DESC:FIELD OF INVENTION
[0001] The present subject matter described herein generally relates to a drive system for a hybrid two-wheeled vehicle.
BACKGROUND OF INVENTION
[0002] In recent times there is an increased demand to control emissions from automobiles, in view of stringent emission norms. As a result, a number of hybrid and electric vehicles are seeing the light of the day in order to minimize the amount of emissions.
[0003] For example, typical hybrid vehicles configured to be powered either by an internal combustion engine or a traction motor independently or both simultaneously, are replacing normal engine powered vehicles. Said hybrid vehicles are configured to operate in different operating modes such as sole engine mode, sole motor mode, hybrid power mode, hybrid economy mode and the like. Particularly, said hybrid vehicles, especially of the parallel type include a drive system for transmitting power from the engine to a rear wheel, while the engine is operating in different operating modes such as sole engine mode, hybrid power mode or hybrid economy mode. However, when the motor alone operates, it directly drives the rear wheel without involving any power transmission system.
[0004] In a known art, a drive system provided to transmit power from the internal combustion engine to the rear wheel includes a driven pulley which is directly supported on a flange which is permanently and rigidly secured to a motor shroud of the traction motor. Particularly, said flange made of steel is used to support the driven pulley. Thus, presence of the flange results in significant increase in weight at a hub of the rear wheel, thereby resulting in increased inertia at the rear wheel of the hybrid vehicle. Increased inertia at the rear wheel results in energy losses which is undesirable. Moreover, presence of the flange also results in overall increase in width and weight of the hybrid vehicle. Further, in hybrid vehicles there is also a need to prevent energy losses due to increased friction of a belt of the drive system.
[0005] Further, in a condition when the traction motor of the hybrid vehicle is operating to drive the rear wheel, there is a need to isolate the engine from the traction motor so that there is no power transmission to the engine from the motor.
[0006] There is therefore a need to provide a drive system in which energy losses are minimized, while ensuring that there is no power transmission from the motor to the engine. Further, it is also essential to achieve compactness and weightlessness of the drive system so that overall compactness and weightlessness of the hybrid vehicle is achieved.
[0007] It is therefore desired to address the problems encountered in the background as discussed above.

BRIEF DESCRIPTION OF DRAWINGS
[0008] The detailed description of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.
[0009] Figure 1 illustrates a side view of a hybrid vehicle including a drive system in accordance with an embodiment of the present invention.
[00010] Figure 2a illustrates a cross sectional view of the drive system as connected to the rear wheel in accordance with a first embodiment of the present invention.
[00011] Figure 2b illustrates a cross sectional view of the drive system depicting an arrangement of a driven pulley thereof in accordance with the first embodiment of the present invention.
[00012] Figure 3a illustrates a side cross sectional view of the drive system as connected to the rear wheel in accordance with a second embodiment of the present invention.
[00013] Figure 3b illustrates a cross sectional view of the drive system taken along a line A-A in FIG.3a in accordance with the second embodiment of the present invention.
[00014] Figure 4 illustrates an exploded view of the drive system in accordance with the second embodiment of the present invention.
[00015] Figure 5 illustrates a cross sectional view of a driven member of said drive system in accordance with the second embodiment of the present invention.
[00016] Figure 6 illustrates a cross sectional view of a driven pulley of said drive system in accordance with the second embodiment of the present invention.
[00017] Figure 7 illustrates a cross sectional view of the drive system in accordance with a third embodiment of the present invention.
DETAILED DESCRIPTION
[00018] The present invention has been devised in view of the above stated problems.
[00019] It is an object of the present invention to provide a hybrid vehicle including a drive system, the configuration and arrangement of which aids in preventing energy losses.
[00020] It is another object of the present invention to provide a drive system for a hybrid vehicle which aids in preventing power transmission to an engine of said vehicle during operation of a motor thereof.
[00021] It is yet another object of the present invention to provide a drive system, a manner of disposition thereof aiding in achieving weightlessness and compactness of the hybrid vehicle.
[00022] It is still another object of the present invention to provide a drive system whose construction and arrangement aids in achieving smooth transmission between various modes of vehicle operation.
[00023] It is one more object of the present invention to provide a drive system, whose configuration is such that minimal wear out of parts thereof is ensured.
[00024] It is still another object of the present invention to provide a drive system whose configuration enables easy assembly of parts thereof.
[00025] The subject matter described herein therefore relates to a drive system for a hybrid vehicle, said hybrid vehicle comprising an internal combustion engine and a traction motor for driving a rear wheel of said vehicle. Traction motor in the present embodiment is hub mounted traction motor. Particularly, operation of said engine or the traction motor or both for driving the vehicle, depends on selection of different drive modes such as sole engine mode where engine alone powers the vehicle, sole motor mode where the traction motor alone powers the vehicle, a hybrid power mode wherein the engine and the traction motor together power the hybrid vehicle, and a hybrid economy mode wherein only the engine or only the traction motor or both power the hybrid vehicle depending on the vehicle operating conditions such as vehicle speed etc. Particularly, said hybrid vehicle includes a drive system for transmitting power from said internal combustion engine to the rear wheel when the engine operates either in sole engine mode or in hybrid power mode or in hybrid economy mode. The drive system as per an aspect of the present invention prevents power transmission from the rear wheel to the engine in a condition when said motor powers said vehicle. The drive system as per the present invention includes a motor shroud for covering the traction motor from at least one side, and which in turn is configured to support other members of said drive system including a driven member and a driven pulley. Said driven pulley supports a belt for transmitting power from the engine to the rear wheel. As per the present invention, the drive system further includes a one way clutch for preventing transmission of power from the rear wheel to the engine through the belt when the motor alone is powering the rear wheel. Whereas in one embodiment, said one way clutch is affixed to said driven member, in another embodiment said one way clutch is affixed to said driven pulley. Further, presence of the one way clutch ensures that the belt is not driven even when the vehicle is going downhill. Thus, the drive system as per the present invention aids in ensuring that the belt is not unnecessarily driven, thereby preventing wear out of the belt. Therefore, unnecessary energy loss due to belt friction is prevented. Moreover, since parts of the drive system including the driven member, and the driven pulley are supported to the motor shroud without involving the use of additional supporting members, it is ensured that compactness of said hybrid vehicle is achieved. Particularly, since the use of any mounting member permanently integrated with the motor shroud is eliminated in the present invention, weightlessness of the hybrid vehicle is also ensured.
[00026] As per another aspect of the present invention, a plurality of damper members is disposed between a portion of said motor shroud and said driven pulley, in order to enable smooth transmission during different modes of vehicle operation without causing said hybrid vehicle to jerk.
[00027] Thus, the aspects of the present invention aid in preventing power transmission to the engine when the traction motor is motoring, thereby preventing unnecessary driving of the belt, while also ensuring compactness and weightlessness of the hybrid vehicle.
[00028] Summary provided above explains the basic features of the invention and does not limit the scope of the invention. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings.
[00029] Exemplary embodiments detailing features of the drive system in accordance with the present invention will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present invention will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Further, it is to be noted that terms “upper”, “lower”, “right”, “left”, “front”, “forward”, “rearward”, “downward”, “upward”, “top”, “bottom” and like terms are used herein based on the illustrated state or in a standing state of the hybrid vehicle with a driver sitting thereon unless otherwise elaborated. Furthermore, a longitudinal axis refers to a front to rear axis relative to said vehicle, defining a vehicle longitudinal direction; while a lateral axis refers to a side to side, or left to right axis relative to said vehicle, defining a vehicle lateral direction. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
[00030] Arrows provided in the top right corner of each figure depicts direction with respect to the motorcycle, wherein an arrow F denotes front direction, an arrow R indicates rear direction, an arrow Up denotes upward direction, an arrow Dw denotes downward direction, an arrow Rh denotes right side, an arrow Lh denotes left side, as and where applicable.
[00031] With reference to FIG. 1, a description is made of a hybrid vehicle 100 in accordance with an embodiment of the present invention. FIG.1 is a side view of said hybrid vehicle 100. Said vehicle 100 illustrated, has a step-through type frame assembly 105. The step-through type frame assembly 105 includes a head tube 105A, a main tube 105B and a pair of side tubes 105C. Particularly, the main tube 105B extends downwards and rearwards from an anterior portion of the head tube 105A. Further, the pair of side tubes 105C extends inclinedly upwardly from the main tube 105B towards a rear end of said vehicle 100. Thus, the frame assembly 105 extends from a front portion to a rear portion of the vehicle.
[00032] The hybrid vehicle 100 further includes a plurality of body panels for covering said frame assembly 105, and is mounted thereto. In the present embodiment said plurality of panels includes a front panel 115A, a leg shield 115B, an under-seat cover 115C, and a left and a right side panel 115D. Further, a glove box may be mounted to said leg shield 115B.
[00033] In a step through space formed between said leg shield 115B and said under seat cover 115C, a floorboard 120 is provided. Further, a seat assembly 125 is disposed above said under-seat cover 115C, and is mounted to the pair of side tubes 105C. A utility box (not shown) is disposed below the seat assembly 125. A fuel tank (not shown) is positioned at one end of the utility box. A rear fender 126 for covering at least a portion of a rear wheel 127 is positioned below the fuel tank.
[00034] One or more suspension(s)/shock absorbers 130 are provided in a rear portion of said vehicle 100 for comfortable ride. Further said vehicle 100 comprises of plurality of electrical and electronic components including a headlight 135A, a taillight 135B, a transistor controlled ignition (TCI) unit (not shown), a starter motor (not shown) and the like. A touch screen LCD unit (not shown) is provided on a handle bar 110 to display various operating modes, power flow pattern and warning signals. Rear view mirrors 112 are mounted on the right and left sides of the handle bar 110. Said vehicle 100 is also provided with hazard lamps (not shown).
[00035] An internal combustion engine 140, hereinafter “engine”, is arranged behind said floorboard 120 and supported between the pair of side tubes 105C. Particularly, said internal combustion engine 140 is supported by a swing arm 109. The swing arm 109 is attached to a lower portion of the main tube 105B by means of a toggle link (not shown). The other end of the swing arm 109 holds the rear wheel 127. The rear wheel 127 and the swing arm 109 are connected to the pair of side frames 105C by means of one or more shock absorbers 130 provided on either side of said vehicle 100.
[00036] Said hybrid vehicle 100 further includes a traction motor 150 mounted on a hub of the rear wheel 127. Said traction motor 150 is powered by a battery (not shown) disposed in a rear portion of the vehicle. A controller (not shown) is also provided to control various vehicle operative modes.
[00037] Said hybrid vehicle 100 is configured to be propelled either by the engine 140 alone or by the traction motor 150 alone or by both engine 140 and traction motor 150 simultaneously. At zero vehicle speed, a rider can select any of the following four operating drive modes with the help of a mode switch. The four operating drive modes of the hybrid vehicle 100 are: (a) a sole engine mode where engine 140 alone powers the vehicle (b) a sole motor mode where the traction motor 150 alone powers the vehicle (c) a hybrid power mode wherein the engine 140 and the traction motor 150 together power the hybrid vehicle 100 (d) a hybrid economy mode wherein only the engine 140 or only the traction motor 150 or both power the hybrid vehicle depending on the vehicle operating conditions.
[00038] In other words, the rear wheel 127 of the vehicle is driven by either the engine 140 alone or by the motor 150 alone or by both the engine 140 and the motor 150 simultaneously. Particularly, power from the engine 140 to the rear wheel 127 is transmitted by a transmission assembly including a drive system 200 (shown in FIG.2a) as per an embodiment of the present invention. However, when the traction motor 150 drives, power from the motor 150 is directly transmitted to the rear wheel 127. As per one embodiment and as may be seen in FIG.2a, said traction motor 150 is covered by a motor shroud 201 from at least one side. As per an aspect of the present invention, said motor shroud 201 serves to at least partially encompass/house one or more parts of the drive system 200 and therefore constitutes a part of the drive system 200. On another side of the wheel shaft 129, the motor shroud 201 serves to house a brake drum (not shown). Thus, since the motor shroud 201 serves to house parts of the drive system 200 and the brake drum, compactness of the hybrid vehicle at the hub is achieved. Moreover, weightlessness of the vehicle is also achieved since no additional members are required for supporting the drive system and the brake drum as they are directly supported on the motor shroud 201.
[00039] Power from the engine 140 is transmitted to the rear wheel 127 through the drive system 200 as per a first embodiment of the present invention. As may be seen in FIG.2a, the drive system 200 as per the present embodiment includes a belt 205 supported between a drive pulley 207 and a driven pulley 204; said drive pulley 207 being supported on an output shaft 141 of the engine, and the driven pulley 204 being directly supported on the motor shroud 201. Preferably, said belt 205 is a toothed belt. Particularly, while one end of the belt 205 is supported on a first flange 205a affixed to the output shaft 141, the other end of the belt 205 is supported on a second flange 205b affixed to the driven pulley 204. For example in the present embodiment, while the first flange 205a is disposed in an outer side of the output shaft 141, the second flange 205b is disposed in an inner side of the driven pulley 204, facing the rear wheel 127. Provision of the first flange 205a and the second flange 205b as described above enables easy assembly of the belt 205.
[00040] Further, as per a first embodiment and as may be seen in FIG.2a and FIG.2b, the driven pulley 204 is directly rigidly supported on the motor shroud 201. For example, as may be seen in FIG.2b, the driven pulley 204 is secured to the motor shroud 201 by means of fasteners 208. More particularly, a plurality of mounting lugs 201a is provided on the motor shroud 201 to receive the driven pulley 204. Once the driven pulley 204 is located on said plurality of mounting lugs 201a, fasteners 208 are used to secure said driven pulley 204. Thus, the use of the flange as per the prior art for mounting the driven pulley 204 is eliminated. Further, since the driven pulley 204 is directly supported on the motor shroud 201, when said pulley 204 rotates, it directly rotates the motor shroud 201, which in turn rotates the rear wheel 127. Thus, power is transmitted directly through the drive system 200 to the rear wheel 127 without involving any energy losses since the motor is not caused to rotate unnecessarily. Moreover, since use of the flange for mounting the driven pulley is eliminated, weight at the hub of the rear wheel is significantly reduced, thereby resulting in reduced inertia at the rear wheel, which in turn results in reduced energy losses.
[00041] The drive system 200 including the belt 205 and the driven pulley 204, thus assembled serves to transmit power to the rear wheel 127 in an engine operating condition such as sole engine mode, hybrid power mode or hybrid economy mode when engine is powering the vehicle.
[00042] Further, the drive system 200 as per the present invention is also adapted to prevent transmission of power to the engine 140 when the rear wheel 127 is driven by the traction motor 150. As per a preferred embodiment, and as may be seen in FIG.2a, the drive system 200 includes a one way clutch 203 which serves to prevent power transmission from the rear wheel 127 to the engine 140.
[00043] FIG.2a denotes the arrangement of the one way clutch 203 as per one implementation of the present invention. As may be seen in FIG.2a, the one way clutch 203 is coupled to the output shaft 141 of the internal combustion engine 140. Presence of the one way clutch 203 at the output shaft 141 ensures that there is no power transmission to the engine 140 when the motor is driving the rear wheel 127. Particularly, the one way clutch 203 gets disengaged from the output shaft 141 or starts slipping over the output shaft 141 when said motor 150 powers the rear wheel 127, thereby cutting power transmission to the engine 140 at the output shaft 141.
[00044] The arrangement and working of the drive system 200 including that of the one way clutch 203 as per another implementation of the present invention is elaborated in FIGs.3a-FIG.6. FIG.3b denotes a cross sectional view of the drive system 200 taken along a line A-A in FIG.3a. The drive system 200 as per the present embodiment includes the motor shroud 201 which is concentrically disposed around the rear wheel shaft 129, serves to cover the traction motor 150 from at least one side, and is affixed to the hub of the rear wheel 127. For example, in the present embodiment, said motor shroud 201 is detachably attached to the hub by means of fasteners 208. Further, the motor shroud 201 is adapted to receive one or more members of the drive system 200. As per a second embodiment of the present invention, and as may be seen in FIG.3b and FIG.4, the motor shroud 201 is adapted to support a driven member 202 of the drive system 200. Particularly, the motor shroud 201 is provided with the plurality of mounting lugs 201a disposed radially along an outer surface thereof, for receiving said driven member 202. The driven member 202 is correspondingly provided with a plurality of mounting holes 202a for location onto said plurality of mounting lugs 201a. Further, the driven member 202 includes a central hole 202b which gets concentrically disposed around the rear wheel shaft 129 when said driven member 202 is located on said plurality of mounting lugs 201a. The driven member 202 as per the present embodiment includes the one way clutch 203. Particularly, said one way clutch 203 is press fitted in the central hole 202b of said driven member 202 (shown in FIG.5). Thus, the driven member 202 detachably attached to said motor shroud 201 through said plurality of mounting lugs 201b is concentrically disposed around the rear wheel shaft 129 with the one way clutch 203 in a spaced relation with said rear wheel shaft 129. Thus, said motor shroud 201 is adapted to removably receive said driven member 202
[00045] Further, the motor shroud 201 is provided with a plurality of damper members 201b configured to be located over each mounting lug of the plurality of mounting lugs 201a. Particularly, it is ensured that the plurality of damper members 201b thus located over the plurality of mounting lugs 201a do not dismount/come off due to vibrations, by providing a retainer member 206. In the present embodiment, said retainer member 206 is provided in the form of a plate and is secured to said plurality of mounting lugs 201a by means of fasteners 208, thereby ensuring that the plurality of damper members 201b do not get dislocated/dismounted in vehicle running condition. Thus, the retainer member 206 is also concentrically disposed around the rear wheel shaft 129.
[00046] Furthermore, as per the present embodiment, the driven pulley 204 is also concentrically disposed around the rear wheel shaft 129, and floatingly supported over said shaft 129. In the present embodiment, the driven pulley 204 includes a needle roller bearing 204n in a central portion thereof, said needle roller bearing 204n directly rests on the rear wheel shaft 129. Further, the driven pulley 204 includes a protruding sleeve member 204a (shown in FIG.6) which is held in contact with the one way clutch 203 in an assembled condition of the driven pulley 204. In the present embodiment, said protruding sleeve member 204a is formed by encasting with said driven pulley 204. However, in another embodiment, said protruding sleeve member 204a may be press fitted to the driven pulley 204.
[00047] In an engine operating condition, power from the output shaft 141 (shown in FIG.2b) is transmitted to the rear wheel 127 through the drive system 200. Particularly, when the driven pulley 204 starts rotating, it causes the one way clutch 203 to rotate, due to contact of the one way clutch 203 with the protruding sleeve member 204a of the driven pulley 204. Further, since the one way clutch 203 is disposed in the driven member 202, it causes the driven member 202 to rotate. Furthermore, since the driven member 202 is secured to the motor shroud 201, rotation of the driven member 202 causes the motor shroud 201 to rotate, thereby causing the rear wheel 127 to rotate. Thus, drive system 200 directly transmits power from the engine to the rear wheel 127 in an engine operating condition, including operation of the engine in sole engine mode, hybrid power mode and hybrid economy mode.
[00048] In a condition when the traction motor 150 operates, including in sole motor mode and in hybrid economy mode, it causes the rear wheel 127 to rotate, thereby resulting in rotation of the motor shroud 201. Rotation of the motor shroud 201 in turn causes the driven member 202 and thereby the one way clutch 203 to rotate. However, due to its contact with the protruding sleeve member 204a of the driven pulley 204, which tries to apply an opposite force on the one way clutch 203; the one way clutch 203 starts slipping over the protruding sleeve member 204a. As a result the one way clutch fails 203 to transfer power to the driven pulley 204 so as to drive it in the motor operating condition. Therefore, it is ensured that there is no power transmission to the engine 140 in either the sole motor mode or the hybrid economy mode, through the drive system 200. Moreover, since the one way clutch 203 fails to transfer power to the driven pulley 204 in the motor operating condition, said driven pulley 204 supporting the belt 205; it is ensured that the belt 205 is not driven during motoring. As a result, it is ensured that energy loss due to friction of the belt is eliminated.
[00049] As per a third embodiment of the present invention and as may be seen in FIG.7, the one way clutch 203 may be disposed in the driven pulley 204, and the driven pulley 204 may be disposed over a sleeve member or an insert member 201c which is encasted with the motor shroud 201. Particularly, said driven pulley 204 is concentrically disposed over said insert member 201c, with said insert member 201c being supported over the needle roller bearing 204n. In the present embodiment, said one way clutch 203 is press fitted in the driven pulley 204. During operation of the engine 140, the one way clutch 203 gets engaged with the insert member 201c causing said insert member 201c to rotate; and thereby causing said motor shroud 201 to rotate. The rear wheel 127 is therefore caused to rotate. However, when the motor 150 begins to operate, the one way clutch 203 begins to slip over the insert member 201c, thereby preventing rotation of the driven pulley 204; and thus preventing power transmission to the engine. In another embodiment, said insert member may be press fitted on said motor shroud. Thus, the third embodiment of the present invention serves to eliminate the need for a separate driven member as disclosed in the second embodiment, for encompassing/accommodating the one way clutch. However, the working of the one way clutch remains the same as that discussed in the first and second embodiments.
[00050] As per an aspect of the present invention, since the drive system including the driven pulley is directly supported on the motor shroud, without involving the need for separate mounting members, compactness of the drive system, and therefore that of the hybrid vehicle is maintained. Moreover, presence of the plurality of damper members ensures that there is smooth transmission of power from said drive system to the hub of the rear wheel, thereby ensuring that the hybrid vehicle does not experience jerking while different modes of operation are being selected.
[00051] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims:
,CLAIMS:We Claim:
1. A drive system (200) for a hybrid vehicle (100), said hybrid vehicle comprising an internal combustion engine (140) and a hub mounted traction motor (150) for driving a rear wheel (127) of said hybrid vehicle (100); said engine (140) being operatively connected to said motor (150) through said drive system (200), with at least a portion of said drive system (200) being concentrically disposed around a wheel shaft (129) of the rear wheel (127);
wherein, said drive system (200) includes a motor shroud (201), and a driven pulley (204), said driven pulley (204) being rigidly supported to said motor shroud (204).
2. The drive system (200) as claimed in claim 1, wherein said drive system (200) includes a one way clutch (203), said one way clutch (203) being coupled to an output shaft (141) of said engine (140).
3. The drive system (200) as claimed in claim 1, wherein said motor shroud (201) detachably attached to a hub of the rear wheel (127) covers said traction motor (150) from at least one side.
4. A drive system (200) for a hybrid vehicle (100), said hybrid vehicle (100) comprising an internal combustion engine (140) and a hub mounted traction motor (150) for driving a rear wheel (127) of said hybrid vehicle (100); said engine (140) being operatively connected to said motor (150) through said drive system (200), with at least a portion of said drive system (200) being concentrically disposed around a wheel shaft (129) of the rear wheel (127);
wherein, said drive system (200) includes a motor shroud (201), a driven member (202) and a driven pulley (204), said motor shroud (201) being adapted to removably receive said driven member (202), and said driven pulley (204) being floatingly supported over said wheel shaft (129).
5. The drive system (200) as claimed in claim 4, wherein said motor shroud (201) includes a plurality of mounting lugs (201a) disposed radially along an outer surface thereof for receiving said driven member (202).
6. The drive system (200) as claimed in claim 5, wherein said motor shroud (201) includes a plurality of damper members (201b), and wherein each damper member of said plurality of damper members (201b) is located over each mounting lug of said plurality of mounting lugs (201a).
7. The drive system (200) as claimed in claim 4 or claim 5, wherein said driven member (202) is detachably attached to said plurality of mounting lugs (201a) of said motor shroud (201).
8. The drive system (200) as claimed in claim 4, wherein said drive system (200) includes a one way clutch (203), said one way clutch (203) being accommodated in said driven member (202).
9. The drive system (200) as claimed in claim 8, wherein said driven pulley (204) includes a protruding sleeve member (204a) which is held in contact with the one way clutch (203) in an assembled condition of the driven pulley (204).
10. The drive system (200) as claimed in claim 4, wherein said drive system (200) includes a one way clutch (203), said one way clutch (203) being accommodated in said driven pulley (204), and wherein said driven pulley (204) is disposed over an insert member (201c) encasted with said motor shroud (201).