Operation of an air conditioning system and motor vehicle

Abstract

Method for operating an air conditioning system (1) of a motor vehicle (2), comprising a ventilation system (3) for generating at least one airflow (4) in the vehicle interior (5) and at least one temperature control system (6) for temperature-controlling the airflow (4), wherein during operation of the air conditioning system (1) it is checked whether a trigger condition (7) is met, the fulfillment of which depends on a predicted remaining driving time (8) until reaching a predetermined driving destination (9) of the motor vehicle (2), wherein if the trigger condition (7) is met the temperature control system (6) is switched off, wherein at least at one time (10) after the trigger condition (7) has been met and before reaching the driving destination (9) the ventilation rate (11) of the ventilation system (3) is increased compared to the ventilation rate (11) used at the time (12) of the trigger condition (7) being met,to increase the air velocity of the airflow (4) in the area of ​​at least one vehicle occupant (13) in the vehicle interior (5).

Description

[0001] The invention relates to a method for operating an air conditioning system of a motor vehicle, comprising a ventilation device for generating at least one airflow in the vehicle interior and at least one temperature control device for temperature-regulating the airflow, wherein, during operation of the air conditioning system, it is checked whether a trigger condition is met, the fulfillment of which depends on a predicted remaining driving time until the vehicle reaches a predetermined destination, and wherein, upon fulfillment of the trigger condition, the temperature control device is switched off. The invention also relates to a motor vehicle.

[0002] The switching off or reducing the power output of air conditioning systems in motor vehicles in the vicinity of a possible driving destination or before reaching a planned driving destination for efficiency reasons is known from documents DE 10 2011 120 868 A1 and US 2016 / 0325600 A1.

[0003] When the vehicle's air conditioning system is deactivated in operating conditions where the outside temperature is significantly higher than the interior temperature and / or there is strong sunlight, the temperature inside the vehicle initially rises relatively quickly. As the interior temperature gradually approaches the outside temperature, the temperature increase inside the vehicle then slows down.

[0004] For example, if the vehicle's air conditioning is deactivated when the outside temperature is 30°C and the interior is set to 20°C, the interior temperature can potentially reach 24°C in less than two minutes. Since many users consider a temperature increase of more than 4°C unacceptable, the air conditioning can only be deactivated shortly before the target temperature is reached, as otherwise the automatic deactivation is likely to be rejected and the function switched off. Therefore, the energy-saving potential of such an efficiency function is currently rather low, at least at high outside temperatures.

[0005] The invention is therefore based on the objective of further increasing the efficiency of the operation of an air conditioning system in a motor vehicle.

[0006] The object is achieved according to the invention by a method of the type mentioned at the outset, wherein at least at one time after the fulfillment of the triggering condition and before reaching the destination, the ventilation strength of the ventilation device is increased compared to the ventilation strength used at the time the triggering condition was fulfilled, in order to increase the air velocity of the airflow in the area of ​​at least one vehicle occupant in the vehicle interior.

[0007] For example, the ventilation level can be increased to a new, higher value at a single point in time after the trigger condition is met and before the destination is reached, or over a short time interval, and this higher value can then be maintained, particularly until the destination is reached. Alternatively, the increase in ventilation level can also occur continuously or quasi-continuously at several such points in time, or over a longer sub-interval of the time interval between the trigger condition being met and the destination being reached, and thus at a multitude of points in time.

[0008] By increasing the ventilation intensity according to the invention during part of the time interval between the fulfillment of the trigger condition and reaching the destination, and thus in particular while the temperature control device is switched off, the fact that an airflow in the area of ​​the vehicle occupant leads to a reduction in the temperature perceived by that occupant is exploited. Thus, a noticeably greater increase in the interior temperature can be permitted without being unacceptable to the user, since the user does not perceive the full extent of the temperature increase due to the increased air velocity of the airflow.

[0009] As will be explained in more detail later, the point at which the ventilation intensity is increased, or rather, when an increase in ventilation intensity begins, can be significantly delayed, for example by at least 10 seconds, at least 20 seconds, or at least one minute, from the moment the triggering condition is met. This allows the temperature inside the vehicle to rise slightly before the perceived temperature is reduced by the increased airflow speed. In particular, this ensures that the temperature perceived by the occupant does not fall below the temperature perceived at the moment the triggering condition is met, meaning the occupant perceives no, or at least no noticeable, cooling.

[0010] For example, tests have shown that airflow speeds of up to 10 km / h are acceptable for almost all users. Such an airflow reduces the perceived temperature by approximately 4°C, so in the example mentioned at the beginning, it is permissible for the indoor temperature to rise by 8°C, or to 28°C, before the temperature increase becomes unacceptable for typical users.

[0011] However, since the interior temperature rises increasingly slowly as the difference to the outside temperature decreases, the increase in interior temperature from 20°C to 28°C in the example above can, depending on the specific conditions, take three to six times longer than the increase from 20°C to 24°C. Therefore, the increase in ventilation intensity according to the invention makes it possible to deactivate the temperature control device significantly earlier before reaching the destination, for example, 6 minutes before reaching the destination, thus achieving considerably greater energy savings, especially since many typical journeys last 15-20 minutes and the typically energy-intensive operation of the temperature control device can therefore be dispensed with for a significant portion of the journey time.

[0012] While the approaches described above completely deactivate or reduce the performance of the air conditioning systems, the method according to the invention allows the power supplied to the ventilation system to be increased in order to increase the air velocity of the airflow in the area of ​​at least one vehicle occupant in the vehicle interior. Since the operation of the temperature control unit in air conditioning systems is generally considerably more energy-intensive than the operation of the ventilation system, the method according to the invention can achieve a significant overall energy saving.

[0013] The inventive method is particularly relevant for purely electrically powered motor vehicles. Depending on the model and design, the average electricity consumption per 100 km of driving distance for these vehicles typically ranges between 12 kWh and 30 kWh, according to manufacturer specifications. Most consumption calculations are performed using 15 kWh per 100 km. If, for example, an average speed of 60 km / h is achieved, the drive system requires an average of 15 kW of power.

[0014] An air conditioning system typically operates at full capacity briefly at the start of a journey to reach the desired set temperature. A modern air conditioning system requires more than 10 kW of power at full capacity. According to current research and development, a minimum of 1.5 kW is required to maintain the temperature, for example, to keep the vehicle at 20°C. Under the specified conditions, it can therefore be assumed that at least 10% of the vehicle's energy consumption is caused by the air conditioning system during typical driving. The power consumption of the ventilation system is typically negligible compared to the power consumption of the temperature control system.

[0015] A typical car journey in Germany lasts approximately 15 minutes. As explained above, the inventive method allows, for example, the climate control system to be switched off approximately 6 minutes before reaching the destination, without noticeably reducing passenger comfort. Thus, the climate control system only needs to operate for approximately 60% of the journey time, reducing the vehicle's energy consumption in this example by approximately 40% of the energy consumption of the climate control system, and therefore by a total of approximately 4%. With the same battery capacity and otherwise identical operating conditions, this results in an approximately 4% increase in range.

[0016] However, the inventive method is also suitable for motor vehicles with internal combustion engines, since a reduction in fuel consumption and thus a reduction in CO2 emissions can also be achieved there.

[0017] The airflow can result, at least primarily, from the recirculation of air within the vehicle by the ventilation system. However, fresh air drawn in from the outside can also be added, or only such fresh air can be used to generate the airflow, whereby fresh air can be drawn in, for example, via at least one heat exchanger and / or dehumidifier in order to minimize the introduction of heat or moisture into the vehicle interior.

[0018] The prediction of the remaining travel time can be made depending on the specified destination, the actual position of the vehicle determined in particular by means of a position sensor, for example by means of GPS, and an average and / or current and / or predicted driving speed for the further journey to the destination or a predicted driving speed profile.

[0019] The destination can be set manually, for example using a navigation system. However, it is also possible to automatically select or predict a destination that the vehicle is likely to travel to, for example based on known previous user behavior and the current position of the vehicle.

[0020] The fulfillment of the trigger condition can depend on a predetermined target ventilation level, wherein the ventilation level is increased to the target ventilation level at at least one point in time within a time interval between the fulfillment of the trigger condition and the achievement of the travel destination, and / or wherein, within this time interval, the ventilation level exceeds the predetermined target ventilation level by a maximum of 20% or a maximum of 10% of the target ventilation level.

[0021] As the ventilation intensity increases, and thus the airflow velocity in the area of ​​the vehicle occupants increases, the temperature perceived by the occupants is further reduced at a given interior temperature, as discussed above. This allows for a higher interior temperature upon reaching the destination. The higher the target ventilation intensity, the earlier the ventilation system can be deactivated, or rather, the longer the predicted remaining travel time.

[0022] The maximum airflow velocity achievable by the ventilation system in the passenger compartment is often perceived as unpleasant or disturbing by the occupants, making it advisable to limit the ventilation rate. However, since increasingly limited ventilation rates necessitate later deactivation of the temperature control system if the user-perceived temperature is to be maintained within the desired range, it is therefore advisable to consider this limitation by setting the target ventilation rate as part of the activation condition.

[0023] The aforementioned exceedances of the target ventilation level by a maximum ventilation level of 20% or 10% can result, in particular, from control deviations. Preferably, the ventilation level is controlled or regulated in such a way that, from a certain point onward, it is maintained at least approximately at the target ventilation level until the destination is reached.

[0024] The target ventilation rate can be fixed, for example, by the vehicle manufacturer. In particular, the target ventilation rate can be specified in such a way that a predetermined airflow velocity, for example, a flow velocity of 10 km / h, results at a reference position in the vehicle interior. The reference position can, for example, correspond to the seating position of a driver or another vehicle occupant.

[0025] Preferably, the target ventilation level should be user-adjustable. For example, the setting can be adjusted via a vehicle control panel, a smartphone, or a portal provided by the vehicle manufacturer. The target ventilation level can also be adjusted indirectly, for example, by selecting a driving mode, such as Eco or Comfort mode.

[0026] The airflow velocity at a specific location within the vehicle, such as the driver's head area, can be used directly as the ventilation rate or target ventilation rate. However, to simplify the control of the ventilation system and the evaluation of the triggering condition, it can be advantageous to use a control variable of the ventilation system as the ventilation rate or target ventilation rate. This variable could be, for example, the rotational speed of a fan or the current or power supplied to the ventilation system or at least one component thereof. In general, any quantity that is expected to have a monotonic relationship to the airflow velocity at a given reference position in the vehicle interior can be used as the ventilation rate or target ventilation rate.

[0027] The ventilation rate may deviate from the target ventilation rate by a maximum of 20% or 10% over a partial interval of the time interval between the fulfillment of the trigger condition and reaching the destination, wherein the partial interval includes, in particular, the time of reaching the destination. The partial interval may comprise at least 30%, at least 50%, or at least 70% of this time interval.

[0028] Alternatively, it would be possible, for example, to dynamically regulate the ventilation level depending on a measured or estimated interior temperature, for instance, to keep the temperature perceived by the occupants as constant as possible, at least for part of the time interval. In this case, the ventilation level can be limited, in particular, by the target ventilation level, or, as explained above, only an exceedance of the target ventilation level by a maximum of 10% or 20% can be permitted, for example, due to overshoot of the temperature control.

[0029] It is possible that the ventilation level will only be increased at or from a point in time after the time the trigger condition is fulfilled, at which a predetermined temperature limit is exceeded by a determined or predicted interior temperature value relating to the interior temperature in the vehicle interior.

[0030] A delayed increase in ventilation intensity compared to when the triggering condition is met is particularly useful when the ventilation intensity is increased rapidly, for example, in stages. If such an increase were to occur immediately upon or after the triggering condition is met, the temperature perceived by the occupant would initially drop below the temperature perceived at the time of triggering due to the higher ventilation intensity. This can be avoided by first allowing a certain rise in the interior temperature before the perceived temperature is lowered by a stronger airflow.

[0031] The interior temperature can be determined using at least one temperature sensor. Such a temperature sensor is typically already present in an air conditioning system. In principle, however, it is also possible to predict the future temperature profile inside the vehicle at the time of activation, meaning that a predicted interior temperature value can be available or determined for any point in time after the activation.

[0032] The trigger condition is preferably fulfilled or can only be fulfilled if - on the one hand, a predicted warm-up time corresponds to or exceeds the predicted remaining driving time, wherein the predicted warm-up time indicates how long after the fulfillment of the trigger condition a limit point is expected to be reached at which a predicted interior temperature value, relating to an interior temperature in the vehicle interior at the limit point, reaches or exceeds a predetermined maximum temperature, and / or - on the other hand, a predicted interior temperature value, which relates to an interior temperature in the vehicle interior for the end of the predicted remaining driving time and thus for reaching the destination, is less than or equal to the maximum temperature.

[0033] In particular, based on the vehicle's operating parameters discussed below, a temporal temperature profile of the interior temperature can be predicted, which is expected to trigger the shutdown of the temperature control system at the time the trigger condition is evaluated. This temperature profile can then be used to verify the aforementioned conditions.

[0034] If, for example, an analytical model of the temperature profile is used—that is, a closed-form formula or a functional relationship—parameterized by the operating parameters, then, in the case of the second condition mentioned, it is sufficient to determine the predicted interior temperature value for the time at the end of the predicted remaining driving time. By rearranging such an analytical model, or at least one equation describing this model, the same model can also be used to calculate the predicted warm-up time.

[0035] However, it is also possible, for example, to calculate predicted indoor temperature values ​​for several, especially uniformly complained, time intervals from the time of evaluation of the trigger condition and to check from which time interval these predicted indoor temperature values ​​exceed the maximum temperature in order to determine the warm-up time.

[0036] The predicted warm-up time and / or the predicted indoor temperature value can be determined depending on an actual indoor temperature value, which describes the indoor temperature at the time the trigger condition is met, and / or a predetermined target indoor temperature, to which the indoor temperature is regulated before the trigger condition is met, and / or an outdoor temperature value, which relates to an outdoor temperature outside the vehicle, and / or sensor data from a light sensor and / or a cooling capacity required to maintain the indoor temperature at the target indoor temperature.

[0037] In particular, depending on the aforementioned parameters, a temperature change curve can be determined that describes the predicted time-dependent temperature profile of the predicted indoor temperature value after the temperature control device has been switched off.

[0038] The current indoor temperature or the target indoor temperature can be used as the initial value for the temperature change curve. This approach takes advantage of the fact that, after a sufficient operating time of the air conditioning system, the target indoor temperature typically corresponds at least approximately to the actual indoor temperature.

[0039] The difference between the outside temperature and the actual inside temperature, or the target inside temperature, describes the temperature gradient between the outside and inside. This gradient allows for the estimation of heat transfer per unit of time and thus the temperature change over time within the vehicle interior. The relationship used for this purpose can be determined empirically, for example, through reference measurements on the same vehicle or on a similarly constructed vehicle, such as a reference vehicle of the same type. Alternatively, it could be derived based on a known geometry of the vehicle and the material properties of its components.

[0040] The sensor data from the light sensor can be used to take into account additional heating of the vehicle interior due to direct sunlight.

[0041] A humidity value relating to the humidity in the vehicle interior can be determined, whereby the fulfillment of the trigger condition may additionally depend on the humidity value and / or whereby the temperature control device can be reactivated if, after the temperature control device has been switched off, a reactivation condition evaluating the humidity value is fulfilled.

[0042] In many air conditioning systems, the operation of the temperature control unit dries the recirculated air or the air drawn in from the vehicle's surroundings. When the temperature control unit is deactivated, the humidity inside the vehicle can therefore rise sharply in certain operating situations, for example, due to the influx of warm, humid air from outside and / or perspiration from vehicle occupants. High humidity inside the vehicle can, however, lead to mold growth after the vehicle is switched off or, after a temperature drop, to condensation freezing, for example, on vehicle windows. Therefore, it is advantageous to switch off the temperature control unit, or leave it switched off, only when the humidity inside the vehicle is not too high.

[0043] Additionally or alternatively, an automatic fatigue detection system can be used to determine the fatigue level of the vehicle occupant or at least one of the vehicle occupants, whereby the fulfillment of the trigger condition may additionally depend on the fatigue level and / or whereby the temperature control system can be reactivated if, after the temperature control system has been switched off, a reactivation condition evaluating the fatigue level is met.

[0044] In particular, the vehicle occupant for whom the fatigue level is being determined may be the driver. While the increase in interior temperature due to the climate control system being switched off before reaching the destination is unproblematic for a sufficiently alert driver, a potentially impaired concentration and reaction time in a tired driver can be exacerbated by the rising interior temperature. This problem can be avoided by implementing fatigue detection and taking the fatigue level into account as part of the trigger and reactivation conditions, as explained above.

[0045] The level of fatigue can, for example, differentiate between two stages: a sufficiently alert driver and a tired driver. If a tired driver is detected, a warning can be issued to the driver, in a manner already known, urging them to stop driving. Independently of this, or additionally, if a tired driver is detected, the trigger condition may not be met, or the reactivation condition may be met, in order to prevent an increase in the interior temperature.

[0046] Various approaches to assessing driver fatigue are known in the art and will therefore not be explained in detail. For example, it is possible to evaluate the frequency of steering movements, eye-closing times, pupil movements, or similar factors.

[0047] The predicted remaining travel time can be predicted depending on an identified occupant identity of the vehicle occupant or at least one of the vehicle occupants and / or a current time and / or a current date and / or a current traffic situation.

[0048] The accuracy of travel time prediction can be further improved by considering the aforementioned dependencies or parts thereof. These dependencies can be taken into account in addition to the vehicle's current position and the destination. Other input data, such as those used in travel time estimation in navigation systems, can also be considered. For example, map data can be used to define the characteristics of a route between the current position and the destination, as well as current weather conditions.

[0049] The current time and / or date can be read from a vehicle clock, for example, at the time the trigger condition is checked or slightly beforehand, or received wirelessly, such as as part of a radio signal. The time and / or date, especially the current day of the week, can be analyzed to estimate typical traffic volume on a planned or predicted route between the current position and the destination. This is possible, for example, using map data that specifies traffic data for individual route segments that varies depending on the time of day and day of the week.

[0050] Alternatively or additionally, the current traffic situation can be received wirelessly or retrieved from a server and / or estimated based on sensor data, for example, based on other vehicles detected in the vehicle's vicinity.

[0051] The occupant identity can be taken into account, particularly for the driver of the vehicle. Based on the occupant identity, individual driving behavior can be considered, such as the speed typically used by the driver in the current traffic situation.

[0052] As explained above, the inventive method can take into account a large number of different input data when determining the predicted remaining travel time. A relationship between the travel time and the various input data can be determined, for example, by statistical analysis of a large number of recorded reference data, for example, by means of regression analysis.

[0053] However, the predicted remaining travel time can be determined particularly favorably by an algorithm trained through machine learning. Specifically, supervised learning can be used, where each training dataset can include the actual travel time required to reach a given destination as the target result, as well as values ​​for the input data to be processed by the algorithm. The algorithm can then be trained, for example, in a known manner, by error feedback, such as a gradient descent method in the case of a differentiable algorithm.

[0054] The destination can be automatically selected from several possible destinations depending on the current position of the vehicle and / or the determined occupant identity of the vehicle occupant or at least one of the vehicle occupants and / or the current time and / or the current date.

[0055] The possible destinations can be derived from map data from a navigation system, for example. Based on the occupant's identity, a previous destination selection by the driver or another occupant can be taken into account. For instance, based on the current position, direction of travel, and optionally the day of the week or time of day, the destination can be estimated with good accuracy for most drivers. Destination determination can be very precise, for example, if known parking preferences of the occupant are also considered for the various destinations. The automatically selected destination can be updated several times during the journey. To achieve noticeable energy savings, it is sufficient if the actual destination is identified a few minutes before it is reached.

[0056] In addition to the method according to the invention, the invention relates to a motor vehicle with an air conditioning device comprising a ventilation device for generating at least one airflow in the vehicle interior and at least one temperature control device for temperature-controlling the airflow, and a control device for controlling the air conditioning device, wherein the control device is configured to carry out the method according to the invention.

[0057] The features described in relation to the method according to the invention can be transferred to the motor vehicle according to the invention, along with the advantages mentioned therein, and vice versa.

[0058] Further advantages and details of the invention will become apparent from the following exemplary embodiments and the accompanying drawings. These schematically illustrate: Fig. 1 an embodiment of the motor vehicle according to the invention, Fig. 2 a flowchart of an embodiment of the method according to the invention, and Fig. 3 an exemplary progression of an actual and a perceived indoor temperature in the procedure according to Fig. 2.

[0059] Fig. Figure 1 shows a motor vehicle 2 with an air conditioning system 1, which includes a ventilation system 3 for generating at least one airflow 4 in the vehicle interior 5 and at least one temperature control system 6, for example a compression refrigeration unit, for temperature-controlling the airflow 4. In the example, the ventilation system 3 is shown as a fan. However, the ventilation system 3 can additionally or alternatively include other components configured to determine the direction and speed of the airflow 4.

[0060] As shown schematically by arrows 36 and 37, air is drawn in from the vehicle environment or the interior 5 by the ventilation device 3, which is then tempered and optionally dried by the temperature control device 6 to provide the air for the airflow 4.

[0061] Frequently, the climate control system 1 is activated by the vehicle occupant 13 at the start of the journey or during operation, and the climate control system 1 is not explicitly switched off by the vehicle occupant 13, so that the climate control system is only deactivated when the vehicle is parked at the destination. However, as already explained in the general part of the application, significant energy savings can be achieved if the climate control system 6 is deactivated well before reaching the destination, whereby a high level of occupant comfort can be achieved by appropriately selecting the deactivation time and, in particular, by lowering the perceived temperature 44 through adjustment of the operation of the ventilation system 3.

[0062] Therefore, in the example, the air conditioning unit 1 is controlled by a control unit 35, which repeatedly checks during the operation of the air conditioning unit 1 whether a trigger condition 7 is met, the fulfillment of which depends on a predicted remaining travel time 8 until the vehicle 2 reaches a predetermined destination 9. If the trigger condition 7 is met, the control unit switches off the temperature control unit 6.

[0063] As already explained in the general part of the description, if the air conditioning system 1 were completely deactivated, the temperature 44 perceived by the occupant 13 would rise rapidly in many situations when the trigger condition is met, so that the trigger condition 7 would have to be chosen so that the shutdown only occurs shortly, for example less than a minute, before the expected arrival at the destination.

[0064] Therefore, in the motor vehicle 2, the ventilation device 3 continues to be operated even after the trigger condition has been fulfilled, whereby at at least one time 10 after the trigger condition 7 has been fulfilled and before the destination 9 has been reached, the ventilation strength 11 of the ventilation device 3 is increased compared to the ventilation strength 11 used at time 12 of the fulfillment of the trigger condition 7 in order to increase the air velocity of the airflow 4 in the area of ​​at least one vehicle occupant 13 in the vehicle interior 5.

[0065] In this example, the rotational speed of the fan used as ventilation device 3 is increased. However, it would also be possible, additionally or alternatively, to adjust flaps, baffles, or similar devices in the air path to increase the ventilation rate 11. Generally, selecting a higher ventilation rate 11 can be understood as any measure that increases the flow velocity of the airflow 4 in the area of ​​the vehicle occupant 13 or at a predetermined reference point 47 in the vehicle 2.

[0066] An exemplary embodiment of this procedure for operating the air conditioning unit 1, implemented by the control unit 35, will be described below with additional reference to the one in Fig. The flowchart shown in section 2 explains this. In addition to the core functionality explained above, the example shown uses additional process steps to achieve further advantages.

[0067] In step S1, several possible destinations 34 are initially specified, which are defined, for example, by map data 41. For example, any parking opportunity can initially be identified as a possible destination 34.

[0068] In step S2, information is collected that is suitable for predicting a likely current destination and / or a likely travel time to that destination. In alternative versions of the procedure, not all of the information collected in the example, as explained below, needs to be collected, or additional information can be taken into account.

[0069] An occupant's identity 29 of the vehicle occupant 13 can be determined, for example, using a camera 38 and facial recognition. Alternatively, a driver can be identified as a vehicle occupant 13, for example, using a personalized electronic vehicle key.

[0070] A current time 30 and a current date 31 can, for example, be provided by an internal vehicle clock that is not displayed, or received wirelessly, for example as part of a radio signal.

[0071] A current traffic situation 32 can, for example, be queried wirelessly from a server or received as part of a radio signal. Additionally or alternatively, sensor data from the vehicle's environmental sensors (not shown) can be evaluated to, for example, deduce the current traffic situation 32 based on the number of vehicles detected in the vehicle's vicinity and their driving behavior.

[0072] The actual position 33 of the motor vehicle 2 can be recorded, for example, via a GPS sensor 49.

[0073] In step S3, a likely destination 9 of the vehicle 2 is selected from the possible destinations 34. For example, the selection can be based on a statistical analysis of previous journeys of the vehicle occupant 13, identified by occupant identity 29. Such an analysis can reveal, for instance, which of the possible destinations 34 is typically visited by the vehicle occupant 13, particularly around the current time 30 and on the day of the week known from the current date 31, and with what probability. Additionally or alternatively, a calendar assigned to the vehicle occupant 13 can be considered. The destination with the highest probability of being visited can then be selected as the likely destination 9.Instead of a statistical evaluation of previous journeys, these could, for example, also be used to train an algorithm through machine learning to select the expected destination 9.

[0074] Since the selection of the anticipated destination 9, as will be explained in more detail later, only becomes relevant for the described procedure when this destination 9 is expected to be reached after a few minutes of remaining travel time, it is not a problem if an incorrect anticipated destination 9 is initially determined when the distance to the actual destination is relatively large. Therefore, for the described procedure, it is sufficient if the prediction of the anticipated destination 9 achieves good accuracy when the actual destination is already relatively close.

[0075] In a simplified version of the procedure shown, it would also be possible for the specified destination 9 to be explicitly specified by the occupant 13 or, for example, by a navigation system of the vehicle 2 which is not shown.

[0076] In step S4, a remaining travel time 8 until reaching the anticipated destination 9, as specified in step S3, is predicted. In a simple implementation of the procedure, the distance from the current position 33 to the specified destination 9, determined based on map data 41, could be divided by an expected travel speed. Since different speeds are typically reached on different sections of this route, the distance from the current position 33 to the specified destination 9 can also be divided into several segments, for each of which partial travel times are determined and added together to obtain the predicted remaining travel time 8.

[0077] In the simplest case, the expected driving speed can be estimated based on a maximum speed specified by the map data for the respective route segment. Preferably, however, the current traffic situation 32 or an expected traffic situation based on the current time 30 and the current date 31, especially the day of the week, is also taken into account. Based on the determined occupant identity 29, in particular a driver profile assigned to the occupant identity 29, the expected driving behavior of the driver in the specific traffic situation can also be considered.

[0078] In principle, a relationship between the aforementioned quantities can be determined by a statistical analysis of previous driving processes, for example by parameterizing the algorithm 48 for determining the predicted remaining driving time 8 using regression analysis.

[0079] To account for more complex relationships between the various input data, it can be advantageous to parameterize algorithm 48 using machine learning. For example, algorithm 48 can be based on a neural network, with the input weights of the neural network's nodes determined during training. Training can be performed using supervised learning, for which training datasets based on previous journeys can be provided. These datasets include both the input data and the actual travel time required to reach the destination, which serves as the target training outcome.

[0080] In the illustrated embodiment, steps S5 and S6 serve to predict a warm-up time 18, which indicates how long after switching off the temperature control device 6 a limit time 19 is expected to be reached, for which a predicted internal temperature value 17 reaches or exceeds a predetermined maximum temperature 45.

[0081] In step S5, relevant input data for this determination are first acquired. In this example, an actual indoor temperature value 20, which describes the current indoor temperature, is acquired via temperature sensor 50, along with a predefined target indoor temperature 21, to which the indoor temperature is currently regulated. With a sufficiently long operating time of the air conditioning unit 1, this information is redundant, as the actual indoor temperature should at least approximately correspond to the target indoor temperature if the air conditioning unit 1 is functioning correctly. Acquiring both values ​​can serve, for example, for validation purposes. In alternative configurations, however, it would be sufficient to acquire only one of these two pieces of information.

[0082] Furthermore, an outside temperature value 22, which relates to the outside temperature outside the vehicle 2, is determined via the temperature sensor 40, sensor data 23 from a light sensor 25, and a cooling capacity 24 required to maintain the interior temperature at the target interior temperature 21. Heat input into the interior 5 depends, on the one hand, on how much the body heats up due to direct sunlight, which can be estimated using the sensor data 23, and, on the other hand, on the difference between the outside temperature value 22 and the actual interior temperature value 20 or the target interior temperature 21. The relationship between these variables and the heat input can be determined through prior calibration measurements on the vehicle or a reference vehicle that is at least largely identical in construction.

[0083] Since the heat input into the interior 5 is compensated for by the cooling capacity 24 during normal operation of the air conditioning unit 1, the cooling capacity 24 can be used as an alternative or additional measure of the heat input. Taking this into account can enable validation and / or a more precise determination of the heat input.

[0084] In the example, the determination of the limit time 19 is carried out in step S6 by first predicting a respective indoor temperature value 17 for a large number of time points, in particular evenly spaced ones, in order to determine a time-temperature curve, as exemplified in Fig. Figure 3 is shown as a solid line for the case where the temperature outside the vehicle 2 is significantly higher than the interior temperature and / or there is strong solar radiation. Time is plotted on the x-axis (42) and temperature on the y-axis (43). The dashed line in Fig. Figure 3 shows the temperature 44 felt by the occupant 13, which also depends on the flow rate of the airflow 4.

[0085] As in Fig. As shown in Figure 3, the interior temperature values ​​17 initially correspond at least approximately to the target interior temperature 21 as long as the air conditioning unit 1 is operated as usual. From time 12, when the temperature control unit 6 is switched off, the interior temperature values ​​17 initially rise rapidly. With increasing distance from time 12, the slope of the temperature curve flattens out, as the interior temperature increasingly approaches the exterior temperature or can even exceed it in strong sunlight, thus reducing the heat input into the interior 5.

[0086] Based on the predicted indoor temperature values ​​17, it is easy to see at which point in time 19 these will reach or exceed the specified maximum temperature 45. The predicted warm-up time 18 then corresponds to the time interval between the point in time 19 and time 12.

[0087] Instead of explicitly determining the time-temperature curve or the multiple predicted indoor temperature values ​​17, the predicted indoor temperature value 17 can also be defined as a function of the input variables. By rearranging the equation that results when the maximum temperature is used as the indoor temperature value 17 as the result of the function, the limit time 19 or the predicted warm-up time 18 could also be calculated analytically.

[0088] As will be explained in more detail later, in the example, at time 10 in the time interval 15 between the deactivation of the temperature control device 6 and the expected achievement of the specified driving destination 9, the ventilation device is activated to increase the ventilation strength 11, whereby in Fig. 3 To illustrate the effect achieved, let's assume an increase in ventilation intensity 11, i.e., the fan speed, in a single stage. The faster airflow in the area of ​​the vehicle occupant 13 then leads to a reduction in the perceived temperature 44 by the occupant compared to the actual interior temperature by the amount 46. For example, if we assume an increase in the airflow speed from approximately 0 km / h to approximately 10 km / h, this would result in a reduction in the perceived temperature 44 of approximately 4°C.

[0089] Assuming that vehicle occupants can tolerate a temperature increase to a temperature limit 16, which is, for example, 4°C above the target interior temperature 21, a maximum temperature 45 can be permitted that is above this temperature limit 16 by the reduction amount 46. Thus, the permissible maximum temperature 45, and ultimately the fulfillment of the trigger condition 7 explained below, can depend on the target ventilation rate 14, to which the ventilation rate 11 is increased at time 10 or generally within the interval 15.

[0090] For example, it may be possible for the vehicle occupant to explicitly or indirectly specify the target ventilation level 14, to which the ventilation level 11 can be increased to a maximum. Since this also adjusts the permissible maximum temperature 45 and thus the limit time 19, the vehicle occupant 13 can, for example, enable the temperature control unit 6 to switch off earlier and thus achieve greater energy savings by allowing a higher target ventilation level 14.

[0091] In steps S7 to S9, a trigger condition 7 is checked. If this condition is met, the temperature control unit 6 is switched off in step S10. In step S7, it is first checked whether the predicted warm-up time 18 equals or exceeds the predicted remaining travel time 8. Trigger condition 7 can only be met if this is the case. In other words, trigger condition 7 should only be met if the predicted remaining travel time 8 is sufficiently short that the interior temperature values ​​17 in the interior 5 are expected to remain below the maximum temperature 40 during the remaining travel time 8.

[0092] Since in the Fig. In the example shown, where the interior temperature perceived by the vehicle occupant 13 is reduced by the amount 46 from time 10 onwards due to the airflow 4, the trigger condition 7 in the example is therefore only fulfilled if it can be assumed that the interior temperature perceived by the vehicle occupant 13 will not exceed the temperature limit 16 until the destination 9 is reached.

[0093] As already explained in the general section, the operation of the temperature control unit 6 may also be necessary to prevent excessively high humidity in the vehicle interior. Therefore, in the example, step S8 additionally checks, as a necessary sub-condition of the trigger condition 7, whether a humidity value 26 determined by the humidity sensor 39 is less than a predefined limit value.

[0094] Since, as already explained in the general section, allowing a temperature increase in the vehicle interior can be problematic even if the driver is fatigued, the example in step S9 checks, as a further necessary sub-condition of trigger condition 7, whether a fatigue level of 28 of the vehicle occupant 13 indicates sufficient alertness. The fatigue level 28 can be determined, for example, based on camera images from camera 38 by evaluating, for instance, the end-of-sleep times of the vehicle occupant 13. Additionally or alternatively, steering movements can be evaluated. Approaches to fatigue detection are known per se and will therefore not be explained in detail.

[0095] If the trigger condition 7 is not met, the procedure continues with step S14, in which the air conditioning unit 1 is operated in the usual manner to regulate the indoor temperature to the target indoor temperature 21 by appropriately controlling the temperature control unit 6 and the ventilation unit 3.

[0096] If, however, all sub-conditions of the trigger condition 7 checked in steps S7 to S9 are met, the temperature control unit 6 is deactivated in step S10, for example by stopping the operation of a compressor of a compression refrigeration machine. The ventilation unit 3 can also be deactivated initially. In this example, however, the ventilation unit 3 is initially operated largely at a low ventilation rate 11, so that, as in Fig.Figure 3 shows the time before time 10, where the temperature felt by the occupant 13 is slightly below the internal temperature values ​​17.

[0097] In step S11, it is then checked whether the current interior temperature value 17 has already reached the temperature limit value 16 due to the warming of the air in the interior of the vehicle 2 after the temperature control unit 6 has been switched off. In this example, this is the case at time 10, so that at this time 10 in step S12, the ventilation level 11 of the ventilation unit 3 is set to the target ventilation level 14, thereby reducing the perceived temperature 44 by the reduction amount 46.

[0098] If, however, the temperature limit of 16 has not yet been reached, step S 12 is initially skipped.

[0099] In step S13, it is then checked whether a reactivation condition 27 is met. In the example, reactivation condition 27 is met if it is detected that the humidity value 26 determined by the humidity sensor 39 exceeds a limit value at the current time and / or if the fatigue level 28 of the vehicle occupant 13 indicates fatigue of the vehicle occupant 13. In these cases, the temperature control unit 6 is reactivated in order to then resume normal climate control of the interior from step S14 onwards.

[0100] If, however, the reactivation condition 27 is not met, the procedure is repeated from step S11, so that the temperature control device 6 remains inactive, in particular until the travel destination 9 is reached, and thus a significant energy saving can be achieved. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2011 120 868 A1

[0002] US 2016 / 0325600 A1

[0002]

Claims

[1] Method for operating an air conditioning system (1) of a motor vehicle (2), comprising a ventilation system (3) for generating at least one airflow (4) in the vehicle interior (5) and at least one temperature control system (6) for temperature control of the airflow (4), wherein during the operation of the air conditioning system (1) it is checked whether a trigger condition (7) is met, the fulfillment of which depends on a predicted remaining driving time (8) until reaching a predetermined driving destination (9) of the motor vehicle (2), wherein if the trigger condition (7) is met the temperature control system (6) is switched off, characterized by, that at at least one time (10) after the fulfillment of the triggering condition (7) and before reaching the destination (9) the ventilation strength (11) of the ventilation device (3) is increased compared to the ventilation strength (11) used at the time (12) of the fulfillment of the triggering condition (7) in order to increase the air velocity of the airflow (4) in the area of ​​at least one vehicle occupant (13) in the vehicle interior (5). [2] Method according to claim 1, characterized by, that the fulfillment of the trigger condition (7) depends on a predetermined target ventilation level (14), wherein the ventilation level (11) is increased to the target ventilation level (14) at at least one time point (10) of a time interval (15) between the fulfillment of the trigger condition (7) and the achievement of the travel destination (9) and / or wherein within this time interval (15) the ventilation level (11) exceeds the predetermined target ventilation level (14) by a maximum of 20% or a maximum of 10% of the target ventilation level (14). [3] Method according to claim 1 or 2, characterized by , that the ventilation intensity (11) is increased only at or from a time (10) after the time (12) of the fulfillment of the trigger condition (7) at which a specified temperature limit (16) is exceeded by a determined or predicted interior temperature value (17) relating to an interior temperature in the vehicle interior (5). [4] Method according to any of the preceding claims, characterized by , that the trigger condition (7) is fulfilled or can only be fulfilled if - on the one hand, a predicted warm-up time (18) corresponds to or exceeds the predicted remaining driving time (8), wherein the predicted warm-up time (18) indicates how long after the fulfillment of the trigger condition (7) a limit time (19) is expected to be reached at which a predicted interior temperature value (17), relating to an interior temperature in the vehicle interior (5) at the limit time (19), reaches or exceeds a predetermined maximum temperature (45), and / or - on the other hand, a predicted interior temperature value (17), which relates to an interior temperature in the vehicle interior (5) for an end of the predicted remaining driving time (8) and thus for reaching the driving destination (9), is less than or equal to the maximum temperature (45). [5] Method according to claim 4, characterized by , that the predicted warm-up time (18) and / or the predicted interior temperature value (17) are determined as a function of an actual interior temperature value (20) that describes the interior temperature at time (12) of the fulfillment of the trigger condition (7), and / or a predetermined target interior temperature (21) to which the interior temperature is regulated before the fulfillment of the trigger condition (7), and / or an outside temperature value (22) that relates to an outside temperature present outside the vehicle (2), and / or sensor data (23) of a light sensor (25) and / or a cooling capacity (24) required to maintain the interior temperature at the target interior temperature (21). [6] Method according to any of the preceding claims, characterized by, that a humidity value (26) relating to the interior humidity (5) of the motor vehicle (2) is determined, wherein the fulfillment of the trigger condition (7) additionally depends on the humidity value (26) and / or wherein the temperature control device (6) is reactivated if, after the temperature control device (6) has been switched off, a reactivation condition (27) which evaluates the humidity value (26) is fulfilled. [7] Method according to any of the preceding claims, characterized by , that by means of an automatic fatigue detection a fatigue level (28) of the vehicle occupant (13) or at least one of the vehicle occupants (13) is determined, wherein the fulfillment of the trigger condition (7) additionally depends on the fatigue level (28) and / or wherein the temperature control device (6) is reactivated if, after the temperature control device (6) has been switched off, a reactivation condition (27) which evaluates the fatigue level (28) is fulfilled. [8] Method according to any of the preceding claims, characterized by , that the predicted remaining travel time (8) - on the one hand, depending on a determined occupant identity (29) of the vehicle occupant (13) or at least one of the vehicle occupants (13) and / or a current time (30) and / or a current date (31) and / or a current traffic situation (32), and / or - on the other hand, is determined by an algorithm (48) that is trained by machine learning. [9] Method according to any of the preceding claims, characterized by , that the destination (9) is automatically selected from several possible destinations (34) depending on the actual position (33) of the motor vehicle (2) and / or the or a determined occupant identity (29) of the vehicle occupant (13) or at least one of the vehicle occupants (13) and / or the or a current time (30) and / or the or a current date (31). [10] Motor vehicle with an air conditioning device (1) comprising a ventilation device (3) for generating at least one airflow (4) in the vehicle interior (5) and at least one temperature control device (6) for temperature control of the airflow (4), and a control device (35) for controlling the air conditioning device (1), characterized by that the control device (35) is set up to carry out the procedure according to one of the preceding claims.

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