Method for controlling a start-stop function for a hybrid motor vehicle

Abstract

Method for controlling a start-stop function of a hybrid motor vehicle with an internal combustion engine, an electric motor and a vehicle battery, comprising the steps: - Detection (S2) of an instantaneous battery voltage (U Batterie ) the vehicle battery, - Recording (S3) a current temperature (Temp Motor ) of the internal combustion engine, - Continuation of the journey after the hybrid vehicle has come to a standstill, accompanied by the shutdown of the combustion engine, a) with the internal combustion engine or b) with the electric motor as the drive type, according to a predefined start-stop strategy taking into account the current battery voltage (U) Batterie ) and the current temperature (Temp Motor ) of the internal combustion engine and taking into account at least one further parameter, taking into account a) the instantaneous battery voltage (U Batterie ), b) the current temperature (Temp Motor ) of the internal combustion engine, c) and at least one further parameter, which are considered as input parameters by a matrix (1) and / or flow into a matrix (1) as input variables, whereby, with the aid of the matrix (1), it is evaluated which of the two drive types is activated for the continuation of the journey, where the matrix result is compared with a reference value to determine whether the matrix result a) is greater than the reference value, or b) is smaller than the reference value where the battery voltage (U) Batterie ), the temperature (Temp Motor ) of the combustion engine as well as at least one further parameter are evaluated using a multidimensional characteristic curve field to determine whether, according to the specified start-stop strategy, a continuation of the journey after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine, a) with the internal combustion engine or b) with the electric motor to be designed as a drive type where the current battery voltage (U Batterie ), the current temperature (Temp Motor ) of the internal combustion engine and / or at least one further parameter is / are considered as a weighted value.

Description

[0001] The invention relates to a method for controlling a start-stop function of a hybrid motor vehicle, a control device and a hybrid motor vehicle.

[0002] In the light of the invention, the term “hybrid vehicle” is to be understood as a vehicle which has both an internal combustion engine drive and an electric motor drive, whereby both motor drive variants and their drive power are designed to move the motor vehicle over longer distances, whereby the motor drive variants can be brought into operation both alone and in cooperation to drive the vehicle.

[0003] To reduce fuel and energy consumption, modern vehicles are equipped with so-called start-stop systems, which shut off the combustion engine when the vehicle is stationary (for example, at a red light). These systems can be used in vehicles powered solely by combustion engines, but also in hybrid vehicles, which have an electric drive motor in addition to a combustion engine.

[0004] To determine whether the combustion engine will actually shut down when a vehicle is stationary (synonym for vehicle standstill), various evaluation parameters are considered in practice according to the state of the art to ensure that the combustion engine can be restarted safely. For example, the charge level of a vehicle's battery and the current temperature of the combustion engine are used as evaluation parameters.

[0005] However, taking these two parameters into account, it can very easily happen that the combustion engine is switched off when the vehicle is stationary (vehicle is at a standstill) at a red light and has to be restarted very shortly afterwards (in the range of seconds, e.g. 2 seconds).

[0006] The latter behavior is perceived as annoying by most drivers, since the disadvantage of the disturbance caused by starting the combustion engine outweighs the advantage of fuel savings and emission reductions due to the brief shutdown of the combustion engine.

[0007] From the subsequently published DE 10 2017 218 369 A1, a start-stop control for a vehicle with an internal combustion engine drive is disclosed, wherein in this disclosed method for controlling a start-stop function of an internal combustion engine in a motor vehicle, the internal combustion engine is stopped when the motor vehicle is stopped (vehicle standstill) and when a predetermined switch-off condition is present, wherein the predetermined switch-off condition depends on at least three input parameters.

[0008] The present invention is based on the subsequently published DE 10 2017 218 369 A1, whereby the inventive solution extends to so-called hybrid vehicles or includes hybrid vehicles.

[0009] From DE 10 2004 006 991 A1 a method for operating an internal combustion engine of a motor vehicle, in particular a hybrid vehicle, is known, wherein during operation of the motor vehicle, upon occurrence of at least one predetermined first condition, a stop operation for the internal combustion engine is requested, in which the internal combustion engine is stopped, and upon occurrence of at least one predetermined second condition, the internal combustion engine is restarted independently of a torque request by a driver or a restart of the internal combustion engine is requested.As further stated in this document, when stop operation is requested, a time period is determined for at least one second condition, after which this second condition is expected to occur after activation of stop operation and to lead to the restart of the internal combustion engine, and the time period is compared with a predetermined threshold value for a minimum duration of stop operation, wherein stop operation is inhibited if at least one time period is shorter than the predetermined threshold value and stop operation is permitted if one, several or all time periods are equal to or longer than the predetermined threshold value.

[0010] DE 10 2006 033 930 A1 relates to a method for operating a hybrid drive of a vehicle, wherein the hybrid drive has at least one internal combustion engine and at least one electric motor as drive units. As further stated in this document, the following steps are performed: - Determining the driving profile of a route; and - Operating the internal combustion engine and / or electric motor, or components and / or auxiliary units of these drive units, depending on operating parameters obtained from determining the driving profile.

[0011] From DE 10 2012 218 737 A1 a method for automatically switching off and starting a drive motor in a motor vehicle by means of a start-stop device is known, which automatically switches off the drive motor when all predetermined switch-off conditions are met, and which automatically starts the automatically switched off drive motor when a switch-on request is present, and wherein in the sense of a switch-off condition an automatic switch-off is only permitted if the current state of charge of an energy storage device providing the energy for the automatic start of the drive motor exceeds a state of charge limit value dependent on the temperature of this energy storage device.

[0012] Since the technology of an automatic start-stop system is a relatively new one, there is still potential for improvement.

[0013] There is still a lot of room for optimization, especially with hybrid vehicles, i.e. vehicles that have both a combustion engine and an electric motor.

[0014] The object of the invention is therefore to present a solution by means of which the technology of an automatic start-stop system in a vehicle with a hybrid drive is further perfected.

[0015] The object is achieved by a method, a control device, and a hybrid motor vehicle according to the independent claims. Advantageous further developments are specified in the dependent claims.

[0016] The method according to the invention for controlling a start-stop function of a motor vehicle with an internal combustion engine and a vehicle battery comprises the steps: - Detecting the current battery voltage of the vehicle battery, - Recording the current temperature of the combustion engine, - Continuation of the journey after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine, a) with the combustion engine or b) with the electric motor as the drive type, according to a predetermined start-stop strategy, taking into account the current battery voltage and the current temperature of the combustion engine and taking into account at least one other parameter, taking into account a) the current battery voltage (U Batterie ), b) the current temperature (Temp Motor ) of the combustion engine, c) and at least one further parameter, which are taken into account as input parameters by a matrix (1) and / or flow into a matrix (1) as input variables, wherein with the aid of the matrix (1) it is evaluated which of the two drive types is activated for the continuation of the journey, where the matrix result is compared with a reference value to determine whether the matrix result a) is greater than the reference value, or b) is smaller than the reference value,where the battery voltage (U Batterie ), the temperature (Temp Motor ) of the combustion engine and at least one further parameter are evaluated using a multi-dimensional characteristic field to determine whether, according to the specified start-stop strategy, a continuation of the journey after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine, a) with the combustion engine or b) is to be carried out with the electric motor as the drive type, whereby the current battery voltage (U Batterie ), the current temperature (Temp Motor ) of the combustion engine and / or at least one other parameter is / are taken into account as weighted value(s).

[0017] In order to achieve further perfection of an automatic start-stop system, the invention proposes that when the drive is reactivated, a multidimensional matrix is ​​used to decide which of the two drive types (combustion engine drive or electric motor drive) is to be used for the upcoming onward journey. A notice:

[0018] The solution does not refer to criteria for deactivation, but to the phase of activation or re-deactivation after the vehicle drive has been deactivated, for example when the vehicle is stationary or at a standstill (for example at a red light), in which the combustion engine is switched off or the electric motor is stopped.

[0019] As already discussed in the as yet unpublished application with the priority date of October 13, 2017, the engine is preferably switched off when the vehicle is stationary (vehicle at a standstill). The vehicle may have a conventional drive with an internal combustion engine or a hybrid drive that additionally has an electric drive motor. The battery voltage of a vehicle battery is a measure of the vehicle battery's state of charge. The vehicle battery can preferably be charged by the internal combustion engine and serves as an energy storage device, for example, for operating the electric drive motor in a hybrid drive or for (re-)starting the internal combustion engine.

[0020] According to the invention, it is proposed that at least one further parameter is taken into account as an influencing factor as to whether a continuation of the journey, after a standstill of the hybrid vehicle, accompanied by a shutdown of the combustion engine, a) with the combustion engine or b) with the electric motor as the drive type.

[0021] According to a first preferred embodiment, information about a topology of the upcoming route is taken into account as a further parameter.

[0022] To decide which of the two drive types (combustion engine drive or electric motor drive) is (re)activated after deactivation (stop) of the combustion engine when the vehicle is stationary or when the vehicle is at a standstill, a) analogous to the solutions of the still unpublished application with the priority date 13.10.2017, b) decided using a (further) multidimensional matrix.

[0023] As with the solutions of the as yet unpublished application with the priority date of 13 October 2017, weighted factors are preferably used in the decision-making process as to which of the two drive types (combustion engine drive or electric motor drive) is activated for the next section of the route.

[0024] The information about a topology of the upcoming route can be determined on the vehicle side with the help of a navigation system and / or an e-horizon system and the current position of the hybrid vehicle and / or received via a communication interface in the hybrid vehicle.

[0025] The information about a topology of the upcoming route can preferably contain the information whether the upcoming route is (still) in town or country, whether a town will soon be reached or left, or whether the vehicle is approaching an intersection or traffic lights, or more generally, whether the upcoming route / topology of the upcoming route is "pieced up" in the sense of many possible "disturbing factors" (e.g. many traffic lights, many short route sections / sections).

[0026] Taking this information into account, for example, if the vehicle battery is at a normal charge level and the upcoming journey is very fragmented, the journey will be continued after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine, preferably with the electric motor as the drive type.

[0027] In contrast, if the vehicle battery is at a low charge level and the upcoming journey is not very fragmented, the journey will preferably be continued with the combustion engine as the drive type after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine.

[0028] In an advantageous embodiment of the invention, the method for controlling a start-stop function is characterized in that the battery voltage, the temperature of the combustion engine and the at least one further parameter are evaluated using a multi-dimensional characteristic field to determine whether, according to the predetermined start-stop strategy, a continuation of the journey after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine, a) with the combustion engine or b) is to be carried out with the electric motor as the drive type.

[0029] In a further advantageous embodiment of the invention, the at least three input parameters, namely the battery voltage, the combustion engine temperature and information about the topology of the upcoming route are evaluated as a complex by means of an at least three-dimensional matrix (at least three-dimensional characteristic field) in order to be able to make a needs-based decision regarding the continuation of the journey after a standstill of the hybrid vehicle, accompanied by a shutdown of the combustion engine, in the manner of whether a) with the combustion engine or b) the journey is to be continued using the electric motor as the propulsion method.

[0030] This evaluation of the three input parameters is preferably carried out via a computing unit.

[0031] In a further advantageous embodiment of the invention, one or more of the input parameters, ie the current battery voltage, the current temperature of the combustion engine and / or the at least one further parameter are taken into account as weighted value(s).

[0032] The weighted values ​​can, for example, be variable values.

[0033] The weighted values ​​can, for example, be defined as a function of the input parameters and / or according to a table of values ​​depending on the input parameters.

[0034] In a further advantageous embodiment of the invention, in the case of the predefined start-stop strategy, a continuation of the journey, after a standstill of the hybrid vehicle, accompanied by a shutdown of the combustion engine, with the electric motor as the drive type is provided (is carried out) if the evaluation of the input parameters results in a calculated value which exceeds a predefined limit value or threshold value, or the matrix result is greater than the reference value.

[0035] For the sake of clarity, it should be noted that the expression “accompanied by a shutdown of the internal combustion engine” is to be understood in a general sense (including the past) and does not refer exclusively to the most recent driving cycle or the most recent section of the journey, but that the shutdown or deactivation of the internal combustion engine may have occurred one or more driving cycles or one or more sections of the journey in the past, or in the broadest sense, “the shutdown / deactivation of the internal combustion engine” may also be due to the last driving operation / the last use of the vehicle.

[0036] The vehicle's automatic start-stop system therefore does not restart the combustion engine if the evaluation of the multidimensional characteristic curve (preferably using a computing unit) results in a value greater than or equal to a predefined and / or predeterminable limit. Exceeding the limit therefore corresponds to a decision to use the electric motor drive mode to continue driving.

[0037] A control device with a processor unit which is configured to carry out a method according to the invention, as well as a motor vehicle with such a control device are further aspects of the invention.

[0038] In the following, the invention will be described with reference to Fig. 1 to 3 are explained in more detail using examples. The figures and the values ​​given therein are only examples and are intended to facilitate understanding.

[0039] They show schematically: Fig. 1: a circuit diagram of a preferred embodiment of the method according to the invention; an engine start-stop control of a vehicle with a hybrid drive via a multidimensional (at least 3 or more) characteristic curve map; Fig. 2: exemplary one-dimensional characteristic maps for individual possible evaluation parameters according to a preferred embodiment of the invention; Fig. 3: a flow chart for carrying out the method according to the invention according to an embodiment variant.

[0040] The Fig. 1 shows an example of a matrix (1) in which three input parameters are taken into account, or in this matrix (1) the three input variables come into effect as weighted variables, whereby the input parameters are a) the battery voltage (U Batterie ), b) the current temperature (Temp Motor ) of the combustion engine, and c) the topology of the upcoming route (FS Topologie ), is.

[0041] If a request for a start / activation of the vehicle drive is present from a control unit (SE) not shown in detail by means of a HIGH signal level, the matrix (1) is used to evaluate on the basis of the parameters shown which of the two drive types is activated for the following driving operation or for the continuation of the journey (for the onward journey).

[0042] As can be seen from the logic, the matrix result (e.g. in the range from 1 to 5) is compared with a reference value (1.5) to determine whether the result is greater than the reference value (1.5) or smaller than the reference value (1.5).

[0043] As can be seen from the Fig. 1, if the matrix result value is greater than 1.5, the electric motor is activated (*2), whereas if the matrix result value is less than 1.5, the combustion engine is activated (*1).

[0044] The exact matrix result value of 1.5 is assigned to one of the two drive types depending on the design (so that no undefined states can occur).

[0045] The Fig. 2 shows an example of three input parameters, or exemplary one-dimensional characteristic maps for individual possible evaluation parameters according to a preferred embodiment of the invention.

[0046] As from the Fig. As can be seen in Figure 2, three parameters are shown here, which are included in the matrix of Fig. 1 are used as input variables to determine which drive type is used to continue the journey after a stop.

[0047] This is explained in more detail below using two examples: In Fig. In Figure 2, individual input parameters are represented as a one-dimensional array. The multidimensionality is achieved by multiplying the weighted individual parameters.

[0048] As can be seen from the individual sub-figures and the exemplary calculation of the Fig. 2, a) with a well-charged battery and a “pieced-up” route with many expected “disturbances” (breaks, vehicle standstills, risk of traffic jams, traffic lights), the electric motor is selected as the drive type and, after a deactivation phase of the combustion engine, the electric motor is activated accordingly (here, restarting the combustion engine is not worthwhile), whereas b) in the case of a poorly charged battery and a “less fragmented” route with few expected “disturbances” (breaks, vehicle standstills, risk of traffic jams, traffic lights), the combustion engine is selected as the drive type and, after a deactivation phase of the combustion engine, the combustion engine is activated accordingly (in this case, restarting the combustion engine is worthwhile).

[0049] As can be seen from the weighting of the individual parameters, in this example, or for this application, the influence of the combustion engine temperature has a rather insignificant influence, or rather, compared to the other influencing parameters, only a smaller influence (weighting factor) on the matrix result.

[0050] Nevertheless, it is important not to neglect the combustion engine temperature as such in the overall concept, since taking it into account does justice to the fact that a warm combustion engine (temp. Motor= large) can be started more easily than a cold combustion engine (Temp Motor = low). For this reason, with a warm combustion engine (temp Motor = large or medium), for example for the battery voltage (U Batterie ) accordingly assume a lower value than a still tolerable value in order to continue the journey with the electric motor, since the matrix product still exceeds a predetermined limit value in order to be able to guarantee a "comfortable" starting behavior of the combustion engine during the further course of the journey.

[0051] Of course, when setting the lower limit of the battery voltage as a tolerable value, it is important to ensure that this value (e.g. after a longer break in driving) is also valid when the combustion engine is cold (temp. Motor= low) still guarantees a safe starting behavior of the combustion engine, whereby two cases must be distinguished: - comfortable starting of the combustion engine, and - guaranteed starting of the combustion engine

[0052] A guaranteed starting process must be ensured at all times (regardless of the combustion engine temperature or other parameters), whereby no requirements regarding "comfort" (e.g. starting time less than x seconds, "perceptibility" by the driver, ...) are placed on the starting process, since this is a "one-time" operating case at the start of the journey.

[0053] A comfortable starting process, on the other hand, should meet stricter criteria, such as a starting time of less than x seconds, very low "perceptibility" by the driver, ..., since this is a "repeated" operating case during the journey.

[0054] Fig. 2 A) shows an example field for the battery voltage U-battery (U Batterie ) as input parameter.

[0055] Fig. 2 B) shows an example of a field for the topology of the upcoming route (FS Topologie ) as input parameter.

[0056] Fig. 2 C) shows an example field for the combustion engine temperature (Temp Motor ) as input parameter. Example 1:

[0057] The battery voltage of the vehicle battery U Batterie is 13 volts.

[0058] The weighting function in Fig. 2 A shows that this corresponds to a weighting value of 1.6.

[0059] The topology of the upcoming route (FS Topologie ) is rated as “typical” to “very” “fragmented” based on electronic map data and the current vehicle position, which according to Fig. 2B) corresponds to a weighted value of 1.5. The combustion engine temperature is in a medium range (Temp Motor = medium) and is given a weighting factor of 1.0.

[0060] Then the matrix criterion MK=1.6*1.5*1.0=2.4. A specified limit of 1.5 is thus exceeded, since MK > limit 1.5. The limit is therefore exceeded. Therefore, after a stop procedure with the combustion engine shut down, the electric motor is selected as the drive type for continued travel. Example 2:

[0061] The battery voltage of the vehicle battery U Batterie is 10.5 volts, corresponding to a weighting factor of 0.8.

[0062] The topology of the upcoming route (FS Topologie ) is assessed as being less fragmented due to electronic map data and the current vehicle position, which according to Fig. 2B) corresponds to a weighted value of 0.65. At an average combustion engine temperature (Temp Motor = medium), with a weighting factor = 1.0 applies to the matrix criterion MK=0.8*0.65*1.0=0.52 and thus MK < limit 1.5. The limit is therefore undershot. Thus (after a stop with shutdown of the combustion engine), the combustion engine is selected as the drive type for continued travel.

[0063] For reasons of operational safety, it goes without saying that even during the journey, especially during longer uninterrupted operation with the electric motor as the drive type, a cyclical check is carried out to determine whether the limit value is undercut during the journey. If the limit value is detected to be undercut (MK < 1.5), an automatic switch to the combustion engine as the drive type can be made so that excessive discharge of the vehicle battery can be reliably prevented.

[0064] Fig. 3 shows an example of the implementation of the method according to the invention according to a preferred embodiment.

[0065] In step S1, the method starts by, for example, a drive request from a control unit (SE) not shown in detail, signaling (requesting) a request for a start / activation of the vehicle drive by means of a HIGH signal level.

[0066] In step S2, the battery voltage (U Batterie ) of the vehicle battery.

[0067] In step S3, the combustion engine temperature (Temp Motor ) recorded.

[0068] In step S4, a further input parameter is recorded or determined, e.g. based on electronic map data and the current vehicle position, how the topology of the upcoming route (FS Topologie ) is.

[0069] In step S5, these input parameters are evaluated by a computing unit within the framework of the start-stop strategy (for example, in the form of a multiplication of the parameters) and accordingly a decision is made as to which drive type, whether a) with the combustion engine or b) with the electric motor, the journey is continued after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine (combustion engine or electric motor).

Claims

[1] Method for controlling a start-stop function of a hybrid motor vehicle with an internal combustion engine, an electric motor and a vehicle battery, comprising the steps: - Detection (S2) of a current battery voltage (U Batterie ) of the vehicle battery, - Recording (S3) a current temperature (Temp Motor ) of the combustion engine, - Continuation of the journey after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine, a) with the combustion engine or b) with the electric motor as the drive type, according to a given start-stop strategy taking into account the current battery voltage (U Batterie ) and the current temperature (Temp Motor ) of the combustion engine and taking into account at least one other parameter, taking into account a) the current battery voltage (U Batterie ), b) the current temperature (Temp Motor ) of the combustion engine, c) and at least one further parameter, which are taken into account as input parameters by a matrix (1) and / or flow into a matrix (1) as input variables, wherein with the aid of the matrix (1) it is evaluated which of the two drive types is activated for the continuation of the journey, where the matrix result is compared with a reference value to determine whether the matrix result a) is greater than the reference value, or b) is less than the reference value, where the battery voltage (U Batterie ), the temperature (Temp Motor ) of the combustion engine and at least one further parameter are evaluated using a multi-dimensional characteristic field to determine whether, according to the specified start-stop strategy, a continuation of the journey after the hybrid vehicle has come to a standstill, accompanied by a shutdown of the combustion engine, a) with the combustion engine or b) with the electric motor as drive type, where the instantaneous battery voltage (U Batterie ), the current temperature (Temp Motor ) of the combustion engine and / or at least one other parameter is / are taken into account as weighted value(s). [2] Method for controlling a start-stop function according to claim 1, wherein the at least one further parameter is information about a topology of the upcoming route (FS Topologie ) contains. [3] Method for controlling a start-stop function according to claim 2, wherein the information about a topology of the upcoming route (FS Topologie) is determined with the aid of a navigation system and / or an e-horizon system and the current position of the hybrid motor vehicle (S4) and / or received via a communication interface in the hybrid vehicle. [4] A method for controlling a start-stop function according to claim 1, wherein the weighted value(s) are variable values. [5] Method for controlling a start-stop function according to one of claims 1 and 4, wherein the and / or the weighted values ​​are determined as a function of the input parameters and / or according to a value table depending on the input parameters. [6] Method for controlling a start-stop function according to one of the preceding claims 1, 4 to 5, wherein according to the predetermined start-stop strategy, a continuation of the journey, after a standstill of the hybrid vehicle, accompanied by a shutdown of the combustion engine, is to be carried out with the electric motor as the drive type if the matrix result is greater than the reference value. [7] Control device with a processor unit which is arranged to carry out a method for controlling a start-stop function according to one of the preceding claims. [8] Hybrid motor vehicle with a control device according to claim 7.

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