A dynamic detection method for brake shoe friction force

Abstract

The present invention belongs to the field of rail transit braking technology, and discloses a dynamic detection method for brake shoe friction. The specific scheme is as follows: using computer digital simulation technology, force analysis is performed on brake-related components, and the stress-deformation sensitive points are found according to the correlation between the local deformation of different parts of each brake-related component and the braking friction. The present invention directly obtains the wheel braking friction by real-time detection of the stress-strain conditions of the stress-deformation sensitive points of brake force components such as brake shoes or brake shoe supports, avoiding the existing dynamic braking friction value obtained by assuming that the friction coefficient is a constant, and being unable to respond in real time to the changes in the friction coefficient with changes in vehicle speed, temperature rise during braking, ambient humidity, etc. The present invention solves the above-mentioned deficiencies of the existing dynamic braking friction measurement method, and improves the vehicle's driving safety, reliability, running comfort and control convenience.

Description

Technical Field

[0001] The invention belongs to the technical field of rail transit braking, and in particular is a method for dynamically detecting brake shoe braking friction force. Background Art

[0002] Braking control technology is a key technology for rail vehicles, which is related to vehicle driving safety, operational reliability, comfort and other aspects. The key to braking control technology is to apply matching braking friction according to the vehicle braking demand instruction. At present, the actual applied value of braking friction is obtained indirectly. Some are converted into positive pressure by measuring the air pressure value of the brake cylinder and then multiplied by the friction coefficient (set as a constant value) to obtain the braking friction. However, due to product manufacturing differences, this indirect measurement method will have different efficiency factors when the air pressure value is converted into positive pressure. At the same time, the friction material performance, vehicle speed, temperature rise during braking, ambient humidity, etc. have a huge impact on the friction coefficient, resulting in a large deviation in the converted braking friction. There are also methods that bury a force sensor between the brake shoe and the wheel to directly measure the positive pressure, and then multiply it by the friction coefficient (set as a constant value) to obtain the braking friction, but this solution still cannot eliminate the influence of the change in the friction coefficient. There are also some methods that obtain the speed and acceleration through a speed sensor or an acceleration sensor and then indirectly calculate the braking friction, but there are also problems such as difficulty in reference selection and delayed response, which leads to a lag in the adjustment of the braking friction and cannot well meet the needs of real-time detection and adjustment of vehicle anti-skid processes. Summary of the invention

[0003] The purpose of the present invention is to solve the above problems. The present invention provides a method for dynamic detection of brake shoe friction force to solve the problems existing in the background technology.

[0004] To achieve the above purpose, the present invention provides the following technical solution: a method for dynamic detection of brake shoe friction force, the specific solution is as follows:

[0005] S1. Use computer digital simulation technology to analyze the stress of brake-related components under the influence of various external forces during the braking process. Find the stress-deformation sensitive points based on the correlation between the local deformation of different parts of each brake-related component and the braking friction force;

[0006] S2. Install the sensor assembly at the above-mentioned stress-deformation sensitive point;

[0007] S3. During the braking process, the detection and calculation unit installed near the sensor assembly or other positions of the vehicle collects and integrates the data of all the above sensor assemblies, analyzes and processes the data through software algorithms using mathematical statistics principles, filters out various interference or abnormal data, estimates the braking friction force, and iteratively optimizes the criteria based on the estimation;

[0008] S4. On a device that is completely consistent with the actual working state and can directly and accurately measure the brake friction force (i.e., the production process equipment in the laboratory), under the condition that all possible working environment parameters can be correctly covered, based on the comparison results of the measured brake friction force (relative true value, as the measurement reference value) and the estimated value (indication) of this method, a correction function of the brake friction force estimation relative to the working environment parameters is established through a software algorithm;

[0009] S5. Apply the above correction function to the actual device to correct the estimated value of the braking friction force obtained by this method and output it as the detection value of the braking friction force.

[0010] The present invention obtains the dynamic braking friction force of the brake shoe by performing strain detection on the stress-deformation sensitive points of the brake-related components during the braking process. The measurement is direct and easy to implement.

[0011] The strain sensor and the sensors related to working environment parameters such as temperature, humidity, vibration, etc. in the present invention can be directly installed on the surface of existing brake components without causing damage to the existing product structure, and the installation is simple and convenient.

[0012] The present invention obtains the dynamic braking friction force of the brake shoe through the stress deformation caused by the braking force. The influencing factor of this detection method is only related to the material deformation characteristics of the force-bearing components. The force-bearing areas used by the force-bearing components on normal vehicle products are all within the elastic deformation range, with high linearity (even if there is a certain nonlinearity, it can be corrected by the material characteristic curve). Therefore, the detection result is highly accurate.

[0013] The present invention obtains the dynamic braking friction force of the brake shoe through the stress deformation caused by the braking force, and has good real-time performance. As long as the component material is subjected to force, it will deform. This is the characteristic of the material. The change of force and deformation occur simultaneously. Therefore, the present detection method obtains the dynamic braking friction force of the brake shoe by detecting the stress deformation, and has high real-time performance.

[0014] In general, compared with detection methods such as burying force sensors in the positive pressure direction or installing velocity sensors, acceleration sensors, etc., the present invention has a simple concept, is easy to install, will not damage the original product structure, is easy to implement, and can obtain more accurate measurement results in real time.

[0015] As a preferred technical solution of the present invention, the sensor assembly includes but is not limited to strain sensors and sensors related to working environment parameters such as temperature, humidity, and vibration. The detection operation unit includes but is not limited to a data acquisition unit and an operation analysis unit. The output end of the sensor assembly is electrically connected to the input end of the data acquisition, and the output end of the data acquisition is electrically connected to the input end of the operation analysis unit.

[0016] As a preferred technical solution of the present invention, the computer digital simulation technology includes but is not limited to ANSYS and MATLAB finite element simulation analysis technology.

[0017] As a preferred technical solution of the present invention, the brake-related components include brake shoes, brake shoe supports, and other brake force-bearing components on the vehicle.

[0018] As a preferred technical solution of the present invention, the sensitive points include points that have a high correlation with deformation in both the friction force direction and the positive pressure direction during the braking process, points that have a high correlation with deformation in the friction force direction and a low correlation with deformation in the positive pressure direction, and points that have a high correlation with deformation in the positive pressure direction and a low correlation with deformation in the friction force direction.

[0019] As a preferred technical solution of the present invention, the correction function includes the influence of the temperature and humidity environment on the stress-deformation amount of the force, and also includes the influence of other working environments such as vibration on the stress-deformation amount of the force.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention directly obtains the wheel braking friction force by real-time detection of the stress and strain of brake shoe or brake shoe support and other brake force-bearing components, thereby avoiding the disadvantage that the existing dynamic braking friction force value obtained by assuming the friction coefficient to be a constant cannot reflect the change of the friction coefficient with the vehicle speed, temperature rise during braking, ambient humidity and the like in real time. It also avoids the disadvantage that the braking friction force value indirectly calculated by the speed sensor and the acceleration sensor has a delayed response and is not convenient for active and real-time precise control of the braking friction force during braking.

[0022] The beneficial effect of the present invention is that the dynamic braking friction of the brake shoe can be detected in real time through the above-mentioned measurement method, which has the advantages of direct measurement, high accuracy and good real-time performance. The vehicle can quickly and accurately adjust the braking friction according to the real-time detection result. Due to the improved adjustment accuracy, the adjustment times and time of the corresponding braking control components can be reduced, the life of the vehicle braking system and the braking response speed can be improved, and the braking wheel rubbing, braking accidents and the like caused by inaccurate braking friction and delayed response can be effectively reduced. At the same time, it is also convenient to realize precise control of vehicle speed, acceleration, parking distance, etc., which can improve the comfort and convenience of vehicle operation. In addition, the invention can facilitate the consistency control of the deceleration of coupled vehicles, effectively reduce the coupling force between vehicles and the longitudinal impact of vehicles. In general, the present invention solves the shortcomings of the existing dynamic braking friction measurement method mentioned above, and improves the driving safety, reliability, operation comfort and control convenience of vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of force analysis of the brake shoe friction force of the present invention;

[0024] Figure 2 The schematic diagram of the brake shoe friction force dynamic detection method of the present invention;

[0025] Figure 3 This is an example diagram of the sensor arrangement of the present invention.

[0026] In the figure: 1. wheel; 2. brake shoe; 3. brake shoe support; 4. first strain sensor; 5. first temperature and humidity sensor; 6. first vibration sensor; 7. second strain sensor; 8. second temperature and humidity sensor; 9. second vibration sensor; 10. sensor assembly; 20. detection operation unit. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The present invention provides an embodiment of a brake shoe friction force dynamic detection method, in which, Figure 2 As shown, the detection method mainly includes two parts: a sensor component 10 and a detection operation unit 20, which can realize real-time detection and output of dynamic brake shoe braking friction value.

[0029] The above-mentioned sensor assembly includes a strain sensor and sensors related to working environment parameters such as temperature, humidity, vibration, etc. for compensation and correction, and is installed on brake shoes, brake shoe supports or other brake-related force-bearing components.

[0030] The above-mentioned detection operation unit mainly includes functional modules such as data acquisition, signal amplification, operation circuit (including software algorithm), and shell protection. The unit can be packaged together with any of the sensors and arranged at the sensor, or it can be separated from the sensor and installed at any convenient installation position on the vehicle.

[0031] Figure 1 The schematic diagram of force analysis of the brake shoe friction force of the present invention, the brake shoe friction force f = μFn;

[0032] Among them, μ is the friction coefficient of the contact surface between the brake shoe and the wheel;

[0033] Fn is the normal pressure of the arc of contact between the wheel and the brake shoe;

[0034] f is the braking friction force in the tangential direction of the contact arc between the wheel and the brake shoe;

[0035] Relatively speaking, the normal positive pressure can be detected or calculated by means of force sensors, brake cylinder pressure, etc., but the tangential braking friction force cannot be directly measured by force sensors. At present, the friction coefficient is set as a constant, and the brake shoe friction force is obtained by multiplying the positive pressure Fn by the friction coefficient μ. However, since the friction coefficient is related to many factors such as the characteristics of the brake shoe friction material, the vehicle speed, the dryness of the friction pair contact surface, and the temperature rise during braking, it has great uncertainty. Therefore, the conversion method of setting the friction coefficient as a constant through positive pressure has great uncertainty, and the actual deviation is often large; there are also some methods that use speed sensors or acceleration sensors to obtain speed and acceleration and then indirectly calculate the braking friction force, but there are also problems such as difficult reference selection and delayed response. The above are the difficulties to be solved by the present invention.

[0036] Figure 3 This is an example diagram of the installation and arrangement of the sensor components of the present invention. The large circle at position No. 1 is a wheel, No. 2 in contact with the wheel is a brake shoe, and No. 3 is in contact with the rear end of the brake shoe. Strain sensors No. 4 and No. 7, temperature and humidity sensors No. 5 and No. 8, and vibration sensors No. 6 and No. 9 are installed and arranged on the brake shoe support. In addition, strain sensors No. 11 and No. 14, temperature and humidity sensors No. 12 and No. 15, and vibration sensors No. 13 and No. 16 are installed and arranged at the same position on the back of the brake shoe support.

[0037] In this embodiment, the strain sensors 4, 7, 11, and 14 in the sensor assembly are used to detect the stress deformation in the tangent and normal directions of the above-mentioned sensitive points during braking in real time, and feed back to the acquisition circuit of the detection operation unit. The detection operation unit calculates the braking friction force through a software algorithm.

[0038] In this embodiment, the temperature and humidity sensors 5, 8, 12, 15 and the vibration sensors 6, 9, 13, 16 in the sensor assembly detect the temperature, humidity and vibration conditions of the corresponding positions of the brake shoe support during braking in real time, and feed them back to the detection operation unit. The detection operation unit corrects the detected stress and deformation according to the temperature, humidity, vibration conditions and material properties, thereby eliminating the influence of such working environment on the detected braking friction results.

[0039] The beneficial effect of the present invention is that the dynamic braking friction of the brake shoe can be detected in real time through the above-mentioned measurement method, which has the advantages of direct measurement, high accuracy and good real-time performance. The vehicle can quickly and accurately adjust the braking friction according to the real-time detection results. Due to the improved adjustment accuracy, the adjustment times and time of the corresponding braking control components can be reduced, the life of the vehicle braking system and the braking response speed can be improved, and the braking wheel rubbing and braking accidents caused by inaccurate braking friction and delayed response can be effectively reduced. At the same time, it is also convenient to realize the precise control of vehicle speed, acceleration, parking distance, etc., which can improve the comfort and convenience of vehicle operation. In addition, the invention can easily realize the consistency control of the deceleration of coupled vehicles, effectively reducing the coupling force between vehicles and the longitudinal impact of vehicles;

[0040] In general, the present invention solves the above-mentioned deficiencies of the existing dynamic brake friction force measurement method and improves the driving safety, reliability, running comfort and control convenience of the vehicle.

[0041] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0042] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for dynamic detection of brake shoe friction force, characterized in that: The specific plan is as follows: S1. Use computer digital simulation technology to analyze the stress of brake-related components under the influence of various external forces during the braking process, and find out the stress-deformation sensitive points according to the correlation between the local deformation of different parts of each brake-related component and the braking friction force; S2. Install the sensor assembly at the above-mentioned stress-deformation sensitive point; S3. During the braking process, the detection and calculation unit installed near the sensor component or other locations of the vehicle collects and fuses the data of all sensor components, analyzes and processes the data through software algorithms using mathematical statistics principles, filters out various interference or abnormal data, estimates the braking friction force, and iteratively optimizes the criteria based on the estimation; S4. On a device that is completely consistent with the actual working state and can directly and accurately measure the brake friction force, under the condition that all possible working environment parameters can be correctly covered, according to the comparison result of the measured brake friction force and the estimated value of this method, a correction function of the brake friction force estimation relative to the working environment parameters is established through a software algorithm; S5, applying the correction function to the actual device, correcting the estimated braking friction force obtained by the method, and outputting the result as the detected value of the braking friction force; The sensor assembly includes a strain sensor and sensors related to temperature, humidity, vibration and other working environment parameters. The detection operation unit includes a data acquisition unit and an operation analysis unit. The output end of the sensor assembly is electrically connected to the input end of the data acquisition, and the output end of the data acquisition is electrically connected to the input end of the operation analysis unit. The sensitive points include points that have a high correlation with deformation in both the friction force direction and the positive pressure direction during the braking process, points that have a high correlation with deformation in the friction force direction and a low correlation with deformation in the positive pressure direction, and points that have a high correlation with deformation in the positive pressure direction and a low correlation with deformation in the friction force direction.

2. A brake shoe friction force dynamic detection method according to claim 1, characterized in that: The computer digital simulation technology includes ANSYS and MATLAB finite element simulation analysis technology.

3. A brake shoe friction force dynamic detection method according to claim 1, characterized in that: The brake-related components include brake shoes, brake shoe supports and other brake-loaded components on the vehicle.

4. A brake shoe friction force dynamic detection method according to claim 1, characterized in that: The correction function includes the influence of the temperature and humidity environment on the stress and deformation, as well as the influence of vibration and other working environments on the stress and deformation.

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