System and method for evaluating continuously variable transmission

Abstract

A system and method of evaluating a continuously variable transmission (CVT) on a vehicle (22) includes positioning the vehicle (22) having the CVT (26) on a test bench (24), where the test bench (24) includes rollers (58, 60) for receiving wheel assemblies (36, 38) of the vehicle (22), and where the vehicle (22) further includes a driveline (40) and an electronics system (28) including a transmission controller (50a). The vehicle (22) on the test bench (24) is operated to rotate a wheel assembly (36, 38) of the vehicle (22) through a drivetrain (40) of the vehicle (22). While operating a vehicle (22) on a test bench (24), a computer (54) acquires data from an electronic system (28) of the vehicle (22), where the data is used to determine, based on the acquired data, whether the CVT (26) is operating in an acceptable manner.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Provisional Application Serial No. 63 / 524,487, filed on June 30, 2024, the entire contents of which are incorporated herein by reference.

[0002] Background Technology and Technical Field This invention relates to a system and method for evaluating continuously variable transmissions (CVTs), and more particularly for evaluating CVTs of vehicles on a test bench.

[0003] A continuously variable transmission (CVT) is a known form of automatic transmission used in vehicles such as passenger cars. Unlike conventional automatic transmissions, CVTs can vary within a continuous range of gear ratios, while conventional automatic transmissions have multiple gears, each with a specific gear ratio. A CVT enables a vehicle's engine to operate within or at an optimal RPM range when the vehicle is traveling at different speeds. For example, this might include operating the engine within a specific optimal RPM range to produce the required power or torque levels or fuel consumption levels. Summary of the Invention

[0004] This invention provides a system and method for rapidly evaluating the operating performance of a CVT in a vehicle, and is particularly suitable for evaluating such transmissions in used vehicles.

[0005] According to one aspect of the invention, a method for evaluating a continuously variable transmission (CVT) in a vehicle includes: positioning a vehicle having a CVT on a test bench, the test bench including rollers for receiving wheel assemblies of the vehicle, and the vehicle including a drivetrain and an electronic system including a transmission controller. The method further includes: operating the vehicle on the test bench, thereby rotating the wheel assemblies of the vehicle via the vehicle's drivetrain; acquiring data from the vehicle's electronic system using a computer during the operation of the vehicle on the test bench; and determining, based on the acquired data, whether the CVT is operating in an acceptable manner.

[0006] In a particular aspect of this method, the acquired data includes data from the transmission controller, such as the target pulley ratio of the CVT and the actual pulley ratio of the CVT. The acquired data may additionally and / or alternatively include the rotational speeds of the CVT pulleys, such as the rotational speed of the CVT's driving pulley and / or the rotational speed of the driven pulley, such as the target speed and / or actual speed of the CVT pulleys, for example, the target speed and / or actual speed of the CVT's driving pulley and / or the target speed and / or actual speed of the driven pulley. The step of determining whether the CVT is operating in an acceptable manner may include analyzing the acquired data, for example, comparing the target pulley ratio of the CVT relative to the actual pulley ratio, and / or comparing the target speed of one or both of the CVT's driving or driven pulleys with the actual speed of the corresponding pulley, and / or the step of determining whether the CVT is operating in an acceptable manner may include comparing the acquired data with predetermined acceptable criteria.

[0007] According to another aspect, determining whether a CVT is operating in an acceptable manner may include evaluating the acquired data using an evaluation program (e.g., an evaluation program residing on a computer). This includes using the evaluation program to compare the acquired data with predetermined acceptable standards.

[0008] The steps of operating the vehicle on the test bench may include having a person operate the vehicle while it is on the test bench, and / or may additionally or additionally include accelerating the vehicle. The step of accelerating the vehicle may include accelerating the vehicle from a first speed to a second speed, for example, where the second speed is higher than the first speed, such as accelerating from zero or low speed to a highway speed, for example, in the range of 55 mph to 80 mph, or in the range of 60 mph to 80 mph. The step of accelerating the vehicle may be performed at a rate at which the CVT does not simulate a conventional multi-speed automatic transmission. That is, acceleration is performed at a rate at which the CVT does not simulate gear shifts. The step of determining whether the CVT is operating in an acceptable manner may include analyzing at least a portion of the acquired data.

[0009] Furthermore, determining whether the CVT is operating in an acceptable manner may include determining whether the CVT is slipping, including, for example, determining whether the CVT pulleys are slipping relative to the CVT belt. The step of determining whether the CVT is slipping may additionally include determining whether the CVT's driving pulley is slipping relative to the belt and / or whether the driven pulley is slipping relative to the belt.

[0010] According to another aspect of the invention, a system for evaluating a CVT in a vehicle includes: a test bench having rollers for receiving wheel assemblies of a vehicle equipped with a CVT; wherein the test bench is configured to enable the vehicle's drivetrain to drive the vehicle's wheels when the vehicle is placed on the test bench; the system further includes a computer configured to be operatively connected to the vehicle's electronic system, wherein the electronic system includes a transmission controller; and wherein the computer is configured to receive data from the electronic system during vehicle operation on the test bench; and the system is further configured to determine, based on the acquired data, whether the CVT is operating in an acceptable manner. In a specific embodiment, the system is operable to perform the methods discussed above.

[0011] This evaluation method and system can be used to evaluate CVTs in vehicles, including whether the CVT operates within predetermined requirements, and can also be used to diagnose specific components within the CVT that are prone to slippage. These and other objects, advantages, uses, and features of the invention will become apparent upon reading the following description in conjunction with the accompanying drawings. Attached Figure Description

[0012] Figure 1 It is a three-dimensional view of a vehicle with a continuously variable transmission (CVT) placed on a test bench for evaluation; Figure 2 yes Figure 1 Side view of the vehicle and test bench; Figure 3 yes Figure 1 A schematic partial illustration of the vehicle's powertrain system; Figure 4 yes Figure 1 A schematic partial diagram showing the connection between the vehicle's electrical system and diagnostic computing equipment; Figure 5 This is an exemplary schematic diagram showing the change of the CVT pulley ratio of the first vehicle and the vehicle speed over time; Figure 6 This is an exemplary schematic diagram showing the change of the CVT pulley ratio of the second vehicle with the vehicle speed over time; Figure 7 This is an exemplary schematic diagram showing the engine speed of the first vehicle and the speed of the CVT's drive pulley; Figure 8 This is an example schematic diagram showing the engine speed of the second vehicle and the speed of the CVT's drive pulley; Figure 9 This is a schematic diagram of a software program for analyzing acquired data according to one aspect of the present invention. Detailed Implementation

[0013] The invention will now be described with reference to the accompanying drawings, wherein the elements numbered in the following text correspond to the elements numbered in the drawings. Figure 1 and Figure 2 A system 20 for evaluating a vehicle 22 on a test bench 24 is shown. Specifically, the system 20 is used to evaluate the continuously variable transmission (CVT) 26 of the vehicle 22 by reading the on-board diagnostic parameter ID (“PID”) in the vehicle 22’s electronic system 28 while the vehicle 22 is running on the test bench 24. Figure 3 In the illustrated embodiment, as discussed in detail below, CVT 26 comprises a conventional CVT transmission and includes a pair of variable-diameter pulleys 30 and 32, with a belt 34 arranged around the pulleys 30 and 32. In the illustrated embodiment, pulley 30 is the driving pulley, and pulley 32 is the driven pulley. Vehicle electronics 28 issues commands to CVT 26 based on driving conditions (including load, throttle position, etc.) to achieve a specific desired gear ratio between pulleys 30 and 32. During operation, system 20 monitors the actual pulley gear ratio via readings from electronics 28 (e.g., under specific test conditions or parameters) and compares the actual pulley gear ratio with a target or specified pulley gear ratio to assess whether one or more pulleys 30 and 32 are slipping relative to belt 34.

[0014] As previously mentioned, vehicle 22 includes CVT 26, wherein vehicle 22 includes front tires, rear tires, wheel assemblies 36 and 38, and a transmission or powertrain 40. Figure 3 Vehicle 22 can be configured as front-wheel drive, rear-wheel drive, all-wheel drive, etc. According to... Figure 3 Understandably, in addition to CVT 26, powertrain 40 also includes engine 42 having crankshaft 44 connected to torque converter 46, which is connected to CVT 26. Driveshaft 48 is connected to CVT 26 and extends to drive one or more wheel assemblies 36, 38 of vehicle 22, for example, via a differential. In the illustrated embodiment, pulley 30 is configured as a driving pulley or input pulley, and pulley 32 is configured as a driven pulley or output pulley. Although connected via belt 34 as referred to herein, it should be understood that belt 34 includes belt or chain drive connection between pulley 30 and pulley 32, or other such connection, to transmit drive motion from driving pulley 30 to driven pulley 32.

[0015] Reference Figure 4The electronic system 28 of vehicle 22 is shown as including multiple electronic control units (ECUs) or controllers 50a-50d, which are illustrated herein in schematic form. It should be understood that vehicle 22 may include a number of ECUs or controllers different from those shown in 50a-50d. An on-board diagnostic data port 52 (e.g., which may be referred to as a data link connector (DLC), diagnostic connector, or diagnostic data link connector) is provided, through which a diagnostic computer or reader 54 can connect to the electronic system 28, for example, via a cable 56, to acquire data and / or exchange data with the electronic system 28. Specifically, computer 54 is configured to acquire data related to vehicle systems, sensors, electronic system 28, and other parameters via parameter ID (“PID”) (e.g., via a controller area network (CAN bus)). Computer 54 may be configured as a laptop, tablet, handheld device, etc., and computer 54 may include multiple computer units, including, for example, units for exchanging data between various vehicle communication protocols.

[0016] according to Figure 1 and Figure 2 It is understood that the test bench 24 is configured as a roller-braked test bench, having pairs of rollers 58, 60 for rotatably supporting the front tires, rear tires, and wheel assemblies 36, 38. The vehicle 22 is configured to operate on the test bench 24 such that the power system 40 drives one or more of the rollers 58, 60, wherein the rollers 58, 60 can provide rolling resistance to the drive wheels of the vehicle 22 through inertial resistance; alternatively, an electric motor 62 coupled to the rollers 58 of the test bench 24 may provide additional resistance to the driven wheels of the vehicle 22. Although in the illustrated embodiment, the test bench 24 is equipped with four pairs of rollers 58, 60 for each wheel assembly of the wheel assemblies 36, 38 of the vehicle 22, it should be understood that alternatively configured test benches may have fewer such pairs of rollers, for example, two sets of front wheels for a front-wheel-drive vehicle. Furthermore, it should be understood that, within the scope of this invention, alternative configurations and arrangements of roller-braced test benches or dynamometers may be employed.

[0017] During operation of vehicle 22, electronic system 28 sends commands to CVT 26, for example via transmission control module or transmission controller 50a, to determine, for example, the target or desired pulley ratio (PGR) of drive pulley 30 and driven pulley 32 when vehicle 22 is in motion, based on load conditions, throttle position, and other factors. Accordingly, electronic system 28 detects data to determine the actual PGR of pulleys 30 and 32 based on their rotational speeds (e.g., the detected RPMs of pulleys 30 and 32).

[0018] According to an embodiment of the invention, when the vehicle 22 is run on the test bench 24, a computer 54 is used to acquire PID data related to both the target PGR and the actual PGR from the electronic system 28, and then compares these data to evaluate the state of the CVT 26. For example, by comparing the target PGR and the actual PGR, it can be used to assess whether one or both of the pulleys 30 and 32 are slipping relative to the belt 34. That is, when the transmission controller instructs the CVT 26 to operate in a given state, by comparing the actual operating state, it can be used to assess whether the CVT 26 is operating as instructed, or whether the CVT 26 is within an acceptable deviation range relative to the given state.

[0019] In one implementation, vehicle 22 is tested by an operator seated inside the vehicle while it is positioned on test bench 24, wherein the operator depresses the accelerator pedal by foot. The accelerator position can be maintained at a sufficiently low position (i.e., engine load) to keep the engine rotational speed constant as vehicle speed increases. The operator maintains a constant engine RPM within a reasonable range—i.e., within the operator's level of control—which can be approximately +200 RPM or -200 RPM relative to a target RPM. This range can be a pre-set control range that is monitored during testing and provides indications and / or warnings to the operator during evaluation. In particular, keeping the vehicle at a sufficiently low accelerator position prevents the CVT transmission controller 50a from simulating a conventional multi-speed automatic transmission. In some vehicles equipped with CVTs, for example, when the operator depresses the accelerator, the vehicle transmission controller increases the engine RPM to provide feedback based on the driver's habitual engine response to a multi-speed automatic transmission, thereby causing the CVT transmission controller 50a to simulate a conventional automatic transmission. This simulation can be avoided by maintaining a sufficiently low throttle position. Furthermore, the test bench 24 is configured to provide a similar road load level to the drivetrain 40 via the rolling inertia of the rollers 58, 60 or optionally via the torque applied by the motor 62.

[0020] In a specific implementation, vehicle 22 can accelerate from zero to a speed equivalent to a highway speed as displayed on the speedometer, such as 60 mph to 80 mph. However, it should be understood that other testing methods and other throttle positions may be used instead of accelerating the vehicle from 0 mph to 60 to 80 mph. For example, the high speed or highway speed may also be 55 mph or lower. Therefore, the evaluation procedure may include acceleration from low or slow speeds to high speeds or highway speeds. However, it should be understood that the evaluation system and method according to the invention may include running vehicle 22 on test bench 24 in an alternative manner. Furthermore, CVT 26 may also be evaluated without operating vehicle 22 on test bench 24, but rather on a road or runway.

[0021] The operator can observe the output of the electronic system 28 through the computer 54 to monitor the operation of the vehicle 22 during the test, for example, on the display screen 55 of the computer 54. Figure 9 The output of the electronic system 28 is observed on the computer 54. Alternatively and / or additionally, the computer 54 may be equipped with a test procedure protocol or monitoring display to provide visual or other feedback to the operator during testing, thereby guiding the operator to properly perform or operate the vehicle on the test bench 24 within predetermined desired parameters (e.g., throttle position, engine RPM, speed, and / or time). This can help obtain a consistent percentage and consistency of throttle application. For example, during an evaluation process in which the operator evaluates the CVT 26 of the vehicle 22 on the test bench 24, displays and feedback regarding the evaluation can be presented to the operator via the screen 55 of the computer 54. Such data may include, for example, an engine RPM display and a vehicle speed display, as well as step-by-step instructions for performing the evaluation. The evaluation procedure 74 on the computer 54 ( Figure 9 It can be used to display data and instructions to the operator.

[0022] As previously described, when vehicle 22 is running on test bench 24, on-board diagnostic PID data from electronic system 28 is recorded by computer 54 for evaluation of CVT 26 (e.g., via evaluation procedure 74). Specifically, computer 54 can be used to capture target PGR, actual PGR, relative throttle position, and vehicle speed. Vehicle speed can be obtained from PID data associated with the speedometer on vehicle 22, and / or can be obtained based on the rolling speed of rollers 58 and / or 60 on test bench 24.

[0023] Data processing of the recorded information can be performed to determine CVT 26 based on the evaluation process. (See reference...) Figure 5 and Figure 6The evaluation of the acquired data may include a graphical assessment of the deviation between the target PGR and the actual PGR relative to the vehicle speed, during which the vehicle 22 accelerates on the test bench 24. See details [link to relevant documentation]. Figure 5 For a given vehicle 22, a pulley ratio comparison 72 is shown in percentage form of vehicle speed data 70 relative to target PGR data and actual PGR data. The ratio comparison 72 can be calculated, for example, according to the formula “target PGR / actual PGR - 1”, where the plotted result is zero when the target PGR and actual PGR are equal. Figure 5 The transmission ratio comparison chart 72, ranging from approximately 23,000 milliseconds to 40,000 milliseconds, shows that the target PGR and actual PGR of vehicle 22 are approximately equal, thus presenting a basically straight line. Therefore, this indicates that the CVT 26 of vehicle 22 being tested or evaluated is operating as expected. In other words, there is no significant deviation between the target PGR and the actual PGR, therefore CVT 26 can be considered to be operating within acceptable parameters or specifications.

[0024] Please note that in Figure 5 In the process of achieving maximum speed, when the operator begins to remove his / her foot from the accelerator pedal (i.e., "tip-out"), the plotted gear ratio comparison 72 shows an inflection point that occurs after 40,000 milliseconds. Therefore, the evaluation of data acquired by computer 54 from electronic system 28 can be limited to data acquired before tip-out; for example, evaluation program 74 can use the tip-out inflection point to automatically limit the data used for evaluation. Similarly, the gear ratio comparison 72 plotted during initial testing may fluctuate, making the initial data unusable for evaluation. Therefore, data may not be available for the entire operating range, or not all acquired data may be suitable for data analysis to assess whether CVT 26 is slipping.

[0025] Furthermore, data evaluation may include adjusting or offsetting the acquired target PGR data and actual PGR data relative to each other to accommodate the mechanical lag time between the transmission controller 50a issuing the gear ratio command signal and the actual gear ratio of the CVT 26 pulleys 30, 32 being obtained based on the signal from controller 50a. For example, the target PGR data acquired at a given time may be compared with the actual PGR data acquired after a delay time Δ to accommodate the mechanical lag time. For example, the PID data or signal of the target PGR may be acquired or updated every 50 to 100 milliseconds, while the mechanical adjustment of the actual PGR requires a certain amount of time in contrast.

[0026] Figure 6 Showing with Figure 5 The publicly disclosed comparisons of similar acquired data, however, pertain to different vehicles of the same brand and model22. For example... Figure 6 The transmission ratio comparison is shown in Figure 72. Figure 5 Compared to Figure 72, a significant difference exists between the target PGR and the actual PGR within the same time range of approximately 23,000 ms to 40,000 ms. This indicates that... Figure 6 The CVT 26 in the tested vehicle 22 did not operate as expected, for example, due to mechanical slippage of one or more pulleys 30, 32 relative to belt 34.

[0027] It should be recognized that alternative data analysis or comparison methods can be used for the target PGR and the actual PGR. These include, for example, summing the differences between the target PGR and the actual PGR (e.g., for each data point), summing the squares of the differences, establishing a best-fit error line and calculating the PGR deviation from that error line, calculating the area under the curve (actual PGR - target PGR) over time, or using other methods and approaches.

[0028] Furthermore, it should be recognized that computer 54 may contain one or more programs for directly evaluating the aforementioned data and / or providing feedback to the operator; for example, the computer may contain evaluation program 74. For instance, computer 54 may perform data analysis through program 74 and provide the operator with an indication of whether the CVT is considered to be operating in an acceptable manner based on pre-set criteria. For example, the program may provide text indicators or colors, such as green or red to indicate success or failure. While it may display to the operator, such as... Figure 5 and Figure 6 The data is in the form of a computer 54, but the CVT evaluation system and evaluation program 74 can perform data analysis and, for example, provide the operator with an indication of whether the CVT is considered to be operating in an acceptable manner based on a pre-set standard programmed in the program 74 (the data is compared or evaluated relative to that pre-set standard).

[0029] In the case where CVT 26 is determined to be slipping as described above, the acquired data can also be evaluated to determine which of the driving pulley 30 or the driven pulley 32 is slipping relative to belt 34. Figure 7 and Figure 8 Data analysis for this purpose is shown based on an evaluation of the engine RPM relative to the RPM of the drive pulley 30. For this purpose, the computer 54 can obtain PID data regarding the speed of the drive pulley 30 and / or the driven pulley 32, as well as PID data regarding the engine RPM as described above. See details... Figure 7For a given vehicle 22, the plotted engine RPM and drive pulley 30 RPM are shown to be roughly smooth and matched within a roughly horizontal region between the upper and lower limits, thus indicating that drive pulley 30 is not slipping. If CVT 26 has previously been determined to be slipping, then excluding slippage of drive pulley 30, it can be inferred that driven pulley 32 is slipping relative to belt 34. (Refer to...) Figure 8 In contrast, the engine RPM and drive pulley RPM plotted for a different vehicle 22 are compared with... Figure 7 Similar sections exhibit numerous fluctuations or bumps. This indicates that the drive pulley 30 is slipping, and the torque converter 46 has sufficient rigidity to transmit this vibration back to the crankshaft 44, thus affecting the engine RPM. Although not shown in the figure, it should be recognized that a similar data analysis of the engine RPM relative to the driven pulley 32 RPM can be performed. Furthermore, it should be recognized that the intervention of the torque converter 46 may play a role in comparing the engine RPM and the speed of the drive pulley 30, for example, because the torque peak in a non-shift transmission is significantly lower, the torque converter 46 is typically locked. Additionally, the difference between the target PGR and the actual PGR can itself be used to identify whether either the drive pulley 30 or the driven pulley 32 is slipping. Similarly, the acquired data can be evaluated by running an evaluation program (e.g., evaluation program 74) on the computer 54 to determine which of the drive pulley 30 or the driven pulley 32 is slipping relative to the belt 34.

[0030] Figure 9 An evaluation program 74 residing on computer 54 is schematically depicted. As described above, this evaluation program performs data analysis on PID data, such as target PGR, actual PGR, engine speed, drive pulley and driven pulley speeds, and time. It should be understood that program 74 can be a single program module or multiple program modules running concurrently. Furthermore, as described above, program 74 can instruct the operator on vehicle 22 on test bench 24 and provide textual and / or visual instructions indicating whether CVT 26 of vehicle 22 is considered acceptable. The assessment of the acceptability of CVT 26 based on data analysis can be based on preset limits established in program 74, which can be obtained through statistical analysis of multiple vehicles of the same brand and model, or vehicles equipped with the same CVT transmission, or through other similar comparative analysis methods. For example, the predetermined limits can be based on acceptable deviations between actual PGR and target PGR. Furthermore, although this example illustrates data analysis using computer 54 located near vehicle 22, it should be understood that more than one computer can also be used, including scenarios where data is transferred to a remote computer for data analysis.

[0031] According to various aspects of the invention, the CVT evaluation system 20 thus includes a test bench 24 on which a vehicle 22 operates, while data is acquired from and / or monitored by a computer 54 and an evaluation program 74 from the vehicle 22's electronic systems 28. The method includes driving the vehicle 22 onto the test bench 24 and operating the vehicle 22 on the test bench 24, for example, operating the vehicle 22 on the test bench 24 within predetermined limits or parameters. The method also includes acquiring data from the vehicle 22's electronic systems 28, for example, by the computer 54 during the operation of the evaluation program 74, and processing the data to evaluate the CVT.

[0032] Without departing from the principles of this invention, changes and modifications may be made to the specific embodiments described herein. This invention is limited only by the scope of the appended claims and is interpreted in accordance with the principles of patent law (including the doctrine of equivalents).

Claims

1. A method of evaluating a continuously variable transmission (CVT) on a vehicle, the method comprising: positioning a vehicle having a CVT on a test stand, wherein the test stand includes rollers for receiving wheel assemblies of the vehicle, and wherein the vehicle further includes a drivetrain and an electronic system including a transmission controller; operating the vehicle on the test stand such that the wheel assemblies of the vehicle are rotated through the drivetrain of the vehicle; acquiring data from the electronic system of the vehicle with a computer during operation of the vehicle on the test stand; and determining whether the CVT is operating in an acceptable manner based on the acquired data.

2. The method of claim 1, wherein, The acquired data includes data from the transmission controller of the vehicle.

3. The method of claim 1, wherein, The acquired data includes a target pulley ratio of the CVT and an actual pulley ratio of the CVT.

4. The method of any one of claims 1 to 3, wherein, The acquired data includes a rotational speed of a drive pulley of the CVT and / or a rotational speed of a driven pulley of the CVT.

5. The method of any one of claims 1 to 3, wherein, The determining includes analyzing the acquired data by comparing the target pulley ratio of the CVT to the actual pulley ratio of the CVT.

6. The method of claim 5, wherein, The determining includes comparing the acquired data to predetermined acceptable criteria.

7. The method of any one of claims 1 to 3, wherein, The determining includes evaluating the acquired data by an evaluation program resident on the computer.

8. The method of any one of claims 1 to 3, wherein, Operating the vehicle on the test stand includes operating the vehicle by a person while the vehicle is on the test stand.

9. The method of claim 8, wherein, The operating includes accelerating the vehicle from a first speed to a second speed, and wherein the second speed is higher than the first speed.

10. The method of claim 9, wherein, Accelerating the vehicle to the second speed includes accelerating the vehicle to a highway speed.

11. The method of any one of claims 1 to 3, wherein, The determining includes analyzing a portion of the acquired data.

12. The method of any one of claims 1 to 3, wherein, Determining whether the CVT is operating in an acceptable manner includes determining whether the CVT is slipping, and wherein determining whether the CVT is slipping includes determining whether a pulley of the CVT is slipping relative to a belt of the CVT.

13. The method of claim 12, wherein, Determining whether the CVT is slipping includes determining whether a drive pulley of the CVT is slipping relative to the belt and / or whether a driven pulley is slipping relative to the belt.

14. A method of evaluating a continuously variable transmission (CVT) on a vehicle, the method comprising: positioning a vehicle having a CVT on a test stand, wherein the test stand includes rollers for receiving wheel assemblies of the vehicle, and wherein the vehicle further includes a drivetrain and an electronic system including a transmission controller; operating the vehicle on the test stand such that the wheel assemblies of the vehicle are rotated through the drivetrain of the vehicle; acquiring data from the electronic system of the vehicle with a computer during operation of the vehicle on the test stand, wherein the acquired data includes a target pulley ratio of the CVT and an actual pulley ratio of the CVT; and determining whether the CVT is operating in an acceptable manner based on the acquired data. determining, based on the acquired data, whether the CVT is operating in an acceptable manner, and wherein the determining includes analyzing the acquired data by comparing a target pulley ratio of the CVT to an actual pulley ratio of the CVT.

15. The method of claim 14, wherein, The acquired data includes data from a transmission controller of the vehicle.

16. The method of claim 14, wherein, The acquired data further includes a rotational speed of a drive pulley of the CVT and / or a rotational speed of a driven pulley of the CVT.

17. The method of any one of claims 14 to 16, wherein, Analyzing the acquired data includes comparing the acquired data to predetermined acceptable standards.

18. A system for evaluating a continuously variable transmission (CVT) on a vehicle, the system comprising: a test stand having a roller for receiving a wheel assembly of a vehicle equipped with a CVT, wherein the test stand is configured to enable a drivetrain of the vehicle to drive the wheels of the vehicle when the vehicle is placed on the test stand; a computer configured to be operatively connected to an electronic system of the vehicle, wherein the electronic system includes a transmission controller; wherein the computer is configured to receive data from the electronic system during operation of the vehicle on the test stand, and wherein the system is further configured to determine, based on the acquired data, whether the CVT is operating in an acceptable manner.

19. The system of claim 18, wherein, The acquired data includes a target pulley ratio of the CVT and an actual pulley ratio of the CVT, and wherein the system is configured to determine whether the CVT is operating in an acceptable manner by comparing the target pulley ratio of the CVT to the actual pulley ratio of the CVT.

20. The system of claim 18 or 19, wherein, The acquired data includes a rotational speed of a drive pulley of the CVT and / or a rotational speed of a driven pulley of the CVT.

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