Engine coupling system

A vehicle comprises a vehicle body. An internal combustion engine is mounted to the vehicle body. The engine comprises a crankshaft mounted in a crankcase. A drive system is mounted to the vehicle body. A transmission is coupled with the drive system. A coupling system couples the engine with the transmission. The coupling system comprises a drive member and a driven member. The drive member is coupled with the crankshaft. The driven member is coupled with the transmission. The driven member is rotatably mounted in the crankcase. The drive member is coupled with the driven member.

RELATED APPLICATIONS

This application is based upon and claims the priority of Japanese Patent Application No. 2002-246407, filed on Aug. 27, 2002, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application generally relates to propulsion systems. More specifically, the present application relates to a coupling system for vehicle engines.

2. Description of the Related Art

Snowmobiles, and other vehicles, generally include an internal combustion engine mounted to the vehicle body. Additionally, such vehicles typically include a drive system mounted to the vehicle body for contacting a travel surface. A transmission can be included for coupling the internal combustion engine with the drive system of the vehicle.

A transmission can include an input shaft and an output shaft. One end of the input shaft is often coupled with the crankshaft of the engine. The other end of the output shaft is usually coupled with the drive system to transmit power to the drive system. When the internal combustion engine is driven, power is transmitted through the transmission to the drive system to enable the vehicle to travel along a travel surface.

SUMMARY OF THE INVENTION

One aspect of at least one of the inventions disclosed herein includes the realization that the connection between a crankshaft of an engine and an input shaft of a transmission can be improved by supporting the input shaft with the body of the engine and connecting the input shaft to the crankshaft through a damper. As such, the loads on the crankshaft can be reduced while the durability of the connection between the crankshaft and the input shaft can be enhanced.

For example, known assemblies for coupling an input shaft of a transmission to a crankshaft of an engine of, for example, but without limitation, a snowmobile, rely on a direct, rigid connection between the input shaft and the crankshaft. As such, loads imparted to the input shaft are directly transferred to the crankshaft of the engine in the form of torsional and bending loads. Thus, in order to increase the strength of the connection between the input shaft and the crankshaft, the input shaft and/or the crankshaft must be made larger. Changing the shape of a crankshaft requires significant design considerations in light of, for example, the number of bearings typically used to support a crankshaft and balancing. Thus, by configuring the crankcase to support the input shaft, the crankcase can absorb some of the loads transmitted from the input shaft, thereby reducing the total load on the crankshaft and avoiding the need to redesign the crankshaft.

Thus, in accordance with another aspect of at least one of the inventions disclosed herein, a vehicle comprises a vehicle body and an internal combustion engine mounted to the vehicle body. The engine comprises a crankshaft mounted in a crankcase. The crankshaft extends along a first axis. A drive system is mounted to the vehicle body. The drive system is for contacting a travel surface. Rotation of at least a portion of the drive system enables movement of the vehicle body relative the travel surface. A transmission is coupled with the drive system. A coupling system couples the engine with the transmission. The coupling system comprises a drive member and a driven member. The drive member is located along the first axis and is coupled with the crankshaft. The driven member is located along the first axis and is coupled with the transmission. The driven member is rotatably mounted in the crankcase. The drive member is coupled with the driven member.

Another aspect of at least one of the inventions disclosed herein involves a vehicle that comprises a vehicle body. An internal combustion engine is mounted to the vehicle body. The engine comprises a crankshaft mounted in a crankcase. A drive system is mounted to the vehicle body. The drive system is for contacting a travel surface. A transmission is coupled with said drive system. A means for coupling the engine with the transmission within the crankcase is provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference toFIG. 1, a vehicle20having certain features, aspects and advantages of the present inventions is described below. As shown inFIG. 1, the vehicle20is a snowmobile. A snowmobile is an environment for which many features, aspects and advantages of the present inventions provide particular advantages. Nevertheless, certain features, aspects and advantages of the present inventions can be used with other vehicles20, such as all-terrain vehicles and watercraft.

As shown inFIG. 1, the vehicle20comprises a vehicle body22, an internal combustion engine24mounted to the vehicle body22, a drive system26mounted to the vehicle body22for contacting a travel surface28to enable movement of the vehicle20relative the travel surface28, a transmission system30coupled with the drive system26, and a coupling device32for coupling the engine24with the transmission30.

The vehicle body22carries a number of other components of the vehicle20. For example, a vehicle body cover34is disposed over the vehicle body22. The vehicle body cover34defines, in part, an engine compartment36in which the engine24is mounted. The engine24is described in greater detail below. A battery38and a heat exchanger40are shown within the vehicle body22and are also described in further detail below.

A windshield42is disposed over a mid-portion of the vehicle body cover34. The windshield42provides some degree of protection for the riders from wind and other elements during operation of the vehicle20. Rearward of the windshield42, a fuel tank44is mounted to the vehicle body22in a manner that allows the vehicle body cover34and the fuel tank44to appear to blend together.

A seat46is mounted to the vehicle body22, rearward of the fuel tank44. The seat46preferably is a saddle-type seat. Foot rests48project from the sides of the vehicle body22, adjacent to the seat46.

A grab bar50is disposed rearward from the seat46, The grab bar50comprises a grabbing portion52that can be used to raise a rear portion of the vehicle20for turning and maneuvering when the vehicle20is not being ridden. The illustrated grab bar50is generally U-shaped and is mounted in a generally horizontal manner. However, other forms of grab bars can be used. For instance, the grab bar50can be define one or a plurality of loops, or it can be semicircular, in a vertical or an inclined in orientation. Thus, any suitable grab bar construction can be used.

Forward of the seat46and the fuel tank44, a steering handle assembly54is disposed. The steering handle assembly54can carry appropriate controls and can be coupled to a pair of front skis56. Manipulation of the steering handle assembly54causes the direction of the vehicle20to be altered. The skis56are mounted to the vehicle body22through a front suspension assembly58. Any suitable front suspension assembly58can be used.

The engine24in the illustrated arrangement is a four-cycle, multi-cylinder engine mounted within the engine compartment36. The engine24has an engine body60that is supported on the vehicle body22.

An intake system62is configured to introduce air and fuel into the engine body60. The intake system62comprises an air filter64and a carburetor66.

An exhaust system68is configured to discharge exhaust gases to the atmosphere after combustion in the engine24. The exhaust system68comprises exhaust pipes70and a muffler72.

The engine body60comprises a crankcase74supported on the vehicle body22. The crankcase74houses a crankshaft76. The engine body60comprises a plurality of cylinders78projecting upward from the crankcase74toward the rear of the vehicle20. The engine body60comprises an oil pan80covering a bottom portion of the crankcase74. The engine24and engine body60are described in greater detail below.

As shown inFIGS. 1 and 2, the engine24drives a transmission system30, which is a continuously variable transmission. Other transmissions can also be used. The transmission system30preferably is coupled with the engine24through a coupling device32, described in further detail below. In the illustrated arrangement, the transmission system30comprises a pulley system82, a speed change gear system84, and a power transmission gear system86.

The pulley system82comprises an input shaft88coupled with a drive pulley90and an output shaft92coupled with a driven pulley94. The input shaft88can be coupled with the drive pulley90through the speed change gear system84.

The speed change gear system84can comprise a clutch, a centrifugal clutch, or a sprag clutch. In other embodiments, the input shaft88can be directly coupled with the drive pulley90.

The drive pulley90powers a driven pulley94through a transmission belt96. In the illustrated arrangement the transmission belt96is a v-belt96. In some configurations, a drive chain can be used in place of the v-belt96. Other arrangements also can be used.

The driven pulley94is connected to and rotates about an output shaft92. The output shaft92is coupled with the power transmission gear system86. The transmission system30and the drive system26are coupled through the power transmission gear system86.

As shown inFIG. 1, the drive system26comprises a drive shaft98coupled with the transmission system30through the power transmission gear system86. The drive shaft98powers a drive unit100. The drive unit100generally comprises a plurality of drive wheels102and a drive track104. The drive wheels102provide a motive force to the drive track104, which is commonly used in the vehicle industry.

With continued reference toFIG. 1, the drive track104is guided around a preferred path on a pair of slide rails106, a plurality of suspension wheels108and main rear suspension wheels110. The slide rails106preferably support the suspension wheels108and the main rear suspension wheels110.

An idler roller112preferably is mounted to the vehicle body22and is configured to help to define the preferred path for the drive track104. As is known in the vehicle industry, these components can be mounted to the vehicle body22with a rear suspension system114. Any suitable rear suspension system114can be used and certain portions of the rear suspension system114have been schematically illustrated inFIGS. 1 and 2.

Many of the above-described components are generally conventional and can be arranged and configured in any suitable manner. Additionally, the above-described components can be replaced by other suitable components where desired. Any details omitted to this point have been considered well within the design knowledge of those of ordinary skill in the art.

FIG. 2further illustrates the exhaust system68of the vehicle20. As noted above, combustion byproducts are exhausted through the exhaust system68, along the direction identified generally by the reference numeral116. In the illustrated arrangement, the exhaust system68comprises an exhaust pipe70that extends rearward from the engine24.

The exhaust pipe70comprises exhaust runners118that extend rearward from the engine24. The exhaust runners118can be tuned for improved engine performance. Additionally, the length of each runner118can be lengthened prior to merging together with any other runners118of the exhaust pipe70such that pulse effects between the exhaust runners can be reduced. Optionally, an attenuation chamber or passage120between two or more runners can be used to reduce the effect of reflected pressure pulses in the exhaust system68.

With continued reference toFIG. 2, each exhaust runner118includes an upstream end communicating with a respective cylinder defined by the engine body60. In the illustrated embodiment, each exhaust runner118is coupled to an exhaust discharge pipe122that is individually joined to the engine body60, e.g., with a flange. At least two of the runners118join at a merge location124and the merged flow then divides into manifold pipes126. In some arrangements, a single manifold pipe can be used.

The manifold pipes126extend rearward to a muffler72. The muffler72provides an enlarged volume into which the exhaust can flow. Exhaust energy is dissipated within muffler72and the noise level of the exhaust can thus be decreased. In the illustrated arrangement, the muffler72is disposed below a portion of the seat46that is rearward of a rider section of the seat46.

Two exhaust pipe ends128extend rearward from the muffler72. In some arrangements, a single exhaust pipe end128can extend from the muffler72. Other numbers of exhaust pipe ends128also can be used. The exhaust pipes70preferably discharge exhaust gases116into the atmosphere. As illustrated inFIG. 1, the exhaust pipe ends128can extend upwardly and rearwardly from the muffler72. Preferably, the exhaust pipe ends128terminate at a location forward of the grab portion52of the grab bar50.

As shown inFIGS. 3,4, and5, the engine body60comprises a crankcase74housing a crankshaft76, a cylinder block78defining cylinder bores132projecting rearwardly and upwardly from the crankcase74, an oil pan80provided to cover an underside of the crankcase74, pistons130slidably fitted in the cylinder bores132, and connecting rods134which couple the crankshaft76with the pistons130. An axis136of the crankshaft76extends horizontally, from one side of the vehicle body22to the other. A cylinder head150closes the upper ends of the cylinder bores132. The cylinder bores132, the upper surfaces of the pistons130, and a lower surface of the cylinder head150together define corresponding combustion chambers148(FIG. 4).

Intake and exhaust passages138,140are defined in the cylinder head150to provide access to the combustion chambers148. Intake and exhaust valves142,144are movable to open and close the intake and exhaust passages138,140, respectively. A valve mechanism (not shown) operates the intake and exhaust valves142,144to open and close appropriately in association with the crankshaft76.

The engine24further includes an ignition system. With reference toFIG. 4, spark plugs146, at least one for each of the combustion chambers148, are affixed to the cylinder head150so that electrodes, which are defined at one end of the spark plugs146, are exposed to the respective combustion chambers148. Spark plugs146preferably are fired in a conventional manner so as to ignite an air/fuel charge during each combustion or “power” stroke.

As shown inFIGS. 3 and 5, the engine24can comprise a balancer shaft152. The balancer shaft152is located above the crankshaft76and extends generally parallel to the crankshaft76. The engine24can also comprise a balancer shaft gear system154configured to drive the balancer shaft152. For example, the balancer shaft gear system154can couple the balancer shaft152to the crankshaft76.

The engine24can also comprise a starter156for starting the engine24. The starter156can include a starter motor158coupled with the crankshaft76through a starter gear system160.

As shown inFIG. 3, the intake system62includes a carburetor66. The carburetor66is located adjacent a forward-facing surface of the engine body60. The carburetor66can be configured to mix air62and fuel64for combustion in the combustion chambers148. An air filter64supplies air to the carburetor66. The air filter64is located above the front surface of the cylinder78and in front of, and above, the balancer shaft152.

A cooling system166is provided for cooling the internal combustion engine24. The cooling system166is described further below with reference toFIG. 5. A lubrication system168is described further below with reference toFIG. 4.

As shown inFIG. 4, the transmission30includes an input shaft88located generally along the same axis136as the crankshaft76. The input shaft88is coupled with the crankshaft76through the coupling device32. The input shaft88is coupled with the drive pulley90such that the drive pulley90is supported on the input shaft88and rotates with the input shaft88.

The coupling device32is supported within the crankcase74by at least one bearing. Preferably, two set of bearings support the coupling device32. In the illustrated embodiment, the coupling device32is supported by inner and outer bearings170,172. As used herein, the terms “outer” and “inner” refer to the positions of the bearings170,172relative to each other and the engine body60, i.e., the bearing172is disposed closer to the center of the engine body60relative to the position of the bearing170. However, other orientations are possible.

The coupling device32is rotatable about the axis136of the crankshaft76. The coupling device32is coupled to the crankshaft76and the input shaft88. The input shaft88is supported by the coupling device32. The drive pulley90is supported on the input shaft88. A further advantage is provided where the coupling device32comprises a damper174. The coupling device32is described further below with reference toFIGS. 6 and 7.

As shown inFIG. 4, a lubrication system168is provided to lubricate the engine24. Portions of the lubrication system168are also shown inFIG. 3. The lubrication system168comprises an oil pan80capable of storing oil176. The illustrated lubrication system168is known as a dry-sump lubrication system. Thus, the oil pan80is usually referred to as an “oil cap”. However, one of ordinary skill in the art recognizes that the present lubrication system features can be incorporated into any type of lubrication system, including dry-sump and wet-sump recirculating-lubricant systems, as well as other types of lubrication systems.

A regulating wall178separates a first chamber180from a second chamber182inside the oil pan80. In the illustrated embodiment, the wall178is formed on the oil pan80. However, in other embodiments, the wall178can be part of the crankcase.

The regulating wall170is approximately centered with respect to side portions of the vehicle body22. Thus, the first and second chambers180,182are referred to hereinafter as side chambers180,182.

However, one of ordinary skill in the art recognizes that if the engine24were mounted in a vehicle such that the crankshaft88extends parallel to a longitudinal axis of the vehicle, the chambers180,182would be arranged one in front of the other. In other words, the chambers180,182could be referred to as forward and rearward chambers. Additionally, it is to be noted that in such a vehicle, the regulating wall178can be arranged so as to extend generally parallel to a longitudinal axis of the vehicle. As such, the wall178would define side chambers, similar to the illustrated embodiment.

Preferably, the wall178is configured to restrict the flow of oil176within the oil pan80. Additionally, the wall178preferably is configured to distribute oil176generally evenly between the first and second side chambers180,182.

The lubrication system168also comprises first and second oil pumps184,186. The first and second oil pumps184,186can both be scavenging pumps that draw the oil176from the oil pan80. The first and second oil pumps184,186pump the oil176into a common oil passage188formed in the cylinder block78and then into an oil tank (not shown) to store the oil176therein.

Optionally, the engine24can also include an oil cooler190configured to extract heat from the oil176. In the illustrated embodiment, the oil cooler190is mounted on the front surfaces of the cylinder block78. The first and second oil pumps184,186pump oil176through the oil passage188into the oil cooler190to cool the oil176.

The lubrication system168also comprises an oil feed pump192for supplying the oil176stored in the oil tank to portions of the engine24which benefit from lubrication. The first and second oil pumps184,186and the oil feed pump192comprise pump casings194.

A pump shaft196passes through the respective pump casings194and is rotatable about an axis extending generally parallel to the crankshaft80. In the illustrated embodiment, the crankshaft80and the oil pump shaft196extend in a lateral direction relative the vehicle body22.

The first and second oil pumps184,186, and the oil feed pump192, comprise rotors198housed within the respective pump casings194coupled with the pump shaft196to rotate with the pump shaft196. It is to be noted that the shaft196can be formed from a single member, or a plurality of shaft members connected to each other in an end-to-end fashion. As such, each rotor (or impeller)198can be mounted on a separate shaft member. In the illustrated embodiment, the shaft196is formed from a single member.

First and second oil inlet ports200,202are formed in the pump casings194of the respective oil pumps184,186. The first oil inlet port200extends between the first side chamber180and the first oil pump184. The second oil inlet port202extends between the second side chamber182and the second oil pump186. Thus, during operation. the first and second oil inlet ports200,202draw oil176from the first and second side chambers180,182respectively.

The pump shaft196supports the rotors198of the first oil pump184, the second oil pump186, and the oil feed pump192, and thus defines a single axis. The pump shaft196is coupled with the crankshaft76by a chain coupler204. Thus, respective oil pumps184,186,192can be driven together with the engine24through a single drive device, thereby simplifying the construction of the lubrication system and lowering the weight of the engine24.

A further advantage is provided where the pump casings194of the first and second oil pumps184,186are both located within one of the first and second chambers180,182. As such, the pumps184,186form a compact unit and are more easily accessible. Further, the pump casings194of the first and second oil pumps184,186can be molded together. Additionally, the casings of all three pumps184,186,192can be formed in one piece, thereby forming a single compact unit that can be more easily removed and re-installed.

Another advantage is provided where the pumps184,186are disposed so as to extend downwardly from the crankcase74. For example, as shown inFIG. 4, the pumps184,186are disposed generally below the crankshaft88. As such, when the oil pan80is removed from the crankcase74, the pumps184,186are more exposed, thereby providing easier access to the pumps184,186. The pump casings194can be detachably clamped to the underside of the crankcase74by fasteners. As such, the pump casings194can be more easily removed from below the engine24when the oil pan80is removed.

As the engine24is driven, the respective oil pumps184,186draw oil176from the oil pan80and deliver it into the oil tank. As the oil feed pump192is driven, the oil176stored in the oil tank is delivered to the various portions of the engine24to lubricate the engine24. After lubrication, the oil176naturally flows down into the first and second side chambers180,182of the oil pan80.

The oil pan80is detachably clamped to the underside of the crankcase74by fasteners206. In the illustrated embodiment, when the oil pan80is detached from the underside of the crankcase74, the respective oil pumps184,186,192and a lower portion of the chain coupler204protrude downwardly from the underside of the crankcase74. As such, the illustrated embodiment provides a further advantage in providing easier access to the respective oil pumps184,186,192and the chain coupler204for the maintenance and inspection thereof.

FIG. 5shows the engine24, a cooling system166, a balancer shaft152, and a starter156. Portions of the cooling system166are also shown inFIGS. 3 and 4.

In the illustrated embodiment, the cooling system166is configured to cool the engine24with coolant208. The cooling system166comprises coolant jackets210formed in the cylinder block78and the oil cooler190. A coolant pump212is located above the crankshaft76and is supported on the cylinders78. The coolant pump212is configured to deliver coolant208to the coolant jackets210(shown inFIG. 4).

The cooling system166also comprises a coolant pump gear system214to couple the coolant pump212to the balancer shaft152. The cooling system166further comprises a heat exchanger40(shown inFIGS. 1 and 3) located behind the crankcase74for air cooling the coolant208after it circulates through the coolant jackets210. As the engine24is driven, the coolant pump212circulates coolant208to cool the engine24.

A battery38, as shown inFIGS. 1,2and3, is provided for supplying electric power to the spark plugs146of the engine24, the starter motor158of the starter device156, an engine control device (not shown), as well as other components. The battery38is located above and in front of the engine body60, in front of the balancer shaft152, and below the air filter64, substantially in the center of the vehicle body22relative side portions of the vehicle body22. The battery38is supported by the vehicle body22.

When the starter motor158cranks the crankshaft76to start up the engine24, air62and fuel64are drawn into the cylinders78from the intake device62. A mixture of air62and fuel64is ignited inside the combustion chambers148by the spark plugs146. Combustion gases116are discharged through the exhaust system68. The engine24continues to run and provides a drive force that is transmitted to the drive system26through the transmission system30. The drive track104of the drive system26revolves to drive the vehicle20over the travel surface28.

As shown inFIGS. 6 and 7, the coupling device32comprises a drive member216, a driven member218, and a plurality of dampers174. The drive member216comprises a base portion220and a plurality of blades222extending radially outward from the base portion220. The base portion220of the drive member216is coupled with an end of the crankshaft76. As shown inFIG. 7, the base portion220is engaged with the crankshaft76with a splined arrangement.

The driven member218comprises a base portion224and an inner support portion225. The base portion224of the driven member218is coupled on a first side with the input shaft88of the transmission system30. The base portion224also includes an annular outer wall227and a plurality of blades226extending radially inward from the outer wall227. The damper members174are disposed between the outwardly extending blades222and the inwardly extending blades226.

The inner support portion225extends inwardly, relative to the engine body60, from the annular outer wall227, over the crankshaft76, and to the inner bearing172. Additionally, the inner support portion225is connected to the base portion224with a plurality of bolts228. Thus, the inner support portion225allows the input shaft88to be supported by both of the inner and out bearings172,170.

As such, the input shaft88is not supported only by the crankshaft. Rather, the input shaft88is rotatably supported by the crankcase74. Thus, the bending loads applied to the input shaft through the interaction of the drive belt96and the drive pulley90are not transferred to the crankshaft76. Rather, such bending loads are imparted to the bearings170,172. Additionally, because the drive member216is coupled with the driven member218within the crankcase74, the coupling device32is protected from the environment in which the snowmobile20is operated.

In the illustrated embodiment, the drive member216, and the dampers174, are generally covered by the driven member218. The base220of the drive member216extends axially out from the crankshaft76and the blades222of the drive member216extend radially out toward the base224of the driven member218. The blades226of the driven member218extend radially in toward the base220of the drive member216. The blades222of the drive member216are fitted in among the blades226of the driven member218. The blades222,226of the drive member216and the driven member218are alternately arranged in the coupling device32. The dampers174are provided between pairs of adjacent blades222,226in the coupling device32.

The dampers174preferably comprise a compressible material that is wedged between a pair of adjacent blades222,226. The dampers174preferably comprise a rubber material. The dampers174, being compressible, can absorb some of the initial or transient torque loads applied by the crankshaft76to the input shaft88. By absorbing some of the torque applied in this manner, the dampers176make the transfer of rotational motion between the crankshaft76and the input shaft88smoother. This, in turn, improves the smoothness of the transmission30, which also improves the ride of the vehicle20.

The coupling device32preferably reduces impact forces that typically are transferred from the crankshaft76to the input shaft88by incorporating a plurality of dampers, such as the dampers174. The coupling device32preferably comprises a simple configuration wherein the driven member218forms a housing around, or encloses, the drive member216and dampers174. The compact design and configuration preferably facilitates rotatably mounting the coupling device32within the crankcase74. Accordingly, the coupling device32provides increased strength and support for the transmission system30without greatly increasing the weight of the vehicle20as well as other features and advantages.

As discussed above, some embodiments discussed herein provide an improved coupling device32. As shown inFIG. 6, the coupling device32is supported directly on the crankcase76of the engine. A driven member218of the coupling device32is supported at two bearing locations170,172within the crankcase. The driven member218is coupled with, and supports, the input shaft88of the transmission system30. Accordingly, the input shaft88is supported on the crankcase74, through the coupling device32, rather than being supported simply on a free end of the crankshaft76. Supporting the input shaft88on the crankcase74provides added strength and support for the input shaft88and the transmission system30. The coupling device32preferably provides a connection with greater strength and support without significantly increasing the weight of the vehicle20and without requiring changes in the design of the crankshaft76.

Although the present inventions have been described in terms of a certain embodiment, other embodiments apparent to those of ordinary skill in the art also are within the scope of these inventions. Thus, various changes and modifications may be made without departing from the spirit and scope of the inventions. For instance, various components may be repositioned as desired. Moreover, not all of the features, aspects and advantages are necessarily required to practice the present inventions. Accordingly, the scope of at least one of the present inventions is intended to be defined only by the claims that follow.