DE102009000292A1 - Method for producing control or diagnostic variable for turbocharger, involves providing variable geometry to turbocharger in internal combustion engine, where control or diagnostic variable is based on turbine output of turbocharger - Google Patents

Abstract

The method involves providing variable geometry to a turbocharger in an internal combustion engine. A control variable or diagnostic variable is based on a turbine output (PT-MEAS) of the turbocharger, where the turbine output is produced by a compressor output of the turbocharger and the moment of inertia of the rotating units of the turbocharger. Independent claims are also included for: (1) an arrangement for producing a control or diagnostic variable for a turbocharger; and (2) an internal combustion engine with a turbocharger.

Description

The This invention relates to a method and an assembly for recovery a control and / or diagnostic quantity for a variable geometry turbocharger of an internal combustion engine, regulatory and diagnostic methods and arrangements based thereon as well as a suitably equipped internal combustion engine.

at Turbochargers with variable geometry, also VNT (Variable Nozzle Turbocharger) called, are advanced exhaust gas turbocharger for Diesel or gasoline engines, as well as conventional turbochargers have a turbine and a compressor impeller by a common wave are interconnected, and where in addition, the vanes on the exhaust side pneumatically or are adjustable by electric motor. This allows you to operate according to the exhaust gas amount and / or the boost pressure demand a more efficient Reach operating point of the turbocharger.

It are VNT turbochargers with an improved design and a Decreased total moment of inertia known to provide improved transient operating performance have, d. h., the current operating power is during transitions between engine operating conditions - such. B. load changes - quickly changeable. Due to a better charge pressure control with engine acceleration and a more advantageous in terms of emissions faster Exhaust gas recirculation control (faster increase the exhaust back pressure) improves the useful factor of such Turbocharger. Strict emission requirements can only be met Meet a turbocharger over long periods of time works optimally in every operating area.

in the The prior art uses either a feedforward control by means of an open loop based on speed and torque setpoint tables or closed-loop control Base of boost pressure setpoint error.

Of the VNT turbocharger itself is not directly based on the boost pressure, but based on the turbine pressure ratio, the speed and the gas stream operated. In addition, the transition operating performance is based on the power difference between the generator (the turbine) and the compressor. If the turbine is not optimal on the compressor is tuned, the operating power decreases as the turbine the power required to charge the incoming fresh air can not produce the compressor. This also leads to emission problems.

If no VNT position feedback is provided, a Boost pressure errors are used to slow the turbocharger operating performance to recognize. However, such a diagnosis is slow, and it can have many different causes for such a boost error give, for. B. often a blocked or jammed VNT adjustment, but also a leak in the fresh air line or an overloaded Exhaust particulate filter.

If a VNT position feedback is provided, the Position control variable by means of a closed Control circuit to be monitored. If the position rule size is large, a VNT disorder is diagnosed (eg blocked or clamped VNT adjustment). This method also has disadvantages, since the ECU (Electronic Control Unit, electronic Control unit) of the engine an additional measurement signal required as input signal, namely the VNT position feedback, which requires increased effort, and since the real feedback drifting, especially in the hot and sooty Exhaust environment.

In the DE 601 14 979 T2 It is proposed to control a variable geometry turbocharger by means of a controlled variable proportional to the speed of the turbocharger. The exact relationship between the controlled variable and the speed of the turbocharger and the manner of control is not disclosed.

Of the The invention is based on the object of providing a more suitable control and / or diagnostic size for a turbocharger with variable geometry and a VNT control based on it and to provide VNT diagnosis.

These Task is achieved by a method according to claim 1, 4 or 6, by an arrangement according to claim 9, 10 or 11 and by an internal combustion engine according to claim 12 solved.

The invention is based on the recognition that the disadvantages of the current situation lead to potential improvements, if the engine in the sense of the required turbine power (= compressor power in steady state) in addition to the boost pressure in the intake manifold is controlled, whereby a better transition operating performance, better and faster control and simpler and more reliable diagnostic functions can be realized. In particular, the evaluation according to the invention of the angular velocity of the turbocharger, ie its rotational speed, on the one hand opens up improved control possibilities and on the other hand offers better diagnostic options.

Further Embodiments of the invention are the description and the dependent claims refer to.

The Invention is described below with reference to the illustrated in the drawings Embodiment exemplified in more detail. Show it:

1 a typical map of the compressor power in the steady state, which is equal to the turbine power in this state, as a function of the engine speed and the displayed torque setpoint; and

2 a block diagram for explaining the control structure for the turbocharger.

in the Embodiment includes an internal combustion engine a variable geometry turbocharger, also called VNT below, a tachometer for the shaft of the turbocharger, more Sensors for determining additional measured variables, which are mentioned below, and an ECU.

At equilibrium, the compressor power is equal to the turbine power and the turbocharger shaft is not accelerating. In general, however, the turbine torque T _T and the compressor torque T _C are linked together as follows: Jω. = T T - T C (1) where J is the moment of inertia of the rotating parts of the turbocharger, ω is the angular velocity of the turbocharger, ie its speed, and ω. is the derivative of the angular velocity, ie the angular acceleration. Multiplying equation (1) by the angular velocity ω and combining the friction torque with the turbine torque, one obtains when the turbine power P is _T and the compressor power P _C is: Jω .ω = T T ω - T C ω = F T - P C (2)

Since there is no pumping fluctuation and the temperature variation upstream of the compressor is much smaller than upstream of the turbine (ie, in the exhaust manifold), the compressor power can be easily calculated. The turbine power P _T can be calculated in accordance with equation (2) as follows: P C + Jω .ω = P T (3)

There the moment of inertia J of the rotating parts of the turbocharger is known and whose speed ω, from which also ω. reveals Measured by a tachometer, the transition turbine power calculated from the compressor capacity.

mit

η_C

Kompressorwirkungsgrad (gesamt zu statisch (total to static)),

π_C

Kompressordruckverhältnis,

γ

Verhältnis c_p/c_ν der spezifischen Wärmekapazität der Frischluft bei konstantem Druck zur spezifischen Wärmekapazität der Frischluft bei konstantem Volumen,

ṁ_corr

korrigierter Kompressorgasstrom und

T_upc

Temperatur stromaufwärts des Kompressors.

By means of a standard sensor equipment on the fresh air side, which is normally provided in modern engines, the pressure and the temperature upstream of the compressor, the pressure downstream of the compressor (normally measured in the inlet manifold) - and thus the pressure ratio along the compressor - Air mass flow, the overall efficiency to static (a function of speed and pressure ratio) and the temperature upstream of the compressor are determined. Then you get the compressor performance as follows:

With

η _C

Compressor efficiency (total to static),

π _C

Compressor pressure ratio,

γ

Ratio c _p / c _{ν of} the specific heat capacity of the fresh air at constant pressure to the specific heat capacity of the fresh air at constant volume,

_corr

corrected compressor gas flow and

T _upc

Temperature upstream of the compressor.

mit:

ṁ

Frischluftstrom, vom Sensor oder geschätzt

T_ref

Referenztemperatur

P_upC

Druck aufwärts des Kompressors

P_ref

Referenzdruck

Here ṁ _{corr is} composed of:

With:

m '

Fresh air flow, from the sensor or estimated

T _ref

reference temperature

P _upC

Pressure up the compressor

P _ref

reference pressure

mit

T_dnC

Temperatur stromabwärts des Kompressors.

The compressor efficiency η _C is again composed of:

With

T _dnC

Temperature downstream of the compressor.

• – zur Regelung mit geschlossenem Regelkreis auf Basis der Leistung für eine bessere Übergangs-Betriebsleistung, da die Differenz zwischen der Turbinenleistung und der Kompressorleistung die Übergangs-Betriebsleistung (oder Beschleunigung) darstellt;
• – zur Vorwärtsregelung mit offenem Regelkreis auf Basis der Leistung für modellbasierte Turbolader-Steuerung;
• – zur Diagnose von Turbolader-Störungen durch Schätzen der ”Effizienz” der Turbine. Wenn die Turbine mehr oder weniger Leistung erzeugt als anhand der Berechnung der Kompressorleistung erwartet, gibt es eine Störung oder ein Problem, z. B. eine blockierte Schaufelverstellung für die Leitschaufeln des Turboladers auf der Abgasseite, ein Lagerproblem, einen Ölverlust od. dgl.

The turbine power P _T can be used as follows:

• - closed-loop control based on power for better transient operating performance, as the difference between turbine power and compressor power represents transient operating power (or acceleration);
• - open-loop forward control based on model-based turbocharger control power;
• - To diagnose turbocharger malfunctions by estimating the "efficiency" of the turbine. If the turbine produces more or less power than expected from the compressor power calculation, there is a fault or problem, e.g. B. a blocked blade adjustment for the vanes of the turbocharger on the exhaust side, a storage problem, an oil loss od. Like.

1 Figure 12 shows a typical map of steady state compressor power that is equal to turbine power in this state as a function of engine speed and indicated torque setpoint. This map is used in the form of a look-up table or the like in the closed-loop control. Note that there is no correction for transient operation, which is still to be added in practice.

2 shows the control structure for the turbocharger based on the performance in detail. From the engine speed N and the torque setpoint TQI_SP is in a two-dimensional lookup table 2 determines an equilibrium power requirement PT_DMD. This is the input variable 1 of a three-dimensional VNT setpoint chart 4 used. As inputs two and three of the VNT setpoint card 4 For example, a corrected turbocharger speed and a corrected turbine gas flow are used. The VNT setpoint card 4 provides a feedforward set point VNT_OL_SP.

In the blocks 6 to 14 According to equations 3 and 4, the measured turbine power PT_MEAS is calculated. In the block 16 is then formed by subtraction of PT_DMD and PT_MEAS a power setpoint error PT_ERR, which by a PID controller (proportional + integrating + abs tend) 18 and a saturation trimmer 20 is directed. The resulting rule variable VNT_CL_TERM is in the block 22 to the feedforward setpoint VNT_OL_SP from the VNT setpoint map 4 added. The sum VNT_CL_SP becomes in a saturation trimmer 24 truncated before being fed as a controlled variable VNT_CL_SP_FINAL the VNT component driver to operate the blade adjustment for the vanes of the turbocharger on the exhaust side.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 60114979 T2 [0008]

Claims (12)

Method for obtaining a control and / or diagnostic variable for a variable geometry turbocharger in an internal combustion engine, characterized in that the control and / or diagnostic quantity is based at least on a turbine power P _{T of} the turbocharger, which is obtained by P _T = P _C + J, where P _{C is} the supercharger power of the turbocharger, J is the moment of inertia of the rotating parts of the turbocharger, ω is the angular velocity of the turbocharger, and ω. whose angular acceleration is. A method according to claim 1, characterized in that the compressor power P _{C of} the turbocharger is obtained by

where η _{C is} the compressor efficiency, π _{C is} the compressor pressure ratio, c _{p is} the specific heat capacity of the fresh air at constant pressure, γ is the ratio c _p / c _{ν of} the specific heat capacities of the fresh air at constant pressure or constant volume, ṁ _corr der _{Mass air flow} through the compressor is and T _{upc is} the temperature upstream of the compressor. Method according to claim 1 or 2, characterized that the control and / or diagnostic size also based on a compressor power demand in the equilibrium state, depending on the current engine speed and a torque setpoint is determined. Method for controlling a turbocharger with variable Geometry of an internal combustion engine, characterized in that the turbocharger controlled by a controlled variable is obtained by a method according to one of the claims 1 to 3 is won. Method according to claim 4, characterized in that that the controlled variable for controlling a blade adjustment for the guide vanes of the turbocharger on the exhaust side is used. Method for detecting a malfunction in a variable geometry turbocharger of an internal combustion engine, characterized in that a diagnostic size is monitored which is obtained by a method according to claim 1. A method according to claim 6, characterized in that the turbine power P _{T of} the turbocharger is compared with an expected value and is closed in the case of excessive deviation from the expected value to a fault of the turbocharger. Method according to claim 7, characterized in that that the disturbance of the turbocharger in a blocked blade adjustment, There is a storage problem and / or a loss of oil. Arrangement for obtaining a control and / or diagnostic quantity for a variable geometry turbocharger of an internal combustion engine, characterized in that the arrangement for carrying out A method according to any one of claims 1 to 3 is. Arrangement for controlling a turbocharger with variable Geometry of an internal combustion engine, characterized in that the arrangement for carrying out a method according to claim 4 or 5 is formed. Arrangement for detecting a malfunction in a variable geometry turbocharger of an internal combustion engine, characterized in that the arrangement for carrying out A method according to any one of claims 6 to 8 is. Internal combustion engine with a turbocharger with variable Geometry, characterized in that the internal combustion engine for Implementation of a method according to one of the claims 1 to 8 is set up.