METHOD AND DEVICE FOR CONTROLLING A TURBOCHARGER

Abstract

A method for establishing a permitted maximum differential pressure (p.sub.max) of an air filter (3) arranged in an intake tract (2) of an internal combustion engine (1), wherein a control reserve of the internal combustion engine (1) is determined and the maximum permissible differential pressure (p.sub.max) of the air filter (3) is established as a function of the determined control reserve.

Claims

1. A method for establishing a permitted maximum differential pressure (p.sub.max) of an air filter (3) arranged in an intake tract (2) of an internal combustion engine (1), wherein a control reserve of the internal combustion engine (1) is determined and the maximum permissible differential pressure (p.sub.max) of the air filter (3) is established as a function of the determined control reserve.

2. A method according to claim 1, wherein a control range of a control variable for the flow of a fuel-air mixture or an exhaust gas is used as a control reserve, wherein preferably the following variables are used in isolation or any combination: the position of a bypass valve (4) of a turbocharger bypass (5) of the internal combustion engine (1) the position of a throttle valve (6) of the internal combustion engine (1) the position of a wastegate (7) an adjustable geometry of a turbocharger (8)

3. A method according to claim 1 or 2, wherein as control reserve the following can be used isolated or in combination: a control range of a control element for the specific energy density of the fuel-air mixture, preferably a lambda value a control range of a control element for the ignition time for the spark ignition of a fuel-air mixture in the combustion chambers of the internal combustion engine a control range of a control element for the volumetric efficiency, preferably adjustment of a variable valve train a control range of a control element for an EGR rate

4. A method according to at least one of the preceding claims, wherein a load state of the air filter (3) is being determined.

5. A method according to at least one of the preceding claims, wherein: a standard air flow is calculated from the operating variables of the internal combustion engine the actual present air flow is calculated taking into account the ambient pressure and the charge-air temperature from the standard air flow a comparison of a measured differential pressure (p) via the air filter with the maximum permitted differential pressure (p.sub.max) for the actual present air flow takes place

6. A method according to claim 5, wherein the measurement of the actually present differential pressure (p) and of the operating variables of the internal combustion engine (1) for the calculation of the standard air flow and the measurement of the ambient pressure and the charge-air temperature can be done continuously or cyclically.

7. A method according to at least one of the preceding claims, wherein based on the calculated actual present air flow and a maximum permitted differential pressure (p.sub.max) adjusted via the actual present air flow, the load condition and/or the remaining operating time of the air filter (3), particularly in a partial-load operation, of the internal combustion engine is estimated.

8. A method according to at least one of the preceding claims, wherein the degradation of the air filter (3) and the internal combustion engine (1) are monitored and it gets calculated which maximum permitted differential pressure (p.sub.max) may be authorized and/or extrapolated into the future and estimated, when the air filter (3) must be replaced.

9. Internal combustion engine (1) comprising at least one air filter (3) arranged in an intake tract (2) of an internal combustion engine (1) a control device (9), in which a maximum permitted differential pressure (p.sub.max) for the air filter can be stored characterized in that the control device (9) is designed to determine a specific control reserve of the internal combustion engine (1) and the maximum permitted differential pressure (p.sub.max) of the air filter (3) from the measurement values of the at least one sensor and the operating data of the internal combustion engine (1) as a function of the determined control reserve.

10. An internal combustion engine according to the preceding claim, wherein a control range of a control variable for the flow of a fuel-air mixture or an exhaust gas is given as a control reserve, preferably in isolation or any combination: the position of a bypass valve (4) of a turbocharger bypass (5) of the internal combustion engine (1) the position of a throttle valve (6) of the internal combustion engine (1) the position of a wastegate (7) an adjustable geometry of a turbocharger (8)

11. An internal combustion engine according to at least one of the preceding claims, wherein the control reserve is given by: a control range of a control element for the specific energy density of the fuel-air mixture, preferably a lambda value a control range of a control element for the ignition time for the spark ignition of a fuel-air mixture in the combustion chambers of the internal combustion engine a control range of a control element for the volumetric efficiency, preferably adjustment of a variable valve train a control range of a control element for an EGR rate

12. An internal combustion engine according to at least one of the preceding claims, wherein the control device (9) is designed to determine the load state of the air filter (3).

13. An internal combustion engine according to at least one of the preceding claims, wherein the control device (9) is designed to: calculate a standard air flow from the operating variables of the internal combustion engine (1) calculate an actual present air flow taking into account the ambient pressure and the charge air temperature from the standard air flow carry out a comparison of a measured differential pressure (p) via the air filter (3) with the maximum permitted differential pressure (p.sub.max) for the actual present air flow

14. An internal combustion engine according to at least one of the preceding claims, wherein the control device (9) is designed to carry out the measurement of the actual present differential pressure (p) and of the operating variables of the internal combustion engine (1) for the calculation of the standard air flow and the measurement of the ambient pressure and the charge-air temperature continuously or cyclically.

Description

[0026] Exemplary embodiments of the invention will be explained with reference to the figures. The figures show:

[0027] FIG. 1 schematically an internal combustion engine according to the invention

[0028] FIG. 2 the differential pressure applied via the air filter over the operating hours of an internal combustion engine and

[0029] FIG. 3 the differential pressure applied via the air filter over the volume flow of the charge air.

[0030] FIG. 1 shows schematically an internal combustion engine 1 according to the invention with an intake tract 2 for charge air which can be supplied to the combustion chambers (not shown) of the internal combustion engine 1 and an air filter 3 arranged in the intake tract 2. The internal combustion engine 1 comprises a throttle valve 6, a wastegate 7, sensors 10 for the measurement of various operating variables and a control device 9 for the control of various control elements. A turbocharger 8 is provided, which can be flowed around a turbocharger bypass 5, depending on the position of a bypass valve 4.

[0031] FIG. 2 shows the increase of the differential pressure p over the number of operating hours for a typical internal combustion engine (for two different operating conditions of the internal combustion engine 1) starting from an initial differential pressure of p0. Drawn horizontally with dotted lines are two different values of the maximum permitted differential pressure p.sub.max. When the differential pressure p reaches the maximum permitted differential pressure p.sub.max, the air filter 3 must be replaced. The higher the maximum permitted differential pressure p.sub.max, the later this is the case. In the example shown, the two plotted values for the maximum permitted differential pressure p.sub.max differ by a control reserve of the internal combustion engine 1. By including this control reserve in the calculation of the maximum permitted differential pressure p.sub.max, an extension of the operating time of the air filter from time t1 to the time t1 can take place.

[0032] FIG. 3 shows a diagram with different operating points p1, p2, p2 of the air filter, wherein the differential pressure p is applied against the actually present volume flow V. Delineated is the maximum permitted differential pressure p.sub.ma x(upper solid straight line) in dependence of the actual present volume flow V, and a minimum permitted differential pressure (lower solid straight line), also in dependence of the volume flow V.

[0033] If the maximum permitted differential pressure p.sub.max is exceeded, the air filter must be changed. This also applies when the minimum permitted differential pressure drops below, since generally there is a defective air filter then.

[0034] Here follows the description of a typical aging process of an air filter based on the diagram in FIG. 3. At the first measurement of the differential pressure p and the first volume flow V at a first time, a first differential pressure p1 is measured at volume flow V1. With unchanged operating conditions, in particular an unchanged volume flow, a second differential pressure p2 is measured at a later time, which is already closer to the maximum permitted differential pressure p.sub.max(with or without utilization of the control reserve). It can now be estimated how much time remains until the maximum permitted differential pressure p.sub.maxis reached (for example, by linear extrapolation).

[0035] If the operating conditions since the first measurement have changed (which here is noticeable in an increased volume flow V2), then the second measured differential pressure p2 will have a different distance to the maximum permitted differential pressure p.sub.max. Again, it can now be estimated how much time remains until the maximum permitted differential pressure p.sub.max is reached (for example, by linear extrapolation) even though the operating conditions have changed.

[0036] Based on the calculated actual present air flow and a maximum permitted differential pressure (p.sub.max) adjusted via the actual present air flow, the load condition and/or the remaining operating time of the air filter (3), particularly in a partial-load operation, of the internal combustion engine can be estimated.