Method for performing brake disc cleaning of a vehicle

Abstract

The present disclosure relates to a method for performing brake disc cleaning of an at least partially electrically driven vehicle comprising a brake system with at least one friction brake whose surface can come into contact with a corresponding brake disc, the method comprising a step S1 of determining an upcoming braking event by using at least forward vehicle information, a step S2 of predicting a required deceleration level of the own vehicle by using the forward vehicle information, and a step S3 of implementing brake disc cleaning of the friction brake only in case the predicted required deceleration level of the own vehicle in the upcoming braking event is above a predetermined value.

Description

Technical Field

[0001] This disclosure relates to a method for performing brake disc cleaning of a vehicle that is at least partially electrically driven, a computer program element configured to implement the method, and an electric vehicle that is at least partially electrically driven, including a control unit configured to implement the method. Background Technology

[0002] BEVs (Battery Electric Vehicles) and PHEVs (Plug-in Hybrid Electric Vehicles) with relatively large electric motors rarely use friction brakes because regenerative braking is prioritized and will cover most braking needs. When the required deceleration reaches a certain level, some braking will be applied by friction brakes.

[0003] Because hard braking is relatively uncommon in everyday driving, friction brakes are not used adequately, leading to rust on the brake discs in cold and wet conditions.

[0004] Rust on the brake discs can significantly reduce braking performance, resulting in unnecessarily longer braking distances. Another side effect is unpleasant noise at very low speeds (such as during parking maneuvers), where friction brakes are still in use, and even when the brakes are not engaged.

[0005] Currently, many EVs (electric vehicles) employ disc cleaning functions by using only friction brakes, allowing the temperature rise during each braking event to accumulate and reach a desired level, such as 100 degrees Celsius. This mitigates brake disc rusting. However, in this case, there is little to no possibility of recovery. Summary of the Invention

[0006] Currently, there is no specific braking event selection when cleaning brake discs. The nominal approach is to use friction brakes at regular intervals, even if some of these involve low braking energy and are of little use. Once disc cleaning is activated, all braking events will be affected by friction brake application. This strategy is very inefficient, especially considering the strong demand for longer distances in BEVs.

[0007] Therefore, it may be necessary to provide an improved method for performing brake disc cleaning on at least partially electrically powered vehicles.

[0008] The problem is at least partially resolved or mitigated by the subject matter of the independent claims of this disclosure, wherein further examples are incorporated in the dependent claims.

[0009] According to a first aspect, a method is provided for cleaning the brake discs of at least partially electrically driven vehicles (the vehicle itself, a parent vehicle, or a privately owned vehicle), the vehicle including a braking system having at least one friction brake. The surface of the friction brake can contact a corresponding brake disc. The method includes (not necessarily in this order):

[0010] - Step S1: Determine the upcoming braking event of the at least partially electrically driven vehicle by using at least the information of the vehicle ahead.

[0011] - Step S2: Predict the required deceleration level for at least partially electrically powered vehicles by using information about vehicles ahead.

[0012] - Step S3: Perform brake disc cleaning of the friction brake of the at least partially electrically driven vehicle only if the predicted deceleration level required for the upcoming braking event of the at least partially electrically driven vehicle is above a predetermined value.

[0013] Therefore, a smarter (e.g., more energy-efficient) method for cleaning brake discs is provided.

[0014] In one example, the information about the vehicle ahead may include at least one of several conditions, such as the time gap between the vehicle and the vehicle ahead, the predicted deceleration required by the vehicle, and the vehicle's expected braking energy, which are used to assess the vehicle's braking conditions, i.e., to predict the level of deceleration required by the vehicle. Therefore, the information about the vehicle ahead can be collected using several vehicle units used to observe the environment, such as cameras, radar sensors, sensors for determining acceleration, etc.

[0015] In one example, further information can be combined with information about the vehicle ahead to determine an upcoming braking event for a vehicle that is at least partially electrically powered (in the subsequent vehicle). This further information includes at least one of the vehicle's adaptive regenerative braking force and driver behavior information such as actual pedal position. The adaptive regenerative braking function can be used as an information source to indicate the potential level (force) of braking required.

[0016] If the required deceleration level for the vehicle is predicted to be above a certain value during an upcoming braking event, thus achieving high braking energy, then brake disc cleaning can be performed only during that type of braking event, thereby minimizing unnecessary use of the friction brakes.

[0017] Furthermore, in one example, the required deceleration level of the vehicle can be predicted by determining a safe distance from the vehicle ahead, and / or calculating the corresponding regenerative braking force of the vehicle, and / or determining the required braking force of the vehicle based on the vehicle mass and / or the estimated road load, and / or determining the required braking energy and / or braking power of the vehicle.

[0018] The time gap t between this vehicle and the vehicle in front can be calculated. gap Multiplied by the vehicle's actual speed (v) ego To determine the safe distance d from the vehicle ahead:

[0019] d = t gap *v ego

[0020] The time interval t gap The calculation is performed by looking up a table, and its value depends on the vehicle's actual speed, i.e., its rate v. ego .

[0021] To calculate the adaptive regenerative braking force of this vehicle, the acceleration required to achieve zero relative velocity between the vehicle and the vehicle in front within a safe distance d when approaching the vehicle ahead is calculated as follows:

[0022]

[0023] in:

[0024] v ahead Speed ​​of the vehicle ahead

[0025] a: The acceleration required to achieve zero relative velocity between this vehicle and the vehicle in front.

[0026] a pred The predicted acceleration required to activate brake disc cleaning in this vehicle.

[0027] Therefore, acceleration a pred It is the acceleration required to activate the brake disc cleaning process.

[0028] The estimated road load F is based on the vehicle mass and is estimated solely by vehicle motion sensors such as accelerometers. roadload Determine the required braking force F for this vehicle. brake This can be accomplished through the following calculation:

[0029] F brake =mass*a+F roadload

[0030] The road load can be calculated using a set of constants multiplied by the linear sum and square of the vehicle speed v: F_rl=c1+c2*v+c3*v^2.

[0031] The braking energy required for this vehicle is E brake It depends on the existing brake disc temperature model for each vehicle and can be determined by the following formula:

[0032]

[0033] in:

[0034] E req The predicted braking energy required for cleaning the brake discs of this vehicle.

[0035] The required braking power P for this vehicle brake Calculated as follows

[0036] P brake =F brake *r W *ω wheel >P req [kW]

[0037] in:

[0038] r W Effective wheel radius

[0039] ω wheel Deceleration during braking

[0040] P req Braking force required by the driver

[0041] Furthermore, in one example, a braking event of this vehicle may be triggered when at least one, some, or all of the following conditions are met:

[0042] - The regenerative braking force of this vehicle exceeds the predetermined level and / or rate.

[0043] - The determined speed difference between this vehicle and the vehicle in front exceeds the predetermined speed.

[0044] - The accelerator pedal release rate of this vehicle exceeds the predetermined value, and

[0045] - The driver of this vehicle requested a braking torque exceeding the predetermined value.

[0046] If single-pedal drive is applicable to this vehicle, at least one of the following conditions may also need to be met:

[0047] - The accelerator pedal position of this vehicle is below the predetermined value, and

[0048] - The driver of this vehicle has requested a braking torque rate exceeding the predetermined value.

[0049] In another example, a computer program element is proposed that is configured to implement the methods described above when run by a processor.

[0050] In another example, a computer program element readable storage medium is proposed that stores the computer program element as described above.

[0051] In another example, an electric vehicle that is at least partially electrically driven is proposed, including one or more units configured to acquire information about a vehicle ahead, one or more units configured to acquire information about the vehicle itself, and at least one control unit configured to implement the method described above.

[0052] This vehicle information may include at least the vehicle's pedal status and / or braking information and / or regenerative braking force. Attached Figure Description

[0053] Exemplary examples of the invention will now be described with reference to the accompanying drawings.

[0054] Figure 1 A schematic diagram illustrating an exemplary example of a method for performing brake disc cleaning is shown.

[0055] Figure 2 A schematic diagram showing the measurement of the adaptive regenerative force function of an exemplary example of a method for performing brake disc cleaning is provided.

[0056] Figure 3 The steps of a method for performing an exemplary example of brake disc cleaning are shown.

[0057] The accompanying drawings are merely illustrative and are intended to illustrate examples of the invention. In principle, identical or equivalent elements have the same reference numerals. Detailed Implementation

[0058] Figure 1 A schematic diagram illustrating an exemplary example of a method for performing brake disc cleaning is shown. Here, information required to predict the deceleration level in order to determine whether brake disc cleaning should be performed is illustrated.

[0059] As can be seen, the information is collected in the central module 10, which can process the information and also command the braking systems 200 and 201. The braking systems 200 and 201 are directed to the brake control module 200 for the friction brakes (whose brake discs need to be cleaned, for example, to remove rust) and the electric motor unit 201 (which is responsible for regenerative braking). In order for the central module 10 to command the braking modules 200 and 201, information from the environmental observation unit 100 (such as cameras, radar, and other sensors), as well as driver behavior information from unit 101 and the required braking energy from the vehicle's brake disc model 102, are necessary.

[0060] Driver behavior information is mainly the status of the accelerator and brake pedals or the status from a single pedal, which is suitable for acceleration and braking in the case of single-pedal driving.

[0061] When all the necessary information is available, the central module 10 calculates the predicted braking force (in N) and converts it into energy (in J). This energy is used to compare with the braking energy (in J) required for the upcoming braking event. Then, the levels of frictional braking torque and regenerative braking torque are calculated.

[0062] Once the accelerator pedal is released or the brake pedal is depressed (in a single-pedal configuration, only when the pedal is released at a predetermined position), a request to apply the respective torques is sent to modules 200 and 201 to act accordingly, thereby activating the brake disc cleaning.

[0063] In one example, the following conditions need to be met to send the request:

[0064] - The adaptive regenerative force has an absolute level of 1500 N and a rate greater than 300 N / s,

[0065] - The speed difference between this vehicle and the vehicle ahead > 10 km / h, and

[0066] - The accelerator pedal release rate > X% / s and the accelerator pedal position < Y% (in single-pedal driving), where X and Y are predetermined values depending on the vehicle and its configuration, and

[0067] - The braking torque required by the driver > V Nm, the rate of the braking torque required by the driver > W Nm / s (in single-pedal driving), where V and W are predetermined values depending on the vehicle and its configuration.

[0068] In Figure 2 shows a schematic diagram of the measurement of the adaptive regenerative force function of an exemplary example of the method for performing brake disc cleaning. Here, approximately 1.63 seconds before the braking force required by the driver (indicated by the rising side of the solid line), the possible need for braking (indicated by the dashed line) is recorded. It can be seen that the release rate of the accelerator pedal or the rising rate of the driver's braking request can be used as a cue / trigger for the upcoming high deceleration demand, and thus prepare to engage the frictional brake, mainly for cleaning the brake disc.

[0069] Using the proposed method, it is possible to minimize the activation of disc cleaning application by predicting the use of friction braking in upcoming braking events. Brake disc cleaning is only performed if the required deceleration level of the vehicle is predicted to be sufficiently high (exceeding a predetermined value) and therefore high braking energy is expected in the upcoming braking event. Thus, unnecessary use of friction brakes can be minimized.

[0070] From a study of the accompanying drawings, disclosure, and appended claims, those skilled in the art can understand and implement other variations of the disclosed examples in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" and "an" do not exclude multiple. A single processor or other unit can perform the functions of several items or steps recited in the claims. The fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously. Computer programs can be stored / distributed on suitable media, such as optical storage media or solid-state media provided with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems. Any reference marks in the claims should not be construed as limiting the scope of the claims.

[0071] Reference tag list

[0072] 10. Central Module

[0073] 100 Environmental Observation Units

[0074] 101 Driver Behavior Information Unit

[0075] 102 Brake Disc Model

[0076] 200 Braking Control Module

[0077] 201 Motor Unit

[0078] S1-S3 steps of the S1-S3 method

Claims

1. A method for cleaning the brake disc of a vehicle that is at least partially electrically driven, the vehicle comprising a braking system having at least one friction brake, the surface of which is capable of contacting a corresponding brake disc. The method includes: - Determine the upcoming braking event of the at least partially electrically powered vehicle by using at least the information of the vehicle ahead. -Predict the required deceleration level of the at least partially electrically driven vehicle by using the information about the vehicle ahead in combination with at least one of adaptive regenerative braking force and driver behavior information, and - Brake disc cleaning of the friction brake of the at least partially electrically driven vehicle shall be performed only if the predicted deceleration level required by the at least partially electrically driven vehicle in the upcoming braking event is above a predetermined value and the braking energy required in the upcoming braking event is above the predicted braking energy required for brake disc cleaning.

2. The method of claim 1, wherein the information about the vehicle ahead includes at least one of the time gap with the vehicle ahead, the predicted required deceleration, and the required braking energy.

3. The method according to claim 1 or 2, wherein the prediction of the required deceleration level of the at least partially electrically driven vehicle is performed by the following steps: - Determine a safe distance from the vehicle ahead, and - Calculate the adaptive regenerative braking force, and - The required braking force is determined based on the mass of the at least partially electrically driven vehicle and the estimated road load, and - Determine the required braking energy and braking power.

4. The method according to claim 1 or 2, wherein a braking event is triggered when at least one of the following conditions is met: - The adaptive regenerative braking force exceeds a predetermined level and / or rate. - The determined speed difference between the at least partially electrically powered vehicle and the vehicle in front exceeds a predetermined speed. - The accelerator pedal release rate exceeded the predetermined value, and - The braking torque requested by the driver exceeds the predetermined value.

5. The method according to claim 1 or 2, where single-pedal drive is applicable, requires that at least one of the following conditions be met: - The adaptive regenerative braking force exceeds a predetermined level and / or rate. - The determined speed difference between the at least partially electrically powered vehicle and the vehicle in front exceeds a predetermined speed. - The accelerator pedal position is lower than the predetermined value, and - The driver's required braking torque rate exceeds the predetermined value.

6. A computer-readable storage medium storing computer program elements configured to, when executed by a processor, implement the method according to any one of claims 1 to 5.

7. An electric vehicle that is at least partially electrically powered, comprising: - One or more units configured to acquire information about vehicles ahead. - One or more units configured to acquire vehicle information of the at least partially electrically powered vehicle, and - At least one control unit configured to implement the method according to any one of claims 1 to 5.

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