One of the goals for my EV build is to have an efficient cooling system. I am limited on battery space (and therefore range) already, and I am using drivetrain components well outside of their rated capacity as far as cooling goes (the GS450h motors and inverters were never designed for continuous use as traction motors).
I wanted a variable system that will let me:
- Cool the motors when required
- Heat the cabin when required
- Recycle the motor heat to heat the cabin.
For my third point, I would need a single cooling loop, with the motors sending their warm water to the heater core.
Here is the design of my cooling system. It contains two valves which can separate the coolant into two loops, or pass it through as a single loop. I've included pictures of the two "states", series (one loop) and parallel (two loops).
Complete:
Series:
Parallel:
Note that for the "series" setup, the secondary pump and heater would not run.
For completeness, here are the components I currently have:
Main pump - Pierburg CWA200
Secondary Pump - Lexus GS450h auxilliary coolant pump
Valve - BMW X5 dual valve https://images-na.ssl-images-amazon.com ... L1500_.jpg
Heater - Chevrolet Volt / Ampera heater
Note that the coolant valves are not the A/B type, they are two separate valves. This is the flaw in my system. To change states, I must switch 4 solenoid valves, and in either state, I must have two solenoids energised at all times. (in my diagrams, I have named the solenoids A, B, C, and D). this is inefficient! The pipework is a nightmare and I'm not sure if I can plumb this in the space I have.
What I'd prefer is a true "series/parallel" coolant valve. These used to be common in US cars in the 60's and 70's:
This would be an ideal solution!
The question is, where can I find these valves? Has anyone come across an electronic controlled variant that isn't $200 in the USA and won't ship to the UK? Are they used in any EV's? My early searching says no, but often the "cooling system" diagrams of EVs aren't all that specific.
Most of the ones that I can find these days are cable or vacuum operated. I'd prefer not to use these as it means fabricating an actuator for them.
For reference, I am using 19mm ID hose for most of my cooling system, but the "Lexus" parts (inverter, motor, secondary pump) are 16mm ID.
Also, since people always seem to ask about my flowchart software, it's online at http://draw.io. Great for quick basic plans!