CN116495167A - Folding propeller system capable of being automatically unfolded and limited and design method - Google Patents
Folding propeller system capable of being automatically unfolded and limited and design method Download PDFInfo
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- CN116495167A CN116495167A CN202310569107.7A CN202310569107A CN116495167A CN 116495167 A CN116495167 A CN 116495167A CN 202310569107 A CN202310569107 A CN 202310569107A CN 116495167 A CN116495167 A CN 116495167A
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- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000005452 bending Methods 0.000 claims abstract description 20
- 230000009471 action Effects 0.000 claims abstract description 7
- 238000009434 installation Methods 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 14
- 230000005484 gravity Effects 0.000 claims description 9
- 238000000926 separation method Methods 0.000 claims description 9
- 230000000712 assembly Effects 0.000 claims description 4
- 238000000429 assembly Methods 0.000 claims description 4
- 238000010008 shearing Methods 0.000 claims description 4
- 230000001133 acceleration Effects 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 5
- 230000000694 effects Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 239000000843 powder Substances 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C11/00—Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
- B64C11/16—Blades
- B64C11/20—Constructional features
- B64C11/28—Collapsible or foldable blades
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C11/00—Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
- B64C11/02—Hub construction
- B64C11/04—Blade mountings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
- B64F5/00—Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
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- Aviation & Aerospace Engineering (AREA)
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Abstract
The invention provides a folding propeller system capable of being automatically unfolded and limited and a design method thereof, comprising the following steps: the motor propeller comprises a motor propeller connecting piece, a folding shaft, a double-torsion spring unfolding assembly and a limiting pin; a motor is arranged at the center of the motor propeller connecting piece, and the motor propeller connecting piece is driven to rotate through the motor; the two ends of the motor propeller connecting piece are symmetrically provided with propellers, and the propeller hub of each propeller is axially connected with the outer end of the motor propeller connecting piece in a folding way through a folding shaft; according to the folding propeller system capable of being automatically unfolded and limited, the chordwise bending moment and the strength influence of centrifugal force on the folding system, which are generated when the propeller rotates at a high speed, are considered, and the structure is ensured not to be damaged in the use process; the propeller can still automatically develop a required angle when not relying on the action of centrifugal force, so that collision with structures such as wings and tail wings of an aircraft when rotating is avoided; the limiting device for preventing the blade from being excessively unfolded is simple and easy to implement.
Description
Technical Field
The invention belongs to the technical field of aircraft propulsion system design, and particularly relates to a folding propeller system capable of being automatically unfolded and limited and a design method.
Background
Propeller propulsion systems are an important branch of aircraft propulsion systems and are also the primary source of power for most unmanned aircraft. For catapulting type or air-launching type aircrafts, the conventional non-foldable propeller is limited in use due to space problems, extra resistance caused by non-working conditions and the like, so that the foldable propeller is beginning to be widely focused. For catapult or air-launched aircraft, the propeller is folded in an axial manner.
Patent CN 110127034A discloses a foldable propeller, mainly used for the problem of positioning of paddles; patent CN 113911319A discloses a folding limit mechanism for a propeller of an unmanned aerial vehicle; the invention of the above patent has single function, and can only realize the limit function. Patent CN 209192205U discloses a folding propeller and an unmanned aerial vehicle, which are only used for solving the problem of space storage; patent CN 111252237A discloses a folding and unfolding device and a propeller, patent CN 209321229U discloses a folding propeller, a power device and an unmanned aerial vehicle, patent CN 110871881B discloses a propeller folding mechanism for an ejection unmanned aerial vehicle, and the above-mentioned patents only describe the form and working mode of the folding structure of the propeller, do not relate to the design method of the folding system, and do not consider the problem of structural strength.
In summary, the axial folding propeller system in the related art mainly has the following problems. Firstly, as the folding system is influenced by centrifugal force generated when the propeller rotates at a high speed, the strength of the folding system cannot meet the working requirement of the propeller rotating at a high speed, and the folding system is easy to damage in the use process; secondly, the folding system structure mostly considers the single function of folding or limiting, and has less structural design which comprehensively considers the combination of autonomous flicking (unfolding without depending on the centrifugal force effect generated when the propeller rotates) and limiting. In summary, the existing literature does not find out a folding propeller system with autonomous unfolding and limiting functions and a design method thereof, which are proposed by the system while considering structural strength.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a folding propeller system capable of being automatically unfolded and limited and a design method thereof, which can effectively solve the problems.
The technical scheme adopted by the invention is as follows:
the invention provides a folding propeller system capable of being unfolded and limited independently, comprising: the motor propeller comprises a motor propeller connecting piece (10), a folding shaft (20), a double-torsion spring unfolding assembly (30) and a limiting pin (40);
a motor (50) is arranged at the center of the motor propeller connecting piece (10), and the motor propeller connecting piece (10) is driven to rotate through the motor (50); the two ends of the motor propeller connecting piece (10) are symmetrically provided with propellers (60), and the propeller hub of each propeller (60) is axially connected with the outer end of the motor propeller connecting piece (10) in a folding way through the folding shaft (20);
-mounting the torsion spring expansion assemblies (30) below each folding shaft (20), driving the propellers (60) to be automatically expanded along the folding shafts (20) through the torsion spring expansion assemblies (30);
and the root of each propeller (60) is provided with a limiting pin (40), and the maximum angle of autonomous expansion of the propeller (60) is limited by the limiting pin (40).
Preferably, the torsion spring expanding assembly (30) comprises a first spring (301), a second spring (302), a connecting rod (303), a first fixing rod (304), a second fixing rod (305), a first spring guide rod (306), a second spring guide rod (307), a first spring mounting seat (308) and a second spring mounting seat (309);
the first spring mounting seat (308) and the second spring mounting seat (309) are symmetrically arranged at the bottom of one end of the motor propeller connecting piece (10) front and back; the first spring installation seat (308) is fixedly provided with the first spring guide rod (306); the second spring mounting seat (309) is fixedly provided with the second spring guide rod (307); the first spring guide rod (306) and the second spring guide rod (307) are coaxially and horizontally arranged;
the first spring (301) is sleeved on the first spring guide rod (306), and the second spring (302) is sleeved on the second spring guide rod (307); the inner end of the first spring (301) is connected with the inner end of the second spring (302) integrally through the connecting rod (303); the outer end of the first spring (301) is clamped on the first spring mounting seat (308); the outer end of the second spring (302) is clamped on the second spring mounting seat (309);
the connecting rod (303) is propped against the lower part of the propeller (60); when the folding propeller system capable of being automatically unfolded and limited is released, under the combined action of the first spring (301) and the second spring (302), the connecting rod (303) is driven to rotate, and then the propeller (60) is driven to be automatically unfolded.
Preferably, a motor mounting hole (101) for mounting the motor (50) is formed in the center of the motor propeller connecting piece (10); two ends of the motor propeller connecting piece (10) are respectively provided with a folding shaft mounting hole (102) for mounting the folding shaft (20); two ends of the motor propeller connecting piece (10) are respectively provided with a first spring installation seat assembly hole (103) for installing the first spring installation seat (308) and a second spring installation seat assembly hole (104) for installing the second spring installation seat (309); and motor assembly holes (105) for mounting the motor (50) are formed around the motor propeller connecting piece (10).
Preferably, two ends of the motor propeller connecting piece (10) are provided with C-shaped grooves (106), and the C-shaped grooves (106) are coaxially provided with two through holes, namely a first through hole (107) and a second through hole (108), along the front-back direction; the first through hole (107) and the second through hole (108) form the folding shaft mounting hole (102).
Preferably, the propeller (60) comprises a blade (601) and a hub (602) at the root of the blade (601);
the paddle hub (602) is provided with a folding shaft assembly hole (603) and a limiting pin assembly hole (604).
Preferably, the limit pin (40) comprises a limit screw (401) and a nut (402);
the limiting screw rod (401) passes through the limiting pin assembly hole (604), and the nuts (402) are arranged at two ends of the limiting screw rod (401).
The invention also provides a design method of the folding propeller system capable of being automatically unfolded and limited, which comprises the following steps:
step 1, determining flight parameters of a folding propeller system, comprising: centrifugal force F of propeller under limit working condition Separation of Propeller chordwise bending moment M String ；
Step 2, the minimum moment M required by the self gravity of the propeller is overcome Twisting for 1min As the minimum value M of the spring mounting torque Twisting for 2min Therefore, the minimum value M of the spring mounting torque is determined using the following formula Twisting for 2min The method comprises the steps of carrying out a first treatment on the surface of the According to the minimum value M of the spring mounting torque Twisting for 2min Determining a property parameter of the spring, comprising: spring material, diameter D of spring wire 1 Pitch diameter D of spring coil ring 2 And the number of turns N;
M twisting for 1min ＝M Twisting for 2min ＝mgl Shaft
Wherein:
m is the mass of the propeller;
g is gravity acceleration;
l shaft The distance from the center of gravity of the blade to the folding shaft;
step 3, centrifugal force F of the propeller under the limit working condition Separation of As the maximum shear force to be applied to the folding shaft (20), the minimum diameter d of the folding shaft (20) is determined by the following equation min ：
Wherein:
pi is the circumference ratio;
[ tau ] is the allowable shear stress of the folded shaft material;
step 4, determining dangerous section related parameters, including:
step 4.1, centrifugal force F of the propeller under the limit working condition Separation of As the maximum tensile force applied to the dangerous section, the minimum value A of the dangerous section area is determined by the following formula min ：
Wherein:
[ sigma ] is the allowable stress of the dangerous section material;
dangerous section, which refers to the section of the first through hole (107) and the second through hole (108) of the folding shaft (20) installed at the two ends of the motor propeller connecting piece (10);
step 4.2, bending moment M of the chord direction of the propeller String As the maximum value of the bending moment born by the dangerous section, the minimum value W of the bending resistance section coefficient of the dangerous section is determined by adopting the following method min ：
Step 4.3, according to the minimum value A of the dangerous cross-sectional area min And minimum value W of dangerous section bending resistance section coefficient min The constraint condition to be met by the dangerous section parameter is determined by adopting the following formula:
A min ＝4bh
wherein:
b is the wall thickness of the first through hole (107) or the second through hole (108) at the dangerous section position;
h is the hole depth of the first through hole (107) or the second through hole (108);
n is the distance from the bottom surface of the first through hole (107) to the top surface of the second through hole (108);
q hole diameter of the first through hole (107) or the second through hole (108);
step 5, determining relevant parameters of the limiting pin (40), including:
step 5.1, determining position parameters of the limiting pin (40), including an angle alpha and a distance beta; wherein, angle α refers to: taking the center of the left folding shaft (20) as an origin, and taking the center of the right folding shaft (20) as a ray to form a first ray; taking the center of the left folding shaft (20) as an origin, and taking the center of the left limiting pin (40) as a ray to form a second ray; the included angle between the first ray and the second ray is the angle alpha;
distance β refers to: the distance between the center of the left folding shaft (20) and the center of the left limiting pin (40);
determining the value range of the angle alpha; the distance beta is determined as follows:wherein r is 1 Is the hub radius;
step 5.2, the minimum torque required to spring the propeller by the double torsion spring, namely the minimum value M of the double torsion spring mounting torque Twisting for 2min The elastic force generated by the flick propeller, namely the shearing force F born by the screw rod of the limiting pin is calculated, so the minimum value d of the screw rod diameter of the limiting pin (40) is determined by adopting the following method Screw min :
Wherein:
[ tau ] is the allowable shear stress of the bolt material;
and 6, designing the folding propeller system capable of being automatically unfolded and limited according to the related parameters designed in the steps 2 to 5 and the structure of the folding propeller system capable of being automatically unfolded and limited.
The folding propeller system capable of being automatically unfolded and limited and the design method thereof have the following advantages:
according to the folding propeller system capable of being automatically unfolded and limited, the chordwise bending moment and the strength influence of centrifugal force on the folding system, which are generated when the propeller rotates at a high speed, are considered, and the structure is ensured not to be damaged in the use process; the propeller can still automatically develop a required angle when not relying on the action of centrifugal force, so that collision with structures such as wings and tail wings of an aircraft when rotating is avoided; the limiting device for preventing the blade from being excessively unfolded is simple and easy to implement.
Drawings
Fig. 1 is a schematic view showing a folding state of a folding propeller system provided by the present invention;
fig. 2 is a schematic view showing an unfolded state of the folding propeller system provided by the present invention;
FIG. 3 is a perspective view of the folding propeller system provided by the present invention at an angle;
fig. 4 is a perspective view of the folding propeller system provided by the present invention at another angle;
FIG. 5 is a top view of the folding propeller system provided by the present invention;
FIG. 6 is a perspective view of the motor propeller connector and the torsion spring deployment assembly provided by the present invention in an assembled state;
FIG. 7 is a perspective view of a motor propeller connector provided by the present invention;
FIG. 8 is a cross-sectional view of a motor propeller connector at A-A according to the present invention;
FIG. 9 is a perspective view of a torsion spring deployment assembly provided by the present invention;
FIG. 10 is a perspective view of a torsion spring provided by the present invention;
FIG. 11 is a perspective view of a spring mount provided by the present invention;
FIG. 12 is an assembly view of a folding shaft and a stop pin provided by the present invention;
fig. 13 is a perspective view of a propeller provided by the present invention;
fig. 14 is a schematic view of a rotor hub of a propeller provided by the invention with a folding shaft assembly hole and a limiting pin assembly hole;
fig. 15 is an assembly parameter diagram of the folding shaft and the limiting pin provided by the invention.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
According to the folding propeller system capable of being automatically unfolded and limited, the chordwise bending moment and the strength influence of centrifugal force on the folding system, which are generated when the propeller rotates at a high speed, are considered, and the structure is ensured not to be damaged in the use process; the propeller can still automatically develop a required angle when not relying on the action of centrifugal force, so that collision with structures such as wings and tail wings of an aircraft when rotating is avoided; the limiting device for preventing the blade from being excessively unfolded is simple and easy to implement.
The present invention provides an autonomously deployable and limitable folding propeller system, with reference to fig. 1 to 5, comprising: the motor propeller connector 10, the folding shaft 20, the double torsion spring unfolding assembly 30 and the limiting pin 40;
a motor 50 is installed at the center of the motor propeller connector 10, and the motor propeller connector 10 is driven to rotate through the motor 50; the two ends of the motor propeller connecting piece 10 are symmetrically provided with propellers 60, and the hub of each propeller 60 is axially connected with the outer end of the motor propeller connecting piece 10 in a folding way through a folding shaft 20;
a double-torsion spring unfolding assembly 30 is arranged below each folding shaft 20, and the propeller 60 is driven to automatically unfold along the folding shafts 20 through the double-torsion spring unfolding assembly 30;
the root of each propeller 60 is provided with a limiting pin 40, and the maximum angle of autonomous deployment of the propeller 60 is limited by the limiting pin 40.
The motor propeller connector 10, the torsion spring deployment assembly 30, the stop pin 40 and the propeller 60 are each described in detail below:
one-piece torsion spring deployment assembly 30
Referring to fig. 9, 10 and 11, the torsion spring deployment assembly 30 includes a first spring 301, a second spring 302, a connecting rod 303, a first securing rod 304, a second securing rod 305, a first spring guide 306, a second spring guide 307, a first spring mount 308 and a second spring mount 309;
the first spring mounting seat 308 and the second spring mounting seat 309 are symmetrically arranged at the bottom of one end of the motor propeller connecting piece 10 in the front-back direction; the first spring mount 308 fixedly mounts the first spring guide 306; the second spring mount 309 fixedly mounts the second spring guide 307; the first spring guide 306 and the second spring guide 307 are coaxially and horizontally arranged;
the first spring 301 is sleeved on the first spring guide rod 306, and the second spring 302 is sleeved on the second spring guide rod 307; and, the inner end of the first spring 301 is integrally connected with the inner end of the second spring 302 through a connecting rod 303; the outer end of the first spring 301 is clamped on the first spring mounting seat 308; the outer end of the second spring 302 is clamped to a second spring mount 309; the connecting rod 303 abuts under the propeller 60; the double-torsion spring is provided with a double-torsion spring moving end and a double-torsion spring fixed end, the fixed end of the double-torsion spring is fixed on the motor propeller connecting piece through a spring mounting device, the moving end of the double-torsion spring is contacted with the blade, and an anti-friction adhesive tape is stuck at the contact position of the blade.
The propeller consists of a hub and blades, and the initial state is a folded state and is bound by a specific device. When the aircraft reaches a specific state, the restraint device is unfolded, the folding propeller system capable of being automatically unfolded and limited is released, and under the combined action of the first spring 301 and the second spring 302, the connecting rod 303 is driven to rotate, so that the propeller 60 is driven to be automatically unfolded.
(two) Motor-Propeller connection 10
Different materials can be selected according to the design requirement for the materials of the motor propeller connecting piece, aviation aluminum alloy can be generally selected, and meanwhile, the motor propeller connecting piece can be designed into different shapes to match with the motor. Referring to fig. 7 and 8, a motor mounting hole 101 for mounting the motor 50 is formed at the center of the motor propeller connector 10; two ends of the motor propeller connecting piece 10 are respectively provided with a folding shaft mounting hole 102 for mounting the folding shaft 20; the two ends of the motor propeller connecting piece 10 are respectively provided with a first spring installation seat assembly hole 103 for installing a first spring installation seat 308 and a second spring installation seat assembly hole 104 for installing a second spring installation seat 309, wherein the first spring installation seat assembly hole 103 and the first spring installation seat assembly hole 103 can be four blind holes; around the motor propeller connector 10, motor assembly holes 105 for mounting the motor 50 are provided.
Two ends of the motor propeller connecting piece 10 are provided with symmetrical propeller installation positions, the propeller installation positions are C-shaped grooves 106, and the C-shaped grooves 106 are coaxially provided with two through holes in the front-rear direction, namely a first through hole 107 and a second through hole 108; the first through hole 107 and the second through hole 108 form a folding shaft mounting hole 102.
(III) Propeller 60
Referring to fig. 13 and 14, the propeller 60 includes a blade 601 and a hub 602 at the root of the blade 601; the hub 602 is provided with a folding shaft assembly hole 603 and a stop pin assembly hole 604.
Specifically, the hub 602 is inserted into the C-shaped groove 106 of the mounting position, the folding shaft assembly hole 603 is connected to the through hole of the C-shaped groove in the up-down direction by a bolt, the bolt simultaneously serves as the folding shaft of the propeller, and the other limit pin assembly hole 604 is connected to the limit pin 40.
(IV) stop pin 40
Referring to fig. 12, the stopper pin 40 includes a stopper screw 401 and a nut 402; the limit screw 401 passes through the limit pin assembly hole 604, and nuts 402 are arranged at two ends of the limit screw 401. The diameter of the limit screw 401 is the same as the diameter of a limit pin assembly hole 604 on the propeller hub connected with the limit pin.
The invention also provides a design method of the folding propeller system capable of being automatically unfolded and limited, which comprises the following steps:
step 1, determining flight parameters of a folding propeller system, comprising: centrifugal force F of propeller under limit working condition Separation of Propeller chordwise bending moment M String The method comprises the steps of carrying out a first treatment on the surface of the As shown in fig. 1, the direction 1 is an axial direction when the propeller is deployed, the direction 2 is a forward direction when the propeller rotates, and the direction 3 is a chord direction when the propeller is deployed.
Of course, in practical applications, the step of determining the size parameter of the propeller further includes: distance R from the center of folding shaft 20 to the tip of the propeller 1 Distance R from rotation axis 4 to tip, thickness H of hub 1 Radius r of hub 1 Propeller mass m.
Step 2, in order to ensure that the propeller can be sprung smoothly, the minimum moment M required by the gravity of the propeller is overcome Twisting for 1min As the minimum value M of the spring mounting torque Twisting for 2min Therefore, the minimum value M of the spring mounting torque is determined using the following formula Torsion 2mi The method comprises the steps of carrying out a first treatment on the surface of the According to the minimum value M of the spring mounting torque Twisting for 2min Determining a characteristic parameter of the spring according to a spring design manual, comprising: spring material, diameter D of spring wire 1 Pitch diameter D of spring coil ring 2 And the number of turns N;
M twisting for 1min ＝M Twisting for 2min ＝mgl Shaft
Wherein:
m is the mass of the propeller;
g is gravity acceleration;
l shaft The distance from the center of gravity of the blade to the folding shaft;
after the property parameters of the spring are determined by adopting the parameters, the structural form of the designed double-torsion spring is shown in figure 10, and the structural form comprises three parts, namely a double-torsion spring moving end, a double-torsion spring spiral ring and a double-torsion spring fixing end. The connecting rod 303 is located at a moving end of the torsion spring, and ends of the first fixing rod 304 and the second fixing rod 305 are fixed ends of the torsion spring. The design of the dual-beef powder spring mounting device is shown in fig. 11, and comprises a spring guide rod, a spring fixing end mounting base and a spring fixing end limiting boss 310. The spring guide rod is of a cylindrical structure and is used for protecting the spring spiral ring, the diameter and the length of the spring spiral ring are determined according to a spring design manual, four bolt holes are formed in the spring fixing end mounting base and are used for mounting spring fixing bolts, and the three parts are matched with the spring fixing bolts to jointly act on the spring fixing end and are used for limiting movement of the spring.
Step 3, centrifuging the propeller under the limit working conditionForce F Separation of As the maximum shearing force to be applied to the folding shaft 20, the minimum diameter d of the folding shaft 20 is determined by the following equation min ：
Wherein:
pi is the circumference ratio;
[ tau ] is the allowable shear stress of the folded shaft material;
wherein the folding shaft 20 is a bolt.
And 4, determining relevant parameters of a dangerous section, wherein the dangerous section is section A in fig. 7, and the sectional view of the dangerous section is shown in fig. 8. When the related parameters of the dangerous section are determined, the tensile force and the bending moment of the dangerous section are required to meet the requirements, and then the strength of the dangerous section is required to meet the requirements.
The method specifically comprises the following steps:
step 4.1, centrifugal force F of the propeller under the limit working condition Separation of As the maximum tensile force applied to the dangerous section, the minimum value A of the dangerous section area is determined by the following formula min The dangerous cross-sectional areas are the areas of the four shaded areas in fig. 8.
Wherein:
[ sigma ] is the allowable stress of the dangerous section material;
dangerous section, which means the section of the first through hole 107 and the second through hole 108 for installing the folding shaft 20, at both ends of the motor propeller connector 10;
step 4.2, bending moment M of the chord direction of the propeller String As the maximum value of the bending moment born by the dangerous section, the minimum value W of the bending resistance section coefficient of the dangerous section is determined by adopting the following method min ：
Step 4.3, according to the minimum value A of the dangerous cross-sectional area min And minimum value W of dangerous section bending resistance section coefficient min The constraint condition to be met by the dangerous section parameter is determined by adopting the following formula:
A min ＝4bh
wherein:
b is the wall thickness of the first through hole 107 or the second through hole 108 at the dangerous section position;
h is the hole depth of the first through hole 107 or the second through hole 108;
n is the distance between the bottom surface of the first through hole 107 to the top surface of the second through hole 108;
q the hole diameter of the first through hole 107 or the second through hole 108;
step 5, determining the related parameters of the limiting pin 40, including:
step 5.1, determining the position parameters of the limiting pin 40, including an angle alpha and a distance beta;
wherein, as shown in fig. 15, the angle α refers to: taking the center of the left folding shaft 20 as an origin, and taking a ray at the center of the right folding shaft 20 to form a first ray S1; taking the center of the left folding shaft 20 as an origin, taking a ray at the center of the left limiting pin 40 to form a second ray S2; the included angle between the first ray S1 and the second ray S2 is the angle alpha;
distance β refers to: the distance from the center of the left folding shaft 20 to the center of the left stopper pin 40;
determining the value Fan Fan of the angle alpha, for example, 0-75 degrees; the distance beta is determined as follows:wherein r1 is the hub radius:
and 5.2, the limiting pin consists of a screw rod with threads at two ends and two nuts, and the diameter of the screw rod is determined by the elasticity generated by the fact that the double-torsion spring bounces off the propeller.
Specifically, the minimum torque required to spring the propeller by the torsion spring, namely the minimum value M of the installation torque of the torsion spring Twisting for 2min The elastic force generated by the flick propeller, namely the shearing force F born by the screw rod of the limit pin is calculated, so the minimum value d of the screw rod diameter of the limit pin 40 is determined by adopting the following method Screw min ：
Wherein:
[ tau ] is the allowable shear stress of the bolt material;
and 6, designing the folding propeller system capable of being automatically unfolded and limited according to the related parameters designed in the steps 2 to 5 and the structure of the folding propeller system capable of being automatically unfolded and limited.
The method specifically comprises the following steps:
step 6.1: perforating at corresponding position of propeller hub
Two through holes are formed in the thickness direction of the propeller hub, and the through holes are respectively: a folding shaft fitting hole 603 and a stopper pin fitting hole 604. Wherein the diameter of the hole of the folding shaft assembly hole 603 is identical to the diameter of the folding shaft 20 determined in step 3; the position of the folding shaft assembly holes 603 is determined according to dangerous section parameters; the position of the stopper pin mounting hole 604 is determined by the positional parameters of the stopper pin 40. The diameter of the hole of the stop pin assembly hole 604 is consistent with the screw diameter of the stop pin 40 determined in step 5.2.
Step 6.2: assembly of a folding propeller system
First, as shown in fig. 14, the screw of the stopper pin is inserted into the stopper pin fitting hole 604 of the propeller hub, and two nuts are respectively attached to both ends of the screw, thereby completing the attachment of the stopper pin and the propeller.
Next, as shown in fig. 10, the spring guide rod is inserted into the spring coil ring, and the spring fixing ends are fixed between the spring fixing bolts; meanwhile, the spring fixing end is clamped between the motor propeller connecting piece and the spring mounting base through the matching of the motor mounting holes 101 on the side face of the motor propeller connecting piece, as shown in fig. 9.
Finally, as shown in fig. 12, the motor propeller connector and the folding shaft used for connecting the propeller are used for assembling the propeller with the limit pin mounted to the C-shaped mounting position of the motor propeller connector, and the assembling process is finished, and the final effect is as shown in fig. 1 and 2. Therefore, the folding propeller system that this application provided, including two screw, a motor screw connecting piece, two screw and motor screw connecting piece's folding axle, two torsion springs, four spring mounting device, sixteen spring fixing bolt and two spacer pins. It should be noted that the motors in fig. 1 and 2 are not included in the folding propeller system, and the motors are mainly used to facilitate the description of the design of the motor propeller connector and the matching portion of the motor and define the front, the back and the side surfaces of the motor propeller connector.
Therefore, the invention provides the folding propeller system capable of being automatically unfolded and limited and the design method thereof, which are suitable for the design of the axial folding propeller system, and the folding propeller system capable of being automatically unfolded and limited considers the chordwise bending moment generated when the propeller rotates at a high speed and the strength influence of centrifugal force on the folding system, can still be automatically unfolded by a required angle without depending on the action of the centrifugal force, can prevent the blades from being excessively unfolded, and avoid collision with structures such as wings, tail wings and the like of an aircraft during rotation; the limiting device for preventing the blade from being excessively unfolded is simple and easy to implement.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which is also intended to be covered by the present invention.
Claims (7)
1. An autonomously deployable and spaceable folding propeller system, comprising: the motor propeller comprises a motor propeller connecting piece (10), a folding shaft (20), a double-torsion spring unfolding assembly (30) and a limiting pin (40);
a motor (50) is arranged at the center of the motor propeller connecting piece (10), and the motor propeller connecting piece (10) is driven to rotate through the motor (50); the two ends of the motor propeller connecting piece (10) are symmetrically provided with propellers (60), and the propeller hub of each propeller (60) is axially connected with the outer end of the motor propeller connecting piece (10) in a folding way through the folding shaft (20);
-mounting the torsion spring expansion assemblies (30) below each folding shaft (20), driving the propellers (60) to be automatically expanded along the folding shafts (20) through the torsion spring expansion assemblies (30);
and the root of each propeller (60) is provided with a limiting pin (40), and the maximum angle of autonomous expansion of the propeller (60) is limited by the limiting pin (40).
2. The autonomously deployable and limitable folding propeller system of claim 1, wherein the double torsion spring deployment assembly (30) comprises a first spring (301), a second spring (302), a connecting rod (303), a first fixing rod (304), a second fixing rod (305), a first spring guide (306), a second spring guide (307), a first spring mount (308) and a second spring mount (309);
the first spring mounting seat (308) and the second spring mounting seat (309) are symmetrically arranged at the bottom of one end of the motor propeller connecting piece (10) front and back; the first spring installation seat (308) is fixedly provided with the first spring guide rod (306); the second spring mounting seat (309) is fixedly provided with the second spring guide rod (307); the first spring guide rod (306) and the second spring guide rod (307) are coaxially and horizontally arranged;
the first spring (301) is sleeved on the first spring guide rod (306), and the second spring (302) is sleeved on the second spring guide rod (307); the inner end of the first spring (301) is connected with the inner end of the second spring (302) integrally through the connecting rod (303); the outer end of the first spring (301) is clamped on the first spring mounting seat (308); the outer end of the second spring (302) is clamped on the second spring mounting seat (309);
the connecting rod (303) is propped against the lower part of the propeller (60); when the folding propeller system capable of being automatically unfolded and limited is released, under the combined action of the first spring (301) and the second spring (302), the connecting rod (303) is driven to rotate, and then the propeller (60) is driven to be automatically unfolded.
3. The autonomously deployable and limitable folding propeller system as claimed in claim 2, characterized in that the centre of the motor propeller connector (10) is provided with a motor mounting hole (101) for mounting the motor (50); two ends of the motor propeller connecting piece (10) are respectively provided with a folding shaft mounting hole (102) for mounting the folding shaft (20); two ends of the motor propeller connecting piece (10) are respectively provided with a first spring installation seat assembly hole (103) for installing the first spring installation seat (308) and a second spring installation seat assembly hole (104) for installing the second spring installation seat (309); and motor assembly holes (105) for mounting the motor (50) are formed around the motor propeller connecting piece (10).
4. A folding propeller system capable of being automatically unfolded and limited according to claim 3, wherein two ends of the motor propeller connecting piece (10) are provided with C-shaped grooves (106), and the C-shaped grooves (106) are coaxially provided with two through holes, namely a first through hole (107) and a second through hole (108), along the front-back direction; the first through hole (107) and the second through hole (108) form the folding shaft mounting hole (102).
5. A self-expanding and limited folding propeller system according to claim 3, characterized in that the propeller (60) comprises a blade (601) and a hub (602) at the root of the blade (601);
the paddle hub (602) is provided with a folding shaft assembly hole (603) and a limiting pin assembly hole (604).
6. The autonomously deployable and limitable folding propeller system as claimed in claim 5, characterized in that said limit pin (40) comprises a limit screw (401) and a nut (402);
the limiting screw rod (401) passes through the limiting pin assembly hole (604), and the nuts (402) are arranged at two ends of the limiting screw rod (401).
7. A method of designing an autonomously deployable and spaceable folding propeller system according to any one of claims 1 to 6, comprising the steps of:
step 1, determining flight parameters of a folding propeller system, comprising: centrifugal force F of propeller under limit working condition Separation of Propeller chordwise bending moment M String ；
Step 2, the minimum moment M required by the self gravity of the propeller is overcome Twisting for 1min As the minimum value M of the spring mounting torque Twisting for 2min Therefore, the minimum value M of the spring mounting torque is determined using the following formula Twisting for 2min The method comprises the steps of carrying out a first treatment on the surface of the According to the minimum value M of the spring mounting torque Twisting for 2min Determining a property parameter of the spring, comprising: spring material, diameter D of spring wire 1 Pitch diameter D of spring coil ring 2 And the number of turns N;
M torsion 1mi ＝M Twisting for 2min ＝mgl Shaft
Wherein:
m is the mass of the propeller;
g is gravity acceleration;
l shaft The distance from the center of gravity of the blade to the folding shaft;
step 3, centrifugal force F of the propeller under the limit working condition Separation of As the maximum shear force to be applied to the folding shaft (20), the minimum diameter d of the folding shaft (20) is determined by the following equation min ：
Wherein:
pi is the circumference ratio;
[ tau ] is the allowable shear stress of the folded shaft material;
step 4, determining dangerous section related parameters, including:
step 4.1, centrifugal force F of the propeller under the limit working condition Separation of As the maximum tensile force applied to the dangerous section, the minimum value A of the dangerous section area is determined by the following formula min ：
Wherein:
[ sigma ] is the allowable stress of the dangerous section material;
dangerous section, which refers to the section of the first through hole (107) and the second through hole (108) of the folding shaft (20) installed at the two ends of the motor propeller connecting piece (10);
step 4.2, bending moment M of the chord direction of the propeller String As the maximum value of the bending moment born by the dangerous section, the minimum value W of the bending resistance section coefficient of the dangerous section is determined by adopting the following method min ：
Step 4.3, according to the minimum value A of the dangerous cross-sectional area min And minimum value W of dangerous section bending resistance section coefficient min The constraint condition to be met by the dangerous section parameter is determined by adopting the following formula:
A min ＝4bh
wherein:
b is the wall thickness of the first through hole (107) or the second through hole (108) at the dangerous section position;
h is the hole depth of the first through hole (107) or the second through hole (108);
n is the distance from the bottom surface of the first through hole (107) to the top surface of the second through hole (108);
q hole diameter of the first through hole (107) or the second through hole (108);
step 5, determining relevant parameters of the limiting pin (40), including:
step 5.1, determining position parameters of the limiting pin (40), including an angle alpha and a distance beta; wherein, angle α refers to: taking the center of the left folding shaft (20) as an origin, and taking the center of the right folding shaft (20) as a ray to form a first ray; taking the center of the left folding shaft (20) as an origin, and taking the center of the left limiting pin (40) as a ray to form a second ray; the included angle between the first ray and the second ray is the angle alpha;
distance β refers to: the distance between the center of the left folding shaft (20) and the center of the left limiting pin (40);
determining the value range of the angle alpha; the distance beta is determined as follows:wherein r is 1 Is the hub radius;
step 5.2, the minimum torque required to spring the propeller by the double torsion spring, namely the minimum value M of the double torsion spring mounting torque Twisting for 2min The elastic force generated by the flick propeller, namely the shearing force F born by the screw rod of the limiting pin is calculated, so the minimum value d of the screw rod diameter of the limiting pin (40) is determined by adopting the following method Screw min :
Wherein:
[ tau ] is the allowable shear stress of the bolt material;
and 6, designing the folding propeller system capable of being automatically unfolded and limited according to the related parameters designed in the steps 2 to 5 and the structure of the folding propeller system capable of being automatically unfolded and limited.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310569107.7A CN116495167A (en) | 2023-05-19 | 2023-05-19 | Folding propeller system capable of being automatically unfolded and limited and design method |
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| CN202310569107.7A CN116495167A (en) | 2023-05-19 | 2023-05-19 | Folding propeller system capable of being automatically unfolded and limited and design method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116853559A (en) * | 2023-09-04 | 2023-10-10 | 北京卓翼智能科技有限公司 | Unmanned aerial vehicle screw automatic folding mechanism |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116853559A (en) * | 2023-09-04 | 2023-10-10 | 北京卓翼智能科技有限公司 | Unmanned aerial vehicle screw automatic folding mechanism |
| CN116853559B (en) * | 2023-09-04 | 2024-02-09 | 北京卓翼智能科技有限公司 | Unmanned aerial vehicle screw automatic folding mechanism |
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