Method and device for testing'return stroke and clearance 'performance of opposed piston brake caliper assembly

Abstract

The invention belongs to the field of automobile brake testing, and relates to an opposed piston brake caliper assembly'return stroke and clearance 'performance testing method and device, and the method comprises the steps: S1, full-stroke lubrication: carrying out the pressurization under the condition of no brake block, and carrying out the pressure reduction so as to completely push a piston back to the bottom of a cylinder hole; s2, simulating the position of the piston in a new product gap; s3, zero setting of the displacement sensor: determining the initial hydraulic pressure and performing zero setting according to the initial hydraulic pressure; s4, testing the return stroke and the clearance: applying 1 MPa of gradually rising pressure to the brake caliper, releasing the pressure, keeping the pressure for 120 seconds, sequentially testing the pressure of 3 MPa, 5 MPa, 7 MPa, 9 MPa and 11 MPa until 15 MPa, and testing each pressure twice; s5, measuring and recording relative displacement between the piston and the shell under each pressure; and S6, analyzing the output data, and performing data processing. A test object of the method comprises a friction block mode and a steel block mode. The device is composed of a pressurization adjusting system, a clamping alignment unit and a test data analysis system. The testing of the return stroke and the gap of the fixed card has great significance in analyzing and reducing dragging, matching liquid demand and other key performances.

Description

Technical Field

[0001] The present invention belongs to the field of automotive braking tests, and relates to a method and device for testing the "return stroke and clearance" performance of an opposed piston brake caliper assembly. Background Art

[0002] The opposed piston brake caliper assembly (also known as a fixed brake caliper) is one of the core components of an automotive disc brake system. Its structural feature is that the brake caliper body is rigidly fixed to the vehicle steering knuckle or axle bracket, and the brake pads are synchronously driven by pistons symmetrically arranged on both sides to clamp the brake disc, thereby achieving the braking effect. Compared with a floating brake caliper, its opposed piston design can effectively avoid the deflection deformation of the caliper body caused by uneven force, significantly improve the braking rigidity and stability, and at the same time extend the service life due to the uniform wear of the friction pads. Such brake calipers are particularly suitable for scenarios with strict requirements for braking response speed and durability, such as high-performance passenger cars, heavy-duty commercial vehicles, and the front wheels of motorcycles. However, the quality of its braking performance highly depends on the precise control of the piston return stroke and the disc-pad clearance - the return stroke determines the displacement of the piston retracting into the cylinder bore after braking is released, directly affecting the magnitude of the drag torque (i.e., the residual braking torque); the disc-pad clearance represents the separation distance between the brake pad and the brake disc in the non-braking state, which is related to the rationality of the required fluid volume (brake fluid filling volume) and the pedal stroke. If the return stroke is insufficient or the clearance is too small, problems such as braking drag, abnormal wear of the friction pads, and overheating deformation of the brake disc will occur; conversely, if the return stroke is too large or the clearance exceeds the standard, potential safety hazards such as redundant brake pedal stroke and delayed braking response may be caused. Therefore, accurately testing the "return stroke and clearance" performance of an opposed piston brake caliper is a key technical link for optimizing its design, improving the energy efficiency and safety of the whole vehicle.

[0003] Currently, the testing methods for brake caliper performance in the industry mostly follow the general technical solutions of floating brake calipers, but there are essential conflicts between their core testing logics and the structural characteristics of opposed piston brake calipers, which are specifically manifested in the following technical limitations:

[0004] (1) Inaccurate measurement method for the return stroke: The piston return stroke of a floating brake caliper can be indirectly estimated through the displacement of the caliper body. However, for an opposed piston brake caliper, since the caliper body is fixed, the piston return stroke needs to be directly measured through the relative displacement between the piston and the caliper housing. The existing technology uses the method of inferring from the change in fluid volume (estimating the piston displacement by measuring the volume of the brake fluid flowing back), but ignores the interference of factors such as seal deformation and the elasticity of the hydraulic pipeline, resulting in a measurement error of up to 15% - 20%, which cannot meet the high-precision calibration requirements.

[0005] (2) Deviation between gap simulation and actual working conditions: To simplify the clamping process, traditional testing devices often use steel modules to replace actual friction blocks for testing. However, the compression and rebound characteristics of friction materials under high pressure (for example, the elastic modulus of NAO materials is 1.2 - 2.5 GPa, significantly lower than 210 GPa of steel) will significantly affect the true value of the disc gap. When using steel blocks for testing, the measured gap value is 30% - 40% smaller than the actual vehicle installation state, resulting in serious distortion of the predicted drag torque.

[0006] (3) Single pressure loading mode: Existing testing standards only conduct static tests with a single pressure value (such as 10 MPa), without considering the dynamic changes of hydraulic pressure during actual vehicle braking (such as the pressure suddenly rising to 15 MPa during emergency braking and fluctuating between 1 - 5 MPa during slow braking). The lack of systematic testing of stepped pressures (1 MPa, 3 MPa, 5 MPa... 15 MPa) and different pressure increasing rates (1 MPa / sec for normal mode, 5 MPa / sec for emergency mode) makes it impossible to evaluate the performance degradation laws after long-term use, such as piston seal ring creep and guide sleeve wear.

[0007] (4) Insufficient clamping adaptability: Due to the vehicle model adaptation requirements, the mounting hole distances of opposed piston brake calipers have various specifications such as 45 mm, 60 mm, 75 mm, etc. Most existing fixtures have a fixed hole distance structure. When testing different types of calipers, the fixtures need to be frequently replaced, and it is difficult to ensure the clamping coaxiality (when the deviation > 0.5 mm, the risk of piston eccentric wear increases by 70%), which greatly affects the test efficiency and data reliability.

[0008] The above technical defects lead to the R & D and verification of opposed piston brake calipers relying heavily on later bench tests and on-road vehicle tests. The problems are as follows:

[0009] The design iteration cycle is extended: Due to the deviation between laboratory test data and actual vehicle conditions, designers need to repeatedly adjust parameters such as the piston seal groove structure and spring return force. The single design optimization cycle is as long as 3 - 4 months;

[0010] The quality control cost increases: The production end cannot quickly detect and screen products with excessive return stroke through testing. The after-sales drag failure rate increases by about 12%, and the annual recall cost of vehicle manufacturers exceeds tens of millions of yuan;

[0011] The user experience is damaged: The inaccurate gap control leads to non-linear changes in the brake pedal stroke (such as excessive "dead zone" at the beginning and abrupt "wall impact feeling" at the end), and the user complaint rate increases by 25% - 30%.

[0012] Therefore, developing a set of "return stroke and gap" performance testing methods and devices dedicated to opposed piston brake caliper assemblies to achieve high-precision, multi-condition, and full-adaptation standardized testing has become an urgent need to break through the industry's technical bottlenecks and improve the reliability of the braking system. Summary of the Invention

[0013] In view of this, the purpose of the present invention is to provide a method and device for testing the "return stroke and clearance" performance of an opposed piston brake caliper assembly, so as to analyze and evaluate the design rationality of key performance indicators such as drag torque and required liquid volume, and improve the service performance and user experience of the opposed piston brake caliper.

[0014] To achieve the above purpose, the present invention provides the following technical solutions: A method for testing the "return stroke and clearance" performance of an opposed piston brake caliper assembly, including the following steps:

[0015] S1, full-stroke lubrication: Apply pressure to the brake caliper until the piston stroke reaches 10 mm and then relieve the pressure in the state without brake pads, so that the piston completely returns to the bottom of the cylinder bore, and repeat this process 5 times;

[0016] S2, simulate the initial clearance state: Set a 2-mm gasket between the disc and the pad, apply pressure 3 times at a pressure of 10 MPa and then remove the gasket to establish the initial position of the piston;

[0017] S3, zero the displacement sensor: Gradually increase the hydraulic pressure until the piston starts to move, and zero the displacement sensor based on this initial hydraulic pressure value;

[0018] S4, multi-stage pressure test: Apply stepped pressures of 1 MPa, 3 MPa, 5 MPa, 7 MPa, 9 MPa, 11 MPa, and 15 MPa to the brake caliper in sequence. After each pressure application, relieve the pressure and hold for 120 seconds, and perform two cycles for each pressure level;

[0019] S5, record data: Measure and record the relative displacement between the piston and the brake caliper housing at each pressure level;

[0020] S6, analyze data: Generate a pressure-displacement return curve and a clearance change curve and output the results.

[0021] Optionally, in step S4, the pressurization and depressurization rates are set to two modes: 1 MPa / sec or 5 MPa / sec.

[0022] Optionally, the test objects include two modes: friction blocks and steel blocks, and different braking interfaces are simulated by replacing the friction blocks or steel blocks.

[0023] An opposed piston brake caliper assembly "return stroke and clearance" performance test device includes a connected pressurization adjustment system, a clamping and alignment unit, and a test data analysis system;

[0024] The pressurization adjustment system is composed of a liquid storage tank, a pressurization device, a pressure sensor, a flow rate control module, and a data recording module, and is used to provide controllable hydraulic pressure to the brake caliper;

[0025] The clamping and alignment unit includes a fixed clamp, an adjustable fixture, a connecting rod, a simulation disc and a thrust block. The adjustable fixture clamps the fixed clamp. The connecting rod passes through the simulation disc and contacts the bottom of the piston to be measured. The thrust block restricts the displacement of the piston at the opposite end.

[0026] The test data analysis system consists of a displacement sensor, a data recording module and a processor. The displacement sensor is installed at the end of the connecting rod to collect piston displacement data in real time.

[0027] Optionally, the adjustable fixture has an adjustable structure with multiple pitch distances and is adapted to install fixed clamps with different pitch distance sizes.

[0028] Optionally, the connecting rod aligns with the mounting holes of the friction block or steel block through the central hole of the simulation disc, and the end is connected to the displacement sensor.

[0029] Optionally, the thrust block is a rigid limiting structure for fixing the piston on the other side opposite to the test piston.

[0030] Optionally, the displacement sensor is a non-contact laser displacement sensor with a measurement accuracy of ±0.01 mm.

[0031] Optionally, the pressurizing device includes an electro-hydraulic proportional valve for precisely controlling the pressurization rate at 1 MPa / sec or 5 MPa / sec.

[0032] Optionally, the simulation disc is a detachable structure and can be replaced with a friction block or steel block test module.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1) The present invention designs a special test method for the "return stroke amount and disc-pad clearance" of the opposed piston type brake caliper assembly, realizing accurate and real tests for the return stroke amount and disc-pad clearance. Through this innovative test method, we can deeply analyze and evaluate the design rationality of key performance parameters such as drag torque and required fluid volume. This not only helps to optimize the overall design of the brake caliper and improve its performance under different working conditions, but also provides a powerful analysis basis and solution for possible failure modes and problems such as drag, drag wear, uneven wear, and poor pedal feel during the use of the end product. In addition, by accurately testing the return stroke amount and disc-pad clearance, the present invention significantly improves the design robustness of the fixed brake caliper, enhances its stability and reliability in practical applications, and thus further improves the safety and driving experience of users.

[0035] 2) The present invention innovatively proposes a test device for the "return stroke amount and disc-pad clearance" of an opposed piston brake caliper assembly, and elaborates in detail the test principle, the constituent units of the test device, and the test guarantee conditions. The test device consists of multiple modules such as a pressure regulating system, a clamping and alignment unit, and a test data analysis system. Each module is carefully designed to ensure the accuracy and reliability of the test process. By clarifying the test principle and the functions and cooperation methods of each constituent unit, the present invention provides a strong guarantee for the complete and accurate implementation of the test method. At the same time, the use of this test device also helps to improve the first-pass rate of the fixed caliper assembly research and development, greatly shortens the research and development cycle, and reduces the development time and cost of bench tests and road tests. In addition, due to the simple structure, convenient operation, and high degree of automation of the test device, it is easy to be popularized and applied in the industry, contributing new strength to the development of automotive braking test technology.

[0036] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in preferred detail below in conjunction with the accompanying drawings, where:

[0038] Figure 1 is the flowchart of the test method of the present invention;

[0039] Figure 2 is the schematic diagram of the principle composition of the test device of the present invention;

[0040] Figure 3 is the schematic diagram of the multi-spacing adjustable structure of the present invention;

[0041] Figure 4 is the curve of the test structure data processing result of the present invention.

[0042] Reference numerals: pressure regulating system 1, fixed caliper 2, adjustable fixture 3, multi-spacing adjustable structure 31, connecting rod 4, simulation disc 5, thrust block 6, test data analysis system 7. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0044] Among them, the attached drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation on the present invention; in order to better illustrate the embodiments of the present invention, some components in the attached drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted.

[0045] In the attached drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the attached drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the attached drawings are only for illustrative purposes and should not be construed as a limitation on the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0046] Please refer to Figures 1 to 4 , which is a method and device for testing the "return stroke and clearance" performance of an opposed piston brake caliper assembly. Specifically: Specific Embodiment 1:

[0048] I. Specific implementation steps of the test method

[0049] S1: Full-stroke lubrication

[0050] Operation process: Fix the brake caliper assembly on the test bench through an adjustable fixture 3 ( Figure 3 the multi-pitch adjustable structure 31 therein), ensuring that no brake pads are installed. Start the pressure regulating system 1, apply pressure to the brake caliper through the electro-hydraulic proportional valve, and make the piston stroke reach 10 mm (monitored in real time by the displacement sensor 301). Subsequently, gradually reduce the pressure to make the piston fully retract to the bottom of the cylinder bore. Repeat this process 5 times.

[0051] Purpose: Through full-stroke lubrication, reduce the frictional resistance during the piston movement and ensure the accuracy of subsequent tests.

[0052] S2: Simulate the initial clearance state

[0053] Operation process: Place a 2-mm-thick gasket (simulating the initial clearance of the brake disc) between the simulation disc 5 and the brake pad. Start the pressure regulating system 1 and apply pressure to the brake caliper three times at a pressure of 10 MPa. Then remove the gasket, and the position of the piston at this time is the initial clearance state.

[0054] Purpose: By simulating the initial clearance state of a new vehicle or after repair, provide a reference point for subsequent tests.

[0055] S3: Zero the displacement sensor

[0056] Operation process: Pass the connecting rod 4 through the central hole of the simulation disc 5, and the end touches the bottom of the piston to be measured. Install the displacement sensor (which is part of the test data analysis system 7) at the end of the connecting rod 4, and ensure that its measurement direction is consistent with the piston movement direction. Start the pressure regulating system 1, gradually increase the hydraulic pressure until the piston starts to move. Record the pressure value at this time as the initial hydraulic pressure, and perform a zeroing operation on the displacement sensor.

[0057] Purpose: By zeroing the displacement sensor, ensure the accuracy of subsequent measurement data.

[0058] S4: Multi-stage pressure test

[0059] Operation process: Apply pressure to the brake caliper in sequence according to a predetermined stepped pressure sequence (1 MPa → 3 MPa → 5 MPa → 7 MPa → 9 MPa → 11 MPa → 15 MPa). After each pressure application, hold for a period of time (such as 120 seconds), then relieve the pressure and record the data. Perform two-cycle tests for each pressure level. The pressurization and depressurization rates can be set to 1 MPa / sec or 5 MPa / sec as needed.

[0060] Purpose: By performing a multi-stage pressure test, simulate the working state of the vehicle under different braking intensities, and evaluate the dynamic change characteristics of the piston return amount and the disc-pad clearance.

[0061] S5: Record data

[0062] Operation process: During the test, the test data analysis system 7 automatically records the relative displacement data of the piston and the brake caliper housing at each pressure level;

[0063] For example, return amount: the maximum value of the piston return displacement after pressure relief; clearance deviation: the displacement difference between two tests at the same pressure level.

[0064] Purpose: Provide raw data support for subsequent data analysis.

[0065] S6: Analyze data

[0066] Operation process: Import the recorded data into the data processing software (which is part of the test data analysis system 7) to generate the pressure-displacement return curve and the clearance change curve. Analyze the design rationality of performance parameters such as the drag torque and the required liquid volume based on the curve shape, and evaluate the possible failure modes and problems.

[0067] Purpose: Provide a scientific basis for the optimized design of the brake caliper assembly through data analysis.

[0068] II. Specific implementation structure of the test device

[0069] Pressurization adjustment system 1

[0070] Composition: It includes a liquid storage tank, a pressurization device (such as an electronically controlled proportional valve), a pressure sensor, a flow rate control module, and a data recording module.

[0071] Function: Provide a controllable hydraulic pressure to the brake caliper to ensure the pressure stability and accuracy during the test.

[0072] Clamping and alignment unit

[0073] Composition:

[0074] Fixed caliper 2: Used to fix the brake caliper assembly.

[0075] Adjustable fixture 3: It includes a multi-pitch adjustable structure 31, which can adapt to the installation requirements of brake calipers with different pitches.

[0076] Connecting rod 4: Pass through the simulation disc 5 and contact the bottom of the piston under test to transmit the displacement signal.

[0077] Simulation disc 5: Replace the actual brake disc for testing.

[0078] Thrust block 6: Limit the displacement of the opposed piston to ensure the test accuracy.

[0079] Function: Fix the brake caliper assembly and provide an accurate clamping and alignment function.

[0080] Test data analysis system 7

[0081] Composition: It includes a displacement sensor (such as a non-contact laser displacement sensor), a data recording module, and a processor.

[0082] Function: Real-time collect the piston displacement data and perform processing and analysis to generate key test results such as the pressure-displacement return curve and the clearance change curve.

[0083] Specific embodiment 2,

[0084] Take the opposed piston brake caliper assembly of a certain high-performance passenger car as an example for testing (pitch 60mm, double-piston design).

[0085] Test process:

[0086] 1. Clamping and initialization:

[0087] Press Figure 3 Adjust the adjustable fixture 3 to a hole distance of 60 mm, and install the friction block test module (thickness 12 mm);

[0088] Execute steps S1 - S3 to complete lubrication, clearance simulation, and sensor zeroing.

[0089] 2. Multi - mode testing:

[0090] Normal mode: With a pressurization rate of 1 MPa / sec, the return stroke amount at 15 MPa is measured to be 1.48 mm;

[0091] Emergency mode: With a pressurization rate of 5 MPa / sec, the return stroke amount at 15 MPa is measured to be 1.52 mm (due to the instantaneous deformation of the sealing ring caused by rapid pressurization).

[0092] 3. Data comparison:

[0093] Steel block mode: The measured clearance value is 0.25 mm (22% smaller than 0.32 mm in the friction block mode), verifying the influence of the compression characteristics of the friction material on the clearance;

[0094] Repeatability error: The standard deviation of the return stroke amount in 10 tests ≤ 0.03 mm, proving the stability of the device.

[0095] In this embodiment, for the deviation of the return stroke amount in the emergency mode, it is recommended to optimize the material of the piston sealing ring.

[0096] In practical applications, the test methods and devices can be appropriately adjusted and optimized according to specific vehicle models and test requirements. For example, for the test requirements of heavy - duty commercial vehicles or motorcycle front - wheel brake calipers, the test pressure level can be appropriately increased or parameters such as the test cycle can be adjusted to improve the test accuracy and reliability.

[0097] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. The "return and clearance" performance test method of the opposed piston brake caliper assembly is characterized by: The following steps are involved: S1, full stroke lubrication: in the absence of brake pads, pressurize the brake caliper until the piston stroke reaches 10mm, then reduce the pressure to make the piston completely return to the bottom of the cylinder hole, and repeat this process 5 times; S2, simulating the initial gap state: a 2 mm gasket was set between the discs, and the gasket was removed after pressurizing at 10 MPa for 3 times to establish the initial position of the piston; S3, zeroing the displacement sensor: gradually increase the hydraulic pressure until the piston starts to move, and zero the displacement sensor based on the initial hydraulic pressure value; S4, multi-level pressure test: apply step pressures of 1MPa, 3MPa, 5MPa, 7MPa, 9MPa, 11MPa, and 15MPa to the brake caliper in sequence, release the pressure after each pressurization and keep it for 120 seconds, and perform two cycles for each pressure level; S5, recording data: measuring and recording the relative displacement between the piston and the brake caliper housing at each pressure level; S6, analyze data: generate pressure-displacement return curve and gap change curve and output the results.

2. The "return and clearance" performance test method of the opposed piston brake caliper assembly according to claim 1, characterized in that: In step S4, the rates of pressurization and depressurization are set to two modes: 1 MPa / sec or 5 MPa / sec.

3. The "return and clearance" performance test method of the opposed piston brake caliper assembly according to claim 1, characterized in that: The test objects include two modes: friction block and steel block. Different braking interfaces are simulated by replacing the friction block or steel block.

4. The "return and clearance" performance test device of the opposed piston brake caliper assembly is characterized by: It includes a connected pressurization adjustment system, a clamping alignment unit and a test data analysis system; The pressure regulation system consists of a fluid storage tank, a pressurizing device, a pressure sensor, a flow rate control module and a data recording module, and is used to provide controllable hydraulic pressure to the brake caliper; The clamping and positioning unit includes a fixed clamp, an adjustable clamp, a connecting rod, a simulation disk and a thrust block. The adjustable clamp clamps the fixed clamp, the connecting rod passes through the simulation disk and contacts the bottom of the piston to be tested, and the thrust block limits the displacement of the opposite end piston. The test data analysis system consists of a displacement sensor, a data recording module and a processor. The displacement sensor is installed at the end of the connecting rod to collect piston displacement data in real time.

5. The "return and clearance" performance test device of the opposed piston brake caliper assembly according to claim 4, characterized in that: The adjustable clamp is a multi-hole pitch adjustable structure, which is suitable for installation of fixed clamps with different hole pitch sizes.

6. The "return and clearance" performance test device of the opposed piston brake caliper assembly according to claim 4, characterized in that: The connecting rod is aligned with the mounting hole of the friction block or the steel block through the central hole of the simulation disk, and the end is connected to the displacement sensor.

7. The "return and clearance" performance test device of the opposed piston brake caliper assembly according to claim 4, characterized in that: The thrust block is a rigid limiting structure, which is used to fix the other piston opposite to the test piston.

8. The "return and clearance" performance test device of the opposed piston brake caliper assembly according to claim 4, characterized in that: The displacement sensor is a non-contact laser displacement sensor with a measurement accuracy of ±0.01mm.

9. The "return and clearance" performance test device of the opposed piston brake caliper assembly according to claim 4, characterized in that: The pressurizing device includes an electrically controlled proportional valve for accurately controlling the pressurizing rate to be 1 MPa / sec or 5 MPa / sec.

10. The "return and clearance" performance test device of the opposed piston brake caliper assembly according to claim 4, characterized in that: The simulation disc is a detachable structure and can be replaced by a friction block or a steel block test module.

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