WO2013036779A1

WO2013036779A1 - All wheel drive motorcycle with front wheel overdrive

Info

Publication number: WO2013036779A1
Application number: PCT/US2012/054185
Authority: WO
Inventors: Martin E. Lawson; William E. Lawson
Original assignee: Lawson Martin E; Lawson William E
Priority date: 2011-09-07
Filing date: 2012-09-07
Publication date: 2013-03-14
Also published as: WO2013036779A9

Abstract

The present disclosure includes an all wheel drive motorcycle (10) having an internal combustion engine (18) with an output shaft (20) extending from the engine (18). The output shaft (20) provides power to a rear wheel drive train (22) and a front wheel drive train (24). The rear wheel drive train (22) and the front wheel drive train (24) are coupled together with a planetary differential (52) that allocates selected amounts of power to the front and back wheels (16) and (14). The planetary differential (54) and is geared to provide a selected amount of overdrive to the front wheel 16 relative to the back wheel (14).

Description

ALL WHEEL DRIVE MOTORCYCLE WITH FRONT WHEEL OVERDRIVE

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit U.S. Provisional Application Serial No.

61/531,756 filed on September 7, 2011, the contents of which are incorporated by reference in its entirety.

[0002] This application claims the benefit U.S. Provisional Application Serial No.

61/535,440 filed on September 16, 2011, the contents of which are incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0003] The present invention relates to a two-wheel vehicle such as a motorcycle. More particularly, the present invention relates to an all wheel drive motorcycle.

BACKGROUND OF THE INVENTION

[0004] Many people enjoy riding motorcycles on the road as well as off road. When driving a motorcycle off road, the motorcycle typically encounters rough terrain and obstacles. Many times the driver will have difficulty maintaining the control of the motorcycle when encountering the rough terrain and obstacles because the front wheel suspension cannot adequately adjust to compensate for the unevenness of the terrain or the height of the obstacle. U.S. Patent No. 8,042,641, which names Martin E. Lawson as the inventor and issued on October 25, 2011, describes a suspension and drive system for an all wheel drive motorcycle that overcomes many of these deficiencies, the contents of which are incorporated by reference in its entirety.

[0005] One way to maintain control of a motorcycle while riding off road is to provide a drive force to the front wheel. When a drive force is imparted on the front wheel, the front wheel actively engages the obstacle or uneven terrain. The active engagement of the front wheel with the obstacle or uneven terrain allows the driver maintain better control of the motorcycle when compared to a single wheel drive motorcycle encountering the same obstacle. However, as a front wheel of an all wheel drive motorcycle is turned or cornered, a torque steer is typically created if the drive system is not designed to eliminate torque steer which makes turning an all wheel drive motorcycle very difficult. [0006] An all wheel drive motorcycle can also encounter bump steer when the front wheel engages an obstacle. Bump steer is the unwanted turning of the front wheel and fork caused by the front wheel drive train when the front wheel engages the obstacle.

[0007] Motorcycles, including all wheel drive motorcycles, also have difficulty maneuvering in soft terrain, such as sand. When the front wheel is turned at an angle to the direction of motion to balance or turn the motorcycle the front wheel tends to plow into the soft terrain because the front wheel tends to push straight ahead, instead of the power and traction of the front wheel pulling the front end of the motorcycle in the desired direction. The plowing effect is caused by the fact that the wheel is not capable of faster rotation required to turn the motorcycle because of the increased relative speed of the front wheel relative to the ground due to the vector addition of the forward motion caused by the rear wheel speed and the sideways translation of the front wheel. Thus the front wheel must be driven faster than the rear wheel or "overdriven" in order to stop the front wheel from plowing. In this application, overdrive means that one wheel is driven faster than the other wheel due to the action of a differential.

SUMMARY

[0008] One aspect of the present disclosure includes an all wheel drive motorcycle. The motorcycle includes an internal combustion engine having an output shaft extending from the engine. The output shaft provides power to a rear wheel drive train and a front wheel drive train. The rear wheel drive train and the front wheel drive train are coupled together with a planetary differential that allocates selected amounts of power to both the front and back wheels and is geared to provide a selected amount of overdrive to the front wheel or to the back wheel as needed.

[0009] Another aspect of the present disclosure includes an all wheel drive motorcycle.

The motorcycle includes an internal combustion engine having an output shaft extending from the engine. The output shaft provides power to a rear wheel drive train and a front wheel drive train. The rear wheel drive train and the front wheel drive train are coupled together with a differential that allocates selected amounts of power to the front wheel and the back wheel and is geared to provide an overdrive to either wheel, as necessary. A pair of clutches are also coupled to the front wheel drive train and the rear wheel drive train. In the event that either the front wheel or rear wheel begins to slip beyond a selected upper range or lower range relative to the other wheel, one of the clutches is moved to an engaged position and prevents the differential from supplying excessive power to the slipping wheel, which would effectively cause the motorcycle to stop moving.

[0010] Another aspect of the present disclosure includes an all wheel drive motorcycle.

The motorcycle includes an internal combustion engine having an output shaft extending from the engine. The output shaft provides power to a rear wheel drive train and a front wheel drive train. The rear wheel drive train and the front wheel drive train are coupled together with a differential allocates the selected amounts of power to both the front wheel and the back wheel, for example 33% of the power being allocated to the front wheel drive train and 67% of the power being allocated to the rear wheel drive train and is geared to provide an overdrive to the either wheel. A clutch is also coupled to the front wheel drive train and the rear wheel drive train. In the event that either the front wheel or rear wheel begins to slip beyond a selected range relative to the other wheel, the clutch is moved to an engaged position and prevents the differential from supplying excessive power to the slipping wheel, which would effectively cause the motorcycle to stop moving.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a schematic view of an all wheel drive motorcycle.

[0012] FIG. 2 is a schematic view of a power allocation system for the all wheel drive motorcycle.

DETAILED DESCRIPTION

[0013] An all wheel drive motorcycle is schematically illustrated in FIG. 1 at 10. The motorcycle 10 includes a frame 12 that supports an internal combustion engine 18, a rear or back wheel 14 and a front wheel 16. An output shaft 20 extends from the engine 18 where the output shaft 20 provides power to the back wheel 14 and the front wheel 16 through a back wheel drive train 22 and a front wheel drive train 24, respectively, through a power allocation system 26. The power allocation system 26 is coupled to the output shaft 20 with a chain 27 that engages a sprocket 25. The sprocket 25 is non-rotatably attached to an input shaft 54 to a differential 52.

[0014] The present disclosure provides that power is supplied to the front wheel 16 at all times. Having power supplied to the front wheel 16 at all times provides for better directional control as the front wheel 16 is pulling the motorcycle 10 in the direction of the front wheel in all situations. In contrast, conventional all wheel drive systems only supply power to the front wheel when slippage in the back wheel is detected. The intermittent supply of power to the front wheel can be unreliable and unresponsive, especially at slower speeds.

[0015] Referring to FIGS. 1 and 2, the rear wheel drive train 22 includes a rear drive sprocket 30 that is within the power allocation system 26. A rear wheel drive chain 28 is attached to the rear drive sprocket 30 and a rear axle sprocket 32 that is non-rotatably attached to a back hub 34. The rear wheel 14 is non-rotatably attached to the rear hub 32 such that the rear wheel drive train 22 transfers force from the engine 18 through the power allocation system 26 to the back wheel 14 of the motorcycle 10.

[0016] The power allocation system 26 provides power to the front wheel 16 through the front wheel drive train 24. The front wheel drive train 24 includes a front chain 34 that is coupled to an intermediate fork sprocket 38 that is non-rotatably secured to a left stub shaft 40 where the left stub shaft 40 is positioned proximate a top end of a front fork 42 that supports the front wheel 16. A second sprocket (not shown) is non-rotatably coupled to the stub shaft 40 where a second front chain 44 is coupled to the second sprocket (not shown) and a front wheel hub sprocket 46 non-rotatably attached to a front wheel hub 48.

[0017] Referring to FIG. 2, the power allocation system 26 includes the differential 52 which is housed inside the housing 53. The sprocket 30, sprocket 60 and housing 53 all are fixably attached to the left/rear output shaft where power is supplied to the differential through the input shaft 54. Power is output through having a left shaft (not shown) to housing 53 and a right shaft 56. The left shaft (not shown) provides power to the rear wheel drive train 22 and the right shaft 56 provides power to the front wheel drive train 24. The input and right shafts 52 and 56, respectively, are attached to the frame of the motorcycle with left and right plates that house bearings that engage the input and right shafts 52 and 56, respectively.

[0018] The differential 52 distributes power to the rear wheel drive train 22 through the sprocket 30 that is coupled to the chain 28 where the sprocket 30 is non-rotatably coupled to the differential 52 with the left shaft/housing 53 (not shown). The type of differential 52 that is contemplated is a planetary differential. However, other types of differentials are also contemplated.

[0019] The differential 52 distributes power to the front wheel drive train 22 through either a sprocket 58 non-rotatably attached to the shaft 56 or a sprocket 60 that is non-rotatably attached to the differential left output shaft/housing 53 and sprocket 30. The sprocket 60 includes an internal clutch 62 that is freewheeling until a lower setpoint of a ratio of the rotational speeds of the shafts is reached. (Note: all clutches are assumed to be one way clutches or ratchets unless otherwise identified.) Once the lower setpoint is reached, the internal clutch engages and causes the sprocket 60 to become a drive sprocket. Therefore, the ratcheting clutch 62 interconnects the left output and right shafts 53 and56 respectively.

[0020] A first power supply chain 64 is coupled to the sprocket 58 and a first top sprocket 66 where the first top sprocket 66 is supported by a shaft 68 that is rotatably secured with bearing housed in mounting plates attached to the frame of the motorcycle 10. A second power supply chain 70 is coupled to the sprocket 60 attached to the differential housing/shaft 53and a second top sprocket 72 attached to the shaft 68. The top sprocket 72 includes a second internal clutch that is freewheeling until an upper setpoint between the ratios of the rotational speeds of the shafts (not show) and 56 reach an upper predefined setpoint, at which time the clutch engages the and the sprocket 72 becomes a drive sprocket. Depending upon the relative rotational speeds of the rear drive shaft 53 (not shown) and right shaft 56, respectively, either clutch in the sprocket 60 or 72 engage and lock the differential 52 or be free wheeling so that either the first or second power supply chains 64 or 70, respectively provides power to the front wheel drive train through the chain 34 coupled to a sprocket 33 non-rotatably secured to the shaft 68.

[0021] The differential 52 is geared to provide first and second selected amounts of power to the front and back wheels 16 and 14, respectively. The differential 52 is typically geared to provide about 33% of the power or torque to the front wheel drive train 24 and about 67% of the power or torque to the rear wheel drive train 22. However, the ratio of power or torque provided to the front wheel drive train 24 and the rear wheel drive train 22 can be adjusted depending upon the weight of the motorcycle 10, the terrain in which the motorcycle 10, the weather and many other factors. The ratio of power or torque provided to the front wheel drive train 24 and the rear wheel drive train 22 can range from about 1/1 or 50%/50% to 1/99 or l%/99%, respectively.

[0022] The differential 52 and the front wheel drive train 24 are geared to provide the front wheel 16 with a selected overdrive relative to the back wheel 14. The overdrive can range from about 0.01% to about 10% and more typically the overdrive can range from about 3% to about 7%. A typical overdrive of the front wheel 16 relative to the back wheel 14 is about 5% meaning that the front wheel 16 can rotate about 5% faster than the back wheel 14. The overdrive allows the front wheel 16 of the motorcycle to be more easily steered in loose terrain, such as sand, and prevents the front wheel 16 from plowing in the loose terrain while turning or cornering. However, the overdrive of the front wheel 16 relative to the rear wheel 14 is sufficiently small to not affect the handling of the motorcycle during operation on roads and/or flat, hard surfaces.

[0023] Whiling gearing the differential 52 and the front wheel drive train 24 to provide the overdrive of the front wheel is contemplated, other mechanisms can be utilized to provide the overdrive to the front wheel 16. Exemplary mechanisms to provide an overdrive to the front wheel 16 include electric or hydraulic motors that supply additional power to the front wheel. However, these mechanisms are more complicated than the described gearing of the differential 52 inside housing/shaft 53 and the front wheel drive train 24.

[0024] As previously stated, an exemplary, but non-limiting, ratio of power split would be in the range of 33% of the power being directed to the front drive train 24 and 67% of the power being directed to the rear drive train 22. However, when the torque allocated to the wheels 14 and 16 does not correlate to the traction split between the wheels, such as when the front wheel 16 is lifted, then all of the power would be allocated to the front wheel 16 and no power would be allocated to the rear wheel 14. Conversely, if the back wheel 14 is in wet or slippery terrain while the front wheel 16 has traction, then all the power would be allocated to the back wheel 14 and no power would be allocated to the front wheel 16. This could cause significant problems for the driver and could cause the motorcycle to stop moving forward.

[0025] In order to overcome the problems associated with wheel slippage in a planetary differential 52, the upper and lower clutches are utilized which interconnects the rear drive shaft (not shown) and right drive shaft 56 respectively, that provide power to the rear wheel drive train 22 and the front wheel drive train 24, respectively. The ratcheting clutches within the sprockets 60 and 72 are utilized to control the amount of power or torque supplied to the front and back wheels 16 and 14, respectively, based upon the difference in speed between the left shaft (not shown) and the right shaft56, respectively.

[0026] The clutches are free wheeling and allow for the front drive train 24 and the rear drive train 22 to operate freely when the rotational speed of right shaft 56 is within a set range relative to the rotational speed of the left shaft (not shown). The ratio of the speeds of the rear drive shaft (not shown) and right drive shaft 56 without slippage is predetermined through the gearing of the differential 52. An exemplary ratio is 1.1: 1 of the right shaft 56 relative to the left shaft (not shown). However other ratios are also contemplated.

[0027] However, when slippage of either the front or back wheel 16 and 14, respectively, occurs so that the ratio of the speed of the shafts (not shown) and 56 varies by predetermined percentage, such as for example 10% in either direction from a set point, such that the ratio is 1: 1 or 1.2: 1. When the predetermined lower limit is reached, then the ratcheting clutch 62 within the sprocket 60 engages and prevents further variation from the predetermined ratio of the rotational speeds of the left and right shafts (not shown) and 56, respectively. When the predetermined upper limit is reached, then the ratcheting clutch with the sprocket 72 engages and prevents further variation from the predetermined ratio of the rotational speeds of the left and right shafts (not shown) and 56, respectively. By way of example a ratio 1.2: 1 of left and right shafts (not shown) and 56, correlates the speed of the front wheel being about 20% faster than the speed of the back wheel.

[0028] With the ratcheting clutches disengaged, the ratcheting clutches are free wheeling and power is provided to the sprocket 33 and the front wheel drive chain 34 through the sprockets 58 and 66 and the chain 64 moves about the sprockets 72 and 60 as the clutches free wheel. With the ratcheting clutches disengaged, the chain 70 does not supply any power to the front wheel drive train 24. However, when the ratio of the rotational speed between the left shaft (not shown) and the right shaft 54 are outside of a selected upper limit or a selected lower limit, then one of the ratcheting clutches located within the sprockets 60 or 72 engages and locks the differential 52 and power is transferred to the sprocket 33 and chain 34 though the sprockets 60 and 72 with the chain 70 and the chain 64 rotating at the same speed as the chain 70.

[0029] The power delivery system 26 includes a slip clutch 50 or manually released clutch that allows the motorcycle to be pushed in a backward direction by allowing the slip clutch 50 to slip and thereby overcome the fact that the differential with upper and lower speed controls locks up when pushed in reverse. The slip clutch 50 is set to a maximum torque to drive the front wheel. There is a mechanical advantage around the front drive train chain and sprocket systems 70 + 64 such that the force required to reverse the drive or roll the motorcycle 10 backwards is small compared to the required drive torque for the front wheel drive 24. [0030] The placement of the clutch within the sprocket 60 and between the rear output shaft 53 and the output shaft 56 of the differential 52 provides for full torque to the rear wheel 14 under all conditions. An alternative that would allow the motorcycle to roll backward to the ratcheting clutch 62 would be to replace it with a clutch that is mechanically or electronically deactivated.

[0031] An exemplary ratcheting clutch for engaging when the upper predetermined ratio or the lower predetermined ration of the speeds of the shafts (not shown and 56) is a Sprag clutch. This type of ratcheting clutch does not require additional energy or cause disturbances into the steering action and feel of the motorcycle, relative other mechanisms such as a slip clutch or brake.

[0032] Other devices are contemplated to detect and correct for slippage, including but not limited electronically controlled clutches or brakes that detect speed differences and control the differential speed by incorporating an anti-slip differential. A computer would send signals to the clutch to provide the necessary overdrive to control the speed of the front wheel 16 relative to the back wheel 14.

[0033] However, the devices that control torque between the wheels, instead of control a defined difference in the speed ration between the wheels, can induce steering disturbances and affect and the feel and control of the motorcycle. Further, these devices add substantial complexity that can require additional maintenance and repair costs and do not perform consistently at slower speeds.

[0034] Referring to FIG. 2, the front wheel drive train 24 includes an overrunning ratchet that is located proximate the power allocation system 26. It is contemplated that the overrunning ratchet be located within the sprocket 33. However, the overrunning ratchet can be located anywhere within the front wheel drive train 24 including proximate the front wheel hub sprocket 46.

[0035] The placement of the overrunning ratchet in drive train 24 proximate the front wheel hub sprocket 46, while not illustrated, provides additional safety for the driver because in the event the engine, transmission or differential 52 fails and locks up, the overrunning ratchet will allow the front wheel 16 to continue spinning and aid in prevent the motorcycle 10 from suddenly stopping and causing the driver to catapult over the handle bars. [0036] Additionally, the use of overrunning ratchets as in the drive train 24 could allow for the reduction in the upper and lower limits for the differences in wheel speeds meaning that the ratio could possibly be reduce from around 1.21: 1 to around 1.05: 1 and thus minimize the potential for excessive wheel spinning that may occur when climbing a hill while still allowing for the free wheeling of the front wheel 16 in tight corners.

[0037] Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

CLAIMS:

1. An all wheel drive motorcycle comprising:

a frame;

an internal combustion engine supported by the frame;

a front wheel supported by the frame;

a back wheel supported by the frame; and

a power allocation system that provides a first selected amount of power to the front wheel and a second selected amount of power to the back wheel wherein the power allocation system is configured to provide a selected amount of overdrive to the front wheel relative to the back wheel.

2. The all wheel drive motorcycle of claim 1 and wherein the selected amount of overdrive to the front wheel relative to the back wheel is in a range of between about 0.01 and 10 percent.

3. The all wheel drive motorcycle of claim 1 and wherein the selected amount of overdrive to the front wheel relative to the back wheel is in a range of between about 3 and 7 percent.

4. The all wheel drive motorcycle of claim 1 and wherein the selected amount of overdrive to the front wheel relative to the back wheel is about 5 percent.

5. The all wheel drive motorcycle of claim 1 and wherein the power allocation system comprises:

a differential geared to provide the selected amount of overdrive to the front wheel relative to the back wheel with a first shaft and an output shaft;

an input shaft coupled to the differential and supplying power to the differential from the internal combustion engine;

a rear wheel drive sprocket coupled to the differential with the first shaft;

a first front wheel drive sprocket coupled to the differential;

a first ratcheting clutch operatively connected to the first front wheel drive sprocket; an output shaft coupled to the differential; and

a second front wheel drive sprocket attached to the output shaft and wherein the first ratcheting clutch is configured to engage the differential when a ratio of the speed of the first shaft to the input shaft exceeds a preset lower limit of a preset ratio of the rotational speed of the first shaft to the rotational speed of the output shaft and the first ratcheting clutch is configured to be in a disengaged position when the ratio of the rotational speed of the output shaft to the first shaft is above the preset lower limit.

6. The all wheel drive motorcycle of claim 5 and further comprising a second ratcheting clutch operatively connected to the first ratcheting clutch wherein the second ratcheting clutch is configured to engage the differential when a ratio of the speed of the first shaft to the input shaft exceeds a preset upper limit of a preset ratio of the rotational speed of the first shaft to the rotational speed of the output shaft and the second ratcheting clutch is configured to be in a disengaged position when the ratio of the rotational speed of the output shaft to the first shaft is below the present upper limit.

7. The all wheel drive motorcycle of claim 1 and wherein the preset upper limit of the speed of the output shaft to the first shaft is about 1.2: 1 and wherein the preset lower limit of the speed of the output shaft to the first shaft is about 1: 1.

8. The all wheel drive motorcycle of claim 6 and wherein the second front wheel drive sprocket provides power to the front wheel when the first and second ratcheting clutches are disengaged and wherein the first front wheel drive sprocket provides power to the front wheel when either the first or second ratcheting clutches are engaged.

9. The all wheel drive motorcycle of claim 5 and wherein the differential comprises a planetary differential.

10. The all wheel drive motorcycle of claim 6 and wherein the first and second ratcheting clutches comprise a Sprag clutch.

11. The all wheel drive motorcycle of claim 5 and further comprising an overrunning ratchet within a power train to the front wheel proximate the front wheel.

12. A power allocation system configured for use with a motorcycle having a frame, an internal combustion engine supported by the frame and having an output shaft, a front wheel supported by the frame and a back wheel supported by the frame, the power allocation system comprising:

an input shaft configured to engage the output shaft of an internal combustion engine; a differential coupled to the input shaft and configured to provide a first selected amount of power to the front wheel through an output shaft and a second selected amount of power to the back wheel through a first shaft;

a back wheel drive sprocket attached to the first shaft and adapted to deliver the second selected amount of power to the back wheel;

a first front wheel drive sprocket coupled to the differential;

a first ratcheting clutch coupled to the first front wheel drive sprocket and positionable between a first position wherein the clutch is freewheeling and a second position wherein the clutch engages and locks the differential such that the first front wheel drive sprocket delivers the first selected amount of power to the front wheel when a ratio of the speed of the output shaft relative to the first shaft reaches a predefined lower limit;

a second ratcheting clutch coupled to the first ratcheting clutch and positionable between a first position wherein the clutch is freewheeling and a second position wherein the clutch engages and locks the differential such that the first front wheel drive sprocket delivers the first selected amount of power to the front wheel when a ratio of the speed of the output shaft relative to the first shaft reaches a predefined upper limit; and

a second front wheel drive sprocket attached to the output shaft, the second drive wheel sprocket configured to deliver the second selected amount of power to the front wheel when the first and second ratcheting clutches are in the first position.

13. The power allocation system of claim 12 and wherein the differential comprises a planetary differential wherein the planetary differential is geared to provide a selected of rotational ratio of the output shaft rotational speed to the first shaft rotational speed wherein the ratio exceeds 1: 1.

14. The power allocation system of claim 13 and wherein the planetary differential is geared to provide a selected of rotation ration of the output shaft speed to the first shaft speed wherein the ratio is about 1.1: 1.

15. The power allocation system of claim 12 and wherein the predefined lower limit is about 1 : 1 and the predefined upper limit is about 1.2: 1.

16. The power allocation system of claim 12 and wherein the differential is geared to produce an overdrive of the front wheel relative to the back wheel.

15. The power allocation system of claim 14 wherein the differential is geared to produce about a 5% overdrive of the front wheel relative to the back wheel.

16. The power allocation system of claim 12 and wherein the first selected amount of power supplied to the front wheel ranges from about 1% to about 50% of the total power output by the internal combustion engine and wherein the second selected amount of power supplied to the back wheel ranges from about 50% to about 99% of the total power output by the internal combustion engine.

17. The power allocation system of claim 12 and wherein the first selected amount of power supplied to the front wheel is about 33% of the total power output by the internal combustion engine and wherein the second selected amount of power supplied to the back wheel is about 67% of the total power output by the internal combustion engine.

18. The power allocation system of claim 12 and wherein the first and second ratcheting clutch comprises a Sprag clutch.

19. The power allocation system of claim 12 and further comprising slip clutch or manually released clutch coupled to the first and second ratcheting clutches, the slip clutch configured to allow the motorcycle to be moved backward.