COOLING SYSTEM FOR A MOTOR VEHICLE

Abstract

s A cooling system of a motor vehicle includes a first cooling circuit and a second cooling circuit. A refrigerant circuit supplies a vaporizer associated with the first cooling circuit that has a first target power value (S1) determining a cooling potential. The refrigerant circuit also supplies a refrigerant-coolant heat exchanger associated with the second cooling circuit that has a second target power value (S2) determining a cooling potential. A conveyor unit controls a mass flow of a refrigerant flowing through the refrigerant circuit and can be controlled by the first target power value (S1). The cooling system includes a control unit by way of which the first target power value (S1) can be controlled to achieve the second target power value (S2).

Claims

1. A cooling system of a motor vehicle, said cooling system comprising: a first cooling circuit, a second cooling circuit, a refrigerant circuit that is configured to supply (i) a vaporizer associated with the first cooling circuit, the vaporizer having a first target power value (S1) that is indicative of a cooling potential, and (ii) a refrigerant-coolant heat exchanger associated with the second cooling circuit, the refrigerant-coolant heat exchanger having a second target power value (S2) that is also indicative of a cooling potential, a conveyor unit that is (i) configured to control a mass flow of a refrigerant flowing through the refrigerant circuit and (ii) configured to be controlled by the first target power value (S1), and a control unit that is configured to control the first target power value (S1) so as to achieve the second target power value (S2).

2. The cooling system according to claim 1, wherein the first target power value (S1) is set by a power deficit (LD) of the refrigerant-coolant heat exchanger, wherein the power deficit (LD) is a difference between the second target power value (S2) and an actual power value (LI) of the refrigerant-coolant heat exchanger.

3. The cooling system according to claim 2, wherein the control unit is configured to increase the actual power value (LI).

4. The cooling system according to claim 1, wherein the control unit comprises a PI controller.

5. The cooling system according to claim 1, further comprising a valve element arranged in the refrigerant circuit.

6. A motor vehicle comprising the cooling system of claim 1.

7. A method for a cooling system of a motor vehicle, wherein the cooling system includes (a) a first cooling circuit, (b) a second cooling circuit, (c) a refrigerant circuit that is configured to supply (i) a vaporizer associated with the first cooling circuit, the vaporizer having a first target power value (S1) that is indicative of a cooling potential, and (ii) a refrigerant-coolant heat exchanger associated with the second cooling circuit, the refrigerant-coolant heat exchanger having a second target power value (S2) that is also indicative of a cooling potential, and (d) a conveyor unit that is (i) configured to control a mass flow of a refrigerant flowing through the refrigerant circuit and (ii) configured to be controlled by the first target power value (S1), the method comprising: determining the first target power value (S1), the second target power value (S2) and an actual power value (LI) of the second cooling circuit, determining a power deficit (LD) as a difference between the actual power value (LI) and the second target power value (S2), using the power deficit (LD) to control the first target power value (S1), and controlling the first target power value (S1) until the second target power value (S2) is achieved.

8. The method according to claim 7, further comprising controlling the first target power value (S1) by increasing a cooling potential of the vaporizer.

9. The method according to claim 7, wherein a control unit associated with the cooling system and comprising a control element is used for controlling, wherein the control element is configured to control the first target power value (S1) as a function of the power deficit (LD).

10. The method according to claim 9, wherein the control element is a PI controller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Additional advantages, features and details of the invention arise from the following description of preferred exemplary embodiments and with reference to the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and/or shown only in the figure can be used not only in the respectively indicated combination but also in other combinations or on their own without departing from the scope of the invention. Shown are:

[0022] FIG. 1 is a schematic diagram of a cooling system according to aspects of the invention of a motor vehicle, comprising a first cooling circuit and a second cooling circuit,

[0023] FIG. 2 is a time-temperature diagram of a target temperature value of the first cooling circuit of the cooling system according to FIG. 1, and

[0024] FIG. 3 is a time-power diagram of target and actual powers of the first cooling circuit and the second cooling circuit.

DETAILED DESCRIPTION OF THE INVENTION

[0025] A cooling system 1 according to aspects of the invention of a motor vehicle 2, whose drive s assembly not shown in more detail is embodied in the form of an internal combustion engine and an electric motor, thus a drive assembly commonly referred to as a hybrid drive, or in the form of an electric motor or in the form of an assembly generating at least electrical power, is designed according to FIG. 1.

[0026] The cooling system 1 according to aspects of the invention comprises a first cooling circuit 3, which is provided for the climate control of an interior 4 of the motor vehicle 2, and a second cooling circuit 5, which is designed for cooling the drive assembly 16 and/or its components 16, which heat during operation, as well as a refrigerant circuit 6, which is designed for supplying refrigerant to both cooling circuits 4, 5.

[0027] The first cooling circuit 3 comprising a first circuit line 7 of the cooling system 1 is thermally coupled to the refrigerant circuit 6 by means of a vaporizer 8 which is accommodated in the first circuit line 7 such that fluid can flow through it. Via a first conveyor assembly 9 of the cooling system 1, which is designed in the form of a blower and which is also accommodated in the first circuit 7 such that fluid can flow through it, fresh air is supplied to the first cooling circuit 3 preferably from an environment 11, wherein the vaporizer 8, which comprises an expansion valve 10 designed for controlling, is arranged in the first cooling circuit 3 between the first conveyor assembly 9 and the interior 4.

[0028] A refrigerant-coolant heat exchanger 12, a so-called chiller, serves to thermally couple the second cooling circuit 5 to the refrigerant circuit 6. The refrigerant-coolant heat exchanger 12, which comprises a further expansion valve 13 for controlling, is accommodated in a second circuit line 14 of the cooling system 1 such that fluid can flow through it, said second circuit line being associated with the second cooling circuit 5. In order to convey coolant in the second cooling circuit 5, said circuit comprises a second conveyor assembly 15 of the cooling circuit 1 in the form of a pump, which is arranged upstream of the cooling components 16 and downstream of the refrigerant-coolant heat exchanger 12 in the direction of a flow through the second cooling circuit 5 indicated by means of the arrow. At this point, it should be mentioned that a flow through the first cooling circuit 3 is likewise indicated by means of an arrow, wherein this flow takes place from the environment 11 in the direction of the interior 4.

[0029] The refrigerant circuit 6 comprises a refrigerant circuit line 17 of the cooling system 1 via which the refrigerant can be supplied to the vaporizer 8 and the refrigerant-coolant heat exchanger 12. The refrigerant circuit 6 is divided into a first refrigerant sub-circuit 18 and a second refrigerant sub-circuit 19, wherein the first refrigerant sub-circuit 18 is associated with the first cooling circuit 3 and the second refrigerant sub-circuit 19 is associated with the second cooling circuit 5. In other words, the first refrigerant sub-circuit 18 is designed to supply refrigerant to the vaporizer 8 and the second refrigerant sub-circuit 19 is designed to supply refrigerant to the refrigerant-coolant heat exchanger 12. Or, in yet other words, the first refrigerant sub-circuit 18 is designed to supply an air-flow cooling and the second refrigerant sub-circuit 19 is designed to supply a water-flow cooling.

[0030] The refrigerant circuit 6 furthermore comprises a conveyor unit 20 in the form of a compressor, which is accommodated in the refrigerant circuit line 17 such that fluid can flow through it, as well as a condenser 21. Furthermore, a valve element 22 in the form of a shut-off valve is arranged in the refrigerant circuit line 17, by means of which valve element a flow through the refrigerant circuit 6 can be controlled. The conveyor unit 20 serves to control a mass flow of the refrigerant and is thus designed as a control unit of the cooling system 1, which control unit, in accordance with the prior art, controls a power of the vaporizer 8, wherein a power of the refrigerant-coolant heat exchanger 12 results, i.e., is not directly controlled.

[0031] The cooling system 1 according to aspects of the invention comprises a control unit 23, which serves to set the operation of the conveyor unit 20. The control unit 23 has a control element in the form of a PI controller. Likewise, the control unit 23 could also be designed with another control element that is suitable for the control explained in more detail below.

[0032] By means of the control unit 23, a first target power value S1 of the first cooling circuit 3 can be controlled in order to achieve a second target power value S2 of the second cooling circuit 5. In other words, the control unit 23 controls the first target power value S1 to the effect that, starting from an actual power value LI of the second cooling circuit 5, which is below the desired second target power value S2, i.e., is insufficient for cooling the cooling components 16, the second target power value S2 is set or, in other words, the second target power value S2 is set at the end of the controlling.

[0033] At this point, it should be mentioned that the target power values S1, S2 and the actual power value LI are to be understood as the power values of the refrigeration machines arranged in the cooling circuits 3, 5, of the vaporizer 8 and of the refrigerant-coolant heat exchanger 12, which power values cause an associated cooling power potential of the cooling circuits 3, 5, which is why the target power values S1, S2 and the actual power value LI are associated with the cooling circuits 3, 5.

[0034] The first target power value S1 can be set by means of a power deficit LD of the refrigerant-coolant heat exchanger 12, wherein the power deficit LD is a difference between the second target power value S2 and an actual power value LI of the refrigerant-coolant heat exchanger 12. In other words, a current cooling potential of the refrigerant-coolant heat exchanger 12, which is associated with the actual power value LI, is not sufficient and a need for a higher cooling potential of the second cooling circuit 5 exists. The desired cooling potential of the second cooling circuit 5 can be reached with a second target power value S2 that is to be set, in other words, that is to be adjusted by means of the control unit 23. For this purpose, by means of the determined power deficit LD, a total cooling potential of the refrigerant circuit 6 is changed by changing the cooling potential of the first cooling circuit 3. The actual power value LI can be increased by means of the control unit 23.

[0035] A method according to aspects of the invention for operating the cooling system 1 is explained below with reference to FIGS. 2 and 3. In FIG. 2, a target temperature T.sub.S to be adjusted in the first cooling circuit 3 is marked in a temperature T-time t diagram by means of a dash-dotted line and is used to bring about the first target power value S1 and the second target line value S2. Furthermore, a curve of an initial target temperature Tsu is marked by means of a solid line and corresponds to a target temperature of the vaporizer 8 of the first cooling circuit 3 before a correction by means of the power deficit LD. The target temperature T.sub.S has a lower value than the initial target temperature T.sub.Su, as a result of which the total cooling potential of the refrigerant circuit 6 can be increased, e.g., is increased by increasing a rotational speed of the conveyor unit 20.

[0036] In FIG. 3, the target power values S1, S2 and the actual power value LI are marked as well as an initial target power value S1u of the first cooling circuit 3. It can be seen that due to the control of the first target power value S1 as a function of the power deficit LD, the second target power value S2 can be reached and the first target power value S1 can be increased.

[0037] The method according to aspects of the invention is wherein in a first step, the first target power value S1, the second target power value S2 and the actual power value LI of the second cooling circuit 5 are determined, and in a second step, the power deficit LD is determined as the difference between the actual power value LI and the second target power value S2. In a third step, the first target power value S1 is controlled until the second target power value S2 is achieved, wherein the power deficit LD is used to control the first target power value S1. In other words, a rotational speed of the conveyor unit 20 is, for example, increased in the refrigerant circuit 6 for indirectly or directly supplying refrigerant to the two cooling circuits 3, 5 until the second target power value S2 is reached. Increasing the rotational speed of the conveyor unit 20 results in a reduction of a temperature of the refrigerant flowing in the refrigerant circuit 6, whereby the cooling potential of the vaporizer 8 is increased.

[0038] The cooling circuit 1 according to aspects of the invention comprises the valve element 22, which is generally fully open during the operation of the cooling circuit 1. If the cooling circuit 1 according to aspects of the invention is operated outside the method according to the invention, the cooling potentials of the cooling circuits 3, 5 can be set by means of this valve element 22.

LIST OF REFERENCE SIGNS

[0039] 1 Cooling system

[0040] 2 Motor vehicle

[0041] 3 First cooling circuit

[0042] s 4 Interior

[0043] 5 Second cooling circuit

[0044] 6 Refrigerant circuit

[0045] 7 First circuit line

[0046] 8 Vaporizer

[0047] 9 First conveyor assembly

[0048] 10 Expansion valve

[0049] 11 Environment

[0050] 12 Refrigerant-coolant heat exchanger

[0051] 13 Further expansion valve

[0052] 14 Second circuit line

[0053] 15 Second conveyor assembly

[0054] 16 Cooling component

[0055] 17 Refrigerant circuit line

[0056] 18 First refrigerant sub-circuit

[0057] 19 Second refrigerant sub-circuit

[0058] 20 Conveyor unit

[0059] 21 Condenser

[0060] 22 Valve element

[0061] 23 Control unit

[0062] LD Power deficit

[0063] LI Actual power value

[0064] P Power

[0065] S1 First target power value

[0066] S1.sub.u Initial power target value

[0067] S2 Second target power value

[0068] T Temperature

[0069] T.sub.S Target temperature value

[0070] T.sub.Su Initial target temperature value

[0071] t Time