DE102021207066A1 - Method for operating a braking device for a vehicle and braking device for a vehicle - Google Patents

Abstract

The present invention provides a method for operating a braking device (10) for a vehicle (F), which can be connected to a driving stabilization system (ESP), comprising recognizing (S1a) a need to trigger a braking process and/or receiving (S1b) a command to generate a braking force on the braking device (10) from a user via a brake pedal (PE) of the braking device (10); Generating (S2) a braking force on a braking unit of the braking device (10) as a function of a pedal force received via the brake pedal, with an amplification (S3) or reduction (S4) of a pedal resistance force being effected by a brake amplification device (BE) and thereby the pedal resistance force a current braking mode is adjusted.

Description

The present invention relates to a method for operating a braking device for a vehicle and a braking device for a vehicle.

State of the art

Conventional vehicles include a brake system with a brake master cylinder in which a force can be generated and passed on to a brake unit. A brake booster can also be used to generate an amplification of that force for the brake unit that the driver generates himself on a brake pedal. The brake system can be operated via hydraulic pressure, in which case the hydraulic pressure generated can then also exert a reverse force as a resistance force on the pedal. In this way, a driver can be given the feeling of the effort exerted on the brake system. This drag force can be altered by using the brake booster as it can generate a portion of the drag force. In the case of electric vehicles, there can be an additional influence if the vehicle is operated in a recuperation mode.

In the WO 2013/083243 A1 a drive train of an all-wheel drive vehicle is described, with a first axle and a second axle and two electrical machines, each machine driving one of the axle halves.

Disclosure of Invention

The present invention provides a method of operating a braking device for a vehicle according to claim 1 and a braking device for a vehicle according to claim 10.

Preferred developments are the subject of the dependent claims.

Advantages of the Invention

The idea on which the present invention is based is to specify a method for operating a braking device for a vehicle and a braking device for a vehicle, wherein when using a brake boosting device, a resistance force can be passed on to a brake pedal during a braking process with more precise situation and this more precisely to current Pressure ratios in the brake system can be adjusted to give the driver a more realistic brake feel via pedal resistance.

According to the invention, in the method for operating a braking device for a vehicle, which can be connected to a driving stabilization system, a need to trigger a braking process and/or a command to generate a braking force on the braking device is recognized by a user via a brake pedal of the braking device; generating a braking force at a braking unit of the braking device as a function of a pedal force received via the brake pedal, wherein a pedal resistance force is increased or reduced by a brake boosting device and the pedal resistance force is thereby adapted to a current braking mode of operation.

The braking device can advantageously be installed in a vehicle with an electric machine. The driving stabilization system can be, for example, an electronic stability system (ESP) for traction control. The brake unit can be any known type of brake on one or more wheels and/or axles. The pedal force can correspond to the force that the driver applies to the pedal. This force can be amplified and passed on to a hydraulic system of the braking device for the braking unit. A force resistance can be generated in the brake line to the rear of the brake unit, which can give the driver a feeling of the braking conditions. The feedback between the brake pedal and the brake unit can advantageously be better adapted to the force communication between the brake pedal and the brake unit, and the reproduction and generation of the realistic braking resistance on the brake pedal, in other words the pedal resistance force, can be improved and generated more realistically. This can be particularly beneficial when the vehicle is being operated in a regenerative braking mode, which can modify brake feel from feedback from the hydraulic braking system.

In general, the following relation can be established for force feedback: $$\text{pedal drag force}=\text{hydraulic power}+\text{spring force}-\text{additional power}.$$

Here, the hydraulic force corresponds to a force that is generated by hydraulic pressure, and this pressure is multiplied by a piston area of the master brake cylinder. The spring force embodies a sum of forces on spring components, for example one or more springs in a master brake cylinder and one or more springs in the brake booster device, which can serve as return springs to an initial position. The additional force corresponds to a force generated by the brake boosting device. In this case, a reduction in hydraulic force can result in a reduction in pedal resistance force.

The reduction of a pedal resistance force and thus a modification of the brake feel on the brake pedal can be influenced by controlling and adjusting the operation of the brake boosting device accordingly. In this way, the reduction in pedal (resistance) force and its transmission can be compensated.

The additional force can be influenced indirectly, for example by adjusting a manipulated variable of the brake boosting device (DRR offset, driver request recognition offset value).

By setting a so-called “DRR offset”, ie a differential travel in the brake boosting device, an associated controlled variable can be adapted, advantageously in such a way that a desired force component can be generated by it. In the event that a mechanical reinforcement is not adapted via software, a differential travel of 0 mm can advantageously always be corrected. By adding such an offset (“DRR offset”), the amplification in the brake amplification device can be adjusted using software. The brake boosting device can either boost more (DRR offset > 0 mm) or boost less (DRR offset < 0 mm) compared to the purely mechanical boost/force effect.

The differential travel can relate to a difference between the stroke of the input rod and the stroke of the piston.

This correction (adjustment of the resistance force) can depend on a current system pressure (in the master brake cylinder at the current time) on the braking device, for example on the respective operating point of the braking device, which can be described with a virtual system pressure.

There may be a stroke pressure characteristic of the presently installed brake components/brake system and it may be predetermined.

The stroke is the measured stroke of the rod (connecting rod) and the pressure is the pressure measured at the master brake cylinder. In the case of volume blending, the virtual pressure results from this stroke-pressure characteristic and the stroke by the brake boosting device. Without the volume blending, the virtual pressure is equal to the pressure measured at the master cylinder.

A virtual system pressure can be an estimated quantity, which can correspond to the currently prevailing conditions in the system from calculations or estimates. This estimate may vary from an actual size or be within a tolerance range of that size. The estimated variable for the virtual system pressure can be assigned to a specific and ascertained pedal position for which the typically prevailing system pressure is known, but which can actually also deviate from the typical value in modified operation, for example in recuperative partial operation.

There can therefore be a difference between the virtual size and the actual size. A volume modification (volume hiding) can occur in the braking device system, which can modify the actual pressure in the system. The virtual system pressure can then correspond to an estimated pressure at the brake device, with the effect of the volume modification not necessarily having to be taken into account, with a hydraulic brake model being able to be used, for example.

The volume modification may be a volume that can be shifted (or reduced) into an accumulator unit to thereby reduce hydraulic torque gladly and instead to enable or increase regenerative torque. The greater the regenerative torque, the more volume is shifted into the accumulator unit.

The accumulator unit can be a storage chamber for hydraulic fluid in the hydraulic unit of the brake system.

This correction or modification can also depend on a further correcting or comparison variable (jumpln).

This correcting or comparison variable (JumpIn pressure) can correspond to a reference pressure in the brake boosting device at which the driver comes into contact with the hydraulic system or the pressure level as resistance at the pedal corresponds to that of the hydraulic pressure. Before this reference pressure (this value is reached), the driver has no direct connection to the hydraulics and the driver force/pedal force only corresponds to the preload of the spring force, which must be overcome in order to actuate the pedal (cut-in spring).

Instead of a current pressure, a target pressure to be achieved in the system can be calculated. The target pressure, for example in the master brake cylinder, can be a desired pressure that can occur on the brake device and/or on the brake pedal with a corresponding pedal resistance force that is adapted to the mode of operation. In order to obtain a force-displacement characteristic, i.e. a respective force on the brake unit and a corresponding feedback and pedal resistance force, it may be necessary to adjust a position of an actuator before an intermediate section (intermediate operation) is terminated, for example below the Jumpln value. The actuator (boost body or valve body) can be an actuator device, which can be used to designate a part of the brake booster device that is driven translationally by the motor and that, in addition to the input rod, can be responsible for the pressure build-up.

A limit in the compensation below a Jumpln value (specified and known by user specifications) can be defined at an originally set gap value. This can involve compensating for the pedal (resistance) force, which can be influenced by mixing the torques (from the motor, the electric machine or the brake booster device) (torque blending). The gap value (GapLap) is the initial distance between the input rod (plunger plate) and the reaction disc. Depending on how large this distance is initially, the jump-in point (pressure at which the driver comes into force coupling with the hydraulics) comes sooner or later.

The desired Jumpln value can be predetermined by the user. One goal can be to compensate for a lack of deformation of a reaction disk by volume blending. When the user requests braking, he presses the pedal and pushes a volume from the master brake cylinder to the wheels (their brake assemblies). In the case of purely regenerative braking, the driver must press/compensate for this part of the volume in the accumulator unit in order to prevent hydraulic braking torque. With a reduction in regenerative torque, the volume for the accumulator unit can be pushed back to the wheels to increase hydraulic braking torque. This is volume blending. Usually, the reaction disc can be deformed by the pressure of the master cylinder, and at a jump pressure (jump-in), the reaction disc can touch the input rod by a deformation. With volume blending, master cylinder pressure is not increased due to regenerative braking, thereby reducing or eliminating reaction disk deformation. Therefore, the brake booster can generate force blending to generate this deformation.

If the driver operates the braking device until a defined end or at JumpIn is reached, a proportion of the compensation can be calculated based on a current pressure or on the target pressure. The end of the Jumpln indicates the case where the output rod contacts the reaction disk so that the user/driver can feel a counter force (component) from the pressure in the master cylinder. In conventional vehicles, the end of the Jumpln corresponds to the situation when the pressure in the brake master cylinder reaches the Jumpln pressure. Without braking (torque) torque mixing, the end of the Jumpln is where the virtual pressure reaches the Jumpln pressure.

It can be assumed that a deformation of the reaction disc can be linear. The signals of the pressure values can be limited by a maximum of the desired JumpIn.

P_JI can be a desired jumping pressure, PFA_offset (P_JI) is a DRR offset (displacement) at desired jumping pressure, a_preJumpln is a PFC
(Pedal (resistance) force compensation) factor, which can guarantee or increase the likelihood of constant JI with volume blending.

The driver can press the brake pedal when braking and push a volume from the master cylinder to the wheels.
In purely regenerative braking, the volume pushed by the driver can be pushed into the accumulator unit to prevent hydraulic torque.

If the regenerative torque is reduced, the volume for the accumulator unit can be pushed back to the wheels to increase the hydraulic torque, which can be referred to as volume blending.

There may be an initial gap lap between the output rod and the reaction disc, in which case the master cylinder would have no effect on pedal force. When the pressure in the master cylinder increases, the reaction disc can be deformed, and above a certain pressure the reaction disc can then touch the output rod, which can correspond to the jump pressure (jump-in) P_JI.

$$\text{a}\_\text{preJumpIn}=\left(-\text{initial gap lap}-\text{PFA}\_\text{Offset}\left(\text{P}\_\text{JI}\right)\right)\text{/}\left(\text{P}\_\text{JI}\right)$$

A calculation can be made according to which $$-\text{Initial gap lap}=\text{P}\_\text{JI}*\text{a}\_\text{preJumpIn}+\text{PFA}\_\text{offset}\left(\text{P}\_\text{JI}\right),\text{and}$$

$$\text{a}\_\text{preJumpIn}=\left(-\text{initial gap lap}-\text{PFA}\_\text{offset}\left(\text{P}\_\text{JI}\right)\right)\text{/}\left(\text{P}\_\text{JI}\right)$$

The compensation fraction without any pressure (PFC_Offset_virtual) can be calculated as a sum of a fraction before Jumpln and a fraction after Jumpln.

During recuperative braking in an ESP system in combination with the brake boosting device, the pressure in the entire brake system and at the wheels is reduced by the brake volume displaced by the brake boosting device being held in a storage chamber for a specific time. If the driver is force-coupled to the hydraulics, i.e. above the jump-in point, this drop in pressure in the brake system can be felt directly by the driver as a pedal is applied. In order to prevent this, the brake boosting device can reduce a boost equivalent to the pressure drop and thus compensate for the reduced counterforce (no or only little pressure). $$\begin{array}{l}\text{PFC}\_\text{offset}\_\text{virtual}=\text{pMcVirtual}.\text{at least}\left(\text{P}\_\text{JI}\right)*\text{a}\_\text{preJumpIn}+(\text{pMcVirtual}-\\ \text{P}\_\text{JI}).\text{Max}\left(0.0\right)*\text{a}\_\text{postJumpIn})\end{array}$$

The term max(0.0) means that the calculated value is never less than 0.0, e.g. Y=(pMcVirtual - P_JI).max(0.0), Y>=0.

• Wenn pMcVirtual kleiner als P_JI ist, dann ist pMcVirtual.min(P_JI) = pMcVirtual.
• Wenn pMcVirtual (als Druck am Hauptbremszylinder) größer als P_JI ist, dann ist pMcVirtual.min(P_JI) = P_JI.

Concerning the minimum of the pMcVirtual:

• If pMcVirtual is less than P_JI, then pMcVirtual.min(P_JI) = pMcVirtual.
• If pMcVirtual (as pressure at the master brake cylinder) is greater than P_JI, then pMcVirtual.min(P_JI) = P_JI.

That means the factor a_preJumpln is only used for the part of pMcVitual below JI. The factor for converting pressure to PFC_Offset is not equal between below and above JI.

• Wenn pMcVirtual kleiner als P_JI ist, dann (pMcVirtual - P_JI).max(0.0) = 0.0. In diesem Fall hat der Faktor, a_postJumpln keinen Einfluss auf die Berechnung von PFC_OffSet_Virtual.

Concerning a maximum of the difference (pMcVirtual - P_JI):

• If pMcVirtual is less than P_JI, then (pMcVirtual - P_JI).max(0.0) = 0.0. In this case the factor a_postJumpln has no influence on the calculation of PFC_OffSet_Virtual.

The compensation factor for the actual pressure (a_actual_calc) can depend on an operating point, where $$\text{a}\_\text{actually}\_\text{calculate}=\text{PFC}\_\text{offset}\_\text{virtual/pMcVirtual}.$$

It should be mentioned here that pMcVirtual is a theoretical (master brake) cylinder pressure at the current working point without recuperation, P_JI is the Jumpln pressure (reference pressure when the driver comes into force coupling with the hydraulic system), a_pre_Jumpln is a factor in [mm/bar], which depends on the hardware of the brake booster device determines how many mm per bar differential pressure the actuator in the brake booster device has to retract to compensate for the reduced bulging/deformation of the reaction disk.
pMcVirtual - P_Jl is thus a theoretical difference between the operating point and Jumpln pressure.
a_postJumpln is a factor in [mm/bar] which, depending on the hardware of the brake booster, determines how many mm per bar of differential pressure the actuator in the brake booster has to move back to compensate for the loss of back pressure.
PFC_Offset_virtual is a theoretical DRR offset (manipulated variable) which would have to be adjusted by the brake booster device if there were fully recuperative braking (with 0 bar counterforce in the brake power cylinder). Furthermore, a_actual_calc can be a resulting factor in [mm/bar] as a combination of the two factors a_pre_Jumpln and a_post_Jumpln the current working point (theoretical pressure in the brake power cylinder as pMcvirtual).

The portion of the current pressure can also remain uncompensated by the force compensation and PFC_Offset_actual = P_actual * a_actual_calc.

P_actual is the pressure in the master cylinder, which can be measured with a pressure sensor in the ESP. Due to a CAN delay, the value for P_actual may be delayed, for example 40ms.

The variation of the compensation for the pedal (resistance) force can be a difference between a virtual and an actual compensation difference, $$\text{PFC}\_\text{TargetPositionOffset}=\text{PFC}\_\text{offset}\_\text{virtual}-\text{PFC}\_\text{offset}\_\text{actually}$$

PFC_TargetPositionOffset can be a variable that can result from the difference between PFC_Offset virtual (theoretical manipulated variable with full recuperation, i.e. back pressure of 0 bar) and PFC_Offset_actual (manipulated variable which does not have to be compensated because there is still residual pressure (P_actual) in the system )

The additional force can be proportional to the PFC_TargetPositionOffset.

If the pressure at the master cylinder is less than pMcVitualStrokeBased (which can be a virtual pressure which can be calculated from an original/actual stroke pressure (shock or rod pressure) minus pressure characteristics and the input rod stroke, given by the brake booster device), then PFC_TargetPositionOffset can become negative and the additional force of the brake booster device can be reduced, which can result in an increase in the pedal (resistance) force for the driver.

According to a preferred embodiment of the method, the braking mode at least partially controls and carries out recuperation on an electrical machine.

According to a preferred embodiment of the method, a braking impression, which corresponds to a current braking situation, is simulated for the driver by the pedal resistance force.

According to a preferred embodiment of the method, a control signal delay between the driving stabilization system and the brake boosting device is taken into account and compensated for in order to generate the braking force and/or to increase or decrease the pedal resistance force.

According to a preferred embodiment of the method, the brake boosting device compensates for a pedal force that results from a difference between a pressure in a master brake cylinder of the braking device and a determined pedal pressure that is triggered by a user.

Here, the pedal force can also correspond to a pedal resistance force.

According to a preferred embodiment of the method, the brake boosting device reduces brake support during recuperative braking and adjusts the pedal resistance force to purely hydraulic braking on the braking device.

According to a preferred embodiment of the method, a dynamic pressure is determined at the beginning of a recuperative braking mode and taken into account when generating the pedal resistance force if the dynamic pressure exceeds a predetermined maximum value.

The dynamic pressure results from throttling effects on the inlet and outlet cylinders. The dynamic pressure can therefore be a dynamic pressure in the master cylinder. Due to throttling effects in the intake valve and exhaust valve, it is possible that the entire volume is not shifted from the master cylinder into the storage chamber. This builds up pressure in the master cylinder.

According to a preferred embodiment of the method, an approximate pressure at the master brake cylinder is determined by measuring a comparison current in the brake booster device and drawing conclusions about the approximate pressure at the master brake cylinder from this.

According to a preferred embodiment of the method, a rotor position sensor of an electric motor, with which the brake boosting device is operated, is read and the phase currents of the electric motor are determined, and from this a motor current of the brake boosting device is determined as a comparison current, from which a torque of the motor of the brake boosting device is subsequently determined is, from which the approximate pressure at the master brake cylinder is then determined.

A stagnation pressure in the main brake cylinder can be generated by throttling effects on an input piston and output piston in the ESP. In the case of a quick pedal actuation, the entire volume is not moved into the accumulator unit by the driver. Therefore, stagnation pressure may be generated in the master cylinder.

This stagnation pressure can be high when there is rapid pedal application, which can result from a high volume flow from the driver and also due to a low temperature and therefore high viscosity of the brake fluid. The pressure on the master cylinder can be much higher than the virtual pressure for a short time.

Therefore, the pedal force, felt for the driver or on the braking device, can be much greater than usual, i.e. with a conventional braking system.

In order to reduce the pedal force that can be generated by the stagnation pressure, force superimposition can be used with the brake booster device, which can be based on the pressure at the master brake cylinder. $$\text{PFC}\_\text{offset}\_\text{actually}=\text{P}\_\text{MC}*\text{a}\_\text{actually}\_\text{calculate}$$

P_MC is the pressure at the master brake cylinder, PFC-Offset_actual is an "actual manipulated variable". This does not need to be compensated if there is still pressure in the system.

Due to a control signal delay between the driving stabilization system and the brake booster device of around 20-40ms, the signal relating to the pressure at the master brake cylinder can already be 20-40ms old, with the driving stabilization system being able to send this signal to the brake booster device. If the pedal is actuated quickly, the gradient of the pressure at the main brake cylinder can rise to, for example, 500 bar/s. The control signal delay can already amount to/create a deviation of 10 to 20 bar.

The compensation can be combined with already known compensation approaches for the pedal resistance force.

For this purpose, an application can be expanded in such a way that a PFC+ function can also be used.

In addition to the PFC and PFC+, a dynamic pressure can also be compensated at its peak values at the beginning of a recuperative phase. In order to reduce or rule out an influence of the control signal delay of the pressure signal, a pressure at the master brake cylinder can be estimated, i.e. approximated, which can be based on a motor current of the brake boosting device, so that an error from the control signal delay can be reduced or prevented. Then a pedal (resistance) force can be comparable and similar to that from a conventional brake system, i.e. without stagnation pressure or without the so-called (torque blending) torque blending, which can then correspond to pedal behavior as with purely hydraulic braking. Said motor can be a (servo)motor of the brake boosting device.

A PFC can increase pedal force when reducing force from the brake booster device. With PFC+ this can be reversed.

The pedal force can be adapted depending on a pressure difference between pMC and p_virtual, where the adaptation can be an increase or a decrease.

According to the invention, the braking device for a vehicle, which can be connected to a driving stabilization system, comprises a brake boosting device; a control device which is set up to recognize a need to trigger a braking process and/or to receive a command for generating a braking force at the braking device from a user via a brake pedal of the braking device; a braking unit; a brake pedal, wherein the control device and the brake unit can be operated together and are set up to generate a braking force on the brake unit as a function of a pedal force received via the brake pedal, wherein a pedal resistance force can be generated or changed by the brake boosting device in order to thereby transmit the pedal resistance force to a adapt the current braking mode.

The method is also characterized by the features and advantages mentioned in connection with the braking device and vice versa.

Further features and advantages of embodiments of the invention result from the following description with reference to the attached drawings.

character list

The present invention is explained in more detail below with reference to the exemplary embodiments given in the schematic figures of the drawing.

• 1 eine Blockdarstellung von Verfahrensschritten des Verfahrens zum Betreiben einer Bremseinrichtung für ein Fahrzeug gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;
• 2 einen Bremsprozess an einer Bremseinrichtung mit einem Fahrstabilisationssystem und einer Bremsverstärkungseinrichtung nach einem Vergleichsbeispiel;
• 3 einen Druckverlauf an einem Hauptbremszylinder und eine Näherung zu diesem in einem Verfahren gemäß eines Ausführungsbeispiels der vorliegenden Erfindung;
• 4 einen Bremsprozess an einer Bremseinrichtung mit einem Fahrstabilisationssystem und einer Bremsverstärkungseinrichtung gemäß eines Ausführungsbeispiels der vorliegenden Erfindung.

Show it:

• 1 a block diagram of method steps of the method for operating a braking device for a vehicle according to an embodiment of the present invention;
• 2 a braking process on a braking device with a driving stabilization system and a brake boosting device according to a comparative example;
• 3 a pressure curve on a master brake cylinder and an approximation to this in a method according to an embodiment of the present invention;
• 4 a braking process on a braking device with a driving stabilization system and a brake boosting device according to an exemplary embodiment of the present invention.

In the figures, the same reference symbols denote the same elements or elements with the same function.

1 shows a block diagram of method steps of the method for operating a braking device for a vehicle according to an embodiment of the present invention.

In the method for operating a braking device for a vehicle, a need for triggering a braking process is recognized S1a and/or a command for generating a braking force on the braking device is received S1b from a user via a brake pedal of the braking device; generating S2 a braking force at a brake unit of the braking device as a function of a pedal force received via the brake pedal, with an increase S3 or reduction S4 of a Pedal resistance force is carried out by a brake boosting device and thereby the pedal resistance force is adapted to a current braking mode.

2 shows a braking process on a braking device with a driving stabilization system and a brake boosting device according to a comparative example.

The curves PF-orig and PF-fluct are shown in the drawing above. The PF-orig is a pedal (resistance) force with purely hydraulic brakes. The PF-fluct is a current pedal (resistance) force that the driver feels.

In the drawing in the middle, a pMC-esp is shown as a measured pressure at the main brake cylinder in the ESP, which can be equal to the real and current pressure in the main brake cylinder.

The pMC verse is a measured pressure at the master cylinder that the brake booster device can obtain from the ESP. Here, CAN can be observed as a shift in time.

The compensation PFC can be based on the delayed signal of the pMC. The brake boosting device (gradient of the pMC x signal delay) can compensate the pedal (resistance) force by the pressure fluctuation too much or too little.

With a positive gradient of the pMC, the brake boosting device can reduce the pedal (resistance) force too little or even increase the pedal (resistance) force. In the case of a negative gradient, the brake boosting device can increase the pedal (resistance) force too little or even reduce it.

This can cause a hard pedal (feel) such as at the beginning of braking and a sudden drop in pedal feel shortly thereafter.

The PFC act in the drawing below is a PFC offset due to the late CAN difference.

PFC-corr can be a corrected PFC offset in order to feel the same pedal force as with conventional braking, for example purely hydraulic. The difference between the PFC-act and the PFC-korr can cause a fluctuation in the pedal force.

In contrast, according to the invention, a magnetic field-oriented current control can take place in the brake boosting device. Two (shunt resistors) can be present. With these resistors two phase currents can be measured directly and a phase current can be calculated from the measured phase currents.

A motor current of the brake boosting device can be calculated very precisely from a measurement at a rotor position sensor and the three phase currents.

Therefore, a motor torque can be calculated. In the brake boosting device, the generated motor torque may be equal to a sum of an inertia term and a constant friction and a hydraulic power. $$\text{I}*\left(\text{dw}\right)\text{/}\left(\text{German}\right)={\text{T}}_{\text{hydraulic}}+{\text{T}}_{\text{constant}}$$

Here, I is the moment of inertia of the motor, (dw)/(dt) is the angular acceleration, T _hydraulic is the motor torque and T _constant is the torque due to friction.

3 shows a pressure curve on a master brake cylinder and an approximation to this in a method according to an embodiment of the present invention.

wobei als p als pMC_E der geschätze/berechnete Druck im Hauptbemszylinder bezeichnet werden kann, welcher sich mittels angegebener Formel berechnen lässt. Fgearout ist eine Ausgangskraft des Motors, Fin eine Einganstangenkraft und Fsprings eine Federkraft oder Federkräfte (Federn im Hauptbremszylinder, Rückstellfedern (Return Spring) in der Bremsverstärkereinrichtung). Weiters ist A eine Fläche des Hauptbremszylinders und das η_TMC beschreibt eine Effektivität des Hauptbremszylinders.In the 3 an estimated pressure at the master brake cylinder pMC_E (over time) is shown. The estimated pressure pMC_E can by
a formula can be calculated as follows: $$p=\frac{f_{Gea\mathrm{right}O\mathrm{and}t}+f_{in}-f_{sp\mathrm{right}inGs}}{A}\cdot n_{TMC}$$

where the estimated/calculated pressure in the main brake cylinder can be designated as p as pMC_E, which can be calculated using the given formula. Fgearout is an output force of the engine, Fin is an input rod force, and Fsprings is a spring force or spring forces (springs in the master cylinder, return springs (return spring) in the brake booster device). Furthermore, A is an area of the master brake cylinder and the η_TMC describes an effectiveness of the master brake cylinder.

iB_pMC1_float is a signal in the brake booster device for the pressure at the master brake cylinder, which can be measured with a sensor in the ESP. A signal delay can result in a gap between pCmpF_MC (ESP signal for the pressure measured at the master brake cylinder) and iB_pMC1_float. pCmpF_MC1 can be the measured pressure at the master brake cylinder, which can be present without a signal delay to the driving stabilization system.

The estimated pMC_E can partially correspond to the graph pCmpF_MC1. Therefore, the influence of the signal delay of the control signal can be reduced or avoided.

PFC_Offset_actual = pMC_E * a_actual_calc can be determined by pMC_E.

4 shows a braking process on a braking device with a driving stabilization system and a brake boosting device according to an embodiment of the present invention.

The pedal (resistance) force compensation may be based on the estimated pMC, in other words based on the difference between the virtual pressure and the pMC-estimated. The pedal feeling can thus be improved.

A pressure variation between an actual pMC (measured in the ESP) and the estimated pMC in the brake boosting device can be neglected.

the 4 shows a display similar to that 2 , but compensation for the CAN offset has been achieved, at least for the most part.

The PFC offset that is calculated on the pMC_estimated can be very close to the offset that can be calculated on or based on the current and measured pMC in the ESP. Therefore, the PF-real can be almost or exactly the same as the PF-orig.

This can be done by compensation, in other words by taking into account the CAN time shift in signal transmission, as in the 2 shown result, being compared to the 2 to the variables shown there analogously, taking into account the compensation of the signal delay (CAN), these variables PF_orig, PF_real, pMC_vers, pMC_esp, PFC_act, PFC-korr) can be adjusted to one another completely or within an acceptable tolerance.

Although the present invention has been fully described above with reference to the preferred exemplary embodiment, it is not restricted thereto but can be modified in a variety of ways.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2013083243 A1 [0003]

Claims (10)

Method for operating a braking device (10) for a vehicle (F), which can be connected to a driving stabilization system (ESP), comprising the steps: - Recognizing (S1a) a need to trigger a braking process and/or receiving (S1b) a command for generating a braking force on the braking device (10) from a user via a brake pedal (PE) of the braking device (10); - Generation (S2) of a braking force on a braking unit of the braking device (10) as a function of a pedal force received via the brake pedal, with an amplification (S3) or reduction (S4) of a pedal resistance force being effected by a brake amplification device (BE) and thereby the pedal resistance force a current braking mode is adjusted. procedure after claim 1 , In which the braking mode at least partially controls and carries out a recuperation of an electric machine. procedure after claim 1 or 2 , in which a braking impression, which corresponds to a current braking situation, is simulated for the driver by the pedal resistance force. Procedure according to one of Claims 1 until 3 , in which a control signal delay between the driving stabilization system (ESP) and the brake boosting device (BE) is taken into account and compensated for generating the braking force and/or for increasing or reducing the pedal resistance force. Method according to any of the preceding Claims 1 until 4 , in which the brake boosting device (BE) compensates for a pedal force which results from a difference between a pressure in a master brake cylinder of the braking device and a determined pedal pressure which is triggered by a user. Procedure according to one of Claims 1 until 5 , In which the brake boosting device (BE) reduces brake support during recuperative braking and adjusts the pedal resistance force to purely hydraulic braking on the braking device. procedure after claim 6 , in which a dynamic pressure is determined at the beginning of a recuperative braking mode and is taken into account when generating the pedal resistance force when the dynamic pressure exceeds a predetermined maximum value. Method according to any of the preceding Claims 1 until 7 , in which an approximate pressure at the master brake cylinder is determined by measuring a comparison current in the brake boosting device (BE) and drawing conclusions about the approximate pressure at the master brake cylinder from this. procedure after claim 8 , in which a rotor position sensor of an electric motor, with which the brake boosting device is operated, is read and the phase currents of the electric motor are determined, and from this a motor current of the brake boosting device is determined as a comparison current, from which a torque of the motor of the brake boosting device is subsequently determined, from which then the approximate pressure at the master brake cylinder is determined. Braking device (10) for a vehicle (F), which can be connected to a driving stabilization system (ESP), comprising: - a brake boosting device (BE); - a control device (SE), which is set up to recognize a need to trigger a braking process and/or to issue a command to generate a braking force on the braking device (10) from a user via a brake pedal (PE) of the braking device (10). receive; - a braking unit; - a brake pedal (PE), wherein the control device and the brake unit can be operated together and are set up to generate a braking force on the brake unit as a function of a pedal force received via the brake pedal, wherein a pedal resistance force can be generated or changed by the brake boosting device (BE). is to thereby adjust the pedal resistance force to a current braking operation.

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