Control device and method for operating a hybrid drive system

Abstract

The invention relates to a control device for a hybrid drive system, comprising an internal combustion engine, an electric machine, at least one torsional vibration damper and an electronic control unit, wherein the torsional vibration damper is designed for optimized vibration damping when the internal combustion engine is operated with the full number of cylinders of the internal combustion engine, and the control unit is configured such that the electric machine simulates at least almost equally the torque excitation of the deactivated internal combustion engine in connection with cylinder ignition in purely electric operation until the internal combustion engine is started again.

Description

Technical Field

[0001] The present invention relates to control devices and methods for operating a hybrid drive system for a motor vehicle, the hybrid drive system having at least one electric drive motor (also referred to as an electric motor or simply an electric motor) and an internal combustion engine (also referred to as an internal combustion engine (VKM)), the at least one electric drive motor and the internal combustion engine being used separately or together to generate the driving torque required mostly at the transmission output of the vehicle. Background Technology

[0002] EP 2 911 928 B1 relates to a method for torsional vibration smoothing in a drivetrain having an internal combustion engine (especially a reciprocating piston engine) and at least one additional machine (especially an electric motor) connected to the internal combustion engine. During at least one first phase of the internal combustion engine, torque pulses are introduced into the drivetrain, and at least one torque pulse for torsional vibration smoothing is selectively generated by the additional machine. During at least one second phase following the first phase, the torque pulses of the additional machine are introduced into the drivetrain in a manner that is out of phase with the torque pulses of the internal combustion engine. Here, EP 2 911 928 B1 relates to providing a solution for improving comfort in conventional internal combustion engines with three or fewer cylinders, a solution that is disadvantageous from the perspective of vibration and torsional vibration technology. Summary of the Invention

[0003] The objective of this invention is to improve the comfort and dynamics of a vehicle in a control unit and method for operating a hybrid drive system, while maintaining reduced energy consumption.

[0004] This task is solved by the features of the present invention.

[0005] The present invention relates to a control device for a hybrid drive system, the hybrid drive system comprising an internal combustion engine, an electric motor, at least one torsional vibration damper and an electronic control unit, the electric motor being designed to generate driving torque for a vehicle, wherein the torsional vibration damper is designed for optimized vibration damping during operation of the internal combustion engine with all cylinders of the internal combustion engine in operation.

[0006] Furthermore, the control unit is configured such that the electric motor, in pure electric operation, at least almost identically simulates the (complete) cylinder ignition-related torque excitation of the deactivated internal combustion engine by means of electrically generated torque excitation, until the internal combustion engine is restarted.

[0007] Alternatively or additionally, the control unit is configured such that the electric motor, when the internal combustion engine is running with only partially deactivated cylinders, at least almost identically supplements the missing cylinder ignition-related torque excitation of the deactivated cylinders until all cylinders of the internal combustion engine are restarted. Partial cylinder operation or operation with partially deactivated cylinders means that some cylinders of the internal combustion engine are not ignited and therefore do not provide torque excitation.

[0008] The characteristic of torsional vibration dampers (especially torsional mass oscillators) is that the damping mass supported by the oscillation is functionally matched to the excitation of a specific number of cylinders in an internal combustion engine.

[0009] This invention is based on the following two fundamental understandings, which are related individually or in combination with each other.

[0010] Basic understanding 1:

[0011] In a hybrid drivetrain, the damping effect of a torsional damper in the form of a speed-sensitive mass oscillator is preferably achieved in electric driving mode:

[0012] According to the present invention, in a topology having P1 or P2 ( Figure 1 In a hybrid drive system, a torsional vibration damper (especially a torsional mass oscillator) is provided as a damping or buffering measure for the torsional vibration of the internal combustion engine. The damping mass of the torsional vibration damper is oscillatingly supported and functionally matched to the excitation of a specific number of cylinders in the internal combustion engine.

[0013] In electric driving mode, there is usually no excitation caused by the internal combustion engine, in which the torsional mass oscillator or torsional damper loses its damping characteristics.

[0014] When the internal combustion engine suddenly restarts, the oscillating torsional mass requires a limited time to exert its damping effect due to the engine's initial start-up after pure electric driving. Therefore, this can negatively impact comfort, particularly in the P1 architecture or in the P2 architecture when transitioning from pure electric driving to hybrid and / or internal combustion engine driving, which is used in a simulated P1 mode, i.e., achieving electric driving with a closed disengagement clutch.

[0015] Therefore, according to the first concept of the present invention, in pure electric drive, a torque variation curve similar to the excitation caused by the cylinder of the internal combustion engine is applied to the torque of the motor, with the aim of maintaining the torsional vibration damper or torsional mass oscillator supported downstream in its damping effect.

[0016] Basic understanding 2:

[0017] Using at least one specific torsional vibration damping system in the form of a torsional vibration damper, preferably a combination of a torsional vibration damper and a torsional vibration damper, and by means of a corresponding torque excitation from an electric motor, the torsional vibration damper (especially implemented as a speed-sensitive mass oscillator or centrifugal pendulum) is maintained at different excitation frequencies based on an internal combustion engine arrangement:

[0018] This understanding is based on the analysis of the vibration characteristics of a hybrid drivetrain with at least one speed-sensitive torsional vibration damper, preferably a mass oscillator, under selective cylinder deactivation.

[0019] According to the invention, at least one torsional vibration damper with a specific engine arrangement is integrated into the drivetrain, the damper ensuring damping (preferably as complete as possible) of speed oscillations in the drivetrain at preferably relatively low speeds. When the internal combustion engine is running at its full cylinder count, the damper is matched to the excitation arrangement. In the case of operation of an internal combustion engine with (partial) cylinder deactivation, the damper loses most of its effectiveness due to the changed, excitation-driven engine arrangement.

[0020] Furthermore, to maintain the damping effect, according to the present invention, in the case of (partial) cylinder deactivation, for the speed-sensitive mass oscillator (DSM), the excitation frequency of the engine arrangement is maintained by a motor when all cylinders are running. The motor is preferably integrated between the internal combustion engine and the torsional damper (especially in the form of a speed-sensitive mass oscillator). Here, the motor is a frequency-controlled torque source that supplements the torque excitation of the deactivated cylinders of the internal combustion engine by electrically generated targeted torque excitation. For this purpose, the missing torque excitation, time-synchronized with the deactivated cylinders, is introduced by the motor with a similar amplitude and shape.

[0021] Preferably, an additional torsional damper, for example in the form of a spring stage, is integrated between the internal combustion engine and the electric motor to pre-damp the torque excitation of the internal combustion engine, so that the torque excitation caused by the electric motor does not have to be at the level of the torque excitation of the internal combustion engine.

[0022] This invention is also based on the following extended understanding:

[0023] When the internal combustion engine restarts and the necessary traction is compensated by the electric motor until the traction is taken over by the ignited internal combustion engine, a large amount of energy is undesirably consumed and time is required.

[0024] In known hybrid drive system topologies with a disengagement clutch between the internal combustion engine and the electric motor, the internal combustion engine is typically decoupled by engaging the disengagement clutch during pure electric driving. Pure electric driving with a towing or coupled internal combustion engine has not yet been used due to its high drag torque.

[0025] In an advantageous extension, the invention specifies that, under preset operating conditions, particularly in pure electric driving and / or during energy recovery, the internal combustion engine is not decoupled (if entirely possible), but rather its drag torque is reduced as much as possible.

[0026] Here, according to the present invention, in the non-ignition operation of an internal combustion engine, the scavenging valve control device (especially for the cylinder intake and cylinder exhaust valves) is operated in a sense that the intake and exhaust valves are at least almost completely, preferably completely, and persistently closed, said scavenging valve control device is actually configured for charging control in an ignited internal combustion engine. Preferably, the non-ignition, towing operation of the internal combustion engine is activated under specific conditions in pure electric driving (positive driving torque) or under specific conditions in energy recovery (negative driving torque) with such closed intake and exhaust valves.

[0027] By utilizing the extended scheme according to the invention, drag torque is significantly reduced not only in hybrid power architectures with fixed coupling between the electric motor and the internal combustion engine, but also in hybrid power architectures with a disengaging clutch between the internal combustion engine and the electric motor, by means of a lock-up intake valve and an exhaust valve on the internal combustion engine during non-ignition operation of the internal combustion engine.

[0028] A particularly advantageous implementation scheme for a lock-up valve, not only in the case of towing in pure electric operation but also in the case of towing energy recovery, is: fully variable valve stroke control on the intake valve side and simple deactivation of the valve mechanism on the exhaust valve side by means of a switching actuator. To illustrate the principled structure of a feasible valve control device for fully variable valve stroke control, see, for example, DE 101 23 186 A1.

[0029] According to another approach, a software (SW) program is used in the control unit. This software program can be configured to be implemented on the processor of the control unit (e.g., on the vehicle's controller) and thereby to implement the methods described herein.

[0030] According to another aspect, a storage medium is described. The storage medium may include software programs configured to be implemented on a processor and thereby to implement the methods described herein.

[0031] It should be noted that the methods, apparatus, and systems described herein can be used not only individually but also in combination with other methods, apparatus, and systems described herein. Furthermore, any aspect of the methods, apparatus, and systems described herein can be combined with each other in various ways. In particular, the features of the invention can be combined with each other in various ways. Attached Figure Description

[0032] The invention will now be described in more detail with reference to embodiments. Herein, in the accompanying drawings:

[0033] Figure 1 The diagram schematically illustrates a vehicle having a hybrid drivetrain and a control unit for controlling an electric motor as an electric drive motor according to the invention. The hybrid drivetrain can be optionally configured as a P1 architecture or a P2 architecture.

[0034] Figure 2 A first alternative scheme for controlling the motor according to the invention is shown, and

[0035] Figure 3 A second alternative scheme for controlling the motor according to the present invention is shown. Detailed Implementation

[0036] Figure 1 The vehicle includes an internal combustion engine 3 and an electric motor 5, which can be used individually or in combination to generate a driving torque for the vehicle 1. The internal combustion engine 3 and the electric motor 5 are configured such that the torques generated by the respective drive motors are added together to form a total driving torque, which is typically transmitted to at least two drive wheels of the vehicle 1, for example, via a transmission 7 and the output shaft of the transmission 7. Electrical energy for operating the electric motor 5 is stored in an energy storage device (e.g., a 48V battery or a high-voltage storage device), which is not shown in more detail here.

[0037] Furthermore, vehicle 1 includes an electronic control unit 10 (e.g., a motor controller) configured to determine the required total driving torque. The required total driving torque can be preset, for example, by the driver of vehicle 1 via the accelerator pedal. For instance, the driver can manipulate the accelerator pedal to request an increased total driving torque. The control unit 10 can be configured to divide the required total driving torque into a first torque for the internal combustion engine 3 and a second torque for the electric motor 5. In other words, the control unit 10 can be configured to operate the internal combustion engine 3 and the electric motor 5 according to the required total driving torque.

[0038] also, Figure 1An optional disengagement clutch 8 is shown, through which the internal combustion engine 3 and the electric motor 5 can be decoupled. With this disengagement clutch 8, a so-called P2 hybrid topology exists. Without this disengagement clutch 8, a so-called P1 hybrid topology exists.

[0039] The torsional vibration damper 4 is preferably disposed between the internal combustion engine 3 and the electric motor 5 in the form of a spring buffer. For example, a torsional vibration damper 9 in the form of a centrifugal pendulum is connected downstream of the electric motor 5.

[0040] The internal combustion engine 3 preferably has a first valve control device for closing the intake valve and a second valve control device for closing the exhaust valve. The first and second valve control devices, combined with a function module for reducing drag torque in the control unit 10, can achieve highly effective drag reduction by closing the intake and exhaust valves. Finally, a starting element 6, preferably in the form of a clutch or a torque converter with a lock-up clutch, is preferably provided upstream of or within the transmission 7. The device for reducing drag torque... Figure 1 It is schematically shown in the accompanying figure with reference numeral 2.

[0041] The internal combustion engine 3 of the hybrid drive system can be at least partially or completely deactivated, for example, in the case of (pure) electric operation of the hybrid drive system (if necessary) and / or in the case of energy recovery during so-called inertial coasting when the vehicle's wheels drive the output shaft. The drive shaft of the deactivated internal combustion engine 3 can therefore be driven and / or rotated by the electric motor 5 (in the case of the disengagement clutch 8 being engaged) and / or by the wheels of the vehicle 1 during non-ignition towing operation. The non-ignition towing operation of the internal combustion engine 3 has the advantage that the internal combustion engine 3 can be quickly and efficiently re-ignited to provide drive torque to the overall drive system of the vehicle 1.

[0042] According to the present invention, the torsional vibration damper 9 is designed for optimized vibration damping during the operation of the internal combustion engine with all cylinders of the internal combustion engine 3 (4 in this case).

[0043] With the help of Figure 2 The effects of the method according to the first alternative scheme according to the invention are illustrated schematically or qualitatively:

[0044] The control unit 10 is configured such that, during pure electric operation, the motor 5 at least almost identically simulates the cylinder ignition-related torque excitations Z1 to Z4 of the deactivated internal combustion engine 3 as electric torque excitations ME (Z1' to Z4') until the internal combustion engine 3 restarts. MS represents the sum of the two torque excitations MV and ME.

[0045] With the help of Figure 3The effects of the method according to the second alternative scheme of the present invention are shown:

[0046] The control unit 10 is configured to such that the electric motor 5, in the case of only partially deactivated cylinders of the internal combustion engine 3 (Z2 and Z4 in this case), supplements the missing cylinder ignition-related torque excitation MV of the deactivated cylinders with at least almost the same electric torque excitation ME (Z2' and Z4') until all cylinders of the internal combustion engine 3 are restarted.

[0047] Preferably, the internal combustion engine 3 is driven or kept coupled by the electric motor 5 during operation that is partially or completely deactivated (without combustion), wherein, especially in the P2 topology, the clutch 8 remains closed.

[0048] The torsional vibration damper 4 disposed between the internal combustion engine 3 and the electric motor 5 is preferably configured as a spring stage for vibration damping throughout the entire speed range.

[0049] The torsional vibration damper 9 located downstream of the motor 5 is preferably configured as a speed-dependent centrifugal pendulum for vibration damping in a relatively low speed range.

[0050] This invention is not limited to the embodiments shown. In particular, it should be noted that the specification and drawings are intended to illustrate the principles of the proposed methods, apparatus, and systems only.

Claims

1. A control device for a hybrid drive system, the hybrid drive system comprising an internal combustion engine (3), an electric motor (5), at least one torsional vibration damper (9), and an electronic control unit (10), the electric motor being designed to generate driving torque for a vehicle, - The torsional vibration damper (9) is designed for optimized vibration damping when the internal combustion engine is running at all cylinder numbers of the internal combustion engine (3), and The control unit (10) is configured such that the electric motor (5) in pure electric operation simulates, at least almost equally, the cylinder ignition-related torque excitation (MV) of the deactivated internal combustion engine (3) by means of an electrically generated torque excitation (ME) until the internal combustion engine (3) is restarted, with the aim of maintaining the downstream torsional damper in its damping effect.

2. A control device for a hybrid drive system, the hybrid drive system comprising an internal combustion engine (3), an electric motor (5), at least one torsional vibration damper (9), and at least one electronic control unit (10), the electric motor being designed to generate driving torque for a vehicle. -The torsional vibration damper (9) is designed for optimized vibration damping when the internal combustion engine is running at full cylinder capacity of the internal combustion engine (3). -The internal combustion engine (3) is configured to perform full and partial cylinder operation, and The control unit (10) is configured such that the electric motor (5) supplements, at least almost equally, the missing cylinder ignition-related torque excitation (MV) of the deactivated cylinders (Z2, Z4) by means of electrically generated torque excitation (ME) during the operation of some cylinders of the internal combustion engine (3) until all cylinders of the internal combustion engine (3) are restarted, thereby maintaining the damping of the torsional vibration damper under different excitation frequencies based on the engine arrangement of the internal combustion engine by means of the corresponding torque excitation of the electric motor.

3. The control device according to claim 1 or 2, characterized in that, The internal combustion engine (3) is driven and towed by the electric motor (5) during operation that is partially or completely shut down.

4. The control device according to claim 1 or 2, characterized in that, The internal combustion engine (3) has a regulating device (2) for deactivating the intake valve opening action and the exhaust valve opening action, and the control unit (10) is configured such that the intake valve opening action and the exhaust valve opening action are deactivated when the internal combustion engine (3) is at least partially or completely deactivated and towed by the electric motor (5).

5. The control device according to claim 1 or 2, characterized in that, An additional torsional damper (4) is installed between the internal combustion engine (3) and the electric motor (5).

6. The control device according to claim 1 or 2, characterized in that, The torsional vibration damper (9) is located downstream of the motor (5).

7. The control device according to claim 5, characterized in that, The torsional damper (4) is configured as a spring stage for vibration damping throughout the entire speed range.

8. The control device according to claim 1 or 2, characterized in that, The torsional vibration damper (9) is configured as a speed-dependent centrifugal pendulum for vibration damping in a relatively low speed range.

9. A method for operating a hybrid drive system by means of a control unit (10) according to any one of claims 1 to 8, - The torsional vibration damper (9) is designed for optimized vibration damping when the internal combustion engine is running at all cylinder numbers of the internal combustion engine (3), and - By means of the control unit (10) that controls the electric motor (5). - In pure electric operation, the torque excitation (ME) generated electrically is used to at least almost identically simulate the cylinder ignition-related torque excitation (MV) of the deactivated internal combustion engine (3) until the internal combustion engine (3) is restarted. The purpose is to maintain the downstream torsional damper in its damping effect, and / or - In the case of only partially deactivated cylinders of the internal combustion engine (3), the missing cylinder ignition-related torque excitation (MV) of the deactivated cylinders (Z2, Z3) is supplemented at least almost the same by means of electrically generated torque excitation (ME) until all cylinders of the internal combustion engine (3) are restarted, thereby maintaining the damping of the torsional vibration damper under different excitation frequencies based on the engine arrangement of the internal combustion engine by means of the corresponding torque excitation of the electric motor.

10. The application of the method according to claim 9 or the control device according to any one of claims 1 to 8 in a P2 topology hybrid drive system, the P2 topology hybrid drive system having a disengagement clutch (8) that keeps closed between the internal combustion engine (3) and the electric motor (5).

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