Automatic compensation method and system for detecting brake pedal feeling based on PV

Abstract

The invention provides an automatic compensation method and system for detecting brake pedal feeling based on PV. Brake loop pressure P is detected in real time through a hydraulic sensor, the state of a vehicle is judged through EHB, micro pressure buildup is actively conducted when conditions are met, the liquid demand V of a brake is indirectly calculated, and then the PV of the vehicle brake is calculated. Then the detected PV data is transmitted to an ECU for processing, the ECU compares the actual PV data of the vehicle with standard PV data, calculates the needed compensation amount, establishes a model according to the compensation amount, calls the relation between the brake pedal stroke of the EHB software after compensation and the pressure P and the pressure buildup rate through analysis and table lookup, achieves the consistent brake pedal feeling through compensation, and achieves the purpose of braking the vehicle. And the braking reliability and the driving safety and comfort are improved.

Description

Technical Field

[0001] The present invention relates to a field, and in particular to a method and system for automatically compensating brake pedal feel based on PV detection. Background Art

[0002] Drum brakes are the predominant braking solution for commercial light trucks (light trucks). Their core advantages lie in their simple structure, low manufacturing and maintenance costs, and high braking torque output. Compared to disc brakes, drum brakes require a smaller drum diameter to achieve the same braking torque, making this compact design particularly well-suited to the spatial requirements of medium- and heavy-duty trucks. However, in practice, drum brakes have significant technical limitations: due to production process constraints, achieving high consistency in the clearance between the drum and the shoe is difficult. This clearance directly affects the PV characteristics (Pressure, Volume) of the braking system. Specifically, increasing the brake clearance significantly increases the PV value. This, combined with the dispersion caused by factors such as the discrete friction coefficient of the shoe and the attenuation of the brake drum's performance, ultimately leads to significant variations in PV characteristics between different vehicles.

[0003] This PV difference is directly reflected in the dynamic response of the braking system: vehicles with higher PV values require longer brake fluid pressure build-up times, resulting in a soft braking experience for the driver; conversely, vehicles with lower PV values build pressure too quickly, resulting in an overly sensitive brake response and a tendency to cause sudden braking. This nonlinear pedal feedback difference not only reduces the consistency of the driving experience but, more importantly, can cause the driver to misjudge braking effectiveness under emergency braking conditions, seriously impacting driving safety. Existing technology systems suffer from two drawbacks: First, traditional clearance control relies on manual feeler gauge measurement, which can only obtain single-point clearance data at a local position on the brake. Measurement accuracy is significantly affected by operator experience, and the screening process is time-consuming, labor-intensive, and inefficient. Second, existing brake assist systems lack intelligent adjustment capabilities and are unable to adaptively compensate for the differences in pedal feel caused by different PV characteristics, making it difficult for the system to balance the contradiction between braking response speed and handling comfort. Summary of the Invention

[0004] In response to the defects in the prior art, the purpose of the present invention is to provide a method and system for automatic compensation of brake pedal feel based on PV detection, which adaptively adjusts the brake pedal feel by real-time detection of the brake hydraulic pressure and required fluid volume to achieve a braking experience with consistent pedal feel.

[0005] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0006] According to a first aspect of the present invention, a method for automatically compensating brake pedal feel based on PV detection is provided, comprising the following steps:

[0007] S1. Vehicle status verification: When the system receives a PV detection command, it detects the vehicle's current speed, acceleration, and power-on status parameters in real time. PV detection is initiated when the vehicle speed = 0, acceleration = 0, the vehicle is powered off, and the ECU is in a power-off sleep state and operating normally.

[0008] S2. After the vehicle status is verified, the EHB system is controlled to perform a micro-pressure buildup operation, establishing a brake system pressure of 1 bar to eliminate the gap between the brake drum and the brake shoe;

[0009] S3.ECU calculates the actual PV value of the current braking system, including:

[0010] S3.1 During the micro-pressure buildup process, the brake system pressure is monitored in real time via the hydraulic sensor. When the pressure reaches 1 bar, the current brake system pressure value P is recorded.

[0011] S3.2 The ECU calculates the required brake fluid volume V to build up a 1-bar pressure based on the number of motor revolutions corresponding to 1 bar and the displacement of the master cylinder caused by the rack and pinion.

[0012] S3.3 Calculate the actual PV value of the current braking system based on the current pressure value P and the required fluid volume V of the braking system;

[0013] S4. The ECU compares the actual PV value of the brake system with the standard PV value and determines the deviation state based on the deviation range of the required fluid volume V. The preset standard PV value is 1 bar pressure corresponding to 10 ml fluid volume:

[0014] For the actual PV value, when the pressure is 1 bar, if V∈[10.5,15]ml, it is judged as a large PV, indicating a decrease in the pressure build-up rate; if V∈[8,9.5]ml, it is judged as a small PV, indicating an abnormal increase in the pressure build-up rate; if V>15.5ml or V<8ml, it is judged as a seriously large or seriously small PV, triggering an instrument panel alarm;

[0015] S5. Establish a pedal feel model and calculate the compensation amount based on the actual PV value and the standard PV value;

[0016] S6. Adjust pedal feel based on the calculated compensation amount and pedal feel model. Analyze and retrieve the relationship between the compensated EHB software brake pedal travel, pressure P, and pressure build rate from a table. Compensation adjustment is performed through coefficient calculation to ultimately achieve a consistent brake pedal feel.

[0017] S6. Data solidification: Save the adjusted PV value to the Flash memory for recall the next time the vehicle is powered on.

[0018] Optionally, if it is detected that the wheel speed is not equal to 0, the system voltage is abnormal, or there is a sign of leakage, the PV detection is terminated.

[0019] Optionally, after the vehicle is powered off, the ECU enters a dormant state with a delay of 1 minute through software, and completes PV detection and data storage during the delay period; when the KL15 wake-up voltage of the ECU is 0, the constant power KL30 maintains power supply.

[0020] Optionally, the calculation of the required fluid volume V in the above step S3.2 includes: multiplying the cross-sectional area of the master cylinder by the displacement S of the master cylinder piston to obtain V by calculation.

[0021] Optionally, the method according to claim 1 is characterized in that in step S4: when V>15.5ml, it is determined that the braking response is seriously too slow; when V<8ml, it is determined that there is a risk of braking drag.

[0022] Optionally, the compensation adjustment in step S5 includes: when the PV is too large, the pressure building rate is accelerated according to the coefficient calculation compensation, and the pressure building time is shortened so that the total time is the same as the standard PV; when the PV is too small, the pressure building rate is slowed down according to the coefficient calculation compensation, and the pressure building time is lengthened so that the total time is the same as the standard PV.

[0023] According to a second aspect of the present invention, a system for automatically compensating brake pedal feel based on PV detection is provided, which adopts the above-mentioned method for automatically compensating brake pedal feel based on PV detection, comprising:

[0024] Hydraulic sensor module for real-time monitoring of brake system pressure;

[0025] The motor drive module controls the rack and pinion to push the piston of the master cylinder;

[0026] ECU, integrating PV value calculation, deviation determination, compensation algorithm and pedal feel adjustment mechanism;

[0027] Flash memory, stores standard PV values and corrected compensation parameters.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The method and system provided by the present invention detect brake clearance and apply an adaptive compensation algorithm to perform real-time dynamic compensation, thereby achieving a consistent brake pedal feel, ensuring a stable braking effect, and improving driving safety and comfort.

[0030] 2. The method and system provided by the present invention are implemented through software algorithms, without the need for complex mechanical structure adjustments or hydraulic system optimization. They can be easily integrated into existing brake systems, reducing manual adjustment costs and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0032] Figure 1 This is a flow chart of the method for automatically compensating brake pedal feel based on PV detection described in the first embodiment. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0035] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures. In addition, all directional indications in this application (such as up, down, left, right, front, back, bottom...) are only used to explain the relative position relationship, movement, etc. between the components under a specific posture (as shown in the figures). If the specific posture changes, the directional indication will also change accordingly. Furthermore, the descriptions of "first", "second", etc. in the application are for descriptive purposes only and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0036] First embodiment

[0037] like Figure 1 As shown, this embodiment provides a method for automatically compensating brake pedal feel based on PV detection. By detecting the brake hydraulic pressure and required fluid volume in real time, the brake pedal feel is adaptively adjusted to achieve a consistent braking experience. The method specifically includes the following steps:

[0038] Step S1. After the system issues a PV test command, the EHB electronic hydraulic brake system monitors the vehicle's current speed, acceleration, power-on status, and other parameters in real time, and determines whether the vehicle's current state meets the PV test conditions. If the wheel speed is not equal to zero, the system voltage is abnormal, or there are signs of leakage, the PV test process is terminated. PV testing is only performed when the vehicle's state meets the preset PV test conditions. The preset PV test conditions are: PV testing is initiated when the vehicle speed and acceleration are zero, the vehicle is powered off, and the ECU is operating normally during its power-off sleep period. The ECU is powered by the normally powered KL30. After the vehicle is powered off, software design (postrun) delays the ECU's sleep period by one minute. During this one-minute period, the PV test is completed, and the detected PV data is saved and written to the flash memory.

[0039] Step S2. After the vehicle status verification is completed and the vehicle status meets the PV detection conditions, the EHB system actively builds up a pressure of 1 bar to eliminate the gap between the brake drum and the shoe (the driver is not aware of it).

[0040] Step S3. Detect and calculate the actual PV value of the current brake;

[0041] Step S3.1 During the EHB system micro-pressure buildup process, the hydraulic sensor monitors the brake system pressure P in real time until the brake system hydraulic pressure reaches 1 bar, and transmits the actual brake system pressure value P when the system pressure reaches 1 bar to the electronic control unit (ECU).

[0042] Step S3.2 The ECU calculates the required brake fluid volume V for 1 bar pressure buildup based on the number of motor revolutions corresponding to the micro-pressure buildup of 1 bar and the displacement S of the master cylinder piston pushed by the gear rack. The calculation is then done by multiplying the cross-sectional area of the master cylinder by the displacement of the master cylinder piston.

[0043] Step S3.3: The ECU calculates the actual PV value of the current braking system based on the current actual braking system pressure value P and the required fluid volume V for 1 bar of pressure buildup calculated in steps S3.1 and S3.2.

[0044] Step S4: Compare the actual PV value calculated in step S3 with the standard PV value stored in the ECU (preset 1 bar corresponds to 10 ml), and determine the PV deviation type according to the table below.

[0045] Hydraulic P Liquid volume V PV type Performance 1bar 10ml Standard PV Normal brake pedal feel 1bar 10.5-15ml Large PV To establish 1 bar requires more liquid, the motor needs to rotate more times, the pressure build rate becomes slower, and the pressure build time becomes longer. 1bar 8-9.5ml Small PV Less fluid is needed to establish 1 bar, the motor needs to rotate fewer times, the pressure build-up rate becomes faster, and the pressure build-up time becomes shorter. 1bar >15.5ml or <8ml Severely oversized or severely undersized The braking response is too slow or the braking is too sensitive or there is lag, which needs to trigger the instrument panel alarm

[0046] Step S5. Establish a pedal feel model and calculate the compensation amount: In order to provide a consistent pedal feel, the system establishes a pedal feel model and calculates the compensation amount based on the actual PV deviation.

[0047] Step S6: Pedal feel is adjusted based on the calculated compensation amount and the pedal feel model. The relationship between the compensated EHB software brake pedal travel, pressure P, and pressure build rate is retrieved through table analysis. The compensated pressure build rate is calculated based on a coefficient to ensure that the braking system's response matches the driver's input and provides a consistent brake pedal feel. Specifically, for larger PVs, the pressure build rate is accelerated based on the coefficient, shortening the pressure build time to match the standard PV. For smaller PVs, the pressure build rate is slowed based on the coefficient, lengthening the pressure build time to match the standard PV.

[0048] Step S7: Save the adjusted PV data to the Flash memory for direct use the next time the vehicle is powered on.

[0049] Second embodiment

[0050] This embodiment provides a system for automatically compensating brake pedal feel based on PV detection, which is used to implement the method for automatically compensating brake pedal feel based on PV detection in the first embodiment, including:

[0051] Hydraulic sensor module for real-time monitoring of brake system pressure;

[0052] The motor drive module is used to control the rack and pinion to push the piston of the master cylinder;

[0053] ECU, integrating PV value calculation, deviation determination, adaptive compensation algorithm and pedal feel adjustment mechanism;

[0054] Flash memory is used to store standard PV values and corrected compensation parameters.

[0055] The above describes the specific embodiments of the present invention. Based on the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical concept of this invention.

Claims

1. A method for automatically compensating brake pedal feel based on PV detection, characterized in that: The following steps are involved: S1. Vehicle status verification: When the system receives a PV detection command, it detects the vehicle's current speed, acceleration, and power-on status parameters in real time. PV detection is initiated when the vehicle speed = 0, acceleration = 0, the vehicle is powered off, and the ECU is in a power-off sleep state and operating normally. S2. After the vehicle status is verified, the EHB system is controlled to perform a micro-pressure buildup operation, establishing a brake system pressure of 1 bar to eliminate the gap between the brake drum and the brake shoe; S3.ECU calculates the actual PV value of the current braking system, including: S3.1 During the micro-pressure buildup process, the brake system pressure is monitored in real time via the hydraulic sensor. When the pressure reaches 1 bar, the current brake system pressure value P is recorded. S3.2 The ECU calculates the required brake fluid volume V to build up a 1-bar pressure based on the number of motor revolutions corresponding to 1 bar and the displacement of the master brake cylinder as converted by the rack and pinion. S3.3 Calculate the actual PV value of the current braking system based on the current pressure value P and the required fluid volume V of the braking system; S4. The ECU compares the actual PV value of the brake system with the standard PV value and determines the deviation state based on the deviation range of the required fluid volume V. The preset standard PV value is 1 bar pressure corresponding to 10 ml fluid volume: For the actual PV value, when the pressure is 1 bar, if V∈[10.5,15]ml, it is judged as a large PV, indicating a decrease in the pressure build-up rate; if V∈[8,9.5]ml, it is judged as a small PV, indicating an abnormal increase in the pressure build-up rate; if V>15.5ml or V<8ml, it is judged as a seriously large or seriously small PV, triggering an instrument panel alarm; S5. Establish a pedal feel model and calculate the compensation amount based on the actual PV value and the standard PV value; S6. Adjust pedal feel based on the calculated compensation amount and pedal feel model. Analyze and retrieve the relationship between the compensated EHB software brake pedal travel, pressure P, and pressure build rate from a table. Compensation adjustment is performed through coefficient calculation to ultimately achieve a consistent brake pedal feel. S6. Data solidification: Save the adjusted PV value to the Flash memory for next vehicle power-on call.

2. The automatic compensation method for brake pedal feel based on PV detection according to claim 1, characterized in that: If the wheel speed is not equal to 0, the system voltage is abnormal, or there is leakage, the PV test is terminated.

3. The automatic compensation method for brake pedal feel based on PV detection according to claim 1, characterized in that: After the vehicle is powered off, the ECU enters a dormant state after a delay of 1 minute through software, and completes PV detection and data storage during the delay period; when the KL15 wake-up voltage of the ECU is 0, the constant power KL30 maintains power supply.

4. The automatic compensation method for brake pedal feel based on PV detection according to claim 1, characterized in that: The calculation of the required fluid volume V in the above step S3.2 includes: multiplying the cross-sectional area of the master cylinder by the displacement S of the master cylinder piston to obtain V.

5. The automatic compensation method for brake pedal feel based on PV detection according to claim 1, characterized in that: The method according to claim 1 is characterized in that in step S4: when V>15.5ml, it is determined that the braking response is seriously too slow; when V<8ml, it is determined that there is a risk of brake drag.

6. The automatic compensation method for brake pedal feel based on PV detection according to claim 1, characterized in that: The compensation adjustment in step S5 includes: when the PV is too large, the pressure build-up rate is accelerated according to the coefficient calculation compensation, and the pressure build-up time is shortened so that the total time is the same as the standard PV; when the PV is too small, the pressure build-up rate is slowed down according to the coefficient calculation compensation, and the pressure build-up time is lengthened so that the total time is the same as the standard PV.

7. A brake pedal feel automatic compensation system based on PV detection, characterized in that: The method for automatically compensating brake pedal feel based on PV detection according to any one of claims 1 to 6 comprises: Hydraulic sensor module for real-time monitoring of brake system pressure; The motor drive module controls the rack and pinion to push the piston of the master cylinder; ECU, integrating PV value calculation, deviation determination, compensation algorithm and pedal feel adjustment mechanism; Flash memory, stores standard PV values and corrected compensation parameters.

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