Power connector and power terminal assembly

Abstract

The present invention discloses a power connector and a power terminal group, wherein the power connector includes an insulating housing and at least one power terminal group. The insulating housing has at least one terminal accommodating hole. At least one power terminal group is inserted into the at least one terminal accommodating hole; wherein each power terminal group has an inner terminal and an outer terminal, wherein each inner terminal has a connecting section and an elastic section connected to the connecting section, each of the outer terminals has a conducting portion, a pin portion located at one end of the conducting portion, and a bending portion located between the conducting portion and the pin portion, the pin portion is exposed from the insulating housing, and the connecting section of the inner terminal is fixedly connected to the conducting portion of the outer terminal.

Description

Technical Field

[0001] The invention relates to a power connector and a power terminal group thereof, in particular to a power connector and a power terminal group thereof capable of transmitting relatively large current. Background Art

[0002] As electronic technology develops, electronic devices have an increasing demand for current, so power connectors require stronger power terminal sets to withstand larger currents.

[0003] In order to transmit a larger current, the power terminal group needs to be made of purer copper metal to provide better conductivity and avoid power loss. However, pure copper is softer, has good ductility, and poor mechanical strength. Therefore, it is necessary to provide terminals with better elasticity to clamp the inserted male terminals or electrical contact module cards to produce better electrical contact. This method can be made of copper alloy. However, how to combine two metals of different materials while transmitting a larger current and making the terminals in close contact is a problem that the industry needs to face. Summary of the invention

[0004] The main purpose of the present invention is to provide a power connector and a power terminal group thereof, wherein the power terminal group has outer terminals with better conductive properties to conduct larger currents and inner terminals with better clamping force to elastically clamp inserted terminals or module cards.

[0005] Another object of the present invention is to provide a power connector and a power terminal group thereof, wherein the power terminal group has a heat dissipation structure for dissipating waste heat generated during the transmission of large currents.

[0006] To achieve the purpose described above, one embodiment of the present invention provides a power connector, which includes an insulating shell and at least one power terminal group. The insulating shell has at least one terminal accommodating hole. At least one power terminal group is assembled in the at least one terminal accommodating hole; each power terminal group has an inner terminal and an outer terminal, each inner terminal has a connecting section and an elastic section connected to the connecting section, each outer terminal has a conductive portion, a pin portion located at one end of the conductive portion, and a bent portion located between the conductive portion and the pin portion, the pin portion is exposed from the insulating shell, and the connecting section of the inner terminal is fixedly connected to the conductive portion of the outer terminal.

[0007] To achieve the purpose described above, the present invention also provides a power terminal group, including an inner terminal and an outer terminal, wherein each of the inner terminals has a connecting section and an elastic section connected to the connecting section, and each of the outer terminals has a conducting portion, a pin portion located at one end of the conducting portion, and a bending portion connecting the conducting portion and the pin portion, wherein the conducting portion is in the shape of a plate, the pin portion is exposed outside the insulating shell, and the connecting section of the inner terminal is fixedly connected to the conducting portion of the outer terminal.

[0008] Preferably, the bent portion of the outer terminal has a plurality of heat dissipation ribs.

[0009] Preferably, the conductivity coefficient of the outer terminal is greater than the conductivity coefficient of the inner terminal; wherein the elasticity coefficient of the inner terminal is greater than the elasticity coefficient of the outer terminal.

[0010] Preferably, the inner terminal further has a heat dissipation section, which is connected to the connecting section and opposite to the elastic section.

[0011] The beneficial effect of the present invention may be that the power connector and the power terminal group provided by the embodiment of the present invention may be suitable for power connectors that transmit large currents, and the elastic section of the inner terminal provides a better clamping force for elastically clamping the inserted terminal or module card to ensure good electrical contact. The outer terminal may use a material with better conductivity to transmit a larger current. The power terminal group of the present invention also provides a heat dissipation structure, which may be formed on the outer terminal or the inner terminal. The outer terminal may be provided with a plurality of heat dissipation ribs, which are integrally formed and protrude outward from the surface of the bent portion. The inner terminal may extend backward to form a heat dissipation section, which may increase the heat dissipation area.

[0012] In order to further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. Herein, preferred feasible implementation methods are given. However, the attached drawings are only provided for reference and description and are not used to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a perspective exploded view of the first embodiment of the power connector of the present invention.

[0014] Figure 2 It is a perspective view of a first embodiment of a power terminal group according to the present invention.

[0015] Figure 3 It is a perspective exploded view of the first embodiment of the power terminal group of the present invention.

[0016] Figure 4 It is a side view of the first embodiment of the power terminal group of the present invention.

[0017] Figure 4A It is a cross-sectional view of the first embodiment of the power connector of the present invention.

[0018] Figure 5 It is a perspective exploded view of the second embodiment of the power connector of the present invention.

[0019] Figure 6 It is a perspective view of a second embodiment of a power terminal group according to the present invention.

[0020] Figure 7 It is a perspective exploded view of a second embodiment of a power terminal assembly of the present invention.

[0021] Figure 8 It is a side view of a second embodiment of the power terminal group of the present invention.

[0022] Fig. 9 It is a perspective exploded view of a third embodiment of a power connector of the present invention.

[0023] Fig.10 It is a perspective view of a third embodiment of a power terminal group according to the present invention.

[0024] Fig.11 It is a perspective exploded view of a third embodiment of a power terminal group of the present invention.

[0025] Fig.12 It is a side view of a third embodiment of a power terminal group according to the present invention.

[0026] Fig.13 It is a perspective exploded view of a fourth embodiment of a power connector of the present invention.

[0027] Fig.14 It is a perspective view of a fourth embodiment of a power terminal group according to the present invention.

[0028] Fig.15 It is a perspective exploded view of a fourth embodiment of a power terminal group according to the present invention.

[0029] Fig.16 It is a side view of a fourth embodiment of a power terminal group according to the present invention. DETAILED DESCRIPTION

[0030] [First embodiment]

[0031] Please refer to Figure 1 and Figure 2, are respectively a stereoscopic exploded view of a first embodiment of a power connector of the present invention and a stereoscopic view of a first embodiment of a pair of power terminal groups. The present invention provides a power connector 100, which includes an insulating housing 10 and a plurality of pairs of power terminal groups 20, 20'. The insulating housing 10 has a plurality of terminal accommodating holes 12, and the terminal accommodating holes 12 penetrate the insulating housing 10 along the longitudinal direction of the power terminal group 20. Each terminal accommodating hole 12 includes two opposite plug-in slots 122 to respectively accommodate a pair of power terminal groups 20, 20'. The insulating housing 10 also forms a plurality of snap-in holes 120, and a snap-in hole 120 is formed above and below each plug-in slot 122, and the snap-in hole 120 connects the plug-in slot 120 to the outside of the insulating housing 10. However, the number of the power terminal group and the terminal accommodating hole of the present invention can be at least one, and the number is not limited to this embodiment.

[0032] In this embodiment, each pair of power terminal groups 20, 20' has an inner terminal 21, 21 and an outer terminal 22, 22'. The inner terminal 21 of the upper power terminal group 20 is the same as the inner terminal 21' of the lower power terminal group 20'. The outer terminal 22 of the upper power terminal group 20 is slightly different from the outer terminal 22' of the lower power terminal group 20', and the difference between the two is mainly that the bending portion of the outer terminal 22' is smaller than the bending portion of the outer terminal 22. A square slot is formed between the pair of outer terminals 22, 22'. However, it can be understood that the present invention is not limited to this, and the upper outer terminal can be the same as the lower outer terminal. The following description principle is represented by the upper power terminal group 20. In addition, the number of power terminal groups in this embodiment can be at least one, for example, in a terminal accommodating hole 12, only one power terminal group 20 is provided at the upper plug-in slot 122, and only one outer terminal 22' is provided at the lower plug-in slot 122. Alternatively, only one power terminal set 20 ′ is disposed in the lower plug-in slot 122 , and only one external terminal 22 is disposed in the upper plug-in slot 122 .

[0033] See also Figure 2 and Figure 3 The power terminal set 20 has an inner terminal 21 and an outer terminal 22, wherein the inner terminal 21 has a connecting section 211 and an elastic section 212 connected to the connecting section 211. The outer terminal 22 has a conductive portion 221, a pin portion 223 located at one end of the conductive portion 221, and a bent portion 222 located between the conductive portion 221 and the pin portion 223. The pin portion 223 is exposed to the insulating housing 10, and the connecting section 211 of the inner terminal 21 is fixedly connected to the conductive portion 221 of the outer terminal 22, preferably by welding, but not limited thereto. The elastic section 212 of the inner terminal 21 has at least one elastic arm (as represented by reference numerals 2121 and 2124) extending in a direction away from the connecting section 211.

[0034] In order to cope with the heat that may be generated during the high current transmission process, in this embodiment, the bent portion 222 of the external terminal 22, 22' has a plurality of heat dissipation ribs 2221 to increase the heat dissipation area of ​​the external terminal 22, 22'. The heat dissipation ribs 2221 can be directly stamped from the bent portion 222 and protrude outward from the surface of the bent portion 222 in an integral manner.

[0035] See also Figure 3 The structure of the inner terminal is described in detail below. The connecting section 211 of the inner terminal 21 has two opposite outer sides, and each outer side has two interference protrusions 2111 protruding from the two sides of the conductive portion 221 of the outer terminal 22. In addition, each outer side also has an auxiliary welding portion 2110 adjacent to the interference protrusions 2111. The auxiliary welding portion 2110 of this embodiment is located between the two interference protrusions 2111. The auxiliary welding portion 2110 in this embodiment is notched and recessed inward from the outer side. In principle, it is a non-linear recessed shape, such as a sawtooth shape, which helps the connecting section 211 of the inner terminal 21 to be welded to the conductive portion 221 of the outer terminal 22. The number of the above-mentioned interference protrusions 2111 can be at least one. The above-mentioned interference protrusions 2111 are conducive to fixing the inner terminal 21 in the insulating housing 10 in an interference manner, and the auxiliary welding portion 2110 is conducive to welding and fixing the inner terminal 21 to the outer terminal 22.

[0036] In this embodiment, the connecting section 211 of the inner terminal 21 further has a hooking portion 213, which is formed by punching the connecting section 211 and forming a punching hole 2130. The conducting portion 221 of the outer terminal 22 has an opening 2210, and the free end of the hooking portion 213 passes through the opening 2210 of the conducting portion 221 of the outer terminal 22. More specifically, the hooking portion 213 is slightly S-shaped, such as Figure 4A As shown, the local hooking portion 213 is bent and protrudes from one side of the connecting section 211, that is, away from the direction of the external terminal 22, and extends into the terminal accommodating hole 12 of the insulating housing 10; the hooking portion 213 is bent and extended through the punching hole 2130, and the free end of the hooking portion 213 passes through the punching hole 2130 and extends to the other side of the connecting section 211, that is, toward the direction of the external terminal 22, and away from the elastic section 212. The free end of the hooking portion 213 extends into the engaging hole 120 of the insulating housing 10. Since the hooking portion 213 passes through the opening 2210 of the conductive portion 221 and abuts against the engaging hole 120 of the insulating housing 10, the positioning of the power terminal set 20, 20' in the insulating housing 10 can be strengthened. In this way, the power terminal set 20, 20' can be provided with a function of preventing backward movement, and preventing the power terminal set 20, 20' from being displaced backward due to the force of the male terminal or the module card being inserted.

[0037] See also Figure 3 and Figure 4 , Figure 4 It is a side view of the first embodiment of the power terminal group of the present invention. In this embodiment, the elastic section 212 of the inner terminal 21 has an elastic arm 2121 (or called the first elastic arm) extending in a direction away from the connecting section 211 and a pair of outer elastic arms 2124 (or called the second elastic arm) extending toward the connecting section 211, and the elastic arm 2121 is located between the pair of outer elastic arms 2124. The elastic arm 2121 is bent and extended outward from the middle of one side edge of the connecting section 211, and the elastic arm 2121 has a bent contact portion near the free end. The two ends of the side edge of the connecting section 211 each have an extension arm 2123, and the outer elastic arm 2124 is bent and extended from the free end of the extension arm 2123 toward the connecting section 211.

[0038] See also Figure 4 The advantage of the present invention is that it can be applied to power connectors that transmit large currents. The elastic section 212 of the inner terminal 21 can be used to elastically clamp the terminal of the plug connector or the module card (not shown) to ensure good electrical contact. The outer terminal 22 or 22' can be made of a material with better conductivity to transmit larger currents.

[0039] Preferably, the conductivity of the outer terminals 22, 22' is greater than the conductivity of the inner terminal 21; the elastic modulus of the inner terminal 21 is greater than the elastic modulus of the outer terminals 22, 22'. The modulus of elasticity is also called the Young's modulus (unit: N / m 2 ). It is defined as the ratio of stress to corresponding strain of an ideal material at small deformation. The elastic modulus is a material constant that characterizes the material's ability to resist elastic deformation. Its value reflects the ease with which the material can be elastically deformed.

[0040] More specifically, the outer terminals 22, 22' are used to conduct larger currents, and therefore are preferably made of pure copper. However, pure copper is relatively soft, has good ductility, and has poor mechanical strength. The present embodiment utilizes an inner terminal 21 having a larger elastic coefficient to provide a better clamping force to elastically clamp a terminal or module card (not shown) inserted into a power connector. The inner terminal 21 is preferably made of a copper alloy, such as brass or bronze by adding zinc or tin, which can increase its mechanical strength and corrosion resistance. Brass is an alloy of copper and zinc, with a golden color, good corrosion resistance, excellent strength, and is easy to cast and machine. Bronze is an alloy of copper and several other elements including tin, aluminum, silicon, and nickel. For example, beryllium bronze and beryllium copper alloy. The beryllium content is 1.7% to 2.5%. Beryllium bronze has high elastic limit and fatigue limit, excellent wear resistance and corrosion resistance, and good electrical and thermal conductivity; phosphor bronze, adding phosphor to bronze, can form an extremely hard compound, increase wear resistance and corrosion resistance, and is suitable for making spring materials. The proportion is about 91% to 97% copper, 3% to 9% tin, and 0.2% phosphorus bronze, with high hardness and fatigue resistance.

[0041] [Second Embodiment]

[0042] Please refer to Figure 5 and Figure 6 , respectively, are a perspective exploded view of a second embodiment of a power connector of the present invention and a perspective view of a second embodiment of a pair of power terminal groups. In this embodiment, the power connector 100a includes an insulating housing 10a and a plurality of pairs of power terminal groups 20a, 20a'. The insulating housing 10a has a plurality of terminal accommodating holes 12. Each pair of power terminal groups 20a, 20a' has an inner terminal 21a, 21a and an outer terminal 22a, 22a'. The inner terminal 21a has a connecting section 211 and an elastic section 212 connected to the connecting section 211. The outer terminal 22a (or 22a') has a conductive portion 221, a pin portion 223 located at one end of the conductive portion 221, and a bent portion 222 located between the conductive portion 221 and the pin portion 223.

[0043] See also Figure 7 and Figure 8 The main difference between this embodiment and the above embodiment is that the inner terminal 21a further has a heat dissipation section 215, which is connected to the connection section 211 and opposite to the elastic section 212. Each heat dissipation section 215 has a plurality of parallel heat dissipation gratings 2151 and a folded portion 2152 connecting the ends of the plurality of heat dissipation gratings 2151. Figure 8As shown, the heat dissipation grid 2151 is generally U-shaped and extends in a direction away from the outer terminal 20a (22a'). The heat dissipation section 215 of this embodiment makes good use of the space between the bent portions 222. The reversed portion 2152 of the upper inner terminal 21a further abuts against the bent portion 222 of the outer terminal 22a. The surface of the bent portion 222 of the outer terminal 22a of this embodiment is smooth, and of course it can also have the heat dissipation ribs of the above embodiment.

[0044] [Third Embodiment]

[0045] Please refer to Fig. 9 and Fig.10 , respectively, are a perspective exploded view of a third embodiment of a power connector of the present invention and a perspective view of a pair of power terminal sets of the third embodiment. In this embodiment, the power connector 100b includes an insulating housing 10b and a plurality of pairs of power terminal sets 20b, 20b'. The insulating housing 10b has a plurality of terminal accommodating holes 12 and a plurality of partitions 124 respectively located in the terminal accommodating holes 12. The partitions 124 are generally cross-shaped, and separate four spaces in each terminal accommodating hole 12.

[0046] Please refer to Fig.11 and Fig.12 , respectively, are a perspective exploded view and a side view of the third embodiment of the power terminal set of the present invention. Each pair of power terminal sets 20b, 20b' has an inner terminal 21b, 21b and an outer terminal 22b, 22b'. The inner terminal 21b has a connecting section 211 and an elastic section 212 connected to the connecting section 211. The outer terminal 22b (or 22b') has a conductive portion 221, a pin portion 223 located at one end of the conductive portion 221, and a bent portion 222 located between the conductive portion 221 and the pin portion 223. The difference from the above embodiment is that the elastic section 212 of the inner terminal 21b extends beyond the conductive portion 221 of the outer terminal 22b (or 22b'), and the elastic section 212 has a pair of elastic arms 2121 extending in a direction away from the connecting section. The length of the conductive portion 221 along the longitudinal direction is substantially equal to the length of the connecting section 211 along the longitudinal direction.

[0047] The cross-shaped partition 124 separates four spaces in the terminal receiving hole 12 to accommodate two pairs of elastic arms 2121 .

[0048] The shape of the connecting section 211 is the same as that of the first embodiment. In addition, the bending portion 222 has a plurality of heat dissipation ribs 2221 which are the same as those of the first embodiment.

[0049] The advantage of this embodiment is that the outer terminal 22b (or 22b') has a shorter conductive portion 221, which can save the material of the outer terminal 22b (or 22b'). Compared with other embodiments, the elastic arm 2121 of the inner terminal 21b of this embodiment is wider and can provide a stronger clamping force.

[0050] [Fourth Embodiment]

[0051] Please refer to Fig.13 and Fig.14 , respectively, are a perspective exploded view of a fourth embodiment of a power connector of the present invention and a perspective view of a pair of power terminal groups of the fourth embodiment. In this embodiment, the power connector 100c includes an insulating housing 10c and a plurality of pairs of power terminal groups 20c, 20c'. The insulating housing 10c has a plurality of terminal accommodating holes 12 and a plurality of partitions 124 respectively located in the terminal accommodating holes 12. The partitions 124 are generally cross-shaped, and separate four spaces in each terminal accommodating hole 12.

[0052] Please refer to Figure 14 to Figure 15 , Fig.15 : This is a three-dimensional exploded view of the fourth embodiment of the power terminal group of the present invention. Each pair of power terminal groups 20c, 20c' has an inner terminal 21c, 21c and an outer terminal 22c, 22c'. The inner terminal 21c has a connecting section 211 and an elastic section 212 connected to the connecting section 211. The outer terminal 22c (or 22c') has a conductive portion 221, a pin portion 223 located at one end of the conductive portion 221, and a bent portion 222 located between the conductive portion 221 and the pin portion 223. The bent portion 222 has a plurality of heat dissipation ribs 2221, which are integrally formed and protrude outward from the surface of the bent portion 222.

[0053] Please refer to Fig.15 The difference between this embodiment and the above embodiment is that the conductive portion 221 of the outer terminal 22c (or 22c') is formed into a forked shape and has a pair of forked arms 2212. The elastic segment 212 of the inner terminal 21c has a pair of arc-shaped bridge portions 2125, a pair of abutting portions 2126 respectively connected to the pair of arc-shaped bridge portions 2125 and respectively abutting against the pair of forked arms 2212, and a plurality of elastic arms 2127 extending from the abutting portions 2126. Each elastic segment 212 of this embodiment has three elastic arms 2127 extending forward and two elastic arms 2127 extending backward.

[0054] Please refer to Fig.16, is a side view of the fourth embodiment of the power terminal set of the present invention. Compared with other embodiments, the bifurcated arm 2212 of this embodiment is inclined toward the elastic section 212, thereby helping to share the stress of the inner terminal and strengthening the overall clamping force. In addition, the front ends of the plurality of elastic arms 2127 extend beyond the bifurcated arm 2212. In general, the number of elastic arms 2127 of this embodiment is greater than that of the above embodiments.

[0055] In summary, the beneficial effect of the present invention is that the power connector and the power terminal group provided by the embodiment of the present invention can be suitable for power connectors that transmit large currents, and the elastic section of the inner terminal provides a better clamping force to elastically clamp the terminal or module card of the plug connector (not shown) to ensure good electrical contact. The outer terminal can use a material with better conductivity to transmit a larger current.

[0056] The power terminal group of the present invention also provides a heat dissipation structure, which can be formed on the outer terminal or the inner terminal. The outer terminal can be provided with a plurality of heat dissipation ribs, which are integrally formed and protrude outward from the surface of the bent portion. The inner terminal can extend backward to form a heat dissipation section, and each heat dissipation section 215 has a plurality of parallel heat dissipation grids 2151, which can increase the heat dissipation area.

[0057] It should be noted that the words “substantially” and “approximately” in the present invention are used to modify any relationship that may vary slightly, such as slight inconsistencies caused by factors such as allowable processing errors, but such slight changes will not change its essence.

[0058] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention description and drawings are included in the protection scope of the present invention.

Claims

1. A power connector, characterized in that: include: An insulating housing having at least one terminal receiving hole; and At least one power terminal set is assembled in the at least one terminal receiving hole; wherein each power terminal set has: An inner terminal and an outer terminal, wherein each inner terminal has a connecting section and an elastic section connected to the connecting section, each outer terminal has a conducting portion, a pin portion located at one end of the conducting portion, and a bending portion located between the conducting portion and the pin portion, the pin portion is exposed outside the insulating housing, the connecting section of the inner terminal is fixedly connected to the conducting portion of the outer terminal, the connecting section has two opposite outer sides, and each of the outer sides also has an auxiliary welding portion for the inner terminal to be welded and fixed to the outer terminal; Wherein, the elastic section of the inner terminal has a first elastic arm and a second elastic arm, the first elastic arm has a bent contact portion near the free end, and the free end of the second elastic arm has a bent contact portion; wherein the contact portion at the free end of the first elastic arm and the contact portion on the free end of the second elastic arm are staggered front to back with each other.

2. The power connector according to claim 1, wherein: The bent portion of the outer terminal has a plurality of heat dissipation ribs.

3. The power connector according to claim 1, wherein: The conductivity coefficient of the outer terminal is greater than the conductivity coefficient of the inner terminal; wherein the elastic coefficient of the inner terminal is greater than the elastic coefficient of the outer terminal.

4. The power connector according to claim 1, wherein: The conductive portion of the external terminal is in a flat plate shape.

5. The power connector according to claim 1, wherein: The auxiliary welding portion is in the shape of a notch, and is recessed inward from the outer edge.

6. The power connector according to claim 1, wherein: The inner terminal also has a heat dissipation section, which is connected to the connection section and is opposite to the elastic section.

7. The power connector according to claim 1, wherein: The inner terminal has a pair of the second elastic arms, and the first elastic arm is located between the pair of the second elastic arms.

8. The power connector according to claim 7, wherein: The elastic section of the inner terminal extends beyond the conductive portion of the outer terminal, and the elastic section has a pair of first elastic arms extending in a direction away from the connecting section.

9. The power connector according to claim 1, wherein: The conductive portion of the outer terminal forms a forked shape and has a pair of forked arms, wherein the elastic section of the inner terminal has a pair of arc-shaped bridging portions, a pair of abutting portions respectively connected to the pair of arc-shaped bridging portions and respectively abutting against the pair of forked arms, and a plurality of the first elastic arms extending from the abutting portions.

10. The power connector according to claim 9, characterized in that: The bifurcated arm is inclined toward the elastic section.

11. The power connector according to claim 1, wherein: The power terminal group is in a pair and arranged opposite to each other, and a square slot is formed between the pair of external terminals.

12. A power terminal group, characterized in that: include: An inner terminal and an outer terminal, wherein each inner terminal has a connecting section and an elastic section connected to the connecting section, each outer terminal has a conducting portion, a pin portion located at one end of the conducting portion, and a bending portion connecting the conducting portion and the pin portion, wherein the conducting portion is in a flat plate shape, and the pin portion is exposed outside the insulating housing, the connecting section of the inner terminal is fixedly connected to the conducting portion of the outer terminal, the connecting section has two opposite outer sides, and each of the outer sides also has an auxiliary welding portion for the inner terminal to be welded and fixed to the outer terminal; Wherein, the elastic section of the inner terminal has a first elastic arm and a second elastic arm, the first elastic arm has a bent contact portion near the free end, and the free end of the second elastic arm has a bent contact portion; wherein the contact portion at the free end of the first elastic arm and the contact portion on the free end of the second elastic arm are staggered front to back with each other.

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