Arrangement and method for cooling of coolant in a cooling system in a vehicle

Abstract

An arrangement and a method for cooling coolant in a cooling system in a vehicle: The cooling system includes a first cooling circuit, a first coolant pump ( 11 ) to circulate coolant through the first cooling circuit, a first radiator ( 13 ) to cool the coolant, and a thermostat ( 12 ) which opens to direct coolant to the first radiator ( 13 ) when the coolant is above the thermostat's regulating temperature (t 2 ); and a second cooling circuit includes a second radiator ( 20 ) to cool coolant. A flow device ( 23, 29 ) selectively transfers a portion of coolant from the first cooling circuit to the second cooling circuit, so that this portion of the coolant is cooled in the second radiator ( 20 ) when the coolant in the first cooling circuit is within a temperature range defined by a lowest temperature (t 1 ) at which the coolant initially needs cooling and a highest temperature which is equal to the thermostat's regulating temperature (t 2 ).

1 . An arrangement for cooling of coolant in a cooling system in a vehicle, comprising:
 the cooling system comprising a first cooling circuit which comprises a first coolant pump configured and operable to circulate coolant through the first cooling circuit, a first radiator configured and operable to cool the coolant in the first cooling circuit, and a thermostat at the first cooling circuit configured to open and when open, to direct coolant to the first radiator when the coolant in the first cooling circuit is above a regulating temperature (t 2 ) of the thermostat;   a second cooling circuit which comprises a second radiator for cooling of coolant, a flow device which comprises a valve, when the valve is in a first position, the valve is configured and operable to direct coolant from the first cooling circuit to the second cooling circuit, and when the valve is in a second position, the valve is configured and operable to prevent coolant from passing from the first cooling circuit to the second cooling circuit; and   the flow device further comprises a temperature sensor which detects the coolant temperature at a location in the first cooling circuit, a control unit which receives information from the temperature sensor, wherein the control unit is configured to put the valve into the second position when the coolant in the first cooling circuit is at a temperature below the lowest temperature (t 1 ) at which the coolant initially needs cooling and is also below the thermostat's regulating temperature (t 2 ) and in the first position when the coolant in the first cooling circuit is within a temperature range defined by the lowest temperature (t 1 ) at which the coolant initially needs cooling and a highest temperature which is equal to the thermostat's regulating temperature (t 2 ).   
     
     
         2 . A cooling system according to  claim 1 , wherein the second cooling circuit comprises a second coolant pump configured and operable to circulate coolant through the second cooling circuit; and
 the control unit is configured and operable for controlling activation of the second coolant pump.   
     
     
         3 . A cooling system according to  claim 2 , further comprising said flow device is configured and operable to selectively either transfer or not transfer coolant from the first cooling circuit to the second cooling circuit in operating situations where the coolant in the first cooling circuit is at a temperature above the thermostat's regulating temperature (t 2 ). 
     
     
         4 . A cooling system according to  claim 3 , further comprising the second cooling circuit comprises a first connecting line configured and operable to lead at least a part of the coolant from the first cooling circuit to the second cooling circuit, and a second connecting line configured and operable to lead the coolant back to the first cooling circuit from the second cooling circuit after the coolant has again passed through the second radiator. 
     
     
         5 . A cooling system according to  claim 1 , wherein the first radiator and the second radiator are air-cooled. 
     
     
         6 . A cooling system according to  claim 5 , wherein the first radiator and the second radiator are situated in regions of the vehicle such that in substantially all of the operating conditions of the radiators, the second radiator is cooled by air which is at a lower temperature than the first radiator. 
     
     
         7 . A method for cooling of coolant in a cooling system in a vehicle, wherein the cooling system comprises:
 a first cooling circuit which comprises:   a first coolant pump configured and operable to circulate coolant through the first cooling circuit, a first radiator configured and operable to cool the coolant in the first cooling circuit, and a thermostat at the first cooling circuit configured to open and when open, to direct coolant to the first radiator when the coolant in the first cooling circuit is above a regulating temperature (t 2 ) of the thermostat;   a second cooling circuit which comprises a second radiator for cooling of coolant and a flow device which comprises a valve, when the valve is in a first position, the valve is configured and operable to direct coolant from the first cooling circuit to the second cooling circuit, and when the valve is in a second position,   the valve is configured and operable to prevent coolant from passing from the first cooling circuit to the second cooling circuit; and   the method comprising:   detecting the coolant temperature at a location in the first cooling circuit, receiving detected temperature information putting the valve into the second position when the coolant in the first cooling circuit is at a temperature below the lowest temperature (t 1 ) at which the coolant initially needs cooling and which is below the thermostat's regulating temperature (t 2 ) and putting the valve into the first position when the coolant in the first cooling circuit is within a temperature range defined by a lowest temperature (t 1 ) at which the coolant initially needs cooling and a highest temperature which is equal to the thermostat's regulating temperature (t 2 ).