Control system with at least one electronic control unit for controlling an internal combustion engine in a hybrid vehicle

Abstract

Control system with at least one electronic control unit (3, 5) for controlling an internal combustion engine in a hybrid vehicle, wherein the control unit is designed to receive input signals for acquiring data for recognizing a current situation (S0) and for recognizing at least one situation (S1, S2) prevailing in the near future with respect to an expected speed profile (v e ) evaluates and that it depends at least on the expected velocity profile (v e ) controls the starting and stopping of the combustion engine, characterized in that the control unit is designed such that the starting or stopping of the combustion engine depends on dynamically shifted e-driving speed limits (eV) Max,CD , eV Max,CS) is feasible, and the control unit is designed in such a way that starting the combustion engine is brought forward to an acceleration process or postponed if, due to an expected change in operating strategy mode from Charge Depleting (discharging the high-voltage storage) to Charge Sustaining (maintaining the charge state or charging the high-voltage storage), starting the combustion engine is required anyway, which would otherwise fall into a constant-speed driving phase.

Description

[0001] The invention relates to a control system with at least one electronic control unit for controlling an internal combustion engine in a hybrid vehicle.

[0002] Hybrid vehicles, which include at least one combustion engine and at least one electric motor as drive motors, have been available as production vehicles for many years. These hybrid vehicles feature control systems with at least one electronic control unit, which, through appropriately programmed function modules, executes various operating procedures to select an operating mode adapted to the current driving situation. Selectable operating modes include, in particular, purely electric driving (only the electric motor provides propulsion; "E-mode," "E-driving"), purely combustion engine driving (only the combustion engine provides propulsion), and / or hybrid-powered driving (both the electric motor and the combustion engine provide propulsion).

[0003] Known operating procedures primarily consider the state of charge of the battery or other electrical storage device (e.g., supercapacitor) to select the operating mode. In some cases, parameters such as the current vehicle speed, driving style, or certain currently configured customer functions are also taken into account.

[0004] For further information on the state of the art, reference is made to DE 198 31 487 C1, DE 100 35 027 A1, DE 10 2010 062 379 A1, DE 101 49 905 B4, DE 10 2013 016 569 A1, DE 10 2013 218 187 A1, FR 2 863 953 A1 and US 2015 / 0 314 775 A1.

[0005] The purpose of the invention is to further improve a control system with an operating method of the type mentioned above.

[0006] This problem is solved according to the invention by the subject matter of claim 1. Advantageous embodiments of the invention are contained in the dependent claims.

[0007] The invention generally comprises a method for controlling the start-up and shutdown of an internal combustion engine in a hybrid vehicle, wherein the start-up and shutdown behavior is optimized in a defined manner, which will be discussed in more detail below, by means of an evaluation of the current situation as well as upcoming situations, preferably in a defined foresight range, with regard to an expected speed profile and preferably also to a load profile depending on driver interaction and / or the state of charge of the high-voltage storage system.

[0008] According to the invention, data for detecting a current situation and for detecting at least one situation prevailing in the near future (e.g., defined forecast horizon < 5 km) are generally acquired and evaluated with regard to the expected speed profile. Such data for predicting the speed profile include, in particular: - Map data on environmental and / or traffic guidance information from navigation systems (e.g., ADAS with RTTI) as well as (driver-specific) learning systems for predicting the most likely route ahead, for predicting speeds in upcoming curves, for recording upcoming and current speed limits, for predicting the upcoming gradient of the route, for predicting the average speed depending on the traffic density on the upcoming route, etc. and / or - Sign recognition systems (e.g., KAFAS), especially for recognizing traffic signs that affect the expected speed and / or - Camera systems for recording the current state of the upcoming and relevant traffic light system (traffic light state detection) as well as (learning) systems in the vehicle or via backend for temporal prediction of the relevant traffic light systems (traffic light state prediction) and / or - Vehicle sensors (e.g. radar and KAFAS) for detecting other road users ahead (especially speed and acceleration of the vehicle in front) and / or - All other systems that can contribute to a prediction of the expected speed profile.

[0009] In addition, at least one driver interaction is preferably determined, in particular by recording the accelerator pedal position and the current load request.

[0010] According to the invention, the starting and stopping of the combustion engine is primarily controlled based on the expected speed profile and the expected load profile within a given forecast horizon, and preferably also on current driver interaction. Furthermore, the starting and stopping behavior is optimized depending on the vehicle's operating state, particularly the state of charge of the high-voltage battery.

[0011] The expected speed profile is preferably compared with the usual charge-dependent fixed maximum electric driving speed limits for purely electric driving (E-mode) when the battery is fully charged (CD = "charge depleting", upper electric driving speed limit) and when it is discharged (CS = "charge sustaining", lower electric driving speed limit). If the current electric driving speed limit is undershot by the actual speed, the combustion engine is immediately switched off, according to the state of the art. If the current electric driving speed limit is exceeded by the actual speed, the combustion engine is immediately restarted, according to the state of the art. Furthermore, according to the state of the art, restarting or switching off also occurs outside these speed limits if load limits, which depend on speed and battery charge level, are exceeded or fallen below.The invention specifically considers the expected speed and load profile, and not just the current speed and load, with regard to these previously rigidly defined limits. According to the invention, the new situation(s) that may arise in the near future can lead to a (continuous) upward and downward shift and / or to the ignoring of these previously situation-independent starting limits.

[0012] The control by means of the control system according to the invention or the method according to the invention for controlling the starting or stopping of an internal combustion engine is carried out in a defined manner, namely preferably in such a way that • that phases with only a brief shutdown or only a brief restart of the combustion engine are avoided and / or • that the E-mode is maintained for as long as possible at comparatively low loads, or avoided at comparatively high or increasing loads, and / or • that the combustion engine is preferably started during acceleration processes and not during constant driving. • That expected long delays should preferably be driven with the combustion engine switched off. • That the number of start-up and shutdown processes in customer operations is reduced.

[0013] In an advantageous embodiment of the invention, starting from a purely electric driving state when acceleration to a value above the upper e-driving speed limit is expected, the combustion engine is started as soon as the load demand increases or at the beginning of the acceleration, and not only when the largely static e-driving speed limit or load limit is exceeded.

[0014] In a further advantageous embodiment of the invention, the combustion engine is prevented from being switched off if a deceleration is expected to result in only a brief drop below the electric driving speed limit. This prevents the combustion engine from restarting shortly after it has been switched off.

[0015] In a further advantageous embodiment of the invention, the combustion engine is switched off early, even before the electric vehicle speed limit is reached, when deceleration is expected to fall below the electric vehicle speed limit. This requires that the deceleration lasts long enough or that the expected speed remains below the electric vehicle speed limit.

[0016] Furthermore, during deceleration and coasting maneuvers where the target speed is above the electric vehicle speed limit, the combustion engine is switched off (early) when the load is removed, provided that a prolonged period of unloaded driving or deceleration is expected (e.g., coasting downhill). This is preferably the case when the (early) shutdown is considered customer-value and efficient.

[0017] Preferably, regardless of the electric driving limits and without a load request, the combustion engine is prevented from starting as long as no acceleration is expected or taking place. This means that, where possible, the combustion engine is "masked" by an acceleration process. Engine restarts during constant-speed driving are avoided.

[0018] According to the prior art, the combustion engine restarts if the charge level of the high-voltage battery drops too low. In a further advantageous embodiment of the invention, the restart thresholds, which depend on the charge level of the high-voltage battery, are adjusted so that the combustion engine does not restart during constant-speed driving. Instead, the combustion engine restarts early or late by means of a masking mechanism during acceleration. This means that the switch from a charge-depleting strategy (discharging the high-voltage battery when it has a sufficient charge level) to a charge-sustaining strategy (maintaining the low charge level of the high-voltage battery) is deliberately shifted to achieve a more customer-friendly and efficient operating strategy.

[0019] Preferably, for acoustic and dynamic reasons, the combustion engine is started at the beginning of an acceleration process and not only after exceeding the currently valid e-driving speed limit, i.e., potentially under high load of the combustion engine, if the expected speed profile suggests that one of these two limits will be exceeded or that the battery will discharge.

[0020] In a further advantageous embodiment of the invention, load-dependent starting of the combustion engine is prevented if the expected speed profile remains consistently below the currently valid electric driving speed limit (e.g., due to a continuous speed limit significantly below the currently valid electric driving speed limit or an upcoming red light). This situation-dependent start robustness thus prevents the combustion engine from briefly starting during short load demands from the driver and therefore enhances the electric driving experience from the customer's perspective.

[0021] In a further advantageous embodiment of the invention, the temporary shutdown of the combustion engine during short vehicle stops (e.g. before stop signs, prediction of a short remaining red phase of the traffic light, etc.) is prevented if the low charge level of the high-voltage storage device does not allow electric driving.

[0022] A further advantageous embodiment of the invention provides for an early start of the combustion engine upon reliable detection of an incipient overtaking maneuver (e.g., with the aid of a turn signal, tractor detection, a relatively slow-moving vehicle in front in low traffic density, etc.). The aim is to increase the response and dynamics of the overtaking maneuver.

[0023] According to the invention, the control unit is designed such that the starting of the combustion engine is postponed to a later acceleration process if, due to the expected change in operating strategy modes from Charge Depleting (discharging the high-voltage storage) to Charge Sustaining (maintaining the charge state or charging the high-voltage storage), a starting of the combustion engine is necessary anyway, which would otherwise fall within a constant-speed driving period.

[0024] The invention offers the following advantages: 1) Enhanced driving experience in e-mode through • Extension of the driving phase in E-mode (by reducing load-related start-up in expected low-load situations) • Energy optimization • Initial robustness 2) Improvement of acoustics and customer comprehensibility of the operating strategy through • Avoidance of briefly switching off or restarting the combustion engine • Reduction of lay-down vibrations • Starting robustness (in the lower speed band) • Reduction of start-up and shutdown processes in customer operations • Avoidance of start-up processes during constant speed driving (e.g., by means of masking during accelerations) • Prioritizing starts before high-load situations (avoiding high coupling speed) 3) Reduction in fuel consumption or increase in range through • Prevention of unnecessary electric-mode driving under expected high load • Reduction of start-up losses by avoiding unnecessary lay-up operations • Increased use of recuperation energy by switching off the combustion engine early 4) Improved athleticism or response through • Avoidance of only short-term storage procedures before high-load situations • Starting the combustion engine early before high load demands

[0025] The drawing illustrates exemplary embodiments of the invention. Fig. 1. the essential functional components required for carrying out the operating procedure underlying the tax system, Fig. Example 1: First situation in the near future: acceleration, Fig. Example 2: first situation in the near future: turning maneuver or curve, Fig. Example 3: First situation in the near future: Delay until just above the lower e-driving speed limit, Fig. Example 4: first situation in the near future: acceleration; second situation in the near future: battery discharged, Fig. Example 5: Second situation in the near future: Delay down to below the lower e-driving speed limit, Fig. Example 6: first situation in the near future: no increase in expected speed.

[0026] In Fig. 1 represents a vehicle-integrated sensor system 1, for example, consisting of a camera and a front radar for detecting traffic signs and vehicles ahead, as well as a navigation system 2 for traffic guidance detection and congestion forecasting. Sensor system 1 can also include sensors for traffic light detection or prediction. Alternatively, traffic light prediction can be implemented or supported by a learning backend system. Traffic light prediction can be incorporated into the determination of the expected speed and load profile. The data from these two systems 1 and 2 are input signals to a prediction module 3. The prediction module 3 is used to determine an expected speed profile v. eas well as a load profile based on this data, and can be a functional module of an electronic control unit not shown in detail here. For example, an accelerator pedal sensor 4 is provided to record driver interaction, the output signal FP of which reflects the driver's current load request or load request profile. The output signal FP and the expected speed profile v determined in the predictive module 3 e These are input signals of a control function module 5, which is also part of the control unit. The control function module 5 preferably contains a software program product through which the operating strategy of the control system according to the invention is implemented.

[0027] The operating strategy is based on the following state of the art: The currently valid e-vehicle speed limit will be... MaxIf the actual speed falls below the set speed limit, the combustion engine is switched off according to current technology. If the currently valid electric vehicle speed limit (eV) is exceeded... Max If the actual speed is exceeded, the combustion engine restarts immediately according to the prior art. The same applies if the start / stop limits, defined as dependent on speed and load state, are exceeded or fallen below due to the driver's load request. The invention allows the expected speed profile v e as well as the expected load profile with regard to these previously rigidly set limits. According to the invention, the two situations S1 and S2 that lie in the near future can lead to a shift and / or the ignoring of these previously situation-independent predefined e-driving speed and load limits. Details of this operating strategy are provided with reference to the examples in the Fig. 2 to 7 explained:

[0028] In the Fig. 2 to 7 are expected velocity profiles v starting from a current situation S0 e The diagram illustrates a first situation S1 in the near future and possibly also a second situation S2 in the near future. These three situations lie within a defined foresight horizon of, for example, approximately 2 km. In each figure, the state-of-the-art operating strategy is shown at the top, based on the velocity profiles v. e The image shows a superimposed representation of a started or shut-down combustion engine. The corresponding operating strategy according to the invention is shown below. The solid line indicates the velocity v. e with the combustion engine started, and using the dashed line, the speed v is shown in each case. e Shown with the combustion engine removed.

[0029] According to Fig. 2. The current situation S0 is a purely electric constant speed driving (v e (=const.) according to the speed limit (50 km / h) below the currently valid e-vehicle speed limit. Max,CD , i.e., with the combustion engine switched off. The first situation S1, indicated by the detection of an imminent town limit sign, suggests an acceleration to approximately 100 km / h. Situation S2, indicated by the absence of new data, suggests a maintenance of the speed reached after acceleration. At time FP+, the driver issues a load request. According to the invention, if acceleration to a value above the currently valid electric vehicle speed limit (eV) is expected, the system will then... Max,CD The combustion engine is started as soon as the load demand increases. According to the current state of the art, this only occurs after exceeding the currently valid electric vehicle speed limit. Max,CDor a start-up is initiated after a speed-dependent load limit is exceeded. With this example according to the invention, an earlier start-up (=reduction of the usual a / v characteristic curve) is performed to improve the response behavior. At the same time, the start-up comfort is significantly improved, since the coupling of the combustion engine takes place under a considerably lower load and speed.

[0030] According to Fig. 3 is the current situation S0, a constant speed outside the town at 100 km / h above the currently valid e-vehicle speed limit. Mmax,CD, i.e., with the combustion engine running. The first situation S1, for example, indicates an upcoming turning maneuver or curve, i.e., a brief deceleration, through the detection of a curve warning sign or the evaluation of map information regarding the curve radius in the near future. Situation S2, through (still) valid speed limits, indicates a return to the current situation S0. According to the invention, the shutdown of the combustion engine is now prevented (shutdown prevention AV) because only a brief drop below the currently valid electric vehicle speed limit eV is expected. Max,CD This is expected. Compared to the prior art, which involves briefly disengaging the combustion engine, this example according to the invention primarily increases comfort and dynamics.

[0031] According to Fig. 4 is the current situation S0, a constant speed outside the town at 100 km / h above the currently valid e-vehicle speed limit. Max,CD , i.e., with the combustion engine running. The first situation S1, for example, indicates a prolonged reduction in speed down to below the eV driving speed limit, due to the detection of a town sign. Max,CD The new level of expected speed will not be exceeded again in a possible situation S2. According to the invention, the combustion engine is switched off here when deceleration is expected to fall below the electric vehicle speed limit (eV). Max,CD or eV Max,CS The FP (premature deceleration) process is already initiated with the removal of the load, even before the electric vehicle speed limit is reached (early deceleration FA). According to current technology, the eV (electric vehicle) process only begins after the electric vehicle speed limit has been reached. Max,CD or eV Max,CSThe combustion engine is disengaged. This example according to the invention increases efficiency.

[0032] According to Fig. 5 is the current situation S0, a purely electric constant speed drive according to the speed limit of 30 km / h, i.e. below the eV driving speed limit. Max,CSFor the operating state of charge sustaining. The first situation, S1, indicates an acceleration to approximately 70 km / h due to the detection of an imminent speed limit of 70 km / h. Situation S2, due to the absence of new data, suggests maintaining the speed reached after acceleration. After the speed increase, a change in the operating strategy from Charge Depleting CD (i.e., preferentially electric driving) to Charge Sustaining CS (maintaining the charge state) is expected in situation S2 due to a low charge level in the high-voltage battery. According to the prior art, this change is associated with the combustion engine starting independently of load and speed. According to the invention, the combustion engine is now started at the very beginning of an acceleration process.The effect is an advance CSV of the transition from the discharge process CD to the charging process CS, in order to "mask" the initial start during acceleration. This improves traceability and comfort compared to the state of the art, which, according to this example, involves an initial start during constant speed driving.

[0033] According to Fig. 6 is the current situation S0, a purely electric constant speed drive outside the town at 70 km / h between the e-driving speed limits eV Max,CD and eV Max,CSThe first situation, S1, triggers a restart according to the state of the art, as a change in the operating strategy from Charge Depleting CD (i.e., prioritizing electric driving) to Charge Sustaining CS (maintaining the charge state) is imminent due to a low charge level in the high-voltage battery. The second situation, S2, indicates, for example, through the detection of the 30 km / h speed limit, a longer-lasting reduction in speed below the new eV driving speed limit valid in Charge Sustaining CS. Max,CS According to the invention, the combustion engine is started without a load request, which is triggered by the upcoming change in the currently valid electric vehicle speed limit. Max,CD on eV Max,CSThe transition from DC to CS is postponed to a later point in time (postponement of the CSV transition from DC to CS to a later acceleration process). The resulting advantage is an enhanced e-driving experience, improved customer comfort, and greater transparency of the operating strategy from the customer's perspective.

[0034] According to Fig. 7. The current situation S0 is a purely electric constant speed drive outside the town, for example at 60 km / h, significantly below the currently valid eV driving speed limit. Max,CD (or eV) Max,CSNo increase in the expected speed is predicted for the preceding section of the route (situations S1 and S2). If the driver requests a short-term load peak LS, for example, to pass through a yellow traffic light phase, the combustion engine starts and shuts off again after a short time, according to the current state of the art, if the speed-dependent load limit is exceeded. According to the invention, situation-dependent start-up robustness, achieved by raising the load-related start-up limits to a higher level, prevents this short-term start-up, provided it is foreseeable that the load request will not be prolonged. Very high load requests and exceeding the currently valid electric driving speed limit will still result in the combustion engine starting.The advantages of situation-dependent start robustness include increased efficiency and an improved e-driving experience, as well as a reduction in the number of combustion engine starts during customer operation. Fig. Figures 1-7 show only examples of an expected speed profile that can result from all the information mentioned above. Furthermore, other examples, such as the early restart of the combustion engine before a detected overtaking maneuver or a shutdown prevention device during brief stops (stop sign, traffic light with a short remaining red phase, etc.), are not shown separately.

[0035] Control system with at least one electronic control unit for controlling an internal combustion engine in a hybrid vehicle

Claims

[1] Control system with at least one electronic control unit (3, 5) for controlling an internal combustion engine in a hybrid vehicle, wherein the control unit is designed to receive input signals for acquiring data for recognizing a current situation (S0) and for recognizing at least one situation (S1, S2) prevailing in the near future with respect to an expected speed profile (v e ) evaluates and that it depends at least on the expected velocity profile (v e ) controls the starting and stopping of the combustion engine, characterized by , that the control unit is designed in such a way that the starting or stopping of the combustion engine depends on dynamically shifted e-driving speed limits (eV) Max,CD , eV Max,CS) is feasible, and the control unit is designed in such a way that starting the combustion engine is brought forward to an acceleration process or postponed if, due to an expected change in operating strategy mode from Charge Depleting (discharging the high-voltage storage) to Charge Sustaining (maintaining the charge state or charging the high-voltage storage), starting the combustion engine is required anyway, which would otherwise fall into a constant-speed driving phase. [2] Tax system according to claim 1, characterized by , that the control unit is designed in such a way that it additionally records at least one input signal (FP) for evaluating a load profile and / or other driver interaction and that it also controls the starting or stopping of the combustion engine depending on the driver interaction. [3] Tax system according to one of the preceding claims, characterized bythat the control unit is designed in such a way that the starting or stopping of the combustion engine deviates from specified e-driving speed limits (eV) Max,CD , eV Max,CS ) and / or predefined e-driving load start limits are feasible. [4] Tax system according to one of the preceding claims, characterized by that the control unit is designed in such a way that, in the event of expected acceleration to a value above the currently valid electric vehicle speed limit (eV), Max,CD or eV Max,CS ) the combustion engine is started as soon as a load request (FP+) increases. [5] Tax system according to one of the preceding claims, characterized by , that the control unit is designed in such a way that the shutdown of the combustion engine is prevented if there is only a brief drop below the currently valid electric vehicle speed limit (eV) Max,CD or eV Max,CS) is expected.

6. Tax system according to one of the preceding claims, characterized by that the control unit is designed in such a way that the shutdown of the combustion engine in the event of expected deceleration down to below the currently valid e-driving speed limit (eV) Max,CD or eV Max,CS ) already with a load removal (FP-) even before falling below the currently valid e-driving speed limit (eV) Max,CD or eV Max,CS ) is carried out.

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