Speed control based on brake temperature

Abstract

The speed control process limits the speed of the vehicle to ensure that the brake can decelerate the vehicle without overheating. The speed control process includes estimating a current temperature of the at least one brake. The speed control process then calculates a speed limit of the vehicle at which, for example, the brake does not exceed the maximum temperature when the brake is applied to decelerate the vehicle to stop. The speed control process may limit the vehicle at or below a speed limit by setting a motor torque limit.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 374,218, filed on August 31, 2022, the entire disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates to a process of controlling the speed of a vehicle. More specifically, the process of controlling the speed may be based on an estimation of the brake capacity of the vehicle. Background Art

[0004] Vehicle brakes slow down the vehicle through friction between the brake pads and the rotor of the vehicle. When braking, kinetic energy is converted into heat energy. Therefore, when the vehicle brakes heavily, repeatedly, and / or for a long time, heat may accumulate and overheat the brakes. The brakes of an overheated vehicle may cause brake attenuation due to the loss or reduction of friction between the brake pads and the rotor. If allowed to reach a certain temperature, the brakes may also suffer irreversible damage. Therefore, when the vehicle is traveling at high speeds and / or for a long time, brake attenuation or permanent brake damage may occur, and the brakes may not work as expected and slow the vehicle within the expected time and distance. Accurately understanding the brake capacity without explicit sensors can reduce costs and design complexity. In addition, preemptive control speed based on estimates or predictions of brake capacity can improve user safety by notifying and taking action to limit potentially dangerous situations associated with attenuated braking performance or loss of function. Summary of the invention

[0005] The present disclosure generally relates to a process of controlling the speed of a vehicle. More specifically, various embodiments of the present disclosure relate to a process of controlling the speed of a vehicle based on brake temperature estimation.

[0006] One aspect relates to a method for controlling the speed of a vehicle based on braking capacity, the method comprising estimating a current temperature of a brake of the vehicle. The brake may have a maximum operating temperature. The method further comprises determining a thermal margin of the brake and determining a speed limit of the vehicle. The speed limit may be based at least in part on the thermal margin. The method may further comprise imposing a speed limit on the vehicle.

[0007] A variation of the above aspect is where determining the speed limit includes determining a road condition for the vehicle.

[0008] A variation of the above aspect is where the brake is the warmest brake of the vehicle at the time of the temperature estimation.

[0009] A variation of the above aspect is where the thermal margin includes an amount of thermal energy that, if absorbed by the brake, would increase the temperature of the brake from a current temperature to a maximum operating temperature.

[0010] A variation of the above aspect also includes determining a torque limit for an electric machine of the vehicle. The torque limit may be based at least in part on a speed limit. The method also includes applying a torque limit to the vehicle.

[0011] A variation of the above aspect is where determining a speed limit for the vehicle includes estimating a current temperature, determining a thermal margin, and determining a speed limit based at least in part on the thermal margin of each brake of the vehicle; and selecting a lowest speed limit as the speed limit for the vehicle.

[0012] A variation on the above aspect is where the current temperature of the vehicle's brakes is estimated based at least in part on pressure data of the brakes and / or a current speed of the vehicle.

[0013] Another aspect relates to a system for controlling vehicle speed based on braking capability. The system includes a processor configured to estimate a current temperature of a brake of the vehicle, the brake having a maximum operating temperature. The processor may be configured to also determine a thermal margin of the brake and determine a speed limit for the vehicle. The speed limit may be based at least in part on the thermal margin. The processor may be configured to also impose a speed limit on the vehicle.

[0014] A variation of the above aspect is where the thermal margin includes an amount of thermal energy that, if absorbed by the brake, would increase the temperature of the brake from a current temperature to a maximum operating temperature.

[0015] A variation of the above aspect is where the processor is configured to determine a torque limit for an electric machine of the vehicle. The torque limit is based at least in part on a speed limit. The processor is further configured to also apply a torque limit to the vehicle.

[0016] A variation of the above aspect also includes where calculating the torque limit includes determining a road condition for the vehicle.

[0017] A variation of the above aspect is where the brake is the warmest brake of the vehicle at the time of the temperature estimation.

[0018] A variation of the above aspect is where the processor is further configured to estimate the current temperature, determine a thermal margin, and determine a speed limit based at least in part on the thermal margin of each brake of the vehicle; and select the lowest speed limit as the speed limit for the vehicle.

[0019] A variation on the above aspect is where the current temperature of the vehicle's brakes is estimated based at least in part on pressure data of the brakes and / or a current speed of the vehicle.

[0020] Another aspect relates to a method for controlling the speed of a vehicle based on braking capacity, the method comprising estimating a current temperature of a brake of the vehicle. The brake may have a maximum operating temperature. The method further comprises determining a thermal margin of the brake and determining a torque limit of the vehicle. The torque limit may be based at least in part on the thermal margin. The method may further comprise applying a torque limit to an electric machine.

[0021] A variation of the above aspect is where determining the torque limit includes determining a road condition for the vehicle.

[0022] A variation of the above aspect is where the brake is the warmest brake of the vehicle at the time of the temperature estimation.

[0023] A variation of the above aspect is where the thermal margin includes an amount of thermal energy that, if absorbed by the brake, would increase the temperature of the brake from a current temperature to a maximum operating temperature.

[0024] A variation of the above aspect is where determining a speed limit for the vehicle includes estimating a current temperature, determining a thermal margin, and determining a speed limit based at least in part on the thermal margin of each brake of the vehicle; and selecting a lowest speed limit as the speed limit for the vehicle.

[0025] A variation on the above aspect is where the current temperature of the vehicle's brakes is estimated based at least in part on pressure data of the brakes and / or a current speed of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure is described with reference to the accompanying drawings, wherein like reference characters refer to like elements, and in which:

[0027] Figure 1 is an exemplary graph showing a mapping of torque limits according to speed limits and brake temperatures.

[0028] Figure 2 is based on Figure 1 An exemplary graph of FIG. 1 is shown with a torque-speed line at a temperature of 25° C. and a torque-speed line at a temperature of 500° C. added.

[0029] Figure 3 is based on Figure 2 An exemplary graph of , wherein an envelope is formed between the three lines.

[0030] Figure 4 Exemplary simulation results are shown for recording time-temperature at different temperature limits and different test profiles.

[0031] Figure 5 Exemplary simulation results for recording time-velocity at different temperature limits and different test profiles are shown.

[0032] Figure 6 Exemplary simulation results are shown recording time-torque at different temperature limits and different test profiles.

[0033] Figure 7 A block diagram illustrating an exemplary speed control system according to the present disclosure is shown.

[0034] Figure 8 A flow chart illustrating an exemplary speed control process according to the present disclosure is shown. DETAILED DESCRIPTION

[0035] In general, one or more aspects of the present disclosure relate to a process of controlling the speed of a vehicle. In certain embodiments, the present disclosure relates to a process of controlling the speed of a vehicle based on brake temperature estimates. The process of controlling the speed may include using a thermal model to estimate the brake temperature. The brake thermal model may be different for different vehicles with different weights, structures, and acceleration / braking mechanisms. In some embodiments, the brake thermal model may provide an estimate of the brake temperature without a temperature sensor. The brake thermal model may provide information about the thermal margin or thermal capacity remaining in the vehicle's braking system. For example, the brake temperature estimate from the brake thermal model may be used to calculate the thermal margin, or the amount of thermal energy required to keep each brake above its maximum temperature (e.g., the temperature at which the brake may decay or fail).

[0036] The speed control process may also include using the vehicle model to determine a maximum speed that the vehicle can reach when the brakes are at a certain temperature. Within or at the maximum speed limit, the vehicle brakes may be actuated to safely decelerate the vehicle without fading or losing the ability to generate friction (e.g., without reaching or exceeding a maximum temperature at which the brakes may fade or fail). In some embodiments, as Figure 7 As illustrated, the vehicle model may employ a speed control system 100 using vehicle model data 110. In some embodiments, the vehicle model data 110 may include brake pressure data 112 and vehicle speed data 114 for the vehicle. The processing component 120 may use the vehicle model data 110 to calculate the thermal capacity and convert the thermal capacity into a maximum vehicle speed specific to the vehicle.

[0037] For example, in Figure 8During the exemplary speed control process shown, when the vehicle is traveling at a certain speed, the processing component 120 of the speed control system 100 can use the thermal model to estimate the current brake temperature in step 1002. In step 1004, in some embodiments, the processing component 120 of the speed control system 100 can use the current estimated brake temperature and other data of the specific vehicle model from the vehicle model data 110 (e.g., the thermal capacity of the brakes) to calculate the thermal capacity of the brake system (e.g., the amount of thermal energy required to make each brake exceed its maximum temperature). Then in step 1006, in some embodiments, the speed control system 100 can then use the vehicle model data 110 data from the vehicle model (e.g., the mass of the vehicle) to convert the thermal capacity into a maximum vehicle speed.

[0038] In some embodiments, in step 1008, the processing component 120 of the speed control system 100 may also calculate an operating limit (e.g., a torque limit of a vehicle engine or motor) that may limit the vehicle to a determined speed limit. For example, in some embodiments, the vehicle may be limited to traveling at or below the speed limit as long as the motor is controlled to apply a torque that does not exceed the torque limit. In some embodiments, the speed control system 100 may also include a control component 130 that may be configured to receive and implement operating limits to control the speed of the vehicle, for example, by controlling the vehicle engine or motor in step 1010. The calculation of operating limits may also depend on many variables, such as the condition or inclination of the road on which the vehicle is traveling. In some embodiments, the speed control process may also include determining a torque limit using road slope information. For example, when the vehicle is traveling on a flat road, a lower torque limit may be set to limit the vehicle to a certain speed limit.

[0039] In some embodiments, speed control system 100 may also be implemented on a vehicle having a regenerative braking system by using a set of vehicle data and calculations specific to the regenerative braking system.

[0040] The vehicle may include brakes on each drive axle (e.g., front and rear brakes). In some embodiments, the speed control process may be calculated based on the estimated temperature of all brakes of the vehicle and then a minimum speed limit may be imposed to ensure that none of the brakes fade or lose functionality. In some embodiments, the speed control process may be calculated based on the highest estimated temperature of all brakes. In some embodiments, the highest estimated temperature is used for the brakes on the front axle. In some embodiments, the highest estimated temperature is used for the brakes on the rear axle. In some embodiments, the speed control process may be calculated based only on the estimated temperature of the brakes on the front axle. In other embodiments, the speed control process may be calculated based on estimates or predictions of other capabilities of one or more brakes of the vehicle.

[0041] Figure 1-3 is an exemplary chart mapping torque limit according to speed limit and brake temperature, where X is speed, Y is temperature, and Z is torque limit. Figure 1 Line 10 in illustratively illustrates how the torque limit may correspond to the speed limit and brake temperature of a particular vehicle model under certain conditions using a speed control process according to the present disclosure. For example, when the vehicle's brakes are estimated to be at a temperature of Y2°C, the vehicle may be limited to being at or below X2mph. At or below Z2mph, the remaining capacity or capability of the brake system is sufficient to safely stop the vehicle. In order to maintain a speed of Z2mph, the vehicle may limit the torque output of the motor to Z2Nm. That is, according to Figure 1 , applying a speed control process under certain conditions, when the estimated brake temperature is Y2°C, the vehicle can be configured to operate at a Z2Nm torque limit, traveling at a speed of X2mph or less. The flat portion of line 10 with a constant Z value (e.g., at Z3Nm) corresponds to the torque value required to maintain the corresponding speed limit of the vehicle. In some embodiments, the flat portion corresponds to a range of temperatures and speeds where no torque limit is actually applied according to the speed control process. Figure 1 It is illustrated that in some embodiments, the speed control process may use the function represented by line 10 to determine speed and / or torque limits based on brake temperature.

[0042] Figure 2 is based on Figure 1 , an exemplary system-level torque-speed line 20 at a brake temperature of Y4°C (e.g., 500°C) and an exemplary torque-speed line 30 at a temperature of Y5°C (e.g., 25°C) are added to form the limits of the torque output limit envelope. The flat portions of lines 20 and 30 with constant Z values ​​(e.g., Z4Nm for line 20 and Z5Nm for line 30) correspond to the torque values ​​required to maintain the corresponding speed limits of the vehicle. In certain embodiments, the flat portions correspond to a range of temperatures and speeds where no torque limit is actually applied according to the speed control process. In some embodiments, line 20 is added at a brake temperature of 500°C because at a brake temperature of 500°C, the remaining capacity or capacity of the brake system is sufficient to safely stop the vehicle from the maximum speed of the vehicle. In some embodiments, lines 20 and 30 may be added at temperatures of 600°C and 0°C. In other embodiments, lines 20 and 30 may be added at any other desired temperature based on various considerations and factors (e.g., different brake materials, vehicle conditions, and road conditions).

[0043] Figure 3 is based on Figure 2, where envelope 40 is formed by continuously blending lines 20 and 30 to line 10. Envelope 40 may define the torque limit for each speed and brake temperature coordinate. Figure 3 It is illustrated that in some embodiments, the speed control process may use the functions represented by lines 10 , 20 , 30 and envelope 40 to determine speed and / or torque limits based on brake temperature.

[0044] Figure 4-6 are exemplary simulation results performed at different temperature limits and different test distributions. Figure 4 The simulation results recording time-temperature are shown. Figure 5 The simulation results of recording time-velocity are shown. Figure 6 The simulation results of recording time-torque are shown. Figure 4-6 As shown, the speed control process can be used with different temperature limits (such as the maximum brake temperature that is considered allowable) and different test profiles (such as adjusting the speed from 0 mph to 134 mph and back to 0 mph, as shown in FIG. Figure 4-6 ) to test and fine-tune.

[0045] like Figure 4 As shown, each graph shows a line where the temperature or y value does not exceed a preset temperature limit (e.g., 800°C, 850°C, etc.) These results may indicate that the implemented speed control process is effective in controlling the brake temperature below the preset allowable temperature limit of the brake.

[0046] like Figure 5 As shown, each graph shows a line with speeds or y values ​​corresponding to the speeds specified by the test profile (e.g., 0-134-0 mph, 50-80-50 mph, etc.) These results can indicate that the implemented speed control process is effective in controlling the speed limit below the determined speed limit of the vehicle.

[0047] like Figure 6 As shown, each graph shows a maximum torque line 100 recording the maximum torque allowed at the current brake temperature and speed, a torque limit line 200 recording the torque limit determined by the speed control process at the brake temperature and speed, and an actual torque line 300 recording the actual applied torque. These results show the torque actual line 300 under the torque limit line 200 under the maximum torque line 100, and these results can indicate that the implemented speed control process effectively controls the speed under different temperature limits and test profiles while implementing the torque limit determined by the speed control process.

[0048] In certain embodiments, the speed control process may include determining and communicating a preferred front and rear brake bias to improve thermal performance. The front and rear brakes of a vehicle typically operate at different pressures due to their different roles, configurations, and locations in the vehicle. By adjusting the braking force ratio between the front and rear brakes (e.g., brake bias), the overall braking efficiency may be maximized. The preferred front and rear brake bias may be informed by the speed control process, for example, by determining the maximum allowable temperature of the front and rear brakes, the torque applied to the front and rear brakes, and related information.

[0049] The foregoing disclosure is not intended to limit the disclosure to the precise form or specific field disclosed. Therefore, it is contemplated that various alternative embodiments and / or modifications to the disclosure, whether explicitly described or implied herein, are possible in light of the present disclosure. Having thus described the embodiments of the disclosure, it will be appreciated by those of ordinary skill in the art that changes may be made in form and detail without departing from the scope of the disclosure. Therefore, the disclosure is limited only by the claims.

[0050] In the foregoing description, the present disclosure has been described with reference to specific embodiments. However, as will be appreciated by those skilled in the art, the various embodiments disclosed herein may be modified or implemented in various other ways without departing from the spirit and scope of the present disclosure. Therefore, the description is considered to be illustrative and is intended to teach those skilled in the art to make and use the various embodiments of the disclosed process of controlling speed. It should be understood that the disclosed forms shown and described herein will be considered as representative embodiments. Equivalent elements, materials, processes or steps may replace those representatively shown and described herein. In addition, certain features of the present disclosure may be utilized independently of the use of other features, all of which are obvious to those skilled in the art who benefit from the description of the present disclosure. Expressions such as "including", "comprising", "incorporating", "consisting of", "having", "is" used to describe and claim the present disclosure are intended to be interpreted in a non-exclusive manner, i.e., to allow for the presence of items, components or elements that are not explicitly described. References to the singular should also be interpreted as involving the plural.

[0051] In addition, various embodiments disclosed herein are used for illustration and explanation purposes, and shall not be interpreted as control of the present disclosure.All joint words quote (such as attachment (attached), paste (affixed), coupling (coupled), connection (connected) etc.) are only used to help readers understand the present disclosure, and will not cause limitation, particularly about the position, orientation or use of system and / or method disclosed herein.Therefore, if any, joint words quote and should be interpreted broadly.In addition, this type of joint words quote and does not necessarily mean that two elements are directly connected to each other.In addition, all numerical terms, such as but not limited to "first (first)", "second (second)", "third (third)", "primary (primary)", "secondary (secondary)", "main (main)" or any other common and / or numerical terms, also should only be regarded as identifiers, to help readers understand various elements, embodiments, changes and / or modifications of the present disclosure, and can not cause any limitation, particularly about relative to or exceed another element, embodiment, change and / or modification any element, embodiment, change and / or modification order or preference.

[0052] It should also be appreciated that one or more of the elements shown in the drawings / figures may also be implemented in a more separate or integrated manner, or even removed or rendered inoperable in some cases, as may be useful depending on the particular application.

Claims

1. A method for controlling the speed of a vehicle based on braking capability, the method comprising: estimating a current temperature of brakes of the vehicle, the brakes having a maximum operating temperature; determining a thermal margin of the brake; determining a speed limit for the vehicle, the speed limit based at least in part on the thermal margin; as well as The speed limit is imposed to control the speed of the vehicle.

2. The method of claim 1 , wherein determining the speed limit comprises: A road condition for the vehicle is determined. 3 . The method of claim 1 , wherein the brake is the warmest brake of the vehicle at the time of temperature estimation. 4 . The method of claim 1 , wherein the thermal margin comprises an amount of thermal energy that, if absorbed by the brake, would increase the temperature of the brake from the current temperature to the maximum operating temperature.

5. The method according to claim 1, further comprising: determining a torque limit for an electric machine of the vehicle, the torque limit being based at least in part on the speed limit; as well as The torque limit is imposed on the vehicle.

6. The method of claim 1 , wherein determining the speed limit of the vehicle comprises: estimating a current temperature, determining a thermal margin, and determining a speed limit based at least in part on the thermal margin for each brake of the vehicle; And the lowest speed limit is selected as the speed limit for the vehicle. 7 . The method of claim 1 , wherein the current temperature of the brakes of the vehicle is estimated at least in part based on pressure data of the brakes and / or a current speed of the vehicle.

8. A system for controlling the speed of a vehicle based on braking capability, the system comprising: A processor, the processor being configured to: estimating a current temperature of the brake of the vehicle, the brake having a maximum operating temperature; determining a thermal margin of the brake; determining a speed limit for the vehicle, the speed limit based at least in part on the thermal margin; as well as The speed limit is imposed to control the speed of the vehicle.

9. The speed control system of claim 6, wherein the thermal margin comprises an amount of thermal energy that, if absorbed by the brake, would increase the temperature of the brake from the current temperature to the maximum operating temperature.

10. The speed control system of claim 6, wherein the processor is configured to: determining a torque limit for an electric machine of the vehicle, the torque limit being based at least in part on the speed limit; and The torque limit is imposed on the vehicle.

11. The speed control system of claim 6, wherein calculating the torque limit comprises: A road condition for the vehicle is determined.

12. The speed control system of claim 6, wherein said brake is the warmest brake of said vehicle at the time of temperature estimation.

13. The speed control system of claim 8, wherein the processor is further configured to: estimate a current temperature, determine a thermal margin, and determine a speed limit based at least in part on the thermal margin of each brake of the vehicle; and select a lowest speed limit as the speed limit for the vehicle.

14. The speed control system of claim 8, wherein the current temperature of the brakes of the vehicle is estimated based at least in part on pressure data of the brakes and / or a current speed of the vehicle.

15. A method for controlling the speed of a vehicle based on braking capability, the method comprising: estimating a current temperature of brakes of the vehicle, the brakes having a maximum operating temperature; determining a thermal margin of the brake; determining a torque limit for an electric machine of the vehicle, the torque limit based at least in part on the thermal margin; as well as The torque limit is applied to limit the speed of the motor.

16. The method of claim 15, wherein determining the torque limit comprises: A road condition for the vehicle is determined.

17. The method of claim 15, wherein the brake is the warmest brake of the vehicle at the time of temperature estimation.

18. The method of claim 15, wherein the thermal margin comprises an amount of thermal energy that, if absorbed by the brake, would increase the temperature of the brake from the current temperature to the maximum operating temperature.

19. The method of claim 15, wherein determining the speed limit of the vehicle comprises: estimating a current temperature, determining a thermal margin, and determining a speed limit based at least in part on the thermal margin for each brake of the vehicle; And the lowest speed limit is selected as the speed limit for the vehicle.

20. The method of claim 15, wherein the current temperature of the brakes of the vehicle is estimated based at least in part on pressure data of the brakes and / or a current speed of the vehicle.

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