Method for optimizing a cycle through a load change in a powertrain of a hybrid vehicle and hybrid vehicle

Abstract

The invention relates to a method for optimizing a cycle during a load change in a drive train (9) of a hybrid vehicle (1) comprising an internal combustion engine (2) and an electric motor (3), wherein - a first engine control unit (5) for controlling the internal combustion engine (2) and a second engine control unit (6) communicated with it for controlling the electric motor (3) are used, - the two engine control units (5, 6) monitor the drive train (9) for a load change and an associated gear cycle, - the two engine control units (5, 6) separately calculate a possible torque intervention to optimize the clearance when a load change is detected, - at least one of the two motor control units (5, 6) first makes a torque intervention via the electric motor (3) to optimize the game cycle, if this is possible or desired, and - if a torque intervention via the electric motor (3) is not possible or not sufficiently possible, at least one of the two motor control units (5, 6) shall perform a torque intervention via the internal combustion engine (2) for the duration of the game.

Description

[0001] The present invention relates to a method for optimizing a driving cycle, particularly with regard to comfort and dynamics, during a load change in a powertrain comprising an electric motor and an internal combustion engine by means of a torque intervention. The invention also relates to a hybrid vehicle with an internal combustion engine and an electric motor, as well as two engine control units.

[0002] From DE 10 2015 121 094 A1, a method for operating a hybrid-electric vehicle is known which coordinates the operation of an internal combustion engine, a motor, and brakes to reduce drivetrain play without delay in generating negative torque. In response to a request to transition from positive to negative torque, the internal combustion engine and the electric motor are controlled such that drivetrain torques are rapidly reduced to a lower positive value, the drive shaft torque is slowly reduced through the drivetrain play range, and then the drivetrain torque is rapidly reduced to the target value. To avoid delay, the friction brakes are applied to supply the negative torque during the transition.

[0003] Generally, during load changes, a clicking noise and an associated uncomfortable longitudinal jerking due to backlash can often occur in the drivetrain. Such backlash occurs when power is transferred from the driven wheels to the drivetrain. A gear transmission is typically located within the drivetrain. During a load change, a momentary interruption of torque can occur, for example, when two gears in a transmission, engaged with each other, rotate at different rates and opposing flanks of the gear teeth come into contact, resulting in negative engagement.

[0004] A disadvantage of methods known from the state of the art so far is that they have deficiencies in terms of efficiency and control quality.

[0005] The present invention therefore deals with the problem of providing a method for optimizing the cycle time during a load change in a drive train comprising an electric motor and an internal combustion engine by means of a torque intervention, which is improved in particular with regard to efficiency, comfort, dynamics and control quality.

[0006] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0007] The present invention is based on the general concept of optimizing the clearance cycle during a load change in a drive train comprising an electric motor and an internal combustion engine more quickly and efficiently by having two motor control units independently calculate the required torque intervention when such a load change occurs and initially apply the necessary torque intervention for clearance optimization / reduction via the electric motor. In the inventive method for optimizing the clearance cycle during a load change in a drive train comprising an electric motor and an internal combustion engine by means of a torque intervention, a first motor control unit is used to control the internal combustion engine and a second motor control unit, communicated with it, is used to control the electric motor.At least one of the engine control units (ECUs), preferably both ECUs, monitor the drivetrain for load changes and the associated backlash, particularly using appropriate sensors. If at least one of the two ECUs detects such a load change in the drivetrain, both ECUs calculate a possible torque intervention separately and thus redundantly to optimize / reduce the backlash. To optimize, and in particular reduce, the backlash, at least one of the two ECUs then first applies torque to the drivetrain via the electric motor, provided this is possible and desired. This depends, for example, on the availability and parameters of the electric motor and the combustion engine.Optimization of the gear ratio via torque intervention at the electric motor is therefore only carried out if this is possible, desired, and makes sense. If such torque intervention via the electric motor into the drivetrain is not possible, insufficient, or not desired, at least one of the two engine control units performs torque intervention via the combustion engine to optimize the gear ratio. Typically, the engine control unit that calculates the required torque intervention more quickly also carries it out completely. The major advantage of the method according to the invention is that the second engine control unit, which, for example, is a power electronics unit or is connected to one, is used to monitor and detect a load change and simultaneously to calculate a torque intervention required to optimize the gear ratio.By redundantly calculating the required torque intervention using the two motor control units, signal propagation delays can be avoided, and a higher sampling rate, control quality, and possible adjustment range of the power electronics can be used to optimize the control system. The subsequent torque intervention, initially via the electric motor, further increases the efficiency of the method according to the invention, since a significantly faster changeover of the drivetrain can be achieved via torque intervention using the power electronics at the electric motor. This significantly faster torque intervention allows the backlash occurring during a load change to be compensated for much more quickly, thereby significantly improving driving comfort and dynamics in such a vehicle.

[0008] In an advantageous further development of the method according to the invention, the engine control unit that calculates the torque intervention for optimizing / reducing the clearance more quickly performs the torque intervention. By redundantly calculating a torque intervention required during a load change to optimize the clearance, not only can the overall process be accelerated, since the faster engine control unit always performs the torque intervention, but the control quality can also be improved.

[0009] In a further advantageous embodiment, the second motor control unit includes power electronics and uses these to perform the torque intervention required during a load change to optimize the clearance cycle. The direct coupling of the second motor control unit to the power electronics allows for extremely rapid instruction to be sent to the electric motor to optimize the clearance cycle. It is understood that if the first motor control unit calculates the required torque intervention for optimizing the clearance cycle faster than the second motor control unit, the first motor control unit can control the second motor control unit and, via the second, the power electronics, thus enabling an extremely rapid response to a load change occurring in the drivetrain.By always activating the electric motor first to optimize the game cycle, the faster path can always be used.

[0010] In a particularly advantageous embodiment of the inventive method, the second motor control unit takes parameters of the electric motor into account when calculating the torque engagement to optimize the backlash. Such parameters can be, for example, the speed of the electric motor, an operating temperature, or similar factors. In particular, parameters that can be considered include the state of the disengaging clutch, a differential speed, a relative backlash, an adapted free play, a transmission input speed, a drivetrain tension, and / or a driver-requested torque / gradient.

[0011] In a particularly preferred embodiment of the method, the second engine control unit takes into account the availability of the electric motor for torque intervention to optimize clearance. Additionally or alternatively, the first engine control unit can take into account the availability of the internal combustion engine for torque intervention to optimize clearance. The availability of the electric motor can be determined, for example, via an available absolute battery charging / discharging current, a difference between charging and discharging current, and / or the absence of signal errors.

[0012] In a further advantageous embodiment, the first or second engine control unit takes into account a driver-requested torque. Such consideration can be achieved, for example, by the engine control unit that performs the torque intervention required to optimize the gear ratio. A driver-requested torque can be taken into account, for example, by a commanded over-compression of the (transmission) clutch or by a slowing down of the driver-requested torque's implementation.

[0013] The present invention is further based on the general concept of providing a hybrid vehicle with a powertrain comprising an electric motor and an internal combustion engine, which also includes a first engine control unit for controlling the internal combustion engine and a second engine control unit communicated therewith for controlling the electric motor, wherein the two engine control units are configured to carry out the method described in the preceding paragraphs. With the hybrid vehicle according to the invention and the redundant monitoring for detecting a game cycle, i.e.,In the case of a powertrain replacement, as well as the optimal selection of the electric motor or the combustion engine for optimizing the gear ratio, particularly rapid optimization of the gear ratio can be achieved through a corresponding torque intervention. By redundantly calculating the required torque intervention, signal propagation delays are avoided by the two engine control units, and a higher sampling rate of the power electronics can be used to optimize the control. Overall, the hybrid vehicle according to the invention can thus significantly increase driving comfort and dynamics for the user.

[0014] Further important features and advantages of the invention will become apparent from the dependent claims, the drawing and the associated description of the figures based on the drawing.

[0015] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention as defined by the claims. Components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or be integral areas or sections of this unit, even if this is depicted differently in the drawing.

[0016] A preferred embodiment of the invention is shown in the drawing and is explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0017] The onlyFig. Figure 1 shows a hybrid vehicle according to the invention.

[0018] According to the Fig. In the invention, a hybrid vehicle 1 comprises an internal combustion engine 2 and an electric motor 3, which can act alternatively or cumulatively on at least two driven wheels 4. The internal combustion engine 2 and the electric motor 3, as well as the driven wheels 4, are integrated into a drive train 9. A first engine control unit 5 for controlling the internal combustion engine 2 and a second engine control unit 6, communicated with it, for controlling the electric motor 3 are also provided. The second engine control unit 6 has power electronics 7 or, as is shown in the invention, is a power electronics unit 7. Fig. Figure 1 shows a connection to such a system. The power electronics 7 are arranged between the electric motor 3 and a vehicle battery 8.

[0019] Generally, the combustion engine 2 and / or the electric motor 3 generates drive power via the drivetrain 9, which is transmitted to the driven wheels 4. Under certain conditions, however, power flows in the opposite direction through the drivetrain 9, which can lead to a momentary interruption of torque. This occurs, for example, when a shaft rotates in such a way that opposing flanks of gear teeth in an unspecified transmission come into contact with each other, a phenomenon commonly referred to as backlash. During this backlash, energy can accumulate in the drivetrain 9, leading to a clicking sound or a longitudinal jerk in the hybrid vehicle 1, both of which are perceived as unpleasant.

[0020] To optimize this clearance cycle during a load change, a method according to the invention is employed in which at least one of the two motor control units 5, 6 monitors the drive train 9 for a load change and the associated clearance cycle. Upon detecting a load change, the two motor control units 5, 6 calculate the necessary torque intervention for optimizing the clearance cycle separately and thus redundantly. At least one of the two motor control units 5, 6, typically the one that calculates the torque intervention for optimizing / reducing the clearance cycle more quickly, first applies the calculated torque intervention to the drive train 9 via the electric motor 3, provided this is possible. If this is not possible or not sufficiently possible, or if the motor control unit 5, 6 calculates the torque intervention more quickly, the motor control unit 5, 6 applies the calculated torque intervention to the drive train 9 via the electric motor 3, provided this is possible.If this is not desired, at least one of the two engine control units 5, 6, typically the one that calculates the required torque intervention for optimizing / reducing the clearance cycle more quickly, applies a torque intervention via the combustion engine 2. Through the redundant monitoring and recording of a load change and the associated clearance cycle, as well as the redundant calculation of the torque intervention required to optimize the clearance cycle, signal propagation delays can be avoided, and a higher sampling rate of the power electronics 7 can be used to optimize the control. This significantly increases efficiency, control quality, and thus driving comfort and dynamics for a user of the hybrid vehicle 1.

[0021] Generally, the engine control unit 5, 6 that performs the torque intervention required to optimize / reduce the clearance during a load change carries this out to completion. The option to switch interventions is available.

[0022] The second engine control unit 6 is, according to the Fig.1 is connected to the power electronics 7 and, via these, to the electric motor 3, enabling particularly rapid torque response during load changes. The second motor control unit 6 can additionally consider parameters of the electric motor 3 when calculating the required torque response to optimize the backlash, such parameters being, for example, the speed of the electric motor 3 or its general availability. The first motor control unit 5 can similarly consider parameters of the internal combustion engine 2 for torque response to optimize backlash, as well as, for example, the availability of the internal combustion engine 2.At least one of the following parameters can be considered: driver request gradient, minimum / maximum engine speed, power transmission, individual wheel speeds, gears, speed gradients, slip at the drive clutch, driving program, relative free play, adapted free play, change of mind detection, vehicle speed, clutch status, shift sequence, accelerator pedal position, modeled target speed (reference speed), VC start / stop status, coasting status, speed controller intervention, diagnostics, signal errors, engine temperature or transmission sump temperature, battery limits, ESP / MSR / ASR intervention and brake status, as well as the transverse locking status of the disconnect clutch, differential speed.

[0023] Furthermore, the first engine control unit 5 or the second engine control unit 6 can also take into account a driver-requested torque, which is specified via an accelerator pedal 10, in particular an accelerator pedal or a brake pedal. The engine control unit 5, 6 that performs the torque intervention required to optimize the clutch engagement then also takes into account the driver-requested torque, in particular a commanded over-compression of the clutch / transmission clutch or a deceleration of the driver-requested torque.

[0024] All in all, with the hybrid vehicle 1 according to the invention and the inventive method, which, for the optimization of the clearance during a load change in a drive train 9, causes the redundant calculation of the required torque intervention via both engine control units 5, 6, a significantly faster optimization of the clearance and thus a significantly more comfortable driving experience can be achieved. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2015 121 094 A1

[0002]

Claims

[1] Method for optimising a play run during a load change in a drive train (9) of a hybrid vehicle (1) comprising an internal combustion engine (2) and an electric motor (3), in which - a first engine control unit (5) is used to control the internal combustion engine (2) and a second engine control unit (6) communicating therewith is used to control the electric motor (3), - the two engine control units (5, 6) monitor the drive train (9) for a load change and the associated play, - the two engine control units (5, 6) separately calculate a possible torque intervention to optimise the clearance when a load change is detected, - at least one of the two engine control units (5, 6) initially carries out a torque intervention via the electric motor (3) to optimise the play, if this is possible and desired, and - if a torque intervention via the electric motor (3) is not possible or not sufficiently possible or not desired, at least one of the two engine control units (5, 6) carries out a torque intervention via the combustion engine (2) in order to optimise the play run. [2] Method according to claim 1, characterized by that the engine control unit (5, 6) which calculates the torque intervention more quickly to optimize the play cycle carries out the torque intervention. [3] Method according to claim 1 or 2, characterized by that the second engine control unit (6) has or is connected to power electronics (7) and uses these to implement the torque intervention via the electric motor (3). [4] Method according to claim 1, characterized by that the second engine control unit (6) takes into account parameters of the electric motor (3) when calculating the torque intervention in order to optimize the play run. [5] Method according to one of the preceding claims, characterized by that the first engine control unit (5) takes into account the availability of the combustion engine (2) for a torque intervention to optimize play. [6] Method according to one of the preceding claims, characterized by that the second engine control unit (6) takes into account the availability of the electric motor (3) for a torque intervention to optimize play. [7] Method according to one of the preceding claims, characterized by that the first engine control unit (5) or the second engine control unit (6) takes into account a driver's desired torque. [8] Method according to claim 7, characterized by that the engine control unit (5, 6) which carries out the torque intervention required to optimise the play through takes into account the driver's desired torque with a commanded over-pressing of a drive clutch or a slowing down of the driver's desired torque. [9] Hybrid vehicle (1), - with a drive train (9) comprising an internal combustion engine (2) and an electric motor (3), - with a first engine control unit (5) for controlling the internal combustion engine (2) and a second engine control unit (6) communicating therewith for controlling the electric motor (3), wherein the two engine control units (5, 6) are designed to carry out the method according to one of the preceding claims. [10] Hybrid vehicle (1) according to claim 9, characterized by that the second engine control unit (6) has or is connected to power electronics (7).

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