JPS61205396A - Variable pitch propeller - Google Patents

Abstract

PURPOSE:To simplify the structure and reduce manufacturing cost of the propeller in the caption by using shape memory alloys as material for a blade-angle changing actuator. CONSTITUTION:A hub 4 is fixed to the revolving shaft 2 of a motor 1. A coil spring 9 made of spring steel and a coil spring 10 made of one-way type shape memory alloy like nickel titanium alloy are suspended between the tip part of a main rod 8 and the bottom of a blade 6. By heating or cooling off the coil spring 10, the blade angle can be changed easily so that the wind direction is changed. With this contrivance, the structure as a variable pitch propeller can be simplified and at the same time the manufacturing cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable pitch propeller that uses a shape memory alloy to change the blade angle.

Conventionally, variable pitch propellers have complicated structures and have only been used in some cases for propulsion of aircraft and ships.

An object of the present invention is to obtain a variable pitch propeller that is simple in structure, lightweight, and low cost.

The present invention will be described based on drawings of embodiments. In FIG. 1, a nose 4 is fixed to a rotating shaft 2 of a motor 1, and a bearing portion for holding a rotating shaft 7 of a blade 6 is attached to the nose 4. There are 5. Four pillars 8 are further fixed to the no-pu 4, and between the tip of the pillar 8 and the lower part of the blade 6 are a coil spring 9 made of spring steel and a unidirectional shape made of nickel titanium alloy or the like. A coil spring 10 made of a memory alloy is suspended. A small propeller 3 is fixed to a rotating shaft 2 inside the motor 1, and a coil 11 of nichrome wire is arranged on the front surface of the motor 1. The motor 1 is an open type motor with its front and rear surfaces open, and when the rotating shaft 2 rotates in the direction of the arrow 12, the small propeller generates a flow of wind flowing from the rear surface of the motor 1 toward the front. The crystal structure of the coil spring 10 forms a martensitic phase at room temperature, the force of the spring becomes weaker, and the force of the coil spring 9 becomes relatively stronger. Therefore, the blade angle at room temperature is different from that shown in FIG.
appears to be stretched. The blade angle shown in Figure 1 is
When the coil spring 10 is heated, its crystal structure returns to the austenite phase, which is the parent phase, and as a result, the coil spring 10 tries to return to its original contracted state, and the spring force becomes stronger, so the force of the coil spring 9 becomes relatively weaker. As a result, the coil spring 10 is compressed and the coil spring 9 is expanded.

In the device configured as described above, when the motor 1 is started so that its rotating shaft 2 rotates in the direction of the arrow 12, and the nichrome wire coil 11 is heated by passing a current through it, the small propeller 3 generates a The wind turns into hot air and heats the coil spring 10.

When the temperature of the coil spring 10 rises and reaches a transformation point where its crystal structure changes from a martensitic phase to an austenite phase, the coil spring 10 contracts and the coil spring 9 expands for the reasons described above. At this time, the positive blade angle that the blades 6 form with the propeller rotating surface becomes maximum, and the speed of the wind flowing from the blades 6 in the opposite direction to the motor 1 becomes maximum. Next, when the current flowing through the nichrome wire coil 11 is cut off to stop the generation of hot air, the coil spring 10 is gradually cooled down. When the temperature of the coil spring 10 decreases and reaches a transformation point where its crystal structure changes from an austenite phase to a martensite phase, the fill spring 9 contracts and the coil spring 10 expands for the aforementioned reason. At this time, the blade angle becomes maximum, and the speed of the wind flowing from the blade 6 toward the motor 1 becomes maximum. As explained above, the variable pitch propeller shown in FIG. 1 allows the blade angle to be easily changed and the direction of the wind to be changed by simply heating or cooling the coil spring 10. In the device shown in Fig. 1, by providing a stopper to regulate the amount of change in the blade angle, the positive blade angle becomes maximum when the coil spring 10 is at high temperature, and the positive blade angle becomes maximum when the coil spring 10 is at room temperature. When the angle is minimized, the wind speed can be easily changed without changing the rotation speed of the motor 1.

FIG. 2 shows another embodiment in which only a coil spring made of a unidirectional shape memory alloy is used as the actuator for changing the blade angle, and the rotation axis 7 of the blade is located at the rear root of the blade 6. A coil spring 10 made of a unidirectional shape memory alloy is suspended between the cage wing and the lower part of the root 6 and the support 8.

In the device configured as described above, the rotating shaft 2 rotates in the direction of the arrow 12, and when the coil spring 10 is exposed to high temperature, the crystal structure of the coil spring 10 changes to the austenite phase, which is the parent phase, and remains in its original form. The propeller is in a contracted state, the blade angle of the propeller is at its minimum, and the speed of the wind flowing from the propeller in the opposite direction to the motor 1 is at its minimum. Next, coil spring 1
0 at room temperature, the crystal structure of the coil spring 10 changes to a martensitic phase and the force of the spring becomes weak.On the other hand, since aerodynamic torsional stress is acting on the rotating blades 6, the aerodynamic force The torsional stress becomes relatively larger than the force of the coil spring 10, and the blade 6 is rotated in a direction in which the blade angle increases. Therefore, the wind speed is the maximum.

In addition, if the rotation axis of the blade is placed at the front base of the blade,
Aerodynamic torsional stress acts in the direction of reducing the blade angle, and 1
A coil spring made of a directional shape memory alloy acts in the direction of increasing the blade angle.

In FIGS. 1 and 2, a coil spring, which is a linear actuator that acts in a linear direction, is used as an actuator for changing the blade angle. In addition to the method shown in FIGS. 1 and 2, various methods can be considered for changing the blade angle by causing the linear actuator to act on the blade, such as a method using a link mechanism.

FIG. 3 shows a second embodiment in which the rotary actuator properties of a coil spring made of a unidirectional shape memory alloy are used to change the blade angle. The tip end thereof is inserted into the hole 16 of the hub 4, and the base portion thereof is held by the bearing plate 13. A coil spring 14 made of a unidirectional shape memory alloy is inserted between the bearing plate 13 and the hole 16. One end of the coil spring 14 is inserted into the hole 15 of the hub 4, and one end of the coil spring 14 is inserted into the hole 15 of the hub 4. It is inserted into hole 17.

In the device configured as described above, when the rotating shaft 2 rotates in the direction of the arrow 12 and the coil spring 14 is exposed to high temperature, the crystal structure of the coil spring 14 changes to the austenite phase, which is the parent phase, and returns to its original form. A certain coil is wound up, the blade angle of the propeller is minimized, and the speed of the wind flowing from the propeller in the opposite direction to the motor 1 is minimized.

Next, when the coil spring 14 is placed at room temperature, the coil spring 14
The crystal structure of changes to martensitic phase and the force of the spring becomes weaker.On the other hand, since aerodynamic torsional stress is acting on the rotating blade 6, the aerodynamic torsional stress of coil spring 1
The force becomes relatively larger than that of 4 and rotates the blade 6 in a direction in which the blade angle increases. Therefore, the wind speed is the maximum.

The variable pitch propellers shown in Figures 2 and 3 utilize aerodynamic screw stress acting on the blades in addition to coil springs made of unidirectional shape memory alloy as a means of changing the blade angle. , if a coil spring made of a bidirectional shape memory alloy is used instead of a unidirectional shape memory alloy,
It is possible to change the blade angle using only a coil spring made of a bidirectional shape memory alloy without using aerodynamic torsional stress. This bidirectional shape memory alloy can remember its original shape at high temperatures and its original shape at low temperatures, so by raising the temperature of the coil spring to a high or low temperature, you can easily change the blade angle from dog to small or vice versa. can.

In addition, centrifugal force generated when a propeller rotates can be used to change the blade angle, as is used to change the blade angle of an aircraft's variable-pitch propeller to avoid the aerodynamic torsional stress mentioned above. good.

In FIGS. 1 to 3, the shape of the shape memory alloy is shown as a coil spring shape, but it does not necessarily have to be a coil spring shape, and any shape that effectively generates deer due to its shape memory effect may be used.

As described above, the present invention has the advantage that by using a shape memory alloy as an actuator for changing the blade angle in a variable pitch propeller, the blade angle can be easily changed without using a complicated mechanism. Therefore, it is possible to realize a variable pitch propeller with a simple structure, light weight, and low manufacturing cost, and the applications of the variable pitch propeller can be expanded.

FIG. 4 shows an embodiment in which the above-mentioned bidirectional shape memory alloy is used as the material for the root portion of the blade, in which a plate 10 on which the bidirectional shape memory alloy is applied to the hub 4 is used as a material. The blades 6 are fixed to the plate 10 with rivets 2.
It is fixed by 1. The shape of the plate 10 and the position of the blades 6 shown by solid lines in FIG. 4 are for the case where the plate 10 is at high temperature.The shape of the plate 10 and the position of the blade 6 when the plate 10 is at low temperature are two points. Indicated by a dashed line. The variable pitch propeller shown in Fig. 4 has a very simple structure because it has no rolling parts for changing the blade angle. Note that it is also possible to integrally mold the entire hub and blades from a bidirectional shape memory alloy. The present invention, an embodiment of which is shown in FIG. 4, realizes a variable pitch propeller that is extremely simple in structure, lightweight, and inexpensive to manufacture, and can expand the applications of variable pitch propellers.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the invention, and FIGS. 2 to 4 are partial perspective views showing other embodiments of the invention.

Claims (16)

[Claims] (1) A variable pitch propeller characterized in that a shape memory alloy is used as a material for part or all of the actuator that changes the blade angle. (2) The variable pitch propeller according to claim 1, characterized by comprising an actuator that increases the blade angle and an actuator that decreases the blade angle. (3) The variable pitch propeller according to claim 2, characterized in that each blade is provided with one actuator for increasing the blade angle and one actuator for decreasing the blade angle. (4) Claims 2 to 3, characterized in that one of the actuators is an actuator made of a shape memory alloy, and the other is a spring type actuator made of a spring material. Variable pitch propeller described in. (5) The material of the actuator that changes the blade angle by acting in only one direction, either increasing or decreasing the blade angle, is a shape memory alloy, and it can be used as a means to change the blade angle in the other direction. The variable pitch propeller according to claim 1, characterized in that the aerodynamic torsional stress of the blades when the propeller rotates is utilized. (6) The variable pitch propeller according to claim 5, characterized in that each blade is provided with one actuator. (7) The variable pitch propeller according to any one of claims 1 to 6, wherein the actuator is a linear actuator. (8) The variable pitch propeller according to any one of claims 1 to 6, wherein the actuator is a rotary actuator. (9) The variable pitch propeller according to claim 8, characterized in that a coil spring-like actuator is inserted into the rotating shaft of each blade. (10) The variable pitch propeller according to any one of claims 1 to 8, wherein the actuator has a coil spring shape. (11) The variable pitch propeller according to any one of claims 1 to 8, wherein the actuator made of a shape memory alloy has a coil spring shape. (12) A small propeller that sends air in the direction of an actuator made of shape memory alloy is attached to the rotating shaft of the variable pitch propeller, and a heat source or cold source is placed on the front side of the small propeller on the actuator side. A variable pitch propeller according to claims 1 to 11. (13) The variable pitch propeller according to claim 12, wherein the small propeller is disposed within a drive motor of the variable pitch propeller, and a heating wire is disposed in front of the motor. (14) The blade or a part of the blade is made of a bidirectional shape memory alloy, and the shape of the blade or a part of the blade transforms due to a change in temperature, the blade angle changes, and conversely, the temperature returns to its original state. A variable pitch propeller characterized in that the shape of the blade or a part of the blade undergoes reverse transformation to restore its original state and the blade angle returns to its original state. (15) The small propeller is attached to the rotating shaft of the variable pitch propeller, and a heat source or a cold source is arranged on the front surface of the small propeller on the variable pitch propeller side. Variable pitch propeller. (16) The variable pitch propeller according to claim 15, wherein the small propeller is disposed within a drive motor of the variable pitch propeller, and a heating wire is disposed in front of the motor.