Caliper clamping force estimation method based on short-stroke pressure sensor

Abstract

The invention discloses a caliper clamping force estimation method based on a short-stroke pressure sensor, and belongs to the technical field of automobile EMB control, and the method comprises the following steps: S1, disc contact estimation: arranging the short-stroke pressure sensor at a four-wheel EMB, measuring a disc contact point through the short-stroke pressure sensor, and recording the contact point as a zero point position; s2, on the basis of data measured by a short-stroke pressure sensor, a curve of actually measured clamping force and clamping stroke in a measuring range is constructed, and rigidity is calculated; s3, according to the measured data of the actual brake clamping force and the clamping stroke, a stroke-clamping force estimated value curve graph of the whole vehicle four-wheel EMB system is constructed; and S4, taking the measured contact point as the zero point of the stroke in S3 again, and obtaining a curve graph of the stroke-clamping force estimated value again. The short-stroke pressure sensor is used, the cost is reduced, errors are reduced, the risk of the whole vehicle is reduced, safety is improved, the clamping force is estimated based on the disc contact points, and more stable and efficient clamping force estimation is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile EMB control, and in particular to a caliper clamping force estimation method based on a short-stroke pressure sensor. Background Art

[0002] An electronic mechanical caliper (EMB) uses an electric motor as a power source and a reduction mechanism (gear set, ball screw, etc.) to achieve a large caliper clamping force. This allows the caliper to have sufficient clamping force to brake the vehicle's wheels by tightening the brake disc.

[0003] To achieve precise control of clamping force, most current solutions on the market use force sensors to obtain feedback and then implement clamping force control based on control theory. However, having a force sensor at each wheel end can be costly for the entire system. Traditional clamping force estimation methods in the industry are mostly based on motor position sensors and the stiffness of EMB products. This approach introduces the risk of errors (due to varying temperatures, friction pad wear, and transmission wear). Especially when all four factors have certain errors, there is a risk of loss of deceleration or loss of stability due to excessive braking deviation. Summary of the Invention

[0004] The purpose of the present invention is to provide a caliper clamping force estimation method based on a short-stroke pressure sensor to solve the problem that the use of a full-range pressure sensor is high in cost, and the estimation only from the EMB wheel end without using a pressure sensor will have an error risk, especially when all four have certain errors, the whole vehicle will lose deceleration, or the braking deviation will be too large, resulting in the loss of stability of the whole vehicle.

[0005] Technical solution: The present invention provides a method for estimating the clamping force of a caliper based on a short-stroke pressure sensor, comprising the following steps: S1 disc contact estimation: short-stroke pressure sensors are set on the four-wheel EMBs to measure the disc contact point and record the contact point as the zero point. Based on the measurement data of the short-stroke pressure sensor, S2 constructs a curve of the measured clamping force and clamping stroke within the measuring range and calculates the stiffness; S3 constructs a curve diagram of the estimated value of the travel-clamping force of the four-wheel EMB system of the vehicle based on the measured data of the actual brake clamping force and clamping stroke; S4 uses the measured contact point as the zero point of the stroke in S3 to obtain a curve diagram of the stroke-clamping force estimation value.

[0006] Furthermore, in the above-mentioned caliper clamping force estimation method based on a short-stroke pressure sensor, the measuring range of the short-stroke pressure sensor in S1 is 0-Force_min. When the feedback value of the short-stroke pressure sensor is greater than a certain threshold Force_touch, it can be determined that the disc is in contact, thereby measuring the disc contact point.

[0007] Furthermore, in the above-mentioned method for estimating the caliper clamping force based on a short-stroke pressure sensor, the Force_min is far lower than the clamping force range required by the caliper.

[0008] Furthermore, in the above-mentioned method for estimating the caliper clamping force based on a short-stroke pressure sensor, in order to make the obtained clamping force estimation value more accurate in step S2, step S2 can be repeated multiple times to achieve consistency between the clamping force and the external standard force sensor, so that the data is more accurate and general.

[0009] Furthermore, in the above-mentioned method for estimating the caliper clamping force based on a short-stroke pressure sensor, the step S2 further includes the following steps: S21 rig estimation starts. When the short-stroke pressure sensor data F_FB is less than a certain threshold F_touch_min, the motor control pushes the ball screw forward; S22: When the motor controls and pushes the ball screw forward until the short-stroke pressure sensor value F_FB is greater than the threshold value F_touch and the duration is greater than a certain threshold value T_touch_hold, the position at this time is recorded and marked as zero position P_touch. At the same time, the motor continues to push the ball screw; S23: When the value of the full-stroke pressure sensor set outside the test bench is greater than the maximum clamping force F_caliper_max of the caliper design, the motor controls the ball screw to retract until it reaches the P_touch position, records the value of the short-stroke pressure sensor at this time, and assigns F_touch_back = F_FB; S24 calculates |F_touch-F_touch_back| < threshold F_touch_tolence, locks the disc contact point P_touch, and obtains a stiffness curve diagram of the stroke and the clamping force after contact; S25 The motor position control continues to retreat to a certain threshold of the disc gap P_Disc_Pad_tolence, and the estimation ends.

[0010] Furthermore, in the above-mentioned caliper clamping force estimation method based on a short-stroke pressure sensor, the S21-S25 estimation process is repeated multiple times, and different temperatures and different friction plate wear conditions are added to calculate the clamping force estimation compensation value, so that the value is more accurate.

[0011] Furthermore, in the above-mentioned caliper clamping force estimation method based on a short-stroke pressure sensor, the threshold Force_touch, threshold F_touch_min, threshold F_touch, threshold T_touch_hold, threshold F_touch_tolence, and threshold P_Disc_Pad_tolence are all set according to specific vehicle conditions.

[0012] Furthermore, in the above-mentioned caliper clamping force estimation method based on a short-stroke pressure sensor, the short-stroke pressure sensor is used to measure the clamping force between the friction pad and the brake disc.

[0013] Furthermore, in the above-mentioned method for estimating the caliper clamping force based on a short-stroke pressure sensor, the electronic mechanical caliper in S1-S4 includes a brake disc, a friction plate, a ball screw assembly, and a short-stroke pressure sensor. The brake disc is arranged between the friction plates, and there is a gap between the brake disc and the friction plate. The friction plate is connected to the ball screw assembly, and a short-stroke pressure sensor is arranged on the inner side of the ball screw assembly.

[0014] Furthermore, in the above-mentioned caliper clamping force estimation method based on a short-stroke pressure sensor, the gap between the brake disc and the friction plates on both sides is in the range of 0.1-0.5 mm.

[0015] It can be seen from the above technical solution that the caliper clamping force estimation method based on the short-stroke pressure sensor described in the present invention has the following beneficial effects: 1) Cost savings: from requiring a full-range pressure sensor to requiring only a short-stroke pressure sensor, the manufacturing and accuracy requirements for the pressure sensor supplier are much lower, resulting in lower costs; 2) Low risk. If all four EMBs have no pressure sensors, there will be a problem of large errors, resulting in excessive or insufficient braking force, or even the risk of the entire vehicle losing stability. 3) Good stability, does not conflict with other EMB stiffness estimation methods, and estimates the clamping force based on a more accurate EMB disc contact point, providing more stable and efficient clamping force estimation; 4) Good safety, based on the temperature information compensation of the short-stroke pressure sensor, the data is more accurate and safer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of a caliper clamping force estimation method based on a short-stroke pressure sensor according to the present invention; Figure 2 This is a schematic flow chart of step S2 of the present invention; Figure 3 This is a schematic diagram of a stroke-clamping force estimation curve of the present invention; Figure 4This is a schematic diagram of the installation structure of the electronic mechanical caliper of the present invention.

[0017] In the figure: friction plate 1, brake disc 2, ball screw assembly 3, short-stroke pressure sensor 4. DETAILED DESCRIPTION Example

[0018] like Figure 1 A caliper clamping force estimation method based on a short-stroke pressure sensor is shown, comprising the following steps: S1 disc contact estimation: short-stroke pressure sensors are set on the four-wheel EMBs to measure the disc contact point and record the contact point as the zero point. Based on the measurement data of the short-stroke pressure sensor, S2 constructs a curve of the measured clamping force and clamping stroke within the measuring range and calculates the stiffness; S3 constructs a curve diagram of the estimated value of the travel-clamping force of the four-wheel EMB system of the vehicle based on the measured data of the actual brake clamping force and clamping stroke; S4 uses the measured contact point as the zero point of the stroke in S3 to obtain a curve diagram of the stroke-clamping force estimation value.

[0019] like Figure 3 A caliper clamping force estimation method based on a short-stroke pressure sensor is shown in the figure. The three curves shown in the figure are all stroke-clamping force curves: The blue one is obtained from bench testing and is the standard curve; The orange color is obtained from the vehicle test and is the actual curve; The green curve is obtained by shifting the orange curve to the left by 0.12mm (0.12mm is the contact point between the friction plate and the brake disc); like Figure 4 The electronic mechanical caliper installation structure shown in the figure has a short-stroke pressure sensor 4 used to measure the clamping force between the friction plate 1 and the brake disc 2. Under non-braking conditions, there is a disc gap of about 0.2-0.4mm. The short-stroke pressure sensor 4 is used to measure the clamping force between the friction plate and the brake disc. When the disc is not in contact, the reading of the short-stroke pressure sensor 4 is 0. After the disc contacts, as the clamping continues, the ball screw assembly 3 continues to control the compression of the friction plate 1. At this time, it can be concluded that Figure 3 The stroke-clamping force curve is shown.

[0020] As can be seen from the figure, the green curve closely matches the standardized blue curve obtained from the bench test, indicating a very small error between the two. This suggests that, for clamping force estimation, measuring the contact point between the friction pad and the brake disc and resetting that contact point to the zero point of the curve will result in a stroke-clamping force curve that has only a small error compared to the standard curve, leading to a much more accurate clamping force estimate.

[0021] In this embodiment, the electronic mechanical caliper in S1-S4 includes a friction plate 1, a brake disc 2, a ball screw assembly 3, and a short-stroke pressure sensor 4. The brake disc 2 is arranged between the friction plates 1, and there is a gap between the brake disc 2 and the friction plate 1. The friction plate 1 is connected to the ball screw assembly 3, and a short-stroke pressure sensor 4 is arranged on the inner side of the ball screw assembly 3.

[0022] like Figure 1 A caliper clamping force estimation method based on a short-stroke pressure sensor is shown. The measuring range of the short-stroke pressure sensor in S1 is 0-Force_min. When the feedback value of the short-stroke pressure sensor is greater than a certain threshold Force_touch, it can be determined that the disc is in contact, thereby measuring the disc contact point; the Force_min is far lower than the clamping force range required by the caliper (such as 45KN, 65KN, etc.).

[0023] Example 2 On the basis of Example 1, in this embodiment, as Figure 1 The method for estimating the clamping force of a caliper based on a short-stroke pressure sensor is shown. In order to make the estimated clamping force value obtained in step S2 more accurate, step S2 can be repeated multiple times to achieve consistency between the clamping force and the external standard force sensor, making the data more accurate and general.

[0024] like Figure 2 In the method for estimating the clamping force of a caliper based on a short-stroke pressure sensor, the step S2 further includes the following steps: S21 rig estimation starts. When the short-stroke pressure sensor data F_FB is less than a certain threshold F_touch_min, the motor control pushes the ball screw forward; S22: When the motor controls and pushes the ball screw forward until the short-stroke pressure sensor value F_FB is greater than the threshold value F_touch and the duration is greater than a certain threshold value T_touch_hold, the position at this time is recorded and marked as zero position P_touch. At the same time, the motor continues to push the ball screw; S23: When the value of the full-stroke pressure sensor set outside the test bench is greater than the maximum clamping force F_caliper_max of the caliper design, the motor controls the ball screw to retract until it reaches the P_touch position, records the value of the short-stroke pressure sensor at this time, and assigns F_touch_back = F_FB; S24 calculates |F_touch-F_touch_back| < threshold F_touch_tolence, locks the disc contact point P_touch, and obtains a stiffness curve diagram of the stroke and the clamping force after contact; S25 The motor position control continues to retreat to a certain threshold of the disc gap P_Disc_Pad_tolence, and the estimation ends.

[0025] In this embodiment, the estimation process of S21-S25 is repeated multiple times, and different temperatures and different friction plate wear conditions are added to calculate the clamping force estimation compensation value, so that the value is more accurate.

[0026] The threshold Force_touch, threshold F_touch_min, threshold F_touch, threshold T_touch_hold, threshold F_touch_tolence, and threshold P_Disc_Pad_tolence are all set according to specific vehicle conditions.

[0027] It should be noted that the above is merely a technical solution of the invention and is not intended to be limiting. Although the present invention has been described in detail with reference to preferred embodiments, it should be understood by those skilled in the art that the technical solution of the invention may be modified or replaced with equivalents without departing from the scope of the technical solution of the invention, and all such modifications or equivalents should be encompassed by the claims of the present invention.

Claims

1. A caliper clamping force estimation method based on a short-stroke pressure sensor, characterized in that The following steps are involved: S1 disc contact estimation: short-stroke pressure sensors are set on the four-wheel EMBs to measure the disc contact point and record the contact point as the zero point. Based on the measurement data of the short-stroke pressure sensor, S2 constructs a curve of the measured clamping force and clamping stroke within the measuring range and calculates the stiffness; S3 constructs a curve diagram of the estimated value of the travel-clamping force of the four-wheel EMB system of the vehicle based on the measured data of the actual brake clamping force and clamping stroke; S4 uses the measured contact point as the zero point of the stroke in S3 to obtain a curve diagram of the stroke-clamping force estimation value.

2. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 1, characterized in that: The measuring range of the short-stroke pressure sensor in S1 is 0-Force_min. When the feedback value of the short-stroke pressure sensor is greater than a certain threshold Force_touch, it can be determined that the disk is in contact, thereby measuring the disk contact point.

3. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 2, characterized in that: The Force_min is much lower than the clamping force range required by the caliper.

4. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 1, characterized in that: In order to make the estimated value of the clamping force obtained in step S2 more accurate, step S2 can be repeated multiple times to ensure that the clamping force is consistent with the external standard force sensor, making the data more accurate and general.

5. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 1, characterized in that: The S2 further comprises the following steps: S21 rig estimation starts. When the short-stroke pressure sensor data F_FB is less than a certain threshold F_touch_min, the motor control pushes the ball screw forward; S22: When the motor controls and pushes the ball screw forward until the short-stroke pressure sensor value F_FB is greater than the threshold value F_touch and the duration is greater than a certain threshold value T_touch_hold, the position at this time is recorded and marked as zero position P_touch. At the same time, the motor continues to push the ball screw; S23: When the value of the full-stroke pressure sensor set outside the test bench is greater than the maximum clamping force F_caliper_max of the caliper design, the motor controls the ball screw to retract until it reaches the P_touch position, records the value of the short-stroke pressure sensor at this time, and assigns F_touch_back = F_FB; S24 calculates |F_touch-F_touch_back| < threshold F_touch_tolence, locks the disc contact point P_touch, and obtains a stiffness curve diagram of the stroke and the clamping force after contact; S25 The motor position control continues to retreat to a certain threshold of the disc gap P_Disc_Pad_tolence, and the estimation ends.

6. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 1, characterized in that: The estimation process of S21-S25 is repeated multiple times, and different temperatures and different friction plate wear conditions are added to calculate the clamping force estimation compensation value, so that the value is more accurate.

7. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 4, characterized in that: The threshold Force_touch, threshold F_touch_min, threshold F_touch, threshold T_touch_hold, threshold F_touch_tolence, and threshold P_Disc_Pad_tolence are all set according to specific vehicle conditions.

8. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 1, characterized in that: The short-stroke pressure sensor is used to measure the clamping force between the friction pad and the brake disc.

9. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 1, characterized in that: The electronic mechanical caliper in S1-S4 includes a brake disc, a friction plate, a ball screw assembly, and a short-stroke pressure sensor. The brake disc is arranged between the friction plates, with a gap between the brake disc and the friction plates. The friction plate is connected to the ball screw assembly, and a short-stroke pressure sensor is arranged on the inner side of the ball screw assembly.

10. The method for estimating caliper clamping force based on a short-stroke pressure sensor according to claim 9, characterized in that: The gap between the brake disc and the friction plates on both sides is in the range of 0.1-0.5 mm.

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