Multicopter

Abstract

To provide a multicopter that can sufficiently prevent or dissolve occurrence of a suction effect, and has a high degree-of-freedom of propeller design.SOLUTION: A multicopter 1 comprises a plurality of propellers 2, and a vent pipe 4 of which one end is located at a position lower than the propeller 2 and the other end is located at a position equal to or higher than the plurality of propellers 2. Since air below the propeller 2 is supplied above the propeller 2 via the vent pipe 4, a diameter and a position of the vent pipe 4 can be suitably adjusted without receiving restriction to a size and a position of the propeller 2 compared to a prior art that has supplied air above the propeller 2 via an open hole formed in the propeller 2, and air of an amount sufficient for preventing or dissolving suction effect between a ceiling and the propeller 2 can be supplied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multicopter equipped with a mechanism for preventing or eliminating the suction effect. [Background technology]

[0002] It has been known that when an unmanned helicopter approaches a ceiling (upper wall), a phenomenon occurs in which the thrust from the propeller increases suddenly. Hereinafter, this phenomenon will be referred to as the "suction effect." Figure 14(A) is a diagram showing the airflow near the propeller of a single-rotor unmanned helicopter when the suction effect is not occurring. Figure 14(B) is a diagram showing the airflow near the propeller of a single-rotor unmanned helicopter when the suction effect is occurring. Figure 15(A) is a diagram showing the airflow near the propeller of a multicopter when the suction effect is occurring, and Figure 15(B) is a diagram showing the airflow when Figure 15(A) is viewed from above.

[0003] When an unmanned helicopter approaches a ceiling, the ceiling becomes an obstacle (in the case of a multicopter, the main body supporting the propeller also becomes an obstacle), and air can only flow above the propeller from the outside. This narrows the airflow path above the propeller, increasing the flow rate and lowering the pressure between the ceiling and the propeller. This increases the pressure difference between the top and bottom of the propeller, increasing the propeller's thrust and creating a suction effect. When the suction effect occurs, an "adhesion force" is generated that prevents the multicopter from moving away from its position close to the ceiling. Therefore, in order to descend (move away) from its position close to the ceiling, the power to rotate the propeller must be reduced compared to when the suction effect is not occurring (normal descent), which can cause unstable control of the multicopter's attitude and other aspects immediately after descent.

[0004] To prevent the above-described suction effect, the aircraft (multicopter) of Patent Document 1 has a rotor (propeller) equipped with a hub attached to the rotation shaft and an annular body that surrounds and connects to the hub and has blades attached to it, with a pressure recovery hole formed as a through-hole between the hub and the annular body. This pressure recovery hole supplies air between the ceiling and the rotor (propeller) (suction side), reducing the pressure difference between the space between the ceiling and the propeller and the underside of the propeller. This prevents a sudden increase in thrust. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-104576 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the aircraft (multicopter) of Patent Document 1 uses pressure recovery holes, which are through-holes formed in the rotor (propeller), to reduce the pressure difference between the space between the ceiling and the propeller and the space below the propeller, thereby preventing the occurrence of the suction effect. However, with a configuration that simply forms through-holes, the size and position of the through-holes are restricted by the size and position of the propeller, and the amount and position of air supplied between the ceiling and the propeller may be insufficient to prevent or eliminate the suction effect. In addition, forming through-holes in the propeller reduces the degree of freedom in designing the propeller's shape.

[0007] Therefore, an object of the present invention is to provide a multicopter that can sufficiently prevent or eliminate the occurrence of the suction effect and has a high degree of freedom in propeller design. [Means for solving the problem]

[0008] (1) In order to solve the above problem, the multicopter of the present invention is characterized by having a plurality of propellers, one end of which is positioned lower than the plurality of propellers, and the other end of which is positioned higher than the plurality of propellers.

[0009] According to the configuration described in (1) above, air below the propeller flows into the vent pipe from one end, passes through the vent pipe, and is supplied from the other end to above the propeller. This reduces the pressure difference between the space between the ceiling and the propeller and the space below the propeller, even when the multicopter approaches the ceiling and a suction effect occurs, causing a sudden increase in propeller thrust. This suppresses a sudden increase in thrust. Here, according to the configuration described in (1) above, since air below the propeller is supplied above the propeller via the vent pipe, the diameter of the vent pipe can be adjusted appropriately without being limited by the size of the propeller, compared to conventional technology in which air is supplied above the propeller through a through-hole formed in the propeller. This makes it possible to supply a sufficient amount of air to prevent or eliminate the suction effect between the ceiling and the propeller. Furthermore, by using a vent pipe, one end of the vent pipe can be positioned below the propeller in a suitable position to take in air, and the other end of the vent pipe can be positioned above the propeller in a suitable position to send air therethrough, thereby further increasing the amount of air supplied above the propeller. Also, the degree of freedom in designing the shape of the propeller is increased.

[0010] (2) The multicopter may further include a main body to which the plurality of propellers are attached, and an inspection device attached to the top of the main body for inspecting an object to be inspected.

[0011] According to the configuration (2) above, by moving the multicopter close to the object to be inspected (such as a ceiling) above the main body, it is possible to inspect the object, such as a structure, using the inspection device attached to the top of the main body. Here, by supplying air below the propeller to above the propeller through the ventilation pipe, it is possible to prevent or eliminate the problem of the multicopter being unable to move away from the close position to the object to be inspected due to a suction effect when the inspection is completed.

[0012] (3) The multicopter may further include a main body around which the plurality of propellers are attached, and the other end of the ventilation pipe may be positioned between two adjacent propellers or between the plurality of propellers.

[0013] According to the configuration (3) above, air below the propellers can be supplied to a position between two adjacent propellers or a position between multiple propellers via the other end of the ventilation pipe. This allows air below the propellers to be supplied above two or multiple propellers, effectively preventing or eliminating the suction effect. Furthermore, when the other end of the ventilation pipe is located between multiple propellers, air below the propellers can be supplied above the main body, where pressure is most likely to drop in the area above the propellers, very effectively preventing or eliminating the suction effect between the ceiling and the propeller. Note that when the other end of the ventilation pipe is located between two adjacent propellers, the same effect can be achieved even if the other end of the ventilation pipe is located closer to the main body.

[0014] (4) In the multicopter, the vent at the one end of the ventilation pipe may be positioned below at least one propeller of the plurality of propellers and facing the propeller.

[0015] According to the above configuration (4), it is possible to increase the amount of air below the propeller that flows into the vent by the rotation of the propeller.

[0016] (5) In the multicopter of (4) above, the ventilation pipe may have a first section extending in the vertical direction and a second section bent upward from the lower end of the first section, and the ventilation port formed at the end of the second section may be formed to face the propeller, and a through hole may be formed in the second section, and an opening / closing mechanism may be provided that can freely open and close the through hole.

[0017] According to the configuration (5) above, when the through-hole formed in the bent portion is closed by the opening / closing mechanism, air below the propeller can be supplied above the propeller through the vent pipe. When the through-hole is open, air in the vent pipe is released to the outside of the vent pipe through the through-hole, restricting the supply of air below the propeller above the propeller. In this way, opening and closing the through-hole allows for switching between eliminating the suction effect and not eliminating it. For example, when performing an inspection with inspection equipment mounted on a multicopter, it may be preferable to have the suction effect occur during the inspection because it allows the equipment to maintain a position close to the object being inspected (such as the ceiling). In such cases, the through-hole can be opened and then closed when the equipment leaves the object being inspected after the inspection. In this way, opening and closing the through-hole restricts the supply of air below the propeller above the propeller. This increases the overall propeller thrust and results in higher energy efficiency compared to conventional configurations in which a large amount of air continues to be supplied between the ceiling and the propeller through pressure recovery holes formed in the rotor blades (propellers).

[0018] (6) In the multicopter of (5) above, an opening / closing valve that can open and close the ventilation pipe may be provided at a position closer to the other end than the position where the through hole is formed in the ventilation pipe.

[0019] According to the configuration (6) above, even if the through-hole is opened by the opening / closing mechanism, air may be supplied above the propeller through the vent pipe, but according to the configuration (6) above, by closing the vent pipe with the opening / closing valve, it is possible to prevent air from being supplied above the propeller through the vent pipe. In this way, since the vent pipe can be closed appropriately with the opening / closing valve, it is possible to further increase the overall thrust of the propeller compared to the conventional configuration in which air is continuously supplied between the ceiling and the propeller through the through-hole (pressure recovery hole) formed in the rotor (propeller).

[0020] (7) In the multicopter, an electric fan may be attached to the one end of the ventilation pipe.

[0021] According to the configuration (7) above, the rotation of the electric fan increases the amount of air below the propeller that flows into one end of the vent. Furthermore, because the propeller and the electric fan can be driven separately, it is easy to adjust the amount of air supplied above the propeller. For example, when carrying out an inspection using inspection equipment mounted on a multicopter, it may be preferable to have a suction effect during the inspection. In such cases, the electric fan can be stopped or slowed down, and then operated when the aircraft leaves the inspection object after the inspection. In this way, stopping or slowing down the electric fan limits the supply of air below the propeller to above the propeller. This increases the overall propeller thrust, resulting in higher energy efficiency, compared to conventional configurations in which a large amount of air continues to be supplied between the ceiling and the propeller through pressure recovery holes formed in the rotor blades (propellers).

[0022] (8) In the multicopter of (7) above, an opening / closing valve that can open and close the ventilation pipe may be provided at a position on the other end side of the ventilation pipe relative to the mounting position of the electric fan.

[0023] According to the configuration (8) above, even when the electric fan is stopped, air may be supplied above the propeller through the vent pipe, but according to the configuration (8) above, by closing the vent pipe with the on-off valve, it is possible to prevent air from being supplied above the propeller through the vent pipe. In this way, since the vent pipe can be closed with the on-off valve, it is possible to further increase the overall thrust of the propeller compared to the conventional configuration in which air continues to be supplied between the ceiling and the propeller through the through-holes (pressure recovery holes) formed in the rotor (propeller).

[0024] (9) In the multicopter of (7) above, the electric fan may be capable of being driven by switching its rotation direction between a forward direction and a reverse direction.

[0025] According to the configuration of (9) above, the electric fan can be not only stopped but also rotated in reverse, which further prevents the supply of air when air is not being supplied above the propeller. In this way, the supply of air above the propeller through the vent pipe can be further restricted by the reverse rotation of the electric fan, which makes it possible to further increase the overall propeller thrust compared to the conventional configuration in which air continues to be supplied between the ceiling and the propeller through the through-holes (pressure recovery holes) formed in the rotor (propeller).

[0026] (10) In the above multicopter, the number of the ventilation pipes provided may be the same as the number of the plurality of propellers, and the other end of each of the ventilation pipes may be positioned at different positions between the two adjacent propellers, or at positions between the plurality of propellers.

[0027] According to the above configuration (10), the same number of vent pipes as the number of propellers are provided, and the other end of each vent pipe is disposed at a different position between two adjacent propellers or at a position between the propellers. By passing the other ends of the same number of vent pipes as the number of propellers, it is possible to easily supply air below the propellers over the propellers, thereby effectively eliminating the suction effect. [Effects of the Invention]

[0028] According to the above configuration, it is possible to sufficiently prevent or eliminate the occurrence of the suction effect, and to provide a multicopter with a high degree of freedom in propeller design. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a front view of a multicopter according to a first embodiment. [Figure 2] 1, and FIG. 3B is an explanatory diagram of the airflow near the propeller 2 of the multicopter 1 according to the first embodiment. [Figure 3] 2A is a front view of the multicopter shown in FIG. 1 when the opening / closing mechanism is open, and FIG. 2B is a front view of the multicopter shown in FIG. 1 during inspection. [Figure 4] (A) is a diagram showing the air flow when the opening / closing mechanism is closed in the multicopter shown in Figure 1, and (B) is a diagram showing the air flow when the opening / closing mechanism is open in the multicopter shown in Figure 1. [Figure 5] FIG. 10A is a front view of the multicopter according to the second embodiment when the opening / closing valve is closed, and FIG. 10B is a front view of the multicopter according to the second embodiment when the opening / closing valve is open. [Figure 6] FIG. 10A is a diagram showing the air flow when the opening / closing valve is open in the multicopter according to the second embodiment, and FIG. 10B is a diagram showing the air flow when the opening / closing valve is closed in the multicopter according to the second embodiment. [Figure 7] FIG. 10(A) is a front view of a multicopter according to a third embodiment, and FIG. 10(B) is a plan view of the multicopter shown in FIG. [Figure 8] FIG. 10A is a front view of the multicopter according to the third embodiment during inspection, and FIG. 10B is a diagram showing the air flow when the electric fan is rotated in the forward direction in the multicopter according to the third embodiment. [Figure 9] FIG. 10A is a diagram showing the air flow when the electric fan is not rotating in the multicopter according to the third embodiment, and FIG. 10B is a diagram showing the air flow when the electric fan is rotating in the reverse direction. [Figure 10] FIG. 10A is a front view of the multicopter according to the fourth embodiment when the opening / closing valve is closed, and FIG. 10B is a front view of the multicopter according to the fourth embodiment when the opening / closing valve is open. [Figure 11] FIG. 10A is a diagram showing the air flow when the opening / closing valve is open in the multicopter according to the fourth embodiment, and FIG. 10B is a diagram showing the air flow when the opening / closing valve is closed in the multicopter according to the fourth embodiment. [Figure 12] 1A is a front view of a multicopter according to a modified example of the first embodiment, and FIG. 1B is a front view of a multicopter according to a modified example of the third embodiment. [Figure 13] FIG. 2 is a plan view of a multicopter according to a modified example of the first embodiment. [Figure 14] (A) is a diagram showing the air flow near the propeller of a single-rotor unmanned helicopter when the suction effect is not occurring, and (B) is a diagram showing the air flow near the propeller of a single-rotor unmanned helicopter when the suction effect is occurring. [Figure 15] (A) is a diagram showing the air flow near the propeller of a multicopter when the suction effect is occurring, and (B) is a diagram showing the air flow when (A) is viewed from above. DETAILED DESCRIPTION OF THE INVENTION

[0030] [First embodiment] A multicopter 1 according to a first embodiment to which the present invention is applied will be described below with reference to FIGS. 1 to 4. FIG. 1 is a front view of the multicopter 1 according to the first embodiment. FIG. 2(A) is a plan view of the multicopter 1 shown in FIG. 1. FIG. 2(B) is an explanatory diagram of the air flow near the propeller 2 of the multicopter 1 according to the first embodiment. FIG. 3(A) is a front view of the multicopter 1 shown in FIG. 1 when the opening / closing mechanism is open. FIG. 3(B) is a front view of the multicopter 1 shown in FIG. 1 when the opening / closing mechanism is closed. FIG. 4(A) is a diagram showing the air flow when the opening / closing mechanism is closed in the multicopter 1 shown in FIG. 1. FIG. 4(B) is a diagram showing the air flow when the opening / closing mechanism is open in the multicopter 1 shown in FIG. 1. In addition, the front side of Figure 1 will be referred to as the "front" of multicopter 1, the back side will be referred to as the "rear" of multicopter 1, the right side will be referred to as the "right side" of multicopter 1, the left side will be referred to as the "left side" of multicopter 1, the top side will be referred to as the "above" of multicopter 1, and the bottom side will be referred to as the "below" of multicopter 1.

[0031] As shown in FIGS. 1 and 2A, the multicopter 1 includes multiple propellers 2, a main body 3 around which the multiple propellers 2 are attached, and an air duct 4, one end of which is positioned lower than the multiple propellers 2 and the other end of which is positioned higher than the multiple propellers 2. The multicopter 1 according to the first embodiment is characterized by the inclusion of this air duct 4. This air duct 4 enables air to be supplied above the propellers 2 even when the multicopter 1 approaches the ceiling, causing the ceiling to obstruct and narrow the airflow path above the propellers. This prevents a large pressure difference between the upper and lower sides of the propellers, thereby preventing or eliminating the suction effect. The configuration of the multicopter 1 according to the first embodiment will be described in more detail below.

[0032] [First embodiment: configuration of main body and propeller] In the multicopter 1 according to the first embodiment, the main body (main body frame) 3 is substantially rectangular parallelepiped-shaped and includes four arms 11 extending radially from the four corners in a plan view, with a propeller 2 attached to the tip of each arm 11. When distinguishing between the four propellers 2, the right front propeller 2 will be referred to as the first propeller 21, the left front propeller 2 as the second propeller 22, the right rear propeller 2 as the third propeller 23, and the left rear propeller 2 as the fourth propeller 24. Although four propellers 2 are provided, the number of propellers 2 is not limited to four and may be more than four, or may be less than four, or may be two or more.

[0033] Multicopter 1 is equipped with a main body 3, which is mounted with a drive device (not shown) such as a motor for driving multiple propellers 2, a control device (not shown) for this drive device, a battery (not shown), etc. Also, a landing gear (skid) 12 is provided below main body 3. Furthermore, as shown in FIG. 3(B), multicopter 1 is capable of attaching an inspection device 5 to the top of main body 3, and by providing inspection device 5, it is possible to inspect an object to be inspected (such as a ceiling) using inspection device 5.

[0034] [First embodiment: configuration of ventilation pipe] 1 and 2(A), the vent pipe 4 is a tubular member fixed to each of the four side surfaces of the main body 3. The vent pipe 4 includes a first section 41 extending upright in the height direction and a second section 42 bent upward from the lower end of the first section 41. In the first embodiment, the two second sections 42 are formed so that the lower end of the first section 41 branches into two sections in opposite directions. As a result, the vent pipe 4 has a shape resembling two J-shaped sections connected together in a side, front, or rear view. The multicopter 1 is provided with four vent pipes 4, the same number as the number of propellers 2, but a different number may also be provided. Note that the attachment positions of the vent pipes 4 are not limited to the four side surfaces of the main body 3 and may be disposed inside the main body 3, for example.

[0035] The upper end of each vent pipe 4 (the "other end" of the present invention) is located at a different position between two adjacent propellers 2, and air below the propellers can be supplied to the areas above the two propellers 2 through the first vent port 421 at the upper end, as shown in FIG. 2(B). The second vent port 422 at the lower end of the vent pipe 4 (the "one end" of the present invention), i.e., the second vent port 422 formed in the second section end portion 42, is formed to face the propeller 4 ("at least one propeller of the multiple propellers" of the present invention). This allows the propeller 2 to function as a fan that sends air into the second vent port 422, allowing sufficient air to be sent into the vent pipe 4 through the second vent port 422. The rotation of the propeller 2 allows an increased amount of air below the propeller 2 to flow into the second vent port 422.

[0036] The positional relationship between the second vent port 422 and the first to fourth propellers 21, 22, 23, and 24 will be described in more detail below. In the vent pipe 4 attached to the front side of the main body 2, one second portion 42 bends upward and to the right from the lower end of the first portion 41, and the other second portion 42 bends upward and to the left. The second vent port 422 in the second portion 42 bent upward and to the right faces the first propeller 21. The second vent port 422 in the second portion 42 bent upward and to the left faces the second propeller 22. In the vent pipe 4 attached to the rear side of the main body 2, one second portion 42 bends upward and to the right from the lower end of the first portion 41, and the other second portion 42 bends upward and to the left. The second vent port 422 in the second portion 42 bent upward and to the right faces the third propeller 23. Additionally, the second vent 422 of the second portion 42 bent toward the upper left is directed toward the fourth propeller 24.

[0037] In the vent pipe 4 attached to the right side of the main body 2, one second portion 42 bends rearward and upward from the lower end of the first portion 41, and the other second portion 42 bends frontward and upward. The second vent port 422 in the second portion 42 bent rearward and upward faces the third propeller 23. The second vent port 422 in the second portion 42 bent frontward and upward faces the first propeller 21. In the vent pipe 4 attached to the left side of the main body 2, one second portion 42 bends rearward and upward from the lower end of the first portion 41, and the other second portion 42 bends frontward and upward. The second vent port 422 in the second portion 42 bent rearward and upward faces the fourth propeller 24. The second vent port 422 in the second portion 42 bent frontward and upward faces the second propeller 22.

[0038] 3(A), in the multicopter 1 according to the first embodiment, a through-hole 423 is formed in the second portion 42 of the ventilation pipe 4, and an opening / closing mechanism 424 is provided that can open and close this through-hole 423. More specifically, the second portion 42 is composed of a portion (substantially horizontal portion) that extends substantially horizontally from the first portion 41, and a portion (substantially vertical portion) that extends substantially vertically from the end of this substantially vertical portion, and the through-hole 423 is formed on the substantially horizontal portion below the substantially vertical portion. This allows air that flows in from a second ventilation port 422 at the upper end of the substantially vertical portion to be discharged to the outside through the through-hole 423 without flowing toward the first ventilation port 421 from the position where the through-hole 423 is formed.

[0039] The opening / closing mechanism 424 is a plate-like body with one edge rotatably supported, and is rotatably driven by a motor or the like to assume a closed position (when closed) that covers the through-hole 423 and an open position (when open) that exposes the through-hole 423. When the opening / closing mechanism 424 is in the closed position, as shown in FIG. 4(A), air below the propeller 2 can be sufficiently supplied to above the propeller 2 through the vent pipe 4. When the opening / closing mechanism 424 is in the open position, as shown in FIG. 4(B), air inside the vent pipe 2 (air that flows in through the second vent port 422 and passes through the approximately vertical portion) is released to the outside of the vent pipe 4 through the through-hole 423, thereby restricting the supply of air below the propeller 2 to above the propeller 2. In this way, the suction effect can be eliminated or not by opening or closing the through-hole 423 using the opening / closing mechanism 424.

[0040] The rotational drive of the opening / closing mechanism 424 is controlled by a control device (not shown). This control may be performed based on instructions from an operator or may be automatic. An example of the rotational drive control of the opening / closing mechanism 424 will be described. When the multicopter 1 inspects a ceiling or the like using the inspection device 5, it may be preferable to have a suction effect during the inspection, since this allows the multicopter 1 to maintain a position close to the ceiling or the like. In such a case, the opening / closing mechanism 424 is controlled to be in an open position, opening the through-hole 423, and preventing sufficient air from being supplied below the propeller 2 to the area above the propeller 2, as shown in FIG. 4(A). Furthermore, when the multicopter leaves the ceiling or the like after the inspection, it is preferable that the suction effect not be generated. Therefore, the opening / closing mechanism 424 is controlled to be in a closed position, closing the through-hole 423, and preventing sufficient air from being supplied below the propeller 2 to the area above the propeller 2, as shown in FIG. 4(A). In the first embodiment, since it is possible to restrict the supply of air below the propeller 2 to above the propeller 2 by opening and closing the through-hole 423, the overall thrust of the propeller 2 increases, resulting in higher energy efficiency, compared to a configuration in which a large amount of air continues to be supplied between the ceiling and the propeller from pressure recovery holes formed in the rotor (propeller) as in conventional technology. Note that the through-hole 423 and the opening and closing mechanism 424 do not necessarily have to be formed.

[0041] In the multicopter 1 according to the first embodiment described above, air below the propeller 2 flows into the vent pipe 4 from one end, passes through the vent pipe 4, and is supplied from the other end of the vent pipe 4 to above the propeller. This reduces the pressure difference between the space between the ceiling and the propeller 2 and the space below the propeller 2, even when the multicopter 1 approaches the ceiling and a suction effect occurs, causing a sudden increase in propeller thrust. This reduces the sudden increase in thrust. In the multicopter 1 according to the first embodiment, air below the propeller 2 is supplied above the propeller 2 via the vent pipe 4. This allows the diameter of the vent pipe 4 to be adjusted appropriately without being limited by the size of the propeller 2, as compared to conventional technology in which air is supplied above the propeller 2 through a through-hole formed in the propeller 2. This makes it possible to supply a sufficient amount of air to prevent or eliminate the suction effect between the ceiling and the propeller 2. Furthermore, by employing the vent pipe 4, one end of the vent pipe 4 can be positioned below the propeller 2 in a suitable position for taking in air, and the other end of the vent pipe 4 can be positioned above the propeller 2 in a suitable position for sending air thereto, thereby enabling a sufficient amount of air to be supplied above the propeller 2. In addition, the degree of freedom in designing the shape of the propeller 2 is increased.

[0042] (Second embodiment) A multicopter 1A according to a second embodiment of the present invention will be described below with reference to FIGS. 5 and 6. FIG. 5(A) is a front view of the multicopter 1A according to the second embodiment when the on-off valve is closed, and FIG. 5(B) is a front view of the multicopter 1A according to the second embodiment when the on-off valve is open. FIG. 6(A) is a diagram showing the air flow when the on-off valve is open in the multicopter 1A according to the second embodiment, and FIG. 6(B) is a diagram showing the air flow when the on-off valve is closed in the multicopter 1A shown in FIG. 1. In FIGS. 5 and 6, components in the multicopter 1A according to the second embodiment that are similar to those in the multicopter 1 according to the first embodiment are designated by the same numerals. Note that components that correspond to components in the multicopter 1 according to the first embodiment but have a different structure are designated by the same numerals with the suffix "A" added.

[0043] The multicopter 1A according to the second embodiment will be described only in terms of differences from the multicopter 1 according to the first embodiment. The multicopter 1A has an opening / closing valve 425 that can open and close the vent pipe 4A, located at a position higher (the other end) than the position where the through-hole 423 of the vent pipe 4A is formed. More specifically, as shown in FIGS. 5 and 6, the opening / closing valve 425 is attached to the vent hole 421 of the vent pipe 4A. As shown in FIG. 5(A), the opening / closing valve 425 includes two plate-like members 4251, which are arranged side by side at the vent hole 421. The shape of these plate-like members 4251 when aligned side by side is circular in a plan view, and is generally the same as the shape of the vent hole 421. However, the shape does not necessarily have to be circular or generally the same as the shape of the vent hole 421, and may be any shape that can close the vent hole 421. Plate-like member 4251 has a semicircular shape in a plan view, but the center of the arc portion is rotatably fixed to the edge of vent hole 421, so that plate-like member 4251 is rotatably attached to vent hole 421. In the second embodiment, open / close valve 425 is attached to vent hole 421 of vent pipe 4A, but it may be provided in a different position as long as it is located on the upper end side (other end side) of the position where through-hole 423 of vent pipe 4A is formed.

[0044] The plate-shaped members 4251 can rotate around the center of their arc portions as a rotation axis from the closed position shown in FIG. 5(B) and tilt inward toward the vent port 421 to the open position shown in FIG. 5(A). When the two plate-shaped members 4251 are in the closed position (when the on-off valve 425 is closed), the vent port 421 is blocked by the plate-shaped members 4251, and air from the vent port 421 is not supplied above the propeller 2, as shown in FIG. 6(B). When the two plate-shaped members 4251 are in the open position (when the on-off valve 425 is open), the vent port 421 is open, and air from the vent port 421 is supplied above the propeller 2, as shown in FIG. 6(A). Note that, although the plate-shaped members 4251 are tilted inward toward the vent port 421 in the open position, they may also be tilted outward toward the vent port 421. Furthermore, the configuration of the on-off valve 425 is not limited to a configuration including two plate-like members 4251, and may be any configuration that can open and close the ventilation opening 421. The opening and closing of the on-off valve 425, i.e., the control of the rotation of the two plate-like members 4251, may be performed manually by an operator using a remote controller or the like, or may be automatically controlled.

[0045] In cases where it is desirable to have a suction effect, such as when inspecting a ceiling wall with inspection device 5, through-hole 423 is opened by opening / closing mechanism 424 to prevent air from being supplied above propeller 2, and by further closing vent pipe 4A with opening / closing valve 425, it is possible to further prevent air from being supplied above the propeller through vent pipe 4A. In this way, because vent pipe A can be closed appropriately with opening / closing valve 425, the overall thrust of propeller 2 increases, resulting in higher energy efficiency, compared to a conventional configuration in which air is continuously supplied between the ceiling and the propeller from through-holes (pressure recovery holes) formed in the rotor (propeller).

[0046] (Third embodiment) A multicopter 1B according to a third embodiment of the present invention will be described below with reference to FIGS. 7 and 8. FIG. 7(A) is a front view of the multicopter 1B according to the third embodiment, and FIG. 7(B) is a plan view of the multicopter 1B shown in FIG. 7(A). FIG. 8(A) is a front view of the multicopter 1B according to the third embodiment during inspection, and FIG. 8(B) is a diagram showing the airflow when the electric fan is rotated in the forward direction in the multicopter 1B according to the third embodiment. FIG. 9(A) is a diagram showing the airflow when the electric fan is not rotated in the multicopter 1B according to the third embodiment, and FIG. 9(B) is a diagram showing the airflow when the electric fan is rotated in the reverse direction. In FIGS. 7 to 9, the same components in the multicopter 1B according to the third embodiment as those in the multicopter 1 according to the first embodiment are designated by the same reference numerals. Note that components that correspond to those of the multicopter 1 according to the first embodiment but have a different structure are designated by the same numbers with the suffix "B" added.

[0047] The multicopter 1B according to the third embodiment will be described focusing only on the differences from the multicopter 1 according to the first embodiment. In the multicopter 1B according to the third embodiment, an electric fan 6 is attached to one end of a vent pipe 4B. More specifically, in the third embodiment, the vent pipe 4B is a tubular member extending substantially vertically, different in shape from the vent pipe 4 according to the first embodiment, and is provided with a first vent port 421B on the upper side and a second vent port 422B on the lower side. An electric fan 6 is fixed inside the lower end of the vent pipe 4B. The electric fan 6 is integrally provided with a motor (not shown) and is driven to rotate by the motor (not shown). The rotation of the electric fan 6 may be controlled by an operator using a remote controller or the like, or may be automatically controlled. Although the electric fan 6 is attached inside the lower end of the vent pipe 4B according to the third embodiment, it may also be attached to the outside of the lower end of the vent pipe 4B via another member or the like.

[0048] As shown in FIG. 8(A), when the multicopter 1B is inspecting a ceiling using the inspection device 5, it is preferable for the suction effect to occur, so the electric fan 6 may be controlled to stop or slow down its rotation. In this case, as shown in FIG. 9(A), the amount of air supplied above the propeller 2 is reduced. On the other hand, when the multicopter 1B finishes the inspection and moves away from the vicinity of the ceiling, the electric fan 6 is rotated normally. This increases the amount of air supplied above the propeller 2, eliminating the suction effect.

[0049] 9(B), in a modified example of the third embodiment, the electric fan 6 in the multicopter 1B may be capable of switching its rotation direction between forward and reverse. When inspecting a ceiling wall with the inspection device 5, the electric fan 6 is rotated in the reverse direction, so that air from above the propeller 2 is sucked out below the propeller 2 through the air duct 4B, creating a suction effect that makes it easier to keep the multicopter 1B near the ceiling.

[0050] As described above, the configuration of the multicopter 1B according to the third embodiment makes it possible to increase the amount of air below the propeller 2 flowing into one end of the lower vent 422B of the vent pipe 4B by rotating the electric fan 6, and sufficient air can be supplied above the propeller 2 via the upper vent 421B of the vent pipe 4B. Furthermore, because the propeller 2 and the electric fan 6 can be driven separately, it has the advantage of being easier to adjust the amount of air supplied above the propeller 2 than the multicopters 1 and 1A according to the first and second embodiments. Another advantage is that the structure of the vent pipe 4B can be simplified compared to the multicopters 1 and 1A according to the first and second embodiments.

[0051] (Fourth embodiment) A multicopter 1C according to a fourth embodiment of the present invention will be described below with reference to FIGS. 10 and 11. FIG. 10(A) is a front view of the multicopter 1C according to the fourth embodiment when the opening / closing valve is closed, and FIG. 10(B) is a front view of the multicopter 1C according to the fourth embodiment when the opening / closing valve is open. FIG. 11(A) is a diagram showing the air flow when the opening / closing valve is open in the multicopter 1C according to the fourth embodiment, and FIG. 11(B) is a diagram showing the air flow when the opening / closing valve is closed in the multicopter 1C according to the fourth embodiment. In FIGS. 10 and 11, components in the multicopter 1C according to the fourth embodiment that are the same as those in the multicopter 1B according to the third embodiment are designated by the same reference numerals.

[0052] The multicopter 1C according to the fourth embodiment will be described only in terms of the differences from the multicopter 1B according to the third embodiment. The multicopter 1C differs from the multicopter 1B according to the third embodiment only in the structure of the vent pipe 4C. The vent pipe 4C differs from the vent pipe 4B only in the following respect: an opening / closing valve 425 that can open and close the vent pipe 4C is provided at a position on the upper end side (the "other end" according to the present invention) of the vent pipe 4C above the mounting position of the electric fan 6. The configuration of the opening / closing valve 425, the method of mounting it to the vent pipe 4C, the mounting position, and the rotation control method are the same as those of the multicopter 1A according to the second embodiment.

[0053] Even when the electric fan 6 is stopped, air may be supplied above the propeller through the vent pipe 4C, but with the configuration of the multicopter 1C according to the fourth embodiment, the vent pipe 4C can be closed with the on-off valve 425, thereby preventing air from being supplied above the propeller 2 through the vent pipe 4C. Because the vent pipe 4C can be closed with the on-off valve 425 in this way, the overall thrust of the propeller 2 increases, resulting in higher energy efficiency, compared to a configuration in which air continues to be supplied between the ceiling and the propeller through through-holes (pressure recovery holes) formed in the rotor (propeller), as in the prior art.

[0054] The first and second embodiments described above are examples of embodiments to which the present invention is applied, and the configuration can be changed as appropriate. For example, the material, arrangement, number, and type of each component can be changed as appropriate. An example of a modified example in which the configuration of the first and second embodiments is changed will be described below.

[0055] (Variation) Modifications of the first and second embodiments will be described below.

[0056] (1) In the multicopters 1, 1A, 1B, and 1C according to the first to fourth embodiments, the number of ventilation pipes 4, 4A, 4B, and 4C provided is the same as the number of the propellers 2, and the upper end (other end) of each ventilation pipe 4, 4A, 4B, and 4C is disposed at a different position between two adjacent propellers 2. However, the number of ventilation pipes does not necessarily have to be the same as the number of the propellers 2. FIG. 12(A) is a front view showing a multicopter 1D, which is a modified example of the multicopter 1 according to the first embodiment, and FIG. 12(B) is a front view showing a multicopter 1E, which is a modified example of the multicopter 1B according to the third embodiment. The multicopters 1D and 1E each have eight ventilation pipes 4D and 4E, two of which are fixed to each of the four side surfaces of the main body 3. The vent pipe 4D also includes a first section 41D and a second section 42D bent upward from the lower end of the first section 41D. A first vent port 421D is provided at the upper end of the first section 42D, and a second vent port 422D is provided at the end of the second section 42D opposite the first section 42D. Unlike the vent pipe 4 in the first embodiment, the vent pipe 4D does not fork in two opposite directions from the lower end of the first section 41D, but instead has only a single second section 42D. That is, while the vent pipe 4 is shaped like two Js connected together with their left and right reversed, the vent pipe 4D is J-shaped. The modified version of the first embodiment shown in FIG. 12(A) also differs in that multiple (three) opening / closing mechanisms 424D are provided. The configuration of the vent pipe 4E is similar to that of the vent pipe 4B, except for its smaller diameter. An on-off valve 425 may also be provided in the ventilation pipes 4D and 4E.

[0057] (2) In the multicopters 1, 1A, 1B, and 1C according to the first to fourth embodiments, the other end (upper end) of the ventilation pipes 4, 4A, 4B, and 4C is disposed between two adjacent propellers 2 among the plurality of propellers 2, but this configuration is not limited thereto. For example, the upper end (other end) of the ventilation pipes 4A, 4B, and 4C may be disposed between the plurality of propellers 2 (e.g., approximately at the center) in a plan view. FIG. 13 is a front view of a multicopter 1F, which is a modified example of the multicopter 1 according to the first embodiment. In the multicopters 1F, the upper portion of the first portion 41 of the ventilation pipe 4F is bent inward midway and then further bent upward, so that the ventilation opening 421F is positioned between the plurality of propellers 2 (e.g., approximately at the center). [Explanation of symbols]

[0058] 1, 1A, 1B, 1C, 1D, 1E, 1F Multicopter 2 propellers 21 First Propeller 22 Second Propeller 23 Third Propeller 24 Fourth Propeller 3 Main body 4, 4A, 4B, 4C, 4D, 4E, 4F ventilation pipe 41, 41D 1st part 42, 42D 2nd part 421, 421B, 421D, 421F First Vent (Vent) 423 Through Hole 424 Opening and Closing Mechanism 425 Opening and closing valve 5. Inspection equipment 6 Electric Fan

Claims

1. A multicopter with multiple propellers, A multicopter comprising an air duct, one end of which is positioned lower than the plurality of propellers and the other end of which is positioned higher than the plurality of propellers.

2. Further comprising: a main body to which the plurality of propellers are attached; and an inspection device attached to an upper portion of the main body for inspecting an object to be inspected. The multicopter according to claim 1 .

3. a main body around which the plurality of propellers are mounted; The other end of the ventilation pipe is disposed between two adjacent propellers or between the plurality of propellers. The multicopter according to claim 1 .

4. The vent port at the one end of the vent pipe is arranged below at least one propeller of the plurality of propellers and facing the propeller. The multicopter according to claim 1 .

5. the vent pipe has a first section extending in a height direction and a second section bent upward from a lower end of the first section, and a vent hole formed at an end of the second section is formed so as to face the propeller, a through hole is formed in the second portion, and an opening / closing mechanism is provided to open and close the through hole; The multicopter according to claim 4 .

6. an opening / closing valve for freely opening and closing the ventilation pipe is provided at a position on the other end side of the ventilation pipe relative to the position where the through hole is formed; The multicopter according to claim 5 .

7. An electric fan is attached to the one end of the ventilation pipe. The multicopter according to claim 1 .

8. an opening / closing valve for freely opening and closing the ventilation pipe is provided at a position on the other end side of the ventilation pipe relative to the mounting position of the electric fan; The multicopter according to claim 7 .

9. The electric fan is capable of being driven by switching its rotation direction between forward and reverse rotation. The multicopter according to claim 7 .

10. The number of the ventilation pipes provided is the same as the number of the plurality of propellers, and the other end side of each of the ventilation pipes is disposed at different positions between the two adjacent propellers or at positions between the plurality of propellers. The multicopter according to claim 3 .

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