JPS6337000B2 - - Google Patents

Description

[Detailed Description of the Invention] Field of Application The present invention relates to a pitch conversion mechanism that automatically adjusts the blade angle, or pitch, of a rotor blade, and the difference between the thrust set as the power of the variable pitch and the thrust generated by the rotor blade. Regarding the variable pitch mechanism used.

Background technology Aircraft propellers, helicopter rotors,
By adjusting the pitch of rotor blades such as marine propellers, industrial fans, and wind turbines,
Since thrust, absorption torque, air volume, etc. can be easily controlled, its performance characteristics can be significantly improved.

There are a wide variety of variable pitch mechanisms, and they use electricity and hydraulic power for power, and mechanical movement mechanisms that combine cams, links, gears, etc. are mainly used in terms of structure.

As a conventional variable pitch mechanism, U.S. Patent No.
No. 4037986 discloses that a variable pitch actuator including a piston, etc., and a spring are built into a cylindrical portion of a hub that rotatably supports a plurality of blades, and hydraulic pressure is supplied to a chamber on the right side of the piston to control the piston. A configuration has been proposed in which the pitch of the blade is changed using a crank pin depending on the amount of movement. However, in order to supply hydraulic pressure, a seal is installed on the outer periphery of the piston, and guides and ports for accommodating the plunger and springs must be machined, resulting in a complex structure that requires a large number of man-hours for processing and assembly, making it difficult to maintain. I had a bad problem.

Furthermore, in Japanese Patent Publication No. 47-4669, a yoke is attached to a shaft that forms part of a piston, and the pitch is changed by causing the propeller to rotate by the reciprocating motion of the piston, by making the yoke cooperate with a roller eccentrically connected to a propeller blade. A variable pitch mechanism has been proposed, but the structure is complicated and there are problems in that there is no space that can be used effectively in the boss or cylinder.

In addition, Japanese Patent Publication No. 46-3427 discloses a disk-shaped spring element that is installed concentrically within a dome structure that extends forward of the hub to change the load force according to the stroke of the piston. A variable pitch mechanism has been proposed, but it requires a mechanism in which an axial cam element is placed between the piston and the spring group structure, and the ring element is compressed by a bell crank, a spring seat, and an inclined portion of the cam. The problem was that the structure was complex and the number of parts was large, making it easy for failures to occur.

Therefore, the variable pitch mechanism generally has a complicated structure, which causes problems such as weight and space, and ease of maintenance becomes an important issue.

Purpose of the Invention In view of the above-mentioned current situation, it is an object of the present invention to provide a variable pitch mechanism with a small size and simple structure. The purpose of this invention is to create a variable pitch mechanism that makes it possible to directly control thrust or automatically control speed in response to fluctuations in thrust by changing the set thrust value.

Composition of the Invention The present invention comprises: a hub that supports a plurality of blades radially; a cam that is inserted into the hub and is movable parallel to the hub in the direction of a propeller's rotational axis, but is not rotatable; A predicted optimum pitch angle can be obtained by connecting the cam grooves provided on the cam surface for inserting and restraining pins that are eccentrically provided on the lower end surface of the blade, and the inner tip of the hub and the cam. A linear actuator that is extendable and retractable in the direction of the rotation axis so as to generate a force that balances the propeller thrust and the spring force at the cam position; It is composed of a spring that expands and contracts, and by moving the blade relative to the cam groove, the relative linear movement of the hub and cam in the direction of the propeller rotation axis is converted into rotational force around the pitch conversion axis, allowing pitch conversion. A rotor blade variable pitch mechanism characterized by the following.

That is, in this invention, an eccentric pin is provided on the end face of the blade that is radially fixed to the hub, and the pin is restrained in the cam groove, so that the relative longitudinal movement of the hub and the cam is controlled around the pitch conversion axis. Based on the mechanism that converts pitch into rotational movement, the pitch is changed by moving the blade against the cam groove by using the difference between the set thrust and the thrust generated by rotation of the blade. The gist is that.

DISCLOSURE OF THE INVENTION BASED ON DRAWINGS The drawing is a longitudinal sectional view of a hub showing a rotor blade pitch conversion mechanism according to the present invention.

The hub 1 has a cylindrical shape with a closed tip, and has a plurality of blades 3 radially supported on its outer peripheral surface by bearings 2.

The cam 6 has a cylindrical shape and is housed inside the hub 1, and has cam grooves 7 of a predetermined shape, the number of which is equal to the number of three blades, bored on its outer peripheral surface.

A pin 4 is provided on the lower end surface of each blade 3 eccentrically with respect to the center of the pitch conversion axis, and a sleeve 5 is loosely fitted onto the pin 4 and inserted into the cam groove 7.

The cam groove 7 is connected to the blade 3 by the inserted pin 4.
When the hub 1 and cam 6 move relative to each other in the direction of the propeller rotation axis, the blade 3 is rotated by the pin 4 that moves along the groove 7 formed into a predetermined shape, and the pitch is changed.

This cam 6 is provided with a disk-shaped connecting portion 8 on its rear end surface, and is connected and fixed to an output shaft (not shown) of the engine.

Further, the hub 1 rotates together with the cam in response to engine output, and is supported by an output shaft or a connecting portion 8 of the cam so as to be able to move back and forth in the axial direction with respect to the cam 6.

In order to enable the hub 1 and the cam 6 to move relatively in parallel in the direction of the propeller rotation axis and to transmit the rotational force of the engine output shaft, there is a gap between the connecting portion 8 of the hub 1 and the cam 6 or between the hub 1 and the engine output shaft. A slidable portion is provided in between to connect and support.

For example, the left end of the hub 1 in the figure is connected to the engine output shaft by a spline so as to be able to directly transmit rotational force, or as shown in the figure, the hub 1 is supported by a spline to the connecting part 8 of the cam, and the blade is connected to the engine output shaft by receiving the engine output. 3 is configured to rotate.

In the embodiment, a spline is provided between the connecting portion 8 of the hub 1 and the cam 6.

Therefore, the hub 1 and the cam 6 may be supported and connected in any manner as long as they are relatively movable in the direction of the propeller rotation axis.

Further, the hub 1 is connected between its tip and a connecting portion 8 of the cam 6 via a linear actuator 9.

In the drawing, the head of the hydraulic cylinder tube is connected to the connecting portion 8, and the tip of the rod 10 is connected to the hub 1.

Further, a spring 13 is fitted between a pedestal 11 provided around the inside of the closed tip of the hub 1 and a seat 12 provided at the tip end of the cam 6.

Next, the operation and function of the variable pitch mechanism of the present invention constructed as described above will be explained.

First, the blade 3 rotates in response to the output of the engine and generates thrust, and when the thrust exceeds the set thrust, the spring force from the spring 13 is also added, causing the blade 3 to move forward.

As the blade 3 moves forward, the pin 4 restrained by the cam groove 7 rotates the blade 3 along the shape of the groove 7, and the pitch changes to the high pitch side.

Therefore, the torque generated by the rotor increases,
The rotational speed of the rotor blades decreases, resulting in a decrease in thrust.

Next, contrary to the above process, when the hub 1 moves backward, the cam groove 7 rotates the pin 4 of the blade restrained by the groove, and the cam groove 7 rotates the blade 3 toward the lower pitch side. is configured, so
A predetermined amount of pitch transformation is performed.

For example, if you set the necessary thrust according to the flight conditions and determine the output of the linear actuator 9,
The hub 1 is positioned at a position where the output of the linear actuator 9, the thrust force, and the spring force of the spring 13 are balanced.
is stopped and the desired pitch transformation is performed.

That is, the balance equation of the force of the hub in the direction of the propeller rotation axis is expressed as follows.

F=T+kx ………(1) Formula F: Output by linear actuator T: Propeller thrust T=T (β, V, ρ) β: β(x) Blade angle V: Aircraft speed ρ: Air density kx : Spring force k : Spring constant x : Spring elongation In other words, the amount of relative movement between the hub and the engine output shaft In the case of a very simple propeller system, the output of the linear actuator 9 is
Several points, such as landing, are selected by pilot operation.

In more advanced propeller systems, the value of F is determined moment by moment by a computer and varied over time in order to obtain the optimum pitch angle of the propeller depending on the flight conditions (aircraft speed, altitude, engine output).

The thrust value T can be calculated from the aircraft speed V, air density ρ, blade angle β, etc. based on the flight conditions.

Since the thrust value T depends on the rotation angle of the blade 3 around the pitch conversion axis, the output F of the linear actuator 9 is determined so as to maintain a predetermined rotation angle.

The linear actuator 9 is actuated by determining the extension of the spring, that is, the relative movement amount x between the hub 1 and the engine output shaft so that the above equation (1) holds true.

Effects of the Invention That is, the mechanism of the present invention can automatically control the thrust force directly or adjust the speed for thrust fluctuations by selecting the cam groove shape, the output of the actuator, and the spring force.

Moreover, as described in detail, the variable pitch mechanism has a very simple structure, so it has the effect of reducing weight, being able to be installed without being limited by space within the hub, and facilitating maintenance.

By adopting the configuration of the present invention as described above, in particular, by connecting the cam and the tip of the hub via a linear actuator, the following effects can be obtained compared to the conventional variable pitch mechanism.

It is possible to secure a large amount of space within the hub 1 and cam 6 that can be used effectively.

Since the cam 6 is directly moved in the axial direction by the linear actuator 9, the configuration is simple, and even in the event of a failure, it is only necessary to replace the actuator.

By actuating the cam 6 with the linear actuator 9, torque transmission efficiency is good and delay in operation time is less likely to occur.

Since pitch conversion is possible with a single actuator, it is easy to reduce the size and weight, and it is possible to reduce manufacturing costs.

Since the spring 13, actuator 9, cam 6, etc. are arranged at the tip of the hub 1,
It is easy to downsize, disassemble and reassemble for maintenance and inspection, and has excellent maintainability.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of a hub showing a rotor blade pitch conversion mechanism according to the present invention. 1...Hub, 2...Bearing, 3...Blade, 4...Pin, 5...Sleeve, 6...Cam,
7...Cam groove, 8...Connecting portion, 9...Linear actuator, 10...Rod, 11...Pedestal,
12...Catch, 13...Spring.

Claims (1)

[Scope of Claims] 1. A hub that supports a plurality of blades radially; a cam that is inserted into the hub and is movable parallel to the hub in the direction of the propeller rotation axis, but is not rotatable; A predicted optimum pitch angle can be obtained by connecting the cam grooves provided on the cam surface for inserting and restraining pins that are eccentrically provided on the lower end surface of the blade, and the inner tip of the hub and the cam. A linear actuator that is extendable and retractable in the direction of the rotation axis so as to generate a force that balances the propeller thrust and the spring force at the cam position; It is composed of a spring that expands and contracts, and by moving the blade relative to the cam groove, the relative linear movement of the hub and cam in the direction of the propeller rotation axis is converted into rotational force around the pitch conversion axis, allowing pitch conversion. A rotor blade variable pitch mechanism characterized by the following.