EP3490833A1

EP3490833A1 - A method for departing from a recuperation phase in a parallel hybrid vehicle

Info

Publication number: EP3490833A1
Application number: EP17743331.5A
Authority: EP
Inventors: Sebastian Liebert; Michael Friedrich; Benjamin KLUGE
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 2016-08-01
Filing date: 2017-07-25
Publication date: 2019-06-05
Also published as: DE102016214148A1; CN109476226B; WO2018024541A1; US20190168743A1; CN109476226A; US11167748B2

Abstract

A method is provided for departing from a recuperation phase in a parallel hybrid vehicle, wherein, in a first step, the vehicle is in a recuperation phase, started by means of a trigger, with a predefined recuperation driving demand, and, in a second step, the electric machine is brought to an increased rotational speed during the recuperation phase. In a third step, a phase for departing from the recuperation phase is started by means of a trigger, wherein, in this phase, the internal combustion engine is made available for coupling to the electric machine, such that a target rotational speed determined between the internal combustion engine to be connected and the electric machine for the connection to the transmission input is set, and in parallel, by means of an upshift, a highest possible gear ratio for the connection to the drivetrain is set, in order to satisfy a present driving demand. In a fourth step, the departure from the recuperation phase is completed.

Description

Method for leaving a recuperation phase in one

Paralielhybridfahrzeug

The invention relates to a method for exiting a recuperation phase in a parallel hybrid vehicle.

In current hybrid applications, especially parallel (P2) hybrid applications, an attempt is made to make the exit from a recuperation phase as fast and smooth as possible, i. to optimize the operating strategy for connecting the internal combustion engine. This applies both to high-voltage hybrids with voltages of> 60V and to low-voltage hybrids with a voltage of <60V, e.g. 48V in future

Applications.

In previous operating strategies, the trigger is the start of the

Internal combustion engine, a load request on the accelerator pedal. Here, the decoupled internal combustion engine is started from zero speed by a suitable start system by means of drag start or pinion starter and then by

Burning fuel is brought to the appropriate connection speed to the output. Only then is it on the clutch to the drive train

coupled and can contribute to the acceleration of the vehicle. The resulting period without sufficient implementation of the load requirement of the driver and high consumption of electrical energy, which is limited, especially in low-voltage systems available for bridging to the load transfer of the engine leads to functional deficits and only difficult or unacceptable vehicle reactions driver requirements. As an alternative to this method, the engine could remain coupled in braking phases, which the Zustartzeit would be omitted, but also reduces the Rekuperationspotential by the applied drag torque.

The above-mentioned operating strategies are now, for example, in German automakers in series, with a variety of patent applications and

Patents in the areas of recuperation, start / stop and docking of the

Internal combustion engine present.

Based on the above, it is an object of this invention to provide a method that shortens the period without sufficient implementation of the load demand of the driver and high consumption of electric power. This object is achieved by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims.

The inventive method can also with the same effect

different topologies of a parallel hybrid vehicle are used, i. not only in the P2 system but also in a swing-start device as described in Patent No. DE102014214614 B4 and Patent No. DE102014214617 B4, both by BMW AG. This is in addition to at least

required separation device provided a device which allows a coupling of the internal combustion engine to the electric motor, or in other systems which are suitable because of their mechanical properties. For different topologies then the mechanical conditions for coupling or decoupling must be taken into account.

It proposes a method for exiting a recuperation phase in a parallel hybrid vehicle, comprising an internal combustion engine and an electric machine that can be coupled therewith via a separating clutch in conjunction with a device for shock decoupling, comprising at least one flywheel and a second clutch connected gearbox

connectable, wherein the internal combustion engine is completely decoupled from the electric motor via the separating clutch, and wherein the vehicle in a first step in a triggered by a trigger recuperation phase with predetermined Recuperation drive request is located, and in a second step, the electric motor is brought to an increased speed during the Rekuperationsphase. In a third step, a trigger is used to phase out the

Rekuperationsphase started, in which phase the engine is made available for coupling to the electric motor by the second clutch is opened and when it is open, a closing of the clutch takes place, so that the start of the engine is performed as a pulse start such in that a target rotational speed determined between the internal combustion engine to be connected and the flywheel mass for connection to the transmission input is established and, in parallel, the highest possible gear for connection to the drive train is set by means of gear upshifting in order to fulfill a present travel request. In a fourth step, the second clutch is closed fully regulated, so that the exit from the Rekuperationsphase is completed.

Also proposed is a method for exiting a recuperation phase in a parallel hybrid vehicle, comprising an internal combustion engine and an e-machine coupled thereto via a separating clutch, which one with a

Powertrain connected transmission is connectable, wherein the internal combustion engine is completely decoupled from the electric motor via the separating clutch, and wherein the vehicle is started in a first step in a triggered by a trigger

Rekuperationsphase with predetermined recuperation driving request is, and in a second step, the electric motor is brought to an increased speed during the Rekuperationsphase. In a third step, a release phase is started by a trigger from the recuperation phase, in which phase the engine is made available for coupling to the electric motor, a regulated closing of the clutch and a setting of positive torque in the electric motor takes place, so that the start of the internal combustion engine is carried out as an assisted pulse start such that a to be connected between

Setting the internal combustion engine and electric motor for connection to the transmission input determined target speed and parallel by means of gear upshifting a highest possible gear for connection to the drive train is set to a present

Driving requirement to meet. In a fourth step, the separating clutch is completely closed, so that the exit from the Rekuperationsphase is completed. Under Rekuperations driving request and under driving requirement is the requirement to change the driving behavior understood that the trigger to the

Vehicle control is given. For example, by pressing the

Brake pedal, so by pressing or releasing the brake pedal, the requirement made that braked or not to be braked and how much the braking or releasing the brake should be done. Further, releasing the accelerator pedal is a requirement to reduce the speed without braking.

The phase to exit from the recuperation phase begins with the actuation of the trigger and ends with closing the clutch or opening the second clutch.

It is also proposed that the trigger for entering the recuperation phase is an actuation of the brake pedal and to exit the recuperation phase is a decrease or release of the brake pedal or actuation of the accelerator pedal or a speed threshold below.

It is also proposed that in the P2 system in the third step in the phase to exit the Rekuperationsphase the controlled closing of the separating clutch by bringing the separating clutch into slippage occurs.

By the proposed method with the ability to use different triggers for entry and / or exit from the Rekuperationsphase, and by making available the internal combustion engine (VM short) already at the start of the phase to exit the Rekuperationsphase, i. before another

Driving requirement, e.g. an acceleration request is made, a faster fulfillment of the driver's request is ensured with simultaneous jerk-free coupling between the VM and electric motor.

It is also proposed that in the P2 system in the fourth step the

Disconnect in the driving request of a thrust upshift with a

Coupling speed between internal combustion engine and electric motor below the Target rehkun the new aisle is closed, and is closed when driving request a train request with a coupling speed between the engine and electric motor above the target speed of the new gear.

It is also proposed that in the P2 system in the third step for the

pulse start the kinetic energy from the pulse of the electric motor in conjunction with involved transmission parts and the available torque of the electric motor can be used.

It is also proposed that, when entering the recuperation phase, one or more gear downshifts take place to a gear below the gear intended at least for the re-engagement of the internal combustion engine.

By means of said measures, a driver comfortable, i. Jerk-free, coupling between combustion engine and electric motor done.

It is also proposed that during the recuperation phase

Gear tracking takes place in such a way that the at least necessary kinetic energy of the electric motor for the implementation of the pulse start request is maintained. This ensures that a supported pulse start can be carried out at any time and without delay.

Furthermore, a parallel hybrid vehicle is proposed, comprising a

Combustion engine and thus coupled via a clutch electric motor, which is connected to a connected to a drive train transmission, the engine is completely decoupled from the electric motor via the clutch, at least one detection, control and

Execution means adapted to detect a trigger for entry and exit from a recuperation phase, to send, receive and process signals to perform the proposed method.

Furthermore, a parallel hybrid vehicle is proposed, comprising a

Combustion engine and thus via a separating clutch in interaction with a device for shock decoupling, comprising at least one flywheel and a second clutch, coupled e-machine, which with one with a

Drive train is connected to the transmission, wherein the internal combustion engine can be completely decoupled from the electric motor via the separating clutch in conjunction with the device for shock decoupling, at least one detection, control and execution device, which are adapted to a trigger for boarding and Exit from a recuperation phase to capture, send, receive and process signals to perform the proposed method.

Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, with reference to the figures of the drawing, the inventive details shows, and from the claims. The individual characteristics can each individually for themselves or to several in arbitrary

Combination be realized in a variant of the invention.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings.

Fig. 1 shows a typical topology of a prior art parallel hybrid arrangement.

Fig. 2 shows another typical topology of a prior art parallel hybrid arrangement.

3 shows a flowchart of the method according to an embodiment of the present invention.

Figures 1 and 2 show a typical topology of a prior art parallell hybrid arrangement. Shown is a typical topology of a multi-turn automatically switchable transmission 3 in a motor vehicle, preferably one

Hybrid vehicle with conventional internal combustion engine (VM) 1 in combination with an electric machine (EM) 2 in a P2 arrangement (Fig. 1) or with a Flystart device (Fig. 2), so a parallel hybrid arrangement. The EM 2 can be coupled to the VM 1 or decoupled from it based on a predetermined operating strategy via the separating clutch K0. The EM 2 is connected to the multi-speed automatic shiftable transmission 3, which includes both a planetary gear and a DSG (dual-clutch transmission), a CVT (Continuously Variable Transmission) or another kind of multi-speed

automated switchable transmission can be. The transmission 3 is in turn connected to the drive train 4 for driving one or more wheels 5 of the hybrid vehicle.

As described above, in known methods, the exit from a

Recuperation phase normally triggered by the accelerator pedal, i. the VM 1 is switched on only when the accelerator pedal is operated, i. there is an active one

Raise the VM 1. This leads to a delay in the availability of the engine torque and thus the response to the driver's request. Moreover, this method is not optimal for low-voltage vehicle electrical systems, e.g. On-board electrical systems based on e.g. 48V, suitable because a lot of electrical energy is needed to connect the VM 1. This poses no problem with high-voltage systems, as they have enough power to implement the driver's desire for "acceleration." However, the disadvantage is that high-voltage systems require a lot of space and are heavy, which is why it must be used for future low-voltage applications another strategy can be found.

As shown in FIG. 1, only one separating clutch K0 can be provided for disconnecting or coupling the VM 1 to the EM 2, which may be referred to as a P2 hybrid. In Figure 2, an extension of the P2 system to a swing start device, i. a system with a flywheel storage device and flywheel, shown. This system has in addition to the separating clutch K0, which must always be located directly on the VM 1, since this separating coupling K0 is used for coupling or uncoupling of the VM 1, via a device formed as a fly-start device for shock decoupling K1 and 6. This device for shock decoupling has at least a flywheel 6 and a second clutch K1, wherein the flywheel between the

Disconnect K0 and the second clutch K1 is arranged. The second clutch K1 serves to couple the EM 2 to the VM 1 via the flywheel 6 with an almost complete shock decoupling. So it is an intermediate step to

Coupling of the EM 2 to the VM 1 installed in comparison to the P2 system, which provides for an improvement in the coupling, more precisely, a reduction in the impact when coupling. Thus, the coupling is even more comfortable for the driver, since the jerk is eliminated when docking.

Fig. 3 shows a flowchart of the method according to both embodiments of the present invention. The aim of the proposed method is to significantly shorten the period without sufficient implementation of the load requirement of the driver and high consumption of electrical energy, as described above, and thus the use of a P2 system or a fly-starting device, so one

Parallel hybrid system, on a low-voltage basis, e.g. on 48V basis, to enable or to improve. By the proposed method, the driver's request can be met faster and the consumption of electrical energy for vehicle propulsion can be limited.

To implement the method, in a first step S1, the trigger or

Trigger for setting off and starting the VM 1 to a pedal position, e.g. the position of the brake pedal or the accelerator pedal or on a

Speed threshold (for the exit from the Rekuperationsphase) placed below. The entry into the recuperation phase is e.g. initiated by pressing the brake pedal. In this case, the separating clutch K0 between VM 1 and EM 2 is opened and the VM 1 is turned off, i. off.

At the same time in a second step S2 in the transmission 3 more

Gear downshifts performed. The gear downshifts are performed such that the EM 2 connected to the transmission input shaft is brought to a high speed and thus to the high kinetic energy state. For this purpose, it is preferable to switch back by more gears than would be necessary for the braking process. As a result, improved recuperation can be achieved, ie more energy is available at the end of the recuperation phase in order, for example, to couple the VM 1. In a further step, the speed difference, from which an engine start of the VM 1 can take place at any time according to the known pulse starting method by closing the separating clutch K0, is considered. During the recuperation phase, the gears are tracked in the transmission 3 in order to maintain the high kinetic energy state in the EM 2. This means, for example, that the gears are downshifted in order to continue recuperation

optimize.

The exit from the recuperation phase is triggered in a third step S3 by releasing the brake pedal or falling below a speed threshold or pressing the accelerator pedal, also simultaneously with the brake pedal. This can e.g. detected by a corresponding existing sensors and for processing at e.g. a control device to be passed. After detecting the start of the recuperation phase, depending on which parallel hybrid system is used, so P2 or

Flystart device, the VM 1 again coupled to the EM 2. In the P2 system shown in Figure 1, closed-loop closing of the disconnect clutch K0, i. the clutch is slipped, and positive moment locations in the EM 2 are the start of the VM 1 as a supported pulse start. The aim is to execute the pulse start in such a way that the adjusting speed between

connected VM 1 and EM 2 sets above the target speed for connection to the output. So the goal is to have one to connect between

Internal combustion engine VM 1 and

E-machine sets EM 2 for connection to the transmission input determined target speed and parallel by means of gear upshift a highest possible gear to

Connection to the drive train 4 is set to a present

Driving requirement to meet

In the case of the fly-starting device shown in FIG. 2, the second clutch K1 is opened, so that in an intermediate step a separation of the EM 2 from the

Flywheel 6 takes place, which is still decoupled from the VM 1 via the clutch K0. When the second clutch K1 is open, a controlled

Closing the clutch K0, so that the start of the engine is performed as a pulse start, that is to be connected between a Combustion engine VM 1 and flywheel 6 for connection to the

Set transmission input determined target speed and parallel by means of gear upshifting a highest possible gear for connection to the drive train 4 is set to meet a present driving request.

Parallel to the support pulse start the gearbox 3 thus performs in both cases an upshift of the gears, preferably to a gear above the gear required for coupling the VM 1. Thus, at least the proportionate implementation of the driver's request is achieved via the Reibschaltmomente, the goal is that the highest possible gear for connection to the drive train 4 above the

Idle speed is reached, i. the transmission input speed is kept as low as possible.

Subsequently, in a fourth step S4, closing the powertrain, i. the separating clutch K0 in the P2 system and the second clutch K1 in the

Flystart device, the complete adhesion between VM 1, EM 2 and output represented and thus the Rekuperationsphase finished.

In one example, the entry and exit from the Rekuperationsphase be triggered by pressing the brake pedal. As a result, the VM 1 is disconnected by opening the separating clutch K0 of the EM 2 and thus the transmission 3, ie

switched off, i. he does not deliver a moment.

Already at the start of the recuperation phase, the kinetic energy of the EM 2 is increased by switching back the gears below the required gear for the required target speed for reconnecting the VM 1. During the

Rekuperationsphase takes place if necessary, a further tracking, so e.g.

Downshift, the gears to keep the kinetic energy in the EM 2 as high as possible.

The exit from the recuperation phase is again by a trigger, in this example by releasing the brake pedal. During release of the brake pedal, the separating clutch K0 is brought into slippage in the P2 system or in the Flystart first the second clutch K1 opened and then the

Disconnect KO closed, so that VM 1 and EM 2 are separated. Then, a target speed is determined based on the detected travel request, and the gears are upshifted to a gear higher than that for the clutch, i. for the required speed, gear required to meet the driver's request. The determination of the required speed is performed by known methods.

Driving requirements which may arise when triggering the exit from the recuperation phase may be a push upshift or an upshift. In a shear upshift, so when releasing the brake pedal without request that acceleration should take place, so for example. by not pressing the

Accelerator, the clutch KO is closed in the P2 system with a coupling speed below the target speed of the new gear. At a

Upshift, that is, an acceleration request, e.g. by pressing the accelerator pedal, the clutch KO is closed in the P2 system with a coupling speed above the target speed of the new gear. In the

Flystart device, the controlled closing of the clutch, here the second clutch K1, only in the fourth step S4, since the clutch KO has already been fully closed in the third step S3.

For the supported impulse start to exit from the recuperation phase in the P2 system, the mechanical and the kinetic energy (corresponding to the

Speed difference before and after upshifting the gears) from the pulse of the EM 2 in conjunction with the corresponding transmission parts such as the transmission input shaft and the rotating wheelsets, etc., and the available torque of the EM 2 used to start the VM 1. The VM 1 delivers by revving or towing via the controlled closing clutch KO a negative moment (drag). Thus, a supported pulse start during an upshift takes place in the highest possible gear to allow at least largely jerk-free coupling.

In order to enable a completely smooth coupling, the swing start device can be used. In this case, the flywheel 6 acts as a kind of buffer system between VM 1 and EM 2. The coupling is thus not directly via the clutch K0 and the VM 1, but via the intermediate step that the VM 1 is connected to the flywheel 6 via the separating coupling K0, and only then the coupling to the EM 2 takes place, so that the vibrations of the VM 1 are already damped. For this purpose, as a flywheel 6, a well-known DU system, ie a

Nonuniformity damper and a Drehmomentüberlagerungseinrichtung be used. By using a flywheel 6, the pulse at the start of the VM 1 can be removed from the system, so that a smooth

Coupling can be done. Furthermore, as a flywheel other systems, even not fully mechanical systems can be used.

By the proposed method, a faster connection of the VM 1 to the output for a quick implementation of driver requests on the accelerator pedal can be achieved because the VM 1 is already made available when releasing the brake pedal and not only when a request is given to accelerate. At the same time, the recuperation potentials that arise when the

Drag torque of the coupled VM 1 in Bremsrekuperationsphasen must not be overcome.

An additional advantage is that already at the P2 system by the slipping

Transmission occurs at the parallel to the upshifting disconnect clutch K0 less torque disturbance at the transmission output, so that the setting of the VM 1 for the driver is much more comfortable and less load acts on the mechanical components. In the swing start device, the jerk is completely eliminated, so that this represents an improvement to the P2 system.

Although the method for starting the VM 1 during a braking phase, i. When the vehicle is moving, it can also be used for starting from a standstill. This is analogous to the procedure described above.

Claims

claims

1 . Method for leaving a recuperation phase in one

Parallel hybrid vehicle, comprising an internal combustion engine (1) and a thus via a separating clutch (KO) in conjunction with a device for shock decoupling, comprising at least one flywheel (6) and a second clutch (K1) coupled e-machine (2), which with a with a drive train (5) connected to the transmission (3) is connectable, wherein the

Internal combustion engine (1) completely from the electric motor (2) over the

Disconnect coupling (KO) can be decoupled, wherein

- The vehicle is in a first step (S1) in a triggered by a trigger recuperation phase with predetermined Rekuperations- driving request, and

- In a second step (S2), the electric motor (2) during the

Recuperation phase is brought to an increased speed,

- In a third step (S3) by a trigger a phase to exit from the Rekuperationsphase is started, wherein

in this phase, the internal combustion engine (1) for coupling to the electric motor (2) is made available by the second clutch (K1) is opened and when this is a closing of the separating clutch (KO) takes place, so that the start of Internal combustion engine (1) is carried out as a pulse start such that an internal combustion engine to be connected (1) and

Flywheel (6) determined for connection to the transmission input

Set target speed and in parallel by means of gear upshift

the highest possible gear for connection to the drive train is set to meet a present driving request and

- In a fourth step (S4), the second clutch (K1) is closed controlled, so that the exit from the Rekuperationsphase is completed.

2. Method for getting out of a recuperation phase in one

Parallel hybrid vehicle, comprising an internal combustion engine (1) and a via a separating clutch (KO) so coupled electric motor (2) which is connectable to a with a drive train (5) connected to the transmission (3), said Internal combustion engine (1) completely from the electric motor (2) over the

Disconnect coupling (K0) can be decoupled, wherein

- In a second step (S2), the electric motor (2) during the

Recuperation phase is brought to an increased speed,

In this phase, the internal combustion engine (1) is made available for coupling to the electric motor (2), a regulated closing of the separating clutch (K0) and a setting of positive torque in the electric motor (2) takes place, so that the start of the internal combustion engine (1) as a supported pulse start such

is carried out, that one between to be connected

Combustion engine (1) and electric motor (2) for connection to the

Set transmission input determined target speed and parallel means

Gear upshift a highest possible gear to connect to the

Powertrain is set to meet a current driving request and

- In a fourth step (S4), the separating clutch (K0) is completely closed, so that the exit from the Rekuperationsphase is completed.

The method of claim 2, wherein in the third step (S3) in the phase to exit the Rekuperationsphase the controlled closing of

Disconnect coupling (K0) by bringing the separating clutch (K0) into slip.

Method according to claim 2 or 3, wherein in the fourth step (S4) the

Disconnect clutch (K0) is closed at the driving request of a thrust upshift with a coupling speed between the internal combustion engine (1) and electric motor (2) below the target speed of the new gear, and when driving request a train request with a coupling speed between the internal combustion engine (1) and E- Machine (2) is closed above the target speed of the new gear. Method according to one of claims 2 to 4, wherein in the third step (S3) for the supported pulse start, the kinetic energy from the pulse of the electric motor (2) in conjunction with participating transmission parts and the available torque of the electric motor (2) be used.

Method according to one of the preceding claims, wherein when entering the recuperation phase a gear tracking by one or more

Gear downshifts to a gear below the at least intended for the reconnection of the engine gear.

Method according to one of the preceding claims, wherein the trigger for entering the recuperation is an operation of the brake pedal and to exit the Rekuperationsphase a decrease or exiting the brake pedal, pressing the accelerator pedal or below a speed threshold.

Method according to one of the preceding claims, wherein during the recuperation phase, a gear track is performed such that the at least necessary kinetic energy of the electric motor (2) for the implementation of

Pulse start request is maintained.

Parallel hybrid vehicle comprising

- An internal combustion engine (1) and a thus via a clutch (KO) couplable electric motor (2) which is connected to a with a drive train (5) connected to the transmission (3), wherein the internal combustion engine (1) completely from the E -Machine (2) via the separating clutch (KO) is decoupled,

- At least in each case a detection, control and execution device (3, 4, 5), which are adapted to detect a trigger for entry and exit from a Rekuperationsphase to send signals to receive and process the method after one of the previous ones

Perform claims. Parallel hybrid vehicle comprising

- An internal combustion engine (1) and thus via a separating clutch (K0) in conjunction with a device for shock decoupling, comprising at least one flywheel (6) and a second clutch (K1), coupled e-machine (2), which with a with a transmission (3) connected to a drive train (5), wherein the internal combustion engine (1) can be decoupled completely from the electric motor (2) via the separating clutch (K0) in cooperation with the device for shock decoupling,

- At least in each case a detection, control and execution device (3, 4, 5), which are adapted to detect a trigger for entry and exit from a Rekuperationsphase to send signals to receive and process the method To carry out according to one of the preceding claims.