Method for temperature control of a control unit

Abstract

Method for temperature control of a control unit in a vehicle, in which the control unit is actively cooled with a cooling circuit, wherein, when a request to activate the cooling circuit exists, at least one measured variable is used first, and depending on the at least one measured variable, the cooling circuit is activated.

Description

The invention relates to a method for tempering a control unit in a vehicle, in particular a motor vehicle, and to an arrangement for carrying out the method. The method serves in particular to prevent condensation within the control unit.Prior ArtIn control units used in vehicles, it must be ensured that these function reliably at any time of year and at different climatic conditions. This presents a challenge in particular in moist warm areas, since in these, on the one hand, cooling of at least some of the components is required and, on the other hand, condensation of the surface of the components should be avoided.By "betumen" is meant a precipitation and accumulation of moisture on a surface, this is also referred to as wetting or covering with dew. Tau in turn is water condensed by temperature differences.A beta can lead to an undesired influence on the electrical conductivity on the beta surfaces.In the field of advanced driver assistance systems (ADAS), the use of water cooling in the electronic control units (ECU) used is regularly required in order to meet the requirements for the performance of the system. This means that cooling circuits must be taken into account in the mechanical design of the control unit, which circuits make it possible to cool the so-called hot spots, i.e. the components with high power loss, as well as to ensure functionality over the lifetime in the best possible manner.The document EP 2 863 155 A1 describes a heat pump having a compressor and an electric motor connected to the compressor, which in turn is connected to a power output stage. Furthermore, the heat pump has a temperature sensor which is arranged to detect a temperature of the power output stage. Furthermore, a control unit is provided which actuates the power output stage as a function of a temperature signal which represents the detected temperature in such a way that waste heat can be generated in the power output stage by means of a waste current flowing through the power output stage.The document DE 10 2020 214 861 A1 describes a method for preventing condensation within an electronic device. In the method, a temperature inside and a temperature outside a housing of the device are detected. A difference is determined from this. Depending on this difference, a heater is operated.The document DE 10 2013 225 450 B3 describes a method for preventing condensation of a power output stage of a heat pump, in which a temperature of the power output stage is detected and a refrigerant flow at the power output stage is controlled as a function of the detected temperature.Disclosure of the InventionAgainst this background, a method having the features of claim 1 and an arrangement according to claim 10 are presented. Embodiments will be apparent from the dependent claims and from the description.The method presented serves for the temperature control of a control unit in a vehicle, in particular in a motor vehicle. In this case, a cooling circuit is provided, with which the control device can be actively cooled. If, for example, at the start of the vehicle, there is a request for activating the cooling circuit and thus for cooling the control unit, at least one measured variable is first used. As a function of this at least one measured variable, the cooling circuit is then activated. This at least one measurement variable can be measured or detected or already present when the request is present. If a plurality of measured variables are used, at least one of these can already be present and at least one of these can first be detected for the request.In one specific embodiment, it is provided that, as a function of the at least one measured variable, a trigger time is determined at which the cooling circuit is to be activated. At this trigger time, the cooling circuit is then activated and the control device is cooled. In this embodiment, it can then be checked once again at the trigger time whether suitable conditions are actually present. The trigger time is thus verified. If it turns out that suitable conditions are not yet present, for example due to influence of interference variables, then no activation of the cooling circuit takes place.It is also possible to record measured variables continuously or at time intervals and then, if suitable conditions are present, to activate or deactivate the cooling circuit.Suitable conditions are conditions, for example characterized by temperature(s) and / or, in particular, relative humidity(s), which allow the cooling to be activated without condensation occurring.By taking into account a targeted and regulated switching on of the cooling circuit, the risk of condensation within a control unit can be reduced and field failures can thus be prevented.Since the short time events of the condensation for which a coating is designed no longer occur, the need to provide a so-called conformal coating on the printed circuit board is thus no longer present in many cases. As a result, this measure is less frequently used, so that the costs during development can be reduced. Furthermore, it is possible to define the guided start from a temperature standpoint in such a way that potential temperature swings are likewise reduced therewith. This in turn has a positive effect on the service life of the solder joints. Conformal coating is understood to mean a protective coating which can be applied to a printed circuit board. This coating protects the printed circuit board from various environmental influences, such as, for example. Humidity, moisture and impurities.In addition, the defined start of the cooling circuit presented can be extended to further products in the cooling circuit of the vehicle or a system strategy can be defined therefrom, which can be offered in a packet with the control device.In other words, an "when-then formula" is implemented within software for starting / stopping water cooling. This trigger can be set over a defined period of time, for example xx seconds, or over a limit of the relative humidity or temperature, which is established, for example, via additional humidity sensors on the printed circuit board or the internal temperature sensors of the components.An example is outlined below:A vehicle parks in a cold / moist environment, for example. 10° C. and 90% RH (relative humidity), with the assumption that the condition is also present in the vehicle and in the control device. The car is started and with a delay of, for example. 30 s, wherein the exact time specification can be defined on the basis of measurement results, or if the internal temperature sensors have a defined average value which is dependent on the components or the self-heating stroke, the cooling is activated.Here, it also holds true that the value of the delay is defined on the basis of the measurements.As a result, the temperature of the internal air rises or becomes warmer more quickly and is thus able to absorb the moisture from the printed circuit boards. In addition, colder regions of the printed circuit board also become warmer and the micro climates within the control unit are reduced.In this way, the risk of condensation or condensation within the control unit during the starting process is reduced, because these "overshoots" occur during each starting process and are thus avoided. Furthermore, no use of a conformal coating is required. This results in a cost saving. Likewise, this process may be performed during a continuous operation. That is, should a defined relative humidity limit be exceeded during the active operation, cooling is stopped for xx seconds. The exact time specification is defined on the basis of measurement results.If there is an entire cooling circuit for the vehicle, i.e. the control unit is seated in the same cooling circuit as the battery or the electric drive, the control unit requires a "by-pass", i.e. a separate cooling circuit is required. The cooling water can be controlled via this or via the valve control.The arrangement presented serves for carrying out the method and comprises an evaluation unit for this purpose. The arrangement and / or the evaluation unit can be implemented in hardware and / or software and integrated in a control device or designed as such.Further advantages and embodiments of the invention will become apparent from the description and the appended drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.Brief Description of the DrawingsFIG. 1 shows signal curves in two graphs. FIG. 2 shows a schematic illustration of a printed circuit board for carrying out the presented method in two views. FIG. 3 shows a block diagram of an embodiment of a cooling circuit for carrying out the method presented. FIG. 4 shows a flow chart of a possible sequence of the described method. FIG. 5 shows a greatly simplified, purely schematic illustration of a vehicle having an arrangement for carrying out an embodiment of the described method.Embodiments of the InventionThe invention is schematically illustrated in the drawings on the basis of embodiments and is described in detail below with reference to the drawings.FIG. 1 shows different curves of measured variables in two graphs. In a first graph 10, on whose abscissa 12 the time and on whose ordinate 14 the relative humidity and temperature are plotted, several curves of the air humidity are plotted at different points.In a second graph 30, on whose abscissa 32 the time and on whose ordinate 34 the relative air humidity is plotted, different temperature profiles are plotted at different points. A marked region 40 illustrates a jump in the relative humidity caused by a delayed heating of the surrounding air within the control unit, influenced by the water cooling which is switched on in parallel with the power loss. This is also referred to as overshoot. A curve 42 shows the temperature curve of a measurement point in this enlarged region.FIG. 2 shows in two views a printed circuit board for carrying out the method, which is denoted overall by the reference numeral 100. The circuit board 100 is shown at the top in a plan view. The illustration below shows the printed circuit board 100 in a side view.The illustration further shows moisture sensors 102, a SoC 104 (system on chip) representing the hotspot, a region 106 comprising a thermally conductive material (TIM: thermal interface material), a valve 108 and cooling water 110.FIG. 3 shows a block diagram of a cooling circuit, which is denoted overall by the reference numeral 150. The illustration shows a water-cooled control unit 152, a first valve 154, which is triggered by the control unit 152 or moisture sensors and switches a bypass 155, an electric machine 156, a cooler 158, a DC-DC converter 160, a battery 162, a heat exchanger 164, a high-voltage (HV) heating device 166 and a second valve 168.FIG. 4 shows a possible embodiment of the presented method in a flow chart. In a first step 200, the operation of a motor vehicle starts. With the start, a request is made for the activation of a cooling circuit. In this cooling circuit, a bypass ensures that a control device can be cooled via a separate cooling circuit.In a step 202, measured variables are then detected, in this case a temperature and a relative air humidity, typically at a measurement point (coldspot) within the control unit. Based on the measured variables detected, in a step 204 a trigger time for activating the bypass (reference numeral 155 in FIG. 3 ) and thus a time from which the cooling of the control unit is to take place is calculated or determined.In a step 206, the separate cooling circuit is then activated at the specific trigger time, for example by actuating a valve. From this point in time, a brief interruption (xx seconds) of the cooling of the control unit takes place. At this time, conditions prevail in the region of the control unit in which a condensation is prevented.In principle, it is also possible, if a requirement for cooling is present, to record measured variables continuously or at time intervals until a state is detected which indicates that there is no risk for a condensation when the cooling is activated.Alternatively, as soon as the request is present, a trigger time can first be determined and then checked again at this time before the activation of the cooling circuit, typically on the basis of at least one measured variable, whether suitable conditions are actually present.FIG. 5 shows, in purely schematic form, a vehicle which is denoted overall by the reference numeral 300. This vehicle 300 comprises an arrangement 302 for carrying out the method, which in turn has an evaluation unit 304. The illustration also shows a control unit 306 which is connected to a cooling circuit 308.Furthermore, sensors 310 are shown which measure variables, for example. Provide temperatures 312 and humidity values 314.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 2 863 155 A1

[0006] DE 10 2020 214 861 A1

[0007] DE 10 2013 225 450 B3

[0008]

Claims

Method for tempering a control unit (152, 306) in a vehicle (300), in which the control unit (152, 306) is actively cooled by a cooling circuit (150, 308), wherein, if there is a request for activating the cooling circuit (150, 308), at least one measurement variable is first used, and the cooling circuit (150, 308) is activated as a function of the at least one measurement variable.Method according to Claim 1, in which a trigger time at which the cooling circuit (150, 308) has to be activated is determined as a function of the at least one measurement variable, and the cooling circuit (150, 308) is activated at the determined trigger time.Method according to Claim 1 or 2, in which a temperature (312) is detected as a measurement variable.Method according to Claim 3, in which an absolute temperature is detected as a measurement variable.Method according to Claim 3, in which a temperature difference is detected as a measurement variable.Method according to one of Claims 1 to 5, in which a relative air humidity (314) is detected as a measurement variable.Method according to one of Claims 1 to 6, which brings about a time delay in the cooling of the control unit (152, 306).The method according to any one of claims 1 to 7, performed at the start of the vehicle (300).Method according to one of Claims 1 to 8, in which the control unit (152, 306) is cooled via a separate cooling circuit.Arrangement for tempering a control unit (152, 306) in a vehicle (300), having an evaluation unit (304) which is configured to carry out a method according to one of Claims 1 to 9.Arrangement according to Claim 10, to which at least one measuring device for ascertaining a measurement variable is assigned.

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