JPS6220960B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable pitch mechanism for a rotor blade.

By adjusting the pitch of the rotor blades of aircraft propellers, helicopter rotors, ship propellers, industrial fans, wind turbines, etc., thrust, absorption torque, air volume, etc. can be easily controlled, significantly improving performance characteristics. For this purpose, variable pitch mechanisms have traditionally been used for rotor blades, but conventional variable pitch mechanisms are mainly mechanical motion mechanisms that combine cams, links, or gears. It is used in Therefore, variable pitch mechanisms, especially those with multiple blades and propellers, are generally complex mechanisms, which pose various problems such as weight, space, and maintainability. In the present invention, a shank in the shape of a rod with an oval cross section twisted around its axis is fixed concentrically to the pitch conversion axis at the base of a blade rotatably attached to a hub, and the shank is Fitted into a guide groove having a width corresponding to the short axis length of the cross-sectional ellipse of the shank, which is bored in a hollow conical body that is arranged concentrically with the rotation axis of the rotor blade and can move forward and backward in the axial direction. The above problem is solved by providing the blade so that it can rotate around its pitch conversion axis in response to the advance and retreat of the hollow cone. It is an object of the present invention to provide a variable pitch mechanism that is small in number, has high strength, high precision, and operates smoothly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The variable pitch mechanism for a rotor blade according to the present invention will be explained in detail below based on the drawings.

Fig. 1 is a partially sectional front view showing one embodiment of the variable pitch mechanism of the present invention, Fig. 2 is a partially sectional side view taken along line A--A in Fig. It is a partially enlarged view for explanation of the second part of the shank inside, and B is a sectional view of A.

1 is a blade, and its pitch conversion shaft 1' is connected via a thrust bearing 3 disposed on the outer periphery of its base.
It is supported on the hub 6 so that it can freely rotate around the . 2 is a shank, as shown in FIG. It is formed in the shape of a bar twisted spirally around its axis, and is fixed concentrically to the pitch conversion axis 1 at the base of the blade 1, as shown in FIG. 3A. 4 is a hollow cone (the one shown is a cone, but a pyramid can also be used), which is arranged concentrically with the rotation axis 8 of the rotor;
It is provided so that it can be moved back and forth in the axial direction by an actuator 7. 5 and 5' are guide grooves bored on the circumferential surface of the hollow conical body 4, and have a width corresponding to the length of the short axis of the ellipse in the cross section of the shank 2,
When the guide groove 5 is bored along the generatrix of the cone 4 (the line of intersection between the circumferential surface and the plane containing the axis), the guide groove 5' (shown by a chain line in Fig. 1) is formed along the generatrix of the cone 4. On the other hand, the cases in which the holes are drilled diagonally are shown. As shown in the figure, the guide grooves 5 and 5' are bored at positions corresponding to each of the plurality of blades 1 supported on the hub 6, and the shank 2 fixed to each blade 1 is bored at a position corresponding to each of the blades 1 supported on the hub 6. The guide grooves 5 and 5' are arranged to fit into and engage with each other. An actuator 7 is provided to advance and retreat the hollow cone 4 in its axial direction, and when a guide groove 5' is provided, the cone 4 moves freely around its axis at the same time as it advances and retreats. (The rotation mechanism is not shown).

Next, the operation of the variable pitch mechanism of the present invention will be explained.

When the actuator 7 is actuated to move the hollow cone 4 in the direction of the arrow in FIG.
The shank 2 inserted into the guide grooves 5 and 5' rotates in the direction of the arrow in accordance with the deviation of the insertion position due to the movement of the cone-shaped body 4 (the shank 2 moves to its insertion position). It rotates while being guided by the guide grooves 5, 5' so that the long axis of its cross section coincides with the center line of the guide grooves 5, 5'. Therefore, the blade 1 with the shank 2 fixed to its base rotates around 1' of the pitch conversion axis to change the pitch. Similarly, by actuating the actuator 7 in the opposite direction, the pitch of the blade 1 can be changed in the opposite direction.

In addition, when the guide groove is bored obliquely to the generatrix like the guide groove 5', the pitch conversion speed can be arbitrarily adjusted by selecting the inclination angle. This has many advantages over the case where the guide groove is bored along the generatrix, such as the equal guide groove 5, which allows the size to be reduced.

As explained above, the variable pitch mechanism for rotor blades of the present invention has the disadvantages of a complicated mechanism requiring a large number of parts, weight, and
By solving various problems such as space issues, accuracy, strength, and maintainability, the structure originally described was extremely simple, had a small number of parts, and was highly accurate.
This completely achieves the intended purpose of providing a variable pitch mechanism with high strength and smooth operation.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing an embodiment of the variable pitch mechanism for a rotor blade according to the present invention, FIG. 2 is a cross-sectional side view taken along line A-A in FIG. This is a partially enlarged explanatory view of the shank 2 in the figure, and (b) is a sectional view of the shank 2. Explanation of the symbols in the drawings below: 1: Blade;
1': pitch conversion axis of blade 1, 2: shank, 3: thrust bearing, 4: hollow cone,
5: Guide groove, 5': Guide groove (indicated by chain line), 6:
Hub, 7: Actuator, 8: Rotating shaft of rotor blade.

Claims (1)

[Claims] 1. A plurality of blades are mounted on a hub so that they can freely rotate around their pitch conversion axis, and a shank in the shape of a rod with an oval cross section twisted around the axis is attached to the base of each of the blades. The shank is fixed concentrically to its pitch conversion axis, the shank is arranged concentrically with the rotation axis of the rotor blade, and the shank is bored into a hollow conical body that can move forward and backward in the axial direction. Insert and engage into a guide groove having a width corresponding to the short axis length,
A variable pitch mechanism for a rotor blade, characterized in that the blade is provided so as to be able to rotate around its pitch conversion axis in response to the advance and retreat of the hollow cone.