Parking gear assembly for an all terrain vehicle

A straddle-type vehicle includes a frame supporting front and rear wheels, a seat supported above the frame, and an engine having an output shaft. The engine is supported by the frame below the seat. A transmission is coupled to the output shaft. The transmission includes gears. A shift assembly is operatively connected to the engine and is displaceable over a predetermined distance upon application of a predetermined amount of force by a vehicle operator. The selective displacement of the shift assembly shifts the gears. A parking gear assembly is selectively displaceable along with the shift assembly to selectively engage one of the gears to prevent movement of the output shaft.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a parking gear assembly for locking an all terrain vehicle (ATV) in a park position.

2. Description of Related Art

Typically, an ATV includes front wheels and rear wheels suspended on a front end and on a rear end, respectively, of a body frame. Handlebars and a seat are mounted on the frame. A power unit such as an engine is also mounted on the frame and generates the power required to propel the ATV. A transmission is provided to transfer the power generated by the engine to the front wheels, the rear wheels or both the front and rear wheels to drive the ATV. Typically, the ATV operator moves the transmission to a neutral or geared position when the ATV is not in use. This can be dangerous as the ATV may move if parked on a hill, for example. There is no structure to prevent the output shaft of the engine from rotating. Accordingly, there exists a need to provide an ATV with a parking gear assembly to prevent movement of the output shaft of the engine and hence movement of the ATV when stopped.

Bombardier's TRAXTER® ATV includes a parking gear that is mounted on the output shaft. See U.S. Pat. No. 6,296,073, incorporated herein by reference. A need has developed in the art to provide a parking gear that is less expensive, yet just as reliable as the parking gear for the TRAXTER®.

SUMMARY OF THE INVENTION

It is one aspect of the present invention to provide a parking gear assembly for an ATV. According to one preferred embodiment of the present invention, a straddle-type vehicle includes a frame supporting front and rear wheels, a seat supported above the frame, and an engine having an output shaft. The engine is supported by the frame below the seat. A transmission is coupled to the output shaft. The transmission includes gears. A shift assembly is operatively connected to the engine and is displaceable over a predetermined distance upon application of a predetermined amount of force by a vehicle operator. The selective displacement of the shift assembly shifts the gears. A parking gear assembly is selectively displaceable along with the shift assembly to selectively engage one of the gears to prevent movement of the output shaft.

DETAILED DESCRIPTION OF ILLUSTRATED PREFERRED EMBODIMENTS

FIG. 1illustrates an engine10equipped with a parking gear assembly, generally indicated at12inFIGS. 3,4, and9–11of the present invention. In the illustrated embodiment, the engine10is a single cylinder, internal combustion engine with an associated continuously variable transmission (CVT)14. However, the engine10should not be limited to such CVT engine. Instead, the features of the present invention may be applied to any type of internal combustion engine, as would be appreciated by those skilled in the art. For example, the features of the present invention may be applied to a multiple cylinder, in-line, V-type, or opposed cylinder engine without deviating from the scope of the present invention.

Furthermore, while the present invention includes a CVT for use with a single cylinder engine, those skilled in the art would readily appreciate that the CVT could be easily used with any other type, style, or size of internal combustion engine. Moreover, while a CVT is preferred for use with the engine of the present invention, it would be readily appreciated by those skilled in the art that the standard gear shift could be substituted for the CVT without deviating from the scope of the present invention.

In addition, while the engine10, CVT14, and parking gear assembly12have been specifically designed for use with an ATV, which is the preferred use for the present invention, the present invention is not limited just to use on ATVs. To the contrary, the present invention may be used in any vehicle type, including cars, scooters, motorcycles, and other suitable vehicles.

As shown inFIGS. 1 and 3, the engine10includes a cylinder16, a piston18slidably mounted in the cylinder16, a crankshaft20, and a connecting rod22interconnecting the piston18and the crankshaft20. In the illustrated embodiment, the crankshaft20is mounted transversely to the centerline24of the engine10. The engine10may be provided within any suitable fuel delivery system without departing from the scope of the present invention (i.e., carburetor or fuel injection system).

The engine10is designed to be mounted preferably on a frame26of an ATV28. One possible design for the ATV28is shown in dotted lines inFIG. 2. As illustrated, the engine10is positioned between the front wheels30and the rear wheels32of the ATV28.

As illustrated inFIGS. 1 and 2, the engine10is provided with the CVT14, the moving components of which are enclosed within a cover34. The CVT14operatively communicates with an output shaft36through a bevel gear38to provide power to the front wheels30and rear wheels32of the ATV28. Motive power for the four-wheel drive is transmitted to the output shaft36via the bevel gear38. While the ATV28illustrated is all-wheel drive, the ATV28may be a front wheel or rear wheel drive variety. The output shaft36is adapted to project from both sides of the engine10so that both 4-wheel and 2-wheel drive modes may be accommodated.

As shown inFIG. 1, the CVT14includes a drive pulley40and a driven pulley42. The drive pulley40is fixedly connected to the crankshaft20such that torque is transmitted from the crankshaft20to the drive pulley40. A continuous belt43operatively connects the drive pulley40to the driven pulley42to permit torque transfer from the drive pulley40to the driven pulley42. The driven pulley42is fixedly connected to a driven shaft or countershaft44. The driven shaft44is drivingly engaged with a secondary shaft46that is drivingly engaged with the output shaft36. Thus, torque from the crankshaft20is transmitted from the drive pulley40to the driven pulley42via the belt43, from the driven pulley42to the driven shaft44, from the driven shaft44to the secondary shaft46, from the secondary shaft46to the output shaft36, and from the output shaft36to the front wheels30and rear wheels32of the. ATV28.

As shown inFIGS. 4 and 6, the driven shaft44and secondary shaft46each include a plurality of gears used for changing an operational speed of the ATV, i.e., accelerating/decelerating. Specifically, the driven shaft44includes a shift gear48operatively coupled thereto for common rotation about the driven shaft axis. The shift gear48is coupled to driven shaft44through axially aligned splines50,52on the inner surface of the shift gear48and the outer surface of the driven shaft44, respectively. The splines50,52prevent relative rotational movement between the shift gear48and the driven shaft44while permitting relative axial movement therebetween. Thus, the shift gear48is selectively movable along the driven shaft44between a first position (shown inFIGS. 11,12, and14) and a second position (shown inFIG. 13). A pinion gear54is mounted on the driven shaft44adjacent the shift gear48using a bearing56such that the gear54can rotate relative to the driven shaft44. The driven shaft44also includes a gear58that is machined directly thereon.

The secondary shaft46includes a shift gear62operatively coupled to the secondary shaft46for common rotation about the secondary shaft axis. The shift gear62is coupled to secondary shaft46through axially aligned splines64,66on the inner surface of the shift gear62and the outer surface of the secondary shaft46, respectively. The splines64,66prevent relative rotational movement between the shift gear62and the secondary shaft46while permitting relative axial movement therebetween. Thus, the shift gear62is selectively movable along the secondary shaft46between a first position (shown inFIGS. 11 and 13), a second position (shown inFIG. 12), and a third position (shown inFIG. 14). Pinion gears68,70are mounted on the secondary shaft46on opposing sides of the shift gear62using bearing72,74, respectively, such that the gears68,70can rotate relative to the secondary shaft46. The secondary shaft46also includes a bevel gear60that is drivingly interconnected with the gear38provided on the output shaft36. The output shaft36is rotatably supported within the engine10by ball bearings76,78.

Further, as shown inFIGS. 4 and 7, a reverse gear80is provided on a shaft82that extends between the driven shaft44and the secondary shaft46. The reverse gear80is mounted on the shaft82using a bearing85such that the reverse gear80can rotate relative to the shaft82.

As best shown inFIG. 11(showing a neutral position), the driven shaft44, secondary shaft46, and shaft82are positioned such that the shift gear48is engaged with the gear68, the gear54is engaged with the shift gear62, and the gear58is engaged with the gear70via the reverse gear80.

As shown inFIGS. 4 and 5, the shift gears48,62of the driven shaft44and secondary shaft46are controlled by shift forks84,86, respectively, to change the gear ratio of the transmission. Specifically, a shift shaft88supports the shift forks84,86. The shift fork84is operatively engaged with the shift gear48on the driven shaft44and the shift fork86is engaged with the shift gear62on the secondary shaft46. Each shift fork84,86includes a follower90,91that is received within a corresponding groove provided in a gear shift mechanism92.

As shown inFIGS. 4,5,9, and10, the gear shift mechanism92provides a three step gearshift. The gear shift mechanism92includes a toothed wheel gear94having five possible positions: park, reverse, neutral, high, and low. Via a selector shaft96, which is nonrotationally connected to the toothed gear94, transmission of the gear positions to a control shaft98is affected.

As illustrated inFIG. 8, the surface of the control shaft98includes two grooves100,102. The grooves100,102correspond to positions of the shift gears48,62, depending upon the position (i.e. rotation) of the control shaft98, which are selected via shift forks84,86to move into the correct position. More specifically, rotation of the toothed wheel gear94rotates the selector shaft96and the control shaft98nonrotationally connected thereto. As the control shaft98is rotated, the grooves100,102rotate therewith, which causes reciprocating movement of the shift forks84,86. The reciprocating movement of the shift forks84,86causes the shift gears48,62to move axially along the driven shaft44and the secondary shaft46, respectively.

As shown inFIGS. 3,4,9, and10, an index lever104interacts with the selector shaft96to enable identification of the five possible positions. Specifically, the index lever104has a roller106that is biased into engagement with the selector shaft96by a spring108. The selector shaft96has five recesses around the periphery thereof. The roller106of the index lever104engages within a selected one of the recesses, as the selector shaft96is rotated during rotation of the toothed wheel gear94, to signify one of the five positions. In the illustrated embodiment, three of the recesses are positioned adjacent one another to facilitate shifting between these positions (i.e., reverse, neutral, and high). The remaining two recesses are spaced from the adjacent three recesses so that inadvertent shifting to these two positions (i.e., park and low) is avoided.

A shift shaft assembly110is engaged with the gear shift mechanism92to control the shifting of gears, as shown inFIGS. 4 and 5. Specifically, the shift shaft assembly110includes a shift shaft112with a sector gear114secured at one end thereof. The teeth of the sector gear114are engaged with the teeth of the toothed wheel gear94of the gear shift mechanism92. Thus, rotation of the shift shaft112causes rotation of the sector gear114and hence rotation of the toothed wheel gear94between the five positions. The shift shaft112extends outwardly from the engine casing so that it can be operatively engaged with a handle which can be manually rotated by an ATV operator to shift gears.

As shown inFIGS. 4,9, and10, the parking gear assembly12includes a park rod116with a three-toothed segment118at a top portion thereof. The park rod116also includes a pin120that is operatively coupled to the shift shaft assembly110. Specifically, the sector gear114of the shift shaft assembly110includes an elongated groove122that receives the pin120therein. As the shift shaft assembly110is rotated, the park rod116, which is forcibly guided by the pin120engaged with the groove122on the sector gear114, is rotated. When the ATV is in a park position (FIG. 10), the toothed segment118of the park rod116is rotated into engagement with the shift gear62to lock the secondary shaft66and prevent the movement of the output shaft36, as will be further discussed.

The five possible positions, i.e., park, reverse, neutral, high, and low, will now be described in greater detail. In the neutral position as shown inFIG. 11, the shift forks84,86are positioned such that the shift gear48on the driven shaft44is spaced from the gear54. Further, the shift gear62on the secondary shaft46is spaced from both gears68,70. As a result, no torque from the driven shaft44is transferred to the secondary shaft46and hence to the output shaft36. Specifically, the shift gear48engages the freewheeling gear68so it has no effect on the secondary shaft46. Likewise, the gear58engages the freewheeling gear70via gear80so it has no effect on the secondary shaft46. The gear54, which is engaged with shift gear62, freewheels on the driven shaft44so no torque is transferred to the shift gear62and hence the secondary shaft46.

In the park position as shown inFIGS. 10 and 11(the park rod116being shown in phantom inFIG. 11), the shift forks84,86and hence all the gears are in the same position as in the neutral position. However, the toothed segment118of the park rod116is engaged with the shift gear62to lock the secondary shaft46and prevent the movement of the output shaft36, which prevents any movement of the ATV. Specifically, the shift shaft assembly110selectively moves the park rod116, via the pin120, as the ATV is shifted into the park position. In the park position, the park rod116engages the shift gear62which is non-rotatably coupled to the secondary shaft46to thereby prevent the shift gear62and secondary shaft46from rotating. As a result, rotation of the bevel gear60is prevented, which prevents rotation of the output shaft36engaged therewith.

The park rod116is disengaged from the shift gear62when the ATV is not in a park position, as shown inFIG. 9. In the illustrated embodiment, the parking rod116is self-disengaging. Specifically, the teeth on the shift gear62and the three-toothed segment118of the park rod116are angled so that the park rod116may be easily disengaged from the shift gear62. In other words, the teeth are angled such that the force required to disengage the park rod116from the shift gear62is sufficiently low to enable the ATV operator to manually disengage the teeth without requiring additional force.

It is contemplated that the park rod116may act on any gear downstream of the output shaft36. For example, the park rod116may act on another one of the gears associated with the driven shaft44or secondary shaft46to prevent movement of the output shaft. Further, the park rod116may engage the crankshaft20or may engage one of the pulleys40,42.

In the low position (for operation at lower speeds) as shown inFIG. 12, the shift fork86is shifted which shifts the shift gear62into non-rotational engagement with the gear68. The shift gear48is shifted by shift fork84such that it is spaced from the gear54. Specifically, the shift gear62has axially extending portions124,26on opposing sides thereof. The axially extending portions124,126each include a series of teeth on the periphery thereof. The gear68has a recess128on a side thereof that is configured to receive the series of teeth on the extending portion124of the shift gear62. Thus, when the shift gear62is shifted into engagement with the gear68, the teeth on the extending portion124engage in the recess128to non-rotationally couple the shift gear62and the gear68. As a result, torque is transferred from the shift gear48on the driven shaft44to the gear68on the secondary shaft46, from the gear68to the shift gear62engaged therewith, and from the shift gear62to the secondary shaft46nonrotatably engaged therewith. Hence, torque from the secondary shaft46is transferred to the bevel gear60which is engaged with the output shaft36. The gear58engages the freewheeling gear70via gear80so it has no effect on the secondary shaft46. Likewise, the gear54, which is engaged with shift gear62, freewheels on the driven shaft44so it has no effect on the secondary shaft46.

In the high position (for operation at higher speeds) as shown inFIG. 13, the shift fork84is shifted which shifts the shift gear48into non-rotational engagement with the gear54. The shift gear62is shifted by shift gear86such that it is spaced from the gears68,70. Specifically, the shift gear48has an axially extending portion130on one side thereof. The axially extending portion130includes a series of teeth on the periphery thereof. The gear54has a recess132on a side thereof that is configured to receive the series of teeth on the extending portion130of the shift gear48. Thus, when the shift gear48is shifted into engagement with the gear54, the teeth on the extending portion130engage in the recess132to non-rotationally couple the shift gear48and the gear54. As a result, torque is transferred from the shift gear48on the driven shaft44to the gear54engaged therewith, from the gear54to the shift gear62on the secondary shaft46, and from the shift gear62to the secondary shaft46nonrotatably engaged therewith. Hence, torque from the secondary shaft46is transferred to the bevel gear60which is engaged with the output shaft36. The gear58engages the freewheeling gear70via gear80so it has no effect on the secondary shaft46. Likewise, the shift gear48engages the freewheeling gear68on the secondary shaft46so it has no effect on the secondary shaft46.

In the reverse position as shown inFIG. 14, the shift fork86is shifted which shifts the shift gear62into non-rotational engagement with the gear70. The shift gear48is shifted by shift fork84such that it is spaced from the gear54. Specifically, the gear70has a recess134on a side thereof that is configured to receive the series of teeth on the extending portion126of the shift gear62. Thus, when the shift gear62is shifted into engagement with the gear70, the teeth on the extending portion126engage in the recess134to non-rotationally couple the shift gear62and the gear70. As a result, torque is transferred from the gear58on the driven shaft44to the gear80on the shaft82, from the gear80to the gear70on the secondary shaft46, from the gear70to the shift gear62engaged therewith, and from the shift gear62to the secondary shaft46nonrotatably engaged therewith. Hence, torque from the secondary shaft46is transferred to the bevel gear60which is engaged with the output shaft36. The shift gear48engages the freewheeling gear68so it has no effect on the secondary shaft46. Likewise, the gear54, which is engaged with shift gear62, freewheels on the driven shaft44so it has no effect on the secondary shaft46. The reverse gear80is provided to rotate the gear70in an opposite direction with respect to the other gears on the secondary shaft46. Thus, when in the reverse position, the secondary shaft46and the driven shaft44rotate in the same direction.

Further details of the CVT for an internal combustion engine are disclosed in application Ser. No. 09/944,159 entitled “Continuously Variable Transmission for an Internal Combustion Engine”, the contents of which are incorporated herein by reference.

It can thus be appreciated that the aspects of the present invention have been fully and effectively accomplished. The foregoing specific embodiments have been provided to illustrate the structural and functional principles of the present invention, and they are not intended to be limiting. To the contrary, the present invention is intended to encompass all modifications, alterations and substitutions within the spirit and scope of the disclosed embodiments.