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In a cooling system for a motor vehicle engine having indirect charge air cooling, including a general cooling circuit for cooling a power-generating unit which comprises a coolant pump and a main coolant cooler, and an additional cooling circuit which branches off at an output point from the genera

In a cooling system for a motor vehicle engine having indirect charge air cooling, including a general cooling circuit for cooling a power-generating unit which comprises a coolant pump and a main coolant cooler, and an additional cooling circuit which branches off at an output point from the general cooling circuit and returns to the latter at an in-coupling point between the main coolant cooler and the coolant pump and contains an additional coolant cooler, means are provided for sensing the coolant temperature in an area where the coolant of the general cooling circuit and of the additional cooling circuit are mixed and also means for controlling the coolant flow as a function of the sensed coolant temperature.

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1. A cooling system, for a motor vehicle engine having indirect charge air cooling, comprising:a general cooling circuit (1) including a coolant for cooling a power- generating unit (2) which includes a coolant circulating pump (5) and a main coolant cooler (7), an additional cooling circuit (3) for

1. A cooling system, for a motor vehicle engine having indirect charge air cooling, comprising:a general cooling circuit (1) including a coolant for cooling a power- generating unit (2) which includes a coolant circulating pump (5) and a main coolant cooler (7), an additional cooling circuit (3) for cooling additional coolant, which branches off at an output point (6) downstream of the coolant circulating pump (5) but ahead of the engine (2) from the general cooling circuit and returns to the latter at an in-coupling point (19) between the main coolant cooler and the coolant circulating pump (5), and which includes an additional coolant cooler (14) and, upstream of the additional coolant cooler (14), a flow restrictor (12), said additional coolant cooler being arranged in the air stream in front of the main coolant cooler, and a charge air cooler (17) for cooling the charge air supplied to the engine (2), means (10, 21) for sensing the coolant temperature and means (10, 10a) for controlling the coolant flow through the main coolant cooler (7) as a function of the sensed coolant temperature, said means (10, 21) for sensing the coolant temperature being arranged in a region where the coolant of the general cooling circuit and the additional cooling circuit are mixed. 2. A cooling system according to claim 1, wherein the means for sensing the coolant temperature and the means for controlling the coolant flow are integral parts of a thermostat element (10) which is arranged at the in-coupling point (19).3. A cooling system according to claim 1, wherein the means for controlling the coolant flow include an activatable flow-rate control element (10a) which is activated by an associated control unit (20) as a function of the sensed coolant temperature, and the means for sensing the coolant temperature comprise a temperature sensor (21) arranged separately from the flow-rate control element.4. A cooling system according to claim 3, wherein a flow-rate control element (10a) is arranged at the in-coupling point (19).5. A cooling system according to claim 3, wherein the flow-rate control element (10a) is arranged upstream of the main coolant cooler (7), in the direction of flow of the coolant, at a branching point of a bypass line (8) bypassing the main coolant cooler.6. A cooling system according to claim 1, wherein the output point (6) is situated in the region between the coolant circulating pump (5) and the power-generating unit (2).7. A cooling system according to claim 1, wherein the flow restrictor is an adjustable restriction element (12) which is arranged in the additional cooling circuit (3) between the output point (6) and the additional coolant cooler (14).8. A cooling system according to claim 1, wherein the power-generating unit is a motor vehicle engine and the additional cooling circuit includes a cooler for cooling the charge air for the motor vehicle engine, which charge air is supplied by an associated exhaust-gas turbocharger (4).9. A cooling system, for a motor vehicle engine having indirect charge air cooling, comprisinga general cooling circuit (1) including a coolant for cooling the motor vehicle engine (2), which contains a coolant circulating pump (5) and a main coolant cooler (7), an additional cooling circuit (3) for cooling the charge air, which additional cooling circuit (3) branches off at an output point (6) downstream of the coolant circulating pump (5) but ahead of the engine (2) from the general cooling circuit and returns to the latter at an in-coupling point (19) between the main coolant cooler and the coolant pump (5), and which includes an additional coolant cooler (14) and, upstream of the additional coolant cooler (14), a flow restrictor (12), said additional coolant cooler being arranged in the air stream in front of the main coolant cooler, and a charge air cooler (17) for cooling the charge air supplied to the engine (2), and means (10) for controlling the coolant flow through the main coolant cooler (14) as a function of the coolant temperature, said coolant pump (5) being adjustable as to at least one of its pumping volume flow, its coolant circulating rate and its coolant pressure. 10. A cooling system according to claim 9, wherein a thermostat element (10) is arranged at the in-coupling point (19) and said thermostat element (10) includes means for sensing the coolant temperature and means for controlling the coolant flow as integral parts thereof.11. A cooling system according to claim 9, wherein an adjustable coolant pump (5) is used for controlling the coolant flow and for compensating for a change in the volume flow caused by an actuation of the thermostat element (10).12. A cooling system according to claim 9, wherein the coolant pump (5) is adjustable as a function of at least one of engine speed and engine torque.13. A cooling system according to claim 9, wherein the coolant pump (5) is adjustable as a function of the optimum volume flow for the charge air cooling.14. A cooling system according to claim 9, wherein the general cooling circuit is in communication with a coolant expansion tank via at least one bleed line.