Bolt, connecting structure of magnesium alloy component and electric drive assembly

Abstract

The utility model discloses a bolt, a connecting structure of a magnesium alloy component and an electric drive assembly, and relates to the technical field of automobiles. Or, the bolt comprises a bolt body and a coating layer arranged on the surface of the bolt body, and the coating layer comprises a flame-retardant magnesium alloy coating. When the bolt provided by the utility model is used for connecting a magnesium alloy component and other components made of dissimilar materials, the overall potential difference can be greatly reduced, so that the galvanic corrosion degree is reduced. Therefore, the problem that galvanic corrosion is prone to being generated when the speed reducer shell made of magnesium alloy and the all-in-one machine shell made of aluminum alloy are connected through the steel bolts can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of automobiles, and in particular to a connection structure of a bolt and a magnesium alloy component, and an electric drive assembly. Background Art

[0002] The electric drive assembly refers to the collection of electrified components used to drive the wheels of an electric vehicle (EV) or hybrid electric vehicle (HEV). It generally consists of a motor, a reducer, a controller, and other components. The electric drive assembly housing is the outer shell that houses these components. It generally consists of a reducer housing and an integrated unit housing. The reducer housing is made of magnesium alloy, while the integrated unit housing is made of aluminum alloy or other materials.

[0003] The reducer housing is generally connected to the integrated machine housing through steel bolts. In a salt spray environment, galvanic corrosion is likely to occur between the reducer housing, bolts and integrated machine housing, resulting in connection failure. Utility Model Content

[0004] The main purpose of the utility model is to provide a connection structure of bolts, magnesium alloy components and an electric drive assembly, aiming to improve the problem of galvanic corrosion that is easily generated when the reducer housing made of magnesium alloy and the integrated machine housing made of aluminum alloy are connected by steel bolts.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a bolt, which is a flame retardant magnesium alloy bolt; or, the bolt includes a bolt body and a coating layer provided on the surface of the bolt body, and the coating layer includes a flame retardant magnesium alloy coating.

[0006] In one embodiment, the thickness of the flame retardant magnesium alloy coating is 50 μm-200 μm.

[0007] In one embodiment, the coating layer further includes a polytetrafluoroethylene coating, and the polytetrafluoroethylene coating is disposed on the outside of the flame-retardant magnesium alloy coating.

[0008] In one embodiment, the thickness of the polytetrafluoroethylene coating is 50 μm-100 μm.

[0009] In one embodiment, the bolt body is selected from one of a steel bolt body, a copper bolt body, a titanium bolt body, and an aluminum bolt body.

[0010] In one embodiment, the flame retardant magnesium alloy coating is formed by spraying, physical vapor deposition, or hot-dip coating.

[0011] In a second aspect, the present invention provides a connection structure of a magnesium alloy component, comprising at least one of the above-mentioned bolts.

[0012] In a third aspect, the present invention provides an electric drive assembly, including a reducer housing, an integrated machine housing, and a connection structure of the above-mentioned magnesium alloy components.

[0013] In one embodiment, a bonding layer is further provided at the joint surface between the reducer housing and the integrated machine housing.

[0014] In one embodiment, the reducer housing and the integrated machine housing are provided with sunken threaded holes, and the bolts are located in the sunken threaded holes.

[0015] The bolts of this utility model are made of a flame-retardant magnesium alloy, or have a flame-retardant magnesium alloy coating applied to the surface of the bolt body. When these bolts are used to connect magnesium alloy components with other components made of dissimilar materials, the overall potential difference can be significantly reduced, thereby alleviating the degree of galvanic corrosion. Therefore, this utility model can alleviate the problem of galvanic corrosion that is easily generated when connecting a magnesium alloy reducer housing and an aluminum alloy integrated machine housing via steel bolts. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0017] Figure 1 This is a cross-sectional schematic diagram of a bolt in one embodiment of the present utility model;

[0018] Figure 2 This is a cross-sectional schematic diagram of a bolt in another embodiment of the present invention;

[0019] Figure 3 This is a cross-sectional schematic diagram of a bolt in another embodiment of the present invention;

[0020] Figure 4 This is a schematic structural diagram of an electric drive assembly in one embodiment of the present utility model;

[0021] Figure 5 This is a schematic diagram of the connection between the reducer housing and the integrated machine housing in one embodiment of the present utility model.

[0022] Explanation of Figure Numbers

[0023] 100. Bolt; 11. Bolt body; 12. Coating; 121. Flame-retardant magnesium alloy coating; 122. Polytetrafluoroethylene coating;

[0024] 200, reducer housing;

[0025] 300, integrated machine housing;

[0026] 400. Gluing layer. DETAILED DESCRIPTION

[0027] It should be noted that if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. "At least one" appearing in the embodiments of the present invention refers to one or more, and "more" refers to two or more.

[0028] In the description of the embodiments of the present invention, if the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0029] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the technical terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, it can mean fixed connection, detachable connection, or integration; it can mean mechanical connection or electrical connection; it can mean direct connection or indirect connection through an intermediate medium; it can mean internal communication between two components or interaction between two components. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0030] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0031] The electric drive assembly housing is generally composed of a reducer housing and an integrated machine housing. The reducer housing is made of magnesium alloy, while the integrated machine housing is made of other materials such as aluminum alloy. The reducer housing and the integrated machine housing are fastened with steel bolts.

[0032] Because magnesium alloy has the most negative potential, aluminum alloy has the second most negative potential, and steel has the most positive potential, there is a potential difference between the three. Therefore, when the magnesium alloy reducer housing and the aluminum alloy integrated machine housing are connected by steel bolts, a galvanic couple is formed. When the electric drive assembly is exposed to salt spray, the magnesium alloy reducer housing, acting as the anode, corrodes rapidly. Since the aluminum alloy integrated machine housing is at an intermediate potential, its corrosion rate is slower than that of the magnesium alloy reducer housing, but corrosion still occurs.

[0033] To this end, magnesium alloy bolts made of the same material as the reducer housing can be used for connection. In this way, the bolts and the reducer housing are made of the same material, which can reduce the overall potential difference and thus reduce the degree of galvanic corrosion.

[0034] Based on the above considerations, the present invention provides a bolt 100, referring to Figure 1 As shown, the bolt 100 is a flame retardant magnesium alloy bolt, or, referring to Figure 2 As shown, the bolt 100 includes a bolt body 11 and a coating layer 12 disposed on a surface of the bolt body 11 , wherein the coating layer 12 includes a flame-retardant magnesium alloy coating 121 .

[0035] Flame retardant magnesium alloy refers to a magnesium alloy with flame retardant properties, which is generally formed by adding specific alloying elements to the magnesium alloy, such as calcium, beryllium, rare earth elements, etc. The present invention does not limit the specific components of the flame retardant magnesium alloy. For example, the flame retardant magnesium alloy can be KUMADAI non-combustible magnesium alloy, whose components are Mg 88 Al8Ca4 or Mg 85 Al 10 Ca5.

[0036] The flame retardant magnesium alloy bolt refers to a bolt made of flame retardant magnesium alloy. The coating layer 12 refers to a coating formed on the entire surface of the bolt body 11 .

[0037] In the technical solution of the present invention, bolts are made of flame-retardant magnesium alloy or coated with a flame-retardant magnesium alloy. This, on the one hand, can reduce the overall potential difference between the galvanic pairs formed by the bolts, magnesium alloy components, and other dissimilar components, thereby alleviating the degree of galvanic corrosion. On the other hand, the surface of the flame-retardant magnesium alloy has a dense oxide film that can prevent oxygen from entering the interior, thereby reducing the occurrence of corrosion reactions promoted by dissolved oxygen and other impurities. Therefore, the present invention can alleviate the problem of galvanic corrosion that is easily generated when the reducer housing made of magnesium alloy and the integrated machine housing made of aluminum alloy are connected by steel bolts.

[0038] According to some embodiments of the present invention, the thickness of the flame retardant magnesium alloy coating 121 is 50 μm-200 μm. The flame retardant magnesium alloy coating 121 with this thickness range can effectively improve the corrosion situation.

[0039] According to some embodiments of the present invention, Figure 3 As shown, the coating layer 12 further includes a polytetrafluoroethylene coating 122 , which is disposed on the outer side of the flame-retardant magnesium alloy coating 121 .

[0040] Polytetrafluoroethylene (PTFE) is a good insulating material. Providing a PTFE coating 122 on the outermost layer of the bolt body 11 forms an insulating layer between the magnesium alloy component, the aluminum alloy component, and the bolt body 11, preventing or reducing the flow of electrons between the different metals, thereby reducing the driving force of galvanic corrosion. Furthermore, the PTFE coating 122 blocks contact between corrosive media (such as salt spray) and the bolt body 11, reducing the bolt body's 11 involvement in galvanic corrosion. It also reduces contact between corrosive media and the magnesium and aluminum alloy components to a certain extent, thereby slowing the corrosion rate of the entire system.

[0041] According to some embodiments of the present invention, the thickness of the polytetrafluoroethylene coating 122 is 50 μm-100 μm.

[0042] According to some embodiments of the present invention, the bolt body 11 is selected from one of a steel bolt body, a copper bolt body, a titanium bolt body, and an aluminum bolt body. The material of the steel bolt body can be selected from carbon steel, alloy steel, or stainless steel; the material of the copper bolt body can be selected from brass or bronze; the material of the titanium bolt body can be selected from a titanium alloy; and the material of the aluminum bolt body can be selected from an aluminum alloy.

[0043] According to some embodiments of the present invention, the flame retardant magnesium alloy coating 121 is formed by spraying, physical vapor deposition or hot dip coating.

[0044] Spraying methods can be flame spraying or plasma spraying. Flame spraying uses a flame generated by the combustion of a mixture of combustible and combustion-supporting gases as a heat source to heat the flame-retardant magnesium alloy powder to a molten or semi-molten state. The powder is then sprayed onto the surface of the bolt body 11 to form a coating. Plasma spraying uses a plasma spray gun to generate a high-temperature plasma flame, which heats the flame-retardant magnesium alloy powder and sprays it onto the surface of the bolt body 11.

[0045] Physical vapor deposition methods can be vacuum evaporation or sputtering. Vacuum evaporation involves heating and evaporating a flame-retardant magnesium alloy into a gaseous state under a high vacuum environment. This gas is then deposited onto the surface of the bolt body 11 to form a coating. Sputtering, on the other hand, involves bombarding a flame-retardant magnesium alloy target with high-energy particles, sputtering atoms from the target surface and depositing them onto the surface of the bolt body 11.

[0046] The hot-dip coating method is to immerse the bolt body into a molten flame-retardant magnesium alloy liquid so that the flame-retardant magnesium alloy forms a coating on the bolt surface.

[0047] In a second aspect, the present invention provides a connection structure for magnesium alloy components, comprising at least one bolt 100 as described above. The specific configuration of the bolt 100 is described with reference to the aforementioned embodiments. Since the connection structure of the present invention utilizes all of the technical solutions of all of the aforementioned embodiments, it at least possesses all of the beneficial effects brought about by the technical solutions of the aforementioned embodiments, and therefore, no further elaboration is required here.

[0048] In the third aspect, the utility model provides an electric drive assembly, referring to Figure 4 As shown, it includes a reducer housing 200, an integrated machine housing 300 and a connection structure of the above-mentioned magnesium alloy components.

[0049] According to some embodiments of the present invention, Figure 5 As shown, a bonding layer 400 is further provided at the joint surface between the reducer housing 200 and the integrated machine housing 300 .

[0050] The adhesive layer 400 is formed by applying an adhesive to the interface between the reducer housing 200 and the integrated machine housing 300. The adhesive layer 400 provides a physical barrier between the reducer housing 200 and the integrated machine housing 300, thereby preventing or reducing the flow of corrosive media between the two components and thus reducing the likelihood of galvanic corrosion. Furthermore, the adhesive's insulating properties can, to a certain extent, prevent the flow of electrons between the magnesium alloy and the aluminum alloy, thereby mitigating corrosion.

[0051] According to some embodiments of the present invention, the reducer housing 200 and the integrated machine housing 300 are provided with countersunk threaded holes, and the bolts 100 are located in the countersunk threaded holes. The provision of the countersunk threaded holes can reduce stress values, thereby reducing the risk of stress corrosion.

[0052] According to some embodiments of the present invention, Figure 4 and 5 As shown, the present invention provides an electric drive assembly comprising a reducer housing 200 and an integrated machine housing 300, connected by a plurality of flame-retardant magnesium alloy bolts 100. The reducer housing 200 and the integrated machine housing 300 are provided with countersunk threaded holes, and the bolts 100 are positioned within the countersunk threaded holes. An adhesive layer 400 is also provided at the interface between the reducer housing 200 and the integrated machine housing 300.

[0053] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A bolt, characterized in that: The bolt is a flame retardant magnesium alloy bolt; or, The bolt includes a bolt body and a coating layer arranged on the surface of the bolt body, and the coating layer includes a flame-retardant magnesium alloy coating.

2. The bolt according to claim 1, wherein The thickness of the flame retardant magnesium alloy coating is 50 μm-200 μm.

3. The bolt according to claim 1 or 2, wherein: The coating layer further includes a polytetrafluoroethylene coating, and the polytetrafluoroethylene coating is arranged on the outer side of the flame retardant magnesium alloy coating.

4. The bolt according to claim 3, wherein The thickness of the polytetrafluoroethylene coating is 50 μm-100 μm.

5. The bolt according to claim 1, wherein The bolt body is selected from one of a steel bolt body, a copper bolt body, a titanium bolt body, and an aluminum bolt body.

6. The bolt according to claim 1, wherein The flame retardant magnesium alloy coating is formed by spraying, physical vapor deposition or hot dip coating.

7. A connection structure of magnesium alloy components, characterized in that: Comprising at least one bolt according to any one of claims 1 to 6.

8. An electric drive assembly, characterized in that: The invention comprises a reducer housing, an integrated machine housing and a connection structure of the magnesium alloy component according to claim 7.

9. The electric drive assembly according to claim 8, characterized in that: A bonding layer is also provided at the joint surface between the reducer housing and the integrated machine housing.

10. The electric drive assembly according to claim 8, characterized in that: The reducer housing and the integrated machine housing are provided with sunken threaded holes, and the bolts are located in the sunken threaded holes.

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