WO2008020683A1

WO2008020683A1 - Main rotor assembly for helicopter

Info

Publication number: WO2008020683A1
Application number: PCT/KR2007/003696
Authority: WO
Inventors: Ho-Chul Cha
Original assignee: Dada Aviation Industry Co., Ltd
Priority date: 2006-08-14
Filing date: 2007-08-01
Publication date: 2008-02-21

Abstract

The present invention provides a main rotor assembly for a helicopter that can easily generate lift forces and improve output and flight stability. The main rotor assembly for a helicopter includes a mast that is provided to stand in a helicopter body and is supplied with power from an engine so as to be rotated, a plurality of blades provided along the circumference of the mast so that pitches are adjusted to generate lift forces during the rotation of the mast, first and second swash plates provided to the mast so as to become horizontal or inclined in one direction, a plurality of control rods connecting the blades to the swash plates so that pitches of the plurality of blades change when the posture of the swash plates changes, and a plurality of push rods that are supplied with power from a driving source and make the two swash plates horizontal or inclined in one direction.

Description

[DESCRIPTION] [Invention Title]

MAIN ROTOR ASSEMBLY FOR HELICOPTER [Technical Field] The present invention relates to a main rotor assembly for a helicopter. More particularly, the present invention relates to a main rotor assembly for a helicopter that can minimize the occurrence of stall regions during flight so as to improve flight stability and output performance.

[Background Art] In general, when a mast is supplied with power from an engine and rotated in one direction, lift forces are generated by a plurality of blades. Accordingly, a helicopter can vertically take off and land, hover, and fly in any direction.

The above-mentioned flight of a helicopter is achieved by the operation of a swash plate that is provided to the mast. When the mast is rotated by 360 degrees, the swash plate continuously changes pitches of the blades so that lift forces required for flight are generated.

For example, when a helicopter takes off or hovers, the swash plate operates so as to become horizontal. Accordingly, the pitches of the blades on the mast are uniformly maintained and gravity is offset.

Then, when the swash plate is inclined in one direction, the pitch angles of the blades provided on the front side in a flight direction are decreased and the pitch angles of the blades provided on the rear side are increased. For this reason, the helicopter body is inclined toward the front side, and a difference between the lift forces at the front and rear sides causes a driving force. As a result, a helicopter flies forward. That is, when a helicopter is steered forward, the swash plate is inclined toward the front side of the helicopter body. Accordingly, due to the link operation of control rods, the pitch angles of two blades rotated together with the mast or blades passing two positions (right and left positions) periodically change so as to increase at one position and decrease at the other position.

The blades, of which the pitches change as described above, generate lift forces at the front and rear sides according to a principle of gyro precession. In particular, when the lift force at the rear side is larger than that at the front side, the helicopter can fly forwards. [Disclosure]

[Technical Problem]

However, since the mast of the helicopter in the related art is provided with one swash plate, lift forces required for flight are generated while pitches of the blades passing two positions (right and left positions of the body) change. For this reason, it is not possible to efficiently generate lift forces. That is, since the lift forces are generated at only the front and rear sides by the blades passing two positions (right and left positions of the body), it is not possible to secure a satisfactory output performance that is required to increase speed during flight and stall regions easily occur at the rear region of the blades. When the blades to be rotated by the mast rearward move from the front side to the rear side, the stall regions cause loss of the lift forces and speed due to headwind corresponding to the flight speed of the body.

Further, since the headwind causes sway or vibration of the body during flight, flight stability deteriorates and it is difficult to secure output performance corresponding to maximum constant flight speed (about 150 knots). The present invention has been made in an effort to provide a main rotor assembly for a helicopter having the advantage of minimizing stall regions occurring during flight so as to achieve satisfactory flight speed and flight stability. [Technical Solution] An exemplary embodiment of the present invention provides a main rotor assembly for a helicopter that includes: a body; a mast that is provided in the body and supplied with power from an engine so as to be rotated; a plurality of blades provided along the circumference of the mast so that pitches are adjusted to generate lift forces during the rotation of the mast; two swash plates provided to the mast so as to become horizontal or to be inclined in one direction; a plurality of control rods connecting the blades to the swash plates so that pitches of the plurality of blades change when the posture of the swash plates changes; and a plurality of push rods that are supplied with power from a driving source and make the two swash plates horizontal or inclined in one direction. [Advantageous Effects]

According to the present invention, since the main rotor assembly for a helicopter generates lift forces at four regions of the entire rotation region of the mast, it is possible to increase flight speed and to solve various problems occurring due to stall regions. Therefore, it is possible to obtain further improved flight safety.

[Description of Drawings] FIG. 1 is a schematic side view of a main rotor assembly for a helicopter according to an exemplary embodiment of the present invention.

FIG. 2 is a schematic plan view of the main rotor assembly for a helicopter according to the exemplary embodiment of the present invention. FIG. 3 is a perspective view of a main rotor assembly for a helicopter according to another exemplary embodiment of the present invention.

FIG. 4 is a view illustrating operation of swash plates shown in FIG. 3.

FIG. 5 is a view illustrating a control rod connection structure shown in FIG. 3.

FIG. 6 is a view illustrating operation of the main rotor assembly for a helicopter according to the exemplary embodiment of the present invention.

FIG. 7 is a view illustrating lift forces generated when the main rotor assembly for a helicopter according to the exemplary embodiment of the present invention is driven and distribution of the lift forces. [Best Mode]

Preferred exemplary embodiments of the present invention will be described below with reference to the accompanying drawings. Exemplary embodiments of the present invention will be described to be embodied by those skilled in the art. Accordingly, since exemplary embodiments of the present invention may be modified in various ways, the appended claims of the present invention are not limited to the exemplary embodiments.

FIG. 1 is a view showing the entire structure of a main rotor assembly for a helicopter according to an exemplary embodiment of the present invention, with reference numeral 2 indicating a helicopter body.

As shown in FIG. 1 , the helicopter body 2 may have a general structure that includes a nose 2a formed at the front side and a tail 2b formed at the rear side. A tail rotor 2c is provided at the tail 2b, and the tail rotor 2c is a variable-pitch rotor as already known. The tail rotor offsets a reaction torque, which is applied to the body 2 during flight, to adequately control the altitude and direction of the body 2. While vertically passing through a roof panel, a mast R is fixed to the body 2. Although not shown in the drawings, the mast R is supplied with power from an engine and rotated about an axis thereof in a clockwise direction or a counterclockwise direction while vertically provided as described above. As shown in FIG. 2, a general rotor head R1 including a rotor hub is provided at the end of the mast R, and blades B1 , B2, B3, and B4 are fixed to a plurality of blade grips R2 that are formed on the circumference of the rotor head R1 , respectively.

As shown in FIG. 3, each of the blade grips R2 is fitted to the rotor head R1 so that an angle of each of the blade grips R2 with respect to the rotor head R1 can be changed. The blade grips R2 can be fixed to the rotor head R1 by a general method so as to change the pitch of each of the blades B1 , B2, B3, and B4.

Each of the blades B1 , B2, B3, and B4 has a general structure to generate a lift force when being rotated together with the mast R.

Meanwhile, the mast R is provided with a first swash plate 4 and a second swash plate 6, and the two swash plates 4 and 6 are fixed to the mast R with a predetermined space therebetween in a vertical direction as shown in FIG. 3.

Each of the first and second swash plates 4 and 6 includes a rotary plate S1 and a stationary plate S2, and a general bearing K1 is provided in each of the first and second swash plates 4 and 6 so that the rotary plate S1 is rotated in the stationary plate S2.

Further, for example, a general bearing member K2, which is able to rotatably connect elements to each other while spherically contacting an element, is provided between each of the rotary plates S1 and the external circumferential surface of the mast R. Accordingly, as shown in FIG. 4, the two swash plates 4 and 6 can become horizontal or inclined in one direction.

The rotary plates S1 are fixed to the mast by fasteners K3 such as general scissors links so as to be rotated in the same direction when the mast R is rotated. That is, when the mast R is driven, the swash plates 4 and 6 are rotated in the same direction and the stationary plates S2 are not rotated. Accordingly, the rotary plates S1 are rotatably supported while being horizontal or inclined in one direction.

The first and second swash plates 4 and 6 are connected to the four blades B1 , B2, B3, and B4, which are connected to the rotor head R1 , by control rods C1 , C2, C3, and C4 so as to change the pitch.

The first swash plate 4 may be connected to two blades B1 and B3 among the four blades B1 , B2, B3, and B4, which are connected to the mast R, by control rods C1 and C3. The second swash plate 6 may be connected to the other two blades B2 and B4 by control rods C2 and C4 (see FIGS. 3 and 5).

The control rods C1 , C2, C3, and C4 may be connected to the rotary plates S1 of the swash plates 4 and 6 and the blades B1 , B2, B3, and B4 by hinges.

When being connected to the rotary plates S1 of the swash plates 4 and 6 and the blades B1 , B2, B3, and B4, the four control rods C1 , C2, C3, and C4 are disposed among the blades B1 , B2, B3, and B4 as shown in FIG. 5.

Each of the control rods C1 , C2, C3, and C4 has a general structure for connecting the two swash plates 4 and 6 with the blades B1 , B2, B3, and B4 so that the control rods are parallel to the blades and a distance between the swash plates 4 and 6 can be adjusted. The two control rods C2 and C4, which are connected to the second swash plate 6 provided at a lower portion of the mast R, pass through the first swash plate 4 and move in the vertical direction as shown in FIG. 3.

The four control rods C1 , C2, C3, and C4 are divided into pairs (C1 and C3 / C2 and C4). The control rods may be set so that a pitch angle of one of the blades B1 and B3 / B2 and B4, which are connected to the two swash plates 4 and 6 and face each other, is increased due to a downward force, and a pitch angle of the other blade is decreased due to an upward force (when the mast is rotated in the clockwise direction in FIG. 5).

Although not shown in the drawings, the control rods may be connected to have an opposite operation to the above-mentioned connection structure. For example, when each of the swash plates 4 and 6 is inclined in one direction, a pitch of one blade is decreased due to a downward force and a pitch of the other blade is increased due to an upward force.

It is possible to achieve the above-mentioned setting structure by properly determining positions, where the control rods C1 , C2, C3, and C4 are connected to the blade grips R2 fixed to the blades B1 , B2, B3, and B4.

The two swash plates 4 and 6 are supplied with power from a plurality of push rods P1 , P2, P3, and P4, and then change the posture thereof.

As shown in FIG. 3, the plurality of push rods P1 , P2, P3, and P4 are divided into pairs (P1 and P3 / P2 and P4) so as to correspond to the positions where the control rods C1 , C2, C3, and C4 are connected to the swash plates 4 and 6. The push rods may be connected to the stationary plates S2 by hinges.

While operating to descend one point of the swash plate 4 or 6 connected to the push rods and lift the other point of the swash plate 4 or 6 connected to the push rods, the push rods P1 , P2, P3, and P4 can change the posture of the swash plate 4 or 6 so that the swash plate becomes horizontal or inclined in one direction. Although a general driving source is not shown in the drawing, the push rods P1 , P2, P3, and P4 may be supplied with hydraulic pressure from the general driving source provided in the body 2 so as to operate.

Accordingly, while the posture of each of the swash plates 4 and 6 is changed by the up-and-down movement of the push rods P1 , P2, P3, and P4, it is possible to change the pitch angle of each of the blades B1 , B2, B3, and B4.

Next, the operation of the main rotor assembly for a helicopter according to the exemplary embodiment of the present invention will be described. In this exemplary embodiment, a case where the mast R is rotated in a clockwise direction and the main rotor assembly operates for a forward flight will be described by way of example.

In FIG. 6, when one rod (P1) of the two push rods P1 and P3 connected to the first swash plate 4 moves down and the other rod (P3) thereof moves up, a portion of the first swash plate 4 connected to the rod (P1 ) moving down is inclined downward.

When one rod (P2) of the two push rods P2 and P4 connected to the second swash plate 6 moves down and the other rod (P4) thereof moves up, a portion of the second swash plate 6 connected to the rod (P2) moving down is inclined downward.

When the mast R is driven in this case, the stationary plates S2 of the swash plates 4 and 6 are fixed to the push rods P1 , P2, P3, and P4 and thus not rotated. The rotary plates S1 provided in the stationary plates S2 are rotated in the same direction as the mast R.

That is, the rotary plates S1 are supported by the stationary plates S2, and are rotated while being inclined. Accordingly, when passing the downward-inclined portions of the stationary plates during one rotation of the mast R, the control rods, which are divided into pairs (C1 and C3 / C2 and C4) and are fixed to the rotary plates S1 , move down. In contrast, when passing the portions of the stationary plates opposite to the downward-inclined portions, the control rods move up. Therefore, the control rods periodically move up and down. Due to the above-mentioned movement of the control rods C1 , C2,

C3, and C4, pitch angles periodically change as follows: when the pairs of blades B1 and B3 / B2 and B4 fixed to the swash plates 4 and 6 are rotated together with the mast R, two blades B1 and B2 passing the portions in FIG. 6 corresponding to the two push rods P1 and P2 have a maximum pitch and the other two blades B3 and B4 passing the portions corresponding to the other two push rods P3 and P4 have a minimum pitch.

Since the pitch angles periodically change as described above, a lift force generated by each of the blades B1 , B2, B3, and B4 becomes largest at a position that is rotated by 90 degrees from a pitch changing position, according to a principle of gyro precession.

That is, as shown in FIG. 7, four distribution regions A1 , A2, A3, and A4 of lift forces are formed along the circumference of the mast R by the blades B1 , B2, B3, and B4. Among the four distribution regions A1 , A2, A3, and A4 of lift forces, which are formed along the circumference of the mast R, the distribution regions A1 and A2, which are formed at the rear side of the body, are formed to be larger than the distribution regions A3 and A4, which are formed at the front side of the body 2, due to the difference between the maximum pitch angle and the minimum pitch angle of each of the blades B1 , B2, B3, and B4. As a result, a helicopter can fly forward.

According to the above-mentioned structure, it is possible to easily secure output required to increase flight speed, as compared to, for example, a rotor structure of a helicopter in the related art that generates lift forces by using one swash plate at two regions (front and rear sides of the body) along the circumference of a mast.

Particularly, since four distribution regions A of lift forces are formed along the circumference of the mast, it is possible to minimize stall regions that may be formed when each of the blades B1 , B2, B3, and B4 passes through the rear region. As a result, it is possible to secure flight safety as much as possible.

Although four blades B1 , B2, B3, and B4 have formed a group and been connected to the mast R in the exemplary embodiment, the present invention is not limited thereto.

For example, although not shown in the drawings, two or more blades may form a group and be connected to each of the swash plates 2 and 4 so that a pitch angle can change at four or more positions when four or more blades are connected to the mast R and rotated together with the

mast R.

the swash plates is connected to two or more blades so as to change a pitch thereof.

[Claim 4]

The main rotor assembly for a helicopter of claim 1 , wherein the control rods are connected so that a pitch of one of the blades facing each other with the mast interposed therebetween is increased and a pitch of the other thereof is decreased when each of the swash plates is inclined in one direction.

[Claim 5] The main rotor assembly for a helicopter of claim 1 , wherein one or more of the push rods form a group so as to correspond to the swash plates, and the push rods are connected to the two swash plates so that the two swash plates are inclined in different directions with respect to the mast.

[Claim 6]

The main rotor assembly for a helicopter of claim 1 , wherein the push rods operate so that one plate of the two swash plates is inclined at one point on the circumference of the mast and the other plate is inclined at a point rotated by 90 degrees.

15

Claims

[CLAIMS] [Claim 1 ]

A main rotor assembly for a helicopter, comprising: a body; a mast provided in the body, the mast being supplied with power from an engine and rotated; a plurality of blades provided along the circumference of the mast so that pitches are adjusted to generate lift forces during the rotation of the mast; two swash plates provided to the mast so as to become horizontal or to be inclined in one direction; a plurality of control rods connecting the blades to the swash plates so that pitches of the plurality of blades change when the posture of the swash plates changes; and a plurality of push rods that are supplied with power from a driving source and make the two swash plates horizontal or inclined in one direction.

[Claim 2]

The main rotor assembly for a helicopter of claim 1 , wherein four or more blades form a group.

[Claim 3] The main rotor assembly for a helicopter of claim 1 , wherein each of

14 the swash plates is connected to two or more blades so as to change a pitch thereof.

[Claim 4]

[Claim 6]

15