DESCRIPTION

PRESS-CLAMPING TERMINAL FOR CONNECTING TO WIRE

Technical Field

The present invention relates to a connecting structure of a press-clamping terminal to a wire, the press-clamping terminal being open-barrel type and having a U-shaped shield crimping portion.

Background Art

Copper wires are generally used in a wire harness installed in a vehicle such as an automobile. For connecting such wire harnesses to each other or for connecting such a wire harness to on-board equipments, terminals are fixedly secured to the copper wires, and this kind of the terminal is fixedly secured to the copper wire usually by press-clamping.

Each of the terminal for being press-clamped to the copper wire typically includes a bottom plate portion for placing a conductor portion of the copper wire (which is composed of a plurality of copper strands twisted together) thereon, and a pair of crimped pieces extending from the bottom plate portion so as to hold the conductor portion placed on the bottom plate portion therebetween. When the pair of the crimped pieces are crimped inside, the conductor portion is embraced between the crimped pieces and the bottom plate portion. Thus, the terminal is press-clamped to the conductor portion of the copper wire.

FIG. 7 is a drawing for describing a general open-barrel typed press-clamping terminal and a press-clamping method thereof. FIG. 8 is a

cross-sectional view for showing a portion in which the press-clamping terminal is press-clamped to a wire. In the figures, a press-clamping terminal 301 , a wire W, and a lower mold 331 and an upper mold 332 of a press-clamping jig are provided. As shown in FIG. 7, a press-clamping terminal 301 includes an electric connecting portion 302 which contacts and is electrically connected to a mating terminal at a front side in a longitudinal direction of the press-clamping terminal 301 and a wire fixing portion 303 which fixes an end of a shielded wire W at a rear side. Hereinafter, the longitudinal direction is referred to "back and forth direction," and a direction perpendicular to the longitudinal direction is referred to "horizontal direction." The wire fixing portion 303 includes a conductor press-clamping portion 304 which is arranged at a front side and crimped with respect to an exposed conductor Wa' of the shielded wire W, and a shield crimping portion 305 which is arranged at a rear side and crimped with respect to an insulated shield Wb ¹ of the shielded wire W. The electric connecting portion 302, the conductor press-clamping portion 304 and the shield crimping portion 305 share a common bottom plate 311.

The conductor press-clamping portion 304 corresponds to a U-shaped portion on cross-section, which is up-formed by upwardly extending a pair of conductor crimped pieces 314 from opposite ends in the horizontal direction of the bottom plate 311 continued from the electric connecting portion 302. A plurality of serrations (shallow grooves which are line-struck by pressing) 313 extending along the horizontal direction are provided in an inner face of the conductor press-clamping portion 304. The shield crimping portion 305 corresponds to a U-shaped portion on cross-section, which is up-formed by

upwardly extending a pair of shield crimped pieces 315 from opposite ends in the horizontal direction of the bottom plate 311. The shield crimping portion 305 and the conductor press-clamping portion 304 are arranged away from each other at an appropriate interval in the back and forth direction. Each joint side plate 312 is provided between the conductor press-clamping portion 304 and the electric connecting portion 302 so as to upwardly extend from opposite sides of the bottom plate 311 and a rear end of the joint side plates 312 is continued to a front end of the conductor crimped piece 314. The joint side plate 312 makes a portion between the conductor press-clamping portion 304 and the electric connecting portion 302 being a U-shape on cross-section to enhance the bending rigidity.

In order to press-clamp the conductor press-clamping portion 304 of the press-clamping terminal 301 onto the exposed conductor Wa' at a front end of the wire W, the press-clamping portion 301 is placed on a placing surface 331a of the lower mold 331 , and the exposed conductor Wa' at the front end of the wire W is inserted between the conductor crimped pieces 314 of the conductor press-clamping portion 304 and is placed on the bottom plate 311. Then, the upper mold 332 is lowered so that the front end side of the conductor crimped piece 314 is gradually bent inside by a guide slope 332a of the upper mold 332. Eventually, the front end side of the conductor crimped piece 314 is curved to be folded back toward the conductor Wa ¹ by a curved surface continued from the guide slope 332a to a central angular portion 332b, and then, as shown in FIG. 8, the front ends are rubbed together and inserted into the conductor Wa', thereby crimping the conductor crimped pieces 314 to embrace the conductor Wa'. The shield crimped portion 305 is crimped to the insulated shield Wb' of the wire W

as well as the above prior to the crimping of the conductor press-clamping portion 304.

In case the conductor press-clamping portion 304 is press-clamped onto the conductor Wa ¹ of the wire W by crimping the conductor crimped pieces 314 in this way, a conductive metal constituting the press-clamping terminal 301 and the conductor Wa ¹ of the wire W are adhered (or, combined in molecular level or atomic level). Thus, the press-clamping terminal and the wire W are electrically and mechanically combined together strongly.

The press-clamping terminal like this are broadly known, for example in JP-A-7-135031.

In recent years, attention has been directed to aluminum wires in view of the shortage of copper resources, a lightweight design of a vehicle and recyclability. However, an oxide film formed on a surface of an aluminum product is thicker than that on a copper product. Thus, a contact resistance between a conductor portion and a terminal tends to become relatively high in use of the aluminum wire.

One known method of reducing this contact resistance is to strongly crimp the crimped piece of the terminal to the conductor portion, thereby increasing the compressibility of the conductor portion. In this method, oxide films formed on the strands of the conductor portion are destroyed, so that the contact resistance between the conductor portion and the terminal is reduced. In the present specification, "the compressibility of the conductor portion" is defined by the ratio of the cross-sectional area of the conductor portion after the press-clamping to the cross-sectional area of the conductor portion before the press-clamping.

However, stress subjected to the conductor portion increases with the increase of the compressibility of the conductor portion. And besides, aluminum is inferior in mechanical strength to copper. Therefore, when an excessive stress is subjected to the conductor portion of the aluminum wire, a press-clamping strength of the terminal becomes greatly lowered. Therefore, there have been proposed various types of press-clamping structure of an aluminum wire and a terminal for reduction in contact resistance between the conductor portion and the terminal and ensuring of a press-clamping strength of the terminal (see, for example, JP-A-2005-174896 and JP-A-2005-50736). A press-clamping structure disclosed in JP-A-2005-174896 defines a compressibility of a conductor portion to achieve a balance between the reduction in contact resistance between the conductor portion and the terminal and ensuring of the press-clamping strength of the terminal, depending on the cross-sectional area of the conductor portion of the aluminum wire. For example, the compressibility of the conductor portion is set to 50-70 % if the cross-sectional area of the conductor portion is less than 1.5 mm ² , while the compressibility of the conductor portion is set to 40-70 % if the cross-sectional area of the conductor portion is equal to or more than 1.5 mm ² . The compressibility of the conductor portion is typically 75-95 % in case of the copper wire.

A press-clamping structure disclosed in JP-A-2005-50736 includes two pairs of crimped pieces (barrels) which is crimped to a conductor portion 202 of an aluminum portion 201 , as shown in FIGs. 4A and 4B. From a press-clamped state, both crimped pieces 203, 204 are crimped to the conductor portion 202 by using a press-clamping jig having a step, so that a crimp height Hb of the

retaining crimped piece 203 provided at a proximal end of the conductor portion 202 is larger than a crimp height Ha of the conducting crimped piece 204 provided at a tip end of the conductor portion 202. According to this configuration, the press-clamping strength is secured since the compressibility of the conductor portion 202 compressed by the retaining crimped portion 203 is at the same level as in press-clamping the terminal to the copper wire, and at the same time the contact residence is reduced since the compressibility of the conductor portion 202 compressed by the conducting crimped portion 204 is relatively higher. In the press-clamping structure disclosed in JP-A-2005-174896, since the compressibility of the conductor portion is generally high as compared with usage of the copper wire, it is inevitable that the press-clamping strength of the terminal is lowered. That is, if the excessive press-clamping is applied (in case, for example, the compressibility of the conductor portion is set to be equal to or lower than 70 %) in order to suppress the electric resistance of the press-clamping portion of the aluminum wire at a level on the copper wire, the conductor portion is compressed to be easily ruptured when receiving tensile loading in axis direction. As a result, there comes a problem that the intensity of the press-clamping portion is lowered. On the contrary, in the press-clamping structure disclosed in

JP-A-2005-50736, the compressibility of the conductor portion 202 can be varied in accordance with the difference between the crimp height Hb corresponding to a portion at which the retaining crimped piece 203 is crimped and the crimp height Ha corresponding to a portion at which the conducting crimped piece 204. The reduction of the press-clamping strength can be evaded since the

compressibility of the conductor portion 202 compressed by the retaining crimped portion 203 is at the same level as in using the copper wire. However, a special press-clamping jig is required to crimp the crimped pieces 203, 204 to the conductor portion 202 so that crimp heights are different from each other. In addition, the cost is high because it is required to control the heights Ha and Hb at two points of the conducting crimped piece 204 and the retaining crimped piece 203. Although the press-clamping strength is secured by setting the compressibility of the conductor portion 202 compressed by the retaining crimped portion 203 lowered at the same level as in press-clamping the terminal to the copper wire, the electric performance (low and stable electric resistance) should be sacrificed as the compressibility is lowered.

Further, if a crimp height CH ¹ of the conductor press-clamping portion

304 is made lowered to achieve a high compressibility simply as shown in FIG. 8, the joint side plate 312 for jointing the electric connecting portion 302 and the conductor press-clamping portion 304 can be rolled together with the inner-bending of the conductor crimped piece 314 as shown in FIGs. 9A, 9B and 10. That is, if the relationship between the crimp height CH ¹ of the conductor press-clamping portion 304 and a back end height B' of the joint side plate 312 is as follows: CH ¹ - B' < 0 then, the joint side plate 312 is involved in the deformation of the conductor press-clamping portion 304 as shown in FIG. 10. So, since a spring-back force F ¹ of the joint side plate 312 is applied as an expanding force to the conductor crimped piece, a crimping force applied to the conductor Wa' of the wire W by the conductor crimped piece 314 is decreased to lower not only

the mechanical strength, but also the electric connecting performance. FIG. 9A is an outlined side view for showing a press-clamping structure of a known press-clamping terminal, and FIG. 9B is an enlarged view of IXb portion in FIG. 9A. FlG. 10 is a partial plan view for explaining a problem in the known art.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object of the invention is, in case of applying to an aluminum wire for example, to provide a connecting structure of a press-clamping terminal to a shielded wire for achieving a balance between the mechanical connecting structure (high tensile strength) and the electrical connecting structure (low electric resistance) while decreasing the damage to the aluminum wire.

Further, another object of the invention is to provide a connecting structure of a press-clamping terminal to a wire for achieving that the spring back force is not applied from the joint side plate to the conductor crimped piece as much as possible after crimping the conductor press-clamping portion, and thereby achieving a balance between the mechanical connecting structure and the electrical connecting structure, even in case of applying to an aluminum wire. In order to accomplish the above objects, the press-clamping terminal according to the present invention is configured as follows:

A first aspect of the invention is a press-clamping terminal to be connected to a shielded wire including a conductor and an insulated shield covering the conductor, the press-clamping terminal including: a bottom plate; a conductor press-clamping portion which includes a pair of conductor crimped

pieces which extend from opposite sides of the bottom plate and are bent inside to embrace the conductor; a shield crimping portion which includes a pair of shield crimped pieces which extend from the opposite sides of the bottom plate and are bent inside to embrace the insulated shield, so that one piece of the shield crimped pieces overlaps the other piece of the shield crimped pieces; and a first bell mouth which is longitudinally communicated with the shield crimping portion and expands obliquely outward away from the insulated shield at a first inclined angle.

In a second aspect of the invention, the first inclined angle is set within a range from 8 to 35 degrees.

In a third aspect of the invention, the press-clamping terminal, further includes a second bell mouth which is longitudinally communicated with the conductor press-clamping portion and expands obliquely outward away from the conductor at a second inclined angle. In a fourth aspect of the invention, the second inclined angle is set within a range from 8 to 35 degrees.

In a fifth aspect of the invention, the conductor is made of an aluminum or aluminum alloy.

A sixth aspect of the invention is a press-clamping terminal to be connected to a wire including a conductor, the press-clamping terminal including: an electric connecting portion for connecting to a mating terminal; a conductor press-clamping portion which includes: a bottom plate communicated with the electric connecting portion; and a pair of conductor crimped pieces which extend from opposite sides of the bottom plate and are bent inside to embrace the conductor; and a joint side plate which is provided between the conductor

press-clamping portion and the electric connecting portion to extend from the opposite sides of the bottom plate, and a joint end of the joint side plate being communicated with a joint end of the conductor crimped piece, wherein a crimp height of the conductor press-clamping portion from the bottom plate is made greater than a height of the joint end of the joint side plate.

In a seventh aspect of the invention, the conductor crimped pieces are crimped so as to meet the following expression: 2.5t > (CH - B) ≥ 0.5t; where t represents a thickness of the press-clamping terminal, CH represents the crimp height of the conductor press-clamping portion, and B represents the height of the joint end of the joint side plate.

In an eighth aspect of the invention, an inside width between the pair of the conductor crimped pieces in a certain height is set to be larger than an outside width between the joint side plates in the certain height, the certain height indicating the height of the joint end of the joint side plates. According to the first aspect of the invention, the pair of the conductor crimped pieces is crimped on the periphery of the insulated shield, so that one piece of the conductor crimped pieces of the shield crimping portion overlaps the other piece of the conductor crimped pieces, and the first bell mouth is formed at the shield crimping portion after the crimping. Thus, the effect of double crimping of the shield crimped pieces and the effect of rib by the first bell mouth can enhance the rigidity of the shield crimping portion and the clamping force subjected to the shielded wire. As a result, it is possible to enhance the connecting strength of the press-clamping terminal with respect to the shielded wire by just that much. It is not necessary to crimp the conductor press-clamping portion at two points as usual and to sacrifice the electric

performance of the conductor press-clamping portion. Since the first bell mouth is provided at the shield crimping portion, excessive load caused by an edge of the shielded crimping portion is not applied to the insulated shield, and the damage to the insulated shield is prevented. According to the second aspect of the invention, since the inclined angle of the first bell mouth provided at the shield crimping portion is set within the range from 8 to 35 degrees, it is possible to effectively suppress the damage to the insulated shield and to keep a contact pressure between an inner face of the bell mouth and the surface of the insulated shield. Thus, it is possible to enhance the clamping strength of the shield crimping portion. Temporarily, if the inclined angle of the first bell mouth is less than 8 degrees, the edge of the shielded crimping portion is liable to contact the insulated shield, and thus the shielded crimping portion can be damaged easily. On the contrary, if the inclined angle of the first bell mouth exceeds 35 degrees, a gap is liable to be occurred between the inside of the first bell mouth and the surface of the shielded wire, and thus clamping effect of the contact pressure is reduced.

According to the third aspect of the invention, the second bell mouth is formed at the conductor press-clamping portion after the crimping. Thus, a larger radial thickness of the conductor corresponding to a ruptured portion can be kept, and the ruptured strength of the conductor can be enhanced. Further, contact pressure applied between the inside of the second bell mouth and the surface of the conductor can be secured, and the clamping strength of the conductor press-clamping portion can be kept highly. As a result, it is possible to enhance the connecting strength of the press-clamping terminal with respect to the shielded wire.

Il

According to the fourth aspect of the invention, the second bell mouth is formed the conductor press-clamping portion, and the inclined angle of the second bell mouth is set within the range from 8 to 35 degrees. Thus, a larger radial thickness of the conductor corresponding to a ruptured portion can be kept, and the ruptured strength of the conductor can be enhanced. Further, contact pressure applied between the inside of the second bell mouth and the surface of the conductor can be secured, and the clamping strength of the conductor press-clamping portion can be kept highly. As a result, it is possible to enhance the connecting strength of the press-clamping terminal with respect to the shielded wire. Temporarily, if the inclined angle of the second bell mouth is less than 8 degrees, an edge of the second bell mouth contacts the conductor excessively, and thus the conductor can be damaged easily. On the contrary, if the inclined angle of the second bell mouth exceeds 35 degrees, a gap is liable to be occurred between the inside of the second bell mouth and the surface of the conductor, and thus clamping effect of the contact pressure is reduced.

According to the fifth aspect of the invention, since the connecting structure is applied in use of the aluminum wire, press-clamping work is performed without the excessive load to a conductor made of aluminum or aluminum alloy, the tensile strength of which is less than that of the copper conductor.

According to the sixth aspect of the invention, since the crimp height of the conductor press-clamping portion from the bottom plate is made greater than the height of the joint end of the joint side plate, it can be prevented to involve the joint side plate together as much as possible when the conductor crimped pieces are bent inside to be crimped to the conductor of the wire. Consequently,

it is possible to evade the occurrence of the spring back force applied to the joint side plate, and to prevent the expanding force from applying to conductor crimped pieces by the spring back force. Thus, the mechanical connecting performance and the electrical connecting performance can be enhanced. According to the seventh aspect of the invention, the above-mentioned effect can be surely obtained even in consideration of the tolerance in work dimension. Further, unnecessary stress concentration can be evaded and deterioration of the mechanical strength can be prevented.

According to the eighth aspect of the invention, the above-mentioned effect can be surely obtained.

According to the present invention, even in case of applying to an aluminum wire, it is possible to achieve a balance between the mechanical connecting structure and the electrical connecting structure while decreasing the damage to the aluminum wire, and therefore, a high reliable connecting structure can be provided.

According to the present invention, the expansion of the conductor crimped piece after crimping can be prevented as much as possible. Thus, a balance between the mechanical connecting structure and the electrical connecting structure is achieved even in case of applying to an aluminum wire.

Brief Description of Drawings

FIGs. 1A to 1 D are drawings for describing a connecting structure of a press-clamping terminal to a shielded wire according to a first embodiment of the present invention, and in particular, FIG. 1 A is an outlined side view for showing a state where the shielded wire is connected to the press-clamping terminal; FIG.

1 B is an enlarged perspective view of Ib part shown in FIG. 1A; FIG. 1 C is a cross-sectional view taken from line Ic-Ic of FIG. 1 B; and FIG. 1 D is a cross-sectional view taken from line Id-Id of FIG. 1 B.

FIGs. 2A and 2B are cross-sectional views of a bell mouth shown by arrow Il of FIG. 1A, and in particular, FIG. 2A is a drawing for showing a case where an inclined angle of the bell mouth is too large; and FIG. 2B is a drawing for showing a case where the inclined angle of the bell mouth is within a appropriate range.

FIGs. 3A and 3B are characteristic plots in the connecting structure according to the first embodiment, and in particular, FIG. 3A is a characteristic plot for showing a relationship between an inclined angle of the bell mouth of a conductor press-clamping portion and a retaining strength; and FIG. 3B is a characteristic plot for showing a relationship between an inclined angle of the bell mouth of a shield crimping portion and a retaining strength. FIG. 4A is a plan view for showing a press-clamping structure between an aluminum wire and a terminal in a related art; and FIG. 4B is a side view of the press-clamping structure.

FIG. 5A is a side view for showing a press-clamping structure of a press-clamping terminal onto a wire according to a second embodiment of the invention, and FIG. 5B is an enlarged view of Vb portion in FIG. 5A.

FIG. 6 is a plan view of a main part for showing a state before crimping of the press-clamping terminal to achieve the press-clamping structure according to the second embodiment.

FIG. 7 is a perspective view for describing a general open-barrel typed press-clamping terminal and a press-clamping method thereof.

FIG. 8 is a cross-sectional view for showing a portion in which the press-clamping terminal is press-clamped to a wire.

FIGs. 9A and 9B are drawings for showing a press-clamping structure of a known press-clamping terminal; FIG. 9A is an outlined side view, and FIG. 9B is an enlarged view of IXb portion in FIG. 9A.

FIG. 10 is a partial plan view for explaining a problem in the known art.

Best Mode for Carrying Out the Invention

Preferred embodiments according to the present invention will now be described in detail with reference to the drawings. (First Embodiment)

FIGs. 1A to 1 D are drawings for describing a connecting structure of a press-clamping terminal to an aluminum wire (hereinafter, refer to a shielded wire) according to a first embodiment of the present invention, and in particular, FIG. 1 A is an outlined side view for showing a state where the shielded wire is connected to the press-clamping terminal; FIG. 1 B is an enlarged perspective view of Ib part shown in FIG. 1 A; FIG. 1 C is a cross-sectional view taken from line Ic-Ic of FIG. 1 B; and FIG. 1 D is a cross-sectional view taken from line Id-Id of FIG. 1 B. FIGs. 2A and 2B are cross-sectional views of a bell mouth shown by arrow Il of FIG. 1 A, and in particular, FIG. 2A is a drawing for showing a case where an inclined angle of the bell mouth is too large; and FIG. 2B is a drawing for showing a case where the inclined angle of the bell mouth is within a appropriate range. FIGs. 3A and 3B are characteristic plots in the connecting structure according to the first embodiment, and in particular, FIG 3A is a characteristic plot for showing a relationship between an inclined angle of the bell mouth of a conductor

press-clamping portion and a retaining strength (a tensile strength); and FIG. 3B is a characteristic plot for showing a relationship between a retaining strength (a tensile strength) when adding the conductor press-clamping portion to the shield crimping portion and an inclined angle of the bell mouth of a shield crimping portion.

A press-clamping terminal 1 to be employed here is formed by press-molding a conductive metal (mainly, copper-made or copper alloy-made) plate. The press-clamping terminal 1 includes an electric connecting portion 2 which contacts and is electrically connected to a mating terminal at a front side in an extending direction of a shielded wire W, that is, in a longitudinal direction of the press-clamping terminal 1 , and a wire fixing portion 3 which fixes an end of the shielded wire W at a rear side. Hereinafter, the longitudinal direction is referred to "back and forth direction," and a direction perpendicular to the longitudinal direction is referred to "horizontal direction." The shielded wire W includes an exposed conductor Wa formed of a bundle of strands (such as twisted wires) and an insulated shield Wb for covering a periphery of the conductor. The wire fixing portion 3 includes a conductor press-clamping portion 4 which is arranged at a front side and crimped with respect to the exposed conductor Wa of the shielded wire W, and a shield crimping portion 5 which is arranged at a rear side and crimped with respect to the insulated shield Wb of the shielded wire W. The electric connecting portion 2, the conductor press-clamping portion 4 and the shield crimping portion 5 share a common bottom plate 11.

The conductor press-clamping portion 4 corresponds to a U-shaped portion on cross-section, which is up-formed by upwardly extending a pair of

conductor crimped pieces 14 from opposite ends in the horizontal direction of the bottom plate 11 continued from the electric connecting portion 2. The shield crimping portion 5 corresponds to a U-shaped portion on cross-section, which is up-formed by upwardly extending a pair of shield crimped pieces 15 from opposite ends in the horizontal direction of the bottom plate 11. The shield crimping portion 5 and the conductor press-clamping portion 4 are arranged away from each other at an appropriate interval (arrangement in adjacent manner) in the back and forth direction of the press-clamping terminal 1. Each of a height and a width of the pair of the shield crimped pieces 15 is set to a dimension enough to be crimped so as to overlap each other on the periphery of the insulated shield Wa as described below.

In order to connect the press-clamping terminal 1 onto the shielded wire W, the pair of the conductor crimped pieces 14 are bent to be curled inside with a use of an upper mold and a lower mold to press-clamp the conductor press-clamping portion 4 onto the exposed conductor Wa of the end of the shielded wire W, and furthermore, the pair of the shield crimped pieces 15 are bent to be curled inside with a use of the molds to crimp the shield crimping portion 5 on a portion containing the insulated shield Wb of the shielded wire W.

The pair of the shield crimped pieces 15 is crimped on the periphery of the insulated shield Wb, so that one piece of the shield crimped pieces 15 of the shield crimping portion 5 overlaps the other piece of the shield crimped pieces 15. In addition, the pair of the shield crimped pieces 15 is crimped so that a bell mouth (a first bell mouth) 15a, which expands obliquely outward away from the periphery of the insulated shield Wb, is formed at a back end of the shield crimping portion 5 corresponding to a proximal side of the shielded wire W. In

this case, an inclined angle (expanding angle) θ of the bell mouth 15a is set within a range from 8 to 35 degrees.

The pair of the conductor crimped pieces 14 of the conductor press-clamping portion 4 is crimped, so that a bell mouth (a second bell mouth) 14a, which expands obliquely outward away from the surface of the conductor Wa, is formed at least at a back end of the conductor press-clamping portion 4, and in particular, an inclined angle α of the bell mouth 14a is set within a range from 8 to 35 degrees. In this way, the shield crimping portion 5 which includes the bell mouth 15a having the inclined angle θ (= 8 to 35 degrees) is obtained at the back end as shown in FIGs. 1 B to 1 D, and the conductor crimped portion 4 which includes the bell mouth 14a having the inclined angle α (= 8 to 35 degrees) is obtained at the back end as shown in FIG. 2B.

The bell mouths 14a, 15a can be unconsciously formed by crimping the crimped portion while keeping a non-crimped portion adjacent to the crimped portion. That is, high compressive force is applied to the wire corresponding to inside of the crimped portion, whereas the compressive force is hardly applied to the wire corresponding to inside of the non-crimped portion. A similar difference is occurred between the crimped portion and the non-crimped portion as to the compressive force applied to the conductor crimped piece 14 and the shield crimped piece 15. Therefore, the bell mouths 14a, 15a each having an inclined angle (expanding angle) α, θ can be formed at the ends of the conductor press-clamping portion 4 and the shield crimping portion 5, respectively, in accordance with a compressive deformation of wires, and the conductor crimped pieces 14 and the shielded crimped pieces 15. As described above, in the connecting structure according to the first

embodiment, the pair of the conductor crimped pieces 15 is crimped on the periphery of the insulated shield Wb, so that one piece of the shield crimped pieces 15 of the shield crimping portion 5 overlaps the other piece of the shield crimped pieces 15, and the bell mouth 15a is formed at the back end of the shield crimping portion 5 after the crimping. Thus, the effect of double crimping of the shield crimped pieces 15 and the effect of rib by the bell mouth 15a can enhance the rigidity of the shield crimping portion 15 and the clamping force to the shielded wire W. As a result, it is possible to enhance the connecting strength of the press-clamping terminal with respect to the shielded wire W by just that much.

Consequently, it becomes possible to allow the ratio of the connecting strength on the shield crimping portion 5 higher than usual out of the connecting strength on both the conductor press-clamping portion 4 and the shield crimping portion 5. The press-clamping of the conductor press-clamping portion 4 can be done at a higher compressibility while enhancement of the electric performance is emphasized rather than the mechanical strength. According to the configuration, it is not necessary to crimp the conductor press-clamping portion 5 at two points as usual and to sacrifice the electric performance of the conductor press-clamping portion 5. Since the bell mouth 15a is provided at the back end of the shield crimping portion 5, excessive load caused by an edge of the shielded crimping portion 15 is not applied to the insulated shield Wb, and the damage to the insulated shield Wb is prevented.

Since the inclined angle θ of the bell mouth 15a provided at the back side of the shield crimping portion 5 is set within the range from 8 to 35 degrees,

it is possible to effectively suppress the damage to the insulated shield Wb and to keep a contact pressure between an inner face of the bell mouth 15a and the surface of the insulated shield Wb. Thus, it is possible to enhance the clamping strength of the shield crimping portion 5. If the inclined angle θ of the bell mouth 15a is less than 8 degrees, the edge of the shielded crimping portion 15 is liable to contact the insulated shield Wb, and thus the shielded crimping portion 15 can be damaged easily. On the contrary, if the inclined angle θ of the bell mouth 15a exceeds 35 degrees, a gap is liable to be occurred between the inside of the bell mouth 15a and the surface of the shielded wire Wb, and thus clamping effect of the contact pressure is reduced.

Furthermore, in the connecting structure according to the first embodiment, the bell mouth 14a is formed at the back side of the conductor press-clamping portion, and the inclined angle α of the bell mouth 14a is set within the range from 8 to 35 degrees as shown in FIG. 2B. Thus, a larger radial thickness of the conductor Wa corresponding to a ruptured portion can be kept, and the ruptured strength of the conductor Wa can be enhanced. Further, contact pressure F applied between the inside of the bell mouth 14a and the surface of the conductor Wa can be secured, and the clamping strength of the conductor press-clamping portion 4 can be kept highly. As a result, it is possible to enhance the connecting strength of the press-clamping terminal 1 with respect to the shielded wire W.

If the inclined angle α of the bell mouth 14a is less than 8 degrees, an edge 14e of the bell mouth 14a contacts the conductor Wa excessively, and thus the conductor Wa can be damaged easily. On the contrary, if the inclined angle

α of the bell mouth 14a exceeds 35 degrees as shown in FIG. 2A ₁ a gap is liable to be occurred between the inside of the bell mouth 14a and the surface of the conductor Wa ₁ and thus clamping effect of the contact pressure is reduced.

This matter is apparent from the characteristic plot shown in FIG. 3A. In case that the inclined angle α of the bell mouth 14a of the conductor press-clamping portion 4 is set within the range from 8 to 35 degrees, the high retaining strength of the conductor press-clamping portion 4 with respect to the wire is kept. However, if the inclined angle α is set out of the range, especially it exceeds 35 degrees, the retaining strength tends to be extremely lowered. Therefore, setting the inclined angle α of the bell mouth 14a within the range from 8 to 35 degrees enhances the retaining strength.

As shown in FIG. 3B, the inclined angle θ of the bell mouth 15a of the shield crimping portion 5 exceeds 35 degrees, it can be found that the retaining strength of sum of the conductor press-clamping portion 4 and the shield crimping portion 5 tends to be gradually lowered.

As described above, according to the connecting structure of the first embodiment, it is achieved that a balance between the mechanical connecting structure (high tensile strength) and the electrical connecting structure (low electric resistance) while decreasing the damage to the shielded wire W. Especially, since the connecting structure of the embodiment is applied in use of the aluminum wire W, press-clamping work is performed without the excessive load to a conductor made of aluminum or aluminum alloy, the tensile strength of which is less than that of the copper conductor. Even if the insulated shield Wb of the shielded wire W is made of resin containing halogen element, the insulated shield Wb can be effectively prevented from being damaged or broken.

As a specific example of the aluminum alloy, alloy of aluminum and copper can be employed. In case such an aluminum alloy is employed, it is possible to enhance the strength (especially, tensile strength) due to the better extension of the aluminum alloy as compared with aluminum conductor. In the above, description is made of that the bell mouth 14a is formed at the back end of the conductor crimped piece 14. However, as shown in FIGs. 1 A and 1 B, the bell mouth 14a may be formed at the front side of the conductor crimped piece 14. (Second Embodiment) FIG. 5A is a side view for showing a press-clamping structure of a press-clamping terminal onto a wire according to a second embodiment of the invention. FIG. 5B is an enlarged view of Vb portion in FIG. 5A. FIG. 6 is a plan view of a main part for showing a state before crimping of the press-clamping terminal to achieve the press-clamping structure according to the second embodiment.

In a press-clamping structure according to the second embodiment, a press clamping terminal 101 is configured to be press-clamped and fixed to a wire W to meet the following-mentioned conditions, and an aluminum wire having a conductor made of an aluminum or aluminum alloy is applied to this structure.

The press-clamping terminal 101 employed here includes an electric connecting portion 102 which contacts and is electrically connected to a mating terminal at a front side in a longitudinal direction of the press-clamping terminal 101 and a wire fixing portion 103 which fixes an end of a shielded wire W at a rear side. Hereinafter, the longitudinal direction is referred to "back and forth

direction," a direction perpendicular to the longitudinal direction is referred to "horizontal direction." The wire fixing portion 103 includes a conductor press-clamping portion 104 which is arranged at a front side and crimped with respect to an exposed conductor Wa of the shielded wire W, and a shield crimping portion 105 which is arranged at a rear side and crimped with respect to an insulated shield Wb of the shielded wire W. The electric connecting portion 102, the conductor press-clamping portion 104 and the shield crimping portion 105 share a common bottom plate 111.

The conductor press-clamping portion 104 corresponds to a U-shaped portion on cross-section, which is up-formed by upwardly extending a pair of conductor crimped pieces 114 from opposite ends in the horizontal direction of the bottom plate 111 continued from the electric connecting portion 102. The shield crimping portion 105 corresponds to a U-shaped portion on cross-section, which is up-formed by upwardly extending a pair of shield crimped pieces 115 from opposite ends in the horizontal direction of the bottom plate 111. The shield crimping portion 105 and the conductor press-clamping portion 104 are arranged away from each other at an appropriate interval in the back and forth direction. Each joint side plate 112 is provided between the conductor press-clamping portion 104 and the electric connecting portion 102 so as to upwardly extend from both sides of the bottom plate 111 and a rear end (a joint end) of the joint side plates 112 is continued to a front end (a joint end) of the conductor crimped piece 114. The joint side plate 112 makes a portion between the conductor press-clamping portion 104 and the electric connecting portion 102 being a U-shape on cross-section to enhance the bending rigidity. Here, as shown in FIG. 6, an inside width L between a pair of the conductor

crimped pieces 114 of the conductor press-clamping portion 104 is set to be larger than an outside width H between a pair of the joint side plates 112 in a height of an upper edge at a back end of the joint side plate 112, in the same height (a height of the joint end of the joint side plate 112). That is, the following relationship is established: L > H

Then, from a state where the exposed conductor Wa at the front end of the wire W is placed between the conductor crimped pieces 114 of the press-clamping terminal 101 , the pair of the conductor crimped pieces 114 are bent inside to be crimped so that the conductor press-clamping portion 104 is press-clamped onto the conductor Wa of the wire W. Further, from a state where a portion corresponding to the shield Wb of the wire W is placed on between the shield crimped pieces 115 of the press-clamping terminal 101 , the pair of the shield crimped pieces are bent inside to be crimped so that the portion corresponding to the shield Wb of the wire W is fixed to the shield crimped portion 105.

According to the above-mentioned configuration, the press-clamping structure of the embodiment is achieved. In this case, a crimp height CH from the bottom plate 111 of the conductor press-clamping terminal is set to be larger than a back end (a joint end) height B of the joint side plate 112. That is, the conductor press-clamping portion 104 is crimped to satisfy the expression: CH - B > 0 ... (1)

Therefore, according to the press-clamping structure, since the crimp height CH of the conductor press-clamping portion 104 is set to be larger than the back end height B of the joint side plate 112, it is prevented to involve the

joint side plate 112 together as much as possible when the conductor crimped pieces 114 is bent inside to be crimped to the conductor Wa of the wire W.

Consequently, it is possible to evade the occurrence of the spring back force applied to the joint side plate 112, and to prevent the expanding force from applying to conductor crimped pieces 114 by the spring back force. Thus, the mechanical connecting performance and the electrical connecting performance is enhanced.

According to the press-clamping structure, since the connecting structure is applied in use of the aluminum wire having a conductor made of aluminum or aluminum alloy, a balance between enhancement of the electrical performance and the mechanical performance is achieved in the conductor made of aluminum or aluminum alloy, the tensile strength of which is less than that of the copper conductor.

Especially, when the press-clamping terminal 101 is configured to have a metal plate of t mm in thickness, the conductor crimped pieces 114 should be crimped so as to satisfy the expression: 2.5t > (CH - B) > 0.5t ... (2) This is because that, for example, if the expression: (CH - B) > 0.5t is satisfied, the spring back caused by the joint side plate 112 is adequately evaded, and if the expression: 2.5 t > (CH - B) is satisfied, the stress concentration applied to a step P at a joint portion between the joint side plate 112 and the conductor crimped piece 114 can be relaxed.

Next, the validity of the expression (2) is described with a specific example. In case it is assumed that the thickness t = 0.20 mm, the expression:

0.5t = 0.5 x 0.20 = 0.1 is derived. That is, it is required to satisfy (CH - B) ≥ 0.1 mm.

Here, an allowable tolerance of the crimp height CH is ± 0.05 mm in general. The variation in an actual finish of the back end height B of the joint side plate 112 is about ± 0.05 mm. In consideration of this matter, if the condition:

(CH - B) ≥ 0.5t ... (3) is set, (CH - B) = 0 is satisfied in the worst case. Therefore, when the condition (3) is satisfied, the appropriate result can be obtained in consideration of the tolerance in work dimension.

Further, when the upper limit is viewed, in case it is assumed that the thickness t = 0.20 mm, the expression:

2.5t = 2.5 x 0.20 = 0.5 is derived. Therefore, if the condition: 2.5U (CH - B) ... (4) is set, the difference between the crimp height CH of the conductor press-clamping portion 104 and the height B of the joint side plate 112 can be controlled within 0.5 mm. Therefore, the deterioration of the mechanical strength caused by the increase in the difference can be prevented. As a specific example of the aluminum alloy, alloy of aluminum and copper can be employed. In case such an aluminum alloy is employed, it is possible to enhance the strength (especially, tensile strength) due to the better extension of the aluminum alloy as compared with aluminum conductor.

The present invention is not limited to the above embodiments, and suitable modifications, improvements, etc., can be made. Furthermore, the

shape, dimensions, numerical values, form, disposition, etc., of each of the constituent elements of the above embodiments can be arbitrary and are not limited in so far as the invention can be achieved.

Industrial Applicability

According to the present invention, a connecting structure can be provided to achieve a balance between the mechanical connecting structure

(high tensile strength) and the electrical connecting structure (low electric resistance) while decreasing the damage to a shielded wire, especially in use of an aluminum wire as the shielded wire.