portions (5b', 5d'), one (5d') of the pressing contact portions is connected to the electrically operative portion (a) through pressing contact, while another one (5b') of the pressing contact portions is connected to said electrically inoperative portion (b) through pressing contact, so that the electrically inoperative portion (b) forms a loop at the first pressing contact terminal (5'). Electrical connection box (K3) as claimed in claim 1, wherein the first pressing contact terminal (5') includes a tab (5a') connected to the external electrical heating element and first and second pressing contact portions (5d', 5b') extending downwardly from the tab (5a') and intersecting with each other orthogonally; the first and second pressing contact portions (5d', 5b') having first and second slots (5f, 5e'), respectively such that first and second blades provided on peripheries of the first and second slots (5f, 5e') are connected to the conductors of the electrically operative portion (a) and the electrically inoperative portion (b), respectively.

Inventors: INOUE NORI, KOBAYASHI MAKOTO, OKA YOSHITO, ONIZUKA TAKAHIRO, SAKA YUUJI, INOUE, NORI, KOBAYASHI, MAKOTO, OKA, YOSHITO, ONIZUKA, TAKAHIRO, SAKA, YUUJI, Inoue, Nori, c/o Sumitomo Wiring Systems, Ltd, Kobayashi, Makoto, Sumitomo Wiring Systems, Ltd., Oka, Yoshito, c/o Sumitomo Wiring Sys, Ltd., Onizuka, Takahiro, c/o Sumitomo Wiring Sys, Ltd, Saka, Yuuji, c/o Sumitomo Wiring Systems, LTD
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1995
Main classification: H01R9
IPC codes: H01R4, H01H1, H01H85, H01R9