Control device and method for controlling the operation of an internal combustion engine and of an electrical machine in a hybrid vehicle

Abstract

A control device for controlling the operation of an internal combustion engine and of an electrical machine in a hybrid drive assembly, which permits a mechanical coupling of the engine and the machine in a drive train. An engine control part controls the internal combustion engine and an electrical machine control part controls the electrical machine. A monitoring part monitors proper operation of the control parts and, in the event of a malfunction, takes over a control function within a reaction time span. An engine false-start prevention part detects a transition of the internal combustion engine from stopped to running and, in the event of such a transition, checks if a proper start of the internal combustion engine was requested within a predefined past time span in order to prevent a fuel supply release and/or an ignition release if such a start was not requested.

Claims

1. A control device for controlling an operation of an internal combustion engine and of an electric machine in a hybrid drive arrangement of a vehicle, wherein the hybrid drive arrangement provides or permits a mechanical coupling of the engine and the electric machine in a drivetrain, the control device comprising: an engine control part for controlling the internal combustion engine, the engine control part being configured to control a fuel feed enablement and, optionally, an ignition enablement of the internal combustion engine; an electric machine control part for controlling the electric machine, the electric machine control part being configured to control an energization of the electric machine; a monitoring part configured to monitor a proper operation of said engine control part and of said electric machine control part and, when a malfunction is detected, to take over at least one control function of said engine control part and/or of said electric machine control part within a given reaction period; an engine false start prevention part configured to identify a transition from a stationary state to a running state of the internal combustion engine and, upon a transition being identified, to check whether a proper start of the internal combustion engine has been demanded within a predetermined period in the past in order, if the proper start has not been demanded, to prevent the fuel feed enablement and/or the ignition enablement for a predetermined engine interruption duration, wherein the engine interruption duration is at least as long as the given reaction period and lies in a range from 1.2 times to 20 times the given reaction period.

2. The control device according to claim 1, wherein the given reaction period lies in a range from 10 ms to 600 ms and the engine interruption duration is at least 0.5 seconds and no more than 5.0 seconds.

3. The control device according to claim 1, wherein said engine false start prevention part is configured to identify the transition from the stationary state to the running state of the internal combustion engine on a basis of an evaluation of a stored and continuously updated state value relating to a rotational speed of the internal combustion engine.

4. The control device according to claim 1, wherein said engine false start prevention part is configured to check whether a proper start of the internal combustion engine has been demanded within a predetermined period in the past by way of a read-out from a memory in which demands for a proper start of the internal combustion engine are temporarily stored for at least the predetermined period.

5. The control device according to claim 1, wherein the internal combustion engine is a fuel injected engine, and said engine false start prevention part is configured to prevent an injection enablement during the engine interruption duration.

6. The control device according to claim 1, wherein said engine false start prevention part is configured, if an ignition is applied in the internal combustion engine, to prevent an ignition enablement during the engine interruption duration.

7. The control device according to claim 1, wherein the engine interruption duration is at least 0.5 seconds and no more than 5.0 seconds.

8. The control device according to claim 7, wherein the engine interruption duration is at least 1 second and no more than 3 seconds.

9. The control device according to claim 3, wherein said engine false start prevention part is configured to read out the state value relating to the rotational speed of the internal combustion engine from a warm-reset-proof memory area of said control device.

10. A method for controlling an operation of an internal combustion engine and of an electric machine in a hybrid drive arrangement of a vehicle, wherein the hybrid drive arrangement provides or permits a mechanical coupling of the engine and the electric machine in a drivetrain, the method comprising: controlling the internal combustion engine by controlling a controlling a fuel feed enablement and, optionally, an ignition enablement of the internal combustion engine; controlling the electric machine by controlling an energization of the electric machine; monitoring correct control of the internal combustion engine and correct control of the electric machine and, when a malfunction is detected, taking over at least one control function of the control of the internal combustion engine and/or of the control of the electric machine within a given reaction period; identifying a transition from a stationary state to a running state of the internal combustion engine; when the transition is identified, checking whether a proper start of the internal combustion engine has been demanded within a predetermined period in the past; and if the proper start has not been demanded, preventing the fuel feed enablement and/or the ignition enablement for a predetermined engine interruption duration which is at least as long as the given reaction period and lies in a range from 1.2 times to 20 times the given reaction period.

11. The method according to claim 10, which comprises identifying the transition from the stationary state to the running state of the internal combustion engine by evaluating a stored and continuously updated state value relating to a rotational speed of the internal combustion engine, and reading out the state value relating to the rotational speed of the internal combustion engine from a warm-reset-proof memory area of a control device that is used for carrying out the method.

12. A non-transitory computer program product comprising program code which, when executed on a data processing device, carries out the method according to claim 10.

13. The method according to claim 10, wherein the given period lies in a range from 10 ms to 600 ms and the engine interruption duration is at least 0.5 seconds and no more than 5.0 seconds.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows a hybrid drivetrain of a vehicle according to an exemplary embodiment, and

(2) FIG. 2 shows a more detailed illustration of a control device used in the hybrid drive arrangement of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

(3) FIG. 1 shows a hybrid drive arrangement 1 of a vehicle, which in the illustrated example is equipped with two front wheels W1, W2 and two rear wheels W3, W4, wherein the hybrid drive arrangement 1 has an internal combustion engine 20 and an electric machine 30, which in this example are arranged, so as to be permanently coupled by means of a rotary shaft 2, in a drivetrain which leads to the front wheels W1, W2 of the vehicle. As illustrated, the drivetrain also comprises a clutch 3, a transmission (for example manual transmission) 4, and a differential transmission 5.

(4) In the example, the internal combustion engine 20 is an Otto-cycle engine which is operable with gasoline as fuel and which has fuel injection.

(5) Here, the electric machine 30 is a three-phase machine which can be supplied with electrical current from a battery 34 (for example lithium-ion storage battery) by means of a current converter device 32.

(6) The current converter device 32 has a bidirectional DC/AC converter 36, by means of which energization of the electric machine 30 is performed, be it in a drive mode for generating a drive torque in the drivetrain or in a generator mode for recuperating mechanical energy from the drivetrain (for example during the braking of the vehicle).

(7) In the illustrated example, the current converter device 32 furthermore has a bidirectional DC/DC converter 38, by means of which a further battery 40 (with a different nominal voltage than that of the battery 34) is incorporated into the on-board electrical system of the vehicle, such that a “further on-board electrical system” for a supply to further consumers (with a different nominal voltage) is created in this way.

(8) For the control of the operation of the internal combustion engine 20 and of the electric machine 30, a control device 10 is provided which is configured as a program-controlled electronic control device and which, as symbolized in FIG. 1, is operatively connected by means of communication links 11′ and 12′ to the internal combustion engine 20 and to the current converter device 32 in order to perform these control tasks.

(9) Via the communication links 11′ and 12′ (implemented for example as part of a digital communication bus system), it is possible for state values, detected for example by sensor means in the region of the internal combustion engine 20 and of the electric machine 30 (together with DC/AC converter 36) respectively, to be transmitted to the control device 10, and for control commands to be transmitted from the control device 10 to the controlled components 20, 30.

(10) The control device 10 performs the control on the basis of specifications which arise from operator control commands or operator control actions from a driver of the vehicle (for example switching-on of an ignition/electrical supply, accelerator pedal actuation etc.) or which, in the case of an autonomous vehicle, are provided by a navigation system, as is symbolized in FIG. 1 by an “operator control/navigation specification signal” s fed to the control device 10.

(11) If, for example, a particular drive torque of the drivetrain is commanded on the basis of such a specification by means of the signal s, the control device performs control processes suitable for this purpose in accordance with a hybrid drive strategy.

(12) This includes in particular, for example, proper starting of the internal combustion engine 20 by virtue of the electric machine being energized in order to bring the internal combustion engine 20 into a running state.

(13) FIG. 2 shows the construction of the control device 10 in somewhat more detail. Said control device has: an engine control part 11 for the control of the internal combustion engine 20, comprising at least control of a fuel feed enablement and possibly an ignition enablement of the internal combustion engine 20, an electric machine control part 12 for the control of the electric machine 30, comprising at least control of an energization of the electric machine 30, a monitoring part 13 which is designed to monitor proper operation of the engine control part 11 and of the electric machine control part 12 and, in the event of a malfunction being detected, to take over at least one control function of the engine control part 11 and/or of the electric machine control part 12 within a reaction period.

(14) In the exemplary embodiment illustrated, the engine control part 11 and the electric machine control part 12 can be regarded as being subordinate to a drivetrain control part 14, or as components of said drivetrain control part 14, the task of which is to receive control commands from the driver (or alternatively, in the case of an autonomous vehicle, navigation commands), which commands are contained in the supplied specification signal s, and, on the basis of these, to generate, in accordance with the hybrid drive strategy, control commands for all actuatable components in the drivetrain, that is to say in particular the internal combustion engine 20 and the electric machine 30 (though these may also include for example the clutch 3, the transmission 4 and/or further drivetrain components which are not illustrated).

(15) Here, control commands relating to the operation of the internal combustion engine 20 are processed by the engine control part 11 in order to output more specific control commands, such as in this case relating to an injection enablement and an ignition enablement, via the communication link 11′ to the internal combustion engine 20 (to an interface device of the internal combustion engine 20, which is connected to respective actuators or sensors).

(16) Control commands relating to the operation of the electric machine 30 are processed by the electric machine control part 12 in order to generate more specific control commands for the electric machine 30 or the associated DC/AC converters 36 thereof, and output said commands via the communication link 12′.

(17) In the context of the control of the drivetrain performed by the drivetrain control part 14 (for example through specification of an acceleration or deceleration torque in the drivetrain), it is also possible for direct communication between the engine control part 11 and the electric machine control part 12 to be provided, for example a specification of torque setpoint values from the engine control part to the electric machine control part 12, which controls the operation of the electric machine 30.

(18) The engine control part 11, the electric machine control part 12 and the drivetrain control part 14 collectively constitute, as it were, a “normal function level”, whereas the monitoring part 13 constitutes a redundant monitoring level (protected by particular safety mechanisms) which monitors the engine control part 11, the electric machine control part 12 and also the drivetrain control part 14.

(19) In the case of a malfunction of one of the monitored parts 11, 12 and 14 being detected, the monitoring part 13 takes over at least one control function of the engine control part 11 and/or of the electric machine control part 12 within a “reaction period”.

(20) One special feature of the control device 10 consists in that this has an engine false start prevention part 15 which is designed to identify a transition from a stationary state to a running state of the internal combustion engine 20 and, in the event of such a transition being identified, to check whether a proper start of the internal combustion engine 20 has been demanded within a predetermined period in the past in order, in the event of such a start not having been demanded, to prevent the fuel feed enablement and/or the ignition enablement for a predetermined “engine interruption duration”, wherein the engine interruption duration is at least as long as the abovementioned reaction period.

(21) It is thus advantageously possible for an “unauthorized start” of the internal combustion engine 20, for example owing to a malfunction of the electric machine control part 12 and/or of the associated DC/AC converter 36, to be prevented.

(22) In the exemplary embodiment illustrated, the reaction times (until the withdrawal of the malfunction) of the monitoring part 13 lie in the range from approximately 100 ms to 300 ms, and, accordingly, the engine false start prevention part 15 provides a “reaction period” of for example 300 ms.

(23) In this example, the “engine interruption duration” is selected to be 2 s, such that the period until the internal combustion engine 20 could “start up” if the fuel feed enablement and/or ignition enablement were not prevented is very reliably bridged, as it were, by the engine interruption duration. In the example illustrated, the injection enablement and the ignition enablement at the internal combustion engine 20 are prevented. The engine interruption duration for the prevention of the enablement, or the blocking, of ignition/injection in particular encompasses the period after which, after prevention of the torque generation of the electric machine 30, the engine rotational speed has reliably fallen again to an extent sufficient that ignition/injection would be deactivated in any case (for example at a rotational speed<50 rpm).

(24) The engine false start prevention part 15 identifies a transition from a stationary state to a running state of the internal combustion engine 20 on the basis of an evaluation of a stored and continuously updated state value relating to a rotational velocity (for example “rotational speed”) of the internal combustion engine 20. In the illustrated example, the rotational speed of the internal combustion engine 20 is continuously communicated via the communication link 11′ to the control device 10, which stores and continuously updates this rotational speed in a warm-reset-proof memory area of the control device 10. Error-free identification is thus ensured even after a warm reset of the control unit (for example microcontroller device) which implements the engine false start prevention part 15.

(25) The evaluation performed by the engine false start prevention part 15 could for example consist in checking whether a transition from a rotational speed of approximately zero (for example rotational speed lower than 50 rpm) to a rotational speed approximately corresponding to idling of the internal combustion engine (or higher) has occurred (for example rotational speed higher than 700 rpm in the case of nominal idling rotational speed of 900 rpm).

(26) Since it is however generally the case in internal combustion engines that ignition and fuel injection are enabled already at a much lower rotational speed, and an internal combustion engine can subsequently run up “automatically” to idling rotational speed if combustion is possible, it is normally expedient for a rotational speed much lower than the idling rotational speed (for example less than 20% or even less than 10% of the respective idling rotational speed) to be used as a threshold for the identification of a running state of the internal combustion engine.

(27) Against this background, in the example illustrated, the evaluation consists in checking whether, in the internal combustion engine 20, a transition from a rotational speed of approximately zero (for example rotational speed lower than 50 rpm) to a rotational speed of at least 50 rpm (or higher) has occurred.

(28) The engine false start prevention part 15 performs the required check, as to whether a proper start of the internal combustion engine 20 has been demanded (for example by means of the specification signal s or for example by the drivetrain control part 14 or for example by the engine control part 11) within a predetermined period in the past, by means of a read-out from a memory in which such demands for a proper start are temporarily stored at least for the predetermined period.

(29) This “predetermined period” should be selected to be at least as long as the period required by the internal combustion engine 20, proceeding from the stationary state, after a demand for a proper start, to arrive at the running state or to reach at least a rotational speed (in the example, 50 rpm) which, in the case of the discussed evaluation of the engine false start prevention part 15, is used as the identification threshold for the identification of a running state of the internal combustion engine 20. In the example illustrated, it is assumed (merely by way of example) that this is the case after typically 150 ms. Here, the predetermined period is set, with a certain safety margin (generally for example in the range from 1.2 times to 3 times the typical duration of the start process), at 250 ms.

(30) In the exemplary embodiment illustrated, the monitoring part 13 is in particular also designed to monitor proper operation of the engine false start prevention part 15 and, in the specific case of a malfunction of the engine false start prevention part 15 being detected, to take over the control function thereof. The engine false start prevention part 15 on the normal function level (as a constituent part of the engine control part 11) is thus advantageously also implemented redundantly on the monitoring level.

(31) In summary, according to the above exemplary embodiment, “temporary injection and/or ignition suppression” after a commencement of engine running in the absence of a prior start demand is used in order to rule out an unauthorized start or continued running of the engine despite an error reaction time of the monitoring part. As a result of the elimination of the injection and ignition suppression after a predefined duration (engine interruption duration), the possibility of an engine start by towed starting or push-starting of the vehicle is advantageously maintained. Preferably, the information regarding the state of a running engine is stored in a reset-proof memory area in order, after a warm reset, to identify the state of the previously running engine and, in this case, perform no suppression in the event of a running engine being identified.

(32) In the case of a significant reaction time of the safety level, for example of a current converter (inverter) for the control of the energization of the electric machine, for example of the order of magnitude of approximately 100 to 300 ms, it would readily be possible, without the measure according to the invention, in the case of an inverter malfunction (for example with a fully activated maximum torque of the electric machine), for the internal combustion engine to reach a rotational speed at which the injection would normally be activated. With the aid of the invention, it is however possible to ensure a safe system function without the need for the technical outlay for reduced reaction times of the safety level (in particular of the inverter). This leads to a cost reduction (for example in the realization of the inverter).

LIST OF REFERENCE DESIGNATIONS

(33) 1 Hybrid drive arrangement

(34) 2 Rotary shaft (coupling)

(35) 3 Clutch

(36) 4 Transmission

(37) 5 Differential transmission

(38) W1-W4 Vehicle wheels

(39) s Operator control/navigation specification signal

(40) 10 Control device

(41) 11 Engine control part

(42) 11′ Communication link

(43) 12 Electric machine control part

(44) 12′ Communication link

(45) 13 Monitoring part

(46) 14 Drivetrain control part

(47) 15 Engine false start prevention part

(48) 20 Internal combustion engine

(49) 30 Electric machine

(50) 32 Current converter device

(51) 34 Battery

(52) 36 DC/AC converter

(53) 38 DC/DC converter

(54) 40 Further battery