Description:FIELD OF THE INVENTION

[1] The present disclosure generally relates to a saddle-type vehicle. More particularly, the present disclosure relates to a transmission system of a saddle-type vehicle.

BACKGROUND

[2] The transmission system in a saddle-type vehicle, for example an electric vehicle (EV) scooter, includes a gearbox which produces different rotation ratio between a drive motor and drive wheels during running of the EV scooter. The EV scooter consists of a swingarm that connects the rear wheel of the scooter to the frame and allows the wheel to move up and down, absorbing shocks and bumps from the road. Typically, the EV scooter swingarm includes the transmission system or power train which includes the gearbox connected to the drive motor.

[3] Often, it is required to change or modify the gearbox. However, in existing designs in order to change or modify the gearbox, the design of the swingarm or motor needs to be changed or modified as they are interconnected. There is a need to make the gearbox and the drive motor independent of each other without affecting the desired function of each component, so that each of the component can be changed or modified separately.

[4] In prior arts that disclose separate motor and gearbox, in such designs, the lateral stack for the powertrain increases which moves the center of gravity outward in the EV two-wheeler. Further, a separate casing for motor and gearbox requires additional nuts and bolts to mount the gearbox and motor, which increases machining and the mass of the assembly.

SUMMARY

[5] This summary is provided to introduce a selection of concepts, in a simplified format, that is further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.

[6] The main objective of the present disclosure is to disclose a transmission system wherein the gearbox and the drive motor are independent of each other.

[7] Accordingly, a transmission system for a saddle-type vehicle includes a motor compartment. The motor compartment includes a motor casing region and a gearbox casing region. The transmission system includes a motor. The motor includes a hollow output shaft, disposed entirely within the motor casing region, wherein the hollow output shaft comprises a plurality of internal splines. The transmission system includes a gearbox compartment and a gearbox disposed partially within the gearbox compartment. The gearbox includes a solid input shaft comprising a plurality of external splines, wherein the solid input shaft is coupled to the hollow output shaft such that the plurality of external splines of the solid input shaft is engaged to the plurality of internal splines of the hollow output shaft.

[8] To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[9] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[10] Figure 1 illustrates a perspective side view of a saddle-type vehicle;

[11] Figure 2A illustrates a sectional view of a transmission system in a saddle-type vehicle, according to an embodiment of the present disclosure;

[12] Figure 2B illustrates a sectional view of a motor compartment in the transmission system, according to an embodiment of the present disclosure;

[13] Figure 2C illustrates a perspective view of a swingarm assembly having the transmission system, according to an embodiment of the present disclosure;

[14] Figure 2D illustrates an exploded view of a swingarm assembly, according to an embodiment of the present disclosure;

[15] Figure 2E illustrates a sectional view of a transmission system in a saddle-type vehicle, according to an embodiment of the present disclosure; and

[16] Figure 2F illustrates a perspective view of the transmission system, according to an embodiment of the present disclosure.

[17] Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of vehicle, one or more components of the vehicle may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

DETAILED DESCRIPTION OF FIGURES

[18] For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the various embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.

[19] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the present disclosure and are not intended to be restrictive thereof.

[20] Whether or not a certain feature or element was limited to being used only once, it may still be referred to as “one or more features” or “one or more elements” or “at least one feature” or “at least one element.” Furthermore, the use of the terms “one or more” or “at least one” feature or element do not preclude there being none of that feature or element, unless otherwise specified by limiting language including, but not limited to, “there needs to be one or more…” or “one or more elements is required.”

[21] Reference is made herein to some “embodiments.” It should be understood that an embodiment is an example of a possible implementation of any features and/or elements of the present disclosure. Some embodiments have been described for the purpose of explaining one or more of the potential ways in which the specific features and/or elements of the proposed disclosure fulfil the requirements of uniqueness, utility, and non-obviousness.

[22] Use of the phrases and/or terms including, but not limited to, “a first embodiment,” “a further embodiment,” “an alternate embodiment,” “one embodiment,” “an embodiment,” “multiple embodiments,” “some embodiments,” “other embodiments,” “further embodiment”, “furthermore embodiment”, “additional embodiment” or other variants thereof do not necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and/or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and/or elements may be described herein in the context of only a single embodiment, or in the context of more than one embodiment, or in the context of all embodiments, the features and/or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and/or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.

[23] Any particular and all details set forth herein are used in the context of some embodiments and therefore should not necessarily be taken as limiting factors to the proposed disclosure.

[24] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by “comprises... a” does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

[25] Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.

[26] For the sake of clarity, the first digit of a reference numeral of each component of the present disclosure is indicative of the Figure number, in which the corresponding component is shown. For example, reference numerals starting with digit “1” are shown at least in Figure 1. Similarly, reference numerals starting with digit “2” are shown at least in Figure 2.

[27] An Electric Vehicle (EV) or a battery powered vehicle including, and not limited to two-wheelers such as scooters, mopeds, motorbikes/motorcycles; three-wheelers such as auto-rickshaws, four-wheelers such as cars and other Light Commercial Vehicles (LCVs) and Heavy Commercial Vehicles (HCVs) primarily work on the principle of driving an electric motor using the power from the batteries provided in the EV. Furthermore, the electric vehicle may have at least one wheel which is electrically powered to traverse such a vehicle. The term ‘wheel’ may be referred to any ground-engaging member which allows traversal of the electric vehicle over a path. The types of EVs include Battery Electric Vehicle (BEV), Hybrid Electric Vehicle (HEV) and Range Extended Electric Vehicle. However, the subsequent paragraphs pertain to the different elements of a Battery Electric Vehicle (BEV).

[28] In construction, as illustrated in Figure 1, an EV (10) typically comprises a battery or battery pack (12) enclosed within a battery casing and includes a Battery Management System (BMS), an on-board charger (14), a Motor Controller Unit (MCU), an electric motor (16) and a transmission system (18). The primary function of the above-mentioned elements is detailed in the subsequent paragraphs: The battery of an EV (10) (also known as Electric Vehicle Battery (EVB) or traction battery) is re-chargeable in nature and is the primary source of energy required for the operation of the EV, wherein the battery (12) is typically charged using the electric current taken from the grid through a charging infrastructure (20). The battery may be charged using Alternating Current (AC) or Direct Current (DC), wherein in case of AC input, the on-board charger (14) converts the AC signal to DC signal after which the DC signal is transmitted to the battery via the BMS. However, in case of DC charging, the on-board charger (14) is bypassed, and the current is transmitted directly to the battery via the BMS.

[29] The battery (12) is made up of a plurality of cells which are grouped into a plurality of modules in a manner in which the temperature difference between the cells does not exceed 5 degrees Celsius. The terms “battery”, “cell”, and “battery cell” may be used interchangeably and may refer to any of a variety of different rechargeable cell compositions and configurations including, but not limited to, lithium-ion (e.g., lithium iron phosphate, lithium cobalt oxide, other lithium metal oxides, etc.), lithium-ion polymer, nickel metal hydride, nickel cadmium, nickel hydrogen, nickel-zinc, silver zinc, or other battery type/configuration. The term “battery pack” as used herein may be referred to multiple individual batteries enclosed within a single structure or multi-piece structure. The individual batteries may be electrically interconnected to achieve a desired voltage and capacity for a desired application. The Battery Management System (BMS) is an electronic system whose primary function is to ensure that the battery (12) is operating safely and efficiently. The BMS continuously monitors different parameters of the battery such as temperature, voltage, current and so on, and communicates these parameters to the Electronic Control Unit (ECU) and the Motor Controller Unit (MCU) in the EV using a plurality of protocols including and not limited to Controller Area Network (CAN) bus protocol which facilitates the communication between the ECU/MCU and other peripheral elements of the EV (10) without the requirement of a host computer.

[30] The MCU primarily controls/regulates the operation of the electric motor based on the signal transmitted from the vehicle battery, wherein the primary functions of the MCU include starting of the electric motor (16), stopping the electric motor (16), controlling the speed of the electric motor (16), enabling the vehicle to move in the reverse direction and protect the electric motor (16) from premature wear and tear. The primary function of the electric motor (16) is to convert electrical energy into mechanical energy, wherein the converted mechanical energy is subsequently transferred to the transmission system of the EV to facilitate movement of the EV. Additionally, the electric motor (16) also acts as a generator during regenerative braking (i.e., kinetic energy generated during vehicle braking/deceleration is converted into potential energy and stored in the battery of the EV). The types of motors generally employed in EVs include, but are not limited to DC series motor, Brushless DC motor (also known as BLDC motors), Permanent Magnet Synchronous Motor (PMSM), Three Phase AC Induction Motors and Switched Reluctance Motors (SRM).

[31] The transmission system (18) of the EV (10) facilitates the transfer of the generated mechanical energy by the electric motor (16) to the wheels (22a,22b) of the EV. Generally, the transmission systems (18) used in EVs include single speed transmission system and multi-speed (i.e., two-speed) transmission system, wherein the single speed transmission system comprises a single gear pair whereby the EV is maintained at a constant speed. However, the multi-speed/two-speed transmission system comprises a compound planetary gear system with a double pinion planetary gear set and a single pinion planetary gear set thereby resulting in two different gear ratios which facilitates higher torque and vehicle speed.

[32] In one embodiment, all data pertaining to the EV (10) and/or charging infrastructure (20) are collected and processed using a remote server (known as cloud) (24), wherein the processed data is indicated to the rider/driver of the EV (10) through a display unit present in the dashboard (26) of the EV (10). In an embodiment, the display unit may be an interactive display unit. In another embodiment, the display unit may be a non-interactive display unit.

[33] Embodiments of the present disclosure further discusses a modified transmission system (18).

[34] Figure 2A illustrates a sectional view of a transmission system (200) in the saddle-type vehicle (10), according to an embodiment of the present disclosure. The transmission system (200) includes a motor compartment (205) enclosing a motor (210). The motor (210) includes a hollow output shaft (215). The hollow output shaft (215) includes a plurality of internal splines.

[35] The transmission system (200) includes a gearbox compartment (220). The transmission system (200) includes a gearbox (225) disposed partially within the gearbox compartment (220). The gearbox (225) includes a solid input shaft (230) comprising a plurality of external splines. The solid input shaft (230) is coupled to the hollow output shaft (215) such that the plurality of external splines of the solid input shaft (230) is engaged to the plurality of internal splines of the hollow output shaft (215).

[36] In a first embodiment of the transmission system (200), the motor compartment (205) includes a motor casing region (205a) and a gearbox casing region (205b) as illustrated in Figure 2A and Figure 2B. It is to be noted that the gearbox casing region (205b) is integrated to the motor casing region (205a) and is a single cast unit. Further, the gearbox compartment (220) is detachably coupled to the gearbox casing region (205b).

[37] In the first embodiment, the solid input shaft (230), also referred to as the gearbox input shaft (230), extends through the gearbox casing region (205b) of the motor compartment (205) and is coupled to the hollow output shaft (215), also referred to as the hollow motor shaft (215).

[38] In the first embodiment, the transmission system (200) includes a plurality of first support bearings (235a) for supporting the hollow output shaft (215) within the motor casing region (205a). Further, the transmission system (200) includes a plurality of second support bearings (235b) disposed within the motor casing region (205a) for supporting the hollow output shaft (215), i.e., the hollow motor shaft (215). The plurality of second support bearings (235b) are sealed bearings. Alternately, instead of being disposed within the motor casing region (205a), the plurality of second support bearings (235b) may be disposed within the gearbox casing region (205b) for supporting the solid input shaft (230), i.e., the gearbox input shaft (230). The plurality of second support bearings (235b) are unsealed bearings when placed within the gearbox casing region (205b). Furthermore, the transmission system (200) includes a plurality of third support bearings (235c) for supporting the solid input shaft (230) within the gearbox compartment (220).

[39] It is to be noted that the hollow output shaft (215) is configured to be disposed entirely within the motor casing region (205a). There are various advantages of having the hollow output shaft (215) or the hollow motor shaft (215) within the motor compartment (205). The hollow output shaft (215) provides increased durability towards torsional loads. Further, by having the motor shaft (215) as a hollow shaft and the gearbox input shaft (230) as a solid shaft, it shifts the failure point from the motor (210) to the gearbox (225). This helps in reducing the cost of replacement and maintenance, as it is costly to repair and maintain the motor (210) than the gearbox (225).

[40] Further, the hollow motor shaft and the solid gearbox shaft increases the torsional stiffness of gear shaft. This reduces the torsional deflection, which in turn reduces transmission error in the pair of gears. This reduction in transmission error reduces the noise coming out from the powertrain.

[41] In a second embodiment of the transmission system (200), the motor casing region (205a) is detachably coupled to the gearbox casing region (205b), i.e., the motor casing region (205a) and the gearbox casing region (205b) are not integrated or a single cast unit, but they are separate regions. Further, in the second embodiment, the gearbox casing region (205b) is detachably coupled to the gearbox compartment (220). The motor casing region (205a), the gearbox casing region (205b), and the gearbox compartment (220) are illustrated in Figure 2F.

[42] In the second embodiment, the transmission system (200) includes a plurality of first support bearings (235a) for supporting the hollow output shaft (215) within the motor casing region (205a). Further, the transmission system (200) includes a plurality of second support bearings (235b) for supporting the hollow output shaft (215) within the motor casing region (205a). The plurality of second support bearings (235b) are sealed bearings for supporting the hollow output shaft (215) within the motor casing region (205a). The transmission system (200) includes a plurality of third support bearings (235c) for supporting the solid input shaft (230) within the gearbox compartment (220) as illustrated in Figure 2E. The transmission system (200) includes a plurality of fourth support bearings (235d) for supporting the solid input shaft (230) within the gearbox casing region (205b). The plurality of fourth support bearings (235d) are unsealed bearings for supporting the solid input shaft (230) within the gearbox casing region (205b).

[43] In another embodiment, the gearbox casing region (205b) and the gearbox compartment (220) are integrated as one single cast unit and is detachably coupled to the motor casing region (205a). The transmission system (200) includes a plurality of first support bearings (235a) for supporting the hollow output shaft (215) within the motor compartment (205). Further, the transmission system (200) includes a plurality of second support bearings (235b) for supporting the hollow output shaft (215) within the motor casing region (205a). The plurality of second support bearings (235b) are sealed bearings for supporting the hollow output shaft (215) within the motor casing region (205a). Further, the transmission system (200) includes a plurality of third support bearings (235c) for supporting the solid input shaft (230) within the gearbox compartment (220). Furthermore, the transmission system (200) includes a plurality of fourth support bearings (235d) for supporting the solid input shaft (230) within the gearbox casing region (205b). The plurality of fourth support bearings (235d) are unsealed bearings for supporting the solid input shaft (230) within the gearbox casing region (205b). By having the motor casing region (205a) and the gearbox casing region (205b) as detachably coupled, increases the serviceability of the motor (210) and the gearbox (225).

[44] In all of the above embodiments, the transmission system (200) includes a swingarm assembly (240). In all the embodiments, the motor compartment (205) is coupled to the swingarm assembly (240). Figure 2C illustrates a perspective view of the swingarm assembly (240) having the transmission system (200). It is to be noted that the swingarm assembly (240) is an assembly of structural arms (240a, 240b), the motor (210) and the gearbox (225) as illustrated in Figure 2D. Further, the swingarm assembly (240) is supported by the bottom shock mounts (245a, 245b).

[45] The transmission system (200) disclosed in the embodiments eliminate the need for at least one bolting junction. This reduces the machining. Further, eliminating at least a pair of nuts and bolts reduces the mass of the assembly. Furthermore, by having the hollow output shaft (215) of the motor (210) bounded within or disposed entirely within the motor casing (205a), increases the durability of the shaft without decreasing the shaft diameter. It is be noted that the transmission system (200) enables compact packaging of the powertrain in the swingarm with modularity.

[46] In this application, unless specifically stated otherwise, the use of the singular includes the plural and the use of “or” means “and/or.” Furthermore, use of the terms “including” or “having” is not limiting. Any range described herein will be understood to include the endpoints and all values between the endpoints. Features of the disclosed embodiments may be combined, rearranged, omitted, etc., within the scope of the invention to produce additional embodiments. Furthermore, certain features may sometimes be used to advantage without a corresponding use of other features.

[47] List of reference numerals:
Components Reference numerals
Transmission system 200
Saddle-type vehicle 10
Motor compartment 205
Motor 210
Hollow output shaft 215
Gearbox compartment 220
Gearbox 225
Solid input shaft 230
Motor casing region 205a
Gearbox casing region 205b
Plurality of first support bearings 235a
Plurality of second support bearings 235b
Plurality of third support bearings 235c
Plurality of fourth support bearings 235d
Swingarm assembly 240
, Claims:1. A transmission system (200) for a saddle-type vehicle (10), the transmission system (200) comprising:
a motor compartment (205) comprising a motor casing region (205a) and a gearbox casing region (205b);
a motor (210) comprising a hollow output shaft (215), disposed entirely
within the motor casing region (205a), wherein the hollow output shaft (215) comprises a plurality of internal splines;
a gearbox compartment (220); and
a gearbox (225) disposed partially within the gearbox compartment (220),
wherein the gearbox (225) comprises a solid input shaft (230) comprising a plurality of external splines, wherein the solid input shaft (230) is coupled to the hollow output shaft (215) such that the plurality of external splines of the solid input shaft (230) is engaged to the plurality of internal splines of the hollow output shaft (215).

2. The transmission system (200) as claimed in claim 1, wherein the gearbox casing region (205b) is integrated to the motor casing region (205a).

3. The transmission system (200) as claimed in claim 1, wherein the gearbox compartment (220) is detachably coupled to the gearbox casing region (205b), and wherein the solid input shaft (230) extends through the gearbox casing region (205b) of the motor compartment (205) and coupled to the hollow output shaft (215).

4. The transmission system (200) as claimed in claim 3, comprising:
a plurality of first support bearings (235a) for supporting the hollow output shaft (215) within the motor casing region (205a);
a plurality of second support bearings (235b) disposed within the motor casing region (205a) for supporting the hollow output shaft (215), wherein the plurality of second support bearings (235b) are sealed bearings; and
a plurality of third support bearings (235c) for supporting the solid input shaft (230) within the gearbox compartment (220).

5. The transmission system (200) as claimed in claim 1, wherein the motor casing region (205a) is detachably coupled to the gearbox casing region (205b).

6. The transmission system (200) as claimed in claim 5, wherein the gearbox casing region (205b) is detachably coupled to the gearbox compartment (220).

7. The transmission system (200) as claimed in claim 6, comprising:
a plurality of first support bearings (235a) for supporting the hollow output shaft (215) within the motor casing region (205a);
a plurality of second support bearings (235b) for supporting the hollow output shaft (215) within the motor casing region (205a), wherein the plurality of second support bearings (235b) are sealed bearings for supporting the hollow output shaft (215) within the motor casing region (205a);
a plurality of third support bearings (235c) for supporting the solid input shaft (230) within the gearbox compartment (220); and
a plurality of fourth support bearings (235d) for supporting the solid input shaft (230) within the gearbox casing region (205b), wherein the plurality of fourth support bearings (235d) are unsealed bearings for supporting the solid input shaft (230) within the gearbox casing region (205b).

8. The transmission system (200) as claimed in claim 1, wherein the gearbox casing region (205b) and the gearbox compartment (220) are integrated as one single cast unit and is detachably coupled to the motor casing region (205a).

9. The transmission system (200) as claimed in claim 8, comprising:
a plurality of first support bearings (235a) for supporting the hollow output shaft (215) within the motor casing region (205a);
a plurality of second support bearings (235b) for supporting the hollow output shaft (215) within the motor casing region (205a), wherein the plurality of second support bearings (235b) are sealed bearings for supporting the hollow output shaft (215) within the motor casing region (205a);
a plurality of third support bearings (235c) for supporting the solid input shaft (230) within the gearbox compartment (220); and
a plurality of fourth support bearings (235d) for supporting the solid input shaft (230) within the gearbox casing region (205b), wherein the plurality of fourth support bearings (235d) are unsealed bearings for supporting the solid input shaft (230) within the gearbox casing region (205b).

10. The transmission system (200) as claimed in claim 1, comprising a swingarm assembly (240), wherein the motor compartment (205) is coupled to the swingarm assembly (240).