Fatigue test device for automobile axle production

Abstract

The invention relates to the technical field of axles, and discloses a fatigue test device for automobile axle production, and the device comprises a test bench pedestal which is fixedly provided with an axle clamping mechanism, and the axle clamping mechanism is used for fixing a tested axle; the bevel gear differential mechanism comprises a differential mechanism shell, a planetary gear carrier, two half shaft bevel gears, two planetary bevel gears, a large gear, a small gear and a main driving motor. Each of the two load generation systems comprises a cam shaft, a variable lead cylindrical cam, a driven roller, a load rod and a guide sleeve; the two ends of the bevel gear differential mechanism are connected with the two half shafts respectively, transmission gear pairs are arranged at the output ends of the two half shafts respectively, and the transmission gear pairs are connected with the load generation system. The problems of amplitude attenuation, phase lag and waveform distortion during high-frequency load simulation are solved.

Description

Technical Field

[0001] This invention relates to the field of axle technology, and more specifically, to a fatigue testing device for automobile axle production. Background Technology

[0002] As a key component for bearing and transmitting vehicle loads, the automotive axle is subjected to complex and varied road surface excitation loads during actual use. To ensure that the fatigue life of the axle meets design requirements, fatigue testing is necessary during the production stage. Existing axle fatigue testing equipment mainly uses a servo hydraulic system, which simulates the actual road surface load spectrum by adjusting the output pressure of the hydraulic cylinder through an electronically controlled proportional valve.

[0003] However, electro-hydraulic systems exhibit significant technical limitations when simulating high-frequency excitation on actual road surfaces. First, the system's frequency response is limited by the proportional valve's response speed and the compressibility of the hydraulic oil. When the excitation frequency exceeds 10Hz, amplitude attenuation and phase lag occur, making it impossible to accurately reproduce high-frequency load components. Second, high-frequency reciprocating motion causes severe friction in the hydraulic oil at the pipes and valve ports, leading to a rapid increase in oil temperature and a decrease in hydraulic oil viscosity. This alters the system's stiffness and damping characteristics, significantly reducing load control accuracy. Furthermore, the electro-hydraulic system experiences time delays at every stage, from load sensor signal acquisition, A / D conversion, control algorithm calculation to D / A conversion output. The cumulative effect of these delays is particularly pronounced under high-frequency conditions, resulting in severe load waveform distortion and an inability to accurately simulate the high-frequency excitation characteristics of actual road surfaces. Summary of the Invention

[0004] This invention provides a fatigue testing device for automobile axle production, which solves the technical problems of amplitude attenuation, phase lag and waveform distortion in high-frequency load simulation in related technologies.

[0005] This invention provides a fatigue testing device for automobile axle production, comprising: The test bench base is fixedly installed with an axle clamping mechanism, which fixes the test axle. The bevel gear differential includes a differential housing, a planetary gear carrier, two half-shaft bevel gears, two planetary bevel gears, a large gear, a small gear, and a main drive motor. The differential housing is fixedly connected to the test bench base via a bearing seat. The output shaft of the main drive motor is connected to the differential housing, and the other end is mounted on the test bench base via a motor bracket. The small gear is fixed to the motor output shaft, the large gear is fixed to the differential housing, the planetary gear carrier is fixedly connected to the differential housing, and both planetary bevel gears are mounted on the planetary gear carrier. The two half-shaft bevel gears mesh with the two planetary bevel gears respectively. The two ends of the bevel gear differential are connected to two half shafts respectively. The output ends of the two half shafts are equipped with transmission gear pairs. The two transmission gear pairs are connected to a load generation system. The transmission gear pairs include a driving bevel gear and a driven bevel gear. The driving bevel gear and the driven bevel gear mesh at a 90-degree angle. The load generation system includes a camshaft, a variable lead cylindrical cam, a driven roller, a load rod, and a guide sleeve. The variable lead cylindrical cam is fixed to the end of the camshaft by a key connection. The profile of the variable lead cylindrical cam includes three functional sections: an involute inlet section, an Archimedean spiral body section, and a cosine curve outlet section. The driven roller is mounted on the transverse boss in the middle of the load rod by a needle roller bearing. The upper end of the load rod is connected to one end of the test vehicle axle by a ball joint. The lower end of the load rod passes through the guide sleeve on the test bench base. The guide sleeve is equipped with an elastic buffer, which includes an upper spring seat, a lower spring seat, and a combined disc spring assembly. The upper spring seat is fixed to the lower end of the load rod, the lower spring seat is fixed to the test bench base, and the combined disc spring is pre-compressed between the upper spring seat and the lower spring seat.

[0006] Furthermore, the two driving bevel gears are respectively sleeved on the two half shafts, and the two driven bevel gears are respectively connected to the ends of the camshafts in the two load generation systems via splines.

[0007] Furthermore, the guide sleeve is also equipped with a linear bearing to constrain the vertical movement of the load rod.

[0008] Furthermore, each of the two half-shafts is equipped with a flexible coupling, which is located between the bevel gear differential and the load generation system, and is used to compensate for the axial and radial installation errors of the load generation system.

[0009] Furthermore, the variable lead cylindrical cam is a replaceable structure, connected to the flange at the end of the camshaft via bolt holes on the end face, and is used to replace variable lead cylindrical cams with different load spectra.

[0010] Furthermore, the linear bearing inside the guide sleeve adopts a circulating ball bearing structure for circulating rolling between the surface of the load rod and the inner wall of the guide sleeve.

[0011] Furthermore, the lead of the variable lead cylindrical cam varies continuously from 5 mm to 50 mm in the radial direction from the inner ring to the outer ring, for continuous adjustment of the load amplitude.

[0012] Furthermore, the combined disc spring assembly is a modular design, with each module containing a fixed number and arrangement of disc springs.

[0013] Furthermore, the disc springs can be stacked in a combination of unidirectional and anti-unidirectional stacking to change the stiffness characteristics of the elastic buffer.

[0014] Furthermore, the two load generation systems are arranged in a mirror-symmetric manner, and the two variable lead cylindrical cams are set with a 180° phase difference.

[0015] The beneficial effects of this invention are as follows: The fatigue testing device for automobile axle production of the present invention uses a purely mechanical differential load distribution mechanism and a variable lead cylindrical cam load generation system, thus overcoming the factors of slow proportional valve response speed, high compressibility of hydraulic oil, and accumulation of time delay in the electronic control link in the electro-hydraulic system. Therefore, it solves the problems of amplitude attenuation, phase lag, and waveform distortion during high-frequency load simulation.

[0016] Specifically, the variable lead cylindrical cam directly converts rotational motion into linear reciprocating motion of the load rod. The motion conversion process is purely mechanical contact transmission, eliminating the compression delay of hydraulic oil and the signal processing delay of the electronic control system. Precise machining of the cam profile ensures accurate reproduction of the load spectrum. The combined design of the involute inlet section, the Archimedean spiral body section, and the cosine curve outlet section achieves smooth load changes, avoiding impact and vibration.

[0017] The bevel gear differential achieves adaptive load frequency distribution through a purely mechanical differential principle. When there is a difference in stiffness between the left and right ends of the axle, the load rod on the side with lower stiffness experiences less displacement resistance, automatically increasing the rotational speed of the corresponding half-shaft bevel gear. This shortens the rotational cycle of the camshaft on that side, and consequently increases the frequency of load changes. This mechanical feedback characteristic allows the weaker parts of the axle to automatically bear higher-frequency fatigue loads, more realistically simulating the conditions in actual use where weak links bear more dynamic stress cycles. Applying higher-frequency loads to weak parts can more effectively detect potential defects.

[0018] Furthermore, the use of a mechanical transmission system avoids the problem of hydraulic oil overheating, keeps the system's stiffness and damping characteristics stable, and ensures the load control accuracy during long-term operation. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of the fatigue testing device for automobile axle production according to the present invention; Figure 2 This is the invention Figure 1 Enlarged view of point A in the middle; Figure 3 This is a top view of the fatigue testing apparatus for automobile axle production according to the present invention; Figure 4 This is a front view of the load generation system of the present invention; Figure 5 This is a left view of the load generation system of the present invention; Figure 6This is a perspective view of the bevel gear differential of the present invention.

[0020] In the diagram: 100, Test bench base; 101, Axle; 200, Differential housing; 201, Planetary gear carrier; 202, Left half-shaft bevel gear; 203, Planetary bevel gear; 204, Main drive motor; 205, Pinion gear; 206, Large gear; 207, Half-shaft; 208, Right half-shaft bevel gear; 209, Drive bevel gear; 210, Driven bevel gear; 300, Camshaft; 301, Variable lead cylindrical cam; 302, Driven roller; 303, Load bar; 304, Flexible coupling; 305, Involute inlet section; 306, Archimedes spiral main section; 307, Cosine curve outlet section; 400, Guide sleeve; 401, Linear bearing; 402, Upper spring seat; 403, Lower spring seat; 404, Combined disc spring assembly. Detailed Implementation

[0021] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.

[0022] At least one embodiment of the present invention discloses a fatigue testing device for automobile axle production, such as... Figure 1 - Figure 6 As shown, it includes: test bench base 100, axle clamping mechanism, main drive motor 204, bevel gear differential, load generation system on the left and load generation system on the right.

[0023] The test bench base 100 provides a supporting foundation for the entire device. The axle clamping mechanism is fixedly installed at a predetermined position on the test bench base 100 to fix the test axle 101. The main drive motor 204 is mounted on the test bench base 100 via a motor bracket.

[0024] The bevel gear differential includes a differential housing 200, a planetary gear carrier 201, a left half-shaft bevel gear 202, a right half-shaft bevel gear 208, and two planetary bevel gears 203. The differential housing 200 is supported within a bearing housing by a pair of angular contact ball bearings. The bearing housing is fixedly connected to the test bench base 100, and the differential housing 200 can rotate freely. The output shaft of the main drive motor 204 is connected to the differential housing 200 via a gear reduction mechanism, which includes a pinion 205 and a large gear 206. The pinion 205 is fixed to the output shaft of the main drive motor 204, and the large gear 206 is fixed to the differential housing 200. The planetary gear carrier 201 is fixedly connected to the differential housing 200. The two planetary bevel gears 203 are mounted on the planetary gear carrier 201 via planetary gear shafts and can rotate around these shafts. The left half-shaft bevel gear 202 and the right half-shaft bevel gear 208 mesh with the two planetary bevel gears 203 respectively, forming a differential transmission relationship. The left half-shaft bevel gear 202 and the right half-shaft bevel gear 208 are fixedly connected to the left half-shaft 207 and the right half-shaft 207, respectively.

[0025] The load generation system on the left includes a left camshaft 300, a left variable lead cylindrical cam 301, a left driven roller 302, a left load rod 303, and a left elastic damper. The left half-shaft 207 is connected to the left camshaft 300 via a transmission gear pair. The left variable lead cylindrical cam 301 is fixed to the end of the left camshaft 300 via a key connection. The working profile of the variable lead cylindrical cam 301 is precision-machined into a specific spatial curved surface. The profile of the variable lead cylindrical cam 301 includes three functional segments: an involute inlet segment 305, an Archimedean spiral body segment 306, and a cosine curve outlet segment 307. These segments are connected by smooth transition curves. The lead of the variable lead cylindrical cam 301 continuously varies radially from the inner to the outer ring within a range of 5mm to 50mm, achieving continuous adjustment of the load amplitude.

[0026] Both the left and right half-shafts 207 have transmission gear pairs at their output ends. An elastic coupling 304 is located between the bevel gear differential and the load generation system. The elastic coupling 304 can compensate for the axial and radial installation errors of the load generation system. The transmission gear pair includes a driving bevel gear 209 and a driven bevel gear 210. The driving bevel gear 209 and the driven bevel gear 210 mesh at a 90-degree angle. The driving bevel gear 209 is sleeved on the left half-shaft 207 / right half-shaft 207. The driven bevel gear 210 is connected to the ends of the left camshaft 300 / right camshaft 300 in the left load generation system / right load generation system via splines.

[0027] The variable lead cylindrical cam 301 on the left is a replaceable structure. It is connected to the flange at the end of the camshaft 300 through the bolt holes on the end face, which makes it easy to replace the variable lead cylindrical cam 301 with different load spectra.

[0028] The driven roller 302 on the left is mounted on the transverse boss in the middle of the load bar 303 on the left via a needle roller bearing. The outer surface of the roller maintains line contact with the working profile surface of the variable lead cylindrical cam 301. The upper end of the load bar 303 on the left is connected to the left end of the axle 101 via a ball joint. The ball joint allows the load bar 303 to swing within a certain angle range to accommodate the deformation of the axle 101. The lower end of the load bar 303 passes through a guide sleeve 400 on the test bench base 100. A linear bearing 401 is installed inside the guide sleeve 400, which restricts the load bar 303 to move only in the vertical direction.

[0029] To reduce frictional resistance and improve motion accuracy, the linear bearing 401 inside the guide sleeve 400 adopts a circulating ball bearing structure, in which the balls circulate between the surface of the load bar 303 and the inner wall of the guide sleeve 400 under the guidance of the cage.

[0030] The elastic buffer on the left is located below the load rod 303 and consists of an upper spring seat 402, a lower spring seat 403, and a combined disc spring assembly 404. The upper spring seat 402 is fixed to the lower end of the load rod 303, and the lower spring seat 403 is fixed to the test bench base 100 by bolts. The combined disc spring assembly 404 is assembled from multiple disc springs in a specific stacking manner, pre-loaded between the upper spring seat 402 and the lower spring seat 403. The stacking method of the disc springs includes combinations of same-direction stacking and opposite-direction stacking; by adjusting the stacking method, the stiffness characteristics of the elastic buffer can be changed.

[0031] The combined disc spring assembly 404 is a modular design, with each module containing a predetermined number and arrangement of disc springs. The overall stiffness can be adjusted by increasing or decreasing the number of modules.

[0032] The load generation system on the right is arranged in a mirror image of the load generation system on the left. The right half-shaft 207 drives the right camshaft 300 through a flexible coupling 304. The profile of the variable lead cylindrical cam 301 on the right is set with a 180° phase difference from that of the variable lead cylindrical cam 301 on the left. This phase difference allows the load on the right to be in the unloading phase when the load on the left is in the loading phase, realizing alternating loading between the left and right sides or synchronous loading with a specific phase relationship according to the design of the variable lead cylindrical cam 301 profile.

[0033] Execution steps The fatigue testing apparatus for automobile axle production according to this embodiment performs the following steps: Step 1: Install the test axle 101 on the axle clamping mechanism, and adjust the clamping position so that both ends of the axle 101 are aligned and connected with the ball joints of the left and right load bars 303 respectively.

[0034] Step 2: Start the main drive motor 204. The motor drives the differential housing 200 to rotate through the gear reduction mechanism.

[0035] Step 3: The differential housing 200 drives the planetary gear carrier 201 to rotate together. While the planetary gears revolve around the central axis of the bevel gear differential, they transmit the rotational motion to the left half-shaft bevel gear 202 and the right half-shaft bevel gear 208.

[0036] Step 4: The left and right half-shafts 207 drive the corresponding camshafts 300 and variable lead cylindrical cams 301 to rotate synchronously via couplings. Due to the 180° phase difference between the left and right variable lead cylindrical cams 301, an alternating loading mode is achieved.

[0037] Step 5: When the variable lead cylindrical cam 301 rotates, its working surface pushes the driven roller 302, forcing the load rod 303 to reciprocate vertically along the guide sleeve 400. During one revolution of the variable lead cylindrical cam 301, the involute inlet section 305 causes the load to rise slowly from zero, the Archimedean spiral main body section 306 generates a linearly changing main load, and the cosine curve outlet section 307 achieves smooth unloading of the load.

[0038] In step 5, the rotational speed of the variable lead cylindrical cam 301 is controlled by the rotational speed of the main drive motor 204 to achieve the application of loads at different frequencies.

[0039] Step 6: The vertical displacement of the load bar 303 compresses or releases the disc spring assembly in the elastic buffer, generating an elastic restoring force proportional to the displacement. This restoring force is transmitted to both ends of the axle 101 through the load bar 303 and the ball joint, forming the alternating load required for the fatigue test.

[0040] Step 7: When there is a difference in stiffness between the left and right ends of the axle 101, the displacement resistance of the load rod 303 on the side with greater stiffness increases, resulting in an increase in the rotational resistance of the camshaft 300 on that side. The differential characteristics of the bevel gear differential cause the speed of the half-shaft bevel gear on the side with greater resistance to automatically decrease, while the speed on the side with less resistance increases accordingly.

[0041] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A fatigue testing device for automobile axle production, characterized in that, include The test bench base is fixedly installed with an axle clamping mechanism, which fixes the test axle. The bevel gear differential includes a differential housing, a planetary gear carrier, two half-shaft bevel gears, two planetary bevel gears, a large gear, a small gear, and a main drive motor. The differential housing is fixedly connected to the test bench base via a bearing seat. The output shaft of the main drive motor is connected to the differential housing, and the other end is mounted on the test bench base via a motor bracket. The small gear is fixed to the motor output shaft, the large gear is fixed to the differential housing, the planetary gear carrier is fixedly connected to the differential housing, and both planetary bevel gears are mounted on the planetary gear carrier. The two half-shaft bevel gears mesh with the two planetary bevel gears respectively. The two ends of the bevel gear differential are connected to two half shafts respectively. The output ends of the two half shafts are equipped with transmission gear pairs. The two transmission gear pairs are connected to a load generation system. The transmission gear pairs include a driving bevel gear and a driven bevel gear. The driving bevel gear and the driven bevel gear mesh at a 90-degree angle. The load generation system includes a camshaft, a variable lead cylindrical cam, a driven roller, a load rod, and a guide sleeve. The variable lead cylindrical cam is fixed to the end of the camshaft by a key connection. The profile of the variable lead cylindrical cam includes three functional sections: an involute inlet section, an Archimedean spiral body section, and a cosine curve outlet section. The driven roller is mounted on the transverse boss in the middle of the load rod by a needle roller bearing. The upper end of the load rod is connected to one end of the test vehicle axle by a ball joint. The lower end of the load rod passes through the guide sleeve on the test bench base. The guide sleeve is equipped with an elastic buffer, which includes an upper spring seat, a lower spring seat, and a combined disc spring assembly. The upper spring seat is fixed to the lower end of the load rod, the lower spring seat is fixed to the test bench base, and the combined disc spring is pre-compressed between the upper spring seat and the lower spring seat.

2. The fatigue testing device for automobile axle production according to claim 1, characterized in that, The two driving bevel gears are respectively sleeved on the two half shafts, and the two driven bevel gears are respectively connected to the ends of the camshafts in the two load generation systems via splines.

3. The fatigue testing device for automobile axle production according to claim 1, characterized in that, The guide sleeve is also equipped with a linear bearing to constrain the vertical movement of the load rod.

4. The fatigue testing device for automobile axle production according to claim 1, characterized in that, Both half-shafts are equipped with flexible couplings, which are located between the bevel gear differential and the load generation system to compensate for axial and radial installation errors of the load generation system.

5. The fatigue testing device for automobile axle production according to claim 1, characterized in that, The variable lead cylindrical cam is a replaceable structure, connected to the flange at the end of the camshaft via bolt holes on the end face, and is used to replace variable lead cylindrical cams with different load spectra.

6. The fatigue testing device for automobile axle production according to claim 3, characterized in that, The linear bearing inside the guide sleeve adopts a circulating ball bearing structure for circulating rolling between the surface of the load rod and the inner wall of the guide sleeve.

7. The fatigue testing device for automobile axle production according to claim 5, characterized in that, The lead of the variable lead cylindrical cam varies continuously from 5 mm to 50 mm in the radial direction from the inner ring to the outer ring, which is used for continuous adjustment of the load amplitude.

8. The fatigue testing device for automobile axle production according to claim 1, characterized in that, The combined disc spring assembly is a modular design, with each module containing a fixed number and arrangement of disc springs.

9. The fatigue testing device for automobile axle production according to claim 8, characterized in that, The disc springs can be stacked in the same direction or in opposite directions to change the stiffness characteristics of the elastic buffer.

10. The fatigue testing device for automobile axle production according to claim 7, characterized in that, The two load generation systems are arranged in a mirror-symmetric manner, and the two variable lead cylindrical cams are set with a 180° phase difference.

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