An integrated hydraulic pitch control system

Abstract

The present invention discloses an integrated hydraulic pitch control system, relating to the technical field of wind turbine pitch control. The system comprises a push-pull dual pitch control cylinder group, a high-pressure accumulator group, a low-pressure accumulator group, a proportional reversing valve, a return oil power conversion system, and an auxiliary system. The system comprises a first oil cylinder and a second oil cylinder. The output port of the high-pressure accumulator group is connected to the P port of the proportional reversing valve. The A port of the proportional reversing valve is connected to the rod chamber of the first oil cylinder and the rodless chamber of the second oil cylinder through the return oil power conversion system. The B port of the proportional reversing valve is connected to the rodless chamber of the first oil cylinder and the rod chamber of the second oil cylinder through the return oil power conversion system. The T port of the proportional reversing valve is connected to the low-pressure accumulator group, which is connected to the high-pressure accumulator group via the auxiliary system. By eliminating the hydraulic station and liquid slip ring originally arranged in the nacelle, the system can be integrated into the wheel hub, significantly reducing the number of pipelines.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine pitch control, and in particular to an integrated hydraulic pitch control system. Background Art

[0002] Hydraulic pitch control systems typically use a hydraulic station as the power source and hydraulic oil as the transmission medium. This system converts the push-pull force of the cylinder piston rod into pitch torque that rotates the blades, achieving wind turbine pitch control. Currently, hydraulic pitch control systems used in wind turbines employ a split-type layout, with the hydraulic cylinder and valve assembly located within the turbine hub and the hydraulic station within the turbine nacelle, connected via piping and liquid slip rings.

[0003] The split-type variable pitch system has the disadvantages of complicated assembly and debugging, large layout space, long oil circuit, many joints, many fault points, and constant maintenance. Summary of the Invention

[0004] The object of the present invention is to provide an integrated hydraulic pitch system to address the above-mentioned problems, integrate the entire hydraulic pitch system into one, eliminate the hydraulic station and liquid slip ring originally arranged in the cabin, so that it can be installed in the hub and greatly reduce the number of pipelines.

[0005] The technical solution adopted in the present invention is as follows:

[0006] An integrated hydraulic pitch system includes a push-pull double pitch cylinder group, a high-pressure accumulator group, a low-pressure accumulator group, a proportional reversing valve, a return oil power conversion system and an auxiliary system. The push-pull double pitch cylinder group includes a first oil cylinder and a second oil cylinder arranged in forward and reverse directions; the output port of the high-pressure accumulator group is connected to the P port of the proportional reversing valve, the A port of the proportional reversing valve is connected to the rod chamber of the first oil cylinder and the rodless chamber of the second oil cylinder respectively through the return oil power conversion system, the B port of the proportional reversing valve is connected to the rodless chamber of the first oil cylinder and the rod chamber of the second oil cylinder respectively through the return oil power conversion system, the T port of the proportional reversing valve is connected to the low-pressure accumulator group, the low-pressure accumulator group is connected to the high-pressure accumulator group through the auxiliary system, and the auxiliary system includes a replenishing oil pump.

[0007] Optionally, the return oil power conversion system includes a first group of pipelines connecting the A port of the proportional reversing valve with the rod chamber of the first oil cylinder and the rodless chamber of the second oil cylinder respectively, a second group of pipelines connecting the B port of the proportional reversing valve with the rodless chamber of the first oil cylinder and the rod chamber of the second oil cylinder respectively, and a return oil pipeline.

[0008] Optionally, the oil return pipeline includes a first oil return pipeline connected from the rod chamber of the second oil cylinder to the first group of pipelines and a second oil return pipeline connected from the rod chamber of the first oil cylinder to the second group of pipelines.

[0009] Optionally, the first group of pipelines is in one-way communication with the rod chamber of the first oil cylinder; and the second group of pipelines is in one-way communication with the rod chamber of the second oil cylinder.

[0010] Optionally, a first solenoid valve is provided on the first oil return pipeline, and a second solenoid valve is provided on the second oil return pipeline.

[0011] Optionally, the first solenoid valve is a second normally open solenoid valve; and the second solenoid valve is a second normally closed solenoid valve.

[0012] Optionally, the high-pressure accumulator group includes a high-pressure accumulator, a first normally closed solenoid valve and a first normally open solenoid valve, the output port of the high-pressure accumulator is connected to the P port of the proportional reversing valve through the first normally closed solenoid valve, and the output port of the high-pressure accumulator is also connected to the return oil power conversion system through the first normally open solenoid valve.

[0013] Optionally, the proportional reversing valve is a three-position four-way solenoid valve, and the middle position function of the proportional reversing valve is J-type or Y-type.

[0014] Alternatively, port A of the proportional reversing valve is connected to the first group of pipelines through a third normally closed solenoid valve.

[0015] Optionally, the low-pressure accumulator group is connected to the high-pressure accumulator group in one-way communication.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0017] 1. The integrated hydraulic pitch control system disclosed in the present invention adopts an integrated system design, eliminating the liquid slip ring and hydraulic station in the nacelle and integrating the entire pitch control system into the hub. A low-pressure accumulator group replaces the oil tank to avoid the risk of oil leakage from the oil storage device when the wind rotor rotates. The high-pressure accumulator group serves as the main energy source for the pitch control action, and the auxiliary system's supplementary oil pump serves as a supplementary energy source. When the pressure of the high-pressure accumulator group falls below the set value, the supplementary oil pump starts to supply the hydraulic oil in the low-pressure accumulator group to the high-pressure accumulator group, significantly reducing the number of times the supplementary oil pump starts and stops, improving the reliability of the supplementary oil pump and reducing system energy consumption.

[0018] 2. The integrated hydraulic pitch control system disclosed in the present invention, regardless of whether the propellers are in the open or feathering state, the hydraulic oil in the rodless chamber or the rod chamber of one of the oil cylinders is directly replenished to the pitch drive oil circuit through the return oil pipeline, reducing the oil supply of the high-pressure accumulator and the oil replenishment of the replenishing oil pump during the pitch control process, greatly reducing the number of starts and stops of the replenishing oil pump, improving the reliability of the replenishing oil pump, and reducing the system workload and energy consumption; and the return oil pipeline does not need to pass through the proportional reversing valve, and directly enters the system circulation to participate in the pitch control operation, reducing the internal pressure loss and energy loss of the system, improving the system reliability, reducing the required system size under the same load, and saving the system installation space;

[0019] 3. The integrated hydraulic variable pitch system disclosed in the present invention can perform emergency propeller feathering in the emergency shutdown condition of the entire system being powered off, and the energy stored in the high-pressure accumulator can meet the emergency propeller feathering requirements when the power is lost. No other energy storage device is required. The high-pressure accumulator is directly connected to the return oil power conversion system, thereby greatly reducing the number of failure points and pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

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

[0022] Figure 2 It is a principle diagram of embodiment 1 of the present invention;

[0023] Figure 3 This is a schematic diagram of the second embodiment of the present invention.

[0024] Markings in the figure: 1-push-pull double pitch cylinder group, 11-first oil cylinder, 12-second oil cylinder, 2-high-pressure accumulator group, 21-high-pressure accumulator, 22-first normally closed solenoid valve, 23-first normally open solenoid valve, 3-low-pressure accumulator group, 4-proportional reversing valve, 5-return oil power conversion system, 51-first group of pipelines, 52-second group of pipelines, 53-first return oil pipeline, 54-second return oil pipeline, 55-second normally open solenoid valve, 56-second normally closed solenoid valve, 57-third normally closed solenoid valve, 6-auxiliary system, 61-supplementary oil pump. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings.

[0026] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0027] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0028] An integrated hydraulic pitch system, such as Figure 1-3 As shown, it includes a push-pull double-pitch cylinder group 1, a high-pressure accumulator group 2, a low-pressure accumulator group 3, a proportional reversing valve 4, a return oil power conversion system 5 and an auxiliary system 6. The push-pull double-pitch cylinder group 1 includes a first oil cylinder 11 and a second oil cylinder 12 arranged in forward and reverse directions; the output port of the high-pressure accumulator group 2 is connected to the P port of the proportional reversing valve 4, and the A port of the proportional reversing valve 4 is respectively connected to the rod chamber of the first oil cylinder 11 and the rodless chamber of the second oil cylinder 12 through the return oil power conversion system 5. The B port of the proportional reversing valve 4 is respectively connected to the rodless chamber of the first oil cylinder 11 and the rod chamber of the second oil cylinder 12 through the return oil power conversion system 5. The T port of the proportional reversing valve 4 is connected to the low-pressure accumulator group 3, and the low-pressure accumulator group 3 is connected to the high-pressure accumulator group 2 through the auxiliary system 6. The auxiliary system 6 includes a replenishing oil pump 61.

[0029] Among them, the push-pull double pitch cylinder group 1 adopts a forward and reverse arrangement. When the system is working, the hydraulic oil will simultaneously enter the rodless cavity of one cylinder and the rod cavity of the other cylinder, so that the working directions of the two cylinders are opposite, that is, when the rod of the first cylinder 11 is extended, the rod of the second cylinder 12 is retracted, and vice versa, when the rod of the second cylinder 12 is extended, the rod of the first cylinder 11 is retracted; the high-pressure accumulator group 2 is the main power module, which is the main power source for the pitch action, and ensures that the supplementary oil pump 61 does not need to be started regardless of whether the blades are in the open or feathered state, greatly reducing the number of start-stop times of the supplementary oil pump 61, improving the system response speed, and reducing the system energy consumption; the low-pressure accumulator group 3 is an oil storage module, which replaces the oil tank function in the traditional hydraulic pitch system and stores the amount of hydraulic oil discharged from the entire system; the proportional reversing valve 4 is the reversing module of the system, which controls the flow and direction of the hydraulic oil in the system by adopting the forward and reverse arrangement of the first The oil cylinder 11 and the second oil cylinder 12 realize the working needs of the fan to feather or open the blades through the reversing of the proportional reversing valve 4; the return oil power conversion system 5 is an energy-saving module of the system, which directly distributes the hydraulic oil in the rod chamber of the oil cylinder back to the pitch drive oil circuit during the operation of the system, reduces the oil supply of the high-pressure accumulator group 2 and the oil intake of the low-pressure accumulator group 3 during the pitch change process, and reduces the system workload. Furthermore, the return oil power conversion system 5 can make the hydraulic oil in the rod chamber of the extended oil cylinder or the rodless chamber of the retracted oil cylinder flow into the return oil power conversion system 5 in the open or feather state to directly provide replenishment for the pitch drive oil circuit, and the hydraulic oil in the retracted chamber of the other oil cylinder flows into the low-pressure accumulator group 3 for storage; the auxiliary system 6 provides energy replenishment for the high-pressure accumulator 21 and ensures the reliability of the system operation. Furthermore, the auxiliary system 6 can also include a filtering system, a heat exchange system, etc.

[0030] As another specific embodiment, the oil return power conversion system 5 includes a first set of pipes 51 connecting the A port of the proportional reversing valve 4 to the rod chamber of the first oil cylinder 11 and the rodless chamber of the second oil cylinder 12, respectively; a second set of pipes 52 connecting the B port of the proportional reversing valve 4 to the rodless chamber of the first oil cylinder 11 and the rod chamber of the second oil cylinder 12, respectively; and an oil return pipe. The hydraulic oil in the rod chamber of the extending oil cylinder or the rodless chamber of the retracting oil cylinder can flow into the first set of pipes 51 or the second set of pipes 52 through the oil return pipe, thereby directly replenishing the pitch drive oil circuit without passing through the proportional reversing valve 4, reducing the oil supply of the high-pressure accumulator group 2, the oil replenishment of the replenishing oil pump 61, and the oil flow through the proportional reversing valve 4, reducing the internal pressure loss and energy loss of the system, reducing the required system size under the same load, and improving the system reliability.

[0031] As another specific embodiment, the oil return line includes a first oil return line 53 connecting the rod chamber of the second oil cylinder 12 to the first set of pipes 51, and a second oil return line 54 connecting the rod chamber of the first oil cylinder 11 to the second set of pipes 52. In the propeller-switching or feathering state, the hydraulic oil in the rod chamber of one of the oil cylinders directly replenishes the pitch drive oil circuit, reducing the oil supply to the high-pressure accumulator 21 and the oil replenishment amount of the replenishment pump 61 during the pitch control process.

[0032] As another specific embodiment, the first set of pipes 51 is unidirectionally connected to the rod chamber of the first cylinder 11, and the second set of pipes 52 is unidirectionally connected to the rod chamber of the second cylinder 12. This unidirectional flow prevents the hydraulic oil in the rod chamber of a cylinder from flowing into the proportional reversing valve 4 when the rod of the cylinder is extended. Specifically, when the second cylinder 12 is extended, the hydraulic oil in the rod chamber of the second cylinder 12 can only flow to the first set of pipes 51 through the first return oil pipe 53. When the first cylinder 11 is extended, the hydraulic oil in the rod chamber of the first cylinder 11 can only flow to the second set of pipes 52 through the second return oil pipe 54.

[0033] As another specific embodiment, a first solenoid valve is provided on the first oil return line 53, and a second solenoid valve is provided on the second oil return line 54. The first and second solenoid valves can be opened and closed as needed. The first solenoid valve ensures that when the second oil cylinder 12 is retracted, hydraulic oil does not flow from the second set of pipes 52 into the second oil cylinder 12 and then flow along the first oil return line 53 to the first set of pipes 51. The second solenoid valve ensures that when the first oil cylinder 11 is retracted, hydraulic oil does not flow from the first set of pipes 51 into the first oil cylinder 11 and then flow along the second oil return line 54 to the second set of pipes 52.

[0034] In another specific embodiment, the first solenoid valve is a second normally open solenoid valve 55, and the second solenoid valve is a second normally closed solenoid valve 56. In an emergency shutdown condition where the entire system loses power, the first cylinder 11 retracts and the second cylinder 12 extends, thereby achieving emergency feathering. The second normally closed solenoid valve 56 prevents hydraulic oil from flowing from the first set of pipes 51 into the first cylinder 11 and then flowing along the second return oil line 54 to the second set of pipes 52.

[0035] In another specific embodiment, the high-pressure accumulator assembly 2 includes a high-pressure accumulator 21, a first normally closed solenoid valve 22, and a first normally open solenoid valve 23. The output port of the high-pressure accumulator 21 communicates with port P of the proportional reversing valve 4 via the first normally closed solenoid valve 22. The output port of the high-pressure accumulator 21 also communicates with the return oil power conversion system 5 via the first normally open solenoid valve 23. In an emergency shutdown condition where the entire system loses power, the output port of the high-pressure accumulator 21 can be directly connected to the return oil power conversion system 5, thereby enabling emergency feathering without the need for additional energy storage devices, reducing points of failure, and conserving system installation space. Furthermore, when the first cylinder 11 retracts and the second cylinder 12 extends to feather, the output port of the high-pressure accumulator 21 connects to the rod chamber of the first cylinder 11 and the rodless chamber of the second cylinder 12, respectively, through the return oil power conversion system 5, enabling emergency feathering.

[0036] As another specific embodiment, the low-pressure accumulator group 3 is connected to the high-pressure accumulator group 2 in a one-way manner.

[0037] Two specific embodiments are provided below based on the configuration of the proportional reversing valve 4 to further illustrate the integrated hydraulic pitch control system provided by the present invention.

[0038] Example 1

[0039] As an optional embodiment of the present invention, the proportional reversing valve 4 is a three-position, four-way solenoid valve, and the neutral position function of the proportional reversing valve 4 is J-type or Y-type. Furthermore, in this embodiment, the neutral position function of the proportional reversing valve 4 is J-type. In an emergency shutdown condition where the entire system loses power, the hydraulic oil flowing out of the rodless chamber of the first oil cylinder 11 can flow into the low-pressure accumulator group 3, while port A of the proportional reversing valve 4 is blocked, preventing oil from flowing through the normal feathering oil supply line.

[0040] Example 2

[0041] As an optional example of the present invention, port A of the proportional reversing valve 4 is connected to the first set of pipelines 51 via a third normally closed solenoid valve 57. In an emergency shutdown condition where the entire system loses power, this ensures that the hydraulic oil flowing out of the rod chamber of the second oil cylinder 12 can flow into the low-pressure accumulator group 3, and also ensures that port A of the proportional reversing valve 4 is disconnected from the first set of pipelines 51, preventing oil from flowing through the normal propeller oil supply pipeline. Furthermore, the third normally closed solenoid valve 57 and the first normally closed solenoid valve 22 effectively overcome leakage issues in the proportional reversing valve 4, thereby effectively reducing the operation of the replenishment oil pump 61. Furthermore, when the proportional reversing valve 4 is powered off, port B is connected to port T, and port A can be closed. Alternatively, port A can be connected to port T or port P. Because port A of the proportional reversing valve 4 is connected to the first set of pipelines 51 via the third normally closed solenoid valve 57, and port P of the proportional reversing valve 4 is connected to the output port of the high-pressure accumulator 21 via the first normally closed solenoid valve 22, no oil flows through either port A or port P of the proportional reversing valve 4 during a power outage. The proportional reversing valve 4 is a solenoid valve capable of switching between AT, PB, PA, and BT, as well as connecting BT during a power outage. In this embodiment, the proportional reversing valve 4 is a three-position, four-way solenoid valve, and its neutral position is Y-type. Of course, in other implementations, the neutral position of the proportional reversing valve 4 may also be J-type; the proportional reversing valve 4 may also be a two-position, four-way valve with PA and BT in the power outage, etc.

[0042] The integrated hydraulic pitch control system provided by the present invention has the following working process:

[0043] Under the propeller-opening condition, the proportional reversing valve 4 is in the AT and PB states, the first normally closed solenoid valve 22 and the second normally closed solenoid valve 56 are in the passage, and the second normally open solenoid valve 55 and the first normally open solenoid valve 23 are in the closed circuit. The hydraulic oil in the high-pressure accumulator 21 passes through the first normally closed solenoid valve 22 and the PB circuit of the proportional reversing valve 4, and then enters the rodless chamber of the first cylinder 11 and the rod chamber of the second cylinder 12 through the second set of pipes 52. The first cylinder 11 pushes out and the second cylinder 12 retracts to drive the blades to rotate. The oil in the rod chamber of the first cylinder 11 passes through the second return oil pipe 54 and is merged into the second set of pipes 52 through the second normally closed solenoid valve 56, reducing the oil supply to the high-pressure accumulator 21. The oil in the rodless chamber of the second cylinder 12 passes through the first set of pipes 51 and the AT circuit of the proportional reversing valve 4 to enter the low-pressure accumulator group 3. When the pressure of the high-pressure accumulator 21 is lower than the set value, the supplementary oil pump 61 is started to supply the hydraulic oil in the low-pressure accumulator group 3 into the high-pressure accumulator 21 and enter the system circulation.

[0044] During feathering operation, the proportional reversing valve 4 is in the PA and BT states. The first normally closed solenoid valve 22 and the second normally open solenoid valve 55 are open, while the second normally closed solenoid valve 56 and the first normally open solenoid valve 23 are closed. Hydraulic oil in the high-pressure accumulator 21 flows through the first normally closed solenoid valve 22 and the PA circuit of the proportional reversing valve 4, then through the first set of pipes 51 into the rod chamber of the first cylinder 11 and the rodless chamber of the second cylinder 12, respectively. The first cylinder 11 retracts and the second cylinder 12 extends, driving the blades. The oil in the rod chamber of the second cylinder 12 flows through the first return line 53 and the second normally open solenoid valve 55, rejoining the first set of pipes 51, reducing the oil supply to the high-pressure accumulator 21. The oil in the rodless chamber of the first cylinder 11 flows through the second set of pipes 52 and the BT circuit of the proportional reversing valve 4 to enter the low-pressure accumulator group 3. When the pressure of the high-pressure accumulator 21 is lower than the set value, the supplementary oil pump 61 of the low-pressure accumulator group 3 is started to supply the hydraulic oil in the low-pressure accumulator group 3 into the high-pressure accumulator 21 and enter the system circulation.

[0045] During an emergency shutdown with the entire system powered off, the proportional reversing valve 4 is in the BT state. The second normally-open solenoid valve 55 and the first normally-open solenoid valve 23 are open circuits, while the first normally-closed solenoid valve 22 and the second normally-closed solenoid valve 56 are closed circuits. The hydraulic oil in the high-pressure accumulator 21 passes through the first normally-open solenoid valve 23 and then through the first set of pipes 51 into the rod chamber of the first cylinder 11 and the rodless chamber of the second cylinder 12, respectively. The first cylinder 11 retracts and the second cylinder 12 pushes out, driving the blades. The oil in the rod chamber of the second cylinder 12 passes through the first return line 53 and then through the second normally-open solenoid valve 55, rejoining the first set of pipes 51, reducing the oil supply to the high-pressure accumulator 21. The oil in the rodless chamber of the first cylinder 11 passes through the second set of pipes 52 and through the BT circuit of the proportional reversing valve 4 into the low-pressure accumulator. The low-pressure accumulator group 3 stores the oil discharged from the entire system.

[0046] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0047] 1. The integrated hydraulic pitch control system disclosed in the present invention adopts an integrated system design, eliminating the liquid slip ring and hydraulic station in the nacelle and integrating the entire pitch control system into the hub; the low-pressure accumulator group 3 replaces the oil tank to avoid the risk of oil leakage in the oil storage device when the wind rotor rotates; the high-pressure accumulator group 2 serves as the main energy source for the pitch control action, and the supplementary oil pump 61 of the auxiliary system 6 serves as a supplementary energy source. When the pressure of the high-pressure accumulator group 2 is lower than the set value, the supplementary oil pump 61 starts to supply the hydraulic oil in the low-pressure accumulator group 3 to the high-pressure accumulator group 2, which greatly reduces the number of starts and stops of the supplementary oil pump 61, improves the reliability of the supplementary oil pump 61, and reduces system energy consumption;

[0048] 2. The integrated hydraulic pitch control system disclosed in the present invention, regardless of whether the propeller is in the open or feathering state, the hydraulic oil in the rodless chamber or the rod chamber of one of the oil cylinders is directly replenished to the pitch drive oil circuit through the return oil pipeline, thereby reducing the oil supply of the high-pressure accumulator 21 and the oil replenishment amount of the replenishment oil pump 61 during the pitch control process, greatly reducing the number of starts and stops of the replenishment oil pump 61, improving the reliability of the replenishment oil pump 61, and reducing the system workload and energy consumption; and the return oil pipeline does not need to pass through the proportional reversing valve 4, and directly enters the system circulation to participate in the pitch control operation, thereby reducing the internal pressure loss and energy loss of the system, improving the system reliability, reducing the required system size under the same load, and saving the system installation space;

[0049] 3. The integrated hydraulic variable pitch system disclosed in the present invention can perform emergency feathering in the emergency shutdown condition of the entire system when the power is cut off, and the energy stored in the high-pressure accumulator 21 meets the emergency feathering requirement when the power is cut off. No other energy storage device is required. The high-pressure accumulator 21 is directly connected to the return oil power conversion system 5, thereby greatly reducing the number of failure points and pipelines.

[0050] The present invention is not limited to the aforementioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. An integrated hydraulic pitch control system, characterized by: The invention comprises a push-pull double-pitch cylinder group (1), a high-pressure accumulator group (2), a low-pressure accumulator group (3), a proportional reversing valve (4), an oil return power conversion system (5) and an auxiliary system (6), wherein the push-pull double-pitch cylinder group (1) comprises a first oil cylinder (11) and a second oil cylinder (12) arranged in a forward and reverse direction; the output port of the high-pressure accumulator group (2) is connected to the P port of the proportional reversing valve (4); the A port of the proportional reversing valve (4) is connected to the rod chamber of the first oil cylinder (11) and the rodless chamber of the second oil cylinder (12) through the oil return power conversion system (5); the B port of the proportional reversing valve (4) is connected to the rod chamber of the first oil cylinder (11) and the rodless chamber of the second oil cylinder (12) through the oil return power conversion system The system (5) is connected to the rodless chamber of the first oil cylinder (11) and the rod chamber of the second oil cylinder (12) respectively, the T port of the proportional reversing valve (4) is connected to the low-pressure accumulator group (3), and the low-pressure accumulator group (3) is connected to the high-pressure accumulator group (2) through the auxiliary system (6), and the auxiliary system (6) includes a supplementary oil pump (61); the return oil power conversion system (5) allows the hydraulic oil in the rod chamber of the extended oil cylinder or the rodless chamber of the retracted oil cylinder to flow into the return oil power conversion system (5) in the propeller opening or propeller feathering state to directly provide supplement for the pitch drive oil circuit, and the hydraulic oil in the retracted chamber of the other oil cylinder flows into the low-pressure accumulator group (3) for storage; The oil return power conversion system (5) comprises a first group of pipelines (51) connecting the A port of the proportional reversing valve (4) to the rod chamber of the first oil cylinder (11) and the rodless chamber of the second oil cylinder (12), a second group of pipelines (52) connecting the B port of the proportional reversing valve (4) to the rodless chamber of the first oil cylinder (11) and the rod chamber of the second oil cylinder (12), and an oil return pipeline; The oil return pipeline includes a first oil return pipeline (53) connected from the rod chamber of the second oil cylinder (12) to the first group of pipelines (51) and a second oil return pipeline (54) connected from the rod chamber of the first oil cylinder (11) to the second group of pipelines (52); The first group of pipelines (51) is in one-way communication with the rod chamber of the first oil cylinder (11); the second group of pipelines (52) is in one-way communication with the rod chamber of the second oil cylinder (12); The first oil return pipeline (53) is provided with a first solenoid valve, and the second oil return pipeline (54) is provided with a second solenoid valve; The first solenoid valve is a second normally open solenoid valve (55); the second solenoid valve is a second normally closed solenoid valve (56).

2. The integrated hydraulic pitch system according to claim 1, characterized in that: The high-pressure accumulator group (2) comprises a high-pressure accumulator (21), a first normally closed solenoid valve (22) and a first normally open solenoid valve (23); the output port of the high-pressure accumulator (21) is connected to the P port of the proportional reversing valve (4) through the first normally closed solenoid valve (22); and the output port of the high-pressure accumulator (21) is also connected to the oil return power conversion system (5) through the first normally open solenoid valve (23).

3. The integrated hydraulic pitch system according to claim 1, wherein: The proportional reversing valve (4) is a three-position four-way solenoid valve, and the middle position function of the proportional reversing valve (4) is J-type or Y-type.

4. The integrated hydraulic pitch system according to claim 1, wherein: Port A of the proportional reversing valve (4) is connected to the first set of pipelines (51) via a third normally closed solenoid valve (57).

5. The integrated hydraulic pitch system according to claim 1, characterized in that: The low-pressure accumulator group (3) is connected to the high-pressure accumulator group (2) in one direction.

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