Method for controlling an internal combustion engine in a drive system of a motor vehicle and motor vehicle

Abstract

The invention relates to a method for controlling an internal combustion engine (2) in a drive system (16) of a motor vehicle (1), wherein - the internal combustion engine (2) is started and a power output is drawn from it that is above a continuously available power output (10), in particular a maximum available power output (9), - a temperature of at least one exhaust-side component (12) is determined, - a computer device (8) compares the determined temperature of at least one exhaust-side component (12) with a predefined limit temperature (11), and - the computer unit (8) reduces the power available from the internal combustion engine (2) if the determined temperature of at least one exhaust-side component (12) reaches an approach range (13) to the predefined limit temperature (11).

Description

[0001] The present invention relates to a method for controlling an internal combustion engine in a drive system of a motor vehicle. The invention further relates to a motor vehicle comprising an internal combustion engine, an exhaust-side component, and a computer device connected thereto for carrying out this method.

[0002] From DE 10 2012 211 527 A1, a method for controlling an internal combustion engine in a drive system of a motor vehicle is known, in which the internal combustion engine is started and a power output is drawn from it that is above a continuously available power output. Subsequently, the temperature of at least one exhaust-side component is determined, wherein a computer compares the determined temperature with a predefined limit temperature and throttles the maximum power output of the internal combustion engine if the determined temperature reaches a predefined limit temperature.

[0003] From DE 10 2016 208 595 A1, a method for controlling a drive system with at least two drive units, each assigned at least one control unit, is known. In this method, a master control unit calculates a total target torque, which is then divided by the master control unit into individual target torques for each of the drive units. The drive units are controlled by their assigned control units based on these individual target torques. To improve the coordination of several interconnected control units with a common objective, the limit torques associated with the drive units are determined and taken into account by the master control unit when dividing the total target torque.

[0004] From DE 722 316 A a time switch for the time-limited change of an operating state of an internal combustion engine is known, by means of which an overload and thus also damage to the internal combustion engine is to be avoided.

[0005] From DE 10 2007 042 464 A1, a method for controlling an internal combustion engine is known by means of which a short-term increase in power beyond the set maximum power can be generated. This is achieved by providing a time- and / or temperature-controlled switching element that controls a blocking device which limits the amount of fuel to a maximum value corresponding to a maximum power output.

[0006] From DE 10 2009 039 774 A1, a method for controlling a motor vehicle is known, wherein at least one driver-specific evaluation value describing the driver's driving skills is determined, and depending on this value, at least one performance characteristic available to the driver and / or at least one driving function of a system of the motor vehicle is activated or deactivated. Additionally or alternatively, at least one threshold value for automatic driving intervention is adjusted. This is intended, in particular, to enable the operation of the motor vehicle to be better adapted to an individual driver.

[0007] Motor vehicles, and especially sports cars—that is, high-performance vehicles—with internal combustion engines possess both a continuously available engine power output at which the engine is not damaged, and a maximum engine power output that can be accessed for short periods. Thus, more power can be drawn from the engine temporarily, although the maximum available (engine) power always carries the risk of the engine overheating and consequently being damaged.

[0008] Especially when starting an internal combustion engine, particularly a cold start, there is initially no such risk of overheating, as the internal combustion engine and downstream exhaust-side components only warm up slowly.

[0009] However, a disadvantage here is that the thermal inertia present in the drive system can lead to overheating and thus damage to the internal combustion engine or downstream exhaust-side components, even though the power drawn from the internal combustion engine has already been throttled back.

[0010] The present invention therefore addresses the problem of providing a method for controlling an internal combustion engine in a drive system of a motor vehicle, by means of which, in particular during a start, an additional power output above a continuously available engine power output (up to the maximum available engine power output) can be accessed without hesitation and without risking damage to the internal combustion engine.

[0011] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0012] The present invention is based on the general concept of monitoring the temperature of at least one component located downstream of an internal combustion engine on the exhaust side and reducing the maximum available power output of the engine if the temperature of this at least one exhaust-side component approaches a permanently tolerable limit temperature. The maximum available power output of the internal combustion engine is thus reduced as soon as the temperature of the at least one exhaust-side component, i.e., the component connected to an exhaust system, reaches a range approaching the predefined limit temperature of the exhaust-side component. In the following description, the term "power" always refers to the engine power of the internal combustion engine.In the inventive method for controlling an internal combustion engine in a motor vehicle's drive system, after the engine is started, a power output is initially requested that exceeds a continuously available power output, in particular a maximum available power output, thereby providing an acceleration boost and thus significantly increased acceleration. Simultaneously or subsequently, the temperature of at least one component located on the exhaust side of the internal combustion engine is determined. This can be done by a detection device, for example by means of a temperature sensor, or based on a temperature model in a computer system.This computer system compares the measured temperature of at least one exhaust-side component with a predefined limit temperature of the same component and reduces the maximum power output of the internal combustion engine as soon as the measured temperature of the exhaust-side component approaches the previously described range of approximation to the predefined limit temperature of the exhaust-side component. The predefined limit temperature corresponds to a continuously tolerable temperature at which neither the component nor the upstream internal combustion engine is damaged.With the method according to the invention, it is thus possible, at least temporarily, to call up an additional power output above the continuously available engine power, up to the maximum power output, during a start-up, particularly a cold start, of the internal combustion engine, without having to fear that the internal combustion engine or downstream exhaust-side components will be damaged. However, as soon as the determined temperature of the at least one exhaust-side component approaches the defined limit temperature, i.e., reaches the previously described approach range to the predefined limit temperature, or...Upon entering this state, the maximum power output of the internal combustion engine is throttled by means of the method according to the invention, specifically to the continuously available engine power at which neither the internal combustion engine nor the downstream exhaust-side components suffer damage, particularly temperature-related damage. The method according to the invention can, of course, be applied not only during a start-up, especially a cold start, of the internal combustion engine, but also in the same way during operation of the internal combustion engine, for example, during a short uphill drive after a longer downhill drive, in which both the internal combustion engine and the downstream and exhaust-side components have a temperature that is below a maximum permissible limit temperature, i.e., a maximum permissible component temperature.Depending on the driving mode and thus indirectly on the selection of a throttle valve position during overrun (driver releases the accelerator pedal), the cooling of the components to be protected is also achieved during a "normal" brisk drive on a road, and thus a considerably higher frequency is achieved to provide the additional power from the internal combustion engine.

[0013] The approach range can, for example, be from 0 °C to 50 °C. Thus, for instance, with a predefined limit temperature between 450 °C and 600 °C on an exhaust-side component, such as a manifold or turbocharger, the approach range begins at 400 °C to 550 °C. It is important, however, that the approach range is large enough to allow for a gradual, and in particular continuous, reduction of the maximum engine power available from the internal combustion engine. This presents a conflict of objectives: on the one hand, to gradually reduce the available engine power when approaching the predefined limit temperature, in order to avoid a sudden drop in power that a driver might find unpleasant; and on the other hand, to keep the approach range as small as possible to maximize the duration of the reduction in engine power.to be able to access the maximum power from the internal combustion engine until shortly before reaching the predefined limit temperature, thus enabling extremely sporty driving.

[0014] In a particularly preferred embodiment of the inventive method, the computer system reduces the maximum power output of the internal combustion engine to a continuously available power output if the measured temperature of at least one exhaust-side component reaches or exceeds the predefined limit temperature. For example, if the exhaust-side component designed as an exhaust gas turbocharger reaches a temperature of 550 °C, which also corresponds to its limit temperature, the inventive method automatically reduces the maximum power output of the internal combustion engine to a continuously available engine power output at which neither temperature-related damage to the internal combustion engine nor to the exhaust-side component, such as the exhaust gas turbocharger, is to be expected.This makes it possible to drive a motor vehicle with an internal combustion engine and a computer system designed to carry out this process in a sporty manner, without having to fear damage, especially temperature-related damage, due to overheating.

[0015] In an advantageous further development of the inventive method, the temperature of a manifold is determined. A manifold is a pipe section whose curved shape causes a change in the direction of gases at an internal combustion engine, in particular a merging of exhaust gases from different cylinders. Since the manifold is located directly at the exhaust end of the internal combustion engine, it is exposed to a comparatively high temperature load. Using the inventive method, it is possible to safely utilize the thermal inertia of a drive system for sporty driving, while simultaneously preventing temperature-related, i.e., overheating-related, damage to both the internal combustion engine and downstream exhaust-side components by throttling the maximum power output of the engine when approaching the predefined limit temperature.The temperature can be determined, for example, using a detection device, such as a temperature sensor in the area of ​​the manifold, or calculated using a temperature model in the computer system. When this reaches the previously described approximation range of the manifold's temperature, the method according to the invention reduces the maximum available power and thus also the further energy and heat supply to the manifold, whereupon it cools down again and damage can be avoided.

[0016] In a particularly preferred embodiment of the inventive method, the temperature of an exhaust gas turbocharger and / or a catalytic converter is determined or recorded. These two components are each arranged in an exhaust stream of a motor vehicle's drive system containing an internal combustion engine and, due to inertia, are heated only with a delay when the engine is started. It is particularly important to ensure that the exhaust gas turbocharger is operated only at its maximum permissible operating temperature, as higher temperatures can lead, for example, to oil coking and thus to insufficient lubrication of a shaft in the exhaust gas turbocharger, which can ultimately lead to damage and failure of the exhaust gas turbocharger.

[0017] The inventive method can, of course, be extended to all exhaust-side components, so that, for example, the temperature of a catalytic converter in the exhaust system of a drive system can also be determined. A catalytic converter, in particular, can overheat due to excessively high temperatures, and in the worst case, the ceramic material of the catalytic converter can even melt and clog it. By monitoring the temperature, maximum power can be maintained at the internal combustion engine for a comparatively longer period, thus enabling sporty driving, while at the same time reliably preventing temperature-related damage to the catalytic converter and the associated high repair costs.

[0018] It is clear that, using the method according to the invention, different predefined limit temperatures at various exhaust-side components in the exhaust system can be monitored and used for carrying out the method. For example, the temperature at a manifold, an exhaust gas turbocharger, and a catalytic converter can be monitored, each of which has its own predefined limit temperature. If the exhaust-side temperature approaches one of these predefined limit temperatures, the method reduces the maximum engine power available from the internal combustion engine, thereby reliably preventing damage to the component with that predefined limit temperature. The lowest predefined limit temperature is decisive in this regard.

[0019] According to the invention, the maximum power output of the internal combustion engine is throttled proportionally or in a ramp-like manner as the temperature approaches the predefined limit. To ensure the highest possible driving comfort, the method according to the invention should not involve a step-like or abrupt throttling of the maximum engine power, as this could be perceived as unpleasant by the driver. By proportionally throttling the maximum power output of the internal combustion engine with increasing temperature as the temperature approaches the limit, the conflict of interest between maintaining maximum engine power for as long as possible and protecting the exhaust-side components from overheating can be resolved.If, for example, the temperature of the exhaust-side component, determined by the detection device and transmitted to the computer system, or determined by the computer system itself, reaches the approach range and enters it or continues to rise, the maximum power available from the internal combustion engine is throttled, for example in a ramp-like manner or continuously with increasing temperature.

[0020] The present invention is further based on the general concept of providing a motor vehicle comprising an internal combustion engine, an exhaust-side component, and a computer unit, wherein the computer unit is configured to carry out the method described in the preceding paragraphs. This allows the advantages described with respect to the method according to the invention—namely, on the one hand, a significant increase in performance when starting the internal combustion engine, and on the other hand, protection against overheating and thus protection against damage—to also be transferred to the motor vehicle according to the invention.

[0021] In an advantageous further development of the motor vehicle according to the invention, at least one exhaust-side component is designed as a manifold, an exhaust gas turbocharger, or a catalytic converter. This non-exhaustive list already suggests the wide variety of possible embodiments of the exhaust-side components. The motor vehicle according to the invention can, of course, have a detection device with a plurality of individual temperature sensors arranged along the exhaust system, so that preferably the entire exhaust system is monitored and the method according to the invention can thus be used with extreme reliability. Alternatively, temperature modeling in the computer unit can be used to detect / model the temperature of each component at any given time, and this can be supplemented, if necessary, by integrating external temperature sensors.

[0022] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0023] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. The components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or be integral areas or sections of this unit, even if this is depicted differently in the drawings.

[0024] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0025] They show, each schematically Fig. 1 a motor vehicle according to the invention comprising an internal combustion engine, a detection device and a computer device for carrying out a method according to the invention for controlling the internal combustion engine in a drive system of the motor vehicle, Fig. 2 diagrams to illustrate the inventive method for controlling the internal combustion engine in the drive system of the motor vehicle, Fig. 3 possible process steps of the inventive method for controlling the internal combustion engine in the drive system of the motor vehicle.

[0026] According to the Fig. Figure 1 comprises a motor vehicle 1 according to the invention, which is in particular designed as a sports car, and a drive system 16 with an internal combustion engine 2. The internal combustion engine 2 is designed according to the Fig. The internal combustion engine 2 is arranged at the rear of the vehicle 1, although alternative arrangements as a mid-engine or in the front of the vehicle 1 are also conceivable. The internal combustion engine 2 has a manifold 3, which collects the exhaust gases exiting from individual cylinders of the internal combustion engine 2 and feeds them into an exhaust system 4. An exhaust gas turbocharger 5 and / or a catalytic converter 6 may also be arranged in the exhaust system 4.

[0027] A further feature may be a sensor 7 and a computer unit 8 connected to it, wherein the sensor 7 is designed to measure temperatures, for example, at the manifold 3, the exhaust gas turbocharger 5, and / or the catalytic converter 6. Of course, further temperature measurement in the exhaust system 4 at associated components 12 is also conceivable. Alternatively, it is also conceivable that the temperature measurement is fully modeled in the computer unit 8, thus eliminating the need for an additional sensor 7.

[0028] Especially when starting the internal combustion engine 2, but also during prolonged operation, it is desirable for a motor vehicle 1, particularly one designed as a sports car, to be able to draw power from it that exceeds a continuously available power output 10, in particular a maximum available power output 9. Such a maximum available power output 9 of the internal combustion engine 2 is significantly higher than the continuously available engine power output 10 (compare the upper diagram in Fig. 2), wherein the continuously available power output 10 enables the long-term, damage-free operation of the motor vehicle 1 and, in particular, also of the internal combustion engine 2 and the exhaust-side components 12. In order to avoid damage to the internal combustion engine 2 or the exhaust-side components 12 arranged in the exhaust system 4, it is necessary that these do not reach or exceed their long-term tolerable and thus predefined limit temperature 11, or only for short periods.

[0029] For this purpose, the inventive method serves to control the internal combustion engine 2 in the drive system 16 of the motor vehicle 1, in which, according to a first method step A (compare Fig. 3) initially, after the internal combustion engine 2 has been started, a power output can be drawn from it that is above the continuously available power output 10, in particular the maximum available power output 9. Such a maximum available power output 9 enables a particularly sporty (starting) drive.

[0030] Simultaneously, after the start of the internal combustion engine 2, in a second process step B, for example by means of the detection device 7, the temperature of at least one exhaust-side component 12, for example a manifold 3, an exhaust gas turbocharger 5 and / or a catalyst 6, is monitored and these temperatures are transmitted to the computer unit 8. The temperature can also be determined using a temperature model of the computer unit 8. In a third process step C, the computer unit 8 compares the temperature(s) of the at least one exhaust-side component 12 determined by the computer unit 8 or transmitted by the detection device 7 with a predefined limit temperature 11 (see lower diagram in the Fig. 2) and in a fourth process step D, reduces the maximum power 9 available from the internal combustion engine 2 if the temperature of the at least one exhaust-side component 12, transmitted by the detection device 7 or determined by the computer device 8, reaches a range 13 approaching the predefined limit temperature 11. The range 13 approaching the predefined limit temperature 11 is below the predefined limit temperature 11 and includes, for example, 0–100 °C, preferably 20–50 °C, and most preferably 5–20 °C.

[0031] If one considers the Fig. 2, it can be seen that up to time t1 after the start of the motor vehicle 1 and after the start of the internal combustion engine 2, which occurs at time t0, the maximum power 9 available from the internal combustion engine 2 is also being utilized. During the time from t0 to t1, an operating temperature 14 rises (compare lower diagram in the Fig. 2) of at least one exhaust-side component 12, until the operating temperature 14, which is determined during this time, reaches the approach range 13 at time t1.

[0032] When the time t1 is exceeded, at which the operating temperature 14 reaches or enters the approach range 13, the computer device 8 throttles the maximum power 9 available at the internal combustion engine 2, whereby with a further increase of the operating temperature 14 and an approach of the maximum permissible limit temperature 11, in the present case a continuous and proportional throttling of the maximum available power 9 at the internal combustion engine 2 takes place.

[0033] The throttling of the maximum available power 9 of the internal combustion engine 2 takes place in a ramp range 15, which lies between times t1 and t2. The throttling of the maximum available power 9 continues until, at time t2, it has been reduced to the level of the continuously available engine power 10. At the level of the continuously available engine power 10, no temperature-related and thus overheating-related damage to the internal combustion engine 2 or the exhaust-side components 12 is to be expected.

[0034] If the approach range 13 is chosen to be very small, the computer unit 8 can also reduce the maximum power 9 available from the internal combustion engine 2 to the continuously available engine power 10, provided that the determined temperature of at least one exhaust-side component 12 reaches or exceeds the predefined limit temperature 11. This is possible because an immediate failure of the internal combustion engine 2 or the exhaust-side components 12 is not to be expected when the predefined limit temperature 11 is reached or briefly exceeded.

[0035] The detection device 7 can be coupled to, for example, the manifold 3, the exhaust gas turbocharger 5, and / or the catalyst 6 to detect the respective temperatures, with all these exhaust-side components 12 having individual and predefined limit temperatures 11 that they can withstand in the long term. If the detection device 7 monitors several such exhaust-side components 12, the lowest predefined limit temperature 11 is responsible for throttling the maximum power 9 available at the combustion engine 2.

[0036] With the inventive method and the inventive motor vehicle 1, it is possible, particularly when starting the internal combustion engine 2, to call up a power boost in which the power available from the internal combustion engine 2 is significantly higher than the continuously available engine power 10, as shown in the diagram above. Fig.2 between time t0 and time t0. The method according to the invention thus utilizes the thermal inertia of the entire drive system 16 on the exhaust side, so that particularly sporty driving is possible without having to accept damage, especially temperature-related damage.

[0037] If the temperature transmitted by the detection device 7 to the computer unit 8, or the temperature determined by the computer unit 8, reaches the approach range 13 associated with the predefined limit temperature 11 assigned to at least one exhaust-side component 12, the computer unit 8 reduces the maximum power 9 available from the internal combustion engine 2 until, for example, it reaches the continuously available power 10. This reliably prevents damage.

Claims

[1] Method for controlling an internal combustion engine (2) in a drive system (16) of a motor vehicle (1), in which - the internal combustion engine (2) is started and a power is called up from it which is above a permanently available power (10), in particular a maximum available power (9), - a temperature of at least one exhaust-side component (12) is determined, - a computer device (8) compares the monitored temperature of the at least one exhaust-side component (12) with a predefined limit temperature (11), and - the computer device (8) throttles the maximum power (9) that can be called up by the internal combustion engine (2) if the determined temperature of the at least one exhaust-side component (12) reaches an approximation range (13) to the predefined limit temperature (11), characterized bythat the power available from the internal combustion engine (2) is throttled when the approach range (13) to the predefined limit temperature (11) is reached in proportion to an increase in the determined temperature of the exhaust-side component (12). [2] Method according to claim 1, characterized by that the computer device (8) throttles the power available from the internal combustion engine (2) to a continuous engine power (10) if the determined temperature of the at least one exhaust-side component (12) reaches or exceeds the predefined limit temperature (11). [3] Method according to claim 1 or 2, characterized by that a temperature of a manifold (3) is determined. [4] Method according to one of the preceding claims, characterized by that a temperature of an exhaust gas turbocharger (5) is determined. [5] Method according to one of the preceding claims, characterized bythat a temperature of a catalyst (6) is determined. [6] Motor vehicle (1) with an internal combustion engine (2), an exhaust-side component (12) and a computer device (8) which is designed to carry out the method according to one of the preceding claims. [7] Motor vehicle (1) according to claim 6, characterized by that the at least one exhaust-side component (12) is designed as a manifold (3). [8] Motor vehicle (1) according to claim 6 or 7, characterized by that the at least one exhaust-side component (12) is designed as an exhaust-gas turbocharger (5). [9] Motor vehicle (1) according to one of claims 6 to 8, characterized by that the at least one exhaust-side component (12) is designed as a catalyst (6).

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