Pressure Relief Valves in eAxles and EDUs

using Pressure Relief Valves withIn Electric vehicles

A pressure relief valve can be used as a diverter valve to direct coolant flow to components with higher cooling needs (only when necessary). Under normal driving conditions, critical components such as End Windings/Stator Stack/Bearings may not require 100% coolant flow. Under certain high-load conditions (think towing a boat or fast acceleration), the output flow of the pump is increased to crack open a Relief Valve to provide additional coolant flow. This allows the pump to run at greater efficiencies when the downstream components don’t require the additional coolant flow.

The coolant system is split between the primary cooling loop and the secondary coolant loop, with the relief valve gating the secondary loop.

Increased coolant pump efficiencies, increase electrical vehicle range. By making the pump more efficient, you can reduce the total volume of coolant required – saving weight and space within the system.

Common electric vehicle design engineer questions

• Do you plan to have a single cooling loop, or do you expect to divert coolant through an isolated circuit at times?
• What methods are you using to increase the efficiency of the coolant pump?
• How to target coolant flow to end windings/gear box/stator stack/etc.?
• How to provide coolant/lubrication only when needed?
• How to generate more coolant flow under demanding conditions? Do all other components get flooded with extra coolant?

Lee Advantage

• Our pressure relief valves are able to hold a tight cracking pressure tolerance. It’s important that the valve remains closed during normal pump operation, but cracks open quickly when the pump increases output flow.
• Single piece installation versus operator installing discrete components (ball/poppet, spring, and retainer).
• 100% tested component gives customer confidence that the pressure relief valve will function as intended while reducing scrapped housings/re-work.