New energy automobile braking dragging resistance test and comprehensive evaluation method

Abstract

The invention discloses a new energy automobile brake dragging resistance test and comprehensive evaluation method, and belongs to the technical field of automobile safety performance test.The method comprises the steps that brake disc surface height distribution data are measured and processed, and brake disc end jumping amount distribution data are obtained; constructing a braking dragging force comprehensive horizontal correction model based on the mileage; and based on the brake dragging force test data and the brake disc end jumping amount distribution data, a brake dragging force comprehensive evaluation model is constructed. According to the brake dragging force comprehensive evaluation method based on the brake disc end jump amount, the brake disc end jump amount test is added, the vehicle driving mileage is combined, the brake dragging force comprehensive evaluation method based on the brake disc end jump amount is established, the influence conditions of the brake disc end jump amount and brake caliper return control on the brake dragging force can be effectively distinguished, and the method has important value for guiding new energy vehicle brake dragging force optimization.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle safety performance testing, and more specifically, to a new energy vehicle brake drag resistance testing and comprehensive evaluation method. Background Art

[0002] As the new energy vehicle market continues to expand, the cruising range of pure electric vehicles has become the focus of consumers. This is not only related to the convenience of users' daily travel, but also one of the important indicators for measuring the maturity of electric vehicle technology. In order to improve the cruising range, in addition to increasing battery capacity and energy density, reducing the energy consumption during vehicle driving is also critical, among which reducing driving resistance is one of the important strategies. Compared with traditional fuel vehicles, new energy vehicles are more direct and responsive in power output. This feature makes their braking system face a higher workload, and the wear of the brake disc is also aggravated. Braking drag, that is, the additional resistance generated by internal friction or jamming of the braking system when the vehicle is stationary or driving at low speed, has become an important factor affecting energy consumption and cruising range. The optimization of braking drag is crucial to improving the energy efficiency of new energy vehicles. It not only directly affects the sliding distance and energy consumption of the vehicle, but also affects the life and reliability of the braking system. Therefore, major automakers have invested resources to study how to reduce braking drag by optimizing the design of the braking system, improving the return control of the brake caliper, and controlling the end jump of the brake disc.

[0003] At present, the main methods for the industry to carry out brake drag force testing and comprehensive evaluation are as follows:

[0004] Motor reverse drag wheel test method: The motor drives the wheel in reverse to simulate the vehicle's sliding state, and measures the drag torque before and after the brake friction pads are removed. By comparing the two sets of data, the drag force generated by the braking system can be calculated; the magnitude of the drag force directly reflects the resistance level of the vehicle in the non-braking state.

[0005] However, the current road condition prediction methods have the following problems:

[0006] Lack of testing of brake disc status: Existing testing methods often only focus on the magnitude of the drag force, while ignoring the effect of the brake disc's own status (such as wear, end runout, etc.) on the drag force;

[0007] The evaluation content is single: the current evaluation system mainly focuses on the drag force value, and fails to fully consider the effect of brake caliper return control, brake disc end jump, and the impact of mileage on brake disc thickness and performance. These factors are interrelated and work together on the braking system. A single evaluation indicator is difficult to fully and accurately reflect the system performance. Summary of the invention

[0008] One purpose of the present invention is to provide a new energy vehicle brake drag resistance test and comprehensive evaluation method to solve the aforementioned lack of testing of the brake disc state, single evaluation content, and difficulty in fully and accurately reflecting the system performance.

[0009] According to a first aspect of the present invention, a method for testing and comprehensively evaluating brake drag resistance of a new energy vehicle is provided, comprising:

[0010] Measure the brake disc surface height distribution data and process the data to obtain the brake disc end jump distribution data;

[0011] Construct a comprehensive level correction model of brake drag force based on mileage;

[0012] Based on the brake drag force test data and brake disc end jump distribution data, a comprehensive evaluation model for brake drag force is constructed.

[0013] Optionally, before the step of measuring the brake disc surface height distribution data and performing data processing to obtain the brake disc end jump amount distribution data, the step further includes:

[0014] The wheel hub anti-drag torque is tested before and after the friction block is removed, and the resistance torque after the friction block is removed is subtracted from the resistance torque measured before the friction block is removed to obtain the brake drag force test data.

[0015] Optionally, the steps of measuring the brake disc surface height distribution data and performing data processing to obtain the brake disc end jump distribution data include:

[0016] Use a displacement sensor to scan the surface of the brake disc and record the height data of each point on the surface of the brake disc;

[0017] Taking the lowest point on the brake disc surface as the reference zero point, the height data of all measuring points are normalized;

[0018] The height data of all measuring points are converted into a three-dimensional model or a two-dimensional contour map of the brake disc surface, and the brake disc end runout distribution data is calculated.

[0019] Optionally, before using the displacement sensor to scan the surface of the brake disc, the displacement sensor is installed perpendicular to the end surface of the brake disc so that the contact point of the displacement sensor is located in the middle of the braking area.

[0020] Optionally, the step of constructing a brake drag force comprehensive level correction model based on mileage includes:

[0021] The vehicle mileage is read through the vehicle instrument, and the value of the correction coefficient δ is obtained in combination with a preset mileage-correction coefficient mapping table.

[0022] Optionally, based on the brake drag force test data and the brake disc end bounce distribution data, the step of constructing a brake drag force comprehensive evaluation model includes:

[0023] Integrate brake drag force test data with brake disc end bounce distribution data;

[0024] According to the conversion of the brake disc speed into the rotation angle, the relationship between the brake disc end jump distribution data and the drag force test data is obtained, and a linear fit is performed;

[0025] Draw a model diagram of the relationship between brake disc end runout and drag force, and extract corresponding evaluation indicators.

[0026] Optionally, extracting corresponding evaluation indicators includes:

[0027] Extract the drag force a value when the end jump is 0;

[0028] Extract the maximum value b of the end jump;

[0029] Extract the drag force d corresponding to the maximum end jump;

[0030] The first area and the second area in the relationship model diagram are determined based on the drag force a value, the maximum end jump value b, and the drag force d corresponding to the maximum end jump value.

[0031] Optionally, performing evaluation according to the extracted evaluation index includes:

[0032] (A+B)*δ is configured to indicate the comprehensive level of vehicle brake drag;

[0033] B / (A+B) is configured to indicate the degree of influence of the caliper return control on the vehicle brake drag force;

[0034] A / (A+B) is configured to indicate the degree of influence of brake disc end jump on the vehicle's brake drag force.

[0035] The new energy vehicle brake drag resistance test and comprehensive evaluation method disclosed in the present invention has the following technical effects:

[0036] The present invention increases the acquisition of brake disc end jump distribution data, constructs a brake drag force comprehensive level correction model based on mileage, and establishes a brake drag force comprehensive evaluation method combined with brake disc end jump. It can effectively distinguish the influence of brake disc end jump and brake caliper return control on brake drag force, which is of great value for guiding the optimization of brake drag force of new energy vehicles.

[0037] The method of the present invention has comprehensive testing and evaluation content, can accurately locate the influencing factors of the brake drag problem, and effectively support the optimization of the vehicle brake drag problem.

[0038] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0040] Figure 1 A schematic diagram of a flow chart of a new energy vehicle brake drag resistance test and comprehensive evaluation method provided by an embodiment of the present invention;

[0041] Figure 2 A model diagram of the relationship between the end jump amount and the drag force of the new energy vehicle brake drag resistance test and comprehensive evaluation method provided by the embodiment of the present invention;

[0042] Figure 3 A schematic diagram of the relationship between end jump and drag force of a new energy vehicle brake drag resistance test and comprehensive evaluation method provided by an embodiment of the present invention;

[0043] Figure 4 A model diagram of the relationship between end jump and drag force of a new energy vehicle brake drag resistance test and comprehensive evaluation method provided by another embodiment of the present invention;

[0044] Figure 5 A list of correction coefficient δ values ​​for the new energy vehicle brake drag resistance test and comprehensive evaluation method provided by an embodiment of the present invention;

[0045] Figure 6 A schematic diagram of the position of the end jump measuring points of the new energy vehicle brake drag resistance test and comprehensive evaluation method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0047] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0048] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0049] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0050] The current brake drag force test and comprehensive evaluation method has the following problems: it ignores the effect of the brake disc's own state (such as wear, end runout, etc.) on the drag force; it fails to fully consider the effect of the brake caliper return control, the brake disc end runout, and the impact of mileage on the brake disc thickness and performance. A single evaluation index is difficult to fully and accurately reflect the system performance. This application adds a brake disc end runout test, combines the vehicle mileage, and establishes a brake drag force comprehensive evaluation method combined with the brake disc end runout. It can effectively distinguish the impact of the brake disc end runout and the brake caliper return control on the brake drag force, which is of great value in guiding the optimization of the brake drag force of new energy vehicles.

[0051] The present invention proposes an embodiment of a method for testing and comprehensively evaluating the braking drag resistance of a new energy vehicle. Specifically, Figure 1 As shown, the following steps are included:

[0052] The brake disc surface height distribution data is measured and processed to obtain the brake disc end runout distribution data; the brake disc surface height distribution data reflects the flatness, wear and possible deformation of the brake disc surface. The collected height data is processed to remove noise and outliers to ensure data accuracy.

[0053] A brake drag force comprehensive level correction model based on mileage is constructed; wherein the brake drag force comprehensive level correction model can dynamically correct the brake drag force according to the vehicle's mileage.

[0054] Based on the brake drag force test data and the brake disc end jump distribution data, a brake drag force comprehensive evaluation model is constructed. This comprehensive evaluation model not only takes into account the size of the brake drag force, but also comprehensively considers multiple factors such as the wear condition of the brake disc and the vehicle mileage, thereby achieving a comprehensive and objective evaluation of the brake system performance.

[0055] In an embodiment of the present invention, before the step of measuring the brake disc surface height distribution data and performing data processing to obtain the brake disc end jump amount distribution data, the step further includes:

[0056] The wheel hub anti-drag torque is tested before and after the friction block is removed. The resistance torque measured before the friction block is removed is subtracted from the resistance torque after the friction block is removed to obtain the brake drag test data. Among them, when the wheel hub is reversely rotated by an external force (such as a test device) in a non-driven state, a torque that hinders the rotation of the wheel hub will be generated due to the friction and resistance of the braking system inside the wheel. This torque is called the wheel hub anti-drag torque. In the braking system, the friction block (usually refers to the brake pad or brake pad) is a key component that generates braking torque.

[0057] In an embodiment of the present invention, the steps of measuring the brake disc surface height distribution data and performing data processing to obtain the brake disc end jump distribution data include:

[0058] A displacement sensor is used to scan the surface of the brake disc and record the height data of each point on the surface of the brake disc; wherein the displacement sensor is a high-precision displacement sensor, including but not limited to a laser displacement sensor, a contact displacement sensor (such as an LVDT sensor), etc.

[0059] The lowest point on the brake disc surface is used as the reference zero point to normalize the height data of all measurement points. After collecting the height data of all measurement points, the minimum value of these data, i.e., the lowest point on the brake disc surface, is first found. The height data of all measurement points is normalized by subtracting the value of the reference zero point. Normalization helps eliminate errors introduced by different selections of measurement reference surfaces.

[0060] The height data of all measurement points are converted into a three-dimensional model or two-dimensional contour map of the brake disc surface, and the brake disc end runout distribution data is calculated. The normalized height data is imported into a three-dimensional modeling software or data visualization tool, and a three-dimensional model or two-dimensional contour map of the brake disc surface is constructed based on the spatial position information (such as X, Y coordinates) and height data (Z coordinate) of the measurement points.

[0061] In an embodiment of the present invention, before using the displacement sensor to scan the brake disc surface, the displacement sensor is installed perpendicular to the end face of the brake disc so that the contact of the displacement sensor is located in the middle of the braking area; ensuring that the displacement sensor can accurately and stably measure the height change of the brake disc surface while reducing the error introduced by improper installation position.

[0062] In an embodiment of the present invention, the step of constructing a brake drag force comprehensive level correction model based on mileage includes:

[0063] The vehicle mileage is read through the vehicle instrument and combined with the preset mileage-correction factor mapping table, such as Figure 5 As shown, the value of the correction coefficient δ is obtained.

[0064] In an embodiment of the present invention, based on the brake drag force test data and the brake disc end bounce distribution data, the steps of constructing a brake drag force comprehensive evaluation model include:

[0065] Integrate brake drag force test data with brake disc end bounce distribution data;

[0066] According to the conversion of the brake disc speed into the rotation angle, the relationship between the brake disc end jump distribution data and the drag force test data is obtained, and a linear fit is performed;

[0067] Draw a model diagram of the relationship between the brake disc end runout and the drag force, such as Figure 2 As shown, the corresponding evaluation indicators are extracted; the corresponding evaluation indicators include:

[0068] Extract the drag force a value when the end jump is 0;

[0069] Extract the maximum value b of the end jump;

[0070] Extract the drag force d corresponding to the maximum end jump;

[0071] The area of ​​the first region (i.e., the area of ​​the shadow region A) and the area of ​​the second region (i.e., the area of ​​the shadow region B) in the relationship model diagram are determined based on the drag force a value, the maximum end jump value b, and the drag force d corresponding to the maximum end jump value.

[0072] In an embodiment of the present invention, performing evaluation according to the extracted evaluation index includes:

[0073] (A+B)*δ is configured to indicate the comprehensive level of the vehicle's braking drag force, and the smaller the value, the higher the comprehensive level of the braking drag force;

[0074] B / (A+B) is configured to indicate the degree of influence of the caliper return control on the vehicle's brake drag force. The smaller the value, the lower the influence of the caliper return control on the brake drag force, and vice versa.

[0075] A / (A+B) is configured to indicate the degree of influence of brake disc end jump on the vehicle's brake drag force. The smaller the value, the lower the influence of brake disc end jump on the brake drag force, and vice versa.

[0076] The present invention establishes a comprehensive brake drag force evaluation scheme based on the braking operating conditions of new energy vehicles, and constructs a comprehensive brake drag force evaluation method, which can accurately identify the influence of brake disc end jump and brake caliper return control on the drag force, and can effectively support the brake drag force optimization of the product.

[0077] In another embodiment of the present invention, a method for testing and comprehensively evaluating brake drag resistance of a new energy vehicle is proposed, comprising:

[0078] A high-precision displacement sensor is selected to measure the brake disc height. The displacement sensor is a Keyence GT2 displacement sensor with a measurement range of 0 to 100 mm, a measurement accuracy of ±0.5% FS, and a resolution of 0.1 microns.

[0079] Installation requirements for displacement sensors: The displacement sensor is perpendicular to the end face of the brake disc, and the contact of the displacement sensor is located in the middle of the braking area; install the displacement sensor on a bracket or fixture, and carefully adjust its direction to ensure that the measuring axis of the displacement sensor (i.e., the center line from the contact to the displacement sensor) is perpendicular to the end face of the brake disc, and adjust the position of the displacement sensor so that its contact (i.e., the measuring point) is located in the middle of the braking area; after confirming that the direction and contact position of the displacement sensor are correct, use appropriate fasteners (such as screws, nuts, etc.) to firmly fix the displacement sensor on the bracket or fixture, where the position of the brake disc end jump measuring point is as follows: Figure 6 As shown;

[0080] Rotate the brake disc at a constant speed of 5r / min to measure the displacement of the displacement sensor. The data sampling rate should be no less than 10Hz, that is, at least 10 data points should be collected per second.

[0081] Data processing of brake drag force test data and brake disc end jump distribution data, including:

[0082] 1) Draw the relationship curve between vehicle braking drag force and brake disc end jump, and fit the relationship between drag force and end jump; Figure 3 As shown, it is divided into two sections: the end jump section of 0-10um, the drag force is 2.6N*m, and the end jump section of 10-14.5um, the relationship equation between the drag force and the end jump is y= 0.49x-2.3, where y represents the drag force and x represents the end jump;

[0083] 2) Draw a schematic diagram of the drag force analysis, such as Figure 4 As shown;

[0084] 3) If Figure 4 As shown, the area of ​​shaded area A is 4.95, and the area of ​​shaded area B is 37.7;

[0085] Analyze the factors affecting the drag force: B / (A+B) of this vehicle is 0.88, and A / (A+B) is 0.12, which means that the caliper return control has a great influence on the brake drag force of this vehicle, and the brake disc end jump has a relatively low influence on the brake drag force of this vehicle. It is necessary to focus on optimizing the caliper return control, which can significantly reduce the drag problem of this vehicle.

[0086] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings, but the above is only a preferred embodiment of the present invention. It should be noted that the technical features involved in the above embodiments and their preferred methods can be reasonably combined and matched into a variety of equivalent schemes by those skilled in the art without departing from or changing the design ideas and technical effects of the present invention; therefore, the present invention is not limited to the scope of implementation shown in the drawings, and all changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the specification and drawings, should be within the protection scope of the present invention.

Claims

1. A new energy vehicle brake drag resistance test and comprehensive evaluation method, It is characterized in that include: Measure the brake disc surface height distribution data and process the data to obtain the brake disc end jump distribution data; Construct a comprehensive level correction model of brake drag force based on mileage; Based on the brake drag force test data and brake disc end jump distribution data, a comprehensive evaluation model for brake drag force is constructed.

2. The new energy vehicle brake drag resistance test and comprehensive evaluation method according to claim 1, It is characterized in that Before the step of measuring the brake disc surface height distribution data and performing data processing to obtain the brake disc end jump distribution data, the method further includes: The wheel hub anti-drag torque is tested before and after the friction block is removed, and the resistance torque after the friction block is removed is subtracted from the resistance torque measured before the friction block is removed to obtain the brake drag force test data.

3. The new energy vehicle brake drag resistance test and comprehensive evaluation method according to claim 1, It is characterized in that The steps of measuring the brake disc surface height distribution data and performing data processing to obtain the brake disc end jump distribution data include: Use a displacement sensor to scan the surface of the brake disc and record the height data of each point on the surface of the brake disc; Taking the lowest point on the brake disc surface as the reference zero point, the height data of all measuring points are normalized; The height data of all measuring points are converted into a three-dimensional model or a two-dimensional contour map of the brake disc surface, and the brake disc end runout distribution data is calculated.

4. The new energy vehicle brake drag resistance test and comprehensive evaluation method according to claim 3, It is characterized in that Before using the displacement sensor to scan the brake disc surface, the displacement sensor is installed perpendicular to the end face of the brake disc so that the contact point of the displacement sensor is located in the middle of the braking area.

5. The new energy vehicle brake drag resistance test and comprehensive evaluation method according to claim 1, It is characterized in that The steps of constructing a comprehensive level correction model of brake drag force based on mileage include: The vehicle mileage is read through the vehicle instrument, and the value of the correction coefficient δ is obtained in combination with a preset mileage-correction coefficient mapping table.

6. The new energy vehicle brake drag resistance test and comprehensive evaluation method according to claim 1, It is characterized in that Based on the brake drag force test data and the brake disc end jump distribution data, the steps of constructing a brake drag force comprehensive evaluation model include: Integrate brake drag force test data with brake disc end bounce distribution data; According to the conversion of the brake disc speed into the rotation angle, the relationship between the brake disc end jump distribution data and the drag force test data is obtained, and a linear fit is performed; Draw a model diagram of the relationship between brake disc end runout and drag force, and extract corresponding evaluation indicators.

7. The new energy vehicle brake drag resistance test and comprehensive evaluation method according to claim 6, It is characterized in that The corresponding evaluation indicators are extracted including: Extract the drag force a value when the end jump is 0; Extract the maximum value b of the end jump; Extract the drag force d corresponding to the maximum end jump; The first area and the second area in the relationship model diagram are determined based on the drag force a value, the maximum end jump value b, and the drag force d corresponding to the maximum end jump value.

8. The method for testing and comprehensively evaluating the braking drag resistance of new energy vehicles according to any one of claims 5 or 7, It is characterized in that Evaluation based on the extracted evaluation indicators includes: (A+B)*δ is configured to indicate the comprehensive level of vehicle brake drag; B / (A+B) is configured to indicate the degree of influence of the caliper return control on the vehicle brake drag force; A / (A+B) is configured to indicate the degree of influence of brake disc end jump on the vehicle's brake drag force.

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