Vehicle cooling system

Abstract

The disclosure relates to a cooling system and a method for operating the cooling system for cooling a battery of a vehicle using a coolant circuit. The cooling circuit includes a pump device, a heat exchanger for transferring heat between a coolant and the battery, a heat exchanger for transferring heat between the coolant and the surroundings, and a heat exchanger for transferring heat between the coolant and a refrigerant circulating in a refrigerant circuit. The refrigerant circuit is designed with a heat exchanger and an associated expansion element. The refrigerant circuit includes two additional expansion elements. The first expansion element is arranged upstream of the heat exchanger and the second expansion element is arranged downstream of the heat exchanger, with regard to the direction of the refrigerant flow. The heat exchangers designed as evaporators on the refrigerant side can be operated with different pressure and temperature levels.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of priority of German Patent Application Serial No. DE 10 2010 042 122.7-45 filed on Oct. 7, 2010, hereby incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The invention relates to a cooling system for cooling the battery of a vehicle, and, more particularly, to a cooling system for cooling the battery of an electric vehicle or hybrid vehicle using a coolant circuit. The invention further relates to a method for operating the cooling system.BACKGROUND OF THE INVENTION[0003]High-capacity batteries used in electric or hybrid vehicles are used to store electrical energy. The energy is supplied to the battery by connecting the battery to a power supply source. With hybrid vehicles, energy can also be recovered during the braking processes of the vehicle.[0004]During operation, both the battery cells of the battery as well as other components of the electrical drive train, such as t...

AI Technical Summary

Benefits of technology

[0029]Consonant with the present invention, a cooling system for cooling the battery of a vehicle that enables the battery to operate at optimal temperature, maximum efficiency and minimum battery power loss, minimum electrical power consumption, maximum efficiency of the overall system, and maximum operating range of the vehicle, has surprisingly been discovered.

[0048]The solution taught by the disclosure for continuously controlling the temperature of the battery enables operation of the battery at optimal temperature, maximum efficiency and minimum battery power loss, minimum electrical power consumption for conditioning the battery, maximum efficiency of the overall system and the drive system, and maximum operating range of the vehicle.

Problems solved by technology

Any heat generated and liberated in the process must be dissipated, because an elevated operating temperature can result in very high thermal loading on the battery cells.

Due to the limited temperature resistance of batteries, they must be actively cooled.

At temperatures above 40° C., however, increased aging of the battery cells occurs, which can result in damage to the cells if the temperature is higher than 50° C.

In the case of lithium-ion batteries which exhibit limited performance above approximately 40° C., cooling using ambient air is not feasible in all environmental conditions.

The outside air temperature can reach or exceed values of 40° C. on a hot summer day, so that cooling using untreated ambient or outside air is not feasible.

However, the battery may not provide the necessary maximum output.

While the use of cooling air from the vehicle interior permits a narrower temperature range than the use of ambient air, the withdrawal of air from the vehicle interior produces increased noise in the vehicle and therefore reduces the comfort for a user.

Moreover, using air cooling for batteries, which at temperature differences in the range of 0 to 5 K is rather demanding with regard to temperature distribution homogeneity, the temperature spread between the individual battery cells may become too great.

Since the thermostatic expansion valve control is mechanical, the appropriate refrigerating capacity for cooling the battery cannot be provided, which reduces the efficiency of the battery cooling process.

The battery is cooled more than necessary and is therefore operated less efficiently.

The pressure and temperature level in the chiller cannot be controlled independent of the evaporator of the vehicle air-conditioning system.

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