Paddle pitch changing mechanism of wind driven generator

Abstract

The invention relates to the technical field of wind driven generators, and discloses a wind driven generator paddle variable pitch mechanism which comprises a main tower body and a cabin, the cabin is rotationally arranged at the top of the main tower body, a supporting beam is arranged in the cabin, the supporting beam is sleeved with a supporting cylinder, and the supporting cylinder is rotationally sleeved with a cylindrical rotating shaft. The cylindrical rotating shaft is provided with a plurality of fan blades capable of changing pitch automatically, a hydraulic cylinder for driving the fan blades to rotate in a pitch-variable mode is arranged in the cabin, a hydraulic pump station for driving the hydraulic cylinder is arranged at the tail of the cabin, an equipment cabin is arranged in the supporting cylinder, a self-centering reversing valve is arranged in the equipment cabin in a sliding mode, and a linkage assembly for connecting the self-centering reversing valve and the cover plate is arranged in the equipment cabin. Compared with the prior art, the device has the advantages that electronic elements are not needed, electronic faults are avoided, the device is not influenced by eddy current generated by fan blades of a generator, the judgment on the wind speed is more accurate, the device can automatically return to the center to lock a hydraulic driving structure, and an additional brake structure is not needed.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbines, and specifically refers to a blade pitch-changing mechanism for a wind turbine. Background Art

[0002] The pitch-changing system of a wind turbine is a system in which the wind turbine blades installed on the hub change the pitch angle with the help of control technology and a power system to change the aerodynamic characteristics of the blades. Near the rated wind speed, the system adjusts the pitch angle at any time according to the wind speed change, controls the absorbed mechanical energy, ensures the acquisition of the maximum energy (corresponding to the rated power), and reduces the impact of the wind on the wind turbine.

[0003] The existing blade pitch-changing mechanism can refer to CN101555871A, a variable pitch and variable speed wind power generation unit. This mechanism realizes pitch change by the transmission of multiple motors and gears installed in the fan blade hub, causing the fan blade to rotate around its own installation axis. After the pitch change is completed, the fan blade is locked by a braking device to maintain the pitch. This pitch-changing method relies on a complex electronic control system to control the pitch-changing motor and the brake. Moreover, since the motor is installed in the fan blade hub and needs to rotate with the hub during power generation, this pitch-changing device requires a complex electronic control device and electrical connection. In the high-humidity and high-salt environment of offshore wind power generation, the above electronic components and electrical circuits are extremely prone to corrosion and damage.

[0004] The conventional wind speed sensor of a wind turbine is installed above the tail of the generator housing. During the operation of the generator, since its fan blades need to rotate, the moving fan blades will generate eddy currents behind their movement trajectories. After the eddy currents are superimposed on the airflow that pushes the fan blades, they will deflect towards the tail of the generator, interfering with the wind speed sensor and making the perception of the wind speed inaccurate. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing pitch-changing system of a wind turbine is difficult to adapt to the environment of offshore wind power generation and the wind speed perception is inaccurate. The present invention provides a blade pitch-changing mechanism for a wind turbine.

[0006] To solve the above technical problem, the technical solution provided by the present invention is: a blade pitch-changing mechanism for a wind turbine, which includes a main tower body and a nacelle. The nacelle is rotatably arranged on the top of the main tower body. A support beam is arranged inside the nacelle. The support beam sleeves a support cylinder. A cylindrical rotating shaft is rotatably sleeved outside the support cylinder. The cylindrical rotating shaft is provided with a plurality of fan blades that can rotate and change pitch by themselves. A rotating shaft cover is rotatably sleeved outside the cylindrical rotating shaft. A hydraulic cylinder for driving the fan blades to rotate and change pitch is arranged inside the nacelle, and a hydraulic pump station for driving the hydraulic cylinder is arranged at the tail of the nacelle.

[0007] The support cylinder is provided with an equipment cabin. An automatically centering reversing valve is slidably arranged in the equipment cabin. An air inlet cone is arranged at the end of the support beam. Air inlets are arranged on both sides of the air inlet cone. Air flow channels are arranged on both sides of the support cylinder. A cover plate that can be turned up and down is hinged at the connection between the air inlet and the air flow channel. A linkage assembly for connecting the automatically centering reversing valve and the cover plate is arranged in the equipment cabin.

[0008] Furthermore, a valve core with horizontal sliding displacement is arranged inside the automatically centering reversing valve. An air inlet cavity, a flow regulating cavity, a return cavity, an outlet cavity, and an oil supply cavity are sequentially arranged inside the automatically centering reversing valve from the end to the center. The above-mentioned respective cavities are symmetrically arranged on both sides of the automatically centering reversing valve. The flow regulating cavity is arranged in a conical shape. The return cavity and the oil supply cavity are cylindrical with equal cross-sections. The outlet cavity is cylindrical with a cross-section larger than that of the return cavity and the oil supply cavity. An oil supply pipeline is arranged at the top of the flow regulating cavity, bypassing the return cavity and the outlet cavity and communicating with the oil supply cavity. The bottom of the automatically centering reversing valve is provided with an oil pump interface, an oil tank interface, a first hydraulic cylinder interface, and a second hydraulic cylinder interface. Among them, the oil pump interface communicates with the air inlet cavity, the oil tank interface communicates with the return cavity, and the first hydraulic cylinder interface and the second hydraulic cylinder interface respectively communicate with the outlet cavities on both sides of the automatically centering reversing valve. The oil pump interface is connected to the outlet hose of the oil pump of the hydraulic pump station through a hose, the oil tank interface is connected to the oil tank hose of the hydraulic pump station through a hose, and the first hydraulic cylinder interface and the second hydraulic cylinder interface are respectively connected to the two ends of the hydraulic cylinder through hose connections.

[0009] Furthermore, tapered plugs are arranged at both ends of the valve core. Columnar plugs are arranged on both sides in the middle of the valve core. The ends of the tapered plugs move inside the flow regulating cavity, and the roots keep the flow regulating cavity and the return cavity isolated and sealed. The columnar plugs are cylindrical with a cross-section equal to that of the return cavity and the oil supply cavity and a horizontal length equal to that of the outlet cavity, and move directly at both ends of the outlet cavity, and can seal the outlet cavity and the oil supply cavity or the outlet cavity and the return cavity. A connecting rod is arranged at the end of the tapered plug, passing through the shells at both ends of the automatically centering reversing valve and extending to the outside.

[0010] Furthermore, a first guide rod is arranged at the bottom of the equipment cabin. The automatically centering reversing valve is slidably connected to the first guide rod. A damper is arranged at the top of the equipment cabin. The free end of the damper is connected to the top of the automatically centering reversing valve. A lever is arranged at the bottom of the equipment cabin. A first chute is arranged at the top of the lever, and a second chute is arranged at the bottom. The distance between the first chute and the center of rotation of the lever is greater than that of the second chute. The connecting rod is slidably connected to the second chute.

[0011] Furthermore, a second guide rod is arranged at the top of the equipment cabin. A slider is slidably connected to the second guide rod. The slider is slidably connected to the first chute. Push rods are slidably arranged on both sides of the equipment cabin. The push rods move between the equipment cabin above the air flow channel. The two ends of the push rod are respectively hinged to a first connecting rod and a second connecting rod. The end of the first connecting rod is hinged to the cover plate, and the second connecting rod is hinged to both sides of the slider.

[0012] Further, an adjustable distance sliding sleeve is sleeved outside the cylindrical rotating shaft. A first hinge ring is arranged at the end of the adjustable distance sliding sleeve close to the fan blade side, and a first sliding ring is rotatably arranged at the other end. A second sliding ring is rotatably sleeved outside the adjustable distance sliding sleeve, and the end of the second sliding ring is rotatably connected to a second hinge ring.

[0013] Further, a third guiding rod is arranged inside the engine nacelle. The hydraulic cylinder is slidably arranged on the third guiding rod. The cylinder body of the hydraulic cylinder is connected to the first sliding ring, and the free end of the hydraulic cylinder is connected to the second sliding ring.

[0014] Further, an annular lever is fixedly sleeved at the bottom of the fan blade. A first pitch adjusting rod is hinged on one side of the annular lever, and a second pitch adjusting rod is hinged on the other side. The end of the first pitch adjusting rod is hingedly connected to the first hinge ring, and the second pitch adjusting rod is hingedly connected to the second hinge ring.

[0015] Further, a gearbox is arranged at the root of the support cylinder. A gear and a toothed ring that mesh with each other are arranged inside the gearbox. The toothed ring is power-connected to the cylindrical rotating shaft, and the gear is power-connected to a transmission shaft.

[0016] Further, a speed increaser and a power generation module are arranged at the tail of the engine nacelle. The input end of the speed increaser is power-connected to the transmission shaft, and the output end is power-connected to the power generation module.

[0017] Compared with the prior art, the advantages of the present invention are as follows:

[0018] For a high-humidity and high-salt environment, such as offshore wind power generation, the variable pitch system as a whole requires fewer electronic components, and electronic failures are avoided to the greatest extent.

[0019] The intake of the intake cone is not affected by the eddy current generated by the generator fan blade, and the judgment of the wind speed is more accurate.

[0020] The reversing valve that controls the variable pitch mechanism can automatically return to the middle position. After returning to the middle position, the hydraulic drive structure is locked and the adjusted pitch is maintained, without an additional braking structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of the present invention.

[0022] Figure 2 is an exploded structural diagram of the cylindrical rotating shaft of the present invention.

[0023] Figure 3 is a schematic structural diagram of the engine nacelle of the present invention.

[0024] Figure 4 is Figure 3 the structural schematic diagram at a in

[0025] Figure 5 is a schematic diagram when the pitch of the present invention is reduced.

[0026] Figure 6 This is a schematic structural diagram when the pitch of the present invention increases.

[0027] Figure 7 This is a schematic structural diagram of the intake cone of the present invention.

[0028] Figure 8 This is a schematic structural diagram of the equipment cabin of the present invention.

[0029] Figure 9 It is Figure 8 a schematic structural diagram at position b in

[0030] Figure 10 This is a schematic structural diagram of the air inlet of the present invention.

[0031] Figure 11 This is a schematic structural diagram of the self-centering reversing valve of the present invention.

[0032] Figure 12 This is a schematic internal structural diagram of the self-centering reversing valve of the present invention.

[0033] Figure 13 This is a schematic structural diagram of the self-centering reversing valve after the valve position is changed in the present invention.

[0034] As shown in the figure: 1. Main tower body, 2. Machine cabin, 3. Rotating shaft cover, 4. Fan blade, 5. Intake cone, 6. Cylindrical rotating shaft, 7. Support beam, 8. Support cylinder, 9. Support plate, 10. Bearing, 11. Air inlet, 12. Air flow channel, 13. Hydraulic pump station, 14. Power generation module, 15. Speed increaser, 16. Transmission shaft, 17. Gearbox, 18. Gear, 19. Tooth ring, 20. Ring-shaped lever, 21. First pitch adjustment rod, 22. Second pitch adjustment rod, 23. Pitch adjustment sliding sleeve, 24. First hinge ring, 25. Second hinge ring, 26. First sliding ring, 27. Second sliding ring, 28. Third guide rod, 29. Hydraulic cylinder, 30. Equipment cabin, 31. Cover plate, 32. Push rod, 33. First connecting rod, 34. Second guide rod, 35. Slide block, 36. Second connecting rod, 37. First guide rod, 38. Self-centering reversing valve, 39. Damper, 40. Connecting rod, 41. Lever, 42. First chute, 43. Second chute, 45. Oil pump interface, 46. Oil tank interface, 47. First hydraulic cylinder interface, 48. Second hydraulic cylinder interface, 49. Inlet cavity, 50. Flow regulation cavity, 51. Oil supply pipeline, 52. Oil supply cavity, 53. Outlet cavity, 54. Return cavity, 55. Valve core, 56. Conical plug, 57. Cylindrical plug. Detailed implementation manners

[0035] The present invention will be further described in detail below with reference to the accompanying drawings.

[0036] Combined with the attached Figure 1 and the attached Figure 2 and the attachedFigure 3 and the attached Figure 4 , a pitch-changing mechanism for a wind turbine blade, which includes a main tower body 1 and a nacelle 2. A bearing 10 is arranged in the nacelle 2 and rotatably connected to the top of the main tower body 1. A support beam 7 is arranged inside the nacelle 2. The support beam 7 is sleeved with a support cylinder 8. A cylindrical rotating shaft 6 is rotatably sleeved outside the support cylinder 8. The cylindrical rotating shaft 6 is provided with a plurality of fan blades 4 that can rotate and change pitch by themselves. A rotating shaft cover 3 is rotatably sleeved outside the cylindrical rotating shaft 6. A hydraulic cylinder 29 for driving the fan blades 4 to rotate and change pitch is arranged in the nacelle 2. A gearbox 17 is arranged at the root of the support cylinder 8. A gear 18 and a toothed ring 19 that mesh with each other are arranged in the gearbox 17. The toothed ring 19 is power-connected to the cylindrical rotating shaft 6. The gear 18 is power-connected to a transmission shaft 16. A support plate 9 is arranged at the tail of the nacelle 2. A speed increaser 15, a power generation module 14 and a hydraulic pump station 13 for driving the hydraulic cylinder 29 are arranged on the support plate 9. The input end of the speed increaser 15 is power-connected to the transmission shaft 16, and the output end is power-connected to the power generation module 14.

[0037] Combined with the attached Figure 5 and the attached Figure 6 , an adjustable pitch sliding sleeve 23 is sleeved outside the cylindrical rotating shaft 6. A first hinge ring 24 is arranged at the end of the adjustable pitch sliding sleeve 23 close to the fan blade 4, and a first sliding ring 26 is rotatably arranged at the other end. A second sliding ring 27 is rotatably sleeved outside the adjustable pitch sliding sleeve 23. The end of the second sliding ring 27 is rotatably connected to a second hinge ring 25. A third guide rod 28 is arranged inside the nacelle 2. The hydraulic cylinder 29 is slidably arranged on the third guide rod 28. The cylinder body of the hydraulic cylinder 29 is connected to the first sliding ring 26, and the free end of the hydraulic cylinder 29 is connected to the second sliding ring 27. An annular lever 20 is fixedly sleeved at the bottom of the fan blade 4. A first pitch-adjusting rod 21 is hinged on one side of the annular lever 20, and a second pitch-adjusting rod 22 is hinged on the other end. The end of the first pitch-adjusting rod 21 is hinged and connected to the first hinge ring 24, and the second pitch-adjusting rod 22 is hinged and connected to the second hinge ring 25.

[0038] By adjusting the telescopic length of the free end of the hydraulic cylinder 29, the distance between the first hinge ring 24 and the second hinge ring 25 can be changed. By pulling and pushing the annular lever 20 through the first pitch-adjusting rod 21 and the second pitch-adjusting rod 22, the fan blade 4 can be rotated to change the pitch around its root. In summary, the above structure realizes the control of the pitch of the wind turbine fan blade 4 by controlling the hydraulic cylinder 29.

[0039] When the wind turbine works and the fan blades rotate, the first pitch-adjusting rod 21 and the second pitch-adjusting rod 22 pull the first hinge ring 24 and the second hinge ring 25 to rotate synchronously. Since the first sliding ring 26 and the second sliding ring 27 are rotatably connected, the rotation of the fan blades can be decoupled, so that the hydraulic cylinder 29 can also maintain the adjustment and control of the pitch of the fan blade 4 when the fan blades rotate.

[0040] Combined with the attached Figure 7 , the attached Figure 8 and the attached Figure 9, an equipment cabin 30 is provided inside the support cylinder 8. A self-centering reversing valve 38 is slidably arranged inside the equipment cabin 30. An air inlet cone 5 is arranged at the end of the support beam 7. Air inlets 11 are arranged on both sides of the air inlet cone 5. Air flow channels 12 are arranged on both sides of the support cylinder 8. A cover plate 31 that can be turned up and down is hinged at the connection between the air inlet 11 and the air flow channel 12. A linkage assembly for connecting the self-centering reversing valve 38 and the cover plate 31 is provided inside the equipment cabin 30.

[0041] Combined with attached Figure 11 , attached Figure 12 and attached Figure 13 , a valve core 55 with a horizontal sliding displacement is provided inside the self-centering reversing valve 38. An inlet cavity 49, a flow regulation cavity 50, a return cavity 54, an outlet cavity 53, and an oil supply cavity 52 are sequentially arranged inside the self-centering reversing valve 38 from the end to the center. The above-mentioned respective cavities are symmetrically arranged on both sides of the self-centering reversing valve 38. The flow regulation cavity 50 is arranged in a conical shape. The return cavity 54 and the oil supply cavity 52 are cylindrical with equal cross-sections. The outlet cavity 53 is a cylindrical shape with a cross-section larger than that of the return cavity 54 and the oil supply cavity 52. An oil supply pipeline 51 is arranged at the top of the flow regulation cavity 50, bypassing the return cavity 54 and the outlet cavity 53 and communicating with the oil supply cavity 52. An oil pump interface 45, an oil tank interface 46, a first hydraulic cylinder interface 47, and a second hydraulic cylinder interface 48 are provided at the bottom of the self-centering reversing valve 38. Among them, the oil pump interface 45 communicates with the inlet cavity 49, the oil tank interface 46 communicates with the return cavity 54, and the first hydraulic cylinder interface 47 and the second hydraulic cylinder interface 48 respectively communicate with the outlet cavities 53 on both sides of the self-centering reversing valve 38. The oil pump interface 45 is connected to the oil pump outlet hose of the hydraulic pump station 13, the oil tank interface 46 is connected to the oil tank hose of the hydraulic pump station 13, and the first hydraulic cylinder interface 47 and the second hydraulic cylinder interface 48 are respectively connected to the two-end interface hoses of the hydraulic cylinder 29.

[0042] Combined with attached Figure 12 and attached Figure 13 , conical plugs 56 are provided at both ends of the valve core 55. Columnar plugs 57 are arranged on both sides in the middle of the valve core 55. The ends of the conical plugs 56 move inside the flow regulation cavity 50, and the roots keep the flow regulation cavity 50 and the return cavity 54 isolated and sealed. The columnar plugs 57 are cylindrical with a cross-section equal to that of the return cavity 54 and the oil supply cavity 52, and a horizontal length equal to that of the outlet cavity 53, and directly move at both ends of the outlet cavity 53, and can seal the outlet cavity 53 and the oil supply cavity 52 or the outlet cavity 53 and the return cavity 54. A connecting rod 40 is provided at the end of the conical plug 56, passing through the housing at both ends of the self-centering reversing valve 38 and extending to the outside.

[0043] Combined with attached Figure 12 and attached Figure 13 , taking the direction shown in the figure as a reference, among which Figure 12 the valve core 55 shown is in the middle position, and Figure 13 the valve core 55 shown is in the pitch lifting valve position.

[0044] When the spool 55 is in the middle position, the spool 55 seals both sides of the outlet chamber 53, and the hydraulic oil inside the self-centering reversing valve 38 cannot flow freely. The hydraulic oil at both ends of the hydraulic cylinder 29 is sealed in the outlet chamber 53 and the corresponding pipelines, so that the free end of the hydraulic cylinder 29 is locked, and the pitch of the fan blade 4 is maintained unchanged. The hydraulic pump station 13 relieves pressure and circulates through its own pipeline.

[0045] When the spool 55 is in the pitch increasing valve position, the hydraulic oil output by the hydraulic pump station 13 enters the inlet chamber 49, passes through the gap between the conical plug 56 and the flow regulating chamber 50 and enters the oil supply pipeline 51, and finally reaches the oil supply chamber 52. Figure 13 Taking the direction shown as the reference, the right side of the oil supply chamber 52 is sealed by the cylindrical plug 57, and the left side is connected to the outlet chamber 53. In this state, the hydraulic oil enters the outlet chamber 53 and is discharged from the first hydraulic cylinder interface 47 to the hydraulic cylinder 29 to push its free end to contract, increasing the pitch of the fan blade 4. The hydraulic oil on the other side of the hydraulic cylinder 29 enters the outlet chamber 53 on the right side of the oil supply chamber 52. Here, the outlet chamber 53 is connected to the return chamber 54, and the hydraulic oil enters the return chamber 54 and returns to the oil tank of the hydraulic pump station 13 through the oil tank interface 46 to complete the cycle.

[0046] When the spool 55 is in the pitch decreasing valve position, the position of the spool 55 in the self-centering reversing valve 38 is opposite to the position shown Figure 13 and the flow direction of the hydraulic oil is also opposite, so that the hydraulic oil enters the hydraulic cylinder 29 to push its free end to extend, reducing the pitch of the fan blade 4.

[0047] Combined with Fig. Figure 8 and Fig. Figure 9 , a first guide rod 37 is provided at the bottom of the equipment cabin 30, and the self-centering reversing valve 38 is slidably connected to the first guide rod 37. A damper 39 is provided at the top of the equipment cabin 30, and the free end of the damper 39 is connected to the top of the self-centering reversing valve 38. A lever 41 is provided at the bottom of the equipment cabin 30. A first chute 42 is provided at the top of the lever 41, and a second chute 43 is provided at the bottom. The distance between the first chute 42 and the rotation circle of the lever 41 is greater than that of the second chute 43. The connecting rod 40 is slidably connected to the second chute 43. A second guide rod 34 is provided at the top of the equipment cabin 30. A slider 35 is slidably connected to the second guide rod 34, and the slider 35 is slidably connected to the first chute 42. Push rods 32 are slidably provided on both sides of the equipment cabin 30. The push rods 32 move between the equipment cabin 30 above the air flow channel 12. Both ends of the push rods 32 are respectively hinged to the first connecting rod 33 and the second connecting rod 36. The end of the first connecting rod 33 is hinged to the cover plate 31, and the second connecting rod 36 is hinged to both sides of the slider 35.

[0048] The air inlet 11 is in a converging shape from the outside to the inside. After the external air flow enters, its speed continuously increases, enhancing the dynamic pressure of the air flow when blowing the cover plate 31 to turn it up. After the cover plate 31 turns upward, it drives the slider 35 to move through the above structure, and the slider 35 then changes the position of the valve core 55 through the lever 41.

[0049] Taking the Figure 10 indicated direction as the reference, when the wind speed increases, the turning angle of the cover plate 31 becomes larger, the slider 35 moves to the left, so that the lever 41 pulls the valve core 55 to move to the right, making the self-centering reversing valve 38 in the pitch increasing valve position.

[0050] When the wind speed decreases, the turning angle of the cover plate 31 becomes smaller, the slider 35 moves to the right, so that the lever 41 pulls the valve core 55 to move to the left, making the self-centering reversing valve 38 in the pitch decreasing valve position.

[0051] When the valve core 55 is in the pitch increasing valve position or the pitch decreasing valve position, the flow cross-sectional areas formed between the two conical plugs 56 and the flow regulation chamber 50 are not equal. Taking Figure 13 as an example, the flow cross-sectional area in the left flow regulation chamber 50 is smaller than that on the right, making the pressures in the two flow regulation chambers 50 unequal. The hydraulic oil pressure difference on both sides will generate a force on the self-centering reversing valve 38 and the valve core 55 to make the two move relatively back to the middle position.

[0052] The position of the valve core 55 is traction-controlled by the cover plate 31 and the corresponding linkage components. Among them, the lever arm between the rotation axis of the lever 41 and the valve core 55 is significantly smaller than the lever arm between the lever 41 and the slider 35. Therefore, the valve core 55 pushing the slider 35 through the lever 41 is a laborious lever. The hydraulic oil pressure difference needs to be much greater than the dynamic pressure of the external air flow applied to the cover plate 31 to make the valve core 55 move back to the middle position.

[0053] The self-centering reversing valve 38 is freely slidably arranged at the bottom of the equipment cabin 30, and its movement is only provided with relative damping by the damper 39. When the hydraulic oil pressure difference is greater than the damping of the damper 39, the valve body of the self-centering reversing valve 38 can be pushed to move to the middle position.

[0054] As can be seen from the above, by selecting a damper 39 with an appropriate damping value so that the damping it provides is less than the thrust applied to the slider 35 by the dynamic pressure of the air flow on the cover plate 31, it can be realized that after the cover plate 31 and the valve core 55 move due to the wind speed change, the self-centering reversing valve 38 moves to the middle position without changing the position.

[0055] On the contrary, when the external wind speed changes, the magnitude of the dynamic pressure of the air flow received by the cover plate 31 changes, and the turning amplitude of the cover plate 31 changes to make the slider 35 move. Since the lever 41 is a labor-saving lever relative to the slider 35, the cover plate 31 only needs to apply a relatively small thrust to the slider 35 to change the position of the valve core 55, thereby adjusting the pitch.

[0056] The greater the change in wind speed, the greater the movement distance of the spool 55. The self-centering reversing valve 38 can remain at the pitch increasing valve position or the pitch decreasing valve position for a longer time, making the pitch change amplitude positively correlated with the wind speed change amplitude.

[0057] In summary, when the external wind speed changes, the above mechanism controls the fan blade 4 to change the pitch according to the magnitude of the wind speed change and automatically brakes to maintain the adjusted pitch.

[0058] The above describes the present invention and its implementation manners. This description is not restrictive, and the actual structure is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and, without departing from the purpose of the present invention creation, design similar structural manners and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A wind turbine blade pitch-changing mechanism, comprising a main tower (1) and a nacelle (2), wherein the nacelle (2) is rotatably arranged on the top of the main tower (1), a support beam (7) is arranged inside the nacelle (2), a support cylinder (8) is sleeved on the support beam (7), the support cylinder (8) is rotatably sleeved on the outside of a cylindrical rotating shaft (6), the cylindrical rotating shaft (6) is provided with a plurality of blades (4) capable of automatically changing pitch, a rotating shaft cover (3) is rotatably sleeved on the outside of the cylindrical rotating shaft (6), a hydraulic cylinder (29) for driving the blades (4) to change pitch and rotate is arranged inside the nacelle (2), and a hydraulic pump station (13) for driving the hydraulic cylinder (29) is arranged at the rear of the nacelle (2), characterized in that: An equipment cabin (30) is provided in the support tube (8), a self-centering reversing valve (38) is slidably provided in the equipment cabin (30), an air intake cone (5) is provided at the end of the support beam (7), air intake ports (11) are provided on both sides of the air intake cone (5), air flow channels (12) are provided on both sides of the support tube (8), a cover plate (31) that can be turned upside down is hingedly provided at the connection point between the air intake port (11) and the air flow channel (12), a linkage assembly that connects the self-centering reversing valve (38) and the cover plate (31) is provided in the equipment cabin (30), the cover plate (31) turns upside down to change the connection direction of the oil path in the self-centering reversing valve (38) through the linkage assembly, and the connection direction of the oil path in the self-centering reversing valve (38) controls the extension or retraction of the hydraulic cylinder (29), thereby adjusting the pitch angle of the fan blade (4).

2. The wind turbine blade pitch changing mechanism according to claim 1, characterized in that: The self-returning reversing valve (38) is provided with a valve core (55) capable of horizontal sliding displacement. The self-returning reversing valve (38) is provided with an inlet chamber (49), a flow regulating chamber (50), a reflux chamber (54), an outlet chamber (53) and an oil supply chamber (52) in sequence from the end to the center. The above chambers are symmetrically arranged inside the self-returning reversing valve (38). The flow regulating chamber (50) is arranged in a conical shape. The reflux chamber (54) and the oil supply chamber (52) are cylindrical shapes with equal cross-sections. The outlet chamber (53) is cylindrical with a cross-section larger than that of the reflux chamber (54) and the oil supply chamber (52). An oil supply pipeline (51) is provided at the top of the flow regulating chamber (50) to bypass the reflux chamber (54) and the outlet chamber (53) and connect to the oil supply chamber (52). The bottom of the self-returning reversing valve (38) is provided with an oil pump interface (45), an oil tank interface (46), a first hydraulic cylinder interface (47) and a second hydraulic cylinder interface (48), wherein the oil pump interface (45) is connected to the inlet chamber (49), the oil tank interface (46) is connected to the reflux chamber (54), the first hydraulic cylinder interface (47) and the second hydraulic cylinder interface (48) are respectively connected to the outlet chambers (53) on both sides of the self-returning reversing valve (38), the oil pump interface (45) is connected to the oil pump outlet hose of the hydraulic pump station (13), the oil tank interface (46) is connected to the oil tank hose of the hydraulic pump station (13), and the first hydraulic cylinder interface (47) and the second hydraulic cylinder interface (48) are respectively connected to the interface hoses at both ends of the hydraulic cylinder (29).

3. The wind turbine blade pitch changing mechanism according to claim 2, characterized in that: Conical plugs (56) are provided at both ends of the valve core (55), and cylindrical plugs (57) are provided at both sides of the middle of the valve core (55). The ends of the conical plug (56) move in the flow regulating chamber (50), and the root portion keeps the flow regulating chamber (50) and the reflux chamber (54) isolated and sealed. The cylindrical plug (57) is a cylindrical shape with a cross section equal to that of the reflux chamber (54) and the oil supply chamber (52), and a horizontal length equal to that of the outlet chamber (53). It moves directly at both ends of the outlet chamber (53) to seal the outlet chamber (53) and the oil supply chamber (52), or the outlet chamber (53) and the reflux chamber (54). The ends of the conical plug (56) are provided with connecting rods (40) that pass through the housings of the self-centering reversing valve (38) at both ends and extend to the outside.

4. The wind turbine blade pitch changing mechanism according to claim 3 is characterized in that: A first guide rod (37) is provided at the bottom of the equipment cabin (30), the self-centering reversing valve (38) is slidably connected to the first guide rod (37), a damper (39) is provided at the top of the equipment cabin (30), the free end of the damper (39) is connected to the top of the self-centering reversing valve (38), a lever (41) is provided at the bottom of the equipment cabin (30), a first slide groove (42) is provided at the top of the lever (41), and a second slide groove (43) is provided at the bottom, the circular rotation distance between the first slide groove (42) and the lever (41) is greater than the second slide groove (43), and the connecting rod (40) is slidably connected to the second slide groove (43).

5. The wind turbine blade pitch changing mechanism according to claim 4, characterized in that: A second guide rod (34) is provided on the top of the equipment cabin (30), and a slider (35) is slidably connected to the second guide rod (34). The slider (35) is slidably connected to the first slide groove (42). Push rods (32) are slidably provided on both sides of the equipment cabin (30). The push rods (32) move between the equipment cabin (30) and the air flow channel (12). The two ends of the push rod (32) are respectively hingedly connected to the first connecting rod (33) and the second connecting rod (36). The end of the first connecting rod (33) is hingedly connected to the cover plate (31), and the second connecting rod (36) is hingedly connected to both sides of the slider (35).

6. The wind turbine blade pitch changing mechanism according to claim 1, characterized in that: The cylindrical rotating shaft (6) is externally sleeved with a pitch-adjustable sliding sleeve (23); a first hinged ring (24) is provided at the end of the pitch-adjustable sliding sleeve (23) on one side close to the fan blade (4); a first slip ring (26) is rotatably provided at the other end; a second slip ring (27) is rotatably sleeved on the outside of the pitch-adjustable sliding sleeve (23); and an end of the second slip ring (27) is rotatably connected to a second hinged ring (25).

7. The wind turbine blade pitch changing mechanism according to claim 6, characterized in that: A third guide rod (28) is arranged inside the cabin (2), a hydraulic cylinder (29) is slidably arranged on the third guide rod (28), a cylinder body of the hydraulic cylinder (29) is connected to the first slip ring (26), and a free end of the hydraulic cylinder (29) is connected to the second slip ring (27).

8. The wind turbine blade pitch changing mechanism according to claim 6, characterized in that: The bottom of the fan blade (4) is fixedly sleeved with an annular lever (20); a first pitch-adjusting rod (21) is hingedly provided on one side of the annular lever (20); a second pitch-adjusting rod (22) is hingedly connected to the other end; a distal end of the first pitch-adjusting rod (21) is hingedly connected to a first hinge ring (24); and the second pitch-adjusting rod (22) is hingedly connected to a second hinge ring (25).

9. The wind turbine blade pitch changing mechanism according to claim 1, characterized in that: The support cylinder (8) is provided with a gear box (17) at the root thereof. The gear box (17) is provided with a gear (18) and a gear ring (19) meshing with each other. The gear ring (19) is dynamically connected to the cylindrical rotating shaft (6), and the gear (18) is dynamically connected to a transmission shaft (16).

10. The wind turbine blade pitch changing mechanism according to claim 9, characterized in that: A speed increaser (15) and a power generation module (14) are provided at the rear of the nacelle (2); an input end of the speed increaser (15) is power-connected to a transmission shaft (16), and an output end is power-connected to the power generation module (14).

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