Refrigerant Valves in AC- and Heat Pump Systems for Electric Vehicles

Eike Willers; Stephan Wild

doi:10.4271/2020-28-0038

The Thermal Management of Electric Vehicles differs strongly from the Thermal Management in IC engine driven vehicles. The Air Conditioning Circuit itself has comparable requirements, however, the electric components and their properties lead to new architectures. Essential is at least a chiller for the conditioning of the battery, which needs to be cooled down to the range of summer ambient temperatures. The respective control devices need to fulfill different basic requirements

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Small package
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Lightweight
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Low noise
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Low energy consumption,

to play an important role in the Refrigeration architecture of Electric and Hybrid Vehicles.

For conventional systems, optimization of package and weight will be achieved by a 75g TXV with a 28 mm thermal head.

As soon as a battery also has to be cooled, Shut-Off valves will be implemented in the system in order to manage the respective heat loads according to the needs.

For some system configurations, it is important to have a precise electronic control, which is not following the usually fixed superheat characteristic of a conventional TXV. This is achieved by an extremely lightweight, absolutely noiseless Electronic Valve with 60 g cartridge weight for Cooling power output from 0,5 to 4 ton, i.e. from 1,5 to 14kW max.

If the systems get additional functionality such as heat pump operation, it is very advantageous to replace a pair of heavy solenoid valves with a remarkable power consumption of about 15 W per piece by a 2 channel electric switching valve. This valve provides an excellent tightness, very low pressure drop and only 30% of the weight of the solenoid valves. Furthermore the piping and assembly is much more simple and leads to lower refrigerant loss due to a significant reduction of interfaces.

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Refrigerant Valves in AC- and Heat Pump Systems for Electric Vehicles 2020-28-0038

SAE MOBILUS