Method for operating vehicle

Abstract

The invention relates to a method for operating a vehicle (1), the vehicle (1) having:-at least one electric machine, which can be operated in an electric motor operation for driving the vehicle (1) and in a generator operation for braking the vehicle (1) in an energy recovery manner,-an energy storage unit and / or an energy sink, the energy storage unit and / or the energy sink supplies electrical energy to the at least one electric machine during operation of the electric machine and is charged by means of electrical energy recovered during operation of a generator of the at least one electric machine and / or further enables braking of the energy recovery, -an energy recuperation braking system for implementing braking of said energy recuperation, said energy recuperation braking system comprising said at least one electric machine and said energy storage unit and / or energy sink, and-a friction braking system comprising a friction braking device (2) comprising a wheel brake actuator. According to the invention, a request signal (S1, S2, S3) for a deceleration torque generated by an accelerator pedal of the vehicle (1) and / or by at least one auxiliary function of the vehicle (1) is processed in a control unit (3) that does not belong to the friction brake system, a current state (Z) of the energy recovery brake system being checked whether the energy recovery brake is permitted, and the current state (Z) of the energy recovery brake system is not permitted. And the vehicle (1) is braked in an energy recovery manner in accordance with the requested deceleration torque completely or in a range in which the current state (Z) of the energy recovery brake system permits the energy recovery braking.

Description

Technical Field

[0001] The present invention relates to a method for operating a vehicle according to the features of the preamble of claim 1. Background Art

[0002] A method for controlling a braking energy recovery device of a mild hybrid motor vehicle is known from the prior art as described in DE 10 2016 007 838 A1. The motor vehicle has a braking regulation system for braking, which includes at least one hydraulic friction brake as a first brake regulator and at least one electric motor as a second brake regulator. The electric motor can operate as a generator in order to recover the kinetic energy of the motor vehicle. The energy recovered in this way is charged into an energy storage device. The first and second brake regulators are configured to be non-mixable brakes at least during driver braking. In the method, in a first step, a theoretical wheel torque characteristic curve for providing a predeterminable theoretical wheel torque to the driveline of the motor vehicle, which includes an electric motor, is predetermined based on the instantaneous brake pedal travel. Subsequently, the theoretical wheel torque characteristic curve is varied based on a braking process carried out before the current braking process in terms of time.

[0003] A method for determining an initial slope of a braking torque slip characteristic curve from the measured braking slip of at least one vehicle wheel of a vehicle and the braking torque of energy recovery on the vehicle wheel is described in DE 10 2016 201 937 A1. In the method, the wheel speed of the braked vehicle wheel is measured and the wheel speed of the braked vehicle wheel is determined from the wheel speed. In addition, the wheel speed of an unbraked vehicle wheel of the vehicle is measured and the vehicle speed is determined from the wheel speed. The braking slip is determined from the wheel speed of the braked vehicle wheel and the vehicle speed. In addition, the braking torque of energy recovery is determined by measuring the electric power generated by energy recovery. The initial slope of the braking torque slip characteristic curve is determined from the braking torque of energy recovery and the determined slip.

[0004] A method for operating an energy recovery brake of a motor vehicle is known from DE 10 2012 222 507 A1. First, the future operating intensity of the energy recovery brake is evaluated for a forward driving section of the motor vehicle by means of the following input, which indicates the driving mode of the forward driving section. In addition, the maximum non-slip vehicle braking power for the driving section is evaluated based on the input. In addition, the braking power of the energy recovery brake is adjusted to a theoretical braking power not greater than the maximum vehicle braking power for the driving section. Finally, the energy recovery brake is operated with the theoretical braking power on the forward driving section.

[0005] A method for controlling a braking system of a motor vehicle is described in DE 10 2012 210 046 A1. The motor vehicle can be braked by means of friction brakes and an electric machine that can operate as a generator. During the braking process, the frictional braking torque to be applied by the friction brakes and the energy recovery torque to be applied by the electric machine are reduced during the braking torque reduction phase until a corrected total braking torque to be applied by the friction brakes and the electric machine is reached. The energy recovery torque to be applied by the electric machine is influenced by a first feedback loop for compensation within a second feedback loop for controlling the electric machine.

[0006] A method for determining the braking torque of a vehicle comprising a traction battery, at least one energy-recovering brake, and at least one friction brake on a drive shaft is known from DE 10 2010 054 620 A1, taking into account the vehicle state of the lateral dynamics of the vehicle. In the method, at least one braking request is determined and the total braking torque for the vehicle is determined. A first braking torque and a second braking torque of the drive shaft are determined from the total braking torque of the vehicle. In addition, the vehicle state of the lateral dynamics of the vehicle is determined. A third braking torque of the drive shaft is determined based on the first and second braking torques and the vehicle state of the lateral dynamics. In addition, a fourth braking torque of the drive shaft is determined by means of the at least one energy-recovering brake and / or the traction battery. In addition, a fifth braking torque of the drive shaft is determined by limiting the third braking torque of the drive shaft by the fourth braking torque of the drive shaft. The total braking torque of the vehicle is divided into the braking torque for the at least one energy-recovering brake of the drive shaft and the braking torque for the at least one friction brake of the drive shaft. Summary of the Invention

[0007] The object of the present invention is to provide an improved method for operating a vehicle with respect to the prior art.

[0008] According to the invention, the object is solved by a method for operating a vehicle having the features of claim 1.

[0009] Advantageous embodiments of the invention are the technical solutions of the dependent claims.

[0010] The vehicle includes: at least one electric machine, which can operate during the operation of the electric motor for driving the vehicle and during the operation of the generator for braking the vehicle for energy recovery; and an energy storage unit and / or an energy sink, which supplies electrical energy to the at least one electric machine during the operation of the electric motor and is charged by the electrical energy recovered during the operation of the generator of the at least one electric machine and / or can further enable the braking for energy recovery. The energy storage unit can also (especially in relation to the recovered electrical energy) include an energy sink or be configured as such an energy sink, or vice versa, or can especially in relation to the recovered electrical energy be provided with a combination including an energy storage unit and an energy sink. Thus, for example, it can also be stipulated that the recovered energy is not stored or is not fully stored. The energy storage unit and / or the energy sink includes, for example, at least one traction battery and / or at least one capacitor, especially a supercapacitor, and / or at least one flywheel energy storage device and / or at least one resistor, especially a large resistor, or is configured as one of these components. Thus especially when the energy sink only includes a resistor, the recovered energy is not stored but is converted into heat. However, when using the resistor, it is advantageously provided only in addition to the other components of the component. Thereby, the recovered electrical energy can be stored, and furthermore, for example, when this is not possible due to a full state of charge or other circumstances, the braking for energy recovery can be continued in such a way that the remaining recovered electrical energy is converted into heat in the resistor.

[0011] The vehicle further includes an energy recovery braking system for implementing the braking for energy recovery, and the energy recovery braking system has the at least one electric machine and the energy storage unit and / or the energy sink. The vehicle further includes a friction braking system having a friction braking device, and the friction braking device includes a wheel brake actuator.

[0012] The friction braking system is, for example, a hydraulic braking system, but can also be configured as another friction braking system. When the friction braking system is a hydraulic braking system, the friction braking device is correspondingly a hydraulic braking device, the friction brake actuator mentioned below is then a hydraulic brake actuator, the friction brake mentioned below is then a hydraulic brake, the friction brake force distribution regulation mentioned below is then a hydraulic brake force distribution regulation, the adjusted friction deceleration torque mentioned below is then an adjusted hydraulic deceleration torque, and the friction theoretical braking torque mentioned below is then a hydraulic theoretical braking torque.

[0013] According to the present invention, in a method for operating the vehicle, a request signal for a deceleration torque generated by the vehicle's accelerator pedal and / or at least one auxiliary function of the vehicle is processed in a controller that does not belong to the friction braking system, wherein it is checked whether the current state of the energy recovery braking system permits the braking by energy recovery. The controller that does not belong to the friction braking system is in particular a central controller, in particular the central controller of the (in particular electrical) powertrain of the vehicle, and the powertrain in particular includes the at least one electric machine and the energy storage unit and / or energy sink.

[0014] The current state of the energy recovery braking system is in particular the current state of the availability of the energy recovery braking system, i.e. in particular the electrical braking system formed by the vehicle's electrical powertrain. The current state of the energy recovery braking system is in particular the current state of charge of the energy storage unit or relates to the current state of charge of the energy storage unit. Thus, in particular, it is checked whether the energy storage unit can still be charged by the braking by energy recovery, and if so, how much energy generated by the braking by energy recovery the energy storage unit can still receive, or whether the energy storage unit is already fully charged. Then, the vehicle is braked by energy recovery either completely or within the range where the current state of the energy recovery braking system, in particular the energy storage unit, permits the braking by energy recovery, according to the requested deceleration torque.

[0015] Furthermore, in particular, it is provided that when the current state of the energy recovery braking system, in particular the energy storage unit, does not permit or does not fully permit the braking by energy recovery according to the requested deceleration torque, the remaining share of the requested deceleration torque that cannot be obtained by the braking by energy recovery is forwarded to the braking control system of the friction braking system and the vehicle is braked by means of the friction braking system, in particular by means of its friction braking devices, according to the remaining share of the requested deceleration torque.

[0016] An auxiliary function that can generate a request signal for a deceleration torque is, for example, a predictive speed regulation and / or a distance regulation with respect to a vehicle traveling ahead and / or an automated, highly automated or autonomous driving function of the vehicle, and the speed regulation adapts the speed of the vehicle, for example, to the lane direction ahead.

[0017] By the solution according to the present invention, in particular, the functional range of wheel stabilization during the braking by energy recovery is transferred to the controller of the electrical powertrain, in particular the powertrain controller.

[0018] Thus, by means of the solution according to the invention, the main functional scope of energy - recuperative vehicle braking (which especially relates to the deceleration torque requests of the accelerator pedal and one or more assistance systems) is shifted out of the hydraulic braking system, especially out of its brake regulation system and also out of the driving dynamics regulation device and is integrated and processed directly in the controller that does not belong to the hydraulic braking system, especially in the central controller, where energy - recuperative braking is preferably used and perhaps the remaining deceleration torque is achieved only by the friction braking system.

[0019] By means of the solution according to the invention, especially the hitherto existing signal loops are avoided. Hitherto, all deceleration torque requests of the accelerator pedal and one or more assistance systems (first detected in the controller that does not belong to the friction braking system) were transmitted by this controller to the friction braking system, especially the brake regulation system of the friction braking system and / or the driving dynamics regulation device hitherto configured to the friction braking system. From there, in turn, the corresponding share of the requested deceleration torque that should be generated by energy - recuperative braking was transmitted back to the controller that does not belong to the friction braking system. Thereby, an energy - recuperation signal loop was formed. By avoiding this energy - recuperation signal loop, especially the functions related to energy - recuperative braking can be carried out more quickly and better.

[0020] In a possible embodiment of the method, it is further provided that the request signal for deceleration torque generated by the brake pedal of the vehicle is processed in the brake regulation system of the friction braking system. Here, it is checked whether the current state of the energy - recuperative braking system, especially the energy storage unit, permits the energy - recuperative braking. The requested deceleration torque is forwarded to the controller that does not belong to the friction braking system within the range where the current state of the energy - recuperative braking system, especially the energy storage unit, permits the energy - recuperative braking and the vehicle is braked with energy recuperation accordingly. The vehicle is braked by means of the friction braking system, especially by means of its friction braking device, according to the remaining share of the requested deceleration torque. Thus, here too, energy - recuperative braking is preferred over friction braking. However, if a deceleration torque is requested by the brake pedal, it is provided that the check is made in the brake regulation system as to whether the energy recuperation is possible or not. This also has the advantage of a short signal running time, because the brake pedal is coupled to the brake regulation system and thus the request signal of the brake pedal for evaluation in the controller that does not belong to the friction braking system, especially the central controller, must first be forwarded to the brake regulation system. This is avoided in this solution, so that friction braking can also be carried out very quickly, because the signal processing for friction braking is carried out entirely in the brake regulation system, that is, the controller that does not belong to the friction braking system, especially the central controller, is not responsible for this. Therefore, a long signal running time is also avoided for this.

[0021] Thus, in the solution described herein, the hitherto existing architecture for signal detection and forwarding is maintained, i.e., the request signals for the accelerator pedal and the assistance function have hitherto also been detected by a controller that does not belong to the friction braking system, in particular the central controller, and the request signal for the brake pedal has hitherto also been detected by the brake regulation system. This is continued to be maintained. The processing of the request signal for the brake pedal in the brake regulation system is also maintained in order to avoid long signal paths. The hitherto existing transmission of the request signals for the accelerator pedal and the assistance function to the brake regulation system, which request signals result in the aforementioned signal loop, is changed, and now the signal loop is avoided.

[0022] In particular, it is provided that the controller that does not belong to the friction braking system determines the current state of the energy recovery braking system, in particular the energy storage unit, and forwards the current state to the brake regulation system. Thereby, it is ensured that the current state of the energy recovery braking system, in particular the energy storage unit, is available not only in the controller belonging to the friction braking system but also in the brake regulation system and can be used in the above-described manner.

[0023] In an alternative embodiment, the deceleration request for the brake pedal is also processed in the manner described above for the deceleration requests of the accelerator pedal and the assistance function, i.e., in particular also preferably in a controller that does not belong to the friction braking system, in particular the central controller. Thus, at this time, the request signal for the deceleration torque generated by the brake pedal of the vehicle is also processed in the controller that does not belong to the friction braking system, wherein it is checked whether the current state of the energy recovery braking system, in particular the energy storage unit, allows braking by energy recovery. At this time, the vehicle is braked by energy recovery completely or within the range where the current state of the energy recovery braking system, in particular the energy storage unit, allows braking by energy recovery according to the requested deceleration torque. In this alternative embodiment, it is then correspondingly particularly also provided that when the current state of the energy recovery braking system, in particular the energy storage unit, does not allow or does not completely allow braking by energy recovery according to the requested deceleration torque, the remaining share of the requested deceleration torque that cannot be achieved by the braking by energy recovery is forwarded to the brake regulation system of the friction braking system and the vehicle is braked by means of the friction braking system, in particular by means of its friction braking device, according to the remaining share of the requested deceleration torque.

[0024] In particular, it is provided that the controller that does not belong to the friction braking system forwards the deceleration torque for the braking by energy recovery as an electrical theoretical braking torque to the driveline controller of the electrical driveline of the vehicle including the at least one electric motor.

[0025] In particular, it is provided that the driving dynamics control device transmits the minimum drive speed for the electric machine to the driveline controller and the driveline controller performs the braking of the energy recovery by controlling the at least one electric machine in accordance with the electrical theoretical braking torque, however only until the minimum drive speed is reached. Thus, when the minimum drive speed is reached, the braking of the energy recovery, i.e., the energy recovery torque, is reduced in order to comply with the predetermined minimum drive speed. When the minimum drive speed is reached, the driveline controller transmits the remaining deceleration torque that cannot be obtained by the braking of the energy recovery to the driving dynamics control device.

[0026] In particular, it is provided that the braking control system forwards the deceleration torque for the friction braking as the friction theoretical braking torque to the friction braking device.

[0027] In addition, in particular, it is provided that the driving dynamics control device transmits the minimum wheel speed to the friction braking device and the friction braking device performs the friction braking by controlling the friction brake actuator in accordance with the friction theoretical braking torque, however only until the minimum wheel speed is reached. Thus, when the minimum wheel speed is reached, the friction braking, i.e., the friction braking torque, is reduced in order to comply with the predetermined minimum wheel speed. When the minimum wheel speed is reached, the friction braking device transmits the remaining deceleration torque that cannot be obtained by the friction braking to the driving dynamics control device.

[0028] In a possible embodiment, it is provided that the driving dynamics control device transmits the deductible electric deceleration torque, i.e., the deceleration torque that can be deducted by energy recovery by at least one electric machine at a corresponding time, to the controller that does not belong to the friction braking system, in particular the central controller and / or the braking control system of the friction braking system, for stabilizing the vehicle. Advantageously, this is taken into account correspondingly in the braking of the energy recovery and / or the friction braking, i.e., the vehicle is braked by energy recovery and / or friction braking correspondingly. The deductible electric deceleration torque is in particular the maximum possible deductible electric torque. When the deceleration request cannot be fully deducted by the braking of the energy recovery, for example, based on a smooth lane or other situations detected by the driving dynamics control device in particular, only the deductible share of the energy recovery is transmitted. This is the deductible electric deceleration torque, i.e., the deceleration torque that can be deducted by energy recovery by at least one electric machine at a corresponding time. The braking control system or the controller that does not belong to the friction braking system, in particular the central controller, thereby knows that it cannot be further provided electrically but must be provided by the friction brake for additional requirements of the brake pedal, the accelerator pedal or the auxiliary function.

[0029] In a possible embodiment, it is provided that the driving dynamics regulating device transmits the specified brake force distribution to a controller that does not belong to the friction braking system, in particular a central controller and / or the brake regulation system of the friction braking system.

[0030] The driving dynamics regulating device is, for example, separated from the friction braking system, in particular an independent unit, such as an independent controller. The driving dynamics regulating device is thus, for example, also not integrated into the controller that does not belong to the friction braking system, in particular the central controller.

[0031] By specifying a minimum drive speed by the driving dynamics regulating device, targeted brake slip regulation can be achieved based on this limit regulation of the driving dynamics by the driving dynamics regulating device using the electric powertrain of the vehicle, so that braking with energy recovery up to this limit is possible. The minimum drive speed includes, for example, a predetermined maximum slip of, for example, three percent of the wheel, and the predetermined maximum slip is not allowed to be exceeded, because otherwise there is a risk of unstable driving. So far, energy recovery has been cut off when slip occurs. In the solution described here, the energy recovery torque, i.e., the deceleration torque generated by braking with energy recovery, is only reduced when the predetermined minimum drive speed is reached or fallen below, and the energy recovery torque is re-established when the predetermined minimum drive speed is left or exceeded.

[0032] So far, the negative torque of the electric powertrain has been monitored and, if necessary, reduced in the driving dynamics regulating device. For this, it is necessary that each braking desire, i.e., each request signal for the deceleration torque, always has to pass through the driving dynamics regulating device, resulting in the energy recovery signal loop described above.

[0033] In the method described here, the deceleration torque is monitored and, if necessary, reduced directly in the powertrain controller. In particular, the electric braking desire, i.e., the energy recovery braking desire, is directly limited in the powertrain controller, so that the vehicle is no longer unstable. Thus, by means of the method, the braking desires, i.e., the deceleration torque requests, of different requestors, such as the accelerator pedal, the longitudinal adjustment assistance function, and the brake pedal, can be directly provided. The driving dynamics regulating device only specifies the minimum drive speed for the electric powertrain, i.e., for the at least one electric motor, and the minimum wheel speed for the friction braking system, so as not to exceed the maximum slip. The monitoring of the electric torque, in particular the energy recovery torque, is carried out by the electric powertrain, in particular its powertrain controller, and no longer by the driving dynamics regulating device. The monitoring of the friction braking torque is carried out by the friction braking system.

[0034] The solution can in particular achieve an increase in the availability of energy recovery. Energy recovery, i.e., braking for energy recovery, is always possible to the full extent in terms of the driving dynamics regulation device until a predetermined minimum drive speed threshold is reached. In particular, in this way, vehicle instability due to negative torque is avoided.

[0035] As already mentioned, energy recovery has so far ended completely when slipping occurs. This is achieved by setting a slip position. In the method described here, this slip position is cancelled and thus energy recovery is forcibly cut off when a predetermined slip threshold is exceeded in time. This can be achieved by specifically protecting against vehicle instability by means of stipulating and maintaining the minimum drive speed threshold, so that energy recovery can continue until this minimum drive threshold. That is, only the braking for energy recovery has to be reduced so as not to fall below the minimum drive speed, but it is not necessary to completely cut off the braking for energy recovery.

[0036] The method can in addition achieve an improvement in vehicle stability within the limits of driving dynamics, because in this way targeted slip regulation can be achieved for better protection of vehicle stability.

[0037] In addition, the method in particular improves the energy recovery efficiency in so-called one-pedal driving, i.e., when driving the vehicle only with the accelerator pedal, where the vehicle decelerates by braking for energy recovery by gradually releasing the accelerator pedal, and also improves the energy recovery efficiency even during auxiliary function braking. If the vehicle is braked only by energy recovery, in addition, there is no volume displacement of the brake fluid into the low-pressure reservoir and no brake pads are applied to the brake discs.

[0038] The method is in particular added to the signal system used so far, however, time-sensitive signals in the form of torque specifications are replaced by inertial signals, i.e., by corresponding speed specifications in the form of vehicle speed minus braking slip. This is done by means of the monitoring of the minimum wheel speed predetermined by the driving dynamics regulation device or the minimum drive speed predetermined by the driving dynamics regulation device. In addition, in the method described here, the regulation is divided among the controllers that can implement the regulation requirements most quickly. In the driveline controller, for example, the deceleration torque specification is converted into a drive speed value in a cycle of one millisecond, while the torque calculation in the driving dynamics regulation device so far was carried out in a 20 ms cycle and then had to be sent to the controller via the network.

[0039] Due to the transmission time of the theoretical torque over the network of the regulation loop: driving dynamics regulation device - central controller - driveline controller, there has so far been a delay within the regulation loop. In the method described here, the delay is outside the regulation loop, whereby a higher dynamic performance in the regulation loop is possible. Now the regulation loop is closed in the driveline controller.

[0040] In the method described herein, two coordinators for the braking desire are used, namely controllers that do not belong to the friction braking system, in particular a central controller for braking for energy recovery and a braking regulation system for friction braking. So far, everything has been coordinated jointly in the driving dynamics regulation device, which has resulted in the energy recovery signal circuit already mentioned.

[0041] In the method described herein, each braking actuator, i.e., not only the electric powertrain but also the friction braking device, has a separate actuator-side regulation, which is in particular based not only on torque but also on torque and a predetermined minimum rotational speed, i.e., the minimum drive rotational speed or the minimum wheel rotational speed.

[0042] In the method described herein, the braking pedal request, i.e., the deceleration torque requested by the braking pedal, which also causes braking for energy recovery, can also be provided electrically in the above-mentioned manner, and the acceleration pedal request, i.e., the deceleration torque requested by the acceleration pedal, which also causes friction braking, can also be provided by the friction braking system.

[0043] This can be achieved by the two coordinators mentioned above, which can exchange or coordinate the corresponding deceleration requests with each other and request the corresponding deceleration requests through the interface in the corresponding partner controller as needed.

[0044] By the method described herein, braking for energy recovery can be achieved even when slip occurs, because the stability of the vehicle is ensured by the predetermined minimum drive rotational speed.

[0045] The method can achieve two tasks that satisfy the energy recovery function, namely ensuring stability and maintaining and distributing the corresponding deceleration torque requests by distributing them to the actuators of the friction braking system and the electric powertrain.

[0046] In the method, a delay-insensitive signal in the form of rotational speed regulation is used instead of a delay-sensitive signal in the form of torque regulation. Rotational speed regulation is delay-insensitive because it is an inertial quantity that matches the current vehicle speed. Torque regulation is delay-sensitive because it has to quickly implement high torque changes (Momentenhub) and, in the previous operating mode, was additionally sent from the driving dynamics regulation device to the powertrain controller through the central controller, along with the corresponding delay times associated therewith on the bus and in the controller.

[0047] In the method described herein, a controller that does not belong to the friction braking system, especially the central controller, directly gives the desired deceleration torque command to the driveline controller. So far, in terms of the central controller, the energy recovery torque regulation has always been guided through the driving dynamics regulation device and then forwarded to the driveline controller. With the deceleration torque regulation of the controller that does not belong to the friction braking system, especially the central controller, and the minimum driving speed preset by the driving dynamics regulation device, the reduction of the energy recovery torque is now directly implemented on the driveline controller. So far, the reduction of the energy recovery torque has been carried out in the driving dynamics regulation device and then forwarded to the driveline controller through the central controller.

[0048] The described solution enables the expansion of one-pedal driving to the entire available energy recovery range. Flexible adjustment of the energy recovery level is possible. Fast torque regulation similar to the accelerator pedal movement is possible because the friction braking system is not activated, that is, for example, there is no need to use the electric brake amplifier of the friction braking system. Accordingly, the corresponding noise that may interfere is also avoided. The method can achieve the direct response characteristics of the electric driveline without unnecessary delay formation and filtering.

[0049] The method can achieve an improvement in the usability of the energy recovery braking. In addition, the method can achieve the energy recovery braking up to the limit of the driving dynamics. The method can also, for example, achieve the energy recovery braking during cornering with a high lateral acceleration and according to the braking regulation system intervention of the driving dynamics, in which the energy recovery has been cut off so far. The method can therefore achieve the energy recovery braking up to the limit of the driving dynamics even when the road surface friction coefficient is low.

[0050] The method can also achieve an improvement in the vehicle stability during the energy recovery braking.

[0051] The energy recovery braking is always possible in the full range within the limit of the driving dynamics, especially within the predetermined wheel slip. If the predetermined wheel slip is exceeded, the deceleration torque for the energy recovery braking is reduced in the driveline controller, and the deceleration torque is required to reduce the wheel slip below the predetermined slip threshold again.

[0052] The method can achieve an improvement in efficiency because braking is possible without friction brakes, especially without using an integrated device (the brake pedal and the driving dynamics regulation device are in one component) and without a decoupled braking system for one-pedal driving and auxiliary functions. In the deceleration and auxiliary functions with one pedal, there is no remaining braking pressure or no friction brakes are engaged in the system because there is no need to move the hydraulic volume.

[0053] NVH issues (noise, vibration, harshness), i.e., the noise and vibration issues of the braking system, are improved because the friction braking system is only activated when using the friction brake.

[0054] As already mentioned, the delay is minimized by the method because, instead of the time-sensitive signal in the form of torque regulation, the speed regulation in the form of the vehicle speed minus the braking slip, i.e., through the inertial signal, enables the direct transmission of the signal without the delay caused by loop formation and waiting for feedback, and the regulation is divided among the controllers that can implement the regulation requirements most quickly, as already explained above.

[0055] The method can simplify the longitudinal regulator interface because the driving torque interface for the electric braking share of the longitudinal regulator is utilized, so that the same interface is used for both the driving operation and the braking operation of energy recovery. In addition, a separate energy recovery function for the longitudinal regulator is no longer required. Description of the Drawings

[0056] The embodiments of the present invention are further described below with reference to the drawings.

[0057] In the figures:

[0058] Figure 1 A schematic diagram of the vehicle is shown. Detailed Description of the Invention

[0059] Figure 1 A schematic diagram of the braking torque coordination of energy recovery including the stability protection of vehicle 1 is shown, where, for clarity, only the components of the friction braking system and the braking system of energy recovery of vehicle 1 are shown here.

[0060] Vehicle 1 has at least one electric motor that can operate in the motor operation for driving vehicle 1 and in the generator operation for braking vehicle 1 for energy recovery. Vehicle 1 further has an energy storage unit or energy sink that supplies electrical energy to the at least one electric motor during the motor operation and is charged by the electrical energy recovered during the generator operation of the at least one electric motor or enables continued deceleration for energy recovery. Vehicle 1 further has an energy recovery braking system for implementing the braking of energy recovery, which includes the at least one electric motor and the energy storage unit and / or energy sink. Vehicle 1 further has a friction braking system including a friction braking device 2, and the friction braking device includes a wheel brake actuator.

[0061] In a method for operating the vehicle 1, it is provided that request signals S1, S2, S3 for a deceleration torque generated by the accelerator pedal of the vehicle 1 and / or by at least one auxiliary function of the vehicle 1 are processed in a controller 3, hereinafter referred to as the central controller 3, which does not belong to the friction braking system. Here, a setpoint formation 5 for manual or assisted driving is first carried out by the request signals S1, S2, S3. Subsequently, it is checked whether the current state Z of the energy recovery braking system, in particular the state of charge of the energy storage unit, permits braking by energy recovery, i.e. in particular whether the energy storage unit has a sufficient potential for receiving the recovered energy. The vehicle 1 is then braked by energy recovery either completely or to the extent that the current state Z of the energy recovery braking system, in particular the energy storage unit, permits braking by energy recovery, in accordance with the requested deceleration torque.

[0062] When the current state Z of the energy recovery braking system, in particular the energy storage unit, does not permit or does not fully permit braking by energy recovery in accordance with the requested deceleration torque, the remaining share of the requested deceleration torque that cannot be achieved by braking by energy recovery is forwarded to the braking control system 4 of the friction braking system, as shown by the arrow P1, and the vehicle 1 is braked by means of the friction braking system, in particular by means of its friction braking device 2, in accordance with this remaining share of the requested deceleration torque. Thus, this check and, if necessary, the division 6 of the requested deceleration torque in the central controller 3 are carried out.

[0063] A request signal S4 for a deceleration torque generated by the brake pedal of the vehicle 1 is processed in the braking control system 4 of the friction braking system. Here, a setpoint formation 7 for the manual brake is first carried out by the request signal S4. Subsequently, it is checked whether the current state Z of the energy recovery braking system, in particular the energy storage unit, permits braking by energy recovery. For this purpose, the central controller 3 determines the current state Z of the energy recovery braking system, in particular the energy storage unit, and forwards this current state to the braking control system 4, as shown by the arrow P2. In addition, this determined state Z of the energy recovery braking system, in particular the energy storage unit, is also used in the central controller 3 in the manner described above.

[0064] As shown by the arrow P1 configured as a double arrow, the requested deceleration torque is forwarded to the central controller 3 to the extent that the current state Z of the energy recovery braking system, in particular the energy storage unit, permits braking by energy recovery. Correspondingly, the vehicle 1 is braked by energy recovery. The vehicle 1 is braked by friction in accordance with the remaining share of the requested deceleration torque. Thus, this check and the division 8 of the requested deceleration torque in the braking control system 4 are carried out.

[0065] The share of the requested deceleration torque for braking for energy recovery, as the electrical theoretical braking torque ESM, first undergoes torque processing 9 in the central controller 3, which includes torque shaping (Momentenformung) and, if necessary, torque distribution from the perspective of efficiency and driving dynamics. The torque shaping is used to ensure the deceleration gradient so that full deceleration is not suddenly achieved. When the vehicle 1 has multiple electric motors, in particular one electric motor on the front axle and another on the rear axle, the torque distribution from the perspective of efficiency and driving dynamics is carried out. In this case, the electrical theoretical braking torque ESM can be divided among these electric motors, and this is done in particular in such a way that as efficient and / or driving-dynamics-adapted energy recovery as possible is achieved.

[0066] The deceleration torque for braking for energy recovery, and thus the electrical theoretical braking torque ESM processed in this way here, is then forwarded by the central controller 3 to the driveline controller 10 of the electrical driveline of the vehicle 1 that includes the at least one or the multiple electric motors. As schematically shown by the output arrow P3, this is then transmitted to the respective electric motor, and the respective electric motor is operated accordingly.

[0067] In order to also ensure the vehicle stability of the vehicle 1 during braking for energy recovery, in particular to avoid large slips, it is provided that the driving dynamics regulating device 11 transmits the minimum drive speed MAD for the electric motor or the respective electric motor to the driveline controller 10 and the driveline controller 10 implements the braking for energy recovery by controlling the at least one or respective electric motor in accordance with the electrical theoretical braking torque ESM, however only until the minimum drive speed MAD is reached. When the minimum drive speed MAD is reached, the driveline controller 10 transmits the remaining (i.e., regulated) electrical deceleration torque AEV that cannot be obtained by braking for energy recovery to the driving dynamics regulating device 11. The resulting maximum deductible electrical torque is notified by the driving dynamics regulating device 11 to the central controller 3 and the brake regulating system 4 as the deductible electrical deceleration torque 13.

[0068] The share of the requested deceleration torque for frictional braking, as the frictional theoretical braking torque RSM, first undergoes torque processing 12 in the brake regulating system 4, which includes torque distribution from the perspective of stability, i.e., in particular the division to the front axle and the rear axle of the vehicle 1.

[0069] The deceleration torque for frictional braking, and thus the frictional theoretical braking torque RSM processed in this way here, is then forwarded by the brake regulating system 4 to the frictional braking device 2. As schematically shown by the output arrow P4, this is then transmitted to the frictional brake actuator, and the frictional brake actuator is operated accordingly. The frictional braking device 2 additionally obtains information from the anti-lock braking system ABS of the vehicle 1.

[0070] In order to also ensure the driving stability of the vehicle 1 during frictional braking, in particular to avoid large slips, it is provided that the driving dynamics regulating device 11 of the frictional braking device 2 transmits the minimum wheel speed MRD and the frictional braking device 2 performs frictional braking by actuating the frictional braking actuator according to the frictional theoretical braking torque RSM, however only until the minimum wheel speed MRD is reached. The frictional braking device 2 transmits the remaining (i.e., adjusted) frictional braking torque ARV that cannot be achieved by frictional braking when the minimum wheel speed MRD is reached to the driving dynamics regulating device 11.

[0071] In order to stabilize the vehicle 1, the driving dynamics regulating device 11 transmits a deceleration torque 13 to the central controller 3 and the braking regulating system 4 of the frictional braking system, and the deceleration torque can be deducted by at least one electric machine in an energy-recovering manner at the corresponding time. This deceleration torque is substituted into the corresponding divisions 6, 8 of the requested deceleration torque and is thus taken into account together, whereby the vehicle 1 is braked and / or frictionally braked in an energy-recovering manner accordingly.

[0072] In the illustrated example, the driving dynamics regulating device 11 furthermore transmits an electric braking force distribution specification 14 or a frictional braking force distribution specification 15 to the central controller 3 and the braking regulating system 4 of the frictional braking system. In the illustrated example, the electric braking force distribution specification 14 is taken into account in the torque processing 9 in the central controller 3. In the illustrated example, the frictional braking force distribution specification 15 is taken into account in the torque processing 12 in the braking regulating system 4.

[0073] List of reference numerals

[0074] 1 Vehicle

[0075] 2 Frictional braking device

[0076] 3 Controller / Central controller not belonging to the frictional braking system

[0077] 4 Braking regulating system

[0078] 5 Theoretical value formation for manual or assisted driving

[0079] 6 Division of the requested deceleration torque in the central controller

[0080] 7 Theoretical value formation for manual braking

[0081] 8 Division of the requested deceleration torque in the braking regulating system

[0082] 9 Torque processing in the central controller

[0083] 10 Powertrain controller

[0084] 11 Driving dynamic adjustment device

[0085] 12 Torque processing in the braking adjustment system

[0086] 13 Deductible electric deceleration torque

[0087] 14 Electric braking force distribution regulation

[0088] 15 Frictional braking force distribution regulation

[0089] ABS Anti-lock braking system

[0090] AEV Adjusted electric deceleration torque

[0091] ARV Adjusted frictional deceleration torque

[0092] ESM Electric theoretical braking torque

[0093] RSM Frictional theoretical braking torque

[0094] MAD Minimum driving speed

[0095] MRD Minimum wheel speed

[0096] P1 Arrow

[0097] P2 Arrow

[0098] P3 Output arrow

[0099] P4 Output arrow

[0100] S1 Request signal generated by the accelerator pedal

[0101] S2 Request signal generated by the auxiliary function

[0102] S3 Request signal generated by the auxiliary function

[0103] S4 Request signal generated by the brake pedal

[0104] Z Current state of the energy recovery braking system

Claims

1. A method for operating a vehicle (1), wherein, The vehicle (1) has: - at least one electric machine, which can operate in an electric motor operation for driving the vehicle (1) and in a generator operation for braking the vehicle (1) for energy recovery, - an energy storage unit and / or an energy sink, which supplies electrical energy to the at least one electric machine during the electric motor operation and is charged by the electrical energy recovered during the generator operation of the at least one electric machine and / or enables further energy recovery braking, - an energy recovery braking system for implementing the energy recovery braking, which includes the at least one electric machine and the energy storage unit and / or the energy sink, and - a friction braking system including a friction braking device (2), which includes wheel brake actuators, characterized in that request signals (S1, S2, S3) for a deceleration torque generated by the accelerator pedal of the vehicle (1) and / or by at least one auxiliary function of the vehicle (1) are processed in a controller (3) that does not belong to the friction braking system, wherein it is checked whether the current state (Z) of the energy recovery braking system permits the energy recovery braking, and the vehicle (1) is braked for energy recovery completely or within the range in which the current state (Z) of the energy recovery braking system permits the energy recovery braking according to the requested deceleration torque.

2. The method according to claim 1, characterized in that, When the current state (Z) of the energy recovery braking system does not permit or does not completely permit energy recovery braking according to the requested deceleration torque, the remaining share of the requested deceleration torque that cannot be achieved by the energy recovery braking is forwarded to the braking control system (4) of the friction braking system, and the vehicle (1) is braked by means of the friction braking system according to this remaining share of the requested deceleration torque.

3. The method according to claim 2, wherein Request signals (S4) for a deceleration torque generated by the brake pedal of the vehicle (1) are processed in the braking control system (4) of the friction braking system, wherein it is checked whether the current state (Z) of the energy recovery braking system permits the energy recovery braking, and - the requested deceleration torque is forwarded to the controller (3) that does not belong to the friction braking system within the range in which the current state (Z) of the energy recovery braking system permits the energy recovery braking and the vehicle (1) is braked for energy recovery accordingly, and - the vehicle (1) is braked by means of the friction braking system according to the remaining share of the requested deceleration torque.

4. The method according to claim 3, characterized in that, The current state (Z) of the energy recovery braking system is determined by a controller (3) that does not belong to the friction braking system and the current state is forwarded to the braking control system (4).

5. The method according to one of the preceding claims, characterized in that, The deceleration torque for the energy recovery braking is forwarded as an electrical theoretical braking torque (ESM) by a controller (3) that does not belong to the friction braking system to a driveline controller (10) of the electric driveline of the vehicle (1) including the at least one electric machine.

6. The method according to claim 5, characterized in that, The driving dynamics adjustment device (11) transmits the minimum drive speed (MAD) for the electric machine to the driveline controller (10), and the driveline controller (10) performs the braking of the energy recovery by controlling the at least one electric machine in accordance with the electrical theoretical braking torque (ESM), however only until the minimum drive speed (MAD) is reached, wherein the driveline controller (10) transmits the remaining deceleration torque (AEV) that cannot be obtained by the braking of the energy recovery to the driving dynamics adjustment device (11) when the minimum drive speed (MAD) is reached.

7. The method according to any one of claims 2 to 6, characterized in that, The braking adjustment system (4) forwards the deceleration torque for the frictional braking as the frictional theoretical braking torque (RSM) to the frictional braking device (2).

8. The method according to claim 7, characterized in that, The driving dynamics adjustment device (11) transmits the minimum wheel speed (MRD) to the frictional braking device (2), and the frictional braking device (2) performs the frictional braking by controlling the frictional braking actuator in accordance with the frictional theoretical braking torque (RSM), however only until the minimum wheel speed (MRD) is reached, wherein the frictional braking device (2) transmits the remaining deceleration torque (ARV) that cannot be obtained by the frictional braking to the driving dynamics adjustment device (11) when the minimum wheel speed (MRD) is reached.

9. The method according to any one of claims 6 to 8, characterized in that, The driving dynamics adjustment device (11) transmits the deductible electrical deceleration torque (13) to the controller (3) that does not belong to the frictional braking system and / or the braking adjustment system (4) of the frictional braking system for stabilizing the vehicle (1), and brakes the vehicle (1) accordingly with energy recovery and / or frictional braking.

10. The method according to any one of claims 6 to 9, characterized in that, The driving dynamics adjustment device (11) transmits the braking force distribution regulations (14, 15) to the controller (3) that does not belong to the frictional braking system and / or the braking adjustment system (4) of the frictional braking system.

Images