Regulating Device With an Electronic Control Unit for Regulating Boost Pressure in a Supercharged Internal Combustion Engine

Abstract

A regulating device comprising an electronic control unit for regulating boost pressure in a supercharged internal combustion engine with two-stage supercharging, i.e. with a first low-pressure stage (ND) and a second high-pressure stage (HD). The high-pressure stage (HD) has a rigid high-pressure turbine and a controllable regulating flap (RK). The low-pressure stage (ND) has a variable adjustable turbine geometry (VTG). The electronic control unit contains a regulating module that is designed, in particular via an appropriately programmed computer program product, for basic adjuster regulation in such a way that the boost pressure regulation is carried out solely by way of the adjustable turbine geometry (VTG) of the low-pressure stage (ND), wherein the regulating flap (RK) of the high-pressure stage (HD) is controlled in the fully closed state.

Claims

1.-4. (canceled)

5. A regulating device comprising: an electronic control unit for regulating boost pressure in a turbocharged internal combustion engine having at least two-stage turbocharging, having a low-pressure stage and a high-pressure stage, wherein the high-pressure stage has a rigid high-pressure turbine and a controllable bypass regulating flap, and wherein the low-pressure stage has a turbine having variably adjustable turbine geometry, and a regulating module in the electronic control unit, configured for a fundamental one-actuator regulation in the form that boost pressure regulation is performed solely by way of the adjustable turbine geometry of the low-pressure stage to achieve a specified boost pressure target value, wherein the regulating flap of the high-pressure stage is controlled in the completely closed state.

6. The regulating device according to claim 5, wherein the one-actuator regulation is fundamentally activatable when a lower exhaust gas counter pressure is thus achieved than by a two-actuator regulation.

7. The regulating device according to any claim 5, wherein the regulating flap is used as an exception for a smaller defined high load part of the possible operating points as a second actuator for two-actuator regulation, wherein this smaller high load part of the possible operating points is definable in particular by exceeding a specified full load speed limiting value and/or a specified boost pressure limiting value and/or a specified mass flow limiting value related to component protection.

8. A motor vehicle having a regulating device according to claim 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure is explained in more detail by way of an exemplary embodiment and on the basis of a drawing.

[0018] FIG. 1 shows a detail of a double supercharged internal combustion engine having essential components according to the disclosure;

[0019] FIG. 2 shows an enlargement of the control unit having a regulating module according to the disclosure;

[0020] FIG. 3 shows the effect of the disclosure in comparison to the prior art for a specific engine speed; and,

[0021] FIG. 4 shows characteristic maps according to the disclosure for the duty cycles of the affected actuators in comparison to the characteristic maps according to the prior art.

DETAILED DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 shows a detail of essential components of a double supercharged diesel engine D as an example of an internal combustion engine having a rigid turbocharger 1 (without VTG actuator) and having an exhaust gas bypass regulating flap RK in a high-pressure path HD and having a controllable turbocharger 3 in a low-pressure path ND. The turbocharger 3 in the low-pressure path ND has a variably adjustable turbine geometry (ND-VTG) as the actuator for controlling the compression. The regulating flap RK has a variably adjustable valve 2 (RK actuator). Furthermore, the internal combustion engine D has a pressure sensor on the input side for detecting the actual boost pressure p1_ist and optionally a pressure sensor for detecting the precompression pressure p2, wherein the precompression pressure p2 does not have to (still) be detected for the disclosure.

[0023] The internal combustion engine D and in particular also the boost pressure p1 is regulated by an electronic control unit 4. For example, the current boost pressure p1_ist is the input signal of the electronic control unit 4. The boost pressure target value p1_soll is also specified in the electronic control unit 4 as a reference variable of a regulating module 5. Those skilled in the art will appreciate that the electronic control unit 4 may comprise a suitable engine control unit (ECU) and/or engine control module (ECM) having a processing unit (e.g., a microcontroller or a microprocessor) and an associated memory (e.g., ROM, RAM, PROM, EEPROM, etc.) for storage of software, programs, and/or logic to be executed by the processing unit. The regulating module 5 may comprise software, programs, and/or logic to be executed by the processing unit.

[0024] The control unit 4 is shown in somewhat more detail in FIG. 2. The output signals of the control unit 4 are the actuation signals for the ND-VTG actuator 3 (VTG) and the HD-RK actuator 2 (RK).

[0025] The design (in particular programming) of the regulating module 5 and its effect will be explained in more detail in conjunction with FIG. 3.

[0026] The regulating module 5 is designed for a fundamental one-actuator regulation in the form that the boost pressure regulation is performed solely by way of the adjustable turbine geometry ND-VTG of the turbine 3. The regulating flap RK is controlled via the valve 2 in the high-pressure stage HD in the completely closed state, for example, via a duty cycle of 100%.

[0027] This one-actuator regulation (regulator transfer) is fundamentally activated when a lower exhaust gas counter pressure p3 is thus achieved (see also FIG. 1 and reduction by p3 in FIG. 3) than by the two-actuator regulation.

[0028] FIG. 4 shows the characteristic maps according to the disclosure for the duty cycles of the affected actuators 2 and 3.

[0029] Notwithstanding the fundamental one-actuator regulation according to the disclosure, the regulating flap RK is used as an exception via the duty cycle (see white numbers in the characteristic maps) at the valve 2 for a smaller defined high load part of the possible operating points as a second actuator (duty cycle<100%) for two-actuator regulation. This smaller high load part of the possible operating points is preferably defined here in particular by exceeding a specified full load speed limiting value n.sub.M_lim and/or a specified boost pressure limiting value and/or a mass flow limiting value m.sub.lim related to component protection. The limiting values can be empirically determined and stored in the control unit 4.