Torque Sensor for Engines

Product: Torque Sensor for Engines
Development Stage: Prototyping of Functional Metal Parts
Primary Inventor: Muralidhar Ghantasala Ph.D., John Bair Ph.D., Vivek Sri Charan Iddum Ph.D., Department of Mechanical and Aerospace Engineering       
Scientific Publication: None  
License Status: License Available       
Patent Status: International Patent Application PCT/IB2018/057617, US Application 16/807,553 
Reference:  2017-014

Optimization of vehicle drivetrain performance has been an important endeavor for decades. So too has the quest for increased automotive engine fuel efficiency. Engine torque monitoring aids in both of these efforts, as torque data can be utilized to improve the delivery of engine power to the transmission system, thereby increasing performance as well as fuel efficiency.

For example, torque monitoring has become an essential tool for optimizing vehicle performance in trucking fleets. Such fleets comprise a major portion of the bulk goods distribution infrastructure worldwide, with approximately 70% of all freight in the United States delivered by truck. Currently, some trucks are equipped with “direct” torque measurement technology, which typically has an accuracy of 1%. However, due to both the size and cost of the direct measurement apparatus, it is not suitable for a substantial portion of each fleet.

As such, many trucks are equipped with “indirect” torque monitoring technology which typically ranges from 10%-30% accuracy, depending on driving conditions as well as the particular apparatus. While this makes for a decent trade-off relative to direct measurement given the reductions in bulk and cost, there remains substantial room for improvement in accuracy. For example, an indirect torque measurement technology with 5% or better accuracy would provide a significant improvement over existing products so long as the other inherent advantages (size, cost, etc.) can be maintained.

Other types of vehicles could also stand to benefit from similar advances in torque monitoring technology, such as medium and heavy duty, transit, off-highway, and military vehicles. Moreover, regardless of the engine fuel type (e.g., diesel, gasoline, ethanol, fuel cell, hybrid, etc.) drivetrain performance and fuel consumption would still benefit from optimization.

technology description

At WMU, a virtual torque sensor (VTS) has been developed which provides real time engine torque data. The real time data can be used for optimal gear shifting which leads to improved engine performance and better fuel efficiency. 

Uniquely, the WMU technology does not require any direct torque sensing hardware. Rather, the WMU sensor indirectly measures engine torque by running standard engine monitoring data through a complex computer algorithm. To do so, the WMU VTS utilizes a microcontroller that connects with the existing Controller Area Network (CAN) of the vehicle, as shown in Figure 1. For example, Class 8 heavy industrial vehicles generally implement the SAE J-1939 CAN bus standard protocols and algorithms for various engine-transmission monitoring and control activities. When connected with such a CAN, the WMU sensor is able to determine the engine torque based on instantaneous flywheel speed data that is already available for other purposes.

Specifically, the WMU technology implements a proprietary algorithm to analyze various harmonics of the instantaneous flywheel speed and determine angular acceleration, which is then converted to a proportional torque value (Fig. 2). To generate the flywheel speed data, flywheel speed sensors typically sense the passing teeth of the flywheel as it rotates. The passing teeth induce voltage pulses in the flywheel speed sensor, which are then converted to digital signals that are counted by a counter-timer. This time domain information, corresponding to the time between each passing flywheel tooth, becomes the algorithm’s input data, which is used to calculate angular acceleration. The known relationship between angular acceleration and torque for a given flywheel (Fig. 3) is then used to complete the calculation of the indirectly measured torque value.

By producing accurate torque data in this way, WMU’s VTS technology enables the optimization of gear shifting control which can improve fuel efficiency and help to reduce wear and tear. The sensor’s data can also be used to reduce calibration times for engine-transmission testing and engine prognostics, both of which can reduce the likelihood of unplanned down time (an important factor in fleet economics).

potential benefits

• Provides real time engine torque data, with higher accuracy and for lower costs than competing technologies.
• Utilizes existing flywheel speed data, eliminating the need for installing direct torque sensors. 
• Improves fuel economy by enabling gear shifting optimization.
• Reduces calibration times for engine-transmission testing.
• Assists engine progonostics, reducing the likelihood of unplanned down time.