Patent Description:
At present, under the premise of the lightweight of harnesses, aluminum wires will be widely used. However, as the terminals of electric consumption devices are mostly made of copper, aluminum wires should be connected to electric energy transmission copper parts. The electric energy transmission copper parts are generally solid, which wastes materials. In addition, the solid electric energy transmission copper parts are generally processed by hot forging, which consumes much energy, produces large processing errors, and has a high manufacturing cost. Moreover, when different shapes of electric energy transmission copper parts are connected to the aluminum wires by welding, different fixtures are required, which increases the cost and complicates the management of fixtures. Furthermore, the aluminum wires are also welded in a welding device during welding, but the aluminum wires are relatively long and soft, which not only increases the cost of the fixtures, but also makes it difficult to realize loading and unloading of materials in the automatic production, and after welding, the welding flash generated by the welding cannot be removed because aluminum wires are non-rotatable.

Patent application <CIT> discloses an aluminum terminal and a copper-aluminum transition connector, wherein the aluminum terminal includes an insertion cavity for inserting the aluminum wire. The insertion cavity includes a first cavity with an inner diameter matching with an outer diameter of the conductor core of the aluminum wire, and a second cavity with an inner diameter matching with an outer diameter of the insulation layer of the aluminum wire. The rear end of the first cavity is connected to the front end of the second cavity. The minimum wall thickness of the insertion cavity is not less than <NUM>/<NUM> times the wall thickness of the insulation layer. The copper-aluminum transition connector includes the copper terminal and at least one aluminum terminal. The copper terminal is fixed on the front end of the first cavity of the aluminum terminal. The solution described above not only can avoid cracks on the aluminum terminal during the crimping and rationalize the manufacturing cost, but also can improve the performance of the electrical conductivity between the aluminum terminal and the aluminum wire.

Patent application <CIT> discloses a joint of a copper terminal and an aluminium conductor. A copper terminal connecting member of the joint is connected to a conductive core of the aluminium conductor by means of a transition welding layer, and the joint can also be provided with a reinforcing welding layer. Further provided is a method for preparing the joint using plasma arc welding. The connection portion of the copper terminal with the aluminium conductor is filled with solder in a plasma arc welding manner, such that copper and aluminium are connected by means of the solder.

Therefore, in the technical field of electric connections, there is an urgent need for an electric energy transmission joint which can further reduce the weight of copper terminals and the cost of aluminum harnesses.

In order to overcome the disadvantages of the prior art, the present disclosure provides an electric energy transmission joint, which uses an electric energy transmission copper part with a through hole for connection with an electric energy transmission aluminum part, so as to further reduce the weight of the electric energy transmission joint, and obviously reduce the manufacturing cost thereof.

Any references to inventions or embodiments not falling within the scope of the independent claims are to be interpreted as examples useful for understanding the invention.

As compared with the prior art, the present disclosure can have in particular embodiments of the invention the following advantages.

The above description is only a summary of the technical solutions of the present disclosure. In order to understand the technical means of the present disclosure more clearly to carry out the technical means according to the specification, and in order to make the above and other objectives, features and advantages of the present disclosure more obvious and understandable, the following exemplary embodiments will be described in detail with reference to the drawings.

<FIG> is a schematic structural diagram of an electric energy transmission joint according to the present disclosure.

The reference numerals in <FIG> are as follows:.

In order to further explain the technical features adopted by the present disclosure to achieve the intended invention objective and effects thereof, the specific implementations, structures, characteristics and effects of the present disclosure will be described in detail below with reference to the drawings and the exemplary embodiments.

As illustrated in <FIG>, the present disclosure discloses an electric energy transmission joint, including an electric energy transmission copper part, an electric energy transmission aluminum part <NUM>, and an aluminum wire <NUM>. The electric energy transmission copper part includes a fixer <NUM> for connection with an electric consumption device, and a connector <NUM> for connection with the electric energy transmission aluminum part <NUM>. A second through hole is provided inside the connector <NUM>, and a first through hole is provided inside the electric energy transmission aluminum part <NUM>. A front end of the aluminum wire <NUM> stripped of an insulation layer <NUM> is inserted into a cavity formed by the connection of the first through hole and the second through hole, and the electric energy transmission aluminum part <NUM> is connected to the aluminum wire <NUM> by crimping.

Since the connector <NUM> is provided with the second through hole, the weight of the electric energy transmission copper part is greatly reduced, and the production cost is reduced. Moreover, when preparing the electric energy transmission joint, firstly the connector <NUM> of the electric energy transmission copper part is connected to the electric energy transmission aluminum part <NUM>, then the front end of the aluminum wire <NUM> is stripped of the insulation layer <NUM> and inserted into the cavity formed by the connection of the first through hole and the second through hole, and finally the electric energy transmission aluminum part <NUM> and the aluminum wire <NUM> are crimped. The preparation method is simple, the automation of the assembly of the electric energy transmission joint can be realized, and the assembly efficiency is greatly improved.

In addition, since the volumes of the electric energy transmission copper part and the electric energy transmission aluminum part <NUM> are relatively small, it is possible to realize automatic loading and unloading of the electric energy transmission copper part and the electric energy transmission aluminum part <NUM>. Furthermore, it is also possible to directly cut off the flash generated during welding of the connector <NUM> and the electric energy transmission aluminum part <NUM> after welding, so that the electric energy transmission joint does not carry the aluminum wire <NUM> when the flash is cut off, which not only saves the processing time and improves the assembly efficiency, but also avoids the influence of the aluminum wire <NUM> on the electric energy transmission joint when the flash is cut off, thus improving the yield of the electric energy transmission joint.

It should be noted that in the present disclosure, the electric energy transmission copper part is formed by stamping a tubular copper tube. The stamped electric energy transmission copper part includes a fixer <NUM> and a connector <NUM>, and a second through hole is provided inside the connector <NUM>. In addition, a position where the front end of the aluminum wire <NUM> is inserted into the cavity may be in the first through hole or the second through hole.

Since copper is an active metal, the electric energy transmission copper part is susceptible to oxidation corrosion during use, thus increasing the resistance of the electric energy transmission copper part, and even causing a burning accident in severe cases. Therefore, in order to prolong the service life of the electric energy transmission copper part, the surfaces of the fixer <NUM> and the connector <NUM> are provided with plating layers, which are made of at least one selected from the group of nickel, cadmium, zirconium, chromium, cobalt, manganese, aluminum, tin, titanium, zinc, copper, silver, and gold, thus reducing the oxidation corrosion speed of the electric energy transmission copper part and prolonging the service life thereof.

As an exemplary solution, an inner diameter of the electric energy transmission aluminum part <NUM> is one to three times a diameter of a circumscribed circle of the insulation layer <NUM> of the aluminum wire. On the one hand, it can facilitate the front end of the aluminum wire <NUM> stripped of the insulation layer <NUM> to be inserted into the cavity formed by the connection of the first through hole and the second through hole. On the other hand, since the electric energy transmission aluminum part <NUM> is connected to the aluminum wire <NUM> by crimping, if the inner diameter of the electric energy transmission aluminum part <NUM> is more than three times the diameter of the circumscribed circle of the insulation layer <NUM> of the aluminum wire, the electric energy transmission aluminum part <NUM> should be compressed by a large proportion to be crimped to the aluminum wire <NUM>, which easily leads to the breakage of the electric energy transmission aluminum part <NUM>.

To verify the influence of a ratio of the inner diameter of electric energy transmission aluminum part to the diameter of the circumscribed circle of the insulation layer <NUM> of the aluminum wire on a pullout force and a voltage drop of the electric energy transmission joint, the inventor investigates the pullout forces and the voltage drops of the electric energy transmission joints made under different ratios of the inner diameter of the electric energy transmission aluminum part <NUM> to the diameter of the circumscribed circle of the insulation layer <NUM> of the aluminum wire were. The experimental results are shown in Table <NUM>.

As can be seen from Table <NUM>, when the ratio of the inner diameter of the electric energy transmission aluminum part <NUM> to the diameter of the circumscribed circle of the insulation layer <NUM> of the aluminum wire is less than <NUM>, the aluminum wire <NUM> cannot be inserted into the electric energy transmission aluminum part. When the ratio of the inner diameter of the electric energy transmission aluminum part <NUM> to the diameter of the circumscribed circle of the insulation layer <NUM> of the aluminum wire is greater than <NUM>, the pullout force of the electric energy transmission joint is lower than a standard value of <NUM>,<NUM> N, and the voltage drop of the electric energy transmission joint is higher than a standard value of <NUM> mV, which do not meet the requirements of mechanical and electrical properties of the electric energy transmission joint. In addition, when the ratio of the inner diameter of the electric energy transmission aluminum part <NUM> to the diameter of the circumscribed circle of the insulation layer <NUM> of the aluminum wire is large, the electric energy transmission aluminum part <NUM> should be compressed by a large proportion to be crimped to the aluminum wire <NUM>, which easily leads to the breakage of the electric energy transmission aluminum part <NUM>.

Sealant or solder <NUM> is filled between the cavity and an aluminum conductive core <NUM> which is exposed by stripping the insulation layer <NUM> from the front end of the aluminum wire <NUM>. On the one hand, the injection of the sealant or solder <NUM> exhausts the air in the cavity, thus preventing the air and water in the cavity from corroding the connector <NUM> and the electric energy transmission aluminum part <NUM>. On the other hand, because the material of the electric energy transmission aluminum part <NUM> is soft, the electric energy transmission aluminum part <NUM> being crimped to the aluminum wire <NUM> may reduce the mechanical property of the electric energy transmission joint; by providing the sealant or solder <NUM> to connect the connector <NUM>, the electric energy transmission aluminum part <NUM> and the aluminum conductive core <NUM> together, the connection strength between the electric energy transmission joint and the aluminum wire <NUM> is increased. In addition, the sealant or solder <NUM> increases the contact area between the aluminum conductive core <NUM> and the contact area between the connector <NUM> and the electric energy transmission aluminum part <NUM>, thus further improving the electrical property of the electric energy transmission joint.

It should be noted that in the present disclosure, the material of the solder contains at least one selected from the group of nickel and nickel alloy, cadmium and cadmium alloy, zirconium and zirconium alloy, chromium and chromium alloy, cobalt and cobalt alloy, manganese and manganese alloy, tin and tin alloy, titanium and titanium alloy, zinc and zinc alloy, copper and copper alloy, silver and silver alloy, and gold and gold alloy. Exemplarily, the material of the solder is metal or alloy with a melting point not higher than aluminum.

Moreover, since the sealant <NUM> has good ductility and sealing property, when being filled between the aluminum conductive core <NUM> and the cavity, the sealant <NUM> can seal and protect a region between the aluminum conductive core <NUM> and the cavity, so that the aluminum conductive core <NUM> and the cavity are well protected from being eroded by moisture and salt mist, thus prolonging the service life of the electric energy transmission joint.

The sealant <NUM> includes, but is not limited to, a conductive adhesive, a rubber-based sealant, a resin-based sealant, or an oil-based sealant.

In order to understand the influence of the sealant or solder on the properties of the electric energy transmission joint, the inventor carries out a Second Experiment, and the experimental results are shown in Table <NUM>.

As can be seen from the above table, when sealant or solder is filled between the aluminum conductive core <NUM> and the cavity, the pullout force of the electric energy transmission joint is obviously larger than that when no sealant or solder is filled between the aluminum conductive core <NUM> and the cavity, and the voltage drop thereof is smaller than that when no sealant or solder is filled between the aluminum conductive core <NUM> and the cavity. Therefore, the electric energy transmission joint has better electrical and chemical properties when the sealant or solder is filled between the aluminum conductive core <NUM> and the cavity.

As a further exemplary solution, a transitional connection device <NUM> is further provided between the aluminum conductive core <NUM> and the inner wall of the cavity, and at least part of the surface of the transitional connection device <NUM> is provided with protrusions for piercing oxide layers on a surface of the aluminum conductive core <NUM> and a surface of the inner wall of the cavity.

It should be noted that in the present disclosure, the material of the transitional connection device <NUM> contains at least one selected from the group of nickel and nickel alloy, cadmium and cadmium alloy, zirconium and zirconium alloy, chromium and chromium alloy, cobalt and cobalt alloy, manganese and manganese alloy, tin and tin alloy, titanium and titanium alloy, zinc and zinc alloy, copper and copper alloy, silver and silver alloy, and gold and gold alloy.

On the one hand, the protrusions increase the contact area between the aluminum conductive core <NUM>, the transitional connection device <NUM> and the electric energy transmission aluminum part <NUM>, while increasing the friction between the aluminum wire <NUM> and the transitional connection device <NUM> and between the transitional connection device <NUM> and the electric energy transmission aluminum part <NUM>, so that the aluminum wire <NUM> can be prevented from being separated from the electric energy transmission aluminum part <NUM>, thereby improving the mechanical property of the electric energy transmission joint.

On the other hand, the protrusions further increase the number of conductive bumps of the aluminum conductive core <NUM>, which enhances the electric conduction effect while damaging the oxide layers on the surface of the aluminum conductive core <NUM> and the surface of the inner wall of the cavity, so that the aluminum conductive core <NUM> directly contacts the transitional connection device <NUM>, and the transitional connection device <NUM> directly contacts the conductive part of the cavity, thus improving the electrical property of the electric energy transmission joint.

Specifically, the protrusions are a corrugated structure, a serrated structure, a pit structure, a spike structure, an inverted toothed structure, or a mesh structure, which not only increases the surface area of the transitional connection device <NUM>, but also enhances the connection between the transitional connection device <NUM> and the electric energy transmission aluminum part <NUM>, and can also break more oxide layers, so as to improve the electric conductivity.

In order to understand the influence of the protrusions on the properties of the electric energy transmission j oint, the inventor demonstrates by taking the examples in which the protrusions are a corrugated structure, a serrated structure, a pit structure, a spike structure, an inverted toothed structure, and a mesh structure. The results are shown in Table <NUM>.

As can be seen from the above table, when at least part of the surface of the transitional connection device <NUM> is provided with the protrusions in the above shapes or structures, the pullout force of the electric energy transmission joint is larger than that of the electric energy transmission joint without protrusions provided on the surface of the transitional connection device <NUM>, and the voltage drop thereof is smaller than that of the electric energy transmission joint without protrusions provided on the surface of the transitional connection device <NUM>. Therefore, when at least part of the surface of the transitional connection device <NUM> is provided with the protrusions, the electric energy transmission joint has better mechanical and electrical properties.

In other embodiments, the transitional connection device <NUM> is a hollow cylinder at least partially sheathing the aluminum conductive core <NUM>. When the transitional connection device <NUM> is a hollow cylinder, on the one hand, an automatic production with high production efficiency can be realized; on the other hand, the loose aluminum conductive core <NUM> can be pre-contracted by the transitional connection device <NUM>, so that the aluminum conductive core <NUM> can be inserted into the cavity more conveniently, thus avoiding a situation that part of core wires of the aluminum conductive core <NUM> generated during the production cannot be inserted into the cavity, and facilitating the production and the processing of the electric energy transmission joint.

In order to improve the effect of crimping the electric energy transmission aluminum part <NUM> and the aluminum wire <NUM>, a crimping length of the aluminum wire <NUM> accounts for at least <NUM>% of a length of the electric energy transmission aluminum part <NUM>. This is because if the crimping length of the aluminum wire <NUM> is too short, the fixing force of the electric energy transmission aluminum part <NUM> to the aluminum wire <NUM> is insufficient, and the aluminum wire <NUM> is easily separated from the electric energy transmission aluminum part <NUM>. Moreover, if the crimping length is too short, the contact area between the aluminum wire <NUM> and the electric energy transmission aluminum part <NUM> at the crimping position decreases, the current conduction region is relatively small, and a resistance between the aluminum wire <NUM> and the electric energy transmission aluminum part <NUM> increases, resulting in heat at the crimping position, which will degrade the electrical property of the electric energy transmission joint, and even cause a burning accident in severe cases.

In order to understand the influence of a ratio of the crimping length of the aluminum wire <NUM> to the length of the electric energy transmission aluminum part <NUM> on the properties of the electric energy transmission joint, the inventor investigates the ratio of the crimping length of different aluminum wires <NUM> to the length of the electric energy transmission aluminum part <NUM>, and then tests the mechanical and electrical properties of the electric energy transmission joint. The detailed test results are shown in Table <NUM>.

As can be seen from the above table, when the ratio of the crimping length of the aluminum wire <NUM> to the length of the electric energy transmission aluminum part <NUM> is less than <NUM>%, the pullout force of the electric energy transmission joint is less than <NUM>,<NUM> N, which does not meet the requirements of the mechanical property of the aluminum j oint, and the voltage drop is greater than <NUM> mV, which does not meet the requirement of the electrical property, thus seriously affecting the service life of the electric energy transmission joint. Therefore, exemplarily, the crimping length of the aluminum wire <NUM> accounts for at least <NUM>% of the length of the electric energy transmission aluminum part <NUM>.

As a further exemplary solution, the connector <NUM> and the electric energy transmission aluminum part <NUM> are connected by welding.

It should be noted that the welding may include friction welding, resistance welding, ultrasonic welding, electromagnetic welding, pressure diffusion welding, or arc welding, which are described below.

As a further exemplary solution, the connector <NUM> and the electric energy transmission aluminum part <NUM> are connected by friction welding, because the friction welding is simpler for butt parts of large cross-sectional areas with through holes.

As a further exemplary solution, a copper-aluminum transition layer <NUM> is formed between the connector <NUM> and the electric energy transmission aluminum part <NUM> by mutual penetration or mutual combination of copper and aluminum atoms, and the copper-aluminum transition layer <NUM> at least contains a mixture of copper and aluminum, or a mixture of copper, aluminum and copper-aluminum solid solution. Furthermore, the copper-aluminum transition layer <NUM> can slow down the electrochemical corrosion between copper and aluminum, and prolong the service life of the electric energy transmission joint.

The present disclosure further discloses a preparation method for an electric energy transmission joint, including:.

Further, between the welding step and the aluminum wire <NUM> crimping step, the method further includes a step of filling sealant or solder <NUM> between the aluminum conductive core <NUM> and the cavity.

Specifically, filling the cavity with the sealant or solder <NUM> includes: pouring, through holes on a surface of the electric energy transmission copper part, molten sealant or solder <NUM> into the electric energy transmission copper part and the electric energy transmission aluminum part <NUM> having been welded.

Further exemplarily, between the step of filling the cavity with the sealant or solder <NUM> and the aluminum wire <NUM> crimping step, the method further includes a step of sheathing the aluminum conductive core <NUM> by a transitional connection device <NUM>.

It should be noted that in the description of the present disclosure, the terms such as 'first' and 'second' are only used to describe the names of various components, and cannot be understood as indicating or implying the relative importance of each component.

Claim 1:
An electric energy transmission joint, comprising an electric energy transmission copper part, an electric energy transmission aluminum part (<NUM>), and an aluminum wire (<NUM>), with the electric energy transmission copper part comprising a fixer (<NUM>) for connection with an electric consumption device and a connector (<NUM>) for connection with the electric energy transmission aluminum part (<NUM>), wherein a first through hole is provided inside the electric energy transmission aluminum part (<NUM>), a second through hole is provided inside the connector (<NUM>), an aluminum conductive core (<NUM>) exposed by stripping an insulation layer (<NUM>) from a front end of the aluminum wire (<NUM>) is inserted into a cavity formed by the connection of the first through hole and the second through hole, and the electric energy transmission aluminum part (<NUM>) is connected to the aluminum wire (<NUM>) by crimping;
characterized in that
a transitional connection device (<NUM>) is further provided between the aluminum conductive core (<NUM>) and an inner wall of the cavity, and an inner surface and an outer surface of the transitional connection device (<NUM>) is provided with protrusions for piercing oxide layers on a surface of the aluminum conductive core (<NUM>) and a surface of the inner wall of the cavity.