DE102012003581B3 - Compressor governor for a combustion engine for inserting into a motor vehicle, has an interface for combustion engine, through which a control action on the combustion engine is carried out - Google Patents

Abstract

The compressor governor has an interface for combustion engine (1), through which a control action on the combustion engine is carried out, and another interface, through which actual measuring parameters (15) of the combustion engine are determined. A mathematical model is operated parallel to combustion engine. A calculation unit (8,9) calculates an control parameter (3,4). The structure of the compressor governor has two parallely acting interdependent servo loops. An independent claim is included for a method for operating an internal combustion engine for use in a motor vehicle.

Description

Technical area

The present invention relates to an idle speed controller and a method for operating internal combustion engines for use in a motor vehicle.

State of the art

In modern controls and regulations for internal combustion engines, a speed control in the idle state, ie in the lower load and speed range, made for use in conventional vehicles. In the idling state of the internal combustion engine, the speed of the output shaft or the crankshaft is controlled in order to reduce pollutant emissions and to keep fuel consumption low. The main task of the control is to keep the speed of the crankshaft constant at different power requirements of consumers, for example, air conditioning or generator. Other factors influencing environmental and vehicle parameters, such as a temperature of the internal combustion engine or a different battery state of charge. The aim is therefore the adjustment of the idle speed to a target speed and their constant holding at different load torques. In this case, load moments are understood to mean moments acting on the crankshaft directly or indirectly braking, which are caused, for example, by the generator, the air conditioning system, support units such as oil or power steering pump.

Conventional idle controllers are designed as a closed loop. In this case, a current rotational speed of the crankshaft is compared with a target rotational speed and, in accordance with the difference formed thereby, a manipulated variable for engagement with an actuator with which the rotational speed can be controlled is carried out by a regulator. The controller is adapted to the control loop with its controlled system and possible disturbances and measuring devices. For the detection of the speed, a Kurbelwellengeberrad is used with teeth. As an actuator for speed control of the internal combustion engine, an intervention can be made, for example, on a throttle valve, an ignition angle or on injection parameters, such as injection quantity and injection timing.

Furthermore, control methods based on mathematical dynamic models for determining state variables are used to represent the dynamic behavior of the internal combustion engine. In these control methods, the internal combustion engine is regarded as a dynamic system whose internal states are described by state variables. By means of suitable mathematical dynamic models, the further development over time as well as measurable output variables of the dynamic system are calculated and the results are fed back as feedback variables into the calculation of the control parameters for the rotational speed.

From the patent DE 33 33 392 C2 a method for controlling the idling speed of an internal combustion engine is known in which a plurality of linear, mathematically dynamic models are stored according to different operating conditions of the internal combustion engine. Based on the present operating condition of the internal combustion engine, a model adapted to the operating point for the simulation of the behavior is selected. This results in high accuracy using linear models and low-order approximation methods. It is described that an improvement of the control behavior is achieved by the simultaneous change of several control parameters. As an example of control parameters, the intake air amount and the Zündwinkelvorverstellung be listed.

In the published patent application DE 36 05 282 A1 a method is described in which the dynamic system, in particular an internal combustion engine, is modeled by a dynamic model, in particular an equation of state and an output equation, with which a linear approximation is fulfilled. In the event that the mode of operation of the internal combustion engine is not linear, a division of the operating range into a plurality of linear operating states is carried out and, accordingly, a plurality of dynamic models is established. It is stated that to represent a complicated system, such as an internal combustion engine, a dynamic model is generated by various methods, such as a least squares method. Furthermore, it is described that so-called state observers are used with which the state is estimated when the state of the internal combustion engine is difficult to determine.

From the German translation of a European patent specification DE 691 00 125 T2 A method is known for the feedback control of the idle speed of an internal combustion engine in which a difference or error deviation between a detected engine speed and a target speed or a detected air pressure at the inlet port and a predetermined reference pressure is calculated. In the method, a state feedback is used which is based on an optimal controller provided with a quadratic quality criterion, ie an LQ controller (linear quadratic regulation). Furthermore, a simplified linear model is used, which the Changes relative to corresponding reference values.

Object of the invention

The present invention is based on the object to provide an improved idle speed controller and a method for operating internal combustion engines for use in a motor vehicle.

Solution of the task

The object is achieved by an idle controller according to the features of claim 1 and a method according to the features of claim 7. Advantageous developments emerge from the subclaims and the embodiment.

Description of the invention

The invention provides an improved idle speed controller and an improved method for operating internal combustion engines, with which a comfortable speed control at idle of an internal combustion engine is made possible. The idling of an internal combustion engine defines itself in operation at low crankshaft speeds corresponding to a range of application of the internal combustion engine between 200 and 2500 revolutions per minute, which just as much drive power is delivered by the internal combustion engine, as is necessary for maintaining the operation of the internal combustion engine and its ancillaries themselves. For the speed control, the invention uses a non-linear mathematical model, which calculates the variables relevant for the idling control more accurately compared to the known methods. This is followed by a mathematically exact description and accordingly a higher robustness compared to the known methods.

The invention is based on a control with a parallel to the actual, real internal combustion engine non-linear mathematical model. For the control of the idling speed, that is the crankshaft speed in the idling state of the internal combustion engine, the deviation between a real crankshaft speed of the real engine and a modeled by the non-linear mathematical model crankshaft speed of the modeled internal combustion engine is returned and used to shift or to correct a setpoint input for the crankshaft speed. The corrected setpoint specification for the crankshaft speed is further processed to a first control variable for influencing the combustion. The first manipulated variable is a manipulated variable z directly influencing the combustion. For example, the ignition angle at which the efficiency of combustion in a combustion chamber of the internal combustion engine can be varied so as to control the combustion resulting torque and thus the crankshaft speed.

Furthermore, a setpoint specification for a torque reserve is provided, which is processed together with the corrected setpoint input for the crankshaft speed to another manipulated variable to control the air charge in a combustion chamber of the internal combustion engine. The further manipulated variable can be a throttle valve angle with which the air charge, ie the air mass in a combustion chamber of a cylinder of the internal combustion engine, can be varied in order to control a maximum torque that can be achieved from the combustion. Based on a current torque of the internal combustion engine, a torque reserve is to be provided, wherein the maximum achievable torque is composed of a current setpoint or actual torque and the torque reserve. For example, a torque reserve is realized by a Zündwinkelsteuerung by an air charge is set, which allows a lying above the currently requested actual torque lying maximum achievable torque and Zündwinkelvorhalt out to a non-torque optimal ignition angle torque reserve for the set air filling is achieved. In the event of a sudden increase in demanded torque, for example, when switching on an air conditioner, the additionally requested torque can be compensated by the fast-acting ignition angle control. The slower to be controlled path of air filling is subsequently tracked to rebuild the torque reserve.

Due to the exact, non-linear modeling of the controlled system and the associated model accuracy reduces the risk of an unstable or oscillating control loop, which leads to an improvement in the robustness of the scheme. In addition, an explicit consideration of manipulated variable restrictions as a further advantage is easily possible.

To improve the control at different load or braking torques, a non-linear disturbance observer is introduced. Based on an exact model of the crankshaft dynamics, the latter estimates an effective load or braking torque which uses a measured rotational speed of the crankshaft, a measured fill-determining variable, for example an intake manifold pressure or an air mass flow, and a modeled driving torque as input variables. The speed of this estimation can be adjusted without affecting the dynamics of the transfer of leadership.

The control of the crankshaft speed in the idling range can be activated via a threshold, which is compared with a difference between the real speed and a desired speed. The nonlinear mathematical model is then initialized with current measurements of crankshaft speed, inflation determining magnitude, operating temperature, and engine intake air temperature. For this, in addition to the identification of the nonlinear mathematical model, the method requires only two parameters for specifying the desired dynamics of the guide transmission and only one parameter for setting the nonlinear disturbance observer.

The invention advantageously utilizes the approximate independence of the torques of the internal combustion engine from the crankshaft dynamics in the region close to the idling region. The device according to the invention provides an idle controller with a control structure having two parallel control loops, wherein a first control loop adjusts an indicated setpoint torque with high dynamics and a second control loop sets a maximum torque that can be achieved if necessary to provide the torque reserve. However, the second control loop is closed only when the torque reserve of the internal combustion engine is used up. On the other hand, the maximum available torque is only controlled. The achievable maximum torque can be determined from the current filling information. Both control loops are assigned the nonlinear disturbance observer, which estimates a load or braking torque and provides it for the calculation of the manipulated variables.

Accordingly, the invention provides an advantageous idling controller of an internal combustion engine for use in a motor vehicle, wherein the idle controller at least one interface to the internal combustion engine, via which a control intervention on the internal combustion engine is feasible, at least one further interface, via which current measured variables of the internal combustion engine can be detected, at least one operated parallel to the internal combustion engine mathematical model and at least one arithmetic unit for calculating at least one manipulated variable, wherein the structure of the idle controller comprises at least two mutually parallel, interdependent control loops, wherein in a first control loop, a combustion directly influencing first manipulated variable and in a second Control loop a the air filling influencing further control variable is calculated and at least one Störgrößenbeobachter with the at least two control loops ve is rbunden, which estimates a load or braking torque and the at least one computing unit for calculating at least one manipulated variable supplies.

In accordance with the invention, the first control loop operates with comparatively higher dynamics than the second control loop, since a direct influencing of the combustion and thus a significantly faster intervention on the internal combustion engine are made possible by means of the first control variable. By means of the further manipulated variable for influencing the air filling only a delayed by the inertia of the air path intervention on the operation of the internal combustion engine is possible. Furthermore, the provision of the torque reserve is subject to a lower requirement for a controller dynamics.

According to the invention, the first control loop advantageously comprises a first arithmetic unit of the crankshaft speed for calculating an ignition angle as manipulated variable and the second control loop a second arithmetic unit of the air charge for calculating a throttle angle or a Hubkurvenverstellung of gas exchange valves as manipulated variable. According to the invention, the mathematical model operated parallel to the internal combustion engine is advantageously designed as a nonlinear mathematical model. Furthermore, the disturbance observer is designed as a nonlinear disturbance observer. With the nonlinear disturbance observer, at least one current measured variable relating to the state of the internal combustion engine is processed to an estimated load or braking torque. In this case, a fill-determining variable, for example an intake manifold pressure or an air mass flow, and / or a crankshaft rotational speed is used as the current measured variable.

The idle controller according to the invention processes a setpoint input as a reference variable for a crankshaft speed in the first control loop and a setpoint input as a reference variable for a torque reserve, which is required for comfortable idling control, in the second control loop. A control of the crankshaft speed in the first control loop processes the setpoint input for the crankshaft speed corrected by the difference between a current crankshaft speed and a crankshaft speed of the internal combustion engine calculated in parallel using the non-linear mathematical model to a manipulated variable which is used both to control the internal combustion engine and as an input for the engine nonlinear mathematical model is used. A regulation of the air charge in the second control loop processes the setpoint specification for the torque reserve and the corrected setpoint input for the crankshaft speed to a manipulated variable, which also serves both to control the internal combustion engine and as an input for the non-linear mathematical model.

The nonlinear disturbance observer processes the manipulated variables for crankshaft speed and Air filling and current measurements from the operation of the internal combustion engine to make an estimate of the fault and to make a connection to the controller for crankshaft speed and air filling to improve the noise suppression. The input values are processed in the nonlinear disturbance observer to an estimated load or braking torque and integrated for control within the two control loops. According to the invention, the current measured variables are advantageously a current crankshaft speed and a current charge information. The filling information is to be understood as a measured variable via which a direct or indirect determination of the air mass in the respective cylinder of the internal combustion engine is possible.

Accordingly, an advantageous according to the invention method for operating an internal combustion engine for use in a motor vehicle, wherein the internal combustion engine is in the idle state and the crankshaft speed of the internal combustion engine is controlled using an idle controller. The idle controller comprises at least one interface to the internal combustion engine, via which a control intervention on the internal combustion engine can be performed, at least one further interface via which current parameters of the internal combustion engine can be detected, at least one parallel to the internal combustion engine operated mathematical model and at least one arithmetic unit for calculating at least one manipulated variable , Based on a setpoint input for a crankshaft speed in a first control loop, a first control variable for influencing the combustion is calculated and used for engagement with the internal combustion engine and as an input in a parallel to the internal combustion engine operated non-linear mathematical model. Based on a setpoint specification for a torque reserve in a second control loop, a further manipulated variable for influencing the air charge is calculated and used for engagement with the internal combustion engine and as an input variable in a parallel to the internal combustion engine operated nonlinear mathematical model. A speed difference of a modeled by the non-linear mathematical model, ie calculated crankshaft speed and a current real crankshaft speed of the internal combustion engine is used to correct the setpoint input for the crankshaft speed. This corrected setpoint specification for the crankshaft speed for the calculation of new manipulated variables for influencing the combustion and the air filling is used in the respective control loop. A disturbance observer estimates a load or braking torque based on the information about the current manipulated variables and current measured variables for the state of the internal combustion engine and makes this available to the calculation of the manipulated variables in the respective control loop.

embodiment

By way of example, an embodiment of the device according to the invention is shown here. In the accompanying figure, a schematic representation of the idle controller according to the invention is shown.

The idle controller comprises several interfaces with an internal combustion engine ( 1 ), via which a control of the internal combustion engine ( 1 ) and what information about the operation of the internal combustion engine ( 1 ), how at least one current crankshaft speed and a current charge information can be determined. Parallel to the real operation of the internal combustion engine ( 1 ) the real operation of the internal combustion engine ( 1 ) by means of a nonlinear mathematical model ( 2 ). During operation of the internal combustion engine ( 1 ) results as a function of manipulated variables ( 3 . 4 ) a real crankshaft speed ( 5 ) and a modeled crankshaft speed ( 6 ) of the internal combustion engine whose deviation from each other as a speed difference ( 7 ) for a computing unit of crankshaft speed ( 8th ) in a first control loop and for an arithmetic unit of the air filling ( 9 ) is returned in a second control loop. In the first control loop, a setpoint input for a crankshaft speed ( 10 ) about the returned speed difference ( 7 ) between the real and modeled crankshaft speed ( 5 . 6 ) to a corrected setpoint specification for the crankshaft speed ( 11 ) and to a first manipulated variable ( 3 ), for example, to a Zündwinkelsollwert, processed, which is then set to control the real internal combustion engine and further as the first input of the nonlinear mathematical model ( 2 ) serves. In the second control loop, the speed difference ( 7 ) between the real and modeled crankshaft speed ( 5 . 6 ) corrected setpoint specification for the crankshaft speed ( 11 ) and a setpoint specification for a torque reserve ( 12 ) to another manipulated variable ( 4 ), for example, a throttle target angle, which is then also set to control the real internal combustion engine and further as a further input variable of the nonlinear mathematical model ( 2 ) serves. By means of a disturbance variable observer ( 13 ) is a load or braking torque ( 14 ) and for calculating the manipulated variables ( 3 . 4 ) in the arithmetic units ( 8th . 9 ) of the two control loops included. For estimating the load or braking torque ( 14 ), the manipulated variables ( 3 . 4 ) of the two control loops as well as current measured variables ( 15 ) the crankshaft speed and a current filling information of the real internal combustion engine ( 1 ) used.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

nonlinear mathematical model

3

first manipulated variable

4

additional manipulated variable

5

real crankshaft speed

6

modeled crankshaft speed

7

Speed difference

8th

Calculation unit of the crankshaft speed

9

Arithmetic unit of the air filling

10

Setpoint specification for a crankshaft speed

11

corrected setpoint specification for the crankshaft speed

12

Setpoint specification for a torque reserve

13

disturbance observer

14

Load or braking torque

15

current measurements

Claims (7)

Idling controller of an internal combustion engine ( 1 ) for use in a motor vehicle, wherein the idle controller at least one interface to the internal combustion engine ( 1 ), via which a control intervention on the internal combustion engine ( 1 ), at least one further interface via which current measured variables ( 15 ) of the internal combustion engine ( 1 ) are detectable, at least one parallel to the internal combustion engine ( 1 ) operated mathematical model and at least one arithmetic unit ( 8th . 9 ) for calculating at least one manipulated variable ( 3 . 4 ), characterized in that the structure of the idle controller comprises at least two parallel-acting, mutually dependent control loops, wherein in a first control loop, a first control variable directly influencing the combustion ( 3 ) and in a second control loop a further control variable influencing the air charge ( 4 ) and at least one disturbance observer ( 13 ) is connected to the at least two control loops, which a load or braking torque ( 14 ) and the at least one arithmetic unit ( 8th . 9 ) for calculating at least one manipulated variable ( 3 . 4 ) feeds. Idling controller of an internal combustion engine ( 1 ) for use in a motor vehicle according to claim 1, characterized in that the first control loop with higher dynamics than the second control loop works. Idling controller of an internal combustion engine ( 1 ) for use in a motor vehicle according to any one of the preceding claims, characterized in that the first control loop, a first arithmetic unit of the crankshaft speed ( 8th ) for calculating an ignition angle as the first manipulated variable ( 3 ) and the second control loop, a second computing unit of the air filling ( 9 ) for calculating a throttle angle or a stroke curve adjustment of gas exchange valves as another control variable ( 4 ). Idling controller of an internal combustion engine ( 1 ) for use in a motor vehicle according to one of the preceding claims, characterized in that the at least one parallel to the internal combustion engine ( 1 ) operated mathematical model as a nonlinear mathematical model ( 2 ) is executed. Idling controller of an internal combustion engine ( 1 ) for use in a motor vehicle according to one of the preceding claims, characterized in that at least one disturbance observer ( 13 ) as a nonlinear disturbance observer ( 13 ) is executed. Idling controller of an internal combustion engine ( 1 ) for use in a motor vehicle according to claim 5, characterized in that by means of the nonlinear Störgrößenbeobachter ( 13 ) at least one current measurement ( 15 ) to the state of the internal combustion engine ( 1 ) to a calculated load or braking torque ( 14 ) is processable, wherein the at least one current measured variable ( 15 ) is a filling information and / or a crankshaft speed. Method for operating an internal combustion engine ( 1 ) for use in a motor vehicle, wherein the internal combustion engine ( 1 ) is in the idle state and the crankshaft speed of the internal combustion engine ( 1 ) is controlled using an idle controller and the idle controller at least one interface to the internal combustion engine ( 1 ), via which a control intervention on the internal combustion engine ( 1 ), at least one further interface via which current measured variables ( 15 ) of the internal combustion engine ( 1 ) are detectable, at least one parallel to the internal combustion engine ( 1 ) operated mathematical model and at least one arithmetic unit ( 8th . 9 ) for calculating at least one manipulated variable ( 3 . 4 ), characterized in that based on a setpoint input for a crankshaft speed ( 10 ) in a first control loop, a first manipulated variable directly influencing the combustion ( 3 ) and for intervention on the Internal combustion engine ( 1 ) and as input into a parallel to the internal combustion engine ( 1 ) operated nonlinear mathematical model ( 2 ), further based on a setpoint specification for a torque reserve ( 12 ) in a second control loop another manipulated variable ( 4 ) is calculated for influencing the air charge and for engaging the internal combustion engine ( 1 ) and as input into a parallel to the internal combustion engine ( 1 ) operated nonlinear mathematical model ( 2 ) is used, wherein a speed difference ( 7 ) one by means of the nonlinear mathematical model ( 2 ) modeled crankshaft speed ( 6 ) and a current real crankshaft speed ( 5 ) of the internal combustion engine ( 1 ) for correcting the setpoint specification for the crankshaft speed ( 10 ), this corrected setpoint specification for the crankshaft speed ( 11 ) for the calculation of new manipulated variables ( 3 . 4 ) is used to influence the combustion and the air charge in the respective control loop and a Störgrößenbeobachter ( 13 ) based on the information on the current control variables ( 3 . 4 ) and current measured variables ( 15 ) to the state of the internal combustion engine ( 1 ) a load or braking torque ( 14 ) and the calculation of the manipulated variables ( 3 . 4 ) in the respective control loop.

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