Brake-by-wire master cylinder transmission mechanism friction characteristic test bench and method thereof

Abstract

The invention relates to the technical field of drive-by-wire hydraulic brake systems, in particular to a drive-by-wire brake master cylinder transmission mechanism friction characteristic test bed and a method thereof. The device comprises a fixing support, and an input end is arranged on the fixing support. According to the invention, decoupling test of the transmission mechanism and the hydraulic pipeline and elimination of hydraulic pressure interference can be realized; an input source is replaced by servo motor input, so that the input is controllable, and the input accuracy is improved compared with the input of manually treading a brake pedal; the thrust of the master cylinder push rod of the drive-by-wire brake master cylinder transmission mechanism is borne by the stress spring with lower use cost, so that a force sensor with higher use cost and variable stroke is avoided; meanwhile, improvement can be carried out on the basis of the device, when the friction characteristics of the system transmission mechanism are tested, the friction characteristics in the full friction process can be accurately tested according to the testing method, accurate measurement of the friction force of the drive-by-wire brake master cylinder transmission mechanism is achieved, and the robustness of pressure control of the drive-by-wire hydraulic brake system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wire-controlled hydraulic brake systems, and in particular to a friction characteristic test bench and method for a wire-controlled brake master cylinder transmission mechanism. Background Art

[0002] Since the wire-controlled hydraulic brake system is an electromechanical-hydraulic servo system that combines mechanics, electronics, and fluids, the master cylinder hydraulic pressure exhibits a significant creep phenomenon and a dead zone of constant pressure due to its own friction during braking. Therefore, the system's friction characteristics seriously affect the system's response speed and accuracy, hindering the precise control of the master cylinder hydraulic pressure. Therefore, a friction characteristic test bench is needed to study the system's friction characteristics. Currently, friction characteristic test benches for wire-controlled master cylinder transmission mechanisms mostly use the entire wire-controlled mechanism (including hydraulic piping) to conduct friction characteristic research. The hydraulic piping cannot be decoupled, resulting in coupling with the hydraulic component during friction measurement. As a result, the measurement results can only quantitatively analyze the approximate range of friction, but cannot accurately measure it. At the same time, for wire-controlled systems, the input of previous friction characteristic test benches mostly uses human-depressed brake pedals connected to travel sensors and force sensors to measure their status information. The human-depressed brake pedal input is significantly different from the expected input, affecting the accuracy of the test bench output results.

[0003] To address the above issues, a friction characteristics test bench for the master cylinder transmission mechanism of a wire-controlled brake system was built, and a servo motor was used as the input source instead of the manually actuated brake pedal as input to improve the accuracy and controllability of the system input. The master cylinder and hydraulic pipeline were decoupled for testing to eliminate the influence of changes in the master cylinder hydraulic pressure. At the same time, in order to reduce the cost of the bench construction, a reasonable type of force spring was used to bear the output of the master cylinder push rod, avoiding the use of more expensive force sensors with their own deformation. For this purpose, we proposed a friction characteristics test bench for the master cylinder transmission mechanism of a wire-controlled brake and its method. Summary of the Invention

[0004] The object of the present invention is to provide a friction characteristics test bench and method for a brake-by-wire master cylinder transmission mechanism to solve the problems raised in the above-mentioned background technology.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A friction characteristics test bench for a wire-controlled brake master cylinder transmission mechanism includes a fixed bracket, an input end is provided on the fixed bracket, the input end includes a servo motor and a torque sensor, a servo motor is fixed on the top of the fixed bracket, and the output end of the servo motor is equipped with a torque sensor.

[0007] Preferably, the fixed bracket is also provided with an output end, and the output end includes a displacement sensor, a displacement sensor wire bracket, a displacement sensor bracket, a force spring, a retractable force sensor bracket and a force sensor. The displacement sensor bracket is fixed at one end of the top of the fixed bracket, the displacement sensor is fixed at the top of the displacement sensor bracket, a displacement sensor wire bracket is provided on one side of the displacement sensor, a retractable force sensor bracket is fixed on one side of the fixed bracket, a force sensor is fixed on one side of the retractable force sensor bracket, a force spring is fixed on the side of the force sensor away from the retractable force sensor bracket, and the force spring is connected to the inner side of the displacement sensor wire bracket.

[0008] Preferably, the torque sensor is equipped with a wire-controlled master cylinder transmission mechanism at one end away from the servo motor, and the displacement sensor is arranged parallel to the output end of the wire-controlled master cylinder transmission mechanism. The wire-controlled master cylinder transmission mechanism is a worm gear and a ball screw mechanism. The input end of the servo motor is connected to the worm, and the worm gear generates torque which is transmitted to the nut. The rotation of the nut pushes the threaded shaft to generate thrust which is transmitted to the master cylinder push rod of the wire-controlled master cylinder transmission mechanism. The master cylinder push rod of the wire-controlled master cylinder transmission mechanism is fixed to one end of the force spring.

[0009] Preferably, both ends of the torque sensor are connected to the input end of the brake-by-wire master cylinder transmission mechanism and the output end of the servo motor through couplings respectively.

[0010] A method for using a friction characteristic test bench for a brake-by-wire master cylinder transmission mechanism, applicable to a brake-by-wire master cylinder transmission mechanism friction characteristic test bench, comprises the following steps:

[0011] S1: Start the servo motor and measure the servo motor speed and torque information through the torque sensor. At the same time, the output end of the wire control master cylinder transmission mechanism is the master cylinder push rod, and its displacement and thrust are measured through the displacement sensor and force sensor.

[0012] S2: Data is transmitted to the host computer through the data acquisition system for data acquisition;

[0013] S3: After determining the parameters of the brake-by-wire master cylinder transmission mechanism, the friction force of the transmission mechanism is calculated according to the transmission principle of the brake-by-wire master cylinder transmission mechanism.

[0014] Preferably, the calculation principle in S is to bring the servo motor input torque into the calculation formula of the wire-controlled master cylinder transmission mechanism output torque, and calculate step by step to obtain the master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism. The difference between the master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism and the measured master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism is the system friction force under this working condition.

[0015] Preferably, the master cylinder push rod of the wire-controlled master cylinder transmission mechanism squeezes the force-bearing spring to bear deformation, and the force sensor collects the thrust change. The specific calculation process is as follows:

[0016] The worm gear output torque T1 is expressed as:

[0017] T1=T in *i

[0018] Where T in is the torque input from the motor to the worm, expressed as:

[0019]

[0020] Z2 is the number of worm gear teeth, and Z1 is the number of worm heads;

[0021] The ball screw converts the rotational torque T1 generated by the worm gear into a linear thrust F1 expressed as:

[0022]

[0023] Among them, P h is the ball screw lead, and the worm gear torque T is substituted into the linear thrust F1 to obtain:

[0024]

[0025] If the actual horizontal thrust collected by the force sensor is F2, the transmission mechanism friction force F of the wire control master cylinder transmission mechanism can be expressed as:

[0026] F=F1-F2.

[0027] Preferably, the maximum static friction force test step of the wire control master cylinder transmission mechanism is:

[0028] Step 1: Adjust the brake-by-wire master cylinder transmission mechanism to its initial position, adjust the servo motor to position mode, and adjust the torque in position mode.

[0029] Step 2: Gradually increase the input torque of the servo motor, causing the master cylinder push rod of the wire-controlled master cylinder transmission mechanism to move and then stop, and record the torque sensor values ​​at multiple different positions;

[0030] Step 3: Calculate the master cylinder push rod thrust of the brake-by-wire master cylinder transmission mechanism step by step according to the value recorded by the torque sensor using the calculation method in S. Subtract the value recorded by the force sensor to obtain the maximum static friction force of the brake-by-wire master cylinder transmission mechanism under test.

[0031] Preferably, the Coulomb friction force test steps of the wire-controlled brake master cylinder transmission mechanism are:

[0032] Step 1: Adjust the brake-by-wire master cylinder transmission mechanism to its initial position. Set the servo motor to position mode and set multiple constant speeds to evenly push the transmission mechanism.

[0033] Step 2: Calculate the master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism step by step according to the value recorded by the torque sensor at this time according to the above calculation method, and subtract it from the value recorded by the force sensor to obtain the Coulomb friction force of the wire-controlled master cylinder transmission mechanism being tested.

[0034] Preferably, the viscous friction and inertial force testing steps of the wire-controlled master cylinder transmission mechanism are:

[0035] Step 1: Adjust the brake-by-wire master cylinder transmission mechanism to its initial position. Set the servo motor to speed control in position mode, and set a faster speed and different acceleration times.

[0036] Step 2: Calculate the difference between the thrust value input to the master cylinder push rod of the wire-controlled master cylinder transmission mechanism and the value recorded by the force sensor. When the wire-controlled master cylinder transmission mechanism is rapidly actuated, the nonlinear factors affecting the friction force of the wire-controlled master cylinder transmission mechanism include Coulomb friction, viscous friction, and inertial force. The friction force generated by the rapidly actuated wire-controlled master cylinder transmission mechanism minus the obtained Coulomb friction is the sum of the viscous friction and inertial force.

[0037] It can be seen without a doubt that the above-mentioned technical solution of this application can definitely solve the technical problem to be solved by this application.

[0038] At the same time, through the above technical solutions, the present invention has at least the following beneficial effects:

[0039] 1. The main difference between the present invention and the existing friction characteristic test bench is that the present invention can realize the decoupling test of the transmission mechanism and the hydraulic pipeline, which has the advantage of eliminating hydraulic pressure interference and making the test data more accurate; the input source is replaced by servo motor input, which has the advantage of controllable input and higher input accuracy than manual brake pedal input.

[0040] 2. The present invention adopts a relatively low-cost force spring to bear the thrust of the master cylinder push rod of the wire-controlled brake master cylinder transmission mechanism, and at the same time produces deformation, thereby avoiding the use of a high-cost force sensor with a variable stroke. At the same time, improvements can be made on the basis of the present invention. When testing the friction characteristics of the system transmission mechanism, the friction characteristics of the entire friction process can be accurately tested according to the test method, and the friction force of the wire-controlled brake master cylinder transmission mechanism can be accurately measured, thereby improving the robustness of the pressure control of the wire-controlled hydraulic brake system. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 It is a structural schematic diagram of the present invention;

[0043] Figure 2 Schematic diagram of the connection structure between the fixing bracket and the servo motor of the present invention;

[0044] Figure 3 It is a top view schematic diagram of the present invention;

[0045] Figure 4 This is a topological diagram of the present invention.

[0046] In the accompanying drawings, the components represented by each symbol are listed as follows:

[0047] In the figure: 1. Fixed bracket; 2. Servo motor; 3. Torque sensor; 4. Brake-by-wire master cylinder transmission mechanism; 5. Displacement sensor; 6. Displacement sensor wire bracket; 7. Force spring; 8. Retractable force sensor bracket; 9. Force sensor; 10. Coupling; 11. Displacement sensor bracket. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] Example 1

[0050] Reference Figure 1-4 A friction characteristic test bench for a wire-controlled master cylinder transmission mechanism includes a fixed bracket 1, an input end is provided on the fixed bracket 1, the input end includes a servo motor 2 and a torque sensor 3, a servo motor 2 is fixed on the top of the fixed bracket 1, and the output end of the servo motor 2 is equipped with a torque sensor 3, the servo motor 2 is connected to a servo motor controller, and is used to provide input torque and speed signals to the wire-controlled master cylinder transmission mechanism 4; the torque sensor 3 is connected to a torque power meter, and is placed between the wire-controlled master cylinder transmission mechanism 4 and the servo motor 2, and is used to measure the input torque and speed signals of the servo motor 2; the wire-controlled master cylinder transmission mechanism 4 is expandable, and the test sample can be replaced according to its own test requirements.

[0051] An output end is also provided on the fixed bracket 1, which includes a displacement sensor 5, a displacement sensor wire bracket 6, a displacement sensor bracket 11, a force spring 7, a retractable force sensor bracket 8 and a force sensor 9. A displacement sensor bracket 11 is fixed at one end of the top of the fixed bracket 1, and a displacement sensor 5 is fixed on the top of the displacement sensor bracket 11. A displacement sensor wire bracket 6 is provided on one side of the displacement sensor 5. A retractable force sensor bracket 8 is fixed on one side of the fixed bracket 1, and a force sensor 9 is fixed on one side of the retractable force sensor bracket 8. A force spring 7 is fixed on the side of the force sensor 9 away from the retractable force sensor bracket 8. The force spring 7 is connected to the inner side of the displacement sensor wire bracket 6. The displacement sensor 5 is connected to a digital signal transmitter for testing the displacement stroke of the master cylinder push rod of the wire-controlled brake master cylinder transmission mechanism 4.

[0052] The torque sensor 3 is equipped with a wire-controlled master cylinder transmission mechanism 4 at one end away from the servo motor 2, and the displacement sensor 5 is arranged parallel to the output end of the wire-controlled master cylinder transmission mechanism 4. The wire-controlled master cylinder transmission mechanism 4 is a worm gear and a ball screw mechanism. The input end of the servo motor 2 is connected to the worm, and the worm gear generates torque and transmits it to the nut. The rotation of the nut pushes the threaded shaft to generate thrust that is transmitted to the master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4. The master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4 is fixed to one end of the force spring 7. The force spring 7 is used to withstand the output force of the master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4, and convert the displacement of the master cylinder push rod into its own deformation; the force sensor 9 is used to receive the thrust of the master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4 transmitted by the force spring 7 and measure it.

[0053] The two ends of the torque sensor 3 are respectively connected to the input end of the brake-by-wire master cylinder transmission mechanism 4 and the output end of the servo motor 2 through a coupling 10 . The coupling 10 is used for power transmission.

[0054] Example 2

[0055] like Figure 4 As shown, a method for using a friction characteristic test bench for a brake-by-wire master cylinder transmission mechanism is applicable to a friction characteristic test bench for a brake-by-wire master cylinder transmission mechanism, comprising the following steps:

[0056] S1: Start the servo motor 2 and measure the speed and torque of the servo motor 2 through the torque sensor 3. At the same time, the output end of the wire control master cylinder transmission mechanism 4 is the master cylinder push rod, and its displacement and thrust are measured by the displacement sensor 5 and the force sensor 9. The torque sensor 3, displacement sensor 5, and force sensor 9 all use the Modbus protocol to analyze the sensor signals.

[0057] S2: Data is transmitted to the host computer through the data acquisition system for data acquisition;

[0058] S3: After determining the parameters of the brake-by-wire master cylinder transmission mechanism 4 , the friction force of the transmission mechanism is calculated according to the transmission principle of the brake-by-wire master cylinder transmission mechanism 4 .

[0059] The calculation principle in S3 is to bring the input torque of the servo motor 2 into the calculation formula of the output torque of the wire-controlled master cylinder transmission mechanism 4, and calculate the master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism 4 step by step. The difference between the thrust of the master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4 and the measured thrust is the system friction force under this working condition.

[0060] The master cylinder push rod of the wire control master cylinder transmission mechanism 4 squeezes the force spring 7 to bear deformation, and the force sensor 9 collects the thrust change. The specific calculation process is as follows:

[0061] The worm gear output torque T1 is expressed as:

[0062] T1=T in *i

[0063] Where T in is the torque input from the motor to the worm, and i is the transmission ratio of the worm gear mechanism, which can be expressed as:

[0064]

[0065] Z2 is the number of worm gear teeth, and Z1 is the number of worm heads;

[0066] The ball screw converts the rotational torque T1 generated by the worm gear into a linear thrust F1 expressed as:

[0067]

[0068] Among them, P h is the ball screw lead, and the worm gear torque T1 is substituted into the linear thrust F1 to obtain:

[0069]

[0070] If the actual horizontal thrust collected by the force sensor is F2, the transmission mechanism friction force F of the wire control master cylinder transmission mechanism 4 is expressed as:

[0071] F=F1-F2

[0072] Using the above calculation formula and through analysis of the friction mechanism, it is necessary to measure the maximum static friction, Coulomb friction, viscous friction and inertia force of the wire-controlled master cylinder transmission mechanism 4. In other implementations, the wire-controlled master cylinder transmission mechanism 4 is an EHB transmission mechanism, and the torque sensor 3 is combined with other sensors to form a speed torque sensor.

[0073] Example 3

[0074] Further optimizing Example 2, the maximum static friction force test steps of the wire control master cylinder transmission mechanism 4 are as follows:

[0075] Step 1: Adjust the brake-by-wire master cylinder transmission mechanism 4 to the initial position, adjust the torque of the servo motor 2 in the position mode, input low torque, and start at different master cylinder push rod positions to measure the static friction at different master cylinder push rod positions;

[0076] Step 2: Gradually increase the input torque of the servo motor 2, so that the master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4 is displaced and then stops, and record the values ​​of the torque sensor 3 at multiple different positions;

[0077] Step 3: Calculate the master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism 4 step by step according to the calculation method in S3 based on the value recorded by the torque sensor 3, and subtract the value recorded by the force sensor 9 to obtain the maximum static friction force of the tested wire-controlled master cylinder transmission mechanism 4. When performing the above test, the displacement sensor 5 can synchronously record the master cylinder push rod displacement and speed of the wire-controlled master cylinder transmission mechanism 4, and the torque sensor 3 can synchronously record the input torque and speed of the servo motor 2. At this time, the state information can be used to describe the friction characteristics of the system.

[0078] Example 4

[0079] Further optimizing Example 2, the Coulomb friction force test steps of the wire-controlled master cylinder transmission mechanism 4 are as follows:

[0080] Step 1: Adjust the brake-by-wire master cylinder transmission mechanism 4 to its initial position. The servo motor 2 is speed-controlled in position mode. Multiple constant speeds are set to evenly propel the transmission mechanism. The brake-by-wire master cylinder transmission mechanism 4 is actuated at an extremely low speed to negligibly affect viscous friction and inertial forces.

[0081] Step 2: Calculate the master cylinder push rod thrust of the wire control master cylinder transmission mechanism 4 step by step according to the value recorded by the torque sensor 3 at this time according to the above calculation method, and subtract it from the value recorded by the force sensor 9 to obtain the Coulomb friction force of the wire control master cylinder transmission mechanism 4 under test.

[0082] Example 5

[0083] Further optimizing Example 4, the viscous friction and inertial force testing steps of the wire-controlled master cylinder transmission mechanism 4 are as follows:

[0084] Step 1: Adjust the brake-by-wire master cylinder transmission mechanism 4 to the initial position, and set the servo motor 2 to speed control in position mode, with a faster speed and different acceleration times.

[0085] Step 2: Calculate the difference between the input thrust value of the master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4 and the value recorded by the force sensor 9. When the wire-controlled master cylinder transmission mechanism 4 is rapidly actuated, the nonlinear factors affecting the friction force of the wire-controlled master cylinder transmission mechanism 4 include Coulomb friction, viscous friction and inertial force. The friction force generated by the rapid actuation of the wire-controlled master cylinder transmission mechanism 4 minus the obtained Coulomb friction is the sum of the viscous friction and inertial force. When performing the above test, the displacement sensor 5 can synchronously record the displacement and speed of the master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4, and the torque sensor 3 can synchronously record the input torque and speed of the servo motor 2. At this time, the state information can be used to describe the friction characteristics of the system.

[0086] From the above, we can know that:

[0087] The present invention addresses the following technical problems: Since a wire-controlled hydraulic brake system is an electromechanical-hydraulic servo system that combines mechanics, electronics, and fluids, the master cylinder hydraulic pressure exhibits a significant creep phenomenon and a dead zone of constant pressure due to the presence of inherent friction during braking. Therefore, the system's friction characteristics seriously affect the system's response speed and accuracy, hindering the precise control of the master cylinder hydraulic pressure. Therefore, it is necessary to construct a friction characteristics test bench to study the system's friction characteristics. Currently, most wire-controlled master cylinder transmission mechanism friction characteristics test benches use a complete wire-controlled mechanism (including hydraulic piping) to conduct friction characteristics research. The hydraulic piping cannot be decoupled, resulting in coupling with the hydraulic portion during friction measurement. Consequently, the measurement results can only quantitatively analyze the approximate range of friction, failing to accurately measure it. Furthermore, for wire-controlled systems, conventional friction characteristics test benches often use human-operated brake pedals connected to a travel sensor and a force sensor to measure their state information. However, the human-operated brake pedal input differs significantly from the expected input, affecting the accuracy of the test bench's output results. By adopting the technical solutions of the above-mentioned embodiments and the above-mentioned configuration, the present application can certainly solve the above-mentioned technical problems and achieve the following technical effects:

[0088] 1. The main difference between the present invention and the existing friction characteristic test bench is that the present invention can realize the decoupling test of the transmission mechanism and the hydraulic pipeline, which has the advantage of eliminating hydraulic pressure interference and making the test data more accurate; the input source is replaced by the input of the servo motor 2, which has the advantage of controllable input and higher input accuracy than the input by manually stepping on the brake pedal.

[0089] 2. The present invention adopts a relatively low-cost force spring 7 to withstand the thrust of the master cylinder push rod of the wire-controlled master cylinder transmission mechanism 4, and at the same time produces deformation, thereby avoiding the use of a relatively high-cost force sensor 9 with its own variable stroke; at the same time, based on the present invention, improvements can be made. When testing the friction characteristics of the system transmission mechanism, the friction characteristics of the entire friction process can be accurately tested according to the test method, and the friction force of the wire-controlled master cylinder transmission mechanism 4 can be accurately measured, thereby improving the robustness of the pressure control of the wire-controlled hydraulic brake system.

[0090] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0091] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are given in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned specific embodiments, or to make equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the present invention specification and drawings, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. A friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism, characterized in that: The invention comprises a fixed bracket (1), wherein an input end is provided on the fixed bracket (1), wherein the input end comprises a servo motor (2) and a torque sensor (3), wherein the servo motor (2) is fixed on the top of the fixed bracket (1), and the output end of the servo motor (2) is equipped with a torque sensor (3).

2. The friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism according to claim 1, characterized in that: The fixed bracket (1) is also provided with an output end, and the output end includes a displacement sensor (5), a displacement sensor wire bracket (6), a displacement sensor bracket (11), a force spring (7), a retractable force sensor bracket (8) and a force sensor (9). One end of the top of the fixed bracket (1) is fixed with a displacement sensor bracket (11), the top of the displacement sensor bracket (11) is fixed with a displacement sensor (5), one side of the displacement sensor (5) is provided with a displacement sensor wire bracket (6), one side of the fixed bracket (1) is fixed with a retractable force sensor bracket (8), one side of the retractable force sensor bracket (8) is fixed with a force sensor (9), and the side of the force sensor (9) away from the retractable force sensor bracket (8) is fixed with a force spring (7), and the force spring (7) is connected to the inner side of the displacement sensor wire bracket (6).

3. The friction characteristics test bench for the brake-by-wire master cylinder transmission mechanism according to claim 2, characterized in that: The torque sensor (3) is equipped with a wire-controlled master cylinder transmission mechanism (4) at one end away from the servo motor (2). The displacement sensor (5) is arranged in parallel with the output end of the wire-controlled master cylinder transmission mechanism (4). The wire-controlled master cylinder transmission mechanism (4) is a worm gear and a ball screw mechanism. The input end of the servo motor (2) is connected to the worm gear. The worm gear generates torque and transmits it to the nut. The nut rotates to push the threaded shaft to generate thrust and transmit it to the master cylinder push rod of the wire-controlled master cylinder transmission mechanism (4). The master cylinder push rod of the wire-controlled master cylinder transmission mechanism (4) is fixed to one end of a force spring (7).

4. The friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism according to claim 3, characterized in that: The two ends of the torque sensor (3) are respectively connected to the input end of the wire-controlled brake master cylinder transmission mechanism (4) and the output end of the servo motor (2) through a coupling (10).

5. A method for using a friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism, applicable to a friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Start the servo motor (2), measure the speed and torque information of the servo motor (2) through the torque sensor (3), and at the same time, the output end of the wire-controlled master cylinder transmission mechanism (4) is the master cylinder push rod, and its displacement and thrust are measured through the displacement sensor (5) and the force sensor (9); S2: Data is transmitted to the host computer through the data acquisition system for data acquisition; S3: After determining the parameters of the wire-controlled master cylinder transmission mechanism (4), the friction force of the transmission mechanism is calculated according to the transmission principle of the wire-controlled master cylinder transmission mechanism (4).

6. The method for using the friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism according to claim 5, characterized in that: The calculation principle in S3 is to bring the input torque of the servo motor (2) into the calculation formula of the output torque of the wire-controlled master cylinder transmission mechanism (4), and calculate the master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism (4) step by step. The difference between the master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism (4) and the measured master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism (4) is the system friction force under this working condition.

7. The method for using the friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism according to claim 6, characterized in that: The master cylinder push rod of the wire-controlled master cylinder transmission mechanism (4) squeezes the force-bearing spring (7) to undergo deformation, and the force sensor (9) collects the thrust change. The specific calculation process is as follows: The worm gear output torque T1 is expressed as: T1=T in *i Where T in is the torque input from the motor to the worm, and i is the transmission ratio of the worm gear mechanism, which can be expressed as: Z2 is the number of worm gear teeth, and Z1 is the number of worm heads; The ball screw converts the rotational torque T1 generated by the worm gear into a linear thrust F1 expressed as: Among them, P h is the ball screw lead, and the worm gear torque T1 is substituted into the linear thrust F1 to obtain: If the actual horizontal thrust collected by the force sensor is F2, the transmission mechanism friction force F of the wire control master cylinder transmission mechanism (4) is expressed as: F=F1-F2.

8. The method for using the friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism according to claim 7, characterized in that: The maximum static friction force test steps of the wire-controlled brake master cylinder transmission mechanism (4) are as follows: Step 1: Adjust the brake-by-wire master cylinder transmission mechanism (4) to the initial position, and adjust the torque of the servo motor (2) in the position mode; Step 2: gradually increase the input torque of the servo motor (2), and the master cylinder push rod of the wire-controlled master cylinder transmission mechanism (4) is displaced and then stopped, and the values ​​of the torque sensor (3) at multiple different positions are recorded; Step 3: Calculate the master cylinder push rod thrust of the wire control master cylinder transmission mechanism (4) step by step according to the value recorded by the torque sensor (3) according to the calculation method in S3, and subtract the value recorded by the force sensor (9) to obtain the maximum static friction force of the wire control master cylinder transmission mechanism (4) under test.

9. The method for using the friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism according to claim 8, characterized in that: The Coulomb friction force test steps of the wire-controlled brake master cylinder transmission mechanism (4) are as follows: Step 1: Adjust the brake-by-wire master cylinder transmission mechanism (4) to the initial position, and control the speed of the servo motor (2) in the position mode, setting multiple sets of constant speeds to evenly push the transmission mechanism; Step 2: Calculate the master cylinder push rod thrust of the wire-controlled master cylinder transmission mechanism (4) step by step according to the value recorded by the torque sensor (3) at this time according to the above calculation method, and subtract the value recorded by the force sensor (9) to obtain the Coulomb friction force of the wire-controlled master cylinder transmission mechanism (4) under test.

10. The method for using the friction characteristics test bench for a brake-by-wire master cylinder transmission mechanism according to claim 9, characterized in that: The viscous friction and inertia force testing steps of the wire-controlled brake master cylinder transmission mechanism (4) are as follows: Step 1: Adjust the wire-controlled brake master cylinder transmission mechanism (4) to the initial position, and the servo motor (2) is speed-controlled in the position mode, setting a faster speed and different acceleration times; Step 2: Calculate the difference between the input thrust value of the master cylinder push rod of the wire control master cylinder transmission mechanism (4) and the value recorded by the force sensor (9). When the wire control master cylinder transmission mechanism (4) is rapidly actuated, the nonlinear factors affecting the friction force of the wire control master cylinder transmission mechanism (4) include Coulomb friction, viscous friction and inertial force. The friction force generated by the rapidly actuated wire control master cylinder transmission mechanism (4) minus the obtained Coulomb friction is the sum of the viscous friction and the inertial force.

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