Description:FORM 2
The Patent Act 1970
(39 of 1970)
and
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“SPLIT MOTOR HOUSING FOR POWER TRANSMISSION SYSTEM OF A VEHICLE”

Endurance Technologies Limited
E-92, M.I.D.C. Industrial Area, Waluj,
Chh. Sambhajinagar – 431136 (formerly Aurangabad),
Maharashtra, India

The following specification describes the nature of the invention and the manner in which it is to be performed.

Field of Invention

[001] The present invention relates to a motor housing for power transmission system of a vehicle. More particularly, the present invention relates to the motor housing for electric vehicles wherein said motor housing has a uniquely profiled cooling jackets and a plurality of split parts joined together in a liquid tight manner.

Background of the Invention

[002] Electric motors are widely used in power transmission system of electric / hybrid vehicles for powering the said vehicles. An electric motor is an electrical machine that converts the electrical energy into mechanical energy. All electric motors have a housing that serves the function of housing and protecting the working components of the motor. The conventional motor housings of the electric / hybrid vehicles have an integrated structure having a main housing and an end cover for housing the gearbox of the vehicle. The motor housings are generally provided with the cooling channel(s) which can be installed in between the stator assembly (lost cores), rotor assembly and motor housing. This requires a complex manufacturing process which is not suitable for large-scale manufacturing. Also, the cross-sections of the cooling channels of the conventional motor housings are relatively large. This accounts for an increased volume of cooling liquid which further leads to an increased system weight. An alternative manufacturing method for creating liquid cooling channels in the motor housing is to use cast-in pipes, which later form the cooling channels. This process is also very complex and not suitable for mass production.

[003] Also, the conventional method of manufacturing the liquid cooled motor housings includes the formation of cooling jackets in a casted alloy part which is usually fused with another casted alloy cover. The casted alloys have a certain amount of hydrogen which leads to the formation of pores thus having a poor sealing performance which might lead to the leakage of the cooling fluid therefrom.

[004] Therefore, to address the limitations of the existing solutions, there is a pressing need of providing a liquid-cooled motor housing, especially for electric motors of electric / hybrid vehicles, which are cost-effective, easy to automate and can be produced economically in large and very large quantities.

Objectives of the Present Invention

[005] The main object of the present invention is to provide a motor housing for a power transmission system of a vehicle.

[006] Another object of the present invention is to provide a motor housing having an inner housing and an outer housing and said two housing are intelligently joined together in a liquid tight manner.

[007] Another object of the present invention is to provide a uniquely profiled inner housing formed in a manner to have an optimum geometry of cooling jackets.

[008] Yet, another object of the present invention is to provide an outer housing having an integrated end cover for housing the power transmission system of a vehicle.
Brief Description of Drawings

[009] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein and advantages thereof will be better understood from the following description when read with reference to the following drawings, wherein

[0010] Figure 1 discloses the isometric view of the motor housing as per the present invention.

[0011] Figure 2 describes the cut-sectional view of the motor housing of the present invention.

[0012] Figure 3 depicts the isometric view of the inner housing of the motor housing in accordance with the present invention.

[0013] Figure 4 shows the cut-sectional view of the inner housing of the motor housing in accordance with the present invention.

[0014] Figure 5 discloses the isometric view of the outer housing of the motor housing in accordance with the present invention.

[0015] Figure 6 presents the cut-sectional view of the outer housing of the motor housing in accordance with the present invention.

Detailed Description of the Present Invention

[0016] The invention will now be described in detail with reference to the accompanying drawings which must not be viewed as restricting the scope and ambit of the invention. Referring to Figs. 1 and 2, the motor housing (500) of the present invention comprises of an inner housing (100) and an outer housing (200) wherein the said inner housing (100) is joined with the outer housing (200) in a liquid-tight manner.

[0017] Referring to Figs 3 and 4, the inner housing (100) is a hollow cylindrical body (110) having an annular base (115) wherein the cylindrical body (110) protrudes upwardly from the annular base (115) in an integral manner. The annular base (115) of the inner housing has an inner top face (115T) and an outer bottom face (115B). The annular base (115) has an annular collar (110AC) protruding out from the inner top face (115T) of the annular base (115) of the inner housing (100). The annular collar (110AC) has a thorough opening (110P) formed therein which allows the fitting of the inner housing (100) with the outer housing (200).

[0018] The cylindrical body (110) of the inner housing (100) has a vertical axis A-A wherein the said cylindrical body (110) is configured to have a plurality of circular ribs (120) and a plurality of helical ribs (130) formed over its outer peripheral surface. The helical ribs (130) are positioned in between the two extreme circular ribs (120) and merges with the said circular ribs (120). The extremity between the said ribs is defined as the space in between a top circular rib (120T) and a bottom circular rib (120B). The cylindrical body (110) of the inner housing also has a plurality of elliptical tabs (140) protruding out from the outer peripheral surface of the cylindrical body (110) wherein the said elliptical tabs (140) are positioned in a non-uniform orientation over its periphery. The non-uniform orientation of the tabs (140) facilitates the formation of fluid pockets resulting in accumulation of the cooling fluid therein. A plurality of cooling jackets (120J) are formed in between the two consecutive ribs (120, 130) wherein the said ribs (120, 130) are distributed on the outer peripheral surface of the cylindrical body (110) in a manner to have a uniform spacing between each other. The number of cooling jackets (120J) are selected in a manner to have an optimum volume of the cooling fluid and thus the said jackets range from a minimum three jackets to a maximum five jackets.

[0019] Referring to Figs 5 and 6, the outer housing (200) is configured to have a hollow cylindrical body (210) having a vertical axis B-B and an end cover (220) wherein the cylindrical body (210) and the end cover (220) are formed as an integral unit to each other. The cylindrical body (210) of the outer housing (200) is configured to house the inner housing (100) and the end cover (220) is configured to house the gear mechanism of the power transmission system of the vehicle. The cylindrical body (210) of the outer housing (200) has an inner top face (210T) confirming to the matching geometry of the annular base (115) and the annular collar (110AC) of the inner housing (100) thus forming an annular collar (210AC) therein. The annular collar (210AC) has an opening (210P) allowing the passage for the drive mechanism of the power transmission of the vehicle.

[0020] The cylindrical body (210) of the outer housing (200) is configured to have an inner diameter greater than the outer diameter of the ribs (120, 130) of the inner housing (100) in accordance with the suitable press-fitting tolerances. The cylindrical body (210) of the outer housing (200) has a plurality of mounting tabs (210M) at its top end (210TE) wherein the said mounting tabs (210M) facilitates the mounting of the motor housing (500) with the power transmission system. Further, the said cylindrical body (210) is configured to have a plurality of vertical ribs (210VR) in axial direction B-B and a plurality of annular ribs (210AR) formed on its outer peripheral surface in such a way that each of the annular ribs (210AR) is orthogonal with the vertical ribs (210VR). The said vertical ribs (210VR) and the annular ribs (210AR) helps in imparting / inducing the mechanical strength to the outer housing (200).

[0021] The inner housing (100) and the outer housing (200) are formed by the high pressure die-casting method (HPDC) wherein the said housings are made from an aluminum or copper alloy and the most preferable alloys are SiCu2(Fe), Si9Cu3(Fe), Si12Cu1(Fe) and AlSi9MnMg.

[0022] The motor housing (500) of the present invention is formed by joining the inner housing (100) and the outer housing (200) together in a manner to have the vertical axis A-A of the inner housing (100) coincide with the vertical axis B-B of the outer housing (200). The said housings are joined by using the friction stir welding wherein at least one weld seam is formed in between the top end (110TE) of the outer peripheral surface of the cylindrical body (110) of the inner housing (100) and the top end (210TE) of the inner peripheral surface of the cylindrical body (210) of the outer housing. The weld seam has a closed circular shape covering the entire periphery of the inner housing (100) and the outer housing (200) to ensure that no liquid between the inner housing (100) and the outer housing (200) is escaped out from the cooling jackets (120J). The inner housing (100) and the outer housing (200) are further additionally fastened together with the help of the fastening means viz. screws, rivets, gas shielded arc welding etc. after the friction stir welding. The additional fastening of the said inner and outer housings imparts the extra rigidity to the motor housing (500), thus sealing the cooling jackets thereby. Further, these additional sealing between the inner housing (100) and the outer housing (200) increases the rigidity of the motor housing (500) thus enabling the manufacturing of the motor housing (500) lighter in weight but with enhanced mechanical properties viz. high strength and load-bearing capacity.

[0023] The motor housing (500) having a uniquely profiled inner housing (100) and the outer housing (200) joined together by friction stir welding forming a liquid tight seal provides an optimal geometry of the cooling jackets in a process-reliable and cost-effective manner. Thus, the weight of the motor housing (500) is in optimum range owing to the optimized volume of the cooling water channels.

[0024] The motor housing (500) of the present invention provides the following technical advantages that contributes to the advancement of technology:
- It provides an optimum geometry of cooling jackets which leads in weight reduction.
- It efficiently minimizes the casting cycle time and assembly time.
- It helps in achieving an optimum and uniform temperature gradient within the motor housing.
- It contributes to eliminate complex manufacturing process thus leading to a cost effective solution.
- The sealing between the inner housing (100) and the outer housing (200) increases the rigidity of the motor housing (500) thus enabling the manufacturing of the motor housing (500) lighter in weight but with enhanced mechanical properties viz. high strength and load-bearing capacity.
[0025] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the invention herein has been described in terms of a generalized form, those skilled in the art will recognize that the invention herein can be practiced with modification within the spirit and scope of the invention as described herein. , Claims:We Claim

1. A split motor housing for power transmission system of a vehicle comprising of an inner housing (100) and an outer housing (200)
wherein,
- the inner housing (100) is an integral unit of a hollow cylindrical body (110) and an annular base (115) wherein the cylindrical body (110) protrudes upwardly from the annular base (115) in axial direction A-A; and said cylindrical body (110) is configured to have a plurality of circular ribs (120) and a plurality of helical ribs (130) formed over its outer peripheral surface;
- the outer housing (200) is an integral unit of a hollow cylindrical body (210) and an end cover (220) wherein said cylindrical body (210) is configured to house the inner housing (100) and the end cover (220) is configured to house a gear mechanism of the power transmission system of the vehicle; and
- the inner housing (100) is joined with the outer housing (200) in a liquid-tight manner by the friction stir welding in a manner to have the vertical axis A-A of the inner housing (100) coinciding with the vertical axis B-B of the outer housing (200).

2. The split motor housing for power transmission system of a vehicle as claimed in claim 1, wherein
- the annular base (115) of the inner housing (100) is configured to have an inner top face (115T), an outer bottom face (115B) and an annular collar (110AC); and said annular collar (110AC) protrudes out from the inner top face (115T) of the annular base (115) of the inner housing (100); and
- the helical ribs (130) are positioned in between the two extreme circular ribs (120) and configured to merge with the said circular ribs (120); and the extremity between the said ribs (120) is defined as the space in between a top circular rib (120T) and a bottom circular rib (120B).

3. The split motor housing for power transmission system of a vehicle as claimed in claim 2, wherein
- the cylindrical body (110) of the inner housing (100) is configured to have a plurality of elliptical tabs (140) protruding out from the outer peripheral surface of the cylindrical body (110);
- the two consecutive ribs (120, 130) are configured to form a cooling jacket (120J) and said ribs (120, 130) are distributed on the outer peripheral surface of the cylindrical body (110) in a manner to have a uniform spacing between the two consecutive ribs (120, 130); and
- said cooling jackets (120J) are selected in a manner to have an optimum volume of the cooling fluid.

4. The split motor housing for power transmission system of a vehicle as claimed in claim 3, wherein
- the elliptical tabs (140) on the cylindrical body (110) of the inner housing (100) are positioned in a non-uniform orientation over periphery of said cylindrical body (110) to facilitate the formation of fluid pockets resulting in accumulation of the cooling fluid therein; and
- the cooling jackets (120J) on the cylindrical body (110) ranges from minimum three jackets to maximum five jackets.

5. The split motor housing for power transmission system of a vehicle as claimed in claim 1, wherein
- the cylindrical body (210) of the outer housing (200) is configured to have a top face (210T) confirming to the matching geometry of the annular base (115) and the annular collar (110AC) of the inner housing (100); and said annular collar (110AC) of the inner housing (100) has a thorough opening (110P) formed therein configured to fit said inner housing (100) with the outer housing (200);
- an annular collar (210AC) of the outer housing (200) has an opening (210P) configured to house the drive mechanism of power transmission of the vehicle;
- the inner diameter of the cylindrical body (210) of the outer housing (200) is greater than the outer diameter of the ribs (120, 130) on the inner housing (100) configured to maintain the press-fitting tolerance; and
- said cylindrical body (210) of the outer housing (200) is configured to have a plurality of mounting tabs (210M) at its top end (210TE) wherein the said mounting tabs (210M) are configured to mount the motor housing (500) with the power transmission system of the vehicle.

6. The split motor housing for power transmission system of a vehicle as claimed in claim 5, wherein
- said cylindrical body (210) is configured to have a plurality of vertical ribs (210VR) in axial direction B-B and a plurality of annular ribs (210AR) formed on its outer peripheral surface;
- each of the annular ribs (210AR) is orthogonal with the vertical ribs (210VR); and
- said vertical ribs (210VR) and the annular ribs (210AR) are configured to induce the mechanical strength to the outer housing (200).

7. The split motor housing for power transmission system of a vehicle as claimed in any of the claims 4 and 6, wherein the inner housing (100) and the outer housing (200) are made by a high pressure die-casting method (HPDC) from an aluminum or copper alloy selected from SiCu2(Fe), Si9Cu3(Fe), Si12Cu1(Fe) and AlSi9MnMg.

8. The split motor housing for power transmission system of a vehicle as claimed in claim 7, wherein
- the said housings (100 and 200) are joined by the friction stir welding wherein at least one weld seam is formed in between the top end (110TE) of the outer peripheral surface of the cylindrical body (110) of the inner housing (100) and the top end (210TE) of the inner peripheral surface of the cylindrical body (210) of the outer housing (200);
- said weld seam is configured to have a closed circular shape covering the entire periphery of the inner housing (100) and the outer housing (200) to ensure that no liquid between the inner housing (100) and the outer housing (200) is escaped out from the cooling jackets (120J);
- said inner housing (100) and the outer housing (200) are fastened together with the help of the fastening means after the friction stir welding to impart the rigidity to the motor housing (500); and
- said fastening means are selected from screws, rivets, and gas shielded arc welding.

Dated this 24th day of Oct. 2024

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

To,
The Controller of Patents,
The Patent Office, at Mumbai