Patent Description:
Many vehicles use a continuously variable transmission (CVT) to transmit power from the engine to the wheels. A CVT includes a drive pulley, a driven pulley, and drive belt around the pulleys. The engine drives the drive pulley, which drives the belt, which drives the driven pulley, which then drives the wheels, typically via other mechanical components provided between the driven pulley and the wheels.

Each of the pulleys has a movable sheave and a fixed sheave. As the movable sheave of a given pulley moves closer to the fixed sheave, the drive belt is pushed to turn about a greater radius about the pulley, and the pulley is said to have a greater effective diameter. Similarly, as the movable sheave moves away from the fixed sheave, the drive belt moves to turn about a smaller radius about the corresponding pulley, and the pulley is said to have a smaller effective diameter. During operation, as the speed of the engine increases, the effective diameter of the drive pulley increases and the effective diameter of the driven pulley decreases. Similarly, as the speed of the engine decreases, the effective diameter of the drive pulley decreases and the effective diameter of the driven pulley increases.

When the engine is under a heavy load, such as during acceleration, travelling uphill or when towing a load, the effective diameter of the drive pulley decreases and the effective diameter of the driven pulley increases.

Many drive belts of CVTs are made of polymer which wear due to friction, tension and deformation. During operation of the CVT, a given portion of the drive belt will experience tension, compression and bending as the drive belt rotates around the pulleys. As the drive belt rubs against the sheaves as their effective diameters change, the belt can slip relative to the pulleys and the drive belt is squeezed and deforms between the sheaves of the pulleys. Also, when the belt turns about the pulleys, the material of the belt gets compressed on the inside and stretches on the outside, and this effect increases as the effective diameter of the pulleys decreases. All of this leads to wear of the drive belt. For this reason, vehicle manufacturers typically recommend to change the drive belt after a certain number of kilometers travelled by the vehicle, a certain number of hours of operation of the vehicle or a combination thereof. In some vehicles, a visual indication that maintenance is recommended is provided on an instrument panel to inform the driver that the drive belt should be inspected or may need to be changed.

However, setting the maintenance schedule based on number of kilometers traveled and/or number of hours of operations does not take into account the vehicle's operating conditions, such as the way in which the driver operates the vehicle and/or other environmental conditions in which the vehicle operates. For example, a driver who accelerates and/or decelerates quickly and often will cause more wear to the drive belt than a driver that operates the vehicle at constant speed for long periods of time. Also for example, a polymer belt will wear faster in a hot environment than in a cold environment. <CIT> discloses a maintenance prompting method for an electromechanical control CVT, the method comprising calculating the actual speed ratio, calculating the no-load speed ratio, calculating the slip rate, reading the input torque, judging the speed ratio, judging the torque, judging the slip rate and the like. By means of the steps, a driver can monitor the quality of lubricating oil online and arrange maintenance reasonably. Meanwhile, in the method, the structure of an angle displacement sensor and the material of a belt wheel are improved, so that the angle displacement sensor and the belt wheel are more suitable for use of the CVT, and the result of the prompting method is more stable.

There remains a desire for a method for estimating wear of the polymer drive belt of a CVT that takes into account the vehicle's operating conditions.

It is an object of the present technology to ameliorate at least some of the inconveniences present in the prior art.

The present technology provides a method for estimating wear of a polymer drive belt of a CVT which, in some embodiments, uses a belt load-representative parameter, a belt speed-representative parameter and/or a belt temperature representative parameter to determine one or more factors. The one or more factors are then used to modify a parameter used to determine when the drive belt may need to be replaced. In one example where the parameter used to estimate when the drive belt may need to be replaced is distance travelled by the vehicle, if the vehicle travels <NUM>, but with a lot of acceleration and deceleration cycles and in a very hot environment such as the desert for example, the one or more factors could modify this <NUM> to actually count as <NUM> towards the maintenance limit to account for the extra wear on the belt resulting from such an operation. A similar modification could be done where the parameter is time. In another example, the parameter is a counter based on the one or more factors.

According to one aspect of the present technology, there is provided a method for estimating wear of a polymer drive belt according to claim <NUM>.

In some embodiments of the present technology, the at least one first operating parameter includes a belt load-representative parameter.

In some embodiments of the present technology, the at least one first operating parameter further includes a belt speed-representative parameter.

In some embodiments of the present technology, the at least one first operating parameter of the vehicle is at least one of: vehicle speed; engine speed; drive belt speed; rotational speed of a driven pulley of the CVT; rotational speed of a ground engaging member of the vehicle; rotational speed of a rotating element operatively connecting the driven pulley to the ground engaging member; engine load; engine torque; CVT ratio; air charge; or relative air charge.

In some embodiments of the present technology, the belt speed-representative parameter is one of: vehicle speed; engine speed; drive belt speed; rotational speed of a driven pulley of the CVT; rotational speed of a ground engaging member of the vehicle; or rotational speed of a rotating element operatively connecting the driven pulley to the ground engaging member. The belt load-representative parameter is one of: engine load; engine torque; CVT ratio; air charge; or relative air charge.

In some embodiments of the present technology, the belt speed-representative parameter is vehicle speed and the belt load-representative parameter is relative air charge.

In some embodiments of the present technology, determining the first belt wear-affecting factor comprises: inputting the belt speed-representative parameter and the belt load-representative parameters in one of a first map, a first table or a first equation; and obtaining the first belt wear-affecting factor from the one of the first map, the first table or the first equation.

In some embodiments of the present technology, the at least one first operating parameter of the vehicle is engine speed.

In some embodiments of the present technology, determining the first belt wear-affecting factor comprises: inputting the at least one first operating parameter of the vehicle in one of a first map, a first table or a first equation; and obtaining the first belt wear-affecting factor from the one of the first map, the first table or the first equation.

In some embodiments of the present technology, the at least one first operating parameter of the vehicle further includes a substitute operating parameter of the vehicle; and the first belt wear-affecting factor is determined using the substitute operating parameter when at least one of the belt load-representative parameter and the belt speed-representative parameter is unavailable or faulty.

In some embodiments of the present technology, the substitute operating parameter of the vehicle is different from the belt load-representative parameter and the belt speed-representative parameter.

In some embodiments of the present technology, the belt load-representative and belt speed-representative parameters are relative air charge and vehicle speed; and the substitute operating parameter of the vehicle is engine speed.

In some embodiments of the present technology, the first belt wear-affecting factor is a belt load factor associated with a load applied on the drive belt.

In some embodiments of the present technology, the at least one second operating parameter is a belt temperature-representative parameter.

In some embodiments of the present technology, the at least one second operating parameter of the vehicle is at least one of: ambient air temperature; CVT air intake air temperature, the CVT air intake air temperature being a temperature of air in a CVT air intake assembly supplying air in a CVT housing of the CVT; CVT housing air temperature, the CVT housing air temperature being a temperature of air in the CVT housing; or drive belt temperature.

In some embodiments of the present technology, the at least one second operating parameter of the vehicle is ambient air temperature.

In some embodiments of the present technology, determining the second belt wear-affecting factor comprises: inputting the at least one second operating parameter of the vehicle in one of a second map, a second table or a second equation; and obtaining the second belt wear-affecting factor from the one of the second map, the second table or the second equation.

In some embodiments of the present technology, the second belt wear-affecting factor is a belt temperature factor associated with a temperature of the drive belt.

In some embodiments of the present technology, the belt wear-representative parameter is one of: vehicle speed; vehicle travel distance; drive belt use time; drive belt rotations; engine rotations; or drive belt wear units.

In some embodiments of the present technology, applying the first and second wear-affecting factors to the belt wear-representative parameter to obtain the adjusted belt wear-representative parameter comprises: multiplying the belt wear-representative parameter by the first wear-affecting factor and by the second wear-affecting factor to obtain the adjusted belt wear-representative parameter.

In some embodiments of the present technology, applying the first and second wear-affecting factors to the belt wear-representative parameter to obtain the adjusted belt wear-representative parameter comprises: multiplying the belt wear-representative parameter by the first wear-affecting factor to obtain a first intermediate adjusted belt wear-representative parameter; multiplying the belt wear-representative parameter by the second wear-affecting factor to obtain a second intermediate adjusted belt wear-representative parameter; and adding the first and second intermediate adjusted belt wear-representative parameter to obtain the adjusted belt wear-representative parameter.

In some embodiments of the present technology, assigning a first weight to the belt wear-representative parameter prior to multiplying the belt wear-representative parameter by the first wear-affecting factor; and assigning a second weight to the belt wear-representative parameter prior to multiplying the belt wear-representative parameter by the second wear-affecting factor.

In some embodiments of the present technology, adjusting the total belt wear-representative parameter based on the adjusted belt wear-representative parameter to obtain the updated total belt wear-representative parameter comprises: adding the adjusted belt wear-representative to the total belt wear-representative parameter.

In some embodiments of the present technology, comparing the updated total belt wear-representative parameter to a threshold belt wear; and providing an indication of a need for transmission maintenance on the vehicle when the updated total belt wear-representative parameter is greater than or equal to the threshold belt wear.

In some embodiments of the present technology, comparing the updated total belt wear-representative parameter to a threshold belt wear; and reducing engine performance when the updated total belt wear-representative parameter is greater than or equal to the threshold belt wear.

In some embodiments of the present technology, adjusting the total belt wear-representative parameter based on the adjusted belt wear-representative parameter to obtain the updated total belt wear-representative parameter comprises: subtracting the adjusted belt wear-representative from the total belt wear-representative parameter.

In some embodiments of the present technology, comparing the updated total belt wear-representative parameter to a threshold belt wear; and providing an indication of a need for transmission maintenance on the vehicle when the updated total belt wear-representative parameter is less than or equal to the threshold belt wear.

In some embodiments of the present technology, the adjusted belt wear-representative parameter corresponds to a first belt wear-representative parameter; and the total belt wear-representative parameter corresponds to a second belt wear-representative parameter that is different from the first belt wear-representative parameter; and adjusting the total belt wear-representative parameter based on the adjusted belt wear-representative parameter comprises: converting the adjusted belt wear-representative parameter to correspond to correspond to the second belt wear-representative parameter to obtain a converted adjusted belt wear-representative parameter; and adjusting the total belt wear-representative parameter based on the converted adjusted belt wear-representative parameter.

In some embodiments of the present technology, the adjusted belt wear-representative parameter corresponds to vehicle speed; and the total belt wear-representative parameter corresponds to vehicle travel distance.

In some embodiments of the present technology, the one of the first map, the first table or the first equation has a normal wear region and an extra wear region; when the first belt wear-affecting factor is obtained from the normal wear region, applying the first belt wear-affecting factor to the belt wear-representative parameter does not increase a value of the belt wear-representative parameter; and when the first belt wear-affecting factor is obtained from the extra wear region, applying the first belt wear-affecting factor to the belt wear-representative parameter increases the value of the belt wear-representative parameter.

In some embodiments of the present technology, the one of the second map, the second table or the second equation has a normal wear region and an extra wear region; when the second belt wear-affecting factor is obtained from the normal wear region, applying the second belt wear-affecting factor to the belt wear-representative parameter does not increase a value of the belt wear-representative parameter; and when the second belt wear-affecting factor is obtained from the extra wear region, applying the second belt wear-affecting factor to the belt wear-representative parameter increases the value of the belt wear-representative parameter.

In some embodiments of the present technology, adjusting the total belt wear-representative parameter based on the adjusted belt wear-representative parameter to obtain the updated total belt wear-representative parameter comprises: adding the adjusted belt wear-representative parameter to the belt wear-representative parameter to obtain a sum; and adjusting the total belt wear-representative parameter based on the sum to obtain the updated total belt wear-representative parameter.

In some embodiments of the present technology, the method further comprises resetting the total belt wear-representative parameter upon receiving a signal indicative that the drive belt has been replaced by another drive belt.

In some embodiments of the present technology, the method further comprises repeating the steps of the method with a magnitude of the total belt wear-representative parameter corresponding being replaced by a magnitude of the updated total belt wear-representative parameter.

According to another aspect of the present technology, there is provided a vehicle according to claim <NUM>.

In some embodiments of the present technology, the plurality of sensors include at least two different sensors selected from: a vehicle speed sensor; a wheel speed sensor; an engine speed sensor; an intake air temperature sensor; an intake air pressure sensor; an ambient air temperature sensor; a belt temperature sensor; a CVT housing air temperature sensor; a CVT housing pressure sensor; an atmospheric pressure sensor; and a throttle position sensor.

According to another aspect of the present technology, there is provided a method for estimating wear of a polymer drive belt of a continuously variable transmission (CVT) provided in a vehicle. The method comprises: sensing a belt load-representative parameter of the vehicle; sensing a belt temperature-representative parameter of the vehicle; determining an estimated change in belt wear based on the belt load-representative parameter and the belt temperature-representative parameter; adjusting an estimated total belt wear based on the estimated change in belt wear to obtain an updated estimated total belt wear; comparing the updated estimated total belt wear to a threshold belt wear; and providing an indication of a need for maintenance on the vehicle when the updated estimated total belt wear is greater than or equal to the threshold belt wear.

Embodiments of the present technology each have at least one of the above-mentioned object and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present technology that have resulted from attempting to attain the above-mentioned object may not satisfy this object and/or may satisfy other objects not specifically recited herein.

Additional and/or alternative features, aspects and advantages of embodiments of the present technology will become apparent from the following description, the accompanying drawings and the appended claims.

The present technology will be described with respect to a three-wheeled straddle-type vehicle <NUM>. However, it is contemplated that the present technology could be applied to other vehicles equipped with a continuously variable transmission (CVT), some example of which will be briefly described further below.

With reference to <FIG> and <FIG>, a three-wheeled vehicle <NUM> has a front end <NUM> and a rear end <NUM> defined consistently with the forward travel direction of the vehicle <NUM>. The vehicle <NUM> has a frame <NUM>. A left front wheel <NUM> mounted to the frame <NUM> by a left front suspension assembly <NUM>, a right front wheel <NUM> mounted to the frame <NUM> by a right front suspension assembly <NUM>, and a single rear wheel <NUM> mounted to the frame <NUM> by a rear suspension assembly <NUM>. The left and right front wheels <NUM> and the rear wheel <NUM> each have a tire secured thereto. The front wheels <NUM> are disposed equidistant from a longitudinal centerline of the vehicle <NUM>, and the rear wheel <NUM> is centered with respect to the longitudinal centerline.

In the illustrated embodiment, each front suspension assembly <NUM> is a double A-arm type suspension, also known as a double wishbone suspension. It is contemplated that other types of suspensions, such as a McPherson strut suspension, or swing arm could be used. Each front suspension assembly <NUM> includes an upper A-arm <NUM>, a lower A-arm <NUM> and a shock absorber <NUM>. A sway bar <NUM> is connected to the front members of both lower A-arms <NUM> to reduce motion of one of the left and right front wheels <NUM> with respect to the other of the left and right front wheels <NUM>, and to thereby reduce rolling motion of the vehicle <NUM>. The rear suspension assembly <NUM> includes a swing arm <NUM> and a shock absorber <NUM>. The swing arm <NUM> is pivotally mounted at a front thereof to the frame <NUM>. The rear wheel <NUM> is rotatably mounted to the rear end of the swing arm <NUM> which extends on a left side of the rear wheel <NUM>. The shock absorber <NUM> is connected between the swing arm <NUM> and the frame <NUM>.

The vehicle <NUM> has a laterally centered straddle seat <NUM> mounted to the frame <NUM>. In the illustrated embodiment, the straddle seat <NUM> is intended to accommodate a single adult-sized rider, i.e. the driver. It is however contemplated that the straddle seat <NUM> could be configured to accommodate more than one adult-sized rider (the driver and one or more passengers). A driver footrest <NUM> is disposed on either side of the vehicle <NUM> and vertically lower than the straddle seat <NUM> to support the driver's feet. In the embodiment of the vehicle <NUM> illustrated herein, the driver footrests <NUM> are in the form of foot pegs disposed longitudinally forward of the straddle seat <NUM>. It is also contemplated that the footrests <NUM> could be in the form of footboards. It is contemplated that the vehicle <NUM> could also be provided with one or more passenger footrests disposed rearward of the driver footrest <NUM> on each side of the vehicle <NUM>, for supporting a passenger's feet when the seat <NUM> is configured to accommodate one or more passengers in addition to the driver. A brake operator (not shown), in the form of a foot-operated brake pedal, is connected to the right driver footrest <NUM> for braking the vehicle <NUM>.

A handlebar <NUM>, which is part of a steering assembly <NUM>, is disposed in front of the seat <NUM>. The handlebar <NUM> is used by the driver to turn the front wheels <NUM> to steer the vehicle <NUM>. A central portion of the handlebar <NUM> is connected to an upper end of a steering column <NUM>. From the handlebar <NUM>, the steering column <NUM> extends downwardly and leftwardly. A lower end of the steering column <NUM> is connected to a number of arms and linkages <NUM> that are operatively connected to the front wheels <NUM> such that turning the handlebar <NUM> turns the steering column <NUM> which, through the arms and linkages <NUM>, turns the front wheels <NUM>. It is contemplated that the steering assembly <NUM> could include a power steering unit to facilitate steering of the vehicle <NUM>.

A throttle operator <NUM> of the vehicle <NUM> is provided as a rotatable right hand grip on the handlebar <NUM>. The throttle operator <NUM> is rotated by the driver to control power delivered by an engine <NUM> of the vehicle <NUM>. It is contemplated that the throttle operator could be in the form of a thumb-operated or finger-operated lever and/or that the throttle operator <NUM>. The handlebar <NUM> has connected thereto various controls such as an engine start-up button and an engine cut-off switch located laterally inwardly of the left and right hand grips. A display cluster <NUM> is provided forwardly of the handlebar <NUM>. The display cluster <NUM> provides information to the driver of the vehicle <NUM> such as vehicle speed, engine speed, fuel lever, and other notifications and warnings, such as vehicle maintenance related notifications.

The frame <NUM> supports and houses the engine <NUM> which located forwardly of the straddle seat <NUM>. In the illustrated embodiment of the vehicle <NUM>, the engine <NUM> is an inline, three-cylinder, four-stroke internal combustion engine, but could be a two-stroke or diesel internal combustion engine. It is also contemplated that the engine <NUM> could have more or less cylinders. It is also contemplated that the engine <NUM> could have cylinders arranged in a configuration other than inline. For example, the engine <NUM> could be a V-type, two-cylinder, two-stroke internal combustion engine.

The engine <NUM> is operatively connected to the rear wheel <NUM> to drive the rear wheel <NUM>. With reference to <FIG> and <FIG>, the engine is operatively connected to the rear wheel <NUM> via an engine output shaft <NUM>, a continuously variable transmission (CVT) <NUM>, a transfer case <NUM>, a driveshaft <NUM>, and a gear assembly <NUM>. It is contemplated that the engine <NUM> could be operatively connected to the front wheels <NUM> instead of, or in addition to, the rear wheel <NUM>. The engine <NUM>, the engine output shaft <NUM>, the CVT <NUM>, the transfer case <NUM>, the driveshaft <NUM> and the gear assembly <NUM> form part of a vehicle powertrain <NUM> which will be described below in further detail. As can be seen, the transfer case <NUM> is disposed rearward of the engine <NUM>, and the CVT <NUM> is disposed rearward of the transfer case <NUM>. The CVT <NUM> and the transfer case <NUM> form a transmission assembly of the vehicle <NUM>.

With reference to <FIG>, a fuel tank <NUM> supplies fuel to the engine <NUM>. The fuel tank <NUM> is disposed longitudinally rearward of the CVT <NUM>. The straddle seat <NUM> is disposed behind the fuel tank <NUM>.

Also with reference to <FIG>, a radiator <NUM> is mounted to the vehicle frame <NUM> and in front of the engine <NUM>. The radiator <NUM> is fluidly connected to the engine <NUM> for cooling engine coolant used to cool the engine <NUM>.

With reference to <FIG> and <FIG>, each of the two front wheels <NUM> and the rear wheel <NUM> is provided with a brake <NUM>. Each brake <NUM> is a disc-type brake mounted onto a hub of its respective wheel <NUM> or <NUM>. Other types of brakes are contemplated. Each brake <NUM> includes a rotor mounted onto the wheel hub and a brake caliper straddling the rotor. Brake pads are mounted to the caliper so as to be disposed between the rotor and the caliper on either side of the rotor. The foot-operated brake operator is operatively connected to the brakes <NUM> provided on each of the two front wheels <NUM> and the rear wheel <NUM>. It is contemplated that the brake operator could be in the form of a hand-operated brake lever connected to the handlebar <NUM> instead of or in addition to the foot-operated brake pedal as shown herein.

The vehicle <NUM> also includes a number of fairings <NUM>, only some of which have been labeled in <FIG> for clarity, which are connected to the frame <NUM> to enclose and protect the internal components of the vehicle <NUM> such as the engine <NUM>.

The powertrain <NUM> now be described with reference to <FIG>.

With reference to <FIG>, the engine <NUM> has a crankcase <NUM>, a cylinder block <NUM> disposed on and connected to the crankcase <NUM>, and a cylinder head assembly <NUM> disposed on and connected to the cylinder block <NUM>. A crankshaft (not shown) is housed in the crankcase <NUM>. The cylinder block <NUM> defines three cylinders (not shown). A piston (not shown) is disposed inside each cylinder for reciprocal movement therein. The lower end of each piston is linked by a connecting rod (not shown) to the crankshaft. A combustion chamber is defined in the upper portion of each cylinder by the walls of the cylinder, the cylinder head assembly <NUM> and the top of the piston. Explosions caused by the combustion of an air/fuel mixture inside the combustion chambers cause the pistons to reciprocate inside the cylinders. The reciprocal movement of the pistons causes the crankshaft to rotate, thereby allowing power to be transmitted from the crankshaft to the rear wheel <NUM>. The cylinder head assembly <NUM> includes a fuel injector (not shown) for each cylinder. The fuel injectors receive fuel from the fuel tank <NUM> via a fuel rail <NUM>. A spark plug <NUM> is provided in the cylinder head assembly <NUM> for each cylinder to ignite the air/fuel mixture in each cylinder. The exhaust gases resulting from the combustion of the air-fuel mixture in the combustion chamber are removed from the engine <NUM> and are then released to the atmosphere via exhaust ports <NUM> of the engine <NUM> and an exhaust system (not shown). The exhaust system includes an exhaust manifold connected to a left side of the engine <NUM> to receive exhaust gas from the exhaust ports <NUM> and a muffler to receive exhaust gas from the exhaust manifold.

The engine <NUM> receives air from an air intake system <NUM>. As can be seen in <FIG>, the air intake system <NUM> includes an air intake assembly <NUM>, a throttle body <NUM> and an air intake manifold <NUM>. The air intake assembly <NUM> is disposed on the left side of a centerline of the engine <NUM> (defined by the output shaft <NUM>). The throttle body <NUM> and the air intake manifold <NUM> are disposed on the right side of the centerline of the engine <NUM>. The air intake assembly <NUM> defines a forwardly facing air inlet <NUM>. The air intake assembly <NUM> also includes a number of features such as internal walls and an air filter to help prevent the entry of dust and water into the engine <NUM>. The throttle body <NUM> includes a throttle valve (not shown) actuated by a throttle motor <NUM> to control a flow of air to the engine <NUM>. The air intake manifold <NUM> is connected to the engine <NUM> and defines three outlets (one per cylinder) to supply air to the air intake ports (not shown) of the engine <NUM>. During operation, air flows into the air intake assembly <NUM> via the air inlet <NUM>, the through the throttle body <NUM>, then through the air intake manifold <NUM> and finally to the combustion chambers of the engine <NUM>.

With reference to <FIG>, the transfer case <NUM> includes a transfer case housing <NUM> which is mounted to the rear end of the engine <NUM> via bolts The transfer case <NUM> also includes an input sprocket, an output sprocket, and a chain (all not shown) enclosed by the transfer case housing <NUM>. The output sprocket is operatively connected to the input sprocket by the chain. It is also contemplated that the output sprocket could be driven by the input sprocket via a belt or a gear train.

The engine output shaft <NUM> extends rearwardly from the rear end of the crankcase <NUM>, through an engine output shaft housing <NUM> (<FIG>) connected to the transfer case housing <NUM> to connect to the CVT <NUM>. In the illustrated embodiment, the engine output shaft <NUM> is connected directly to the crankshaft and serves as an extension thereof, but it is contemplated that the engine output shaft <NUM> could be operatively connected to the crankshaft via one or more gears. It is also contemplated that the engine output shaft <NUM> could be integrally formed with the crankshaft.

The CVT <NUM> includes a CVT housing <NUM> (<FIG>) disposed longitudinally rearward of the transfer case <NUM>. With reference to <FIG>, the CVT <NUM> also includes a drive pulley <NUM>, a driven pulley <NUM> and a drive belt <NUM> wrapped around the drive pulley <NUM> and the driven pulley <NUM> for driving the driven pulley <NUM>. The pulleys <NUM>, <NUM> and the drive belt <NUM> are disposed inside the CVT housing <NUM>. The drive belt <NUM> is made of a polymer, such as rubber for example.

In order to cool the drive pulley <NUM>, the driven pulley <NUM> and the drive belt <NUM>, a CVT air intake assembly <NUM> (<FIG>) supplies air inside the CVT housing <NUM>. The CVT air intake assembly <NUM> is disposed on a right side of the engine <NUM> and defines a forwardly facing air inlet <NUM>. The CVT air intake assembly <NUM> includes a number of features such as internal walls to help prevent the entry of dust and water into the CVT housing <NUM>.

Returning to <FIG>, the drive pulley <NUM> is mounted to the rear end of the engine output shaft <NUM> extending rearwardly from the crankcase <NUM> so as to rotate therewith. The drive pulley <NUM> is disposed in the lower portion of the CVT housing <NUM>. The driven pulley <NUM> is mounted on the rear end of a shaft <NUM>. The driven pulley <NUM> is disposed above the drive pulley <NUM> in the illustrated embodiment of the vehicle <NUM>. It is however contemplated that the driven pulley <NUM> could be disposed in a different position with respect to the drive pulley <NUM>. It is contemplated that the driven pulley <NUM> could be disposed lower than the drive pulley <NUM>, for example, if the drive pulley <NUM> was connected to the engine output shaft <NUM> indirectly instead of directly as shown herein.

The input sprocket of the transfer case <NUM> is mounted to the front end of the shaft <NUM>. The output sprocket of the transfer case <NUM> is disposed vertically below the input sprocket and is laterally offset toward the left side thereof. The output sprocket of the transfer case <NUM> selectively engages the driveshaft <NUM> via a gear selection assembly (not shown) for rotating the driveshaft <NUM> and thereby the rear wheel <NUM>. The gear selection assembly is disposed inside the transfer case housing <NUM> in the illustrated embodiment of the vehicle <NUM>. It is however contemplated that the gear selection assembly could be disposed outside the transfer case housing <NUM>. The driveshaft <NUM> extends through the opening <NUM> (<FIG>) defined in the transfer case <NUM> to engage the gear selection assembly. The gear selection assembly includes a forward gear, a reverse gear and a neutral position.

Referring now to <FIG>, the rear end of the driveshaft <NUM> is connected to the gear assembly <NUM>. The gear assembly <NUM> includes a universal joint <NUM>, a pinion (not shown), a bevel gear (not shown) and a housing <NUM>. The pinion and bevel gear are disposed inside the housing <NUM>. The universal joint <NUM> is connected between the rear end of the driveshaft <NUM> and the pinion. The pinion engages the bevel gear which is fixed to the hub of the rear wheel <NUM>.

Returning to <FIG>, the CVT <NUM> will be described in more detail. The drive pulley <NUM> includes a movable sheave <NUM> that can move axially relative to a fixed sheave <NUM> to modify an effective diameter of the drive pulley <NUM>. The moveable sheave <NUM> has centrifugal weights that push the movable sheave <NUM> relative to the fixed sheave <NUM> as the speed of rotation of the drive pulley <NUM> increases such that the effective diameter of the drive pulley <NUM> increases. Similarly, the driven pulley <NUM> includes a movable sheave <NUM> that can move axially relative to a fixed sheave <NUM> to modify an effective diameter of the driven pulley <NUM>. The effective diameter of the driven pulley <NUM> is in inverse relationship to the effective diameter of the drive pulley <NUM>. The movable sheaves <NUM> and <NUM> are on opposite sides of the drive belt <NUM>.

Turning now to <FIG>, various electronic components of the vehicle <NUM> will be described.

The vehicle <NUM> includes an electronic control unit (ECU) <NUM> that receives signals from a number of sensors, some of which are described below, and uses these signals to control an operation of the engine <NUM> and other components of the vehicle <NUM>, such as the display cluster <NUM>. The ECU <NUM> includes a non-transitory computer readable medium (not shown) and a processor (not shown). The processor of the ECU <NUM> is configured to perform a number of operations including the methods for estimating wear of the drive belt <NUM> described below. The ECU <NUM> is electronically connected to an electronic storage unit <NUM>, such as a hard drive or a flash drive for example, which stores data sent from and/or to be used by the ECU <NUM> and stores a number of control maps, some of which are described below, to be used by the ECU <NUM>. It is contemplated that the storage unit <NUM> and/or the display cluster <NUM> could be integrated with the ECU <NUM>. It is also contemplated that the storage unit <NUM> could be split into multiple storage units. Similarly it is contemplated that the functions of the ECU <NUM> could be split between multiple ECUs.

Based on the signals received from at least some of the various sensors communicating with the ECU <NUM>, the ECU <NUM> controls the operation of the fuel injectors, the spark plugs <NUM> and the throttle body <NUM> in order to control an engine torque output by the engine <NUM> in order to control a speed and acceleration of the vehicle <NUM>.

Based on the signals received from some of the various sensors communicating with the ECU <NUM>, the ECU <NUM> causes the display cluster <NUM> to display various vehicle parameters, such as, but not limited to, vehicle speed, engine speed, fuel level, engine temperature, distance traveled (odometer function) and ambient temperature. The ECU <NUM> can also cause the display cluster <NUM> to display various warnings for the driver of the vehicle, such as, but not limited to, "check engine", "check tire pressure", "maintenance required" and "battery voltage low". These warnings can be words displayed on a screen or can be in the form of an icon displayed on the cluster or some other visual, auditory or haptic indicator.

In the present embodiment, the storage unit <NUM> stores two belt load maps <NUM>, <NUM>, a belt temperature map <NUM> and a vehicle speed estimation map <NUM> that are used in the methods described below. The storage unit <NUM> also stores other maps used by the ECU <NUM> to perform other control methods used in the operation of the vehicle, such as for controlling the operation of the engine <NUM>. The two belt load maps <NUM>, <NUM> are used to determine corresponding belt load factors <NUM>, <NUM> (<FIG>, <FIG>) based on different inputs. The belt temperature map <NUM> is used to determine a belt temperature factor <NUM> (<FIG>). The vehicle speed estimation map <NUM> is used to provide an estimated vehicle speed <NUM> (<FIG>) when the sensor responsible for providing a signal indicative of vehicle speed to the ECU <NUM> is unavailable, due to sensor failure for example, or is sending faulty signals. It is contemplated that the vehicle speed estimation map <NUM> could be a collection of maps the outputs of which can be used together to estimate the vehicle speed. It is contemplated that one or more of the maps <NUM>, <NUM>, <NUM> and <NUM> could be replaced by a table containing corresponding data or one or more equations used to provide the same output as the maps <NUM>, <NUM>, <NUM> and <NUM>. Also, although the same reference numerals for the maps <NUM>, <NUM>, <NUM>, <NUM> in the various methods described below, it is contemplated that the maps <NUM>, <NUM>, <NUM>, <NUM> could be different in different methods.

A vehicle or wheel speed sensor <NUM> communicates with the ECU <NUM> to provide a signal indicative of vehicle speed to the ECU <NUM>. In embodiments where the sensor <NUM> is a vehicle speed sensor <NUM>, the sensor <NUM> can be in the form of a global position system (GPS) unit that sends a vehicle position signal to the ECU <NUM>. Based on changes in position over time, which is obtained from the timer <NUM> described below or an internal timer of the ECU <NUM>, the ECU <NUM> is able to determine the vehicle speed. It is also contemplated that the GPS unit could have an integrated timer allowing it to calculate the vehicle speed and send a signal representative of the vehicle speed to the ECU <NUM>. The vehicle speed sensor <NUM> could also be a pitot tube or another type of sensor used to measure linear speed. In embodiments where the sensor <NUM> is a wheel speed sensor <NUM>, the wheel speed sensor <NUM> senses a rotational speed of a wheel, such as the rear wheel <NUM>, and sends a signal representative of this speed to the ECU <NUM>. The ECU <NUM> can then calculate the vehicle speed using this signal and the diameter of the rear wheel <NUM>. It is contemplated that the wheel speed sensor <NUM> could measure the rotational speed of one of the front wheels <NUM> instead. It is also contemplated that multiple wheel speed sensors <NUM> could be used to measure the rotational speed of two or all three wheels <NUM>, <NUM>. It is also contemplated that the sensor <NUM> could instead be used to sense a rotational speed of the driven pulley <NUM>, or a rotational speed of a rotating element operatively connecting the driven pulley <NUM> to the rear wheel <NUM>, such as the driveshaft <NUM>, the shaft <NUM> or part of the gear assembly <NUM> for example, and use the signal from the sensor <NUM> to determine vehicle speed. It is also contemplated that the vehicle <NUM> could be provided with both a vehicle speed sensor and a wheel speed sensor or any combination of the sensors described above that can be used to determine vehicle speed.

An engine speed sensor <NUM> communicates with the ECU <NUM> to provide a signal indicative of engine speed to the ECU <NUM>. In the present embodiment, the engine speed sensor <NUM> senses a rotational speed of the crankshaft of the engine <NUM>. In another embodiment, the engine speed sensor <NUM> senses a rotational speed of the output shaft <NUM> of the engine <NUM>. In another embodiment, the engine speed sensor <NUM> senses a rotational speed of the drive pulley <NUM> which rotates at the same speed as the crankshaft and the output shaft <NUM>.

An intake air temperature sensor <NUM> communicates with the ECU <NUM> to provide a signal indicative of the temperature of the air being supplied to the engine <NUM>. The intake air temperature sensor <NUM> is positioned to sense the temperature of the air in the air intake system <NUM>.

An intake air pressure sensor <NUM> communicates with the ECU <NUM> to provide a signal indicative of the pressure of the air being supplied to the engine <NUM>. The intake air pressure sensor <NUM> is positioned to sense the pressure of the air in the air intake system <NUM>. It is contemplated that a CVT housing pressure sensor positioned within the CVT housing <NUM> and in communication with the ECU <NUM> for providing a signal indicative of the pressure of the air within the CVT housing <NUM> could be provided.

An ambient air temperature sensor <NUM> communicates with the ECU <NUM> and senses ambient air temperature to provides a signal indicative of the temperature of the ambient air to the ECU <NUM>.

An atmospheric pressure sensor <NUM> communicates with the ECU <NUM> and senses atmospheric air pressure to provide a signal indicative of the atmospheric pressure to the ECU <NUM>.

A throttle position sensor <NUM> communicates with the ECU <NUM> and senses a position of the throttle valve of throttle body <NUM> to provide a signal indicative of this position to the ECU <NUM>.

A timer <NUM> communicates with the ECU <NUM> and provides signals indicative of time elapsed since the vehicle <NUM> has been turned on and/or the current time. The ECU <NUM> uses the time provided by the time <NUM> in various calculations.

Turning now to <FIG>, various methods for estimating wear of the drive belt <NUM> will be described. In each of these embodiments, two belt wear-affecting factors are determined based on various operating parameters of the vehicle. Belt wear-affecting factors are factors which are based on operating characteristics of the CVT <NUM> which will have an effect of the wear of the drive belt <NUM>. These include, but are not limited to, the load on the drive belt <NUM>, changes in speed of the drive belt <NUM>, the forces applied by the sheaves <NUM>, <NUM>, <NUM>, <NUM> on the drive belt <NUM>, the ratio of the effective diameters of the pulleys <NUM>, <NUM> (CVT ratio) and the temperature of the drive belt <NUM>. In all of the methods described below, the two belt wear-affecting factors used are the belt load factor <NUM> and the belt temperature factor <NUM>. The belt load factor <NUM> is associated with the load applied on the drive belt <NUM>. The belt temperature factor <NUM> is associated with the temperature of the drive belt <NUM>. It is contemplated that other factors could be used and that more or less than two factors could be used. The two belt wear-affecting factors are applied to a belt wear-representative parameter. The belt wear-representative parameter is a parameter that has a relation to the lifespan of the drive belt <NUM>. For example, some drive belt manufacturers rate the life of the drive belt <NUM> in terms of vehicle travel distance or in terms of drive belt use time. Other examples of belt wear-representative parameters include, but are not limited to, vehicle speed, drive belt rotations, engine rotations, and drive belt wear units. A drive belt wear unit is a generic parameter used to correlate to the lifespan of the drive belt <NUM>. For example, a drive belt that is rated for <NUM>, could be said to be rated for <NUM> drive belt wear units, but it does not have to be one-to-one as long as the other values used in the method are used accordingly. The methods described below use different belt wear-representative parameters.

When rating the life of a drive belt <NUM>, drive belt manufacturers make certain assumption regarding the way the drive belt <NUM> will be used and the environment the drive belt <NUM> will be used in. So a drive belt <NUM> rated for <NUM> of vehicle travel distance should need replacement after <NUM>. However, depending on how the drive belt <NUM> is used and the environment is used in, it may have to be replaced before <NUM> is reached, or may only need to be replaced after more than <NUM>. The belt wear-affecting factors are used to adjust the belt wear-representative parameter to be closer to a value corresponding to an equivalent amount of wear under "normal" operating conditions. For example, if the vehicle <NUM> travels <NUM> meters under the conditions corresponding to those used when rating the life of the drive belt <NUM>, the drive belt <NUM> will have the amount of wear expected from <NUM> meter of vehicle travel distance. However, if the vehicle <NUM> travels <NUM> meters but during hard acceleration and in a very hot environment, the drive belt <NUM> will wear more than in the previous example (i.e. under the conditions corresponding to those used when rating the life of the drive belt <NUM>). The belt wear-affecting factors are used to account for this extra wear. In the previous example, if the drive belt <NUM> has <NUM>% more wear than would normally be expected, then the belt wear-affecting factors, if properly determined, will adjust the <NUM> meters of actual vehicle travel distance to count as <NUM> meters of vehicle travel distance (i.e. <NUM> x <NUM>). Since the <NUM> meters of actual vehicle travel distance result in an amount of wear of the drive belt <NUM> equivalent to that which would be expected from <NUM> meters of vehicle travel distance under the conditions corresponding to those used when rating the life of the drive belt <NUM>, it is the vehicle travel distance adjusted by the belt wear-affecting factors (i.e. <NUM> meters), that is used to calculate the amount of life of the drive belt <NUM> that has been spent.

In the methods described below, various alternatives will be provided. It should be understood that alternatives proposed in one of the methods could be applied in the other methods even if these alternatives are not specifically recited in these other methods. Also, similar elements in the various methods have been labeled with the same reference numerals.

The methods described below also make reference to an operating parameter of the vehicle <NUM> called relative air charge, which is expressed as a percentage. Air charge corresponds to the quantity of air that is supplied in the cylinder of the engine <NUM> for one combustion cycle. Relative air charge represents the comparison of an air charge to a standard air charge occurring under certain predetermined conditions. The predetermined conditions can be Standard Temperature and Pressure (STP, <NUM> Celsius, <NUM> bar), Normal Temperature and Pressure (NTP, <NUM> Celsius, <NUM> Atmosphere), Standard Ambient Temperature and Pressure (SATP, <NUM> Celsius, <NUM> kPa), or some other temperature and pressure. As would be understood, the belt load map <NUM> will need to be modified depending on the predetermined conditions for temperature and pressure are used since, for a given air charge, the relative air charge will vary depending on which predetermined conditions are used to calculate the standard air charge. In the present embodiment, the relative air charge is calculated by the ECU <NUM> based on the engine speed, the intake air temperature, the intake air pressure, the atmospheric pressure and the throttle position sensed by the sensors <NUM>, <NUM>, <NUM>, <NUM> and <NUM> respectively. It is contemplated that the relative air charge could be determined by the ECU <NUM> by inputting the same operating parameters of the vehicle <NUM> into one or more maps or tables. It is also contemplated that the relative air charge could be determined using different operating parameters of the vehicle <NUM> depending on the sensors available. For example, in a vehicle equipped with an air flow meter sensing air flow through the air intake system, the air flow meter could be used to determine the relative air charge.

Turning now to <FIG>, a first method <NUM> for estimating wear of the drive belt <NUM> will be described. The method <NUM> begins by inputting a belt load-representative parameter and a belt speed-representative parameter into the belt load map <NUM>. In the method <NUM>, the belt load-representative parameter is relative air charge <NUM> and the belt speed-representative parameter is vehicle speed <NUM> in km/h. The air charge <NUM> is calculated by the ECU <NUM> as described above and the vehicle speed <NUM> is obtained by the ECU <NUM> from the signal received from the speed sensor <NUM>. It is contemplated that the relative air charge <NUM> and the vehicle speed <NUM> could be replaced by other belt load-representative and belt speed-representative parameters, with the belt load map <NUM> being modified accordingly. For example, it is contemplated that the relative air charge <NUM> could be replaced by engine load, engine torque, CVT ratio, air charge or any other engine parameter that correlates sufficiently with engine load, and the vehicle speed <NUM> could be replaced by engine speed, drive belt speed, a rotational speed of the driven pulley <NUM>, a rotational speed of the rear wheel <NUM>, the rotational speed of a rotating element operatively connecting the driven pulley <NUM> to the rear wheel <NUM>, or any other vehicle parameter that correlates sufficiently with belt speed.

As can be seen in <FIG>, in the belt load map <NUM>, for each combination of relative air charge <NUM> and vehicle speed <NUM> the map provides a corresponding belt load factor <NUM>. As can be seen in <FIG>, the relative air charge <NUM> goes up to a maximum relative air charge RACMAX. It is contemplated that the maximum relative air charge RACMAX could go above <NUM>%. As can also be seen in <FIG>, the minimum belt load factor is <NUM>, but it is contemplated that it could be less than one if the operation of the vehicle <NUM> result in less wear of the drive belt <NUM> than accounted for in a predetermined threshold belt wear distance, discussed further below. In the belt load map <NUM> shown in <FIG>, the belt load factor is <NUM> when the vehicle speed <NUM> is less than a transition vehicle speed VST or when the relative air charge <NUM> is less than a transition relative air charge RACT. This flat region is referred to herein as the normal wear region. Also, in the belt load map <NUM>, the belt load factor is greater than <NUM> when the vehicle speed <NUM> is greater than the transition vehicle speed VST and the relative air charge <NUM> is greater than the transition relative air charge RACT. This raised region is referred to herein as the extra wear region. As will be discussed below, the belt temperature map <NUM> also has a normal wear region and an extra wear regions. As long as the vehicle <NUM> is operated in the normal wear regions, the life of the drive belt <NUM> will be as expected, but operating the vehicle <NUM> in any one of the extra wear regions will result in a shorter belt life due to the extra wear experienced by the drive belt <NUM> when the vehicle <NUM> is operated under these conditions. The belt load map <NUM> and the belt temperature map <NUM> can be determined experimentally.

Returning to the method <NUM> in <FIG>, the ECU <NUM> obtains the belt load factor <NUM> from the belt load map <NUM>. Then the ECU <NUM> multiplies the belt load factor <NUM> by the vehicle speed <NUM> to obtain a load adjusted vehicle speed <NUM> (i.e. the vehicle speed <NUM> adjusted to take into consideration the belt load factor <NUM>). The vehicle speed <NUM> is equal to the vehicle speed <NUM> but expressed in meters per second instead of in kilometers per hour. As can be seen in <FIG>, this is done by dividing the vehicle speed <NUM> by <NUM>.

The method <NUM> continues by inputting a belt temperature-representative parameter into the belt temperature map <NUM>. In the method <NUM>, the belt temperature-representative parameter is ambient air temperature <NUM>. The ambient air temperature <NUM> is obtained by the ECU <NUM> from the signal received from the ambient air temperature sensor <NUM>, which correlates sufficiently with drive belt temperature in a vehicle such as the vehicle <NUM>. It is contemplated that the ambient air temperature <NUM> could be replaced by another belt temperature-representative parameter, with the belt temperature map <NUM> being modified accordingly. For example, it is contemplated that the ambient air temperature <NUM> could be replaced by CVT air intake temperature, CVT housing temperature, or drive belt temperature provided by a CVT air intake temperature sensor, a CVT housing air temperature sensor and a belt temperature sensor respectively. The CVT air intake temperature is a temperature of the air in the CVT air intake assembly <NUM>. The CVT housing temperature is a temperature of the air in the CVT housing <NUM>. The drive belt temperature is the actual temperature of the drive belt <NUM> sensed at a given location or locations along its travel path.

As can be seen in <FIG>, in the belt temperature map <NUM>, for each value of ambient air temperature <NUM> the map provides a corresponding belt temperature factor <NUM>. As can be seen in <FIG>, the air temperature varies between a minimum temperature Tmin and a maximum temperature Tmax. The values of the minimum temperature Tmin and the maximum temperature Tmax will vary depending on the specific vehicle and its operating environment. For example, in a snowmobile such as the snowmobile <NUM> described below, the range of temperatures would include lower temperatures than for the vehicle <NUM>. As can also be seen in <FIG>, the minimum belt temperature factor is <NUM>, but it is contemplated that it could be less than one if the operation of the vehicle <NUM> result in less wear of the drive belt <NUM> than accounted for in a predetermined threshold belt wear distance, discussed further below. In the belt temperature map <NUM> shown in <FIG>, the belt load factor is <NUM> when the ambient air temperature <NUM> is less than a transition temperature TT. This flat region is referred to herein as the normal wear region. Also, in the belt temperature map <NUM>, the belt temperature factor is greater than <NUM> when the ambient air temperature <NUM> is greater than the transition temperature TT. This raised region is referred to herein as the extra wear region.

Returning to the method <NUM> in <FIG>, the ECU <NUM> obtains the belt temperature factor <NUM> from the belt temperature map <NUM>. Then the ECU <NUM> multiplies the belt temperature factor <NUM> by the load adjusted vehicle speed <NUM> to obtain a load and temperature adjusted vehicle speed <NUM> (i.e. the load adjusted vehicle speed <NUM> adjusted to take into consideration the belt temperature factor <NUM>).

It is contemplated that the vehicle speed <NUM> could first be multiplied by the belt temperature factor <NUM> and that the result of this multiplication could then be multiplied by the belt load factor <NUM> to obtain the load and temperature adjusted vehicle speed <NUM>.

In the method <NUM> of <FIG>, drive belt life is estimated in terms of vehicle travel distance. As such, in this method a total belt wear-representative parameter is also estimated in terms of vehicle travel distance, which is referred to herein as the total belt wear distance <NUM>. As such, the load and temperature adjusted vehicle speed <NUM> is converted to distance by multiplying it by a time interval <NUM> to obtain an adjusted belt wear distance <NUM>. The time interval <NUM> corresponds to the time between each cycle of the method <NUM>. In one example, the time interval <NUM> is <NUM> milliseconds, but it could be more or less depending on the computing power of the ECU <NUM> and the response time of the sensors, amongst other factors.

The adjusted belt wear distance <NUM> is then added to the total belt wear distance <NUM> obtained from a previous cycle of the method <NUM> in order get an updated total belt wear distance <NUM>. When the drive belt <NUM> is brand new, the total belt wear distance <NUM> is zero meter and increases as the vehicle <NUM> is used. The total belt wear distance <NUM>, which is in meters, is then divided by <NUM> to have a total belt wear distance <NUM> in kilometers. The total belt wear distance <NUM> is then compared to the threshold belt wear distance. If the total belt wear distance <NUM> is greater than or equal to the threshold belt wear distance, the ECU <NUM> sends a signal to the display cluster <NUM> to provide an indication that there is a need for transmission maintenance or more generally that there is a need for maintenance on the vehicle. The method <NUM> is then repeated. In place of or in addition to controlling the display cluster <NUM> to provide an indication to the driver, it is contemplated that the ECU <NUM> could control the engine <NUM> to reduce engine performance, such as by reducing one or more of the maximum engine speed, opening of the throttle body <NUM>, fuel injection and spark timing.

In the present implementation, the threshold belt wear distance is set based on a use of the vehicle <NUM> operated within the normal wear regions of the operating parameters discussed herein. It is contemplated that in an alternate embodiment, the threshold belt wear distance could be set based on a use of the vehicle at least partially outside the normal wear regions and, in such cases, belt wear effecting factors, such as the belt load factor <NUM> and the belt temperature factor <NUM>, of between <NUM> and <NUM> could be output from their respective maps <NUM>, <NUM>, thereby accounting for use in operating conditions that produce less wear and downwardly adjusting the wear-representative parameter, such as distance travelled by the vehicle <NUM>.

During transmission maintenance, if the drive belt <NUM> is replaced by a new drive belt <NUM>, the technician making the change uses the display cluster <NUM>, an outside tool communicating with the ECU <NUM> or some other means of communicating with the ECU <NUM> to send a signal which indicates to the ECU <NUM> that a new belt <NUM> has been installed. Upon receiving this signal, the ECU <NUM> resets the total belt wear distance <NUM> to zero meter.

It is contemplated that the total belt wear distance <NUM> could be adjusted differently than by adding the adjusted belt wear distance <NUM> to the total belt wear distance. In an alternative embodiment, the total belt wear distance <NUM> starts at a predetermined value and the adjusted belt wear distance <NUM> is subtracted from the total belt wear distance <NUM>. The total belt wear distance <NUM> is then compared to a threshold belt wear distance. If the total belt wear distance <NUM> is less than or equal to the threshold belt wear distance, the ECU <NUM> sends a signal to the display cluster <NUM> to provide an indication that there is a need for transmission maintenance.

It is also contemplated that belt load map <NUM> and the belt temperature map <NUM> could have the same shape for providing their respective factors <NUM>, <NUM>, but that all of the values of the factors <NUM>, <NUM> would be one less than illustrated in <FIG> and <FIG>. As such the factors <NUM>, <NUM> would have a minimum value of <NUM> instead of <NUM>. Therefore, the load and temperature adjusted vehicle speed <NUM> would provide the variation of vehicle speed resulting from the factors <NUM>, <NUM> and the vehicle speed obtained at <NUM> would be added to the vehicle speed <NUM> before being multiplied by the time interval <NUM>. In an alternative embodiment using these modified maps <NUM>, <NUM>, the variation of vehicle speed obtained at <NUM> would be carried through up to <NUM> such that <NUM> would instead provided a variation in total wear distance (i.e. how much distance the extra wear corresponds to). This variation in total wear distance would then be added to the actual vehicle travel distance that is recorded in parallel. The result of this sum would then be compared to the threshold belt wear distance.

Turning now to <FIG>, another method <NUM> for estimating wear of the drive belt <NUM> will be described. The method <NUM> begins by inputting a belt speed-representative parameter into the belt load map <NUM>. In the method <NUM>, the belt speed-representative parameter is engine speed <NUM>. The engine speed <NUM> is obtained by the ECU <NUM> from the signal received from the engine speed sensor <NUM>.

As can be seen in <FIG>, in the belt load map <NUM>, for each value of engine speed <NUM> the map provides a corresponding belt load factor <NUM>. As can also be seen in <FIG>, the minimum belt load factor is <NUM>, but it is contemplated that it could be less than one if the operation of the vehicle <NUM> results in less wear of the drive belt <NUM> than expected. In the belt load map <NUM> shown in <FIG>, the belt load factor <NUM> is <NUM> when the engine speed <NUM> is less than a transition engine speed RPMT. This flat region is referred to herein as the normal wear region. Also, in the belt load map <NUM>, the belt load factor <NUM> is greater than <NUM> when the engine speed <NUM> is greater than the transition engine speed RPMT. This raised region is referred to herein as the extra wear region. The belt load map <NUM> can be determined experimentally.

Returning to the method <NUM> in <FIG>, the ECU <NUM> obtains the belt load factor <NUM> from the belt load map <NUM>. Then the ECU <NUM> multiplies the belt load factor <NUM> by the estimated vehicle speed <NUM> to obtain a load adjusted vehicle speed <NUM> (i.e. the estimated vehicle speed <NUM> adjusted to take into consideration the belt load factor <NUM>). The estimated vehicle speed <NUM> is obtained by the ECU <NUM> from the vehicle speed estimation map <NUM> into which the engine speed <NUM> has been provided as an input. It is contemplated that additional inputs could be provided in the vehicle speed estimation map <NUM> in order to obtain the estimated vehicle speed <NUM>.

The remaining steps of the method <NUM> are the same as those of the method <NUM> described above, and as such will not be described again.

In one embodiment, the ECU <NUM> uses both methods <NUM> and <NUM> for estimating wear of the drive belt <NUM>. In this embodiment, the ECU <NUM> starts by using the method <NUM>. Then, should the relative air charge <NUM> or the vehicle speed <NUM> become unavailable or has a faulty value, due to failure of a sensor or to a sensor sending faulty signals, the ECU <NUM> switches to the method <NUM> and uses engine speed <NUM> as a substitute operating parameter to the relative air charge <NUM> and the vehicle speed <NUM>. When switching to the method <NUM>, the total belt wear distance <NUM> in the method <NUM> is assigned the last valid value of the total belt wear distance <NUM> of the method <NUM>. Should the relative air charge <NUM> and the vehicle speed <NUM> become available again or no longer provide faulty values, the ECU <NUM> would then switch back to the method <NUM> and the total belt wear distance <NUM> in the method <NUM> is assigned the last value of the total belt wear distance <NUM> of the method <NUM>.

Turning now to <FIG>, another method <NUM> for estimating wear of the drive belt <NUM> will be described. The method <NUM> begins by determining the belt load factor <NUM> from the relative air charge <NUM> and the vehicle speed <NUM> as in the method <NUM>. The vehicle speed <NUM> is multiplied by the time interval <NUM> to obtain a distance <NUM> (i.e. a belt wear distance). The distance <NUM> is multiplied by the belt load factor <NUM> to obtain a load adjusted distance <NUM>. The belt temperature factor <NUM> is then determined as in the method <NUM>. The load adjusted distance <NUM> is then multiplied by the belt temperature factor <NUM> to obtain an adjusted belt wear distance <NUM>. The adjusted belt wear distance <NUM> is then added to the total belt wear distance <NUM> to obtain an updated total belt wear distance <NUM>. The updated total belt wear distance <NUM> is then compared to the threshold belt wear distance as in the method <NUM> to determine if an indication that transmission maintenance is needed should be provided. The method <NUM> then repeats.

Turning now to <FIG>, another method <NUM> for estimating wear of the drive belt <NUM> will be described. The method <NUM> is suitable for embodiments where a life span of the drive belt is expressed in terms of drive belt use time. The method <NUM> begins by determining the belt load factor <NUM> from the relative air charge <NUM> and the vehicle speed <NUM> as in the method <NUM>. The time interval <NUM>, which represent the drive belt used time for this cycle of the method <NUM>, is then multiplied by the belt load factor <NUM> to obtain a load adjusted time interval <NUM>. The belt temperature factor <NUM> is then determined as in the method <NUM>. The load adjusted time interval <NUM> is then multiplied by the belt temperature factor <NUM> to obtain an adjusted time interval <NUM>. The adjusted time interval <NUM> is then added to a total belt wear time <NUM> to obtain an updated total belt wear time <NUM>. The updated total belt wear time <NUM> is then compared to a threshold belt wear time to determine if an indication that transmission maintenance is needed should be provided. The method <NUM> then repeats.

It is contemplated that the method <NUM> could be modified to use a belt-wear representative parameter such as drive belt rotations, engine rotations or drive belt wear units instead of drive belt use time.

Turning now to <FIG>, another method <NUM> for estimating wear of the drive belt <NUM> will be described. The method <NUM> begins by determining the belt load factor <NUM> and the belt temperature factor <NUM> as in the method <NUM>. The belt load factor <NUM> is multiplied by a load weight <NUM> to obtain a load induced wear <NUM>. The load weight <NUM> is the belt wear-representative parameter to which a weight representative of the importance of the belt load factor <NUM> has been assigned. As such, the load induced wear <NUM> is the weighted belt wear-representative parameter adjusted to account for the belt load factor <NUM>. The belt temperature factor <NUM> is multiplied by a temperature weight <NUM> to obtain a temperature induced wear <NUM>. The temperature weight <NUM> is the belt wear-representative parameter to which a weight representative of the importance of the belt temperature factor <NUM> has been assigned. As such, the temperature induced wear <NUM> is the weighted belt wear-representative parameter adjusted to account for the belt temperature factor <NUM>. The load induced wear <NUM> and the temperature induced wear <NUM> are then added to get an estimated change in belt wear <NUM>. The estimated change in belt wear <NUM> is representative of the estimated amount of wear of the drive belt <NUM> for this cycle of the method <NUM>. The estimated change in belt wear <NUM> is then added to the total estimated belt wear <NUM> to obtain an updated estimated total belt wear <NUM>. The updated estimated total belt wear <NUM> is then compared to a threshold belt wear to determine if an indication that transmission maintenance is needed should be provided. The method <NUM> then repeats.

The method <NUM> will now be described in an example where the belt wear-representative parameter is drive belt wear units. For purposes of the present example, the normal amount of wear per cycle of the method <NUM> is <NUM> drive belt wear units. Also for purposes of the present example, the belt load factor <NUM> is considered to account for <NUM> percent of the wear of the drive belt <NUM> and the belt temperature factor <NUM> is considered to account for <NUM> percent of the wear of the drive belt <NUM>. As such, the load weight <NUM> is <NUM> drive belt wear units (i.e. <NUM>% of <NUM> drive belt wear units) and the temperature weight <NUM> is <NUM> drive belt wear units (i.e. <NUM>% of <NUM> drive belt wear units). If the belt load factor <NUM> is <NUM>, the load induced wear <NUM> is <NUM> drive belt wear units. If the belt temperature factor <NUM> is <NUM>, the temperature induced wear <NUM> is <NUM> drive belt wear units. The estimated change in belt wear <NUM> for this cycle is then <NUM> drive belt wear units (i.e. <NUM> plus <NUM>). As would be understood this is <NUM>% more than the normal amount of wear per cycle of the method <NUM> of <NUM> drive belt wear units. The <NUM> drive belt wear units are then added to the estimated total belt wear <NUM>, and the result is compared to a threshold wear expressed in terms of drive belt wear units which is related to a number of drive belt wear units at which the drive belt <NUM> should be replaced.

It is contemplated that the above methods <NUM>, <NUM>, <NUM>, <NUM>, <NUM> could be modified so as to use the same parameters as input, but that the adjusted belt wear-representative parameter could be obtained without using one or both factors <NUM>, <NUM>. In one example, the maps <NUM>, <NUM> could output an adjusted value of the parameter directly. In another example, one or both maps <NUM>, <NUM> could be omitted and the inputs that were previously used by the maps <NUM>, <NUM> could then be used to calculated the adjusted belt wear-representative parameter through other means.

One example of such an alternative embodiment of a method starts by sensing a belt load-representative parameter of the vehicle and a belt temperature-representative parameter of the vehicle. Then, an estimated change in belt wear based on the belt load-representative parameter and the belt temperature-representative parameter is determined. An estimated total belt wear is then adjusted based on the estimated change in belt wear to obtain an updated estimated total belt wear. The updated estimated total belt wear is compared to a threshold belt wear. If the updated estimated total belt wear is greater than or equal to the threshold belt wear, an indication of a need for maintenance on the vehicle is provided. The method is then repeated.

Turning now to <FIG>, examples of other vehicles equipped with a CVT and in which the above methods for estimating wear of the drive belt can be implemented will be described. These vehicles are an all-terrain vehicle (ATV) <NUM>, a snowmobile <NUM> and an off-road, side-by-side vehicle (SSV) <NUM>.

<FIG> shows the ATV <NUM>. The ATV <NUM> has four wheels <NUM>, a straddle-seat <NUM> to accommodate a driver and a passenger, and a handlebar <NUM> for steering the front wheels <NUM>. The engine (not shown) of the ATV <NUM> is disposed under the seat <NUM>. The engine is coupled to a CVT <NUM> disposed on the left side of the engine. The CVT <NUM> is operatively connected to the wheels <NUM>.

<FIG> shows the snowmobile <NUM>. In the snowmobile <NUM>, the ground engaging members are two front skis <NUM> and a rear drive track <NUM>, which differs from the vehicle <NUM>, the ATV <NUM> and the SSV <NUM> which have wheels as ground engaging members. The snowmobile also has a straddle-seat <NUM> to accommodate a driver, and a handlebar <NUM> for steering the front skis <NUM>. The engine (not shown) of the snowmobile <NUM> is disposed forwardly of the seat <NUM> laterally between the skis <NUM>. The engine is coupled to a CVT <NUM> (schematically shown) disposed on the left side of the engine. The CVT <NUM> is operatively connected to the drive track <NUM>.

Claim 1:
A method (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) for estimating wear of a polymer drive belt (<NUM>) of a continuously variable transmission, CVT (<NUM>, <NUM>, <NUM>, <NUM>), provided in a vehicle (<NUM>, <NUM>, <NUM>, <NUM>), the drive belt having a lifespan and the method (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising:
determining a first belt wear-affecting factor (<NUM>, <NUM>, <NUM>) based on at least one first operating parameter of the vehicle (<NUM>, <NUM>, <NUM>, <NUM>);
determining a second belt wear-affecting factor (<NUM>, <NUM>, <NUM>) based on at least one second operating parameter of the vehicle (<NUM>, <NUM>, <NUM>, <NUM>);
applying the first and second wear-affecting factors (<NUM>, <NUM>, <NUM>) to a belt wear-representative parameter having a relation to the lifespan of the belt to obtain an adjusted belt wear-representative parameter; and
adjusting a total belt wear-representative parameter based on the adjusted belt wear-representative parameter to obtain an updated total belt wear-representative parameter.