JP7706087B2 - Propeller Guard - Google Patents

Description

This disclosure relates to a propeller guard.

A bridge inspection method is known that includes a first step of taking video for inspecting a bridge using an inspection camera unit capable of 360-degree shooting that is mounted on an unmanned aerial vehicle housed in a spherical protective member, a second step of taking video of the unmanned aerial vehicle flying near the bridge from a distance away from the unmanned aerial vehicle, and a third step of displaying the inspection video taken in the first step and the flight video taken in the second step in a synchronized state on a video synchronization display unit later (see Patent Document 1).

Patent No. 6684507

In consideration of the above-mentioned conventional circumstances, the present disclosure provides a propeller guard that can prevent a flying object moving vertically from stopping flight when it comes into contact with an object.

The present disclosure provides a propeller guard that surrounds a propeller of an aircraft having at least three or more horizontal ribs extending radially from a main body, an outermost ring rib connecting the tips of the horizontal ribs, a motor fixed to the horizontal ribs and having a propeller fixed to a drive shaft in a substantially vertical direction, and a connecting ring rib arranged vertically above the main body, the propeller guard comprising a bumper arranged radially from the connecting ring rib, having an upper end fixed to the connecting ring rib and a lower end fixed to the outermost ring rib, and having an inclination angle that gradually increases from the connecting ring rib to the outermost ring rib, the bumper being supported rotatably and protruding outside the bumper by at least a portion of the rotation radius, and having a plurality of rollers arranged in an inclined direction, the outside of the bumper being opposite the side facing the main body of the aircraft .

The present disclosure provides a propeller guard that surrounds the propeller of an aircraft having at least three or more horizontal ribs extending radially from a main body, an outermost ring rib connecting the tips of the horizontal ribs, a motor fixed to the horizontal ribs and having a propeller fixed to a drive shaft in a substantially vertical direction, and a connecting ring rib arranged vertically above the main body, the propeller guard comprising bumpers arranged radially from the connecting ring rib, with upper ends fixed to the connecting ring rib and lower ends fixed to the outermost ring rib, and an inclination angle that gradually increases from the connecting ring rib to the outermost ring rib, and a mesh member that covers the gap between adjacent bumpers and has an opening that surrounds the beam irradiation range of a TOF sensor arranged between the main body and the connecting ring rib.

The present disclosure makes it possible to prevent a flying object moving vertically from ceasing flight when it comes into contact with an object.

1 is a side view of an aircraft equipped with a propeller guard according to a first embodiment; FIG. 2 is a perspective view of the aircraft shown in FIG. 1, with a portion of the aircraft omitted, viewed from diagonally below. FIG. 2 is a plan view of the flying vehicle shown in FIG. Schematic diagram of the bumper seen from the side Bumper side view Side view of a bumper with a protrusion Exploded perspective view of the bumper A perspective view of a flying object showing the beam irradiation range of a TOF sensor. A perspective view of a mesh member Diagram of when a flying object touches a step during ascent An explanatory diagram showing the process by which an aircraft equipped with a mesh member having openings avoids getting caught A front view showing the opening An explanatory diagram showing the process by which an aircraft avoids getting caught on various structures.

(How one embodiment of the present disclosure was achieved)
For example, in a bridge inspection, an inspection camera unit installed in an unmanned aerial vehicle housed in a spherical protective member may be used to take photographs for inspecting the bridge. The spherical protective member is formed by arranging a plurality of triangles, each of which is made up of a frame member with three sides, in a spherical shape, and covers the unmanned aerial vehicle. The spherical protective member has a suitable degree of flexibility. By providing each joint (corner) of the protective member with a material having a suitable degree of flexibility, the protective member can prevent the bridge from being damaged even if the unmanned aerial vehicle collides with the bridge during flight. However, for example, an unmanned aerial vehicle (a so-called drone) flying to inspect the inside of a manhole may get caught on a structure such as a step or a receiving frame when passing through the neck of the manhole, and the flight may be stopped.

Below, we explain an example of a propeller guard that can prevent a flying object moving vertically from stopping when it comes into contact with an object.

Below, with reference to the drawings as appropriate, an embodiment specifically disclosing the propeller guard according to the present disclosure will be described in detail. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the attached drawings and the following explanation are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
1 is a side view of an aircraft 13 equipped with a propeller guard 11 according to embodiment 1. First, an outline of the configuration of the aircraft 13 equipped with the propeller guard 11 according to embodiment 1 will be described.

The flying object 13 has a main body 15 including a drive board, and at least three horizontal ribs 17 (see FIG. 2) extending radially from the main body 15. In the first embodiment, the horizontal ribs 17 are, for example, four, but as described above, the number is not limited to four as long as there are three or more. The tips of the horizontal ribs 17 extending from the main body 15 are connected to the inner diameter side of a first outermost ring rib 19 that is annular in the horizontal plane. The first outermost ring rib 19 is an annular rib that is octagonal in plan view (see FIG. 3). The first outermost ring rib 19 has an octagonal horizontal cross section at the outermost shape of the flying object 13.

A second outermost ring rib 21, which has the same shape as the first outermost ring rib 19, is fixed at a distance above the first outermost ring rib 19 by a vertical rib 23. The first outermost ring rib 19 and the second outermost ring rib 21 overlap in a plan view. In the first embodiment, the outermost ring rib is configured as a two-stage structure by the first outermost ring rib 19 and the second outermost ring rib 21, but may be a single-stage structure as long as a space is secured to avoid interference with the propeller 27 described later.

Figure 2 is a perspective view of the flying object 13 shown in Figure 1, with a portion thereof omitted, viewed from diagonally below. A motor 25 is fixed to each horizontal rib 17 at approximately halfway along the extension direction. In other words, four motors 25 are arranged. Each motor 25 has a drive shaft that is approximately vertical and protrudes upward. A propeller 27 is fixed to the drive shaft. In the first embodiment, the propeller 27 has four blades to correspond to the number of motors 25 arranged, but the number of motors 25 arranged and the number of blades of the propeller 27 are not limited to these values.

In the first embodiment, four horizontal ribs 17 are provided, and propellers 27 are arranged corresponding to each horizontal rib 17. In the first embodiment, a quadcopter (an example of a drone) having four propellers 27, which has a small number of parts and is relatively easy to control, is described as an example, but the flying object 13 may also be a tricopter (an example of a drone) having three propellers 27, a hexacopter (an example of a drone) having six propellers 27, or an octocopter (an example of a drone) having eight propellers 27.

In a quadcopter, adjacent propellers 27 rotate in opposite directions to each other to cancel out the gyro moment around the yaw axis, which is an inverting torque. Gravity, lift, thrust, and drag are applied to the main body 15. In a quadcopter, lift and thrust are generated by the rotation of the propellers 27. In a windless state, if the sum of lift and thrust balances gravity, the main body 15 will be horizontally stationary (hovering state). If the rotational speed of all four propellers 27 is increased in the same way, the sum of lift and thrust will exceed gravity and the main body 15 will rise. Conversely, if the rotational speed of all four propellers 27 is decreased, the sum of lift and thrust will be less than gravity and the main body 15 will descend.

In this flying object 13, a combined lift and a combined thrust act on the radial center where the four propellers 27 are arranged. In the first embodiment, this radial center is referred to as the main body center 29 of the flying object 13.

As shown in FIG. 1, a flight controller 33 is provided above the main body 15 via a plurality of standing ribs 31. A substrate 37 is supported above the flight controller 33 by standing ribs 35. Four sensors (e.g., TOF (Time Of Flight) sensor 39) are arranged on the substrate 37, with beam directions being four directions of radiation from the center 29 of the main body. A camera 43 (see FIG. 3) is arranged above the substrate 37 via standing ribs 41. The optical axis of the optical system of the camera 43 is arranged substantially coaxially in the vertical direction passing through the center 29 of the main body. A leg shaft 45 is vertically attached to the lower side of each horizontal rib 17. In addition, a second camera 47, a distance sensor 49, a communication device 51, etc. are arranged on the underside of the main body 15. The distance sensor 49 is, for example, an ultrasonic sensor or a distance sensor.

Figure 3 is a plan view of the flying object 13 shown in Figure 1. The flying object 13 has a connecting ring rib 53 arranged vertically above the main body 15. The connecting ring rib 53 is formed in a circular ring shape. The connecting ring rib 53 connects the upper end 57 of each bumper 55, which is a component of the propeller guard 11 arranged in the radial direction, at the radial center side of each of the multiple bumpers 55. In the first embodiment, the bumpers 55 are, for example, eight, but the number is not limited to eight. The connecting ring rib 53 connects the upper end 57 of each bumper 55 and is supported by each bumper 55, and is arranged above the main body 15 at a distance. The bumpers 55 of the propeller guard 11 are arranged in the radial direction with the connecting ring rib 53 as the center, and the upper end 57 is fixed to the connecting ring rib 53, and the lower end 59 is fixed to the second outermost ring rib 21 as shown in Figure 1.

Figure 4 is a schematic diagram of the bumper 55 as seen from the side. Each bumper 55 is formed so that the inclination angle θ gradually increases from the connecting ring rib 53 toward the second outermost ring rib 21. Here, "gradually increasing" is a term that includes the concepts of both a curved, bent shape in which the inclination angle increases continuously, and a broken line-like bent shape in which the inclination angle increases stepwise. Considering contact with objects when the aircraft 13 ascends in the vertical direction, it is more preferable that the propeller guard 11 has a curved, bent shape without corners.

In FIG. 4, when a virtual circle of radius R is drawn from the origin of the orthogonal XY axes, the curve of the bumper 55 in the side view shown in FIG. 4 has a starting point Ps (upper end) that intersects with the vertical axis Y1, which corresponds to the line of the Y axis moving in the -X direction (leftward on the paper). The inclination angle θ1 of the tangent 61 to the horizontal line HL at the starting point Ps is set to, for example, about 21°, and the inclination angle θ2 of the tangent 61 to the horizontal line HL at the end Pe is set to, for example, about 80°. The inclination angle θ4 of the curve of the bumper 55 at a point the same distance L from the starting point Ps is greater than the inclination angle θ3 at a point the same distance L from the Y axis of the arc of radius R that is the starting point Ps1. In other words, at the same distance L from the main body center 29, the inclination angle θ of the bumper 55 is greater than that of the curve of radius R, making it easier to slip.

The curve of the bumper 55 is not limited to a circular arc. For example, it can be an elliptical curve with a major axis that is a vertical line passing through the body center 29. In this case, the outer shell shape of the flying object 13 is the surface shape of a spheroid with a major axis that is a vertical line passing through the body center 29. As described above, the inclination angle θ of this spheroid surface shape is larger than that of a spherical shape at the same distance from the body center 29, so that even if the bumper 55 comes into contact with an object when the flying object is ascending, it will slide easily.

In the first embodiment, as shown in FIG. 3, multiple bumpers 55 are arranged at equal intervals in the circumferential direction and in eight radial directions. Each bumper 55 is formed in a plate shape with a thickness t in the direction of a tangent 61 at the point where the bumper 55 intersects with the outer diameter circle of the connecting ring rib 53 shown in FIG. 3. Every other propeller 27 is arranged below the space formed between the bumpers. The propeller guard 11 having eight bumpers 55 completely covers and surrounds the propeller 27 of the aircraft 13.

In the first embodiment, the propeller guard 11 covers the upper half of the flying object 13 and acts to prevent it from getting caught during ascent, but if a similar configuration is inverted upside down to cover the lower half of the flying object 13, it can similarly prevent it from getting caught during descent. Below, the function and configuration of the propeller guard 11 during ascent will be mainly described as a representative example.

Figure 5 is a side view of bumper 55. Multiple rollers 63 are arranged in the bumper 55 in an oblique direction. The rollers 63 protrude outside the bumper 55 by at least a portion of their turning radius.

The rollers 63 are arranged so that they are densely packed on the lower side of the bumper 55 in the tilt direction and sparsely packed on the upper side of the bumper 55 in the tilt direction. Here, "dense" means that the density of the roller outer periphery length per unit area on the bumper contact surface facing the object is high. In other words, it means that the outer peripheries of adjacent rollers are adjacent to each other at a close distance. Also, "sparse" means that the density of the roller outer periphery length per unit area on the bumper contact surface facing the object is low. In other words, it means that the outer peripheries of adjacent rollers are adjacent to each other at a large distance. Therefore, even if the pitch (spacing) between the central axes of adjacent rollers is large, if the outer diameter of the rollers is large, it is possible to achieve dense (a state in which the outer peripheries of the rollers 63 are close to each other). Conversely, even if the pitch (spacing) between the central axes of adjacent rollers is small, if the outer diameter of the rollers is small, it is sparse (a state in which the outer peripheries of the rollers 63 are separated). In other words, the density is determined by the distance between the outer peripheries of adjacent rollers.

In the first embodiment, the rollers 63 are configured to have a larger diameter as they move downward in the inclination direction of the bumper 55. As an example, the first five rollers from the connecting ring rib 53 are small rollers 65 with an outer diameter of 8 mm. The sixth to eighth rollers from the connecting ring rib 53 are medium rollers 67 with an outer diameter of 10 mm. The ninth to fourteenth rollers from the connecting ring rib 53 are large rollers 69 with an outer diameter of 12 mm.

Figure 6 is a side view of the bumper 55 with the protrusions 71 formed. The bumper 55 may have the protrusions 71 formed between adjacent rollers. The protrusions 71 protrude radially outward at a position lower than the outer diameter of the roller. The protrusions 71 are formed in a mountain-shaped protrusion with a smooth curve without corners. The height of the protrusion can be set according to the outer diameter size of the roller 63. That is, the height of the protrusion can be made small between small rollers in the above example, a little larger between medium rollers, and even larger between large rollers. Note that in Figure 6, the inner circumference of the bumper 55 is linear, but the frame may be made corrugated by providing recesses. By making it corrugated, the width of the frame can be made narrower than that of Figure 6, and the weight can be reduced.

7 is an exploded perspective view of the bumper 55. The bumper 55 is assembled by bonding a pair of plate-shaped bumper frames 73 and a bumper frame 75 together in the plate thickness direction. A plurality of support shafts 77 are fixed to one of the bumper frames 73 at intervals in the extension direction of the bumper 55 in a direction perpendicular to the radial direction of the bumper 55 (i.e., in the plate thickness direction). The inner holes of the annular rollers 63 are inserted into the support shafts 77 and attached. The one bumper frame 73 with the rollers 63 attached to the support shafts 77 is assembled by fixing the support shafts 77 to the bumper frame 75 by fitting the support shafts 77 into the shaft holes 79 formed in the other bumper frame 75. The rollers 63 may be supported by a short shaft 81 shorter than the support shafts 77, and the shaft ends may be abutted against the bumper frame 75 to prevent them from falling off. The bumper 55 may be fixed by thermal welding or ultrasonic welding between the support shaft 77 and the shaft hole 79.

The material of the bumper 55 is, for example, ABS, which is lightweight and has high strength. The material of the roller 63 is, for example, PTFE, which is lightweight and has smoothness. Note that the materials of the bumper 55 and the roller 63 are not limited to these.

Figure 8 is a perspective view of the flying object 13, which shows a schematic of the beam irradiation range 83 of the TOF sensor 39. The propeller guard 11 can be configured with a mesh member 85 in addition to the bumpers 55. The mesh member 85 is a structural material with a mesh that covers the gaps between adjacent bumpers. In the flying object 13, eight bumpers 55 are arranged radially, so a total of eight mesh members 85 are used, one between each bumper.

The above-mentioned TOF sensor 39 is disposed in the flying object 13 between the main body 15 and the connecting ring rib 53. The TOF sensor 39 is used in a measurement method using the TOF method. In measurement using the TOF method, the time it takes for a pulsed laser beam emitted from the TOF sensor 39 to return to the light receiving element in the TOF sensor is measured, and the time is converted into distance. The mesh member 85 has an opening 87 that surrounds the beam irradiation range 83 of the TOF sensor 39.

Figure 9 is a perspective view of mesh member 85. Opening 87 of mesh member 85 is formed as a quadrilateral with diagonals 89 arranged vertically. Mesh member 85 has a mesh of openings of various sizes, also quadrilaterals or triangles, formed around opening 87, with opening 87 having the largest opening area. As described below, opening 87 acts to prevent flying object 13 from coming into contact with and getting caught on structures (such as steps or receiving frame 97) when passing through neck 93 of manhole 91.

In addition, the flying body 13 has a wire 99 (see FIG. 8) stretched with a predetermined tension between the tip of the landing gear 45 and the first outermost ring rib 19. The wire 99 connects the tips of the four landing gears 45 to each other in a ring (square shape). The wire 99 is also stretched in a V-shape from the tip of each landing gear 45 to both ends of one side of the first outermost ring rib 19 that is adjacent to each other. The wire 99 prevents a structure (such as a step or a receiving frame 97) that approaches relatively from below the flying body 13 from entering and getting caught between the landing gears, or between the landing gear 45 and the first outermost ring rib 19 when the flying body 13 descends. As described above, if the flying body 13 has a bumper 55 that covers the upper half, in addition to the bumper 55 that covers the lower half by flipping the same configuration upside down, the wire 99 will not be necessary. By including the wires 99, the flying object 13 can be made lighter and less expensive than if it were equipped with a bumper 55 that covers the lower half.

Next, we will explain the operation of the propeller guard according to the first embodiment described above.

The propeller guard 11 according to the first embodiment is configured to surround the propeller 27 of the flying object 13. Specifically, the propeller guard 11 includes at least three horizontal ribs 17 extending radially from the main body 15 of the flying object 13, a second outermost ring rib 21 connecting the tips of the horizontal ribs 17, a connecting ring rib 53 arranged vertically above the main body 15, and a bumper 55 arranged radially from the connecting ring rib 53, an upper end 57 fixed to the connecting ring rib 53 and a lower end 59 fixed to the outermost ring rib, and an inclination angle gradually increasing from the connecting ring rib 53 to the outermost ring rib. The flying object 13 includes a motor 25 fixed to the horizontal rib 17 and having a propeller 27 fixed to a drive shaft in a substantially vertical direction.

Figure 10 is an explanatory diagram of when the flying object 13 comes into contact with a step 95 during ascent. When the flying object 13 is ascending vertically upward in the flight space, the bumper 55 may unintentionally come into contact with a protruding object (e.g., step 95) that protrudes perpendicularly to the direction of travel. When the protruding object is a step 95, the maximum protruding length S is generally standardized as 8 cm. In this case, the step 95 comes into contact with the bumper 55 that is outside the center 29 of the main body of the flying object 13. Because the bumper 55 slides against the step 95 toward the outermost ring rib, the flying object 13 can proceed in the direction of travel without stopping.

The inclination angle θ of each bumper 55 gradually increases toward the second outermost ring rib 21. The propeller guard 11 covers the upper half of the flying vehicle 13 and acts to prevent it from getting caught during ascent.

The flying body 13 has a motor 25 with a propeller 27 fixed to a horizontal rib 17 extending radially from the main body 15. The flying body 13 according to the first embodiment, a quadcopter, has four propellers 27. In this flying body 13, a combined lift and a combined thrust act on the radial center where the four propellers 27 are located.

In plan view, the closer the flying object 13 is to the center 29 of the main body, the less it is affected by the reaction force from an object that it collides with during ascent. In contrast, the further away from the center 29 of the main body the flying object 13 is, the more it is affected by the reaction force from an object that it collides with during ascent. For this reason, even if an object does not get caught near the center 29 of the main body, if it hits a position farther away from the center 29 of the main body, it tends to get caught because the effect of the combined lift is smaller due to the principle of leverage. In other words, it is easy for the flying object to tilt forward and backward (pitch) or sideways (roll). When this pitch or roll occurs, the wind is blown out from the bottom of the propeller 27 and sucked in from the top of the propeller 27, and the flying object may stick to the wall and instantly lose its balance.

Therefore, the bumper 55 of the propeller guard 11 is formed with an inclination angle θ2 as large as possible (approaching 90 degrees) at a position radially outward from the center 29 of the main body. Even if the bumper 55 comes into contact with an object at a position radially outward from the center 29 of the main body, the flying object 13 slides easily and is less likely to get caught. In addition, the sliding reduces the reaction force from the object, making it less likely to lose flight balance. For example, when the flying object 13 flying to inspect the inside of a manhole passes through the neck 93 of the manhole 91, it can pass through without getting caught even if it comes into contact with a structure (such as a step or receiving frame 97). As a result, it is possible to prevent the flying object 13 moving vertically from stopping when it collides with an object.

In addition, in the propeller guard 11, the bumper 55 is rotatably supported by a support shaft 77 perpendicular to the radial direction, and at least a portion of the rotation radius protrudes outside the bumper 55 and has multiple rollers 63 arranged in an inclined direction.

In this propeller guard 11, rollers 63 are attached to the bumpers 55. The rollers 63 are rotatable on support shafts 77 that are perpendicular to the radial direction. In the first embodiment, the radial directions are eight directions that are equally spaced in the circumferential direction. In other words, the angle between adjacent bumpers 55 is 45°. The direction perpendicular to the radial direction is the tangent direction at the point where the bumpers 55 intersect with the outer diameter circle of the connecting ring rib 53 in a plan view.

At least a portion of the rotation radius of the rollers 63 protrudes outside the bumper 55. A number of rollers 63 are arranged in the inclined direction of the bumper 55. Even if the flying object 13 comes into contact with an object during ascent, the rollers 63 make contact and rotate, making it extremely easy to slide and unlikely to get caught. In addition, because the flying object slides easily, the reaction force from the object is further reduced, making it even less likely to lose flight balance.

In addition, in the propeller guard 11, the distance between adjacent rollers among the multiple rollers 63 is greater on the upper side of the bumper 55 in the tilt direction than on the lower side of the bumper 55 in the tilt direction. For example, the distance between adjacent rollers among the multiple rollers 63 is dense on the lower side of the bumper 55 in the tilt direction and sparse on the upper side of the bumper 55 in the tilt direction.

In this propeller guard 11, the rollers 63 are dense on the lower side of the inclination direction of the bumper 55 and sparse on the upper side of the inclination direction of the bumper 55. In the propeller guard 11, the rollers 63 are dense on the lower side of the inclination direction away from the body center 29, increasing the probability that an object that collides during ascent will hit the rollers 63. If an object hits the rollers 63 when the flying object 13 is rising, the sliding friction can be reduced compared to when the object hits the bumper 55 directly, making it less susceptible to the effects of reaction forces from the object. In addition, by making the rollers 63 sparse on the upper side of the inclination direction of the bumper 55, which is less susceptible to the effects of reaction forces from objects, the flying object 13 can be made lighter.

In addition, in the propeller guard 11, the rollers 63 become larger in diameter as they move downward in the inclination direction of the bumper 55.

In this propeller guard 11, the mass of one bumper is the sum of the roller plate and the roller bearing axle. When the roller bearing axle accounts for a large proportion of the mass, the mass can be reduced by closely arranging large diameter rollers 63 rather than closely arranging small diameter rollers 63. In the propeller guard 11, by arranging rollers 63 whose diameters increase toward the lower side of the inclination direction of the bumper 55, it is possible to reduce the weight of the aircraft 13 while closely arranging the rollers 63 on the lower side of the inclination direction of the bumper 55.

In addition, in the propeller guard 11, the bumper 55 has a convex portion 71 formed between adjacent rollers that protrudes outward at a position lower than the outer diameter of the roller.

In this propeller guard 11, a convex portion 71 (bump) is formed between the rollers of the bumper 55. The convex portion 71 protrudes outward from the bumper 55 at a position lower than the outer diameter of the roller. In other words, an object will come into contact with the roller 63 before the convex portion 71 does. The convex portion 71 is formed, for example, with a convex curved surface that is less likely to get caught.

If there is a gap between the rollers of the bumper 55, depending on the shape of the object, it may get caught between the rollers. Or, if the object hits the gap between the rollers, it may become a fulcrum, causing the flying object 13 to rotate significantly.

In the bumper 55, a protrusion 71 is provided in the gap between the rollers, so that an object strikes the protrusion 71 between the rollers and is guided to the roller 63. Even if an object enters between the rollers during ascent of the flying object 13, the object strikes the protrusion 71 and is guided to the roller 63, so that the object is less likely to slip and get caught due to the same action as described above. As a result, the object can be prevented from getting caught between the rollers and causing the flying object 13 to rotate.

A wire 99 is also provided to stretch between the first outermost ring rib 19 and the tip of the leg shaft 45.

This wire 99 allows the flying object 13 to pass through without getting caught even if the landing gear 45 comes into contact with a structure as it descends through the neck 93 of the manhole 91.

The propeller guard 11 according to the first embodiment is configured to surround the propeller 27 of the flying object 13. Specifically, the propeller guard 11 includes at least three horizontal ribs 17 extending radially from the main body 15 of the flying object 13, a second outermost ring rib 21 connecting the tips of the horizontal ribs 17, a connecting ring rib 53 arranged vertically above the main body 15, a bumper 55 arranged radially from the connecting ring rib 53, an upper end 57 fixed to the connecting ring rib 53 and a lower end 59 fixed to the outermost ring rib, and a mesh member 85 having an opening 87 that covers the gap between adjacent bumpers and surrounds the beam irradiation range 83 of a sensor (e.g., a TOF sensor 39) arranged between the main body 15 and the connecting ring rib 53. The flying object 13 includes a motor 25 fixed to the horizontal rib 17 and having a propeller 27 fixed to a drive shaft in a substantially vertical direction.

The inclination angle θ of each bumper 55 gradually increases toward the second outermost ring rib 21. The propeller guard 11 covers the upper half of the flying vehicle 13 and acts to prevent it from getting caught during ascent.

The flying body 13 has a motor 25 with a propeller 27 fixed to a horizontal rib 17 extending radially from the main body 15. The flying body 13 according to the first embodiment, a quadcopter, has four propellers 27. In this flying body 13, a combined lift and a combined thrust act on the radial center where the four propellers 27 are located.

In plan view, the closer the flying object 13 is to the center 29 of the main body, the less it is affected by the reaction force from an object that it collides with during ascent. In contrast, the further away from the center 29 of the main body the flying object 13 is, the more it is affected by the reaction force from an object that it collides with during ascent. For this reason, even if an object does not get caught near the center 29 of the main body, if it hits a position farther away from the center 29 of the main body, it tends to get caught because the effect of the combined lift is smaller due to the principle of leverage. In other words, it is easy for the flying object to tilt forward and backward (pitch) or sideways (roll). When this pitch or roll occurs, the wind is blown out from the bottom of the propeller 27 and sucked in from the top of the propeller 27, and the flying object may stick to the wall and instantly lose its balance.

Therefore, the bumper 55 of the propeller guard 11 is formed with an inclination angle θ as large as possible (approaching 90 degrees) at a position radially outward from the center 29 of the main body. Even if the bumper 55 comes into contact with an object at a position radially outward from the center 29 of the main body, the flying object 13 slides easily and is less likely to get caught. In addition, the sliding reduces the reaction force from the object, making it less likely to lose flight balance. For example, when the flying object 13 flying to inspect the inside of a manhole passes through the neck 93 of the manhole 91, it can pass through without getting caught even if it comes into contact with a structure (such as a step or receiving frame 97). As a result, it is possible to prevent the flying object 13 moving vertically from stopping when it collides with an object.

Figure 11 is an explanatory diagram showing the process by which an aircraft 13 equipped with a mesh member 85 having an opening 87 avoids getting caught. In addition, the propeller guard 11 is equipped with a mesh member 85 that covers the gap between adjacent bumpers. The mesh member 85 is configured so that the field of view of the TOF sensor 39 installed in the middle of the main body 15 and the connecting ring rib 53 is almost the opening 87. In other words, the mesh member 85 is formed so as not to block the irradiation beam or reflected beam from the TOF sensor 39 by providing the opening 87.

The mesh member 85 of the propeller guard 11 makes it difficult for structures to get into the gaps formed between the bumpers, and prevents them from getting caught on the second outermost ring rib 21, allowing them to pass through. As a result, it is possible to prevent the flying object 13 moving vertically from stopping when it collides with an object.

In addition, in the propeller guard 11, the opening 87 is formed into a quadrilateral with diagonals 89 arranged above and below.

Figure 12 is a front view showing the opening 87. In this propeller guard 11, the opening 87 is opened to a certain size (with a margin) so as not to block the irradiation beam or reflected beam (i.e., the field of view) from the TOF sensor 39. For this reason, there is a possibility that a relatively small structure (such as the corner of the step 95) may get into the opening 87.

Therefore, the opening 87 is formed in a quadrilateral with diagonals 89 arranged vertically. The quadrilateral is, for example, a rhombus. In the rhombus opening 87, the two lower sides 101 gradually approach and intersect toward the lower diagonal 89. For example, assume that the corner of the step 95 enters the opening 87 of the mesh member 85 as the flying object 13 ascends, as shown in FIG. 11. Then, as the flying object 13 ascends, the two lower sides 101 relatively guide the corner of the step 95. As a result, the step 95 does not remain stuck in the opening 87, but is pushed relatively outward from the opening 87 while sliding along the two lower sides 101 (in reality, the flying object 13 moves away from the step 95) and is discharged. As a result, the flying object 13 can escape from the step 95. The above explanation is for when the flying object 13 is ascending, but even when it is descending, if the step 95 fits into the opening 87 of the mesh member 85, the flying object 13 can escape from the step 95 in the same manner (upper two sides 103).

Figure 13 is an explanatory diagram showing the process by which the flying object 13 avoids getting caught on various structures. When the flying object 13 ascends, the propeller guard 11 equipped with the bumper 55 and mesh member 85 can prevent the flying object 13 from getting caught on the step 105 of the manhole 91 or the receiving frame 97 of the manhole cover by the sliding action of the bumper 55 and the pushing action of the opening 87 as described above. As a result, even during automatic flight beyond visual line of sight, the flying object itself is less likely to get caught on objects, and it can proceed in the direction of travel without stopping.

Therefore, the propeller guard 11 according to the first embodiment can prevent the flying object 13 moving vertically from stopping when it comes into contact with an object.

Although the embodiments have been described above with reference to the drawings, it goes without saying that the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, amendments, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure. Furthermore, the components in the above-described embodiments may be combined in any manner as long as it does not deviate from the spirit of the invention.

This disclosure is useful as a propeller guard that can prevent a flying object moving vertically from stopping flight when it comes into contact with an object.

REFERENCE SIGNS LIST 11 Propeller guard 13 Aircraft 15 Main body 17 Horizontal rib 19 First outermost ring rib 21 Second outermost ring rib 25 Motor 27 Propeller 39 TOF sensor 53 Connecting ring rib 55 Bumper 57 Upper end 59 Lower end 63 Roller 71 Convex portion 77 Support shaft 83 Beam irradiation range 85 Mesh member 87 Opening 89 Diagonal angle θ Tilt angle

Claims (7)

A propeller guard configured to surround a propeller of an aircraft,
Horizontal ribs extending radially from the body of the flying vehicle;
An outermost ring rib connecting tips of the horizontal ribs;
A connecting ring rib arranged vertically above the main body;
a bumper disposed radially from the connecting ring rib, the bumper having an upper end fixed to the connecting ring rib and a lower end fixed to the outermost ring rib, the bumper having an inclination angle gradually increasing from the connecting ring rib toward the outermost ring rib ,
The bumper has a plurality of rollers that are rotatably supported, protrude at least a portion of a turning radius outside the bumper, and are disposed in an inclined direction;
The outer side of the bumper is opposite to the side facing the main body of the aircraft .
Propeller guard. a distance between adjacent rollers among the plurality of rollers is greater on an upper side in a tilt direction of the bumper than on a lower side in a tilt direction of the bumper;
2. The propeller guard of claim 1 . The roller has a larger diameter toward the lower side in the inclination direction of the bumper.
3. The propeller guard of claim 2 . The bumper has a protrusion formed between adjacent rollers, the protrusion protruding outward at a position lower than the outer diameter of the rollers ,
The outer side is the side of the bumper opposite to the main body of the aircraft .
2. The propeller guard of claim 1 . A propeller guard configured to surround a propeller of an aircraft,
Horizontal ribs extending radially from the body of the flying vehicle;
An outermost ring rib connecting tips of the horizontal ribs;
A connecting ring rib arranged vertically above the main body;
a bumper disposed radially from the connecting ring rib, the bumper having an upper end fixed to the connecting ring rib and a lower end fixed to the outermost ring rib, the bumper having an inclination angle gradually increasing from the connecting ring rib toward the outermost ring rib,
A wire is further provided to stretch between the outermost ring rib and the tip of the leg of the aircraft .
Propeller guard. A propeller guard configured to surround a propeller of an aircraft,
At least three horizontal ribs extending radially from the body of the aircraft;
An outermost ring rib connecting tips of the horizontal ribs;
A connecting ring rib arranged vertically above the main body;
a plurality of bumpers arranged in a radial direction around the connecting ring rib, the bumpers having upper ends fixed to the connecting ring rib and lower ends fixed to the outermost ring rib;
a mesh member covering the gap between adjacent bumpers and having an opening surrounding a beam irradiation range of a sensor disposed between the main body and the connecting ring rib;
Propeller guard. The opening is formed into a quadrilateral with diagonals arranged above and below.
7. The propeller guard of claim 6 .

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