Method for control and/or regulation of a hybrid powertrain of a motor vehicle with an exhaust gas recirculation system

Abstract

A method for control and/or regulation of a hybrid powertrain of a motor vehicle, wherein exhaust gas is taken from an exhaust system and delivered to a fresh air supply of an internal combustion engine, wherein the residual recirculated exhaust gas is purged from the fresh air supply in the event of a negative load jump. After the negative load jump, the internal combustion engine continues to run with a smaller load and simultaneously the torque supplied by the internal combustion engine is recuperated by means of the electric machine, wherein no positive torque in total is applied to the output of the powertrain.

Claims

1. A method for control and/or regulation of a hybrid powertrain of a motor vehicle, the method comprising: taking exhaust gas from an exhaust system; delivering the exhaust gas to a fresh air supply of an internal combustion engine so as to provide recirculated exhaust gas to the internal combustion engine; and purging the residual recirculated exhaust gas from the fresh air supply in the event of a negative load jump; wherein, in order to purge the residual recirculated exhaust gas, the internal combustion engine continues to run with a smaller load after the negative load jump and substantially simultaneously the torque supplied by the internal combustion engine is recuperated via an electric machine so that no positive torque in total is applied to an output of the hybrid powertrain, and wherein the negative load jump occurs in the hybrid powertrain having a manual transmission when a driver disengages a clutch to change gears, and wherein the electric machine regulates a speed of the internal combustion engine.

2. The method according to claim 1, wherein the internal combustion engine continues to be operated at an efficiency-optimized load point after the negative load jump.

3. The method according to claim 1, wherein the torque supplied by the internal combustion engine is overcompensated for by the electric machine in order to represent to a driver a braking frictional torque of an internal combustion engine coasting in gear.

4. The method according to claim 1, wherein the electric machine is arranged on an engine side of the clutch, wherein the clutch is opened after the negative load jump, and wherein the electric machine recuperates mechanical energy within a framework of speed regulation of the internal combustion engine.

5. The method according to claim 1, wherein the electric machine is arranged on a transmission side of the clutch, wherein the clutch is closed in the case of the negative load jump, and a negative torque is applied to the hybrid powertrain via the electric machine.

6. A method for control and/or regulation of a hybrid powertrain of a motor vehicle, the method comprising: taking exhaust gas from an exhaust system; delivering the exhaust gas to a fresh air supply of an internal combustion engine so as to provide recirculated exhaust gas to the internal combustion engine; and purging the residual recirculated exhaust gas from the fresh air supply in the event of a negative load jump; wherein, in order to purge the residual recirculated exhaust gas, the internal combustion engine continues to run with a smaller load after the negative load jump and substantially simultaneously the torque supplied by the internal combustion engine is recuperated via an electric machine so that no positive torque in total is applied to an output of the hybrid powertrain, and wherein the negative load jump occurs in the hybrid powertrain having an automatic transmission, wherein the negative load jump occurs to protect a clutch in a case of shifting operations during acceleration.

Description

SUMMARY OF THE INVENTION

(1) It is therefore an object of the present invention to improve the generic method.

(2) According to an exemplary embodiment of the invention, the method is continued after the occurrence of a negative load jump by the means that, after the negative load jump, the internal combustion engine continues to run with a smaller load and simultaneously the torque supplied by the internal combustion engine is recuperated by means of the electric machine, wherein no positive torque in total is applied to the output of the powertrain. The internal combustion engine continues to run with a smaller load, which is required in order to convey the residual recirculated exhaust gases (EGR constituents) out of the intake system, wherein the torque supplied by the internal combustion engine is simultaneously recuperated by means of the electric machine. As a result, there is likewise no positive torque in total applied to the output of the powertrain. The output of the powertrain is composed of the driven wheels. It is possible to flush out the EGR constituents in this way without applying a positive torque to the driven wheels.

(3) Furthermore, it is possible to additionally continue to operate the internal combustion engine at an efficiency-optimized load point and to utilize the electrical energy that is then additionally generated for subsequent acceleration or for electric range extension.

(4) Furthermore, the possibility exists that the torque supplied by the internal combustion engine is overcompensated for by the electric machine in order to represent a braking frictional torque of an internal combustion engine coasting in gear that the driver expects in principle after releasing the accelerator. In total, this targeted control of the internal combustion engine and of the electric machine can lead to the problem of the EGR constituents that must be flushed being solved on the one hand, and on the other hand can achieve the result that the mechanical energy liberated in this process is temporarily stored in the form of electrical energy.

(5) There are multiple possibilities for incorporating the electric machine into the powertrain. The electric machine can be arranged on the engine side of a clutch, wherein the clutch is opened after the negative load jump, wherein the electric machine recuperates the mechanical energy within the framework of speed regulation of the internal combustion engine.

(6) A possibility for allowing the internal combustion engine to continue to run without delivering torque to the powertrain is the opening of a clutch between the internal combustion engine and a transmission, wherein in this case the electric machine recuperates the mechanical energy within the framework of speed regulation of the engine. In this embodiment, the electric machine is arranged on the engine side from the viewpoint of the clutch. In this design, no braking action on the powertrain by the electric machine is possible at all.

(7) Furthermore, the electric machine can be arranged on a transmission side of the clutch, wherein the clutch is closed in the case of the negative load jump, and a negative torque is applied to the powertrain by means of the electric machine. This variant with closed clutch is preferred on account of the possibility of additionally applying negative torque to the powertrain.

(8) This control strategy of the internal combustion engine and electric machine can be utilized for additional dynamic processes. One possibility here is a gear change. The negative load jump can occur in a hybrid powertrain with a manual transmission after the driver disengages the clutch to change gears, wherein the electric machine regulates the speed of the internal combustion engine. In the case of manual transmissions, the abovementioned negative load jump occurs when the driver eases up on the accelerator and disengages the clutch to change gears. In this case the speed of the internal combustion engine can be regulated by means of the electric machine in the event that it is not to be shut off immediately for one of the abovementioned reasons.

(9) Furthermore, the negative load jump can occur in a hybrid powertrain with an automatic transmission, wherein the negative load jump occurs to protect the clutch, in particular in the case of shifting operations during acceleration. In the case of automatic transmissions, the torque of the internal combustion engine is briefly reduced to protect the clutch, in particular in the case of shifting operations during acceleration. This likewise represents a negative load jump. In gasoline engines this occurs in particular by means of injection blank-out, closing of the throttle, or an ignition-advance reduction. Injection blank-out is equivalent to the above-described shutoff of the engine with the associated potential problems, for which reason the proposed strategy should be used if necessary. In the case of an ignition-advance reduction, the efficiency of combustion is intentionally degraded. In some circumstances, it may be energetically more favorable to burn with an efficiency-optimized ignition timing and to electrically recuperate the excess energy. Since the internal combustion engine would also be under load during the shifting operation in this case, the torque would also be available immediately after the end of the shifting operation, which would not have been the case in a shifting operation with a closed throttle, for example.

(10) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.