Method for testing a brake caliper

Abstract

The application provides a test method of a brake caliper, comprising: assembling a brake caliper to be tested to a vibration device, and connecting a piston working chamber of the brake caliper to be tested to a hydraulic pipeline; performing vibration test on the brake caliper to be tested by the vibration device, detecting a brake fluid change amount in the hydraulic pipeline at the end of the vibration test; increasing vibration energy of the vibration device and repeatedly performing the vibration test until a step change of the brake fluid change amount is detected; and obtaining a piston anti-knock capacity value of the brake caliper to be tested according to vibration energy corresponding to the step change. The application dynamically simulates whole vehicle road conditions by using the vibration device and the hydraulic pipeline, accurately monitors a critical point of piston anti-knock in the process of increasing vibration energy and repeatedly performing the vibration test through the brake fluid change amount, overcomes the problem that experimental test is disconnected from whole vehicle road conditions, can accurately and efficiently evaluate piston anti-knock capacity, and reduces dependence on whole vehicle road test, development cost and risk.

Description

Technical Field

[0001] This application relates to the field of braking technology, and more specifically, to a test method for brake calipers. Background Technology

[0002] Brake caliper knockback refers to the phenomenon where road vibrations or other factors cause the brake disc to strike the brake caliper piston, pushing the piston back into the caliper cylinder. Knockback can create an abnormal gap between the piston and the brake disc, resulting in the driver feeling a longer pedal travel and needing to press the pedal deeper to achieve braking the next time they brake.

[0003] Currently, the assessment of brake caliper knockback mainly relies on two methods: experimental testing and vehicle road testing. However, experimental testing is mostly static testing, which cannot accurately simulate the actual road conditions of a vehicle; vehicle road testing is resource-intensive, costly, and time-consuming, and is mostly conducted in the mid-to-late stages of development, posing a significant risk of rework.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] This application provides a test method for brake calipers that can accurately, cost-effectively and efficiently evaluate the piston knockback resistance of brake calipers.

[0006] According to one aspect of this application, a method for testing a brake caliper is provided, comprising the following steps: assembling the brake caliper under test to a vibration device, and connecting the piston working chamber of the brake caliper under test to a hydraulic line; performing a vibration test on the brake caliper under test using the vibration device, and detecting the change in brake fluid in the hydraulic line at the end of the vibration test; increasing the vibration energy of the vibration device and repeating the vibration test until a step change in the brake fluid is detected; and obtaining the piston knockback resistance value of the brake caliper under test based on the vibration energy corresponding to the step change.

[0007] By utilizing vibration equipment and hydraulic lines, the road conditions of a complete vehicle can be dynamically simulated, overcoming the problem of disconnect between experimental testing and actual vehicle road conditions. The change in brake fluid measured at the end of each vibration test characterizes the displacement of the piston from its initial position after this vibration test. During the process of increasing vibration energy and repeating the vibration test, the critical point of piston anti-knockback is precisely monitored through the change in brake fluid. The critical point where the brake fluid change undergoes a step change can be identified by observing inflection points graphically, thus accurately obtaining the piston anti-knockback capability value of the tested brake caliper. Using the testing method of this application, piston anti-knockback capability can be accurately and efficiently evaluated, reducing reliance on complete vehicle road testing and lowering development costs and risks.

[0008] In some embodiments, the test method for brake calipers further includes the following steps: before the first vibration test, the hydraulic line is activated, and the flow rate of brake fluid required to push the piston of the brake caliper under test from the initial position to the working position is detected and recorded as the initial fluid requirement; after each vibration test, the hydraulic line is activated, and the flow rate of brake fluid required to push the piston of the brake caliper under test from the current position to the working position is detected and recorded as the test fluid requirement; when a step change in the amount of brake fluid is detected, the piston stroke difference of the brake caliper under test is obtained based on the difference between the test fluid requirement corresponding to the step change and the initial fluid requirement.

[0009] By measuring the required brake fluid volume, the piston displacement can be quantified and correlated with the degree of piston knockback. A step change in brake fluid volume indicates that the piston has knocked back under vibration testing. Based on the difference between the test required fluid volume corresponding to the step change and the initial required fluid volume, as well as the effective area of ​​the brake master cylinder in the hydraulic line, the piston stroke difference can be obtained. This difference characterizes the displacement of the piston of the brake caliper under test due to the vibration test corresponding to the step change, i.e., the degree of piston knockback.

[0010] In some embodiments, the vibration device can vibrate along the X-axis and / or Y-axis and / or Z-axis; when performing vibration testing on the brake caliper under test, the vibration device is controlled to vibrate along one or more coordinate axes to detect the piston anti-knockback capability value of the brake caliper under test along the one or more coordinate axes.

[0011] Vibration equipment can be used to simulate multi-directional vibrations of a vehicle during road testing, comprehensively assess the anti-knockback capability of the piston of the brake caliper under test in different directions, and improve the accuracy of the test.

[0012] In some embodiments, when performing a vibration test on the brake caliper under test, the vibration device is controlled to perform sinusoidal vibration according to set vibration parameters, the vibration parameters including vibration frequency, acceleration, and vibration time; increasing the vibration energy of the vibration device includes increasing the acceleration of the sinusoidal vibration by a set step size; obtaining the piston anti-backlash capability value of the brake caliper under test includes using the acceleration value of the sinusoidal vibration as the piston anti-backlash capability value of the brake caliper under test.

[0013] By utilizing sinusoidal vibration and vibration parameter control, vibration testing becomes standardized and repeatable, avoiding the uncertainties caused by random vibration. By increasing the acceleration of the sinusoidal vibration in predetermined steps, the vibration energy can be gradually increased to approach the critical point of piston knockback. This allows for accurate detection of step changes, ensuring the precision of the vibration test.

[0014] In some embodiments, a bidirectional flow meter is provided in the hydraulic pipeline; wherein the change in brake fluid is the cumulative net flow rate measured by the bidirectional flow meter during the vibration test, and the brake fluid flow rate is the cumulative positive flow rate measured by the bidirectional flow meter during the operation of the hydraulic pipeline; and the bidirectional flow meter is zeroed before each increase in the vibration energy of the vibration device.

[0015] Using a bidirectional flow meter allows for accurate measurement of minute, transiently changing brake fluid flow rates, enabling precise monitoring of piston knockback and overcoming the insufficient resolution of conventional flow meters. Furthermore, a zeroing operation ensures the independence of each vibration test, preventing cumulative errors.

[0016] In some embodiments, the working position is configured as the critical position at which the piston of the brake caliper under test begins to contact the brake disc; wherein, a pressure sensor is provided in the hydraulic line, and during the operation of the hydraulic line, the starting point at which the pressure value detected by the pressure sensor rises linearly is determined as the point at which the piston of the brake caliper under test reaches the working position.

[0017] Using a pressure sensor, it is possible to accurately determine whether the piston has reached the working position.

[0018] In some embodiments, activating the hydraulic line and detecting the brake fluid flow rate required to push the piston of the brake caliper under test from the initial position to the working position, and recording it as the initial required flow rate, includes: repeatedly activating the hydraulic line and detecting the brake fluid flow rate required to push the piston of the brake caliper under test from the initial position to the working position; if the fluctuation range of the brake fluid flow rate detected multiple times is less than a first threshold, the last detected brake fluid flow rate is recorded as the initial required flow rate.

[0019] Multiple measurements can reduce the impact of random fluctuations, ensure the accuracy of the initial fluid requirement, and confirm that the system has stabilized before vibration, thus guaranteeing accurate subsequent testing. During the initial fluid requirement testing process, the last measurement is closest to the vibration test, representing the precise initial state of the system just before the vibration test. Therefore, the brake fluid flow rate detected last is used as the initial fluid requirement.

[0020] In some embodiments, after the vibration test, the hydraulic line is activated, and the brake fluid flow rate required to push the piston of the brake caliper under test from its current position to the working position is detected and recorded as the test fluid requirement. This includes: after the vibration test ends and a certain period of time is waited, the steps of activating the hydraulic line and detecting the brake fluid flow rate required to push the piston of the brake caliper under test from its current position to the working position are repeated multiple times; if the fluctuation amplitude of the brake fluid flow rate detected multiple times is less than a second threshold, the brake fluid flow rate detected for the first time is recorded as the test fluid requirement.

[0021] After the vibration test, a waiting period is allowed for residual vibration to cease before the required brake fluid volume is measured. Multiple measurements reduce the impact of random fluctuations and ensure the accuracy of the measured fluid volume. During the measurement, the first reading captures the most immediate, uninterrupted effect of the vibration test on the piston position, avoiding measurement errors caused by delays. Therefore, the brake fluid flow rate detected in the first reading is used as the measured fluid volume to ensure that the difference between the measured and initial fluid volumes accurately reflects the degree of piston displacement.

[0022] In some embodiments, after detecting the change in brake fluid and the required test fluid volume in each vibration test cycle, the method further includes: comparing the difference between the required test fluid volume and the initial fluid volume with the difference between the change in brake fluid volume to a set threshold; if so, performing a step to increase the vibration energy or a step to obtain the piston stroke difference.

[0023] Verifying the consistency between the difference in required fluid volume and the initial required fluid volume and the change in brake fluid volume enables cross-validation of data, which can ensure the quality of vibration test data.

[0024] In some embodiments, until a step change in the brake fluid quantity is detected, the process is performed as follows: until a step change in the difference between the test fluid requirement and the initial fluid requirement is detected.

[0025] Since the difference between the test fluid requirement and the initial fluid requirement for each vibration test is theoretically consistent with the change in brake fluid, step changes can be monitored based on the difference between the test fluid requirement and the initial fluid requirement.

[0026] In some embodiments, until a step change in the brake fluid change is detected, the following steps are taken: plotting a relationship curve with the vibration energy as the abscissa and the difference between the brake fluid change or the test fluid requirement and the initial fluid requirement as the ordinate; and determining the inflection point where the ordinate value in the relationship curve changes from a stable state to an increasing state as the critical point where the step change occurs.

[0027] By identifying the critical point where a step change occurs through the relationship curve, and then determining the piston's anti-knockback capability value accordingly, data analysis can be simplified.

[0028] In some embodiments, the test method for brake calipers further includes the following steps: assembling the brake caliper under test into a vehicle for road condition testing, and obtaining the fluid demand difference required for the piston of the brake caliper under test to move from a rest position to a working position before and after the road condition test; obtaining the vibration energy corresponding to the fluid demand difference obtained from the vibration test, which matches the fluid demand difference obtained from the road condition test, and establishing a correlation between the road spectrum energy of the road condition test and the vibration energy of the vibration test; and establishing an evaluation data table containing the characteristic parameters of the brake caliper under test, the piston anti-knockback capability value, the road spectrum energy, and the fluid demand difference obtained from the road condition test, based on the correlation.

[0029] By utilizing the matching relationship between the fluid demand difference obtained from road condition tests and vibration tests, a correlation can be established between the road spectrum energy from road condition tests and the vibration energy from vibration tests. This establishes a connection between experimental tests and whole-vehicle road tests, and further allows for the creation of an evaluation data table that can be used to evaluate other brake calipers. This enables other brake calipers to evaluate piston anti-knockback capability based on the evaluation data table, reducing reliance on whole-vehicle road tests.

[0030] In some embodiments, obtaining the difference in fluid demand required for the piston of the tested brake caliper to move from a rest position to a working position before and after a road condition test includes: before the road condition test, detecting a first fluid demand required for the piston of the tested brake caliper to move from a rest position to a working position, wherein the first fluid demand is detected at least once and the value of the last detected value is taken; after the road condition test is completed, detecting a second fluid demand required for the piston of the tested brake caliper to move from a rest position to a working position, wherein the second fluid demand is detected at least once and the value of the first detected value is taken; calculating the difference between the second fluid demand and the first fluid demand as the difference in fluid demand required for the piston of the tested brake caliper to move from a rest position to a working position before and after the road condition test.

[0031] The detection of the first required fluid volume is conducted in the same way as the initial required fluid volume, and the detection of the second required fluid volume is conducted in the same way as the test required fluid volume. Based on the difference between the second and first required fluid volumes and the effective area of ​​the vehicle's brake master cylinder, the difference in pedal travel before and after the road condition test can also be obtained.

[0032] In some embodiments, the piston of the brake caliper engages with the piston working chamber via a sealing ring; the characteristic parameters include the piston parameters and / or sealing ring parameters and / or piston working chamber parameters of the brake caliper; wherein, the piston parameters include the piston diameter and / or the clearance between the piston and the piston working chamber and / or the surface roughness of the piston, the sealing ring parameters include the interference fit of the sealing ring and / or the coefficient of friction of the sealing ring and / or the mounting groove depth of the sealing ring, and the piston working chamber parameters include the stiffness of the piston working chamber and / or the surface roughness of the piston working chamber.

[0033] Characteristic parameters refer to parameters that affect the piston's anti-knockback capability, mainly focusing on the properties of the piston, seals, and piston working chamber.

[0034] In some embodiments, the brake caliper testing method further includes the following steps: based on the influence of the characteristic parameters on the piston anti-knock capability value, determining the relationship between the piston anti-knock capability value of the new brake caliper and the piston anti-knock capability value of existing brake calipers in the evaluation data table; wherein, the influence of the characteristic parameters on the piston anti-knock capability value is obtained based on physical principles and / or existing vibration tests and / or existing road condition tests; if the piston anti-knock capability value of the new brake caliper is greater than or equal to the piston anti-knock capability value of the qualified brake caliper in the evaluation data table, and the required road spectrum energy of the new brake caliper is less than or equal to the road spectrum energy of the qualified brake caliper, determining that the fluid demand difference value obtained from the road condition test of the new brake caliper is qualified; if the piston anti-knock capability value of the new brake caliper is less than the piston anti-knock capability value of the qualified brake caliper. If the new brake caliper's piston anti-rebound capability value is greater than the value of the unqualified brake caliper's piston anti-rebound capability in the evaluation data table, a road test is performed on the new brake caliper to obtain the fluid demand difference value. If the new brake caliper's piston anti-rebound capability value is greater than or equal to the value of the qualified brake caliper's piston anti-rebound capability, and the new brake caliper's required road spectrum energy is greater than the required road spectrum energy of the qualified brake caliper, a road test is performed on the new brake caliper to obtain the fluid demand difference value. If the new brake caliper's piston anti-rebound capability value is less than or equal to the value of the unqualified brake caliper's piston anti-rebound capability, the fluid demand difference value obtained from the road test is determined to be unqualified. Wherein, the fluid demand difference value of the qualified brake caliper is less than or equal to the set qualification standard, and the fluid demand difference value of the unqualified brake caliper is greater than the qualification standard.

[0035] By using evaluation data tables, the piston knockback capability of a new brake caliper can be inferred based on known data on the piston knockback capability of the brake caliper. This allows for efficient evaluation of the piston knockback performance of the new brake caliper in vehicle road tests, enabling pre-evaluation of the new caliper's performance based on historical data during the design phase. This reduces the need for experimental testing and vehicle road testing, and accelerates the development cycle.

[0036] In some embodiments, when it is impossible to determine the relationship between the piston knockback capability value of the new brake caliper and the piston knockback capability value of the existing brake caliper in the evaluation data table, the method further includes the following step: performing a vibration test on the new brake caliper to obtain the piston knockback capability value of the new brake caliper.

[0037] After obtaining the piston's anti-knockback capability value through vibration testing, the difference in fluid requirement obtained from road condition testing of the new brake caliper can be predicted based on the evaluation data table, reducing the need for whole vehicle road testing.

[0038] In some embodiments, when conducting road condition tests on the new brake caliper to obtain the fluid requirement difference value of the new brake caliper, the method further includes the following step: adding the characteristic parameters of the new brake caliper, the piston anti-knock capability value, the road spectrum energy, and the fluid requirement difference value obtained from the road condition test to the evaluation data table. This improves the evaluation data table, facilitating subsequent evaluation of the brake caliper's piston anti-knock capability.

[0039] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the specification, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0041] Figure 1 This illustration shows the steps of the test method for brake calipers in an embodiment of this application;

[0042] Figure 2 This illustration shows a schematic diagram of the connection between the tested brake caliper, the vibration device, and the hydraulic lines in an embodiment of this application.

[0043] Figure 3 This illustration shows a schematic diagram of an implementation process of a test method for brake calipers in an embodiment of this application;

[0044] Figure 4 The graph showing the relationship between vibration test data and vibration energy in the embodiments of this application is illustrated.

[0045] Figure 5 This paper shows a comparison chart of vibration test data of the brake caliper under test in the embodiments of this application;

[0046] Figure 6 A schematic diagram of the evaluation data table in an embodiment of this application is shown. Detailed Implementation

[0047] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to those described herein. Rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0048] The accompanying drawings are merely illustrative of this application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0049] The processes shown in the accompanying drawings are merely illustrative and do not necessarily include all steps. For example, some steps can be broken down, some steps can be combined or partially combined, and the actual execution order may change depending on the actual situation. The terms "first," "second," and similar words used in the specific description do not indicate any order, quantity, or importance, but are only used to distinguish different components. The terms "upper," "lower," "left," "right," "vertical," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. The term "multiple" means two or more, unless otherwise explicitly specified. Furthermore, in the description of this application, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a connection within two elements.

[0050] It should be noted that, unless otherwise specified, the embodiments of this application and the features in different embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0051] Figure 1 This illustrates the main steps of the brake caliper testing method. Figure 2 The diagram illustrates the connection structure between the tested brake caliper, the vibrating equipment, and the hydraulic lines. Figure 1 and Figure 2 As shown in the embodiments of this application, the test method for brake calipers includes the following steps:

[0052] S110, the brake caliper 200 under test is assembled to the vibration device 210, and the piston working chamber of the brake caliper 200 under test is connected to the hydraulic line 220;

[0053] S120, the brake caliper 200 under test is subjected to vibration test by vibration device 210, and the change in brake fluid in hydraulic line 220 is detected at the end of vibration test;

[0054] S130, increase the vibration energy of the vibration device 210 and repeat the vibration test until a step change in the amount of brake fluid is detected;

[0055] S140, based on the vibration energy corresponding to the step change, obtain the piston anti-knockback capability value of the tested brake caliper 200.

[0056] Using the vibration device 210 and hydraulic lines 220, the actual road conditions of a vehicle can be dynamically simulated, overcoming the problem of disconnect between experimental testing and actual road conditions. The piston engages with the piston working chamber through a sealing ring; due to the friction of the sealing ring on the piston, the piston has a certain ability to resist external energy impact. Vibration testing is performed by driving the brake caliper 200 under test through the vibration device 210, simulating road vibration excitation. During the vibration test, the change in brake fluid in the hydraulic lines 220 reflects the brake fluid flow caused by the piston displacement; the change in brake fluid measured at the end of each vibration test characterizes the degree of piston displacement from its initial position after this vibration test. Monitoring the change in brake fluid allows for the monitoring of the piston's dynamic behavior, enabling the capture of the transient characteristics of the knockback phenomenon. By increasing the vibration energy and repeating the vibration test, the change in brake fluid precisely monitors the critical point at which the piston experiences knockback, ensuring the sensitivity and accuracy of the test and improving test precision. When the vibration energy gradually increases and exceeds the critical point, the piston begins to move from relative rest, causing a step change in the change in brake fluid in the hydraulic lines 220. The critical point where the brake fluid volume changes abruptly can be identified by observing inflection points graphically. The vibration energy corresponding to this abrupt change, i.e., the critical vibration energy at which the piston knocks back, can be defined as the piston knockback resistance value of the tested brake caliper 200, or the piston knockback resistance point. The piston knockback resistance value can also be used to compare the piston knockback resistance of different brake calipers, providing data support for design optimization.

[0057] The testing method described in this application can accurately and efficiently evaluate the piston's anti-knockback capability, reduce reliance on full-vehicle road testing, and lower development costs and risks.

[0058] In some embodiments, the test method for brake calipers further includes the following steps: before the first vibration test, the hydraulic line is activated to detect the brake fluid flow rate required to push the piston of the brake caliper under test from the initial position to the working position, and this flow rate is recorded as the initial fluid requirement; after each vibration test, the hydraulic line is activated to detect the brake fluid flow rate required to push the piston of the brake caliper under test from the current position to the working position, and this flow rate is recorded as the test fluid requirement; when a step change in the amount of brake fluid is detected, the piston stroke difference of the brake caliper under test is obtained based on the difference between the test fluid requirement corresponding to the step change and the initial fluid requirement.

[0059] The initial position of the piston refers to the position where the piston remains stationary under the frictional force of the sealing ring when no external vibration excitation is applied. The working position can be configured as the critical position where the piston begins to contact the brake disc, or it can be defined as a specific position as needed. The piston displacement can be quantified by measuring the required fluid volume, so as to correlate it with the degree of piston knockback. The initial required fluid volume reflects the reference position of the piston in a static, unforced state, providing a basis for comparison of subsequent changes. The test required fluid volume measured after the vibration test reflects the piston position change caused by the vibration test, quantifying the phenomenon of changes in the gap between the piston and the brake disc caused by the piston displacement. When the brake fluid volume changes abruptly, it indicates that the piston has knocked back under the vibration test. Based on the difference between the test required fluid volume corresponding to the step change and the initial required fluid volume, and the effective area of ​​the brake master cylinder in the hydraulic line, the piston stroke difference can be obtained, characterizing the displacement of the piston of the tested brake caliper caused by the vibration test corresponding to the step change, i.e., the degree of piston knockback. The formula for calculating the piston stroke difference can be: Piston stroke difference = Difference between the test fluid requirement and the initial fluid requirement corresponding to the step change ÷ Actual area of ​​the brake master cylinder of the hydraulic line.

[0060] The hydraulic master cylinder is configured to supply brake fluid to the piston's working chamber to move the piston. The master cylinder can be connected to a brake fluid reservoir and driven by an electric motor.

[0061] In some embodiments, the vibration device can vibrate along the X-axis and / or Y-axis and / or Z-axis; when performing vibration testing on the brake caliper under test, the vibration device is controlled to vibrate along one or more coordinate axes to detect the piston knockback resistance value of the brake caliper under test along one or more coordinate axes.

[0062] Vibration equipment can be used to simulate multi-directional vibrations of a vehicle during road testing, comprehensively assess the anti-knockback capability of the piston of the brake caliper under test in different directions, and improve the accuracy of the test.

[0063] In some embodiments, when performing a vibration test on the brake caliper under test, the vibration device is controlled to perform sinusoidal vibration according to set vibration parameters, including vibration frequency, acceleration, and vibration time; increasing the vibration energy of the vibration device includes increasing the acceleration of the sinusoidal vibration according to a set step size; obtaining the piston anti-backlash capability value of the brake caliper under test includes using the acceleration value of the sinusoidal vibration as the piston anti-backlash capability value of the brake caliper under test.

[0064] By utilizing sinusoidal vibration and vibration parameter control, vibration testing becomes standardized and repeatable, avoiding the uncertainties caused by random vibration. By increasing the acceleration of the sinusoidal vibration in predetermined steps, the vibration energy can be gradually increased to approach the critical point of piston knockback. This allows for accurate detection of step changes, ensuring the precision of the vibration test.

[0065] In other embodiments, the vibration device can also be controlled to vibrate according to other suitable vibration excitation waveforms, as long as it is easy to find the critical point that causes a step change in the amount of brake fluid.

[0066] In some embodiments, refer to Figure 2 As shown, a bidirectional flow meter 221 is installed in the hydraulic pipeline. The bidirectional flow meter 221 is configured to detect the flow rate of brake fluid flowing into and out of the piston working chamber. The brake fluid change is the cumulative net flow rate value measured by the bidirectional flow meter 221 during the vibration test. The brake fluid flow rate is the cumulative positive flow rate value measured by the bidirectional flow meter 221 during the operation of the hydraulic pipeline. Before each increase in the vibration energy of the vibration equipment, the bidirectional flow meter 221 is reset to zero.

[0067] During vibration testing, the brake fluid flow rate changes are relatively small due to the instantaneous back-and-forth movement of the piston. Conventional flow meters lack sufficient inherent mechanical resolution, requiring software enhancement to improve this resolution. Furthermore, conventional flow meters are typically unidirectional; for monitoring the minute flow rate caused by the piston's transient directional changes during vibration testing, the flow meter signal needs to be re-encoded for accurate measurement. This application utilizes a bidirectional flow meter 221, which can accurately measure minute, transiently directional brake fluid flow rates, enabling accurate monitoring of piston knockback and overcoming the insufficient resolution of conventional flow meters. Additionally, a zeroing operation ensures the independence of each vibration test, avoiding cumulative errors.

[0068] The cumulative net flow rate value represents the brake fluid flow rate corresponding to the net displacement of the piston relative to its initial position after the vibration test. A positive cumulative net flow rate value indicates that brake fluid flowed net into the piston working chamber during the vibration test, pushing the piston towards the brake disc. A negative cumulative net flow rate value indicates that brake fluid flowed net out of the piston working chamber during the vibration test, causing the piston to bounce back and be pushed away from the brake disc. A zero or near-zero cumulative net flow rate value indicates that the piston did not move during the vibration test or, although it moved back and forth, eventually returned to near its initial position. The cumulative positive flow rate value refers to the total amount of brake fluid flowing unidirectionally into the piston working chamber, measured by the bidirectional flowmeter 221, during the test process of activating the hydraulic line to push the piston to the working position. The cumulative positive flow rate value represents the brake fluid flow rate required to push the piston from its initial position to the working position, i.e., the required fluid volume. The initial required fluid volume is the cumulative positive flow rate value when the piston is not subjected to vibration and is in its natural initial position; the test required fluid volume is the cumulative positive flow rate value when the piston, after undergoing the vibration test, may have shifted and is in a new position. The difference between the required liquid volume and the initial required liquid volume can directly reflect the piston displacement caused by vibration.

[0069] In some embodiments, the working position is configured as the critical position where the piston of the brake caliper under test begins to contact the brake disc. See also... Figure 2 As shown, a pressure sensor 222 is installed in the hydraulic pipeline. During the start-up of the hydraulic pipeline, the starting point of the linear increase in pressure value detected by the pressure sensor 222 is determined as the piston of the brake caliper under test reaching the working position.

[0070] Using pressure sensor 222, it is possible to accurately determine whether the piston has reached the working position. Combined with... Figure 2 As shown, a precision servo motor 224 can slowly and constantly push the brake master cylinder 223 to push the piston of the brake caliper under test, while a pressure sensor 222 monitors the pressure value in the hydraulic line. When the pressure value begins to rise linearly, it indicates that the piston has contacted the brake disc, that is, the piston has reached the working position. The stroke pushed by the servo motor from the start of movement to the moment when the pressure value begins to rise linearly corresponds to the test fluid requirement of the current test.

[0071] In some embodiments, activating the hydraulic line and detecting the brake fluid flow rate required to push the piston of the brake caliper under test from the initial position to the working position, and recording it as the initial required flow rate, includes: repeatedly activating the hydraulic line and detecting the brake fluid flow rate required to push the piston of the brake caliper under test from the initial position to the working position; if the fluctuation range of the brake fluid flow rate detected multiple times is less than a first threshold, the last detected brake fluid flow rate is recorded as the initial required flow rate.

[0072] Multiple measurements can reduce the impact of random fluctuations, ensure the accuracy of the initial fluid requirement, and confirm that the system has stabilized before vibration, thus guaranteeing accurate subsequent testing. The fluctuation range of the brake fluid flow rate detected multiple times can be the standard deviation of the detected flow rates or other parameters used to measure the fluctuation range. The first threshold can be set as needed, for example, 5%, but is not limited to this. During the initial fluid requirement testing process, the last measurement is closest to the vibration test, representing the precise initial state of the system just before the vibration test; therefore, the last detected brake fluid flow rate is used as the initial fluid requirement.

[0073] In some embodiments, after the vibration test, the hydraulic line is activated, and the brake fluid flow rate required to push the piston of the brake caliper under test from its current position to its working position is detected and recorded as the test fluid requirement. This includes: after the vibration test ends and a certain period of time is waited, the steps of activating the hydraulic line and detecting the brake fluid flow rate required to push the piston of the brake caliper under test from its current position to its working position are repeated multiple times; if the fluctuation amplitude of the brake fluid flow rate detected multiple times is less than a second threshold, the brake fluid flow rate detected for the first time is recorded as the test fluid requirement.

[0074] After the vibration test, a waiting period is allowed for residual vibration to cease before the required brake fluid volume is measured. Multiple measurements reduce the impact of random fluctuations and ensure the accuracy of the measured fluid volume. The fluctuation range of the brake fluid flow rate detected multiple times can be the standard deviation of the detected flow rates or other parameters used to measure this fluctuation. The second threshold can be set as needed and may or may not be equal to the first threshold. During the measurement of the required fluid volume, the first measurement captures the most immediate, uninterrupted impact of the vibration test on the piston position, avoiding measurement errors caused by delays. Therefore, the brake fluid flow rate detected in the first measurement is used as the measured fluid volume to ensure that the difference between the measured and initial fluid volumes accurately reflects the degree of piston displacement.

[0075] In some embodiments, after detecting the change in brake fluid and the test fluid requirement in each vibration test cycle, the method further includes: comparing the difference between the test fluid requirement and the initial fluid requirement with the difference between the brake fluid change and a set threshold; if so, performing a step to increase vibration energy or a step to obtain piston stroke difference.

[0076] Verifying the consistency between the required brake fluid volume in the test and the initial required volume (i.e., the difference in required volume obtained from the vibration test) and the change in brake fluid volume ensures the quality of the vibration test data through cross-validation. The difference in required volume obtained from the vibration test represents the additional brake fluid flow required to compensate for piston displacement due to vibration. If the piston does not move, the difference is approximately zero; if the piston moves, the difference is usually greater than zero. Theoretically, the difference in required volume obtained from each vibration test should be approximately equal to the change in brake fluid volume. If the two values ​​are close, it indicates that the vibration test data is accurate and the test results are reliable. A threshold can be set as needed, for example, 5% of the brake fluid change, but it is not a limitation. If the two values ​​differ significantly, the vibration test can be repeated after ruling out hardware malfunctions.

[0077] In some embodiments, until a step change in brake fluid volume is detected, the action is performed as follows: until a step change in the difference between the test required fluid volume and the initial required fluid volume is detected.

[0078] Since the difference between the test fluid requirement and the initial fluid requirement for each vibration test is theoretically consistent with the change in brake fluid, step changes can be monitored based on the difference between the test fluid requirement and the initial fluid requirement.

[0079] In some embodiments, until a step change in the brake fluid quantity is detected, the following steps are taken: plotting a relationship curve with vibration energy as the abscissa and the difference between the brake fluid quantity change or the test fluid quantity and the initial fluid quantity as the ordinate; and determining the inflection point where the ordinate value in the relationship curve changes from a stable state to an increasing state as the critical point where a step change occurs.

[0080] Identifying the critical point of a step change using the relationship curve, and thus determining the piston's anti-knockback capability value, simplifies data analysis. The inflection point where the vertical axis value in the relationship curve changes from a stable state to an increasing state can be observed, identified using a curve fitting algorithm, or determined by identifying the point where the first derivative value in the relationship curve first reaches a local maximum.

[0081] Figure 3 This diagram illustrates a specific implementation process for testing brake calipers, combined with... Figure 2 and Figure 3The process includes the following steps: S310, connect the brake caliper 200 under test to the hydraulic line 220 and perform filling and venting. The hydraulic line 220 is equipped with a bidirectional flow meter 221 for measuring instantaneous micro-flow changes in brake fluid, a pressure sensor 222 for monitoring hydraulic pressure changes, a master cylinder 223 for providing brake fluid, and a servo motor 224 for controlling the movement of the master cylinder 223. S320, adjust the vibration direction of the vibration device 210 to the Z-axis direction. The X-axis corresponds to the vehicle's forward and reverse direction, the Y-axis is the left-right direction (aligned with the piston axis of the brake caliper 200 under test), and the Z-axis is the vertical direction. The brake caliper 200 under test can be mounted on the vibration device 210 using a fixture 211. S330, measure the initial required fluid volume three times, with an interval of t seconds between each measurement. The test results are recorded as pre-FVD1, pre-FVD2, and pre-FVD3. S340, Start the vibration device 210 to perform sinusoidal vibration at a frequency of aHz, an acceleration of 1g, and a vibration time of 2 minutes. Take the value of the bidirectional flow meter 221 at the end of the vibration test and record it as FR. S350, After t seconds of vibration test completion, measure the required liquid volume three times, with an interval of t seconds between each measurement. Record the test results as post-FVD1, post-FVD2, and post-FVD3. S360, Calculate the difference between post-FVD1 and post-FVD3 and record it as ΔFVD. ΔFVD can be compared with FR for cross-validation. S370, Repeat S340, S350, and S360, maintaining sinusoidal vibration at a frequency of aHz and a vibration time of 2 minutes. Acceleration is accumulated in steps of 1g until the FR / ΔFVD value with a step change is found. Record the corresponding acceleration value as the piston anti-backlash capability point in the Z-axis direction of the tested brake caliper 200. S380, adjust the vibration direction of the vibration device 210 to the Y-axis direction, and repeat S330, S340, S350, S360, and S370 to test the piston anti-knockback capability of the brake caliper 200 under test in the Y-axis direction.

[0082] Figure 4 The relationship curve between vibration test data and vibration energy is shown in the diagram, with reference to... Figure 4 As shown, the horizontal axis represents vibration energy (acceleration of sinusoidal vibration), and the vertical axis represents FR or ΔFVD during the vibration test. Using the inflection point of the relationship curve, the piston's anti-backlash capability point 400 can be found, representing the minimum vibration energy at which the piston resists backlash. The higher the piston's anti-backlash capability value, the stronger its anti-backlash capability.

[0083] Figure 5The vibration test data of the brake caliper under test is shown. Specifically, the vibration test is conducted in the Y-axis direction. The values ​​of three FR (FR1, FR2, FR3) and three ΔFVD (ΔFVD1, ΔFVD2, ΔFVD3) are measured as the acceleration gradually increases from 1g to 4g. Figure 5 In the graph, the horizontal axis represents acceleration in g (gravitational acceleration), and the vertical axis represents flow rate in cc (cubic centimeters). Figure 5 It is evident that the piston's anti-knock capability is between 2g and 3g at the acceleration range. During multiple measurements, the piston's anti-knock capability may decrease due to lubrication generated by the relative movement between the piston and the seal ring, but it remains concentrated between 2g and 3g. Furthermore, the measured ΔFVD value is essentially equivalent to the FR value.

[0084] The testing method described in this application requires no full-vehicle road testing from setup to data analysis, consumes very little time, greatly saves resources and time, and can be tested based on brake caliper samples in the early stages of design.

[0085] In some embodiments, the test method for brake calipers further includes the following steps: assembling the brake caliper under test into a vehicle for road condition testing, and obtaining the fluid demand difference required for the piston of the brake caliper under test to move from a rest position to a working position before and after the road condition test; obtaining the vibration energy corresponding to the fluid demand difference obtained from the vibration test, which matches the fluid demand difference obtained from the road condition test, and establishing a correlation between the road spectrum energy of the road condition test and the vibration energy of the vibration test; and establishing an evaluation data table containing the characteristic parameters of the brake caliper under test, the piston anti-knockback capability value, the road spectrum energy, and the fluid demand difference obtained from the road condition test, based on the correlation.

[0086] The fluid demand difference obtained from vibration testing, which is matched with the fluid demand difference obtained from road condition testing, can be either equal to or less than a threshold value. By utilizing the matching relationship between the fluid demand difference obtained from road condition testing and the fluid demand difference obtained from vibration testing, a correlation can be established between the road spectrum energy from road condition testing and the vibration energy from vibration testing. This establishes a link between experimental testing and vehicle road testing, and further allows for the creation of an evaluation data table that can be used to assess the piston anti-knockback capability of other brake calipers, reducing reliance on vehicle road testing.

[0087] In some embodiments, obtaining the difference in fluid demand required for the piston of the tested brake caliper to move from a rest position to a working position before and after a road condition test includes: before the road condition test, detecting a first fluid demand required for the piston of the tested brake caliper to move from a rest position to a working position, wherein the first fluid demand is detected at least once and the value of the last detected value is taken; after the road condition test is completed, detecting a second fluid demand required for the piston of the tested brake caliper to move from a rest position to a working position, wherein the second fluid demand is detected at least once and the value of the first detected value is taken; and calculating the difference between the second fluid demand and the first fluid demand as the difference in fluid demand required for the piston of the tested brake caliper to move from a rest position to a working position before and after the road condition test.

[0088] The detection of the first fluid requirement is conducted in the same manner as the initial fluid requirement, and the detection of the second fluid requirement is conducted in the same manner as the test fluid requirement. Based on the difference between the second and first fluid requirements and the effective area of ​​the vehicle's brake master cylinder, the difference in pedal travel before and after the road condition test can also be obtained (e.g., pedal travel difference = difference between the second and first fluid requirements ÷ effective area of ​​the vehicle's brake master cylinder). Alternatively, in some embodiments, the difference in pedal travel before and after the road condition test can also be obtained and converted into the difference in fluid requirement obtained from the road condition test.

[0089] In some embodiments, in addition to testing and calibration to establish the correlation between road spectrum energy and vibration energy, the conversion between road spectrum energy and vibration energy can also be achieved based on theoretical calculations using the principle of energy equivalence.

[0090] In some embodiments, the piston of the brake caliper engages with the piston working chamber via a sealing ring; the characteristic parameters include the piston parameters and / or sealing ring parameters and / or piston working chamber parameters of the brake caliper; wherein, the piston parameters include the piston diameter and / or the clearance between the piston and the piston working chamber and / or the surface roughness of the piston, the sealing ring parameters include the interference fit of the sealing ring and / or the coefficient of friction of the sealing ring and / or the depth of the mounting groove of the sealing ring, and the piston working chamber parameters include the stiffness of the piston working chamber and / or the surface roughness of the piston working chamber.

[0091] Characteristic parameters refer to parameters that affect the piston's anti-knockback capability, mainly focusing on the properties of the piston, seals, and piston working chamber.

[0092] Figure 6 The evaluation data table is shown for reference. Figure 6As shown, the evaluation data table can include Section A (characteristic parameters of brake calipers), Section B (piston anti-knock capability value), Section C (road spectrum energy), and Section D (difference in fluid requirement obtained from road condition tests). Section A records the product design characteristics of brake calipers, where the rows are product sequences (product 1, product 2, product 3...) and the columns are characteristic parameters (characteristic parameter 1, characteristic parameter 2, characteristic parameter 3...). Section B records the vibration test results, i.e., the piston anti-knock capability value of each tested brake caliper. Section B shares the product sequence with Section A, and the columns in Section B are piston anti-knock capability values ​​(1g, 2g, 3g...), representing vibration energy, or vibration energy level. Section C records the comparison between the road spectrum energy (specifically, the equivalent energy spectral density of the road spectrum energy) from the road condition test and the vibration energy from the vibration test. Section D records the road condition test results, with the vertical axis representing the road spectrum energy from the road condition test and the horizontal axis representing the difference in fluid requirement obtained from the road condition test. The difference in required fluid volume is evaluated using the pass / fail standard. If the difference in required fluid volume obtained from the road condition test is less than the pass / fail standard (see the green pass / fail baseline, a reference line formed by connecting the data from areas A, B, C, and D of a pass / fail brake caliper), the corresponding brake caliper is considered pass / fail. If the difference in required fluid volume obtained from the road condition test is greater than the pass / fail standard (see the red fail / fail baseline, a reference line formed by connecting the data from areas A, B, C, and D of a fail / fail brake caliper), the corresponding brake caliper is considered fail / fail. The pass / fail standard can be determined based on specific vehicle model requirements and operating conditions. Furthermore, if more test data for mass-produced brake calipers is available, it can be added to the evaluation data table for subsequent evaluation. Mass-produced brake calipers are generally considered pass / fail.

[0093] Continue to refer to Figure 6 The process of setting a qualified baseline includes, for example, selecting qualified samples, such as one or more mass-produced brake calipers that perform well in terms of fluid requirement difference during road condition testing; collecting data from four zones, where zone A records the characteristic parameters of the brake caliper (e.g., 0.6mm interference fit of the seal, 48mm piston diameter, etc.), zone B records the piston anti-knockback capability value obtained from the vibration test of the brake caliper (e.g., 16g), zone C records the road spectrum energy corresponding to the brake caliper during road condition testing (e.g., equivalent to 16g in the vibration test), and zone D records the road condition test result of the brake caliper (fluid requirement difference less than the qualified standard); then, connecting the data points of the brake caliper in zones A, B, C, and D with a broken line forms the qualified baseline. The process of setting an unqualified baseline is similar.

[0094] In some embodiments, the brake caliper testing method further includes the following steps: based on the influence of characteristic parameters on the piston knockback resistance value, determining the relationship between the piston knockback resistance value of the new brake caliper and the piston knockback resistance value of existing brake calipers in the evaluation data table, according to the characteristic parameters of the new brake caliper; wherein, the influence of characteristic parameters on the piston knockback resistance value is obtained based on physical principles and / or existing vibration tests and / or existing road condition tests. For example, if the interference fit of the seal ring is larger in the new brake caliper compared to the existing brake caliper, then according to physical principles, it can be determined that the piston of the new brake caliper is more resistant to knockback than the piston of the existing brake caliper, that is, the piston knockback resistance value of the new brake caliper is greater than that of the existing brake caliper. As another example, if the mounting groove depth of the seal ring is smaller in the new brake caliper compared to the existing brake caliper, according to existing vibration tests and / or existing road condition tests, when the mounting groove depth of the seal ring is reduced, the piston knockback resistance of the brake caliper decreases, then it can be determined that the piston knockback resistance value of the new brake caliper is less than that of the existing brake caliper. If there is enough data from existing vibration tests and road condition tests, the relationship between the piston knockback capability of the new brake caliper and that of the existing brake caliper can be determined based on a combination of multiple characteristic parameters.

[0095] If the piston knockback resistance value of the new brake caliper is greater than or equal to the piston knockback resistance value of the qualified brake caliper in the evaluation data table, and the required road spectrum energy of the new brake caliper is less than or equal to the road spectrum energy of the qualified brake caliper, then the required fluid volume difference value obtained from the road condition test of the new brake caliper is deemed qualified. The required road spectrum energy of the new brake caliper corresponds to the road vibration conditions of the target operating environment of the new brake caliper.

[0096] If the piston knockback resistance value of the new brake caliper is less than that of the qualified brake caliper but greater than that of the unqualified brake caliper in the evaluation data sheet, it is impossible to estimate the difference in fluid requirement of the new brake caliper under actual vehicle conditions. Therefore, road condition testing is conducted on the new brake caliper to obtain the difference in fluid requirement of the new brake caliper.

[0097] Even if the piston anti-knock capability of the new brake caliper is greater than or equal to that of the qualified brake caliper, and the required road spectrum energy of the new brake caliper is greater than that of the qualified brake caliper, it is still impossible to estimate the difference in fluid demand of the new brake caliper under actual vehicle conditions. Therefore, road condition tests are conducted on the new brake caliper to obtain the difference in fluid demand of the new brake caliper.

[0098] If the piston knockback resistance value of the new brake caliper is less than or equal to that of the substandard brake caliper, the fluid requirement difference obtained from the road test of the new brake caliper is deemed unacceptable. In this case, the new brake caliper can be optimized based on the evaluation data table without waiting for full vehicle road testing. For example, statistical tools (such as correlation analysis and principal component analysis) can be used to analyze the evaluation data table, quantifying the influence of each characteristic parameter on the piston knockback resistance value, so that one or more characteristic parameters of the brake caliper can be reasonably optimized based on the analysis results.

[0099] Among them, the fluid requirement difference of qualified brake calipers is less than or equal to the set qualified standard, while the fluid requirement difference of unqualified brake calipers is greater than the qualified standard.

[0100] By using evaluation data tables, the piston knockback capability of a new brake caliper can be inferred based on known data on the piston knockback capability of the brake caliper. This allows for efficient evaluation of the piston knockback performance of the new brake caliper in vehicle road tests, enabling pre-evaluation of the new caliper's performance based on historical data during the design phase. This reduces the need for experimental testing and vehicle road testing, and accelerates the development cycle.

[0101] In some embodiments, when it is impossible to determine the relationship between the piston knockback capability value of the new brake caliper and the piston knockback capability value of the existing brake caliper in the evaluation data table, such as when the characteristic parameters are subject to multiple variables or exceed the range of the evaluation data table, the following step is also included: performing a vibration test on the new brake caliper to obtain the piston knockback capability value of the new brake caliper.

[0102] After obtaining the piston's anti-knockback capability value through vibration testing, the difference in fluid requirement obtained from road condition testing of the new brake caliper can be predicted based on the evaluation data table, reducing the need for whole vehicle road testing.

[0103] In some embodiments, when conducting road tests on a new brake caliper to obtain the fluid requirement difference for the new brake caliper, the method further includes the following step: adding the characteristic parameters of the new brake caliper, the piston anti-knock capability value, the road spectrum energy, and the fluid requirement difference obtained from the road test to an evaluation data table. This refines the evaluation data table, facilitating subsequent evaluation of the brake caliper's piston anti-knock capability and improving accuracy and adaptability. Utilizing the continuously improving evaluation data table, the design parameters of the brake caliper can be effectively correlated with the vehicle's road conditions, reducing reliance on vehicle road testing and enabling accurate prediction of piston anti-knock capability during the design phase. This allows for optimization of the brake caliper design, reducing development costs and risks.

[0104] In some embodiments, based on the evaluation data table, machine learning algorithms (such as multiple linear regression, decision trees, etc.) can be used to build a predictive model. For example, the model can be trained using the feature parameters of area A as input and the piston anti-knock capability value of area B and the difference in fluid requirement obtained from road condition testing in area D as output. When a new brake caliper is available, its feature parameters can be input into the predictive model to predict the piston anti-knock capability value and the difference in fluid requirement obtained from road condition testing for the new brake caliper.

[0105] Finally, it should be noted that the above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this application, and all such modifications or substitutions should be considered within the scope of protection of this application.

Claims

1. A test method for brake calipers, characterized in that, Includes the following steps: The brake caliper under test is assembled onto the vibration equipment, and the piston working chamber of the brake caliper under test is connected to the hydraulic line; The vibration test is performed on the brake caliper under test using the vibration equipment, and the change in brake fluid in the hydraulic line is detected at the end of the vibration test. Increase the vibration energy of the vibration device and repeat the vibration test until a step change in the amount of brake fluid is detected; Before the first vibration test, the hydraulic line is activated to detect the brake fluid flow rate required to push the piston of the brake caliper under test from the initial position to the working position, and this flow rate is recorded as the initial fluid requirement. After each vibration test, the hydraulic line is activated to detect the brake fluid flow rate required to push the piston of the brake caliper under test from the current position to the working position, and this flow rate is recorded as the test fluid requirement. When a step change in the brake fluid flow rate is detected, the piston stroke difference of the brake caliper under test is obtained based on the difference between the test fluid requirement corresponding to the step change and the initial fluid requirement. After detecting the brake fluid change and the test fluid requirement within each vibration test cycle, the method further includes: comparing whether the difference between the test fluid requirement and the initial fluid requirement and the difference between the brake fluid change is less than a set threshold; if so, either the step of increasing the vibration energy or the step of obtaining the piston stroke difference is executed. The hydraulic pipeline is equipped with a bidirectional flow meter. The change in brake fluid is the cumulative net flow rate measured by the bidirectional flow meter during the vibration test. The brake fluid flow rate is the cumulative positive flow rate measured by the bidirectional flow meter during the operation of the hydraulic pipeline. Before each increase in the vibration energy of the vibration equipment, the bidirectional flow meter is reset to zero. Specifically, until a step change in the brake fluid quantity is detected, the process includes: plotting a relationship curve with the vibration energy as the abscissa and the difference between the brake fluid quantity change or the test fluid requirement and the initial fluid requirement as the ordinate; and determining the inflection point where the ordinate value in the relationship curve changes from a stable state to an increasing state as the critical point where the step change occurs. Based on the vibration energy corresponding to the step change, the piston knockback capability value of the tested brake caliper is obtained; and The brake caliper under test is assembled into the vehicle for road condition testing, and the difference in fluid demand required for the piston of the brake caliper to move from the rest position to the working position before and after the road condition test is obtained. The vibration energy corresponding to the difference in fluid demand obtained from the vibration test is obtained and matched with the difference in fluid demand obtained from the road condition test. The correlation between the road spectrum energy of the road condition test and the vibration energy of the vibration test is established. Based on the correlation, an evaluation data table is established, which includes the characteristic parameters of the brake caliper under test, the piston anti-knockback capability value, the road spectrum energy, and the difference in fluid demand obtained from the road condition test.

2. The test method as described in claim 1, characterized in that, It also includes the following steps: Based on the influence of the characteristic parameters on the piston anti-knock capability value, the relationship between the piston anti-knock capability value of the new brake caliper and the piston anti-knock capability value of the existing brake calipers in the evaluation data table is determined according to the characteristic parameters of the new brake caliper. The influence of the characteristic parameters on the piston's anti-knockback capability value is obtained based on physical principles and / or existing vibration tests and / or existing road condition tests. If the piston anti-knock capability value of the new brake caliper is greater than or equal to the piston anti-knock capability value of the qualified brake caliper in the evaluation data table, and the required road spectrum energy of the new brake caliper is less than or equal to the road spectrum energy of the qualified brake caliper, then the required fluid volume difference value obtained from the road condition test of the new brake caliper is determined to be qualified. If the piston knockback resistance value of the new brake caliper is less than that of the qualified brake caliper but greater than that of the unqualified brake caliper in the evaluation data table, a road condition test is performed on the new brake caliper to obtain the fluid requirement difference of the new brake caliper. If the piston anti-knock capability value of the new brake caliper is greater than or equal to the piston anti-knock capability value of the qualified brake caliper, and the required road spectrum energy of the new brake caliper is greater than the road spectrum energy of the qualified brake caliper, a road condition test is performed on the new brake caliper to obtain the fluid demand difference of the new brake caliper. If the piston knockback resistance value of the new brake caliper is less than or equal to the piston knockback resistance value of the unqualified brake caliper, the difference in fluid requirement obtained from the road condition test of the new brake caliper is determined to be unqualified. Wherein, the fluid requirement difference of the qualified brake caliper is less than or equal to the set qualified standard, and the fluid requirement difference of the unqualified brake caliper is greater than the qualified standard.

3. The test method as described in claim 2, characterized in that, In cases where the relationship between the piston knockback capability value of the new brake caliper and the piston knockback capability value of the existing brake calipers in the evaluation data table cannot be determined, the following steps are also included: Vibration tests were performed on the new brake caliper to obtain the piston knockback resistance value of the new brake caliper.

4. The test method as described in claim 1, characterized in that, The vibration device can vibrate along the X-axis and / or Y-axis and / or Z-axis; When performing a vibration test on the brake caliper under test, the vibration device is controlled to vibrate along one or more coordinate axes to detect the piston knockback resistance value of the brake caliper under test along the one or more coordinate axes.

5. The test method as described in claim 1, characterized in that, When performing a vibration test on the brake caliper under test, the vibration device is controlled to perform sinusoidal vibration according to the set vibration parameters, including vibration frequency, acceleration and vibration time. Increasing the vibration energy of the vibrating device includes: increasing the acceleration of the sinusoidal vibration by a set step size; Obtaining the piston knockback resistance value of the brake caliper under test includes: using the acceleration value of the sinusoidal vibration as the piston knockback resistance value of the brake caliper under test.

6. The test method as described in claim 1, characterized in that, The working position is configured as the critical position at which the piston of the brake caliper under test begins to contact the brake disc; The hydraulic line is equipped with a pressure sensor. During the operation of the hydraulic line, the starting point at which the pressure value detected by the pressure sensor rises linearly is determined as the point at which the piston of the brake caliper under test reaches the working position.

7. The test method as described in claim 1, characterized in that, The hydraulic line is activated, and the brake fluid flow rate required to push the piston of the tested brake caliper from its initial position to its working position is measured and recorded as the initial fluid requirement, including: Repeat the steps of starting the hydraulic line multiple times and measuring the brake fluid flow rate required to push the piston of the brake caliper under test from the initial position to the working position; If the fluctuation range of the brake fluid flow rate detected multiple times is less than the first threshold, the last detected brake fluid flow rate is recorded as the initial required fluid volume.

8. The test method as described in claim 1, characterized in that, After the vibration test, the hydraulic line is activated, and the brake fluid flow rate required to push the piston of the brake caliper under test from its current position to the working position is measured and recorded as the test fluid requirement, including: After the vibration test is completed and a certain amount of time is waited, the steps of starting the hydraulic line and detecting the brake fluid flow rate required to push the piston of the brake caliper under test from the current position to the working position are repeated multiple times. If the fluctuation range of brake fluid flow detected multiple times is less than the second threshold, the brake fluid flow detected for the first time shall be recorded as the test fluid requirement.

9. The test method as described in claim 1, characterized in that, Until a step change in the brake fluid quantity is detected, the process continues as follows: until a step change in the difference between the test required fluid quantity and the initial required fluid quantity is detected.

10. The test method as described in claim 1, characterized in that, Based on the difference in required fluid volume between the test fluid volume corresponding to the step change and the initial fluid volume, the piston stroke difference of the brake caliper under test is obtained, including: The piston stroke difference of the brake caliper under test is obtained based on the difference between the test fluid demand corresponding to the step change and the initial fluid demand, as well as the working area of ​​the brake master cylinder of the hydraulic line. The brake master cylinder of the hydraulic line is configured to supply brake fluid to the piston working chamber.

11. The test method as described in claim 1, characterized in that, Obtain the difference in fluid requirement required for the piston of the tested brake caliper to move from its rest position to its working position before and after the road condition test, including: Before the road condition test, the first fluid requirement required for the piston of the brake caliper under test to move from the rest position to the working position is detected, wherein the first fluid requirement is detected at least once and the value of the last detected value is taken. After the road condition test is completed, the second fluid requirement required for the piston of the brake caliper under test to move from the rest position to the working position is detected, wherein the second fluid requirement is detected at least once and the value of the first detection is taken. The difference between the second required fluid volume and the first required fluid volume is calculated as the difference in fluid volume required for the piston of the tested brake caliper to move from the rest position to the working position before and after the road condition test.

12. The test method as described in claim 1, characterized in that, The piston of the brake caliper engages with the piston working chamber via a sealing ring; The characteristic parameters include the piston parameters and / or sealing ring parameters and / or piston working chamber parameters of the brake caliper; Wherein, the piston parameters include the piston diameter and / or the clearance between the piston and the piston working chamber and / or the piston surface roughness; the sealing ring parameters include the sealing ring interference and / or the sealing ring friction coefficient and / or the sealing ring mounting groove depth; and the piston working chamber parameters include the piston working chamber stiffness and / or the piston working chamber surface roughness.

13. The test method as described in claim 2, characterized in that, In obtaining the fluid requirement difference of the new brake caliper by conducting road condition tests, the method further includes the following steps: The characteristic parameters of the new brake caliper, the piston anti-knock value, the road spectrum energy, and the fluid requirement difference obtained from road condition tests are added to the evaluation data table.

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