Grass mower capable of adjusting grass mowing height

Abstract

The utility model discloses a grass mower capable of adjusting the grass mowing height. The problem that in the prior art, grass mowing equipment cannot adjust the grass mowing height is solved. The grass mower capable of adjusting the grass mowing height comprises a main machine and a walking wheel, the walking wheel is installed on the rear portion of the main machine to support one end of the main machine, a grass mowing assembly is arranged on the front portion of the main machine, the grass mower further comprises a cam installed on the main machine in a rotating mode, the cam is supported between the ground and the main machine, and the cam is connected with the main machine. The cam can rotate to adjust the supporting height of the cam to the main machine, the cam has the tendency of rotating in the first direction when the grass mower advances, a self-locking mechanism is arranged between the main machine and the cam, and the self-locking mechanism limits rotation of the cam in the first direction when the grass mower advances. The grass mowing height is adjusted through the cam, the cam and the self-locking mechanism are matched to lock the grass mowing height when the grass mower advances, and the grass mowing requirements of users for different lawns are met.

Description

TECHNICAL FIELD

[0001] The utility model relates to a grass cutter field especially adjustable grass cutting height's grass cutter. BACKGROUND

[0002] With the development of society, people's entertainment way also more and more diversification, corresponding to the need of lawn sports ground is more and more big, or the number of courtyard lawn is more and more, with it gave birth to a lot of lawn maintenance machines, such as grass trimmer, mower etc., the purpose is all to the grass for pruning.But the above machine of usually all cannot pass through the machine itself to adjust, to realize people's demand for different height lawn, they use these machines often only pruning machine sets the lawn of unchangeable height.

[0003] The technical personnel of the prior art urgently need a grass cutter with adjustable grass cutting height, so that users can adjust the cutting height of the machine to cut lawns of different heights to meet the needs of users for lawns of different heights. CONTENT OF THE UTILITY MODEL

[0004] The utility model solves the technical problem that the prior art lacks and proposes a grass cutter with adjustable grass cutting height to solve the problem that the grass cutting equipment in the prior art cannot adjust the grass cutting height.

[0005] In order to realize the above technical target, the utility model provides a grass cutter with adjustable grass cutting height, which comprises a host computer and a walking wheel, the walking wheel is installed at the rear of the host computer to support one end of the host computer, the front part of the host computer is provided with a grass cutting assembly, further comprising a cam rotatingly installed on the host computer, the cam is supported between the ground and the host computer, the cam can rotate to adjust the support height of the cam to the host computer, when the grass cutter advances, the cam has a tendency to rotate in a first direction, a self-locking mechanism is arranged between the host computer and the cam, and the self-locking mechanism limits the rotation of the cam in the first direction when the grass cutter advances.

[0006] The grass cutter of the utility model realizes the adjustment and locking of the grass cutting height of the grass cutter through the cooperation of the cam and the self-locking mechanism, and meets the needs of users for different grass cutting heights of different lawns and the stability of the grass cutting height when the grass cutter cuts grass.

[0007] As a preferred, when the cam rotates in a second direction opposite to the first direction, the self-locking mechanism releases the rotation restriction of the cam.

[0008] By adopting the foregoing technical scheme, on the one hand, the structure of the self-locking mechanism is simplified, and the cost of the self-locking mechanism is reduced, on the other hand, the rotation of the cam in the second direction is not easily restricted, and the convenience of the operator in adjusting the grass cutting height is improved.

[0009] As a preferred, the rotation driving of the cam in the second direction is from the backward movement of the mower or external driving force.

[0010] The foregoing technical solutions make the user not need to touch or approach the mower blade when adjusting the mowing height, reduce the risk of the user's hand being cut by the blade, and improve the safety of the mower.

[0011] As a preferred, the self-locking mechanism comprises a first ratchet gear arranged on the cam and a second ratchet gear arranged on the main machine, at least one of the first ratchet gear and the second ratchet gear is provided with a plurality of,

[0012] The rotation of the first ratchet gear in the first direction radially engages or axially engages the second ratchet gear radially or axially.

[0013] The rotation of the first ratchet gear in the first direction, at least one of the first ratchet gear and the second ratchet gear can be deformed or displaced, or at least one of the cam or the main machine can be deformed or displaced, so that the first ratchet gear slides relative to the second ratchet gear.

[0014] The foregoing technical solutions realize one-way transmission of the self-locking mechanism through cooperation of the first ratchet gear and the second ratchet gear, further simplify the structure of the self-locking mechanism, and reduce the cost of the mower.

[0015] As a preferred, one of the first ratchet gear and the second ratchet gear is provided with an abutting groove, and the other of the first ratchet gear and the second ratchet gear is coupled in the abutting groove in the forward movement state of the mower.

[0016] The foregoing technical solutions increase the contact area of engagement between the first ratchet gear and the second ratchet gear by providing the abutting groove, and at the same time, the abutting groove can limit the lateral sliding of the first ratchet gear and the second ratchet gear, so that the first ratchet gear and the second ratchet gear can abut more stably, and the reliability of the self-locking mechanism is improved.

[0017] As a preferred, the self-locking mechanism comprises a transmission member, the transmission member is driven by the motor to drive the rotation of the cam, and the transmission member is self-locked to limit the bidirectional rotation of the cam.

[0018] The foregoing technical solutions make the operator not need to manually rotate the cam, so that the mowing height of the mower is adjusted more conveniently, and the self-locking of the transmission member makes the forward movement or the backward movement of the mower not change the mowing height, which meets the different mowing height requirements of the user for different lawns and further ensures the consistency of the mowing height.

[0019] As preferred, the transmission member comprises a worm gear and a worm, the worm is rotatably mounted on the main machine, the cam is coaxial with the worm, and the motor is connected with the worm gear.

[0020] By the transmission adjustment of the worm gear and the worm, the support height of the cam to the main machine is adjusted, the bidirectional rotation of the cam 200 can realize the adjustment of the mowing height, and the convenience of the mowing height adjustment is improved.

[0021] As preferred, the hand-held rod is further provided with a control module connected with the motor, the motor can rotate forward or reversely, and the control module controls the operation of the motor.

[0022] By the above technical scheme, the convenience of the mowing height adjustment is further improved.

[0023] As preferred, the cam is provided with two, the two cams are arranged on the left and right sides of the main machine, a connecting shaft is arranged between the two cams, and the cam rotates with the connecting shaft.

[0024] By the above technical scheme, the two cams are arranged, so that the cam can stably support one end of the main machine, the consistency of the mowing height of the mower is improved, the rotation of the two cams makes the adjustment of the mowing height more convenient, and the operation convenience of the operator is improved.

[0025] As preferred, the cam is in an elliptical shape, and the rotation axis of the cam is the center point of the elliptical shape.

[0026] By the above technical scheme, the cam is arranged in an elliptical shape, so that the cam has two maximum extreme points with the largest ground distance and two minimum extreme points with the smallest ground distance, and the cam can be switched between the two extreme points of the support position with the ground in one rotation, so that the rotation angle of the cam required for adjusting the mowing height of the mower is reduced, and the operation time is reduced.

[0027] These features and advantages of the present application will be described in detail in the following specific embodiments and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a schematic view of a mower in the embodiments of the present application;

[0029] Figure 2 FIG. 2 is an exploded view of the mower in the embodiments of the present application;

[0030] Figure 3 FIG. 3 is a schematic view of the cam in the embodiments of the present application; Figure 2 FIG. 4 is an enlarged view of position A in FIG. 3;

[0031] Figure 4The utility model discloses a front view of the lawn mower in the embodiment of the utility model,

[0032] Figure 5 The utility model discloses a schematic view that the first convex rib and the second convex rib abut in the embodiment of the utility model,

[0033] Figure 6 The utility model discloses a schematic view that the first convex rib and the second convex rib slide relative to each other in the embodiment of the utility model,

[0034] Figure 7 The utility model discloses a schematic view of the ratchet wheel and the pawl in the embodiment of the utility model,

[0035] Figure 8 The utility model discloses another schematic view of the ratchet wheel and the pawl in the embodiment of the utility model,

[0036] Reference signs:

[0037] 100, main machine, 110, blade seat, 111, cavity, 120, grass cutting assembly,

[0038] 200, cam, 210, connecting shaft, 211, operation part,

[0039] 300, walking wheel,

[0040] 400, hand-held rod,

[0041] 500, self-locking mechanism, 510, ratchet wheel, 511, first ratchet tooth, 512, jointable part, 513, non-jointable part, 520, pawl, 521, second ratchet tooth, 522, abutment groove. DETAILED DESCRIPTION

[0042] The technical scheme of the embodiment of the utility model will be explained and described below in combination with the drawings of the embodiment of the utility model, but the following embodiment is only the preferred embodiment of the utility model, not all. Based on the embodiment in the embodiment, other embodiments obtained by the person skilled in the art without making creative labor all belong to the protection scope of the utility model.

[0043] In the description of the utility model, it is understood that the orientation or position relation indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise" and the like is the orientation or position relation shown based on the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model.

[0044] Furthermore, the terms "first" and "second" 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" or "several" means two or more, unless otherwise expressly defined.

[0045] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of 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.

[0046] like Figures 1 to 4 As shown in the embodiment of this utility model, an adjustable lawnmower includes a main unit 100, a cam 200, wheels 300, and a handle 400. The wheels 300 are mounted at the rear of the main unit 100 to support one end of the main unit 100. A mowing assembly 120 is provided at the front of the main unit 100. The cam 200 is rotatably mounted on the main unit 100 and supported between the ground and the main unit 100. The rotation of the cam 200 adjusts the support height of the cam 200 on the main unit 100. The handle 400 is connected to the rear of the main unit 100 and has a handle for the operator to grip.

[0047] The lawnmower also includes a battery pack and a control unit, which controls the operation of the mowing assembly 120 and is connected to the battery pack.

[0048] When the lawnmower moves forward, the cam 200 tends to rotate in the first direction. A self-locking mechanism 500 is provided between the main unit 100 and the cam 200. The self-locking mechanism 500 restricts the rotation of the cam 200 in the first direction and locks the lawnmower's mowing height when the lawnmower moves forward.

[0049] Since the main unit 100 is equipped with a walking wheel 300 at the rear, the walking wheel 300 limits the height of the rear end of the main unit 100. By rotating the cam 200, the height of the other end of the main unit 100 is changed, thereby changing the distance between the mowing component 120 and the ground, and thus realizing the adjustment of the mowing height of the lawnmower.

[0050] The adjustment and locking of the mowing height of the mower are realized through the cooperation of the cam 200 and the self-locking mechanism 500, the needs of users for different mowing heights of different lawns are met, and the stability of the mowing height of the mower is maintained when mowing, meanwhile, through the cooperation of the cam 200 and the self-locking mechanism 500, the user does not need to touch or approach the mower blade when adjusting the mowing height, the risk of the user's hand being cut by the blade is reduced, and the safety of the mower is improved.

[0051] In the embodiment, two walking wheels 300 are arranged on the left and right sides of the rear part of the main machine 100. By arranging two walking wheels 300, the support of the walking wheels 300 to the rear part of the main machine 100 is improved, and the stability of the mower when moving is improved, which helps to improve the consistency of the mowing height of the mower.

[0052] In the embodiment, the main machine 100 further comprises a blade seat 110 for mounting the mowing assembly 120. The blade seat 110 is further provided with a cavity 111 for accommodating the cam 200 and allowing the cam 200 to rotate, and the lower end of the cavity 111 is open to facilitate the cam 200 to support the ground. The mowing assembly 120 comprises a mowing blade and a mowing motor for driving the mowing blade to move.

[0053] In one embodiment, two cams 200 are arranged on the left and right sides of the main machine 100, and a connecting shaft 210 is arranged between the two cams 200, and the two cams 200 rotate coaxially with the connecting shaft 210.

[0054] In the embodiment, two cavities 111 are arranged on the left and right sides of the blade seat 110, and the two cams 200 are accommodated in the cavities 111 and are rotatably connected with the blade seat 110, and the first protruding ribs are arranged on the cavity walls of the cavities 111.

[0055] By arranging two cams 200, the cam 200 can more stably support one end of the main machine 100, and the consistency of the mowing height of the mower is improved, and the adjustment of the mowing height is more convenient, and the operation convenience of the operator is improved.

[0056] In one embodiment, based on the mower of the foregoing embodiment, when the cam 200 rotates in the second direction opposite to the first direction, the self-locking mechanism 500 releases the rotation restriction of the cam 200.

[0057] Specifically, the self-locking mechanism 500 is a one-way transmission mechanism located between the cam 200 and the main unit 100. When the lawnmower moves forward, the self-locking mechanism 500 transmits power between the cam 200 and the main unit 100, causing the main unit 100 to restrict the rotation of the cam 200. When the cam 200 rotates in the second direction, the self-locking mechanism 500 releases the transmission between the cam 200 and the main unit 100, and the cam 200 rotates relative to the main unit 100, thereby releasing the rotation restriction of the cam 200.

[0058] This design simplifies the structure of the self-locking mechanism 500 and reduces its cost. On the other hand, it also makes it easier for the operator to adjust the mowing height, as the rotation of the cam 200 in the second direction is less restricted.

[0059] In one embodiment, a structure of the self-locking mechanism 500 is described. The self-locking mechanism 500 includes a first ratchet 511 disposed on the cam 200 and a second ratchet 521 disposed on the main unit 100. At least one of the first ratchet 511 and the second ratchet 521 is provided in multiples. The first ratchet 511 engages radially or axially with the second ratchet 521 during rotation in a first direction. During rotation of the first ratchet 511 in a second direction, at least one of the first ratchet 511 and the second ratchet 521 may deform or displace, or at least one of the cam 200 or the main unit 100 may deform or displace, so that the first ratchet 511 slides relative to the second ratchet 521.

[0060] For example, such as Figure 5 , Figure 6 As shown, the cam 200 is provided with a plurality of first ratchet teeth 511, and the blade holder 110 is provided with a plurality of second ratchet teeth 521. The plurality of first ratchet teeth 511 are circumferentially distributed on the cam 200 along the rotation axis of the cam 200, and the plurality of second ratchet teeth 521 are circumferentially distributed on the blade holder 110 along the rotation axis of the cam 200. Each of the first ratchet teeth 511 and the second ratchet teeth 521 is provided with an engaging portion 512 and a non-engaging portion 513. The rotation of the cam 200 in the first direction causes the engaging portions 512 of the first ratchet teeth 511 and the second ratchet teeth 521 to abut against each other and engage axially. The rotation of the cam 200 in the second direction causes at least one of the first ratchet teeth 511 and the second ratchet teeth 521 to deform or displace, or at least one of the cam 200 or the blade holder 110 to deform or displace, causing the non-engaging portions 513 of the first ratchet teeth 511 and the second ratchet teeth 521 to slide relative to each other.

[0061] The engageable portion 512 is formed by the first ratchet 511 and the second ratchet 521 protruding upwards from the longitudinal wall, while the non-engageable portion 513 is formed by the inclined surface extending downwards from the longitudinal wall. The two longitudinal walls abut against each other to achieve unidirectional transmission, and the two inclined surfaces slide relative to each other to disengage the transmission.

[0062] It is understandable that the first ratchet 511 may be provided as one, and the second ratchet 521 may be provided as multiple; or, the first ratchet 511 may be provided as multiple, and the second ratchet 521 may be provided as one.

[0063] For example, such as Figure 7 , Figure 8 As shown, a ratchet 510 is fixed on the cam 200, and a pawl 520 is rotatably connected to the blade holder 110. The ratchet 510 has several first ratchet teeth 511, and the pawl 520 has second ratchet teeth 521. When the cam 200 rotates in the first direction, the first ratchet teeth 511 fall between two adjacent second ratchet teeth 521, and the first ratchet teeth 511 and the second ratchet teeth 521 abut against each other and engage radially. When the cam 200 rotates in the second direction, the tooth wall of the first ratchet teeth 511 pushes the second ratchet teeth 521 to move, thereby causing the first ratchet teeth 511 and the second ratchet teeth 521 to slide relative to each other.

[0064] It is understandable that the ratchet 510 may have only one ratchet tooth, while the pawl 520 may have multiple ratchet teeth; or the ratchet 510 may have multiple ratchet teeth, and the pawl 520 may also have multiple pawl teeth.

[0065] It is understandable, or it is possible, that the ratchet 510 is fixed to the blade holder 110, and the pawl 520 is rotatably connected to the cam 200.

[0066] The pawl 520 is equipped with a return spring so that the pawl 520 can be reset in time.

[0067] In the above configuration, the unidirectional transmission of the self-locking mechanism 500 is achieved through the cooperation of the first ratchet 511 and the second ratchet 521, which further simplifies the structure of the self-locking mechanism 500 and reduces the cost of the lawnmower.

[0068] In another embodiment, another structure of the self-locking mechanism 500 is described. The self-locking mechanism 500 is a one-way bearing. The cam 200 is mounted to the blade holder 110 through the one-way bearing. Thus, when the lawnmower moves forward, the self-locking mechanism 500 drives between the cam 200 and the blade holder 110 to stop the rotation of the cam 200. When the cam 200 rotates in the second direction, the self-locking mechanism 500 causes the cam 200 to slide relative to the main unit 100.

[0069] In one embodiment, in the lawnmower based on the foregoing embodiment, the rotational driving force of the cam 200 in the second direction comes from the backward movement of the lawnmower or an external driving force.

[0070] Users can rotate cam 200 in the second direction by pushing the lawnmower backward, or users can directly rotate cam 200 in the second direction.

[0071] In the embodiment, the operation part 211 is arranged on one end of the connecting shaft 210 protruding out of the main machine 100, and the user can rotate the operation part 211 to rotate the cam 200 in the second direction. The operation part 211 is a knob.

[0072] In this way, the user does not need to touch or approach the grass cutting blade when adjusting the grass cutting height, the risk of the user's hand being cut by the blade is reduced, and the safety of the grass trimmer is improved.

[0073] In one embodiment, one of the first ratchet 511 and the second ratchet 521 is provided with the abutting groove 522, the first ratchet 511 is rotated in the first direction, and the other of the first ratchet 511 and the second ratchet 521 is coupled in the abutting groove 522.

[0074] The abutting groove 522 is arranged on the engageable part 512 of one of the first ratchet 511 and the second ratchet 521, and the engageable part 512 of the other of the first ratchet 511 and the second ratchet 521 is coupled in the abutting groove 522.

[0075] By arranging the abutting groove 522, the contact area of the engagement between the first ratchet 511 and the second ratchet 521 is increased, and the abutting groove 522 can limit the lateral sliding of the first ratchet 511 and the second ratchet 521, so that the first ratchet 511 and the second ratchet 521 can be more stably abutted, and the reliability of the self-locking mechanism 500 in stopping the rotation of the cam 200 is improved.

[0076] In one embodiment, different from the foregoing embodiments, the grass trimmer further comprises a motor, and the self-locking mechanism 500 comprises a transmission member, the transmission member is driven by the motor to drive the rotation of the cam 200, and the transmission member is self-locked to limit the bidirectional rotation of the cam 200.

[0077] The transmission member comprises a torque receiving end and a torque output end, the torque receiving end and the torque output end have a large transmission ratio therebetween, and the torque receiving end and the torque output end are frictionally transmitted when transmitting torque, and the friction force of the torque receiving end and the torque output end generates a friction torque. The torque output end is inputted with torque, and the torque output end transmits a reverse rotation torque to the torque receiving end, and when the reverse rotation torque is smaller than the friction torque, the transmission member is self-locked.

[0078] By the above arrangement, the operator does not need to manually rotate the cam 200, so that the grass trimmer is more convenient to adjust the grass cutting height, and the self-locking of the transmission member makes the forward or backward movement of the grass trimmer not change the grass cutting height, which meets the different grass cutting height requirements of the user for different lawns and further ensures the consistency of the grass cutting height.

[0079] In one embodiment, the transmission member comprises a worm and a worm wheel, the worm is rotatably mounted on the main machine 100, the cam 200 is mounted on the worm and rotates coaxially with the worm, the worm wheel is in meshing transmission with the worm, and the rotation of the worm wheel drives the rotation of the worm.

[0080] When the worm wheel rotates, the worm wheel meshes with the worm to drive the rotation of the cam 200 to change the support height of the cam 200 to the main machine 100.

[0081] When the worm wheel does not rotate, the worm wheel and the worm are self-locked to lock the support height of the cam 200 to the main machine 100, thereby locking the mowing height of the mower.

[0082] In one embodiment, the worm wheel and the worm are self-locked through a thread angle smaller than a friction angle. The forward rotation or reverse rotation of the worm wheel can drive the worm to rotate to drive the rotation of the cam 200.

[0083] The support height of the cam 200 to the main machine 100 is adjusted through the meshing transmission of the worm wheel and the worm, and the bidirectional rotation of the cam 200 can realize the adjustment of the mowing height, thereby improving the convenience of the adjustment of the mowing height.

[0084] In other embodiments, the transmission member can also be a planetary gear set with a large transmission ratio.

[0085] In one embodiment, the mower based on the above embodiment further comprises a hand-held rod 400 connected to the rear of the main machine 100, the hand-held rod 400 is provided with a control module connected to the motor, the motor can rotate forward and reverse, the control module controls the operation of the motor, and the operation of the motor drives the rotation of the worm wheel. The mower further comprises a battery pack, and the motor and the control module are connected to the battery pack.

[0086] In one embodiment, the cam 200 is provided with two, and the two cams 200 are respectively arranged on the left and right sides of the main machine 100, and the worm is connected between the two cams 200 and drives the rotation of the two cams 200.

[0087] By providing two cams 200, the cam 200 can more stably support one end of the main machine 100, and the consistency of the mowing height of the mower is improved. The rotation of the two cams 200 makes the adjustment of the mowing height more convenient, thereby improving the operation convenience of the operator.

[0088] In one embodiment, the cam 200 is in an elliptical shape, and the rotation axis of the cam 200 is the center point of the ellipse.

[0089] The center point of the ellipse is the focus of the major axis and the minor axis of the ellipse. When the end point of the major axis of the elliptical cam 200 is supported on the ground, the mowing height is the highest, and when the end point of the minor axis of the elliptical cam 200 is supported on the ground, the mowing height is the lowest.

[0090] By configuring the cam 200 to be elliptical, so that the cam 200 has two maximum extreme points of maximum ground clearance and two minimum extreme points of minimum ground clearance, the cam 200 can switch between the two extreme points of the supporting position with the ground in a half turn, thereby reducing the angle of rotation of the cam 200 required when adjusting the mowing height of the mower, and reducing the operation time of the operator.

[0091] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that the present application includes but is not limited to the contents described in the drawings and the above specific embodiment. Any modification that does not deviate from the function and structural principle of the present application shall be included in the scope of the claims.

Claims

1. An adjustable cutting height mower comprising a main body and a walking wheel, said walking wheel being mounted to a rear portion of said main body to support one end of said main body, a front portion of said main body being provided with a cutting assembly, characterized in that, The lawn mower further comprises a cam rotatably mounted on the main body, the cam being supported between the ground and the main body, the cam being rotatable to adjust the supporting height of the cam to the main body, the cam having a tendency to rotate in a first direction when the lawn mower is moving forward, a self-locking mechanism being provided between the main body and the cam, the self-locking mechanism limiting the rotation of the cam in the first direction when the lawn mower is moving forward.

2. A height adjustable lawnmower as claimed in claim 1, characterised in that, The self-locking mechanism releases the rotation limitation of the cam when the cam rotates in a second direction opposite to the first direction.

3. A height adjustable lawnmower as claimed in claim 2, characterised in that, The rotation of the cam in the second direction is driven by the backward movement of the lawn mower or an external driving force.

4. A height adjustable lawnmower as claimed in claim 2, characterised in that, The self-locking mechanism comprises a first ratchet provided on the cam and a second ratchet provided on the main body, at least one of the first ratchet and the second ratchet being provided with a plurality of, The rotation of the first ratchet in the first direction radially engages or axially engages the second ratchet radially or axially. The rotation of the first ratchet in the first direction causes at least one of the first ratchet and the second ratchet to deform or displace, or at least one of the cam and the main body to deform or displace, so that the first ratchet slides relative to the second ratchet.

5. A height adjustable lawnmower as claimed in claim 4, characterised in that, One of the first ratchet and the second ratchet is provided with an abutting groove, the other of the first ratchet and the second ratchet being coupled in the abutting groove in the forward movement state of the lawn mower.

6. A height adjustable lawnmower as claimed in claim 1, characterised in that, The lawn mower further comprises an electric motor, the self-locking mechanism comprises a transmission member, the transmission member being driven by the electric motor to rotate the cam, and the transmission member being self-locked to limit the bidirectional rotation of the cam.

7. A height adjustable lawnmower as claimed in claim 6, characterised in that, The transmission member comprises a worm gear and a worm, the worm being rotatably mounted on the main body, the cam being coaxially rotatable with the worm, the electric motor being connected to the worm gear.

8. A height adjustable lawnmower as claimed in claim 7, characterised in that, The lawn mower further comprises a hand-held rod, the hand-held rod being provided with a control module connected to the electric motor, the electric motor being capable of forward rotation or reverse rotation, the control module controlling the operation of the electric motor.

9. A height adjustable lawnmower as claimed in claim 1, characterised in that, The cam is provided in two, the two cams being provided on the left and right sides of the main body, the two cams being coaxially rotatable.

10. A height adjustable lawnmower as claimed in claim 1, characterised in that, The cam is in the shape of an ellipse, the rotation axis of the cam being the center point of the ellipse.

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