Method for operating an internal combustion engine

Abstract

Method for operating an internal combustion engine (2) comprising at least a crankshaft (4) and at least an intake manifold (6) with a throttle valve (8), wherein the method comprises at least the following steps: a) Intake of air via the intake manifold (6) for the duration of an intake stroke (16) of the internal combustion engine (2), b) Determining a crankshaft angle (12) of the crankshaft (4), c) Intervening in a control angle (13) of the throttle valve (8) at least for the duration of a final period (18) of the intake stroke (16), wherein the crankshaft angle (12) determines when the final period (18) of the intake stroke (16) begins, wherein in step c) the control angle (13) is kept constant at the value that was present at the beginning of the final period (18) of the intake stroke (16).

Description

[0001] The invention relates to a method for operating an internal combustion engine, in particular for a single-track motor vehicle, wherein the method can in particular influence an actuation angle of a throttle valve in an intake manifold.

[0002] Internal combustion engines are known in which the engine speed can be adjusted independently of driver input via an electronically controlled throttle valve. This is the case, for example, with so-called EGAS systems. In such systems, the throttle valve is not controlled by a cable directly connected to an accelerator pedal. Instead, the accelerator pedal input is detected electronically, and the throttle valve is controlled accordingly via an actuator. This electronic intervention allows the throttle valve position to be adjusted not only according to the driver's input but also taking other influencing factors into account.

[0003] Furthermore, it is known to electronically control the fill quantity, i.e., the amount of air (and possibly also fuel) to be drawn into the combustion chambers of the internal combustion engine. The required fill quantity is calculated, for example, according to the currently demanded power output of the internal combustion engine. Factors such as driver input and other factors (ambient air pressure, current engine speed, parameters of the fuel to be burned, etc.) can be included in this calculation.

[0004] In known systems, the problem is that between the time the fill quantity is calculated and the end of the actual intake process, conditions and circumstances can change so drastically that the fill quantity used no longer corresponds to the prevailing conditions. The deviation between the calculated fill quantity and the actually required fill quantity can even correspond to the difference between the minimum and maximum possible fill quantity. An excessive fill quantity can lead to a significant drop in engine speed, even causing the internal combustion engine to stall, due to the additional compression work required. In such situations, achieving an emissions-optimized fuel-air mixture is often impossible. Current technological approaches exist to address this using complex digital engine electronics. However, these approaches have limitations.The time required for calculation, dispensing, and transport of the fuel must be taken into account.

[0005] Based on this, the object of the present invention is to further solve, or at least alleviate, the technical problems described in connection with the prior art. A method is presented that makes this possible and, in particular, enables the prevention of a drop in engine speed and, especially, of the stalling of the internal combustion engine as a result of such effects.

[0006] This problem is solved by a method according to the features of claim 1. Further advantageous embodiments of the method are specified in the dependent claims. The features listed individually in the claims can be combined with one another in any technologically meaningful way and can be supplemented by explanatory details from the description, thereby showing further embodiments of the invention.

[0007] The inventive method for operating an internal combustion engine comprising at least one crankshaft and at least one intake manifold with a throttle valve includes at least the following steps: a) Drawing in air through the intake manifold for the duration of an intake stroke of the internal combustion engine, b) Determining a crankshaft angle of the crankshaft, c) Intervening in the throttle valve angle at least for the duration of a final period of the intake stroke, whereby the start of the final period of the intake stroke is determined via the crankshaft angle.

[0008] The internal combustion engine is preferably an engine for a single-track motor vehicle, particularly a motorcycle. However, the internal combustion engine could also be, for example, one for an automobile, an aircraft, or a ship. The crankshaft is preferably connected to one or more cylinders via connecting rods. The crankshaft serves to transmit power from the cylinders. A linear motion of the cylinders in alternating directions is converted into a continuous rotary motion by means of the crankshaft (and the connecting rods). Preferably, the internal combustion engine is a four-stroke engine.

[0009] The internal combustion engine, and in particular its cylinders, are supplied with air via at least one intake manifold. This intake manifold is designed so that air from the vehicle's surroundings can flow in at one end. The cylinders, or rather their intake valves, are connected to the other end. The throttle valve regulates the airflow in the intake manifold. Preferably, the throttle valve is designed such that in an open position (defined here as an angle of 90°), the entire cross-section of the intake manifold is open, and in a closed position (defined here as 0°), no air can pass through the intake manifold.

[0010] The process steps a) to c) are preferably carried out at least partially simultaneously.

[0011] The intake stroke of an internal combustion engine, or more specifically, the intake stroke of a cylinder within that engine, is the period during which the intake valve of the respective cylinder is open, allowing air to be drawn into the cylinder. During the intake stroke, the cylinder volume increases due to the movement of the connecting rod and crankshaft.

[0012] In some designs, the air drawn into the internal combustion engine during the intake stroke can be mixed with fuel by injecting fuel into the intake manifold. This is known as "port fuel injection." Alternatively, air can be drawn into the cylinder without fuel, and fuel injected directly into the cylinder. This is known as "direct fuel injection."

[0013] Step b) is preferably carried out during the entire operation of the internal combustion engine. The crankshaft angle can be determined using a measuring device on the crankshaft. The presence of the various strokes of the internal combustion engine (power stroke, exhaust stroke, intake stroke, compression stroke) is preferably detected via the crankshaft angle. Detection of the individual strokes via the crankshaft angle is particularly accurate.

[0014] The throttle valve angle is changed in step c) at least for the duration of the final phase of the intake stroke. Preferably, the final phase of the intake stroke comprises the last 60% of the duration of a valve lift of the intake valves (i.e., the time the intake valves require to close), and more preferably the last 50% of this period.

[0015] The intervention in the throttle valve angle according to step c) is preferably achieved via an electronic control system. Alternatively, the intervention can also be implemented mechanically, e.g., by means of a camshaft. The term "intervention" here refers to any deliberate deviation from the normally prevailing position of the throttle valve. During an intake stroke, the throttle valve is normally freely movable in order to minimize flow resistance for the air entering the combustion engine or cylinders and thus achieve the lowest possible energy losses. "Intervention" here also specifically includes the temporary restriction of this free movement of the throttle valve, for example, by locking or obstructing the throttle valve for a specific period.

[0016] This intervention ensures that, particularly just before the intake valves close, less air (and possibly less fuel) is drawn into the cylinder. During this critical period of the intake stroke, conventional methods for operating internal combustion engines often result in the intake of an excessive amount of air. An excessive air volume can lead to the problems described above, such as a reduction in engine speed. Reducing the air volume prevents the internal combustion engine from stalling. Furthermore, it can reduce pollutant emissions, especially CO2 emissions. The described method is particularly advantageous when used in the idling operating conditions of an internal combustion engine. Using this method in idling conditions allows for particularly low idle speeds.Surprisingly, the problem of engine speed reduction or stalling can be solved by this described throttling in the final phase of an intake stroke.

[0017] In a preferred embodiment of the method, in step c) the positioning angle is kept constant at the value that was present at the beginning of the final period of the intake stroke.

[0018] In this embodiment, the intervention according to step c) occurs in such a way that any changes in the throttle valve angle are suppressed for the duration of the final phase of the intake stroke. This means, in particular, that an increase in the throttle valve angle due to the described intervention is suppressed during this period. For example, if the driver wishes to increase the engine speed, this would typically lead to an increase in the throttle valve angle. At least for the duration of the final phase of the intake stroke, this is suppressed in this embodiment. This prevents, in particular, an excessive amount of fuel entering the combustion chambers, as described above.

[0019] In a further preferred embodiment of the method, the throttle valve is set to an angle before the end of the intake stroke that allows a lower airflow than a comparable angle that would be present without this method. In particular, a smaller throttle valve angle is set than the angle that would be present without this method.

[0020] The reference angle is defined as the throttle valve angle calculated or otherwise determined, taking into account all influencing factors used in the respective internal combustion engine and the respective operating method. Preferably, the throttle valve angle is reduced upon reaching the end of the intake stroke. This preferably reduces the airflow through the intake manifold. It is preferred that the throttle valve angle be reduced by at least 10%, and particularly by at least 20%.

[0021] It is particularly preferred that the throttle valve angle is limited to a maximum value that is independent of any driver request or similar influences (i.e., in particular, of a requested angle, which is here referred to as the reference angle). The described method can preferably also be active when the internal combustion engine is idling, with the throttle angle preferably limited accordingly. For example, the throttle angle can be limited such that the intake manifold is only open to air to a maximum of 1% (compared to 100% with the throttle valve fully open), which can correspond to the idle position. In this case, the throttle angle is approximately 1° (i.e., the throttle valve is almost completely closed). Preferably, the maximum throttle angle is between 0.5° and 5°, and particularly between 1° and 2°.

[0022] By reducing the angle of attack as soon as the end of the intake stroke is reached, the effect described above can be enhanced, ensuring that not too much air (especially air not mixed with fuel) enters the combustion chambers during the critical phase just before the intake valves close.

[0023] In a further preferred embodiment of the method, the throttle valve angle is electronically controlled at least in step c).

[0024] It is particularly preferred that the throttle valve angle is electronically controlled throughout the entire operation of the internal combustion engine. However, it is also possible, for example, to additionally act on an otherwise mechanically controlled throttle valve according to the described method.

[0025] The intervention performed in step c) is characterized in particular by the fact that it is carried out individually for each intake stroke of the internal combustion engine's operation. Previously, it was more common to make interventions in the throttle valve position that acted on the valve position for an extended period, independent of the individual strokes of the internal combustion engine's operation. This was done primarily to regulate the engine's power, torque, and / or speed. The intervention described here, performed in step c), is less concerned with regulating power, torque, or speed, but rather aims to reduce the problems described above caused by excessive air intake at the end of an intake stroke.

[0026] Another aspect of the present invention relates to an internal combustion engine comprising at least one crankshaft and an intake manifold with a throttle valve. The internal combustion engine is configured for operation according to a method as described above.

[0027] The special advantages and design features described earlier for the process are applicable and transferable to the described internal combustion engine. The same applies to the special advantages and design features described below for the internal combustion engine, which are applicable and transferable to the described process.

[0028] In a preferred embodiment of the internal combustion engine, the intake pipe has a length of at most 25 cm.

[0029] The length of the intake manifold extends between an opening of the intake manifold to the surroundings of the vehicle and a connection to a cylinder of the internal combustion engine, in particular to an intake valve of the cylinder. If the internal combustion engine has multiple combustion chambers, it is sufficient if the aforementioned condition is met for one of the combustion chambers. However, it is preferred that the aforementioned condition is met for all combustion chambers of the internal combustion engine. This means that the length between the surroundings and the connection or intake of each cylinder is at most 25 cm.

[0030] A particularly short intake pipe allows the amount of intake air to be varied very quickly by adjusting the throttle valve angle. Furthermore, losses due to friction in the intake pipe are reduced. It is especially preferred that the length of the intake pipe section between the throttle valve and the intake valve(s) is no more than 15 cm. The intake air requires only a correspondingly short time to traverse this short distance between the throttle valve and the intake valve, so that a change in the throttle valve angle is quickly transmitted to the combustion chambers. Therefore, such a short intake pipe has a limited capacity to buffer fluctuations in the airflow. For this reason, the described method is particularly efficient when a relatively short intake pipe, preferably less than 25 cm long, is used.

[0031] A short intake manifold can be particularly advantageous at high engine speeds. This is primarily because flow losses during air intake are especially low with a very short intake manifold. The position of the throttle valve within the intake manifold can influence how quickly the engine responds to changes in the throttle valve's angle. Additional beneficial thermodynamic effects may also occur.

[0032] In another preferred embodiment, the internal combustion engine further comprises an electronic actuator for the throttle valve.

[0033] The electronic actuator preferably comprises an electric motor. More preferably, the electronic actuator comprises an electromagnetic actuator of any design. This can enable the adjustment of the throttle valve according to the described method. Preferably, the electronic actuator is connected to a control unit. This could, for example, be an engine control unit.

[0034] The invention is preferably used in a single-track motor vehicle with an internal combustion engine as described.

[0035] The single-track motor vehicle in question is, for example, a motorcycle. A common characteristic of motorcycles is their particularly short intake manifolds. Motorcycle engines are especially prone to the problems described above.

[0036] The invention and its technical context are explained in more detail below with reference to the figures. The figures show particularly preferred embodiments, to which, however, the invention is not limited. It should be noted in particular that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: a schematic representation of a motor vehicle with an internal combustion engine, Fig. 2: a representation of the time course of the throttle valve's angle of rotation.

[0037] Fig. Figure 1 shows a motor vehicle 1 with an internal combustion engine 2. The internal combustion engine 2 has one cylinder 3 connected to a crankshaft 4. The crankshaft angle of the crankshaft 4 can be determined using an angle measuring device 5. The cylinder 3 is connected to an intake manifold 6. The intake manifold 6 has a length 7. The intake manifold 6 has a throttle valve 8 with an opening angle 9. The throttle valve 8 can be controlled by an electronic actuator 10. The electronic actuator 10 is connected to a control unit 11. This is shown by the dotted line.

[0038] Fig. Figure 2 is a plot of both the crankshaft angle ω and the throttle valve angle φ. Fig.Figure 2 shows an example of the throttle valve angle φ during a stroke of an internal combustion engine currently operating in a phase where the engine's power output is increased. This power increase results in a rising throttle valve angle φ. The vertical axis represents only a relatively small fraction of the possible throttle valve angles φ. In a subsequent stroke (not shown here), a further increase in the curve would be observed. The crankshaft angle ω curve is labeled with reference numeral 12 and is referenced to the left vertical axis. The straight line of this curve indicates that the crankshaft angle ω changes linearly over time. Therefore, the crankshaft angle ω can be used instead of the time parameter t to determine the different strokes of the internal combustion engine.Also shown are a power stroke 14, an exhaust stroke 15, an intake stroke 16, and a compression stroke 17 of the internal combustion engine. The curve labeled with reference numeral 13 indicates the throttle valve angle φ and is referenced to the vertical axis. The curve shown is exemplary. In particular, it can be seen that the throttle valve angle φ is kept constant during a final period 18 of the intake stroke 16. This is achieved by intervention according to the described procedure. Reference symbol list 1 single-track motor vehicle 2 Internal combustion engine 3 cylinders 4 Crankshaft 5 Angle measuring device 6 Intake pipe 7 Length 8 Throttle valve 9 Positioning angles 10 electronic actuators 11 Control unit 12 Crankshaft angle ω 13 Throttle valve angle φ 14 work cycles 15 exhaust stroke 16 Intake stroke 17 compression strokes 18 End period of the intake stroke

Claims

[1] Method for operating an internal combustion engine (2) comprising at least one crankshaft (4) and at least one intake manifold (6) with a throttle valve (8), wherein the method comprises at least the following steps: a) Intake of air via the intake manifold (6) for the duration of an intake stroke (16) of the internal combustion engine (2), b) Determining a crankshaft angle (12) of the crankshaft (4), c) Intervening in a control angle (13) of the throttle valve (8) at least for the duration of a final period (18) of the intake stroke (16), wherein the crankshaft angle (12) determines when the final period (18) of the intake stroke (16) begins, wherein in step c) the control angle (13) is kept constant at the value that was present at the beginning of the final period (18) of the intake stroke (16). [2] Method according to claim 1, wherein the throttle valve (8) is set to an angle (13) when the end period (18) of the intake stroke (16) is reached, which allows a lower airflow than a comparable angle that would be present if this method were not used. [3] Method according to one of the preceding claims, wherein the actuation angle (13) of the throttle valve (8) is electronically controlled at least in step c). [4] Internal combustion engine (2) comprising at least a crankshaft (4) and an intake manifold (6) with a throttle valve (8), wherein the internal combustion engine (2) is configured for operation according to a method according to one of the preceding claims. [5] Internal combustion engine according to claim 4, wherein the intake pipe (6) has a length (7) of at most 25 cm [centimeters]. [6] Internal combustion engine (2) according to one of claims 4 to 5, further comprising an electronic actuator (10) for the throttle valve (8). [7] Single-track motor vehicle (1) comprising an internal combustion engine (2) according to any one of claims 4 to 6.

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