container

Abstract

This invention discloses a technology that enables a stable stacked state even when the upper container is stacked with a lateral misalignment relative to the lower container. [Solution] The container 10A of this disclosure is provided with lower outer edge protrusions 27, 28 that protrude from the outer edge region of the lower surface. In a second stacking state in which the containers 10A are stacked with a lateral offset, the lower outer edge protrusions 27, 28 of the upper container 10A come into contact with or approach the multiple upper outer edge protrusions 17, 18 of the lower container 10A from above, thereby suppressing the tilting of the upper container 10A. Furthermore, in the first stacking state where the containers 10A are stacked straight on top of each other, the lower outer edge protrusions 27, 28 of the upper container 10A and the upper outer edge protrusions 17, 18 of the lower container 10A are offset laterally, and the upper and lower containers 10A approach each other vertically until they overlap when viewed from the side, and the lower inner protrusions 20 of the upper container 10A fit inside the multiple upper outer edge protrusions 15J, 16, 17, 18 of the lower container 10A.

Description

[[Technical Field]]

[0001] The present disclosure relates to stackable containers. [[Background Art]]

[0002] As this type of container, there has been known a container in which, when stacked, an inner bottom projection of an upper container is fitted inside an outer top projection of a lower container (see, for example, Patent Document 1). [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2024-6901 (Figure 1, Paragraph

[0085] ) [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] However, in the above-described conventional container, if the upper container is displaced laterally with respect to the lower container, the inner bottom projection of the upper container rides onto the outer top projection of the lower container, resulting in an unstable stacked state in which the upper container can tilt significantly with the outer top projection serving as a fulcrum. In response to this, the present application discloses a technique that enables a stable stacked state even when the upper container is stacked while being displaced laterally with respect to the lower container. [[Means for Solving the Problem]]

[0005] A first aspect of the present disclosure made to solve the above problems is a container having a rectangular planar shape, comprising a plurality of upper outer edge protrusions projecting from multiple positions in the outer edge region of the upper surface, and a lower inner protrusion projecting downward from the inner region of the lower surface, wherein in a first stacking state in which the containers are stacked straight, the lower inner protrusions of the upper container fit inside the plurality of upper outer edge protrusions of the lower container, and the container comprises a lower outer edge protrusion projecting from the outer edge region of the lower surface, wherein in the first stacking state, the lower outer edge protrusion is offset laterally from the first upper outer edge protrusion included in the plurality of upper outer edge protrusions and overlaps when viewed from the lateral direction, and in a second stacking state in which the containers are stacked offset laterally from the lateral direction, the container is in contact with or close to the first upper outer edge protrusion from above.

[0006] A second aspect of the present disclosure is a container having a rectangular planar shape, comprising a plurality of upper outer edge protrusions projecting from multiple positions in the outer edge region of the upper surface, and a lower inner protrusion that projects downward from the inner region of the lower surface, wherein in a first stacking state in which the containers are stacked straight on top of each other, the lower inner protrusions of the upper container fit inside the plurality of upper outer edge protrusions of the lower container, and the upper and lower outer edge regions of the container are provided with upper proximity portions and lower proximity portions that abut or come into contact vertically between the upper and lower containers in a second stacking state in which containers are stacked on top of each other with a lateral offset, wherein in the first stacking state, the upper proximity portions and lower proximity portions are arranged to be laterally offset and overlapping when viewed from the lateral direction. [Effects of the Invention]

[0007] A container according to a first aspect of this disclosure is provided with a lower outer edge projection that protrudes from the outer edge region of the lower surface. In a second stacking state in which the containers are stacked with a lateral offset, the lower outer edge projection of the upper container comes into contact with or approaches the first upper outer edge projection, which is included in the multiple upper outer edge projections of the lower container, from above, thereby suppressing the tilting of the upper container. In a first stacking state in which the containers are stacked straight, the lower outer edge projection of the upper container and the first upper outer edge projection of the lower container are offset laterally, and the upper and lower containers approach each other vertically until they overlap when viewed from the side, and the lower inner projection of the upper container fits inside the multiple upper outer edge projections of the lower container. In other words, the lower outer edge projection does not hinder the fitting of the multiple upper outer edge projections and the lower inner projection in the first stacking state. Thus, in the container of the first embodiment of this disclosure, a stable stacking state is achieved in both the first stacking state and the second stacking state.

[0008] In the second embodiment of the present disclosure, the outer edge region of the upper surface and the outer edge region of the lower surface of the container are provided with upper and lower proximity portions that come into contact or close proximity in the vertical direction between the upper and lower containers in the second stacking state, where containers are stacked on top of each other with a lateral offset, thereby suppressing tilting of the upper container in the second stacking state. Furthermore, in the first stacking state, where containers are stacked straight, the upper and lower containers approach each other vertically until the upper and lower proximity portions are laterally offset and overlap when viewed from the side, and the lower inner protrusions of the upper container fit inside the multiple upper outer edge protrusions of the lower container. In other words, the upper and lower proximity portions do not hinder the fitting of the multiple upper outer edge protrusions and lower inner protrusions in the first stacking state. Thus, the container in the second embodiment of the present disclosure achieves a stable stacking state in both the first and second stacking states. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view of the container according to the first embodiment. [Figure 2] Figure 2A is a side cross-sectional view of the upper part of the upward-facing side wall of the container, and Figure 2B is a side cross-sectional view of the upper part of the folding side wall of the container. [Figure 3] Figure 3 is a magnified perspective view of a portion of the top surface of the container. [Figure 4] Figure 4 is a perspective view of the bottom surface of the container [Figure 5] Figure 5 is an enlarged perspective view with a partial break of the bottom surface of the container [Figure 6] Figure 6 is a partially enlarged perspective view of the bottom surface of the container [Figure 7] Figure 7 is a front view of containers in a first stacked state [Figure 8] Figure 8 is a partially enlarged front view of upper and lower containers in a first stacked state [Figure 9] Figure 9 is a front view of containers in a second stacked state [Figure 10] Figure 10 is a partially enlarged front view of upper and lower containers in a second stacked state [Figure 11] Figure 11 is a cross-sectional view taken along line A-A of Figure 10 [Figure 12] Figure 12 is a perspective view of a container according to a second embodiment [Figure 13] Figure 13 is a partially enlarged plan cross-sectional view of containers in a first stacked state [Figure 14] Figure 14 is a perspective view of the bottom surface of the container [Figure 15] Figure 15 is an enlarged perspective view with a partial break of the bottom surface of the container [Figure 16] Figure 16 is a partially enlarged plan cross-sectional view of containers in a second stacked state [Figure 17] Figure 17A is a plan view of containers in a third stacked state, and Figure 17B is a plan cross-sectional view of containers in the third stacked state [Figure 18] Figure 18 is a partially enlarged plan cross-sectional view of containers in a third stacked state [Figure 19] Figure 19 is a partially enlarged perspective view of containers in a third stacked state [Figure 20] Figure 20A is a side view of containers according to a third embodiment in a first stacked state, and Figure 20B is a side view of the containers in a second stacked state MODE FOR CARRYING OUT THE INVENTION

[0010] [First Embodiment] Hereinafter, a container 10A according to the first embodiment of the present disclosure will be described with reference to FIGS. 1 to 11. As shown in FIG. 1, the container 10A is a so-called foldable container, and includes a pair of flip-up side walls and a pair of foldable side walls 14 between a lower base 11 and an upper frame 12. The planar shape of the container 10A is a rectangle having a longer longitudinal direction H2 than a lateral direction H1. The pair of flip-up side walls 13 oppose each other in the longitudinal direction H2, and their upper ends are hinge-connected to the upper frame 12. On the other hand, the pair of foldable side walls 14 oppose each other in the lateral direction H1, their upper ends and lower ends are hinge-connected to the upper frame 12 and the lower base 11 respectively, and a hinge portion 14H is provided at an intermediate portion in the vertical direction.

[0011] As shown in FIGS. 2A and 2B, the upper frame 12 has an outer side wall 12G forming an outer surface thereof, an inner side wall 12N forming an inner surface thereof, and a ceiling wall 12T connecting upper ends of the outer side wall 12G and the inner side wall 12N. The hanging amount of the inner side wall 12N from the ceiling wall 12T is smaller than that of the outer side wall 12G. The hinge portion of the flip-up side wall 13 is disposed below the inner side wall 12N, and the hinge portion at an upper part of the foldable side wall 14 is further disposed below the same.

[0012] As shown in FIG. 4, the lower base 11 has a structure in which a bank portion 11W protrudes upward from the entire outer edge of a bottom wall 11S. A lower end of the flip-up side wall 13 overlaps an inner surface of the bank portion 11W, and a lower hinge portion of the foldable side wall 14 is disposed inside the bank portion 11W. From the assembled state shown in FIG. 1, in the container 10A, the pair of flip-up side walls 13 are rotated inward and upward to be folded into the upper frame 12, and then the pair of foldable side walls 14 are folded in two so as to be accommodated between the lower base 11 and the upper frame 12, resulting in a folded state (not shown) in which the bank portion 11W of the lower base 11 and the outer side wall 12G of the upper frame 12 overlap each other in the vertical direction.

[0013] The inside of the upper frame 12 forms the top opening 10K of the container 10A (see Figure 2A), and this top opening 10K can be opened and closed by a pair of lids 15 shown in Figure 1. The pair of lids 15 are long rectangles in the vertical direction H2, and are equipped with hinges 15H on a pair of long sides of the upper frame 12 that are parallel to the vertical direction H2. The total length of the pair of lids 15 in the longitudinal direction is approximately the same as the total length of the upper frame 12 in the longitudinal direction, and when closed, both ends of the pair of lids 15 in the longitudinal direction (i.e., both ends in the vertical direction H2) overlap with the top surface of the upper frame 12. The pair of lids 15 can rotate approximately 270 degrees from the closed position. In the closed position, the pivot ends (ends opposite the pivot center) of the pair of lids 15 overlap vertically.

[0014] Furthermore, the container 10A as a whole has a symmetrical shape in both the horizontal direction H1 and the vertical direction H2, except for the part where the pair of lids 15 overlap vertically. Below, the details of each part will be described assuming that the container 10A is in its assembled state and the pair of lids 15 are in the closed state.

[0015] As shown in Figure 1, the hinge portion 15H includes a plurality of upper outer edge protrusions 16 integrally formed on the upper frame 12 and a plurality of upper outer edge protrusions 15J integrally formed on the lid 15, which are arranged in a row in the vertical direction H2. Hereafter, when distinguishing between the plurality of upper outer edge protrusions 16, the pair of upper outer edge protrusions 16 at both ends in the direction of their arrangement will be given the letter "A" at the end, and the other plurality of upper outer edge protrusions 16 will be given the letter "B" at the end.

[0016] As shown in Figure 3, the planar shape of the upper outer edge projections 16A at both ends is, for example, a shape in which a quarter circle is attached to one end in the longitudinal direction of a rectangle, and comprises a flat upper surface 16J, an inner surface 16N and an outer surface 16G, a quarter-circular arc surface 16V that is continuous with the end of the inner surface 16N that is away from the upper outer edge projection 16B, and an end surface 16W that faces the upper outer edge projection 16B. When viewed from above, the end surface 16W of the upper outer edge projection 16A has a recessed central part, and a support hole (not shown) for supporting the hinge shaft 15S of the lid 15 described below is formed in this recessed part. Furthermore, the upper outer edge projection 16B near the center has a shape in which a C-shaped arc wall 16C for supporting the hinge shaft 15S is provided on the inner surface of the projection wall 16D that rises from the outer edge of the upper frame 12. Furthermore, as shown in Figure 1, the central upper outer edge projection 16B has a block shape and has support holes (not shown) on both ends in the vertical direction H2 for supporting the hinge shaft 15S.

[0017] The central upper outer edge projection 16B and the upper outer edge projections 16A at both ends are at the same height, while the upper outer edge projection 16B closer to the center is slightly lower. Furthermore, the outer surfaces of the multiple upper outer edge projections 16 are located on the same plane (i.e., they are flush). In addition, the upper outer edge projections 16A at both ends protrude inward more than the other upper outer edge projections 16B.

[0018] Multiple upper outer edge projections 15J are arranged at multiple positions within each lid 15, sandwiched between the upper outer edge projections 16 in the vertical direction H2. As shown in Figure 3, each upper outer edge projection 15J has a cylindrical body 15E extending in the vertical direction H2 and a cylindrical body support 15F integrated with the lower part and inward-facing side of the cylindrical body 15E. A hinge shaft 15S extending axially from the cylindrical body 15E is rotatably supported by the aforementioned upper outer edge projection 16. Furthermore, the upper outer edge projection 15J is slightly lower than the multiple upper outer edge projections 16. Also, as shown in Figure 11, in the horizontal direction H1, the outward-facing side of the upper outer edge projection 15J is located slightly inward from the outer surfaces of the multiple upper outer edge projections 16, and the inward-facing side of the upper outer edge projection 15J is located at approximately the same position as the inward-facing side of the upper outer edge projections 16B, excluding both ends. Furthermore, a portion of the upper outer edge projection 16A becomes an inner projection 16T that protrudes inward from both ends of the group of projections consisting of multiple upper outer edge projections 15J, 16A, and 16B.

[0019] As shown in Figure 1, on the upper surface of the container 10A, a pair of outer edge regions parallel to the lateral direction H1 have a pair of upper edge projections 17 and a pair of upper edge projections 18 arranged in a line in the lateral direction H1 with a gap between them. The pair of upper edge projections 18 are integrally formed on the pair of lids 15 near the pivot end. The pair of lids 15 also have a pair of rectangular through holes 15A formed at a position away from the upper edge projections 18 toward the pivot center. The pair of upper edge projections 17 are integrally formed on the upper frame 12 and protrude upward from the pair of lids 15 through the pair of through holes 15A. As shown in Figure 11, both the upper edge projections 17 and 18 have a planar shape that is a rectangle elongated in the lateral direction H1, and the width in the vertical direction H2 is the same, with the upper edge projection 18 being smaller than the upper edge projection 17 in the lateral direction H1. Furthermore, as shown in Figure 3, the upper surfaces of the upper outer edge protrusions 17 and 18 are both flat, and the upper surface of the upper outer edge protrusion 17 is located above the upper outer edge protrusion 18 and is flush with the upper outer edge protrusion 16A.

[0020] As shown in Figure 4, the lower surface of the container 10A has an inner lower surface projection 20 formed by extending the inner region surrounded by the outer edge region downward from the outer edge region. More specifically, as shown in Figure 5, the inner lower surface projection 20 consists of, for example, a base projection 20G formed by slightly stepping downward the inner region of the lower surface of the bottom wall 11S, and a rib 20L formed on the entire lower surface of the base projection 20G except for the central part in the lateral direction H1. The portion where the rib 20L is not formed becomes a lower surface groove 21 extending in the vertical direction H2 at the center of the lateral direction H1 in the inner lower surface projection 20. The rib 20L also consists of a contour portion 20L1 extending along the boundary between the outer edge of the base projection 20G and the lower surface groove 21, and a grid portion 20L2 forming a grid inside the contour portion 20L1. Then, as shown in Figure 7, when the containers 10A are stacked in a straight line (hereinafter referred to as the "first stacking state"), the inner lower surface projection 20 of the upper container 10A is fitted inside the portion of the upper surface of the lower container 10A that is surrounded on all sides by the multiple upper surface outer edge projections 15J, 16, 17, 18 (see Figure 1) described above, and as shown in Figure 8, the multiple upper surface outer edge projections 16, 17 of the lower container 10A come into contact with the outer edge region of the lower surface of the upper container 10A.

[0021] As shown in Figure 4, the bottom groove 21 has a pair of stepped sections 21D located near both ends in the longitudinal direction, with a pair of wide sections 21A located towards the ends of the pair of stepped sections 21D, and a narrow section 21B in the space between the pair of stepped sections 21D. Each stepped section 21D is inclined with respect to the longitudinal direction of the bottom groove 21 and gradually widens towards the wide sections 21A. When another container 10A is stacked on top of a container 10A by shifting it laterally in the direction H1 (hereinafter referred to as the "second stacking state"), the multiple upper outer edge protrusions 15J,16 of the lower container 10A fit into the bottom groove 21 of the upper container 10A.

[0022] Specifically, as shown in Figure 9, for example, when two containers 10A are placed side by side in the lateral direction H1, and the upper container 10A is stacked on top of them, shifted by half a container width in the lateral direction H1, a second stacking state is reached, and as shown in Figure 11, a pair of protrusions (upper outer edge protrusions 15J, 16) included in a pair of hinge portions 15H adjacent to the lower pair of containers 10A fit into the lower groove portion 21 of the upper container 10A. At this time, the inner protrusions 16T at both ends of the pair of protrusions fit perfectly into the wide portion 21A of the lower groove portion 21, and the ribs 20L that constitute the particularly wide portion 21A of the lower groove portion 21 and the inner protrusions 16T of the upper outer edge protrusions 16 are approximately parallel and face each other in the lateral direction H1. Furthermore, the middle portion of the pair of protrusions, excluding both ends, fits perfectly into the narrow section 21B of the lower groove 21.

[0023] In this embodiment, the inner lower projection 20 consists of a base projection 20G that protrudes slightly downward in a stepped manner from the inner region of the lower surface of the bottom wall 11S, as described above, and a rib 20L formed on the lower surface of the base projection 20G, with the portion without the rib 20L forming the lower groove 21. However, the base projection 20G may be omitted, and the inner and outer edges of the lower surface of the bottom wall 11S may be made flush, with the portion without the rib 20L forming the lower groove 21. That is, the outer edge of the lower surface of the bottom wall 11S and the inner portion of the lower groove 21 may be made flush. However, if the base projection 20G is provided as in this embodiment, the bottom surface of the container 10A can be lowered by the amount of the base projection 20G provided, thereby increasing the inner dimensions.

[0024] As shown in Figure 4, on the outer edge region of the outer surface of the container 10A, a pair of short sides parallel to the lateral direction H1 are provided with a pair of lower outer edge protrusions 27 and a pair of lower outer edge protrusions 28 spaced apart and aligned in the lateral direction H1. As shown in Figure 6, the pair of lower outer edge protrusions 27 are formed of ribs of the same thickness as the ribs 20L included in the lower inner protrusion 20, and the lower surface of the lower outer edge protrusion 27 is flush with the lower surface of the lower inner protrusion 20. Furthermore, the planar shape of the lower outer edge protrusion 27 is a symmetrical trapezoid, and one corner where the base and hypotenuse of the trapezoid intersect is positioned to overlap with one of the four corners of the lower inner protrusion 20. Moreover, the side of the lower outer edge protrusion 27 that is away from the lower inner protrusion 20 is located slightly inward from the outer surface of the bottom wall 11S.

[0025] The pair of lower outer edge projections 28 have a shape in which a part of the bottom wall 11S is made into a square pyramidal shape and protrudes downward, with one side of each being integrated with the outer surface of the lower inner projection 20, and the opposite side being located outward from the side of the lower outer edge projection 27 and inclined in the vertical direction. Furthermore, the lower surface of the lower outer edge projection 28 is located above the lower surface of the lower outer edge projection 27, and the height difference between their lower surfaces is approximately the same as the height difference between the upper surfaces of the upper outer edge projection 17 and the upper outer edge projection 18.

[0026] Although the lower surface of the lower outer edge projection 28 is located at approximately the same height as the groove bottom surface of the lower groove 21 (the lower surface of the base projection 20G), a height difference may be provided between them. If a height difference is provided between the lower surface of the lower outer edge projection 28 and the groove bottom surface of the lower groove 21, it is preferable to provide a height difference between the upper outer edge projection 17 and the upper outer edge projection 16A so that the upper outer edge projection 16A contacts the groove bottom surface of the lower groove 21 when the second layer is stacked.

[0027] The multiple lower outer edge protrusions 27, 28 and the multiple upper outer edge protrusions 17, 18 are positioned so as not to overlap each other in the vertical direction. When the container 10A is in the first stacked state described above, as shown in Figure 8, the multiple upper outer edge protrusions 17, 18 and the multiple lower outer edge protrusions 27, 28 are positioned offset from each other in the lateral direction H1 between the upper and lower containers 10A, and overlap when viewed from the lateral direction H1. When the container 10A is in the second stacked state described above, as shown in Figure 10, the upper outer edge protrusion 17 and the lower outer edge protrusion 28 overlap and come into contact or close proximity in the vertical direction between the upper and lower containers 10A, and the upper outer edge protrusion 18 and the lower outer edge protrusion 27 overlap and come into contact or close proximity in the vertical direction.

[0028] More specifically, as shown in Figure 11, when two containers 10A are placed side by side in the lateral direction H1, if the outer surfaces that touch each other are defined as the reference outer surface K1 (in this embodiment, the outer surfaces of both ends of the upper frame 12 and the lower base 11 in the lateral direction H1), then the distance L1 from the reference outer surface K1 shown in Figure 3 to the center of the upper outer edge projection 17 in the lateral direction H1 is approximately the same as the distance L11 from the center surface K2 of the container 10A in the lateral direction H1 shown in Figure 6 to the center of the lower outer edge projection 28 in the lateral direction H1. Furthermore, although the distance L2 from the reference outer surface K1 shown in Figure 3 to the center of the lateral H1 of the upper outer edge projection 18 is different from the distance L12 from the central surface K2 shown in Figure 6 to the center of the lateral H1 of the lower outer edge projection 27, the difference between these distances ΔL (=L12-L2) is, for example, less than half of the sum of the sizes of the lateral H1 of the upper outer edge projection 18 and the lower outer edge projection 27. As a result, as described above, when the container 10A is in a second stacking state, the upper outer edge projection 17 and the lower outer edge projection 28 overlap vertically between the upper and lower containers 10A, as shown in Figure 11, and the upper outer edge projection 18 and the lower outer edge projection 27 also overlap vertically (see Figure 10).

[0029] This concludes the explanation of the configuration of the container 10A in this embodiment. Next, the effects of the container 10A will be explained. As shown in Figure 4, the container 10A in this embodiment is equipped with lower outer edge protrusions 27 and 28 that protrude from the outer edge region of the lower surface. In the second stacking state, where the containers 10A are stacked with a lateral offset H1, as shown in Figure 10, the multiple upper outer edge protrusions 15J and 16 of the lower container 10A abut approximately in the center of the upper container 10A in the lateral direction H1, and the upper outer edge protrusions 17 and 18 of the lower container 10A abut or are in close proximity to the lower outer edge protrusions 27 and 28 of the upper container 10A. This prevents the upper container 10A from tilting like a seesaw around the contact point with the multiple upper outer edge protrusions 15J and 16 of the lower container 10A. Furthermore, in the first stacking state where the containers 10A are stacked straight on top of each other, the lower outer edge projections 27, 28 of the upper container 10A and the upper outer edge projections 17, 18 of the lower container 10A are offset in the lateral direction H1, and the upper and lower containers 10A approach each other in the vertical direction until they overlap when viewed from the lateral direction H1, and the lower inner projections 20 of the upper container 10A fit inside the multiple upper outer edge projections 15J, 16, 17, 18 of the lower container 10A. In other words, the lower outer edge projections 27, 28 do not hinder the fitting of the multiple upper outer edge projections 15J, 16, 17, 18 and the lower inner projections 20 in the first stacking state. Thus, in this embodiment, the containers 10A are stable in both the first and second stacking states.

[0030] Furthermore, in the container 10A, the upper outer edge protrusions 15J,16 of the lower container 10A fit into the lower groove 21 of the upper container 10A, thus preventing the upper and lower containers 10A from shifting laterally in the second stacking direction H1. Moreover, both ends of the lower groove 21 in the longitudinal direction form widened sections 21A, and correspondingly, inner protrusions 16T are provided at both ends of the group of protrusions from the upper outer edge protrusions 15J,16, thus preventing the upper and lower containers 10A from shifting vertically in the H2 direction. In other words, in this embodiment, the upper and lower containers 10A are positioned two-dimensionally in the horizontal plane not only in the first stacking state but also in the second stacking state. Furthermore, the upper outer edge projection 17 of the lower container 10A faces the lower inner projection 20 in the vertical direction H2 below the lower outer edge projection 28 of the upper container 10A, and this also restricts the vertical displacement H2 between the upper and lower containers 10A. In other words, the upper outer edge projection 17 faces the lower inner projection 20 in the vertical direction H2 in both the first and second stacking states, and plays a role in restricting the vertical displacement H2 between the upper and lower containers 10A.

[0031] Furthermore, some of the multiple upper outer edge protrusions 15J, 16A, 16B, 17, and 18, specifically upper outer edge protrusions 16A and 17, protrude more from the upper surface of the upper frame 12 than the others, and since they are integrally formed with the upper frame 12, the load on the lid member 15 in the first stacking state is reduced. Also, although the amount of protrusion of the upper outer edge protrusions 17 and 18 from the upper surface of the container 10A differs, the amount of protrusion of the lower outer edge protrusions 27 and 28 from the lower surface of the container 10A also differs accordingly. Then, in the second stacking state, as shown in Figure 10, the upper outer edge protrusion 18 with a small protrusion and the lower outer edge protrusion 27 with a large protrusion overlap in the vertical direction, and the upper outer edge protrusion 17 with a large protrusion and the lower outer edge protrusion 28 with a small protrusion overlap in the vertical direction. In other words, according to the configuration of this embodiment, even if the protrusion amounts of the upper outer edge protrusions 17 and 18 are different, they can be used as upper outer edge protrusions to restrict the tilting of the upper container 10A in the second stacking state.

[0032] Furthermore, as a second stacking state, as shown in Figure 9, a so-called straddle stacking state is possible, in which one container 10A is stacked so as to straddle a pair of containers 10A placed side by side, and a so-called lateral offset stacking state is possible, although not shown, in which one container 10A is stacked on top of another container 10A with a lateral offset H1. In this embodiment, since the lower outer edge protrusions 27 and 28 are arranged on both the left and right sides of the lower groove 21, tilting on both the left and right sides is prevented even when the container is stacked in a straddle stacking state. In addition, since multiple lower outer edge protrusions 27 and 28 are arranged on each of the left and right sides of the lower groove 21, the load on each of the lower outer edge protrusions 27 and 28 is distributed.

[0033] Furthermore, since the lower surface of the container 10A in this embodiment has a flat surface within the lower groove 21 without ribs or the like, when performing a so-called slide stack, for example, by tilting the upper container 10A and sliding it to create a second stack, the upper outer edge protrusions 15J,16 of the lower container 10A will not catch on the flat surface of the upper container 10A, enabling smooth slide stacking.

[0034] Furthermore, as shown in Figure 5, the outward-facing side surface of the lower outer edge projection 28 is inclined and is located further outward than the outward-facing side surface of the lower outer edge projection 27. Therefore, when the upper and lower containers 10A are stacked in a second layer using a slide stack, the lower outer edge projection 28 smoothly rests on the upper outer edge projection 17 first, and then the lower outer edge projection 27 rests on the upper outer edge projection 18. An inclined surface may also be provided on the lower outer edge projection 27.

[0035] Furthermore, in the structure of this embodiment, the upper container 10A is positioned higher than the lower container 10A in the second stacking state compared to the first stacking state, resulting in a larger gap between the upper and lower containers 10A. This allows for a choice of configurations: when airtightness is desired, the containers 10A are stacked in the first stacking state; when ventilation is desired, the containers 10A are stacked in the second stacking state.

[0036] In this embodiment, the upper outer edge protrusions 17 and 18 correspond to the "first upper outer edge protrusion" in the first aspect of the present disclosure and Feature 1 below, as well as the "upper side adjacent portion" in the second aspect of the present disclosure and Feature 14 below, while the lower outer edge protrusions 27 and 28 correspond to the "lower outer edge protrusion" in the first aspect of the present disclosure and Feature 1 below, as well as the "lower side adjacent portion" in the second aspect of the present disclosure and Feature 14 below, and also correspond to the lower outer edge protrusions 27 and 28. Furthermore, the upper outer edge projection 17 corresponds to the "large upper outer edge projection" in Feature 4 below, the upper outer edge projection 18 corresponds to the "small upper outer edge projection" in Feature 4 below, the lower outer edge projection 27 corresponds to the "large lower outer edge projection" in Feature 4 below, and the lower outer edge projection 28 corresponds to the "small lower outer edge projection" in Feature 4 below.

[0037] [Second Embodiment] The container 10B of the second embodiment of this disclosure, shown in Figures 12 to 19, is the same as the container 10A of the first embodiment, but with the addition of a central upper projection 31 (see Figure 12) and additional lower outer edge projections 25, 26 (see Figure 14). Hereinafter, only the configurations that differ from the first embodiment will be described.

[0038] As shown in Figure 12, the central projection 31 on the top surface is formed at a position slightly offset toward the pivot center from the overlapping portion of the pair of lids 15. The central projection 31 on the top surface is also positioned at both ends in the longitudinal direction (vertical direction H2 of the container 10B) of the lid 15 and forms a rib structure extending in the longitudinal direction of the lid 15. Furthermore, the end faces of the central projection 31 on the top surface that face toward the center in the vertical direction H2 of the container 10B are inclined surfaces that are tilted in the vertical direction. In addition, the distance between opposing end faces of the central projections 31 on the top surface aligned in the vertical direction H2 is narrower than the total length of the inner projection 20 on the bottom surface in the horizontal direction H1 (see Figure 4). Moreover, the central projection 31 on the top surface is at the same height as or lower than the outer edge projection 18 on the top surface, regardless of whether it is the upper or lower overlapping lid 15 of the pair of lids 15. Furthermore, the spacing between adjacent upper central protrusions 31 in the lateral direction H1 is such that they fit perfectly into the wide portion 21A of the lower groove 21 (see Figure 13).

[0039] As shown in Figure 14, an additional bottom groove 22 is formed on the bottom surface of the container 10B, extending in the horizontal direction H1 at a position that bisects the container 10B in the vertical direction H2. In addition, similar to the bottom groove 21, a stepped portion 22D is formed in the additional bottom groove 22 near both ends, and both ends are widened portions 22A. Furthermore, the length and width of the widened portions 22A of the additional bottom groove 22 are the same as the length and width of the widened portion 21A of the bottom groove 21.

[0040] Additional lower surface outer edge protrusions 25 and 26 are formed on a pair of outer edge regions parallel to the vertical direction H2 on the lower surface of container 10B. As shown in Figure 15, the additional lower surface outer edge protrusion 25 has a rib structure that extends laterally in H1 from the corner of the lower surface inner protrusion 20 that is integrated with the lower surface outer edge protrusion 27. The lower surface of the additional lower surface outer edge protrusion 25 is flush with the lower surface inner protrusion 20. On the other hand, the additional lower surface outer edge protrusion 26 is positioned closer to the additional lower surface groove 22 between the additional lower surface outer edge protrusion 25 and the additional lower surface groove 22, and has a rib structure that extends laterally in H1 from the lower surface inner protrusion 20. The amount of extension of the additional lower surface outer edge protrusion 26 from the lower surface inner protrusion 20 in the later direction H1 is smaller than the amount of extension of the additional lower surface outer edge protrusion 25 from the lower surface inner protrusion 20 in the later direction H1. Furthermore, the lower surface of the additional lower outer edge projection 26 is located above the lower surfaces of the additional lower outer edge projection 25 and the lower inner projection 20, and the difference in height is approximately the same as the difference in height of the upper surfaces of the upper outer edge projections 17 and 18 (see Figure 12).

[0041] This concludes the explanation of the configuration of container 10B in this embodiment. Next, the operation and effects of container 10B will be explained. When container 10B is in the first stacked state, as shown in Figure 13, the two pairs of central upper surface protrusions 31 of the lower container 10B fit perfectly into the pair of wide sections 21A of the lower surface groove 21 of the upper container 10B. Otherwise, the first stacked state of container 10B is the same as the first stacked state of container 10A in the first embodiment.

[0042] When container 10B is in the second stacking state, as shown in Figure 16, the additional lower outer edge projection 25 comes into contact with or is close to the upper central projection 31. Otherwise, the second stacking state of container 10B is the same as the second stacking state of container 10A in the first embodiment.

[0043] Even when container 10B is in the third stacking state shown in Figure 17A, the tilting of the upper container 10B is restricted. That is, when another container 10B is placed on top of a pair of containers 10B placed side by side, rotated 90 degrees, and one of the long outer edges of the upper container 10B is placed on top of the short outer edge of the lower pair of containers 10B, and the upper container 10A is stacked so as to straddle the lower pair of containers 10B, the upper outer edge protrusions 15J,16 of the lower pair of containers 10B fit into the additional lower groove 22 of the upper container 10B, and the upper container 10B is restricted from moving in the lateral direction H1 of the lower container 10B. Furthermore, as shown in Figure 18, the upper outer edge projection 16A of the lower container 10B fits into the wide portion 22A of the additional lower groove 22, thereby restricting the upper container 10B from moving in one direction H2 of the lower container 10B. Moreover, as shown in Figure 19, the lower inner projection 20 of the upper container 10B abuts against or is close to the upper central projection 31 of the lower container 10B, the additional lower outer edge projection 25 of the upper container 10B abuts against or is close to the upper outer edge projection 18 of the lower container 10B, and the additional lower outer edge projection 26 of the upper container 10B abuts against or is close to the upper outer edge projection 17 of the lower container 10B. As a result, even in the third stacked state, the tilting of the upper container 10B is restricted, resulting in a stable stacked state.

[0044] Furthermore, when stacking the containers in a second layer using the slide stacking mechanism, the additional lower outer edge protrusion 25 of the upper container 10B rests on the upper central protrusion 31 of the lower container 10B before the lower outer edge protrusions 27 and 28 of the upper container 10B come into contact with the upper outer edge protrusions 17 and 18 of the lower container 10B, thereby suppressing the left-right tilting of the upper container 10B during sliding. In addition, since one end face of the upper central protrusion 31 is inclined, the additional lower outer edge protrusion 25 rests smoothly on the upper central protrusion 31.

[0045] Furthermore, the distance between opposing end faces of the upper central protrusions 31 aligned in the vertical direction H2 is narrower than the total length of the lower inner protrusion 20 in the horizontal direction H1 (see Figure 4). Therefore, when stacking in a third layer in a slide stack, the lower inner protrusion 20 of the upper container 10B rests on the upper central protrusion 31 of the lower container 10B at any slide position, suppressing the tilting of the upper container 10B.

[0046] [Third Embodiment] The container 10C of the third embodiment of this disclosure, shown in Figures 20A and 20B, is provided with an upper outer edge projection 32 that protrudes more upward than the upper outer edge projection 17 (see Figure 8) of the container 10A of the first embodiment. In addition, the lid 15 is provided with an upper outer edge projection 36 that is lower than the upper outer edge projection 18, in the portion adjacent to the upper outer edge projection 18 in the vertical direction H2 (direction perpendicular to the plane of the paper in Figure 20A).

[0047] On the other hand, the lower part of the container 10C is provided with a lower outer edge recess 34 that is open downwards and to the sides, located directly below the upper outer edge projection 32 of the lower base 11. In addition, the outer edge region of the lower surface of the container 10C is provided with a lower outer edge auxiliary projection 33 located directly below the upper outer edge projection 36. The lower surface of the lower outer edge auxiliary projection 33 is flush with the lower surface of the lower inner projection 20. Except for the above configuration, the container 10C is the same as the container 10A of the first embodiment.

[0048] In this embodiment, as shown in Figure 20A, when the container 10C is in the first stacking state, the upper outer edge projection 32 of the lower container 10C is received by the lower outer edge recess 34 of the upper container 10C. The upper outer edge projection 16A of the lower container 10C then abuts against the lower outer edge region of the upper container 10C, and the lower outer edge auxiliary projection 33 of the upper container 10C abuts against the upper outer edge projection 36 of the lower container 10C. Otherwise, it is the same as the first stacking state of the container 10A in the first embodiment.

[0049] Furthermore, as shown in Figure 20B, when the container 10C is in a second stacking state, the upper outer edge projection 32 of the lower container 10C abuts against or comes close to the wall portion 35 adjacent to the lower outer edge recess 34 of the lower container 10C, thereby suppressing the tilting of the upper container 10C. In addition, the lower outer edge auxiliary projection 33 is positioned adjacent to the upper outer edge projection 32, thereby restricting lateral displacement of the upper and lower containers 10C in the lateral direction H1. Aside from these points, the second stacking state is the same as that of the container 10A in the first embodiment. In the first embodiment, lateral displacement of the upper and lower containers 10A in the second stacking state was restricted by providing a bottom groove 21. However, in the third embodiment, since lateral displacement in the second stacking state is restricted by the lower outer edge auxiliary protrusion 33 and the upper outer edge protrusion 32, the bottom groove 21 is not provided, and the base protrusion 20G (see Figure 5) is made to bulge downwards significantly, thereby increasing the internal dimensions of the container 10C.

[0050] In this embodiment, the upper outer edge projection 32 corresponds to the "upper side adjacent portion" in the second aspect of the present disclosure and feature 14 below, as well as the "second upper outer edge projection" in feature 11 below, and the wall portion 35 corresponds to the "lower side adjacent portion" in the second aspect of the present disclosure and feature 14 below.

[0051] [Other embodiments] Although the containers 10A to 10C in each of the above embodiments were foldable containers, the structure of each embodiment may also be applied to a non-foldable container. Furthermore, the foldable structure of the container is not limited to the structure of the above embodiments, and may not have an upper frame 12, with the lower ends of each side wall hinged to a lower base to make it foldable.

[0052] Containers 10A to 10C were equipped with a rotatable lid 15, but they may also be equipped with a lid that can be separated from the container body. Furthermore, although the lid in the above embodiment was of a segmented design, it may also be of a single-piece design. In addition, in a container equipped with a detachable lid, all of the upper outer edge protrusions may be integrally formed with the lid, or some or all of the upper outer edge protrusions may be integrally formed with the container body and protrude upward from the lid through through holes provided in the lid.

[0053] In the above embodiment, when stacked across the upper container 10A, the upper outer edge projection 16 of the lower container 10A was in contact with the lower inner projection 20 of the upper container 10A (specifically, the bottom surface of the groove 21 of the lower groove). However, the upper outer edge projections 17, 18 and the lower outer edge projections 27, 28 may come into contact between the upper and lower containers 10A, so that the lower inner projection 20 and the upper outer edge projection 16 do not come into contact.

[0054] In the first embodiment described above, in the second stacked state, the left and right lower outer edge protrusions 27, 28 of the upper container 10A all abutted against or came close to the upper outer edge protrusions 17, 18 of the lower container 10A, preventing tilting from side to side (see Figure 10). However, a gap may be created between the upper outer edge protrusions 17, 18 and the lower outer edge protrusions 27, 28, allowing for slight tilting.

[0055] Although the containers 10A to 10C in the above embodiment had a symmetrical shape in the horizontal direction H1 and the vertical direction H2, except for the point where a part of a pair of lids 15 overlap, they may also have an asymmetrical shape. Specifically, for example, the lower outer edge projection may be located on only one side with respect to the central plane K2 (see Figure 11) in the vertical direction H2, or the shape and arrangement of the lower outer edge projection may differ on one side and the other side of the central plane K2.

[0056] In the above embodiment, containers 10A to 10C are configured such that the upper outer edge protrusions are not provided directly above the lower outer edge protrusions 27 and 28, so that when the containers are in the first stacked state, the lower outer edge protrusions 27 and 28 do not interfere with the upper outer edge protrusions. However, an upper outer edge protrusion that is low enough not to interfere even when the containers are in the first stacked state may be provided directly above the lower outer edge protrusions 27 and 28.

[0057] In the containers 10A and 10B of the first and second embodiments described above, the upper outer edge protrusion 18 (small upper outer edge protrusion) was positioned closer to the center of container 10A than the upper outer edge protrusion 17 (large upper outer edge protrusion). Conversely, the upper outer edge protrusion 17 (large upper outer edge protrusion) may be positioned closer to the center of container 10A than the upper outer edge protrusion 18 (small upper outer edge protrusion). However, in the first stacking state, it is preferable that the upper outer edge protrusion 18 (small upper outer edge protrusion), which does not receive the load of containers 10A and B, is positioned closer to the center of container 10A than the upper outer edge protrusion 17 (large upper outer edge protrusion), which receives the load of containers 10A and B.

[0058] The upper connecting protrusions that connect the upper outer edge protrusions 16, 17, and 18 may be installed in a range that does not interfere with the lower outer edge protrusions 25, 26, 27, and 28 in the first, second, and third stacking states. Alternatively, a configuration may be provided in which recesses are installed in a range that interferes with the lower outer edge protrusions 25, 26, 27, and 28 in the first, second, and third stacking states.

[0059] Similarly, the lower outer edge protrusions 25, 26, 27, and 28 may also have lower connecting protrusions that connect them to each other, placed in a range that does not interfere with the upper outer edge protrusions 16, 17, and 18 in the first, second, and third stacking states. Alternatively, a configuration may be provided in which recesses are placed in a range that interferes with the upper outer edge protrusions 16, 17, and 18 in the first, second, and third stacking states.

[0060] In the above embodiment, the lower groove portion was formed by ribs, but the base projection portion may also be formed by changing the surface angle downwards.

[0061] In the containers 10A to 10C of the above embodiment, the bottom grooves 21 and 22 were provided in such a way that they divided the inner bottom projection 20 into two equal parts at the center of the horizontal direction H1 or the vertical direction H2. However, they may be provided at a position off to one side, or multiple grooves may be provided in the horizontal direction H1 or the vertical direction H2 to divide it into three or more sections.

[0062] <Note> The following describes the features extracted from the above embodiment, showing their effects and other details as needed. For ease of understanding, the reference numerals of the corresponding specific components in the above embodiment will be indicated in parentheses as appropriate; however, these features are not limited to the specific components indicated in parentheses.

[0063] [Feature 1] A container (10A~10C) having a rectangular planar shape and comprising multiple upper outer edge protrusions (15J, 16~18, 32) protruding from multiple positions in the outer edge region of the upper surface, and an inner lower surface protrusion (20) that protrudes downward from the inner lower surface region, wherein in the first stacking state in which the containers (10A~10C) are stacked straight on top of each other, the inner lower surface protrusion (20) of the upper container (10A~10C) fits inside the multiple upper outer edge protrusions (15J, 16~18, 32) of the lower container (10A~10C), and the lower inner surface protrusion (20) of the upper container (10A~10C) protrudes from the outer edge region of the lower surface of the container (10A~10C) The container is equipped with protruding lower outer edge protrusions (27, 28), and in the first stacking state, the lower outer edge protrusions (27, 28) are offset laterally (lateral direction H1) from the first upper outer edge protrusions (17, 18) included in the plurality of upper outer edge protrusions (15J, 16, 18, 32) between the upper and lower containers (10A to 10C) and overlap when viewed from the lateral direction (lateral direction H1), and in the second stacking state in which the containers (10A to 10C) are stacked offset laterally (lateral direction H1), the containers (10A to 10C) are in contact with or close to the first upper outer edge protrusions (17, 18) from above between the upper and lower containers (10A to 10C).

[0064] The container of Feature 1 is equipped with a bottom outer edge projection that protrudes from the outer edge region of the bottom surface. In the second stacking state, where the containers are stacked with a lateral offset, the bottom outer edge projection of the upper container comes into contact with or approaches the first upper outer edge projection, which is included in the multiple upper outer edge projections of the lower container, from above, thereby suppressing the tilting of the upper container. In the first stacking state, where the containers are stacked straight, the bottom outer edge projection of the upper container and the first upper outer edge projection of the lower container are offset laterally, and the upper and lower containers approach each other vertically until they overlap when viewed from the side, and the bottom inner projection of the upper container fits inside the multiple upper outer edge projections of the lower container. In other words, the bottom outer edge projection does not hinder the fitting of the multiple upper outer edge projections and the bottom inner projection in the first stacking state. Thus, the container of Feature 1 of this disclosure maintains a stable stacked state in both the first and second stacked states.

[0065] [Feature 2] The container (10A~10C) according to Feature 1, wherein the lower outer edge protrusions (27, 28) are arranged on both sides of the lower surface of the container (10A~10C) at a position facing the outer edge region of one end in the lateral direction (lateral direction H1) of the lower container (10A~10C) in the second stacking state.

[0066] The second stacking state can be considered as a stacking state in which one container is stacked on top of another container with a lateral offset, or as a so-called straddle stacking state in which a container is stacked so as to straddle a pair of containers placed side by side. In the straddle stacking state, the upper outer edge protrusion at one lateral end of the lower pair of containers abuts against the lower surface of the upper container, causing the upper container to be in a so-called seesaw state. In contrast, in the configuration of Feature 2, the lower outer edge protrusions are positioned on both sides of the lower surface of the container at a position opposite the outer edge region of one lateral end of the lower container in the second stacking state, so that the tilting on both sides of the seesaw state is restricted and the stacking state is stabilized.

[0067] [Feature 3] The container (10A~10C) according to feature 1 or 2, wherein the lower outer edge protrusions (27, 28) are arranged at multiple positions on the lower surface of the container (10A~10C) in the second stacking state, at least one side of the position facing the outer edge region of one end of the lower container (10A~10C) in the lateral direction (lateral direction H1), and in the second stacking state, the lower outer edge protrusions (27, 28) of the upper container (10A~10C) overlap the first upper outer edge protrusions (17, 18) of the lower container (10A~10C) from above at multiple positions in the lateral direction (lateral direction H1).

[0068] In the container of Feature 3, when the upper container rests on the upper outer edge projection at one lateral end of the lower container in the second stacking state, the lower outer edge projection of the upper container overlaps from above with the first upper outer edge projection of the lower container at multiple lateral positions, thereby distributing the load.

[0069] [Feature 4] The container (10A~10C) according to feature 3, wherein the first upper outer edge protrusions (17, 18) include a small upper outer edge protrusion (18) and a large upper outer edge protrusion (17), the amount of protrusion from the upper surface of the container (10A~10C) being different in size, and the lower outer edge protrusions (27, 28) include a small lower outer edge protrusion (28) and a large lower outer edge protrusion (27), the amount of protrusion from the lower surface of the container (10A~10C) being different in size, and in the second stacked state, the small upper outer edge protrusion (18) and the large lower outer edge protrusion (27) overlap vertically between the upper and lower containers (10A~10C), and the large upper outer edge protrusion (17) and the small lower outer edge protrusion (28) overlap vertically.

[0070] The container of Feature 4 includes a small upper outer edge protrusion and a large upper outer edge protrusion, which serve as first upper outer edge protrusions with different protrusion amounts from the top surface of the container, and corresponding to these, a small lower outer edge protrusion and a large lower outer edge protrusion, which serve as lower outer edge protrusions with different protrusion amounts from the bottom surface of the container. With this configuration, even if multiple types of upper outer edge protrusions with different protrusion amounts are included, they can be used as first upper outer edge protrusions to restrict the tilting of the upper container in the second stacking state.

[0071] [Feature 5] In the first stacked state, the large upper outer edge projection (17) abuts against or is close to the upper container (10A~10C), and the small upper outer edge projection (18) faces the upper container (10A~10C) with a gap between them, as described in Feature 4 of the container (10A~10C).

[0072] When the first upper outer edge projection includes a small upper outer edge projection and a large upper outer edge projection, as shown in Feature 5, in the first stacked state, the large upper outer edge projection may be in contact with or close to the upper container, and the small upper outer edge projection may be positioned opposite the upper container with a gap between them. Alternatively, the bottom surface of the container may be made uneven so that in the first stacked state, both the large upper outer edge projection and the small upper outer edge projection are in contact with or close to the upper container. Alternatively, in the first stacked state, the small upper outer edge projection may be in contact with or close to the upper container, and the large upper outer edge projection may be positioned opposite the upper container with a gap between them.

[0073] [Feature 6] The container (10A~10C) according to feature 3, comprising an upper opening (10K) that opens the upper surface of the container (10A~10C), and a lid (15) that closes the upper opening (10K), wherein the first upper outer edge projections (17, 18) include at least one of either a lid-integrated first upper outer edge projection (18) integrally formed with the lid (15), or a lid-penetrating first upper outer edge projection (17) that protrudes upward from the opening edge of the upper opening (10K) in the container (10A~10C) and penetrates a through hole (15A) provided in the lid (15).

[0074] If the container is equipped with a lid that closes the top opening, as shown in Feature 6, the first top outer edge projection may include at least one of either a lid-integrated first top outer edge projection that is integrally formed with the lid, or a lid-penetrating first top outer edge projection that protrudes upward from the opening edge of the top opening in the container and penetrates a through hole provided in the lid, or all of the first top outer edge projection may be positioned independently of the lid.

[0075] [Feature 7] A container (10A~10C) according to any one of the features 1 to 6, wherein the lower inner projection (20) is provided with a lower groove (21) that divides it into two in the lateral direction (lateral direction H1), and in the second stacked state, the upper outer edge projections (15J, 16) of the lower container (10A~10C) are configured to fit into the lower groove (21) of the upper container (10A~10C).

[0076] In the container of Feature 7, the outer rim projection on the upper surface of the lower container fits into the groove on the lower surface of the upper container when stacked in the second layer, thus preventing the upper container from shifting laterally when stacked in the second layer.

[0077] [Feature 8] The container (10A~10C) according to feature 7, wherein both longitudinal ends of the lower groove (21) form a pair of widened portions (21A) that are stepped wider than the intermediate portion between them, and both ends of the group of protrusions consisting of the plurality of upper outer edge protrusions (15J, 16) that fit inside the lower groove in the second stacked state are provided with inner protrusions (16T) in which the portion that fits into the widened portion (21A) protrudes inward.

[0078] In the container of Feature 8, when the second stacking state is reached, the inner protrusions of the upper outer edge projection of the lower container fit into a pair of wide portions at both ends in the longitudinal direction of the lower groove portion of the upper container, and the upper container is positioned two-dimensionally in the horizontal plane when the second stacking state is reached.

[0079] [Feature 9] The container (10B) according to feature 7 or 8, wherein the planar shape of the container (10B) is a rectangle with the vertical direction (H2) being longer than the horizontal direction (horizontal direction H1), and is provided with an additional bottom groove (22) that divides the lower inner projection (20) in two in the vertical direction (H2), and in a third stacking state in which the upper container (10B) is rotated 90 degrees relative to the lower container (10B) and stacked with an offset in the horizontal direction (horizontal direction H1), the upper outer edge projection (15J,16) of the lower container (10B) is configured to fit into the additional bottom groove (22) of the upper container (10B).

[0080] According to the container configuration of Feature 9, in the third stacking state, the protruding outer edge of the upper surface of the lower container fits into the additional lower groove of the upper container, thus preventing the upper container from shifting laterally in the third stacking state.

[0081] [Feature 10] The container (10C) according to feature 9, wherein both longitudinal ends of the additional lower groove (22) form a pair of widened portions (22A) that are stepped wider than the portion between the ends, and both ends of the group of protrusions (16) consisting of a plurality of upper outer edge protrusions (16) that fit inside the additional lower groove (22) in the third stacked state are provided with inner protrusions (16T) in which the portion that fits into the widened portion (22A) protrudes inward.

[0082] In the container of Feature 10, when the container is stacked in the third layer, the inner protrusions of the outer edge projections on the upper surface of the lower container fit into a pair of wide sections at both ends of the longitudinal direction of the additional lower groove section of the upper container, and the upper container is positioned two-dimensionally in the horizontal plane when stacked in the third layer.

[0083] [Feature 11] A container (10C) having a rectangular planar shape, comprising a plurality of upper outer edge protrusions (15J, 16~18, 32) protruding from multiple positions in the outer edge region of the upper surface, and a lower inner protrusion (20) that protrudes downward from the inner region of the lower surface, wherein in a first stacking state in which the containers (10C) are stacked straight on top of each other, the lower inner protrusion (20) of the upper container (10C) fits inside the plurality of upper outer edge protrusions (15J, 16~18, 32) of the lower container (10C), A container (10C) is provided with a lower outer edge recess (34) formed by depression in the outer edge region of the lower surface of the container (10C), and a second upper outer edge projection (32) included in the plurality of upper outer edge projections (15J, 16~18, 32) that is received by the lower outer edge recess (34) of the upper container (10C) in the first stacking state, and in the second stacking state in which the containers (10C) are stacked with a lateral shift (lateral direction H1), the second upper outer edge projection (32) of the lower container (10C) abuts against or is close to the upper container (10C).

[0084] The container of Feature 11 comprises multiple upper outer edge protrusions projecting from multiple positions in the outer edge region of the upper surface, and an inner lower surface protrusion that projects downward from the inner lower surface region. In the first stacking state, where the containers are stacked straight, the inner lower surface protrusions of the upper container fit inside the multiple upper outer edge protrusions of the lower container. Furthermore, the outer edge region of the lower surface of the container has a recessed lower outer edge, and the multiple upper outer edge protrusions include a second upper outer edge protrusion that is received by the lower outer edge recess of the upper container in the first stacking state. In the second stacking state, where the containers are stacked with a lateral offset, the second upper outer edge protrusion of the lower container abuts against or comes close to the upper container. This suppresses tilting of the upper container in the second stacking state, resulting in a stable stacking state in the second stacking state.

[0085] [Feature 12] A container (10B) according to any one of features 1 to 11, wherein the outer edge region of the lower surface is provided with additional lower outer edge protrusions (25, 26), and in a third stacking state in which the upper container (10B) is rotated 90 degrees relative to the lower container (10B) and stacked with a lateral offset (lateral direction H1), the first upper outer edge protrusions (17, 18) of the lower container (10B) are in contact with or close to the additional lower outer edge protrusions (25, 26) of the upper container (10B).

[0086] In the container of Feature 12, stable stacking states are achieved in the first, second, and third stacking states, thus increasing the degree of freedom in the stacking configuration.

[0087] [Feature 13] A container (10B) according to any one of the features 1 to 12, comprising: an upper opening (10K) that leaves the upper surface of the container (10B) open; a lid (15) that closes the upper opening (10K); a lower groove (21) that divides the lower inner projection (20) into two in the lateral direction (lateral direction H1); and an upper central projection (31) positioned in the center of the upper surface of the container (10B) in the lateral direction (lateral direction H1) and projecting upward from the lid (15), wherein in the first stacked state, the upper central projection (31) of the lower container (10B) is received by the lower groove (21) of the upper container (10B); and in the second stacked state, the upper central projection (31) of the lower container (10B) abuts against or is close to the lower surface of the lower inner projection (20).

[0088] In the container of Feature 13, the second stacking state can be stabilized not only by the first upper outer rim projection but also by the upper central projection of the lid. Furthermore, in the first stacking state, the upper central projection fits into the lower groove between the upper and lower containers, so the upper central projection also has the effect of restricting lateral movement between the containers in the first stacking state.

[0089] [Feature 14] A container (10A~10C) having a rectangular planar shape and comprising multiple upper outer edge protrusions (15J, 16~18, 32) protruding from multiple positions in the outer edge region of the upper surface, and an inner lower surface protrusion (20) that protrudes downward from the inner lower surface region, wherein in a first stacking state in which the containers (10A~10C) are stacked straight on top of each other, the inner lower surface protrusion (20) of the upper container (10A~10C) fits inside the multiple upper outer edge protrusions (15J, 16~18, 32) of the lower container (10A~10C), and the container (10A~10C) In the second stacking state, where containers (10A~10C) are stacked on top of each other with a lateral offset (lateral direction H1), the outer edge region of the upper surface and the outer edge region of the lower surface are provided with upper surface proximity parts (17, 18, 32) and lower surface proximity parts (27, 28, 35) that come into contact or are close to each other in the vertical direction between the upper and lower containers (10A~10C). In the first stacking state, the upper surface proximity parts (17, 18, 32) and the lower surface proximity parts (27, 28, 35) are arranged so as to be offset in the lateral direction (lateral direction H1) and overlap when viewed from the lateral direction (lateral direction H1).

[0090] In the container of Feature 14, the outer edges of the upper and lower surfaces are provided with upper and lower proximity parts that come into contact or are close to the upper and lower containers in the second stacking state, where containers are stacked on top of each other with a lateral offset. This suppresses tilting of the upper container in the second stacking state. In the first stacking state, where containers are stacked straight, the upper and lower containers approach each other in the vertical direction until the upper and lower proximity parts are laterally offset and overlap when viewed from the side. The lower inner protrusions of the upper container fit inside the multiple upper outer edge protrusions of the lower container. In other words, the upper and lower proximity parts do not hinder the fitting of the multiple upper outer edge protrusions and lower inner protrusions in the first stacking state. Thus, the container of Feature 14 achieves a stable stacking state in both the first and second stacking states. Furthermore, the specific configuration of the adjacent section on the lower side may be as described in feature 15 below, or as described in feature 16 below.

[0091] [Feature 15] The container (10A~10C) according to feature 14, wherein the upper adjacent portions (17,18) are first upper outer edge protrusions (17,18) included in the plurality of upper outer edge protrusions (15J,16~18,32), and the lower adjacent portions (27,28) are lower outer edge protrusions (27,28) that protrude from the outer edge region of the lower surface of the container (10A~10C).

[0092] [Feature 16] The container (10C) according to feature 14, wherein a lower outer edge recess (34) is formed by depression in the outer edge region of the lower surface of the container (10C), the upper adjacent portion (32) is a second upper outer edge protrusion (32) included in the plurality of upper outer edge protrusions (15J, 16~18, 32) and is received by the lower outer edge recess (34) of the upper container (10C) in the first stacking state, and the lower adjacent portion (35) is a wall portion (35) of the container (10C) located next to the lower outer edge recess (34).

[0093] While this specification and drawings disclose specific examples of the technology included in the claims, the technology described in the claims is not limited to these specific examples, but also includes various modifications and changes to these examples, as well as parts of the examples taken individually. [Explanation of symbols]

[0094] 10A~10C container 10K top opening 15 Lid member 15J,16 Upper outer edge projection 17. Upper outer edge projection (first upper outer edge projection, upper side adjacent part, large upper outer edge projection) 18. Upper outer edge projection (first upper outer edge projection, upper side adjacent part, small upper outer edge projection) 20 Bottom inner protrusion 21 Bottom groove 21A, 22A Wide section 21D, 22D Step section 22 Additional bottom groove 25,26 Additional lower outer edge protrusion 27 Lower surface outer edge protrusion (lower surface side proximal part, large lower surface outer edge protrusion) 28 Lower surface outer edge protrusion (lower surface side proximal part, small lower surface outer edge protrusion) 31 Top center protrusion 32. Upper outer edge projection (second upper outer edge projection, upper side adjacent portion) 34 Lower outer edge recess 35 Wall (near lower side) 36. Outer edge projection on the upper surface H1 Horizontal H2 Vertical

Claims

1. A container having a rectangular planar shape, comprising multiple upper outer edge protrusions projecting from multiple positions in the outer edge region of the upper surface, and a lower inner protrusion that projects downward from the inner region of the lower surface compared to the outer edge region, In the first stacking state where the containers are stacked straight on top of each other, the inner lower surface protrusions of the upper container fit inside the multiple outer upper surface protrusions of the lower container, The container is provided with a lower outer edge projection that protrudes from the outer edge region of the lower surface, In the first stacking state, the lower outer edge projection is offset laterally from the first upper outer edge projection included in the plurality of upper outer edge projections between the upper and lower containers and overlaps when viewed from the side, and in the second stacking state in which the containers are stacked with the containers offset laterally from each other, the containers between the upper and lower containers are in contact with or close to the first upper outer edge projection from above.

2. The container according to claim 1, wherein the lower outer edge projections are arranged on both sides of the lower surface of the container at a position facing the outer edge region of one end of the lower container in the second stacking state.

3. The aforementioned lower outer edge protrusions are arranged at multiple positions on the lower surface of the container that are dispersed laterally on at least one side, with respect to the position facing the outer edge region of one end of the lower container in the second stacking state. The container according to claim 1, wherein in the second stacking state, the lower outer edge projection of the upper container overlaps the first upper outer edge projection of the lower container from above at multiple lateral positions.

4. The first upper outer edge projection includes a small upper outer edge projection and a large upper outer edge projection, the latter having different amounts of protrusion from the upper surface of the container. The aforementioned lower outer edge protrusion includes a small lower outer edge protrusion and a large lower outer edge protrusion, which differ in the amount of protrusion from the lower surface of the container. The container according to claim 3, wherein in the second stacking state, the small upper outer edge protrusion and the large lower outer edge protrusion overlap vertically between the upper and lower containers, and the large upper outer edge protrusion and the small lower outer edge protrusion overlap vertically.

5. The container according to claim 4, wherein in the first stacked state, the large upper outer edge projection abuts against or is close to the upper container, and the small upper outer edge projection faces the upper container with a gap between them.

6. The container is provided with a top opening that opens the top surface and a lid that closes the top opening. The container according to claim 3, wherein the first upper outer edge projection includes at least one of either a lid-integrated first upper outer edge projection integrally formed with the lid, or a lid-penetrating first upper outer edge projection that protrudes upward from the opening edge of the upper opening in the container and penetrates a through hole provided in the lid.

7. The lower surface inner projection is provided with a lower groove that divides it into two in the lateral direction, and in the second stacked state, the plurality of upper outer edge projections of the lower container are configured to fit into the lower groove of the upper container. The longitudinal ends of the aforementioned lower groove form a pair of wider sections that are stepped and wider than the intermediate section between them. The container according to any one of claims 1 to 6, wherein both ends of the group of protrusions consisting of a plurality of upper outer edge protrusions that fit inside the lower groove in the second stacked state are provided with inner protrusions having portions that are fitted into the wide portion that protrude inward.

8. A container having a rectangular planar shape, comprising multiple upper outer edge protrusions projecting from multiple positions in the outer edge region of the upper surface, and a lower inner protrusion that projects downward from the inner region of the lower surface compared to the outer edge region, In the first stacking state where the containers are stacked straight on top of each other, the inner lower surface protrusions of the upper container fit inside the multiple outer upper surface protrusions of the lower container, In the second stacking state, where containers are stacked on top of each other with a lateral offset, the outer edge region of the upper surface and the outer edge region of the lower surface of the container are provided with an upper-side proximity portion and a lower-side proximity portion that come into contact with or are close to the upper and lower containers in the vertical direction. The containers, in the first stacked state, are arranged such that the upper and lower adjacent portions are offset laterally and overlap when viewed from the lateral direction.

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