Cooling circuit and control procedure for a thermal management system

Abstract

Cooling circuit (1) configured for a thermal management system (2) comprising the following components: - a circuit management (3); - a switchable pressure source (4); - an adjustable control valve (5) for controlling a coolant flow in the circuit line (3) and - a control unit (6) for controlling the pressure source (4), characterized in that the control unit (6) is communicatively connected to the control valve (5), so that when the control valve (5) is adjusted, the pressure source (4) is switched off by means of the control unit (6) and / or the line pressure in the circuit line (3) is reduced.

Description

[0001] The invention relates to a cooling circuit for a thermal management system, a control method for controlling a pressure source of such a cooling circuit, and a thermal management system with such a cooling circuit.

[0002] Cooling circuits are known from the prior art that comprise a thermal management module (WMM), also referred to as a thermal management module (TMM), as a thermal management system, for example as a cooling control circuit for an internal combustion engine of a motor vehicle. For example, DE 10 2013 209 582 A1 discloses a control valve designed as a rotary valve ball for a thermal management module, which is designed for space-optimized components of a cooling circuit of an internal combustion engine. Such a rotary valve is driven by an electric motor and can be moved into various positions, for example, a closed position or an open position. For many applications, it is necessary to search for cost-effective solutions that also enable the lowest possible energy consumption.

[0003] DE 10 2017 122 271 A1 discloses a switching unit for a WMM of a motor vehicle.

[0004] DE 10 2014 207 280 A1 discloses a cooling system for a motor vehicle and a valve regulating the cooling system.

[0005] DE 103 11 188 A1 discloses a method and a device for demand-based cooling of an internal combustion engine.

[0006] DE 10 2008 000 876 A1 discloses a motor vehicle air conditioning control system with an electric water pump.

[0007] Based on this, the present invention is based on the object of at least partially overcoming the disadvantages known from the prior art. The features of the invention are derived from the independent claims, for which advantageous embodiments are presented in the dependent claims. The features of the claims can be combined in any technically reasonable manner, whereby the explanations from the following description as well as features from the figures, which comprise additional embodiments of the invention, can also be consulted for this purpose.

[0008] The invention relates to a cooling circuit for a thermal management system comprising the following components: - a district management; - a switchable pressure source; - an adjustable control valve for controlling a cooling liquid flow in the circuit and - a control unit for controlling the pressure source.

[0009] The cooling circuit is characterized in that the control unit is communicatively connected to the control valve, so that when the control valve is adjusted, the pressure source is switched off by means of the control unit and / or a line pressure in the circuit line is reduced.

[0010] A circuit line is designed to carry a coolant at a desired line pressure so that a desired coolant flow can be circulated and heat from a heat source is dissipated. The pressure source is, for example, a pump or a closable connection to a pressure system. The control valve is, for example, a rotary slide valve whose actuator is a rotary slide by means of which a coolant flow can be discretely or continuously controlled, i.e. throttled. Alternatively, the control valve is a switching valve by means of which two, three or more discrete states (a small total number) can be set, for example, a partial circuit can be switched on or off. The actuator for changing a position or state of the actuator of the control valve is, in one embodiment, structurally integrated into the control valve. In another embodiment, the actuator is a separate structural unit.The control unit is a central processor, for example, one integrated into a motor vehicle's electrical system or the pressure source. For example, the control unit consists of several decentralized processors that communicate with each other, meaning that, for example, computing power and storage power are spatially separated and / or decentralized.

[0011] The hydraulic system conditions of the cooling circuit, for example, of a motor vehicle, and the boundary conditions within the coolant regulator determine certain performance requirements for the actuator of a coolant regulator in order to be able to perform an adjustment process of the control valve's actuator. When line pressure is applied, such an adjustment process of the control valve must occur in addition to the system's inherent friction against the respective line pressure. Under certain load cases, this can result in very high hydraulic forces acting on the control valve.

[0012] Due to the increasing number of mechatronic systems in motor vehicles and / or the demand for lower power consumption, especially electrical power consumption, the use of smaller actuators is desirable. This is also advantageous in terms of the cost of such actuators. However, in certain load cases, a smaller actuator is not capable of adjusting the control valve's actuator against the applied hydraulic line pressure.

[0013] Today's cooling circuits are usually pressure-controlled, i.e., operated with a constant line pressure. In order to be able to make the actuators smaller, it is proposed here to deviate from this and thus reduce the required actuating forces on the actuator of the control valve. For this purpose, a control unit is provided, preferably a conventionally available pressure control unit, which not only controls the pressure source, for example, based on a detected line pressure, but also communicates with the control valve. When it is stated that the control unit communicates with the control valve, this means communication with the associated actuator with regard to controlling a change in the position of the actuator and / or communication with a sensor on or near the actuator of the control valve.This means that either a control of the control valve is integrated into the control unit for the pressure source or a control signal for the control valve is also transmitted to the control unit. In one embodiment, a control signal is transmitted directly from a further control unit that is set up to control the control valve and is, for example, conventionally designed, to the control unit of the pressure source. Alternatively or additionally, a control signal is transmitted directly or indirectly from the control valve, for example by detecting a characteristic variable, such as the application of an electrical voltage and / or a mechanical actuating force to the actuator of the control valve, to the control unit of the pressure source, or such a characteristic variable is detected by this control unit itself.

[0014] In response to this control signal, in one embodiment, the pressure source is briefly shut off until the control valve actuator is moved to the new position. In another embodiment, the line pressure applied to the control valve is merely reduced. For example, the pressure source is operated at a reduced power.

[0015] This measure makes it possible to create a smaller actuator, with lower power requirements, and / or with a technology unsuitable for high actuating forces. One such technology is a permanent magnet-operated control valve, for example, in which the actuating force is limited by the system. A control-technically complex and power-intensive spindle drive, which can generate high actuating forces, can be dispensed with.

[0016] It is further proposed in an advantageous embodiment of the cooling circuit that the pressure source is an electromechanical pump, wherein the pump can be switched off and / or throttled by means of the control unit.

[0017] The advantage of an electromechanical pump is its fast response and the possibility of implementation with a uniform communication architecture. For example, such an electromechanical pump is wired so that it only delivers full power or is shut down. The electromechanical pump, for example, is mechanically pressure-controlled, meaning the pump's mechanical systems are designed for a specific power output within a narrow tolerance band. If the line pressure increases, the pump's pressure power output is intrinsically reduced.

[0018] In another embodiment, the pump can be throttled in a controlled manner, for example via an electrical power consumption and / or a speed detection.

[0019] It is further proposed in an advantageous embodiment of the cooling circuit that a throttle unit is provided in the circuit line upstream of the control valve, and the control unit reduces a line pressure in the circuit line when the control valve is actuated by means of the throttle unit.

[0020] A throttle slide, for example, is suitable as such a throttle unit, preferably with low power consumption, where any hydraulic influence is negligible. In one embodiment, a pressure-controlled pump is regulated down to a lower pressure output due to the resulting back pressure. Alternatively, the line pressure at the pressure source, for example, a connection to a pressure system, remains constant. Only the pressure downstream of the throttle unit, i.e., at the control valve, is reduced.

[0021] According to a further aspect, a control method for controlling a pressure source of a cooling circuit according to an embodiment as described above is proposed, the control method comprising the following steps: a. the control unit receives a control signal for the control valve; b. in response to the control signal, the control unit switches off the switchable pressure source and / or reduces the line pressure provided by the pressure source and effective at the control valve; c. the control unit receives an end signal for the control valve and d. upon the end signal, the control unit switches the switchable pressure source back on and / or the control unit cancels the reduction in the line pressure provided by the pressure source and effective at the control valve.

[0022] The control signal is, for example, an electrical voltage change, a digitized command, or a power current, which is recorded, processed or unprocessed, by the control unit as a signal for the control valve. In one embodiment, it is irrelevant whether the control valve is intended to enable a larger or smaller coolant flow, because the only relevant factor is whether the actuator subject to the hydraulic forces needs to be moved. This is assumed when a control signal is output. However, the control signal can also be recorded indirectly through measured variables, for example, as described above, by the control unit for the pressure source.

[0023] Conversely, the end signal is a signal or measured value from which it can be concluded that the actuator of the control valve is no longer moving or no longer needs to be moved. For example, a zero voltage, negligible power consumption, or a corresponding digitalized command.

[0024] For the process of reducing the line pressure applied to the control valve or its actuator, reference is made to the previous description.

[0025] It is further proposed in an advantageous embodiment of the control method that the position of the control valve can be changed within a few tenths of a second.

[0026] Due to the very short shutdown period of the pressure source during a control process, the resulting pressure fluctuations in the cooling circuit are not considered critical. Rather, during this short period, there is only a pressure decrease, which remains virtually ineffective due to inertia in the system. Therefore, it is not necessary to implement measuring systems and control loops designed to monitor a pressure reduction.

[0027] It is further proposed in an advantageous embodiment of the control method that during the shutdown and / or reduction of the line pressure in step b. in the circuit line, the line pressure is monitored, wherein the line pressure is monitored, preferably at an inlet of the pressure source, and is kept at a minimum pressure by appropriate control, preferably by means of the control unit, wherein the minimum pressure preferably deviates at most by a predetermined deviation from a target pressure in the circuit line, wherein the predetermined deviation corresponds to a pressure tolerance.

[0028] This embodiment creates a safety system by monitoring the line pressure. A critical pressure drop is thus reliably avoided. For example, if the pressure falls below a predetermined limit below the target pressure, the pressure source is switched on again, or the line pressure reduction is canceled. After a predetermined grace period, if necessary, the actuator is then activated again, and the pressure source is switched off accordingly, or the line pressure is reduced. Alternatively, the line pressure is maintained at a predetermined minimum pressure by alternately switching the pressure source on and off, or by correspondingly alternating throttling in the manner of pulse width modulation.

[0029] According to a further aspect, a thermal management system for a motor vehicle is proposed, preferably for an internal combustion engine, comprising the following components: - a cooling circuit according to an embodiment as described above for conducting a cooling liquid, wherein the cooling circuit is preferably configured for a control method according to an embodiment as described above; - a heat dissipation interface for a heat sink, wherein the heat sink is preferably a cooler and - a heat absorption interface for a heat source, wherein one of the heat sources is preferably a combustion chamber of an internal combustion engine, wherein a volume flow of the cooling liquid in the cooling circuit can be changed by means of the control valve.

[0030] The thermal management system proposed here is designed to dissipate heat from a heat source, for example, a motor vehicle's internal combustion engine, and to supply a cooling fluid with a suitable temperature and thus heat capacity to the heat source using a heat sink. For this purpose, the thermal management system has a cooling circuit, which can be operated, for example, with map-controlled operation.

[0031] The thermal management system has a heat absorption interface for a heat source, for example, a heat exchanger with a plurality of cooling fins or a connection to a heat exchange device, and a heat dissipation interface, for example, also a heat exchanger with a plurality of cooling fins or a connection to a heat exchange device, for a heat sink. The heat sink is, for example, airflow in conjunction with a radiator of a motor vehicle, wherein the radiator additionally includes, for example, a fan for stationary operation (no airflow).

[0032] The control valve or associated actuator is designed to regulate the cooling circuit, ensuring a quick, low-power, and reliable change in the cooling state by effectively reducing the pressure across the control valve. At the same time, the control valve or actuator requires little space and is a cost-effective component.

[0033] One control position, for example, is a (fully) open or (fully) closed flow, for example of the entire cooling circuit or an additional circuit. Another control position is the throttling of one or more flow rates. Furthermore, the inflow from or outflow into an additional circuit, i.e., the branching off of a partial flow or the supply of a partial flow, can be controlled using the control valve. The control valve can therefore be used to change the volume flow of the coolant and / or switchably supply a coolant to the heat dissipation interface and / or the heat absorption interface. The temperature control can thus be influenced using the control valve.

[0034] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, whereby it should be noted that the drawings are not to scale and are not suitable for defining proportions. It is shown in Fig. 1: a thermal management system in a motor vehicle and Fig. 2: a flowchart of a control procedure.

[0035] In Fig. 1 shows a section of a motor vehicle 9 in which a heat management system 2, comprising a cooling circuit 1 for the internal combustion engine 10, is shown in the engine compartment, i.e. where the internal combustion engine 10 is located. The cooling circuit 1 connects, by means of a main circuit 16 of the circuit line 3, a first heat absorption interface 13, here at the internal combustion engine 10, which thus represents a heat source 15, and a heat dissipation interface 11, which uses, for example, (airborne) wind, which represents a heat sink 12, to dissipate heat. The cooling circuit 1 further connects, by means of a secondary circuit 17 of the circuit line 3, a second heat absorption interface 14, here at the vehicle interior 18 of the motor vehicle 9, and the heat dissipation interface 11. The coolant in the cooling circuit 1 is pumped by the pressure source 4, for example a coolant pump.Here, a control valve 5 is shown in a first switching state, with only the main circuit 16 receiving flow. By moving the switching symbol upwards in the illustration, the inflow to the secondary circuit 17 is opened in the second switching state, so that both the circuit line 3 of the main circuit 16 and the secondary circuit 17 receive flow.

[0036] In Fig. 2 shows a flow chart of a control method according to the above description. The reference numerals refer to the illustration in Fig. 1. In step a., the control unit 6 receives a control signal for the control valve 5, i.e., for example, that the secondary circuit 17 is to be supplied with flow and, for this purpose, the control valve 5 must be actuated accordingly. In step b.1, in response to this control signal, the control unit 6 switches off the switchable pressure source 4. Alternatively or additionally, a throttle unit 7 is actuated to reduce the line pressure at the control valve 5. Thus, the line pressure provided by the pressure source 4 and present at the control valve 5 is reduced. In step b.2, the control valve 5 is actuated simultaneously or shortly thereafter and moved to the new position. In step c., the control unit 6 receives an end signal from or for the control valve 5, i.e., for example, that the desired position has been reached, in the example according to Fig.1 both the main circuit 16 and the secondary circuit 17 of the circuit line 3 are supplied with coolant. Alternatively, the end signal is triggered by a pressure measurement, for example at an inlet 8 of the pressure source 4, which has detected an exceedance of a pressure difference (Δp). Then, in step d.1, the control unit 6 switches the switchable pressure source 4 back on and / or the control unit 6 cancels the throttling by means of the throttling unit 7. This cancels the reduction in the line pressure provided by the pressure source 4 and applied to the control valve 5. In step d.2, at the same time, shortly before or shortly after, the control valve 5 is actuated such that it remains in the current position, for example by means of a locking device and / or an inhibition.

[0037] The control valve of the cooling circuit proposed here can be operated with a cost-effective and small actuator. List of reference symbols 1 cooling circuit 2 Thermal management system 3 District management 4 Pressure source 5 Control valve 6 Control unit 7 Throttle unit 8 Input of the pressure source 9 Motor vehicle 10 Internal combustion engine 11 Heat dissipation interface 12 heat sink 13 first heat absorption interface 14 second heat absorption interface 15 Heat source 16 Main Circle 17 subsidiary circuit 18 Vehicle interior

Claims

[1] Cooling circuit (1) arranged for a thermal management system (2), comprising the following components: - a circuit line (3); - a switchable pressure source (4); - an adjustable control valve (5) for controlling a cooling liquid flow in the circuit line (3) and - a control unit (6) for controlling the pressure source (4), characterized by that the control unit (6) is communicatively connected to the control valve (5), so that when the control valve (5) is adjusted, the pressure source (4) is switched off by means of the control unit (6) and / or a line pressure in the circuit line (3) is reduced. [2] Cooling circuit (1) according to claim 1, wherein the pressure source (4) is an electromechanical pump which can be switched off and / or throttled by means of the control unit (6). [3] Cooling circuit (1) according to claim 1 or 2, wherein a throttle unit (7) is provided in the circuit line (3) upstream of the control valve (5) and the control unit (6) reduces a line pressure in the circuit line (3) when the control valve (5) is actuated by means of the throttle unit (7). [4] Control method for controlling a pressure source (4) of a cooling circuit (1) according to one of the preceding claims, wherein the control method comprises the following steps: a. the control unit (6) receives a control signal for the control valve (5); b. in response to the control signal, the control unit (6) switches off the switchable pressure source (4) and / or the control unit (6) reduces the line pressure provided by the pressure source (4) and effective at the control valve (5); c. the control unit (6) receives an end signal for the control valve (5) and d. in response to the end signal, the control unit (6) switches the switchable pressure source (4) back on and / or the control unit (6) cancels the reduction in the line pressure provided by the pressure source (4) and effective at the control valve (5). [5] Control method according to claim 4, wherein the position of the control valve (5) can be changed within a few tenths of a second. [6] Control method according to claim 4 or 5, wherein during the shutdown and / or reduction of the line pressure in step b. in the circuit line (3), the line pressure is monitored and maintained at a minimum pressure by appropriate control by means of the control unit (6), wherein the minimum pressure deviates from a target pressure in the circuit line (3) by a maximum of a predetermined deviation, wherein the predetermined deviation corresponds to a pressure tolerance. [7] Thermal management system (2) for a motor vehicle (9), comprising the following components: - a cooling circuit (1) according to one of claims 1 to 3 for carrying a cooling liquid; - a heat dissipation interface (11) for a heat sink (12), and - a heat absorption interface (13, 14) for a heat source (15), wherein a volume flow of the cooling liquid in the cooling circuit (1) can be changed by means of the control valve (5).

Images