JP2020185984A - Determination of brake pedal characteristic curve for brake system of vehicle with regeneration brake - Google Patents

Abstract

To provide a modification method of a brake pedal operation characteristic curve of a vehicle with a regeneration brake.SOLUTION: A brake system includes a friction brake which is hydraulically connected with an electromechanical actuator by a hydraulic component and a regeneration brake. A brake pedal characteristic curve is a function of pressure in the hydraulic component depending on a stroke of the electromechanical actuator. The brake pedal characteristic curve has an idle stroke and a stiffness factor. This method includes following each step of: performing measurement of the brake pedal characteristic curve, by the electromechanical actuator, in accordance with a dynamically determined criterion, in particular after a pre-defined number of manipulation of the brake system, where at least a part of braking action is produced by the friction brake; storing the measured brake pedal characteristic curve; and replacing the brake pedal characteristic curve by the measured brake pedal characteristic curve.SELECTED DRAWING: Figure 4

Description

The present invention relates to a braking system for a vehicle having a regenerative brake. In particular, the present invention relates to a method of modifying a brake pedal characteristic curve for a braking system. Furthermore, the present invention relates to control devices, usages, program elements, and computer readable media.

Energy efficiency is becoming more significant in vehicles, especially in electric and hybrid vehicles. Therefore, attempts have been made to operate the electric motors of electric and hybrid vehicles as generators as often as possible when braking, and to use the braking process for energy recovery accordingly. This is often referred to as regeneration. In many cases, attempts have been made to convey to the driver, who is about to start braking by operating the brake pedal, the feeling of a brake pedal as when braking with a conventional hydraulic friction brake. .. Thereby, it is realized that the driver receives a similar or equivalent brake pedal sensation each time when the braking action is similar. For this purpose, a vehicle, eg, a control system, stores a brake pedal characteristic curve for the brake system. However, the braking mechanism and hydraulic system of the friction brake change throughout the useful life of the vehicle, so that the stored brake pedal characteristic curve does not match the actual brake pedal characteristic curve of the friction brake. Therefore, in at least some vehicles, braking that only friction braking contributes to deceleration can be performed on a regular basis. At that time, the brake pedal characteristic curve can be measured and the brake pedal characteristic curve can be updated; otherwise, the brake pedal sensation will not be compatible with the braking action. That is, by frequently measuring the brake pedal characteristic curve, it is possible to achieve a rough agreement between the stored brake pedal characteristic curve and the actual brake pedal characteristic curve. However, especially in electric and hybrid vehicles, the opposite is true: applying the brakes needed for measurement loses potential regenerative energy-ie by friction on the brakes-and thus deceleration by friction brakes. Should be done as rarely as possible.

The challenges of the present invention provide a balance between the smallest possible difference between the stored brake pedal characteristic curve and the actual brake pedal characteristic curve on the one hand and the rarest possible friction braking braking on the other. To provide a method.

This problem is solved by the object of the independent claim. Development examples of the present invention will become clear from the dependent claims and the following description.

The first aspect relates to a method of modifying the brake pedal characteristic curve for a brake pedal for operating the vehicle's braking system, the braking system being set up to generate a braking action for the vehicle. The braking system includes a friction brake that is hydraulically connected to an electromechanical actuator by a hydraulic component and a regenerative brake. The brake pedal characteristic curve is a function of pressure in the hydraulic component that depends on the stroke of the electromechanical actuator. The brake pedal characteristic curve has an idle stroke and a rigidity coefficient.

The brake pedal characteristic curve is a characteristic curve that reflects the pressure that can be sensed by the brake pedal with respect to the pedal stroke of the brake pedal. The brake pedal characteristic curve can be perceived by the driver as a brake pedal sensation, for example. The brake pedal characteristic curve may be implemented in a single (partial) system of the vehicle, for example in a brake pedal simulator. The brake pedal characteristic curve is formed by the cooperation of multiple (partial) systems of the vehicle, for example, at least one of the (partial) systems such as a brake booster, booster, brake pedal simulator, and / or electromechanical actuator. In one case, it may be implemented. The brake pedal characteristic curve may be stored in a single (partial) system accordingly, or may be stored in multiple (partial) systems. The brake pedal operates the vehicle's braking system to produce the braking action for the vehicle.

The vehicle may be, for example, a land traveling vehicle, in particular a passenger car, a transporter, a truck, a dedicated land vehicle, or an amphibious vehicle. The vehicle may be an electric vehicle or a hybrid vehicle. The vehicle can include at least one large electric motor. A large electric motor is an electric motor that contributes to moving a vehicle. Large electric motors of this type can have high regenerative potential, i.e., can make a major contribution to energy recovery during the braking process.

The friction brake of the braking system is a brake that contributes to the deceleration of the vehicle by friction. The friction brake can be operated at least partially by an electromechanical actuator. The electromechanical actuator can be controlled through a control system and may be part of a brake-by-wire system, for example. The friction brake is hydraulically connected to the electromechanical actuator by a hydraulic component. The hydraulic component may be a simple hydraulic pipe, for example in the case where each electromechanical actuator is connected to the wheel of the vehicle. The hydraulic component can include a multi-circuit braking system and / or may be part of a multi-circuit braking system. In some embodiments, the hydraulic component may be connected to the brake pedal, for example via a master brake cylinder connected to the brake pedal.

A regenerative brake in a braking system is a brake that operates as a generator at least one electric motor that contributes to moving the vehicle. Regenerative braking can be controlled through a control system and may be part of a brake-by-wire system, for example. Only regenerative braking can be used, only friction braking can be used, or both partial braking systems are in principle free to use to produce braking action for the vehicle during braking. It can be used in selectable ratios. The distribution of braking action to each partial braking system should use, for example, the desired deceleration or driving conditions, brake assist-eg ABS (Anti-Lock System) or ESC (Electronic Stability Control) -and / Alternatively, it may depend on how the electric motor and partial braking system are implemented in the vehicle.

In one embodiment, it is possible to apply at least a portion of the invention to a braking system that has, or in addition to, a motor brake, an eddy current brake, or a similar brake in place of or in addition to a regenerative brake. This is the case for at least some tracks. Even when such a system is involved, the proportion of friction brakes in the braking process can be reduced and a similar brake pedal feel is maintained each time for a particular deceleration.

The brake pedal characteristic curve is a function of pressure in the hydraulic component that depends on the stroke of the electromechanical actuator. That is, the brake pedal characteristic curve-and thus the so-called brake pedal sensation-is a kind of "imitation" of the pressure situation in the hydraulic component and / or in response to the pressure situation in the hydraulic component. In simple terms, the driver should be informed of the brake pedal feel that the driver would receive if, for example, a purely hydraulic brake (including servo brake equipment in some cases) was operated. For this purpose, a vehicle, eg, a control system, stores a brake pedal characteristic curve for the brake system. The brake pedal characteristic curve may be stored, for example, as a function and / or stored as a set of interpolation points where interpolation is made between them. The brake pedal characteristic curve can resemble the "traditional" pV characteristic curve (pressure / volume characteristic curve) of the braking system. The brake pedal characteristic curve has an idle stroke and a rigidity coefficient. The idle stroke corresponds to the idle stroke of a purely hydraulic braking system in which the braking action before the orifice hole is closed does not yet occur. The modulus of stiffness is at a predefined location, for example above the pressure measured in the master brake cylinder, or at a pressure near about 10 bar, or at a low pressure measured, for example, at a hydraulic component ( For example, about 5 bar), which corresponds almost to the gradient of the brake pedal characteristic curve.

Such a brake pedal characteristic curve is applied to the brake pedal simulator. Brake pedal simulators may be manufactured, for example, as independent members and may include springs, mechanical resistors (eg, cushioning members), and / or other members. The brake pedal simulator may be manufactured as part of the vehicle's servo brake equipment. That is, the brake pedal no longer acts directly on the hydraulic component of the brake system, but controls the brake system through the brake pedal simulator. As a result, the brake pedal feel when making certain decelerations is essentially the brake pedal feel when the vehicle is decelerated purely by friction brakes, purely by regenerative braking, or by "mixing" of these brakes. Can be. However, the brake pedal feel should still be in line with the pressure conditions in the (hydraulic) friction brake or hydraulic component; this is achieved by the brake pedal characteristic curve and the brake pedal simulator.

The method of modifying the brake pedal characteristic curve has the following steps:
-After a predefined number of brake system operations, an electromechanical actuator performs a measurement of the brake pedal characteristic curve, where at least part of the braking action is generated by the friction brake and the rest is regenerated. Produced by the brakes
-As an optional step: the measured brake pedal characteristic curve is saved and
-The measured brake pedal characteristic curve replaces the brake pedal characteristic curve.

Since the brake pedal characteristic curve is a function of pressure in the hydraulic component that depends on the stroke of the electromechanical actuator, the measurement of the brake pedal characteristic curve-also called "rigidity determination" -is one sensor (or multiple sensors). ) Allows for actuator stroke and hydraulic components. In braking systems where there is a hydraulic coupling between the electromechanical actuator and the brake pedal, one sensor (or multiple sensors) of the brake pedal can also be utilized as an alternative or addition to the actuator stroke sensor. At the time of measurement, at a predefined interpolation point and / or continuously, the stroke of the electromechanical actuator or brake pedal and the pressure generated by the hydraulic component at that time are determined. Therefore, at least one portion of the braking action is generated by the friction brake. The rest of the braking action is produced by regenerative braking. That is, if the stiffness determination is often performed, the energy discarded by the friction brake is not (or is not) used for regeneration, so that energy efficiency is unnecessarily impaired. On the other hand, it makes sense to often perform stiffness determinations to avoid large differences between the actual and stored characteristic curves. To make the best possible compromise between these conflicting requirements, the measurement of the brake pedal characteristic curve is performed by the electromechanical actuator only after a predefined number of brake system operations. ..

As an alternative or addition, another dynamic criterion can be selected, for example, brake wear estimates based on the latest measurement and / or accelerometer, altimeter, temperature instrument history, and / Or other criteria. Along with this, it is possible to determine the rigidity more frequently, for example, in urban traffic or mountain road driving than in highway driving with almost no obstacles. The number of predefined operations (or other criteria) of the braking system can be dynamically determined. For example, the number of such operations relates to the vehicle type and / or age and / or brake configuration-eg pads (eg "Non Asbestos Organic", NAO, etc.), brake shoes, size and number of brake pistons, etc.- May depend on. The number of predefined operations can be reduced, for example in stop-and-go traffic conditions and mountain road driving, increased in highway driving, and / or other criteria can be selected.

After the brake pedal characteristic curve measurement has been performed, the measured brake pedal characteristic curve can be saved at an optional step. For example, it can be stored in the vehicle's control system and, accordingly, can also be used during braking involving regenerative braking (“regenerative braking”). In that case, it may make sense not to save each of the measured brake pedal characteristic curves, for example, when the measurements are unstable or not sufficiently complete. For example, a measurement can be identified as unstable if, for example, peaks or other differences attributed to impaired electromagnetic compatibility are measured. For example, a measurement can be determined to be incomplete enough if only a small portion of the actuator stroke is measured and / or a dynamic effect that is too large is measured.

Eventually, the brake pedal characteristic curve previously used in the braking system is replaced by the measured brake pedal characteristic curve. Here, "replaced" does not mean that the brake pedal characteristic curve is dramatically changed in many cases, but rather adapts the brake pedal characteristic curve in multiple small steps in a real system. It means that it can be ("gentle" or "gradual" change). Large differences in the measured brake pedal characteristic curves can also be used, at least occasionally, as (negative) validation criteria; for example, large differences from previously used brake pedal characteristic curves are measured. It may be necessary to discard the brake pedal characteristic curve as invalid. Other predefined criteria can also be applied for the replacement with the measured brake pedal characteristic curve. Such criteria can, for example, consider whether the difference was captured by another mechanism. For example, the fading of the brake system (eg when driving on steep mountain roads) can be compensated by other (partial) systems of the vehicle, thereby providing a brake pedal characteristic curve in the case of these types of differences. No need to adapt. Such criteria can also consider, for example, whether the difference was (perhaps or actually) caused by a short-term change in the braking system or by a long-term change. Replacements can include incremental adaptation through idle stroke and stiffness coefficients.

That is, this method allows the braking system to utilize a near-realistic brake pedal characteristic curve in many cases, or often, during the operating time of the vehicle. At the same time, the number of unnecessary measurements-and the associated unnecessary friction braking-is reduced; thereby the energy efficiency of the vehicle can be significantly improved. In addition, it can reduce the load on the friction brake and the associated wear and other wear on the friction brake. Further, the influence of NVH (NVH: Noise, Vibration, Harshness, that is, noise, vibration, harshness) based on the different brake pedal characteristic curves can be reduced. In addition, it is possible to avoid irritation with the so-called brake pedal. Frustration with these types of brake pedals can include, for example, pedal pushback (eg, in the case of incorrect or poorly adapted brake pedal characteristic curves). In addition, for example, after visiting a factory and changing brakes, it is possible to record the new brake pedal characteristic curve more quickly and provide it to the driver, which makes it even faster and / or more often realistic. A pedal feel is provided.

Yet another drawback can be avoided by the method described: for example, in the case of a hybrid electric crossover braking system (hev-X), an unrealistic brake pedal characteristic curve-for example, by mistake. The determined stiffness value-can lead to deceleration failures, for example, when the driver is constantly braking and the generator is unable to meet the required braking power, or does so. It should be, but in a situation where the target pressure of the determined hydraulic component cannot be achieved depending on the volume transferred. For example, even in a hybrid electric parallel braking system (hev-II), if the brake pedal characteristic curve is not determined sufficiently accurately, overpressure of the orifice hole of the hydraulic cylinder may occur. It can lead to, for example, hydraulic short circuits, NVH problems, and / or increased component load-eg, hydraulic pump load.

In one embodiment, the method has yet another step:
-When the vehicle is moved and a braking action for the vehicle is generated, a counter containing the number of braking processes performed is incremented, at least part of the braking action is generated by friction braking.

For example, a counter can be selected as a dynamic reference indicating whether or not the measurement of the brake pedal characteristic curve should be performed. For example, the counter count can be increased when braking is performed where the measurement of the brake pedal characteristic curve could not be performed. This may be the case, for example, when the friction brake was not or was not fully involved in braking, or when the brake pedal characteristic curve measurement could not be performed with sufficient quality, for example. When the measurement is unstable or not perfect enough. This may be the case, for example, with controller intervention (eg with a brake assist system), over-dynamic driving and / or over-dynamic braking. The level of the counter (counter value) can reflect, for example, the predefined number of operations of the braking system-or its function-that the measurement of the brake pedal characteristic curve is subsequently performed. This number of times how many brakes should be applied without measuring the brake pedal characteristic curve can be vehicle-specific and / or can take into account current and / or past traffic conditions, for example. The initial counter value can be determined for the vehicle and / or the vehicle series, for example, prior to delivery of the vehicle or vehicle series. After exceeding the predefined counter value, the friction brake measurement can be forced, for example by limiting the generator torque of the regenerative brake. The brake pedal characteristic curve can be measured and the counter is reset as soon as it is available and the brake pedal characteristic curve is saved for subsequent regenerative braking.

In one embodiment, the method has yet another step:
-The counter is set to zero when the vehicle (10) is moved and a braking action for the vehicle (10) is generated, at which time the entire braking action is generated by the friction brake (20).

The counter is set to zero (reset) when the entire braking action is generated by the friction brake and a successful measurement can be made. The counter can also be reset when braking is performed without the generator torque being utilized, which allows a successful measurement of the brake pedal characteristic curve-for example, by friction braking alone. This can lead to further improvements in vehicle energy efficiency.

In one embodiment, the method has yet another next step:
-Counters are stored in non-volatile memory when the vehicle is switched off
-Counters are read from non-volatile memory when the vehicle is switched on.

Along with this, there is an advantage that the standard of "latest level of counter" can be maintained beyond the new start of the vehicle.

In one embodiment, the measurement of the brake pedal characteristic curve is performed by an electromechanical actuator when the vehicle is stopped. In one embodiment, measurements of the brake pedal characteristic curve can also be performed regardless of the predefined number of operations of the braking system-and, for example, the level of the counter.

A vehicle is "stopped" when it is stopped or stopped and is switched off. At this time, the driver can leave the vehicle. It is possible (more than necessary) to check for mechanical fixation, such as the P position of the handbrake and / or automatic transmission. Such measurements at rest have the advantage of not requiring the operation of the brake pedal; in particular, the driver does not have to be required to operate the brake pedal.

This embodiment has the advantage that the brake pedal characteristic curve and particularly the stiffness of the brake system can be determined with high quality. To that end, for example, the following aspects contribute:
-No lateral acceleration occurs when the vehicle is stopped. Left-right acceleration can compromise the quality of measurement based on dynamic effects.
-When the vehicle is stopped, there is no disc impact on the brake disc, so there is no error in measurement accuracy.
-Since the actuator can operate quasi-statically, there is no dynamic effect of the pressure measured by the hydraulic component, for example due to the mass of the hydraulic fluid.

In addition, when the vehicle is in motion, various effects can occur on the vehicle that can upset the measurement of the brake pedal characteristic curve. For example, it may be desirable that short-term effects-such as temperature and fading-are not or only slightly incorporated into the modulus of stiffness. Instead, the long-term effect should be incorporated into the measurement more accurately and / or earlier. This can be true in the higher range for static or quasi-static measurements. Measurements when the vehicle is stopped may need to be performed relatively rarely while the vehicle is running, or may even be omitted-for example, if the vehicle is stopped relatively frequently. It can also be preferable for some reason. For certain braking architectures, improved measurement framework conditions are met when measuring at rest. For example, in a hybrid electric parallel braking system (hev-II), the orifice holes are closed, the idle stroke determination is successfully completed at the beginning of braking, and volume blending and / or controller intervention on the front axle is performed. It may be required not to do so; see, for example, the further description (in the description of the drawings) below. Such framework conditions can be met, if anything, when the vehicle is stopped.

In one embodiment, a set of pedal characteristic curves including hysteresis can be recorded. Hysteresis can occur in many real-world hydraulic braking systems. Therefore, reflecting this phenomenon is another factor for a realistic pedal feel.

In one embodiment, the measurement of the brake pedal characteristic curve takes into account systematic differences to the measurement when the vehicle is moving in measuring the brake pedal characteristic curve when the vehicle is stopped. Differences in these different measurements are explained in detail above.

In one embodiment, the method has another step:
− The difference between the measured brake pedal characteristic curve and the stored brake pedal characteristic curve is determined.
-The predefined number of brake system operations changes depending on the difference.

The difference between the measured brake pedal characteristic curve and the stored brake pedal characteristic curve is determined, for example, by referring to a number of measurement points and / or by comparing the idle stroke and stiffness of both pedal characteristic curves. can do. Differences can also be analyzed based on the measurement series. The measurement series can also take into account time transitions. Based on or depending on the analysis of one or more differences, the predefined number of operations of the braking system is modified. For example, large differences and / or sudden increases in differences can lead to a reduction in the number of brake system operations. Thresholds for such changes can be vehicle-specific and / or hardware-specific. It is also possible to provide tolerances where differences do not lead to changes. When these tolerances are exceeded and the difference between the actual and stored characteristic curves is large enough to increase the risk of hardware damage and / or NVH problems, this is a braking system. This leads to a reduction in the number of operations of the brake pedal characteristic curve, thereby re-performing or forcing the measurement of the brake pedal characteristic curve as soon as possible.

In one embodiment, long-term changes in braking system parameters are considered more strongly than short-term changes. Brake system parameters can be, for example, the thickness of the brake pads, the material of the brake pads, the amount of brake fluid in the hydraulic component, and / or the assembly of the hydraulic system (eg, mounting position).

Long-term changes in the braking system can be caused, for example, by vehicle error since line production, aging of the braking system, wear and the like. Short-term changes can be caused by, for example, temperature, fading, and so on. Short-term changes are often compensated by other systems in the vehicle. Too steep and / or too large changes in the brake pedal characteristic curve can lead to increased risk of hardware damage and / or NVH problems. Strong consideration of long-term changes can be achieved, for example, by comparing a series of measurements and / or by more weighting the measurements at rest.

Another aspect relates to a vehicle controller set up to carry out the methods described above and / or below.

Another aspect relates to a vehicle having the control device described above.

Another aspect relates to the use of this method for determining the brake pedal characteristic curve of a vehicle as described above and / or described below.

Another aspect relates to a program element that, when executed on the controller described above, instructs the controller to perform the method described above.

Another aspect relates to a computer-readable medium in which the program elements described above are stored.

Next, yet another measure for improving the present invention will be described in detail with reference to the drawings with a description of preferred embodiments of the present invention.

It is a schematic diagram which shows the vehicle based on one Embodiment. It is a schematic diagram which shows the brake pedal characteristic curve based on one Embodiment. It is a schematic diagram which shows the apparatus which determines the rigidity based on one Embodiment. It is a schematic diagram which shows the measurement of the brake pedal characteristic curve based on one Embodiment. It is a schematic diagram which shows the method based on one Embodiment. It is a schematic diagram which shows another method based on one embodiment.

FIG. 1 shows a schematic view of a vehicle 10 based on one embodiment. This vehicle has a control unit 35 of the brake system 25. The control unit 35 is controlled by a brake pedal 12 for operating the brake system 25, and the brake system 25 is set up to generate a braking action for the vehicle 10. The brake pedal 12 has a brake pedal simulator 14, to which a brake pedal characteristic curve 30 (see FIG. 2) is applied. The braking system 25 has four friction brakes 20, which are hydraulically connected by an electromechanical actuator 21, each of which is a hydraulic component 22-schematically shown here as a brake pipe. .. Further, the brake system 25 has a regenerative brake 15 which is also controlled by the control unit 35. The control unit 35 has a storage device 37 capable of storing, for example, the brake pedal characteristic curve 30. Only the regenerative brake 15 can be used, or only the friction brake 20 can be used to generate the braking action for the vehicle 10 when braking, or both of these partial braking systems 15 and In principle, 20 can be used at a freely selectable ratio.

FIG. 2 shows a schematic diagram of the brake pedal characteristic curves 30 and 31 based on one embodiment. Here, the brake pedal characteristic curve 30 is a function of the pressure of the hydraulic component 22 that depends on the stroke of the electromechanical actuator 21 (see FIG. 1). On the y-axis, the pressure p in the hydraulic component 22 is displayed depending on the stroke s of the electromechanical actuator 21 on the x-axis. The pressure p-depending on the embodiment of the braking system-can take into account the pressure of the main cylinder (master cylinder) controlled and / or mechanically coupled by the brake pedal 12 as an addition or alternative. In FIG. 2 shown, the first brake pedal characteristic curve 30 is compared with the measured brake pedal characteristic curve 31. Changes in idle stroke s0 and stiffness f can be clearly seen between both brake pedal characteristic curves. Multiple individual measurements-and accompanying braking-may be required for the measurements of the brake pedal characteristic curves 30, 31.

FIG. 3 shows a schematic diagram of a device 50 that determines rigidity based on one embodiment. The pressure p of the hydraulic component 22 (see FIG. 1) and the stroke s of the electromechanical actuator 21 are applied to the input unit 51 as input data. The pressure p and the stroke s (see FIG. 2) are utilized in the component 52 for the (new) determination of the stiffness f. The stroke s and the stiffness f are used for estimating the idle stroke s0. The idle stroke s0 can be approximately 0 to 6 mm. The idle stroke s0 is used together with the brake pedal characteristic curve 30 to determine the target pressure p ^* . Further, the brake pedal characteristic curve 30 is also incorporated into the determination of stiffness f, for example to discard invalid measurements. The target pressure p ^* and the stiffness f are used to determine the virtual target pressure pv. The virtual target pressure pv and pressure p are transmitted to the transition logic 54. The transition logic 54 acts so that the transition from hydraulic braking to regenerative braking and vice versa is barely or completely perceptible to the driver. In addition to this, the transition logic 54 can consider the signal "blending mode" b, which should (or is) braked purely hydraulically (ie, only by the friction brake 20) or. The generator adjusts whether braking is assisted (by the regenerative brake 15). Further, the transition logic 54 can take into account the brake pedal movement 56, which incorporates the dynamic aspects of the movement of the brake pedal 12 into the control unit. As a result, the transition logic 54 supplies the target deceleration td. This is applied to the output unit 59 of the device 50 together with the virtual target pressure pv.

FIG. 4 shows a graph 60 of the measurement process of the brake pedal characteristic curve 30 based on one embodiment. Here, a braking system architecture is adopted that takes into account the pressure of the main cylinder (master cylinder) controlled and / or mechanically connected by the brake pedal 12. In the graph 60, the time t is plotted on the x-axis, during which the brake pedal 12 (see FIG. 1) is operated and the measurement is performed during that time. The stroke s of the brake pedal 12 is displayed as the upper dashed curve s, and the speed v of the brake pedal 12 is displayed as the lower curve v. In this embodiment, the speed v of the brake pedal 12 must not exceed the maximum speed v _max so that the dynamic effect (eg of the brake fluid) does not make the measurement useless. Measurement 62 is performed between the start time ts and the end time te. At the start time ts, the determination of idle stroke s0 (see FIG. 3) must be completed successfully. At time t0, before the start time ts, the orifice hole must be closed. No volumetric blending (eg, on the front axle) should be performed during measurement 62. A volume blend is one in which the volume transferred by the pedal operation of the brake pedal 12 is stored elsewhere rather than sent to the wheel brake caliper, thereby preventing the generation of hydraulic brake torque and doing so. It is a process that fully utilizes the available generator torque. In addition, controller intervention (by Controller-Intervention, eg ABS) should not be performed.

FIG. 5 shows a schematic diagram of the method based on one embodiment as a flowchart 80. In step 81, the measurement of the brake pedal characteristic curve 30 (see FIG. 2) is executed. The measurement of the brake pedal characteristic curve 30 is performed, for example, after a predefined number of operations of the brake system 25 (and / or other dynamically determined criteria). The measurement is performed by the electromechanical actuator 21. In some embodiments, an architecture of the braking system is utilized in which the pressure of the main cylinder (master cylinder) controlled by the brake pedal 12 and / or mechanically connected is considered alternative or additionally. Will be done. At the time of measurement, at least one portion of the braking action is generated by the friction brake 20. In step 82, the measured brake pedal characteristic curve 31 is stored in the storage device. For example, the brake pedal characteristic curve 31 can be stored in the control system of the vehicle, and can be used for braking in which regenerative braking is involved. For example, when the measurements are unstable or incomplete, it may make sense not to save each of the measured brake pedal characteristic curves. In step 83, the brake pedal characteristic curve previously used in the braking system is replaced by the measured brake pedal characteristic curve. In doing so, a predefined criterion for replacement with the measured brake pedal characteristic curve can be applied. For example, large deviations from the previously used brake pedal characteristic curve can be discarded as invalid.

FIG. 6 shows a schematic diagram of another method based on one embodiment as a flowchart 100. This method is started in step 101. In step 102, it is checked whether the vehicle 10 (see FIG. 1) is stopped or moving. When the vehicle 10 is stopped, in step 103, the stop measurement is performed as described in detail above. At that time, for example, an electromechanical actuator is controlled so that braking is performed when stopped, measurement is performed at that time, and optionally storage is performed. In one embodiment, the measurement of the brake pedal characteristic curve at rest is at the level of a counter that counts the number of brakings that have not been measured, regardless of the predefined number of brake system operations. Regardless-can also be done. In such a stop measurement, the driver can be outside the vehicle 10. At step 104, it is checked whether the measurement meets certain criteria (see above) or whether the measurement must be discarded. If it is determined that the measurement was successful, in step 105 the brake pedal characteristic curve previously used in the braking system is replaced with the measured brake pedal characteristic curve and the counter is set to zero. The method can then be terminated in step 114 or started again in step 101.

When the vehicle 10 is not stopped, in step 106, it is checked whether or not the vehicle 10 has been newly started. If yes, the counter is read in step 107. Subsequently, in step 108, it is checked whether the counter exceeds the predefined value. If yes, the involvement of the friction brake 20 (see FIG. 1) is forced during the next braking in step 109, and / or the next braking is performed solely by the friction brake 20. Then, in step 112, the brake pedal characteristic curve previously used in the braking system is replaced by the measured brake pedal characteristic curve and the counter is set to zero. If it is confirmed in step 108 that the counter has not yet exceeded the predefined value, then "normal" braking is performed in step 110. If the brake pedal characteristic curve was successfully measured during this braking in step 110, then in step 112 the brake pedal characteristic curve previously used in the braking system was measured by the measured brake pedal characteristic curve. Replaced-or adapted in multiple small steps ("gentle" or "incremental" changes) -the counter is set to zero. Otherwise, the counter is incremented in step 113. The method is subsequently terminated in step 114 or restarted in step 101.

10 Vehicle 12 Brake pedal 15 Regenerative brake 20 Friction brake 21 Electromechanical actuator 22 Hydraulic component 25 Brake system 27 Non-volatile memory 30 Measured brake pedal characteristic curve 31 Saved brake pedal characteristic curve 33 Difference 35 Control device 37 Non-volatile memory

Claims (15)

In the method of modifying the brake pedal characteristic curve (30) for the brake pedal (12) for operating the brake system (25) of the vehicle (10), the brake system (25) is a brake for the vehicle (10). Set up to generate action,
The brake system (25)
A friction brake (20) hydraulically connected to an electromechanical actuator (21) by a hydraulic component (22),
It has a regenerative brake (15) and
The brake pedal characteristic curve (30) is a function of pressure in the hydraulic component (22) that depends on the stroke of the electromechanical actuator (21) and has an idle stroke and a rigidity coefficient.
The method has the following steps:
After a predefined number of operations of the braking system (25), the electromechanical actuator (21) performs a measurement of the brake pedal characteristic curve (30), at which at least part of the braking action is said friction. It is generated by the brake (20) and the rest is generated by the regenerative brake (15).
A method in which the brake pedal characteristic curve (30) is replaced by the measured brake pedal characteristic curve (31). Has yet another step,
The method of claim 1, wherein the measured brake pedal characteristic curve (31) is stored. Has yet another step,
When the vehicle (10) is moved and a braking action for the vehicle (10) is generated, a counter containing the number of braking processes performed is incremented.
The method according to claim 1 or 2, wherein at most a part of the braking action is generated by the friction brake (20) at this time. Has yet another step,
The counter is set to zero when the vehicle (10) is moved and a braking action for the vehicle (10) is generated.
The method according to claim 1 or 2, wherein the entire braking action is then generated by the friction brake (20). Has yet another step,
When the vehicle (10) is switched off, the counter is stored in the non-volatile memory (37).
The method according to any one of claims 1 to 4, wherein the counter is read from the non-volatile memory (37) when the vehicle (10) is switched on. The method of claim 1 or 2, wherein the measurement of the brake pedal characteristic curve (30) is performed by the electromechanical actuator (21) when the vehicle (10) is stopped. The measurement of the brake pedal characteristic curve (30) is compared with the measurement when the vehicle (10) is moving in the measurement of the brake pedal characteristic curve (30) when the vehicle (10) is stopped. The method according to claim 6, which takes into consideration the difference in the system at the time. The method according to any one of claims 1 to 7, wherein the brake pedal characteristic curve (30) has hysteresis. The difference (33) between the measured brake pedal characteristic curve (30) and the stored brake pedal characteristic curve (31) is determined.
The method according to any one of claims 1 to 8, wherein the predefined number of operations of the braking system is changed depending on the difference (33). The method of any one of claims 1-9, wherein long-term changes in the parameters of the braking system are considered more strongly than short-term changes. A control device (35) for a vehicle (10) set up to carry out the method according to any one of claims 1 to 10. A vehicle having the control device (35) according to claim 11. The method of using the method according to any one of claims 1 to 10, for determining the brake pedal characteristic curve (30) of the vehicle (10). A program element that instructs the control device (35) to carry out the method according to any one of claims 1 to 10 when executed by the control device (35) according to claim 11. A computer-readable medium in which the program elements of claim 14 are stored.

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