Magnesium alloy housing for electric vehicle drive unit

Abstract

A magnesium (Mg) alloy housing for a drive unit of an electric vehicle (EV) having a drive shaft connected to an electric motor is provided. The Mg alloy housing includes a main body including a Mg alloy. The main body is arranged to house the drive unit of the EV. The housing further includes a cylindrical hub disposed on the main body. The hub has a bore formed therethrough and is arranged to couple the drive shaft of the electric motor to the drive unit. The hub includes a Mg portion having an inner surface. The hub further includes an aluminum (Al) insert having an outer surface. The Al insert is arranged to be disposed on the Mg portion such that the inner surface is aligned with the outer surface, thereby defining a weld interface. The Al insert includes iron (Fe) and manganese (Mn) and has a Fe / Mn weight ratio between 1:20 and 1:30.

Description

Technical Field

[0001] This disclosure relates to a magnesium alloy housing for a drive unit of an electric vehicle, and more specifically to a magnesium alloy housing with an aluminum alloy insert for enhanced fatigue resistance. Background Technology

[0002] Magnesium alloys have been used in electric vehicle drive units to reduce weight. While sufficient, magnesium drive unit housings sometimes experience fatigue cracking due to their material properties. Summary of the Invention

[0003] Therefore, while current electric vehicle drive unit housings have achieved their intended purpose, there is a need for new and improved housings and methods for manufacturing such housings.

[0004] According to one aspect of this disclosure, a magnesium (Mg) alloy housing is provided for a drive unit of an electric vehicle (EV) having a drive shaft connected to an electric motor. The Mg alloy housing includes a body comprising a Mg alloy. The body is arranged to house the drive unit of the EV.

[0005] In this respect, the housing also includes a cylindrical hub disposed on the body. The hub has a hole formed therethrough and is arranged to connect the drive shaft of an electric motor to a drive unit. The hub includes a first Mg portion having a first inner surface and a second Mg portion having a second inner surface. The hub includes an aluminum (Al) insert having a first outer surface and a second outer surface. The Al insert is cast between the first Mg portion and the second Mg portion such that the first inner surface is aligned with the first outer surface to define a first interface and the second inner surface is aligned with the second outer surface to define a second interface.

[0006] According to this aspect, the Al insert comprises iron (Fe) and manganese (Mn) and has an Fe / Mn weight ratio between 1:20 and 1:30. The Al insert has a flange formed adjacent to the first outer surface. The flange is arranged to be loaded with compressive stress and to transfer the compressive stress to the first interface to counteract tensile stress during use, thereby minimizing fatigue and cracking thereon.

[0007] In one embodiment of this aspect, the Al insert has the following components: 0.1 to 13.0 wt% silicon (Si), 0.05 to 4.0 wt% copper (Cu), 0.01 to 3.0 wt% magnesium (Mg), 0.01 to 0.2 wt% iron (Fe), 0.1 to 1.0 wt% manganese (Mn), 0 to 0.3 wt% nickel (Ni), 0 to 6.0 wt% zinc (Zn), and 0 to 0.5 wt% chromium (Cr).

[0008] In another embodiment, the Al insert is a forged Al alloy having a composition comprising 0.1 to 1.5 wt% Si, 0.05 to 2.0 wt% Cu, 0.01 to 3.0 wt% Mg, 0.01 to 0.2 wt% Fe, 0.5 to 1.0 wt% Mn, 0 to 0.3 wt% Ni, 0.1 to 6.0 wt% Zn, and 0 to 0.5 wt% Cr.

[0009] In yet another embodiment of this aspect, the Al insert is a cast aluminum alloy having a composition comprising 4.0 to 13.0 wt% Si, 0 to 4.0 wt% Cu, 0.01 to 1.5 wt% Mg, 0.01 to 0.2 wt% Fe, 0.1 to 1 wt% Mn, 0 to 0.3 wt% Ni, 0 to 3 wt% Zn and 0 to 0.5 wt% Cr.

[0010] In one embodiment, the Fe / Mn weight ratio of the Al insert is 1:20. In another embodiment, the Fe / Mn weight ratio of the Al insert is 1:25. In yet another embodiment, the Fe / Mn weight ratio of the Al insert is 1:30.

[0011] In another embodiment, the Al insert has notches formed on its first and second outer surfaces to enhance mechanical bonding. In yet another embodiment, the compressive stress is between 150 mPa and 250 mPa. In still another embodiment, each of the first and second outer surfaces includes a Zn coating thereon to enhance metallurgical bonding at the first and second interfaces.

[0012] According to another aspect of this disclosure, a magnesium (Mg) alloy housing for a drive unit of an electric vehicle (EV) is provided, the EV having a drive shaft connected to an electric motor. The Mg alloy housing includes a body comprising a Mg alloy, the body being arranged to house the drive unit of the EV. The Mg alloy housing also includes a cylindrical hub disposed on the body. The hub has a hole formed therethrough and is arranged to connect the drive shaft of the electric motor to the drive unit. The hub includes a first Mg portion having a first inner surface and a second Mg portion having a second inner surface.

[0013] The hub includes an aluminum (Al) insert having a first outer surface and a second outer surface. The Al insert is cast between a first Mg portion and a second Mg portion such that a first inner surface is aligned with the first outer surface to define a first interface and a second inner surface is aligned with the second outer surface to define a second interface. The Al insert comprises iron (Fe) and manganese (Mn) and has an Fe / Mn weight ratio between 1:20 and 1:30. The Al insert has a flange formed adjacent to the first outer surface. The flange is arranged to be loaded with compressive stress and to transfer the compressive stress to the first interface to counteract tensile stress during use, thereby minimizing fatigue and cracking thereon.

[0014] In this respect, the Al insert comprises 0.1 to 13.0 wt% silicon (Si), 0.05 to 4.0 wt% copper (Cu), 0.01 to 3.0 wt% magnesium (Mg), 0.01 to 0.2 wt% iron (Fe), 0.1 to 1.0 wt% manganese (Mn), 0 to 0.3 wt% nickel (Ni), 0 to 6.0 wt% zinc (Zn) and 0 to 0.5 wt% chromium (Cr).

[0015] In one embodiment, the Al insert is a forged Al alloy having a composition comprising 0.1 to 1.5 wt% Si, 0.05 to 2.0 wt% Cu, 0.01 to 3.0 wt% Mg, 0.01 to 0.2 wt% Fe, 0.5 to 1.0 wt% Mn, 0 to 0.3 wt% Ni, 0.1 to 6.0 wt% Zn, and 0 to 0.5 wt% Cr.

[0016] In another embodiment, the Al insert is a cast aluminum alloy having a composition comprising 4.0 to 13.0 wt% Si, 0 to 4.0 wt% Cu, 0.01 to 1.5 wt% Mg, 0.01 to 0.2 wt% Fe, 0.1 to 1 wt% Mn, 0 to 0.3 wt% Ni, 0 to 3 wt% Zn, and 0 to 0.5 wt% Cr.

[0017] In yet another embodiment, the Fe / Mn weight ratio of the Al insert is 1:20. In still another embodiment, the Fe / Mn weight ratio of the Al insert is 1:25. In yet another embodiment, the Fe / Mn weight ratio of the Al insert is 1:30.

[0018] In another embodiment, the Al insert has notches formed on its first and second outer surfaces to enhance mechanical bonding. In yet another embodiment, the compressive stress is between 150 mPa and 250 mPa. In still another embodiment, each of the first and second outer surfaces includes a Zn coating thereon to enhance metallurgical bonding at the first and second interfaces.

[0019] According to another aspect of this disclosure, a method for manufacturing a Mg alloy housing for a drive unit of an electric vehicle (EV) having a drive shaft connected to an electric motor is disclosed. The Mg alloy housing has enhanced fatigue resistance and includes: providing a body comprising a Mg alloy, the body being arranged to house the drive unit of the EV, and providing a cylindrical hub disposed on the body.

[0020] In this respect, the hub has a hole formed therethrough and is arranged to connect the drive shaft of an electric motor to a drive unit. The hole has a center through which a rotation axis is defined. The hub includes a Mg portion having an inner surface. The hub includes an aluminum (Al) insert having an outer surface. The Al insert is arranged on the Mg portion such that the inner surface is aligned with the outer surface, thereby defining a weld interface. The Al insert comprises iron (Fe) and manganese (Mn) and has an Fe / Mn weight ratio between 1:20 and 1:30. The Al insert has a flange formed adjacent to the outer surface. The flange is arranged to be loaded with compressive stress and to transfer the compressive stress to the weld interface to counteract tensile stress during use, thereby minimizing fatigue and cracking thereon.

[0021] In this respect, the method further includes rotating the Al insert at 500 to 3000 rpm over the Mg portion about a rotation axis; and moving the Al insert to the Mg portion such that the inner surface is aligned with the outer surface to define a weld interface. The method also includes contacting the inner and outer surfaces at the weld interface with a loading pressure of 10 to 300 mPa to frictionally weld the Al insert and the Mg portion.

[0022] 1. A magnesium (Mg) alloy housing for a drive unit of an electric vehicle (EV), the electric vehicle having a drive shaft connected to an electric motor, the Mg alloy housing comprising:

[0023] The body comprises a Mg alloy body, which is arranged to house the drive unit of the EV;

[0024] A cylindrical hub disposed on the body, the hub having a hole formed through the hub and arranged to connect the drive shaft of the electric motor to the drive unit, the hub including a first Mg portion having a first inner surface and a second Mg portion having a second inner surface, the hub including an aluminum (Al) insert having a first outer surface and a second outer surface, the Al insert being cast between the first Mg portion and the second Mg portion such that the first inner surface is aligned with the first outer surface to define a first interface and the second inner surface is aligned with the second outer surface to define a second interface, the Al insert comprising iron (Fe) and manganese (Mn) and having an Fe / Mn weight ratio between 1:20 and 1:30, the Al insert having a flange formed adjacent to the first outer surface, the flange being arranged to be loaded with compressive stress and to transfer the compressive stress to the first interface to counteract tensile stress during use, thereby minimizing fatigue and cracking thereon.

[0025] 2. The housing according to claim 1, wherein the A1 insert comprises the following components:

[0026] Silicon (Si) from 0.1 to 13.0 wt%;

[0027] 0.05 to 4.0 wt% copper (Cu);

[0028] 0.01 to 3.0 wt% magnesium (Mg);

[0029] 0.01 to 0.2 wt% iron (Fe);

[0030] 0.1 to 1.0 wt% manganese (Mn);

[0031] 0 to 0.3 wt% nickel (Ni);

[0032] 0 to 6.0 wt% zinc (Zn); and

[0033] 0 to 0.5 wt% chromium (Cr).

[0034] 3. The housing according to Scheme 1, wherein the Al insert is a forged Al alloy, and the forged Al alloy has the following components:

[0035] 0.1 to 1.5 wt% Si;

[0036] 0.05 to 2.0 wt% Cu;

[0037] 0.01 to 3.0 wt% Mg;

[0038] 0.01 to 0.2 wt% Fe;

[0039] 0.5 to 1.0 wt% Mn;

[0040] 0 to 0.3 wt% Ni;

[0041] 0.1 to 6.0 wt% Zn; and

[0042] 0 to 0.5 wt% Cr.

[0043] 4. The housing according to Scheme 1, wherein the Al insert is a cast aluminum alloy, and the cast aluminum alloy has the following components:

[0044] 4.0 to 13.0 wt% Si;

[0045] 0 to 4.0 wt% Cu;

[0046] 0.01 to 1.5 wt% Mg;

[0047] 0.01 to 0.2 wt% Fe;

[0048] 0.1 to 1 wt% Mn;

[0049] 0 to 0.3 wt% Ni;

[0050] 0 to 3 wt% Zn; and

[0051] 0 to 0.5 wt% Cr.

[0052] 5. The housing according to Scheme 1, wherein the Fe / Mn weight ratio of the Al insert is 1:20.

[0053] 6. The housing according to Scheme 1, wherein the Fe / Mn weight ratio of the Al insert is 1:25.

[0054] 7. The housing according to Scheme 1, wherein the Fe / Mn weight ratio of the Al insert is 1:30.

[0055] 8. The housing according to claim 1, wherein the A1 insert has recesses formed on the first outer surface and the second outer surface of the A1 insert for enhancing mechanical connection.

[0056] 9. The housing according to Scheme 1, wherein the compressive stress is between 150 mPa and 250 mPa.

[0057] 10. The housing according to claim 1, wherein each of the first outer surface and the second outer surface includes a Zn coating on the first outer surface and the second outer surface for enhancing metallurgical bonding at the first interface and the second interface.

[0058] 11. A magnesium (Mg) alloy housing for a drive unit of an electric vehicle (EV), the electric vehicle having a drive shaft connected to an electric motor, the Mg alloy housing comprising:

[0059] The body comprises a Mg alloy body, which is arranged to house the drive unit of the EV;

[0060] A cylindrical hub disposed on the body, the hub having a hole formed through the hub and arranged to connect the drive shaft of the electric motor to the drive unit, the hub including a first Mg portion having a first inner surface and a second Mg portion having a second inner surface, the hub including an aluminum (Al) insert having a first outer surface and a second outer surface, the Al insert being cast between the first Mg portion and the second Mg portion such that the first inner surface is aligned with the first outer surface to define a first interface and the second inner surface is aligned with the second outer surface to define a second interface, the Al insert comprising iron (Fe) and manganese (Mn) and having an Fe / Mn weight ratio between 1:20 and 1:30, the Al insert having a flange formed adjacent to the first outer surface, the flange being arranged to be loaded with compressive stress and to transfer the compressive stress to the first interface to counteract tensile stress during use, thereby minimizing fatigue and cracking thereon, the Al insert comprising:

[0061] Silicon (Si) from 0.1 to 13.0 wt%;

[0062] 0.05 to 4.0 wt% copper (Cu);

[0063] 0.01 to 3.0 wt% magnesium (Mg);

[0064] 0.01 to 0.2 wt% iron (Fe);

[0065] 0.1 to 1.0 wt% manganese (Mn);

[0066] 0 to 0.3 wt% nickel (Ni);

[0067] 0 to 6.0 wt% zinc (Zn); and

[0068] 0 to 0.5 wt% chromium (Cr).

[0069] 12. The housing according to claim 11, wherein the Al insert is a forged Al alloy, the forged Al alloy having the following components:

[0070] 0.1 to 1.5 wt% Si;

[0071] 0.05 to 2.0 wt% Cu;

[0072] 0.01 to 3.0 wt% Mg;

[0073] 0.01 to 0.2 wt% Fe;

[0074] 0.5 to 1.0 wt% Mn;

[0075] 0 to 0.3 wt% Ni;

[0076] 0.1 to 6.0 wt% Zn; and

[0077] 0 to 0.5 wt% Cr.

[0078] 13. The housing according to claim 11, wherein the Al insert is a cast aluminum alloy, the cast aluminum alloy having the following components:

[0079] 4.0 to 13.0 wt% Si;

[0080] 0 to 4.0 wt% Cu;

[0081] 0.01 to 1.5 wt% Mg;

[0082] 0.01 to 0.2 wt% Fe;

[0083] 0.1 to 1 wt% Mn;

[0084] 0 to 0.3 wt% Ni;

[0085] 0 to 3 wt% Zn; and

[0086] 0 to 0.5 wt% Cr.

[0087] 14. The housing according to claim 11, wherein the Fe / Mn weight ratio of the Al insert is 1:20.

[0088] 15. The housing according to claim 11, wherein the Fe / Mn weight ratio of the Al insert is 1:25.

[0089] 16. The housing according to claim 11, wherein the Fe / Mn weight ratio of the Al insert is 1:30.

[0090] 17. The housing according to claim 11, wherein the A1 insert has recesses formed on the first outer surface and the second outer surface of the A1 insert for enhancing mechanical connection.

[0091] 18. The housing according to claim 11, wherein the compressive stress is between 150 mPa and 250 mPa.

[0092] 19. The housing according to claim 11, wherein each of the first outer surface and the second outer surface includes a Zn coating on the first outer surface and the second outer surface for enhancing metallurgical bonding at the first interface and the second interface.

[0093] 20. A method for friction welding a Mg alloy housing for a drive unit of an electric vehicle (EV), the electric vehicle having a drive shaft connected to an electric motor, the Mg alloy housing having enhanced fatigue resistance, and the method comprising:

[0094] A body comprising a Mg alloy is provided, the body being arranged to house the drive unit of the EV;

[0095] A cylindrical hub disposed on the body is provided, the hub having a hole formed through the hub and arranged to connect the drive shaft of the electric motor to the drive unit, the hole having a center through which a rotation axis is defined, the hub including a Mg portion having an inner surface, the hub including an aluminum (Al) insert having an outer surface, the Al insert being disposed on the Mg portion such that the inner surface is aligned with the outer surface to define a weld interface, the Al insert comprising iron (Fe) and manganese (Mn) and having an Fe / Mn weight ratio between 1:20 and 1:30, the Al insert having a flange formed adjacent to the outer surface, the flange being arranged to be loaded with compressive stress and to transfer the compressive stress to the weld interface to counteract tensile stress during use, thereby minimizing fatigue and cracking thereon;

[0096] The Al insert is rotated about the axis of rotation above the Mg portion at 500 to 3000 rpm;

[0097] The Al insert is moved to the Mg portion such that the inner surface is aligned with the outer surface to define the weld interface; and

[0098] The inner surface and the outer surface are brought into contact at the welding interface with a loading pressure of 10 to 300 mPa to friction weld the Al insert and the Mg portion.

[0099] Other areas of application will become apparent from the description provided herein. It should be understood that the descriptions and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0100] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0101] Figure 1A This is a schematic diagram of an electric vehicle (EV) having a magnesium (Mg) alloy housing for its drive unit, according to an embodiment of the present disclosure.

[0102] Figure 1B It is an embodiment of the present disclosure for use Figure 1A A perspective view of the magnesium (Mg) alloy housing of the drive unit of an electric vehicle (EV).

[0103] Figure 1C yes Figure 1A Side view of the cylindrical hub of the Mg alloy shell.

[0104] Figure 2A and Figure 2B yes Figure 1B A perspective view of the aluminum (Al) alloy insert of the cylindrical hub.

[0105] Figure 3A and Figure 3B This is a perspective view of the Al insert of a cylindrical hub of a Mg alloy housing according to another embodiment of the present disclosure.

[0106] Figure 4A According to another embodiment, it includes Figure 3A and Figure 3B A plan view of the Mg alloy housing of the Al insert.

[0107] Figure 4B This is a cross-sectional view of the Mg alloy shell taken along line 4B-4B.

[0108] Figure 5 This is a flowchart of a method for friction welding a Mg alloy shell with an Al alloy insert. Detailed Implementation

[0109] The following description is exemplary in nature and is not intended to limit this disclosure, application, or use.

[0110] This disclosure provides a magnesium alloy housing for a drive unit in an electric vehicle. The housing has a magnesium alloy body and a hub disposed on the body. The hub comprises an aluminum alloy portion or insert, to which the magnesium alloy is die-cast. The aluminum alloy portion has a relatively lower predetermined iron / manganese weight percentage than typical aluminum alloys. It has been unexpectedly found that the lower iron to manganese weight ratio (1:20 to 1:30) of the aluminum alloy portion helps to avoid welding problems during die-casting and reduces galvanic corrosion.

[0111] According to one embodiment of this disclosure, Figure 1A An electric vehicle (EV) 10 is depicted, having a magnesium (Mg) alloy housing 12 for its drive unit 14. As shown, the EV 10 has a drive shaft 16 connecting the drive unit 14 to an electric motor 18 of the EV 10. As can be seen, the Mg alloy housing 12 is arranged to house the drive unit 14. The drive unit 14 is connected to the motor 18 via the drive shaft 16 and is arranged to transmit power generated by the motor 18.

[0112] like Figure 1B As shown, the housing 12 includes a body 20 made of a Mg alloy. In this embodiment, as... Figure 1B As depicted, the housing 12 also includes a cylindrical hub 22 disposed on the body 20. The hub 22 has a hole 24 formed therethrough and is arranged to connect the drive shaft 16 of the electric motor 18 to the drive unit 14. As shown, the hub 22 includes a first Mg portion 26 having a first inner surface 28 and a second Mg portion 30 having a second inner surface 32.

[0113] refer to Figures 1B-2B Hub 22 includes an aluminum (Al) alloy insert (hereinafter referred to as the Al insert) having a first outer surface 36 and a second outer surface 38. As depicted, the Al insert 34 is cast between the first Mg portion 26 and the second Mg portion 30. That is, the first inner surface 28 is aligned with the first outer surface 36 to define a first interface 40, and the second inner surface 32 is aligned with the second outer surface 38 to define a second interface 42. According to this embodiment, the Al insert 34 comprises iron (Fe) and manganese (Mn). Preferably, the Al insert 34 has a predetermined Fe / Mn weight ratio to avoid, minimize, or reduce welding problems during the die casting of the Mg alloy and the Al alloy. Typically, the Al alloy contains a relatively high Fe / Mn weight ratio, which can lead to welding problems and galvanic corrosion during the die casting of the Mg alloy and the Al alloy.

[0114] It has been unexpectedly determined that applying a relatively low Fe / Mn weight ratio avoids welding problems and reduces galvanic corrosion during die casting. In this embodiment, the predetermined Fe / Mn weight ratio of the Al insert 34 is between 1:20 and 1:30. In one embodiment, the Fe / Mn weight ratio of the Al insert 34 is 1:20. In another embodiment, the Fe / Mn weight ratio of the Al insert 34 is 1:25. In yet another embodiment, the Fe / Mn weight ratio of the Al insert 34 is 1:30.

[0115] like Figure 2A and Figure 2B As shown, the Al insert 34 has a flange 44 formed adjacent to a first outer surface 36 of the Al insert 34. The flange 44 is arranged to be loaded with compressive stress and to transfer the compressive stress to the first interface 40. During operation of the EV, the compressive stress transferred to the first interface 40 will counteract the tensile stress thereon, thereby reducing fatigue and potential cracking at the first interface 40. Preferably, the compressive stress is between 150 mPa and 250 mPa. Furthermore, the compressive stress to be loaded thereon can be determined by the yield strength of the Mg alloy at the first inner surface 28. It should be understood that, without departing from the spirit or scope of this disclosure, the flange 44 can be loaded with compressive stress by local rolling thereon or by any other suitable method. In addition, each of the first outer surface 36 and the second outer surface 38 includes a Zn coating 46 thereon for enhancing the metallurgical bond with the Mg alloy at the first interface 40 and the second interface 42.

[0116] In one embodiment, the Al insert 34 comprises: 0.1 to 13.0 wt% silicon (Si), 0.05 to 4.0 wt% copper (Cu), 0.01 to 3.0 wt% magnesium (Mg), 0.01 to 0.2 wt% iron (Fe), 0.1 to 1.0 wt% manganese (Mn), 0 to 0.3 wt% nickel (Ni), 0 to 6.0 wt% zinc (Zn), and 0 to 0.5 wt% chromium (Cr).

[0117] In another embodiment, the Al insert 34 is a forged Al alloy having a composition comprising 0.1 to 1.5 wt% Si, 0.05 to 2.0 wt% Cu, 0.01 to 3.0 wt% Mg, 0.01 to 0.2 wt% Fe, 0.5 to 1.0 wt% Mn, 0 to 0.3 wt% Ni, 0.1 to 6.0 wt% Zn, and 0 to 0.5 wt% Cr.

[0118] In yet another embodiment, the Al insert 34 is a cast aluminum alloy having a composition comprising 4.0 to 13.0 wt% Si, 0 to 4.0 wt% Cu, 0.01 to 1.5 wt% Mg, 0.01 to 0.2 wt% Fe, 0.1 to 1 wt% Mn, 0 to 0.3 wt% Ni, 0 to 3 wt% Zn and 0 to 0.5 wt% Cr.

[0119] In one embodiment, the Mg alloy of body 20 comprises 3.8 to 4.2 wt% Al, 0.3 to 0.4 wt% Mn, 0.15 to 0.25 wt% Zn, 3.8 to 4.2 wt% rare earth metal (one of cerium (Ce) and lanthanum (La)) and the balance being Mg.

[0120] Further reference Figure 2A and Figure 2B The Al insert 34 may have recesses 48 formed on its first outer surface 36 and second outer surface 38 for enhancing mechanical bonding. During the die casting of the Mg alloy, the liquid Mg alloy will flow, cool, and solidify within the recesses 48 to enhance mechanical bonding.

[0121] exist Figures 1B-2B The first Mg portion 26 and the second Mg portion 30 can be formed together with the Al insert 34 by die casting methods known in the art. However, before die casting the first Mg portion 26 and the second Mg portion 30 onto the Al insert 34, the Al insert 34 can be preheated to a preheating temperature of 100 to 300 degrees Celsius. That is, as the Al insert 34 (solid) is placed in the mold cavity of the predetermined casting (not shown), the Al insert 34 can be preheated to 100 to 300 degrees Celsius in any suitable manner to enhance diffusion and enhance the metallurgical bonding of Al and Mg at the first interface 40 and the second interface 42 during die casting. When the Al insert 34 is at the preheating temperature, the first Mg portion 26 and the second Mg portion 30 (molten) can be poured or injected into the mold cavity of the predetermined casting and contact the Al insert 34 at the first interface 40 and the second interface 42, respectively. Since Al is more active at higher temperatures, the enhanced diffusion of Al and Mg provides enhanced metallurgical bonding at the first interface 40 and the second interface 42.

[0122] Figures 3A to 4B An aluminum (Al) alloy insert 134 (hereinafter referred to as the Al insert) according to another embodiment of the present disclosure is shown. As shown, the Al insert 134 is similar to that discussed previously. Figure 1A-Figure 2B The Al insert is included, but it also includes a second Mg portion. (Reference) Figures 3A to 4BA magnesium (Mg) alloy housing 112 is provided for a drive unit of an electric vehicle (EV) having a drive shaft connected to an electric motor. As shown, the Mg alloy housing 112 includes a body 120 comprising the Mg alloy. The body 120 is arranged to house the drive unit of the EV.

[0123] In this embodiment, the Mg alloy housing 112 further includes a cylindrical hub 122 disposed on the body 120. As depicted, the hub 122 has a hole 124 formed therethrough and is arranged to connect the drive shaft of an electric motor to a drive unit. The hole 124 has a center through which a rotation axis X is defined. The hub 122 includes an Mg portion 126 having an inner surface 128. Furthermore, the hub 122 includes an Al insert 134 having an outer surface 136. The Al insert 134 is arranged on the Mg portion 126 such that the inner surface 128 is aligned with the outer surface 136 defining a weld interface 140.

[0124] According to this embodiment, the Al insert 34 comprises iron (Fe) and manganese (Mn). Preferably, the Al insert 134 has a predetermined Fe / Mn weight ratio to avoid or minimize welding problems during the welding or die-casting of the Mg alloy and the Al alloy. Typically, the Al alloy contains a relatively high Fe / Mn weight ratio, which can lead to welding problems during the welding or die-casting of the Mg alloy and the Al alloy, as well as galvanic corrosion during operation.

[0125] It has been unexpectedly determined that the relatively low Fe / Mn weight ratio in the Al alloy allows for the avoidance of welding problems and galvanic corrosion during welding or die casting. In this embodiment, the predetermined Fe / Mn weight ratio of the Al insert 134 is between 1:20 and 1:30. In one embodiment, the Fe / Mn weight ratio of the Al insert 134 is 1:20. In another embodiment, the Fe / Mn weight ratio of the Al insert 134 is 1:25. In yet another embodiment, the Fe / Mn weight ratio of the Al insert 134 is 1:30.

[0126] like Figure 3A and Figure 4BAs shown, the Al insert 134 has a flange 144 formed adjacent to its outer surface. The flange 144 is arranged to be loaded with compressive stress and to transfer the compressive stress to the interface. During operation of the EV, the compressive stress transferred to the interface will counteract the tensile stress thereon, thereby reducing fatigue and potential cracking at the interface. Preferably, the compressive stress is between 150 mPa and 250 mPa. Furthermore, the compressive stress to be loaded thereon can be determined by the yield strength of the Mg alloy at the inner surface. It should be understood that, without departing from the spirit or scope of this disclosure, the flange 144 can be loaded with compressive stress by local rolling thereon or by any other suitable method. In addition, the outer surface includes a Zn coating 146 thereon for enhancing the metallurgical bond with the Mg alloy at the interface.

[0127] In one embodiment, the Al insert 134 comprises: 0.1 to 13.0 wt% silicon (Si), 0.05 to 4.0 wt% copper (Cu), 0.01 to 3.0 wt% magnesium (Mg), 0.01 to 0.2 wt% iron (Fe), 0.1 to 1.0 wt% manganese (Mn), 0 to 0.3 wt% nickel (Ni), 0 to 6.0 wt% zinc (Zn), and 0 to 0.5 wt% chromium (Cr).

[0128] In another embodiment, the Al insert 134 is a forged Al alloy having a composition comprising 0.1 to 1.5 wt% Si, 0.05 to 2.0 wt% Cu, 0.01 to 3.0 wt% Mg, 0.01 to 0.2 wt% Fe, 0.5 to 1.0 wt% Mn, 0 to 0.3 wt% Ni, 0.1 to 6.0 wt% Zn, and 0 to 0.5 wt% Cr.

[0129] In yet another embodiment, the Al insert 34 is a cast aluminum alloy having a composition comprising 4.0 to 13.0 wt% Si, 0 to 4.0 wt% Cu, 0.01 to 1.5 wt% Mg, 0.01 to 0.2 wt% Fe, 0.1 to 1 wt% Mn, 0 to 0.3 wt% Ni, 0 to 3 wt% Zn and 0 to 0.5 wt% Cr.

[0130] In one embodiment, the Mg alloy of body 20 comprises 3.8 to 4.2 wt% Al, 0.3 to 0.4 wt% Mn, 0.15 to 0.25 wt% Zn, 3.8 to 4.2 wt% rare earth metal (one of cerium (Ce) and lanthanum (La)) and the balance being Mg.

[0131] Also refer to Figure 3BThe Al insert 134 may have a notch 148 formed on its exterior to enhance the mechanical bond. During the die casting of the Mg alloy, the liquid Mg alloy will flow, cool, and solidify within the notch 148 to enhance the mechanical bond.

[0132] refer to Figure 5 Furthermore, according to another aspect of this disclosure, a method 210 for friction welding a Mg alloy housing for a drive unit of an electric vehicle (EV) having a drive shaft connected to an electric motor is disclosed. The Mg housing has enhanced fatigue resistance. As shown in block 212, method 210 includes providing a body 120 comprising a Mg alloy, the body 120 being arranged to house the drive unit of the EV.

[0133] like Figure 5 As shown, in block 214, method 210 further includes providing a cylindrical hub 122 disposed on the body 120. The cylindrical hub 122 of method 210 may be... Figures 3A to 4B The cylindrical hub 122 is depicted in the diagram. Therefore, in relation to method 210, further reference to the cylindrical hub 122 refers to... Figures 3A to 4B The cylindrical hub 122 shown.

[0134] As discussed, hub 122 has a hole 124 formed therethrough and is arranged to connect the drive shaft of an electric motor to a drive unit. Hole 124 has a center through which a rotation axis is defined. Hub 122 includes an Mg portion having an inner surface. Hub 122 includes an Al insert 134 having an outer surface. Al insert 134 is arranged on the Mg portion such that the inner surface is aligned with the outer surface, thereby defining a weld interface.

[0135] In this example, the body 120 is attached to a fixed structure. Then, in block 216, method 210 further includes rotating the Al insert 134 about a rotation axis over the Mg portion at a rotational speed of 500 to 3000 rpm. In block 218, method 210 further includes moving the Al insert 134 to the Mg portion such that the inner surface is aligned with the outer surface to define a weld interface. In block 220, method 210 further includes bringing the inner surface and the outer surface into contact at the weld interface with a loading pressure of 10 to 300 mPa to frictionally weld the Al insert 134 and the Mg portion. That is, the Al insert 134 is rotated to weld to the inner surface to define the interface while the outer surface contacts the inner surface at a rotational speed of 500 to 3000 rpm under a loading pressure of 10 to 300 mPa.

[0136] The description in this disclosure is merely exemplary in nature, and variations thereof without departing from the spirit and scope of this disclosure are intended to fall within its scope. Such variations should not be considered as departing from the spirit and scope of this disclosure.

Claims

1. A Mg alloy housing for a drive unit of an electric vehicle, the electric vehicle having a drive shaft connected to an electric motor, the housing comprising: The body comprises a Mg alloy body, the body being arranged to house the drive unit of the electric vehicle; A cylindrical hub disposed on the body, the hub having a hole formed through the hub and arranged to connect the drive shaft of the electric motor to the drive unit, the hub including a first Mg portion having a first inner surface and a second Mg portion having a second inner surface, the hub including an Al alloy insert having a first outer surface and a second outer surface, the Al alloy insert being cast between the first Mg portion and the second Mg portion such that the first inner surface is aligned with the first outer surface to define a first interface and the second inner surface is aligned with the second outer surface to define a second interface, the Al insert including Fe and Mn, the Al alloy insert having a flange formed adjacent to the first outer surface, the flange being arranged to be loaded with compressive stress and to transfer the compressive stress to the first interface to counteract tensile stress during use, thereby minimizing fatigue and cracking thereon, each of the first outer surface and the second outer surface including a Zn coating on the first outer surface and the second outer surface for enhancing metallurgical bonding at the first interface and the second interface.

2. The housing according to claim 1, wherein, The Al alloy insert has the following components: 0.1 to 13.0 wt% Si; 0.05 to 4.0 wt% Cu; 0.01 to 3.0 wt% Mg; 0.01 to 0.2 wt% Fe; 0.1 to 1.0 wt% Mn; 0 to 0.3 wt% Ni; 0 to 6.0 wt% Zn; and 0 to 0.5 wt% Cr.

3. The housing according to claim 1, wherein, The Al alloy insert is a forged Al alloy, and the forged Al alloy has the following components: 0.1 to 1.5 wt% Si; 0.05 to 2.0 wt% Cu; 0.01 to 3.0 wt% Mg; 0.01 to 0.2 wt% Fe; 0.5 to 1.0 wt% Mn; 0 to 0.3 wt% Ni; 0.1 to 6.0 wt% Zn; and 0 to 0.5 wt% Cr.

4. The housing according to claim 1, wherein, The Al alloy insert is a cast Al alloy, and the cast Al alloy has the following components: 4.0 to 13.0 wt% Si; 0 to 4.0 wt% Cu; 0.01 to 1.5 wt% Mg; 0.01 to 0.2 wt% Fe; 0.1 to 1 wt% Mn; 0 to 0.3 wt% Ni; 0 to 3 wt% Zn; and 0 to 0.5 wt% Cr.

5. The housing according to claim 1, wherein, The Fe / Mn weight ratio of the Al alloy insert is 1:

20.

6. The housing according to claim 1, wherein, The Fe / Mn weight ratio of the Al alloy insert is 1:

25.

7. The housing according to claim 1, wherein, The Fe / Mn weight ratio of the Al alloy insert is 1:

30.

8. The housing according to claim 1, wherein, The Al alloy insert has recesses formed on the first and second outer surfaces of the Al alloy insert for enhancing mechanical bonding.

9. The housing according to claim 1, wherein, The compressive stress is between 150 MPa and 250 MPa.

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