Description:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
SWINGARM ASSEMBLY INTEGRATED WITH MOTOR AND TRANSMISSION ASSEMBLY

Applicant:
River Mobility Private Limited
A company based in India,
Having its address as:
No. 25/3, KIADB EPIP Zone, Seetharampalya, Hoodi Road, Mahadevapura, Whitefield, Bengaluru, Karnataka, India- 560048

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

PRIORITY INFORMATION
[001] The present application does not claim priority from any other application.
FIELD OF INVENTION
[002] The present invention generally relates to a swingarm assembly. More specifically, the present invention is related to a swingarm assembly integrated with motor and drivetrain.
BACKGROUND OF THE INVENTION
[003] The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology.
[004] A swingarm is used for connecting a rear wheel to a frame of a 2-wheeled vehicle. The swingarm allows vertical movement of the rear wheel, which provides better stability and control to the vehicle during acceleration, deceleration, and cornering. There exist different conventional mechanisms for mounting components on the swingarms.
[005] Some conventional arrangements utilize swingarm mounted motor-transmission assembly. Such conventional arrangements majorly utilize motors mounted within circumference of rear wheels. The motors are arranged in two layouts. A first layout includes installation of the hub motor without offset i.e. using the hub motor integrated with a wheel rim or using the hub motor with a planetary gear train system. A second layout includes installation of the motor with offset i.e. mounting the motor at an offset within a wheel circumference and coupling an input shaft with a wheel output shaft using a drivetrain system.
[006] There are several limitations associated with usage of the hub motors. One such limitation is related to its packaging and power sizing. Specifically, the hub motors installed with wheel rims are able to deliver less power because their power is constrained by size of the wheel rims. To increase the power capacity, size of the wheel rims is often required to be increased, and the increase in size of the wheel rims increases overall weight of unsprung mass. With offset type hub motors, size of the motor is constrained by the packaging i.e. space available on one side of the vehicle. Wheel rim offset is changed to package an offset type hub motor along with a gearbox and rear brake assembly in any vehicle.
[007] Another limitation associated with usage of the hub motors is thermal issues. As the hub motors are mounted within wheel rims, only natural cooling is available. Due to limited temperature drop gained from natural cooling, the hub motors operate at higher temperatures, which causes reduction in performance and efficiency of the hub motors. Similarly, for the offset type hub motors, proper cooling strategy is required to be designed to avoid thermal issues.
[008] Yet another limitation associated with usage of the hub motors is higher structural and shock loads. All road loads and shock loads get transferred to the hub motor through the rims. Therefore, motor mounting is to be made rigid to withstand the loads without undergoing any permanent deformation. Similarly, the offset type hub motors also have to withstand the shock loads, although the shock loads are slightly lesser. Internal components and casing mounting of the offset type hub motors are required to be designed to withstand such loads.
[009] Yet another limitation associated with usage of the hub motors is weight distribution and higher unsprung mass. Higher unsprung mass and rearward weight distribution is not desirable in terms of vehicle comfort and handling.
[0010] Some other conventional arrangements utilize chassis mounted motor-transmission assembly. In such conventional arrangements, the motor is mounted on a chassis as a sprung mass member. Driving force is transferred to a rear wheel through multi-stage or single-stage reduction drivetrains, based on the torque requirement of the rear wheel.
[0011] A limitation associated with usage of the chassis mounted motors is longer center distance drives. As the motor is mounted away from the rear wheel, longer center distance drives are required to be used. Tension variations arise in a belt or chain drive during up-down movement of the swingarm. Such tension variations affect Noise, Vibration, and Harshness (NVH) attributes of a vehicle.
[0012] Another limitation associated with usage of the chassis mounted motors is increased vehicle Center of Gravity (CG) height. Because a chassis mounted motor is mounted above a swingarm pivot point, the CG of the vehicle moves up. Such shifted CG usually affects maneuverability of the vehicle.
[0013] In view of the above mentioned shortcomings, there arises a need for a mechanism for mounting of motors and other necessary components in a vehicle using which the above mentioned limitations could be overcome.
OBJECTS OF THE INVENTION
[0014] A general objective of the invention is to provide a swingarm assembly which improves the center of gravity of a vehicle and thus improves the vehicle’s comfort and handling characteristics.
[0015] Another objective of the invention is to provide a swingarm assembly which offers uniform transfer of external forces to the chassis/frame of the vehicle.
[0016] Yet another objective of the invention is to provide a swingarm assembly which offers installation of a traction motor and drivetrain assembly on the vehicle. Relative motion from the ground to the wheel is inevitable which will cause the chassis to move relatively with suspension and swingarm bush as mount. By integrating the motor and drivetrain both the systems are isolated from such relative motion that are otherwise detrimental to durability and performance of the systems.
[0017] Yet another objective of the invention is to provide a swingarm assembly which allows a traction motor to deliver high power with lesser center distance between transmission components thereby minimising loss and increasing durability of the system.
SUMMARY OF THE INVENTION
[0018] This summary is provided to introduce aspects related to a swingarm assembly for a vehicle, and the aspects are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
[0019] In one embodiment, the swingarm assembly comprises a right swingarm, a left swingarm, and a traction motor positioned between the right swingarm and the left swingarm. The swingarm assembly further comprises a transmission assembly comprising power transferring elements enclosed within a housing. The housing is a recessed portion provided in at least one of the right swingarm and the left swingarm.
[0020] In one aspect, the power transferring elements include one of a chain drive, a belt and pulley drive, or a gearbox.
[0021] In one aspect, the gearbox comprises a plurality of gears selected from a driving gear and a driven gear.
[0022] In one aspect, the driving gear and the driven gear are coupled to each other and an endless transmission drive unit for transmitting driving force from the traction motor to a rear wheel. The endless transmission drive unit is one of a chain drive and a belt drive.
[0023] In one aspect, the swingarm assembly further comprises a transmission cover adapted to cover the transmission assembly enclosed within the housing.
[0024] In one aspect, an input shaft/hub of the transmission assembly is connected to the shaft of the traction motor and an output shaft/hub of the transmission assembly is in constant mesh with the input shaft/hub of the transmission assembly or an endless transmission drive unit.
[0025] In one aspect, the transmission assembly and the endless transmission drive unit are mounted towards a face of the traction motor, and together act as a two-stage speed reduction drivetrain assembly.
[0026] In one aspect, the transmission assembly acts as a primary speed reduction drive and the endless transmission drive unit acts as a secondary speed reduction drive.
[0027] In one aspect, the traction motor acting as a structural intermediate part is mounted between front ends of the right swingarm and the left swingarm, and is positioned closer to pivot points of the right swingarm and the left swingarm.
[0028] In one aspect, the traction motor forming the structural intermediate part is supported at the pivot points of the right swingarm and the left swingarm using sleeves, and press fitted silent block bushes are provided at both sides of the right swingarm and the left swingarm.
[0029] In one aspect, the silent block bushes dampen at least one of road loads, shock loads, and vibrations arising from the traction motor.
[0030] In one aspect, the traction motor forming the structural intermediate part is positioned or supported at the pivot points of the right swingarm and the left swingarm using motor mounts provided on the motor housing and bolted joints provided on either sides of the right swingarm and the left swingarm.
[0031] In one aspect, the endless transmission drive unit comprises one or more sprockets selected from a driving sprocket and a driven sprocket.
[0032] In one aspect, the output shaft of the transmission assembly is connected to the driving sprocket towards the face of the traction motor via a spline shaft connection.
[0033] In one aspect, the driven sprocket is connected to a rear wheel rim using bolted joints.
[0034] In one aspect, the transmission assembly comprises oil seals to prevent leakage of a lubricant used for the driving gear and the driven gear.
[0035] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The accompanying drawings constitute a part of the description and are used to provide a further understanding of the present invention.
[0037] Fig. 1a illustrates a left side view and Fig. 1b illustrates a right side view of a swingarm assembly mounted on a rear wheel of a vehicle, in accordance with an embodiment of the present invention.
[0038] Fig. 2 illustrates a left side view of the swingarm assembly integrated with a chassis of the vehicle, in accordance with an embodiment of the present invention.
[0039] Fig. 3a illustrates a front view of a left swingarm, in accordance with an embodiment of the present invention.
[0040] Fig. 3b illustrates a rear view of the left swingarm, in accordance with an embodiment of the present invention.
[0041] Fig. 4 illustrates a perspective front view of the swingarm assembly present in a disassembled condition, in accordance with an embodiment of the present invention.
[0042] Fig. 5 illustrates a perspective front view of the swingarm assembly present in an assembled condition, in accordance with an embodiment of the present invention.
[0043] Fig. 6 illustrates a perspective rear view of the swingarm assembly present in an assembled condition, in accordance with an embodiment of the present invention.
[0044] Fig. 7 illustrates an exploded view of the swingarm assembly, in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0045] The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. Each embodiment described in this disclosure is provided merely as an example or illustration of the present invention, and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
[0046] The present invention pertains to a swingarm assembly 100 for a vehicle. Fig. 1a illustrates a left side view and Fig. 1b illustrates a right side view of the swingarm assembly 100 mounted on a rear wheel 102 of the vehicle, in accordance with an embodiment of the present invention. Fig. 2 illustrates a left side view of the swingarm assembly 100 integrated with a rear end of a chassis 104 i.e. a main frame of the vehicle, in accordance with an embodiment of the present invention. Specifically, the swingarm assembly 100 may be integrated with the chassis 104 through a suspension 106 i.e. a shock absorber. Similarly, another suspension may be used for integrating the swingarm assembly 100 with the chassis 104 on the other side.
[0047] The swingarm assembly 100 comprises a left swingarm 302 and a right swingarm 304. The left swingarm 302 and the right swingarm 304 may be made of a strong and light material, such as aluminium. Fig. 3a illustrates a front view of the left swingarm 302 and Fig. 3b illustrates a rear view of the left swingarm 302, in accordance with an embodiment of the present invention. On the front side, the left swingarm 302 may comprise a housing 306 for enclosing one or more elements described successively with reference to Fig. 7.
[0048] Fig. 4 illustrates a perspective front view of the swingarm assembly 100 present in a disassembled condition, in accordance with an embodiment of the present invention. Figs. 5 and 6 illustrate perspective front and rear views of the swingarm assembly 100 present in an assembled condition, in accordance with an embodiment of the present invention.
[0049] Inner sides of the right swingarm 304 and the left swingarm 302 are designed to accommodate a traction motor 402 between them. The traction motor 402 acts as a structural intermediate part and is mounted between front ends of the right swingarm 304 and the left swingarm 302. The traction motor 402 may be positioned closer to pivot points 404 present on the right swingarm 304 and the left swingarm 302.
[0050] In one implementation, the traction motor 402 may be supported at the pivot points 404 of the right swingarm 304 and the left swingarm 302 using sleeves 602. The sleeves 602 with press fitted silent block bushes 700 (illustrated in Fig. 7) i.e. rubber bushings are provided at both sides of the right swingarm 304 and the left swingarm 302. The silent block bushes would dampen road loads, shock loads, and vibrations arising from the traction motor 402.
[0051] In another implementation, the traction motor 402 may be supported at the pivot points 404 of the right swingarm 304 and the left swingarm 302 using motor mounts provided on motor housing and bolted joints provided on either sides of the right swingarm 304 and the left swingarm 302.
[0052] Referring again to Fig. 5, the swingarm assembly 100 further comprises a transmission assembly 502. The transmission assembly 502 may be fixed on any of the right swingarm 304 and the left swingarm 302. The transmission assembly 502 may be covered by a transmission cover. The transmission cover may be present on an external side of any of the right swingarm 304 and the left swingarm 302. In one implementation, as shown in Fig. 5, the transmission assembly 502 and the transmission cover may be present on the external side of the left swingarm 302.
[0053] Fig. 7 illustrates an exploded view of the swingarm assembly 100, in accordance with an embodiment of the present invention. The transmission assembly 502 may comprise power transferring elements enclosed within a housing 306 i.e. a recessed portion provided in at least one of the right swingarm 304 and the left swingarm 302. The power transferring elements may include a chain drive, a belt and pulley drive, or a gearbox. The gearbox may comprise a plurality of gears, such as a driving gear 704 and a driven gear 706. The gearbox may be covered using a gearbox cover 702 to prevent ingress of contaminants like dirt and water into the gearbox.
[0054] The driving gear 704 and the driven gear 706 may be coupled to each other and an endless transmission drive unit 708. The endless transmission drive unit 708 comprises one or more sprockets, such as a driving sprocket 710 and a driven sprocket 712. The endless transmission drive unit 708 may allow transmission of driving force from the traction motor 402 to the rear wheel 208. The endless transmission drive unit 708 may be a chain drive or a belt drive.
[0055] An input shaft/hub of the transmission assembly 502 i.e. the driving gear 704 may be connected to the shaft/hub of the traction motor 402. Further, an output shaft of the transmission assembly 502 i.e. the driven gear 706 may be in constant mesh with the input shaft/hub i.e. the driving gear 704 of the transmission assembly 502 or an endless transmission drive unit 708.
[0056] As visible in Figs. 5 through 7, the transmission assembly 502 and the endless transmission drive unit 708 are mounted towards the face of the traction motor 402. The transmission assembly 502 and the endless transmission drive unit 708 may together act as a two-stage speed reduction drivetrain assembly. Specifically, the transmission assembly 502 acts as a primary speed reduction drive and the endless transmission drive unit 708 acts as a secondary speed reduction drive.
[0057] The output shaft of the transmission assembly i.e. the driven gear 706 is connected to the driving sprocket 710 towards a face of the traction motor 402 via a spline shaft connection. The driven sprocket 712 may be connected to a rear wheel rim 714 using bolted joints.
[0058] The transmission assembly 502 may further comprise one or more oil seals 716 to prevent leakage of a lubricant used for the driving gear 704 and the driven gear 706.
[0059] The swingarm assembly described above offers several technical advantages. A few such technical advantages are mentioned henceforth.
[0060] Although the traction motor is mounted on the swingarm as an unsprung mass, the traction motor is located closer to the pivot points of the swingarm. Because of such positioning, the entire weight of the traction motor will not act as unsprung mass, and the vehicle’s comfort and handling characteristics get improved.
[0061] The weight of the traction motor gets concentrated near the Center of Gravity (CG) of the vehicle which helps in weight distribution of the vehicle, hence improves dynamics of the vehicle. The traction motor could also be mounted closer to ground i.e. below the pivot points to further reduce the CG of the vehicle.
[0062] Vertical movement of the swingarm assembly due to road irregularities will impart less shock loads and vibration loads on the traction motor as the traction motor is mounted closer to the pivot point and thus less displacement of the traction motor occurs along a vertical axis.
[0063] Because the traction motor is coupled with the chassis i.e. the main frame using rubber bushing press fitted into swingarm eyes, vibrations arising due to dynamics of the traction motor get reduced. Further, NVH characteristics are improved and transfer of vibrations to driver’s tactile points such as foot rest, floor board, seat, and handlebar is reduced.
[0064] As different suspensions can be used on each side of the swingarm assembly, forces acting on the vehicle are distributed uniformly to its main frame.
[0065] A gearbox assembly integrated with the swingarm can be used with traction motors having different form and power factors by keeping the same architecture. This allows scaling up and evolution of similar variants of the architecture.
[0066] Although implementations of the swingarm assembly have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features or methods are disclosed as examples of implementations of the swingarm assembly.
, Claims:We Claim:
1. A swingarm assembly (100) for a vehicle, comprising:
a right swingarm (304);
a left swingarm (302);
a traction motor (402) positioned between the right swingarm (304) and the left swingarm (302); and
a transmission assembly (502) comprising power transferring elements enclosed within a housing (306), wherein the housing (306) is a recessed portion provided in at least one of the right swingarm (304) and the left swingarm (302).
2. The swingarm assembly (100) as claimed in claim 1, wherein the power transferring elements include one of a chain drive, a belt and pulley drive, or a gearbox.
3. The swingarm assembly as claimed in claim 2, wherein the gearbox comprises a plurality of gears, the plurality of gears are selected from a driving gear (704) and a driven gear (706).
4. The swingarm assembly (100) as claimed in claim 3, wherein the driving gear (704) and the driven gear (706) are coupled to each other and an endless transmission drive unit (708) for transmitting driving force from the traction motor (402) to a rear wheel.
5. The swingarm assembly (100) as claimed in claim 1, further comprises a transmission cover adapted to cover the transmission assembly (502) enclosed within the housing (306).
6. The swingarm assembly (100) as claimed in claim 4, wherein the endless transmission drive unit (708) is one of a chain drive and a belt drive.
7. The swingarm assembly (100) as claimed in claim 1, wherein an input shaft/hub of the transmission assembly (502) is connected to a shaft/hub of the traction motor (402), and an output shaft of the transmission assembly (502) is in constant mesh with the input shaft/hub of the transmission assembly (502) or an endless transmission drive unit (708).
8. The swingarm assembly (100) as claimed in claims 1 and 6, wherein the transmission assembly (502) and the endless transmission drive unit (708) are mounted towards a face of the traction motor (402), and together act as a two-stage speed reduction drivetrain assembly.
9. The swingarm assembly (100) as claimed in claim 8, wherein the transmission assembly (502) acts as a primary speed reduction drive and the endless transmission drive unit (708) acts as a secondary speed reduction drive.
10. The swingarm assembly (100) as claimed in claim 1, wherein the traction motor (402) acting as a structural intermediate part is mounted between front ends of the right swingarm (304) and the left swingarm (302), and is positioned closer to pivot points (404) of the right swingarm (304) and the left swingarm (302).
11. The swingarm assembly (100) as claimed in claim 1, wherein the traction motor (402) forming the structural intermediate part is supported at the pivot points (404) of the right swingarm (304) and the left swingarm (302) using sleeves (602), and press fitted silent block bushes are provided at both sides of the right swingarm (304) and the left swingarm (302).
12. The swingarm assembly (100) as claimed in claim 11, wherein the silent block bushes dampen at least one of road loads, shock loads, and vibrations arising from the traction motor (402).
13. The swingarm assembly (100) as claimed in claim 10, wherein the traction motor (402) forming the structural intermediate part is positioned or supported at the pivot points (404) of the right swingarm (304) and the left swingarm (302) using motor mounts provided on the motor housing and bolted joints provided on either sides of the right swingarm (304) and the left swingarm (302).
14. The swingarm assembly (100) as claimed in claim 6, wherein the endless transmission drive unit (708) comprises one or more sprockets, the one or more sprockets are selected from a driving sprocket (710) and a driven sprocket (712).
15. The swingarm assembly (100) as claimed in claim 14, wherein the output shaft of the transmission assembly (502) is connected to the driving sprocket (710) towards a face of the traction motor (402) via a spline shaft connection.
16. The swingarm assembly (100) as claimed in claim 14, wherein the driven sprocket (712) is connected to a rear wheel rim (714) using bolted joints.
17. The swingarm assembly (100) as claimed in claim 1, wherein the transmission assembly (502) comprises oil seals (716) to prevent leakage of a lubricant used for the driving gear (704) and the driven gear (706).