Digital hydraulic torque loader and closed digital hydraulic rotary loading method

Abstract

The invention discloses a digital hydraulic torque loader and a closed digital hydraulic rotary loading method.The digital hydraulic torque loader comprises a base, a rotary joint, a blade swing cylinder, a left bearing seat, a coupler, an output shaft, a right bearing seat and a servo valve, and the base is used for supporting the digital hydraulic torque loader; the left bearing seat, the right bearing seat and the rotary joint are fixedly connected to the base through bolts; the servo valve is mounted on the upper surface of the rotary joint; according to the loading method, the variable-frequency motor and the motor are regulated and controlled in real time, so that the performance test of the transmission part under the conditions of different rotating speeds and loads is completed; according to the invention, torque closed-loop control can be directly realized, an expensive electro-hydraulic servo valve does not need to be used during loading control, the cost is effectively reduced, and meanwhile, the system structure is simplified, the reliability is high, and the anti-pollution capability is very strong.

Description

Technical Field

[0001] This invention relates to the field of transmission component testing, and in particular provides a digital hydraulic torque loader and a closed-loop digital hydraulic rotary loading method. Background Technology

[0002] In mechanical systems, transmission components, as crucial mechanisms for power transmission and motion conversion, are key to determining the overall performance, efficiency, and reliability of the system. Therefore, accurate and efficient fault diagnosis of transmission components such as gears, bearings, and shafts is essential. Typically, transmission components are tested and their reliability verified using a mechanically enclosed test bench. The hydraulic torque loader is a key product providing torque to this test bench. The torque load is controlled by adjusting the pressure within the hydraulic loader. Since factors such as changes in oil temperature and load can cause pressure fluctuations, real-time adjustment of the hydraulic torque loader's pressure to maintain torque load stability is crucial.

[0003] Most existing hydraulic torque loaders use pressure regulating valves, proportional pressure control valves, and electro-hydraulic servo valves to control the loading torque. In the paper "Design of Hydraulic Loader for Fatigue Life Testing Device of Automobile Transmission Assembly" (Jiang Zhengfeng, 2006), the loading torque is adjusted by regulating the pressure of the hydraulic system through a proportional relief valve. In the paper "Design of Measurement and Control System for Fatigue Testing Bench of Hydraulic Loading Transmission" (Tan Wei, 2018), the loading torque is controlled by controlling the proportional pressure control valve through a PLC to achieve oil pressure input from the pump station to the hydraulic loader. Patent CN202010328493.7, "A Hydraulic Torque Loader," shows the use of an electro-hydraulic servo valve to achieve closed-loop control of torque loading. When high-precision loading torque is required, a closed-loop loading method using an electro-hydraulic servo valve is necessary. This loading method offers high output torque accuracy but requires expensive electro-hydraulic servo valves, has high requirements for hydraulic oil quality, high manufacturing costs, and a complex system structure. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a digital hydraulic torque loader and a closed-loop digital hydraulic rotary loading method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a digital hydraulic torque loader, comprising a base, a rotary joint, a blade oscillating cylinder, a left bearing housing, a coupling, an output shaft, a right bearing housing, and a servo valve. The base supports the digital hydraulic torque loader, and the left bearing housing, right bearing housing, and rotary joint are bolted to the base. The rotary joint includes a housing and a rotating shaft with an internal oil chamber. One end of the rotating shaft is fixedly connected to the inner ring of the bearing in the left bearing housing, and the rotating shaft is rotatable but cannot move axially relative to the left bearing housing. The other end of the rotating shaft is fixed to the blade oscillating cylinder via a flange. The blade oscillating cylinder includes a front cover, a stator housing, a rear cover, and a rotor shaft. The two openings of the stator housing are enclosed by the front cylinder cover and the rear cylinder cover, respectively. The rotor shaft is coaxially fitted together with the stator housing, forming a working cavity between them. The coupling connects the rotor shaft and the output shaft, enabling the two shafts to rotate coaxially and transmit torque. The housing of the coupling is fixedly installed on the rear cover of the blade oscillating cylinder via a flange connection. The output shaft is fixedly connected to the inner ring of the bearing in the right bearing housing, and the output shaft cannot move axially relative to the right bearing housing but can rotate.

[0007] The servo valve is mounted on the upper surface of the rotary joint housing. The servo valve includes a valve block, a spool valve core, a motor, and a gear and rack differential pressure feedback mechanism. The valve block is fixedly connected to the upper surface of the rotary joint housing. The spool valve core is inserted into the valve core mounting hole of the valve block. One end of the spool valve core is coaxially connected to the motor shaft of the motor via an adapter sleeve. The motor is fixedly connected to the valve block via a motor adapter bracket. The spool valve core is non-rotatable but axially movable relative to the adapter sleeve. The motor shaft is non-rotatable and non-axially movable relative to the adapter sleeve. The other end of the spool valve core is connected to the counter-gear and rack differential pressure feedback mechanism.

[0008] The gear and rack differential pressure feedback mechanism includes a feedback housing, a feedback screw, a gear, a rack, a feedback piston, a first thrust spring, and a second thrust spring. The feedback housing is fixedly mounted on the valve block. One end of the feedback screw is threadedly connected to the valve core to form a feedback threaded pair, and the other end is coaxially fixedly connected to the gear. The rack is fixedly mounted on the upper surface of the feedback piston through a connecting block, and the rack meshes with the gear, moving axially as the gear rotates. The feedback piston can move axially within the feedback piston mounting hole of the valve block. The first thrust spring is mounted in the feedback piston mounting hole at one end of the feedback piston. The second thrust spring is mounted in the feedback piston mounting hole at the other end of the feedback piston. A first feedback oil port is provided on the inner wall of the feedback piston mounting hole on the side where the first thrust spring is located, and a second feedback oil port is provided on the inner wall of the feedback piston mounting hole on the side where the second thrust spring is located.

[0009] Furthermore, the housing is provided with an oil inlet hole and an oil return hole; four oil chambers are evenly arranged in the circumferential direction of the rotating shaft, including a first oil inlet chamber, a second oil inlet chamber, a first oil return chamber and a second oil return chamber; the oil inlet hole is connected to the first oil inlet chamber and the second oil inlet chamber of the rotating shaft through an annular groove a, and the oil return hole is connected to the first oil return chamber and the second oil return chamber of the rotating shaft through an annular groove b.

[0010] Furthermore, the outer wall of the rotor shaft and the inner wall of the stator housing are both provided with blades, which divide the working chamber into four equal working chambers. The working chambers include a first oil inlet chamber, a second oil inlet chamber, a first oil return chamber, and a second oil return chamber. The front end cover has four oil ports with the same diameter and structure evenly opened in the circumferential direction, including a first oil inlet port, a second oil inlet port, a first oil return port, and a second oil return port.

[0011] Furthermore, the first oil inlet chamber is connected to the first oil inlet chamber via the first oil inlet port, and the second oil inlet chamber is connected to the second oil inlet chamber via the second oil inlet port; the oil return chamber is connected to the first oil return chamber via the first oil return port, and the oil return chamber is connected to the second oil return chamber via the second oil return port.

[0012] Furthermore, the servo valve is a symmetrical four-sided spool valve with a non-full-circumference opening. The servo valve has four variable throttle ports divided into two groups, and the opening areas of the two groups of variable throttle ports are the same, used to control the oil inflow and outflow of the working chamber. The valve block and the spool valve core are indirectly fitted by a valve sleeve, which is located between the valve block and the spool valve core. The valve sleeve and the valve block are in a clearance seal fit, and the valve sleeve is immovable relative to the valve block. The valve sleeve and the spool valve core are in a clearance seal fit, and the spool valve core is axially movable relative to the valve sleeve.

[0013] Furthermore, the valve block is respectively provided with an oil inlet P, an oil return port T, a first working oil port A, a second working oil port B, a first feedback oil port, and a second feedback oil port; the oil inlet P is used to connect to external high-pressure oil, and the oil return port T is connected to an external hydraulic oil tank; the first working oil port A is connected to the oil inlet of the rotary joint, and the second working oil port B is connected to the oil outlet of the rotary joint to control the inlet and outlet of the working chamber oil; the first feedback oil port is connected to the first working oil port A through an oil passage on the valve block; the second feedback oil port is connected to the second working oil port B through an oil passage on the valve block.

[0014] This invention also provides a closed-loop digital hydraulic rotary loading method, the technical solution of which is:

[0015] The mechanical enclosed test bench includes enclosed gearbox I, enclosed gearbox II, gear shaft I, gear shaft II, gear shaft III, gear shaft IV, gear shaft V, gear shaft VI, main test specimen, auxiliary test specimen, sensor, digital hydraulic torque loader, fixed support, variable frequency motor, coupling I, coupling II, coupling III, coupling IV, coupling V, coupling VI, coupling VII, and coupling VIII.

[0016] Furthermore, the enclosed gearbox I and enclosed gearbox II are two identical two-stage gearboxes. Enclosed gearbox I includes gear shaft I, gear shaft II and gear shaft III, and enclosed gearbox II includes gear shaft IV, gear shaft V and gear shaft VI.

[0017] Furthermore, the variable frequency motor is connected to the gear shaft V via coupling V, the gear shaft IV is connected to the main test piece via coupling IV, one end of the fixed support is connected to the main test piece via coupling III, and the other end of the fixed support is connected to the sensor via coupling II, thus providing fixed support for the main test piece and the sensor. The sensor is connected to the gear shaft I via coupling I. One end of the digital hydraulic torque loader is connected to the gear shaft III via coupling VIII, and the other end is connected to the auxiliary test piece via coupling VII. The auxiliary test piece is connected to the gear shaft VI via coupling VI, forming a closed loop. The variable frequency motor inputs the rotational speed to the mechanically enclosed test bench, and the output power of the variable frequency motor is only used to supplement the friction loss in the closed loop.

[0018] Furthermore, one end of the digital hydraulic torque loader is connected to the gear shaft III via coupling VIII, and the other end is connected to the test specimen via coupling VII. When the digital hydraulic torque loader is working, the two ends of the loader output a pair of torques of the same magnitude but opposite direction, which are transmitted through closed gearbox I and closed gearbox II to apply a load to the main test specimen.

[0019] The beneficial effects of this invention are:

[0020] The digital hydraulic torque loader and closed-loop digital hydraulic rotary loading method of the present invention can directly realize torque closed-loop control, that is, the output torque of the torque loader has a strict linear proportional relationship with the motor shaft rotation angle, accurately providing loading torque. When performing loading control, there is no need to use expensive electro-hydraulic servo valves, which effectively reduces costs. At the same time, it simplifies the system structure, increases reliability, and has strong anti-pollution ability. Attached Figure Description

[0021] Figure 1 This is a top view of a digital hydraulic torque loader according to the present invention;

[0022] Figure 2 yes Figure 1 Sectional view of AA;

[0023] Figure 3 yes Figure 2 A magnified view of part I;

[0024] Figure 4 This is a schematic diagram (partial cross-section) of a gear and rack differential pressure feedback mechanism.

[0025] Figure 5 This is a top view of the rotary joint;

[0026] Figure 6 This is a diagram showing the distribution of the oil inlet chamber of the rotary joint;

[0027] Figure 7 This is a diagram showing the distribution of the return oil chamber of the rotary joint;

[0028] Figure 8 This is a schematic diagram of the internal structure of the swing cylinder;

[0029] Figure 9 This is a structural schematic diagram of a mechanically enclosed test bench;

[0030] Figures 1-9In the middle, 1-base, 2-left bearing housing, 3-rotary joint, 4-servo valve, 5-vane swing cylinder, 6-bearing housing, 7-right bearing housing, 8-output shaft, 9-housing, 10-rotating shaft, 11-front end cover, 12-stator housing, 13-rear end cover, 14-rotor shaft, 15-working chamber, 16-outer shell, 17-motor, 18-slide valve core, 19-valve block, 20-gear rack differential pressure feedback mechanism, 21-motor shaft, 22-motor adapter frame, 23-... - Feedback threaded pair, 24- Gear, 25- Feedback screw, 26- Rack, 27- Feedback housing, 28- Connecting block, 29- Valve sleeve, 30- Adapter sleeve, 31- Feedback piston, 32- First thrust spring, 33- Second thrust spring, 34- First feedback block oil port, 35- Second feedback block oil port, 36- Oil inlet, 37- Oil return hole, 38- Annular groove a, 39- Annular groove b, 40- First oil inlet chamber, 41- Second oil inlet chamber, 42- First oil return hole 43-Second oil return chamber, 44-First oil inlet chamber, 45-Second oil inlet chamber, 46-First oil return chamber, 47-Second oil return chamber, 48-First oil inlet, 49-Second oil inlet, 50-First oil return port, 51-Second oil return port, 52-Oil inlet P, 53-Oil return port T, 54-First working oil port A, 55-Second working oil port B, 56-Enclosed gearbox I, 57-Coupling I, 58-Sensor, 59-Coupling II, 60-Fixed Support components, 61-Coupling III, 62-Main test piece, 63-Coupling IV, 64-Enclosed gearbox II, 65-Gear shaft IV, 66-Gear shaft V, 67-Coupling V, 68-Variable frequency motor, 69-Gear shaft VI, 70-Coupling VI, 71-Supplementary test piece, 72-Coupling VII, 73-Digital hydraulic torque loader, 74-Coupling VIII, 75-Gear shaft III, 76-Gear shaft II, 77-Gear shaft I. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] Figures 1-8As shown, a digital hydraulic torque loader 73 includes a base 1, a rotary joint 3, a vane swing cylinder 5, a left bearing housing 2, a coupling 6, an output shaft 8, a right bearing housing 7, and a servo valve 4. The base 1 supports the digital hydraulic torque loader 73. The left bearing housing 2, the right bearing housing 7, and the rotary joint 3 are bolted to the base 1. The rotary joint 3 includes a housing 9 and a rotating shaft 10 with an internal oil chamber. One end of the rotating shaft 10 is fixed to the inner ring of the bearing in the left bearing housing 2. The rotating shaft 10 cannot move axially relative to the left bearing housing 2 but can rotate. The other end of the rotating shaft 10 is fixed to the front of the vane swing cylinder 5 via a flange. The blade swing cylinder 5 includes a front cover 11, a stator housing 12, a rear cover 13, and a rotor shaft 14. The two openings of the stator housing 12 are encapsulated by a front cylinder cover and a rear cylinder cover, respectively. The rotor shaft 14 is coaxially fitted with the stator housing 12, forming a working cavity 15 between them. The coupling 6 connects the rotor shaft 14 and the output shaft 8, enabling the two shafts to rotate coaxially and transmit torque. The outer shell 16 of the coupling 6 is fixedly installed on the rear cover 13 of the blade swing cylinder 5 via a flange connection. The output shaft 8 is fixedly connected to the inner ring of the bearing in the right bearing seat 7. The output shaft 8 cannot move axially relative to the right bearing seat 7 but can rotate.

[0034] The servo valve 4 is mounted on the upper surface of the housing 9 of the rotary joint 3. The servo valve 4 includes a valve block 19, a spool valve core 18, a motor 17, and a gear rack differential pressure feedback mechanism 20. The valve block 19 is fixedly connected to the upper surface of the housing 9 of the rotary joint 3. The spool valve core 18 is inserted into the valve core mounting hole of the valve block 19. One end of the spool valve core 18 is coaxially connected to the motor shaft 21 of the motor 17 through an adapter sleeve 30. The motor 17 is fixedly connected to the valve block 19 through a motor adapter bracket 22. The spool valve core 18 is not rotatable relative to the adapter sleeve 30 but can move axially. The motor shaft 21 of the motor 17 is not rotatable and cannot move axially relative to the adapter sleeve 30. The other end of the spool valve core 18 is connected to the gear rack differential pressure feedback mechanism 20.

[0035] The gear and rack differential pressure feedback mechanism 20 includes a feedback housing, a feedback screw 25, a gear 24, a rack 26, a feedback piston 31, a first thrust spring 32, and a second thrust spring 33. The feedback housing is fixedly mounted on the valve block 19. One end of the feedback screw 25 is threadedly connected to the valve core to form a feedback threaded pair 23, and the other end is coaxially fixedly connected to the gear 24. The rack 26 is fixedly mounted on the upper surface of the feedback piston 31 through a connecting block 28, and the rack 26 meshes with the gear 24. The rack 26 moves with the gear 24. The feedback piston 31 can rotate and move axially; the feedback piston 31 can move axially within the feedback piston 31 mounting hole of the valve block 19; the first thrust spring 32 is installed in the feedback piston mounting hole at one end of the feedback piston 31; the second thrust spring 33 is installed in the feedback piston mounting hole at the other end of the feedback piston 31; a first feedback oil port 34 is provided on the inner wall of the feedback piston mounting hole on the side where the first thrust spring 32 is located, and a second feedback oil port 35 is provided on the inner wall of the feedback piston mounting hole on the side where the second thrust spring 33 is located.

[0036] The housing 9 is provided with an oil inlet hole 36 and an oil inlet hole 37; the rotating shaft 10 is provided with four oil chambers evenly arranged in the circumferential direction, including a first oil inlet chamber 40, a second oil inlet chamber 41, a first oil return chamber 42 and a second oil return chamber 43; the oil inlet hole 36 is connected to the first oil inlet chamber 40 and the second oil inlet chamber 41 of the rotating shaft 10 through an annular groove a 38, and the oil inlet hole 37 is connected to the first oil return chamber 42 and the second oil return chamber 43 of the rotating shaft 10 through an annular groove b 39.

[0037] Both the outer wall of the rotor shaft 14 and the inner wall of the stator housing 12 are provided with blades, which divide the working chamber 15 into four equal working chambers. The working chambers include a first oil inlet chamber 44, a second oil inlet chamber 45, a first oil return chamber 46, and a second oil return chamber 47. The front end cover 11 has four oil ports with the same diameter and structure evenly opened in the circumferential direction, including a first oil inlet 48, a second oil inlet 49, a first oil return port 50, and a second oil return port 51.

[0038] The first oil inlet chamber 40 is connected to the first oil inlet chamber 44 through the first oil inlet port 48, and the second oil inlet chamber 41 is connected to the second oil inlet chamber 45 through the second oil inlet port 49; the first oil return chamber 42 is connected to the first oil return chamber 46 through the first oil return port 50, and the second oil return chamber 43 is connected to the second oil return chamber 47 through the second oil return port 51.

[0039] The servo valve 4 is a symmetrical four-sided spool valve with a non-full circumferential opening. The servo valve 4 has four variable throttle ports divided into two groups, and the opening areas of the two groups of variable throttle ports are the same, used to control the oil inlet and outlet of the working chamber 15. The valve block 19 and the spool valve core 18 are indirectly fitted by a valve sleeve 29. The valve sleeve 29 is located between the valve block 19 and the spool valve core 18, and the valve sleeve 29 and the valve block 19 are in a clearance seal fit. The valve sleeve 29 is immovable relative to the valve block 19. The valve sleeve 29 and the spool valve core 18 are in a clearance seal fit, and the spool valve core 18 is axially movable relative to the valve sleeve 29.

[0040] The valve block 19 is provided with an oil inlet P 52, an oil return port T 53, a first working oil port A 54, a second working oil port B 55, a first feedback oil port 34, and a second feedback oil port 35. The oil inlet P 52 is used to connect to external high-pressure oil, and the oil return port T 53 is connected to an external hydraulic oil tank. The first working oil port A 54 is connected to the oil inlet 36 of the rotary joint 3, and the second working oil port B 55 is connected to the oil outlet of the rotary joint 3, controlling the inlet and outlet of the oil in the working chamber 15. The first feedback oil port 34 is connected to the first working oil port A 54 through an oil passage on the valve block 19. The second feedback oil port 35 is connected to the second working oil port B 55 through an oil passage on the valve block 19.

[0041] It should be noted that: in this embodiment, the oil inlet hole 36, the first oil inlet chamber 40, the second oil inlet chamber 41, the first oil inlet chamber 44, the second oil inlet chamber 45, the first oil inlet port 48, and the second oil inlet port 49 can also serve as the oil return hole 37, the first oil return chamber 42, the second oil return chamber 43, the first oil return chamber 46, the second oil return chamber 47, the first oil return port 50, and the second oil return port 51 to realize the return of oil. Conversely, the oil return hole 37, the first oil return chamber 42, the second oil return chamber 43, the first oil return chamber 46, the second oil return chamber 47, the first oil return port 50, and the second oil return port 51 can also serve as the oil inlet hole 36, the first oil inlet chamber 40, the second oil inlet chamber 41, the first oil inlet chamber 44, the second oil inlet chamber 45, the first oil inlet port 48, and the second oil inlet port 49 to realize the entry of oil. Therefore, the terms "in" and "out" are not limited to the name.

[0042] Example 2

[0043] Figure 9As shown, the mechanical enclosed test bench includes enclosed gearbox I 56, enclosed gearbox II 64, gear shaft I 77, gear shaft II 76, gear shaft III 75, gear shaft IV 65, gear shaft V 66, gear shaft VI 69, main test piece 62, auxiliary test piece 71, sensor 58, digital hydraulic torque loader 73, fixed support 60, variable frequency motor 68, coupling I 57, coupling II 59, coupling III 61, coupling IV 63, coupling V 67, coupling VI 70, coupling VII 72, and coupling VIII 74.

[0044] The enclosed gearbox I 56 and enclosed gearbox II 64 are two identical two-stage gearboxes. Enclosed gearbox I 56 includes gear shaft I 77, gear shaft II 76 and gear shaft III 75, and enclosed gearbox II 64 includes gear shaft IV 65, gear shaft V 66 and gear shaft VI 69.

[0045] The variable frequency motor 68 is connected to the gear shaft V 66 via coupling V 67. The gear shaft IV 65 is connected to the main test piece 65 via coupling IV 63. One end of the fixed support 60 is connected to the main test piece 65 via coupling III 61, and the other end of the fixed support 60 is connected to the sensor 58 via coupling II 59, providing fixed support for the main test piece 65 and the sensor 58. The sensor 58 is connected to the gear shaft I 77 via coupling I 57. One end of the digital hydraulic torque loader 73 is connected to the gear shaft III 75 via coupling VIII 74, and the other end is connected to the auxiliary test piece 71 via coupling VII 72. The auxiliary test piece 71 is connected to the gear shaft VI 69 via coupling VI 70, forming a closed loop. The variable frequency motor 68 inputs the rotational speed to the mechanically enclosed test bench, and the output power of the variable frequency motor 68 is only used to supplement the friction loss of the closed loop.

[0046] One end of the digital hydraulic torque loader 73 is connected to the gear shaft III 75 via coupling VIII 74, and the other end is connected to the test specimen 71 via coupling VII 72. When the digital hydraulic torque loader 73 is working, the two ends of the loader output a pair of torques of the same magnitude but opposite direction, which are transmitted to the main test specimen 65 through the closed gearbox I 56 and the closed gearbox II 64.

[0047] The following description, with reference to the accompanying diagram, illustrates one operation of the digital hydraulic torque loader:

[0048] An electrical signal is input to motor 17, causing motor shaft 21 of motor 17 to rotate by a certain angle. Motor shaft 21 drives the spool valve core 18 of servo valve 4 to rotate by a certain angle through adapter sleeve 30. Due to the threaded connection between spool valve core 18 and feedback screw 25, the rotational motion of spool valve core 18 is converted into axial displacement under the action of feedback thread pair 23. The throttle port opens, and external high-pressure oil enters the first working oil port A 54 through oil inlet P 52. Part of the oil in the first working oil port A 54 enters the feedback piston mounting hole where the first thrust spring 32 is located through the first feedback oil port 34. The other part of the oil in the first working oil port A 54 enters the oil inlet 36 and then passes through the annular groove a. Oil 38 enters the first oil inlet chamber 40 and the second oil inlet chamber 41 simultaneously. Oil from the first oil inlet chamber 40 enters the first oil inlet chamber 44 through the first oil inlet 48, while oil from the second oil inlet chamber 41 enters the second oil inlet chamber 45 through the second oil inlet 49. That is, oil enters both the first and second oil inlet chambers simultaneously. As the amount of oil in the first and second oil inlet chambers 44 and 45 increases, their volume increases, and the pressure in the inlet chambers rises. Meanwhile, the amount of oil in the first return oil chamber 46 and the second return oil chamber 47 decreases, and their volume decreases. As the pressure in the return oil chamber decreases, the pressure difference between the inlet and return oil chambers creates a pair of equal and opposite loading torques. These loading torques apply load through the output shaft 8 and the rotor shaft 14. At this time, the oil in the first inlet chamber 44 enters the annular groove b sequentially through the first return oil port 50 and the first return oil chamber 42. Simultaneously, the oil in the second inlet chamber 45 also enters the annular groove b sequentially through the second return oil port 51 and the second return oil chamber 43. The oil entering the annular groove b enters the second working oil port B 55 through the return oil hole 37. A portion of the oil entering the second working oil port B 55 returns to the external hydraulic oil tank through the return oil port T 53, while the other portion of the oil entering the second working oil port B 55 enters the feedback piston mounting hole where the second thrust spring 33 is located through the second feedback oil port 35.Because the pressure in the inlet chamber is higher than the pressure in the return chamber, the pressure in the feedback piston mounting hole where the first thrust spring 32 is located is higher than the pressure in the feedback piston mounting hole where the second thrust spring 33 is located. The pressure difference between the two sides of the feedback piston 31 is the load pressure. Under the action of the load pressure, the feedback piston 31 will be pushed towards the oil port 35 of the second feedback block. At the same time, the second thrust spring 33 will be compressed. At this time, the rack 26 will move synchronously with the feedback piston 31 and drive the gear 24 meshing with it to rotate, thereby driving the feedback screw 25 to rotate synchronously. Because there is a threaded connection between the spool valve core 18 and the feedback screw 25, Under the action of the feedback threaded pair 23, the rotational motion of the feedback screw 25 is converted into the linear motion of the spool valve core 18. At this time, the direction of the linear motion of the spool valve core 18 is opposite to the direction of the motor 17's drive. This continues until the spool valve core 18 returns to the neutral position, and the throttle port of the servo valve 4 closes. At this point, a stable pressure difference, i.e., a stable load torque, is formed between the inlet and return oil chambers. In other words, the load torque of the digital hydraulic torque loader 73 has a strictly linear proportional relationship with the rotation angle of the motor shaft 21 of the motor 17; that is, the larger the rotation angle of the motor shaft 21 of the motor 17, the larger the load torque of the digital hydraulic torque loader 73.

[0049] The specific steps of the closed-loop digital hydraulic rotary loading method are illustrated in the attached diagram:

[0050] 1) Connect one end of the main test piece 62 to be tested to the gear shaft IV 65 via coupling IV 63, and connect the other end of the main test piece 62 to the fixed support 60 via coupling III 61; at the same time, connect one end of the auxiliary test piece 71 to the digital hydraulic torque loader 73 via coupling VII 72, and connect the other end of the auxiliary test piece 71 to the gear shaft VI 69 via coupling VI 70;

[0051] 2) Start the variable frequency motor 68 and adjust the drive speed as required. Under the action of the variable frequency motor 68, the speed passes sequentially through coupling V 67, gear shaft V 66, gear shaft IV 65, coupling IV 63, main test piece 62, coupling III 61, fixed support 60, coupling II 59, sensor 58, coupling I 57, gear shaft I 77, gear shaft II 76, gear shaft III 75, coupling VIII 74, digital hydraulic torque loader 73, coupling VII 72, auxiliary test piece 71, coupling VI 70, gear shaft VI 69, and finally returns to gear shaft V 66. The variable frequency motor 68 inputs the speed into the closed transmission circuit formed by the entire transmission system, driving the main test piece and related transmission components to rotate and reach the required speed.

[0052] 3) After the operation is stable, the motor 17 is adjusted to make the digital hydraulic torque loader 73 output a pair of equal and opposite torques. At this time, the torque at one end of the digital hydraulic torque loader 73 is applied to one end of the main test piece 62 through coupling VIII 74, gear shaft III 75, gear shaft II 76, gear shaft I 77, coupling I 57, sensor 58, coupling II 59, fixed support 60, and coupling III 61 in sequence. At the same time, the equal and opposite torque at the other end of the digital hydraulic torque loader 73 is applied to the other end of the main test piece 62 through coupling VII 72, auxiliary test piece 71, coupling VI 70, gear shaft VI 69, gear shaft IV 65, coupling IV 63, and main test piece 62 in sequence, thus applying a pair of equal and opposite torques to the main test piece 62.

[0053] 4) The speed and torque of sensor 58 are monitored in real time. When the relative error is greater than the set value, the variable frequency motor 68 and motor 17 are adjusted in real time. The main test piece 62 can be tested under different speed and load conditions.

[0054] The solutions described in the embodiments are not intended to limit the scope of patent protection of this invention. All equivalent implementations or modifications that do not depart from the scope of this invention are included in the patent scope of this case.

Claims

1. A digital hydraulic torque loader characterized by: The mechanism comprises a base, a rotary joint, a vane swing cylinder, a left bearing seat, a shaft coupling, an output shaft, a right bearing seat and a servo valve; the base is used for supporting the digital hydraulic torque loader, the left bearing seat, the right bearing seat and the rotary joint are fixed on the base by bolts; the rotary joint comprises a shell, a rotary shaft provided in the shell and having an oil cavity, one end of the rotary shaft is fixedly connected with an inner ring of the bearing of the left bearing seat, the rotary shaft is not axially movable but rotatable relative to the left bearing seat; the other end of the rotary shaft is fixedly connected with a front end cover of the vane swing cylinder through a flange; the vane swing cylinder comprises a front end cover, a stator shell, a rear end cover and a rotor shaft, two cylinder mouths of the stator shell are respectively sealed by the front end cover and the rear end cover; the rotor shaft is coaxially sleeved with the stator shell and forms a working cavity with the stator shell; the shaft coupling is connected with the rotor shaft and the output shaft to make the two shafts coaxially rotate and transmit torque; the shell of the shaft coupling is fixedly installed on the rear end cover of the vane swing cylinder through a flange; the output shaft is fixedly connected with an inner ring of the bearing of the right bearing seat, the output shaft is not axially movable but rotatable relative to the right bearing seat; the servo valve is installed on the upper surface of the shell of the rotary joint, the servo valve comprises a valve block, a spool valve core, a motor and a gear rack and pinion pressure difference feedback mechanism; the valve block is fixedly connected with the upper surface of the shell of the rotary joint, the spool valve core is inserted into a valve core mounting hole of the valve block, one end of the spool valve core is coaxially connected with a motor shaft of the motor through an adapter sleeve, the motor is fixedly connected with the valve block through a motor adapter frame, the spool valve core is not rotatable but axially movable relative to the adapter sleeve, the motor shaft of the motor is not rotatable and axially movable relative to the adapter sleeve; the other end of the spool valve core is connected with the gear rack and pinion pressure difference feedback mechanism; the gear rack and pinion pressure difference feedback mechanism comprises a feedback shell, a feedback screw rod, a gear, a rack, a feedback piston, a first thrust spring and a second thrust spring; the feedback shell is fixedly installed on the valve block; one end of the feedback screw rod is threadedly connected with the valve core to form a feedback threaded pair, the other end of the feedback screw rod is coaxially fixedly connected with the gear; the rack is fixedly installed on the upper surface of the feedback piston through a connecting block, the rack is engaged with the gear, and the rack moves axially with the rotation of the gear; the feedback piston is axially movable in a feedback piston mounting hole of the valve block; the first thrust spring is installed in the feedback piston mounting hole at one end of the feedback piston; the second thrust spring is installed in the feedback piston mounting hole at the other end of the feedback piston; a first feedback oil port is formed in the inner wall of the feedback piston mounting hole on the side where the first thrust spring is located, and a second feedback oil port is formed in the inner wall of the feedback piston mounting hole on the side where the second thrust spring is located; the stator shell is provided with an oil inlet hole and an oil return hole; four oil cavities are uniformly arranged in the circumferential direction of the rotary shaft, including a first oil inlet cavity, a second oil inlet cavity, a first oil return cavity and a second oil return cavity; the oil inlet hole is connected with the first oil inlet cavity and the second oil inlet cavity of the rotary shaft through an annular groove a, and the oil return hole is connected with the first oil return cavity and the second oil return cavity of the rotary shaft through an annular groove b.The rotor shaft outer wall and the stator shell inner wall are provided with blades, the blades separate the working cavity into four equal working chambers, the working chambers include a first oil inlet chamber, a second oil inlet chamber, a first oil return chamber and a second oil return chamber; four oil ports with the same aperture and structure are uniformly arranged on the front end cover in the circumferential direction, including a first oil inlet port, a second oil inlet port, a first oil return port and a second oil return port; the first oil inlet cavity is communicated with the first oil inlet chamber through the first oil inlet port, and the second oil inlet cavity is communicated with the second oil inlet chamber through the second oil inlet port; the oil return cavity is communicated with the first oil return chamber through the first oil return port, and the oil return cavity is communicated with the second oil return chamber through the second oil return port.

2. A digital hydraulic torque load simulator according to claim 1, characterized in that: The servo valve is a symmetrical four-edge spool valve adopting a non-full-circle opening form; the servo valve has four variable throttles and is divided into two groups, and the opening areas of the two groups of variable throttles are the same, which are used for controlling the oil liquid in and out of the working chamber; the valve sleeve is arranged between the valve block and the spool valve core for indirect cooperation, the gap sealing cooperation is formed between the valve sleeve and the valve block, and the valve sleeve is not movable relative to the valve block; the gap sealing cooperation is formed between the valve sleeve and the spool valve core, and the spool valve core is axially movable relative to the valve sleeve; the valve block is respectively provided with an oil inlet P, an oil return port T, a first working oil port A, a second working oil port B, a first feedback oil port and a second feedback oil port; the oil inlet P is used for connecting external high-pressure oil liquid, and the oil return port T is connected with an external hydraulic oil tank; the first working oil port A is connected with an oil inlet hole of a rotary joint in communication, the second working oil port B is connected with an oil outlet hole of the rotary joint in communication, and the first and second working oil ports are used for controlling the oil liquid in and out of the working chamber; the first feedback oil port is connected with the first working oil port A through an oil channel on the valve block; and the second feedback oil port is connected with the second working oil port B through an oil channel on the valve block.

3. A closed-loop digital hydraulic rotary loading method, characterized by: The mechanical closed test bench comprises a closed gear box I, a closed gear box II, a gear shaft I, a gear shaft II, a gear shaft III, a gear shaft IV, a gear shaft V, a gear shaft VI, a main test piece, an accompanying test piece, a sensor, a digital hydraulic torque loader, a fixed support, a variable frequency motor, a shaft coupling I, a shaft coupling II, a shaft coupling III, a shaft coupling IV, a shaft coupling V, a shaft coupling VI, a shaft coupling VII and a shaft coupling VIII. The closed gear box I and the closed gear box II are two identical secondary gear boxes. The closed gear box I comprises the gear shaft I, the gear shaft II and the gear shaft III. The closed gear box II comprises the gear shaft IV, the gear shaft V and the gear shaft VI. The variable frequency motor is connected with the gear shaft V through the shaft coupling V. The gear shaft IV is connected with the main test piece through the shaft coupling IV. One end of the fixed support is connected with the main test piece through the shaft coupling III. The other end of the fixed support is connected with the sensor through the shaft coupling II. The sensor is connected with the gear shaft I through the shaft coupling I. One end of the digital hydraulic torque loader is connected with the gear shaft III through the shaft coupling VIII. The other end of the digital hydraulic torque loader is connected with the accompanying test piece through the shaft coupling VII. The accompanying test piece is connected with the gear shaft VI through the shaft coupling VI. A closed loop is formed. The variable frequency motor inputs the rotating speed of the mechanical closed test bench. The output power of the variable frequency motor is only used for supplementing the friction loss in the closed loop. One end of the digital hydraulic torque loader is connected with the gear shaft III through the shaft coupling VIII. The other end of the digital hydraulic torque loader is connected with the accompanying test piece through the shaft coupling VII. When the digital hydraulic torque loader works, a pair of torques with the same size and opposite directions are output at both ends of the loader. The torques are transmitted through the closed gear box I and the closed gear box II to exert a load on the main test piece.

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