Propeller guard

Abstract

To make it possible to prevent flight from stopping when a flight body moving in a vertical direction is brought into contact with an object.SOLUTION: A propeller guard 11 surrounds propellers 27 of a flight body 13 including: at least three pieces of horizontal ribs 17 extending in a radial direction from a body 15; outermost annular ribs (second outermost annular ribs 21) respectively connecting the tip ends of the horizontal ribs 17; a motor 25 which is fixed to the horizontal ribs 17 and has the propellers 27 fixed to an almost vertical driving shaft thereof; and connected annular ribs 53 disposed to the body 15 on the upper side in a vertical direction. The propeller guard is provided with a bumper 55 which is disposed in a radial direction around the connected annular ribs 53, has an upper end part 57 fixed to the connected annular ribs 53, and a lower end part 59 fixed to the outermost annular ribs, and has the inclination angle gradually increased toward the outermost annular ribs from the connected annular ribs 53.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a propeller guard.

Background Art

[0002] A first step of performing video shooting for inspecting a bridge using an inspection camera unit capable of 360-degree shooting disposed on an unmanned aircraft housed in a spherical protective member; a second step of performing video shooting from a distance away from the unmanned aircraft of the state in which the unmanned aircraft is flying near the bridge; and a third step of subsequently displaying the inspection video shot in the first step and the flight video shot in the second step on a video synchronization display unit in a synchronized state. A bridge inspection method characterized by comprising these steps is known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In view of the above-described conventional circumstances, the present disclosure provides a propeller guard capable of suppressing the flight from stopping when a flying object moving in the vertical direction comes into contact with an object.

Means for Solving the Problems

[0005] The present disclosure provides a propeller guard surrounding the propeller of a flying object, comprising 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 disposed vertically above the main body. The propeller guard is arranged radially around the connecting ring rib, with an upper end fixed to the connecting ring rib and a lower end fixed to the outermost ring rib, and includes a bumper whose inclination angle gradually increases from the connecting ring rib toward the outermost ring rib. The bumper is rotatably supported and has a plurality of rollers that project at least a part of the turning radius to the outside of the bumper and are arranged in an inclined direction. The outside of the bumper is the side opposite to the side facing the main body of the flying object. A propeller guard is provided.

[0006] The present disclosure provides a propeller guard surrounding the propeller of a flying object, comprising 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 disposed vertically above the main body. The propeller guard is arranged radially around the connecting ring rib, with an upper end fixed to the connecting ring rib and a lower end fixed to the outermost ring rib, and includes a bumper whose inclination angle gradually increases from the connecting ring rib toward the outermost ring rib, and a mesh member covering the gaps between adjacent bumpers and having an opening surrounding the beam irradiation range of a TOF sensor disposed between the main body and the connecting ring rib.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to prevent the flight from stopping when a flying object moving in the vertical direction contacts an object.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0009] (Background Leading to One Embodiment of the Present Disclosure) For example, in bridge inspection, photography may be performed for inspecting a bridge using an inspection camera unit arranged on an unmanned aircraft housed in a spherical protective member. The spherical protective member is formed by arranging a plurality of triangles composed of three-sided frame members in a spherical shape and covers the unmanned aircraft. The spherical protective member has appropriate flexibility. The protective member is provided with a material having appropriate flexibility at each joint (corner portion), so that even if the unmanned aircraft collides with the bridge during flight, it is possible to prevent damage to the bridge. However, for example, an unmanned aircraft (so-called drone) that inspects and flies inside 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 stop.

[0010] Hereinafter, an example of a propeller guard that can suppress the stop of flight when an aircraft moving in the vertical direction contacts an object will be described.

[0011] Hereinafter, embodiments specifically disclosing the propeller guard according to the present disclosure will be described in detail with reference to the drawings as appropriate. However, a more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art. It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and it is not intended to limit the subject matter described in the claims thereby.

[0012] (Embodiment 1) FIG. 1 is a side view of a flying object 13 including a propeller guard 11 according to Embodiment 1. First, an outline of the configuration of the flying object 13 including the propeller guard 11 according to Embodiment 1 will be described.

[0013] The flying object 13 has a main body 15 including a drive board and at least three or more horizontal ribs 17 (see FIG. 2) extending radially from the main body 15. In Embodiment 1, the number of horizontal ribs 17 is, for example, four, but is not limited to four as long as it is three or more as described above. The tip of each horizontal rib 17 extending from the main body 15 is 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 having an octagonal shape in plan view (see FIG. 3). The horizontal cross section of the outermost shape of the flying object 13 is octagonal due to the first outermost ring rib 19.

[0014] Above the first outermost ring rib 19, a second outermost ring rib 21 having the same shape as the first outermost ring rib 19 is fixed at an interval by a vertical rib 23. The first outermost ring rib 19 and the second outermost ring rib 21 overlap in plan view. In Embodiment 1, the outermost ring rib is configured in a two-stage structure by the first outermost ring rib 19 and the second outermost ring rib 21, but may be in a one-stage structure as long as an interference avoidance space with a propeller 27 described later can be secured.

[0015] FIG. 2 is a perspective view of the flying object 13 shown in FIG. 1, with a part thereof omitted, as seen obliquely from below. A motor 25 is fixed to each of the horizontal ribs 17 at a position approximately halfway along the extending direction. That is, four motors 25 are arranged. Each motor 25 has a drive shaft that protrudes upward in a substantially vertical direction. A propeller 27 is fixed to the drive shaft. In Embodiment 1, the propeller 27 has four blades corresponding 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.

[0016] In Embodiment 1, four horizontal ribs 17 are provided, and a propeller 27 is arranged corresponding to each horizontal rib 17. In Embodiment 1, a quadcopter (an example of a drone) having four propellers 27 with a small number of parts and relatively easy control will be described as an example. However, in addition to this, the flying object 13 may 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.

[0017] In a quadcopter, the gyro moment around the yaw axis, which is a reaction torque, is canceled by rotating adjacent propellers 27 in opposite directions. 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 the lift and thrust balances the gravity, the main body 15 will be in a horizontal stationary state (hovering state). If the rotational speeds of all four propellers 27 are increased equally, the sum of the lift and thrust will exceed the gravity and the main body 15 will rise. Conversely, if the rotational speeds of all four propellers 27 are decreased, the sum of the lift and thrust will be less than the gravity and the main body 15 will descend.

[0018] In this flying object 13, a combined lift and a combined thrust act on the radiation center in the radial direction where the four propellers 27 are arranged. In Embodiment 1, this radiation center will be referred to as the main body center 29 of the flying object 13.

[0019] As shown in Fig. 1, above the main body 15, a flight controller 33 is provided via a plurality of upright ribs 31. Above the flight controller 33, a substrate 37 is supported by an upright rib 35. On this substrate 37, four sensors (for example, TOF (Time Of Flight) sensors 39) whose radial directions in four directions from the main body center 29 are the beam directions are arranged. Above the substrate 37, a camera 43 (see Fig. 3) is arranged via an upright rib 41. The camera 43 is arranged such that the optical axis of the optical system is substantially coaxial in the vertical direction passing through the main body center 29. On each of the horizontal ribs 17, a leg shaft 45 is vertically provided on the lower side in the vertical direction. In addition, on the lower surface of the main body 15, a second camera 47, a distance sensor 49, a communication device 51, etc. are arranged. Note that, for example, an ultrasonic sensor or a distance sensor is used as the distance sensor 49.

[0020] Fig. 3 is a plan view of the flying object 13 shown in Fig. 1. Above the main body 15 in the vertical direction of the flying object 13, a connecting ring rib 53 is arranged. The connecting ring rib 53 is formed in a circular ring shape. The connecting ring rib 53 connects the upper end portions 57 of a plurality of bumpers 55 which are constituent members of the propeller guard 11 provided in the radial direction, at the radial center side of each of the bumpers 55. In Embodiment 1, the number of bumpers 55 is, for example, eight, but it may not be limited to eight. The connecting ring rib 53 connects the upper end portions 57 of each of the bumpers 55 and is in a state of being supported by each of the bumpers 55, and is arranged spaced apart above the main body 15. The bumpers 55 of the propeller guard 11 are arranged in the radial direction around the connecting ring rib 53, the upper end portion 57 is fixed to the connecting ring rib 53, and as shown in Fig. 1, the lower end portion 59 is fixed to the second outermost ring rib 21.

[0021] FIG. 4 is a schematic view of the bumper 55 as seen from the side. Each bumper 55 is formed such that the inclination angle θ gradually increases from the connecting ring rib 53 toward the second outermost ring rib 21. Here, "gradually increases" is a term that includes both the concept of a curved bending shape in which the inclination angle continuously increases and the concept of a folded bending shape in which the inclination angle increases step by step. The propeller guard 11 is more preferably a curved bending shape without corners when the aircraft 13 ascends along the vertical direction, considering contact with an object.

[0022] In FIG. 4, when a virtual circle with a 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 its starting point Ps (upper end) as the intersection with the vertical axis Y1 corresponding to the line where the Y axis moves in the -X direction (left direction of the paper surface). The inclination angle θ1 of the tangent line 61 to the horizontal line HL at the starting point Ps is set to about 21°, for example, and the inclination angle θ2 of the tangent line 61 to the horizontal line HL at the ending point Pe is set to about 80°, for example. The inclination angle θ4 at a point at the same distance L from the starting point Ps of the curve of the bumper 55 is larger than the inclination angle θ3 at a point at a distance L from the Y axis of the arc of the radius R that becomes the starting point Ps1. That is, at a position at the same distance L from the body center 29, the inclination angle θ of the bumper 55 is larger than that of the curve of the radius R, making it easier to slide.

[0023] Note that the curve of the bumper 55 is not limited to an arc. For example, it can be an elliptical curve with the vertical line passing through the body center 29 as the major axis. In this case, the outer shell shape of the aircraft 13 is the surface shape of a prolate ellipsoid with the vertical line passing through the body center 29 as the major axis. The surface shape of this prolate ellipsoid has a larger inclination angle θ than the spherical shape at the same distance from the body center 29, so that even when the bumper 55 contacts an object during the ascent of the aircraft, it is easily slidable.

[0024] In Embodiment 1, as shown in FIG. 3, the plurality of bumpers 55 are arranged at equal intervals in the circumferential direction and in the radial direction in eight directions. Each bumper 55 is formed in a plate shape with a thickness t in the direction of the tangent line 61 at the point where the bumper 55 intersects the outer diameter circle of the connecting ring rib 53 shown in FIG. 3. Propellers 27 are arranged every other one below the separation space formed between the bumpers. The propeller guard 11 having eight bumpers 55 surrounds the propeller 27 of the flying body 13 so as to entirely cover it.

[0025] In Embodiment 1, the propeller guard 11 covers the upper half of the flying body 13 and acts to suppress snagging during ascent. However, if the same configuration is inverted up and down to cover the lower half of the flying body 13, snagging during descent can be similarly suppressed. Hereinafter, the propeller guard 11 will be mainly described taking the action and configuration during ascent as a representative example.

[0026] FIG. 5 is a side view of the bumper 55. A plurality of rollers 63 are arranged in the inclined direction on the bumper 55. At least a part of the rotation radius of the roller 63 protrudes outside the bumper 55.

[0027] The rollers 63 are arranged densely on the lower side in the inclined direction of the bumper 55 and sparsely on the upper side in the inclined direction of the bumper 55. Here, "dense" means that the density of the outer peripheral length of the roller per unit area on the bumper contact surface facing the object is high. That is, it means a state where the outer peripheries of adjacent rollers are adjacent at a short distance. Also, "sparse" means that the density of the outer peripheral length of the roller per unit area on the bumper contact surface facing the object is low. That is, it means a state where the outer peripheries of adjacent rollers are adjacent at a long distance. Therefore, even if the pitch (interval) between the central axes of adjacent rollers is large, if the outer diameter of the roller is large, it can be made dense (a state where the outer peripheries of the rollers 63 approach each other). Conversely, even if the pitch (interval) between the central axes of adjacent rollers is small, if the outer diameter of the roller is small, it becomes sparse (a state where the outer peripheries of the rollers 63 are separated). That is, the density is determined by the distance between the outer peripheries of adjacent rollers.

[0028] In Embodiment 1, the roller 63 is configured to have a larger diameter as it goes downward in the inclined direction of the bumper 55. As an example, the first to fifth rollers 63 from the connecting ring rib 53 are small rollers 65 with an outer diameter of 8 mm. The sixth to eighth rollers 63 from the connecting ring rib 53 are medium rollers 67 with an outer diameter of 10 mm. The ninth to fourteenth rollers 63 from the connecting ring rib 53 are large rollers 69 with an outer diameter of 12 mm.

[0029] FIG. 6 is a side view of the bumper 55 with the convex portion 71 formed. The convex portion 71 may be formed between adjacent rollers of the bumper 55. The convex portion 71 projects radially outward at a position lower than the outer diameter of the roller. The convex portion 71 is formed in a shape that rises in a mountain shape with a smooth curve without corners. The height of the rise can be set according to the outer diameter size of the roller 63. That is, the height of the rise can be made smaller between the small rollers according to the above example, a little larger between the medium rollers, and even larger between the large rollers. In FIG. 6, the inner circumference of the bumper 55 is shown as a straight shape, but a concave portion may be provided to make the frame in a waveform shape. By making it in a waveform shape, the width of the frame can be made narrower compared to FIG. 6, and weight reduction can be achieved.

[0030] FIG. 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 in the plate thickness direction. A plurality of support shafts 77 in the direction orthogonal to the radial direction of the bumper 55 (i.e., the plate thickness direction) are fixed to one of the bumper frames 73 at intervals in the extending direction of the bumper 55. The inner holes of the annular rollers 63 are inserted and attached to the respective support shafts 77. One bumper frame 73 with the rollers 63 attached to the support shafts 77 has the support shafts 77 fitted into the shaft holes 79 formed in the other bumper frame 75, and is assembled by being integrally fixed to the bumper frame 75 with an adhesive or the like. Note that the roller 63 may be supported by a short shaft 81 shorter than the support shaft 77, and the axial end may be abutted against the bumper frame 75 to regulate detachment. The bumper 55 may be fixed by thermally welding or ultrasonic welding the support shaft 77 and the shaft hole 79.

[0031] As the material of the bumper 55, for example, lightweight and high-strength ABS is used. As the material of the roller 63, for example, lightweight and smooth PTFE is used. Note that the materials of the bumper 55 and the roller 63 are not limited to these.

[0032] FIG. 8 is a perspective view of the flying body 13 schematically showing the beam irradiation range 83 of the TOF sensor 39. The propeller guard 11 can be configured to include a mesh member 85 in addition to the bumper 55. The mesh member 85 is a structural material having a mesh that covers the gaps between adjacent bumpers. In the flying body 13, since eight bumpers 55 are arranged radially, a total of eight mesh members 85 are used, one for each gap between the respective bumpers.

[0033] In the flying object 13, the above-described TOF sensor 39 is disposed between the main body 15 and the connecting ring rib 53. The TOF sensor 39 is used in a measurement method based on the TOF method. In the measurement by the TOF method, the time from when a laser beam pulsed from the TOF sensor 39 returns to the light receiving element in the TOF sensor is measured, and the distance is calculated from that time. The mesh member 85 has an opening 87 that surrounds the beam irradiation range 83 of the TOF sensor 39.

[0034] FIG. 9 is a perspective view of the mesh member 85. The opening 87 of the mesh member 85 is formed in a quadrilateral shape in which the diagonals 89 are arranged vertically. The mesh member 85 has openings of various sizes in the shape of a quadrilateral or a triangle formed in a mesh pattern around the opening 87, and the opening 87 has the largest opening area. As will be described later, this opening 87 functions to prevent the flying object 13 from coming into contact with and getting caught on a structure (such as a step or a receiving frame 97) when passing through the neck portion 93 of the manhole 91.

[0035] Note that a wire 99 (see FIG. 8) is stretched between the tip of the leg axis 45 and the first outermost ring rib 19 of the flying object 13 with a predetermined tension. The wire 99 connects the tips of the four leg axes 45 in an annular (quadrilateral) shape. Further, the wire 99 is stretched in a V shape from the tip of each leg axis 45 to both ends of one adjacent side of the first outermost ring rib 19. The wire 99 prevents a structure (such as a step or a receiving frame 97) that relatively approaches from below the flying object 13 when the flying object 13 descends from entering and getting caught between the leg axes and between the leg axis 45 and the first outermost ring rib 19. As described above, if the flying object 13 is provided with bumpers 55 that cover the upper half and a bumper 55 that covers the lower half with the same configuration turned upside down, this wire 99 becomes unnecessary. By providing the wire 99, the flying object 13 can achieve weight reduction at low cost compared to the case where it is provided with a bumper 55 that covers the lower half.

[0036] Next, the operation of the propeller guard according to the above-described Embodiment 1 will be described.

[0037] The propeller guard 11 according to Embodiment 1 is configured to surround the propeller 27 of the flying object 13. Specifically, the propeller guard 11 includes at least three or more 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 disposed vertically above the main body 15, and a bumper 55 disposed radially around the connecting ring rib 53, with the upper end 57 fixed to the connecting ring rib 53 and the lower end 59 fixed to the outermost ring rib, and the inclination angle gradually increasing from the connecting ring rib 53 toward 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 substantially vertical drive shaft.

[0038] FIG. 10 is an explanatory diagram when the flying object 13 during ascent contacts the step 95. When the flying object 13 is ascending vertically, the bumper 55 may accidentally contact a protruding object (e.g., the step 95) protruding in a direction perpendicular to the traveling direction in the flight space. When the protruding object is the step 95, the maximum protrusion length S is generally standardized at 8 cm. In this case, the flying object 13 contacts the step 95 at the bumper 55 outside the main body center 29. Since the bumper 55 slides toward the outermost ring rib with respect to the step 95, the flying object itself can proceed in the traveling direction without stopping.

[0039] Each bumper 55 has an inclination angle θ that gradually increases toward the second outermost ring rib 21. The propeller guard 11 covers the upper half of the flying object 13 and acts to suppress snagging during ascent.

[0040] The flying object 13 has a motor 25 having a propeller 27 fixed to a horizontal rib 17 extending radially from the main body 15. The quadcopter, which is the flying object 13 according to Embodiment 1, has four propellers 27. In this flying object 13, the combined lift and combined thrust act at the radial center where the four propellers 27 are arranged.

[0041] In a plan view, the closer the position of the aircraft 13 is to the body center 29, the less it is affected by the reaction force from the object that collided during ascent. On the other hand, the farther the position of the aircraft 13 is from the body center 29, the more easily it is affected by the reaction force from the object that collided during ascent. For this reason, even an object that was not caught at a position close to the body center 29 may be caught easily when it reaches a position far from the body center 29 because the effect of the combined lift acting by the lever principle becomes small. That is, it becomes easy for the aircraft to tilt in the front-rear direction (Pitch) and the lateral direction (Roll). When these Pitch and Roll occur, there is a possibility that the aircraft will be instantaneously sucked onto the wall surface and lose its flight balance due to the air blown out from below the propeller 27 and the air sucked in from above the propeller 27.

[0042] Therefore, the bumper 55 of the propeller guard 11 is formed at a position radially outward from the body center 29 with the inclination angle θ2 as large as possible (approaching 90 degrees). Even if the bumper 55 contacts an object at a position far from the body center 29 of the aircraft 13, the aircraft can easily slide and is less likely to be caught. In addition, by sliding, the reaction force received from the object is also reduced, making it less likely to lose the flight balance. For example, when the aircraft 13 inspecting inside the manhole passes through the neck 93 of the manhole 91, it can pass through without being caught even if it contacts a structure (such as a step or a receiving frame 97). As a result, it is possible to prevent the flight from stopping when the vertically moving aircraft 13 collides with an object.

[0043] Also, in the propeller guard 11, the bumper 55 is rotatably supported by a support shaft 77 orthogonal to the radial direction, projects at least a part of the rotation radius outside the bumper 55, and has a plurality of rollers 63 arranged in the inclination direction.

[0044] In this propeller guard 11, a roller 63 is attached to the bumper 55. The roller 63 is rotatable about a support shaft 77 that is orthogonal to the radial direction. In Embodiment 1, the radial direction is eight directions at equal intervals in the circumferential direction. That is, the angle sandwiched between adjacent bumpers 55 is 45°. The direction orthogonal to the radial direction is the tangential direction at the point where the bumper 55 intersects the outer diameter circle of the connecting ring rib 53 in a plan view.

[0045] At least a part of the rotation radius of the roller 63 protrudes outside the bumper 55. A plurality of rollers 63 are arranged in the inclined direction of the bumper 55. When the flying object 13 ascends, even if it contacts an object, the roller 63 rotates upon contact, making it extremely easy to slide and difficult to get caught. Also, by easily sliding, the reaction force received from the object is further reduced, making it less likely to lose the flight balance.

[0046] Also, in the propeller guard 11, the distance between adjacent rollers among the plurality of rollers 63 is larger on the upper side in the inclined direction of the bumper 55 than on the lower side in the inclined direction of the bumper 55. For example, the distance between adjacent rollers among the plurality of rollers 63 is dense on the lower side in the inclined direction of the bumper 55 and sparse on the upper side in the inclined direction of the bumper 55.

[0047] In this propeller guard 11, the rollers 63 are dense on the lower side in the inclined direction of the bumper 55 and sparse on the upper side in the inclined direction of the bumper 55. In the propeller guard 11, on the lower side in the inclined direction away from the body center 29 to the outside, the density of the rollers 63 increases, increasing the probability that an object that collides during ascent hits the roller 63. When the flying object 13 ascends, if an object hits the roller 63, compared to the case of directly hitting the bumper 55, the sliding friction can be made smaller, and it can be made less susceptible to the influence of the reaction force from the object. Also, on the upper side in the inclined direction of the bumper 55, where it is less susceptible to the influence of the reaction force from the object, by making the rollers 63 sparse, the weight of the flying object 13 can be reduced.

[0048] Further, in the propeller guard 11, the roller 63 has a larger diameter as it goes downward in the inclination direction of the bumper 55.

[0049] In this propeller guard 11, the mass of one bumper is the sum of the roller plate and the roller receiving shaft. When the ratio of the mass occupied by the roller receiving shaft is large, arranging the large-diameter rollers 63 densely can reduce the mass more than arranging the small-diameter rollers 63 densely. In the propeller guard 11, by arranging the rollers 63 with larger diameters as it goes downward in the inclination direction of the bumper 55, it is possible to reduce the weight of the aircraft 13 while making the rollers 63 dense on the lower side in the inclination direction of the bumper 55.

[0050] Further, in the propeller guard 11, the bumper 55 has convex portions 71 that protrude outward at a position lower than the outer diameter of the rollers between adjacent rollers.

[0051] In this propeller guard 11, convex portions 71 (bumps) are formed between the rollers of the bumper 55. The convex portions 71 protrude outward from the bumper 55 at a position lower than the outer diameter of the rollers. That is, an object contacts the roller 63 before the convex portion 71. The convex portions 71 are formed, for example, as convex curved surfaces that are less likely to get caught.

[0052] In the bumper 55, if there is a gap between the rollers, depending on the shape of the object, it may be pinched between the rollers and get caught. Or, when the object hits the gap between the rollers, that may become a fulcrum and the aircraft 13 may rotate significantly.

[0053] In the bumper 55, by providing the convex portions 71 in the gap between the rollers, when the object hits the convex portions 71 between the rollers, it is guided to the rollers 63. When the aircraft 13 ascends, even if the object enters between the rollers, it hits the convex portions 71 and is guided to the rollers 63. Thus, due to the same action as described above, it easily slides and is less likely to get caught. As a result, it is possible to prevent the object from being pinched between the rollers and the aircraft 13 from rotating.

[0054] In addition, a wire 99 is provided that stretches between the first outermost ring rib 19 and the tip of the leg shaft 45.

[0055] When the flying object 13 descends along the neck 93 of the manhole 91 by means of this wire 99, even if the leg shaft 45 contacts the structure, it will not get caught and can pass through.

[0056] In addition, 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 or more horizontal ribs 17 that extend radially from the main body 15 of the flying object 13, a second outermost ring rib 21 that connects the tips of the horizontal ribs 17, a connecting ring rib 53 that is disposed vertically above the main body 15, a bumper 55 that is disposed radially around the connecting ring rib 53 and has its upper end 57 fixed to the connecting ring rib 53 and its lower end 59 fixed to the outermost ring rib, and a mesh member 85 that covers the gaps between adjacent bumpers and has an opening 87 that surrounds the beam irradiation range 83 of a sensor (for example, the TOF sensor 39) disposed between the main body 15 and the connecting ring rib 53. Note that the flying object 13 includes a motor 25 that is fixed to the horizontal rib 17 and to which the propeller 27 is fixed to a substantially vertical drive shaft.

[0057] Each bumper 55 has an inclination angle θ that gradually increases toward the second outermost ring rib 21. The propeller guard 11 covers the upper half of the flying object 13 and acts to suppress snagging during ascent.

[0058] The flying object 13 has a motor 25 having a propeller 27 fixed to a horizontal rib 17 that extends radially from the main body 15. The quadcopter, which is the flying object 13 according to the first embodiment, has four propellers 27. In this flying object 13, the combined lift and the combined thrust act at the radial center where the four propellers 27 are arranged.

[0059] In a plan view, the closer the position of the flying object 13 is to the body center 29, the less it is affected by the reaction force from the object collided with during ascent. On the contrary, the farther the position of the flying object 13 is from the body center 29, the more easily it is affected by the reaction force from the object collided with during ascent. For this reason, even an object that was not caught near the body center 29 is likely to be caught when it hits a position away from the body center 29 outward, because the action of the combined lift becomes smaller due to the principle of leverage. That is, it becomes easier for the inclination in the front-rear direction (Pitch) and the inclination in the lateral direction (Roll) to occur easily. When these Pitch and Roll occur, there is a possibility that the flying object may be sucked onto the wall surface and instantaneously lose its flight balance due to the ejection of air from below the propeller 27 and the suction from above the propeller 27.

[0060] Therefore, the bumper 55 of the propeller guard 11 is formed at a position radially outward from the body center 29 with the inclination angle θ as large as possible (approaching 90 degrees). Even if the bumper 55 of the flying object 13 contacts an object at a position away from the body center 29, it is difficult to be caught because it easily slides. In addition, by sliding, the reaction force received from the object is also reduced, making it difficult to lose the flight balance. For example, when the flying object 13 for inspecting flight inside the manhole passes through the neck 93 of the manhole 91, it can pass through without being caught even if it contacts a structure (such as a step or a receiving frame 97). As a result, it is possible to prevent the flight from stopping when the flying object 13 moving in the vertical direction collides with an object.

[0061] FIG. 11 is an explanatory diagram showing the process by which the flying object 13 provided with the mesh member 85 having the opening 87 avoids being caught. In addition, the propeller guard 11 includes a mesh member 85 that covers the gap between adjacent bumpers. The mesh member 85 is formed such that the opening 87 is substantially within the viewing range of the TOF sensor 39 installed at the intermediate portion between the main body 15 and the connecting ring rib 53. That is, the mesh member 85 is formed so as not to block the irradiation beam and the reflected beam from the TOF sensor 39 by providing the opening 87.

[0062] The propeller guard 11 is provided with a mesh member 85, which makes it difficult for structures to enter the gap formed between the bumpers, suppresses snagging on the second outermost ring rib 21, and allows passage. As a result, it is possible to suppress the flight from stopping when the flying object 13 moving in the vertical direction collides with an object.

[0063] Also, in the propeller guard 11, the opening 87 is formed in a quadrilateral shape in which the diagonals 89 are arranged vertically.

[0064] FIG. 12 is a front view schematically showing the opening 87. In this propeller guard 11, the opening 87 is opened with a certain size (leaving a margin) so as not to block the irradiation beam or the reflected beam (i.e., the field of view) from the TOF sensor 39. For this reason, relatively small structures (such as the corners of the step 95) may enter the opening 87.

[0065] Therefore, the opening 87 is formed in a quadrilateral shape in which the diagonals 89 are arranged vertically. The quadrilateral is, for example, a rhombus. In the rhombus-shaped opening 87, the lower two sides 101 gradually approach and intersect toward the lower diagonal 89. For example, when the flying object 13 is ascending, assume that the corner of the step 95 enters the opening 87 of the mesh member 85 as shown in FIG. 11. Then, as the flying object 13 ascends, the lower two sides 101 relatively guide the corner of the step 95. As a result, the step 95 does not remain fitted in the opening 87 as it is, but is relatively pushed out to the outside of the opening 87 while sliding on the lower two sides 101 (actually, the flying object 13 separates from the step 95) and is discharged. As a result, the flying object 13 can escape from the step 95. The above description is for the ascending period of the flying object 13, but even when descending, if the step 95 is fitted into the opening 87 of the mesh member 85, the flying object 13 can escape from the step 95 in the same manner (the upper two sides 103).

[0066] FIG. 13 is an explanatory diagram showing the process of the flying object 13 avoiding getting caught on various structures. The propeller guard 11 including the bumper 55 and the mesh member 85 can suppress getting caught on the step portion 105 of the manhole 91, the receiving frame 97 of the manhole cover, etc. when the flying object 13 ascends, by the same sliding by the bumper 55 and pushing-out action by the opening 87 as described above. As a result, even during automatic flight by out-of-sight flight, the flying object itself is less likely to get caught on an object and can proceed in the traveling direction without stopping.

[0067] Therefore, according to the propeller guard 11 according to the first embodiment, it is possible to suppress the flight from stopping when the flying object 13 moving in the vertical direction comes into contact with an object.

[0068] As described above, the embodiments have been described with reference to the drawings, but it goes without saying that the present disclosure is not limited to such examples. It is obvious that those skilled in the art can conceive of various modification examples, correction examples, substitution examples, addition examples, deletion examples, equivalent examples within the scope described in the claims, and it is naturally understood that those also belong to the technical scope of the present disclosure. Further, within the scope not departing from the gist of the invention, the respective components in the above-described embodiments may be arbitrarily combined.

Industrial Applicability

[0069] The present disclosure is useful as a propeller guard capable of suppressing the flight from stopping when a flying object moving in the vertical direction comes into contact with an object.

Explanation of Reference Numerals

[0070] 11 Propeller guard 13 Flying object 15 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 Protrusion 77 Support shaft 83 Beam irradiation range 85 Mesh member 87 Opening 89 Diagonal θ Inclination angle

Claims

1. A propeller guard configured to surround a propeller of an aircraft, a horizontal rib extending radially from the main body of the aircraft, an outermost ring rib connecting the tips of the horizontal ribs, a connecting ring rib disposed vertically above the main body, a bumper disposed radially about 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 a gradually increasing inclination angle from the connecting ring rib toward the outermost ring rib, the bumper being rotatably supported and having a plurality of rollers protruding at least partially outside the bumper in a radial direction and disposed in an inclined direction, the outside of the bumper being on a side opposite to the side facing the main body of the aircraft, a propeller guard.

2. The distance between adjacent rollers among the plurality of rollers is greater on the upper side in the inclined direction of the bumper than on the lower side in the inclined direction of the bumper, The propeller guard according to claim 1.

3. The rollers have a larger diameter as they go toward the lower side in the inclined direction of the bumper, The propeller guard according to claim 2.

4. The bumper is formed with protrusions protruding outward at a position lower than the outer diameter of the rollers between adjacent rollers, the outside being on a side opposite to the side facing the main body of the aircraft in the bumper, The propeller guard according to claim 1.

5. A propeller guard configured to surround a propeller of an aircraft, a horizontal rib extending radially from the main body of the aircraft, an outermost ring rib connecting the tips of the horizontal ribs, a connecting ring rib disposed vertically above the main body, a bumper disposed radially about 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 a gradually increasing inclination angle from the connecting ring rib toward the outermost ring rib, further comprising a wire stretched between the outermost ring rib and the tip of the leg of the aircraft, a propeller guard.

6. A propeller guard configured to surround a propeller of an aircraft, at least three or more horizontal ribs extending radially from the main body of the aircraft, an outermost ring rib connecting the tips of the horizontal ribs, a connecting ring rib disposed vertically above the main body, A plurality of bumpers that are arranged radially around the connecting ring rib, with upper ends fixed to the connecting ring rib and lower ends fixed to the outermost ring rib; A mesh member that covers the gaps between adjacent bumpers and has an opening that surrounds the beam irradiation range of a sensor disposed between the main body and the connecting ring rib. Propeller guard.

7. The opening is formed in a quadrilateral shape with diagonals arranged vertically and horizontally. The propeller guard according to claim 6.

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