Falling-time impact cushioning member for movable body

Abstract

To provide a technique for cushioning falling-time impact for a movable body.SOLUTION: An impact cushioning member (1) for a movable body comprises an arch-shaped outer peripheral part attached to at least one of two tips in the vehicle center axis direction of the movable body and bent to cover the tips in three directions of up, down and front directions in a side view. The upper and lower parts (12 and 13) of the outer peripheral part are provided with an elastically deformable planar cushioning part (10) and a plurality of columnar cushioning parts (20) elastically deformable in a columnar axis direction which are bent to cover the tips in a plan view.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a shock absorbing member for a moving object when dropped. [Background technology]

[0002] Small unmanned exploration vehicles are used to explore the surface of the moon. For example, Patent Documents 1 to 3 disclose unmanned exploration vehicles that are suitable for traveling on rough ground covered with sand, stones, etc.

[0003] Observations from satellites have revealed the existence of huge vertical holes on the surface of the Moon. These holes suggest the existence of underground cavities extending beneath them. These underground cavities are dust-free spaces with smooth, solid floors and are approximately 100m to 50km in size, making them promising sites for building lunar bases. Unmanned rovers are expected to explore these underground cavities and gather information. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-168970 [Patent Document 2] Japanese Patent Publication No. 2020-172222 [Patent Document 3] Patent Publication No. 2021-49795 Summary of the Invention [Problem to be solved by the invention]

[0005] Because the underground cavity is at the bottom of a vertical shaft, the unmanned exploration vehicle must drop down the shaft to reach the bottom. However, there is a risk that the unmanned exploration vehicle may be damaged by the impact of the fall. Therefore, technology is needed to mitigate the impact on the unmanned exploration vehicle when it is dropped.

[0006] An object of one aspect of the present invention is to provide a technique for mitigating impact on a moving body such as an unmanned exploration vehicle when it is dropped. [Means for solving the problem]

[0007] As a result of extensive research into solving the above problems, the inventors discovered that a structural design approach utilizing a compliant mechanism is an effective technique for mitigating the impact on a moving object when it is dropped, leading to the completion of the present invention.

[0008] That is, one aspect of the present invention is as follows.

[0009] [1] A shock-absorbing member for use in absorbing shock when dropped, attached to at least one of two end portions of a moving body in the vehicle central axis direction, an arch-shaped outer periphery that curves in three directions, upward, downward, and forward, so as to cover the tip end portion in a side view; and an elastically deformable planar buffer portion, in which an upper portion covering the upper direction and a lower portion covering the lower direction of the outer periphery are curved so as to cover the tip portion in a front view; a plurality of columnar buffer parts that are elastically deformable in a column axis direction and that are used to attach the planar buffer parts at a distance from the tip end part; A shock absorbing member for a moving body when dropped, comprising: [2] The shock absorber for a moving body when dropped according to [1], wherein the columnar shock absorber has an inclination of 10° or more and 60° or less with respect to the vehicle central axis when viewed from the side. [3] The planar buffer section and the columnar buffer section are made of a resin having a tensile modulus of elasticity of 0.1 MPa or more and 1000 GPa or less when measured according to the ISO 527-1 / -2 standard test method, and when the tensile modulus of elasticity of the resin constituting the planar buffer section is set to 1, the tensile modulus of elasticity of the resin constituting the columnar buffer section is set to 10 or less. [1] A drop impact absorbing member for a moving body as described in [1] or [2]. [4] The shock absorbing member for a moving body when dropped according to any one of [1] to [3], wherein the planar shock absorbing portion has a curved surface portion with a constant curvature. [5] The shock-absorbing member for a moving body when dropped according to any one of [1] to [4], wherein the planar shock-absorbing portion has a flat surface in part. [6] The shock absorbing member for a moving body when dropped according to any one of [1] to [5], wherein the planar shock absorbing portion has a curved surface portion whose curvature changes continuously. [7] A drop impact absorbing member for a moving body described in any one of [1] to [6], wherein the columnar buffer portion is a spring, and when the maximum distance between the upper and lower portions of the planar buffer portion is 100, the value of the second moment of area of ​​the wire cross section of the spring is 0.01 or more and 1000 or less. [8] The planar buffer portion has at least one slit portion extending in the up-down direction in a front view, The slit portion has a wide portion where the slit width is widened. The shock absorbing member for a moving body when dropped according to any one of [1] to [7]. [9] The shock absorbing member for a moving body when dropped according to any one of [1] to [8], which comprises a ground contact portion that contacts the ground when the moving body moves along the ground.

[10] The shock-absorbing member for a moving body when dropped, as described in [9], wherein the planar shock-absorbing portion and the ground contact portion form a continuous surface.

[11] The shock absorber for a moving body when dropped according to any one of [1] to

[10] , wherein the planar shock absorber and the columnar shock absorber are integrally formed.

[12] A drop impact absorbing member for a moving body described in any one of [1] to

[11] , wherein the planar buffer portion is configured to have a thickness in the range of 0.5% or more and 50% or less of the maximum distance between the upper and lower parts of the planar buffer portion.

[13] The shock-absorbing member for a moving body when dropped according to any one of [1] to

[12] , wherein the moving body is an unmanned vehicle or an extraterrestrial unmanned vehicle. [Effects of the Invention]

[0010] According to one aspect of the present invention, it is possible to provide a technique for mitigating the impact on a moving object when it is dropped. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a state in which a shock-absorbing member for a moving body when dropped according to an embodiment of the present invention is attached to the tip of an unmanned vehicle. [Figure 2] 2 is a side view of the shock-absorbing member for a moving body when dropped shown in FIG. 1. FIG. [Figure 3] 2 is a front view of the shock-absorbing member for a moving body when dropped shown in FIG. 1. FIG. [Figure 4] 2 is a top view of the shock-absorbing member for a moving object when dropped shown in FIG. 1. FIG. [Figure 5] 5 is a cross-sectional view taken along line AA' of the drop impact cushioning member for a moving body shown in FIG. 4. FIG. [Figure 6] 10 is a side view of a shock-absorbing member for a moving body when dropped according to a first modified example. FIG. [Figure 7] 10 is a side view of a drop impact cushioning member for a moving body according to Modification 2. FIG. [Figure 8] 1 is a perspective view showing the configuration of a shock absorbing member for a moving body when dropped according to Comparative Example 1. FIG. [Figure 9] FIG. 10 is a diagram showing the simulation results of the maximum tensile stress applied to each part when an unmanned vehicle equipped with a drop impact absorbing member for a moving body according to a comparative example and an example is dropped in direction a. [Figure 10] FIG. 10 is a diagram showing the simulation results of the maximum tensile stress applied to each part when an unmanned vehicle equipped with a drop impact absorbing member for a moving body according to a comparative example and an example is dropped in direction b. DETAILED DESCRIPTION OF THE INVENTION

[0012] [1. Drop shock absorbing materials for mobile objects] An embodiment of the present invention will be described in detail below with reference to the drawings. In this embodiment, an unmanned vehicle is used as an example of a moving body, and an embodiment in which a member for absorbing impact when dropped for a moving body according to this embodiment is applied as a member for absorbing impact when dropped for an unmanned vehicle will be described. For convenience of explanation, the "member for absorbing impact when dropped for a moving body" may be simply referred to as the "impact absorbing member."

[0013] 1 is a perspective view showing an impact buffering member 1 according to this embodiment attached to the tip of a vehicle body M1 of an unmanned vehicle M. The drawing also shows three-dimensional coordinates of an XYZ system in which the axle direction of the two wheels M2 of the unmanned vehicle M is the X axis, the vehicle central axis direction of the unmanned vehicle M is the Y axis, the horizontal plane is defined as the XY plane, and the vertical direction is the Z axis.

[0014] In this specification, the "vehicle center axis" refers to an imaginary line that passes through the center of the wheel axle and is perpendicular to the axle when viewed from above. For example, in Figure 1, the dashed dotted line C represents the vehicle center axis.

[0015] Furthermore, in this specification, the terms "side view," "front view," and "top view" used to describe an impact buffering member according to an embodiment of the present invention have the following meanings. Specifically, "side view" refers to the viewpoint when viewing the impact buffering member 1 from the axle direction of the unmanned vehicle M when the impact buffering member 1 is attached to the tip of the vehicle main body M1. For example, in FIG. 1, "side view" refers to the viewpoint when viewing the impact buffering member 1 from the positive direction of the X-axis.

[0016] Furthermore, "front view" refers to the viewpoint when the impact buffering member 1 is viewed from the front end side of the unmanned vehicle M along the vehicle central axis direction when the impact buffering member 1 is attached to the front end of the vehicle main body M1. For example, in Figure 1, "front view" refers to the viewpoint when the impact buffering member 1 is viewed from the negative direction of the Y axis.

[0017] Furthermore, "top view" refers to the viewpoint when the impact buffering member 1 is viewed vertically from above the unmanned vehicle M when the impact buffering member 1 is attached to the tip of the vehicle body M1. For example, in Figure 1, "top view" refers to the viewpoint when the impact buffering member 1 is viewed from the positive direction of the Z axis in Figure 1.

[0018] The shock absorbing member 1 is attached to at least one of the two tip portions of the unmanned vehicle M in the direction of the vehicle central axis C for the purpose of absorbing shock when dropped. When the unmanned vehicle M also touches the ground with the shock absorbing member 1, it will touch the ground at a total of three points, including the contact points of the two wheels. In this case, the running posture of the unmanned vehicle M will be more stable if the position of the third point of the shock absorbing member 1 is farther from the two contact points of the two wheels. For this reason, by attaching the shock absorbing member 1 to the tip portion of the unmanned vehicle M in the direction of the vehicle central axis C, the position of the shock absorbing member 1 will be farther from the two contact points of the two wheels, which has the effect of further improving the stability of the unmanned vehicle M during running when it touches the ground at three points.

[0019] The impact absorbing member 1 may be attached to the front end or the rear end of the vehicle main body M1, but Figure 1 illustrates an example in which the impact absorbing member 1 is attached to the rear end of the vehicle main body M1.

[0020] The shock-absorbing member 1 includes a planar buffer portion 10 and four springs (columnar buffer portions) 20a to 20d. Note that the spring 20c is hidden behind the planar buffer portion 10 and is therefore not shown in FIG.

[0021] The impact buffering member 1 is attached to the rear tip of the unmanned vehicle M via springs 20a-d. By interposing the springs 20a-d between the planar buffering part 10 and the tip of the vehicle main body part M1, the planar buffering part 10 can be attached at a distance from the tip.

[0022] (Planar buffer) The planar buffer section 10 is an elastically deformable member. Here, "elastically deformable" means that it deforms when subjected to an external force, but returns to approximately its original shape due to its elasticity when the external force is removed.

[0023] Typically, methods for improving the impact resistance of components include increasing their wall thickness or adding ribs to increase rigidity and suppress deformation. However, adding wall thickness or structure also increases weight, which is disadvantageous for applications requiring lightweight construction, such as space development. Therefore, the present invention was designed using the concept of a compliant mechanism, which absorbs impact through elastic deformation. Components designed based on this concept flexibly deform when impact is applied, efficiently dispersing stress within the component and converting the impact into thermal energy for release, thereby avoiding component destruction due to stress concentration. Furthermore, because high rigidity is not required, increases in component weight can be suppressed. In the following description, specifications such as elastic modulus and stress ratio are derived using the concept of a compliant mechanism.

[0024] FIG. 2 is a side view of the impact buffer 1 shown in FIG. 1, as viewed from the positive direction of the X-axis. In FIG. 2, springs 20a and 20b are not shown because they are hidden behind springs 20c and 20d, respectively. As shown in FIG. 2, the planar buffer 10 has an arched outer periphery that curves in three directions—upward, downward, and forward—in a side view to cover the leading end of the vehicle main body M1. Because the planar buffer 10 is a planar member having an arched outer periphery formed using an elastic material, it elastically deforms when subjected to an external force, causing the arched outer periphery to flex. The flexing of the arched outer periphery allows the planar buffer 10 to efficiently distribute stress in the planar direction (i.e., spatial distribution).

[0025] The arch-shaped outer periphery of the planar buffer section 10 is made up of a front section 11 that covers the tip of the vehicle main body section M1 from the front, an upper section 12 that covers it from above, and a lower section 13 that covers it from below.

[0026] The front portion 11 has a curved shape with a curved surface portion whose curvature changes continuously. Because the front portion 11 has such a shape, it is prone to elastic deformation when subjected to an external force, causing deflection at the outer periphery of the front portion 11, and the planar cushioning portion 10 can efficiently distribute stress in the planar direction.

[0027] The upper part 12 is configured to extend in the positive direction of the Y axis from the end of the front part 11. Of the upper part 12, the part covering the upper surface of the tip part of the vehicle main body part M1 is called the second upper part 122, and the part located closer to the front part 11 than this is called the first upper part 121.

[0028] The lower part 13 is configured to extend in the positive direction of the Y axis from the end of the front part 11. Of the lower part 13, the part covering the underside of the tip of the vehicle main body part M1 is called the second lower part 132, and the part located closer to the front part 11 than this is called the first lower part 131.

[0029] 3 is a front view of the impact buffer member 1 shown in FIG. 1 as viewed from the negative direction of the Y axis. As shown in FIG. 3, the upper portion 12 and the lower portion 13 are curved so as to cover the tip portion of the vehicle main body M1 in a front view. Because the upper portion 12 and the lower portion 13 have such a shape, they are elastically deformed when subjected to an external force, causing deflection in the curved outer peripheries of the upper portion 12 and the lower portion 13. The deflection of the curved outer peripheries of the upper portion 12 and the lower portion 13 allows the planar buffer member 10 to efficiently disperse stresses received from above and below in the planar direction.

[0030] 3, the planar buffer 10 has one slit 14 extending in the vertical direction when viewed from the front. By having the slit 14 in the planar buffer 10, when the unmanned vehicle M travels on sandy ground, sand that has flowed into the impact buffer member 1 can be efficiently discharged through the slit 14. Furthermore, by having the slit 14 in the planar buffer 10, a "flexure allowance" is created, which has the effect of absorbing displacements that occur in the left and right members.

[0031] The slit portion 14 extends to the upper portion 12 and the lower portion 13 along the arch shape of the arch-shaped outer periphery of the planar cushioning portion 10. Fig. 4 is a top view of the shock-absorbing member 1 shown in Fig. 1 as viewed from the positive direction of the Z axis. As shown in Fig. 4, the slit portion 14 extends upward to partway through the first upper portion 121 of the upper portion 12. Furthermore, although not shown, the slit portion 14 extends downward to partway through the first lower portion 131 of the lower portion 13.

[0032] The slit width of the slit portion 14 is not particularly limited and can be set as appropriate. As shown in Figures 3 and 4, in the shock-absorbing member 1 according to this embodiment, the slit width of the slit portion 14 is constant in the front portion 11 and gradually narrows from there toward the extension direction of the upper portion 12 (the positive Y-axis direction in Figure 4). As shown in Figure 4, in a top view of the planar buffer 10, the slit portion 14 provided in the upper portion 12 has a generally U-shape in which the slit width gradually narrows toward the extension direction of the upper portion 12. Although not shown, the slit width in the extension direction of the lower portion 13 also gradually narrows from the front portion 11 toward the extension direction of the lower portion 13.

[0033] In this way, by providing the slit portion 14 so that the slit width gradually narrows in the direction of extension of the upper portion 12 and the lower portion 13, it is possible to prevent increased friction and snagging caused by the slit portion 14 during travel.

[0034] From the viewpoint of ensuring the strength of the planar cushioning member 10, the slit width w1 of the slit portion 14 is preferably 80% or less of the length (total width) in the width direction (X-axis direction shown in FIG. 3) of the planar cushioning member 10. Furthermore, the slit width w2 in the portion corresponding to the bending portion where the curvature of the curved surface of the front portion 11 changes significantly can be 5 to 70% of the length (total width) in the width direction (X-axis direction shown in FIG. 3) of the planar cushioning member 10.

[0035] The thickness of the surface of the planar buffer section 10 can be set as appropriate. However, from the viewpoint of maintaining the strength of the planar buffer section 10, the thickness is preferably 0.5% or more of the maximum distance between the upper portion 12 and the lower portion 13 of the planar buffer section 10, and more preferably 1% or more. Furthermore, from the viewpoint of maintaining the cushioning function against deformation, the planar buffer section 10 preferably has a thickness of 50% or less of the maximum distance between the upper portion 12 and the lower portion 13 of the planar buffer section 20. Note that in this specification, the thickness of the surface of the planar buffer section 10 is the average value when the thickness is measured at any five points on the planar buffer section 10. The positions of the any five points are not particularly limited. For example, the five points can be five points on the line where a plane passing through the axle and the vehicle center axis C intersects with the planar buffer section 10. Furthermore, the "maximum distance between the upper portion 12 and the lower portion 13 of the planar buffer portion 20" refers to the maximum value of the height in the Z direction (vertical direction) between the upper portion 12 and the lower portion 13 of the planar buffer portion 20 when the planar buffer portion 10 is attached to the tip of the vehicle body portion M1 and the vehicle body portion M1 is placed on a flat surface. In this specification, for convenience of explanation, the "maximum distance between the upper portion 12 and the lower portion 13 of the planar buffer portion 20" may be referred to as "distance (A)."

[0036] In order to prevent the occurrence of areas where stress is concentrated during a collision, it is preferable that the arched outer periphery of the planar cushioning part 10 has a continuous surface, with the upper part 12, front part 11, and lower part 13 following the arch shape. Here, "continuous surface" means, for example, a surface that is smoothly connected with almost no steps when viewed macroscopically. Note that protrusions such as ribs, which will be described later, may be attached to the surface.

[0037] (Spring) The four springs 20a-d are provided on the surface of the planar buffer portion 10 on the tip side so as to extend in a direction intersecting the surface of the planar buffer portion 10 in order to mount the planar buffer portion 10 at a distance from the tip end of the vehicle main body portion M1.

[0038] The springs 20a-d are elastically deformable in the spring axis direction. The term "elastically deformable" is as explained for the planar buffer portion. By introducing the springs 20a-d into the connection portion with the vehicle main body portion M1, the transmission of impact to the vehicle main body portion M1 can be delayed (i.e., temporal dispersion), and instantaneous stress concentration on the vehicle main body portion M1 can be avoided. In the following explanation, the four springs 20a-d may be referred to simply as springs 20 without distinction.

[0039] By attaching the planar buffer section 10 to the tip end of the vehicle main body M1 using four springs 20a-d, the planar buffer section 10 can be stably attached. The number of springs 20 is not particularly limited as long as it is a number that allows for stable attachment of the planar buffer section 10. For example, the number of springs 20 can be 2 to 10, and from the viewpoint of attachment balance, the number of springs 20 is preferably 3 to 6, and more preferably 4.

[0040] From the viewpoint of suppressing excessive deformation, the spring 20 preferably has a value of the second moment of area of ​​the wire rod cross section of the spring 20 of 0.01 or more when the distance (A) is 100, more preferably 0.1 or more, even more preferably 0.5 or more, and particularly preferably 1.0 or more. As shown in the examples described later, if the value of the second moment of area of ​​the wire rod cross section of the spring 20 when the distance (A) is 100 is 0.01 or more, the spring can more effectively absorb impact when dropped on a moving object. In particular, if the value of the second moment of area of ​​the wire rod cross section of the spring 20 when the distance (A) is 100 is 0.5 or more, a more excellent impact absorption effect can be obtained against impacts from multiple directions (for example, directions a and b shown in the examples).

[0041] Furthermore, from the viewpoint of maintaining appropriate flexibility, when the distance (A) is taken as 100, the value of the second moment of area of ​​the wire cross section of the spring 20 is preferably 1000 or less, and more preferably 100 or less.

[0042] FIG. 5 is a cross-sectional view taken along line A-A' of the impact buffer member 1 shown in FIG. 4. As shown in FIG. 5, the spring 20 is attached to the tip of the vehicle main body M1 so as to be inclined with respect to the vehicle center axis C in a side view. This allows for efficient absorption of impact. The inclination of the spring 20 with respect to the vehicle center axis C is sometimes referred to as the "connection angle." Also, as shown in FIG. 5, the spring 20 may be attached to the planar buffer 10 via an attachment portion 21.

[0043] Springs 20a and 20b, which are adjacent to each other vertically across vehicle center axis C, preferably have a symmetrical positional relationship with respect to a plane that passes through vehicle center axis C and is parallel to the XY plane, and more preferably are inclined at the same angle with respect to vehicle center axis C. Specifically, the inclination α1 of spring 20a with respect to vehicle center axis C and the inclination α2 of spring 20b with respect to vehicle center axis C are preferably the same angle. Since inclination α1 and inclination α2 are the same, springs 20a and 20b are arranged line-symmetrically with respect to vehicle center axis C in a side view. This achieves a symmetrical balance of the entire spring 20, which is less likely to cause problems with driving, etc. Although not shown in FIG. 5, springs 20c and 20d, which are adjacent to each other vertically, preferably also have the same inclination angle with respect to vehicle center axis C.

[0044] Furthermore, from the viewpoint of absorbing impact more efficiently, the spring 20 preferably has an inclination of 10° or more and 60° or less relative to the vehicle center axis C when viewed from the side, more preferably an inclination of 10° or more and less than 60°, even more preferably an inclination of 15° or more and 45° or less, and particularly preferably an inclination of 30°.

[0045] As shown in FIG. 3 , adjacent springs 20a and 20c on either side of the vehicle center axis C are arranged parallel to each other in a front view. The same applies to adjacent springs 20b and 20d on either side of the vehicle center axis C. This results in a symmetrical balance of the entire spring 20, which is less likely to interfere with driving, etc. The lengths of springs 20a-b may be asymmetrical as long as the positional relationship of adjacent springs 20a and 20c or 20b and 20d on either side of the vehicle center axis C is symmetrical with respect to a plane that passes through the vehicle center axis C and is parallel to the ZY plane. Since it is preferable that the overall length of the connecting member from the tip of the vehicle main body M1 to the planar buffer unit 10 be the same, if the lengths of springs 20a-b are different, the overall length of the connecting member formed by spring 20 and mounting portion 21 can be made the same by adjusting the length of the pillar portion of mounting portion 21.

[0046] There are no particular limitations on the cross-sectional shape of the spring 20. For example, a spiral spring with a circular cross section, a spiral spring with a rectangular cross section, a spiral spring with an elliptical cross section, a spiral spring with a square cross section, or the like can be used as the spring 20. From the viewpoint of the balance between flexibility and rigidity, a spiral spring with a rectangular cross section is particularly preferable.

[0047] From the viewpoint of efficiently absorbing impact, it is preferable that the spring diameter of spring 20 is large. For example, the spring diameter of spring 20 is 1 / 15 or more, preferably 1 / 10 or more, and more preferably 1 / 8 or more of the overall width of planar buffer section 10. Furthermore, there is no particular limitation on the upper limit of the spring diameter of spring 20 as long as it can be accommodated in mounting section 21.

[0048] Furthermore, from the viewpoint of efficiently absorbing impact, it is preferable that the number of turns of the spring 20 is large. For example, the number of turns of the spring 20 is preferably 2 or more, and more preferably 3 or more. Furthermore, from the viewpoint of impact resistance performance, there is no particular upper limit to the number of turns of the spring 20. The upper limit may be selected as appropriate from the viewpoint of formability and dimensional constraints. Furthermore, from the viewpoint of efficiently absorbing impact, it is preferable that the cross-sectional area of ​​the spring 20 is large.

[0049] (Grounding part) The shock absorbing member 1 preferably has a ground contact portion that comes into contact with the ground when the unmanned vehicle M moves along the ground. Providing the shock absorbing member 1 with a ground contact portion has the effect of improving the stability of the unmanned vehicle M's travel.

[0050] The shock-absorbing member 1 may have a ground contact portion as a separate member from the planar buffer portion 10, or the planar buffer portion 10 may be configured so that a specific portion of the planar buffer portion 10 functions as the ground contact portion. In this embodiment, the latter example will be described.

[0051] The impact buffering member 1 according to this embodiment is configured so that the lower portion 13 of the planar buffering portion 10 functions as a ground contact portion. Specifically, the curved outer periphery of the lower portion 13 of the planar buffering portion 10 in a front view of the impact buffering member 1 is configured to come into contact with the ground when the unmanned vehicle M moves along the ground.

[0052] As described above, by providing the planar buffer portion 10 with a specific shape, the impact buffering member 1 can efficiently distribute stress during a collision throughout the entire structure of the planar buffer portion 10. Furthermore, by providing multiple springs (columnar buffer portions) 20a-d, it is possible to avoid instantaneous stress concentration on the vehicle main body portion M1. In this way, by using both the planar buffer portion 10 and multiple springs (columnar buffer portions) 20a-d, the impact buffering member 1 can effectively mitigate the impact on the unmanned vehicle M when it is dropped.

[0053] <Materials of the surface buffer and spring> The material constituting the planar buffer section 10 and the spring 20 is not particularly limited as long as it is an elastic material. Examples of elastic materials include resin, wood, and metal. From the viewpoint of reducing the weight of the shock-absorbing member 1, resin is preferred among these. The resin can be appropriately selected from known resins. For example, a resin selected from the group consisting of polyamide-imide resin, polyether-imide resin, and polyphenylsulfone resin can be suitably used as the material constituting the planar buffer section 10 and the spring 20.

[0054] When resin is used as the material for forming the planar buffer portion 10 and the spring 20, from the viewpoint of maintaining rigidity, the resin preferably has a tensile modulus of elasticity of 0.1 MPa or more, and more preferably a resin with a tensile modulus of elasticity of 100 MPa or more. Furthermore, from the viewpoint of flexibility, the resin preferably has a tensile modulus of elasticity of 1000 GPa or less, and more preferably a resin with a tensile modulus of elasticity of 30 GPa or less. Herein, the "tensile modulus" of a resin refers to a value measured according to the ISO 527-1 / -2 standard test method.

[0055] Furthermore, from the viewpoint of efficiently dispersing stress, the smaller the difference between the tensile modulus of the resin constituting the planar buffer section 10 and the tensile modulus of the resin constituting the spring 20, the better. The "difference between the tensile modulus of the resin constituting the planar buffer section 10 and the tensile modulus of the resin constituting the spring 20" can be expressed as the ratio of the tensile modulus of the resin constituting the planar buffer section 10 to the tensile modulus of the resin constituting the spring 20. Specifically, when the tensile modulus of the resin constituting the planar buffer section 10 is set to 1, the tensile modulus of the resin constituting the columnar buffer section 20 is preferably 10 or less, and more preferably 5 or less. When the tensile modulus of the resin constituting the planar buffer section 10 is set to 1, the tensile modulus of the resin constituting the columnar buffer section 20 is within the above range. Therefore, when an external force is applied, not only the resin of the planar buffer section 10 or the spring 20 with the smaller tensile modulus of elasticity deforms, but both the planar buffer section 10 and the spring 20 elastically deform, thereby absorbing the shock. This results in effective shock absorption performance.

[0056] <Applicable vehicles> The configuration of the unmanned vehicle M to which the impact buffering member 1 according to this embodiment is applicable is not particularly limited. As an example, it may be an unmanned vehicle including a vehicle body, a pair of wheels arranged coaxially at both widthwise ends of the vehicle body, and a plurality of claws provided on the outer peripheral surfaces of the rims of the wheels, as described in Patent Documents 1 and 2. Furthermore, the unmanned vehicle M may be an unmanned vehicle (referred to as an "extraterrestrial unmanned vehicle") that has a configuration suitable for traveling in the environment of an extraterrestrial planet (e.g., Mars) or satellite (e.g., the Moon).

[0057] The application of the impact buffering member 1 according to this embodiment is not limited to the unmanned vehicle M described above, but can be applied as an impact buffering member for any moving body other than the unmanned vehicle M when it falls. When applying the impact buffering member 1 according to this embodiment to a moving body other than the unmanned vehicle M, the size of the impact buffering member 1 can be changed appropriately to match the shape and size of the moving body to which it is applied.

[0058] <Modifications of the planar buffer section> The shape of the outer periphery of the planar buffer portion of the shock-absorbing member according to one embodiment of the present invention is not limited to the above-described shape. Fig. 6 is a side view of shock-absorbing member 1A according to Modification 1, and Fig. 7 is a side view of shock-absorbing member 1B according to Modification 2. Note that in Figs. 6 and 7, as in Fig. 2, springs 20a and 20b are not shown because they are hidden behind springs 20c and 20d, respectively.

[0059] For example, like the shock-absorbing member 1A shown in FIG. 6, the outer periphery of the planar buffer portion 10A may have a shape with a curved surface portion having a certain curvature, such as a perfect sphere.

[0060] Furthermore, for example, in the shock-absorbing member according to one aspect of the present invention, the outer periphery of the planar buffer portion may partially have a flat portion.

[0061] 7, like the impact buffering member 1 shown in Fig. 2, the outer periphery of the planar buffering portion 10B is curved, with a curved portion whose curvature changes continuously, but the shapes and sizes of the upper portion 12B and lower portion 13B are different. The upper portion 12B and lower portion 13B of the planar buffering portion 10B are designed so that the areas of the second upper portion and second lower portion, which are portions that cover the top surface of the tip end of the vehicle main body portion M1, are smaller than those of the upper portion 12 and lower portion 13 of the planar buffering portion 10 shown in Fig. 2, and the curvature of the upper portion 12 and lower portion 13 is greater when viewed from the front.

[0062] Although not shown, the upper part of the planar buffer portion of the impact-absorbing member according to one embodiment of the present invention may extend to just before the tip of the vehicle body M1, and may not include a second upper part that covers the upper surface of the tip of the vehicle body M1. Similarly, the lower part of the planar buffer portion of the impact-absorbing member according to one embodiment of the present invention may extend to just before the tip of the vehicle body M1, and may not include a second lower part that covers the underside of the tip of the vehicle body M1. However, from the perspectives of responding to collisions from multiple directions and smoothly contacting the road surface to reduce resistance during driving, it is preferable that the upper and lower parts of the planar buffer portion of the impact-absorbing member according to one embodiment of the present invention extend to positions that cover the upper and lower surfaces of the tip of the vehicle body M1, and that the upper and lower parts include second upper and second lower parts.

[0063] Furthermore, the planar buffer portion of the impact buffer member according to one aspect of the present invention may not have a slit portion, or may have a plurality of slit portions.

[0064] Furthermore, although not shown, the slit portion may be provided with a wide portion where the slit width is increased. The location of the wide portion is not particularly limited. For example, the wide portion may be provided at a position of the slit portion that corresponds to the position of the opening M3 at the tip of the vehicle main body M1 when the impact buffer member is attached to the unmanned vehicle M. With this configuration, when the impact buffer member is attached to the unmanned vehicle M, the opening M3 is located behind the wide portion. Any component can be provided in the opening M3 as needed. Examples of such components include a power terminal. Therefore, providing the wide portion at such a position allows easy access to the component provided in the opening M3. From the viewpoint of easy access to the component provided in the opening M3, it is preferable that the slit width at the widest part of the wide portion be larger than the outer diameter of the opening M3.

[0065] Furthermore, for example, a protruding portion such as a rib protruding toward the unmanned vehicle M may be provided at any portion of the planar buffer portion, such as around the slit portion, as necessary.

[0066] <Modifications of columnar buffer parts> In this embodiment, a spring is used as an example of the columnar shock absorber, but the present invention is not limited to this. Examples of the columnar shock absorber include conventionally known columnar members that are elastically deformable in the column axis direction, such as a bellows structure.

[0067] <Method of manufacturing a drop impact absorbing member for a mobile body> The shock-absorbing member according to one embodiment of the present invention can be manufactured by molding a resin into a desired shape. As a method for molding the resin, a conventionally known resin molding method can be adopted, such as a method using a 3D printer, cutting, injection into a mold, etc.

[0068] In the shock-absorbing member according to one aspect of the present invention, the planar buffer portion and the columnar buffer portion may be integrally molded. This eliminates structurally discontinuous member joints and suppresses stress concentration at specific positions. However, from the viewpoint of mass productivity of the shock-absorbing member according to one aspect of the present invention, it is also preferable to mold the planar buffer portion and the columnar buffer portion separately.

[0069] 〔summary〕 A first aspect of the present invention provides a shock-absorbing member for a moving body during a fall, which is attached to at least one of two leading ends of the moving body in the vehicle central axis direction, and which includes an elastically deformable planar shock absorber having an arched outer periphery that curves upward, downward, and forward to cover the leading end in a side view, and an upper portion of the outer periphery that covers the upward direction and a lower portion that covers the downward direction that are curved to cover the leading end in a front view, and a plurality of columnar shock absorbers that are elastically deformable in a column axis direction for attaching the planar shock absorber at a distance from the leading end. This configuration effectively reduces the impact on the moving body when it is dropped.

[0070] A drop impact cushioning member for a moving body according to Aspect 2 of the present invention is preferably configured such that, in the above-mentioned Aspect 1, the columnar cushioning portion has an inclination of 10° or more and 60° or less with respect to the vehicle central axis in a side view. This configuration can more effectively cushion the impact on the moving body when it is dropped.

[0071] A drop impact cushioning member for a moving object according to aspect 3 of the present invention is preferably configured in accordance with aspect 1 or 2 above, such that the planar cushioning portion and the columnar cushioning portion are made of a resin having a tensile modulus of elasticity of 0.1 MPa or more and 1000 GPa or less when measured according to the ISO 527-1 / -2 standard test method, and the tensile modulus of elasticity of the resin making up the columnar cushioning portion is 10 or less when the tensile modulus of elasticity of the resin making up the planar cushioning portion is 1. This configuration makes it possible to more effectively cushion the impact on the moving object when it is dropped.

[0072] The drop impact cushioning member for a moving object according to Aspect 4 of the present invention may be configured such that, in any one of Aspects 1 to 3, the planar cushioning portion has a curved surface portion with a constant curvature. This configuration can more effectively cushion the impact on the moving object when it is dropped.

[0073] A drop impact cushioning member for a moving body according to a fifth aspect of the present invention is any one of the first to fourth aspects, and may be configured such that the planar cushioning portion has a flat portion in part.

[0074] A sixth aspect of the present invention provides a drop shock absorbing member for a moving object according to any one of the first to fifth aspects, wherein the planar shock absorbing portion has a curved surface portion whose curvature changes continuously. This configuration can more effectively absorb the impact on the moving object when it is dropped.

[0075] A drop impact cushioning member for a moving object according to aspect 7 of the present invention is preferably configured in any one of aspects 1 to 6 above, wherein the columnar cushioning section is a spring, and the value of the second moment of area of ​​the wire cross section of the spring is 0.01 or more and 1000 or less, where the maximum distance between the upper and lower parts of the planar cushioning section is 100. With this configuration, it is possible to more effectively cushion the impact on the moving object when it is dropped.

[0076] The impact-absorbing member for a moving body according to aspect 8 of the present invention is any one of aspects 1 to 7 above, wherein the planar shock-absorbing portion has at least one slit portion extending in the vertical direction in a front view, and the slit portion has a wide portion where the slit width is widened. With this configuration, sand can be efficiently discharged out of the impact-absorbing member when traveling on sandy ground, etc.

[0077] The shock-absorbing member for a moving body when dropped according to a ninth aspect of the present invention may be configured to include a ground contact portion that contacts the ground when the moving body moves along the ground in any one of the above-mentioned aspects 1 to 8. This configuration can improve the running stability of the moving body.

[0078] A drop impact cushioning member for a moving object according to aspect 10 of the present invention is preferably configured such that the planar cushioning portion and the contact portion form a continuous surface in the above-mentioned aspect 9. This configuration can more effectively cushion the impact on the moving object when it is dropped.

[0079] The drop impact cushioning member for a moving body according to aspect 11 of the present invention may be configured such that the planar cushioning portion and the columnar cushioning portion are integrally molded in any one of the above aspects 1 to 10. This configuration is expected to eliminate structurally discontinuous member joints and suppress stress concentration at specific positions.

[0080] A drop impact cushioning member for a moving object according to aspect 12 of the present invention is preferably configured such that, in any one of aspects 1 to 11 above, the planar cushioning portion has a thickness in the range of 0.5% to 50% of the maximum distance between the upper and lower parts of the planar cushioning portion. This configuration makes it possible to more effectively cushion the impact on the moving object when it is dropped.

[0081] A thirteenth aspect of the present invention provides a shock absorbing member for a moving body when dropped, in any one of the first to twelfth aspects above, wherein the moving body may be an unmanned vehicle or an extraterrestrial unmanned vehicle.

[0082] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present invention. [Example]

[0083] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0084] [Examples 1 to 22, Comparative Examples 1 and 2] Impact buffering members of Examples 1 to 22 and Comparative Examples 1 and 2 were manufactured by changing specifications such as the shape of the planar buffering portion, the angle at which the columnar buffering portion is connected to the mobile object main body, and the type of resin that constitutes the planar buffering portion and the columnar buffering portion. Specific specifications of the impact buffering members of Examples 1 to 22 and Comparative Examples 1 and 2 are shown in Table 1. FIG. 8 is a perspective view showing the configuration of the impact buffering member of Comparative Example 1, which has a genuine shape. As shown in FIG. 8, the impact buffering member of Comparative Example 1 has a structure in which the portions that correspond to the upper and lower portions of the planar buffering portion in the impact buffering members of the Examples are connected by two column members that extend vertically.

[0085] [Table 1]

[0086] <Tensile stress test> As shown in Figure 1, data for each impact-absorbing member in Examples 1 to 22 and Comparative Examples 1 and 2 was prepared, in which the member was attached to the rear tip of the vehicle main body M1 of the model data for the unmanned vehicle M. The tensile stress generated when the unmanned vehicle M was dropped in direction a (the negative Z-axis direction shown in Figure 1), and the tensile stress generated when the unmanned vehicle M was dropped in direction b (the negative Y-axis direction shown in Figure 1) were calculated by computer-based simulation analysis.

[0087] The data extraction locations for tensile stress in the a direction were four: the collision area, the connection area (lower side) with the vehicle body M1, the connection area (upper side) with the vehicle body M1, and the vehicle body M1. The data extraction locations for tensile stress in the b direction were three: the collision area, the connection area with the vehicle body M1, and the vehicle body M1. Here, for the data extraction locations in the a direction, "connection area (lower side)" refers to the connection area on the collision side, and "connection area (upper side)" refers to the connection area on the anti-collision side. For the data extraction locations in the a and b directions, "collision area" refers to the part that came into contact with the ground and the area nearby. For the data in the b direction, the data shown as "connection area" is the numerical value extracted from the highest value of the four connection areas.

[0088] The specific analysis conditions for the drop impact analysis were as follows: (Analysis conditions) An impact analysis was conducted simulating the situation of being dropped and coming into contact with the ground, and the maximum principal stress generated in each impact buffer member was calculated. Structural analysis simulation software was used for the calculations. The analysis targets each impact interference member and part of the main body case, with the remaining members considered to be a concentrated mass. The ground was considered to be a rigid surface. The material properties of each impact interference member, including Young's modulus, Poisson's ratio, and density, were set according to the physical properties of the material. Young's modulus was set based on values ​​such as tensile strength provided by the manufacturer. The contact condition was contact between each impact interference member and the ground. The output condition was the maximum principal stress generated in each impact interference member. For the impact analysis, the mesh shape was either hexahedral or tetrahedral.

[0089] (Processing of analysis results) The maximum values ​​at each time were obtained from the analytical results of the maximum principal stress generated in each impact interference component. Of these maximum values, the highest value across all time points was used for evaluation.

[0090] The results are shown in Figures 9 and 10. Figure 9 is a diagram showing the simulation results of the maximum tensile stress applied to each part when an unmanned vehicle equipped with a drop shock absorber for a moving body according to the comparative example and the example is dropped in direction a. Figure 10 is a diagram showing the simulation results of the maximum tensile stress applied to each part when an unmanned vehicle equipped with a drop shock absorber for a moving body according to the comparative example and the example is dropped in direction b. Note that for Examples 2, 6, and 10, the value of the second moment of area of ​​the cross section of the wire material of the spring was set small assuming a soft spring, so an error occurred under these simulation conditions and data could not be obtained.

[0091] The results shown in Figures 9 and 10 show that the combined use of a planar buffer and a spring can significantly reduce the tensile stress applied to the vehicle body M. Furthermore, by adjusting the shape of the planar buffer and the connection angle of the spring with the vehicle body M, it is possible to effectively distribute the stress, and as a result, it is possible to achieve a maximum stress of less than 60 MPa. Furthermore, it was found that by adjusting the value of the second moment of area of ​​the cross section of the spring wire, which is a parameter for the softness of the spring, it is possible to obtain a better impact mitigation effect against impacts from multiple directions, such as the a direction and the b direction. [Industrial Applicability]

[0092] The present invention can be used as a drop shock absorbing member for absorbing the shock that occurs when an unmanned vehicle such as an unmanned exploration vehicle is dropped. [Explanation of symbols]

[0093] 1, 1A, 1B Drop shock absorbing member for mobile body, 10 Planar buffer portion, 11 Front portion, 12 Upper portion, 13 Lower portion, 14 Slit portion, 20, 20a, 20b, 20c, 20d Columnar buffer portion, 121 First upper portion, 122 Second upper portion, 131 First lower portion, 132 Second lower portion

Claims

1. a shock absorbing member for use in absorbing shock when dropped, attached to at least one of two end portions of a moving body in a vehicle central axis direction, an arch-shaped outer periphery that curves in three directions, upward, downward, and forward, so as to cover the tip end portion in a side view; and an elastically deformable planar buffer portion, in which an upper portion covering the upper direction and a lower portion covering the lower direction of the outer periphery are curved so as to cover the tip portion in a front view; a plurality of columnar buffer parts that are elastically deformable in a column axis direction and that are used to attach the planar buffer parts at a distance from the tip end part; A shock absorbing member for a moving body when dropped, comprising:

2. 2. The shock absorber for a moving body when dropped according to claim 1, wherein the columnar shock absorber has an inclination of 10 degrees or more and 60 degrees or less with respect to the vehicle central axis in a side view.

3. the planar buffer portion and the columnar buffer portion are made of a resin having a tensile modulus of elasticity of 0.1 MPa or more and 1000 GPa or less when measured according to the ISO 527-1 / -2 standard test method; When the tensile modulus of elasticity of the resin constituting the planar buffer portion is set to 1, the tensile modulus of elasticity of the resin constituting the columnar buffer portion is 10 or less. The shock-absorbing member for a moving body when dropped according to claim 1.

4. 2. The shock absorbing member for a mobile body when dropped according to claim 1, wherein said planar shock absorbing portion has a curved surface portion having a constant curvature.

5. 2. The shock absorbing member for a moving body when dropped according to claim 1, wherein said planar shock absorbing portion has a flat portion in part.

6. 2. The shock absorbing member for a mobile body when dropped according to claim 1, wherein said planar shock absorbing portion has a curved surface portion whose curvature changes continuously.

7. 2. The shock-absorbing member for a moving body when it falls, as described in claim 1, wherein the columnar buffer portion is a spring, and when the maximum distance between the upper and lower portions of the planar buffer portion is 100, the value of the second moment of area of ​​the wire cross section of the spring is 0.01 or more and 1000 or less.

8. the planar buffer portion has at least one slit portion extending in the up-down direction in a front view, The slit portion has a wide portion where the slit width is widened. The shock-absorbing member for a moving body when dropped according to claim 1.

9. 2. The shock absorbing member for a moving body when dropped according to claim 1, further comprising a ground contact portion that contacts the ground when the moving body moves along the ground.

10. 10. The shock absorbing member for a moving body when dropped according to claim 9, wherein said planar shock absorbing portion and said ground contact portion form a continuous surface.

11. 2. The shock absorber for a moving body when dropped according to claim 1, wherein said planar shock absorber and said columnar shock absorber are integrally formed.

12. 2. The impact absorbing member for a mobile body when dropped as described in claim 1, wherein the planar buffer portion is configured to have a thickness in the range of 0.5% or more and 50% or less of the maximum distance between the upper and lower parts of the planar buffer portion.

13. The shock-absorbing member for a moving body when dropped according to claim 1 , wherein the moving body is an unmanned vehicle or an extraterrestrial unmanned vehicle.

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