Quote:
Originally Posted by e*clipse
It's a group dynamics thing I've noticed with a few other projects I've worked on. In a very open group, or one just starting (before politics and personalities get involved) there can be an amazing "energy" that brings out new ideas.   One thing that can really hurt is a "know it all" in the group. 
I really like the positive free ideas energy in this group of folks, and I'm trying to do my best to help out. I'm also not very good at this, so please have some patience with me.
Regarding outrunner motors, I'm familiar with them from an RC airplane and helicoptor perspective. One definite advantage they have is the magnets are attached to the inside of the (outside) rotor, so there's little danger of the magnets spinning off.
A thing that may be helpful with the motor/transmission decision is a general spreadsheet to calculate torque required, speed required, torque delivered to the wheel, etc. Inputs could be final drive ratio, tire diameter, gear ratio (s) , motor torque/ power curve.
For example, what final drive gear ratio does the Subaru diff use? What gear ratios are available in a C4 transmission? I'm just using these specific numbers because real numbers would be helpful. I do have all that info for my truck, but I've noticed that a tranny designed for a turbocharged gas engine isn't optimum for a turbocharged diesel engine. This really must be true for and electric motor.  |
Hey E*clips
Yeah I hear ya. I have followed many projects online and seen them degrade into the... "my tool is bigger than yours" mud slinging.
The way I do things is weld up an assembly and see if it goes boom. I have no real world reference for numbers so when it comes to math I am a bit lost, as a result I find physical parallels. When gathering info for an electric car project the usual answer to getting off the line faster is more amps/bigger motor/bigger controller...
I know people don't like to shift gears because of the danger of over revving the motor but as I have heard them all say "when they need a little extra for hills or jumping on the freeway they shift. So why not just add two automatic gear ranges to help when needed... Hence my thoughts of going with the C4 from the get go.
For some stock numbers start with C4 (OEM) 2.46 1st 1.46 2nd 1.00 direct and the final drive "differential" ratio would be chosen depending on the torque curve of the motor used. If the motor has gobs of torque such as a modified outrunner then a highr final drive like 3.5 would be in order. If the motor was like the MGR's then a lower final drive ratio would be used like 4.44. But there is also aftermarket gears that can range about anything you like.
Either way the end result would be as if you had no transmission when in direct drive. You would just have the added benefit of extra torque when needed without resorting to higher amps and all the pit falls that come with it.
Shifting would be a simple matter of telling the controller to pause for the clutches to switch and then resume.
Cyruscosmo