Method and control device for detecting, during the operation of a hybrid vehicle, whether combustion is taking place in an internal combustion engine of the hybrid vehicle

Abstract

A method to detect whether combustion is taking place in an internal combustion engine of a hybrid vehicle during operation of the hybrid vehicle, whereby a decoupler is provided between the internal combustion engine and an electric machine that serves to power the hybrid vehicle, comprising opening the decoupler between the internal combustion engine and the electric machine, receiving a speed signal when the decoupler is open, said signal indicating a rotational speed of the internal combustion engine when the decoupler is open, and determining, on the basis of the speed signal when the decoupler is open, whether combustion is taking place in the internal combustion engine. The present invention also relates to a control device to carry out the method according to the invention.

Claims

1. A method to detect whether combustion is taking place in an internal combustion engine of a hybrid vehicle during operation of the hybrid vehicle, whereby a decoupler is provided between the internal combustion engine and an electric machine that serves to power the hybrid vehicle, and whereby a speed sensor is provided between the internal combustion engine and the decoupler, comprising: determining, according to a passive diagnosis during which the decoupler is closed, whether there is an indication that combustion is absent in the internal combustion engine by analyzing, using the speed sensor, a rotational speed of the internal combustion engine as a function of a crankshaft angle, when, according to the passive diagnosis, it is determined that no combustion is taking place in the internal combustion engine: opening the decoupler between the internal combustion engine and the electric machine; stopping fuel injection and mass flow into the internal combustion engine after the decoupler has been opened, and restarting the internal combustion engine while the decoupler is still open; after the internal combustion engine has been restarted and while the decoupler is still open, receiving a speed signal from the speed sensor when the decoupler is open, said speed signal indicating a rotational speed of the internal combustion engine when the decoupler is open; and determining, on the basis of the speed signal when the decoupler is open, whether combustion is taking place in the internal combustion engine.

2. The method according to claim 1, whereby the determining as to whether there is the indication that combustion is absent in the internal combustion engine is further made on the basis of at least one of the following signals: when the decoupler is closed, on the basis of a lambda signal of a lambda sensor representing a lambda value of the lambda sensor of the hybrid vehicle when the decoupler is closed; on the basis of a torque signal that indicates the torque value of the electric machine when the decoupler is closed; and/or on the basis of the engine temperature.

3. The method according to claim 1, wherein the determination as to whether combustion is taking place in the internal combustion engine comprises: that, when the decoupler is open, the rotational speed of the internal combustion engine is compared to a prescribed limit rotational speed of the internal combustion engine; and that it is determined that no combustion is taking place in the internal combustion engine if the rotational speed of the internal combustion engine is lower than the prescribed limit rotational speed.

4. The method according to claim 3, whereby it is determined that no combustion is taking place in the internal combustion engine if the rotational speed of the internal combustion engine is lower than the prescribed limit rotational speed after a prescribed period of time after the decoupler was opened.

5. The method according to claim 1, whereby, if it has been determined that no combustion is taking place in the internal combustion engine, a driver information signal is generated which indicates that no combustion is taking place in the internal combustion engine.

6. The method according to claim 1, whereby, if it is determined that combustion is taking place in the internal combustion engine, the decoupler is closed.

7. A control device to detect whether combustion is taking place in an internal combustion engine of a hybrid vehicle during operation of the hybrid vehicle, whereby a decoupler is provided between the internal combustion engine and an electric machine that serves to power the hybrid vehicle, whereby a speed sensor is provided between the internal combustion engine and the decoupler, and whereby the control device is configured to carry out a method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described by way of examples, making reference to the accompanying drawings. The following is shown:

(2) FIG. 1 is an embodiment of a drive train of a hybrid vehicle, in a schematic view;

(3) FIG. 2 is an embodiment of a control device according to the invention, in a schematic view;

(4) FIG. 3 is a flow diagram of a first embodiment of a method according to the invention to detect whether combustion is taking place in an internal combustion engine; and

(5) FIG. 4 is a flow diagram of a second embodiment of a method according to the invention to detect whether combustion is taking place in an internal combustion engine.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows an embodiment of a drive train 1 of a hybrid vehicle. The drive train 1 of the hybrid vehicle comprises an internal combustion engine 10 having a crankshaft 11, an electric drive 12 and a decoupler 13 by means of which the electric drive 12 is connected to the crankshaft 11 of the internal combustion engine 10. The internal combustion engine 10 and the electric drive 12 are coupled via a transmission 14 to a drive axle 15 that is connected to wheels 16 of the hybrid vehicle. The transmission 14 is, for example, a dual-clutch transmission.

(7) The drive train 1 also comprises a speed sensor that has a transmitter wheel 17 with fifty-eight teeth 170 and a Hall sensor 18. The transmitter wheel 17 is attached to the crankshaft 11 between the internal combustion engine 10 and the decoupler 13. The Hall sensor 18 scans the transmitter wheel during one rotation of the crankshaft 11 and generates a high-resolution, oscillating speed signal. The speed signal of the Hall sensor 18 is conveyed via a data bus 19 to a control device 2.

(8) The control device 2 is configured to carry out a method 3, 4 which is described below with reference to FIGS. 3 and 4 and which serves to detect whether combustion is taking place in an internal combustion engine of a hybrid vehicle during operation of the hybrid vehicle.

(9) As shown in FIG. 2, the control device 2 has a signal input 20 that can be connected to the data bus 19 and that can receive the speed signal via the control device 2. The control device 2 also has a processor 21 that is connected to the signal input 20, a data storage unit 22 that is connected to the processor 21 and a signal output 23 that is connected to the processor 21. A program that contains instructions for the processor 21 so that the processor can be controlled by means of one of the methods 3, 4 is stored in the data storage unit 22. The processor 21 is a microprocessor which is configured to carry out the method 3, 4 that serves to detect whether combustion is taking place in an internal combustion engine of a hybrid vehicle during operation of the hybrid vehicle. The signal output 23 can be connected to a control motor or to an actuator (not shown here) of the decoupler 13 in order to transmit a control signal to open or close the decoupler, and it can be connected to a display in order to transmit a driver information signal and to show the driver that the internal combustion engine is defective since no combustion is taking place in the internal combustion engine.

(10) FIG. 3 shows a flow diagram of a first embodiment of a method 3 according to the invention to detect whether combustion is taking place in an internal combustion engine.

(11) In 30, a passive diagnosis is carried out as to whether combustion is taking place in the internal combustion engine. In this process, for example, when the decoupler is closed, the speed sensor receives a high-resolution speed signal that indicates the rotational speed of the internal combustion engine as a function of a crankshaft angle, and subsequently determines whether a crankshaft angle at which a cylinder of the internal combustion engine is at its upper dead center coincides with a crankshaft angle at which the high-resolution speed signal exhibits a minimum value. If the crankshaft angles differ, then the passive diagnosis indicates that combustion is probably taking place in the internal combustion engine. However, if the crankshaft angles coincide, then the passive diagnosis indicates that it is probable that no combustion is taking place in the internal combustion engine.

(12) If it is detected in 30 that combustion is taking place in the internal combustion engine, then the passive diagnosis is repeated in 30.

(13) If it is detected in 30 that no combustion is taking place in the internal combustion engine, then the decoupler between the internal combustion engine and the electric drive is opened in 31. For this purpose, a control signal is transmitted to the control motor or to the actuator of the decoupler, said signal causing the control motor or the actuator to open the decoupler.

(14) In 32, when the decoupler is open, the speed sensor receives a speed signal that indicates the rotational speed of the internal combustion engine when the decoupler is open.

(15) In 33, it is determined whether combustion is taking place in the internal combustion engine. For this purpose, after the decoupler has been opened, it is detected whether the rotational speed of the internal combustion engine after 3 seconds has dropped to approximately the idling speed of the internal combustion engine or to approximately 0 rpm. If the rotational speed has dropped only to the idling speed, it is determined that combustion is taking place in the internal combustion engine. If, in contrast, the rotational speed has dropped to about 0 rpm, it is determined that no combustion is taking place in the internal combustion engine.

(16) If it is determined in 33 that combustion is taking place in the internal combustion engine, then the decoupler is closed in 34. For this purpose, before the decoupler is closed, the internal combustion engine is synchronized to the transmission speed and, as soon as the rotational speed of the internal combustion engine approximately matches the transmission speed, a control signal is transmitted to the control motor or to the actuator of the decoupler, said signal causing the control motor or the actuator to close the decoupler. After the decoupler has been closed, the hybrid vehicle is once again operated in the hybrid mode of operation.

(17) If it is determined in 33 that no combustion is taking place in the internal combustion engine, then back-up measures are initiated in 35. The back-up measures comprise a switch-over to a purely electric mode of operation of the hybrid vehicle with a power limitation in order to extend the range that can be driven in the electric mode of operation and to display driver information indicating that the driver should go to a repair garage. In order to display the driver information, an appropriate driver information signal is transmitted to a display device.

(18) FIG. 4 shows another embodiment of a method 4 to detect whether combustion is taking place in the internal combustion engine during operation of the hybrid vehicle.

(19) In 30, as described in conjunction with FIG. 3, a passive diagnosis is carried out as to whether combustion is taking place in the internal combustion engine. If it is detected in 30 that combustion is taking place in the internal combustion engine, then the passive diagnosis is repeated in 30.

(20) If it is detected in 30 that no combustion is taking place in the internal combustion engine, then in 31, as described in conjunction with FIG. 3, the decoupler between the internal combustion engine and the electric drive is opened.

(21) In 36, the internal combustion engine is stopped. For this purpose, the internal combustion engine is switched off in that the fuel injection as well as the mass flow through the internal combustion engine are interrupted.

(22) In 37, the internal combustion engine is restarted. In this context, the internal combustion engine is started in the idling mode of operation when the decoupler is open.

(23) In 32, as described in conjunction with FIG. 3, a speed signal is received when the decoupler is open.

(24) In 38, it is determined whether no combustion is taking place in the internal combustion engine. For this purpose, after the restart of the internal combustion engine, it is determined whether the rotational speed of the internal combustion engine has risen to approximately the idling speed of the internal combustion engine. If the rotational speed has not risen to the idling speed, it is determined that no combustion is taking place in the internal combustion engine. Otherwise, if the rotational speed has risen to the idling speed, it is determined that combustion is taking place in the internal combustion engine.

(25) If it is determined in 38 that combustion is taking place in the internal combustion engine, then in 34, the decoupler is closed, as described in conjunction with FIG. 3.

(26) If it is determined in 38 that no combustion is taking place in the internal combustion engine, then in 35, back-up measures are initiated, as described in conjunction with FIG. 3.

LIST OF REFERENCE NUMERALS

(27) 1 drive train 10 internal combustion engine 11 crankshaft 12 electric drive 13 decoupler 14 transmission with drive clutch 15 drive axle 16 wheel 17 transmitter wheel 170 teeth of the transmitter wheel 18 Hall sensor 19 data bus 2 control device 20 signal input 21 processor 22 data storage unit 23 signal output 3, 4 method to detect whether combustion is taking place in the internal combustion engine 30 conducting a passive diagnosis as to whether combustion is taking place in the internal combustion engine 31 opening the decoupler 32 receiving a speed signal when the decoupler is open 33 determining whether combustion is taking place in the internal combustion engine 34 closing the decoupler 35 initiating back-up measures 36 stopping the internal combustion engine 37 restarting the internal combustion engine 38 determining whether combustion is taking place in the internal combustion engine