Servo pump controlled pitch control system and control method

Abstract

The present invention discloses a servo pump-controlled variable pitch system and method, the system includes: an electric servo pump control unit, the electric servo pump control unit includes a servo motor and a hydraulic pump, the hydraulic pump has a bidirectional pressure output function, the servo motor is used to control the delivery of the power oil of the hydraulic pump; a servo driver, the servo driver converts the instructions from the controller into a control signal that can be recognized by the servo motor; a variable pitch hydraulic cylinder, the variable pitch hydraulic cylinder is connected to the hydraulic pump, the variable pitch hydraulic cylinder has a displacement sensor, the displacement sensor is used to monitor the stroke of the telescopic rod of the variable pitch hydraulic cylinder; an air cooler, the air cooler cools the electric servo pump control unit according to the heat generated by the electric servo pump control unit. The electric servo pump control unit of the present invention combines the technical advantages of both hydraulic and motor drives, greatly reduces energy consumption and provides a cleaner working environment, reduces the occupied space of the entire machine equipment, and maintains the characteristics of flexible servo electric motion control and small size.

Description

Technical Field

[0001] The present invention relates to a wind turbine pitch control system, and more particularly to a servo pump controlled pitch control system and a control method thereof. Background Art

[0002] The existing wind turbine pitch control systems are mostly motor-driven or electro-hydraulic servo valve-controlled.

[0003] The traditional motor-driven pitch control solution is a purely mechanical transmission that drives the reduction box gears to rotate. However, due to the use environment, the gears will be subject to greater impact and the rigid structure has poor seismic resistance, resulting in severe wear of the gear ring and increased tooth clearance, which in turn causes delayed pitch control response or even failure, short gear ring life, and extremely high maintenance costs.

[0004] The traditional electro-hydraulic servo valve control system is an open system that requires an external pump station and oil tank, resulting in low equipment integration, high installation cost, complex pipelines, many leaks, constant pressure operation of the hydraulic oil source and throttling losses in the pipelines and valve ports, resulting in system energy waste. At the same time, the servo valve has poor anti-pollution ability and requires a high level of oil cleanliness. The system needs to be equipped with a precision filtration device, which increases the system installation cost. Summary of the invention

[0005] An object of the present invention is to provide a new technical solution for a servo pump-controlled pitch control system and a control method, which can at least solve one technical problem existing in the prior art.

[0006] According to a first aspect of the present invention, a servo pump-controlled pitch system is provided for use in a wind turbine generator set, the system comprising: an electric servo pump control unit, the electric servo pump control unit comprising a servo motor and a hydraulic pump, the hydraulic pump having a bidirectional pressure output function, the servo motor being used to control the delivery of power oil of the hydraulic pump; a servo driver, the servo driver converting instructions from a controller into control signals recognizable by the servo motor; a pitch hydraulic cylinder, the pitch hydraulic cylinder being connected to the hydraulic pump, the pitch hydraulic cylinder having a displacement sensor, the displacement sensor being used to monitor the stroke of the telescopic rod of the pitch hydraulic cylinder; and an air cooler, the air cooler cooling the electric servo pump control unit according to the heat generated by the electric servo pump control unit.

[0007] Optionally, the pitch hydraulic cylinder is connected to the hydraulic pump, and the pitch hydraulic cylinders are arranged in series in opposite directions.

[0008] Optionally, the air cooler is equipped with a temperature transmitter to cool the electric servo pump control unit.

[0009] Optionally, the servo pump-controlled pitch system further includes: a functional valve group, wherein the functional valve group is connected to the electric servo pump control unit.

[0010] Optionally, the functional valve group includes:

[0011] A safety relief valve, the safety relief valve is used to limit the rated working pressure of the system;

[0012] An accumulator is used to absorb pulsation of the hydraulic pump when the hydraulic pump is in a first speed operation state.

[0013] Optionally, the functional valve group further includes:

[0014] A pressure transmitter, wherein the pressure transmitter is used to adjust the oil pressure;

[0015] An electromagnetic reversing valve, the electromagnetic reversing valve is used to change the oil passage;

[0016] A liquid replenishing valve is used to replenish oil.

[0017] Optionally, the functional valve group further includes:

[0018] A high-pressure filter, wherein the high-pressure filter is used to filter oil;

[0019] A throttle valve, wherein the throttle valve is used to adjust the oil flow;

[0020] A shuttle valve is used for bidirectional control of oil.

[0021] Optionally, the servo pump-controlled pitch system further includes:

[0022] A power source module, the power source module is used to provide power;

[0023] A security protection module is used to provide security protection for the system.

[0024] Optionally, the servo pump-controlled pitch system further includes:

[0025] An oil replenishment circuit module, the oil replenishment circuit module is used to replenish oil according to different working conditions;

[0026] A flow asymmetric module, the flow asymmetric module is used to compensate for the flow demand of the hydraulic cylinder;

[0027] A system status monitoring module, wherein the system status monitoring module is used to monitor the operating status of the system.

[0028] A second aspect of the present invention provides a control method for a servo pump-controlled pitch system, which is applied to the control method for the servo pump-controlled pitch system described in the above embodiment, and the method comprises:

[0029] The electric servo pump control unit is used to control the delivery of the power oil of the hydraulic pump;

[0030] The servo driver converts the command from the controller into a control signal that can be recognized by the servo motor;

[0031] Monitoring the stroke of the telescopic rod of the pitch hydraulic cylinder by means of a pitch hydraulic cylinder having a displacement sensor;

[0032] According to the heat generated by the electric servo pump control unit, an air cooler is used to cool the electric servo pump control unit.

[0033] The servo pump-controlled variable pitch system of the present invention is applied to wind turbines. The electric servo pump control unit is the core unit of the servo pump-controlled variable pitch system. The electric servo pump control unit combines the technical advantages of both hydraulic and motor drives, which can greatly reduce energy consumption and provide a cleaner working environment. Since conventional hydraulic pump stations and complex piping are not required, the occupied space of the entire machine equipment can be effectively reduced. The servo pump-controlled variable pitch system of the present invention maintains the characteristics of flexible servo electric motion control and small size, and introduces a closed hydraulic system, eliminating the oil source pump station and pipeline components, thereby bringing extremely low leakage points, saving installation space, and having a large cost advantage.

[0034] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0036] Figure 1 is a working principle diagram of a servo pump-controlled pitch control system according to an embodiment of the present invention;

[0037] Figure 2 is a pitch control principle diagram of a servo pump-controlled pitch control system according to an embodiment of the present invention;

[0038] Figure 3 is a structural schematic diagram of a servo pump-controlled pitch control system according to an embodiment of the present invention;

[0039] Figure 4 Schematic diagram of the structure of the accumulator of the servo pump-controlled pitch control system according to an embodiment of the present invention.

[0040] Reference numerals:

[0041] Servo motor 1; hydraulic pump 2; functional valve group 30; electromagnetic reversing valve 3; throttle valve 4; shuttle valve 5; safety relief valve 6; pressure measuring joint 7; liquid replenishing valve 8; pressure transmitter 9; temperature transmitter 10; high-pressure filter 11; accumulator 12; air cooler 13; pitch hydraulic cylinder 14. DETAILED DESCRIPTION

[0042] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0043] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0044] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0045] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0046] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0047] In the specification and claims of the present invention, if the term "first" or "second" is involved, it may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the related objects are in an "or" relationship.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present invention.

[0049] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" involved should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The servo pump controlled pitch control system according to an embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0051] like Figures 1 to 4 As shown, the servo pump-controlled pitch control system according to an embodiment of the present invention is applied to a wind turbine generator set, and the system includes an electric servo pump control unit, a servo driver, and an air cooler 13.

[0052] Specifically, the electric servo pump control unit includes a servo motor 1 and a hydraulic pump 2. The hydraulic pump 2 has a bidirectional pressure output function. The servo motor 1 is used to control the delivery of the power oil of the hydraulic pump 2. The servo driver converts the instructions from the controller into control signals that can be recognized by the servo motor 1. The pitch hydraulic cylinder 14 is connected to the hydraulic pump 2. The pitch hydraulic cylinder 14 has a displacement sensor, which is used to monitor the stroke of the telescopic rod of the pitch hydraulic cylinder 14. The air cooler 13 cools the electric servo pump control unit according to the heat generated by the electric servo pump control unit.

[0053] In other words, the servo pump-controlled pitch system according to the embodiment of the present invention is mainly applied to wind turbines, and the servo pump-controlled pitch system is mainly composed of an electric servo pump control unit, a servo driver, a servo driver and an air cooler 13. Figure 1 As shown, the electric servo pump control unit includes a servo motor 1 and a hydraulic pump 2. The electric servo pump control unit (EPU) is the core unit of the servo pump-controlled pitch system. The electric servo pump control unit (EPU) combines the technical advantages of both hydraulic and motor drives, which can greatly reduce energy consumption and provide a cleaner working environment. Since it does not require conventional hydraulic pump stations and complex piping, it can effectively reduce the space occupied by the entire machine equipment.

[0054] The hydraulic pump 2 has a bidirectional pressure output function, and the servo motor 1 is used to control the delivery of the power oil of the hydraulic pump 2. The servo driver converts the instructions from the controller into control signals that can be recognized by the servo motor 1. The servo driver can convert the instructions from the controller into control signals that can be recognized by the servo motor 1. The servo driver uses an appropriate control algorithm to convert the analog signal sent by the controller into a digital signal, which is then processed by the internal CPU and finally outputs the target current or position signal required by the servo motor 1. The servo driver controls the speed of the servo motor 1 by the frequency and number of pulses received.

[0055] The pitch hydraulic cylinder 14 is connected to the hydraulic pump 2, and the pitch hydraulic cylinder 14 has a displacement sensor, which is used to monitor the stroke of the telescopic rod of the pitch hydraulic cylinder 14. The air cooler 13 can cool the electric servo pump control unit according to the heat generated by the electric servo pump control unit.

[0056] Therefore, the servo pump-controlled pitch system according to the embodiment of the present invention is applied to a wind turbine generator set. The electric servo pump control unit is the core unit of the servo pump-controlled pitch system. The electric servo pump control unit combines the technical advantages of both hydraulic and motor drives, which can greatly reduce energy consumption and provide a cleaner working environment. Since conventional hydraulic pump stations and complex piping are not required, the occupied space of the entire machine equipment can be effectively reduced. The servo pump-controlled pitch system of the present invention maintains the characteristics of flexible servo electric motion control and small size, and introduces a closed hydraulic system, eliminating the oil source pump station and pipeline components, thereby bringing extremely low leakage points, saving installation space, and having a large cost advantage.

[0057] According to one embodiment of the present invention, the pitch hydraulic cylinder 14 is connected to the hydraulic pump 2, and the pitch hydraulic cylinders 14 are arranged in series opposite to each other (see Figure 2 ) to improve system work efficiency.

[0058] According to one embodiment of the present invention, the air cooler 13 is equipped with a temperature transmitter 10 to cool the electric servo pump control unit. Figure 1 As shown, the air cooler 13 matches the temperature transmitter 10, and can cool the servo motor 1 and the hydraulic pump 2 according to the heat generation requirements of the servo pump control system, thereby improving the cooling efficiency and enhancing the system performance.

[0059] According to one embodiment of the present invention, the servo pump-controlled pitch system also includes: a functional valve group 30, which is connected to the electric servo pump control unit. Compared with the traditional electro-hydraulic servo valve control system, the electro-hydraulic servo pump control system realizes high-performance control of the hydraulic pitch system. By setting the functional valve group 30, the servo pitch control system can effectively solve the inherent problems of the electro-hydraulic servo valve control technology, and has the advantages of high efficiency and energy saving, high power-to-weight ratio and environmental friendliness.

[0060] According to one embodiment of the present invention, Figure 1 , Figure 3 and Figure 4 The functional valve group 30 shown includes a safety relief valve 6 and an accumulator 12. There are multiple safety relief valves 6 and accumulators 12, and the safety relief valve 6 is used to limit the rated working pressure (maximum working pressure) of the system to prevent the system from overloading. The accumulator 12 is used to absorb the pulsation of the hydraulic pump 2 in the first speed (low speed) operating state. According to one embodiment of the present invention, the functional valve group 30 also includes a pressure transmitter 9, an electromagnetic reversing valve 3 and a refilling valve 8, wherein there are multiple pressure transmitters 9, electromagnetic reversing valves 3 and refilling valves 8, and the pressure transmitter 9 is used to adjust the oil pressure. The electromagnetic reversing valve 3 is used to change the oil passage. The refilling valve 8 is used to replenish the oil, and the refilling valve 8 can also be used to realize the functions of underflow replenishment and excess flow overflow.

[0061] According to one embodiment of the present invention, Figure 1 As shown, the functional valve group 30 also includes a high-pressure filter valve, a throttle valve 4 and a shuttle valve 5, wherein the high-pressure filter 11 is used to filter the oil. The throttle valve 4 is used to adjust the oil flow. The shuttle valve 5 is used to control the oil in both directions. Compared with the traditional electro-hydraulic servo valve control system, the electro-hydraulic servo pump control system of the present invention realizes high-performance control of the hydraulic pitch system, and the specific configuration is composed of components such as a servo motor 1, a metering pump, a functional valve group 30, an accumulator 12, a hydraulic cylinder and a controller. The volume servo pitch control system can effectively solve the inherent problems existing in the electro-hydraulic servo valve control technology, and has the advantages of high efficiency and energy saving, high power-to-weight ratio and environmental friendliness. Of course, in the present invention, the functional valve group 30 also has structures such as a pressure measuring joint 7 and a one-way valve, which will not be described in detail in the present invention.

[0062] According to one embodiment of the present invention, the servo pump-controlled variable pitch system also includes a power source module and a safety protection module, wherein the power source module is used to provide power, and the safety protection module is used to provide safety protection for the system to achieve emergency propeller function and system maximum pressure value limitation.

[0063] According to one embodiment of the present invention, the servo pump-controlled pitch control system also includes an oil replenishment circuit module, a flow asymmetry module and a system status monitoring module, wherein the oil replenishment circuit module is used to replenish oil according to different working conditions. The flow asymmetry module is used to compensate for the flow demand of the hydraulic cylinder. The system status monitoring module is used to monitor the operating status of the system. In the present invention, a solenoid valve is provided at the oil port of the oil cylinder to ensure the locking function of the oil cylinder during long-term shutdowns such as installation, maintenance, and pitch setting.

[0064] In summary, in the servo pump-controlled pitch system for wind turbines of the present invention, the electric servo pump control unit (EPU) is the core unit of the servo pump-controlled pitch system. The electric servo pump control unit (EPU) combines the technical advantages of both hydraulic and motor drives, which can greatly reduce energy consumption and provide a cleaner working environment. Since it does not require a conventional hydraulic pump station and complex piping, it can effectively reduce the occupied space of the entire machine equipment. Compared with the traditional electro-hydraulic servo valve control system, the electro-hydraulic servo pump control system realizes high-performance control of the hydraulic pitch system. The specific configuration is composed of components such as a servo motor 1, a metering pump, a functional valve group 30, an accumulator 12, a hydraulic cylinder and a controller. The volumetric servo pitch control system can effectively solve the inherent problems of the electro-hydraulic servo valve control technology, and has the advantages of high efficiency and energy saving, high power-to-weight ratio and environmental friendliness. The servo pump control system consists of a power source module, a safety protection module, an oil replenishment circuit module, a flow asymmetry module and a system status monitoring module; it realizes the functions of emergency propeller function, system maximum pressure value limitation, system oil replenishment to prevent pump from sucking air, system oil replenishment or overflow compensation for asymmetric hydraulic cylinder flow demand and system operation status monitoring.

[0065] Of course, for those skilled in the art, other structures and working principles of the servo pump-controlled pitch system are understandable and achievable, and will not be described in detail in the present invention.

[0066] According to a second aspect of the present invention, a control method for a servo pump-controlled pitch system is provided, which is applied to the control method for the servo pump-controlled pitch system in the above embodiment, and the method comprises:

[0067] An electric servo pump control unit is used to control the delivery of power oil of the hydraulic pump 2;

[0068] The servo driver converts the command from the controller into a control signal that can be recognized by the servo motor 1;

[0069] The stroke of the telescopic rod of the pitch hydraulic cylinder 14 is monitored by the pitch hydraulic cylinder 14 having a displacement sensor;

[0070] According to the heat generated by the electric servo pump control unit, an air cooler 13 is used to cool the electric servo pump control unit.

[0071] That is to say, Figure 1 As shown, in the control method of the servo pump-controlled pitch system of the present invention, an electric servo pump control unit can be used to control the delivery of the power oil of the hydraulic pump 2. The electric servo pump control unit (EPU) is the core unit of the servo pump-controlled pitch system. The electric servo pump control unit (EPU) combines the technical advantages of both hydraulic and motor drives, which can greatly reduce energy consumption and provide a cleaner working environment. Since conventional hydraulic pump stations and complex piping are not required, the occupied space of the entire machine equipment can be effectively reduced.

[0072] The servo driver converts the instructions from the controller into control signals that can be recognized by the servo motor 1. The servo driver can convert the instructions from the controller into control signals that can be recognized by the servo motor 1. The servo driver uses appropriate control algorithms to convert the analog signals sent by the controller into digital signals, which are then processed by the internal CPU and finally output the target current or position signal required by the servo motor 1. The servo driver controls the speed of the servo motor 1 by the frequency and number of pulses received.

[0073] The pitch hydraulic cylinder 14 with a displacement sensor monitors the travel of the telescopic rod of the pitch hydraulic cylinder 14. According to the heat generated by the electric servo pump control unit, the air cooler 13 is used to cool the electric servo pump control unit.

[0074] In summary, the control method of the servo pump-controlled pitch system for a wind turbine generator set of the present invention, the electric servo pump control unit (EPU) is the core unit of the servo pump-controlled pitch system, the electric servo pump control unit (EPU) combines the technical advantages of both hydraulic and motor drives, can greatly reduce energy consumption and provide a cleaner working environment, and because it does not require a conventional hydraulic pump station and complex piping, it can effectively reduce the occupied space of the entire machine equipment. Compared with the traditional electro-hydraulic servo valve control system, the electro-hydraulic servo pump control system realizes high-performance control of the hydraulic pitch system, and the specific configuration is composed of components such as a servo motor 1, a metering pump, a functional valve group 30, an accumulator 12, a hydraulic cylinder and a controller. The volumetric servo pitch control system can effectively solve the inherent problems of the electro-hydraulic servo valve control technology, and has the advantages of high efficiency and energy saving, high power-to-weight ratio and environmental friendliness. The servo pump control system consists of a power source module, a safety protection module, an oil replenishment circuit module, an asymmetric flow module and a system status monitoring module; it can realize the functions of emergency feathering, system maximum pressure value limitation, system oil replenishment to prevent pump from sucking empty, system oil replenishment or overflow compensation asymmetric hydraulic cylinder flow demand and system operation status monitoring;

[0075] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A servo pump controlled pitch control system, applied to a wind turbine generator set, characterized in that: The system comprises: An electric servo pump control unit, the electric servo pump control unit comprising a servo motor (1) and a hydraulic pump (2), the hydraulic pump (2) having a bidirectional pressure output function, and the servo motor (1) being used to control the delivery of power oil of the hydraulic pump (2); A servo driver, which converts instructions from a controller into control signals that can be recognized by the servo motor (1); A pitch hydraulic cylinder (14), the pitch hydraulic cylinder (14) being connected to the hydraulic pump (2), the pitch hydraulic cylinder (14) having a displacement sensor, the displacement sensor being used to monitor the stroke of the telescopic rod of the pitch hydraulic cylinder (14); An air cooler (13), wherein the air cooler (13) cools the electric servo pump control unit according to the heat generated by the electric servo pump control unit.

2. The servo pump-controlled pitch system according to claim 1, characterized in that: The pitch-changing hydraulic cylinders (14) are connected to the hydraulic pump (2), and the pitch-changing hydraulic cylinders (14) are arranged in series in opposite directions.

3. The servo pump-controlled pitch system according to claim 1, characterized in that: The air cooler (13) is equipped with a temperature transmitter (10) to cool the electric servo pump control unit.

4. The servo pump-controlled pitch system according to claim 1, characterized in that: Also includes: A functional valve group (30), wherein the functional valve group (30) is connected to the electric servo pump control unit.

5. The servo pump-controlled pitch system according to claim 4, characterized in that: The functional valve group (30) comprises: A safety relief valve (6), the safety relief valve (6) being used to limit the rated working pressure of the system; An accumulator (12) is used to absorb pulsation of the hydraulic pump (2) in a first speed operation state.

6. The servo pump-controlled pitch system according to claim 4, characterized in that: The functional valve group (30) further comprises: A pressure transmitter (9), wherein the pressure transmitter (9) is used to adjust the oil pressure; An electromagnetic reversing valve (3), the electromagnetic reversing valve (3) being used to change an oil passage; A liquid replenishing valve (8), wherein the liquid replenishing valve (8) is used to replenish oil.

7. The servo pump-controlled pitch system according to claim 4, characterized in that: The functional valve group (30) further comprises: A high-pressure filter (11), wherein the high-pressure filter (11) is used to filter oil; A throttle valve (4), wherein the throttle valve (4) is used to adjust the flow rate of oil; A shuttle valve (5), wherein the shuttle valve (5) is used for bidirectionally controlling oil.

8. The servo pump-controlled pitch system according to claim 1, characterized in that: Also includes: A power source module, the power source module is used to provide power; A security protection module is used to provide security protection for the system.

9. The servo pump-controlled pitch system according to claim 1, characterized in that: Also includes: An oil replenishment circuit module, the oil replenishment circuit module is used to replenish oil according to different working conditions; A flow asymmetric module, the flow asymmetric module is used to compensate for the flow demand of the hydraulic cylinder; A system status monitoring module, wherein the system status monitoring module is used to monitor the operating status of the system.

10. A control method for a servo pump-controlled pitch system, applied to the control method for a servo pump-controlled pitch system according to any one of claims 1 to 9, characterized in that: The method comprises: An electric servo pump control unit is used to control the delivery of power oil of a hydraulic pump (2); Converting the command from the controller into a control signal recognizable by the servo motor (1) through a servo driver; Monitoring the travel of the telescopic rod of the pitch-changing hydraulic cylinder (14) by means of a pitch-changing hydraulic cylinder (14) having a displacement sensor; According to the heat generated by the electric servo pump control unit, an air cooler (13) is used to cool the electric servo pump control unit.

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