Thermal management system with coolant circuit and heat exchanger thermally operatively connected to a refrigerant circuit, method for operating such a thermal management system and motor vehicle having such a thermal management system

Abstract

The invention relates to a thermal management system (10) for an at least partially electrically driven motor vehicle (100), having a refrigerant circuit (12), a coolant circuit (22) with at least one coolant pump (24, 24z), a heat exchanger (18), in particular a chiller, which is thermally operatively connected to the refrigerant circuit (12) and to the coolant circuit (22), wherein the coolant circuit (22) is connected to at least one electric component (26), in particular a battery storage unit, of the motor vehicle (100) for the conditioning, in particular cooling, of said electric component. According to the invention, the coolant circuit (22) has: a main line portion (22h), which connects the coolant pump (24) to the electric component (26), and at least one secondary line portion (22n, 22nz), which downstream of the coolant pump (24) branches off from the main line portion (22h) at a branching point (A1, A2) and upstream of the electric component (26) opens into the main line portion (22h) at an opening point (M1, M2), wherein the heat exchanger (18) is arranged in the main line portion (22h) or in the secondary line portion (22n). The invention also relates to a method for operating such a thermal management system (10) and to a motor vehicle (100) having such a thermal management system (10).

Description

[0001] Thermal management system with coolant circuit and heat exchanger in thermal connection with a refrigerant circuit, method for operating such a thermal management system and motor vehicle with such a thermal management system

[0002] DESCRIPTION:

[0003] The invention relates to a thermal management system for an at least partially electrically powered motor vehicle, comprising a refrigerant circuit, a coolant circuit with at least one coolant pump, and a heat exchanger, in particular a chiller, which is in thermal communication with the refrigerant circuit and the coolant circuit. The coolant circuit is connected to at least one electrical component, in particular a battery storage unit, of the motor vehicle for conditioning, in particular cooling, the component. Furthermore, the invention relates to a method for operating such a thermal management system and to a motor vehicle having such a thermal management system.

[0004] For the state of the art, reference is made to, for example, DE 10 2009 015 658 A1, DE 10 2011 118 162 A1 and DE 10 2018 206 936 A1.

[0005] In thermal management systems in motor vehicles with at least partially electric drive, particularly in hybrid or electric vehicles, the refrigerant circuit and the coolant circuit are thermally connected. For example, in AC operation of the refrigerant circuit, a high coolant temperature, particularly in combination with high coolant volume flows, leads to increased low pressure in the refrigerant circuit. In other words, an increased cooling demand on the electrical component, which is accompanied by heating of the coolant, creates a kind of conflict of objectives with an optimal operating pressure in the refrigerant circuit when it is used to cool interior air (AC operation).

[0006] The object underlying the invention is to provide a thermal management system in which an optimized AC operation of the refrigerant circuit is enabled at a permanently high coolant temperature.

[0007] This problem is solved by a thermal management system, a method for its operation, and a motor vehicle having the features of the respective independent patent claim. Advantageous embodiments with useful further developments are specified in the dependent patent claims.

[0008] What is proposed is a thermal management system for an at least partially electrically driven motor vehicle, comprising a refrigerant circuit, a coolant circuit with at least one coolant pump, and a heat exchanger, in particular a chiller, which is in thermal connection with the refrigerant circuit and the coolant circuit, wherein the coolant circuit is connected to at least one electrical component, in particular a battery storage unit, of the motor vehicle for conditioning, in particular cooling, the component.It is provided that the coolant circuit comprises: a first main line section which connects the coolant pump to the electrical component, and at least one secondary line section which branches off from the main line section at a branching point downstream of the coolant pump and opens into the main line section at a mouth point upstream of the electrical component, wherein the heat exchanger is arranged in the main line section or in the secondary line section.

[0009] By means of the proposed structure of the coolant circuit with main line section and with secondary line section as well as the heat exchanger optionally arranged in one of these line sections, a basic structure is provided which makes it possible to influence the active flow of coolant through the heat exchanger so that due to the thermal interaction in the refrigeration system, a desired low pressure level is achieved for the (evaporating) refrigerant, on the one hand for an interior cooling process to be carried out parallel to a coolant cooling process and on the other hand for a pure coolant cooling process.

[0010] In the thermal management system, at least one valve device can be assigned to the secondary line section and / or the main line section, which valve device is configured to adjust a coolant volume flow through the secondary line section and / or the main line section. Using one or more valve devices, the coolant volume flow delivered by the coolant pump can, on the one hand, be selectively directed entirely through the main line section or entirely through the secondary line section, and, on the other hand, the delivered coolant volume flow can be distributed into partial volume flows between the main line section and the secondary line section.This allows for optimized use of the coolant volume flow delivered by the coolant pump to achieve the desired conditioning, particularly sufficient cooling, of the electrical component, while also adjusting the heat input from the coolant to the refrigerant circuit to an operating state that prevents the low-pressure level of the refrigerant from being raised or excessively raised. In other words, this approach or this thermal management system design is suitable for reducing the low-pressure level of the refrigerant by reducing the coolant volume flow.

[0011] In the thermal management system, the secondary line section can form a bypass to bypass the heat exchanger located in the main line section. This makes it possible to circulate at least a partial volume flow in the coolant circuit in a targeted manner past the heat exchanger, so that the coolant actively circulates in the coolant circuit even when only a small amount of heat is transferred to the refrigerant circuit in the heat exchanger. This enables a type of modified cooling of the electrical component, so that conditioned coolant can always be provided to the electrical component at the required total volume flow, but with a reduced mixed temperature of the two partial volume flows.

[0012] This ensures that the electrical component is always provided with the required coolant volume flow. This coolant volume flow is split upstream of the electrical component into two separate lines. The first line or bypass line is flowed through by an unconditioned first (partial) volume flow, and the second line, containing the heat exchanger, enables conditioning of the second (partial) volume flow. The unconditioned and conditioned volume flows are recombined upstream of the electrical component and adjusted to a new, lower mixed temperature level, which creates a cooling effect on the electrical component.

[0013] A low volume flow at the (refrigerant-to-coolant) heat exchanger can result in a reduced low-pressure level in the refrigerant circuit, particularly in a refrigeration system operating in the "combined or parallel interior cooling and coolant cooling" configuration. This can result in effective cooling of the coolant due to an increased temperature gradient or increased driving temperature difference between the refrigerant and the coolant. The cold coolant flow and the warm (bypass) coolant flow provide a new, cooler mixed temperature for the electrical component.

[0014] In the thermal management system, an additional coolant pump can be arranged in the secondary line section. The branch point of the secondary line section can be arranged downstream of the discharge point of the secondary line section with respect to the main line section, such that the coolant in the secondary line section is conveyed counter to the flow direction in the main line section. In other words, a type of coolant recirculation can be realized in this way, so that the coolant can be (re)circulated locally in the area of ​​the branch point, secondary line section, discharge point, and main line section (between the branch point and discharge point).

[0015] In the thermal management system, a check valve can be installed in the secondary line section between the additional coolant pump and the outlet point. This prevents coolant from flowing back against the desired circulation direction. Furthermore, when the additional coolant pump is not operating, it can be ensured that the coolant is only pumped through the main line section.

[0016] In the thermal management system, the heat exchanger can be located downstream of the additional coolant pump in the secondary line section. This configuration allows the heat exchanger to be integrated as needed at any time and supplied with a (partial) volume flow of coolant as required.

[0017] In the thermal management system, the heat exchanger can be arranged in the main line section, wherein the secondary line section can provide a return of coolant for flowing through the heat exchanger again, and wherein the coolant circuit can have an additional secondary line section that forms a bypass for the heat exchanger and the secondary line section with the additional coolant pump. This makes it possible to both enable a (re)circulation of coolant through the heat exchanger, thus enabling a type of boost cooling of at least a partial volume flow of coolant, and to enable at least partial bypassing of the heat exchanger for a (partial) volume flow of coolant.

[0018] A method for operating a thermal management system with the generic properties is also proposed, wherein the power of the coolant pump is reduced so that the coolant volume flow passed through the heat exchanger is smaller than a maximum possible coolant volume flow, such that the coolant continues to circulate in the coolant circuit and, due to the thermal active connection between the coolant circuit and the refrigerant circuit, a low pressure in the refrigerant circuit is maintained or reduced.

[0019] A method for operating a thermal management system described above is also proposed, wherein the coolant volume flow is directed proportionally through the main line section and the at least one secondary line section such that downstream of the outlet point, a maximum coolant volume flow is supplied to the electrical component for cooling it. The (partial) volume flows of coolant flowing through the main / secondary sections can be adjusted as needed by changing the cross-section of at least one coolant-side valve. In this way, a partial volume flow can be specifically directed to the heat exchanger to cool the coolant, thus setting a desired low-pressure level for the coolant. The coolant, in turn, enables optimal coolant conditioning in addition to interior air conditioning.

[0020] In the method, in a thermal management system with the additional coolant pump in the secondary line section, the coolant pump in the main line section and the additional coolant pump in the secondary line section can be operated alternately or simultaneously. Particularly when both coolant pumps are operated simultaneously, one coolant pump is operated at a lower power than the other. This allows the coolant flow to the electrical component and through the heat exchanger to be optimally adjusted.

[0021] Also proposed is a motor vehicle with at least partially electric drive and with a thermal management system described above, which can also be operated in particular according to a method mentioned above. Further advantages and details of the invention will become apparent from the following description of embodiments with reference to the figures. In the figures:

[0022] Fig. 1 shows a simplified and schematic view of a thermal management system with refrigerant circuit and coolant circuit in a motor vehicle;

[0023] Fig. 2 shows a simplified and schematic view of a thermal management system with a secondary line section in the coolant circuit;

[0024] Fig. 3 shows a simplified and schematic view of a thermal management system with a bypass section having an additional coolant pump;

[0025] Fig. 4 shows a simplified and schematic view of a thermal management system with a bypass section having an additional coolant pump and with an additional bypass section;

[0026] Fig. 5 shows a simplified and schematic view of a thermal management system with a bypass section, which has an additional coolant pump and a heat exchanger.

[0027] Fig. 1 shows a simplified and schematic representation of a thermal management system 10, which is arranged in a motor vehicle 100, illustrated purely schematically as a dot-dash rectangle. The motor vehicle 100 has a drive system (not shown here) that is at least partially electric. The motor vehicle 100 is therefore a hybrid vehicle or an electric vehicle.

[0028] The thermal management system 10 has a refrigerant circuit 12, shown in dashed lines. In the highly simplified representation shown here, the refrigerant circuit 12 comprises a refrigerant compressor 14, an external condenser or gas cooler 16, and an evaporator 18, which is implemented here as a so-called chiller. Upstream of the evaporator 18, a conventionally provided expansion element or valve 20 is shown. It should be noted that the refrigerant circuit 12 is illustrated here with only very few components. Of course, the refrigerant circuit 12 can also have other components not shown, such as at least one interior evaporator, a heating register, a refrigerant collection tank, and the like.

[0029] The thermal management system 12 further comprises a coolant circuit 22, illustrated by solid lines. The coolant circuit 22 has a (first) coolant pump 24. Furthermore, the coolant circuit is connected to the heat exchanger 18 or chiller 18, so that the coolant circuit 22 and the refrigerant circuit 12 are in operative thermal communication with one another. The coolant circuit 22 is configured, in particular, to condition, in particular, to cool, an electrical component 26 of the motor vehicle 100, which is illustrated here as an example of a battery storage unit.

[0030] In the coolant circuit 22, the coolant flows clockwise in the selected representation, which is illustrated by the corresponding arrow symbols.

[0031] With a thermal management system 10, which has a configuration according to

[0032] Fig. 1, a method for operating the thermal management system 10 can be carried out, wherein the power of the coolant pump 24 is reduced so that the coolant volume flow Vp_CH conducted through the heat exchanger 18 is smaller than a maximum possible coolant volume flow Vp_max, such that the coolant continues to circulate in the coolant circuit and due to the thermal operative connection between the coolant circuit 22 and the refrigerant circuit 12, a low pressure in the refrigerant circuit 12 is maintained or reduced.

[0033] Fig. 2 shows a thermal management system 10 similar to Fig. 1. Components that have already been explained with reference to Fig. 1 have the same reference numerals, so a repeated description is omitted.

[0034] The thermal management system 10 of Fig. 2 has a main line section 22h in the coolant circuit 22, which connects the coolant pump 24 to the electrical component 26. The main line section 22h can also be understood as a supply section with respect to the electrical component 26 to be cooled.

[0035] The coolant circuit 22 has a secondary line section 22n, which branches off from the main line section 22h at a branch point A1 downstream of the coolant pump 24 and flows into the main line section 22h at a junction point M1 upstream of the electrical component 26. In the example shown, the heat exchanger 18, which is in thermal communication with the refrigerant circuit 12, is arranged in the main line section 22h of the coolant circuit 22.

[0036] A valve device 28 is assigned to the secondary line section 22n, which is configured to adjust the coolant volume flow via the secondary line section 22n or the main line section 22h. Additionally, a valve device 30 can also be provided in the main line section 22h. Furthermore, it is also conceivable for a single valve device, for example in the form of a mixing valve, to be arranged in the region of the branch A1.

[0037] In the example of Fig. 2, the secondary line section 22n forms a bypass to bypass the heat exchanger 18 arranged in the main line section 22h.

[0038] The valve device 28 and / or the valve device 30 can adjust the volume flow of coolant that is routed through the main line section 22h or the secondary line section 22n. Thus, with a thermal management system 10 according to Fig. 2, a method for operating the thermal management system 10 can be carried out, wherein the coolant volume flow Vp_max is routed proportionally through the main line section Vp_CH and the secondary line section Vp_BP such that downstream of the outlet point M1, a maximum coolant volume flow Vp_max is supplied to the electrical component 26 for cooling. Essentially, the following applies: Vp_max = Vp_CH + Vp_BP

[0039] This makes it possible to circulate at least a partial volume flow Vp_BP specifically past the heat exchanger 18 in the coolant circuit 22, so that the coolant actively circulates in the coolant circuit 22 even when heat transfer to the refrigerant circuit 12 is desired in the heat exchanger 18. In such a configuration, the refrigerant circuit 12 is either in dual operation and is thus set to a low evaporation temperature level while simultaneously requiring the maintenance of the interior air conditioning. Or the single chiller mode is selected and, analogously, at a high (total) coolant volume flow and / or at potentially high heat transfer values ​​(k*A [W / m 2K]) between electrical component 28 and coolant, for the adjustability of permissible low-pressure levels in refrigeration system 12, this target pressure level is set by partial volume flows at heat exchanger 18. Excessively high low-pressure levels of the refrigerant, in turn, result in high densities and thus mass flows of the refrigerant and lead to functional limitations at compressor 14, such as excessive torque. This enables a type of modified cooling of electrical component 26, so that conditioned coolant can always be provided to electrical component 26 at the required total volume flow, but with the resulting mixed temperature of the two partial volume flows.

[0040] Fig. 3 shows the thermal management system 10 as in Fig. 2. In contrast to the example in Fig. 2, an additional (second) coolant pump 24z is arranged in the secondary line section 22n. The branch point A1 of the secondary line section 22n can now be arranged downstream of the outlet point M1 of the secondary line section 22n with respect to the main line section. In other words, the branch A1 and the outlet M1 of the secondary line section 22n are interchanged compared to the previous illustration in Fig. 2.

[0041] Thus, in the secondary line section 22n, the coolant is conveyed counter to the flow direction in the main line section 22h. In other words, a type of coolant recirculation (also referred to as a short circuit) can be realized in this way, so that the coolant can be (re)circulated locally in the area of ​​branch point A1, secondary line section 22n, outlet point M1, and main line section 22h.

[0042] A check valve 32 can be arranged in the secondary line section 22n between the additional coolant pump 24z and the outlet point M1. This prevents coolant from flowing back against the desired circulation direction in the secondary line section 22n. Furthermore, when the additional coolant pump 24z is not operating, it can be ensured that the coolant is only pumped through the main line section 22h and thus through the heat exchanger 18.

[0043] Due to the possibility of returning or recirculating coolant, a type of boost cooling of coolant can be achieved if the coolant is recirculated for a certain period of time by means of the bypass line section 22n and the additional coolant pump 24z.

[0044] With a thermal management system 10 according to Fig. 3, a method for operating the thermal management system 10 can be carried out, wherein the coolant pump 24 in the main line section 22h and the additional coolant pump 24z in the secondary line section 22n are operated alternately or simultaneously. Furthermore, a method can be implemented wherein, during simultaneous operation of the two coolant pumps 24, 24z, one coolant pump, for example, the first coolant pump 24 in the main line section 22h, is operated at a lower power than the other coolant pump, for example, the second coolant pump 24z in the secondary line section 22n. This allows the coolant flow to the electrical component 26 and through the heat exchanger 18 to be optimally adjusted.Furthermore, it is also conceivable that when starting the coolant circuit 22, initially only the second coolant pump 24z is put into operation, so that a well-cooled amount of coolant can be generated by means of recirculation, wherein the first coolant pump 24 can be started up in a targeted or continuous manner at a later time in order to effect the circulation of coolant to the electrical component 26.

[0045] Fig. 4 shows an example of the thermal management system 10, which is in principle a combination of the examples in Figs. 2 and 3.

[0046] The heat exchanger 18 is arranged in the main line section 22h, wherein the secondary line section 22n can provide a return of coolant for flowing through the heat exchanger 18 again. With regard to the secondary line section 22n and the arrangement of the branch A1 and the orifice M1, reference is made to the above description of Fig. 3, which also applies here.

[0047] In the example of Fig. 4, the coolant circuit 22 has an additional secondary line section 22nz, which forms a bypass for the heat exchanger 18 and the secondary line section 22n with the additional coolant pump 24z.

[0048] The additional secondary line section 22nz starts at a branch A2 and ends at an orifice M2. The additional secondary line section 22nz is essentially designed like the secondary line section 22n (without coolant pump) of Fig. 2. For the sake of completeness, the valve devices 28, 30, which are already known from Fig. 2, are also shown again for the configuration of Fig. 4.

[0049] This makes it possible to enable both a (re)circulation of coolant through the heat exchanger 18, thus enabling a type of boost cooling of at least a partial volume flow of coolant, and to enable at least partial bypassing of the heat exchanger for a (partial) volume flow of coolant. This arrangement allows two sub-circuits in the coolant circuit to be operated completely independently. On the one hand, the electrical component 26 can be supplied with coolant and flushed via the pump 24 and the additional secondary line section 22nz. On the other hand, the heat exchanger 18 can specifically condition the coolant flow circulating there via the additional pump 24z and the secondary line section 22n.In this section, it is even conceivable to install a coolant reservoir (not shown) for (pre-)conditioned coolant, which can be metered into the inflow to the electrical component 26 or completely mixed in as needed. The reservoir, in turn, can be directly and permanently integrated into the secondary branch 22n or provided in a switchable manner, whereby the latter can be realized by means of an additional branch if necessary.

[0050] The thermal management system 10 with the configuration of Fig. 4 enables flexible operation of the coolant circuit 22, whereby both a complete bypass of the heat exchanger 18 is possible and a recirculation of coolant for the purpose of boost cooling, as already described above with reference to Figs. 2 and 3.

[0051] Fig. 5 shows another example of the thermal management system 10. Here, the coolant circuit 22 has the secondary line section 22n as already described with reference to Fig. 3, i.e., with an additional coolant pump 24z. In this example, however, the heat exchanger 18 is arranged downstream of the additional coolant pump 24z in the secondary line section 22n. Using such a configuration, the heat exchanger 18 can be integrated at any time as needed and supplied with a demand-based (partial) volume flow of coolant.

[0052] During operation of such a thermal management system 10 shown in Fig. 5, the first coolant pump 24 can, in principle, be controlled as desired or operated with any power consumption. Coolant is supplied to the heat exchanger 18 as needed via the additional (second) coolant pump 24z, and the cooled coolant is then mixed back into the main coolant flow at M1. The two coolant pumps 24, 24z can be operated simultaneously, and they can be operated with the same or different power consumption.

[0053] It should also be noted that such a cooling concept is not necessarily geared exclusively to electric drive concepts or the cooling of their components. In a similar way, it can also cover and serve cooling effects for internal combustion engines or other alternative high-temperature concepts with high coolant turnover.

Claims

PATENT CLAIMS:

1. Thermal management system (10) for an at least partially electrically driven motor vehicle (100) with a refrigerant circuit (12), a coolant circuit (22) with at least one coolant pump (24, 24z), a heat exchanger (18), in particular a chiller, which is in thermal operative connection with the refrigerant circuit (12) and the coolant circuit (22), wherein the coolant circuit (22) is connected to at least one electrical component (26), in particular a battery storage unit, of the motor vehicle (100) for its conditioning, in particular cooling, characterized in that the coolant circuit (22) has: a main line section (22h) which connects the coolant pump (24) to the electrical component (26), and at least one secondary line section (22n, 22nz) which is connected downstream of the coolant pump (24) from the main line section (22h) at a branch point (A1,A2) branches off and opens into the main line section (22h) at a point of confluence (M1, M2) upstream of the electrical component (26), wherein the heat exchanger (18) is arranged in the main line section (22h) or in the secondary line section (22n).

2. Thermal management system (10) according to claim 1, characterized in that at least one valve device (28, 30) is assigned to the secondary line section (22n) and / or the main line section (22h), which valve device is designed to adjust a coolant volume flow via the secondary line section (22n) and / or the main line section (22h).

3. Thermal management system (10) according to claim 1 or 2, characterized in that the secondary line section (22n) forms a bypass. to bypass the heat exchanger (18) arranged in the main line section (22h).

4. Thermal management system (10) according to one of the preceding claims, characterized in that an additional coolant pump (24z) is arranged in the secondary line section (22n), and in that the branching point (A1) of the secondary line section (22n) is arranged downstream of the mouth point (M1) of the secondary line section (22n) with respect to the main line section (22h), such that in the secondary line section (22n) the coolant is conveyed counter to the flow direction in the main line section (22h).

5. Thermal management system (10) according to claim 4, characterized in that a check valve (32) is arranged in the secondary line section (22n) between the additional coolant pump (24z) and the outlet point (M1).

6. Thermal management system (10) according to claim 4 or 5, characterized in that in the secondary line section (22n) the heat exchanger (18) is arranged downstream of the additional coolant pump (24z).

7. Thermal management system (10) according to claim 4 or 5, characterized in that the heat exchanger (18) is arranged in the main line section (22h), the secondary line section (22n) provides a return of coolant for flowing through the heat exchanger again, and that the coolant circuit (22) has an additional secondary line section (22nz) which forms a bypass for the heat exchanger (18) and the secondary line section (22n) with the additional coolant pump (24z).

8. A method for operating a thermal management system (10) according to the preamble of claim 1, wherein the power of the coolant pump (24) is reduced so that the heat exchanger (18) is smaller than a maximum possible coolant volume flow, such that the coolant continues to circulate in the coolant circuit (22) and due to the thermal active connection between the coolant circuit (22) and the refrigerant circuit (12) a low pressure in the refrigerant circuit (12) is maintained or reduced.

9. A method for operating a thermal management system (10) according to one of claims 1 to 7, wherein the coolant volume flow is passed proportionally through the main line section (22h) and the at least one secondary line section (22n, 22nz) such that downstream of the mouth point (M1) a maximum coolant volume flow is supplied to the electrical component (26) for cooling thereof.

10. The method according to claim 9, wherein in a thermal management system (10) with the additional coolant pump (24z) in the secondary line section (22n), the coolant pump (24) in the main line section (22h) and the additional coolant pump (24z) in the secondary line section (22n) are operated alternately or simultaneously, wherein in particular when the two coolant pumps (24, 24z) are operated simultaneously, one coolant pump is operated with a lower power than the other coolant pump.

11. Motor vehicle (100) with at least partially electric drive with a thermal management system (10) according to one of claims 1 to 7.

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