Method for controlling the internal combustion engine of a motor vehicle and device for controlling the internal combustion engine of a motor vehicle

Abstract

Method for controlling the internal combustion engine (4) of a motor vehicle during the operation of the motor vehicle, wherein the internal combustion engine (4) has at least two operating modes in which different torque ranges are provided, and the control has a switching function for switching the internal combustion engine between the at least two operating modes, comprising the steps: Performing route forecasting during operation to determine route data for upcoming track sections, Predicting the torque requirement for upcoming track sections based on track data, The switching function for changing the internal combustion engine from a first operating mode to at least the second operating mode for an upcoming section of track may only be activated if the track forecast for the upcoming section shows that the operating point of the internal combustion engine lies within a torque range for at least a predetermined period of time, which covers the torque requirement predicted for this section of track by at least the second operating mode. characterized by the fact that the operating modes are realized through different compression ratios of the internal combustion engine.

Description

[0001] The invention relates to a method for controlling the internal combustion engine of a motor vehicle according to the preamble of claim 1 and to a corresponding device according to the preamble of claim 9.

[0002] Cylinder deactivation, also known by the abbreviation CYC, is a technology for internal combustion engines in which one or more cylinders are deactivated whenever low torque is required. This technology has been known for many years and has long been used in series production, particularly in gasoline engines with a high number of cylinders, such as 8 or 12. Examples of cylinder deactivation can be found in 8- and 12-cylinder engines from manufacturers like Audi, BMW, and Daimler, where usually half of the cylinders are deactivated simultaneously. Cylinder deactivation is also conceivable for diesel engines, but as far as is known, it has not yet been implemented in series production.

[0003] The advantage of cylinder deactivation is that the engine consumes less fuel when operating with fewer cylinders. This technology was first introduced into series production in a Volkswagen 4-cylinder engine in the Golf 7, which was launched in 2012.

[0004] A disadvantage of dual-clutch transmission (DC-CT) is that fuel consumption increases significantly for a period of several hundred milliseconds during the switching process, and the overall fuel consumption potential decreases considerably with frequent switching. This is because the torque must be adjusted between the operating states with full and half cylinders by means of efficiency-reducing ignition timing adjustments to avoid discomfort caused by jerking. Therefore, switching should be performed as infrequently as possible.

[0005] German patent application DE 10 2010 033 606 A1 describes an engine control system for a motor vehicle with the capability of cylinder deactivation. Furthermore, the engine control system includes a road gradient module, which detects the gradient of a road ahead of the vehicle. If the detected gradient exceeds a predefined threshold and cylinder deactivation is active, the deactivated cylinders are reactivated to provide sufficient torque to overcome the road gradient. The increased fuel consumption during the cylinder deactivation switchover is not taken into account.

[0006] From US patent 8,401,733 B2, a powertrain unit for a motor vehicle with a control unit is known, wherein the control unit has a route-specific learning mode that can be activated at the driver's request. The learned information includes, as a function of the route, for example, braking and acceleration data, steering angle information, driver-side torque requests, and longitudinal and lateral acceleration data, whereby the assignment of the data to the route is carried out by means of navigation, for example, via GPS or odometry. Based on the acquired data, after completion of the learning phase, the operation of the powertrain unit along the route is optimized, taking into account the driver's behavior. This optimization can, for example, be aimed at improving fuel efficiency by performing gear changes at low engine speeds or deactivating cylinders when torque demand is low.When driving the learned route again, the optimized operating parameters of the powertrain unit can be used. The increased fuel consumption during the switching of the ZAS (central locking system) is not taken into account here either.

[0007] The torque of a gasoline engine can also be adjusted without efficiency-reducing ignition timing measures if, for example, rapid charge adjustment options such as rapid lift adjustment of the intake valves are available, or if a rapid change in torque is possible by changing the fuel quantity. However, these options involve additional costs and are therefore not available for the majority of gasoline engines currently in series production for mass-market vehicles.

[0008] Further methods and devices for controlling a motor vehicle are known from DE 11 2012 001 021 T5, DE 10 2009 038 110 A1 and DE 10 2010 003 757 A1.

[0009] The invention is therefore based on the objective of reducing the frequency of switching operations when using cylinder deactivation and avoiding the associated increased fuel consumption.

[0010] The problem is solved by a method for controlling the internal combustion engine of a motor vehicle with the features of claim 1 and by a corresponding device with the features of claim 9. Preferred embodiments of the invention are the subject of the dependent claims.

[0011] The inventive method for controlling the internal combustion engine of a motor vehicle during driving operation, wherein the internal combustion engine has at least two operating modes in which different torque ranges are provided, and wherein the control of the internal combustion engine has a switching function for switching the internal combustion engine between the at least two operating modes, comprises the following steps - Conducting a route forecast during operation to determine route data for upcoming track sections, - Predicting the torque requirements of upcoming road sections based on the road data, - Activating the switching function to change the internal combustion engine from a first operating mode to at least the second operating mode for an upcoming section of track only if it is apparent from the track forecast for the upcoming section of track that the operating point of the internal combustion engine lies for at least a predetermined period of time in a torque range that covers the torque requirement predicted for this section of track by at least the second operating mode.

[0012] The basic idea is to reduce the number of switching operations between the internal combustion engine's operating modes by only switching when the engine's operating point will remain within a suitable range for a sufficiently long period. In other words, in the case of cylinder deactivation, a switch from full to half cylinder operation only occurs if the torque demand of the upcoming section of the route remains within the low-load operating range intended for half cylinder operation for a sufficiently long time. The same applies to switching from half to full cylinder operation; a switch to full cylinder operation only occurs when high loads are required for a sufficiently long period.

[0013] Internal combustion engines with different operating modes, between which switching is possible, can be implemented in several ways. One implementation is the previously mentioned cylinder deactivation, in which the engine can be operated, for example, with a full number of cylinders and with a reduced number of cylinders. In the invention, the internal combustion engine is operated with different compression ratios, resulting in different load ranges, and switching between these different compression ratios is possible. FSI engines can be operated in lean-burn and homogeneous combustion modes with different load ranges, and the switching occurs between lean-burn and homogeneous combustion. Finally, one operating mode in the partial load range can be implemented using a so-called HCCI combustion process (Homogeneous Charge Compression Ignition), and the other operating mode through normal engine operation.There too, switching between modes results in increased fuel consumption, and reducing the number of switching operations would lower consumption.

[0014] Preferably, the specified time duration is greater than or equal to 5 seconds. If the time duration is shorter, the switching process between operating modes, especially in cylinder deactivation mode, is not worthwhile in terms of fuel efficiency.

[0015] In the case of cylinder deactivation, cylinder deactivation is preferably carried out when, for the specified period, the torque requirement is in the operating range of the internal combustion engine with a reduced number of active cylinders, and deactivated cylinders are activated when, for the specified period, the torque requirement is in the operating range of the internal combustion engine with a full number of active cylinders.

[0016] Preferably, the route forecast provides a prediction of the expected route and a prediction of the expected speed, from which a prediction of the torque requirement for the drive during the journey is derived.

[0017] Route prediction is preferably performed based on information or route data from a navigation system, adaptive cruise control (ACC) system, Car2X system, a digital map, and / or internet-based route data. Route data for the upcoming route includes, for example, static data such as traffic signs, speed limits, and the topography of the road segment ahead, as well as dynamic environmental data such as traffic and road conditions like slipperiness. Furthermore, route data includes the vehicle's environmental perception data and the desired or target speed of the vehicle for the upcoming road segment, i.e., the anticipated driving speed.

[0018] The switching operations were preferably carried out at the beginning of a phase with reduced torque requirement and at the beginning of a phase with increased torque requirement for the specified duration.

[0019] The device according to the invention for controlling the internal combustion engine of a motor vehicle during driving operation, wherein the device is set up and designed to carry out the method described above, and wherein the internal combustion engine has at least two operating modes in which different torque ranges are provided, comprises: - a device for performing a switching function between at least two operating modes, - a device for carrying out a route forecast to determine route data of upcoming route sections, - a forecasting device for predicting the torque requirements of upcoming track sections based on the track data, wherein - the switching function between the first operating mode and at least a second operating mode for an upcoming section of track is only activated if it is apparent from the track forecast of the upcoming section that the operating point of the internal combustion engine lies for a specified period of time in a range of the second operating mode that covers the torque requirement predicted for this section of track.

[0020] Possible operating modes include the previously mentioned cylinder deactivation, compression switching, lean / homogeneous operation and HCCI operation.

[0021] Preferably, the route prediction system includes a navigation system, environmental detection, a Car2X system, a digital map, and / or access to internet-based route data. In particular, the route prediction system may have access to a digital map. The digital map may be an integral part of the navigation system, or the map information may be downloaded from the internet.

[0022] Route prediction technology can therefore be provided by information and algorithms currently available in the vehicle, with these information sources allowing for an estimation of the likely route traveled, an estimation of the likely vehicle speed, and the resulting torque requirement for the drive system during travel. In automated vehicles, the vehicle speed can not only be estimated, but the optimal target speed calculated in the control units is directly set by them.

[0023] This makes it possible to determine in advance which sections of the route offer favorable conditions for cylinder deactivation or switching; in other words, when sufficiently long high-load operating phases exist for the full number of cylinders or sufficiently long low-load phases for half the number of cylinders. The switching processes are preferably carried out at the beginning or end of these driving phases. Exceptions must be ensured in the event of sudden deviations between the driver's desired torque and the estimated torque requirement.

[0024] Compared to conventional combustion engine operation with cylinder deactivation, combining this with route prediction reduces the frequency of switching between high and low cylinder operation, thereby lowering fuel consumption. The increased fuel consumption associated with cylinder switching is therefore eliminated.

[0025] A preferred embodiment of the invention is explained below with reference to the drawing. This shows Fig. 1 A block diagram of the device for controlling the internal combustion engine of a motor vehicle.

[0026] The in Fig. The device shown in Figure 1 for controlling the internal combustion engine of a motor vehicle comprises a device 1 for performing a route prediction, which, based on supplied route data and information, performs a prediction of upcoming route segments. The route data and information about the upcoming route segments supplied to the route prediction device 1 are, in the example of the Fig.1. The route is generated by a navigation system 5, a digital map 6, an environmental sensing system 7, and an internet connection 8. This list of information and route data-generating devices is only exemplary. For example, the digital map 6 can be an integral part of the navigation system 5, or it can be accessed via the internet 8. The environmental sensing system generates information about the vehicle's immediate surroundings, using, for example, radar or camera systems. ACC systems can thus generate the desired environmental data. Current traffic data and road condition data, such as road slipperiness, can be fed into the route prediction system via the internet or a suitable infotainment system.

[0027] Generally, route data for upcoming road segments can be categorized into static map data, dynamic environmental data, and vehicle environment data. Static map data includes, for example, traffic signs, speed limits, and topographic data such as gradients, inclines, curves, and the overall road profile of upcoming segments. Dynamic environmental data encompasses traffic and the condition of upcoming road segments, with the condition of the road segment including information such as road surface slipperiness, i.e., the coefficient of friction. Vehicle environment data relates to the geometry of the immediate surroundings and any obstacles within them, such as other vehicles and their speeds, as well as the vehicle's own speed.

[0028] The aforementioned route data of upcoming route sections are fed to a forecasting device 2, in which an estimate or forecast of the required torque for the upcoming route section(s) is carried out.

[0029] The estimated required torque is fed to a switching device 3 for switching an internal combustion engine 4, wherein the internal combustion engine 4 has at least two operating modes between which it can switch depending on the load requirement. Furthermore, the results of the route forecast 1 are fed to the switching device 3. Based on the route data of the upcoming route segment and the torque estimate, the switching device 3, which is aware of the current first operating mode of the internal combustion engine 4, can check whether the operating point of the internal combustion engine 4 lies within a torque range for at least a predetermined period of time that covers the torque requirement predicted for this route segment by the at least second operating mode. If this is the case, the switching device 3 causes the operating mode to be switched from the current first operating mode to the at least second operating mode.

[0030] Using the example of cylinder deactivation, where the internal combustion engine would have the operating modes "full number of cylinders" and "reduced number of cylinders," a switch from "full number of cylinders" to "reduced number of cylinders" occurs when the upcoming section of road can be driven with a sufficiently low load requirement for a sufficiently long period. If it is foreseeable that a high-load operating phase will be required for a predetermined period of time on an upcoming section of road, for example, due to a road incline, the system switches from "reduced number of cylinders" to "full number of cylinders." Reference symbol list 1. Setting up route forecasting 2 Forecasting device 3 switching device operating modes 4 Internal combustion engines with different operating modes 5 Navigation 6 digital card 7. Environmental detection 8 Internet access

Claims

[1] Method for controlling the internal combustion engine (4) of a motor vehicle during the operation of the motor vehicle, wherein the internal combustion engine (4) has at least two operating modes in which different torque ranges are provided, and the control has a switching function for switching the internal combustion engine between the at least two operating modes, comprising the steps: Performing route forecasting during operation to determine route data for upcoming track sections, Predicting the torque requirement for upcoming track sections based on track data, The switching function for changing the internal combustion engine from a first operating mode to at least the second operating mode for an upcoming section of track may only be activated if the track forecast for the upcoming section shows that the operating point of the internal combustion engine lies within a torque range for at least a predetermined period of time, which covers the torque requirement predicted for this section of track by at least the second operating mode. characterized by that the operating modes are realized through different compression ratios of the internal combustion engine. [2] Method according to claim 1, characterized by that the duration is greater than or equal to 5 seconds. [3] Method according to claim 1 or 2, characterized by , that the operating modes of the internal combustion engine (4) are realized by operating the internal combustion engine (4) with different numbers of cylinders. [4] Method according to claim 3, characterized by , that cylinder deactivation is carried out if, for the specified period, the torque requirement is in the operating range of the internal combustion engine with a reduced number of active cylinders, and the deactivated cylinders are activated if, for the specified period, the torque requirement is in the operating range of the internal combustion engine with a full number of active cylinders. [5] Method according to claim 1 or 2, characterized by that the operating modes are realized through lean operation and homogeneous operation of an internal combustion engine or through different HCCI combustion processes. [6] Method according to any of the preceding claims, characterized by, that the route forecast performs a prediction of the expected route and a prediction of the expected speed, from which a prediction of the torque requirement for the drive during the journey is derived. [7] Method according to claim 6, characterized by , that the route prediction is based on information from a navigation system, an ACC system, a Car2X system, a digital map and / or internet-based route data. [8] Method according to any of the preceding claims, characterized by that the switching operations take place at the beginning of a phase with reduced torque requirement and at the beginning of a phase with increased torque requirement for the specified duration. [9] Device for controlling the internal combustion engine (4) of a motor vehicle during driving operation, wherein the device is set up and designed to carry out the method according to one of the preceding claims, and wherein the internal combustion engine (4) has at least two operating modes in which different torque ranges are provided, comprising a device (3) for performing a switching function between the at least two operating modes, a device (1) for carrying out a route forecast to determine route data of upcoming route sections, a forecasting device (2) for forecasting the torque requirement of upcoming track sections based on the track data, wherein The switching function between the first operating mode and at least a second operating mode for an upcoming section of track is only activated if it is apparent from the track forecast of the upcoming section of track that the operating point of the internal combustion engine (4) lies for a specified period of time in a range of the second operating mode that covers the torque requirement predicted for this section of track. [10] Device according to claim 9, characterized by that the facility for performing route forecasting includes a navigation system, an ACC system, a Car2X system, a digital map and / or access to internet-based route data.

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