CHAIN or BELT DRIVEN DIFFERENTIAL
CHAIN or BELT DRIVEN DIFFERENTIAL
I am looking for info on drive solutions maybe via a toothed belt preferably but chain is ok, to a diff driving the rear wheels of a car. Ive even considered using a 2VC transaxle due to its small size and weight. I just want to avoid using the original gearbox or going front wheel drive due to the excessive losses. Any experiences.
A chain drive on an EV can sound VERY loud. The Human ear has adjustable gain and you start to hear all sorts of stuff as other noise goes away.
The arguments between fixed and multi-ratio transmissions are very application dependent. I would tend to keep the transmission in most cases. Both sides of the argument were presented an a BVS annual Lunch a few years ago. The fixed ratio Fiesta couldn't drive up onto it's trailer un-assisted at the end of the day!
My Scirocco could have been locked in 3rd gear and still given good acceleration to it's 70+mph top speed (rev limited in 3rd), but it had a big 9" diameter GE motor and a 192v battery pack to give high torque well up the rev range. Both the motor and the controller ran much hotter driving in 3rd, rather than 2nd gear around town. I'd even use 1st in crawling traffic and a mechanical reverse was much cheaper than contactors.
A lower speed range, or lighter vehicle, or motor with a very wide speed/torque range shift the bias in favor of fixed ratio. You need to look at SYSTEM efficiency and not focus too much on losses in any one area.
The arguments between fixed and multi-ratio transmissions are very application dependent. I would tend to keep the transmission in most cases. Both sides of the argument were presented an a BVS annual Lunch a few years ago. The fixed ratio Fiesta couldn't drive up onto it's trailer un-assisted at the end of the day!
My Scirocco could have been locked in 3rd gear and still given good acceleration to it's 70+mph top speed (rev limited in 3rd), but it had a big 9" diameter GE motor and a 192v battery pack to give high torque well up the rev range. Both the motor and the controller ran much hotter driving in 3rd, rather than 2nd gear around town. I'd even use 1st in crawling traffic and a mechanical reverse was much cheaper than contactors.
A lower speed range, or lighter vehicle, or motor with a very wide speed/torque range shift the bias in favor of fixed ratio. You need to look at SYSTEM efficiency and not focus too much on losses in any one area.
Paul
http://www.compton.vispa.com/scirocco/
http://www.morini-mania.co.uk
http://www.compton.vispa.com/the_named
http://www.compton.vispa.com/scirocco/
http://www.morini-mania.co.uk
http://www.compton.vispa.com/the_named
- geekygrilli
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I think its important to draw on people's real-life experience on things like this.
Having a variable gear ratio is a real bonus. Like Paul's car, my cinquecento is perfectly capable of driving everywhere in 3rd, but its inefficient. For trafficy town driving 2nd gear is better, and getting up people's steep drive-ways andon/off trailers 1st is used. I also use 4th on the North Circular.
All that said, my motor has a limited rev range up to 3500 rpm.
My opinion, for what its worth would be to go with the transaxle so you can change gear if necessary. Then, if one gear will do, get a diff, and I would go for belt drive as the quietness of an EV means you hear every little squeak, rattle and clonk in you car and it makes you paranoid!
Regards
Christopher
Having a variable gear ratio is a real bonus. Like Paul's car, my cinquecento is perfectly capable of driving everywhere in 3rd, but its inefficient. For trafficy town driving 2nd gear is better, and getting up people's steep drive-ways andon/off trailers 1st is used. I also use 4th on the North Circular.
All that said, my motor has a limited rev range up to 3500 rpm.
My opinion, for what its worth would be to go with the transaxle so you can change gear if necessary. Then, if one gear will do, get a diff, and I would go for belt drive as the quietness of an EV means you hear every little squeak, rattle and clonk in you car and it makes you paranoid!
Regards
Christopher
Hi Mark
I've been thinking along the same lines myself for a while. Here are a couple of links to off-the-shelf solutions:
http://www.westgarage.co.uk/services/ch ... rives.html
http://www.quaife.co.uk/Chain-drive-car ... fferential
The Z Cars site and Mini Forum are a good place to find information about chain drives.
It should be fairly easy to fit a belt sprocket to one of those diffs as well. A sprocket from a Harley or Kawasaki 250/440 LTD might work, although the tooth count is a bit low for the reduction you're likely to need. Medway also do a good range of belts and sprockets.
I recently picked up a couple of 7" Prestolite motors cheap that look as if they should be good for 30 kW each with some extra cooling. I'm trying to make up my mind whether to use both of them in a series/parallel switching arrangement with a belt drive as you suggest, or just to use one mated with a standard gearbox. This is in a mini with a projected final weight of 700 kg. Very tempted by the twin motor approach at the moment. I'd like good low-end acceleration and top speed of 75 mph. I'd be grateful for any advice as to which is likely to give the best performance Paul.
I've been thinking along the same lines myself for a while. Here are a couple of links to off-the-shelf solutions:
http://www.westgarage.co.uk/services/ch ... rives.html
http://www.quaife.co.uk/Chain-drive-car ... fferential
The Z Cars site and Mini Forum are a good place to find information about chain drives.
It should be fairly easy to fit a belt sprocket to one of those diffs as well. A sprocket from a Harley or Kawasaki 250/440 LTD might work, although the tooth count is a bit low for the reduction you're likely to need. Medway also do a good range of belts and sprockets.
I recently picked up a couple of 7" Prestolite motors cheap that look as if they should be good for 30 kW each with some extra cooling. I'm trying to make up my mind whether to use both of them in a series/parallel switching arrangement with a belt drive as you suggest, or just to use one mated with a standard gearbox. This is in a mini with a projected final weight of 700 kg. Very tempted by the twin motor approach at the moment. I'd like good low-end acceleration and top speed of 75 mph. I'd be grateful for any advice as to which is likely to give the best performance Paul.
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