Abstract
In a control system having at least one electronic control unit for controlling an internal combustion engine in a hybrid vehicle, the control unit is designed in such a way that it evaluates input signals for detecting data for identifying a current situation and for identifying at least one situation prevailing in the near future with regard to an expected speed and load curve. The control system controls, in a manner that is adaptive to the situation, the restart and shutoff of the internal combustion engine.
Claims
1. A control system, comprising: an electronic control unit that controls an internal combustion engine in a hybrid vehicle, wherein the control unit is operatively configured to: evaluate input signals for detecting data identifying a current situation and for detecting at least one future situation forecast in a near future with respect to an expected speed curve, control a restart and a shutoff of the internal combustion engine in the hybrid vehicle as a function of the expected speed curve, and carry out the restart or shutoff of the internal combustion engine in a manner deviating from predetermined E-driving speed limits and/or predetermined E-driving load limits.
2. The control system according to claim 1, wherein the control unit is further operatively configured to: additionally detect at least one input signal for evaluating a load curve and/or another driver interaction, and control the restart or shutoff of the internal combustion engine also as a function of the driver interaction.
3. The control system according to claim 1, wherein the control unit is further operatively configured such that: a restart of the internal combustion engine is already advanced or shifted to an acceleration process when through an expected change of operating strategy modes from charge depleting to charge sustaining in any case a restart of the internal combustion engine is necessary, which otherwise falls chronologically into a steady speed.
4. The control system according to claim 1, wherein the control unit is further operatively configured to: carry out the restart or shutoff of the internal combustion engine depending on dynamically shifted E-driving speed limits and/or E-driving load limits.
5. The control system according to claim 1, wherein the control unit is further operatively configured to: with an expected acceleration to a value above a currently valid E-driving speed limit, carry out a restart of the internal combustion engine as soon as there is an increase of a load demand.
6. The control system according to claim 1, wherein the control unit is further operatively configured to: prevent the shutoff of the internal combustion engine when an actual speed is expected to fall below the currently valid E-driving speed limit for only a short duration.
7. The control system according to claim 1, wherein the control unit is further operatively configured to: with an expected deceleration to below the currently valid E-driving speed limit, carry out the shut off of the internal combustion engine as soon as there is a load relief before the actual speed falls below the currently valid E-driving speed limit.
8. An electronic control unit of a control system that controls an internal combustion engine in a hybrid vehicle, comprising: a processor and associated program memory having stored therein program code sections that, when executed, carry out a control to: evaluate input signals for detecting data identifying a current situation and for detecting at least one future situation forecast in a near future with respect to an expected speed curve, control a restart and a shutoff of the internal combustion engine in the hybrid vehicle as a function of the expected speed curve, and carry out the restart or shutoff of the internal combustion engine in a manner deviating from predetermined E-driving speed limits and/or predetermined E-driving load limits.
9. A method of controlling a restart and a shutoff of an internal combustion engine in a hybrid vehicle, the method comprising the steps of: evaluating a current situation and at least one situation forecast ahead of the vehicle; at least with regard to an expected speed curve as a function of a driver interaction and/or of a charge state of a high-voltage reservoir of the hybrid vehicle, controlling the restart and the shutoff of the internal combustion engine in a defined manner deviating from predetermined E-driving speed limits and/or predetermined E-driving load limits.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a schematic diagram of the essential necessary functional components for carrying out the operating method forming the basis of the control system.
(2) FIG. 2 graphically illustrates example 1: first situation in the near future: acceleration.
(3) FIG. 3 graphically illustrates example 2: first situation in the near future: turning-off procedure or curve.
(4) FIG. 4 graphically illustrates example 3: first situation in the near future: deceleration up to shortly above the lower E-driving speed limit.
(5) FIG. 5 graphically illustrates example 4: first situation in the near future: acceleration; second situation in the near future: discharging battery.
(6) FIG. 6 graphically illustrates example 5: second situation in the near future: deceleration up to below the lower E-driving speed limit.
(7) FIG. 7 graphically illustrates example 6: first situation in the near future: no increase in the expected speed.
DETAILED DESCRIPTION OF THE DRAWINGS
(8) In FIG. 1, a sensor system 1 belonging to the vehicle is illustrated, consisting for example of a camera and a front radar for the recognition of traffic signs and preceding vehicles, as is a navigation system 2 for traffic routing identification and prediction of traffic jams. The sensor system 1 can also comprise, for example, a sensor technology for identifying traffic lights or predicting traffic lights. Alternatively, the traffic light forecast can also be realized or respectively supported by use of a learning backend system. A traffic light forecast can be integrated into the determining of the expected speed and load curve. The data of these two systems 1 and 2 are input signals of a forecast module 3. The forecast module 3 is configured for determining an expected speed curve v.sub.e and a load curve on the basis of these data, and can be a function module of an electronic control unit which is not illustrated in further detail here. For the detection of the driver interaction, an accelerator pedal sensor 4 is provided here for example, the output signal FP of which reproduces the current load demand or respectively the load demand curve of the driver. The output signal FP and the expected speed curve v.sub.e determined in the forecast module 3 are input signals of a control function module 5, which is likewise part of the control unit. In the control function module 5 preferably a software program product is contained, by which the operating strategy of the control system according to the invention is realized.
(9) The operating strategy builds on the following prior art. When the currently valid E-driving speed limit eV.sub.Max is fallen below by the actual speed, according to the prior art the internal combustion engine is shut off. When the currently valid E-driving speed limit eV.sub.Max is exceeded by the actual speed, according to the prior art the internal combustion engine is restarted immediately. The same applies on exceeding or respectively falling below restart or respectively shutoff limits defined in a speed-dependent and charge state-dependent manner through the load demand on the part of the driver. Through the invention, the expected speed curve v.sub.e and the expected load curve are considered with regard to these hitherto rigidly set limits. The two situations S1 and S2 lying in the near future here can lead, according to the invention, to the shifting and/or ignoring of these hitherto situation-independent predetermined E-driving speed limits and load limits. Details concerning this operating strategy are explained by way of the examples according to FIGS. 2 to 7.
(10) In FIGS. 2 to 7, proceeding from a current situation S0, speed curves v.sub.e to be expected are illustrated for a first situation S1 in the near future and possibly also for a second situation S2 in the near future. These three situations lie in a defined forecast horizon of, for example, approximately 2 km. In each figure, at the top the operating strategy according to the prior art is illustrated by means of the speed curves v.sub.e with superimposed illustration of a restarted or shut off internal combustion engine. At the bottom, in an analogous manner, the operating strategy according to the invention is respectively illustrated. Here, by means of the continuous line, respectively the speed v.sub.e with a restarted internal combustion engine is illustrated, and by means of the dashed line respectively the speed v.sub.e with a shut off internal combustion engine is illustrated.
(11) According to FIG. 2, the current situation S0 is a purely electric steady speed (v.sub.e=const.), according to the preset speed (50 km/h), below the currently valid E-driving speed limit eV.sub.Max, CD, i.e. with a shut off internal combustion engine. The first situation S1 is indicative, through the detection of a city limit sign, in the near future of an acceleration to approximately 100 km/h. Situation S2 is indicative, through the absence of new data, of a maintaining of the speed reached after the acceleration. At the moment FP+, a load demand is issued by the driver. According to the invention, with an acceleration to be expected to a value above the currently valid E-driving speed limit eV.sub.Max, CD, a restart of the internal combustion engine is carried out already with an increase of the load demand. According to the prior art, a restart is carried out only after exceeding the currently valid E-driving speed limit eV.sub.Max, CD or after exceeding a speed-dependent load limit. With this example according to the invention, an advanced restart (=lowering of the usual a/v characteristic) is carried out, in order to improve the response performance. At the same time, the restart comfort is distinctly improved, because the connecting of the internal combustion engine takes place under a distinctly lower load and rotation speed.
(12) According to FIG. 3, the current situation S0 is a steady speed outside the built-up area at 100 km/h, which is above the currently valid E-driving speed limit eV.sub.Max, CD, i.e. with an activated internal combustion engine. The first situation S1 is indicative, for example through the recognition of a warning sign for a bend or through evaluation of map information with regard to the bend radius, in the near future of a turning procedure or a bend, therefore a brief deceleration. Situation S2 is indicative, through (still) valid speed limits, of a return to the current situation S0. According to the invention, the shutoff of the internal combustion engine is now prevented (switch-off prevention AV), because only a brief falling below of the currently valid E-driving speed limit eV.sub.Max, CD is expected. Through this example according to the invention, compared to the prior art, which provides a brief shutoff of the internal combustion engine, above all the comfort and the dynamics are increased.
(13) According to FIG. 4 the current situation S0 is a steady speed, outside the built-up area at 100 km/h, which is above the currently valid E-driving speed limit eV.sub.Max, CD, i.e. with an activated internal combustion engine. The first situation S1 is indicative, for example through the recognition of a town sign, of a longer-lasting speed reduction to below the E-driving speed limit eV.sub.Max, CD. The new level of the expected speed is not exceeded again in a possible situation S2. According to the invention, the shutoff of the internal combustion engine at a deceleration, which is to be expected, to below the E-driving speed limit eV.sub.Max, CD or respectively eV.sub.Max, CS is already carried out with the load relief FP still before the falling below of the E-driving speed limit (premature shutoff FA). According to the prior art, a shutoff of the internal combustion engine is carried out only after falling below of the E-driving speed limit eV.sub.Max, CD or respectively eV.sub.Max, CS. Through this example according to the invention, the efficiency is increased.
(14) According to FIG. 5 the current situation S0 is a purely electric steady speed according to the preset speed 30 km/h, therefore below the E-driving speed limit eV.sub.Max, CS, for the operating state to keep charge state (charge sustaining). The first situation S1 is indicative, through the identifying of a speed limit of 70 km/h in the near future, of an acceleration to approximately 70 km/h. Situation S2 is indicative, through the absence of new data, of a maintaining of the speed reached after the acceleration. After the speed increase has taken place, in situation S2 an operating strategy change from charge depleting CD (i.e. preferably electric driving) to charge sustaining CS (keeping charge state) owing to a low charge state of the high-voltage reservoir is to be expected. This change, according to the prior art, is connected with a restart of the internal combustion engine independent of load and speed. According to the invention, a restart of the internal combustion engine is carried out already at the start of an acceleration process. The effect is a pre-shifting CSV of the transition from the discharging process CD to the charging process CS, in order to mask the restart in the acceleration. Hereby, compared to the prior art, which according to the example here provides a restart during the steady speed, the reproducibility and the comfort are increased.
(15) According to FIG. 6 the current situation S0 is a purely electric steady speed outside the built-up area at 70 km/h between the E-driving speed limits eV.sub.Max, CD and eV.sub.Max, CS. The first situation S1 provides, according to the prior art, for a restart, because a change of the operating strategy from charge depleting CD (i.e. preferably electric driving) to charge sustaining CS (keeping charge state) is imminent owing to a low charge state of the high-voltage reservoir. The second situation S2 is indicative, for example, through the identifying of the speed limit 30 km/h, of a longer-lasting speed reduction below the valid new E-driving speed limit eV.sub.Max, CS in the charge sustaining CS. According to the invention here without the presence of a load demand, the restarting of the internal combustion engine, which is to be attributed to the upcoming change of the currently valid E-driving speed limit from eV.sub.Max, CD to eV.sub.Max, CS, is shifted to a later point in time (shifting CSV of the transition from DC to CS to a later acceleration process). The advantage resulting herefrom is an increase of the E-driving experience, of customer comfort and an increased reproducibility of the operating strategy from the customer's point of view.
(16) According to FIG. 7, the current situation S0 is a purely electric steady speed outside the built-up area at, for example 60 km/h, distinctly below the currently valid E-driving speed limit eV.sub.Max, CD (or respectively eV.sub.Max, CS). Also on the section lying ahead (situation S1 and S2) no increase to the expected speed is predicted. When the driver demands a brief load peak LS, for example for driving over a yellow traffic light phase, according to the current prior art on exceeding the speed-dependent load limit the internal combustion engine restarts and shuts off again after a short period of time. According to the invention, a situation-dependent restart robustness prevents this brief restart by means of raising the restart limits, which are due to load, to a higher level, in so far as it is foreseeable that a longer load request is not concerned. Very high load requests and an exceeding of the current valid E-driving speed limit also still bring about a restart of the internal combustion engine. The advantages of the situation-dependent restart robustness are an increase in the efficiency and of the E-driving experience and a reduction of the number of internal combustion engine restarts in customer operation.
(17) FIGS. 1-7 only show examples of an expected speed curve, which can result from all information mentioned in the introduction. In addition, further examples, such as a premature restart of the internal combustion engine before an identified overtaking procedure or a shutoff preventer in the case of brief stops (stop sign, traffic light with short remaining red phase, etc.) are not presented separately.
(18) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
