Brake pedal feel calibration method and system for an electro-hydraulic brake-by-wire system

Abstract

The application provides a kind of electronic hydraulic brake-by-wire system brake pedal feel calibration method, including in electronic hydraulic brake-by-wire system, periodically detecting the piston displacement amount and pedal lever displacement amount driven by built-in driving permanent magnet synchronous motor;If the piston displacement amount driven by built-in driving permanent magnet synchronous motor is less than the pedal lever displacement amount in the current cycle detection, then the pedal lever displacement amount detected in the current cycle is divided into a predetermined number, and the corresponding built-in driving permanent magnet synchronous motor assistance of each divided pedal lever displacement amount in the current cycle is calibrated by a preset calibration function.The application also provides a kind of electronic hydraulic brake-by-wire system brake pedal feel calibration system.

Description

Technical Field

[0001] This invention relates to the field of vehicle braking technology, and in particular to a method and system for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system. Background Technology

[0002] Currently, the brake pedal feel of traditional fuel-powered vehicles' vacuum braking systems is determined by their mechanical structure, making it impossible to calibrate the brake pedal feel once production begins. With the increasing popularity of new energy vehicles, electro-hydraulic brake-by-wire systems, which use electric power instead of vacuum assistance, are becoming more widely used in the braking systems of new energy electric vehicles. This makes it possible to calibrate the brake pedal feel to meet customer needs for different brake pedal sensations.

[0003] However, existing electro-hydraulic brake-by-wire systems require the design of a brake feel simulator to calibrate the brake feel, making the calibration process complex, difficult, and costly. Therefore, it is necessary to improve the existing brake feel calibration method for electro-hydraulic brake-by-wire systems, enabling calibration without a brake feel simulator, thus simplifying the calibration process and reducing costs. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a method and system for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system, which simplifies the difficulty of brake pedal feel calibration and reduces calibration costs.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a method for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system, the method comprising the following steps:

[0006] In the electro-hydraulic linear control braking system, the displacement of the piston and the displacement of the pedal driven by the built-in permanent magnet synchronous motor are periodically detected.

[0007] If the piston displacement driven by the built-in permanent magnet synchronous motor is less than the pedal displacement in the current cycle, the pedal displacement detected in the current cycle is divided into equal parts according to a predetermined number. Then, the built-in permanent magnet synchronous motor assist corresponding to each equal part of the pedal displacement in the current cycle is calibrated by a preset calibration function.

[0008] The method further includes:

[0009] Based on the preset relationship function between the pedal and the pedal force, the pedal force corresponding to each equal segment of the pedal displacement in the current cycle is obtained, and the pressure output to the brake caliper by the calibrated built-in drive permanent magnet synchronous motor in the current cycle is obtained. This pressure is then compared with the pedal force corresponding to each equal segment of the pedal displacement in the current cycle, and the calibration completion degree of the built-in drive permanent magnet synchronous motor is determined based on the comparison results.

[0010] The steps for determining the calibration completion rate of the built-in drive permanent magnet synchronous motor based on the comparison results include:

[0011] If it is determined that the pressure output to the brake caliper by the calibrated built-in permanent magnet synchronous motor in the current cycle is consistent with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, then the calibration of the built-in permanent magnet synchronous motor assist is considered complete; conversely, if it is determined that the pressure output to the brake caliper by the calibrated built-in permanent magnet synchronous motor in the current cycle is inconsistent with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, then the calibration of the built-in permanent magnet synchronous motor assist is considered incomplete.

[0012] The built-in drive permanent magnet synchronous motor assistance is calibrated by the magnitude of the operating current of the built-in drive permanent magnet synchronous motor.

[0013] The calibration function is F. L =fun(x) pi ); where F L To assist the built-in permanent magnet synchronous motor, x pi Let x be the displacement of the pedal in the i-th equal division, and fun() be the displacement of the pedal in any equal division. pi With built-in drive permanent magnet synchronous motor assist F L A linear interpolation function between [two points].

[0014] This invention also provides a brake pedal feel calibration system for an electro-hydraulic brake-by-wire system, comprising:

[0015] The displacement detection unit is used to periodically detect the displacement of the piston and the pedal rod driven by the built-in permanent magnet synchronous motor in the electro-hydraulic wire control braking system.

[0016] The brake pedal feel calibration unit is used to, if the piston displacement driven by the built-in drive permanent magnet synchronous motor is less than the pedal displacement in the current cycle, divide the pedal displacement detected in the current cycle into a predetermined number of equal parts, and then calibrate the built-in drive permanent magnet synchronous motor assist corresponding to each equal part of the pedal displacement in the current cycle through a preset calibration function.

[0017] This also includes:

[0018] The calibration completion judgment unit is used to obtain the pedal force corresponding to each equal segment of pedal displacement in the current cycle according to the preset relationship function between pedal and pedal force, and to obtain the pressure output to the brake caliper by the calibrated built-in drive permanent magnet synchronous motor in the current cycle. It further compares the pressure with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, and judges the calibration completion of the built-in drive permanent magnet synchronous motor based on the comparison results.

[0019] The built-in drive permanent magnet synchronous motor assistance is calibrated by the magnitude of the operating current of the built-in drive permanent magnet synchronous motor.

[0020] The calibration function is F. L =fun(x) pi ); where F L To assist the built-in permanent magnet synchronous motor, x pi Let x be the displacement of the pedal in the i-th equal division, and fun() be the displacement of the pedal in any equal division. pi With built-in drive permanent magnet synchronous motor assist F L A linear interpolation function between [two points].

[0021] Implementing the embodiments of the present invention has the following beneficial effects:

[0022] This invention periodically compares the piston displacement driven by the built-in permanent magnet synchronous motor with the pedal displacement. After dividing the pedal displacement that is smaller than the piston displacement driven by the built-in permanent magnet synchronous motor into equal parts, the corresponding built-in permanent magnet synchronous motor assist is quickly calibrated through a preset calibration function, thereby simplifying the difficulty of brake pedal feel calibration and reducing calibration costs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0024] Figure 1 This is a schematic diagram of the structure of an electro-hydraulic brake-by-wire system in a method for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system provided in an embodiment of the present invention.

[0025] Figure 2 A flowchart of a method for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system provided in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of a brake pedal feel calibration system for an electro-hydraulic brake-by-wire system provided in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0028] The inventor discovered that, as Figure 1 As shown, the electro-hydraulic brake-by-wire system consists of a motor controller, a permanent magnet synchronous motor, transmission gears, push rods, a reservoir, and brake calipers. This electro-hydraulic brake-by-wire system receives brake pedal signals or target hydraulic command signals from the vehicle controller, driving the built-in permanent magnet synchronous motor. The motor rotates a certain angle through a position ring, and simultaneously pushes the push rod through the reduction gears, further pushing the reservoir piston, causing the brake fluid to act on the brake pumps in the four wheels of the vehicle. The brake circuit generates brake hydraulic pressure, thereby stopping the vehicle.

[0029] At this time, when the built-in permanent magnet synchronous motor drives the piston to displace by x e Greater than the displacement of the pedal x p At that time, the pedal force F p This is equal to the sum of the preload and elastic force of the pedal's built-in spring 1, and the damping force of the mechanical system itself. Therefore, the static force balance equation on the pedal can be obtained, expressed as:

[0030] F p =k p *(x e -x p )+F0(1);

[0031] In equation (1), k p F0 and F0 are the spring constant and preload of the pedal lever's built-in spring 1, respectively.

[0032] Therefore, the pedal force F at this stage can be seen. p This is determined by the mechanical structure, which makes it impossible to calibrate the brake pedal feel.

[0033] Similarly, when the built-in permanent magnet synchronous motor drives the piston to displace x... e Less than the displacement of the pedal x p At that time, the built-in permanent magnet synchronous motor assists F L With pedal force F p The piston is pushed by the combined forces of the preload and elastic force of the pedal lever's spring 1, the system's own damping force, and the preload and elastic force of the piston push rod's spring 2. Therefore, the force balance equation for the piston in a static state can be obtained as follows:

[0034] F p +F L=k0*x p +F mc (2);

[0035] In equation (2), k0 is the elastic coefficient of the piston push rod's built-in spring 2, and F mc This is the reaction force of hydraulic pressure acting on the piston.

[0036] Therefore, it can be seen that the built-in drive permanent magnet synchronous motor assists F in this stage. L It can be based on the displacement of the pedal x p The calibration is performed to calibrate the brake pedal feel. The calibration function is F. L =fun(x) p ); fun() is the displacement x of the pedal. p With built-in drive permanent magnet synchronous motor assist F L The linear interpolation function between them. Therefore, based on formula (2), the inventors designed a new method for calibrating the brake pedal feel of an electronic hydraulic brake-by-wire system.

[0037] like Figure 2 As shown, this is an embodiment of the present invention, illustrating a method for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system proposed by the inventors. This method is relevant to the electro-hydraulic brake-by-wire system (see details for the specific structure). Figure 1 Implemented on a connected system, the method includes the following steps:

[0038] Step S1: In the electro-hydraulic linear control braking system, periodically detect the displacement of the piston and the pedal rod driven by the built-in permanent magnet synchronous motor.

[0039] Step S2: If the piston displacement driven by the built-in permanent magnet synchronous motor is less than the pedal displacement in the current cycle, the pedal displacement detected in the current cycle is divided into equal parts according to a predetermined number, and the built-in permanent magnet synchronous motor assist corresponding to each equal part of the pedal displacement in the current cycle is calibrated by a preset calibration function.

[0040] Step S3: Based on the preset relationship function between pedal and pedal force, obtain the pedal force corresponding to each equal segment of pedal displacement in the current cycle, and obtain the pressure output to the brake caliper by the calibrated built-in drive permanent magnet synchronous motor in the current cycle. Further compare it with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, and determine the calibration completion degree of the built-in drive permanent magnet synchronous motor based on the comparison results.

[0041] The specific process is as follows: In step S1, in the electro-hydraulic linear brake system, through... Figure 1 The motor controller in the middle realizes the displacement x of the piston driven by the built-in permanent magnet synchronous motor. e The acquisition, and through Figure 1 The pedal displacement sensor in the middle realizes the measurement of the pedal displacement x p The data is obtained and periodically (e.g., every 5 seconds) is checked on both.

[0042] In step S2, if the built-in permanent magnet synchronous motor drives the piston to displace by x in the current cycle... e < pedal displacement x p Then the pedal displacement measured in the current cycle will be x p After dividing the material into equal parts according to a predetermined quantity (e.g., n equal parts), (to be counted as x) p1 x p2 , , , , x pn ), through the aforementioned preset calibration function F L =fun(x) p This calibrates the built-in permanent magnet synchronous motor assist corresponding to each equal division of the pedal displacement in the current cycle, i.e., F. L =fun(x) pi It should be noted that the built-in drive permanent magnet synchronous motor assists F. L The calibration can be performed by measuring the operating current of the built-in permanent magnet synchronous motor.

[0043] In step S3, by Figure 1 The standard for determining whether the target calibration has been completed is whether the pressure displayed by the pressure sensor matches the pedal force of the target braking feel curve. It should be noted that the target braking feel curve is set by a target function relationship between the pedal displacement and the preset pedal force, meaning that the corresponding pedal force can be tracked in real time through the pedal displacement.

[0044] Therefore, firstly, based on the preset relationship function between the pedal and the pedal force, the pedal force corresponding to each equal division of the pedal displacement in the current cycle is obtained.

[0045] Secondly, obtain the pressure output to the brake caliper by the calibrated built-in drive permanent magnet synchronous motor during the current cycle.

[0046] Finally, the pressure output to the brake caliper by the built-in drive permanent magnet synchronous motor in each equal part of the current cycle is compared with the corresponding pedaling force to determine the calibration completion of the built-in drive permanent magnet synchronous motor assist.

[0047] At this point, if it is determined that the pressure output to the brake caliper by the calibrated built-in permanent magnet synchronous motor in the current cycle is consistent with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, then the calibration of the built-in permanent magnet synchronous motor assist is considered complete; conversely, if it is determined that the pressure output to the brake caliper by the calibrated built-in permanent magnet synchronous motor in the current cycle is inconsistent with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, then the calibration of the built-in permanent magnet synchronous motor assist is considered incomplete.

[0048] like Figure 3 As shown in the embodiment of the present invention, a brake pedal feel calibration system for an electro-hydraulic brake-by-wire system includes:

[0049] The displacement detection unit 110 is used to periodically detect the displacement of the piston and the pedal rod driven by the built-in permanent magnet synchronous motor in the electro-hydraulic linear control braking system.

[0050] The brake pedal feel calibration unit 120 is used to calibrate the pedal displacement detected in the current cycle by dividing the pedal displacement detected in the current cycle into a predetermined number of equal parts and then using a preset calibration function to calibrate the pedal displacement corresponding to each equal part of the pedal displacement in the current cycle.

[0051] This also includes:

[0052] The calibration completion judgment unit 130 is used to obtain the pedal force corresponding to each equal segment of pedal displacement in the current cycle according to the preset relationship function between pedal and pedal force, and to obtain the pressure output to the brake caliper by the calibrated built-in drive permanent magnet synchronous motor in the current cycle. It further compares the pressure with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, and judges the calibration completion of the built-in drive permanent magnet synchronous motor based on the comparison result.

[0053] The built-in drive permanent magnet synchronous motor assistance is calibrated by the magnitude of the operating current of the built-in drive permanent magnet synchronous motor.

[0054] The calibration function is F. L =fun(x) pi ); where F L To assist the built-in permanent magnet synchronous motor, x pi Let x be the displacement of the pedal in the i-th equal division, and fun() be the displacement of the pedal in any equal division. pi With built-in drive permanent magnet synchronous motor assist F L A linear interpolation function between [two points].

[0055] Implementing the embodiments of the present invention has the following beneficial effects:

[0056] This invention periodically compares the piston displacement driven by the built-in permanent magnet synchronous motor with the pedal displacement. After dividing the pedal displacement that is smaller than the piston displacement driven by the built-in permanent magnet synchronous motor into equal parts, the corresponding built-in permanent magnet synchronous motor assist is quickly calibrated through a preset calibration function, thereby simplifying the difficulty of brake pedal feel calibration and reducing calibration costs.

[0057] It is worth noting that in the above system embodiments, the various units are divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional unit are only for easy distinction between each other and are not used to limit the scope of protection of the present invention.

[0058] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, optical disk, etc.

[0059] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system, characterized in that, The method includes the following steps: In the electro-hydraulic linear control braking system, the displacement of the piston and the displacement of the pedal driven by the built-in permanent magnet synchronous motor are periodically detected. If the piston displacement driven by the built-in permanent magnet synchronous motor is less than the pedal displacement in the current cycle, the pedal displacement detected in the current cycle is divided into equal parts according to a predetermined number, and the built-in permanent magnet synchronous motor assist corresponding to each equal part of the pedal displacement in the current cycle is calibrated by a preset calibration function. The method further includes: Based on the preset relationship function between pedal and pedal force, the pedal force corresponding to each equal segment of pedal displacement in the current cycle is obtained, and the pressure output to the brake caliper by the calibrated built-in drive permanent magnet synchronous motor in the current cycle is obtained. This pressure is then compared with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, and the calibration completion of the built-in drive permanent magnet synchronous motor is determined based on the comparison results. The calibration function is: F L =fun(x pi ) ;in, F L It provides power to the built-in permanent magnet synchronous motor. x pi For the first i The displacement of the pedal is divided into equal parts. fun() For any equal division of the pedal displacement x pi With built-in drive permanent magnet synchronous motor assist F L A linear interpolation function between [two points].

2. The method for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system as described in claim 1, characterized in that, The steps for determining the calibration completion rate of the built-in drive permanent magnet synchronous motor based on the comparison results include: If it is determined that the pressure output to the brake caliper by the calibrated built-in permanent magnet synchronous motor in the current cycle is consistent with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, then the calibration of the built-in permanent magnet synchronous motor assist is considered complete; conversely, if it is determined that the pressure output to the brake caliper by the calibrated built-in permanent magnet synchronous motor in the current cycle is inconsistent with the pedal force corresponding to each equal segment of pedal displacement in the current cycle, then the calibration of the built-in permanent magnet synchronous motor assist is considered incomplete.

3. The method for calibrating the brake pedal feel of an electro-hydraulic brake-by-wire system as described in claim 2, characterized in that, The built-in drive permanent magnet synchronous motor assist is calibrated by the magnitude of the operating current of the built-in drive permanent magnet synchronous motor.

4. A brake pedal feel calibration system for an electro-hydraulic brake-by-wire system, characterized in that, include: The displacement detection unit is used to periodically detect the displacement of the piston and the pedal rod driven by the built-in permanent magnet synchronous motor in the electro-hydraulic wire control braking system. The brake pedal feel calibration unit is used to calibrate the pedal displacement detected in the current cycle by dividing the pedal displacement detected in the current cycle into a predetermined number of equal parts and then using a preset calibration function to calibrate the pedal displacement corresponding to each equal part of the pedal displacement in the current cycle. Also includes: The calibration completion judgment unit is used to obtain the pedal force corresponding to each equal part of the pedal displacement in the current cycle according to the preset relationship function between the pedal and the pedal force, and to obtain the pressure output to the brake caliper by the calibrated built-in drive permanent magnet synchronous motor in the current cycle. It further compares the pressure with the pedal force corresponding to each equal part of the pedal displacement in the current cycle, and judges the calibration completion of the built-in drive permanent magnet synchronous motor based on the comparison results. The calibration function is: F L =fun(x pi ) ;in, F L It provides power to the built-in permanent magnet synchronous motor. x pi For the first i The displacement of the pedal is divided into equal parts. fun() For any equal division of the pedal displacement x pi With built-in drive permanent magnet synchronous motor assist F L A linear interpolation function between [two points].

5. The brake pedal feel calibration system for an electro-hydraulic brake-by-wire system as described in claim 4, characterized in that, The built-in drive permanent magnet synchronous motor assist is calibrated by the magnitude of the operating current of the built-in drive permanent magnet synchronous motor.

Images