A lift system and a three-wheeled lawn mower

Abstract

The utility model provides a kind of height adjustment system and three-wheel lawn mower, height adjustment system includes chassis, fixing frame, first connecting piece, second connecting piece, third connecting piece, universal wheel, rear wheel assembly and adjusting assembly. First connecting piece, second connecting piece and third connecting piece are all recessed structure, and third connecting piece makes fourth shaft, second shaft, first shaft and third shaft constitute parallelogram structure. Adjusting assembly is used to synchronously adjust the relative height of universal wheel and rear wheel body and chassis. The height adjustment system improves the shear resistance and carrying capacity of first connecting piece, second connecting piece and third connecting piece, effectively avoids the problem of parallelogram structure geometric size deviation caused by stress deformation of the height adjustment system of conventional lawn mower, ensures that universal wheel and rear wheel body always keep synchronous lifting, improves the structural stability and service life of the whole machine, ensures the flatness of lawn trimming, improves work quality, reduces system failure rate, reduces maintenance cost.

Description

Technical Field

[0001] This utility model relates to the field of lawnmower technology, specifically to a height adjustment system and a three-wheeled lawnmower. Background Technology

[0002] Three-wheeled lawnmowers, with their flexible steering and stable support structure, have become essential equipment for small to medium-sized lawn mowing scenarios. The height adjustment system, as a key component determining the mowing height and work quality, directly impacts the equipment's practicality and user experience. Currently, most mainstream three-wheeled or four-wheeled lawnmowers rely on a parallelogram structure for height adjustment. The core of this structure lies in connecting various moving parts via linkages or connecting plates to ensure the synchronization of the casters and rear wheels during lifting and lowering.

[0003] In existing height adjustment systems with a parallelogram structure, the core components used to connect the shaft and the actuator often employ a single connecting rod or a thin connecting plate design. These components typically have a flat or simple rod-shaped cross-section, resulting in a small moment of inertia and weak overall rigidity, which can easily lead to instability in the parallelogram structure.

[0004] During lawnmower operation, the aforementioned components must withstand impact forces from the ground (such as crushing protruding stones or bumpy roads), driving forces during height adjustment, and lateral forces generated by the swivel wheels. Under prolonged stress, traditional connecting rods are prone to bending deformation, while thin connecting plates may undergo torsional deformation or wing plate tilting, directly compromising the geometric accuracy of the parallelogram structure. This leads to asynchronous lifting and lowering movements of the swivel wheels and rear wheels, causing chassis tilting. This instability not only easily results in uneven lawn mowing height, affecting work quality, but may also cause interference friction between moving parts, accelerating equipment wear and tear. Utility Model Content

[0005] In view of the deficiencies in the prior art, the purpose of this utility model is to provide a height adjustment system and a three-wheeled lawnmower to solve or at least alleviate one or more of the above-mentioned technical problems or other problems existing in the prior art.

[0006] To achieve the above objectives, this utility model provides a height adjustment system, including a chassis; a fixing frame disposed on the chassis, on which a first shaft and a second shaft are rotatably mounted; a first connecting member with a groove structure fixed to the first shaft, the first connecting member having two first wing plates, the two first wing plates passing through the first shaft, and a third shaft rotatably mounted on the two first wing plates; and a second connecting member with a groove structure disposed below the first connecting member, the second connecting member fixed to the second shaft, the second connecting member having two second wing plates, the two second wing plates passing through the second shaft, and a fourth shaft rotatably mounted on the two second wing plates.

[0007] A third connector with a groove structure has two third wing plates, which are respectively arranged on both sides of the first connector and the second connector. The third wing plates are rotatably fitted on the third shaft and the fourth shaft, and the fourth shaft, the second shaft, the first shaft and the third shaft form a parallelogram structure. A caster wheel is provided on the third connector. A rear wheel assembly is provided on the chassis, and the rear wheel assembly has two rear wheel bodies. An adjustment assembly is provided, which is connected to the first shaft and the rear wheel assembly respectively. The adjustment assembly is used to synchronously adjust the relative height of the caster wheel and the rear wheel bodies with respect to the chassis.

[0008] Preferably, the first connecting member includes a first web and a first connecting plate, the first web and the first connecting plate are respectively connected to two first wing plates, the first shaft is located between the first web and the first connecting plate, and the first web and the first connecting plate are respectively fixedly connected to the first shaft.

[0009] Preferably, the second connecting member includes a second web and a second connecting plate, the second web and the second connecting plate are respectively connected to two second wing plates, the second shaft is located between the second web and the second connecting plate, and the second web and the second connecting plate are respectively fixedly connected to the second shaft.

[0010] Preferably, it further includes two torsion springs, which are sleeved on the first shaft. Each torsion spring is located on the outer side of the corresponding first wing plate. One torsion arm of the torsion spring is connected to the first wing plate, and the other torsion arm of the torsion spring is connected to the fixing frame.

[0011] Preferably, it further includes two first wave washers and two second wave washers; the two first wave washers are respectively passed through the third shaft, and each first wave washer is disposed between the first wing plate and the third wing plate on the corresponding side; the two second wave washers are respectively passed through the fourth shaft, and each second wave washer is disposed between the second wing plate and the third wing plate on the corresponding side.

[0012] Preferably, the adjustment assembly includes a connecting arm, a first connecting rod, a handle, a linkage assembly, and a limiting gear plate. The connecting arm is fixed on the first shaft, and one end of the first connecting rod is hinged to the connecting arm. The handle is connected to the first connecting rod through the linkage assembly, and the two rear wheels are mounted on the linkage assembly. The handle is used to adjust the relative height of the swivel wheels and the rear wheels to the chassis. The limiting gear plate is mounted on the chassis and is used to limit the position of the handle.

[0013] Preferably, the linkage assembly includes a second link and two fourth connectors, the two fourth connectors being respectively disposed at both ends of the second link, the rear wheel being rotatably disposed on the corresponding fourth connector, the handle being disposed on one of the fourth connectors, and the first link being hinged to the other fourth connector; the rear wheel assembly includes a drive shaft, a drive assembly, and two transmission assemblies, the drive shaft being rotatably disposed on the chassis, the axis of the drive shaft not coinciding with the axis of the rear wheel, the two fourth connectors being rotatably disposed on the drive shaft, and the drive assembly being used to drive the drive shaft to rotate; each transmission assembly corresponds to one rear wheel, and the transmission assembly is drivingly connected to the drive shaft and the rear wheel.

[0014] Preferably, the third connecting member is provided with a third link, and the wheel frame of the universal wheel is provided with a fifth axle, which is rotatably mounted on the third link; the bottom end of the fifth axle is inclined toward the front of the chassis, and the angle between the axis of the fifth axle and the vertical line perpendicular to the horizontal plane is 4 to 10°.

[0015] Preferably, it further includes a locking component for locking the wheel frame of the omnidirectional wheel to prevent the wheel frame of the omnidirectional wheel from rotating relative to the third link.

[0016] This utility model also provides a three-wheeled lawnmower, including the above-mentioned height adjustment system.

[0017] The beneficial effects of this utility model are:

[0018] This utility model discloses a height adjustment system and a three-wheeled lawnmower. The structural design of the first, second, and third connecting parts enables the first connecting part to effectively resist bending and torsional deformation when subjected to radial and torsional forces from the third axis, and the second connecting part to effectively resist radial and torsional forces from the fourth axis. This improves the shear resistance and load-bearing capacity of the first, second, and third connecting parts, effectively avoiding the problem of parallelogram structure geometric dimension deviation caused by force deformation in the height adjustment system of conventional lawnmowers. It ensures that the caster wheel and the rear wheel always maintain synchronous lifting, improves the structural stability and service life of the whole machine, ensures the flatness of lawn mowing, improves the work quality, reduces the system failure rate, and reduces maintenance costs. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0020] Figure 1 This is a schematic diagram of the height adjustment system provided in an embodiment of the present invention;

[0021] Figure 2 This is a partial schematic diagram showing the mating of the third connector with the front wheel assembly;

[0022] Figure 3 A schematic diagram of the structure of the adjustment components and the rear wheel assembly;

[0023] Figure 4 This is a partial schematic diagram of the mounting bracket;

[0024] Figure 5 This is a schematic diagram of the connection between the first shaft and the first connecting rod.

[0025] Figure 6 This is a schematic diagram of the structure of the first connector and the second connector;

[0026] Figure 7 A schematic diagram of the structure of the first and second waveform washers;

[0027] Figure 8 This is a side view of the swivel wheel;

[0028] Figure 9 This is a schematic diagram of the chassis bottom structure;

[0029] Figure 10 This is a partial schematic diagram of the rear wheel assembly;

[0030] Figure 11 This is a schematic diagram of the explosion of the rear wheel structure;

[0031] Figure 12 This is a schematic diagram of the structure of the gear and gear ring meshing;

[0032] Figure label:

[0033] 10. Chassis; 20. Fixing frame; 21. First axle; 22. Second axle; 30. First connecting piece; 31. First wing plate; 32. Third axle; 33. First web plate; 34. First connecting plate; 40. Second connecting piece; 41. Second wing plate; 42. Fourth axle; 43. Second web plate; 44. Second connecting plate; 50. Third connecting piece; 51. Third wing plate; 52. Third link; 60. Caster wheel; 61. Fifth axle; 70. Rear wheel assembly; 71. Rear wheel body; 72. Drive shaft; 73. Drive assembly; 74. Gear; 75. Gear ring; 80. Adjustment assembly; 81. Connecting arm; 82. First link; 83. Handle; 84. Second link; 85. Fourth connecting piece; 86. Limiting gear plate; 91. Torsion spring; 92. First wave washer; 93. Second wave washer; 94. Locking assembly. Detailed Implementation

[0034] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0035] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this utility model pertains.

[0036] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0037] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly defined.

[0038] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0039] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] like Figure 1-12 As shown, in one embodiment of this utility model, a height adjustment system is provided, including a chassis 10, a fixing frame 20, a first connecting member 30, a second connecting member 40, a third connecting member 50, casters 60, a rear wheel assembly 70, and an adjustment component 80. The chassis 10 serves as the basic support component of the entire height adjustment system, ensuring the stability of the overall structure. The fixing frame 20 is fixedly installed on the chassis 10, and its function is to provide rotational support for the first shaft 21 and the second shaft 22. The first connecting member 30 is similar to a channel steel structure and is fixedly installed on the first shaft 21. The first connecting member 30 has two parallel first wing plates 31, which pass through the first shaft 21. A third shaft 32 is rotatably mounted on the two first wing plates 31. The second connector 40 is similar to a channel steel structure and is located below the first connector 30. The second connector 40 is fixed on the second shaft 22. The second connector 40 has two parallel second wing plates 41, which are inserted through the second shaft 22. A fourth shaft 42 is rotatably mounted on the two second wing plates 41. The axes of the fourth shaft 42, the third shaft 32, the second shaft 22, and the first shaft 21 are parallel to each other.

[0041] The third connecting member 50 is also similar to a channel steel structure. The third connecting member 50 has two parallelly arranged third wing plates 51, which are respectively arranged on both sides of the first connecting member 30 and the second connecting member 40. The third wing plates 51 are rotatably fitted onto the third shaft 32 and the fourth shaft 42, forming a parallelogram structure with the fourth shaft 42, the second shaft 22, the first shaft 21, and the third shaft 32. The universal wheel 60 serves as the front wheel and is mounted on the third connecting member 50. The universal wheel 60 changes its relative height to the chassis 10 as the third connecting member 50 rises and falls, simultaneously enabling flexible steering of the lawnmower. The rear wheel assembly 70 is mounted on the chassis 10, providing the main driving power support for the lawnmower. The rear wheel assembly 70 has two rear wheel bodies 71. The adjusting component 80 is connected to the first shaft 21 and the rear wheel assembly 70, and is used to synchronously adjust the relative height of the universal wheel 60 and the rear wheel bodies 71 to the chassis 10.

[0042] The height adjustment system disclosed in this embodiment features a structural design of the first connector 30, the second connector 40, and the third connector 50. This design enables the first connector 30 to effectively resist bending and torsional deformation when subjected to radial and torsional forces from the third shaft 32, and the second connector 40 to effectively resist radial and torsional forces from the fourth shaft 42. This enhances the shear resistance and load-bearing capacity of the first connector 30, the second connector 40, and the third connector 50, effectively avoiding the problem of parallelogram structure geometric dimension deviation caused by force deformation in conventional lawnmower height adjustment systems. It ensures that the caster wheel 60 and the rear wheel body 71 always maintain synchronous lifting and lowering, improving the structural stability and service life of the entire machine, guaranteeing the flatness of lawn mowing, improving work quality, reducing the system failure rate, and reducing maintenance costs.

[0043] In one embodiment, the first connector 30 includes a first web 33 and a first connecting plate 34, the first web 33 and the first connecting plate 34 being fixedly connected to two first wing plates 31 respectively, and a first shaft 21 being located between the first web 33 and the first connecting plate 34, the first web 33 and the first connecting plate 34 being fixedly connected to the first shaft 21 respectively.

[0044] The first connecting member 30 is a closed frame structure consisting of two first wing plates 31, a first web plate 33, and a first connecting plate 34. This structural design enables the first connecting member 30 to effectively resist bending and torsional deformation when subjected to radial and torsional forces from the third shaft 32. When the adjusting assembly 80 drives the first shaft 21 to rotate the first connecting member 30, thereby causing the third shaft 32 to lift the third connecting member 50, the first connecting member 30 will not tilt due to force or the first wing plate 31 will not dent due to force. This ensures that the third shaft 32 always remains in the preset axial direction parallel to the first shaft 21, providing reliable support for the stable movement of the parallelogram structure.

[0045] Meanwhile, the first web plate 33 and the first connecting plate 34 wrap around the first shaft 21 in the middle and fix it to it. This multi-point fixing method, compared with the traditional connecting rod that is only connected to the shaft through a single hole, greatly improves the connection strength and coaxiality between the first connecting piece 30 and the first shaft 21, and avoids the problem of the first connecting piece 30 shifting relative to the first shaft 21 due to loose connection, thereby destroying the synchronization of the parallelogram structure.

[0046] In one embodiment, the second connector 40 includes a second web plate 43 and a second connecting plate 44, the second web plate 43 and the second connecting plate 44 being fixedly connected to two second wing plates 41 respectively, and the second shaft 22 being located between the second web plate 43 and the second connecting plate 44, the second web plate 43 and the second connecting plate 44 being fixedly connected to the second shaft 22 respectively.

[0047] Similarly, the technical effect of the second connector 40 is similar to that of the first connector 30. Located below the first connector 30, the second connector 40 must withstand the vertical load transmitted by the third connector 50 and the lateral force of the fourth shaft 42 during the movement of the parallelogram structure. The grooved structure, similar to a channel steel, gives the second connector 40 excellent shear resistance and load-bearing capacity. The two second flanges 41 can evenly distribute the force transmitted by the fourth shaft 42, preventing localized stress concentration that could damage the second connector 40.

[0048] When the caster wheel 60 contacts an uneven surface and generates an upward impact force, this impact force is transmitted to the second connector 40 through the third connector 50 and the fourth shaft 42. The groove structure of the second connector 40 can quickly disperse the impact force to the second web plate 43, the second connecting plate 44, and the second shaft 22, and then the second shaft 22 transmits it to the fixed frame 20 and the chassis 10, effectively buffering the impact on the entire height adjustment system. At the same time, the fixed connection structure between the second web plate 43, the second connecting plate 44, and the second shaft 22 ensures that the second connector 40 will not slip or wobble when rotating synchronously with the second shaft 22, ensuring that the distance between the fourth shaft 42 and the second shaft 22 remains constant. Together with the first shaft 21 and the third shaft 32, it maintains the geometric accuracy of the parallelogram structure, thereby achieving precise synchronous lifting and lowering of the caster wheel 60 and the rear wheel body 71.

[0049] In one embodiment, the height adjustment system further includes two torsion springs 91, which are sleeved on the first shaft 21. Each torsion spring 91 is located on the outer side of the corresponding first wing plate 31. One torsion arm of the torsion spring 91 is connected to the first wing plate 31, and the other torsion arm is connected to the fixing frame 20. The torsion springs 91 can provide a certain elastic restoring force for the first connecting member 30, reducing the operating force required by the operator during the adjustment of the adjusting assembly 80. At the same time, they can play a certain buffering role when the system is subjected to vibration or impact, thereby protecting the components from damage.

[0050] In one embodiment, the height adjustment system further includes two first wave-shaped washers 92 and two second wave-shaped washers 93. The two first wave-shaped washers 92 are respectively mounted on the third shaft 32, with each first wave-shaped washer 92 positioned between the first wing plate 31 and the third wing plate 51 on a corresponding side. The two second wave-shaped washers 93 are respectively mounted on the fourth shaft 42, with each second wave-shaped washer 93 positioned between the second wing plate 41 and the third wing plate 51 on a corresponding side. The wave-shaped washers have good elasticity and shock absorption properties, effectively eliminating gaps between the first wing plate 31 and the third wing plate 51, and between the second wing plate 41 and the third wing plate 51, reducing wear on the components during relative movement. Simultaneously, they also serve to prevent loosening, ensuring connection reliability and improving the overall stability and service life of the system.

[0051] In one embodiment, the adjustment assembly 80 includes a connecting arm 81, a first connecting rod 82, a handle 83, a linkage assembly, and a limiting gear 86. The connecting arm 81 is fixed to the first shaft 21, and one end of the first connecting rod 82 is hinged to the connecting arm 81. The handle 83 is connected to the first connecting rod 82 via the linkage assembly and is used to adjust the relative height of the swivel wheel 60 and the rear wheel 71 with respect to the chassis 10. The limiting gear 86 is mounted on the chassis 10 and is used to limit the position of the handle 83.

[0052] Specifically, the linkage assembly includes a second connecting rod 84 and two fourth connecting members 85. The two fourth connecting members 85 are respectively located at both ends of the second connecting rod 84. The rear wheel body 71 is rotatably mounted on the corresponding fourth connecting member 85. The handle 83 is mounted on one of the fourth connecting members 85. The first connecting rod 82 is hinged to the other fourth connecting member 85. The rear wheel assembly 70 includes a drive shaft 72, a drive assembly 73, and two transmission assemblies. The drive shaft 72 is mounted on the chassis 10 via two bearings. The axis of the drive shaft 72 does not coincide with the axis of the rear wheel body 71. The two fourth connecting members 85 are rotatably mounted on the drive shaft 72. The drive assembly 73 is used to drive the drive shaft 72 to rotate. The drive assembly 73 is prior art and will not be described in detail in this embodiment.

[0053] Each transmission assembly corresponds to a rear wheel body 71. The transmission assembly drives the drive shaft 72 and the rear wheel body 71. The rear wheel body 71 includes a wheel cover and a wheel body body. The wheel cover is rotatably mounted on the fourth connecting member 85, and the wheel body body is rotatably fitted onto the wheel cover. The transmission assembly includes a gear 74 and a gear ring 75. The gear 74 is fixed to one end of the drive shaft 72, and the gear ring 75 is installed in the inner ring of the wheel body body and meshes with the gear 74.

[0054] By rotating the handle 83, the operator can sequentially move the first connecting rod 82, the connecting arm 81, the second connecting rod 84, and the two fourth connecting parts 85, thereby driving the first shaft 21 to rotate. The rotation of the first shaft 21 will drive the caster wheel 60 to rise and fall through the first connecting part 30, the third connecting part 50, and other components. At the same time, the two fourth connecting parts 85 will drive the rear wheel body 71 to rotate around the axis of the drive shaft 72, realizing the raising and lowering of the rear wheel body 71, ultimately achieving the purpose of synchronous height adjustment of the caster wheel 60 and the rear wheel body 71. When the handle 83 is adjusted to the appropriate position, the limiting gear plate 86 can fix the handle 83 to prevent the handle 83 from shifting due to vibration or other factors during operation, ensuring the stability of the height of the caster wheel 60 and the rear wheel body 71.

[0055] In one embodiment, a third connecting rod 52 is fixed to the third connecting member 50, and a fifth axle 61 is provided on the wheel frame of the caster wheel 60. The fifth axle 61 is rotatably mounted on the third connecting rod 52, allowing the caster wheel 60 to flexibly turn around the fifth axle 61. The bottom end of the fifth axle 61 is inclined towards the front of the chassis 10, and the angle between the axis of the fifth axle 61 and the vertical line perpendicular to the horizontal plane is 4 to 10° (preferably 5° in this embodiment, see reference). Figure 8 The appropriate tilt of the fifth axle 61 can increase the distance between the wheel body of the universal wheel 60 and the web of the third connecting member 50, thereby preventing interference between the third connecting member 50 and the wheel body of the universal wheel 60 after deformation.

[0056] In one embodiment, the height adjustment system further includes a locking component 94 for locking the wheel frame of the caster wheel 60 to prevent the wheel frame of the caster wheel 60 from rotating relative to the third link 52. When the lawnmower needs to travel in a straight line, the locking component 94 can fix the caster wheel 60 to ensure the straightness of the machine's working path. The locking component 94 is prior art and will not be described in detail in this embodiment.

[0057] This embodiment also provides a three-wheeled lawnmower, including the aforementioned height adjustment system. Because it employs the aforementioned height adjustment system, it has the same working principle and technical effects as the height adjustment system in the above embodiments, and will not be described again here.

[0058] Numerous specific details are set forth in this specification. However, it will be understood that embodiments of this invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. A height adjustment system, characterized in that, include: Chassis (10); A fixing frame (20) is mounted on the chassis (10), and a first shaft (21) and a second shaft (22) are rotatably mounted on the fixing frame (20); A first connector (30) with a groove structure is fixed on the first shaft (21). The first connector (30) has two first wing plates (31). The two first wing plates (31) are inserted through the first shaft (21). A third shaft (32) is rotatably mounted on the two first wing plates (31). A second connector (40) with a groove structure is provided below the first connector (30). The second connector (40) is fixed on the second shaft (22). The second connector (40) has two second wing plates (41). The two second wing plates (41) are inserted through the second shaft (22). A fourth shaft (42) is rotatably provided on the two second wing plates (41). The third connector (50) with a groove structure has two third wing plates (51). The two third wing plates (51) are respectively arranged on both sides of the first connector (30) and the second connector (40). The third wing plates (51) are rotatably fitted on the third shaft (32) and the fourth shaft (42), and the fourth shaft (42), the second shaft (22), the first shaft (21) and the third shaft (32) form a parallelogram structure. The caster wheel (60) is provided on the third connector (50); A rear wheel assembly (70) is provided on the chassis (10), the rear wheel assembly (70) having two rear wheel bodies (71); as well as An adjustment assembly (80) is connected to the first shaft (21) and the rear wheel assembly (70) respectively. The adjustment assembly (80) is used to synchronously adjust the relative height of the omnidirectional wheel (60) and the rear wheel body (71) with the chassis (10).

2. The height adjustment system according to claim 1, characterized in that, The first connector (30) includes a first web plate (33) and a first connecting plate (34). The first web plate (33) and the first connecting plate (34) are respectively connected to two first wing plates (31). The first shaft (21) is located between the first web plate (33) and the first connecting plate (34). The first web plate (33) and the first connecting plate (34) are respectively fixedly connected to the first shaft (21).

3. The height adjustment system according to claim 1, characterized in that, The second connecting member (40) includes a second web plate (43) and a second connecting plate (44). The second web plate (43) and the second connecting plate (44) are respectively connected to two second wing plates (41). The second shaft (22) is located between the second web plate (43) and the second connecting plate (44). The second web plate (43) and the second connecting plate (44) are respectively fixedly connected to the second shaft (22).

4. The height adjustment system according to claim 1, characterized in that, It also includes two torsion springs (91), which are sleeved on the first shaft (21). Each torsion spring (91) is located on the outside of the corresponding first wing plate (31). One torsion arm of the torsion spring (91) is connected to the first wing plate (31), and the other torsion arm of the torsion spring (91) is connected to the fixing frame (20).

5. The height adjustment system according to claim 1, characterized in that, It also includes two first wave washers (92) and two second wave washers (93); the two first wave washers (92) are respectively passed through the third shaft (32), and each first wave washer (92) is disposed between the first wing plate (31) and the third wing plate (51) on the corresponding side; the two second wave washers (93) are respectively passed through the fourth shaft (42), and each second wave washer (93) is disposed between the second wing plate (41) and the third wing plate (51) on the corresponding side.

6. The height adjustment system according to claim 1, characterized in that, The adjustment assembly (80) includes a connecting arm (81), a first connecting rod (82), a handle (83), a linkage assembly, and a limiting gear plate (86). The connecting arm (81) is fixed on the first shaft (21), and one end of the first connecting rod (82) is hinged to the connecting arm (81). The handle (83) is connected to the first connecting rod (82) through the linkage assembly. The two rear wheel bodies (71) are mounted on the linkage assembly. The handle (83) is used to adjust the relative height of the universal wheel (60) and the rear wheel bodies (71) with respect to the chassis (10). The limiting gear plate (86) is mounted on the chassis (10). The limiting gear plate (86) is used to limit the position of the handle (83).

7. The height adjustment system according to claim 6, characterized in that, The linkage assembly includes a second link (84) and two fourth connectors (85). The two fourth connectors (85) are respectively located at both ends of the second link (84). The rear wheel body (71) is rotatably mounted on the corresponding fourth connector (85). The handle (83) is mounted on one of the fourth connectors (85). The first link (82) is hinged to the other fourth connector (85). The rear wheel assembly (70) includes a drive shaft (72), a drive assembly (73), and two transmission assemblies. The drive shaft (72) is rotatably mounted on the chassis (10). The axis of the drive shaft (72) does not coincide with the axis of the rear wheel body (71). Two fourth connecting members (85) are rotatably mounted on the drive shaft (72). The drive assembly (73) is used to drive the drive shaft (72) to rotate. Each transmission assembly corresponds to one rear wheel body (71). The transmission assembly drives the drive shaft (72) and the rear wheel body (71).

8. The height adjustment system according to claim 1, characterized in that, The third connecting member (50) is provided with a third connecting rod (52), and the wheel frame of the universal wheel (60) is provided with a fifth axle (61), which is rotatably mounted on the third connecting rod (52); The bottom end of the fifth shaft (61) is inclined toward the front of the chassis (10), and the angle between the axis of the fifth shaft (61) and the vertical line perpendicular to the horizontal plane is 4 to 10°.

9. The height adjustment system according to claim 8, characterized in that, It also includes a locking component (94) for locking the wheel frame of the caster wheel (60) to prevent the wheel frame of the caster wheel (60) from rotating relative to the third link (52).

10. A three-wheeled lawnmower, characterized in that, The height adjustment system includes any one of claims 1-9.

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