Description:TECHNICAL FIELD
[001] The present disclosure generally relates to a sub-frame assembly for mounting a motor in an electric vehicle and more particularly, the present disclosure relates to a rear sub-frame assembly with a three-point motor mounting arrangement for mounting the motor at a rear-side of the vehicle.
BACKGROUND
[002] Electric vehicles which have a rear wheel drive predominantly employ a motor to power the rear wheels of the vehicle. Conventionally, the motor is mounted onto a sub-frame of the vehicle by means of four mounting points provided on the sub-frame. Alternatively, the motor can be mounted on the sub-frame through three-point mounting, wherein two mounting points are provided at a front side of the sub-frame, i.e., one on left side and the other on the right side of the frame, and a third mounting point is provided on a rear side of the sub-frame. In some of the sub-frame assemblies, the two mounting points may be provided at the rear side of the sub-frame and one point provided at the front side of the sub-frame.
[003] Conventionally, the two mounting points are provided with sleeves which are integrated with the sub-frame disposed at the front side of the frame. These mounting sleeves form an integral part of the sub-frame as they are welded rigidly onto the sub-frame. Further, the third mounting point is either provided as a mounting bracket or integrated within the sub-frame at the frame’s rear side. Insulator bushes are press fitted into these mounting sleeves and the third mounting point before the motor is assembled onto the sub-frame, thus making the insulator bushes an integral part of the sub-frame. Hence, during the assembling of the motor onto the sub-frame i.e., during the rear motor lowering, it becomes critical to ensure that the mounting points of the motor align with the corresponding insulator bushes of the two front mounting sleeves and the third rear mounting point.
[004] Therefore, the downsides of the sub-frame assemblies having integrated bushings include the precision required in motor alignment during assembly of the motor onto the sub-frame and the requirement of pre-compression of the insulator bush. These issues are prevalent during the motor lowering while the motor is being mounted and pre-engaged, during the assembly of the motor. Ideally, the insulator bush faces must align to its corresponding butting face on the motor and the bolting axis of the insulator bush must align with the bolting axis of the motor. The alignment of the motor and the bush with the bolt is challenging in the conventional motor lowering and motor mounting scenario due to the tolerances of the parts and due to the variations in the assembling robots. Further, when the assembly of the motor onto the sub-frame is relied on the skill of the operators, the potential of deviation in the assembly is huge which might cause misalignment of the motor mounting faces.
[005] Furthermore, the tolerances of the various parts such as motor, bolts, motor mounting brackets, insulator bushes play a crucial role for bolting axis alignment. Higher tolerances in the parts tend to have higher misalignment in the motor bolting axis and butting faces. The tolerances of the parts stack up and cause higher misalignment in the mounting axis and the butting faces. This misalignment must be accommodated by the insulator bushes to align the motor mounting face and axis during the assembly which would inevitably skew the rubber in the insulator bushes during the assembly and torquing. Thus, the rubber insulator bushes experience a pre-compliance (a pre-compression to accommodate the skew) even in the static condition of the motor (i.e., before the motor is even operated). This leads to a deteriorated performance of the insulator bushes during compliance action when the motor rocks during operation, therefore resulting in vibrations in the motor and sub-frame. These vibrations are then carried over to the vehicle as it takes the transfer path of the vehicle body in white (BIW), setting up noise and vibrations and therefore causing discomfort to the occupants of the vehicle.
[006] The disadvantage due to motor misalignment in the conventional sub-frame assemblies with integrated insulator bushes not only deteriorates the NVH (noise, vibration & harshness) performance of the vehicle but also demands for a robotic assembly of the motor onto the sub-frame since the motor lowering must be accurately controlled within the small band of tolerances to prevent the motor from damaging the insulator bushes and the sub-frame while being lowered into position. Employing a cheaper or manual motor lowering using tackle hanger methodology is not possible in such type of sub-frame constructions due to the aforementioned issues. Thus, robots must be employed for high-precision motor lowering, thereby increasing the cost of the assembly line setup.
[007] Likewise, the tolerances of the features of sub-frame such as the welded sleeve, bolts, bush butting face, bush inner diameter must be accurately controlled limiting the tolerances to limit the stacked-up deviation of the bolt axis and bush resting face. This requires costly manufacturing setup of individual parts to curtail the tolerances of the key assembly features for the motor assembly. The cost of the entire sub-frame assembly in such prior arts is significantly higher and the manufacturing and assembly process is much more tedious.
[008] In the sub-frame assemblies having integrated insulator bushes, apart from the difficulties in assembling/ mounting of the motor on the sub-frame, the service of the insulator bushes also gets complicated. Any damage to the insulator bushes results in scrapping the entire sub-frame as removal of the insulator bushes can damage the welded sleeve permanently, resulting in higher costs incurred by customer during servicing.
[009] Therefore, there is a need for a sub-frame assembly for mounting a motor in a vehicle which obviates the aforementioned drawbacks of the existing sub-frame assembly.
OBJECTS
[010] The principal object of an embodiment of this invention is to provide a sub-frame assembly with a three-point motor mounting arrangement for mounting a motor in a vehicle which enables precision assembly of the motor onto the sub-frame.
[011] Another object of an embodiment of this invention is to provide the sub-frame assembly which includes at least two motor mounting brackets which are pre-assembled onto the motor.
[012] Yet another object of an embodiment of this invention is to provide the sub-frame assembly in which the two motor mounting brackets are mounted onto corresponding brackets provided on the sub-frame, thereby facilitating easy assembling and dis-assembling of the motor and the mounting brackets from the sub-frame.
[013] Still another object of an embodiment of this invention is to provide the sub-frame assembly which comprises of two brackets fastened at a front side of the sub-frame, and two motor mounting brackets pre-assembled on the motor, wherein the motor is assembled onto the sub-frame by mounting the motor mounting brackets on to the corresponding mounting bracket of the sub-frame.
[014] Another object of an embodiment of this invention is to provide the sub-frame assembly in which the motor mounting bracket is an inverted L-shaped bracket having a slot to receive an insulator bush.
[015] Yet another object of an embodiment of this invention is to provide the sub-frame assembly in which the mounting brackets provided on the sub-frame includes a horizontal face and a vertical face transversely extending from the horizontal face, wherein the horizontal and vertical face of the sub-frame bracket guides the L-shaped motor mounting bracket onto the sub-frame with precision.
[016] Still another object of an embodiment of this invention is to provide the sub-frame assembly in which the mounting brackets on the sub-frame and the motor mounting brackets on the motor are provided to facilitate easy and precise alignment of the motor with the sub-frame.
[017] Yet another object of an embodiment of this invention is to provide the sub-frame assembly which includes a motor mounting bracket pre-assembled onto a rear side of the motor at a pre-determined position, whereby facilitates easy alignment with a rear insulator bush inserted into a rear mounting point of the sub-frame.
[018] Another object of an embodiment of this invention is to provide a method for assembling a motor onto a sub-frame assembly having a three-point motor mounting arrangement.
[019] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[020] The embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[021] Fig. 1A is a perspective view of a conventional sub-frame with a three-point motor mounting assembly, wherein two mounting sleeves are integrated within the sub-frame at a front side of the frame and a third mounting point is integrated at a rear side of the sub-frame;
[022] Fig. 1B is a perspective view of the conventional sub-frame with three-point mounting assembly with insulator bushes press-fitted into the front mounting sleeves;
[023] Fig. 2 depicts a perspective view of a sub-frame assembly with a three-point motor mounting arrangement, according to an embodiment of the invention as disclosed herein;
[024] Fig.3 is a top view of the sub-frame assembly with a three-point motor mounting arrangement, according to an embodiment of the invention as disclosed herein;
[025] Fig. 4 is a perspective view from a rear side of the sub-frame assembly, according to an embodiment of the invention as disclosed herein;
[026] Fig. 5 is a perspective view of the sub-frame assembly with a left side motor mounting bracket and a right-side motor mounting bracket assembled onto a left side mounting bracket and right side mounting bracket of the sub-frame, and insulator bushes connected to the motor mounting brackets and rear mounting portion, according to an embodiment of the invention as disclosed herein;
[027] Fig. 6 is an isometric view of the motor mounting bracket with the insulator bush press fitted into the motor mounting bracket, according to an embodiment of the invention as disclosed herein;
[028] Fig. 7 depicts a perspective view of the motor with the motor mounting brackets pre-assembled onto the motor, according to an embodiment of the invention as disclosed herein;
[029] Fig. 8 is perspective view of the motor having a rear motor mounting bracket pre-assembled onto the motor, according to an embodiment of the invention as disclosed herein;
[030] Fig. 9 is a perspective of the motor with the motor mounting bracket and the rear mounting bracket, and the sub-frame assembly with the rear insulator bush inserted into the rear mounting portion, according to an embodiment of the invention as disclosed herein;
[031] Fig.10 is a schematic diagram of the motor mounting bracket depicting the motor mounting bracket and a portion of the sub-frame assembly, according to an embodiment of the invention as disclosed herein; and
[032] Fig.11 is a perspective view of the sub-frame assembly with the motor mounted on the sub-frame, according to an embodiment of the invention as disclosed herein.
DETAILED DESCRIPTION
[033] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[034] The embodiments herein achieve a sub-frame assembly with a three-point motor mounting arrangement for mounting a motor in a vehicle which enables precision assembling of motor onto the sub-frame. Further, the embodiments herein achieve the sub-frame assembly which includes at least two motor mounting brackets which are adapted to be pre-assembled onto the motor. Furthermore, the embodiments herein achieve the sub-frame assembly which includes at least two brackets mounted on a front side of the sub-frame for facilitating mounting of the motor at two points on the front side of the sub-frame and a third motor mounting point provided at a rear side of the sub-frame for facilitating mounting of the motor at a rear-side of the sub-frame. The embodiments herein achieve the sub-frame assembly in which the two motor mounting brackets are mounted onto corresponding mounting brackets provided on the sub-frame, facilitating easy assembling and dis-assembling of the motor and the motor mounting brackets on/from the sub-frame. Further, the embodiments herein achieve the sub-frame assembly which comprises of two brackets fastened at a front side of the sub-frame, and two motor mounting brackets pre-assembled on the motor, wherein the motor is assembled onto the sub-frame by mounting the motor mounting brackets on to the corresponding mounting bracket on the sub-frame. Furthermore, the embodiments herein achieve the sub-frame assembly in which the motor mounting bracket is an inverted L-shaped bracket having a slot to receive an insulator bush. The embodiments herein achieve the sub-frame assembly in which the brackets provided on the sub-frame include a horizontal face and a vertical face transversely extending from the horizontal face, wherein the horizontal and vertical face of the sub-frame bracket guides the L-shaped mounting bracket into place to be fastened onto the sub-frame with precision. Additionally, the embodiments herein achieve the sub-frame assembly in which the brackets on the sub-frame and the motor mounting brackets are provided to facilitate easy and precise alignment of the motor with the sub-frame. The embodiments herein achieve the sub-frame assembly which includes the motor mounting bracket pre-assembled onto a rear side of the motor at a pre-determined position, facilitating easy alignment of a rear insulator bush into a rear mounting portion of the sub-frame. Moreover, the embodiments herein achieve a method for assembling the motor onto a sub-frame assembly having a three-point motor mounting arrangement. Referring now to the drawings, and more particularly to FIGS. 1 through 11, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[035] Fig. 1A depicts a perspective view of a conventional sub-frame (100) with a three-point motor mounting assembly. The sub-frame (100) includes a front cross member (101), a rear cross member (102) positioned parallel to the front cross member (101), and two longitudinal members comprising a left side longitudinal member (103L) and a right-side longitudinal member (103R) connected transversely with the front cross member (101) and the rear cross member (102). Sub-components such as front upper link mounting, front lower link mounting, rear upper link mounting, and rear lower link mounting are mounted on the sub-frame (100) to facilitate attachment of components of the vehicle with the sub-frame. Further, the sub-frame (100) also includes four sub-frame mounting sleeves provided at front and rear corners of the sub-frame (100). Insulator bushes are press fitted into each of the sub-frame mounting sleeves and the sub-frame assembly is assembled onto the body of the vehicle via the four insulator bushes.
[036] The sub-frame (100) includes two sleeves (104L, 104R) which are disposed on the left side longitudinal member (103L) and the right side longitudinal member (103R) respectively, towards a front side of the sub-frame (100). The sleeves (104L, 104R) are integrated into the sub-frame (100) by rigidly welding the sleeves (104L, 104R) onto the sub-frame (100). As shown in Fig. 1B, insulator bushes (106L, 106R) are press-fitted into the sleeves (104L, 104R) before the motor is assembled onto the sub-frame (100). Further, a rear motor mounting slot (105) is provided on a rear side of the sub-frame (100) when viewed in the vehicle lengthwise direction. The rear motor mounting slot (105) is a slot defined into the rear cross member (102) of the sub-frame (100), wherein an insulator bush is inserted, and press fitted into the slot. The motor is assembled on the sub-frame (100) via the insulator bushes press-fitted into the two sleeves (104L, 104R) and the rear motor mounting slot (105).
[037] In the conventional sub-frame assembly (100) the bushes (106 L and 106R) are press fitted into the mounting points i.e., the two front sleeves (104L, 104R) and the rear motor mounting slot (105), before assembling/ mounting of the motor onto the sub-frame (100). When the motor is being assembled onto the sub-frame (100) it is crucial that a face of each of the insulator bushes (106) is aligned correctly with a corresponding butting face/ abutment provided on the motor. Slight misalignment of the insulator bush face and the corresponding abutment of the motor would generate a load on the insulator bushes (106L, 106R) and the sleeves (104L, 104R). The misalignment of the motor during assembly can also cause the sleeves (104L, 104R) to deform due to excess load experienced during the mounting of the motor. Since the sleeves (104L, 104R) are integrated with the sub-frame (100), the entire sub-frame (100) may be replaced if the sleeves (104L, 104R) or insulator bushes (106) are damaged or deformed. Further, the servicing of the insulator bushes (106L, 106R) also becomes complicated, since any damage to the insulator bushes (106L, 106R) will result in scrapping the entire sub-frame (100) as removal of the insulator bushes (106L, 106R) will damage the welded sleeves (104L, 104R) permanently.
[038] Fig. 2 is a perspective view of a sub-frame assembly (200) with three-point motor mounting arrangement, according to an embodiment of the invention as disclosed herein. The sub-frame assembly (200), according to an embodiment includes a front cross member (201), a rear cross member (202) disposed parallelly to the front cross member (201), a left side longitudinal member (203L) and a right side longitudinal member (203R), wherein the left side longitudinal member (203L) and the right side longitudinal member (203R) are connected transversely with the front cross member (101) and the rear cross member (102), forming an integrated sub-frame structure (200A). The sub-frame assembly (200) further includes sub-components such as front upper link mounting brackets (206A, 206B), front lower link mounting bracket (206C), rear upper link mounting member (207A, 207B), lower control arm mounting (209), and toe link mounting (210) connected to the sub-frame structure (200A) at predetermined positions. The sub-frame assembly (200) also includes a plurality of bush sleeves (208) for receiving subframe mounting insulator bushes (208A) (as shown in Fig.4), disposed at two front corners and two rear corners of the sub-frame structure (200A). The sub-frame assembly (200) is assembled onto the body in white (BIW) via the subframe mounting insulator bushes (208A) press-fitted into the plurality of bush sleeves (208).
[039] The sub-frame assembly (200) further includes at least two mounting brackets (204 L, 204 R) disposed on the front cross member (201) of the sub-frame structure (200A) at predetermined positions. However, it is within the scope of this invention to provide the mounting brackets (204L, 204R) on the rear cross member (202) of the sub-frame structure (200A) or any other portion of the sub-frame structure (200A), without deterring from the intended function of the invention. In an embodiment of the invention (as shown in Fig. 2 and 3), the sub-frame assembly (200) includes two mounting brackets (204L, 204R), wherein a first mounting bracket (204L) is mounted on the front cross member (201) on a left side, and a second mounting bracket (204R) is mounted on the front cross member (201) on a right side. In an embodiment, the mounting brackets (204L, 204R) are fastened onto the front cross member (201) through bolts. Each of the mounting brackets (204L, 204R) comprises of a horizontal face (not shown), and a vertical face (not shown) transversely extending from the horizontal face of the corresponding mounting bracket (204L, 204R). The mounting brackets (204L, 204R) are mounted on the front cross member (201) such that the horizontal face of the mounting bracket (204L, 204R) is parallel to a plane of the front cross member (201).
[040] As shown in Fig. 5, the sub-frame assembly (200) includes at least two motor mounting brackets (300) adapted to be mounted on the corresponding mounting brackets (204L, 204R) of the sub-frame assembly (200). According to an embodiment, as shown in Fig. 6, the motor mounting bracket (300) comprises an inverted L-shaped body (300A), wherein a slot is defined into the body (300A) of the motor mounting bracket (300) to receive an insulator bush (300B). In an embodiment, the sub-frame assembly (200) includes two motor mounting brackets (300F, 300S) wherein a first motor mounting bracket (300F) is adapted to be received by the first mounting bracket (204L) of the sub-frame disposed at the left side of the sub-frame structure (200A), and second motor mounting bracket (300S) is adapted to be received by the corresponding second mounting bracket (204R) of the sub-frame assembly (200) disposed at the right side of the sub-frame structure (200A). Further, the motor mounting brackets (300F,300S) are adapted to be mounted on the mounting bracket (204L, 204R) of the sub-frame assembly (200) such that, a shorter portion of the L-shaped body (300A) of the motor mounting brackets (300F and 300S) rests on the horizontal face of the mounting bracket (204L, 204R) and a longer portion of the L-shaped body (300A) is aligned with the vertical face of the mounting bracket (204L, 204R).
[041] The sub-frame assembly (200) further includes a third motor mounting portion (205) provided at a rear side (when viewed in the vehicle lengthwise direction) of the sub-frame structure (200A). However, it is within the scope of this invention to provide the third motor mounting portion/point (205) at front side of the sub-frame assembly (200) or at any other portion of the sub-frame assembly (200) without deterring with the intended purpose of the invention. In an embodiment, the third motor mounting portion/ point (205) (hereinafter also referred to as rear mounting portion) is connected to the rear cross member (202) of the sub-frame structure (200A), as shown in Fig. 4 and Fig. 5. The third motor mounting portion (205) comprises a slot for receiving a rear insulator bush (205A). The rear insulator bush (205A) is press-fitted into the slot such that a face of the rear insulator bush (205A) is engaged to a corresponding receiving portion on a motor (400). In an embodiment, as shown in Fig.8, the sub-frame assembly (200) includes a rear motor mounting bracket (500) which is adapted to be connected with the motor (400) such that the rear motor mounting bracket (500) facilitates the coupling of the rear insulator bush (205A) of the rear mounting portion (205) with the motor (400).
[042] Further, the insulator bush (300B) is inserted into the slot defined in the body (300A) of the motor mounting brackets (300F, 300S) (as shown in Fig. 6 and Fig. 7) before the motor mounting bracket (300F, 300S) is assembled on the motor (400). In an embodiment, the insulator bush (300B) is press-fitted into the body (300A) of the motor mounting brackets (300F, 300S). After the insulator bush (300B) has been inserted and pre-press fitted into the motor mounting brackets (300F, 300S), each of the motor mounting bracket (300F, 300S) is connected to the corresponding receiving portion of the motor (400). In an embodiment, the first motor mounting bracket (300F) with the insulator bush (300B) is mounted on a left side-receiving portion (not shown) of the motor (400) and the second motor mounting bracket (300S) with the pre-press fitted insulator bush (300B) is mounted on a right-side receiving portion (not shown) of the motor (400). Further, the rear motor mounting bracket (500) is connected to the motor (400) at a predetermined position before the motor (400) is assembled onto the sub-frame assembly (200). The rear insulator bush (205A) of the rear mounting portion (205) is inserted into the slot defined in the rear mounting portion (205) before the motor (400) is assembled onto the sub-frame structure (200A). A motor sub-assembly comprising the motor (400) with the motor mounting brackets (300F, 300S) and the rear mounting bracket (500) mounted on the motor (400), are then assembled onto the sub-frame assembly (200) (as shown in Fig. 11). The motor sub assembly is aligned with the sub-frame assembly (200) such that the motor mounting brackets (300F, 300S) rest on the corresponding mounting brackets (204L, 204R) of the sub-frame assembly (200), wherein the horizontal face and the vertical face of the mounting brackets (204L, 204R) guide the motor mounting brackets (300F,300S) into place on the sub-frame assembly (200). Further, the rear motor mounting bracket (500) is aligned with the rear insulator bush (205A) of the rear mounting portion (205) such that a face of the rear insulator bush (205A) is in line with a corresponding butting portion on the rear motor mounting bracket (500).
[043] In an embodiment of the invention, the motor mounting brackets (300F, 300S), and the mounting brackets (204L, 204R) of the sub frame assembly (200) are made of a material such as aluminum. In another embodiment of the invention, the motor mounting brackets (300F and 300S) are fastened to the corresponding mounting brackets (204L, 204R) through fastening means comprising of bolts after the motor sub-assembly is aligned with the sub-frame assembly (200).
[044] The sub-frame assembly (200) facilitates simpler and cheaper assembling of the motor (400) onto the sub-frame structure (200A) by eliminating/minimizing the need for robotic assembly. The sub-frame assembly (200) employs mounting brackets (204L, 204R) to receive the motor (400) via the motor mounting brackets (300F, 300S). This enables the free lowering of the motor (400) manually with semi-skilled labor by employing a simple tackle hanger methodology wherein the motor (400) is hung from top using ropes, chains, or belts and slowly lowered into an assembly position. Further, since the motor mounting bracket (300F, 300S) are designed as L-shaped, the motor sub-assembly is guided by the vertical and horizontal face of the mounting brackets (204L, 204R) of the sub-frame assembly (200). The horizontal face of the mounting brackets (204L, 204R) ensures that the entire weight of the motor sub-assembly is rested onto the sub-frame assembly (200). This also helps in aligning a motor mounting bolt axis and butting faces of the motor (400) as they are not strained by the self-weight of the motor (400) hung by the hanger ropes. Thus, misalignment can be avoided significantly.
[045] In an embodiment, an entry chamfer (204A) is provided in each of the mounting bracket (204) (as shown in Figure 10) which ensures smooth entry and alignment of mounting faces and bolt axis of the motor mounting brackets (300F,300S) with the mounting brackets (204L and 204R) on the sub-frame structure (200A). Further, the motor mounting brackets (300F, 300S) define a predetermined profile opposite to the mounting face such that the predetermined profile facilitates easy assembly of the motor mounting brackets (300F, 300S) to the front cross member (201). In an embodiment, the predetermined profile is a slot extending on both sides of the L-shaped motor mounting brackets (300F and 300S).
[046] A method (600) for assembling a motor (400) on a sub-frame assembly (200) comprising a front cross member (201), a rear cross member (202) disposed parallel to the front cross member (201), a left longitudinal member 203L) and a right longitudinal member (203R) each connected transversely with the front cross member (201) and the rear cross member (202). The method (600) includes mounting at least two mounting brackets (204L, 204R) on the front cross member (201) at predetermined positions. In an embodiment, a first mounting bracket (204L) is mounted on the front cross member (201) at a left side, and a second mounting bracket (204R) is mounted on the front cross member (201) at a right side. The method (600) further includes providing a third motor mounting portion (205) at a rear side (when viewed in the vehicle lengthwise direction) of the sub-frame assembly (200), wherein a rear insulator bush (205A) is inserted in a slot defined in the third motor mounting portion (205). In an embodiment, the third motor mounting portion (205) is connected to the rear cross member (202) at a predetermined position. Furthermore, the method (600) includes assembling at least two motor mounting brackets (300F, 300S) on the motor (400) at predetermined positions, wherein the motor mounting brackets (300F, 300S) comprise an L-shaped body (300A) with an insulator bush (300B) inserted into the body (300A). In an embodiment, a first mounting bracket (300F) is mounted on a corresponding receiving portion on a left side of the motor (400) and a second mounting bracket (300S) is mounted on a corresponding receiving portion on a right side of the motor (400). The method (600) also includes connecting a rear motor mounting bracket (500) with a corresponding receiving portion at the rear side of the motor (400). The method (600) further includes aligning the motor (400) with the sub-frame assembly (200) such that the two motor mounting brackets (300F, 300S) rest on the corresponding mounting brackets (204L, 204R) on the sub-frame structure (200A) and the rear motor mounting bracket (500) aligns with the rear insulator bush (205A) of the rear mounting portion (205), and a bolting axis of the motor mounting brackets (300) align with a bolting axis of the corresponding mounting bracket (204L, 204R). In an embodiment, the motor mounting brackets (300) are guided into place by a horizontal face and vertical face of the mounting brackets (204L, 204R) of the sub-frame assembly (200). Additionally, the method (600) includes fastening the motor mounting brackets (300F, 300S) to the corresponding mounting brackets (204L, 204R) on the sub-frame structure (200A) through a fastening means such as a bolt. In an embodiment, the motor (400) is aligned and assembled onto the sub-frame assembly (200) by manually lowering the motor (400).
[047] The technical advantages achieved by the embodiments disclosed herein include providing the sub-frame assembly in which mounting brackets provided on the sub-frame for ease of assembling motor onto the sub-frame structure, facilitate ease of serviceability of motor and the sub-frame components due to removal and re-fitment of the motor using simple mounting brackets, lowers the cost of motor assembly as compared to costly robotics and automated line set up by enabling manual assembly with precision while using semi-skilled personnel, low service cost to the customer in the event of insulator bush failure as only low-cost aluminum brackets and bush need to be replaced instead of replacing the entire rear sub frame, No damage to the rear sub frame is caused during replacement and refitment of the bush unlike press-fit concept, and low-cost assembly fixtures for assembling rear motor onto the sub-frame.
[048] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. 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 embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

LIST OF REFERENCE NUMERALS
100 CONVENTIONAL SUBFRAME
101 FRONT CROSS MEMBER
102 REAR CROSS MEMBER
103L LEFT SIDE LONGITUDINAL MEMBER
103R RIGHT SIDE LONGITUDINAL MEMBER
104L, 104R SLEEVES
105 REAR MOTOR MOUNITNG SLOT
106L, 106R INSULATER BUSHES
200 SUBFRAME ASSEMBLY
200A SUBFRAME STRUCTURE
201 FRONT CROSS MEMBER
202 REAR CROSS MEMBER
203L LEFT SIDE LONGITUDINAL MEMBER
203R RIGHT SIDE LONGITUDINAL MEMBER
204L LEFT SIDE/FIRST MOUNTING BRACKET
204R RIGHT SIDE/ SECOND MOUNTING BRACKET
204A ENTRY CHAMFER
205 REAR MOUNTING PORTION/ THIRD MOTOR MOUNITNG POINT
205A REAR INSULATOR BUSH
206A, 206B FRONT UPPER LINK MOUNTING BRACKETS
206C FRONT LOWER LINK MOUNITNG BRACKET
207A, 207B REAR UPPER LINK MOUNITNG MEMBER
208 BUSH SLEEVES
208A SUBFRAME MOUNITNG INSULATER BUSHES
209 LOWER CONTROL ARM MOUNTING
210 TOE LINK MOUNTING
300F FIRST MOTOR MOUNTING BRACKET
300S SECOND MOTOR MOUNTING BRACKET
300A BODY OF MOTOR MOUNTING BRACKET
300B INSULATOR BUSH
400 MOTOR
500 REAR MOTOR MOUNTING BRACKET

, Claims:We claim,
1. A sub-frame assembly (200) for an electric vehicle, said subframe assembly (200) comprising: a sub-frame structure (200A) having a front cross member (201), a rear cross member (202), a left longitudinal member (203L) and a right longitudinal member (203R) connected transversely with the front cross member (201) and the rear cross member (202);
at least two motor mounting brackets (300F,300S), wherein each of the motor mounting bracket (300F,300S) defines a slot in a body (300A) of the motor mounting bracket (300F,300S) to receive an insulator bush (300B);
at least two mounting brackets (204L, 204R) attached to the front cross member (201) of the sub-frame structure (200A), wherein the mounting brackets (204L, 204R) are adapted to receive and guide a corresponding motor mounting bracket (300F, 300S) for mounting on the sub-frame structure (200A); and
at least one rear mounting portion (205), the rear mounting portion (205) adapted to receive a rear insulator bush (205A) through a slot defined in the rear mounting portion (205).

2. The sub-frame assembly (200) as claimed in claim 1, wherein,
each of the mounting bracket (204L, 204R) comprises a horizontal face, and vertical face extending transversely from the horizontal face;
the mounting bracket (204L, 204R) is attached to the front cross member (201) such that the horizontal face of the mounting bracket (204L, 204R) is parallel to a plane of the front cross member (201); and
each of the motor mounting bracket (300F, 300S) comprises of an inverted L-shaped body (300A), wherein a shorter portion of the L-shaped body (300A) is adapted to rest on the horizontal face of the corresponding mounting brackets (204L, 204R) and a longer portion of the L-shaped body (300A) is adapted to rest on the vertical face of the corresponding mounting brackets (204L, 204R),
wherein, each of the motor mounting bracket (300F, 300S) is adapted to be pre-assembled on a corresponding receiving portion of a motor (400) at pre-determined positions.

3. The sub-frame assembly (200) as claimed in claim 1, wherein the mounting brackets (204L, 204R) are adapted to bear a load of the motor (400), when the motor (400) is being mounted on the sub-frame structure (200A) through the motor mounting brackets (300F, 300S).

4. The sub-frame assembly (200) as claimed in claim 1, wherein the sub-frame assembly (200) includes a rear motor mounting bracket (500) adapted to be pre-assembled at a rear side of the motor (400) through a corresponding receiving portion of the motor (400), wherein the rear motor mounting bracket (500) is adapted to receive a face of the rear insulator bush (205A) inserted into the rear mounting portion (205).

5. The sub-frame assembly (200) as claimed in claim 1, wherein the sub-frame assembly (200) comprises:
said mounting bracket (204L) mounted towards a left side of the front cross member (201), and said mounting bracket (204R) mounted towards a right side of the front cross member (201); and
said at least two motor mounting brackets (300F, 300S) are a first motor mounting bracket (300F) connected to a corresponding receiving portion provided on a left side of the motor (400), and a second motor mounting bracket (300S) connected to its corresponding receiving portion provided on a right side of the motor (400).

6. The sub-frame assembly (200) as claimed in claim 1, wherein the insulator bush (300B) is inserted into the slot defined in the motor mounting bracket (300) before the motor mounting bracket (300) is pre-assembled onto the motor (400).

7. The sub-frame assembly (200) as claimed in claim 1, wherein each of the motor mounting bracket (300F, 300S) is fastened to the corresponding mounting bracket (204L, 204R) on the sub-frame structure (200A) through a fastening.

8. The sub-frame assembly (200) as claimed in claim 1, wherein each of the mounting bracket (204L, 204R) has an entry chamfer (204A) to allow entry of a mounting face and bolting axis of the corresponding motor mounting brackets (300F, 300S).

9. The sub-frame assembly (200) as claimed in claim 1, wherein the mounting brackets (204L, 204R) are made of a material comprising aluminum.

10. A method (600) for assembling a motor (400) on a sub-frame assembly (200), said method (600) comprising:
mounting at least two mounting brackets (204L, 204R) on a front cross member (201) at predetermined positions;
providing a rear mounting portion (205) at a rear side of a sub-frame structure (200A) at a predetermined position;
assembling at least two motor mounting brackets (300F, 300S) on a motor (400) at predetermined positions;
connecting a rear motor mounting bracket (500) with a corresponding receiving portion provided at a rear side of the motor (400);
aligning the motor (400) with the sub-frame (200) for making the two motor mounting brackets (300F, 300S) rest on the corresponding mounting brackets (204L, 204R) on the sub-frame structure (200A) and the rear motor mounting bracket (500) aligns with the rear insulator bush (205A) of the rear mounting portion (205), and a bolting axis of the motor mounting brackets (300F, 300S) align with a bolting axis of the corresponding mounting bracket (204L, 204R); and
fastening the motor mounting brackets (300F, 300S) to the corresponding mounting brackets (204L, 204R) on the sub-frame structure (200A).