Folding baby stroller

Abstract

The utility model discloses a folding baby stroller which comprises four wheels, the four wheels are installed on a first undercarriage, a second undercarriage, a third undercarriage and a fourth undercarriage respectively in a matched mode, the first undercarriage and the second undercarriage are connected to a first base in a rotating mode, and the third undercarriage and the fourth undercarriage are connected to a second base in a rotating mode. A first folding mechanism is connected between the first base and the second base; the first base is rotationally connected with a first leaning frame, the second base is rotationally connected with a second leaning frame, and a second folding mechanism is connected between the first leaning frame and the second leaning frame. When folding is needed, only the first undercarriage and the second undercarriage need to be folded towards the first base, the third undercarriage and the fourth undercarriage need to be folded towards the second base, then the first base and the second base are folded together, the first folding mechanism and the second folding mechanism are contracted, the first leaning frame is folded towards the first base, and the second leaning frame is folded towards the second base. Therefore, folding and storage of the whole equipment are completed.

Description

Technical Field

[0001] The invention belongs to the field of transport vehicles, and in particular relates to a foldable infant stroller. Background Art

[0002] As a convenient parenting tool, baby strollers are widely popular among parents, especially in urban life. Modern families need a stroller that is both lightweight and easy to use, yet fully functional, to meet the needs of different scenarios, such as shopping, traveling, or outdoor activities.

[0003] There are many types of baby strollers on the market, mainly divided into two categories: folding and fixed. Folding strollers are popular because they are easy to store and carry, and are usually made of lightweight materials such as aluminum alloy and high-strength plastic to ensure that the weight is reduced as much as possible while maintaining structural strength.

[0004] The existing foldable baby strollers are relatively mature in folding and unfolding operations, and most designs can achieve quick folding and unfolding through a simple folding mechanism. For example, the patent with the announcement number CN209535179U and the invention name "A foldable stroller frame" discloses a common stroller folding structure, which unfolds like opening a book. Figure 1 As shown, it can be stored like a closed book, so the comparison of documents Figure 5 As shown, its disadvantage is that it is still very bulky after being stored.

[0005] In order to solve this problem, some baby strollers directly reduce the lateral width of the push rod to achieve the effect of reducing the volume. For example, the patent with publication number CN111204369A and invention name "A Baby Stroller" discloses such a stroller, but it sacrifices the stability of the stroller and is easy to shake left and right when pushed. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a foldable infant stroller which is spacious and stable when unfolded and compact when folded, in view of the current status of the above-mentioned prior art.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: a foldable infant stroller, including four wheels, the four wheels are matched and installed on the first landing gear, the second landing gear, the third landing gear and the fourth landing gear respectively, the first landing gear and the second landing gear are rotatably connected to the first base, the third landing gear and the fourth landing gear are rotatably connected to the second base, and a first folding mechanism is connected between the first base and the second base; the first base is rotatably connected to the first support frame, the second base is rotatably connected to the second support frame, and a second folding mechanism is connected between the first support frame and the second support frame. When folding is required, it is only necessary to fold the first landing gear and the second landing gear toward the first base, fold the third landing gear and the fourth landing gear toward the second base, and then bring the first base and the second base together, shrink the first folding mechanism and the second folding mechanism, and then fold the first support frame toward the first base, and fold the second support frame toward the second base, so as to complete the folding and storage of the entire device. The unfolded second folding mechanism serves as a backrest, and the first folding mechanism serves as a position to support the buttocks.

[0008] In a preferred solution, when the first landing gear is stored, the tilting direction of the first landing gear is toward the second landing gear, and the tilting direction of the second landing gear is toward the first landing gear; the tilting direction of the third landing gear is toward the fourth landing gear, and the tilting direction of the fourth landing gear is toward the third landing gear. When the device is folded, the first landing gear and the second landing gear are tilted toward each other, and the third landing gear and the fourth landing gear are also tilted toward each other, which can reduce the storage volume.

[0009] In a preferred embodiment, the first folding mechanism is a connecting rod folding net, that is, a connecting rod folding net composed of a plurality of short sticks connected in a staggered rotation manner, a first rotating shaft is connected between the first folding mechanism and the first base, the first base includes a first guide rail, and a first sliding member slidably arranged on the first guide rail, and a second rotating shaft is arranged between the first sliding member and the first folding mechanism;

[0010] A third rotating shaft is connected between the first folding mechanism and the second base, the second base includes a second guide rail and a second sliding member slidably arranged on the second guide rail, and a fourth rotating shaft is arranged between the second sliding member and the first folding mechanism. When the first base and the second base are brought together, the first folding mechanism will be compressed, and the edge of the first folding mechanism will extend, which will drive the first sliding member to slide on the first guide rail and also drive the second sliding member to slide on the second guide rail.

[0011] In a preferred solution, the first guide rail is columnar, and the first sliding member is an annular member sleeved on the first guide rail; the second guide rail is columnar, and the second sliding member is an annular member sleeved on the second guide rail.

[0012] In another scheme of the first folding mechanism, the first folding mechanism is a connecting rod folding net, a first rotating shaft is connected between the first folding mechanism and the first base, the first base is connected to the first short rod through the fifth rotating shaft, a sixth rotating shaft is provided between the first short rod and the first folding mechanism; a third rotating shaft is connected between the first folding mechanism and the second base, the second base is connected to the second short rod through the seventh rotating shaft, and an eighth rotating shaft is provided between the second short rod and the first folding mechanism. When the first base and the second base are brought together, the first folding mechanism will be compressed, the edge of the first folding mechanism will be extended, and the first short rod and the second short rod will be driven to swing.

[0013] In a preferred embodiment, the second folding mechanism is a connecting rod folding net, a ninth rotating shaft is connected between the second folding mechanism and the first frame, the first frame includes a third guide rail, and a third sliding member slidably arranged on the third guide rail, and a tenth rotating shaft is arranged between the third sliding member and the second folding mechanism; an eleventh rotating shaft is connected between the second folding mechanism and the second frame, the second frame includes a fourth guide rail, and a fourth sliding member slidably arranged on the fourth guide rail, and a twelfth rotating shaft is arranged between the fourth sliding member and the second folding mechanism. When the first frame and the second frame are brought together, the second folding mechanism will be compressed, the edge of the second folding mechanism will extend, and the third sliding member will slide on the third guide rail, and the fourth sliding member will slide on the fourth guide rail. When the first base and the second base are brought together, the first folding mechanism will be compressed, the edge of the first folding mechanism will extend, and the first short rod and the second short rod will swing.

[0014] In a preferred solution, the third guide rail is columnar, and the third sliding member is an annular member sleeved on the third guide rail; the fourth guide rail is columnar, and the fourth sliding member is an annular member sleeved on the fourth guide rail.

[0015] In another scheme of the second folding mechanism, the second folding mechanism is a connecting rod folding net, a ninth rotating shaft is connected between the second folding mechanism and the first frame, the first frame is connected to the third short rod through the fourteenth rotating shaft, and a fifteenth rotating shaft is provided between the third short rod and the second folding mechanism; an eleventh rotating shaft is connected between the second folding mechanism and the second frame, the second frame is connected to the fourth short rod through the sixteenth rotating shaft, and a seventeenth rotating shaft is provided between the fourth short rod and the second folding mechanism. When the first frame and the second frame are brought together, the second folding mechanism will be compressed, the edge of the second folding mechanism will be extended, and the third short rod and the fourth short rod will be driven to swing.

[0016] In a preferred solution, the first landing gear, the second landing gear, the third landing gear and the fourth landing gear are of telescopic rod type, which is convenient for retraction and storage.

[0017] In a preferred solution, the rotation shaft of the first landing gear is located directly below the first base, the rotation shaft of the second landing gear is located on the side of the first base, and the rotation shaft of the first support frame is located above the first base; the rotation shaft of the third landing gear is located directly below the second base, the rotation shaft of the third landing gear is located on the side of the second base, and the rotation shaft of the second support frame is located above the second base. This makes storage more compact.

[0018] The first folding mechanism and the second folding mechanism may also be implemented using telescopic tubes.

[0019] In summary, compared with the prior art, the solution disclosed in the present utility model can achieve large-volume deployment and small-volume storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the first embodiment of the utility model;

[0021] Figure 2 yes Figure 1 Schematic diagram of the decomposition of

[0022] Figure 3 yes Figure 2 A schematic diagram of the enlarged structure of the middle part A;

[0023] Figure 4 yes Figure 2 A schematic diagram of the enlarged structure of the middle B part;

[0024] Figure 5 It is a schematic diagram of the structure between the second base, the third landing gear, the fourth landing gear and the second support frame;

[0025] Figure 6 Yes Figure 5 A schematic diagram of the structure when the components are folded and stored;

[0026] Figure 7 It is a schematic diagram of the structure of the cooperation between the first base, the second base and the first folding mechanism in the second embodiment;

[0027] Figure 8 yes Figure 7 Schematic diagram of the decomposition of

[0028] Fig. 9 is a schematic diagram of the structure of the cooperation between the first support frame, the second support frame and the second folding mechanism of the second embodiment;

[0029] Fig.10 yes Fig. 9 Schematic diagram of the decomposition of

[0030] Fig.11 It is a schematic diagram of the structure of the cooperation between the first base, the second base and the first folding mechanism in the third embodiment;

[0031] Fig.12 It is a schematic diagram of the structure of the cooperation among the first support frame, the second support frame and the second folding mechanism in the third embodiment. DETAILED DESCRIPTION

[0032] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0033] The accompanying drawings are marked as follows: a first folding mechanism 1, a second folding mechanism 2, a first base 3, a first guide rail 31, a first sliding member 32, a second rotating shaft 321, a first rotating shaft 33, a fifth rotating shaft 34, a first short rod 35, a sixth rotating shaft 36, a second base 4, a second guide rail 41, a second sliding member 42, a fourth rotating shaft 421, a third rotating shaft 43, a seventh rotating shaft 44, a second short rod 45, an eighth rotating shaft 46, a first support frame 5, a third guide rail 51, a third sliding member 52, a tenth rotating shaft 521, a ninth rotating shaft 53, a fourteenth rotating shaft 54, a third short rod 55, a fifteenth rotating shaft 56, a second support frame 6, a fourth guide rail 61, a fourth sliding member 62, a twelfth rotating shaft 621, an eleventh rotating shaft 63, a sixteenth rotating shaft 64, a fourth short rod 65, a seventeenth rotating shaft 66, a first landing gear 71, a second landing gear 72, a third landing gear 73, and a fourth landing gear 74.

[0034] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0035] It should be noted that the term "comprising" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a product comprising a series of units is not necessarily limited to those units explicitly listed, but may include other units that are not explicitly listed or inherent to these products.

[0036] In this application, the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", etc. are based on the directions or positional relationships shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

[0037] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0038] In addition, the terms "disposed" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be directly connected, or indirectly connected through an intermediate medium, or it can be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] Embodiment 1, as Figures 1 to 6 As shown, a foldable infant stroller includes four wheels, which are matched and mounted on a first landing gear 71, a second landing gear 72, a third landing gear 73 and a fourth landing gear 74 respectively. The first landing gear 71 and the second landing gear 72 are rotatably connected to a first base 3, the third landing gear 73 and the fourth landing gear 74 are rotatably connected to a second base 4, a first folding mechanism 1 is connected between the first base 3 and the second base 4; the first base 3 is rotatably connected to a first support frame 5, the second base 4 is rotatably connected to a second support frame 6, and a second folding mechanism 2 is connected between the first support frame 5 and the second support frame 6. When folding is required, the first landing gear 71 and the second landing gear 72 are folded toward the first base 3, and the third landing gear 73 and the fourth landing gear 74 are folded toward the second base 4. Then, the first base 3 and the second base 4 are brought together, and the first folding mechanism 1 and the second folding mechanism 2 are contracted. Then, the first support frame 5 is folded toward the first base 3, and the second support frame 6 is folded toward the second base 4. The folding and storage of the entire equipment is completed.

[0041] In the embodiment, when the first landing gear 71 is stowed, the tilting direction is toward the second landing gear 72, and the tilting direction of the second landing gear 72 is toward the first landing gear 71; the tilting direction of the third landing gear 73 is toward the fourth landing gear 74, and the tilting direction of the fourth landing gear 74 is toward the third landing gear 73. When the device is folded, the first landing gear 71 and the second landing gear 72 are tilted toward each other, and the third landing gear 73 and the fourth landing gear 74 are also tilted toward each other, which can reduce the storage volume and reduce the size of the device. Figure 6 The folding directions of the third landing gear 73 and the fourth landing gear 74 can be seen in FIG.

[0042] In the embodiment, Figures 1 to 3As shown, the first folding mechanism 1 is a connecting rod folding network, that is, a connecting rod folding network composed of a plurality of short sticks connected in an intersecting rotation manner, a first rotating shaft 33 is connected between the first folding mechanism 1 and the first base 3, the first base 3 includes a first guide rail 31, and a first sliding member 32 slidably arranged on the first guide rail 31, and a second rotating shaft 321 is arranged between the first sliding member 32 and the first folding mechanism 1;

[0043] A third rotating shaft 43 is connected between the first folding mechanism 1 and the second base 4. The second base 4 includes a second guide rail 41 and a second sliding member 42 slidably disposed on the second guide rail 41. A fourth rotating shaft 421 is disposed between the second sliding member 42 and the first folding mechanism 1. When the first base 3 and the second base 4 are brought together, the first folding mechanism 1 will be compressed, and the edge of the first folding mechanism 1 will extend, which will drive the first sliding member 32 to slide on the first guide rail 31, and also drive the second sliding member 42 to slide on the second guide rail 41.

[0044] In the embodiment, Figures 1 to 3 As shown, the first guide rail 31 is columnar, and the first sliding member 32 is an annular member sleeved on the first guide rail 31 ; the second guide rail 41 is columnar, and the second sliding member 42 is an annular member sleeved on the second guide rail 41 .

[0045] In the embodiment, Figure 1 , 2 As shown in , 4, the second folding mechanism 2 is a connecting rod folding network, a ninth rotating shaft 53 is connected between the second folding mechanism 2 and the first frame 5, the first frame 5 includes a third guide rail 51, and a third sliding member 52 slidably disposed on the third guide rail 51, and a tenth rotating shaft 521 is provided between the third sliding member 52 and the second folding mechanism 2; an eleventh rotating shaft 63 is connected between the second folding mechanism 2 and the second frame 6, the second frame 6 includes a fourth guide rail 61, and a fourth sliding member 62 slidably disposed on the fourth guide rail 61, and a twelfth rotating shaft 621 is provided between the fourth sliding member 62 and the second folding mechanism 2. When the first frame 5 and the second frame 6 are brought together, the second folding mechanism 2 will be compressed, the edge of the second folding mechanism 2 will be extended, and the third sliding member 52 will be driven to slide on the third guide rail 51, and the fourth sliding member 62 will also be driven to slide on the fourth guide rail 61. When the first base 3 and the second base 4 are brought together, the first folding mechanism 1 will be compressed, and the edge of the first folding mechanism 1 will be extended, which will drive the first short rod 35 and the second short rod 45 to swing.

[0046] In the embodiment, the third guide rail 51 is columnar, and the third sliding member 52 is an annular member sleeved on the third guide rail 51 ; the fourth guide rail 61 is columnar, and the fourth sliding member 62 is an annular member sleeved on the fourth guide rail 61 .

[0047] Embodiment 2: The structure of embodiment 2 is similar to that of embodiment 1, except that the structure between the first base 3, the second base 4 and the first folding mechanism 1, and the structure between the first support frame 5, the second support frame 6 and the second folding mechanism 2 are as follows: Figure 7 , 8 As shown, the first folding mechanism 1 is a connecting rod folding network, a first rotating shaft 33 is connected between the first folding mechanism 1 and the first base 3, a first short rod 35 is connected to the first base 3 through a fifth rotating shaft 34, a sixth rotating shaft 36 is provided between the first short rod 35 and the first folding mechanism 1; a third rotating shaft 43 is connected between the first folding mechanism 1 and the second base 4, a second short rod 45 is connected to the second base 4 through a seventh rotating shaft 44, and an eighth rotating shaft 46 is provided between the second short rod 45 and the first folding mechanism 1. When the first base 3 and the second base 4 are brought together, the first folding mechanism 1 will be compressed, the edge of the first folding mechanism 1 will be extended, and the first short rod 35 and the second short rod 45 will be driven to swing.

[0048] In the embodiment, the second folding mechanism 2 is a connecting rod folding network, a ninth rotating shaft 53 is connected between the second folding mechanism 2 and the first frame 5, a third short rod 55 is connected to the first frame 5 through a fourteenth rotating shaft 54, a fourteenth rotating shaft 54 ​​is provided between the third short rod 55 and the second folding mechanism 2; an eleventh rotating shaft 63 is connected between the second folding mechanism 2 and the second frame 6, a fourth short rod 65 is connected to the second frame 6 through a sixteenth rotating shaft 64, a seventeenth rotating shaft 66 is provided between the fourth short rod 65 and the second folding mechanism 2. When the first frame 5 and the second frame 6 are brought together, the second folding mechanism 2 will be compressed, the edge of the second folding mechanism 2 will be extended, and the third short rod 55 and the fourth short rod 65 will be driven to swing.

[0049] Embodiment 3: The structure of embodiment 3 is similar to that of embodiment 1, except that the structure between the first base 3, the second base 4 and the first folding mechanism 1, and the structure between the first support frame 5, the second support frame 6 and the second folding mechanism 2 are as follows: Fig.11 and Fig.12 As shown, the first folding mechanism 1 and the second folding mechanism 2 are telescopic tubes.

[0050] In the first to third embodiments, the first landing gear 71, the second landing gear 72, the third landing gear 73 and the fourth landing gear 74 are of telescopic rod type, which is convenient for retraction and storage.

[0051] In the embodiment, the rotation axis of the first landing gear 71 is located directly below the first base 3, the rotation axis of the second landing gear 72 is located on the side of the first base 3, and the rotation axis of the first support frame 5 is located above the first base 3; the rotation axis of the third landing gear 73 is located directly below the second base 4, the rotation axis of the third landing gear 73 is located on the side of the second base 4, and the rotation axis of the second support frame 6 is located above the second base 4. In this way, it is more compact to store.

[0052] In the above three embodiments, the structures between the first base 3, the second base 4 and the first folding mechanism 1, and the structural features between the first support frame 5, the second support frame 6 and the second folding mechanism 2 can be combined with each other.

[0053] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A foldable infant stroller, comprising four wheels, characterized in that: The four wheels are respectively mounted on a first landing gear (71), a second landing gear (72), a third landing gear (73) and a fourth landing gear (74); the first landing gear (71) and the second landing gear (72) are rotatably connected to a first base (3); the third landing gear (73) and the fourth landing gear (74) are rotatably connected to a second base (4); a first folding mechanism (1) is connected between the first base (3) and the second base (4); the first base (3) is rotatably connected to a first support frame (5); the second base (4) is rotatably connected to a second support frame (6); and a second folding mechanism (2) is connected between the first support frame (5) and the second support frame (6).

2. A foldable infant stroller according to claim 1, characterized in that: When stowed, the first landing gear (71) tilts toward the second landing gear (72), and the second landing gear (72) tilts toward the first landing gear (71); the third landing gear (73) tilts toward the fourth landing gear (74), and the fourth landing gear (74) tilts toward the third landing gear (73).

3. A foldable infant stroller according to claim 2, characterized in that: The first folding mechanism (1) is a connecting rod folding net, a first rotating shaft (33) is connected between the first folding mechanism (1) and the first base (3), the first base (3) comprises a first guide rail (31), and a first sliding member (32) slidably arranged on the first guide rail (31), and a second rotating shaft (321) is arranged between the first sliding member (32) and the first folding mechanism (1); A third rotating shaft (43) is connected between the first folding mechanism (1) and the second base (4); the second base (4) comprises a second guide rail (41) and a second sliding member (42) slidably arranged on the second guide rail (41); a fourth rotating shaft (421) is arranged between the second sliding member (42) and the first folding mechanism (1).

4. A foldable infant stroller according to claim 3, characterized in that: The first guide rail (31) is columnar, and the first sliding member (32) is an annular member sleeved on the first guide rail (31); the second guide rail (41) is columnar, and the second sliding member (42) is an annular member sleeved on the second guide rail (41).

5. The foldable infant stroller according to claim 2, characterized in that: The first folding mechanism (1) is a connecting rod folding network. A first rotating shaft (33) is connected between the first folding mechanism (1) and the first base (3). The first base (3) is connected to a first short rod (35) via a fifth rotating shaft (34). A sixth rotating shaft (36) is provided between the first short rod (35) and the first folding mechanism (1). A third rotating shaft (43) is connected between the first folding mechanism (1) and the second base (4). The second base (4) is connected to a second short rod (45) via a seventh rotating shaft (44). An eighth rotating shaft (46) is provided between the second short rod (45) and the first folding mechanism (1).

6. A foldable infant stroller according to claim 2, characterized in that: The second folding mechanism (2) is a connecting rod folding network, a ninth rotating shaft (53) is connected between the second folding mechanism (2) and the first support frame (5), the first support frame (5) includes a third guide rail (51), and a third sliding member (52) slidably arranged on the third guide rail (51), and a tenth rotating shaft (521) is arranged between the third sliding member (52) and the second folding mechanism (2); an eleventh rotating shaft (63) is connected between the second folding mechanism (2) and the second support frame (6), the second support frame (6) includes a fourth guide rail (61), and a fourth sliding member (62) slidably arranged on the fourth guide rail (61), and a twelfth rotating shaft (621) is arranged between the fourth sliding member (62) and the second folding mechanism (2).

7. A foldable infant stroller according to claim 6, characterized in that: The third guide rail (51) is columnar, and the third sliding member (52) is an annular member sleeved on the third guide rail (51); the fourth guide rail (61) is columnar, and the fourth sliding member (62) is an annular member sleeved on the fourth guide rail (61).

8. The foldable infant stroller according to claim 2, characterized in that: The second folding mechanism (2) is a connecting rod folding network, a ninth rotating shaft (53) is connected between the second folding mechanism (2) and the first support frame (5), the first support frame (5) is connected to the third short rod (55) via the fourteenth rotating shaft (54), and a fourteenth rotating shaft (54) is provided between the third short rod (55) and the second folding mechanism (2); an eleventh rotating shaft (63) is connected between the second folding mechanism (2) and the second support frame (6), the second support frame (6) is connected to the fourth short rod (65) via the sixteenth rotating shaft (64), and a seventeenth rotating shaft (66) is provided between the fourth short rod (65) and the second folding mechanism (2).

9. A foldable infant stroller according to any one of claims 1 to 8, characterized in that: The first landing gear (71), the second landing gear (72), the third landing gear (73) and the fourth landing gear (74) are of telescopic rod type.

10. A foldable infant stroller according to claim 9, characterized in that: The rotating shaft of the first landing gear (71) is located directly below the first base (3), the rotating shaft of the second landing gear (72) is located on the side of the first base (3), and the rotating shaft of the first support frame (5) is located above the first base (3); the rotating shaft of the third landing gear (73) is located directly below the second base (4), the rotating shaft of the third landing gear (73) is located on the side of the second base (4), and the rotating shaft of the second support frame (6) is located above the second base (4).

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