A multicopter includes an airframe, multiple propellers mounted rotatably on the airframe, and a propeller guard installed to surround at least a part of the propellers. The propeller guard is deformed or displaced to contact the propellers and stops rotation of the propellers when the multicopter collides with a collision object. The propeller guard includes a fixed frame and a movable frame positioned near the rotation plane of each propeller. The movable frame is located on one side of the corresponding propeller opposite the airframe, and has a pivot point as a rotation center, supported by the fixed frame, and an engagement portion in which a part of the movable frame is detachably engaged with the fixed frame. When an external force is applied to the movable frame, the engagement portion is disengaged from the fixed frame and the movable frame turns toward the propeller about the pivot point.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority to Japanese Patent Application No. 2023-031789 filed on Mar. 2, 2023, the entire contents of which are incorporated herein by reference.

BACKGROUND

Technical Field

The technology disclosed in this specification relates to a multicopter which has a plurality of propellers and motors that rotate and drive the respective propellers, and which flies by rotating each propeller with the corresponding motor.

Related Art

As one example of this type of technology, a rotary-wing unmanned aircraft (multicopter) described in Japanese unexamined patent application publication No. 2015-212139 (JP 2015-212139 A) is known. The multicopter has an airframe, a plurality of support arms extending from the airframe, and propulsion units mounted to the distal ends of the respective support arms. Each propulsion unit includes a propeller and a motor that drives the propeller. Here, the airframe is provided with a means (propeller guard) for protecting the propellers, so as to protect each propeller against shocks received when the multicopter contacts or collides with an obstacle, and conversely, to prevent each propeller from coming into contact with an individual or an object when the multicopter gets close to the individual or object.

The propeller guard has a plurality of removable lateral bumpers positioned beyond the area of rotation of each propeller and connected to the corresponding propulsion units via connection arms. The connection arm includes a pair of elastically deformable blades having at their ends a clamp mounted on a barrel of the motor.

SUMMARY

Technical Problems

In the case where the multicopter described in JP 2015-212139 A collides with an obstacle or the like (collision object) at such a speed that the propeller guard is damaged or broken, one or more of the rotating propellers may contact the collision object. To deal with this risk, it may be considered to provide the propeller guard with a rigid structure that would avoid damage thereof. However, in this case, the propeller guard may become heavier, resulting in an increase in the overall weight of the multicopter, and the flight performance may be adversely affected.

The disclosed technology has been developed in view of the above situation, and its object is to provide a multicopter that can prevent a rotating propeller from contacting a collision object even if the multicopter collides with the collision object at such a speed that a propeller guard is damaged during flight.

Means of Solving the Problems

(1) To achieve the above object, one aspect of the disclosure provides a multicopter including an airframe, a plurality of propellers mounted rotatably on the airframe, and a propeller guard installed to surround at least a part of the propellers, wherein the propeller guard is configured to be deformed or displaced to contact the propellers and stop rotation of the propellers when the multicopter collides with a collision object.

According to the configuration of the above technology, when the multicopter in flight collides with a collision object, the propeller guard is deformed or displaced so that the propeller comes into contact with the propeller guard before it contacts the collision object, and the propeller stops rotating.

Effect of the Invention

According to the technology described in (1) above, even if the multicopter collides with a collision object at such a speed that the propeller guard is damaged or broken during flight, the rotating propeller can be prevented from contacting the collision object.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

In the following, some embodiments of the multicopter will be described.

First Embodiment

Initially, a first embodiment will be described in detail with reference to the drawings.

The perspective view ofFIG.1shows the appearance of a multicopter1of this embodiment. As shown inFIG.1, the multicopter, which is one type of helicopter, is a rotary-wing aircraft on which three or more propellers (rotors) are installed. The multicopter1of this embodiment has an airframe2, a plurality of propellers (four in total in this embodiment)3mounted rotatably on the airframe2, and a propeller guard4installed to surround the propellers3. In this embodiment, the propellers3are arranged at equal angular intervals around the airframe2.

The airframe2has an airframe base11, and a plurality of arms (four in total in this embodiment)12cantilevered and radiating from the airframe base11. A plurality of motors (four in total in this embodiment)13is provided at distal ends of the respective arms12. Each propeller3is located on the upper side of the corresponding motor13, and is rotated and driven by the motor13. The multicopter1is designed to fly by rotating the propellers3simultaneously with the corresponding motors13. A pair of brackets (four pairs in total in this embodiment)14that extends outwardly while splitting in two is provided on the outer periphery of each motor13. The propeller guard4is supported at the distal ends of the brackets14, and is located to surround the outer sides of the propellers3. A battery that supplies electric power to each motor13, a controller for controlling each motor13, and other components are provided inside the airframe base11.

In this embodiment, the propeller guard4is configured to be displaced and contact one or more propellers3to stop rotation of the propeller(s)3when the multicopter1collides with a collision object, such as an obstacle.

The propeller guard4includes fixed frames21fixed to the respective brackets14, and a plurality of movable frames (four in total in this embodiment)22each positioned in the vicinity of the plane of rotation of a corresponding one of the propellers3. In this embodiment, the propeller guard4is mainly formed of a resin material. Each movable frame22is located on one side of the corresponding propeller3opposite to the airframe base11. Each movable frame22has a pivot point31that serves as the center of rotation of the movable frame22and is supported by the fixed frame21, and an engagement portion32located remote from the pivot point31. In the engagement portion32, a part of the movable frame22detachably engages with the corresponding fixed frame21. When an external force is applied to one of the movable frames22toward the corresponding propeller3, the engagement portion32is disengaged from the fixed frame21, and the movable frame22turns toward the corresponding propeller3about the pivot point31. In this embodiment, at least a portion of the movable frame22having a possibility of contacting the propeller3consists of a plastic member that is plastically deformable. For example, “clay, gel sheet, or plastically deformable metal” may be used as the plastic member.

The perspective views ofFIG.2andFIG.3show the engagement portion32of the movable frame22and its vicinity.FIG.2shows the engaged state of the engagement portion32engaged with the fixed frame21, andFIG.3shows the disengaged state of the engagement portion32disengaged from the fixed frame21. An annular sandwiching portion32ais provided at an end of the fixed frame21, and a sandwiched portion32bthat is sandwiched by the sandwiching portion32ato engage therewith is provided at one end of the movable frame22. The sandwiching portion32aincludes a center hole32aa, and a slit32abthat intersects the center hole32aa. The sandwiched portion32bincludes an arm portion32bathat can fit into the slit32abof the sandwiching portion32a, and a protrusion32bbthat protrudes from the arm portion32baand can engage with the center hole32aaof the sandwiching portion32a.

(Operation and Effect of Multicopter)

The multicopter1of this embodiment, which is configured as described above, operates as follows.FIG.4andFIG.5are schematic plan views showing the movable frame22of the propeller guard4and others. During normal flight of the multicopter1, the propeller3rotates while being spaced a given distance from the propeller guard4, and its rotation is protected by the propeller guard4, as shown inFIG.4.

On the other hand, when the multicopter1in flight collides with a collision object at such a speed that the propeller guard4is damaged or broken, the propeller guard4is displaced, so that the propeller3contacts the propeller guard4before contacting the collision object, and the propeller3stops rotating. Namely, when the multicopter1collides with the collision object, and an external force F1of a certain magnitude or larger is applied to the movable frame22as a part of the propeller guard4, as shown inFIG.5, the movable frame22turns toward the propeller3about the pivot point31. At this time, the propeller3contacts the propeller guard4(the movable frame22) before contacting the collision object, and the propeller3stops rotating. It is thus possible to avoid contact between the collision object and the rotating propeller3. Namely, the propeller3comes into contact with the collision object in a condition where its rotation is stopped. Thus, even if the multicopter1collides with the collision object at such a speed that the propeller guard4is damaged during flight, contact of the rotating propeller3with the collision object can be avoided. As a result, damage to the collision object received from the propeller3can be curbed.

According to the configuration of this embodiment, the portion of the propeller guard4having the possibility of contacting the propeller3consists of the plastic member; therefore, the portion contacting the propeller3is easily deformed at the time of a collision and also easily restored to its original shape. Thus, the portion of the propeller guard4contacting the propeller3can be reused after the collision.

Second Embodiment

Next, the second embodiment will be described in detail with reference to the drawings. In the following description, the same reference numerals are assigned to substantially the same constituent elements as those of the first embodiment, of which description will not be provided, and differences from the first embodiment will be mainly described.

This embodiment is different from the first embodiment in the configuration of the propeller guard4. The perspective views ofFIG.6andFIG.7show the engagement portion32of the movable frame22and its vicinity.FIG.6shows the engaged state of the engagement portion32engaged with the fixed frame21, andFIG.7shows the disengaged state of the engagement portion32disengaged from the fixed frame21. In this embodiment, the configuration of the engagement portion32, etc. is different from that of the first embodiment. Namely, as shown inFIG.6andFIG.7, the sandwiching portion32aof the fixed frame21has a recess32acthat is open to the inside (the side facing the propeller3) of the movable frame22, in place of the center hole32aaof the first embodiment. At the distal end of the arm portion32baof the sandwiched portion32b, a pin portion32bcis formed integrally with the arm portion32bato form a T shape. The pin portion32bcfits into the recess32acand is sandwiched by the sandwiching portion32a, to be thereby engaged with the recess32ac.

(Operation and Effect of Multicopter)

According to the configuration of the multicopter1of this embodiment described above, substantially the same operation and effects as those of the first embodiment can be obtained even though the configuration of the engagement portion32, etc. is different from that of the first embodiment.

Third Embodiment

Next, a third embodiment will be described in detail with reference to the drawings.

In this embodiment, the configuration of the movable frame22is different from those of the above embodiments. The plan views ofFIG.8andFIG.9, which correspond toFIG.4andFIG.5, respectively, show a movable frame22of a propeller guard4and others. As shown inFIG.8andFIG.9, a rotation stopper40that actively stops rotation of the propeller3by contacting the propeller3is provided in a turning end portion of the movable frame22as a portion of the propeller guard4having a possibility of contacting the propeller3.

The rotation stopper40is shown in the cross-sectional view ofFIG.10taken along line A-A inFIG.9. As shown inFIG.10, in this embodiment, the rotation stopper40is formed in a block shape using a rubber material, and has a slit structure41that can contact the distal end of the propeller3to nip and hold the same.

(Operation and Effect of Multicopter)

According to the configuration of the multicopter1of this embodiment described above, the propeller guard4contacts the propeller3via the rotation stopper40, and the propeller3is forced to stop rotating. More specifically, the propeller3is caught in the slit structure41and thus secured to the propeller guard4, so that the propeller3is forced to stop rotating. Thus, the propeller3can be surely stopped.

Fourth Embodiment

Next, a fourth embodiment will be described in detail with reference to the drawings.

In this embodiment, a rotation stopper40of a movable frame22is different from that of the third embodiment.

In this embodiment, the rotation stopper40is formed by an adhesive member (seeFIG.8andFIG.9) that can contact the propeller3. For example, “adhesive tape, adhesive, or birdlime” may be used as the adhesive member.

(Operation and Effect of Multicopter)

According to the configuration of the multicopter1of this embodiment described above, the propeller3is secured to the propeller guard4by the adhesive force of the adhesive member, and the propeller3is forced to stop rotating. Thus, the propeller3can be surely stopped.

Fifth Embodiment

Next, a fifth embodiment will be described in detail with reference to the drawings.

In this embodiment, a rotation stopper40of a movable frame22is different from those of the third and fourth embodiments.

In this embodiment, the rotation stopper40is formed by a foam member (seeFIG.8andFIG.9) that can contact the propeller3. For example, “urethane foam, foamed rubber, or foamed polystyrene (styrene foam)” may be used as the foam member.

(Operation and Effect of Multicopter)

According to the configuration of the multicopter1of this embodiment described above, the propeller3cuts into the foam member to be secured to the propeller guard4, so that the propeller3is forced to stop rotating. Thus, the propeller3can be surely stopped.

Other Embodiments

The disclosed technology is not limited to the embodiments described above, but may be carried out by changing a part of the configuration as appropriate, without departing from the principle of the disclosed technology.

(1) In each of the above embodiments, a part (the movable frame22) of the propeller guard4is configured to be displaced and contact the corresponding propeller3to stop rotation of the propeller3when the multicopter1collides with a collision object. Instead, a part of the propeller guard may be configured to be deformed (e.g., bent) and contact the corresponding propeller to stop rotation of the propeller when the multicopter collides with a collision object. Also, the entire propeller guard may be plastically deformable, and a part of the propeller guard may be configured to be deformed (e.g., bent, dented, etc.). In this case, even if a part of the propeller guard is deformed, it can easily return to its original shape.

(2) In each of the above embodiments, one propeller guard4is provided which surrounds a plurality of propellers3of the multicopter1, and the propeller guard4is provided with the movable frames22. Instead, each propeller may be provided with a propeller guard that surrounds the propeller, and each propeller guard may be provided with a movable frame.

(3) While four propellers3are provided on the multicopter1in each of the above embodiments, this number of the propellers3is an example, and three or more may be suitably assumed to be the number of propellers.

(4) While the propellers3are arranged at equal angular intervals around the airframe2in each of the above embodiments, they are not necessarily arranged at equal angular intervals.

(5) While each propeller3is located above the corresponding motor13in each of the above embodiments, each propeller may be located below the corresponding motor.

INDUSTRIAL APPLICABILITY

The disclosed technology may be applied to various types of multicopters used in various applications.

REFERENCE SIGNS LIST