FIELD OF THE DISCLOSURE

The present disclosure generally relates to vehicle diagnostic systems, and more particularly to diagnostic systems for a drive belt used in a continuously variable transmission (CVT).

BACKGROUND OF THE DISCLOSURE

Conventional vehicles, including utility vehicles and side-by-side vehicles, have an internal combustion engine that generates drive torque. To drive pistons of the engine, an air/fuel mixture combusts within cylinders and the air/fuel mixture is regulated via intake and exhaust valves. The intake valves are selectively opened to draw air into the cylinders, and the air is mixed with fuel to form the air/fuel mixture. To allow exhaust gas to exit from the cylinders after combustion, the exhaust valves are selectively opened at a specific time.

Continuously variable transmissions (CVTs) are typically installed in recreational vehicles, such as snowmobiles and all-terrain vehicles. The CVT provides an infinite number of different gears that are effective at transmitting torque from the engine to an output driveline of the transmission. The output driveline operatively couples the transmission to at least one ground engaging member.

However, due to a belted construction of the CVT, one of the drawbacks is that a drive belt of the CVT tends to wear out and become damaged prematurely when the drive belt is not broken in properly or used excessively under undesirable conditions. Since the drive belt solely transmits the engine power from a drive pulley to a driven pulley of the CVT, the drive belt is an important component of the CVT. Typically, the CVT drive belt is a V-belt, and is made from rubber, usually fiber-reinforced, that is rigid across but flexible along its length. During operation the drive belt undergoes extreme pressure and friction.

When the drive belt loses pressure between the sheaves of the CVT under high-load or over-load conditions, a slippage may occur causing belt damage, such as a spin-burn or hour-glassing event. For example, during the spin-burn event, a belt temperature may rapidly reach over 200 degrees Fahrenheit (° F.) without any warning, and may continue to rise up to 400° F. if no remedial action is taken. At that point, the drive belt is irreparably damaged, and without replacing the damaged drive belt, the vehicle cannot operate, thereby incurring increased maintenance costs and repair time.

As such, there are opportunities to develop an improved diagnostic system and method that can automatically detect or predict a fault of the drive belt before potential belt damage.

SUMMARY OF THE DISCLOSURE

As discussed in greater detail below, an exemplary diagnostic system provides an enhanced diagnostic function for detecting the fault of the CVT drive belt using various circuits and other related systems. In an exemplary diagnostic system and method the monitoring of the operating parameters and the detecting the fault of the CVT drive belt are performed automatically.

Also included in the present disclosure is a system and method configured for monitoring patterns of operating parameter variations during a predetermined time period based on historical information of a comparative logic or algorithm. Further, the present diagnostic system provides enhanced displays and relations of the operating parameters in real time. Additionally, the operating parameters are displayed automatically without substantial manual interruptions. As a result, the overall operational time of an engine system is enhanced without incurring additional operating expenses and maintenance costs.

In one exemplary embodiment, a vehicle diagnostic method of a vehicle including an internal combustion engine and a continuously variable transmission (CVT) operatively coupled to the internal combustion engine is provided. The method comprising the steps of detecting at least one engine crankshaft acceleration variation event of the vehicle using a detection circuit; determining at least one operating parameter received from one or more sensors associated with an operation of the CVT using a monitoring circuit; and determining based on the at least one operating parameter when the at least one detected engine crankshaft acceleration variation is related to a fault of the drive belt of the CVT using an alert circuit. In one example, the diagnostic method further comprises including an environmental condition parameter as the at least one operating parameter, wherein the environmental condition parameter includes at least one of a fuel state signal, an engine coolant temperature signal, a drive belt temperature signal, and a clutch state signal. In another example, the diagnostic method further comprises including an engine-based parameter as the at least one operating parameter, wherein the engine-based parameter is related to at least one of a crankshaft acceleration signal, an engine torque signal, and a transmission gear position signal. In a further example, the diagnostic method further comprises including a driveline-based parameter as the at least one operating parameter, wherein the driveline-based parameter is related to at least one of a vehicle speed signal, an engine speed signal, and a wheel speed signal. In still another example, the diagnostic method further comprises detecting the at least one engine crankshaft acceleration variation event by measuring an acceleration or deceleration rate of a crankshaft acceleration signal. In yet another example, the diagnostic method further comprises detecting the at least one engine crankshaft acceleration variation event based on a variation pattern of the operating parameter measured during a predetermined time period. In a variation thereof, the diagnostic method further comprises determining whether a frequency of the variation pattern is greater than a predetermined threshold. In another variation thereof the diagnostic method further comprises determining whether a pattern time period of the variation pattern is greater than a predetermined time period. In a refinement of the variation thereof the diagnostic method further comprises determining whether a magnitude of the variation pattern. In a further example, the diagnostic method further comprises performing a first correction method for determining whether the engine crankshaft acceleration variation event is caused by a belt slipping event or an engine combustion misfire event based on a single occurrence of the at least one engine crankshaft acceleration variation event. In a yet further example, the diagnostic method further comprises performing a second correction method for determining whether the engine crankshaft acceleration variation event is caused by a belt slipping event or an engine combustion misfire event based on a plurality of occurrences of the at least one engine crankshaft acceleration variation event.

In another exemplary embodiment, a vehicle diagnostic method of a vehicle including an internal combustion engine and a continuously variable transmission (CVT) operatively coupled to the internal combustion engine is provided. The method comprising determining at least one operating parameter received from one or more sensors associated with an operation of the CVT using a monitoring circuit; detecting at least one belt slipping event of a drive belt of the CVT using a detection circuit; determining based on the at least one operating parameter when the at least one detected belt slipping event is related to an impending fault of the drive belt of the CVT using an alert circuit; and notifying the impending fault of the drive belt before belt or driveline damage of the vehicle occurs using the alert circuit. In one example, the diagnostic method further comprises generating an information signal related to the impending fault of the drive belt. In another example, the diagnostic method further comprises providing an option to override a user input by adjusting at least one value of the at least one operating parameter. In a further example, the diagnostic method further comprises detecting the at least one belt slipping event by the detection circuit in at least one of a retroactive control mode and an active control mode. In yet another example, the diagnostic method further comprises receiving a desired vehicle input parameter using the monitoring circuit. In still another example, the diagnostic method further comprises including an environmental condition parameter as the at least one operating parameter. In yet still another example, the diagnostic method further comprises including an engine-based parameter as the at least one operating parameter. In yet a further example, the diagnostic method further comprises including a driveline-based parameter as the at least one operating parameter. In still yet a further example, the diagnostic method further comprises detecting the belt slipping event based on a comparison of an engine-based parameter and a driveline-based parameter for predicting the impending fault of the drive belt. In a variation thereof, the diagnostic method further comprises determining whether at least one of the engine-based parameter and the driveline-based parameter is greater than a predetermined threshold. In a further still example, the diagnostic method further comprises informing the at least one detected belt slipping event using a display; and automatically adjusting the at least one operating parameter based on a predetermined table.

In a further exemplary embodiment, a vehicle diagnostic method of a vehicle including an internal combustion engine and a continuously variable transmission (CVT) operatively coupled to the internal combustion engine is provided. The method comprising the steps of: determining at least one operating parameter received from one or more sensors associated with an operation of the CVT using a monitoring circuit; detecting at least one critical belt life event of a drive belt of the CVT using a detection circuit; determining based on the at least one operating parameter when the at least one detected critical belt life event is related to a fault of the drive belt of the CVT using an alert circuit; and generating an information signal related to a life of the drive belt using the alert circuit. In an example, the diagnostic method further comprises including an environmental condition parameter as the at least one operating parameter, wherein the environmental condition parameter includes a temperature signal. In a further example, the diagnostic method further comprises including an engine-based parameter as the at least one operating parameter, wherein the engine-based parameter is related to at least one of an engine load signal, a throttle position signal, an engine torque signal, and an engine power signal. In yet a further example, the diagnostic method further comprises including a driveline-based parameter as the at least one operating parameter, wherein the driveline-based parameter is related to at least one of a vehicle speed signal and an engine speed signal. In still a further example, the diagnostic method further comprises detecting the critical belt life event based on a comparison of an engine-based parameter, a driveline-based parameter, and an environmental condition parameter; and predicting a remaining life of the drive belt based on the comparison. In a variation thereof, the diagnostic method further comprises determining whether the remaining life of the drive belt is less than a predetermined threshold. In another variation thereof, the diagnostic method further comprises displaying the information signal on a display using a textual or graphical indicator associated with the remaining life of the drive belt. In another example, the diagnostic method further comprises adjusting at least one of an engine-based parameter, a driveline-based parameter, and an environmental condition parameter based on the at least one detected critical belt life event.

In a further exemplary embodiment of the present disclosure, a vehicle diagnostic method of a vehicle including an internal combustion engine and a continuously variable transmission (CVT) operatively coupled to the internal combustion engine is provided. The method comprising the steps of: determining an amount of input energy provided to the CVT by the internal combustion engine; determining an amount of output thermal energy leaving the CVT; determining based on the amount of input energy and the amount of output thermal energy an amount of accumulated energy in the CVT; comparing the amount of accumulated energy to a threshold; and reducing the amount of input energy in response to the amount of accumulated energy satisfying the threshold. In an example thereof, the step of reducing the amount of input energy includes the step of reducing the power provided by the internal combustion engine to the CVT. In another example, the amount of input energy is determined based on mechanical input characteristics to the CVT. In yet another example, the amount of output thermal energy is determined based on fluid characteristics of the CVT. In still another example, the step of determining the amount of input energy provided to the CVT by the internal combustion engine includes the steps of: determining an output power of the internal combustion engine; determining a CVT clutch efficiency based on the determined output power; and determining the amount of input energy provided to the CVT based on the determined output power and the determined CVT clutch efficiency. In a variation thereof, the step of determining the CVT clutch efficiency based on the determined output power includes the step of retrieving from a database the determined CVT clutch efficiency. In yet still another example, the step of determining the amount of output thermal energy leaving the CVT includes the steps of: determining an air temperature of air entering an interior of the CVT; and determining the amount of output thermal energy leaving the CVT based on a CVT clutch airflow model, a heat transfer coefficient, and the determined air temperature.

In a yet further exemplary embodiment of the present disclosure, a vehicle diagnostic method of a vehicle including an internal combustion engine and a continuously variable transmission (CVT) operatively coupled to the internal combustion engine. The method comprising the steps of: detecting a plurality of engine crankshaft acceleration variation events; determining a frequency of the plurality of engine crankshaft acceleration variation events; determining a CVT belt interaction frequency of a drive belt of the CVT; and classifying the plurality of engine crankshaft acceleration variation events as one of an engine misfire event and a CVT belt damage event based on a comparison of the frequency to the CVT belt interaction frequency. In an example thereof, the step of determining the CVT belt interaction frequency of the drive belt of the CVT includes the steps of: determining a pitch diameter of a drive clutch of the CVT; determining a linear speed of the drive belt of the CVT based on the determined pitch diameter of the drive clutch and a rotational speed of a drive shaft of the CVT; and determining the CVT belt interaction frequency of the drive belt based on the determined linear speed of the drive belt of the CVT and a length of the belt.

Additional features and advantages of the present disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.

