A shift fork wear test bench and test method
By using a shift fork wear test bench and a roughened mating ring groove, the problem of decoupling shift fork wear in existing devices was solved, achieving efficient and accurate wear testing, shortening the test cycle and ensuring the reliability of the results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG UNIV
- Filing Date
- 2026-06-15
- Publication Date
- 2026-07-14
Smart Images
Figure CN122385188A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of testing system technology, specifically to a shift fork wear test bench and test method. Background Technology
[0002] In manual / automated manual transmissions (AMT), the shift fork feet (especially the fork foot plastic blocks) mainly experience two types of wear during operation: first, during gear engagement, the shift fork pushes the engagement sleeve / sliding sleeve to move, causing axial pressure and relative sliding wear between the fork foot plastic blocks and the annular groove sidewall; second, during non-shift holding, the engagement sleeve rotates, causing continuous relative sliding friction wear between the fork foot plastic blocks and the annular groove sidewall. These two types of wear determine the lifespan of the plastic blocks, clearance growth, and shift reliability, but for a long time, there has been a lack of dedicated testing methods to separately induce, measure, and compare these two types of wear.
[0003] Existing shift fork testing devices mostly target strength / stiffness or fatigue, applying vertical pressure to the shift fork feet using a press and evaluating strength by acquiring force-deformation curves through sensors. This is a quasi-static loading method and cannot reflect the actual wear mechanism and wear evolution of the shift fork. Other schemes introduce rotating components and loading mechanisms to simulate shift fork foot sliding wear, using an annular groove on the periphery of a friction disc as a mating element to drive the friction disc to rotate and apply a loading force for wear testing. However, these schemes have shortcomings: the wear mating is simplified, making it difficult to reproduce the actual geometry and contact conditions; the test mode is biased towards continuous sliding wear, lacking reproduction of shift cycle axial drive, and it is difficult to decouple shift engagement wear from holding sliding wear. Furthermore, even if existing testing devices can simulate shift wear, the high manufacturing precision and good fit of the shift fork and sleeve result in extremely small wear during a single shift engagement and disengagement process, requiring a large number of cycles for the shift fork durability wear test, thus leading to a long test cycle. Summary of the Invention
[0004] To address the problems existing in the prior art, this invention provides a shift fork wear test bench and test method, which can realize two types of wear tests: shift fork non-shift holding rotational friction and shift engagement cyclic wear. It adopts a calibrable accelerated wear method that only roughens the paired ring groove, which can solve the problems of existing tests being unable to decouple the two types of wear and having a long wear test cycle.
[0005] The technical solution of the present invention is as follows: In a first aspect of the present invention, a shift fork wear test bench is provided, comprising an output shaft simulation mechanism, a shift fork horizontal drive mechanism, and a measuring mechanism mounted on a test bench frame; The output shaft simulation mechanism includes a servo motor, and a shift sleeve, a synchronizer and a shift gear are sequentially installed on the output shaft of the servo motor. Different output shaft speed conditions are simulated by adjusting the speed of the servo motor. The shift fork horizontal drive mechanism includes a stepper screw linear motor. The output end of the stepper screw linear motor is connected to the fork head of the shift fork. The pin of the shift fork is inserted into the annular groove of the shift sleeve. The shift fork is driven to move horizontally by the stepper screw linear motor to simulate the horizontal driving force applied to the shift fork by the actual shift actuator. The measuring mechanism includes a displacement sensor and a pressure sensor. The displacement sensor measures the horizontal displacement of the shift fork, and the pressure sensor measures the axial force generated when the shift fork pushes the shift sleeve and shift gear.
[0006] In some embodiments of the present invention, the pressure sensor is installed between a first baffle and a second baffle, both of which are slidably sleeved on the output shaft of a servo motor, and a support spring is installed between the second baffle and the test bench frame.
[0007] In some embodiments of the present invention, the first baffle is mounted on the output shaft of the servo motor via a thrust ball bearing, and an annular groove is formed on the opposing surfaces of the first baffle and the second baffle, and the pressure sensor is mounted in the annular groove.
[0008] In some embodiments of the present invention, the first baffle is located behind the shift gear, which is mounted on the output shaft of the servo motor via a thrust ball bearing.
[0009] In some embodiments of the present invention, the output shaft of the servo motor is mounted on the test bench via a limit bearing.
[0010] In some embodiments of the present invention, the wall surface of the annular groove of the shift sleeve that contacts the shift fork pin is roughened, and the surface roughness is quantified.
[0011] In a second aspect of the present invention, a method for testing the wear of a shift fork is provided, which is implemented using the shift fork wear test bench described in the first aspect, and includes the following two switchable wear test modes: In the wear mode, the spatial position of the shift fork is locked relative to the test bench frame, and the output shaft of the servo motor rotates at a set speed, so that the plastic block of the shift fork foot and the mating contact surface generate continuous relative sliding friction. The wear of the plastic block is sampled and measured at time intervals or revolution intervals to obtain wear data under the holding condition. In the shifting and wear mode, the output shaft of the servo motor rotates at a set speed, while the linear motor via the stepper screw pushes the upper part of the shift fork to move the shift block according to the set stroke, speed and frequency. This causes the shift fork to drive the shift sleeve to complete the shifting cycle of sequential engagement, meshing and reset along the output shaft axis. The number of shifting cycles is accumulated, and the wear of the plastic block is sampled and measured at intervals to establish the relationship between the number of shifts and the amount of wear under shifting conditions.
[0012] In some embodiments of the present invention, an accelerated wear calibration step is also included: Step 1: With the mating contact surfaces in a standard, unroughened state, conduct at least three sets of repeated wear tests on the same batch of shift forks made of the same material, and record the number of shift cycles at intervals. Corresponding wear amount of plastic block The standard wear curve was obtained by fitting the data. Step 2: Modify only the surface condition of the mating contact surface, increasing its roughness, while maintaining the same shifting conditions as in Step 1 for the shift fork material and structure. Conduct at least three sets of accelerated wear tests, recording the number of accelerated shifting cycles at intervals. Corresponding wear amount The accelerated wear curve was obtained; Step 3: Using the same amount of wear as a benchmark, compare the accelerated wear curve with the standard wear curve to establish the number of accelerated shifts after roughening treatment. Compared to standard shift times The equivalent mapping relationship is used to quantify the acceleration ratio of the wear range corresponding to different shift cycles. When evaluating the wear of shift forks of the same material and structure, accelerated wear tests are conducted using the calibrated roughened dual contact surfaces. The shift cycle and wear curve under standard operating conditions are calculated based on the equivalent mapping relationship.
[0013] In some embodiments of the present invention, when changing the surface state of the mating contact surface, roughening treatment or installation of a replaceable roughened friction ring groove sleeve is performed, and the surface roughness is quantified.
[0014] In some embodiments of the present invention, when roughening the surface condition of the mating contact surface, one of the following methods is used: sandblasting, laser microtexturing, electrical discharge machining, shot peening, knurling, or abrasive grinding.
[0015] One or more technical solutions of the present invention have the following beneficial effects: (1) The shift fork wear test bench of the present invention does not completely reproduce the entire transmission, but focuses on the core components directly related to the wear of the shift fork foot plastic block, selectively retaining key components such as the output shaft, shift fork sleeve, synchronizer, shift gear, and shift fork. On this basis, by fully referencing the force transmission path and load characteristics acting on the shift fork in the actual vehicle shift mechanism, a drive system capable of accurately simulating the axial driving force on the shift fork during the actual shift process is constructed. This structure effectively restores the key mechanical and kinematic conditions affecting wear under actual working conditions, and significantly reduces the complexity and cost of the test equipment, thereby improving test efficiency and operability while ensuring the authenticity of the test results.
[0016] (2) This invention organically couples a servo rotary drive system with a linear shift drive system. This structure has multi-degree-of-freedom collaborative control capabilities, enabling simultaneous, independent, and precise control of the output shaft's rotational speed, the shift fork's horizontal displacement stroke, the frequency of shifting actions, and the magnitude of the horizontal driving force applied to the shift fork. Furthermore, this experimental structure integrates high-precision sensors, which can perform real-time, continuous, and quantitative measurements of the axial driving force and corresponding axial displacement experienced by the shift fork during shifting, providing reliable data support for subsequent wear mechanism analysis and life prediction.
[0017] (3) This invention proposes an accelerated wear test method for shift forks based on roughened dual ring groove components. Without altering the structure, material, or surface condition of the shift fork under test, the contact surface of the sleeve ring groove that works with the shift fork is artificially roughened to increase the friction coefficient and local stress concentration at the contact interface, thereby significantly increasing the wear rate while keeping other operating parameters constant. This method effectively shortens the test cycle and ensures that the wear mode is highly consistent with the failure mode in actual use, exhibiting good engineering applicability and repeatability.
[0018] (4) This invention proposes a mathematical modeling method for equivalent mapping between standard wear curves and accelerated wear curves. This method uses the same cumulative wear amount as a benchmark point, and establishes a quantitative mapping relationship between the number of gear shifts required to reach the same wear level under standard and accelerated operating conditions by comparing and analyzing these shifts. Furthermore, it calculates the corresponding acceleration ratio for different wear stages, thereby scientifically and reasonably extrapolating and converting the wear data obtained from short-cycle, high-intensity accelerated tests into wear evolution patterns during long-term service under standard operating conditions, providing theoretical basis and technical support for product life assessment and reliability verification. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the components on the fork wear test bench of the present invention; Figure 2 This is a schematic diagram showing the relative positions of the components mounted on the output shaft of the present invention. Figure 3 This is a front view of the shift fork to be tested; Figure 4 This is a side view of the shift fork to be tested.
[0020] In the diagram: 1. Spline; 2. First limit bearing; 3. Shift sleeve; 4. Synchronizer; 5. Shift gear; 6. Thrust ball bearing; 7. First baffle; 8. Pressure sensor; 9. Second baffle; 10. Support spring; 11. Second limit bearing; 12. Test bench frame; 13. Servo motor; 14. Stepper screw linear motor; 15. Shift fork; 1501. Fork head; 1502. Fork foot; 16. First displacement sensor; 17. Second displacement sensor. Detailed Implementation
[0021] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is intended to include the plural form as well. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0023] Example 1 In a typical embodiment of the present invention, a shift fork wear test bench is provided, such as... Figure 1 and Figure 2 As shown, the test bench 12 includes an output shaft simulation mechanism, a shift fork horizontal drive mechanism, and a measuring mechanism. The test bench 12 is equipped with a base and support mechanism to support the shift fork horizontal drive mechanism and the measuring mechanism, according to test requirements. The output shaft simulation mechanism effectively simulates the different speed conditions experienced by the transmission output shaft during actual vehicle operation, thus providing dynamic test conditions for the shift fork 15 that closely resemble the real-world operating environment. The shift fork horizontal drive mechanism precisely drives the shift fork 15 to reciprocate horizontally, thereby simulating the horizontal driving force applied to the shift fork 15 by the actual vehicle's shift actuator (such as a shift lever or hydraulic / electric actuator), achieving a high-fidelity reproduction of the shifting process. The measuring mechanism measures displacement, pressure, and other data during the test, providing crucial data support for wear mechanism analysis and life assessment.
[0024] Specifically, the output shaft simulation mechanism includes a servo motor 13. A shift sleeve 3, a synchronizer 4, and a shift gear 5 are sequentially mounted on the output shaft of the servo motor 13. The servo motor 13 is connected to the output shaft via a spline 1 or a coupling. The shift sleeve 3, acting as the object pushed by the shift fork 15, engages with the shift fork foot 1502 through its annular groove to transmit axial force, while simultaneously generating relative friction with the shift fork 15 during rotation. The synchronizer 4 coordinates the speed difference between the shift gear 5 and the engagement sleeve to ensure smooth engagement. The shift gear 5, as the final target of engagement, transmits power after engaging with the engagement sleeve. Different output shaft speed conditions are simulated by adjusting the speed of the servo motor 13.
[0025] The horizontal drive mechanism for the shift fork includes a stepper screw linear motor 14. The stepper screw linear motor 14 serves as the drive element and can be either a stepper screw linear motor or a servo linear module. The output end of the stepper screw linear motor 14 is connected to the fork head 1501 of the shift fork 15, pushing the shift block on the fork head 1501 to move the shift fork 15 horizontally along the output shaft axis, simulating the horizontal driving force applied to the shift fork 15 by the actual shifting actuator. The pins of the shift fork 15 are inserted into the annular groove of the shift sleeve 3. The horizontal movement of the shift fork 15 drives the shift sleeve 3 to move axially, thereby transmitting axial force to achieve shifting. The structure of the shift fork 15 is as follows: Figure 3 and Figure 4 As shown, the upper end of the shift fork 15 has a groove machined into the actuating block, and the front end of the stepper linear motor 14 has a round end or ball end structure, with the round end embedded in the groove of the actuating block. This structure can transmit horizontal thrust while allowing slight attitude deviations, reducing the impact of assembly errors on the movement of the shift fork 15.
[0026] The measuring mechanism includes a displacement sensor and a pressure sensor 8. The displacement sensor measures the horizontal displacement of the shift fork 15, and the pressure sensor 8 measures the axial force generated when the shift fork 15 pushes the shift sleeve 3 and the shift gear 5. Specifically, two displacement sensors can be provided, including a first displacement sensor 16 and a second displacement sensor 17. The first displacement sensor 16 is used to measure the distance between the shift block of the shift fork 15 and the side wall of the test bench or a fixed reference surface in real time, thereby quantifying the horizontal displacement of the shift fork 15 and determining the position and shift stroke of the shift fork 15. The second displacement sensor 17 is used to measure the axial displacement of the shift sleeve 3 relative to the fixed reference of the test bench in real time, thereby verifying the transmission consistency between the displacement of the shift fork 15 and the displacement of the shift sleeve 3, and avoiding deviations in test data caused by relying solely on the displacement data of the shift fork 15 when slippage or lateral movement occurs between the shift fork 15 and the shift sleeve 3.
[0027] The pressure sensor 8 is used to measure the axial force generated when the shift fork 15 pushes the engagement sleeve and shift gear 5 assembly, while limiting the axial movement of the output shaft. Specifically, the pressure sensor 8 is installed between the first baffle 7 and the second baffle 9, both of which are slidably sleeved on the output shaft of the servo motor 13. A support spring 10 is installed between the second baffle 9 and the test bench frame 12. The first baffle 7 transmits the axial load to the pressure sensor 8, while the second baffle 9 supports the pressure sensor 8 and transmits the elastic force of the support spring 10 to the pressure sensor 8. The support spring 10 provides preload to limit the axial movement of the output shaft and absorbs some impact load, ensuring the stability of the axial load measured by the pressure sensor 8 and avoiding measurement accuracy issues caused by excessive axial movement of the output shaft. Furthermore, a small tension / compression sensor can be added between the front end of the stepper linear motor 14's lead screw and the shift block to directly measure the horizontal driving force applied to the shift fork 15 by the actuator, forming a cross-validation with the pressure sensor 8 on the right end.
[0028] Furthermore, an annular groove is formed on the opposing surfaces of the first baffle 7 and the second baffle 9, and the pressure sensor 8 is installed in the annular groove. The first baffle 7 is mounted on the output shaft of the servo motor 13 via a thrust ball bearing 6. Due to the presence of the thrust bearing, the first baffle 7 will not rotate with the shift gear 5, thereby protecting the pressure sensor 8 from rotation.
[0029] like Figure 2 As shown, the first baffle 7 is located behind the shift gear 5 (i.e., on the side away from the servo motor 13 body). The shift gear 5 is mounted on the output shaft of the servo motor 13 via a thrust ball bearing 6. It should be noted that the shift gear 5 and the first baffle 7 are mounted on the output shaft via the same thrust bearing. The shift gear 5 has a groove that embeds into the left shaft ring of the thrust bearing. The first baffle 7 has a groove that embeds into the right shaft ring of the thrust bearing. Rollers are positioned between the left and right shaft rings. There is a gap between the inner ring of the right shaft ring and the wall of the output shaft. Therefore, the left... The right shaft ring, embedded in the groove of the shift gear 5, rotates synchronously with the output shaft. The left shaft ring, embedded in the groove of the first baffle 7, remains stationary. The axial load is transmitted between the left and right shaft rings through rollers. When the output shaft rotates at high speed, the thrust bearing pushes the shift fork 15 to push the axial force generated by the shift gear 5 assembly. This force is stably transmitted to the first baffle 7 and the pressure sensor 8 through the left shaft ring, rollers, and right shaft ring. At the same time, the rotational motion of the shift gear 5 is completely isolated, preventing the first baffle 7 and the pressure sensor 8 from rotating with the shaft. This ensures the accuracy of axial force measurement and structural stability, and also helps to limit the axial movement of the output shaft.
[0030] In this embodiment, the output shaft of the servo motor 13 is mounted on the test bench 12 via limit bearings. Specifically, it includes two limit bearings: a first limit bearing 2 and a second limit bearing 11. The first limit bearing 2 is located at the front end of the output shaft and mounted on the test bench 12, while the second limit bearing 11 is located at the rear end of the output shaft and mounted on the test bench 12. The two limit bearings jointly provide radial support for the output shaft, limiting its radial runout and maintaining the rotational accuracy and rigidity of the shaft system. At the same time, the two limit bearings, together with the thrust bearing and support spring 10 at the right end of the output shaft, jointly constrain the axial degree of freedom of the output shaft from both ends, helping to limit the axial movement of the output shaft and ensuring the stable transmission and measurement of axial load during gear shifting.
[0031] The shift fork wear test bench in this embodiment also includes a lubrication adjustment mechanism and a control and data acquisition system. The lubrication adjustment mechanism adjusts the lubricant type, quantity, temperature, and supply method in the contact area of the shift fork foot 1502 to make the test conditions as close as possible to the actual gearbox lubrication environment. The control and data acquisition system includes a host computer that controls the servo motor 13 and the stepper screw linear motor 14 to synchronously collect data such as output shaft speed, shift count, shift fork 15 displacement, horizontal driving force, temperature, and wear. Since the lubrication adjustment mechanism and control and data acquisition system used are existing technologies, their structure and working principle will not be described in detail.
[0032] Due to the high machining precision and good fit between the shift fork 15 and the shift sleeve 3, the wear during a single gear engagement and disengagement process is minimal. Even with increased shift frequency, a large number of cycles may still be required. To shorten the durability wear test cycle of the shift fork 15, this invention proposes to roughen the wall surface of the annular groove of the shift sleeve 3 where it contacts the shift fork pin (since the shift fork 15 is the part to be tested and should not be modified or treated), and to quantify the surface roughness to simulate the non-ideal smooth contact surface caused by long-term use or manufacturing tolerances in actual gearboxes. This more realistically reflects the wear behavior of the shift fork 15 under complex working conditions. When quantifying the surface roughness, the treated surface roughness can be quantitatively characterized (e.g., Ra value) according to international standards (such as ISO or GB).
[0033] The shift fork wear test bench provided in this embodiment can perform the following two types of wear tests: (1) Non-shift holding wear test The shift fork 15 remains stationary in the set position, while the shift sleeve 3 rotates with the output shaft. The output shaft speed is set by the servo motor 13, causing continuous relative sliding friction between the plastic block of the shift fork foot 1502 and the annular groove sidewall of the shift sleeve 3. During the test, the rotational speed, running time, lubrication conditions, and temperature are recorded, and the wear of the plastic block of the fork foot 1502 is measured after fixed time intervals or fixed rotational intervals.
[0034] This method is used to evaluate the wear resistance of the shift fork 15 when it is held in a non-shifting state for a long period of time.
[0035] (2) Wear test during gear shifting engagement Servo motor 13 drives the output shaft to rotate, and stepper screw linear motor 14 pushes the shift fork block according to the set stroke, speed and frequency, so that shift fork 15 drives shift sleeve 3 to move towards shift gear 5. Synchronizer 4 participates in the engagement process, so that the rotational speed between shift gear 5 and engagement sleeve gradually approaches until the shift engagement state is reached.
[0036] One engagement and reset process can be counted as one shift cycle. By setting different speeds, shift thrusts, shift speeds, and lubrication conditions, the wear of the 1502 plastic block of the shift fork foot in actual shifting action was tested, and the relationship between the number of shifts and the amount of wear was established.
[0037] The shift fork wear test bench provided in this embodiment simulates the two types of wear conditions mentioned above in a controllable manner, measures the wear amount of the shift fork foot 1502 plastic block, establishes the relationship between the number of shifts, rotational speed, horizontal driving force, lubrication conditions, contact surface condition and wear amount, thereby evaluating the wear resistance and anti-wear capability of the shift fork foot 1502 plastic block, and verifying whether it meets the design requirements. The test bench does not need to completely reproduce the entire gearbox, but only needs to retain the key structures and stress-bearing parts directly related to the wear of the shift fork 15. The gearbox output shaft structure can be simplified, retaining core components such as the output shaft, engagement sleeve or shift sleeve 3, synchronizer 4, shift gear 5, and shift fork 15. The above components can be original gearbox parts, or equivalent test pieces can be machined according to the original design parameters.
[0038] Example 2 In a typical embodiment of this invention, a method for testing the wear of a shift fork is provided, which is implemented using the shift fork wear test bench of Embodiment 1. This method supports two flexibly switchable wear test modes: the first is a "hold wear mode," in which the spatial position of the shift fork is mechanically locked relative to the test bench frame to prevent horizontal displacement. Then, a servo motor is started, causing its output shaft to rotate continuously at a preset constant speed, thereby creating continuous relative sliding friction between the plastic block at the lower end of the shift fork and the mating contact surface of the annular groove of the shift sleeve. During this process, samples are periodically taken and measured according to a set time interval or the number of rotations of the servo motor. The wear of the plastic block is measured to obtain wear evolution data under static holding conditions. The second type is the "shifting engagement wear mode". In this mode, the servo motor also rotates at a set speed, and the control system synchronously drives the stepper screw linear motor. According to the preset stroke, movement speed and action frequency, it periodically pushes the shift block at the upper end of the shift fork, so that the shift fork drives the shift sleeve to complete the complete shifting cycle of engagement, full engagement and reset along the axial direction of the servo motor output shaft. The system automatically accumulates the number of shifting cycles completed and samples and measures the wear of the plastic block at the set cycle interval, thereby establishing a quantitative relationship curve between the number of shifts and the cumulative wear under dynamic shifting conditions.
[0039] Furthermore, to shorten the testing cycle, an accelerated wear method based on a roughened contact surface is proposed, which can calibrate accelerated wear, specifically including: Step 1: With the mating contact surface (i.e., the inner wall of the annular groove of the shift sleeve) in a standard smooth surface condition without roughening treatment, select shift fork samples from the same batch, with the same material and structure, and conduct no less than three sets of parallel repeated wear tests; in each set of tests, record the cumulative shift cycles at fixed intervals. Number of times and corresponding wear of plastic blocks Subsequently, statistical analysis and fitting were performed on multiple sets of data to obtain a representative standard wear curve; Step 2: While maintaining the shift fork material, geometry, and shifting parameters (such as lubricant type, test temperature, output shaft speed, shifting thrust, shifting stroke, and shifting frequency) completely identically, only change the surface condition of the mating contact surface, i.e., use a high-roughness surface that has undergone quantitative roughening treatment, and conduct no less than three sets of accelerated wear tests again, simultaneously recording the number of shifting cycles under accelerated conditions. Corresponding wear amount This allows us to obtain an accelerated wear curve. Step 3: Using the same amount of wear as a benchmark, compare and analyze the accelerated wear curve with the standard wear curve to establish the number of accelerated shifts after roughening treatment. Number of gear shifts under standard operating conditions The equivalent mapping relationship between them is established, and the acceleration ratio corresponding to different wear ranges is further quantified (i.e., the ratio of the number of standard cycles required to complete the same wear to the number of accelerated cycles). Subsequently, when evaluating the conventional wear performance of a new batch of shift forks of the same material and structure, a smaller number of accelerated wear tests can be carried out using the calibrated roughened dual contact surface. Based on the aforementioned equivalent mapping relationship, the measured accelerated wear data can be converted into a curve showing the relationship between the number of shifts and the amount of wear under standard operating conditions.
[0040] The surface condition of the mating contact surface can be altered through roughening treatment or by installing a replaceable roughened friction ring groove. Surface roughness can be quantified, and various surface roughness settings can be configured for testing. Specific values can be adjusted based on the actual material, lubricant, and wear rate. When roughening the surface condition of the mating contact surface, one of the following methods can be used: sandblasting, laser microtexturing, electrical discharge machining, shot peening, knurling, or abrasive grinding.
[0041] This testing method can predict the long-term wear trend of shift forks under standard contact surface conditions within a shorter testing cycle, thereby improving the efficiency of shift fork wear resistance evaluation, significantly shortening the test cycle, improving R&D efficiency, and ensuring the engineering applicability and comparability of the evaluation results.
[0042] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.
Claims
1. A test bench for wear of a shift fork, characterized in that, This includes an output shaft simulation mechanism, a shift fork horizontal drive mechanism, and a measuring mechanism, all mounted on a test bench. The output shaft simulation mechanism includes a servo motor, and a shift sleeve, a synchronizer and a shift gear are sequentially installed on the output shaft of the servo motor. Different output shaft speed conditions are simulated by adjusting the speed of the servo motor. The shift fork horizontal drive mechanism includes a stepper screw linear motor. The output end of the stepper screw linear motor is connected to the fork head of the shift fork. The pin of the shift fork is inserted into the annular groove of the shift sleeve. The shift fork is driven to move horizontally by the stepper screw linear motor to simulate the horizontal driving force applied to the shift fork by the actual shift actuator. The measuring mechanism includes a displacement sensor and a pressure sensor. The displacement sensor measures the horizontal displacement of the shift fork, and the pressure sensor measures the axial force generated when the shift fork pushes the shift sleeve and shift gear.
2. The shift fork wear test bench as described in claim 1, characterized in that, The pressure sensor is installed between the first baffle and the second baffle. Both the first baffle and the second baffle are slidably sleeved on the output shaft of the servo motor. A support spring is installed between the second baffle and the test bench frame.
3. The shift fork wear test bench as described in claim 2, characterized in that, The first baffle is mounted on the output shaft of the servo motor via a thrust ball bearing. An annular groove is formed on the opposing surfaces of the first and second baffles, and the pressure sensor is installed in the annular groove.
4. The shift fork wear test bench as described in claim 2, characterized in that, The first baffle is located behind the shift gear, which is mounted on the output shaft of the servo motor via a thrust ball bearing.
5. The shift fork wear test bench as described in claim 1, characterized in that, The output shaft of the servo motor is mounted on the test bench via a limit bearing.
6. The shift fork wear test bench as described in claim 1, characterized in that, The annular groove of the shift sleeve is roughened on the wall surface where it contacts the shift fork pin, and the surface roughness is quantified.
7. A method for testing the wear of a shift fork, implemented using the shift fork wear test bench as described in any one of claims 1-6, characterized in that, Includes the following two switchable wear test modes: In the wear mode, the spatial position of the shift fork is locked relative to the test bench frame, and the output shaft of the servo motor rotates at a set speed, so that the plastic block of the shift fork foot and the mating contact surface generate continuous relative sliding friction. The wear of the plastic block is sampled and measured at time intervals or revolution intervals to obtain wear data under the holding condition. In the gear shifting and wear mode, the output shaft of the servo motor rotates at a set speed, while the linear motor via the stepper screw pushes the upper part of the shift fork to move the shift block according to the set stroke, speed and frequency. This causes the shift fork to drive the shift sleeve to complete the shifting cycle of sequential engagement, meshing and reset along the output shaft axis. The number of shifting cycles is accumulated, and the wear of the plastic block is sampled and measured at intervals to establish the relationship between the number of shifts and the amount of wear under the shifting condition.
8. The method for testing the wear of the shift fork as described in claim 7, characterized in that, It also includes an accelerated wear calibration step: Step 1: With the mating contact surfaces in a standard, unroughened state, conduct at least three sets of repeated wear tests on the same batch of shift forks made of the same material, and record the number of shift cycles at intervals. Corresponding wear amount of plastic block The standard wear curve was obtained by fitting the data. Step 2: Modify only the surface condition of the mating contact surface, increasing its roughness, while maintaining the same shifting conditions as in Step 1 for the shift fork material and structure. Conduct at least three sets of accelerated wear tests, recording the number of accelerated shifting cycles at intervals. Corresponding wear amount The accelerated wear curve was obtained; Step 3: Using the same amount of wear as a benchmark, compare the accelerated wear curve with the standard wear curve to establish the number of accelerated shifts after roughening treatment. Compared to standard shift times The equivalent mapping relationship is used to quantify the acceleration ratio of the wear range corresponding to different shift cycles. When evaluating the wear of shift forks of the same material and structure, accelerated wear tests are conducted using the calibrated roughened dual contact surfaces. The shift cycle and wear curve under standard operating conditions are calculated based on the equivalent mapping relationship.
9. The method for testing the wear of the shift fork as described in claim 8, characterized in that, When changing the surface condition of the mating contact surface, roughening treatment or installation of a replaceable roughened friction ring groove sleeve can be used, and the surface roughness can be quantified.
10. The method for testing the wear of the shift fork as described in claim 9, characterized in that, When roughening the surface condition of the mating contact surface, one of the following methods can be used: sandblasting, laser microtexturing, electrical discharge machining, shot peening, knurling, or abrasive grinding.