Tweet
I am a mechanical engineering undergraduate student in the process of exploring various methods and test rigs that could be used to measure the drive train efficiency of two recumbent bicycles. Hopefully this discussion isn't too far outside of the scope of biomechanics. Allow me to provide some background on my situation:
For my senior project, I am working with two other students in conjunction with our school's Human Powered Vehicle (HPV) club to design a flexible mid-drive that will allow a chain-sprocket mechanism to move concurrently with the steering wheel of a recumbent bicycle.
The two most recent designs feature a chain-sprocket mechanism with a rigid mid-drive that encounter chain twist when the wheel is turned. This chain twist generates losses. By allowing the chain-sprocket mechanism to move concurrently with the steering wheel, we hope to eliminate these loses due to chain twist; the only losses encountered would ideally be due to the hysteresis of the flexible material. We anticipate that these losses will be lower. In turn, this should increase the drive train efficiency. Our final design will be integrated into this year's design.
In order to validate the success of our senior project, we need to measure the drive train efficiency of the two most recent models; this will be used as a benchmark. Without knowing the drive train efficiencies, our project will not have any substance. This leads me to the reason why I started this discussion: does anyone know of any ways to measure the power input to the drive train (on the pedals) and/or any ways to measure the power output of the drive wheel?
There is potential to use a dynamometer and a power-tap power meter to measure output power at our school but we'd like to keep exploring different options in case those aren't compatible or encounter set-up issues. As for input power, there are motors in our school's Electrical Engineering department that supply power near what a human can do (1/3 hp). However, not only is this option precarious, motors have high RPM and low torque whereas humans have high torque and low relatively low RPM. Ideally, we would like to measure drive train efficiency using a human as the input power source. After all, a human will be operating the vehicle.
Keeping in mind that we have a really low budget, what are some methods or devices we could use to measure the input power and output power of the drive train in order to calculate efficiency? I'm willing to hear any ideas that anyone has to share so that my team can continue to make progress on this portion of the project.
Here is an image of the two previous models without their housings:
file:///Users/Moody/Downloads/20160416_212902.jpg
file:///Users/Moody/Downloads/20160416_211016.jpg
Chain twist encountered on previous models:
file:///Users/Moody/Downloads/20160416_211940.mp4
Summary:
• Senior project for this year’s HPV model
• Decrease losses due to chain twist with flexible mid-drive
• Increase drive chain efficiency as a result
• Measure drive train efficiency of two most recent designs to validate future design
This is a really lengthy read but I appreciate everyone who gives it thought.
Thanks!
For my senior project, I am working with two other students in conjunction with our school's Human Powered Vehicle (HPV) club to design a flexible mid-drive that will allow a chain-sprocket mechanism to move concurrently with the steering wheel of a recumbent bicycle.
The two most recent designs feature a chain-sprocket mechanism with a rigid mid-drive that encounter chain twist when the wheel is turned. This chain twist generates losses. By allowing the chain-sprocket mechanism to move concurrently with the steering wheel, we hope to eliminate these loses due to chain twist; the only losses encountered would ideally be due to the hysteresis of the flexible material. We anticipate that these losses will be lower. In turn, this should increase the drive train efficiency. Our final design will be integrated into this year's design.
In order to validate the success of our senior project, we need to measure the drive train efficiency of the two most recent models; this will be used as a benchmark. Without knowing the drive train efficiencies, our project will not have any substance. This leads me to the reason why I started this discussion: does anyone know of any ways to measure the power input to the drive train (on the pedals) and/or any ways to measure the power output of the drive wheel?
There is potential to use a dynamometer and a power-tap power meter to measure output power at our school but we'd like to keep exploring different options in case those aren't compatible or encounter set-up issues. As for input power, there are motors in our school's Electrical Engineering department that supply power near what a human can do (1/3 hp). However, not only is this option precarious, motors have high RPM and low torque whereas humans have high torque and low relatively low RPM. Ideally, we would like to measure drive train efficiency using a human as the input power source. After all, a human will be operating the vehicle.
Keeping in mind that we have a really low budget, what are some methods or devices we could use to measure the input power and output power of the drive train in order to calculate efficiency? I'm willing to hear any ideas that anyone has to share so that my team can continue to make progress on this portion of the project.
Here is an image of the two previous models without their housings:
file:///Users/Moody/Downloads/20160416_212902.jpg
file:///Users/Moody/Downloads/20160416_211016.jpg
Chain twist encountered on previous models:
file:///Users/Moody/Downloads/20160416_211940.mp4
Summary:
• Senior project for this year’s HPV model
• Decrease losses due to chain twist with flexible mid-drive
• Increase drive chain efficiency as a result
• Measure drive train efficiency of two most recent designs to validate future design
This is a really lengthy read but I appreciate everyone who gives it thought.
Thanks!