Coolant circuit arrangement for a motor vehicle and method for operating a coolant circuit arrangement

Abstract

The invention relates to a coolant circuit arrangement (1) for a motor vehicle, comprising a first coolant circuit (2) having a first coolant pump (4) and a second coolant circuit (3) having a second coolant pump (7). It is provided that the first coolant circuit (2) and the second coolant circuit (3) are connected to each other via a pressure transmission line (10) and are fluidically separated from each other away from the pressure transmission line (10), wherein the pressure transmission line (10) is connected on the suction side of the first coolant pump (4) to the first coolant circuit (2) and on the pressure side of the second coolant pump (7) to the second coolant circuit (3) in order to adjust a first coolant pressure present on the suction side of the first coolant pump (4) towards a second coolant pressure present on the pressure side of the second coolant pump (7).The invention further relates to a method for operating a coolant circuit arrangement (1).

Description

[0001] The invention relates to a coolant circuit arrangement for a motor vehicle, comprising a first coolant circuit including a first coolant pump and a second coolant circuit including a second coolant pump. The invention further relates to a method for operating a coolant circuit arrangement.

[0002] For example, the prior art document EP 3 770 010 B1 describes a heat regulation system for an electrically powered vehicle, wherein the system comprises a first and a second closed circuit for circulating a heat transfer fluid, wherein the first closed circuit has a first and a second connection point that divide the first closed circuit into a first and a second branch, the second closed circuit has a third and a fourth connection point that divide the second circuit into a third and a fourth branch, and the first and second connection points can be connected to the third and fourth connection points, respectively.

[0003] Furthermore, the system comprises a first pump positioned along the first branch to circulate the heat transfer fluid from the second connection point to the first connection point, and a second pump positioned along the second closed circuit. The system also includes a first and a second heat exchanger capable of cooling the heat transfer fluid, located along the first and second closed circuits, respectively.

[0004] Finally, the system has a battery pack and an electric / electronic drive unit, which are arranged along the first and second closed circuits respectively and are thus cooled by the heat transfer fluid, and a control valve that can be switched between a first configuration in which the first and second closed circuits transport respective fluid flows independently of each other, and a second configuration in which the first connection point is connected to the third connection point and the second connection point is connected to the fourth connection point, so that they form a single cooling circuit.

[0005] The prior art documents DE 10 2009 051 377 A1, DE 10 2020 134 861 A1, DE 10 2019 205 414 A1 and DE 10 2015 111 407 A1 are also known.

[0006] The object of the invention is to propose a coolant circuit arrangement for a motor vehicle which has advantages over known coolant circuit arrangements, in particular reliably preventing the boiling of coolant in the first coolant circuit.

[0007] This is achieved according to the invention with a coolant circuit arrangement for a motor vehicle with the features of claim 1. It is provided that the first coolant circuit and the second coolant circuit are connected to each other via a pressure transmission line and are fluidically separated from each other away from the pressure transmission line, wherein the pressure transmission line is connected on the suction side of the first coolant pump to the first coolant circuit and on the pressure side of the second coolant pump to the second coolant circuit in order to adapt a first coolant pressure present on the suction side of the first coolant pump to a second coolant pressure present on the pressure side of the second coolant pump.

[0008] Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments described in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are possible.

[0009] The coolant circuit assembly is preferably an integral part of the motor vehicle, but can of course also exist separately, particularly until it is installed on or in the motor vehicle. The coolant circuit assembly serves to regulate the temperature or cool at least one component, preferably several components. For this purpose, it has several coolant circuits, namely at least the first coolant circuit and the second coolant circuit. The first coolant circuit contains a first coolant, and the second coolant circuit contains a second coolant.

[0010] The two coolants, i.e., the first coolant and the second coolant, can be identical. However, it is also possible to use different coolants. The first and second coolants are preferably liquid coolants, meaning they exist in liquid form at least temporarily or predominantly over time. Preferably, both coolants are water-based. This means that the first and second coolants each consist mainly of water. At least one additive, such as antifreeze or the like, can be added to the water in each case. For example, the same additive, particularly with the same concentration or different concentrations, is used for both the first and second coolants, or different additives are used.

[0011] The first coolant is circulated at least temporarily in the first coolant circuit by means of the first coolant pump. The second coolant is also circulated at least temporarily in the second coolant circuit using the second coolant pump. The first and second coolant pumps are preferably operable independently of each other, so that the first and second coolants can be circulated separately in their respective coolant circuits. This means that the equipment or equipment to be temperature-controlled can be independently controlled, or at least temporarily controlled, by means of the coolant circuits.

[0012] For example, the first coolant pump may be operated to circulate the first coolant in the first coolant circuit, while the second coolant pump is deactivated, so that the second coolant is not circulated in the second coolant circuit. Conversely, the first coolant pump may be deactivated, so that the first coolant is not circulated in the first coolant circuit, while the second coolant is circulated in the second coolant circuit using the second coolant pump. However, it is particularly preferred that both coolant pumps are operated simultaneously to circulate both the first coolant in the first coolant circuit and the second coolant in the second coolant circuit.

[0013] Since the coolant circuits serve to cool at least one piece of equipment requiring temperature control, the first coolant and / or the second coolant absorb heat from this equipment, at least temporarily, causing their respective temperatures to rise. If the temperature of the respective coolant exceeds its boiling point, it begins to boil, and gas bubbles of gaseous coolant form. These gas bubbles reduce the efficiency of the respective coolant pump and impair heat transfer via the coolant, for example, by hindering heat absorption from the equipment requiring temperature control and / or heat dissipation, such as in a coolant radiator. For this reason, boiling of the coolant should be prevented.

[0014] For this purpose, the first and second coolant circuits are connected to each other via the pressure transmission line. The connection between the first and second coolant circuits is designed such that they are fluidically separated from each other away from the pressure transmission line. In particular, the two coolant circuits are connected to each other exclusively via the pressure transmission line. The pressure-transmitting connection of the two coolant circuits means that the pressure present in one of the coolant circuits affects the pressure in the other.

[0015] Preferably, the connection of the coolant circuits is designed such that only pressure transmission occurs between them, while an exchange of coolants between the coolant circuits is prevented or at least largely prevented. For example, the pressure transmission line is dimensioned and / or designed such that an exchange of coolants between the two coolant circuits does not occur to any significant extent, even if there is a pressure change in the coolant circuits. This means, in particular, that at most 5%, at most 1%, or at most 0.1% of the first coolant enters the second coolant circuit per hour, and / or at most 5%, at most 1%, or at most 0.1% of the second coolant enters the first coolant circuit.

[0016] The pressure transmission line is connected on one side to the first coolant circuit, specifically the suction side of the first coolant pump. On the other side, it is connected to the second coolant circuit, specifically the pressure side of the second coolant pump. Each coolant pump has a suction side and a pressure side. When a coolant pump is operated to circulate its respective coolant, the coolant is pumped from the suction side towards the pressure side. The coolant then flows through its respective coolant circuit from the pressure side of the pump back to the suction side, from where it is pumped again towards the pressure side.

[0017] Due to pressure losses in the coolant circuits, the coolant pressure on the pressure side of the coolant pump is higher than on its suction side. Since the boiling point of the coolant also depends on its pressure, boiling of the coolant will therefore typically occur on the suction side of the coolant pump. In this case, boiling has the additional disadvantage of causing cavitation in the coolant pump, which further reduces its efficiency. Boiling can be effectively prevented by the described connection of the pressure transfer line to the two coolant circuits and by appropriately operating the coolant pumps.The intention here is to adjust the first coolant pressure of the first coolant on the suction side of the first coolant pump by operating the second coolant pump accordingly, namely in the direction of the second coolant pressure of the second coolant on the pressure side of the second coolant pump.

[0018] The second coolant pump serves not only to circulate the second coolant in the second coolant circuit, but also to maintain a specific pressure level in the first coolant circuit. If the second coolant pump increases the pressure in the second circuit, the pressure in the first circuit also increases, and consequently, so does the overall pressure level in the first circuit. Conversely, if the pressure in the second circuit is reduced by operating the second coolant pump, the pressure in the first circuit decreases, and consequently, so does the pressure level in the first circuit. This means that by operating the second coolant pump, the pressure in the first circuit can be adjusted, or at least temporarily adjusted, to increase the pressure and thus prevent or at least reduce the boiling of the first coolant.This results in particularly efficient operation of the first coolant circuit and consequently of the entire coolant circuit arrangement.

[0019] A further development of the invention provides that a pressure side of the first coolant pump is connected to a first temperature-controlled device via a first coolant heat exchanger, and the pressure transmission line is fluidically connected between the first temperature-controlled device and the suction side of the first coolant pump to the first coolant circuit. The first coolant pumped by the first coolant pump initially flows through the first coolant heat exchanger, where it releases heat, for example to the outside environment or a refrigerant. The first coolant then flows to the first temperature-controlled device. There, it absorbs heat, at least temporarily, thus increasing its temperature.

[0020] The first unit to be cooled is fluidically connected to the suction side of the first coolant pump on its side facing away from the first coolant heat exchanger. The pressure transfer line opens into the first coolant circuit between the first unit to be cooled and the suction side of the first coolant pump, allowing the pressure of the first coolant, which exists between the first unit to be cooled and the suction side of the first coolant pump, to be adjusted via the pressure transfer line. With this configuration of the coolant circuit, the first coolant absorbs heat in the first unit to be cooled before flowing back towards the first coolant pump. This creates the risk of the first coolant boiling. However, boiling is prevented or at least reduced by the pressure transfer line.

[0021] A further development of the invention provides that a pressure side of the second coolant pump is connected to a second device to be tempered via a second coolant heat exchanger and the pressure transmission line is fluidically connected between the pressure side of the second coolant pump and the second coolant heat exchanger to the second coolant circuit, or that the pressure side of the second coolant pump is connected to the second coolant heat exchanger via the second device to be tempered and the pressure transmission line is fluidly connected between the pressure side of the second coolant pump and the second device to be tempered to the second coolant circuit.

[0022] The second coolant circuit can therefore exist in two configurations. In the first configuration, the pressure side of the second coolant pump is connected to the second coolant heat exchanger. In this case, the pressure transmission line between the pressure side of the second coolant pump and the second coolant heat exchanger opens into the second coolant circuit. In the second configuration, the pressure side of the second coolant pump is connected to the second coolant heat exchanger via the second coolant heat exchanger. In this case, the pressure transmission line between the pressure side of the second coolant pump and the second coolant heat exchanger opens into the second coolant circuit. The first configuration has the advantage of particularly effective cooling of the second coolant.The use of the second variant offers the advantage that the pressure transmission line is connected to a point in the second coolant circuit where the second coolant has a comparatively low temperature.

[0023] A further development of the invention provides that the pressure transmission line has a length that is at least 10, at least 30, or at least 50 times greater than its diameter, from a fluid dynamics perspective. It has already been mentioned that the pressure transmission line preferably provides a pressure-transmitting connection exclusively between the two coolant circuits, while preventing any exchange of coolant between the two circuits. This can be achieved, for example, by selecting an appropriate length for the pressure transmission line. Preferably, this length is greater than the diameter of the pressure transmission line by one of the aforementioned factors, i.e., L / D ≥ 10, L / D ≥ 30, or L / D ≥ 50. With such a design of the pressure transmission line, the advantages already mentioned are achieved in a structurally simple manner.

[0024] A further development of the invention provides that the first coolant circuit and the second coolant circuit are fluidically separated via the pressure transmission line, but connected to each other for pressure transmission. Preferably, the pressure transmission line is designed such that the two coolant circuits are completely separated from each other fluidically. This is achieved, for example, by a separating element that is movable and / or elastically deformable within the pressure transmission line. The separating element seals the pressure transmission line, thus preventing an exchange of coolants between the two coolant circuits. At the same time, however, it allows pressure transmission between them. Again, the advantages already mentioned are reliably achieved.

[0025] A further development of the invention provides that a separating element is arranged in the pressure transmission line, which fluidically separates the first coolant circuit and the second coolant circuit. The possible presence of the separating element has already been mentioned. The separating element is, for example, arranged so that it can be moved within the pressure transmission line. Additionally or alternatively, it is elastically deformable. In any case, it is designed such that, on the one hand, it allows pressure transmission between the coolant circuits via the pressure transmission line, but on the other hand, it fluidly separates the two coolants. The advantages already mentioned are thus achieved in a simple manner.

[0026] A further development of the invention provides that the first coolant circuit is a high-temperature circuit. A high-temperature circuit is understood to be a coolant circuit in which, during intended operation of the coolant circuit arrangement, the temperature of the first coolant is at least temporarily or continuously at least 80 °C, at least 100 °C, or at least 120 °C. This means that a certain pressure must be maintained in the first coolant circuit to avoid disadvantages caused by boiling. Accordingly, it is provided, for example, that the first coolant circuit is brought to a specific pressure level during its filling.

[0027] If this pressure level is insufficient, the second coolant pump of the second coolant circuit is operated to increase the first coolant pressure via the pressure transmission line. Preferably, the second coolant circuit is a low-temperature circuit. This is defined as a coolant circuit in which, during normal operation, the second coolant has a temperature of at most 80 °C, at most 70 °C, or at most 60 °C, at least temporarily or continuously. For example, the first coolant circuit serves to cool an internal combustion engine, and the second coolant circuit serves to cool an electrical or electronic device. The described coolant circuit arrangement is particularly advantageous when the first coolant circuit is configured as a high-temperature circuit.

[0028] The invention further relates to a method for operating a coolant circuit arrangement, in particular a coolant circuit arrangement according to the embodiments within the scope of this description, wherein the coolant circuit arrangement has a first coolant circuit comprising a first coolant pump and a second coolant circuit comprising a second coolant pump.The system provides that the first coolant circuit and the second coolant circuit are connected to each other via a pressure transmission line and are fluidically separated from each other away from the pressure transmission line, with the pressure transmission line being connected on the suction side of the first coolant pump to the first coolant circuit and on the pressure side of the second coolant pump to the second coolant circuit, so that a first coolant pressure present on the suction side of the first coolant pump is adjusted towards a second coolant pressure present on the pressure side of the second coolant pump.

[0029] The advantages of such a procedure or such a design of the coolant circuit arrangement have already been mentioned. Both the coolant circuit arrangement and the method for operating it may be further developed as explained in this description, and reference is made to these explanations in that regard.

[0030] A further development of the invention provides that the second coolant pump is controlled in such a way that the first coolant pressure is adjusted towards a target pressure, in particular regulated to the target pressure. The target pressure is determined in any desired manner. If the first coolant pressure deviates from the target pressure, the second coolant pump is controlled so that the first coolant pressure changes towards the target pressure. This is done, for example, within the framework of a control system, so that the first coolant pressure is regulated to the target pressure by appropriately operating the second coolant pump. In any case, boiling of the first coolant can be reliably prevented.

[0031] A further development of the invention provides that the setpoint pressure is selected depending on the coolant temperature present in the first coolant circuit, in particular such that boiling of the first coolant circulated in the first coolant circuit is prevented. The coolant temperature is preferably understood to be the temperature of the first coolant on the suction side of the first coolant pump, or, in terms of fluid flow, between the first device to be temperature-controlled and the suction side of the first coolant pump. For example, the setpoint pressure is selected such that the boiling point of the first coolant at the setpoint pressure is higher than the coolant temperature, for example by a certain temperature difference, in particular by at least 5 K, at least 10 K, or at least 15 K. This reliably prevents boiling of the first coolant.

[0032] The features and combinations of features described in the description, in particular those described in the following figure description and / or shown in the figures, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention, in particular the scope of the claims. Thus, embodiments that are not explicitly shown or explained in the description and / or the figures, but which emerge from or can be derived from the explained embodiments, particularly within the scope of the claims, are also to be considered as encompassed by the invention.

[0033] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The only embodiment shown is... Fig. 1 A schematic representation of a coolant circuit arrangement with a first coolant circuit and a second coolant circuit.

[0034] The Fig. Figure 1 shows a schematic representation of a coolant circuit arrangement 1, such as that used on board a motor vehicle. The coolant circuit arrangement 1 has a first coolant circuit 2 and a second coolant circuit 3. The first coolant circuit 2 has a first coolant pump 4, a first coolant heat exchanger 5, and at least one temperature-controlled device 6. By means of the first coolant pump 4, a first coolant is circulated in the first coolant circuit 2. This coolant flows downstream of the first coolant pump 4 first through the first coolant heat exchanger 5 and then through the first temperature-controlled device 6 before returning to the first coolant pump 4.

[0035] The second coolant circuit 3 comprises a second coolant pump 7, a second coolant heat exchanger 8, and at least one second temperature-controlled device 9. The second coolant pump 7 circulates a second coolant in the second coolant circuit 3, at least temporarily. This coolant flows downstream of the second coolant pump 7 first to the second temperature-controlled device 9 and then to the second coolant heat exchanger 8, before returning to the second coolant pump 7. However, other configurations of the second coolant circuit 3 are also possible.

[0036] The first coolant circuit 2 and the second coolant circuit 3 are connected to each other via a pressure transmission line 10. At one end, the pressure transmission line 10 enters the first coolant circuit 2 between the first temperature-controlled unit 6 and the suction side of the first coolant pump 4. At its other end, it enters the second coolant circuit 3 between the pressure side of the second coolant pump 7 and the second temperature-controlled unit 9. The first coolant circuit 2 is designed as a high-temperature circuit, whereas the second coolant circuit 3 is, for example, a low-temperature circuit.

[0037] A first coolant pressure of the first coolant can be set via the pressure transmission line 10. This pressure exists between the first temperature-controlled device 6 and the suction side of the first coolant pump 4. For this purpose, the second coolant pump 7 is operated such that a specific second coolant pressure of the second coolant is established. This pressure exists between the pressure side of the second coolant pump 7 and the second temperature-controlled device 9. The second coolant pressure influences the first coolant pressure; in particular, the first coolant pressure adjusts towards the second coolant pressure.

[0038] Preferably, the second coolant pump 7 is operated such that the first coolant pressure corresponds to a setpoint pressure. The setpoint pressure is selected depending on the coolant temperature of the first coolant, which is preferably located between the first device to be temperature-controlled 6 and the suction side of the first coolant pump 4. This approach reliably prevents the first coolant from boiling. This results in particularly high efficiency of the coolant circuit arrangement 1 and effective temperature control or cooling of the devices 6 and 9. REFERENCE MARK LIST: 1 Coolant circuit arrangement 2 first coolant circuit 3 second coolant circuit 4 first coolant pump 5 first coolant heat exchanger 6. First unit to be tempered 7 second coolant pump 8 second coolant heat exchanger 9 second unit to be tempered 10 Pressure transmission line

Claims

[1] Coolant circuit arrangement (1) for a motor vehicle, comprising a first coolant circuit (2) comprising a first coolant pump (4) and a second coolant circuit (3) comprising a second coolant pump (7), characterized by , that the first coolant circuit (2) and the second coolant circuit (3) are connected to each other via a pressure transmission line (10) and are fluidically separated from each other away from the pressure transmission line (10), wherein the pressure transmission line (10) is connected on the suction side of the first coolant pump (4) to the first coolant circuit (2) and on the pressure side of the second coolant pump (7) to the second coolant circuit (3) in order to adapt a first coolant pressure present on the suction side of the first coolant pump (4) towards a second coolant pressure present on the pressure side of the second coolant pump (7). [2] Coolant circuit arrangement according to claim 1, characterized by , that a pressure side of the first coolant pump (4) is connected via a first coolant heat exchanger (5) to a first device to be tempered (6) and the pressure transmission line (10) is fluidically connected between the first device to be tempered (6) and the suction side of the first coolant pump (4) to the first coolant circuit (2). [3] Coolant circuit arrangement according to one of the preceding claims, characterized by, that a pressure side of the second coolant pump (7) is connected via a second coolant heat exchanger (8) to a second temperature-controlled device (9) and the pressure transmission line (10) is fluidically connected between the pressure side of the second coolant pump (7) and the second coolant heat exchanger (8) to the second coolant circuit (3), or that the pressure side of the second coolant pump (7) is connected via the second temperature-controlled device (9) to the second coolant heat exchanger (8) and the pressure transmission line (10) is fluidly connected between the pressure side of the second coolant pump (7) and the second temperature-controlled device (9) to the second coolant circuit (3). [4] Coolant circuit arrangement according to one of the preceding claims, characterized by, that the pressure transmission line (10) has a length which is greater by a factor of at least 10, at least 30 or at least 50 than a diameter of the pressure transmission line (10). [5] Coolant circuit arrangement according to one of the preceding claims, characterized by , that the first coolant circuit (2) and the second coolant circuit (3) are fluidically separated via the pressure transmission line (10), but connected to each other in a pressure-transmitting manner. [6] Coolant circuit arrangement according to one of the preceding claims, characterized by , that a separating element is arranged in the pressure transmission line (10) which fluidically separates the first coolant circuit (2) and the second coolant circuit (3). [7] Coolant circuit arrangement according to one of the preceding claims, characterized by , that the first coolant circuit (2) is a high-temperature circuit. [8] Method for operating a coolant circuit arrangement (1) according to one or more of the preceding claims, wherein the coolant circuit arrangement (1) has a first coolant circuit (2) having a first coolant pump (4) and a second coolant circuit (3) having a second coolant pump (7), characterized by, that the first coolant circuit (2) and the second coolant circuit (3) are connected to each other via a pressure transmission line (10) and are fluidically separated from each other away from the pressure transmission line (10), wherein the pressure transmission line (10) is connected on the suction side of the first coolant pump (4) to the first coolant circuit (2) and on the pressure side of the second coolant pump (7) to the second coolant circuit (3), so that a first coolant pressure present on the suction side of the first coolant pump (4) is adjusted towards a second coolant pressure present on the pressure side of the second coolant pump (7). [9] Method according to claim 8, characterized by , that the second coolant pump (7) is controlled in such a way that the first coolant pressure is adjusted towards a target pressure. [10] Method according to claim 8 or 9, characterized by, that the target pressure is selected depending on the coolant temperature present in the first coolant circuit (2).

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