CN210106066U

CN210106066U - Passive pitch control system

Info

Publication number: CN210106066U
Application number: CN201821639302.3U
Authority: CN
Inventors: 陈春梅; 瑞恩·迈克·兰德
Original assignee: Qingdao Randall Aerodynamic Engineering LLC
Current assignee: Qingdao Randall Aerodynamic Engineering LLC
Priority date: 2017-09-25
Filing date: 2018-09-25
Publication date: 2020-02-21
Anticipated expiration: 2028-09-25

Abstract

The utility model discloses a become oar system passively, center on including main shaft and multi-disc the blade that the axis of main shaft distributes, its characterized in that still includes: a resilient movement diverter mechanism for guiding the deflection of the vanes as they move relative to the vane cavity housing and for applying a resilient force to the vanes; a generator, or an electric motor, or an engine, connected to the rotating shaft. The system can automatically obtain the optimal combination of the pitch angle and the rotation speed of different types of turbomachines, and the pure mechanical structure is not influenced by power failure, inaccuracy of an anemometer or user error, so that the reliability, the rigor and the control efficiency of the system are enhanced, and the defects of extreme complexity and high cost of the conventional active control system are overcome.

Description

Passive pitch control system

Technical Field

The utility model relates to a blade technique especially relates to a become oar system passively.

Background

At present, apparatuses that use rotating blades to achieve power input or power output are widely used, for example: the wind power generation device is widely used in wind power generators, water turbines, screw propellers, turbines, rotary wheel machines and other equipment. Wherein the pitch angle of the blades typically needs to be adjusted for different flow rates, as the blades are influenced by the velocity of the fluid (gas or liquid) during rotation. In the prior art, the pitch angle of the blade is usually adjusted by electronic control, and the wind speed is detected by using a computer system to adjust the pitch angle of the blade. However, these rely on several subsystems, such as computers, software, anemometers, thermometers, etc., which are susceptible to errors and faults, resulting in a very complex overall system with low reliability and high manufacturing and maintenance costs. How to design a high, with low costs passive variable pitch system of reliability is the utility model discloses the technical problem that will solve.

SUMMERY OF THE UTILITY MODEL

The utility model discloses the technical problem that will solve is: the passive variable pitch system is provided, the defects of low reliability and high cost of an automatic variable pitch system in the prior art are overcome, the reliability of the automatic variable pitch system is improved, and the manufacturing cost and the maintenance cost of the automatic variable pitch system are reduced.

The technical scheme provided by the utility model, a take passive oar system that becomes of counter weight device, center on including main shaft and multi-disc the blade that the axis of main shaft distributes still includes:

a resilient movement steering mechanism for guiding the blade to turn about its own centre line to change pitch angle upon longitudinal movement of the blade relative to the blade cavity shell, and for applying a resilient force to the blade;

the blade counterweight component is used for offsetting the component influence of the gravity of the blade in the direction of the center line of the blade during the rotation of the blade.

A generator, or an electric motor, or an engine, connected to the rotating shaft.

The blade cavity shell is arranged on the main shaft and used for mounting the blade, and when the blade rotates to cause the centripetal force of the blade to change, the blade can move on the blade cavity shell along the longitudinal axis of the blade.

Further, the blade counterweight assembly comprises an annular guide rail and a gravity roller, the center of the annular guide rail is located above the axis of the main shaft, each blade is provided with the gravity roller, the elastic member is connected between the gravity roller and the blade, and the gravity roller is arranged in the annular guide rail in a rolling or sliding mode.

Further, the mobile steering mechanism includes a slide groove and a guide member provided in the slide groove.

Further, the sliding groove is arranged in the blade cavity shell, and the guide piece is arranged on the blade; alternatively, the runner is provided on the blade and the guide is provided on the blade cavity shell.

Further, the guide piece is a guide post or a sliding block or a shaft ring which is arranged on the sliding groove in a sliding mode.

Further, the guide member is a guide roller which can roll in the chute.

Furthermore, two or more blade cavity shells are distributed in the circumferential direction of the main shaft, a mounting hole is formed in each blade cavity shell, and the root of each blade is mounted in the mounting hole.

Further, a fixing ring is further arranged on the blade cavity shell, and the fixing ring is sleeved on the blade and fixed on the blade cavity shell; or the blade is also provided with a fixing ring, and the fixing ring is sleeved on the blade cavity shell and fixed on the blade.

Further, the elastic member is a member that generates a restoring force to resist deformation when subjected to tension, compression, rotation, or torsion, and includes a spring.

Further, the outer diameter of the blade cavity shell is smaller than the inner diameter of a blade root of the blade, and the blade root can slide on the outer surface of the blade cavity shell; alternatively, the inner diameter of the blade cavity shell is larger than the outer diameter of a blade root of the blade, which can slide in the blade cavity shell.

Further, the blade cavity shells are fully or partially housed inside the central hub, and may also be fully outside the central hub.

Further, linear bearings or ball bearing arrays are used on the blade root or blade cavity shell.

Compared with the prior art, the utility model discloses an advantage is with positive effect: the passive variable-pitch system provided by the utility model applies elastic force to the blades through arranging the elastic component, in the process of the change of the rotating speed of the blades, the centrifugal force generated by the blades is changed, so that the elastic force exerted by the elastic component on the blades is different, and under the condition of different rotating speeds of the blades, moves along the direction vertical to the axis of the main shaft relative to the blade cavity shell, at the moment, the blades are guided by matching with a moving steering mechanism, so that the blades rotate when moving, thereby automatically adjusting the pitch angle to achieve an automatic configuration of the optimum pitch angle for each blade rotation rate, the automatic adjustment of the blade pitch angle is realized by matching the elastic component with the movable steering mechanism in a mechanical mode, a complex electronic control system is not required to be configured, the operation reliability is better, and the whole system is simple in structure and low in manufacturing cost and maintenance cost.

To sum up, compare with prior art, the utility model discloses an advantage summarizes as follows:

1) it is relatively simple.

2) Is not affected by user error.

3) Is not affected by the loss of power.

4) Is not affected by computer failure or malfunction.

5) Immune to electronic subsystem failures or errors (e.g., anemometers).

6) The durability and the service life are extremely high.

7) And 3, low maintenance.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural view of a passive pitch system according to an embodiment of the present invention;

fig. 2 is a partial sectional view of an embodiment of the passive pitch system of the present invention;

fig. 3 is a partial exploded view of an embodiment of the passive pitch control system of the present invention;

FIG. 4 is an assembly diagram of the ring-shaped guide rail, the gravity roller and the spring according to the embodiment of the passive pitch control system of the present invention;

FIG. 5 is an assembly view of the ring-shaped guide rail and the main shaft of the embodiment of the passive pitch control system of the present invention;

FIG. 6 is a first assembly drawing of the ring-shaped guide rail and the gravity roller of the embodiment of the passive pitch control system of the present invention;

FIG. 7 is a second drawing of the assembly of the ring-shaped guide rail and the gravity roller of the embodiment of the passive pitch control system of the present invention;

FIG. 8 is a third assembly drawing of the ring-shaped guide rail and the gravity roller of the embodiment of the passive pitch control system of the present invention;

fig. 9 is a first schematic structural view of a ring-shaped guide rail according to an embodiment of the passive pitch control system of the present invention;

fig. 10 is a schematic structural view of a ring-shaped guide rail according to an embodiment of the passive pitch control system of the present invention;

fig. 11 is a schematic structural view of a ring-shaped guide rail according to an embodiment of the passive pitch control system of the present invention;

fig. 12 is a schematic structural view of a ring-shaped guide rail according to an embodiment of the passive pitch control system of the present invention;

fig. 13 is a schematic structural view of a ring-shaped guide rail according to an embodiment of the passive pitch control system of the present invention;

fig. 14 is a first schematic structural diagram of a gravity roller according to an embodiment of the passive pitch control system of the present invention;

fig. 15 is a schematic structural view of a gravity roller according to an embodiment of the passive pitch control system of the present invention;

fig. 16 is a third schematic structural view of the gravity roller according to the embodiment of the passive pitch control system of the present invention;

FIG. 17 is an assembled view of a blade hub and blade cavity shell;

FIG. 18 is a coordinate analysis view of a blade;

FIG. 19 is a force analysis diagram of a blade;

FIG. 20 is a coordinate analysis of a blade cavity shell.

Description of reference numerals: 1-blade, 2-blade cavity shell, 3-elastic component, 4-guiding piece, 5-sliding chute, 6-fixed ring, 7-blade root, 8-hub, 9-gravity roller, 10-annular guide rail, 11-motor/generator, 12-main shaft, 13-machine shell and 14-rotating cover.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

As shown in fig. 18, the centrifugal force acting on all the rotating blades is proportional to the square of the hub rotational speed. The higher the rotational speed, the higher the centrifugal force pulling the blades away from the hub. This centrifugal force is counterbalanced by a linear spring which elongates as the rotational speed increases. When the spring is stretched, the blade is rotated in its axial direction by the roller and the guide rail. The guide rails may be designed such that the blade pitch angle is strictly increased when the rotational speed is increased (for example for a propeller), or increased within a safe rotational speed range (for example for a turbine), and then decreased and/or reduced to zero when the rotational speed is increased too high.

A simple model of a hub homokinetic rotation system in the vertical plane can be derived for a typical wind turbine, various axial fans, propellers in horizontal linear flight, etc. The model can be used to analyze its dynamics and its behavior in order to make a more appropriate design for various applications.

One useful method is to define a ground-fixed coordinate system and a hub-fixed coordinate system, both coordinate systems having the same origin. XYZ denotes a coordinate system fixed to the ground, XYZ denotes a coordinate system fixed to the hub.

The X-axis is vertical, the Y-axis is out of the page, the Z-axis is horizontal, the Y-and Y-axes are always co-linear, but as the hub rotates, the X-and Z-axes change their orientation, denoted β, and the Z-axis is always directed towards the centerline of a blade cavity shell.

As shown in fig. 19, a free body diagram.

It is necessary to consider the forces and moments exerted on the blades to simulate and understand their blade movements, including their response to disturbances. These forces come from aerodynamic forces, gravity, roller and rail interaction forces, centrifugal forces, springs, and blade cavity shell interaction forces. Free body forces tend to help understand these forces and moments.

There are four key points, A, C, R and G. A is the aerodynamic center of the blade, which is the point of application of aerodynamic force and moment, and C is the center of mass of the blade, which is the point of application of centrifugal force and gravity. R is the reaction force/moment point of action and G is the circular cross-sectional center of the blade roll plane. It is assumed here that the aerodynamic forces in the z-direction are negligible, as are the aerodynamic moments acting in the x-axis and y-axis directions.

In addition, F denotes a force, and M denotes a moment. The subscript a denotes "aerodynamic", c denotes "centrifugal", g denotes "grooved", relates to the force or moment acting on the rail or groove, r denotes "reaction", s denotes "spring", x denotes "in x-direction", y denotes "in y-direction", and z denotes "in z-direction".

The design of the center rail and center roller is used to correct this cyclic effect, pushing up when the blade is at the top of the cyclic rotation and pulling up when the blade is at the bottom of the cyclic rotation_s0The effect of centrifugal force on gravity can be further increased by designing the material near the ends of the blades to have a higher density.

l is the length of the rope, m is the mass, g is the acceleration of gravity, the upper point represents the time derivative，

Is the angular velocity of rotation of the blade about the hub. A drone propeller radius is about 0.1m, with a corresponding "rope length" of about 0.035 m. When the small unmanned aerial vehicle flies, the rotating speed of the propeller can reach 78.5-130.9 rad/s; these frequencies should try to avoid the natural frequencies of the system. When simplifying the drone to point mass and rope, the gravity is 1.6% to 4.5% of the centrifugal force over the entire rotational speed range of the hub. In this case, the pitch angle fluctuations are slight, and it is feasible to omit the central roller and the central guide rail assembly. All systems rotating in the horizontal plane, or operating without the presence of gravity, can work well with the central guide and roller assembly omitted. As another example, consider a typical large wind turbine rotating at 1.05rad/s in a vertical plane, with blades 40 meters in length and a mass of 5500 kilograms. In this case, the gravity is 67% of the centrifugal force, and therefore the center rail and the roller assembly cannot be omitted.

The R point is drawn at the outer edge of the blade shell and at the center of the circular cross-section. The position of R is somewhat optional, since the exact value of a reaction force-moment system can be determined for any assumed point of application. The reaction torque and force are negligibly small in the z-direction (good lubrication, no friction). The spring force is also a result of the geometric analysis of point R.

The last key point is G, which is at the center of the circular cross-section of the plane in which the bladed roll lies. The force exerted on the blade roller can be reduced to a force and corresponding moment exerted on point G. It is assumed that the blade guide is deep enough to prevent the end of the blade roller from contacting the bottom of the blade guide, so that no force is applied to the blade roller in the sub-normal direction of the blade guide. Furthermore, the friction is neglected so that no forces are exerted on the blade roller in the tangential direction of the guide rail. Thus, the force that the guide rail can exert can be reduced to only a force in the direction of the guide rail normal

The index n indicates "normal", the arrow above indicates the vector, and ^ indicates the unit vector. Assuming a completely rigid blade, the equation of motion can be derived.

Equation of motion

(1)F_ax+F_rx+F_gx+W_x＝0

(2)F_ay+F_ry+F_gy＝0

(3)

(4)-F_ay·(z_A-z_R)+F_gy·(z_R-z_G)+M_rx＝0

(5)F_ax·(z_A-z_R)-F_gx·(z_R-z_G)+W_x·(z_C-z_R)+M_ry＝0

(6)

The six equations of motion have eight unknowns F_gx，F_gy，F_gz，M_gz，F_rx，F_ry，M_rx，M_ry(ii) a However, more equations can be derived by way of rail-roller interaction.

(7)

(8)

(9)

Three new ones are obtainedIn the equation, four new unknowns are included: f_g，But do not

Will be determined during the rail design process. Then F_gx，F_gyAnd F and_gzwill become an unknown function F_gWe have nine equations with nine unknowns, which is a solvable system with a unique solution.

As shown in fig. 20, the guide rails are designed to be oriented normal to the direction of the normal.

For this particular utility model, the guide rail design is novel. For convenience, a coordinate system with g subscripts is defined here and starts at the inner edge of the rail, so that z ═ z_g+z_g0And then:

each rail has a constant radial distance from the blade cavity shell centerline, so it is more convenient to use cylindrical coordinates.

r_g＝constant

Can be expressed as a variable z_gA function of (a), wherein the function theta_g(z_g) Determining when the blade has been pulled to a particular z_gPitch angle at position. For a particular blade design operating over a particular domain, several optimal rotation rate/pitch angle combinations may be calculated. Curve fitting can be applied to the optimal rotation rate/pitch angle in the domain to obtain θ_g(z_g). Conversion back to the cartesian coordinate master system fixed to the hub gives the following useful description of the guide rail:

next, we determine the curve length "s" of the guide, described as a function of z (the symbol "-" denotes the integral variable z, in order to distinguish it from the integral limit z)

Introduction of

Etc., the symbol' represents the differential with respect to z, and we determine the unit normal vector as:

acting force and moment

Aerodynamic force

For propellers or turbines, it is usually possible to design around the center value () of flow rate, pitch angle, rotational speed, etc. to meet their efficient operation. Its aerodynamics are then characterized and modeled, including the variation of different parameters and dimensionless coefficients in the application domain. These models are synthesized into the equations of motion of the passive pitch control system.

The centrifugal force is described by the following formula:

where m is the mass of the blade,is the rotational speed of the hub, z_cIs the position of the center of mass of the slice, and is

As a function of (c).

Weight:

if the hub is rotated in a vertical plane, its weight will have no y-component. In this case, the weight-induced forces in the hub-fixed coordinate system will depend on the angle of rotation of the blade, as follows:

W_x＝-W·sin(β)

W_z＝-W·cos(β)

a spring:

if the spring is linear over its working range, the force it exerts on the blade is modeled as:

where k is the linear spring constant, z_s0Is the z position corresponding to a vane roller with zero spring compression or extension. z is a radical of_s0Is a known function of hub rotation angle β, designed to offset the weight W of the blade in the z-direction_z. A change in pitch of the blade will cause the spring to twist and elongate. If the torque is large enough, the coupling is neglected, and the torque generated by the torsion is assumed to be linear, then:

wherein tau is_sIs the torsion spring constant, θ_s0Is the pitch angle corresponding to zero spring torsion.

Roller and reaction force/moment:

using the equations of motion previously derived, the net reaction forces and moments exerted on the blades can be determined.

As shown in fig. 1 to 17, a specific structure of the passive pitch system according to the present embodiment is described with reference to the accompanying drawings:

the passive pitch control system of this embodiment includes blade 1, hub 8 and main shaft 12, hub 8 is fixed on main shaft 12, still includes:

a blade cavity shell 2 arranged on the hub 8 for mounting the blade 1, wherein when the blade 1 rotates to cause the centripetal force of the blade 1 to change, the blade 1 can move on the blade cavity shell 2 along the longitudinal axis of the blade 1;

an elastic member 3 provided in the blade cavity housing 2 for applying an elastic force to the blade 1;

a moving steering mechanism for guiding the blade 1 to turn around its own centre line to change pitch angle upon longitudinal movement of the blade 1 relative to the blade cavity shell 2;

the blade counterweight component is used for offsetting the component force influence of the gravity of the blade 1 in the direction of the center line of the blade 1 during the rotation of the blade 1.

Specifically, in the passive pitch system of the present embodiment, the blade 1, the hub 8 and the main shaft 12 rotate together, the root of the blade 1 is disposed in the blade cavity housing 2, the blade 1 can move back and forth in the axial direction perpendicular to the main shaft 12 relative to the blade cavity housing 2, and can rotate around its central line itself, the elastic member 3 applies an elastic force to the blade 1 to satisfy different rotation speeds, the blade 1 is in a state of force balance, the centrifugal force generated by the blade 1 due to the different rotation speeds of the blade 1 is different, the elastic force applied to the blade 1 by the elastic member 3 is also different, the elastic member 3 stretches and contracts under the different rotation speeds of the blade 1, so that the blade 1 moves in the blade cavity housing 2, and the moving and steering mechanism can guide the blade 1 to correspondingly rotate and deflect to change the pitch angle of the blade 1 during the movement of the blade 1, thereby satisfying that the pitch angle is matched with the rotating speed of the blade 1 to obtain higher efficiency. Compared with the prior art that the pitch angle is adjusted by adopting an electric control system, the automatic pitch-adjusting system of the embodiment realizes mechanical pitch angle adjustment by matching the elastic component 3 and the movable steering mechanism, and in the actual use process, the reliability of pure mechanical adjustment is higher, the whole structure is simple, and the manufacturing cost and the later maintenance cost are lower. The blade counterweight assembly may further include a stationary annular guide rail 10, a center of the annular guide rail 10 is located above an axis of the main shaft 12, each blade 1 is configured with a gravity roller 9, the elastic member 3 is connected between the gravity roller 9 and the blade 1, the gravity roller 9 is arranged in the annular guide rail 10 in a rolling manner, a plurality of blade cavity shells 2 are distributed in a circumferential direction of the hub 8, each blade cavity shell 2 is provided with a mounting hole, the blade root 7 of the blade 1 is mounted in the mounting hole, correspondingly, the elastic member 3 is connected to a root of the blade 1, and the elastic member 3 is also located in the mounting hole and connected to the gravity roller 9. Specifically, because blade 1 is in the rotation process, the position of blade 1 changes periodically, simultaneously, the influence of gravity of blade 1 also can change periodically along with the direction of its centrifugal force, in order to reduce the influence that blade 1 gravity produced to pitch angle adjustment in-process, the influence that gravity produced is subdued through the cooperation of eccentric annular guide rail 10 and gravity roller 9, specifically, when blade 1 rotates to the bottommost, the gravity of blade 1 is the same with the centrifugal force direction, the effort superposes, and when blade 1 rotated to the top, the gravity of blade 1 is opposite with the centrifugal force direction, the effort offsets. When the vane 1 is located at the lower region, gravity is superimposed on the centrifugal force, thereby increasing the force applied to the elastic member 3, increasing the tensile deformation of the elastic member 3 to move the vane 1 outward from the rotation center, and since the center of the annular guide rail 10 is offset from and located above the axis of the rotary shaft 12, the outward displacement of the vane 1 is offset, thereby maintaining the absolute position of the vane 1 in the vane axial direction. Also, when the vane 1 is located at the upper region, gravity and centrifugal force weaken each other to cause the elastic member 3 to generate compression deformation or to reduce tensile deformation so that the vane 1 moves inward toward the rotation center, and since the center of the annular guide rail 10 is offset from and located above the axis of the rotary shaft 12, the inward displacement of the vane 1 is offset, thereby maintaining the absolute position of the vane 1 in the axial direction of the vane. Wherein, in order to improve reliability and structural strength, ring rail 10 includes many and is provided with the guide rail groove side by side, every blade 1 disposes a plurality of that set up side by side gravity roller 9, gravity roller 9 rolls and sets up in corresponding in the guide rail groove 71. The circular guide rail 10 may be a circular or elliptical or approximately triangular closed loop structure. In addition, for the example improvement reliability, avoid blade 1 to break away from out from the mounting hole, still be provided with solid fixed ring 6 on blade chamber shell 2, gu fixed ring 6 overlaps on blade 1 and fixing on blade chamber shell 2, gu fixed ring 6 can block guide 4 and follow the spout 5 and fall out to avoid blade 1 to drop. The elastic member 3 is a member that generates a restoring force to resist deformation when subjected to tension, compression, rotation, or torsion. For example: the elastic member 3 may be a spring or other member having an elastic expansion function. It is also possible to design an elastic mechanism that does not require moving the steering mechanism, but relies on its own torsional and tensile coupling to produce the desired pitch angle.

Further, in order to facilitate the realization of the movable steering mechanism for adjusting the deflection of the vane 1, the movable steering mechanism comprises a sliding slot 5 and a guide 4 arranged in the sliding slot 5. Specifically, the guide piece 4 moves along the sliding chute 5, follows the arc of the sliding chute 5 to guide and control the deflection of the vane 1, wherein the sliding chute 5 can be arranged in the vane cavity shell 2, and the corresponding guide piece 4 is arranged on the vane 2; or, the sliding groove 5 is disposed on the blade 1, and the guiding element 4 is disposed on the blade cavity shell 2, specifically, the sliding groove 5 is disposed on the blade cavity shell 2, and the guiding element 4 is disposed on the blade 1 as an example: after the rotating speed of the blade 1 changes, the blade 1 moves in the mounting hole under the action of centrifugal force, and the blade 1 is guided by the guide piece 4 and the sliding groove 5 in a matching manner in the moving process, so that the blade 1 rotates and deflects along the curve of the sliding groove 5, and the requirement of the pitch angle required under the speed condition is automatically met. Wherein, the guiding element 4 can be a guiding column or a sliding block which is arranged in the sliding groove 5 in a sliding way; alternatively, the guide 4 is a guide roller that can roll in the chute 5. In general, the larger the speed of rotation of the blade 1, the larger the pitch angle of the blade 1 needs to be, so that in the conventional design of the sliding chute 5, the sliding chute 5 may be designed such that the pitch angle of the blade 1 gradually increases during the outward movement of the blade 1 along the sliding chute 5, and conversely, the pitch angle of the blade 1 gradually decreases during the inward movement of the blade 1 along the sliding chute 5.

Wherein the outer diameter of the blade cavity housing 2 is smaller than the inner diameter of the blade root 7 of the blade 1, and the blade root 7 can move on the outer surface of the blade cavity housing 2; alternatively, the inner diameter of the blade cavity housing 2 is larger than the outer diameter of the blade root 7 of the blade 1, the blade root 7 being movable in the blade cavity housing 2. For the hub 8 in the system, the blade cavity shell 2 may be located outside the hub 8, or the size of the hub 8 may be increased, so that the hub 8 partially or completely wraps the blade cavity shell 2, and the blade cavity shell 2 does not protrude from the hub 8.

In addition, in the practical use process, the passive pitch system of the embodiment is provided with additional equipment for inputting power generation or for outputting power, such as: the main shaft 12 may be connected with a generator 11, an electric motor, an engine, or other relevant components.

The utility model provides a passive variable pitch system adopts pure mechanical mechanism, can not receive the influence that has a power failure, anemograph is inaccurate or the user is wrong to strengthened system reliability, rigidness and control efficiency, at the in-process that the blade rotational speed changes, the centrifugal force that the blade produced changes and makes the spring force that the spring applyed to the blade change, the blade will take place to remove for blade chamber shell, and the cooperation removes steering mechanism and guides the blade, make blade self take place to rotate with the automatically regulated pitch angle. In addition, it is also possible to design an elastic mechanism that does not require a mechanical shifting of the steering mechanism, but rather that relies on its own torsional and tensile coupling to produce the desired pitch angle. The system may be adapted to be used in a number of applications, for example, to provide overspeed protection for a fluid driven turbine.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

Claims

1. A passive pitch system comprising a main shaft and a plurality of blades distributed about an axis of the main shaft, further comprising:

a spring-to-move-to-turn mechanism for guiding the blade to turn about its own centerline for changing pitch angle upon longitudinal movement of the blade relative to a blade cavity shell, and for applying a spring force to the blade; the elastic-moving-steering mechanism comprises an elastic member and a moving steering mechanism, wherein the elastic member is arranged in the blade cavity shell and used for applying elastic force to the blade;

a generator, or an electric motor, or an engine, connected to the main shaft.

2. The passive pitch system of claim 1, wherein the mobile steering mechanism includes a chute and a guide disposed in the chute.

3. The passive pitch system of claim 2, wherein the sliding slot is disposed in the blade cavity shell, the guide being disposed on the blade; alternatively, the runner is provided on the blade and the guide is provided on the blade cavity shell.

4. The passive pitch system according to claim 2, wherein the guide is a guide post or a slider or a collar slidably disposed in the sliding groove; alternatively, the guide member is a guide roller that can roll in the chute.

5. A passive pitch system according to claim 1, wherein a linear bearing or ball bearing array is used on the root or blade cavity shell of the blade.

6. The passive pitch system according to claim 1, wherein the two end portions of the elastic member are respectively provided with a connecting member, one of the connecting members is fixed on the blade, and the other connecting member is fixed on the blade cavity shell.