Description:FIELD OF THE INVENTION

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

BACKGROUND

[2] In a saddle-type vehicle, for example an electric vehicle (EV) scooter, drum brakes are used in order to reduce cost of the vehicle. Typically, scooters with drum brakes have solid hubs. Having solid hubs avoid using sand core during casting process of the wheels and keeps the manufacturing cost low. Gravity die casting is a production technique where molten metal is poured into a metal mold or die, forming a casting. Cores, made of sand, serve to shape the inner components of a casting or portions that the pattern cannot shape. Typically, cores are employed to produce voids or hollow areas within a casting.

[3] In vehicles where a sand core is used in the wheel hub along with drum brake system a secondary hub is used on the opposite side which has mountings present for the transmission sprocket also referred to as chain wheel. This secondary hub consists of bearings, rubber dampers, and threaded holes for mounting the transmission sprocket. This increases the number of components and weight of the system.

[4] There is a need for weight reduction of the transmission system, wheels, and brakes as a system in order to reduce the unsprung mass and inertia. Unsprung mass is the total weight of the components that is not supported by the vehicles suspension system including wheels, brakes, and transmission system.

[5] Further, it is desired to reduce the frictional moment of the rotational components, namely the wheels and bearings. The bearings have to withstand various loads, i.e., transmission, brakes, road loads (bumps and cornering). Also, bearing frictional moment increases as more bending and axial loads are applied on the bearings. This further increases the bearing starting torque due to higher rolling resistance which reduces the efficiency and range of the vehicle. Range is critical for electric vehicles, and it is sensitive to the bearing loads hence there is a need to deploy methods to reduce the total frictional moment of the wheel bearings.

SUMMARY

[6] 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.

[7] The main objective of the present disclosure is weight reduction of the transmission, wheels, and brakes as a system in order to reduce the unsprung mass and inertia. Another objective of the present disclosure is to reduce the frictional moment of the rotational components, namely the wheels and bearings, in order to improve mileage.

[8] Accordingly a cast wheel with hollow hub is disclosed in the present disclosure.

[9] In an embodiment of the present disclosure, a cast wheel for a saddle-type vehicle is disclosed. The cast wheel includes a rim. The cast wheel includes a hollow wheel hub disposed within the rim and comprising a plurality of radial openings spaced apart from each other and positioned along a circumferential direction. The hollow wheel hub includes a first side comprising a plurality of axial threaded holes for mounting a transmission pulley. The first side includes a plurality of axial openings positioned between the plurality of axial threaded holes. The hollow wheel hub includes a second side for accommodating a drum brake. The cast wheel includes a plurality of spokes extending between the rim and the hollow wheel hub.

[10] 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

[11] 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:

[12] Figure 1 illustrates a perspective side view of a saddle-type vehicle, according to an embodiment of the present disclosure;

[13] Figure 2A and Figure 2B illustrate a perspective view of a cast wheel in the saddle-type vehicle, according to an embodiment of the present disclosure;

[14] Figure 3 illustrates a sectional view of the hollow wheel hub in the cast wheel, according to an embodiment of the present disclosure;

[15] Figure 4 illustrates a sectional view of the hollow wheel hub in the cast wheel, according to an embodiment of the present disclosure;

[16] Figure 5A illustrates a perspective view of the sand core casting in the cast wheel, according to an embodiment of the present disclosure;

[17] Figure 5B illustrates a sectional view of the sand core casting in the cast wheel, according to an embodiment of the present disclosure;

[18] Figure 6 illustrates a perspective view of the radial openings of the cast wheel, according to an embodiment of the present disclosure; and

[19] Figure 7A and Figure 7B illustrate a perspective view of the housing in the cast wheel, according to an embodiment of the present disclosure.

[20] 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

[21] 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.

[22] 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.

[23] 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.”

[24] 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.

[25] 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.

[26] 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.

[27] 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.

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

[29] 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.

[30] 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).

[31] 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.

[32] 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.

[33] 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).

[34] 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.

[35] 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.

[36] Embodiments of the present disclosure includes a cast wheel for the saddle-type vehicle (10).

[37] Figure 2A and Figure 2B illustrate a perspective view of a cast wheel (200) in the saddle-type vehicle, according to an embodiment of the present disclosure. The cast wheel (200) includes a rim (205), a hollow wheel hub (210), and a plurality of spokes (215) as depicted in Figure 2A and Figure 2B. The spokes (215) extend between the rim (205) and the hollow wheel hub (210).

[38] The hollow wheel hub (210) is disposed within the rim (205). It includes a plurality of radial openings (220a, 220b) spaced apart from each other and positioned along a circumferential direction. The hollow wheel hub (210) includes a first side (225) and a second side (240). Typically, the first side (225) is the left side, and the second side (240) is the right side of the saddle-type vehicle (10).

[39] The first side (225) includes a plurality of axial threaded holes (230a, 230b) for mounting a transmission pulley (not shown). The first side (225) includes a plurality of axial openings (235a, 235b) positioned between the plurality of axial threaded holes (230a, 230b).

[40] The second side (240) is for accommodating a drum brake (250). The second side (240) includes a housing (245) for receiving the drum brake (250). The housing (245) and the drum brake (250) are illustrated in Figure 7A and Figure 7B.

[41] Figure 5A illustrates a perspective view and Figure 5B illustrates a sectional view of the sand core casting in the cast wheel (200), according to an embodiment of the present disclosure. In one embodiment, the cast wheel (200) is manufactured using gravity die casting method using six dies, a top die, a bottom die and four side dies each covering 90 degree of the wheel rim area. In the manufacturing process, first a cast iron ring (505) is positioned in the bottom die of a mold. As shown in the Figure 5A, a sand core (510) is positioned above the cast iron ring (510) such that the sand core (510) is resting on bottom die of the mold maintaining a certain gap with the cast iron ring (510) to facilitate the filling of aluminum in the available gap as illustrated in Figure 5A.

[42] The sand core (510) is formed in the shape of desired hollow shape of the hollow wheel hub (210). The sand core (510) defines and gives shape to the hollow wheel hub (210) during the casting process. The sand core (510) includes radial projections (520) defining shape of the plurality of radial openings (220a, 220b) as illustrated in Figure 5A. Likewise, the axial projections (525) are illustrated in Figure 5B. The sand core (510) is positioned above the cast iron ring (505) by resting the radial projections features of the sand core (510) on the die. The casting process of the cast wheel (200) includes pouring molten metal from the top die of the mold through a gate area to fill spaces. Further, the sand core (510) is removed once the metal solidifies.

[43] The radial projections (520) defining shape of the plurality of radial openings (220a, 220b) are configured in a poka-yoke pattern. In the poka-yoke pattern, one of the plurality of radial projections (520) is characterized to have a higher dimension compared to the remaining plurality of radial projections (520). This is done to define an orientation of the sand core (510) and avoid variations of the positioning of the sand core (510) in the mold. The resulting radial openings (220a, 220b) having varying dimension is further illustrated in Figure 6. In figure 6, the radial opening (220a) has a higher dimension as depicted in View-G when compared to the radial opening (220b) as depicted in View-F in Figure 6.

[44] Referring to Figure 3, the cast wheel (200) includes a plurality of first bearings (305a, 305b) disposed within the first side (225) of the hollow wheel hub (210) and configured to mount the transmission pulley. Further, the cast wheel (200) includes a second bearing (310) disposed within the second side (240) of the hollow wheel hub (210) and configured to mount the drum brake (250).

[45] The hollow wheel hub (210) is characterized by relatively increased width enabling an increased bearing span (315). The bearing span is (315) defined as space between the plurality of first bearings (305a, 305b) and the second bearing (310). The increased bearing span (315) enables positioning of the transmission pulley relatively far from a radial centerline of the cast wheel (200). The increased bearing span (315) enables positioning of the plurality of first bearings (305a, 305b) relatively closer to the transmission pulley. This is further illustrated and explained with reference to Figure 4.

[46] Referring to Figure 4, the various centerlines depicted are wheel centerline (C1), bearing (305b) or bearing 1 centerline (C2), bearing (305a), or bearing 2 centerline (C3), wheel pulley centerline (C4), brake shoe centerline (C5), and bearing (310) or bearing 3 centerline (C6). The positioning of the plurality of first bearings (305a, 305b) relatively closer to the transmission pulley reduces bending moment and rolling resistance of the first set of bearings (305a, 305b). Reducing the bending moment of the first set of bearings (305a, 305b) increases mileage of the saddle-type vehicle. It is to be noted that one of the plurality of radial openings (220a, 220b) is characterized to have a higher dimension compared to the remaining plurality of radial openings (220a, 220b).

[47] Since the central volume of the hollow wheel hub (210) is hollow, the width of the hollow wheel hub (210) can be increased without increasing the hub weight substantially and the transmission pulley can be positioned farther away from the wheel centerline (C1) as illustrated in Figure 4. In one embodiment, the wheel pulley centerline (C4) is 89.25 mm away from wheel centerline (C1). The mounting plane is kept solid to provide the plurality of axial threaded holes (230a, 230b) for transmission pulley mounting.

[48] It is to be noted that majority of the vehicles having drum brake system in internal combustion engine category have solid hubs. Even if the hub is made hollow only radial openings are present and no axial openings are provided. In the present disclosure, the plurality of axial openings (235a, 235b) and the plurality of radial openings (220a, 220b) enable air flow in and out of the hollow wheel hub (210) to cool the drum brake (250).

[49] Further, it is to be noted that majority of the vehicles in prior art having drum brake system in internal combustion engine category, uses a separate sprocket hub (secondary hub) which has threaded holes to mount the transmission sprocket. It has bearing press fitted in the housing and gets clamped to the wheel using rear axle bolt and nut. In the present disclosure, the plurality of axial threaded holes (230a, 230b) provided for mounting the transmission system are part of the cast wheel (200) and the transmission pulley directly gets bolted to the cast wheel (200). Further, in the present disclosure, the bearings (305a, 305b, 310) are placed inside the hollow wheel hub (210). This design in the present disclosure removes one sub assembly, thereby reducing the cost and weight. Further, the radial openings (220a, 220b) and the axial openings (235a, 235b) relatively reduces weight of the cast wheel (200).

[50] In this type of wheel, hub is made hollow using a sand core while providing housing (245) to receive drum brake panel on the right side and has projections to mount transmission pulley on the left side.

[51] The hollow wheel hub (210) has openings in both radial & axial directions which reduces the weight. Further because the hub (210) is made hollow, bearing span (315) could be increased such that bearings (305a, 305b) could be positioned closer to transmission pulley which resulted in lower bending moment on the bearing thereby improving the range of the electric vehicle.

[52] 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.

[53] List of reference numerals:
Components Reference numerals
Cast wheel 200
Rim 205
Hollow wheel hub 210
Plurality of spokes 215
Plurality of radial openings 220a, 220b
First side 225
Axial threaded holes 230a, 230b
Second side 240
Plurality of first bearings 305a, 305b
Second bearing 310
Bearing span 315
Cast iron ring 505
Sand core 510
Radial projections 520
Axial projections 525
Housing 245
Drum Brake 250
, Claims:1. A cast wheel (200) for a saddle-type vehicle (10), the cast wheel (200) comprising:
a rim (205);
a hollow wheel hub (210) disposed within the rim (205) and comprising a plurality of radial openings (220a, 220b) spaced apart from each other and positioned along a circumferential direction (D), wherein the hollow wheel hub (210) comprises:
a first side (225) comprising a plurality of axial threaded holes (230a, 230b) for mounting a transmission pulley, wherein the first side (225) comprises a plurality of axial openings (235a, 235b) positioned between the plurality of axial threaded holes (230a, 230b); and
a second side (240) for accommodating a drum brake (250); and
a plurality of spokes (215) extending between the rim (205) and the hollow wheel hub (210).

2. The cast wheel (200) as claimed in claim 1, comprising:
a plurality of first bearings (305a, 305b) disposed within the first side (225) of the hollow wheel hub (210) and configured to mount the transmission pulley; and
a second bearing (310) disposed within the second side (240) of the hollow wheel hub (210) and configured to mount the drum brake (250).

3. The cast wheel (200) as claimed in claim 2, wherein the hollow wheel hub (210) is characterized by relatively increased width enabling an increased bearing span (315), wherein the bearing span is (315) defined as space between the plurality of first bearings (305a, 305b) and the second bearing (310).

4. The cast wheel (200) as claimed in claim 3, wherein the increased bearing span (315) enables:
positioning of the transmission pulley relatively far from a radial centerline (C1) of the cast wheel (200); and
positioning of the plurality of first bearings (305a, 305b) relatively closer to the transmission pulley.

5. The cast wheel (200) as claimed in claim 4, wherein the positioning of the plurality of first bearings (305a, 305b) relatively closer to the transmission pulley reduces bending moment and rolling resistance of the first set of bearings (305a, 305b), wherein reducing the bending moment of the first set of bearings (305a, 305b) increases mileage of the saddle-type vehicle (10).

6. The cast wheel (200) as claimed in claim 1, wherein the wheel (200) is cast using gravity die casting, wherein the gravity die casting is performed by steps of:
positioning a cast iron ring (505) in a bottom die of a mold;
positioning a sand core (510) above the cast iron ring (505), wherein the sand core (510) defines shape of the hollow wheel hub (210), wherein the sand core (510) comprises radial projections (520) defining shape of the plurality of radial openings (220a, 220b);
pouring molten metal from a top die of the mold through a gate area to fill spaces; and
removing the sand core (510) after solidifying the molten metal.

7. The cast wheel (200) as claimed in claim 6, whererin the radial projections (520) defining shape of the plurality of radial openings (220a, 220b) are configured in a poka-yoke pattern, wherein one of the plurality of radial projections (520) is characterized to have a higher dimension compared to the remaining plurality of radial projections (520) to define an orientation of the sand core (510) and avoid variations of the positioning of the sand core (510) in the mold.

8. The cast wheel (200) as claimed in claim 1, wherein the radial openings (220a, 220b) and the axial openings (235a, 235b) relatively reduces weight of the cast wheel (200).

9. The cast wheel (200) as claimed in claim 1, wherein the plurality of axial openings (235a, 235b) and the plurality of radial openings (220a, 220b) enable air flow in and out of the hollow wheel hub (210) to cool the drum brake (250).

10. The cast wheel (200) as claimed in claim 1, wherein one of the plurality of radial openings (220a, 220b) is characterized to have a higher dimension compared to the remaining plurality of radial openings (220a, 220b).