KR20170026231A - Method and device for determining of a manipulated variable for a supercharger actuator of a supercharger driven by exhaust gases - Google Patents

Abstract

The present invention relates to a method of operating an internal supercharger (7) driven by an exhaust gas of an engine system (1) with a combustion engine (2). The supercharger (7) includes a turbine (71) with an actuator (74) for a variable adjustment of an efficient turbine structure, and a bypass line (75) bypassing the turbine (71) having an adjustable bypass cross sectional area (A_(Byp)). A method of operating the internal supercharger (7) driven by the exhaust gas comprises: (S1) a step of providing a requested target turbine output (P_(Trbsoll)); (S2) a step of determining an effective target turbine cross sectional area (A_(Trbsoll)) corresponding to the required target turbine output (P_(Trbsoll)) based on a current bypass cross sectional area (A_(Bypist)); and a step of operating the actuator (74) in accordance with the determined effective target turbine cross sectional area (A_(Trbsoll)).

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for determining an operating parameter for a supercharger actuator of an exhaust gas-driven supercharger. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharger actuator for a supercharger,

The present invention relates to a combustion engine having an exhaust gas driven supercharger, and more particularly to a method of driving a supercharger actuator of a turbocharger having a variable turbine geometry.

The feed and combustion engines typically include an exhaust gas driven supercharger, such as, for example, a turbocharger. The turbocharger is used to provide an increased boost pressure to the air supply of the combustion engine, so as to realize an increase in the output of the combustion engine. Typically, the turbocharger includes a turbine that is disposed within the exhaust gas discharge conduit and that can be variably adjusted in its efficiency, i.e., a portion of the mechanical output obtained from the exhaust gas enthalpy provided in the exhaust gas discharge conduit can be set. And the compressor of the supercharger is driven by the converted output. For variable adjustment of the efficiency of the turbocharger, the turbocharger may include a controllable variable turbine structure or a controllable wastegate valve or the like.

According to the present invention, there is provided a method for operating an exhaust gas driven supercharger in an engine system having a combustion engine according to claim 1, and an apparatus and an engine system according to claims of the same claim.

Other configurations are specified in the dependent claim.

According to a first aspect, there is provided a method for operating an exhaust gas driven supercharger in an engine system having a combustion engine, the turbocharger having a supercharger actuator for variable adjustment of an effective turbine structure, And a bypass line having a path cross-sectional area,

Providing a desired target turbine output;

Determining, at the current bypass cross-sectional area, an effective target turbine cross-sectional area corresponding to the desired target turbine output;

And driving the supercharger actuator according to the determined effective target turbine cross-sectional area.

The above-described method for operating an exhaust-gas-driven supercharger in an engine system having a combustion engine comprises the steps of: providing a supercharger actuator for variable adjustment of the turbine structure and a supercharger turbine with a bypass line having an adjustable bypass cross- And is related to the topology of the engine system. In this case, the setting of the turbocharger actuator should be performed directly via information on the effective turbine cross-sectional area corresponding to the required turbine output, or via boost pressure control based on the effective turbine cross-sectional area as a reference variable. In at least partially open bypass lines, the determination of the relationship between the required turbine output and the corresponding effective turbine cross-sectional area forming the operating parameters for the turbocharger actuator of the turbocharger is not simple by conventional approaches.

The above-described method is advantageous in that when the bypass line is at least partially open in the reported effective bypass cross-sectional area for a predetermined output demand for the turbocharger formed from a predetermined boost pressure demand by the engine control, Lt; RTI ID = 0.0 > turbine < / RTI > From the effective turbine cross-sectional area, the corresponding operating parameters for the turbocharger actuator of the turbocharger can be derived.

The computational determination of the effective turbine cross-sectional area to reach a predetermined turbine output or boost output has the advantage that it makes it possible to form the boost pressure faster than the pure boost pressure feedback control. On the other hand, the conventional boost pressure feedback control can respond to the deviation between the target boost pressure and the actual boost pressure, which can be directly or indirectly controlled by the computational determination of the effective turbine cross-sectional area based on the predetermined turbine output It is possible to react directly to a change in the bypass area. Thereby, the turbocharger actuator of the turbocharger can be operated by purely controlled operation or by pilot control, whereby a faster response of the turbocharger actuator to the corresponding demand for turbine output is possible.

Further, the required target turbine output can be preset according to the load requirement for the combustion engine according to the operating state, and in particular, depending on the actual operating state of the supercharger, and in particular according to the speed of rotation of the supercharger, .

According to one embodiment, the turbocharger actuator can be controlled and driven by an operating variable according to the effective turbine cross-sectional area.

The turbocharger actuator can be controlled and driven by an operating variable according to the effective target turbine cross-sectional area.

According to an alternative embodiment, the turbocharger actuator may be driven from an effective target turbine cross-sectional area by an operational parameter formed using a predetermined boost pressure feedback control.

Also, the actual turbine power can be determined from the current load information, in particular from the actual boost pressure, and at the current bypass cross-sectional area, the effective actual turbine cross-sectional area corresponding to the actual turbine power is determined and the turbocharger actuator determines the effective target turbine cross- It is determined according to the actual turbine cross-sectional area.

At the current bypass cross-sectional area, determination of the effective turbine cross-sectional area corresponding to turbine power may include determination of the pressure ratio through the turbine.

According to one embodiment, by being reversed (inversion) of the function of the turbine output of the effective turbine cross-section is performed, and a function of the effective turbine cross-section for the desired turbine output can be determined, for the inversion, of the desired turbine output The maximum value is determined, or numerically determined, using the predetermined dependencies, in particular from the property domain.

The determination of the effective turbine cross-sectional area corresponding to the turbine output may also be performed based on a function of the effective turbine area in relation to the required turbine output, wherein the function has a maximum value and the required turbine output is less than the maximum turbine output , Then one of the two possible effective turbine areas is chosen so that the backpressure of exhaust gas is at a minimum.

According to another aspect, there is provided an apparatus for operating an exhaust gas-driven turbocharger in an engine system having a combustion engine, the apparatus configured to execute the method described above.

According to another aspect, there is provided a turbine having a combustion engine, a turbine having a supercharger actuator for variable adjustment of the turbine structure, and a supercharger having a bypass line having bypass cross-sectional areas bypassing the turbine and an engine having the above- System is provided.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

1 shows a schematic diagram of an engine system having a turbocharger.
Figure 2 shows a detail of a portion of a turbine and a turbocharger having an adjustable bypass cross-sectional area and a bypass line surrounding the turbine.
3 shows a feedback control system for determining operating variables for the supercharger actuator in accordance with the boost pressure feedback control.
Figure 4 shows a flow chart for illustration of a method for operation of the supercharger for the engine system of Figure 1;
Figures 5A and 5B show graphs of a plot of a function of turbine power versus effective turbine cross sectional area.

1, an engine system 1 having a combustion engine 2 is shown. The combustion engine 2 is configured as a four-cylinder engine, and in particular may be a diesel engine or a gasoline engine. The combustion engine 2 includes a cylinder 3 (for example, four), through which air is supplied to the cylinder. A throttle valve 5 may be disposed in the air supply section 4. The combustion exhaust gas is discharged from the combustion engine 2 through the exhaust gas discharge section 6.

An exhaust gas driven supercharger 7 is provided in the engine system 1 in which a turbine 71 is disposed in the exhaust gas discharge section 6 and a compressor 72 is disposed in the air supply section 4 . The turbine 71 is mechanically coupled to the compressor 72 via, for example, a shaft 73. The turbine 71 of the turbocharger 7 includes a turbocharger actuator 74 which is capable of setting the efficiency of supercharging, that is, the fraction of the existing exhaust gas enthalpy which is converted into mechanical energy.

The turbocharger actuator 74 may be formed as a VTG actuator (Variable Turbine Geometry (VGT)). During operation, the mechanical output provided by the turbine 71 is determined from the pressure difference between the input side and the output side of the turbine 71 and the exhaust gas mass flow through the turbine 71. The pressure at the input side of the turbine 71 is referred to as the exhaust gas back pressure and, when a subsequent device for exhaust gas aftertreatment, such as, for example, a catalytic converter, is provided, Lt; / RTI > In the case of a multi-stage turbocharger, the pressure at the output side of the turbine 71 may be clearly above the ambient pressure. Depending on the position of the turbocharger actuator 74, an effective turbine cross-sectional area is formed which represents the flow resistance through the turbine 71 or the flow rate of the exhaust gas mass flow.

A bypass line 75 is provided bypassing the turbine 71, in which an adjustable bypass valve 76 is located. The position of the bypass valve 76 determines the effective bypass cross-sectional area that determines the flow resistance through the bypass line 75 or the flow rate of the exhaust gas mass flow.

The compressor 72 sucks air from the surroundings, notably through an air filter (not shown) or, furthermore, through a compressor connected upstream in the case of a multi-stage turbocharger, In the supercharging air section 41, in particular between the compressor 72 and the throttle valve 5.

An exhaust gas recirculation portion 8 for connecting the exhaust gas discharge section 6 with the intake pipe section 42 may be provided. An exhaust gas recirculation valve (81) may be provided in the exhaust gas recirculation portion (8).

The operation of the combustion engine 2 is controlled using the control device 10 which is based on the input value of the load demand V and on the basis of the state variables such as, The throttle valve 5, the exhaust gas recirculation valve 81, the injection valve (not shown) for injecting a predetermined amount of fuel and the supercharger actuator 74 are driven in an appropriate manner, in particular according to the boost pressure feedback control do.

If the backpressure of the exhaust gas at the input side of the turbine 71 is determined, the turbocharger actuator 74 can be actuated in response to an increased output demand or load demand, i. E. Is driven such that a greater portion of the exhaust gas enthalpy provided in the turbine 71 is converted to a mechanical output. The corresponding position of the turbocharger actuator 74, in principle, first increases the pressure difference to the turbine 71 by implementing an increase in the exhaust gas backpressure. This is accomplished through tilting or displacement of the turbine blades in the turbocharger actuator 74 configured in the form of a variable turbine structure.

)의 다른 상태 변수, 바이패스 라인(75)을 통한 바이패스 질량 유동(

), 터빈(71)을 통한 터빈 질량 유동(

), 터빈(71) 상류의 온도(T_Us), 터빈(71) 하류의 온도(T_Ds), 터빈(71) 상류의 압력(P_Us), 터빈(71) 하류의 압력(P_Ds) 및 유효 바이패스 단면적(A_Byp) 및 과급기 액추에이터(74)에 의한 터빈 구조의 설정을 통해 변경될 수 있는 유효 터빈 단면적(A_Trb)이 표시된다. Figure 2 shows a detail view of a portion of a turbocharger 7 and a supercharger 7 having a bypass line 75 in which a bypass valve 76 is disposed. The total exhaust gas mass flow (< RTI ID = 0.0 >

), A bypass mass flow through the bypass line 75 (

), Turbine mass flow through the turbine 71

The temperature T _us upstream of the turbine 71, the temperature T _Ds downstream of the turbine 71, the pressure P _Us upstream of the turbine 71, the pressure P _Ds downstream of the turbine 71, The effective turbine cross-sectional area A _Trb that can be changed through setting of the turbine structure by the effective bypass cross-sectional area (A _Byp ) and the turbocharger actuator 74 is displayed.

3 shows a feedback control system 80 having a model-based boost pressure feedback control as an example. The boost pressure feedback control section includes a feedback control device 81 to which a difference between the actual turbine cross-sectional area A _Trbist from the processing unit 83 and the target turbine cross-sectional area A _Trbsoll from the pilot control device 86 is supplied . This difference is determined in the differential member 82. The feedback control device 81 may be configured as a conventional PID-controller 81 and the manipulated variable S may be output as a pulse occupancy rate for the turbocharger actuator 74. The processing unit 83 includes information on the actual boost pressure P _LDist from the engine system 1, for example, from the boost pressure sensor or from the corresponding calculation model calculated in the controller 10 From which it determines the actual turbine output P _Trbist required for setting the actual boost pressure P _LDist in the output calculation block 84 in a known manner. From the turbine output (P _Trbist ) corresponding to the actual boost pressure (P _LDist ), the corresponding effective actual turbine cross-sectional area (A _Trbist ) is determined in the first turbine area calculation block (85).

Target boost pressure (P _LDsoll ) is formed from the present load demand. The target boost pressure P _LDsoll is provided to the pilot control unit 86 and determines the target turbine output P _Trbsoll in the locus block 87 in accordance with the calculation described below. The target turbine output P _Trbsoll is supplied to the second turbine area calculation block 88 which determines the effective target turbine cross-sectional area (A _Trbsoll ) correspondingly in accordance with the method described later. The information on the target turbine cross-sectional area (A _Trbsoll ) is supplied to the feedback control device 81 and the differential member 82.

The pilot control is based on the set bypass cross-sectional area (A _Byp ) and the required turbine output (P _Trb ). The bypass cross-sectional area (A _Byp ) is preset in accordance with the control point, in particular according to the operating point. The operating parameter S for the turbocharger actuator 74 is formed from the effective turbine cross-sectional area A _Trb corresponding to the required turbine output P _Trb .

Figure 4 shows a flow chart for illustration of a method for operation of a supercharger in an engine system.

The turbine of the turbocharger 7 for setting the required target boost pressure P _LDsoll and the requested target boost pressure P _LDsoll is set based on the required engine torque as the load demand V in step S1, The corresponding turbine output P _{Trb of} the turbine 71 is determined by the control device 10. The target turbine output (P _Trbsoll ) of the turbine (71) is formed from the desired target boost pressure (P _LDsoll ), for example, according to a predetermined function, such as an appropriate characteristic area.

Thereafter, in step S2, the effective target turbine cross-sectional area A _Trbsoll is determined according to a calculation method described below. The effective target turbine cross-sectional area (A _Trbsoll ) represents a pilot variable for the feedback controller.

In step S3, the corresponding actual turbine output P _Trbist of the turbine 71 of the turbocharger 7 is determined by the control device 10 based on the actual boost pressure P _LDist . The actual turbine output P _{Trbist of the} turbine 71 is formed from the actual boost pressure P _LDist in accordance with a predetermined function, for example, an appropriate characteristic area.

Thereafter, in step S4, the effective actual turbine cross-sectional area A _Trbist is determined according to the calculation method described below.

The difference between the actual turbine sectional area A _Trbist and the target turbine sectional area A _Trbsoll and the target turbine sectional area A _Trbsoll are supplied to the feedback control device 81, 71), and assigns it, for example, according to the characteristic area. This method is performed periodically to periodically determine the manipulated variable S so that a more immediate response to a change in the desired target turbine output (P _Trbsoll ) or a change in the bypass cross-sectional area (A _Byp ) have. A possible method for calculating the effective turbine area (A _Trb ) will now be described, at least partially in the bypass line 75, when the corresponding turbine output (P _Trb ) is predetermined.

The above-described method makes it possible to drive the turbocharger 71 using the operating parameter S, so that the boost pressure cut-off and the boost pressure over boost can be reliably suppressed when the bypass cross-sectional area A _Byp is changed . In particular, it can respond quickly to changes in the bypass cross-sectional area (A _Byp ) through model-based pilot control.

A method for determining the effective turbine area in the first and second turbine area calculation blocks 85, 88 is executed. The method is based on the following equation:

이고, here,

ego,

The throttle equation and turbine output (P _Trb ) (equation 4) for turbine 71 (equation 1) and bypass line 75 (equation 2). This simultaneous equation can be solved according to the effective turbine cross-sectional area (A _Trb ). The nonlinearity based on the exponentiation function ( Ψ ) and the exponent of the power equation ( R / c _p ) makes a direct solution of the simultaneous equations impossible. Thus, an approximate solution is used.

Equations (1) through (4)

이며,here,

Lt;

≪ / RTI >

이며, 표준화된 관류 특성 곡선은

이다. 방정식(5)에서 터빈 면적이 비종속 파라미터로서 고려될 경우, 압력비(Π)가 터빈 단면적(A _Trb )의 함수로서 표현된다.

, And the standardized perfusion characteristic curve

to be. When the turbine area is considered as a non-dependent parameter in equation (5), the pressure ratio [ pi ] is expressed as a function of the turbine cross-sectional area (A _Trb ).

The problem of computing these functions can be considered non-dependent. Therefore, by the equations (6 and 7), the turbine output P _Trb can be expressed as a function of the effective turbine cross-sectional area A _Trb .

)를 더 증가시키는데, 이는 바이패스 라인(75)을 통한 바이패스 질량 유동의 증가 또는 터빈(71)을 통한 터빈 질량 유동의 하강을 유도한다. 압력비(

)의 증가는 방정식(4)에 따라 터빈 출력(P_Trb)의 상승을 유도하는 반면, 터빈 질량 유동(

)의 하강은 터빈 출력(P_Trb)의 상승을 최대값의 초과 후에 과보상한다. This function has to be inverted so that when the turbine output P _Trb is pre-set, the required turbine area A _Trb can be determined for this. P _Trb (A _Trb ) is shown for turbine area (A _Trb ), for example in (a), for one set of external parameters in Figures 5a and 5b, A _Trb ). An important problem with inversion is that P _Trb (A _Trb ) contains the maximum value. That is, there are two possible positions of the effective turbine cross-sectional area A _Trb such that the same turbine output P _Trb is achieved. This is due to the fact that the turbine cross-sectional area is formed from the case where the turbine cross-sectional area is reduced past the output maximum value, otherwise the unchanged parameter (especially the bypassed cross-sectional area A _Byp )

Which leads to an increase in the bypass mass flow through the bypass line 75 or a descent of the turbine mass flow through the turbine 71. Pressure ratio

) _Leads to an increase in turbine output (P _Trb ) according to equation (4), while the increase in turbine mass flow

) Overshoots the rise of the turbine output (P _Trb ) after exceeding the maximum value.

It is desirable that the back pressure of the exhaust gas is minimized as much as possible, so that the loss in the combustion engine 2 is reduced. That is, a solution for which the turbine area (A _Trb ) takes a larger value can be selected from two possibilities.

For numerical inversion, it is necessary to recognize the position of the maximum value, since monotonicity is a prerequisite for inversion. The actual transformation is performed by a formula as a zero point problem, and a reverse algorithm is known from the literature for that solution. Examples thereof include a binary method or a Newton method or a method considering a function curve or a combination of a plurality of methods.

Determination of the maximum value of the turbine cross-sectional area (A _Trb ) is a separate problem. Obviously, the maximum value point of P _Trb (A _trb) according to the equation (8) to correspond totally to the equation (5 and 7) follows the curve of the function Π (A _Trb), to be in accordance with the value (R / c _p) . This dependency should be stored in the control device 10 in an appropriate manner.

In theory, the overall maximum value can be determined in the controller 10 in an appropriate manner, but this may increase computational complexity. Analysis of equation (5), the position of the maximum value only depends only one additional parameter in addition to the R / c _p. In other words, the position of the maximum value, for example, according to the characteristics in the regions, R / c _p, and

, The following values,

Lt; / RTI > The effective turbine area (A _Trb ) that derives the output maximum at a given external parameter can be calculated from this value. R / c in accordance with the dependence of _p In this case, if should be ignored due to their small effect, it is sufficient as a characteristic area having only the dependency of only a single X _Byp instead of characteristic regions. Characteristic curve, the maximum value of the output is the data input so that it can not be exceeded in the relevant range of values of R / c _p.

The calculation method calculates an effective turbine area A _Trb that provides the required output of the turbine 71 for the required turbine output P _Trb when the bypass line 75 is open.

For the required output above the maximum possible turbine output at the previously described current operating point, the method includes determining the turbine cross-sectional area A (A), which provides the maximum possible output for the turbine 71, _Trb ). Thereby, the turbine cross-sectional area A _Trb is restricted downward, so that the minimum area according to the operating point can not be lowered.

However, for example, to determine the feedback deviation of the boost pressure feedback from the modeled turbine cross-sectional area, an unlimited turbine cross-sectional area A _Trb may be calculated. This means that if, for example, a turbine output (P _Trb ) exceeding the maximum turbine output is required, then the minimum turbine cross-sectional area according to the pre-set operating point through the previously defined characteristic area is the maximum turbine output and the desired turbine output , The calculated unrestricted area can be achieved to be less than the minimum effective turbine area.

Claims (13)

A method for operating an exhaust gas driven supercharger (7) in an engine system (1) having a combustion engine (2), the turbocharger (7) comprising a supercharger actuator (74) for variable tuning of an efficient turbine structure And a bypass line (75) bypassing the turbine (71) and the turbine (71) and having an adjustable bypass cross-sectional area (A _Byp )
Providing a desired target turbine output (P _Trbsoll )
Current and the bypass cross-section step (S1, S2) corresponding to the target turbine determining an effective cross-sectional area (A _Trbsoll) in which the (A _Bypist), the desired target turbine output (P _Trbsoll),
, And driving (S5) the turbocharger actuator (74) in accordance with the determined effective target turbine cross-sectional area (A _Trbsoll ). 2. The method according to claim 1, wherein the required target turbine output (P _Trbsoll ) is _preset according to the load demand for the combustion engine (2) according to the operating state. 3. The supercharger operating method according to claim 1 or 2, wherein the turbocharger actuator (74) is controlled and driven by an operating variable (S) according to an effective target turbine cross-sectional area (A _Trbsoll ). 3. A turbocharger according to claim 1 or 2, wherein the turbocharger actuator (74) is driven by an operating parameter (S) derived from a valid target turbine cross-sectional area (A _Trbsoll ) . The method of claim 4 wherein the current and the actual turbine output determined from the load information, the current and the effective actual turbine cross-section (A _Trbist) corresponding to the actual turbine output (P _Trbist) determined by the by-pass cross-sectional area (A _Bypist), turbocharger actuator (74) is determined according to the determined effective target turbine cross-sectional area (A _Trbsoll ) and the determined effective actual turbine cross-sectional area (A _Trbist ). The method as claimed in claim 1 or 2, wherein, in the current bypass cross-sectional area (A _Bypist ), the determination of the effective turbine cross-sectional area (A _Trb ) corresponding to the turbine output (P _Trb ) comprises determining the pressure ratio through the turbine To operate the supercharger. The method of claim 6 wherein the effective turbine cross-section is the reverse of the function performed in the turbine output (P _Trb) for (A _Trb). Thus, the function is the determination of the effective turbine cross-section (A _Trbist) for a requested turbine output (P _Trbsoll) And for this reversal, the maximum value of the desired target turbine output (P _Trbsoll ) is determined using a predetermined dependency or numerically. The method of claim 6, wherein the target turbine output decision of the effective turbine cross-section (A _Trb) corresponding to the (P _Trbsoll) are subjected to a function of the effective turbine area (A _Trb) associated with the requested target turbine output (P _Trbsoll) based on One of the two possible effective turbine areas (A _Trb ) is selected so that the exhaust gas back pressure is minimized when the required turbine output (P _Trbsoll ) is less than the maximum turbine output, How it works. An apparatus for operating an exhaust gas driven supercharger (7) in an engine system (1) having a combustion engine (2), the apparatus being operable to carry out the method according to any one of claims 1 to 3. An engine system (1) comprising: a combustion engine (2); A supercharger 7 having a turbine 71 with a turbocharger actuator 74 and a bypass line 75 having bypass cross-sectional area A _{Bypist which} is variable and adjustable to bypass the turbine 71; An engine system (1) comprising an apparatus according to claim 9. A computer program which, when executed on a control device, is arranged to execute the method according to any one of claims 1 to 3 and is stored in a machine-readable storage medium. 12. A machine-readable storage medium having stored thereon a computer program according to claim 11. An electronic control apparatus comprising an electronic storage medium according to claim 12.

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