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Torque Converter Testing and Evaluation
Project BriefThe Drivetrain Engineering torque converter stand is configured to allow testing and evaluation of automatic transmission torque converters, independent of the transmission, while still maintaining full operating conditions.
At Southwest Research Institute (SwRI), the torque converter is mounted in a headstand with the flywheel attached to a ball bearing and spindle assembly. A separate spindle and bearing assembly are mounted in precision fixtures to support the torque converter, replicate the input shaft, and provide automatic transmission fluid (ATF) passage through the torque converter. Flow to the torque converter is provided by a remotely located 20-hp pump and motor. Pressure regulators are located on the charge and discharge lines to simulate back pressures imposed by the transmission.
To eliminate the effects of ATF fluid temperature on torque converter performance, a fluid temperature control circuit is incorporated. The circuit consists of a two-pass heat exchanger and a low-watt-density immersion heater in a closed-loop PID control circuit located in a remote control room. The system is capable of ±2° ATF temperature control through a temperature range of 100 to 300°F for all but heavy stall conditions.
Flow through the torque converter is measured in a non-obtrusive, coriolis-type flow meter that provides real-time mass flow that is insensitive to viscosity.
Input power to the torque converter is supplied by a 175-hp AC motor configured with a constant torque device and a precision speed regulation device for precision closed-loop PID control capable of ±1 rpm and ±1 ft-lb. The torque capacity of the system is 250 ft-lbs. The motor is configured with containment rings and high-speed bearings to allow operation to 4,500 rpm.
Located between the motor and torque converter is a 0.25 percent accurate strain-gauge-type, in-line torque transducer that also houses an active magnetic pickup. Headstand bearing losses are measured and subtracted from the motor torque to determine actual input torque to the converter.
Output from the torque converter is through a 575-hp DC dynamometer, in tandem with a 2:1 reduction gearbox, allowing speeds to 6,000 rpm and torques to 3,000 ft•lb. An in-line torque transducer is also located downstream of the torque converter.
Automated data acquisition occurs during testing, along with a computer monitor display of test parameters and various real-time equations.
Converter testing includes the following:
Testing and evaluation is focused on determining the speed or speed ratio at which the clutch point occurs. Beyond this point, the converter acts as fluid coupling, and little additional information beyond parasitic drag information is obtained.
For more information about our drivetrain engineering capabilities and past performance briefs, or how you can contract with SwRI, please contact Douglas Fussner at dfussner@swri.org or (210) 522-3972.
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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 11 technical divisions. | ||||||||||
December 28, 2012 | ||||||||||
