Title of Invention	INTERNAL COMBUSTION ENGINE WITH CONTINUOUSLY VARIABLE TRANSMISSION
Abstract	Disclosed is an internal combustion engine (200) having a continuously variable transmission (27); a starting system comprising a starter motor (24), a ring gear (29) and a ring gear drive (26) operable on starting of the engine (200), and a crankshaft (220) having a first section (22) and a second section (23) wherein the continuously variable transmission (27) is connected to the first section (22) of the crankshaft (220) and the ring gear (29) of the starting system is connected to the second section (23) of the crankshaft (220) distal from the continuously variable transmission (27).

Title of Invention

INTERNAL COMBUSTION ENGINE WITH CONTINUOUSLY VARIABLE TRANSMISSION

Abstract

Disclosed is an internal combustion engine (200) having a continuously variable transmission (27); a starting system comprising a starter motor (24), a ring gear (29) and a ring gear drive (26) operable on starting of the engine (200), and a crankshaft (220) having a first section (22) and a second section (23) wherein the continuously variable transmission (27) is connected to the first section (22) of the crankshaft (220) and the ring gear (29) of the starting system is connected to the second section (23) of the crankshaft (220) distal from the continuously variable transmission (27).

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 of 1970) As amended by the Patents (Amendment) Act, 2005 & The Patents Rules, 2003 As amended by the Patents (Amendment) Rules, 2005 COMPLETE SPECIFICATION (See section 10 and rule 13) TITLE OF THE INVENTION Internal combustion engine with continuously variable transmission APPLICANTS Name : Bajaj Auto Limited Nationality : Indian Company Address : Akurdi, Pune 411035, Maharashtra, India PREAMBLE TO THE DESCRIPTION The following specification particularly describes the nature of this invention and the manner in which it is to be performed: This invention relates to an internal combustion engine having a continuously variable transmission. An engine used as a prime mover in 2 or 3 wheeled vehicles is typically provided with either a kick start or an electric start. The starting system employed in such vehicles normally has two configurations. Either the starting system operates through a one way clutch or the starting system has what is commonly known as a 'bendix' drive. In the latter case, the starter motor and bendix drive are fixed on the engine crankcase. The magneto is mounted on the crankshaft and rotary motion of the crankshaft is transmitted to a magneto rotor through a key. The magneto generates electricity for operation of ignition, lighting and signaling systems of the vehicle. The output shaft of the starter motor engages with the bendix drive, which in turn engages with the ring gear. When the starter motor is actuated, the motor drives the ring gear. This drives the crankshaft which enables the engine to start. Once the engine has attained a predetermined speed, the bendix drive disengages from the ring gear. Some vehicles of the above type use a continuously variable transmission (CVT). A CVT is a mechanical device in which the torque transmission ratio is infinitely variable over a certain working range. This contrasts with a conventional geared transmission which has a limited number of selectable torque transmission ratios. A CVT automatically changes the torque transmission ratio depending on engine load and speed conditions. To this end, the CVT typically comprises of a driving pulley connected to a first half of a crankshaft of the engine, a driven pulley connected to wheels and a drive belt transmitting torque from the driving pulley to the driven pulley. In some CVT designs, the driving pulley comprises of a centrifugal mechanism that varies the torque transmission ratio depending upon the speed of the driving pulley. Conventionally, when an engine with a CVT is required to be provided with a starter motor, the ring gear of the starting system is provided on the same side of the engine as that on which the CVT is fitted. This side of the engine is less exposed to ingress of dust and other detritus than the magneto side of the engine where a cooling air fan may induce such substances into the engine, potentially causing damage. The ring gear in such an engine is mounted directly on the crankshaft or is integrally formed on parts of the CVT such as the outer half of the driving pulley of the CVT. Nevertheless, engines provided with a starting system having a bendix drive, where the ring gear is fitted on the CVT side proximate the CVT, have certain disadvantages. Where the ring gear is mounted on the crankshaft on the CVT side of the engine, length of the crank shaft is increased. Such an increase in crankshaft length is detrimental to the engine since CVT pulleys get shifted away from the crankshaft bearing on the CVT side. This leads to increased load and consequent stresses on this crankshaft bearing which reduce the life of the bearing. In addition, the increased length of the crankshaft increases the width of the engine, increasing its bulk and possibly leading to loss of fuel economy. On the other hand, where the ring gear is integrally formed on rotating parts of the CVT, such as the outer half of the driving pulley of the CVT, dust caused by movement of the moving belt may damage the bendix drive, as the bendix drive has to be located across the belt to reach to outer half of the driving pulley. It is the object of the present invention to provide an internal combustion engine with a continuously variable transmission less subject to the aforementioned problems of engine packaging and particulate damage to bendix drive and ring gear caused during operation of the CVT. With this object in view, the present invention provides an internal combustion engine having a continuously variable transmission; a starting system comprising a starter motor, a ring gear and a ring gear drive operable on starting of the engine, and a crankshaft having a first section and a second section wherein the continuously variable transmission is connected to the first section of the crankshaft and the ring gear of the starting system is connected to the second section of the crankshaft distal from the continuously variable transmission. The first section of the crankshaft corresponds with the CVT side of the engine where the CVT is fitted. The second section corresponds with the non-CVT side of the engine where the magneto is typically located. In addition, in a forced air cooled engine, a fan for directing cooling air over engine components such as cylinders and cylinder heads is located on this non-CVT side of the engine. The ring gear may be connected to a rotor of the magneto, the rotor being connected to the crankshaft of the engine. The ring gear may be accommodated within the width of the rotor. The ring gear drive may be a bendix drive of conventional construction. The ring gear may be connected to, or formed integral with, the magneto rotor, at a spacing from the fan as described in the Applicant's co-pending Indian Provisional Application 40/MUM/2006 filed 10 January 2006, the contents of which are hereby incorporated by reference, avoiding obstruction of cooling air flow and allowing more efficient cooling. In such case, also, a dust separator may separate the bendix drive and ring gear from the cooling air intake system and fan making dust damage to bendix drive and ring gear much less likely. The internal combustion engine of the invention has several potential advantages. First, a reduction in the overall width of the engine may be achieved with resultant better engine packaging. Second, it may be possible to reduce the weight of the ring gear, by accommodating it within the width of the magneto rotor, consequently reducing the weight of engine and vehicle for a given engine capacity thus achieving greater fuel economy. Stresses on crankshaft bearings may also be reduced increasing bearing life. The internal combustion engine with continuously variable transmission of the invention may be more fully understood from the following description of preferred embodiments thereof made with reference to the accompanying drawings in which: Figure 1 illustrates a sectional view of a typical engine having CVT and a starter motor according to prior art. Figure 2 illustrates a partial view of a typical engine having CVT with ring gear integrally formed on one of the halves of the driving pulley. Figure 3 illustrates a sectional view of a typical engine having a CVT and start motor with bendix drive according to the invention. Referring now to Figure 1, there is shown a prior art internal combustion engine 10 for a motor scooter, wherein a crankshaft 120 having a first section 12 and a second section 13 is assembled in crankcase 11. Starter motor 16 is also assembled with crankcase 11. The engine 10 has a continuously variable transmission (CVT) 107 and CVT components such as the driving pulley 18 are mounted on the first section 12 of the crank shaft 120. A ring gear 14 is also connected to the first section 12 of crank shaft 120 and driven through a one way clutch arrangement 15 in a known manner. The ring gear 14 is driven by the starter motor 16, at the time of starting. Magneto rotor 41 is mounted to the second section 13 of crankshaft 120. Second section 13 of crankshaft 120 corresponds with a non-CVT side of engine 10. Cooling fan 125 is mounted to the magneto rotor 41 on this non-CVT side of engine 10. The crankshaft 120 has bearings 122 and 124, bearing 122 of which is subjected to increased stresses due to the load acting on first section 12 of crankshaft 120. Figure 2 illustrates a partial view of a typical prior art engine 100 showing the ring gear 17 integrally formed on one of the halves of driving pulley 18 of the CVT 107. In such engines employing a CVT transmission, and having a starting system with a bendix drive, the starter motor 116 and bendix drive 117 are mounted on the same section of crankshaft 120 as the CVT 107. So, during starting of engine 100, the bendix drive 117 meshes with ring gear 17 driving it until the engine 100 reaches a predetermined speed at which the bendix drive 117 disengages from ring gear 17. In such an arrangement, dust generated by movement of the CVT belt (not shown) may damage the bendix drive 117. Figure 3 illustrates a partial sectional view of an engine 200 according to the present invention again having a crankshaft 220 comprising a first section 22 and second section 23 assembled in crankcase 21. A driving pulley 31 of CVT 27 is connected to first section 22 of crankshaft 220. A magneto rotor 28 is connected, conventionally, to second section 23 of crankshaft 220. However, contrary to prior practice, ring gear 29 co-operable with the bendix drive 26 during starting, is welded on the outer surface 28a and on the extreme inner edge 28b of magneto rotor 28. This location is on the non-CVT side of engine 200 distal from CVT 27 and, in particular, distal from the driving pulley 31 and belt which generates dust which could damage a bendix drive such as bendix drive 117 of Figure 2. The starter motor 24 is assembled in starter motor housing 25 along with bendix drive 26. The starter motor housing 25 is assembled to crankcase 21. On starting of the engine 200, the driving gear (not separately shown) engages with ring gear 29 when starter motor 24 is actuated, the starting system itself operating in the conventional manner. However, the location of the ring gear 29 on the non-CVT side of engine 200 makes it possible to reduce the length of first section 22 of crankshaft 220 since the width of ring gear 29 is accommodated within the width of the magneto rotor 28 mounted on the second section 23 of the crankshaft 220. Further, as driving pulley 31 of CVT 27 is shifted towards the bearing 32 by at least a value equal to the width of the ring gear 29, reducing bearing stresses, bearing 32 life may be improved. Also, the weight of ring gear 29 is reduced by mounting it on a large diameter of the outer periphery 28a of the magneto rotor 28, a diameter greater than the diameter of the crankshaft 120 where it was mounted in the prior art engine 10 shown in Figure 1. In addition, the bendix drive 26 may no longer be subject to damage from dust generated by the belt of CVT 27 which is located distal to it on the other side of the engine 200. Figure 3 also shows that the ring gear 29 and bendix drive 26 may be protected by a dust cover 50, a portion 51 of which extends between the ring gear 29 and cooling fan 225 to form a seal. Thus, dust and other detritus sucked into the engine 200 by cooling fan 225 is less likely to enter and damage the ring gear 29 and bendix drive 27. 6 Modifications and variations of the internal combustion engine with continuously variable transmission of the present invention may be apparent to the skilled reader of this disclosure. Such modifications and variations are deemed to be within the scope of the invention. claim : 1. An internal combustion engine having a continuously variable transmission; a starting system comprising a starter motor, a ring gear and a ring gear drive operable on starting of the engine, and a crankshaft having a first section and a second section wherein the continuously variable transmission is connected to the first section of the crankshaft and the ring gear of the starting system is connected to the second section of the crankshaft distal from the continuously variable transmission. 2. The engine of claim 1 wherein the first section of the crankshaft corresponds with the CVT side of the engine where the CVT is fitted and the second section of the crankshaft corresponds with the non-CVT side of the engine. 3. The engine of claim 2 wherein the magneto is located in said second section of the crankshaft. 4. The engine of claim 2 or 3 wherein the engine is a forced air cooled engine and a fan for directing cooling air over engine components is connected to the said second section of the crankshaft. 5. The engine of claim 3 wherein said ring gear is connected to a magneto rotor. 6. The engine of claim 5 wherein the ring gear is accommodated within the width of the magneto rotor. 7. The engine of any one of the preceding claims wherein the ring gear drive is a bendix drive. An internal combustion engine substantially as hereinbefore described with reference to Figure 3. Dated this 5th day of January 2007

Full Text

FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Internal combustion engine with continuously variable transmission
APPLICANTS
Name : Bajaj Auto Limited
Nationality : Indian Company
Address : Akurdi, Pune 411035, Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

This invention relates to an internal combustion engine having a continuously variable transmission.
An engine used as a prime mover in 2 or 3 wheeled vehicles is typically provided with either a kick start or an electric start. The starting system employed in such vehicles normally has two configurations. Either the starting system operates through a one way clutch or the starting system has what is commonly known as a 'bendix' drive. In the latter case, the starter motor and bendix drive are fixed on the engine crankcase. The magneto is mounted on the crankshaft and rotary motion of the crankshaft is transmitted to a magneto rotor through a key. The magneto generates electricity for operation of ignition, lighting and signaling systems of the vehicle. The output shaft of the starter motor engages with the bendix drive, which in turn engages with the ring gear. When the starter motor is actuated, the motor drives the ring gear. This drives the crankshaft which enables the engine to start. Once the engine has attained a predetermined speed, the bendix drive disengages from the ring gear.
Some vehicles of the above type use a continuously variable transmission (CVT). A CVT is a mechanical device in which the torque transmission ratio is infinitely variable over a certain working range. This contrasts with a conventional geared transmission which has a limited number of selectable torque transmission ratios. A CVT automatically changes the torque transmission ratio depending on engine load and speed conditions. To this end, the CVT typically comprises of a driving pulley connected to a first half of a crankshaft of the engine, a driven pulley connected to wheels and a drive belt transmitting torque from the driving pulley to the driven pulley. In some CVT designs, the driving pulley comprises of a centrifugal mechanism that varies the torque transmission ratio depending upon the speed of the driving pulley.
Conventionally, when an engine with a CVT is required to be provided with a starter motor, the ring gear of the starting system is provided on the same side of the engine as that on which the CVT is fitted. This side of the engine is less exposed to ingress of dust and other detritus than the magneto side of the engine where a cooling air fan

may induce such substances into the engine, potentially causing damage. The ring gear in such an engine is mounted directly on the crankshaft or is integrally formed on parts of the CVT such as the outer half of the driving pulley of the CVT. Nevertheless, engines provided with a starting system having a bendix drive, where the ring gear is fitted on the CVT side proximate the CVT, have certain disadvantages. Where the ring gear is mounted on the crankshaft on the CVT side of the engine, length of the crank shaft is increased. Such an increase in crankshaft length is detrimental to the engine since CVT pulleys get shifted away from the crankshaft bearing on the CVT side. This leads to increased load and consequent stresses on this crankshaft bearing which reduce the life of the bearing. In addition, the increased length of the crankshaft increases the width of the engine, increasing its bulk and possibly leading to loss of fuel economy.
On the other hand, where the ring gear is integrally formed on rotating parts of the CVT, such as the outer half of the driving pulley of the CVT, dust caused by movement of the moving belt may damage the bendix drive, as the bendix drive has to be located across the belt to reach to outer half of the driving pulley.
It is the object of the present invention to provide an internal combustion engine with a continuously variable transmission less subject to the aforementioned problems of engine packaging and particulate damage to bendix drive and ring gear caused during operation of the CVT.
With this object in view, the present invention provides an internal combustion engine having a continuously variable transmission; a starting system comprising a starter motor, a ring gear and a ring gear drive operable on starting of the engine, and a crankshaft having a first section and a second section wherein the continuously variable transmission is connected to the first section of the crankshaft and the ring gear of the starting system is connected to the second section of the crankshaft distal from the continuously variable transmission.

The first section of the crankshaft corresponds with the CVT side of the engine where the CVT is fitted. The second section corresponds with the non-CVT side of the engine where the magneto is typically located. In addition, in a forced air cooled engine, a fan for directing cooling air over engine components such as cylinders and cylinder heads is located on this non-CVT side of the engine.
The ring gear may be connected to a rotor of the magneto, the rotor being connected to the crankshaft of the engine. The ring gear may be accommodated within the width of the rotor. The ring gear drive may be a bendix drive of conventional construction. The ring gear may be connected to, or formed integral with, the magneto rotor, at a spacing from the fan as described in the Applicant's co-pending Indian Provisional Application 40/MUM/2006 filed 10 January 2006, the contents of which are hereby incorporated by reference, avoiding obstruction of cooling air flow and allowing more efficient cooling. In such case, also, a dust separator may separate the bendix drive and ring gear from the cooling air intake system and fan making dust damage to bendix drive and ring gear much less likely.
The internal combustion engine of the invention has several potential advantages. First, a reduction in the overall width of the engine may be achieved with resultant better engine packaging. Second, it may be possible to reduce the weight of the ring gear, by accommodating it within the width of the magneto rotor, consequently reducing the weight of engine and vehicle for a given engine capacity thus achieving greater fuel economy. Stresses on crankshaft bearings may also be reduced increasing bearing life.
The internal combustion engine with continuously variable transmission of the invention may be more fully understood from the following description of preferred embodiments thereof made with reference to the accompanying drawings in which:
Figure 1 illustrates a sectional view of a typical engine having CVT and a starter motor according to prior art.

Figure 2 illustrates a partial view of a typical engine having CVT with ring gear integrally formed on one of the halves of the driving pulley.
Figure 3 illustrates a sectional view of a typical engine having a CVT and start motor with bendix drive according to the invention.
Referring now to Figure 1, there is shown a prior art internal combustion engine 10 for a motor scooter, wherein a crankshaft 120 having a first section 12 and a second section 13 is assembled in crankcase 11. Starter motor 16 is also assembled with crankcase 11. The engine 10 has a continuously variable transmission (CVT) 107 and CVT components such as the driving pulley 18 are mounted on the first section 12 of the crank shaft 120. A ring gear 14 is also connected to the first section 12 of crank shaft 120 and driven through a one way clutch arrangement 15 in a known manner. The ring gear 14 is driven by the starter motor 16, at the time of starting. Magneto rotor 41 is mounted to the second section 13 of crankshaft 120. Second section 13 of crankshaft 120 corresponds with a non-CVT side of engine 10. Cooling fan 125 is mounted to the magneto rotor 41 on this non-CVT side of engine 10. The crankshaft 120 has bearings 122 and 124, bearing 122 of which is subjected to increased stresses due to the load acting on first section 12 of crankshaft 120.
Figure 2 illustrates a partial view of a typical prior art engine 100 showing the ring gear 17 integrally formed on one of the halves of driving pulley 18 of the CVT 107. In such engines employing a CVT transmission, and having a starting system with a bendix drive, the starter motor 116 and bendix drive 117 are mounted on the same section of crankshaft 120 as the CVT 107. So, during starting of engine 100, the bendix drive 117 meshes with ring gear 17 driving it until the engine 100 reaches a predetermined speed at which the bendix drive 117 disengages from ring gear 17. In such an arrangement, dust generated by movement of the CVT belt (not shown) may damage the bendix drive 117.

Figure 3 illustrates a partial sectional view of an engine 200 according to the present invention again having a crankshaft 220 comprising a first section 22 and second section 23 assembled in crankcase 21. A driving pulley 31 of CVT 27 is connected to first section 22 of crankshaft 220. A magneto rotor 28 is connected, conventionally, to second section 23 of crankshaft 220. However, contrary to prior practice, ring gear 29 co-operable with the bendix drive 26 during starting, is welded on the outer surface 28a and on the extreme inner edge 28b of magneto rotor 28. This location is on the non-CVT side of engine 200 distal from CVT 27 and, in particular, distal from the driving pulley 31 and belt which generates dust which could damage a bendix drive such as bendix drive 117 of Figure 2. The starter motor 24 is assembled in starter motor housing 25 along with bendix drive 26. The starter motor housing 25 is assembled to crankcase 21. On starting of the engine 200, the driving gear (not separately shown) engages with ring gear 29 when starter motor 24 is actuated, the starting system itself operating in the conventional manner. However, the location of the ring gear 29 on the non-CVT side of engine 200 makes it possible to reduce the length of first section 22 of crankshaft 220 since the width of ring gear 29 is accommodated within the width of the magneto rotor 28 mounted on the second section 23 of the crankshaft 220. Further, as driving pulley 31 of CVT 27 is shifted towards the bearing 32 by at least a value equal to the width of the ring gear 29, reducing bearing stresses, bearing 32 life may be improved. Also, the weight of ring gear 29 is reduced by mounting it on a large diameter of the outer periphery 28a of the magneto rotor 28, a diameter greater than the diameter of the crankshaft 120 where it was mounted in the prior art engine 10 shown in Figure 1.
In addition, the bendix drive 26 may no longer be subject to damage from dust generated by the belt of CVT 27 which is located distal to it on the other side of the engine 200. Figure 3 also shows that the ring gear 29 and bendix drive 26 may be protected by a dust cover 50, a portion 51 of which extends between the ring gear 29 and cooling fan 225 to form a seal. Thus, dust and other detritus sucked into the engine 200 by cooling fan 225 is less likely to enter and damage the ring gear 29 and bendix drive 27.
6

Modifications and variations of the internal combustion engine with continuously variable transmission of the present invention may be apparent to the skilled reader of this disclosure. Such modifications and variations are deemed to be within the scope of the invention.

claim :
1. An internal combustion engine having a continuously variable transmission; a starting system comprising a starter motor, a ring gear and a ring gear drive operable on starting of the engine, and a crankshaft having a first section and a second section wherein the continuously variable transmission is connected to the first section of the crankshaft and the ring gear of the starting system is connected to the second section of the crankshaft distal from the continuously variable transmission.
2. The engine of claim 1 wherein the first section of the crankshaft corresponds with the CVT side of the engine where the CVT is fitted and the second section of the crankshaft corresponds with the non-CVT side of the engine.
3. The engine of claim 2 wherein the magneto is located in said second section of the crankshaft.
4. The engine of claim 2 or 3 wherein the engine is a forced air cooled engine and a fan for directing cooling air over engine components is connected to the said second section of the crankshaft.
5. The engine of claim 3 wherein said ring gear is connected to a magneto rotor.
6. The engine of claim 5 wherein the ring gear is accommodated within the width of the magneto rotor.
7. The engine of any one of the preceding claims wherein the ring gear drive is a bendix drive.

An internal combustion engine substantially as hereinbefore described with reference to Figure 3.
Dated this 5th day of January 2007

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Patent Number

268465

Indian Patent Application Number

39/MUM/2006

PG Journal Number

36/2015

Publication Date

04-Sep-2015

Grant Date

31-Aug-2015

Date of Filing

10-Jan-2006

Name of Patentee

BAJAJ AUTO LTD.

Applicant Address

Akurdi, Pune 411035

Inventors:

#	Inventor's Name	Inventor's Address
1	JOSEPH ABRAHAM	Bajaj Auto Ltd, Akurdi, Pune 411035
2	RAJAGOPALAN NARASIMHAN	Bajaj Auto Ltd, Akurdi, Pune 411035

PCT International Classification Number

F02N15/02

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA