147 results about "Variable pitch propeller" patented technology

A hybrid propulsion system includes a main diesel engine for driving the marine turbine and an electric motor. The electric motor has a nominal output that constitutes at least 20% of the nominal output of the main diesel engine. The electric motor remains continuously switched on and maintains, together with a variable-pitch propeller, the main diesel engine at a favorable operating point. The combination of the main diesel engine and the electric motor also allows for a more economical design or operation of the propulsion system.

A variable marine jet propulsion system incorporates a motor, a variable-pitch propeller pump in a spherical housing, a variable housing and a variable inlet duct, and a microcontroller. The pump, the nozzle and the inlet are controlled by the microcontroller, which is programmed to control the pump as a continuously variable power transmission for maintaining efficient motor operation, the nozzle for maintaining efficient pump operation, and the inlet for maintaining efficient recovery of the total dynamic head of the incoming water. The spherical pump housing maintains close fits to the propeller vane tips for more efficient operation at all pitches, including zero and reverse pitches. Zero pitch results in no effective pumping action, effectively a true neutral in fluid power transmission. Reverse pitch in combination with the large variable nozzle provides reverse flow and consequently reverse thrust, which eliminates the need for the “backing bucket”.

The invention discloses a novel variable-diameter variable-pitch propeller. According to the novel variable-diameter variable-pitch propeller, a propeller cap (5) is arranged on a propeller hub (4) and provides a mounting space and a top support for a connecting rod mechanism (1), a driving mechanism (2), a sliding supporting mechanism (6) and a locking release mechanism; the driving mechanism (2) and the sliding supporting mechanism (6) are fixed on the propeller hub (4); the output of the driving mechanism (2) is connected with the connecting rod mechanism (1); a propeller blade (3) is fixed at the guide output end of the connecting rod mechanism (1) through a variable pitch mechanism (8); the bottom of the guide output end of the connecting rod mechanism (1) is connected with the sliding supporting mechanism (6); the connecting rod mechanism (1) is supported and guided through the sliding supporting mechanism (6); the driving mechanism (2) drives the connecting rod mechanism (1) to drive the propeller blade (3) to stretch out and draw back in the propeller diameter direction along with the sliding supporting mechanism (6), so that the diameter size of the whole propeller disc is changed; the connecting rod mechanism (1) is locked through the locking release mechanism (7) after the propeller blade (3) stretches out / draws back in place; and the variable pitch mechanism (8) drives the propeller blade (3) to rotate, so that variable pitch of the whole propeller is realized.

The invention discloses a tail-sitter four-rotor canard aircraft capable of vertically taking off and landing. The tail-sitter four-rotor canard aircraft capable of vertically taking off and landing comprises an aircraft body, wings, canards, vertical tails and power devices; a pair of canards is mounted at the head part of the aircraft body; the wings are on two sides of the tail part of the aircraft body; the vertical tails are respectively arranged above and under the tail part of the aircraft body; the power devices are respectively arranged at the tip parts of the wings and the tip parts of the vertical tails; the power devices are variable pitch propellers; and rotating shafts of the power devices are parallel to the axis of the aircraft body. The tips of the wings, the tips of the vertical tails and the tail end of the aircraft body of the four-rotor canard aircraft mutually form five supporting points; and in a stopping state, the five supporting points enable the aircraft to vertically land on the ground upward. The tail-sitter four-rotor canard aircraft capable of vertically taking off and landing has the advantages of rapid vertical takeoff and landing response speed as well as good controllabitity, stability and wind-resistant performance during vertical takeoff and landing. By using canard configuration, the tail-sitter four-rotor canard aircraft capable of vertically taking off and landing can horizontally fly for a long time at a high speed in the form of a fixed wing and can realize good controllabitity and maneuverability.

According to typical inventive practice, a cylindrical or prolate spheroidal marine hull has two congruent contra-rotative propellers coaxially situated at or near its axial ends. Each propeller has plural blades mechanically and / or flexibly attributed with changeability of blade pitch angles and blade flap angles. A blade-pitch control system adjusts the individual blade pitch angles of both propellers. The blade-pitch control system may be electronically and / or mechanically actuated, and is capable of: (i) cyclically adjusting the blade pitch angles of the two propellers so as to select two respective blade-tip-path planes, each characterized by a direction of thrust that is associated with the blade flap angles and is generally perpendicular to the blade-tip-path plane; (ii) collectively adjusting the blade pitch angles of the two propellers so as to select two respective magnitudes of thrust. The cyclic and collective blade commands, algorithmically coordinated, determine the direction, orientation, and speed of the hull.

A watercraft capable of operating in hydrofoil mode or ground-effect mode with self-righting retractable V-shaped foil, fiberoptic control systems, and a plurality of aircraft style engines with variable pitch propellers for speed and direction control. The V-shaped foil can be fully retracted into the hull allowing operation in shallow water, and the ability to execute a beach landing. Propeller pitch can be reversed allowing the craft to backup. Each engine and propeller can be controlled individually allowing rotating in-place for precise maneuvering control. The hull is a flying wing, airfoil shape for efficient high-speed operation. Engine nacelles are located on airfoil shaped struts, angled in a V-shape, for self-righting effect at high speed. Fuel tanks are within the nacelles, thus outside the main hull for safety.

An embodiment of the invention discloses a helicopter. The helicopter is characterized in that 1), the helicopter is provided with a single engine, power for propulsion devices is outputted by the central engine in a mechanical transmission manner; 2), a tail rotor is omitted, and the variable-pitch propeller horizontal propulsion devices are mounted at the outer ends of stub wings; 3), the propulsion devices on two sides of the helicopter realize same-direction propulsion so that the helicopter flies at a high speed, and the propulsion devices realize differential propulsion in reverse directions so that the heading direction of the helicopter deflects; 4), the lift force compensating stub wings are arranged on two sides of a helicopter body to increase lift force; 5), broad ailerons are disposed at the rear edges of the stub wings, and rolling mobility is improved; and 6), the helicopter is provided with empennages, and pitching and yawing mobility is enhanced. The high-speed helicopter is further characterized by comprising the streamline helicopter body with a single tail boom, a main rotor disposed on the upper side of the helicopter body, the lift force stub wings arranged on the two sides of the helicopter body, the propeller horizontal propulsion devices mounted at the outer ends of the stub wings, horizontal stabilizers positioned out of slip flow of a rear rotor of the helicopter body and a single vertical stabilizer, wherein elevators are arranged at the rear edges of the horizontal stabilizers, and a rudder is disposed at the rear edge of the vertical stabilizer.

The invention discloses an online monitoring system for a storage battery of a fan variable pitch propeller, which comprises a transient discharge circuit, a voltage measuring device, a current measuring device, a temperature measuring device and a controller. The controller comprises a data acquisition module, an automatic switching control module for the transient discharge circuit, a storage battery grouping loop detection control module, a storage battery malfunction coding module, an undervoltage and under-capacitance halt setting value correcting module, a signal processing module, a storage and a halt actuator. The whole working process of the storage battery is detected on line by the online monitoring system, real-time data are acquired, the online monitoring system can judge whether the electric quantity of the storage battery is sufficient or not more really and accurately, detecting results are reliable and effective, and detecting cost is low.

The invention discloses a vertical take-off and landing fixed wing long-endurance air vehicle. The vertical take-off and landing fixed wing long-endurance air vehicle comprises a fuselage in horizontal position in flight; the head part of the fuselage is provided with a pair of canard type wings; the tail part of the fuselage is provided with a pair of wings; a vertical empennage is arranged below the tail part of the fuselage; the lower parts of the wings are provided with at least two pairs of distributed power plants, wherein the number of the power plants is even, and the revolving shafts of the power plants are arranged along the axis of the fuselage; the head part of the fuselage is provided with a vertically distributed through hole; and an elevating control power plant is arranged in the through hole, and the revolving shaft of the elevating control power plant is arranged in vertical. According to the vertical take-off and landing fixed wing long-endurance air vehicle, the elevating control power plant is used for changing rotating aped of variable pitch propellers and elevating control moment force needed by screw pitch output in the whole flight envelope; the number of fixed pitch propellers is larger, and rotating speed of each propeller can be controlled individually, so that rolling and yaw control adjustable minimum pulse-width is smaller, and control accuracy is higher.

The invention provides an intelligent material driven or mechanical driven aircraft with turnable wings, and the aircraft provided by the invention has the advantages of high speed, long voyage, low oil consumption, capability of VTOL (vertical take-of and landing), and capability of hovering. The aircraft comprises an aircraft body, sectional bending turnable wings, electroactive polymer skins, sheet macro-fiber piezoelectric composite material bars, deformed honeycomb fillers, a reversal platform and variable pitch propeller engines, wherein the two variable pitch propeller engines are symmetrically mounted on the rear edges of the wings, the electroactive polymer skins are taken as wing skins, the sheet macro-fiber piezoelectric composite material bars are arranged on the neutral layers of the wings, the spaces between the wing skins and the sheet macro-fiber piezoelectric composite material bars are filled with the deformed honeycomb fillers, and the reversal platform is placed ata rotary center inside the aircraft body. According to the invention, an intelligent driver is utilized as the driving source for wing turning, and the aircraft has the advantages of light weight, simple mechanism, high efficiency and convenience for maintenance, and can be switched rapidly in flying modes of level flaying and hovering through wing turning.

The invention discloses a circulating variable-pitch propeller pipeline robot comprising a guide rod, a linear telescopic motor, a guide wheel, a motion coordinating disc, a fish eye ball head, a telescopic short joint, a driving wheel, a driving wheel supporting rack and a motor having a decelerating set. A rotary bearing is installed in the motion coordinating disc; the center of the rotary bearing is covered with a fish eye bearing; the guide rod is covered with the fish eye bearing in a slide way; the guide wheel is connected with the linear motor telescopic motor; the fish eye ball head is assembled on the linear telescopic motor and in a sleeved connection with a control rod of the motion coordinating disc; the driving wheel is connected with the motor having the decelerating set and installed on the telescopic short joint; the telescopic short joint is connected with the guide rod via the driving wheel supporting rack; a ball head is assembled on the telescopic short joint; the ball head is connected with the ball head on the rotary bearing via a connection rod; and the guide rod is connected with the ball head on the rotary bearing via a synchronous connection rod. The circulating variable-pitch propeller pipeline robot can flexibly move and possesses great traction force, and can be suitable for composite pipeline interior work in a better way.

The disclosed apparatus is an autogyro which utilizes a variable pitch propeller and an electric motor coupled to the lift rotor. At takeoff, the engine may be started with the thrust propeller at zero pitch and the lift rotor-driving electric motor is engaged to spin the lift rotor to the desired take off speed while the autogyro is still stationary on the ground. The pitch of the pusher propeller is switched from zero pitch to the take off power pitch so as to obtain desired forward thrust while the power to the lift rotor is switched off as the autogyro begins to lift off the ground. In this way the takeoff run may be relatively short. Also, if sufficient head wind is present, vertical takeoff would be possible.

Propeller control systems and methods for controlling the pitch of a plurality of propeller blades of a variable pitch propeller assembly operatively coupled with an engine is provided. In one exemplary aspect, the propeller control system includes features for combining overspeed and feathering protective functions in a protective control valve communicatively coupled with a controller. In such an event the controller controls the protective control valve to selectively allow a controlled amount of hydraulic fluid to flow to or from a pitch actuation assembly such that the pitch of the propeller blades can be adjusted based at least in part on the condition of the engine.

The invention relates to a transverse arrangement type composite thrust high-speed helicopter. The helicopter comprises a helicopter body, wings symmetrically arranged on the two sides of the helicopter body, a tail wing arranged at the tail of the helicopter body, engines arranged at the ends of the two sides of the wings, transversely arranged rotor wings arranged above the engines and variablepitch propellers arranged at the positions, close to the direction of the tail wing, of the rears of the engines, wherein the tail wing comprises horizontal tails used for achieving effects of stabilizing pitching and vertical fins used for providing yaw direction motion, the axes of the variable pitch propellers are parallel to the axis of the helicopter body. The transverse arrangement type composite thrust high-speed helicopter sufficiently utilizes advancing blades of the rigid rotor wings at a high speed, and thus pneumatic interference among the rotor wings is reduced; the flying stability can be improved through V-shaped arrangement; the rotor wing / wing interference is effectively reduced by the rigid blade characteristic in the forward flying process, and the transverse distancebetween the two rotor wings sharply reduces the rigidness and the weight of the wings; and propellant blades are arranged below the rotor wings, a transmission system is simplified, and the helicopterbody space is saved.

The invention discloses a tail-sitter type three-rotor canard aircraft capable of vertically taking off and landing. The tail-sitter type three-rotor canard aircraft capable of vertically taking off and landing comprises an aircraft body, wings, a canard wing, a vertical tail and power devices; the canard wing is mounted at the head part of the aircraft body; the wings are positioned on two sides of the tail part of the aircraft body; the vertical tail is arranged under the tail part of the aircraft body; the power devices are respectively arranged at the wing tip parts of the wings and the wing tip part of the vertical tail; and the power devices are variable pitch propellers. Elevons are mounted at the rear edges of the wings; a rudder is mounted at the rear edge of the vertical tail; and an elevating rudder is mounted at the rear edge of the canard wing. The wing tips of the wings, the wing tip of the vertical tail and the tail end of the aircraft body of the tail-sitter type three-rotor canard aircraft capable of vertically taking off and landing mutually form four supporting points; in a stopping state, the four supporting points enable the aircraft to vertically land on the ground upwards; the vertical takeoff and landing response speed of the aircraft is high and the aircraft has good stability during vertically taking off and landing. Through adoption of canard configuraiton, the tail-sitter type three-rotor canard aircraft capable of vertically taking off and landing can horizontally fly at a high speed in the form of a fixed wing and has the advantages of long flying time, good controllability and good motility.

A propeller assembly is disclosed, comprising propeller blades pivotably mounted on a propeller hub. A cam follower is disposed on each propeller blade. A cam is movable between a first position, a second position and a third position. Recesses formed in the cam have a first segment, a second segment and a third segment, oriented at first, second and third angles. The first segment is oriented at a first angle relative to the central axis. The cam followers engage the first segment of the recesses when the cam moves between first and second positions to vary the pitch of the propeller blades between a first pitch and a second pitch. The cam followers engage the second segment of the recesses when the cam moves between second and third positions to vary the pitch of the propeller blades between the second pitch and a third pitch.

The invention discloses an automatic variable-pitch propeller device, a control method thereof and an aircraft. A variable-pitch driving device is connected with a propeller through a variable-pitch structure, and the pitch of the propeller is adjusted by operating the variable-pitch structure; a tension measuring module is connected with a propulsion system and is used for measuring the dynamic tension of the propulsion system; a variable pitch controller determines real-time propeller efficacy value information according to the dynamic tension and input power, determines a target pitch rangeaccording to the propeller rotating speed and airspeed information, and provides a pitch value in the target pitch range by using an automatic optimization method according to the propeller efficacydata, and the propeller performs variable pitch operation. The device can calculate the propeller efficacy value of the propulsion system in real time, automatically optimizes and matches the optimalpitch based on propeller efficacy, and improves the efficiency of the propulsion system of the aircraft.

The invention provides a self-adaptive pneumatic variable-pitch propeller design method. The concept and the method of aircraft longitudinal trimming are utilized. Under the condition that no redundant additional mechanism exists, the aerodynamic characteristics of propeller blades are designed; the method comprises the steps that a balancing principle of double-wing or duck-type layout of an analogy aircraft is adopted; the blades are designed into a double-blade layout with aerodynamic and static stability, so that the propeller has the capacity of providing a high propeller disc load, and meanwhile, the propeller can automatically change the pitch regardless of the forward ratio change caused by the change of the flight speed or the change of the rotation speed, so that the propeller has a relatively good automatic pitch change characteristic in a relatively wide flight envelope.

The invention relates to a propeller for a ship and discloses a variable-pitch propeller for a ship. The variable-pitch propeller comprises a ship shaft, a push-pull rod, racks, a propeller hub, a compensation duct, O-shaped sealing rings, first glands, second glands, blades, partial gears and shaft end retaining rings. When the propeller operates, the ship shaft drives the blades to rotate in the rotating direction of the propeller; a hydraulic variable-pitch piston in a ship power cabin drives the push-pull rod to move in the axial direction of the ship shaft, so that the racks move in the moving direction of the push-pull rod; and each rack is matched with the corresponding partial gears mutually to drive the blades to rotate around the root axes of the blades, so that the pitch angle and the pitch of the propeller are changed, accordingly the thrust of the propeller is changed. By changing the rotating direction of the blades, the direction of the pitch angle can be changed, and accordingly the thrust direction of the propeller is changed.

The invention belongs to the technical field of aviation, and particularly relates to a variable pitch propeller and an unmanned aerial vehicle. The variable pitch propeller comprises a rotating shaft, a first bevel gear, a second bevel gear, a shaft hub and fixed shafts, wherein the first bevel gear is fixed to the rotating shaft, the second bevel gear is rotatably connected to the rotating shaft, the shaft hub is arranged on the rotating shaft between the first bevel gear and the second bevel gear in a sleeving mode and is rotatably connected with the rotating shaft, and the fixed shafts are fixedly connected with the shaft hub and are axially perpendicular to the shaft hub; propeller hubs which are rotatably connected with the fixed shafts are arranged on the fixed shafts in a sleeving mode; torsional deformation pieces which are fixedly connected with the shaft hub and the propeller hubs are arranged on the fixed shaft part between the propeller hubs and the shaft hub in a sleeving mode; propeller blade driving bevel gears which are engaged with the first bevel gear and the second bevel gear are fixedly mounted on the propeller hubs; and the unmanned aerial vehicle comprises the variable pitch propeller. Automatic adjustment of the propeller pitch is realized under interaction between torque of the rotating shaft and reactive torque of the torsional deformation pieces; when the torque becomes large, the propeller pitch becomes small, the thrust performance is enhanced, improvement of the acceleration ability and the flying speed are facilitated, and the problems that the acceleration ability of the variable pitch propeller which changes the propeller pitch through thrust is weak and improving of the flying speed is not easy are solved.

Disclosed are a coaxial two-propeller reverse rotor wing mechanism and an aircraft thereof. The coaxial two-propeller reverse rotor wing mechanism comprises an upper propeller, an upper rotor wing shaft, an upper cone gear, a lower propeller, a lower rotor wing shaft and a lower cone gear. The upper propeller is fixed at the upper end of the upper rotor wing shaft. The upper cone gear is fixed at the lower end of the upper rotor wing shaft in a sleeving mode. The lower propeller is fixed at the lower end of the lower rotor wing shaft. The lower cone gear is fixed at the upper end of the lower rotor wing shaft in a sleeving mode. The upper rotor wing shaft shares the same axis with the lower rotor wing shaft. The upper rotor wing shaft and the low rotor wing shaft are arranged in an over-the-air mode. The upper propeller is a variable pitch propeller. The upper propeller controls variable pitch through a variable pitch assembly. According to the coaxial two-propeller reverse rotor wing mechanism, angular momentum is low, machine arm shaking is low, flying of the aircraft is more flexible, and the wind resistance is high.

A controllable pitch propeller for a ship is provided with an elastic blade root and comprises a propeller hub and a plurality of blades, wherein a connecting piece fixed at the lower end of each blade is inserted into a mounting hole of the propeller hub can be rotated, a securing ring is fixed at the bottom of the mounting hole of the propeller hub, a clearance is reserved between the securing ring and the connecting piece, and two ends of the elastic blade root are respectively inserted into the connecting piece and the securing ring and fixedly connected with the connecting piece and the securing ring. When the power of a main engine is increased or the flow coming speed of the propeller is reduced, the load of the propeller is increased, the pushing force is also increased, the blades are finely adjusted to rotate, the elastic blade root is twisted and deformed, and a pitch angle is changed, and a pitch is reduced. Therefore, the load is reduced. When the load of the propeller is reduced, the elastic blade root enables the pitch angle to recover according to the elastic force. The propeller can adjust the pitch to adapt to the working conditions of the ship, and can enable the blades to carry out adaptive adjustments according to different flow speeds under different angles of rotation, and the load is enabled to be more uniform during a circle of movement.

The invention discloses a variable-pitch propeller, which comprises a motor, a blade installation seat, blades, a pitch-variable rocker arm, a pitch-variable shift fork, a guide seat and a drive rod. The center shaft of the motor, the center of the paddle mounting seat, the center of the guide seat and the center of the pitch-changing fork are all provided with through holes along the vertical direction. The guide seat is installed in the through hole in the center of the motor shaft, the through hole of the paddle mounting seat is set on the upper part of the guide seat and is fixedly connected with the rotating part of the motor at the same time, and the driving rod passes through the center through hole of the guide seat and the The through hole in the center of the pitch change fork connects the motor, the guide seat, the paddle mounting seat and the pitch change fork together. The variable-pitch propeller provided by the present invention is driven by a motor with a through hole in the central shaft, and the pitch-changing mechanism synchronously and reversely controls the pitch change of the blades through the drive rod passing through the through hole on the central shaft of the motor, and has a small number of components, Reasonable structural design, light weight of the whole machine and other advantages, while improving reliability and maintainability.

The invention relates to a double-variable-pitch-propeller aircraft, belonging to the technical field of aviation. The double-variable-pitch-propeller aircraft comprises a fuselage, a tail device, a left wing, a right wing, a left variable-pitch rotor wing, a right variable-pitch rotor wing and an undercarriage. An operation and control system, airborne equipment and energy equipment are equipped in the fuselage. The tail device comprises a left tail propeller, a right tail propeller and a vertical tail. The left variable-pitch rotor wing and the right variable-pitch rotor wing are the same in structure, parameter and working principle and are symmetrically arranged at the left and right sides of the fuselage, so as to supply lift and thrust to the aircraft. The right variable-pitch rotor wing comprises an engine, a main shaft, an electric brush device, a wheel hub and two or four identical propellers which are uniformly distributed around the wheel hub. A main shaft of the right variable-pitch rotor wing is in counterclockwise rotation, at the right side of the main shaft, propeller vanes forwards move at low incidence to generate an upward towing force, and at the left side of the main shaft, the propeller vanes backwards flap at high incidence to generate a forward thrust force, so that the aircraft moves forwards. The aircraft is applied to a variety of tasks, such as aerial photography, geographical mapping, agriculture-forestry-husbandry operation, military reconnaissance and emergency rescue and disaster relief.

The invention relates to a vertical takeoff and landing fixed wing unmanned aerial vehicle with variable pitch propellers. The vertical takeoff and landing fixed wing unmanned aerial vehicle comprises an unmanned aerial vehicle body, wherein wings are separately and fixedly mounted at the middle part of the unmanned aerial vehicle body, and tail wings are separately and fixedly mounted at the tail of the unmanned aerial vehicle body; an engine is mounted at the head of the unmanned aerial vehicle body; two sets of variable pitch propellers are mounted on an output shaft of the engine; when the unmanned aerial vehicle runs, the rotating directions of the two sets of the variable pitch propellers are opposite; each buffer lifting mechanism is arranged on the corresponding tail wing, and comprises a connecting rod, a buffering device and a roller, wherein one end of each connecting rod is hinged to the corresponding tail wing, and the other end of the connecting rod is hinged to the corresponding roller; the middle part of each connecting rod is hinged to the corresponding buffering device which is fixedly mounted in the corresponding tail wing; vertical takeoff, landing and parking are performed by the buffer lifting mechanisms, so that on one hand, the vertical takeoff and landing fixed wing unmanned aerial vehicle has the flight speed of a fixed wing unmanned aerial vehicle, and on the other hand, can perform vertical takeoff, landing and hanging like a rotor unmanned aerial vehicle, and the dependency of the unmanned aerial vehicle on site runways is greatly reduced; and rollers are separately arranged at the tail wings of the unmanned aerial vehicle, and in the flight process, the rollers are driven by an air current to rotate at a high speed, so that in the flight process, the attitude of the unmanned aerial vehicle has better stability.

Blade feedback systems and methods for determining a blade angle position and rotational speed of a plurality of propeller blades of a variable pitch propeller assembly are provided. Exemplary blade feedback system includes features for determining an axial position of a beta tube. Based at least in part on the axial position of the beta tube, the blade angle of the plurality of propeller blades can be determined. Exemplary blade feedback system can also include features for determining the rotational speed of the beta tube such that the rotational speed of the propeller blades can be determined.

The invention discloses an automatic variable-pitch propeller, fixing base assemblies thereof and an aircraft with the same. The fixing base assemblies are assembled on a rotor or a power shaft of a motor (11) of the aircraft. Each fixing base assembly is provided with a paddle (1). The automatic variable-pitch propeller rotates, the paddles (1) generate centrifugal force, a spiral body (5) together with a piston (6) is subjected to a centrifuging effect of the paddles (1) so that the piston (6) slides out of an air cylinder (7), the spiral body (5) gradually extends out from a spiral hole (12), the incidence angles of the paddles (1) change under the matching control of the spiral body (5) and the spiral hole (12), and a vacuum chamber is formed between the air cylinder (7) and an exhaust hole when the piston (6) slides out of the air cylinder (7). The rotating speed is lowered, and when the centrifugal force of the paddles (1) is lowered, the spiral body (5) together with the piston (6) slides into the air cylinder (7) under the vacuum suction of the vacuum chamber and pulls the paddles (1) to rotate back, and therefore the incident angles are changed.

A marine outboard engine has upper and lower engine covers, a swivel bracket, a stern bracket, an engine, a driveshaft, a gear case, a propeller shaft, and a variable pitch propeller. A hydraulic system includes hydraulic steering, trim, and propeller pitch actuators, and at least one valve having at least one inlet, and first, second, and third outlets. The first, second, and third outlets fluidly communicate with the hydraulic steering, trim, and propeller pitch actuators respectively. A pump fluidly communicates with the at least one inlet of the at least one valve. A reservoir stores hydraulic fluid. A control unit controls the at least one valve to control a flow of hydraulic fluid through each of the first, second, and third outlets based at least in part on a signal received from a pressure sensor. Methods of controlling the hydraulic systems are also disclosed.