Variable center distance split type gear test bench and nonlinear vibration test method

Abstract

The application discloses a variable center distance split type gear test bench and a nonlinear vibration testing method. The test bench uses a split open gear box design, and the driving gear shaft and the driven gear shaft are respectively arranged on two parallel driving gear boxes and driven gear boxes. The driving gear box shaft system is fixed on the workbench surface and cannot be moved. The driven gear box, the sensor on the coaxial system and the load motor are placed on the movable platform supported by the linear sliding guide rail, so that the center distance between the driving gear shaft and the driven gear shaft can be adjusted. After the center distance is determined, the center distance is locked through the locking mechanism between the box bodies. The application solves the problem that the traditional integrated gear box cannot change the theoretical gear side clearance. The application can be used for observing the meshing impact phenomenon caused by the gear side clearance, the meshing impact occurs in the gear meshing line direction, and can be used for verifying the nonlinear characteristics in the gear box meshing process, such as periodic state, quasi-periodic state and chaotic state.

Description

Technical Field

[0001] This invention relates to the field of gear testing equipment technology, specifically a split-type gear test bench with variable center distance and its testing method. This invention provides corresponding data processing methods by testing the transmitted torque between gear teeth, the radial vibration of the input and output shafts, the real-time rotational speed, and the real-time angular displacement data, in order to study the nonlinear vibration phenomenon caused by gear meshing impact. Background Technology

[0002] Gears, as key components for power transmission, are widely used in mechanical engineering. Their vibration reduction, noise reduction, and nonlinear dynamics have been a focus of research for scholars both domestically and internationally. To ensure lubrication during gear meshing, backlash must be reserved during the design phase. With changes in gear speed and load, under high-speed and loaded conditions, backlash can lead to tooth surface impact, tooth disengagement, and tooth back impact during gear meshing, a phenomenon known as gear meshing impact. [1,2] In theoretical and simulation studies in this field, various nonlinear characteristics can occur in meshing impacts, including periodic motion, chaotic motion, quasi-periodic motion, period-doubling bifurcation, and Hopf bifurcation. [3] However, since meshing impact occurs along the meshing line of the gear pair, and the tooth flank clearance is on the order of micrometers, its nonlinear vibration cannot be directly measured. Therefore, it is necessary to design a device for indirect measurement of meshing impact. The goal is to generate phase diagrams, Poincaré sections, and maximum Lyapunov exponent diagrams for the measurement. [3] The required data values ​​are used to determine whether the meshing impact is in a state of chaotic vibration. The measured values ​​include the time-varying torque, time-varying angular velocity, and time-varying angular displacement of the driving and driven wheels.

[0003] Due to limitations in operating conditions, size, and usage, gearboxes can be structurally classified into planetary gearboxes and parallel shaft gearboxes. Gears can be spur, helical, or herringbone gears. Supports can be provided by rolling bearings or sliding bearings. Sliding bearings can be further divided into hydrodynamic lubrication and hydrostatic lubrication, and lubrication methods include splash lubrication, forced oil injection lubrication, and solid grease lubrication. Based on high-speed gearboxes in the gas turbine field, the test object of this invention has the following characteristics: actual operating conditions are high-speed and heavy-load; the gear shaft is supported by hydrodynamic lubrication bearings; and it features a single-stage parallel shaft spur and herringbone gear structure.

[0004] The existing technology is as follows:

[0005] Technical Comparison with Patent CN112781865A "A Test Method for Gear Vibration and Noise"

[0006] Patent CN112781865A uses tests on the vibration, noise, and transmission errors of an experimental gearbox to correct the simulation calculation model.

[0007] However, its model still considers traditional vibration data, including housing vibration acceleration, bearing housing vibration acceleration, machine foot vibration acceleration, high and low speed shaft rotation angles, and noise issues.

[0008] Patent CN112781865A adopts an integrated gearbox testing scheme, in which the gearbox is tested as a whole and the system center distance is fixed.

[0009] Currently, test benches for high-speed gearboxes supported by sliding bearings are mostly general-purpose testing machines. The gearbox is tested as a whole with a fixed center distance and the sliding bearing lubrication is not adjustable. The measurement targets are mostly general vibration characteristics, including vibration acceleration values ​​of the bearing housing, vibration acceleration values ​​at the housing, vibration acceleration values ​​at the machine feet, radiated noise, etc. The vibration data of high-speed and low-speed shafts are tested separately and are usually not related. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention proposes a split-type gear test bench with variable center distance and its testing method. The purpose is to test the nonlinear vibration phenomena caused by meshing impact. Therefore, adjusting the tooth flank clearance between the gear teeth is the main control objective of this invention. The measured data values ​​also require synchronous measurement between the high-speed and low-speed gear shafts. The data between each pair are correlated and require coordinated testing, and are ultimately processed into valid data in the meshing line direction. Specifically, this invention comprehensively considers the actual testing needs of high-speed gearboxes in the gas turbine field and designs and develops this open test bench with variable center distance. The test data can be used for nonlinear vibration analysis, observing and searching for chaotic vibration phenomena in the meshing line direction, and plotting phase diagrams, Poincaré section diagrams, and maximum Lyapunov exponent diagrams for analysis. Specifically, a rotary encoder is installed at the shaft end to obtain time-varying angular displacement values ​​through pulse data processing, and a numerical processing scheme is provided to convert them into displacement vibration data in the meshing line direction; a non-contact torque sensor is used to measure the time-varying torque of the high and low speed shafts, which can be converted into time-varying gear meshing force; a non-contact rotary encoder is used to measure the time-varying angular velocity of the high and low speed shafts; and eddy current sensors with a 90° radial angle are set on the high and low speed shafts to collect displacement data to verify the gyroscopic effect of the gear shaft under hydrodynamic lubrication conditions.

[0011] To achieve the above-mentioned technical objectives, the present invention employs the following technical means:

[0012] A split-type gear test bench with variable center distance, used to verify the nonlinear characteristics of the meshing process caused by tooth backlash, includes:

[0013] Workbench;

[0014] The drive gear shaft portion is fixedly mounted on the worktable and located on one side of the worktable, and includes:

[0015] An open-type drive gearbox, a drive gear shaft rotatably mounted on the open-type drive gearbox, a drive gear mounted on the drive gear shaft, and a drive motor axially connected to the drive gear shaft;

[0016] A load gear shaft portion, disposed on the worktable and parallel to the drive gear shaft portion, includes:

[0017] An open driven gearbox, a driven gear shaft rotatably mounted on the open driven gearbox, a driven gear mounted on the driven gear shaft, and a load axially connected to the driven gear shaft;

[0018] The bottom of the open driven gearbox is connected to the worktable via a slide and a locking mechanism. The center distance between the driving gear shaft and the driven gear shaft can be quantitatively adjusted via the slide and the locking mechanism to change the tooth backlash between the driving gear and the driven gear.

[0019] The first torque and speed sensor is used to detect the torque and speed of the drive gear shaft;

[0020] The second torque and speed sensor is used to detect the torque and speed of the driven gear shaft;

[0021] A first non-contact torque and speed sensor is used to detect the time-varying torque and time-varying speed of the drive gear shaft;

[0022] The second non-contact torque and speed sensor is used to detect the time-varying torque and time-varying speed of the driven gear shaft;

[0023] A first rotary encoder is used to detect the time-varying angular displacement value of the free end of the drive gear shaft;

[0024] The second rotary encoder is used to detect the time-varying angular displacement value of the free end of the driven gear shaft;

[0025] Eddy current sensors, including a pair, are set at a 90-degree angle at the shaft end of the drive gear shaft for observing the gyro precession trajectory of the drive gear shaft;

[0026] The controller has its signal input terminal connected to the first torque speed sensor, the second torque speed sensor, the first non-contact torque speed sensor, the second non-contact torque speed sensor, the first rotary encoder, the second rotary encoder, and the eddy current sensor, and its signal output terminal connected to the drive motor.

[0027] Both the driving gear and the driven gear use standard involute tooth profile gears.

[0028] The slide and locking mechanism include:

[0029] A base plate is fixedly connected to the workbench, and a sliding rail moving pair is provided between the base plate and the bottom of the open driven gearbox;

[0030] A thrust block is fixed on a base plate located on one side of the driven gearbox, and a first limiting bolt is threaded onto the thrust block;

[0031] The second limiting bolt is threaded onto the housing on the other side of the driven gearbox, and the non-threaded end of the second limiting bolt is in contact with the driving gearbox.

[0032] The load is a load servo motor, and the load servo motor is connected to the signal output terminal of the controller.

[0033] The drive gear shaft and the drive gearbox are rotatably connected by two first sliding bearings; a hydraulic station is provided around the worktable;

[0034] The bearing lubricating oil in the hydraulic station enters the groove of the first sliding bearing seat through the oil inlet pump and the first oil inlet pipeline respectively. Each first sliding bearing seat is equipped with a first oil inlet flow valve at the oil inlet.

[0035] The driven gear shaft and the driven gearbox are rotatably connected by two second sliding bearings; the bearing lubricating oil in the hydraulic station enters the groove of the second sliding bearing seat through the oil inlet pump and the second oil inlet pipeline respectively, and a second oil inlet flow valve is provided at the oil inlet of each second sliding bearing seat.

[0036] Both the bottom of the inner wall of the open-type active gearbox and the bottom of the inner wall of the open-type active gearbox are provided with oil return grooves, and the bearing lubricating oil is recovered to the oil storage grooves through the oil return pump and the oil return pipeline.

[0037] This invention further discloses a method for nonlinear vibration testing using a split-type gear test bench with variable center distance, including a tooth backlash test:

[0038] The tooth backlash is changed by adjusting the center distance between the gear shafts. After replacing the drive gear shaft and the driven gear shaft, the minimum center distance between them is tested first. The minimum clearance between the drive gear shaft in the open drive gearbox and the driven gear shaft in the open driven gearbox is measured by the slide table and locking mechanism with a clearance micrometer. This is the minimum center distance of the system. The test is carried out without jamming. After the stage test is completed and the system is completely stopped, the center distance between the drive gear shaft and the driven gear shaft is increased at a specific interval and the test is carried out. The test is carried out in sequence. When the center distance is increased to more than the limit distance, it is judged whether the meshing noise increases significantly. If the meshing noise increases significantly, the test of increasing the center distance is stopped.

[0039] This invention further discloses a method for nonlinear vibration testing using the aforementioned split-type gear test bench with variable center distance, including the following tests:

[0040] Step test:

[0041] The test is divided into a constant torque stepped speed test and a constant speed stepped torque test. Taking the constant torque stepped speed test as an example, the center distance between the open drive gearbox and the open driven gearbox is controlled as the normal working condition. The load end is set to no-load condition or a specific torque. The drive motor is started at 50 rpm and kept for 3-5 seconds until it is running stably. Without turning off the drive motor, it is accelerated to the target maximum speed in sequence, with each acceleration interval being 50 rpm. After reaching the target maximum speed, the load servo motor and drive motor are stopped in sequence, and the bearing lubricating oil supply is kept normal.

[0042] Load test:

[0043] According to the actual working conditions, the controller drives the drive motor to input the test speed and maintain it until the operation is stable. Then, the load servo motor applies a specific torque in torque mode. The controller uses the speed value of the first torque speed sensor and the torque value of the second torque speed sensor to control the speed of the drive motor and the torque of the load servo motor in a closed loop to stabilize them and maintain operation for a specific time. After the test is completed, the torque output of the load servo motor is turned off first, and then the drive motor is turned off, while the bearing lubricating oil supply is maintained during the process.

[0044] This invention further discloses a method for nonlinear vibration testing using the aforementioned split-type gear test bench with variable center distance, including the following tests:

[0045] No-load test:

[0046] Turn off the control of the load servo motor or disconnect the flange coupling between the driven gear shaft and the load to keep the entire gearbox model running unloaded. Before running, turn on the oil inlet pump and return pump. After confirming that the flow meter and pressure meter values ​​are stable, conduct a gearbox test at a specific time. After the test is completed, turn off the drive motor until the drive motor stops completely while maintaining the supply of bearing lubricating oil.

[0047] Uniaxial test:

[0048] The slide and locking mechanism completely disengage the driving gear on the driving gear shaft from the driven gear shaft, allowing only the driving gear shaft to operate independently. Within a specific range, a specific speed is selected under the hydrodynamic lubrication condition of the sliding bearing. Based on the structural characteristics of the sliding bearing, a hydrodynamic lubrication model is calculated to maintain operation under oil film support, preventing bearing failure. After the drive motor stops, the bearing lubricating oil is supplied until the drive motor completely stops. The test data includes two parts: motor interference frequency data of the corresponding gear meshing model before stopping, and gyroscope precession path data of the driving gear shaft under hydrodynamic lubrication condition obtained by the eddy current sensor during the free travel segment after stopping.

[0049] Dry friction test;

[0050] Before the experiment, the oil inlet pump was turned off to supply oil to the open drive gearbox and the open driven gearbox. The gearbox spacing was set to the theoretical minimum center distance. The radial displacement data of the eddy current sensor was recorded. After running for 5-10 seconds, the bearing lubricating oil supply was turned on. The oil supply pressure was set to 0.1-0.2 MPa. The oil supply flow rate of the bearing lubricating oil was set according to the value obtained from the rotor dynamics simulation software.

[0051] This invention further discloses a method for nonlinear vibration testing using the aforementioned split-type gear test bench with variable center distance, including the following tests:

[0052] Bearing lubricating oil flow rate setting test: First, select an inlet pressure of 0.1-0.2 MPa based on the dynamic viscosity of the lubricating oil, which is specifically determined by the length of the sliding bearing inlet passage and the number of inlets;

[0053] The lubricating oil enters from the side wall of the sliding bearing and flows in naturally, without considering the static support of the lubricating oil pressure on the gear shaft;

[0054] Dry friction test was performed with lubricating oil turned off. Radial displacement data of eddy current sensor was read and average value of motion was recorded. The oil inlet flow valve of bearing was manually adjusted and the flow rate was increased at intervals of 0.1 L / min. Radial displacement data of eddy current sensor at each flow rate was analyzed until the gear shaft was completely floating in the hydrodynamic lubrication model. At this time, the average radial displacement was the smallest. The flow rate was recorded for other tests.

[0055] In addition, a specific speed was selected for testing in the gear-sliding bearing coupling model. In the theoretical model, if the speed is too low, the gear shaft will never be able to float completely. It needs to be adjusted in time. The specific adjustment plan is to accelerate the test at an initial speed of 1000 rpm in 200 rpm intervals.

[0056] This invention further discloses a data processing method for nonlinear vibration testing based on a split-type gear test bench with a variable center distance, including the conversion of rotational speed in the meshing line direction and the conversion of angular displacement in the meshing line direction.

[0057] I. The conversion of angular displacement in the direction of the meshing line can be obtained first from the characteristics of the involute tooth profile:

[0058] x = R bp θ p -R bg θ g -e(τ) (1.3)

[0059] In the formula, x represents the linear displacement along the meshing line, and R represents the linear displacement along the meshing line. bp R is the base circle radius of the driving gear. bg θ is the base circle radius of the driven gear. p It is the angular displacement of the driving gear, θ g It is the angular displacement of the driven gear, and e(τ) is the comprehensive transmission error along the meshing line direction;

[0060] II. The conversion of angular velocity along the line of engagement is expressed by the following formula:

[0061]

[0062] In the formula, x' is the linear velocity along the meshing line, and n p n is the rotational speed of the driving gear. g The rotational speed of the driven gear;

[0063] III. The time-varying speed and time-varying angular displacement values ​​collected from the driving gear shaft side and the driven gear side are transformed using Equations 1.1 and 1.2 above to obtain two sets of data representing the linear displacement x and linear velocity x' along the meshing line direction, respectively.

[0064] IV. Plot a phase diagram with linear velocity x' as the Y-axis data and linear displacement x as the X-axis data respectively, and take the rotation period as the cutoff to draw a Poincaré section, thereby determining whether the gear meshing system is in a chaotic state or a periodic state.

[0065] 2.3 Beneficial effects of the technical solution created by this invention

[0066] 1) This invention designs a split-type open parallel shaft gearbox. Using this design, the driving and driven gear shafts are respectively mounted in two parallel driving and driven gearboxes. The driving gearbox shaft is fixed to the worktable and cannot move. The driven gearbox, along with the sensors and load motor on the coaxial system, are placed on a movable platform supported by linear sliding guides. This allows the center distance between the driving and driven gear shafts to be adjustable. Once the center distance is determined, it is locked by a locking mechanism between the gearboxes. Because this invention uses standard involute tooth profile gears, the variable center distance can indirectly adjust the tooth flank clearance of the gear meshing system, while ensuring normal meshing. This invention solves the problem that traditional integrated gearboxes cannot change the theoretical tooth backlash, and can be used to observe the meshing impact phenomenon caused by tooth backlash. Meshing impact occurs in the direction of gear meshing line, and this phenomenon is prone to occur under conditions of large tooth backlash, high speed, and variable load. The vibration in the direction of meshing line is usually nonlinear. Therefore, the gearbox design of this invention can be used to verify the nonlinear characteristics of gearbox meshing process, such as periodic state, quasi-periodic state, chaotic state, etc.

[0067] 2) This invention employs sliding bearing support and, based on the principle of hydrodynamic lubrication, places a pair of eddy current sensors at a 90-degree angle at the shaft end to observe the gyroscopic precession trajectory of the gear shaft. The four sliding bearings are independently supplied with oil, allowing for controllable pressure and flow rate. By adjusting the center distance, the gear pairs can be completely disengaged, enabling independent testing of the rotor dynamics characteristics of a single shaft under hydrodynamic lubrication conditions. This solves the problem of non-interventional lubrication in traditional gearbox bearings, enabling testing of hydrodynamically lubricated bearings with varying flow rates and pressures.

[0068] 3) This invention provides an experimental scheme that transforms the acquired data into displacement and linear velocity in the meshing line direction, which can be used to plot the phase diagram and Poincaré section required for nonlinear vibration analysis. Unlike general gearbox testing, this invention involves simultaneous testing of both the input and output shafts. The purpose is to convert angular data into linear data in the meshing line direction for analysis of nonlinear vibrations caused by meshing impacts. Attached Figure Description

[0069] Figure 1 This is a three-dimensional structural diagram of a split-type gear test bench with variable center distance according to the present invention;

[0070] Among them, drive motor 1, flexible coupling 2, first torque and speed sensor 3, first flange coupling 4, first non-contact torque and speed sensor 5, second flange coupling 6, open drive gearbox 7, rotary encoder 8, open pinion 9, third flange coupling 10, second non-contact torque and speed sensor 11, fourth flange coupling 12, second torque and speed sensor 13, second flexible coupling 14, load servo motor 15, worktable 16, oil reservoir 17, rotary encoder 18, thrust block 19, slide platform 20, and linear slider guide rail 21;

[0071] Figure 2 A schematic diagram of the drive gearbox after removing the upper cover and the oil baffle plate;

[0072] Among them, there are oil return line 22, oil inlet line 23, eddy current sensor 24, drive gear shaft 25, first sliding bearing seat (26, 27), drive gearbox housing 28, flexible coupling 38, and oil return groove 29;

[0073] Figure 3 This is a schematic diagram of the small gearbox structure of the present invention;

[0074] Second limiting bolt 30, first limiting bolt 31;

[0075] Figure 4 This is a schematic diagram of the overall layout of the split-type gear test bench with variable center distance according to the present invention;

[0076] Among them, cooling water tower 32, HBM acquisition module 33, NI acquisition module 34, controller 35, industrial control computer 36, and hydraulic station 37;

[0077] Figure 5 This is a schematic diagram of the structure of the gear shaft of the test object;

[0078] Figure 6 This is a schematic diagram of the dynamic model of the gear system along the meshing line.

[0079] Figure 7 This is a flowchart of the nonlinear vibration test described in this invention;

[0080] Figure 8 This is a data processing flowchart for the nonlinear vibration testing method of the split gear test bench with variable center distance of the present invention. Detailed Implementation

[0081] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0082] Device components:

[0083] This invention relates to a split-type gear test bench with variable center distance and a nonlinear vibration testing method.

[0084] The test bench is a two-axis, single-stage parallel shaft structure, consisting of a drive gear shaft and a load gear shaft. It also includes a control system, data acquisition system, oil lubrication system, cooling system, and industrial control computer.

[0085] 1. The drive gear shaft section, from the drive motor to the rotary encoder at the end of the drive gear shaft, includes a drive motor 1, a flexible coupling 2, a torque and speed sensor 3, a first flange coupling 4, a non-contact torque and speed sensor 5, a second flange coupling 6, an open drive gearbox 7, and a rotary encoder 8.

[0086] Since the open-type driving gearbox and the open-type driven gearbox have similar structures, the following description uses the open-type driving gearbox 7 as an example. The specific structure of the open-type driving gearbox 7 is as follows: Figure 2 As shown, this figure is a top view after removing the upper cover and oil baffle plate. Compatible gear shafts include spur gear shafts and herringbone gear shafts, such as... Figure 4 As shown. The first sliding bearing housing 26 and the second sliding bearing housing 27 are installed in the pre-opened groove of the open drive gearbox housing 28, and are configured as a transition fit. The drive gear shaft 25 is installed on the sliding bearing housing.

[0087] The sliding bearings used in this invention are all radial sliding bearings. A gap exists between the sliding bearing and the gear shaft, allowing oil to enter for lubrication. The first sliding bearing housing 26 also serves as an axial positioning element, with an oil film between its sidewall and the gear shaft step to prevent jamming. Bearing lubricating oil is injected into the groove of the sliding bearing housing through the oil inlet pipe 23, ensuring an oil supply pressure of 0.1-0.2 MPa. Figure 2 As shown in section AA, the bearing lubrication here is achieved through hydrodynamic lubrication, which does not require a high-pressure lubricating oil supply.

[0088] The bottom of the inner wall of the open-type drive gearbox housing 28 is provided with an oil return groove 29, which recovers lubricating oil through the oil return pipe 22, such as... Figure 2 As shown in the interface BB.

[0089] Two eddy current sensors 24 are mounted on the side of the journal of the drive gear shaft 25, such as... Figure 2 As shown in section CC, the eddy current sensor 24 has a 1-2 mm gap with the gear shaft surface, enabling non-contact measurement. The measured data is radial displacement vibration data at a 90° angle. The rotary encoder 18 is connected to the shaft system via a flexible coupling 29.

[0090] 2. The entire load gear shaft assembly is mounted on platform 20, including a rotary encoder 18, an open driven gearbox 9, a third flange coupling 10, a second non-contact torque-speed sensor 11, a fourth flange coupling 12, a second torque-speed sensor 13, a second flexible coupling 14, and a load servo motor 15. Platform 20 is mounted on a linear slider guide rail 21, allowing adjustment of the center distance between the driving and driven gear shafts, thereby changing the tooth backlash of the entire meshing system. The position in the center distance direction is fixed by a thrust block 19, a first limit bolt 31, and a second limit bolt 30. Specific method: First, fully screw in the second limit bolt 30, push in the driven gearbox housing 9, so that the driving and driven gears are in full contact and tighten the first limit bolt 31. At this time, it is necessary to ensure that the second limit bolt 30 is not working. Measure the clearance value between the two gearboxes to obtain the center distance value when the gear backlash is zero in the fully jammed state. Then, unscrew the second limit bolt 30 in sequence and test with a quarter turn as the variable. With the help of a clearance micrometer, the center distance adjustment test with an accuracy of 0.01-0.02mm can be achieved.

[0091] 3. Control device, oil lubrication device, cooling device, and industrial control computer: including a first torque and speed sensor 3 for control, a second torque and speed sensor 13 at the load end, a controller 35, a hydraulic station 37, a cooling tower 32, an industrial control computer 36, and a bus; the industrial control computer 36 controls the drive motor 1, the load servo motor 15, the hydraulic station 37, and the cooling tower 32 through the controller 35 based on the signals from the first torque and speed sensor 3 and the second torque and speed sensor 13; the industrial control computer 36 and the controller 35 are connected via a bus. The specific control process is as follows: speed and torque control, firstly, the industrial control computer presets the speed value, and the first torque and speed sensor 3 stabilizes the speed of the drive motor 1. After the speed stabilizes, the industrial control computer sends a torque control signal to the load servo motor 15. At this time, the load motor is in constant torque mode and does not consider the speed change at the load end. The torque value is controlled by the signal from the second torque and speed sensor 13. Since this is a motor-driven system, the load on the load side affects the output efficiency of the drive motor, leading to changes in speed. At this time, the speed of the drive motor and the torque value on the load side are constantly changing. The signals from the drive motor, the drive shaft sensor, the load-side sensor, and the load motor are integrated into a closed-loop control flow. Furthermore, the controller only has on / off control over the cooling tower 32 and the hydraulic station 37. The flow rate and pressure of the hydraulic station providing lubrication to the sliding bearings are controlled by flow valves and pressure valves. The cooling tower is kept constantly to ensure heat dissipation for the load motor.

[0092] 4. Data Acquisition Device: The data to be acquired by the acquisition device includes four types: torque, speed, angular displacement, and radial displacement values ​​of the driving and driven gear shafts. Torque and speed values ​​are acquired via HBM acquisition module 33, while angular and radial displacement values ​​are acquired via NI acquisition module 34. The first non-contact torque-speed sensor 5 and the second non-contact torque-speed sensor 11 connected to the HBM acquisition module are both non-contact sensors, with an actual sampling frequency meeting the 20kHz standard. The NI acquisition module 34 uses four eddy current sensors for the driving and driven gear shafts, acquiring analog current signals. The NI acquisition module 34 includes a counter function, using edge counting to record the pulse values ​​of rotary encoders 8 and 18. The sampling frequency of each sensor is 50kHz.

[0093] Working Principle: This invention divides the parallel shaft gearbox into two parts: an open driving gearbox and an open driven gearbox. Each gearbox is equipped with an axially positioned radial sliding bearing, which can accommodate gear shaft specimens without axial force, including spur gear shaft specimens and herringbone gear shaft specimens. The herringbone teeth themselves can counteract the axial force during meshing transmission. Compared to spur gear shafts, the herringbone driven gear shaft does not require an axial positioning step. Aside from the fixed errors caused by the manufacturing process, the tooth flank clearance between the gear pairs can be adjusted according to the change in center distance due to the geometric characteristics of the meshing line. Since changes in center distance can lead to misalignment between the driven gear shaft and the load section, this invention fixes the sensors, couplings, and other components on the driven gearbox and load shaft system onto the same linear guide slide. The center distance, torque setting, and speed setting are used as experimental input parameters to observe the nonlinear vibration phenomenon during gear meshing.

[0094] This invention provides a test method for nonlinear vibration, including the following steps: bearing lubricating oil flow rate setting test, no-load test, uniaxial test, dry friction test, load test, tooth flank clearance test, and stepped test.

[0095] In the flow rate setting test, a suitable inlet pressure is first selected based on the dynamic viscosity of the lubricating oil, which can be 0.1-0.2 MPa. The specific pressure can be determined by the length of the sliding bearing inlet channel and the number of inlets. The lubricating oil enters from the side wall of the sliding bearing under natural flow conditions, without considering the static support of the gear shaft by the lubricating oil pressure. A dry friction test is performed with the lubricating oil turned off. The radial displacement data of the eddy current sensor 24 is read, and the average value under motion is recorded. The flow rate valve of the bearing is manually adjusted, increasing the flow rate at intervals of 0.1 L / min. The radial displacement data of the eddy current sensor 24 at various flow rates is analyzed until the average radial displacement data is minimized when the gear shaft is completely floating in the dynamic lubrication model. The flow rate is then recorded for subsequent experiments. Additionally, a specific rotational speed needs to be selected for testing in the gear-sliding bearing coupling model. In the theoretical model, if the rotational speed is too low, the gear shaft may not be able to float completely. Adjustments are necessary. A specific adjustment scheme is to start at an initial speed of 1000 rpm and accelerate the test at 200 rpm intervals.

[0096] In the no-load test procedure, the control of the load servo motor can be turned off or the flange coupling 12 can be disconnected to keep the entire gearbox model running under no-load conditions. The drive motor 1 is controlled by the feedback signal of the first torque speed sensor 3, so disconnecting the load end has no impact on the stability of the drive end speed. The operating speed can be set according to the actual operating capability of the drive motor. The rated speed of the drive motor in this test bench is 3000 rpm. Since it is a speed increaser with a gear ratio of 1:2, the driven gearbox can achieve a maximum test speed of 6000 rpm. According to the actual operating requirements of the high-speed gearbox, no-load tests can be conducted at speeds of 50-3000 rpm. Before running the motor system, the sliding bearing oil inlet and return system must be turned on. After confirming that the flow meter and pressure gauge values ​​are stable, the gearbox test is conducted for a specific time. Since the transition from chaotic to periodic motion of the meshing gear pair in the simulation is generally short, 5-30 seconds can be used as the duration of a single test. After the test, the drive motor is turned off until it stops completely while maintaining the lubricating oil supply.

[0097] In the single-axis test procedure, the first limiting bolt 31 is first completely loosened to completely disengage the open drive gearbox 7 from the load shaft system, allowing only the drive shaft system to operate independently. Within a specific range, such as 500-3000 rpm, a specific speed under hydrodynamic lubrication conditions for the sliding bearing is selected. Based on the structural characteristics of the sliding bearing, such as elliptical bearings, three-wedge bearings, and misaligned bearings, a suitable hydrodynamic lubrication model is calculated. The bearing is kept in an oil film support state to prevent bearing burnout. Each run can be 30 seconds. After the drive motor stops, lubrication is maintained until the bearing stops completely. The test data includes two parts: before stopping, the motor interference frequency data of the corresponding gear meshing model can be obtained; after stopping, the free travel segment data of the shaft under hydrodynamic lubrication conditions is obtained through an eddy current sensor.

[0098] In the dry friction test procedure, before the experiment, the oil supply to the open drive gearbox and open driven gearbox of the hydraulic station 37 is shut off. The gearbox spacing is set to the theoretical minimum center distance. The radial displacement data of the eddy current sensor 24 is recorded. After running for 5-10 seconds, the lubricating oil supply can be turned on. The speed should not be too high; for example, the drive motor is set to 500 rpm for the test. The pressure to restore the oil supply is set to 0.1-0.2 MPa, and the flow rate is set according to the values ​​obtained from the rotor dynamics simulation software, for example, a flow rate input of less than 3 L / min. The torque difference is recorded to evaluate the dry friction power consumption. The radial displacement value is recorded to analyze the shaft end vibration characteristics under dry friction conditions.

[0099] In the load test procedure, based on the actual working conditions, within a specific range, such as 500-3000 rpm, the normal operating speed of the sliding bearing under hydrodynamic lubrication is selected; within a specific range, such as 0.1-0.2 MPa, a specific pressure value close to the actual working conditions is selected; the controller 35 drives the drive motor 1 to input the test speed and maintain it until the operation is stable, for example, a stabilization time of 3 seconds can be set; then the load servo motor 15 applies a specific torque in torque mode, for example, 0.1-15 Nm, during which the water cooling system 32 is kept running normally; the controller 35 uses the speed value of sensor 3 and the torque value of sensor 13 to control the speed of drive motor 1 and the torque of load servo motor 15 in a closed loop to stabilize them and maintain operation for a specific time, for example, 30-60 seconds; after the test is completed, the torque output of load servo motor 15 is turned off first, and then the drive motor is turned off, during which the lubricating oil supply is maintained until the system completely stops.

[0100] In the tooth flank clearance test procedure, the tooth flank clearance is changed by adjusting the center distance. After replacing the driving and driven gear shafts, the minimum center distance between them needs to be tested first. This can be done by removing the second limit bolt 30, fully pushing the load platform 20 on the linear guide 21, and applying a small amount of lubricating oil to the optical shaft part of the sliding bearing contact. Rotate the gear shaft system to fully mesh the driving and driven gear shafts, tighten the first limit bolt 31, and measure the minimum clearance between the driving and driven gearboxes with a clearance micrometer. This is the minimum center distance of the system. The test is conducted without jamming. After the system has completely stopped after the phase test is completed, the center distance between them is increased by a specific interval, for example, the center distance is increased by 0.12mm. The test is conducted under no-load conditions at 500-1000 rpm. When the center distance is increased to more than the limit distance of 1-2mm, it is judged whether the meshing noise has increased significantly. At this point, the test of increasing the center distance is stopped.

[0101] The stepped test procedure can be divided into a constant torque stepped speed test and a constant speed stepped torque test. Taking the constant torque stepped speed test as an example, the center distance between the open drive gearbox and the open driven gearbox is controlled under normal working conditions, such as the minimum center distance within an increment of 0.4mm. The load end is taken under no-load conditions or a specific torque. The drive motor 1 is started at 50 rpm and kept for 3-5 seconds until stable operation. Without turning off the drive motor, it is accelerated to the target maximum speed in sequence. The interval between each acceleration can be 50 rpm. After reaching the target maximum speed, such as 1000 rpm, the load servo motor 15 and drive motor 1 are stopped in sequence, while the hydraulic station 37 is kept in normal oil supply until it stops.

[0102] Since meshing impact occurs along the line of engagement, the dynamic model of the entire gear system needs to be discussed within this direction, as illustrated in the diagram. Figure 1 As shown, bearings, as the direct support points of the entire gear system, primarily affect the meshing system through bearing stiffness and damping. For the hydrodynamic lubrication bearing model, the oil supply is a key control variable. A complete hydrodynamic lubrication process requires maintaining an intact oil film throughout all time periods; therefore, the supply of bearing lubricating oil needs to be controlled. Controllable variables include the oil flow rate and pressure. In a dual-rotor, four-bearing support system with gear meshing, the frictional power consumption and end leakage flow of the sliding bearing are affected by the direct support force and rotational speed. In this experiment, all values ​​are expressed in the direction of the meshing line; therefore, the bearing's frictional power consumption and end leakage flow are directly related to the meshing force between the gears.

[0103] Add bearing lubricating oil flow rate setting test: First, select an appropriate inlet pressure according to the dynamic viscosity of the lubricating oil, which can be 0.1-0.2 MPa. The specific pressure can be determined by the length of the sliding bearing inlet channel and the number of inlets. The lubricating oil enters from the side wall of the sliding bearing and is in a natural flow state. The static support of the gear shaft by the lubricating oil pressure is not considered. The lubricating oil is turned off and a dry friction test is performed. The radial displacement data of the eddy current sensor (24) is read and the average value of the motion state is recorded. The flow valve of the bearing is manually adjusted and the flow rate is increased at intervals of 0.1 L / min. The radial displacement data of the eddy current sensor (24) under each flow rate is analyzed until the gear shaft is completely floating in the dynamic pressure lubrication model. At this time, the average radial displacement is the smallest. The flow rate is recorded for other tests. In addition, a specific speed needs to be selected for testing in the gear-sliding bearing coupling model. In the theoretical model, if the speed is too low, the gear shaft will never be able to float completely. It needs to be adjusted in time. The specific adjustment scheme is to accelerate the test at an initial speed of 1000 rpm in intervals of 200 rpm.

[0104] Throughout the testing process, the data acquisition results were consistent. The specific data for nonlinear vibration and chaotic vibration are as follows: the first non-contact sensor 5 obtains the time-varying torque value and time-varying speed value at the end of the driving gear shaft; the rotary encoder 8 obtains the time-varying angular displacement value at the free end of the driving gear shaft; the non-contact sensor 11 obtains the time-varying torque value and time-varying speed value at the end of the driven gear shaft; and the rotary encoder 18 obtains the time-varying angular displacement value at the free end of the driven gear shaft.

[0105] To apply the data to nonlinear vibration analysis, the acquired data values ​​need to be converted into effective vibration values ​​along the meshing line to determine whether the system is in a periodic, quasi-periodic, or chaotic state. This invention provides a data processing method, including the conversion of rotational speed and angular displacement along the meshing line.

[0106] I. The conversion of angular displacement in the direction of the meshing line can be obtained first from the characteristics of the involute tooth profile:

[0107] x = R bp θ p -R bg θ g -e(τ) (1.5)

[0108] In the formula, x is the linear displacement along the meshing line, and R is the linear displacement along the meshing line. bp R is the base circle radius of the driving gear. bg θ is the base circle radius of the driven gear. p It is the angular displacement of the driving gear, θ g It is the angular displacement of the driven gear, and e(τ) is the comprehensive transmission error along the meshing line direction.

[0109] II. The conversion of angular velocity along the line of engagement can be expressed by the following formula:

[0110]

[0111] In the formula, x′ is the linear velocity along the meshing line, and n p n is the rotational speed of the driving gear. g The rotational speed of the driven gear;

[0112] III. By performing the above transformations (Equation 1.1) and (Equation 1.2) on the time-varying speed and time-varying angular displacement values ​​collected from the driving gear shaft side and the driven gear side, two sets of data can be obtained, representing the linear displacement x in the direction of the meshing line and the linear velocity x′ along the direction of the meshing line, respectively.

[0113] IV. Plot a phase diagram with linear velocity x′ as Y-axis data and linear displacement x as X-axis data respectively, and take the rotation period as the cutoff to draw a Poincaré section. This can be used to determine whether the gear meshing system is in a chaotic state or a periodic state.

Claims

1. A split-type gear test bench with variable center distance, used to verify the nonlinear characteristics of the meshing process caused by tooth backlash, comprising: Workbench; The drive gear shaft portion is fixedly mounted on the worktable and located on one side of the worktable, and includes: An open-type drive gearbox, a drive gear shaft rotatably mounted on the open-type drive gearbox, a drive gear mounted on the drive gear shaft, and a drive motor axially connected to the drive gear shaft; A load gear shaft portion, disposed on the worktable and parallel to the drive gear shaft portion, includes: An open driven gearbox, a driven gear shaft rotatably mounted on the open driven gearbox, a driven gear mounted on the driven gear shaft, and a load axially connected to the driven gear shaft; The bottom of the open driven gearbox is connected to the worktable via a slide and a locking mechanism. The center distance between the driving gear shaft and the driven gear shaft can be quantitatively adjusted via the slide and the locking mechanism to change the tooth backlash between the driving gear and the driven gear. The first torque and speed sensor (3) is used to detect the torque and speed of the drive gear shaft; The second torque and speed sensor (13) is used to detect the torque and speed of the driven gear shaft; The first non-contact torque and speed sensor (5) is used to detect the time-varying torque and time-varying speed of the drive gear shaft; The second non-contact torque and speed sensor (11) is used to detect the time-varying torque and time-varying speed of the driven gear shaft; A first rotary encoder (8) is used to detect the time-varying angular displacement value of the free end of the drive gear shaft; The second rotary encoder (18) is used to detect the time-varying angular displacement value of the free end of the driven gear shaft; Eddy current sensors, including a pair, are set at a 90-degree angle at the shaft end of the drive gear shaft for observing the gyro precession trajectory of the drive gear shaft; The controller has its signal input terminal connected to the first torque speed sensor (3), the second torque speed sensor (13), the first non-contact torque speed sensor (5), the second non-contact torque speed sensor (11), the first rotary encoder (8), the second rotary encoder (18), and the eddy current sensor, and its signal output terminal connected to the drive motor. Both the driving gear and the driven gear use standard involute tooth profile gears.

2. The split-type gear test bench with variable center distance according to claim 1, characterized in that, The slide and locking mechanism include: A base plate is fixedly connected to the workbench, and a sliding rail moving pair is provided between the base plate and the bottom of the open driven gearbox; A thrust block (19) is fixed on a base plate located on one side of the driven gearbox, and a first limiting bolt is threaded onto the thrust block; The second limiting bolt is threaded onto the housing on the other side of the driven gearbox, and the non-threaded end of the second limiting bolt is in contact with the driving gearbox.

3. The split-type gear test bench with variable center distance according to claim 1, characterized in that, The load is a load servo motor, and the load servo motor is connected to the signal output terminal of the controller.

4. The split-type gear test bench with variable center distance according to claim 3, characterized in that, The drive gear shaft and the drive gearbox are rotatably connected by two first sliding bearings; a hydraulic station is provided around the worktable; The bearing lubricating oil in the hydraulic station enters the groove of the first sliding bearing seat through the oil inlet pump and the first oil inlet pipeline (23). Each first sliding bearing seat is provided with a first oil inlet flow valve at its oil inlet. The driven gear shaft and the driven gearbox are rotatably connected by two second sliding bearings; the bearing lubricating oil in the hydraulic station enters the groove of the second sliding bearing seat through the oil inlet pump and the second oil inlet pipeline respectively, and a second oil inlet flow valve is provided at the oil inlet of each second sliding bearing seat. Both the bottom of the inner wall of the open-type active gearbox and the bottom of the inner wall of the open-type active gearbox are provided with oil return grooves, and the bearing lubricating oil is recovered to the oil return grooves through the oil return pump and the oil return pipeline.

5. The method for nonlinear vibration testing of the split gear test bench with variable center distance according to claim 1, characterized in that, Including tooth flank clearance test: The tooth backlash is changed by adjusting the center distance between the gear shafts. After replacing the drive gear shaft and the driven gear shaft, the minimum center distance between them is tested first. The minimum clearance between the drive gear shaft in the open drive gearbox and the driven gear shaft in the open driven gearbox is measured by the slide table and locking mechanism with a clearance micrometer. This is the minimum center distance of the system. The test is carried out without jamming. After the stage test is completed and the system is completely stopped, the center distance between the drive gear shaft and the driven gear shaft is increased at a specific interval and the test is carried out. The test is carried out in sequence. When the center distance is increased to more than the limit distance, it is judged whether the meshing noise increases significantly. If the meshing noise increases significantly, the test of increasing the center distance is stopped.

6. The method for nonlinear vibration testing of the split gear test bench with variable center distance according to claim 4, characterized in that, The following tests are included: Step test: The test is divided into a constant torque stepped speed test and a constant speed stepped torque test. Taking the constant torque stepped speed test as an example, the center distance between the open drive gearbox and the open driven gearbox is controlled as the normal working condition. The load end is taken as no-load condition or specific torque. The drive motor (1) is started to speed up to 50 rpm and kept for 3-5 seconds until stable operation. Without turning off the drive motor (1), it is accelerated to the target maximum speed in sequence. The acceleration interval is 50 rpm each time. After reaching the target maximum speed, the load servo motor (15) and the drive motor are stopped in sequence, and the bearing lubricating oil supply is kept normal. Load test: According to the actual working conditions, the controller drives the drive motor to input the test speed and maintain it until the operation is stable. Then, the load servo motor (15) applies a specific torque in torque mode. The controller uses the speed value of the first torque speed sensor (3) and the torque value of the second torque speed sensor (13) to control the speed of the drive motor (1) and the torque of the load servo motor (15) in a closed loop, so as to stabilize them and maintain their operation for a specific period of time. After the test is completed, first turn off the torque output of the load servo motor (15), then turn off the drive motor, while maintaining the supply of bearing lubricating oil.

7. The method for nonlinear vibration testing of the split gear test bench with variable center distance according to claim 4, characterized in that, The following tests are included: No-load test: Turn off the control of the load servo motor or disconnect the flange coupling (12) between the driven gear shaft and the load, so that the entire gearbox model is running unloaded. Before running, turn on the oil inlet pump and the oil return pump. After confirming that the values ​​of the flow meter and pressure meter are stable, take a specific time to conduct the gearbox test. After the test is completed, turn off the drive motor until the drive motor stops completely while maintaining the supply of bearing lubricating oil. Uniaxial test: The slide and locking mechanism completely disengage the driving gear on the driving gear shaft from the driven gear shaft, allowing only the driving gear shaft to operate independently. Within a specific range, a specific speed is selected under the hydrodynamic lubrication condition of the sliding bearing. Based on the structural characteristics of the sliding bearing, a hydrodynamic lubrication model is calculated to maintain operation under oil film support, preventing bearing failure. After the drive motor stops, the bearing lubricating oil is supplied until the drive motor completely stops. The test data includes two parts: motor interference frequency data of the corresponding gear meshing model before stopping, and gyroscope precession path data of the driving gear shaft under hydrodynamic lubrication condition obtained by the eddy current sensor during the free travel segment after stopping. Dry friction test; Before the experiment, the oil inlet pump was turned off to supply oil to the open drive gearbox and the open driven gearbox. The gearbox spacing was set to the theoretical minimum center distance. The radial displacement data of the eddy current sensor (24) was recorded. After running for 5-10 seconds, the bearing lubricating oil supply was turned on. The oil supply pressure was set to 0.1-0.2 MPa. The oil supply flow rate of the bearing lubricating oil was set according to the value obtained from the rotor dynamics simulation software.

8. The method for nonlinear vibration testing of the split gear test bench with variable center distance according to claim 4, characterized in that, The following tests are included: Bearing lubricating oil flow rate setting test: First, select an inlet pressure of 0.1-0.2 MPa based on the dynamic viscosity of the lubricating oil, which is specifically determined by the length of the sliding bearing inlet passage and the number of inlets; The lubricating oil enters from the side wall of the sliding bearing and flows in naturally, without considering the static support of the lubricating oil pressure on the gear shaft; Dry friction test was performed with lubricating oil turned off. Radial displacement data of eddy current sensor (24) was read and the average value of motion was recorded. The oil inlet flow valve of the bearing was manually adjusted and the flow rate was increased at intervals of 0.1L / min. Radial displacement data of eddy current sensor (24) at each flow rate was analyzed until the gear shaft was completely floating in the hydrodynamic lubrication model. At this time, the average radial displacement was the smallest. The flow rate was recorded for other tests. In addition, a specific speed was selected for testing in the gear-sliding bearing coupling model. In the theoretical model, if the speed is too low, the gear shaft will never be able to float completely. It needs to be adjusted in time. The specific adjustment plan is to accelerate the test at an initial speed of 1000 rpm in 200 rpm intervals.

9. A data processing method for nonlinear vibration testing using a split-type gear test bench with variable center distance as described in any one of claims 5 to 7, comprising the conversion of rotational speed in the meshing line direction and the conversion of angular displacement in the meshing line direction. I. The conversion of angular displacement in the direction of the meshing line can be obtained first from the characteristics of the involute tooth profile: x=R bp i p -R bg i g -e(τ) (1.1) In the formula, x represents the linear displacement along the meshing line, and R represents the linear displacement along the meshing line. bp R is the base circle radius of the driving gear. bg θ is the base circle radius of the driven gear. p It is the angular displacement of the driving gear, θ g It is the angular displacement of the driven gear, and e(τ) is the comprehensive transmission error along the meshing line direction; II. The conversion of angular velocity along the line of engagement is expressed by the following formula: In the formula, x' is the linear velocity along the meshing line, and n p n is the rotational speed of the driving gear. g The rotational speed of the driven gear; III. The time-varying speed and time-varying angular displacement values ​​collected from the driving gear shaft side and the driven gear side are transformed using Equations 1.1 and 1.2 above to obtain two sets of data representing the linear displacement x and linear velocity x' along the meshing line direction, respectively. IV. Plot a phase diagram with linear velocity x' as the Y-axis data and linear displacement x as the X-axis data respectively, and take the rotation period as the cutoff to draw a Poincaré section, thereby determining whether the gear meshing system is in a chaotic state or a periodic state.

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