A crimping terminal

Abstract

The present application relates to the technical field of automobile wire harness terminals, in particular to a crimping terminal, which solves the problems of the existing technology that the corrosion inhibitor layer is easy to flow off and the structure of piercing cannot effectively accommodate the oxide layer debris when the copper-aluminum terminal is crimped, comprising a conductor crimping part and a corrosion inhibitor layer, the inner side of the conductor crimping part is formed with a crimping surface for crimping with the conductor of the wire, and the corrosion inhibitor layer covers at least the crimping surface of the conductor crimping part; the corrosion inhibitor layer comprises a carrier and nano-conductive particles dispersed in the carrier, and the carrier is a drying oil; before the conductor crimping part is crimped with the wire, the corrosion inhibitor layer is a liquid coating coated on the crimping surface, and after the conductor crimping part is crimped with the wire, the corrosion inhibitor layer is solidified into a solid film. The beneficial effect is that the drying oil is creatively selected as the carrier of the corrosion inhibitor layer, which is solidified into a tough solid film after being crimped with the aluminum wire. The problem that the liquid coating is easy to flow off under the vibration working condition in the existing technology is solved.

Description

Technical Field

[0001] This invention relates to the field of automotive wiring harness terminal technology, and in particular to a crimp terminal. Background Technology

[0002] In automotive electrical systems, traditional wiring harnesses primarily use copper wires as the carrier for energy and signal transmission. However, with the dwindling global copper resources and continuously rising prices, the cost of automotive wiring harnesses is constantly increasing. To reduce vehicle weight, lower fuel consumption, and reduce costs, the application of aluminum and aluminum alloy wires in the automotive field is gradually gaining attention.

[0003] However, aluminum and aluminum alloy wires face two major technical challenges when connected to conventional copper terminals: First, there is a large potential difference between aluminum and copper, which makes them prone to galvanic and electrochemical corrosion in humid environments, leading to increased contact resistance or even connection failure; Second, a dense oxide layer easily forms on the surface of aluminum and aluminum alloy wires. This oxide layer has high resistance characteristics, which significantly increases the contact resistance between the terminal and the wire, affecting the reliability of the electrical connection.

[0004] To alleviate the aforementioned problems, existing technologies employ copper-aluminum welded terminals, such as connecting copper terminals and aluminum wires via welding to avoid electrochemical corrosion caused by direct contact. However, welded terminals are costly and primarily suitable for larger-gauge wire harnesses, making them difficult to widely apply in automotive applications with numerous small-diameter wires. Furthermore, patent CN113314871A discloses a terminal capable of crimping small-diameter aluminum or aluminum alloy wires. This terminal coats the crimping surfaces of the conductor and insulation crimping portions with an anti-corrosion layer and incorporates a diamond-shaped pit piercing structure in the conductor crimping portion. This anti-corrosion layer mitigates copper-aluminum galvanic corrosion, while the diamond-shaped pit structure breaks down the oxide layer on the aluminum wire surface, improving the connection performance of the copper-aluminum terminal to some extent. This overcomes the shortcomings of traditional welded copper-aluminum terminals, which are only suitable for large-gauge wire harnesses, are costly, and cannot accommodate small-diameter aluminum wires. While this solution improves the connection performance between the aluminum wire and the terminal to some extent, the following areas still warrant improvement: Its corrosion inhibitor layer is made of mineral oil or synthetic oil as a carrier. The coating is in liquid state before and after crimping. Since the terminal is used in automobiles, the terminal is often under vibration. After crimping, the liquid coating is easy to be lost from the crimping part between the wire and the terminal under the action of vibration. It is difficult to maintain the filling effect on the micro gaps of the crimping interface after crimping, which leads to a reduction in corrosion resistance and service life. Its puncture structure is mainly composed of diamond-shaped pits, which can only break the oxide layer on the surface of the aluminum wire through the squeezing action of the pits. There is no dedicated debris collection structure. The debris generated after the oxide layer is broken will remain between the crimping interface of the terminal and the wire, which can easily cause unevenness of the contact interface and a reduction in contact area. During long-term service, this will lead to continuous fluctuation and increase in contact resistance, causing faults such as unstable electrical transmission and local heating, which will significantly reduce the service life and operational reliability of the terminal.

[0005] It should be noted that the above technical information is the result of the applicant's inventive analysis. This explanation is only intended to enhance the understanding of the general background technology of this application by those skilled in the art, and should not be regarded as an admission or implication in any form that the following technical information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] This invention proposes a crimp terminal, which solves the technical problem of how to improve the resistance to electrochemical corrosion of aluminum wires and copper terminals in the prior art.

[0007] The technical solution of this invention is implemented as follows: A crimp terminal includes a conductor crimping portion and a corrosion inhibitor layer. The inner side of the conductor crimping portion forms a crimping surface for crimping with a conductor wire. The corrosion inhibitor layer at least covers the crimping surface of the conductor crimping portion. The corrosion inhibitor layer includes a carrier and nano-conductive particles dispersed in the carrier, wherein the carrier is a drying oil. Before crimping the conductor crimping portion with the conductor wire, the corrosion inhibitor layer is a fluid coating applied to the crimping surface. After crimping, the corrosion inhibitor layer solidifies into a solid film. The corrosion inhibitor layer is liquid before crimping assembly, allowing for uniform coating and penetration to fill microscopic gaps in the crimping surface. After the terminal and conductor are crimped, relying on the oxidative curing properties of the drying oil, it can quickly solidify to form a dense, adherent solid protective film, effectively avoiding the easy loss of traditional liquid corrosion inhibitors under automotive vibration conditions, thereby solving the problem of poor electrochemical corrosion resistance between copper conductors and aluminum terminals.

[0008] Furthermore, the thickness of the corrosion inhibitor layer is 20~60μm. This thickness range facilitates the coating process and ensures that a sufficient solid filler layer is formed after pressing.

[0009] Furthermore, the drying oil is either tung oil or linseed oil. These two drying oils can undergo polymerization reactions in the air and volatilize some components, gradually forming a dense and tough solid film; at the same time, the doped nano-conductive particles can compensate for the insulating properties of the drying oil, ensure the conductive continuity of the pressing interface, and prevent the coating from affecting the electrical transmission performance.

[0010] Furthermore, the crimping surface of the conductor crimping portion is also provided with a piercing structure. This is used to efficiently remove the dense oxide layer on the surface of the aluminum conductor.

[0011] Furthermore, the piercing structure includes transverse grooves and longitudinal grooves, both of which have arc-shaped cross-sections. The presence of transverse and longitudinal grooves allows the corrosion inhibitor to adhere better to the crimping surface of the conductor crimping portion.

[0012] Furthermore, two adjacent transverse grooves and two adjacent longitudinal grooves are arranged intersecting to form a spike. During the crimping process, the spike pierces the oxide layer on the surface of the aluminum or aluminum alloy conductor and forces the oxide layer into the groove between the spikes. The groove serves to accommodate the pierced oxide layer debris, preventing debris from remaining at the crimping interface and causing increased contact resistance or unstable contact.

[0013] Furthermore, the transverse and longitudinal grooves are arranged perpendicularly to each other. The regular vertical groove network also facilitates manufacturing using standard stamping or etching processes, helping to ensure dimensional accuracy and consistency.

[0014] Furthermore, the center-to-center distance between two adjacent transverse grooves is 0.3~0.5mm, and the center-to-center distance between two adjacent longitudinal grooves is 0.3~0.5mm. This center-to-center distance ensures a sufficient number of peaks per unit area to guarantee sufficient removal of the oxide layer. An excessively large center-to-center distance results in sparse peaks and poor oxide layer removal; an excessively small center-to-center distance results in overly dense grooves, reducing the effective metal contact area and increasing manufacturing difficulty.

[0015] Furthermore, the height from the tip of the spike to the bottom of the transverse groove and the height from the tip of the spike to the bottom of the longitudinal groove are 0.06~0.1mm. The spike height is sufficient to pierce the oxide layer of conventional aluminum wires, which is approximately 5~15μm thick, and provides sufficient space for debris collection; at the same time, the thickness of the pierced structure is no more than 1 / 3 of the thickness of the conductor crimping portion. This limitation ensures that after the pierced structure is processed, the substrate of the conductor crimping portion still retains sufficient thickness to withstand the enormous pressure during crimping, preventing the conductor crimping portion from breaking or excessively deforming due to excessive thinning of the root thickness, thus guaranteeing the structural strength and reliability of the connection.

[0016] Furthermore, the terminal also includes an electrical connection portion located at the front end, with a conductor crimp portion disposed at the rear end of the electrical connection portion and integrally connected to it. The electrical connection portion can be a male or female structure, used to achieve insertion with mating terminals. The terminal also includes an insulating crimp portion for crimping with the insulation layer of the conductor, and an anti-corrosion layer also covers the insulating crimp portion. Anti-corrosion protection is also provided between the insulation layer and the terminal.

[0017] The beneficial effects of this invention are as follows: It creatively selects drying oil as the carrier for the corrosion inhibitor layer. This carrier is in a liquid state before crimping, facilitating coating. Furthermore, due to the fluidity of the corrosion inhibitor layer, it can fill the microscopic gaps between the conductor crimped portion and the aluminum wire after deformation during crimping. After crimping with the aluminum wire, the drying oil solidifies into a tough solid film through oxidative polymerization, allowing the corrosion inhibitor layer to solidify within the microscopic gaps between the conductor crimped portion and the aluminum wire. The solid film formed after crimping effectively solves the problem of easy loss of liquid coatings under vibration conditions in existing technologies, thus significantly improving the long-term stability of corrosion resistance and the service life of the terminals. Simultaneously, the nano-conductive particles in the corrosion inhibitor layer ensure the conductivity of the solid film, guaranteeing the reliability of the electrical connection.

[0018] By incorporating a piercing structure formed by the intersection of transverse and longitudinal grooves, the pointed tip effectively pierces and penetrates the dense oxide layer on the surface of the aluminum conductor during crimping, while the intersecting grooves create a dedicated collection space. Debris generated from oxide layer breakage can be collected within these grooves, preventing disordered accumulation of debris at the crimping interface and ensuring a large, flat metal contact surface between the terminal and the conductor's metal body. This structure effectively reduces fluctuations in contact resistance, improves the stability of the electrical connection, lowers the risk of localized overheating during long-term service, and further extends the terminal's service life and reliability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a crimp terminal structure according to the present invention; Figure 2 for Figure 1 Sectional view of AA; Figure 3 for Figure 1 BB section view; Figure 4 This is a schematic diagram of the puncture structure; Figure 5 A top view of the pierced structure; Figure 6 This is a cross-sectional view of the punctured structure.

[0021] In the diagram: 12, Electrical connection part; 51, Wire crimping part; 52, Conductor crimping part; 53, Insulation crimping part; 31, Anti-corrosion layer; 61, Puncture structure; 62, Point; 63, Transverse groove; 64, Longitudinal groove. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1, such as Figure 1 , Figure 2 , Figure 3 As shown, this embodiment provides a crimp terminal, which is generally composed of an electrical connection portion 12 located at the front end and a wire crimp portion 51 located at the rear end. The electrical connection portion 12 is integrally connected to the conductor crimp portion 52 of the wire crimp portion 51. For example, the entire terminal can be integrally manufactured from a single piece of copper or copper alloy sheet through a stamping process. The electrical connection portion 12 is located in... Figure 1 The portion shown is in female form and is used for insertion with the male terminal. In another embodiment, the electrical connection portion 12 can also be in male form. An insulating crimp portion 53 is connected to the rear end of the conductor crimp portion 52. The insulating crimp portion 53 is used to wrap and fix the insulating outer sheath of the wire during crimping.

[0024] The inner surface of the conductor crimp portion 52 forms a crimping surface for electrical and mechanical connection with the conductor portion of an aluminum or aluminum alloy wire. This crimping surface is entirely covered with an anti-corrosion layer 31. For example... Figure 2 , Figure 3 As shown, the resist layer 31 not only covers the pressing surface of the conductor pressing portion 52, but also extends and covers the inner surface of the insulating pressing portion 53. Before pressing, the resist layer 31 is a fluid coating that can be uniformly applied to a specific area of ​​the copper strip substrate before the terminal stamping process by means of roller coating, spraying, etc. The resist layer 31 consists of a drying oil as a carrier and nano-conductive particles uniformly mixed and dispersed in the carrier. Specifically, the drying oil can be tung oil or linseed oil, and the nano-conductive particles can be nano-copper powder or nano-aluminum powder, with an addition amount of 0.2% to 0.4% of the carrier mass.

[0025] In practical applications of crimp terminals, an aluminum wire with a suitable amount of insulation stripped is placed in the wire crimping part 51. A specialized crimping tool is used to simultaneously apply pressure to both the conductor crimping part 52 and the insulation crimping part 53. The crimping surface of the conductor crimping part 52 tightly wraps around and squeezes the aluminum wire conductor, while the insulation crimping part 53 wraps around and squeezes the insulation sheath. During this crimping process, the immense pressure ensures close contact between the conductor crimping part 52 and the wire conductor, and between the insulation crimping part 53 and the insulation sheath. After the crimping is complete, the corrosion inhibitor layer 31 is squeezed and filled into the microscopic voids. The dry oil carrier within it begins an oxidative polymerization reaction, gradually transforming from a liquid to a solid state at room temperature, ultimately forming a tough and highly adhesive solid film. This solid film permanently fills all the microscopic voids between the crimping interfaces, isolating air and moisture that could potentially cause electrochemical corrosion. Meanwhile, the nano-conductive particles uniformly dispersed in the solid film overlap or tunnel through each other to form a conductive network, making the solid film a good conductor of electricity and ensuring a low-resistance connection at the press interface.

[0026] In some alternative embodiments, the thickness of the resist layer 31 is controlled within the range of 20–60 μm. This thickness range ensures both the formation of a continuous solid film and sufficient filling capacity. If the thickness is less than 20 μm, it may not completely cover the microscopically uneven metal surface, resulting in insufficient local filling; if the thickness is greater than 60 μm, the excessively thick liquid coating is easily squeezed out in large quantities during crimping, causing waste and potentially contaminating the crimping tools. Furthermore, an excessively thick organic film layer itself may affect the stress relaxation characteristics after crimping. Although a specific thickness range is selected, it is understood that for terminals and wires of a specific size, those skilled in the art can determine the optimal and precise thickness value within this range through a limited number of experiments, with the interfacial resistance value and salt spray test compliance after crimping as optimization objectives.

[0027] Example 2, based on Example 1, a crimp terminal, such as... Figure 4 , Figure 5 , Figure 6 As shown, the conductor crimping portion 52 has a piercing structure 61 on its crimping surface. This piercing structure 61 specifically includes multiple parallel transverse grooves 63 and multiple parallel longitudinal grooves 64, both of which have arc-shaped cross-sections. In a preferred embodiment, the transverse grooves 63 and longitudinal grooves 64 are arranged perpendicularly to each other, thus forming a series of raised apexes 62 between them. These apexes 62 are arranged in a regular frustum-shaped matrix.

[0028] Furthermore, to ensure the density of the tip and its debris-carrying capacity, the center-to-center distance between two adjacent transverse grooves 63 is 0.3~0.5mm, and the center-to-center distance between two adjacent longitudinal grooves 64 is also 0.3~0.5mm. Preferably, the center-to-center distances are equal, for example, both are 0.4mm. Meanwhile, the vertical height from the tip of the tip 62 to the bottom of the transverse groove 63 and the vertical height to the bottom of the longitudinal groove 64 are both 0.06~0.1mm. This dimension is sufficient to ensure that the tip can effectively pierce the dense alumina layer, typically 515μm thick, on the surface of the aluminum conductor. To prevent excessive processing of the piercing structure 61 from weakening the structural strength of the conductor crimping portion 52, the overall protrusion height of the piercing structure 61 is no greater than 1 / 3 of the thickness of the substrate of the conductor crimping portion 52 (i.e., the thickness of the copper plate used to manufacture the terminal).

[0029] During the crimping process, as the conductor crimping portion 52 curls inward and presses against the aluminum wire, the tips of numerous pointed peaks 62 pierce the wire surface. The high contact stress effectively shears and breaks down the high-resistance oxide layer on the aluminum wire surface. Under continuous compressive force, the oxide layer debris generated by this breakage is pushed and retained in the three-dimensional trench network formed by the crisscrossing transverse trenches 63 and longitudinal trenches 64, moving away from the main contact interface between the tips of the pointed peaks 62 and the newly exposed pure aluminum substrate. Therefore, the pure aluminum material achieves a large-area, unobstructed, and tight contact with the terminal crimping surface (especially the top area of ​​the pointed peaks 62 and the areas beside the trenches), thus forming a stable and low-resistance metal-to-metal electrical connection. The trench's containment function fundamentally avoids increased and fluctuating contact resistance caused by residual debris, significantly improving the connection stability and reliability under long-term vibration and temperature variation conditions.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A crimp terminal, characterized in that, It includes a conductor crimping portion (52) and an anti-corrosion layer (31) disposed on the crimping surface of the conductor crimping portion (52). The anti-corrosion layer (31) includes a drying oil and nano-conductive particles dispersed in the drying oil. The anti-corrosion layer (31) is a fluid coating applied to the crimping surface. After the conductor crimping portion (52) is crimped with the wire, the anti-corrosion layer (31) can be cured into a solid film.

2. The crimp terminal according to claim 1, characterized in that, The thickness of the corrosion inhibitor layer (31) is 20~60μm.

3. The crimp terminal according to claim 1, characterized in that, The drying oil is tung oil or linseed oil.

4. The crimp terminal according to any one of claims 1 to 3, characterized in that, The conductor crimping part (52) is also provided with a piercing structure (61) on the crimping surface.

5. The crimp terminal according to claim 4, characterized in that, The puncture structure (61) includes a transverse groove (63) and a longitudinal groove (64), both of which have an arc-shaped cross-section.

6. The crimp terminal according to claim 5, characterized in that, Two adjacent transverse grooves (63) and two adjacent longitudinal grooves (64) are arranged to form a pointed top (62).

7. The crimp terminal according to claim 6, characterized in that, The transverse grooves (63) and the longitudinal grooves (64) are arranged perpendicular to each other.

8. The crimp terminal according to claim 7, characterized in that, The center distance between two adjacent transverse grooves (63) is 0.3~0.5mm, and the center distance between two adjacent longitudinal grooves (64) is 0.3~0.5mm.

9. The crimp terminal according to claim 6, characterized in that, The height from the tip (62) to the bottom of the transverse groove (63) and the height from the tip (62) to the bottom of the longitudinal groove (64) are 0.06~0.1mm; the thickness of the piercing structure (61) is not greater than 1 / 3 of the thickness of the conductor crimping part (52).

10. The crimp terminal according to claim 1, characterized in that, It also includes an electrical connection part (12) located at the front end, a conductor crimping part (52) disposed at the rear end of the electrical connection part (12) and integrally connected with the electrical connection part (12); it also includes an insulating crimping part (53) for crimping with the insulation layer of the conductor, and an anti-corrosion layer (31) covering the insulating crimping part (53).

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