DE102020210271A1 - Method and device for adjusting a throttle valve for an internal combustion engine with a small intake manifold volume - Google Patents

Abstract

The invention relates to a method for operating an engine system (1) with an internal combustion engine (2) with at least one cylinder (3), in particular an internal combustion engine (2) with a ratio between cylinder displacement and an intake manifold volume (SV) connected thereto of greater than 1 , in particular greater than 2, provided with the following steps: - Providing a request for a target engine torque (MSoll); - Determining a target throttle valve position (SSoll) for adjusting a throttle valve (7) for controlling an air supply into the internal combustion engine (2 ) depending on the target engine torque (MSoll); - Modifying a course of the target throttle valve position (SSoll) depending on the crankshaft angle of a crankshaft of the internal combustion engine (2) to provide a modified target throttle valve position (S'Soll), so that the Change in an air charge is reduced during an injection of fuel into an intake manifold of the internal combustion engine (2); - operate of the internal combustion engine (2) depending on the modified target throttle position (S'Soll).

Description

technical field

The invention relates to internal combustion engines, in particular internal combustion engines with a small intake manifold volume, such as drive engines for motorcycles and the like. Furthermore, the present invention relates to a method for adjusting the throttle valve to a setpoint throttle valve position in an electrically controllable throttle valve actuator.

Technical background

Motorcycles typically have engine systems that include air-guided, port fuel injected internal combustion engines. In general, in the case of air-guided internal combustion engines, the driver specifies a desired engine torque, which is converted into an air charge to be set. The air filling is determined by suitable models and converted into a control for the throttle valve by specifying a target throttle valve position, through which an engine mass flow (air volume) flowing into the internal combustion engine is adjusted.

Internal combustion engines of this type are operated with what is known as mixture pre-control, in which a desired target air-fuel ratio in the combustion chamber is set by specifying a fuel quantity to be injected. In particular, dynamic changes in the required target engine torque and thus in the air quantity flowing into the internal combustion engine set via the throttle valve position by actuating the throttle grip must be taken into account by the mixture pre-control as quickly and precisely as possible.

Dynamic, very rapidly changing target air fillings, as often occur when the throttle is quickly activated on motorcycles, cannot easily be implemented with the same dynamics by the mixture pre-control.

The pamphlet DE 10 2016 200 723 A1 discloses a method for controlling a position of a throttle valve in an intake manifold of an internal combustion engine, through which gas is supplied to a cylinder of the internal combustion engine, the method comprising the steps of determining a desired gas mass flow which flows in the intake manifold via the throttle valve, taking into account gas dynamics in the intake manifold, determining a control signal for the throttle valve using the determined, desired gas mass flow, and controlling the position of the throttle valve based on the determined control signal.

Disclosure of Invention

According to the invention, a method for controlling a throttle valve of an internal combustion engine according to claim 1 and a device and an engine system according to the independent claims are provided.

Further developments are specified in the dependent claims.

• - Bereitstellen einer Anforderung nach einem Soll-Motormoment;
• - Bestimmen einer Soll-Drosselklappenstellung zum Einstellen einer Drosselklappe zum Steuern einer Luftzufuhr in den Verbrennungsmotor abhängig von dem Soll-Motormoment;
• - Modifizieren eines Verlaufs der Soll-Drosselklappenstellung abhängig von dem Kurbelwellenwinkel einer Kurbelwelle des Verbrennungsmotors, um eine modifizierte Soll-Drosselklappenstellung bereitzustellen, so dass die Änderung einer Luftfüllung während einer Einspritzung von Kraftstoff in ein Saugrohr des Verbrennungsmotors reduziert wird;
• - Betreiben des Verbrennungsmotors abhängig von der modifizierten Soll-Drosselklappenstellung.

According to a first aspect, a method is provided for operating an engine system with an internal combustion engine with at least one cylinder, in particular an internal combustion engine with a ratio between cylinder displacement and an intake manifold volume connected thereto of greater than 1, in particular greater than 2, with the following steps:

• - Providing a request for a target engine torque;
• - Determining a target throttle valve position for adjusting a throttle valve for controlling an air supply into the internal combustion engine depending on the target engine torque;
• - modifying a course of the target throttle position depending on the crankshaft angle of a crankshaft of the internal combustion engine to provide a modified target throttle position such that the change in air charge during injection of fuel into an intake manifold of the internal combustion engine is reduced;
• - Operation of the internal combustion engine depending on the modified target throttle position.

Furthermore, a change in the target throttle valve position provided can be permitted or delayed synchronously with the power strokes of the at least one cylinder of the internal combustion engine.

In current engine systems, an electrically controlled throttle valve is actuated immediately after a user has specified a corresponding change in a target engine torque, for example by actuating a throttle grip on a motorcycle. The calculation and implementation of the injection of fuel into the intake manifold, on the other hand, takes place synchronously with the engine speed at fixed crankshaft positions in the work cycle, ie during specific work cycles. Since the driver's request for a change in throttle position therefore becomes arbitrary When this happens in the working cycle, difficulties can arise in assigning the correct amount of fuel to the specified air charge, particularly in the case of internal combustion engines with a small intake manifold volume compared to its cubic capacity (and thus high dynamics of mass flow changes). This is the case in particular when the requested engine torque changes after the fuel quantity to be injected for the following intake stroke has been determined.

For a more precise adjustment of the mixture, an injection well before the intake stroke of the at least one cylinder is advantageous in order to provide the injected fuel with time for evaporation. If, however, after stopping the main injection with a short injection time, the throttle valve opens quickly due to a correspondingly requested target engine torque increase and thus an increase in the cylinder charge, then in order to maintain the target air-fuel ratio, fuel must be post-injected before the end of the intake phase . However, the amount of fuel that can be injected during post-injection is limited by the time available until the intake valves close (end of the intake phase), the flight time of the fuel and the design of the injection valve. Therefore, not every increase in the required setpoint engine torque can be compensated for by a corresponding increase in the injected fuel quantity.

In such cases, in particular, the reduced time for mixture preparation (evaporation of the fuel in the intake manifold) can lead to a deterioration in the combustion quality or, in the case of spark plug wetting with liquid fuel, even to misfiring.

Conversely, an abrupt closing of the throttle valve due to a reduction in the required target engine torque after the main injection with a long injection duration has already been discontinued produces a deviation between the target air-fuel ratio and the actual air-fuel ratio, since there is now excess fuel, ie an air-fuel mixture that is too rich. However, this is not correctable as the fuel has already been injected into the intake manifold.

The faulty mixture pre-control caused by the request for a change in the throttle valve position at an unfavorable time can, in extreme cases, lead to misfires or even to the internal combustion engine dying. These effects have a particularly strong effect at low engine speeds, since the time between two intake phases for a change in the throttle valve position is relatively large here.

According to the above method, it is therefore proposed to carry out the actuation of the throttle valve synchronously with the engine speed and only within a specific range of the crankshaft positions. As a result, a throttle valve opening, injection and intake of fresh air can be synchronized and the mixture pre-control can be optimized. This leads to improved running characteristics, reduced emissions and optimized combustion engine response. The resulting time delay between the point in time at which the desired change in engine torque is requested by actuating the gas grip and the actual throttle valve adjustment can be ignored, since this is only a few milliseconds. In addition, there are no further measures to improve the mixture pre-control, since the provision of a post-injection strategy may be omitted and transient compensation can be optimized.

Provision can be made for a change in the target throttle valve position to be permitted or delayed depending on the point in time at which a fuel quantity to be injected is determined.

Further, a change in the target throttle valve position may be delayed after a timing of setting the amount of fuel to be injected or after a timing of starting injection of the amount of fuel.

According to one embodiment, a request for a change in desired throttle position within the intake stroke may be modified to be implemented in a crank angle range outside of the intake stroke.

Furthermore, a gradient or an amount of a change in the target throttle valve position during a period between the start of the injection or the end of the calculation of the fuel quantity to be injected and the closing of the intake valve for the at least one cylinder can be limited in order to change the air charge during the period limit.

In particular, when the required setpoint engine torque increases after the throttle valve has been opened, the resulting change in the setpoint throttle valve position can be limited to an extent that can be compensated for by a function for carrying out subsequent post-injections.

Alternatively or additionally, when the required setpoint engine torque is reduced after the throttle valve has been opened, the resulting change in the setpoint throttle valve position can be suppressed until the inlet valve closes.

In particular, when the required target engine torque increases after the throttle valve has been opened, the resulting change in the target throttle valve position can be limited to a level such that a maximum charge is not exceeded for which the compression work is still performed by the kinetic energy stored in the system can be.

• - Empfangen einer Anforderung nach einem Soll-Motormoment;
• - Bestimmen einer Soll-Drosselklappenstellung zum Einstellen einer Drosselklappe zum Steuern einer Luftzufuhr in den Verbrennungsmotor abhängig von dem Soll-Motormoment;
• - Modifizieren eines Verlaufs der Soll-Drosselklappenstellung abhängig von dem Kurbelwellenwinkel einer Kurbelwelle des Verbrennungsmotors, um eine modifizierte Soll-Drosselklappenstellung bereitzustellen, so dass die Änderung einer Luftfüllung während einer Einspritzung von Kraftstoff in ein Saugrohr des Verbrennungsmotors reduziert wird;
• - Betreiben des Verbrennungsmotors abhängig von der modifizierten Soll-Drosselklappenstellung.

According to a further aspect, a device, in particular a control unit, is provided for operating an engine system with an internal combustion engine with at least one cylinder, in particular an internal combustion engine with a ratio between the cylinder displacement and an intake manifold volume connected thereto of greater than 1, in particular greater than 2, wherein the device is designed for:

• - Receiving a request for a target engine torque;
• - Determining a target throttle valve position for adjusting a throttle valve for controlling an air supply into the internal combustion engine depending on the target engine torque;
• - modifying a course of the target throttle position depending on the crankshaft angle of a crankshaft of the internal combustion engine to provide a modified target throttle position such that the change in air charge during injection of fuel into an intake manifold of the internal combustion engine is reduced;
• - Operation of the internal combustion engine depending on the modified target throttle position.

character list

• 1 ein Motorsystem mit einem Verbrennungsmotor und einer elektronisch ansteuerbaren Drosselklappe, insbesondere für ein Motorrad;
• 2 ein Signal-Zeit-Diagramm der Verläufe des Saugrohrdrucks, der Ansteuerung des Einspritzventils sowie der Stellung der Drosselklappe für ein Öffnen und ein Schließen der Drosselklappe; und
• 3 ein Funktionsblockschaltbild zur Bereitstellung einer Soll-Drosselklappenposition zur Einstellung der Drosselklappe durch einen Drosselklappensteller.

Embodiments are explained in more detail below with reference to the accompanying drawings. Show it:

• 1 an engine system with an internal combustion engine and an electronically controllable throttle valve, in particular for a motorcycle;
• 2 a signal-time diagram of the curves of the intake manifold pressure, the activation of the injection valve and the position of the throttle valve for opening and closing the throttle valve; and
• 3 a functional block diagram for providing a target throttle position for adjusting the throttle by a throttle actuator.

Description of Embodiments

1 shows a schematic representation of an engine system 1 with an internal combustion engine 2, in particular an air-guided internal combustion engine, z. B. a gasoline engine. The internal combustion engine 2 has at least one cylinder 3 (but can also have more than one cylinder). The internal combustion engine 2 is designed as a 4-stroke internal combustion engine with a relatively small intake pipe volume, such as is used in motorcycles or the like, for example. The intake manifold volume SV is defined as the volume between the throttle valve and the intake valve of at least one cylinder 3.

Fresh air is supplied to the internal combustion engine 2 via an air supply section 5 , and this is admitted into the cylinder 3 through an inlet valve 14 . Combustion exhaust gas is discharged through an exhaust gas discharge section 6 and is discharged through an exhaust valve 15 . A throttle valve 7 is arranged in the air supply section 5 and can be controlled electrically via a throttle valve actuator 8 .

Fuel is injected into an intake manifold section 51 between the throttle valve 7 and the intake valve 14 of the at least one cylinder 3 using an injection valve 11 .

A user of the engine system, such as a driver of a motorcycle driven by it, can generate an actuation signal via a gas actuation 12, which signal is provided in a control unit 10 as a requested target engine torque. The setpoint engine torque is converted into a requested air charge via corresponding control functions in the control unit 10 and this into a setpoint throttle valve position.

The control unit 10 controls the internal combustion engine 2 by specifying the setpoint throttle valve position for a downstream position control using the throttle valve actuator 8 . Furthermore, a fuel quantity corresponding to the air filling or the air mass flow in the internal combustion engine 2 is determined and this is metered by a corresponding activation of the injection valve 11 . The amount of fuel is defined by specifying an opening time of injection valve 11 .

If the user requests a quick change in the target engine torque, the control unit takes control 10 in a conventional manner to the throttle valve actuator 8 in order to provide an air charge in the internal combustion engine 2 that corresponds to the target engine torque. To set an always optimal air-fuel mixture, which is usually set close to λ=1 (stoichiometric equilibrium), the control unit 10 controls the injection valve 11 accordingly, in order to be as close as possible to the end of an intake stroke, ie at the time the intake valves close 14 to set an optimal air-fuel ratio in the cylinders 3 of the internal combustion engine 2 for each combustion.

If the driver requests a change in the target engine torque during or after the calculation of the current fuel quantity or during the ongoing or after the completed injection of the fuel and before the closing of the intake valve 14, the air-fuel ratio changes in the at least one Cylinder 3. In the case of an increase in the setpoint engine torque, this can be compensated conventionally by a timely post-injection of fuel.

in the in 2 The signal-time diagram shown shows the cases of increasing and reducing the setpoint engine torque S _setpoint . The representations are based on a crankshaft angle °KW in order to be able to represent the curves independently of the engine speed. You can see the time profiles of the activation of the injection valves (K1) (in the form of a control voltage U _inj at the injection valve 11), the intake manifold pressure p _s (K2) and the throttle valve position (K3). A change in the throttle valve position TPS, which leads to an increased air filling in the cylinder 3 of the internal combustion engine 2, can be seen in a time period B1. Post-injections N1, N2 take place to maintain an optimal air-fuel ratio.

If the setpoint engine torque is reduced during the time range B2 after the metering of the fuel quantity r for the next work cycle, an excessive fuel quantity r for the reduced air quantity is injected. This leads to an overly rich air-fuel mixture that cannot be compensated for by known measures.

According to the invention, it is now provided that the setpoint throttle valve position is specified synchronously with the power strokes of the internal combustion engine 2 . This can be done, for example, using the in 3 shown function block diagram are made. With the aid of the gas actuation, the driver specifies a target engine torque M _target , which _is converted into an air charge and a target throttle valve position S target via a torque calculation path 21 known per se. Furthermore, a current crankshaft position KW is detected via a position encoder 13 of the crankshaft.

A fuel quantity r to be injected is determined in an injection quantity calculation block 23 as a function of the determined air charge.

A coordination block 22 can provide that after the determination of the fuel quantity r to be injected or after the start of the injection of the fuel quantity r, any change in the throttle valve position S _desired requested by a user, ie the specification of the desired throttle valve position, until the intake valve closes 14 is delayed and a corresponding modified target throttle valve position S' _target is provided.

The modified setpoint throttle valve position S′ _setpoint can be passed on to a position controller 24 for generating a manipulated variable for the throttle valve controller 8 for implementation by the throttle valve controller 8 .

As a rule, the fuel quantity r is metered synchronously with a crankshaft angle KW, so that the calculation of the fuel quantity r is generally already completed before the intake valve 14 opens. Therefore, the coordination block 22 can provide for optimizing the implementation of the desired throttle valve position in such a way that a desired (preferably ideal) composition of the air-fuel mixture in the combustion chamber at the time of intake valve closing is ensured. In particular, it can be provided that the implementation of the setpoint throttle valve position is delayed from the point in time at which the fuel quantity r was calculated until the crankshaft angle of the closing of the intake valve 14 .

Alternatively, the level of a sudden change in the setpoint throttle valve position S _setpoint can be reduced, so that the effect of the change in charge caused thereby in the cylinder 3 of the internal combustion engine 2 is limited. In particular, the gradient of a change in the setpoint throttle valve position S _setpoint can be limited.

In addition, the type of coordination can be handled differently in the coordination block 22 depending on the direction of the change in the setpoint throttle valve position S _setpoint . For example, when there is a request to open throttle valve 7, the change in setpoint throttle valve position S _setpoint can be limited to a level that can be compensated for by a function for carrying out subsequent post-injections. On the other hand, when there is a request for closing the throttle valve, ie a reduction in the setpoint throttle valve position, the change the setpoint throttle valve position S _setpoint is actually suppressed until the point at which intake valve 14 closes.

Furthermore, when there is a request for opening the throttle valve 7, the setpoint throttle valve position can be limited in the coordination block 22 so that a maximum charge is not exceeded for which the compression work can still be performed by the kinetic energy stored in the system.

This prevents internal combustion engine 2 from stalling even if misfiring occurs.

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102016200723 A1 [0005]

Claims (13)

Method for operating an engine system (1) with an internal combustion engine (2) with at least one cylinder (3), in particular an internal combustion engine (2) with a ratio between cylinder displacement and an intake manifold volume (SV) connected thereto of greater than 1, in particular greater 2, with the following steps: - providing a request for a target engine torque (M _target ); - Determining a target throttle valve position (S _target ) for adjusting a throttle valve (7) for controlling an air supply into the internal combustion engine (2) as a function of the target engine torque (M _target ); - Modifying a profile of the target throttle valve position (S _target ) depending on the crankshaft angle of a crankshaft of the internal combustion engine (2) in order to provide a modified target throttle valve position (S' _target ) so that the change in air charge during injection of fuel into a intake manifold of the internal combustion engine (2) is reduced; - Operation of the internal combustion engine (2) depending on the modified target throttle position (S ' _target ). procedure after claim 1 , wherein a change in the target throttle valve position (S _target ) provided is permitted or delayed synchronously with the power strokes of the at least one cylinder (3) of the internal combustion engine (2). procedure after claim 1 or 2 , wherein a change in the target throttle valve position (S _target ) is permitted or delayed depending on the point in time when a fuel quantity (r) to be injected is determined. Procedure according to one of Claims 1 until 3 wherein a change in the target throttle valve position (S _target ) is delayed after a timing of setting the amount of fuel to be injected (r) or after a timing of starting injection of the amount of fuel (r). Procedure according to one of Claims 1 until 4 wherein a request for a change in target throttle position (S _target ) within the intake stroke is modified to be implemented in a crankshaft angle range outside of the intake stroke. Procedure according to one of Claims 1 until 5 , wherein a gradient or an amount of a change in the target throttle valve position (S _target ) during a period between the start of injection or the end of the calculation of the fuel quantity to be injected and the closing of the intake valve (14) for a relevant cylinder (3) are limited to limit change in air charge during the period. procedure after claim 6 , with an increase in the requested setpoint engine torque after opening the throttle valve (7), the resulting change in the setpoint throttle valve position (S _setpoint ) is limited to an extent that can be compensated for by a function for carrying out subsequent post-injections. procedure after claim 6 or 7 , with a reduction in the required target engine torque (M _target ) after opening the throttle valve (7), the resulting change in the target throttle valve position (S _target ) is suppressed until the point at which the intake valve (14) closes. Procedure according to one of Claims 6 until 8th , With an increase in the required target engine torque (M _target ) after opening the throttle valve 7, the resulting change in the target throttle valve position (S _target ) is limited to an extent such that a maximum charge is not exceeded for which the compression work can still be performed by the kinetic energy stored in the system. Device, in particular a control unit (10), for operating an engine system (1) with an internal combustion engine (2) with at least one cylinder, in particular an internal combustion engine with a ratio between cylinder displacement and an intake manifold volume (SV) connected thereto of greater than 1, in particular greater than 2, the device being designed to: - receive a request for a target engine torque (M _target ); - Determining a target throttle valve position (S _target ) for adjusting a throttle valve (7) for controlling an air supply into the internal combustion engine (2) as a function of the target engine torque (M _target ); - Modifying a profile of the target throttle valve position (S _target ) depending on the crankshaft angle of a crankshaft of the internal combustion engine (2) in order to provide a modified target throttle valve position (S' _target ) so that the change in air charge during injection of fuel into a intake manifold of the internal combustion engine (2) is reduced; - Operation of the internal combustion engine (2) depending on the modified target throttle position (S ' _target ). Engine system with an internal combustion engine (2) and a device (10). claim 10 . Computer program with program code means that is set up to implement a method according to one of Claims 1 until 9 execute when the computer program is executed on a data processing device. Machine-readable storage medium with a computer program stored on it claim 12 .

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