CN112930840A

CN112930840A - Convenient type lawn mowing equipment

Info

Publication number: CN112930840A
Application number: CN202110212516.2A
Authority: CN
Inventors: 曹有骏
Original assignee: Shenzhen Jundatong Office Intelligence Technology Co ltd
Current assignee: Shenzhen Jundatong Office Intelligence Technology Co ltd
Priority date: 2021-02-25
Filing date: 2021-02-25
Publication date: 2021-06-11

Abstract

The invention relates to a convenient lawn trimming device, which comprises a shell, a driving motor, a transmission shaft and a blade, the casing is in a cuboid shape, the bottom of the casing is provided with a moving device, the driving motor is arranged at the top in the casing, the bottom of the shell is provided with a mounting hole, the transmission shaft vertically penetrates through the mounting hole and is connected with the inner wall of the mounting hole in a sliding way, the blade is arranged at the bottom end of the transmission shaft, a transmission mechanism is arranged in the shell, the driving motor is connected with the top end of the transmission shaft through the transmission mechanism, the bottom of the shell is provided with at least two auxiliary mechanisms which are circumferentially and uniformly distributed by taking the axis of the transmission shaft as a center, this convenient type lawn mowing equipment has realized the function of clean blade through drive mechanism, avoids manual cleanness, has improved the convenience, moreover, still prevents through complementary unit that stone and blade contact and lead to the blade to damage.

Description

Convenient type lawn mowing equipment

Technical Field

The invention relates to the field of gardening and horticulture, in particular to convenient lawn trimming equipment.

Background

The lawn mower is a common type of garden gardening equipment, is also called a weeder, a grass cutter, a lawn trimmer and the like, is a mechanical tool for trimming lawns, vegetations and the like, and consists of a cutter head, an engine, traveling wheels, a traveling mechanism, blades, handrails and a control part.

When the existing mower is used, when stones exist on the ground, the blades are collided with the stones to be damaged easily, the stones are easy to fly out to hurt people, safety is reduced, and furthermore, after the mower is used, scraps can be remained on the mower, manual cleaning is needed, and convenience is reduced.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: in order to overcome the defects of the prior art, the convenient lawn mowing equipment is provided.

The technical scheme adopted by the invention for solving the technical problems is as follows: a convenient lawn mowing device comprises a shell, a driving motor, a transmission shaft and blades, wherein the shell is in a cuboid shape, a moving device is arranged at the bottom of the shell, the driving motor is arranged at the top in the shell, an installation hole is formed in the bottom of the shell, the transmission shaft vertically penetrates through the installation hole, the transmission shaft is in sliding connection with the inner wall of the installation hole, the blades are arranged at the bottom end of the transmission shaft, a transmission mechanism is arranged in the shell, the driving motor is connected with the top end of the transmission shaft through the transmission mechanism, at least two auxiliary mechanisms are arranged at the bottom of the shell, and the auxiliary mechanisms are circumferentially and uniformly distributed by taking the axis of the transmission shaft as a center;

the transmission mechanism comprises a driving disc, a driven disc, a fixed pipe, at least two transmission rods and at least two lifting assemblies, wherein the driving disc, the driven disc and the fixed pipe are coaxially arranged with the transmission shaft, the bottom end of the fixed pipe is hermetically arranged at the bottom in the shell, the driven disc is arranged in the fixed pipe, the driven disc is in sliding and sealing connection with the inner wall of the fixed pipe, the driven disc is arranged at the top end of the transmission shaft, the driving disc is positioned above the fixed pipe, the driving motor is in transmission connection with the top end of the driving disc, at least two connection holes are formed in the driving disc, the connection holes are circumferentially and uniformly distributed by taking the axis of the fixed pipe as the center, the transmission rods are in one-to-one correspondence with the connection holes, the transmission rods are parallel to the transmission shaft, the transmission rods penetrate through the connection holes, the transmission rods are, the lifting assemblies correspond to the transmission rods one by one, and the lifting assemblies drive the driven disc to move in the fixed pipe along the axial direction of the transmission shaft;

the auxiliary mechanism comprises a groove, a ball, a push rod, a fixing ring, a lifting plate, a magnet block and at least two connecting assemblies, wherein the groove is formed in the bottom of the shell, the center of the ball is arranged in the groove, the ball is matched with the groove, the ball is in sliding connection with the inner wall of the groove, the ball diameter is larger than the width of a notch of the groove, the push rod is vertically arranged, the top end of the push rod is arranged on the ball, the center of the ball is positioned on the axis of the push rod, the fixing ring and the lifting ring are coaxially arranged with the push rod, the inner diameter of the fixing ring is equal to that of the push rod, the inner diameter of the lifting ring is larger than that of the push rod and smaller than that of the lifting ring, the push rod penetrates through the fixing ring, the lifting ring is positioned between the ball and the fixing ring, a gap is formed, the lifting plate is positioned below the driving disc, the magnet block is positioned between the driving disc and the lifting plate, the magnet block is arranged on the driving disc, the lifting plate is made of iron, the magnet block and the lifting plate are arranged opposite to the balls, and the connecting assemblies are uniformly distributed in the circumferential direction by taking the axis of the push rod as the center;

coupling assembling includes first spring, stopper, guide arm and guide hole, the guide hole sets up the bottom at the casing, the guide arm is vertical to be passed the guide hole, the guide arm slides and sealing connection with the inner wall of guide hole, the top of guide arm sets up the bottom at the lifter plate, the bottom of guide arm sets up the top at the lifter ring, the bottom of lifter plate is connected through first spring and the bottom in the casing, first spring is in tensile state, the stopper sets up the top at the lifter ring, the stopper supports with the bottom of casing and leans on.

Preferably, in order to realize the lifting of the driven plate, the lifting assembly comprises an electromagnet, a second spring and a stop block, the stop block is arranged on the inner wall of the fixed pipe and is abutted against the bottom of the driven plate, the electromagnet is arranged on the inner wall of the fixed pipe and is positioned between the driving plate and the driven plate, a gap is formed between the electromagnet and the driven plate, the driven plate is made of iron, the second spring is positioned between the driving plate and the driven plate, and the driving plate is connected with the driven plate through the second spring.

Preferably, in order to improve the cleaning effect of the blade, at least two air blowing assemblies are arranged on the shell and correspond to the transmission rod one by one, each air blowing assembly comprises a first air hole, a second air hole, a first one-way valve and a second one-way valve, the first air hole is formed in the bottom of the shell, the bottom end of the fixed pipe is communicated with the first air hole, the second air hole is formed in the fixed pipe, the first one-way valve is installed in the first air hole, the second one-way valve is installed in the second air hole, the first one-way valve and the second one-way valve are both located below the driven plate, and a through hole is formed in one side of the shell.

Preferably, a filter screen is installed in the through hole for dust prevention.

Preferably, in order to improve the friction force between the push rod and the stone block, the push rod is provided with anti-slip lines.

The convenient lawn trimming device has the advantages that the convenient lawn trimming device achieves the function of cleaning the blade through the transmission mechanism, avoids manual cleaning, improves convenience, and can reduce radial runout generated during rotation of the driven disc through the matching of the fixed pipe and the driven disc compared with the conventional transmission mechanism, so that the stability of rotation of the blade can be improved, and the blade is prevented from being damaged due to the fact that stones are contacted with the blade through the auxiliary mechanism.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a schematic view of a portable lawn mowing apparatus of the present invention;

FIG. 2 is a cross-sectional view of the portable lawn mowing apparatus of the present invention;

FIG. 3 is a schematic view of the drive mechanism of the portable lawn mowing apparatus of the present invention;

FIG. 4 is a schematic view of the auxiliary mechanism of the portable lawn mowing apparatus of the present invention;

in the figure: 1. the automatic cutting machine comprises a shell, 2, a driving motor, 3, a transmission shaft, 4, a blade, 5, a driving disc, 6, a driven disc, 7, a fixed tube, 8, a transmission rod, 9, a ball, 10, a push rod, 11, a fixed ring, 12, a lifting ring, 13, a lifting plate, 14, a magnet block, 15, a first spring, 16, a limiting block, 17, a guide rod, 18, an electromagnet, 19, a second spring, 20, a stop block, 21, a first one-way valve, 22, a second one-way valve and 23 a filter screen.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.

As shown in fig. 1-3, a portable lawn mowing device comprises a housing 1, a driving motor 2, a transmission shaft 3 and a blade 4, wherein the housing 1 is shaped like a cuboid, a moving device is arranged at the bottom of the housing 1, the driving motor 2 is arranged at the top inside the housing 1, a mounting hole is formed in the bottom of the housing 1, the transmission shaft 3 vertically penetrates through the mounting hole, the transmission shaft 3 is slidably connected with the inner wall of the mounting hole, the blade 4 is arranged at the bottom end of the transmission shaft 3, a transmission mechanism is arranged inside the housing 1, the driving motor 2 is connected with the top end of the transmission shaft 3 through the transmission mechanism, at least two auxiliary mechanisms are arranged at the bottom of the housing 1, and the auxiliary mechanisms are circumferentially and uniformly distributed by taking the axis of the transmission shaft 3 as a center;

the transmission mechanism comprises a driving disc 5, a driven disc 6, a fixed pipe 7, at least two transmission rods 8 and at least two lifting assemblies, wherein the driving disc 5, the driven disc 6 and the fixed pipe 7 are coaxially arranged with a transmission shaft 3, the bottom end of the fixed pipe 7 is hermetically arranged at the bottom in a shell 1, the driven disc 6 is arranged in the fixed pipe 7, the driven disc 6 is slidably and hermetically connected with the inner wall of the fixed pipe 7, the driven disc 6 is arranged at the top end of the transmission shaft 3, the driving disc 5 is positioned above the fixed pipe 7, a driving motor 2 is in transmission connection with the top end of the driving disc 5, at least two connection holes are formed in the driving disc 5, the connection holes are circumferentially and uniformly distributed by taking the axis of the fixed pipe 7 as the center, the transmission rods 8 correspond to the connection holes one to one, the transmission rods 8 are parallel to the transmission shaft 3, and the, the driving rod 8 is connected with the inner wall of the connecting hole in a sliding mode, the bottom end of the driving rod 8 is arranged at the top of the driven disc 6, the lifting assemblies correspond to the driving rods 8 one by one, and the lifting assemblies drive the driven disc 6 to move in the fixing pipe 7 along the axial direction of the driving shaft 3;

during the use of the device, the shell 1 is moved on the lawn through the moving device, the driving motor 2 is started, the driving disc 5 can drive the driven disc 6 to rotate through the transmission rod 8, the driven disc 6 rotates to drive the blade 4 to rotate through the transmission shaft 3, the function of mowing can be achieved through the rotation of the blade 4, after mowing is finished, the driving motor 2 stops running, the driven disc 6 is lifted and lowered in the fixed pipe 7 in a reciprocating mode through the lifting assembly, the driving rod 8 is lifted and lowered on the driving disc 5 in a reciprocating mode through the reciprocating lifting of the driven disc 6, the blade 4 is driven to lift and lower in a reciprocating mode through the transmission shaft 3 through the reciprocating lifting of the driven disc 6, namely, fragments on the blade 4 can be separated from the blade 4 under the inertia effect, and the function of cleaning the blade 4 is achieved.

As shown in fig. 4, the auxiliary mechanism includes a groove, a ball 9, a push rod 10, a fixing ring 11, a lifting ring 12, a lifting plate 13, a magnet block 14 and at least two connecting assemblies, the groove is disposed at the bottom of the housing 1, the center of the ball 9 is disposed in the groove, the ball 9 is matched with the groove, the ball 9 is slidably connected with the inner wall of the groove, the diameter of the ball 9 is greater than the width of the notch of the groove, the push rod 10 is vertically disposed, the top end of the push rod 10 is disposed on the ball 9, the center of the ball 9 is located on the axis of the push rod 10, the fixing ring 11 and the lifting ring 12 are both disposed coaxially with the push rod 10, the inner diameter of the fixing ring 11 is equal to the diameter of the push rod 10, the inner diameter of the lifting ring 12 is greater than the diameter of the push rod 10 and smaller than the outer diameter of the lifting ring 12, the push rod 10 passes through the, a gap is formed between the lifting ring 12 and the fixing ring 11, the lifting plate 13 is horizontally arranged in the shell 1, the lifting plate 13 is positioned below the driving disc 5, the magnet block 14 is positioned between the driving disc 5 and the lifting plate 13, the magnet block 14 is arranged on the driving disc 5, the lifting plate 13 is made of iron, the magnet block 14 and the lifting plate 13 are both arranged opposite to the ball 9, and the connecting components are uniformly distributed in the circumferential direction by taking the axis of the push rod 10 as the center;

coupling assembling includes first spring 15, stopper 16, guide arm 17 and guide hole, the guide hole sets up the bottom at casing 1, guide arm 17 is vertical to be passed the guide hole, guide arm 17 slides and sealing connection with the inner wall of guide hole, the top of guide arm 17 sets up the bottom at lifter plate 13, the bottom of guide arm 17 sets up the top at lifter ring 12, lifter plate 13's bottom is connected through first spring 15 and the bottom in the casing 1, first spring 15 is in tensile state, stopper 16 sets up the top at lifter ring 12, stopper 16 supports with casing 1's bottom and leans on.

In the moving process of the shell 1, when the push rod 10 abuts against the stone, the push rod 10 can drive the balls 9 to rotate in the grooves, so that the push rod 10 can be in an inclined state, the driving disc 5 rotates to drive the driven block to synchronously rotate, the magnet block 14 and the iron lifting plate 13 have mutually attracted acting force, and the acting force is inversely proportional to the distance, so that after the distance between the magnet block 14 and the lifting plate 13 is increased, the mutually attracted acting force between the lifting plate 13 and the magnet block 14 is reduced, at the moment, the lifting plate 13 descends through the elastic action of the first spring 15, the lifting plate 13 descends through the guide rod 17 drives the lifting ring 12 to synchronously move, the lifting ring 12 abuts against the fixing ring 11, so that the fixing ring 11 drives the push rod 10 to rotate around the center of the balls 9 to a vertical state under the action of downward thrust, and the push rod 10 can push the stone, thus, the contact between the block and the blade 4 is prevented, and when the distance between the magnet block 14 and the lifting plate 13 is reduced, the lifting plate 13 is lifted by the force of the attraction between the magnet block 14 and the lifting plate 13, and the lifting ring 12 is lifted by the lifting plate 13 via the guide rod 17, and the first spring 15 is compressed.

Preferably, in order to realize the lifting of the driven disc 6, the lifting assembly comprises an electromagnet 18, a second spring 19 and a stop block 20, the stop block 20 is arranged on the inner wall of the fixed pipe 7, the stop block 20 abuts against the bottom of the driven disc 6, the electromagnet 18 is arranged on the inner wall of the fixed pipe 7, the electromagnet 18 is positioned between the driving disc 5 and the driven disc 6, a gap is arranged between the electromagnet 18 and the driven disc 6, the driven disc 6 is made of iron, the second spring 19 is positioned between the driving disc 5 and the driven disc 6, and the driving disc 5 is connected with the driven disc 6 through the second spring 19.

During cleaning the blade 4, the electromagnet 18 is intermittently electrified, when the electromagnet 18 is electrified, the electromagnet 18 and the ferrous driven disc 6 can generate attraction force, namely the driven disc 6 can move upwards, and the second spring 19 is compressed, and after the electromagnet 18 is powered off, the driven disc 6 can move downwards and abut against the stop block 20 through the elastic action of the second spring 19, and the reciprocating lifting of the driven disc 6 can be realized in such a circulating manner.

Preferably, in order to improve the cleaning effect of the blade 4, at least two air blowing assemblies are arranged on the shell 1, the air blowing assemblies correspond to the transmission rod 8 one by one, each air blowing assembly comprises a first air hole, a second air hole, a first one-way valve 21 and a second one-way valve 22, the first air hole is formed in the bottom of the shell 1, the bottom end of the fixing tube 7 is communicated with the first air hole, the second air hole is formed in the fixing tube 7, the first one-way valve 21 is installed in the first air hole, the second one-way valve 22 is installed in the second air hole, the first one-way valve 21 and the second one-way valve 22 are both located below the driven plate 6, and a through hole is formed in one side of the shell 1.

During the upward movement of the driven plate 6, the air cannot be conveyed into the housing 1 from the first air hole and only the air in the housing 1 can be conveyed into the fixed pipe 7 from the second air hole through the one-way characteristic of the first one-way valve 21, while the air outside the housing 1 is conveyed into the housing 1 from the through hole, when the driven plate 6 moves downward, the air in the fixed pipe 7 cannot be discharged from the second air hole and only the air in the fixed pipe 7 can be discharged from the first air hole and acts on the blade 4 through the one-way characteristic of the second one-way valve 22, under the action of the air flow, the separation of the debris from the blade 4 can be facilitated, the cleaning effect of the blade 4 is improved, and the heat dissipation effect of the driving motor 2 can also be improved through the flow of the air in the housing 1.

Preferably, a screen 23 is installed in the through hole for dust prevention.

Dust in the air can be trapped by the screen 23 and prevented from acting on the blade 4.

Preferably, the push rod 10 is provided with anti-slip threads in order to increase the friction between the push rod 10 and the stone.

The anti-slip threads are used for improving the friction force between the push rod 10 and the stone and preventing the push rod 10 from slipping when pushing the stone.

During the use of the device, the shell 1 is moved on the lawn through the moving device, the driving motor 2 is started, so that the driving disc 5 drives the driven disc 6 to rotate through the transmission rod 8, the driven disc 6 rotates to drive the blade 4 to rotate through the transmission shaft 3, the function of mowing can be realized through the rotation of the blade 4, after mowing is finished, the driving motor 2 stops running, the driven disc 6 is driven to reciprocate and lift in the fixed pipe 7 through the lifting component, the reciprocating lifting of the driven disc 6 drives the transmission rod 8 to reciprocate and lift on the driving disc 5, and the reciprocating lifting of the driven disc 6 drives the blade 4 to reciprocate and lift through the transmission shaft 3, so that scraps on the blade 4 can be separated from the blade 4 under the action of inertia, the function of cleaning the blade 4 is realized, and in the moving process of the shell 1, when the push rod 10 is abutted against a stone, the push rod 10 can drive the ball 9 to rotate in the groove, therefore, the push rod 10 can be in an inclined state, the driven block is driven to synchronously rotate by the rotation of the driving disk 5, the magnet block 14 and the iron lifting plate 13 have mutually attracted acting force, and the acting force is inversely proportional to the distance, so that after the distance between the magnet block 14 and the lifting plate 13 is increased, the mutually attracted acting force between the lifting plate 13 and the magnet block 14 is reduced, at the moment, the lifting plate 13 descends under the elastic action of the first spring 15, the lifting plate 13 descends through the guide rod 17 drives the lifting ring 12 to synchronously move and the lifting ring 12 is abutted against the fixing ring 11, so that the fixing ring 11 drives the push rod 10 to rotate around the center of the ball 9 to a vertical state under the action of downward pushing force, namely, the push rod 10 can push the stone, thereby preventing the stone from contacting with the blade 4, when the distance between the magnet block 14 and the lifting plate 13 is reduced, the elevating plate 13 is elevated by the attraction force between the magnet block 14 and the elevating plate 13, and the elevation of the elevating plate 13 causes the elevating ring 12 to be elevated by the guide rod 17, and the first spring 15 is compressed.

Compared with the prior art, this convenient type lawn mowing equipment has realized the function of clean blade 4 through drive mechanism, avoid manual cleanness, the convenience has been improved, compare with current drive mechanism, this drive mechanism is through fixed pipe 7 and driven plate 6's cooperation, can reduce the runout that produces during the driven plate 6 rotates, thereby can improve blade 4 pivoted stability, moreover, still prevent through complementary unit that stone and blade 4 contact and lead to blade 4 to damage, compare with current complementary unit, this complementary unit can also realize promoting the function of stone, the effect is better is clear away to the stone.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A convenient lawn trimming device, which comprises a shell (1), a driving motor (2), a transmission shaft (3) and a blade (4), the shape of the shell (1) is a cuboid, the bottom of the shell (1) is provided with a moving device, the driving motor (2) is arranged at the top in the shell (1), the bottom of the shell (1) is provided with a mounting hole, the transmission shaft (3) vertically penetrates through the mounting hole, the transmission shaft (3) is connected with the inner wall of the mounting hole in a sliding manner, the blade (4) is mounted at the bottom end of the transmission shaft (3), it is characterized in that a transmission mechanism is arranged in the shell (1), the driving motor (2) is connected with the top end of the transmission shaft (3) through the transmission mechanism, the bottom of the shell (1) is provided with at least two auxiliary mechanisms which are circumferentially and uniformly distributed by taking the axis of the transmission shaft (3) as a center;

the transmission mechanism comprises a driving disc (5), a driven disc (6), a fixed pipe (7), at least two transmission rods (8) and at least two lifting components, wherein the driving disc (5), the driven disc (6) and the fixed pipe (7) are coaxially arranged with a transmission shaft (3), the bottom end of the fixed pipe (7) is sealed and arranged at the bottom of the shell (1), the driven disc (6) is arranged in the fixed pipe (7), the driven disc (6) is connected with the inner wall of the fixed pipe (7) in a sliding and sealing manner, the driven disc (6) is arranged at the top end of the transmission shaft (3), the driving disc (5) is positioned above the fixed pipe (7), the driving motor (2) is in transmission connection with the top end of the driving disc (5), at least two connection holes are formed in the driving disc (5), and are circumferentially and uniformly distributed by taking the axis of the fixed pipe (7) as the center, the transmission rods (8) correspond to the connecting holes one by one, the transmission rods (8) are parallel to the transmission shaft (3), the transmission rods (8) penetrate through the connecting holes, the transmission rods (8) are connected with the inner walls of the connecting holes in a sliding mode, the bottom end of each transmission rod (8) is arranged at the top of the driven disc (6), the lifting assemblies correspond to the transmission rods (8) one by one, and the lifting assemblies drive the driven discs (6) to move in the fixed pipe (7) along the axial direction of the transmission shaft (3);

the auxiliary mechanism comprises a groove, a ball (9), a push rod (10), a fixing ring (11), a lifting ring (12), a lifting plate (13), a magnet block (14) and at least two connecting assemblies, wherein the groove is formed in the bottom of the shell (1), the center of the ball (9) is arranged in the groove, the ball (9) is matched with the groove, the ball (9) is in sliding connection with the inner wall of the groove, the ball diameter of the ball (9) is larger than the width of a groove opening of the groove, the push rod (10) is vertically arranged, the top end of the push rod (10) is arranged on the ball (9), the center of the ball (9) is located on the axis of the push rod (10), the fixing ring (11) and the lifting ring (12) are coaxially arranged with the push rod (10), the inner diameter of the fixing ring (11) is equal to that of the push rod (10), the inner diameter of the lifting ring (12) is larger than that of the push rod (10) and smaller than that of the lifting, the push rod (10) penetrates through the fixing ring (11), the lifting ring (12) is located between the ball (9) and the fixing ring (11), a gap is formed between the lifting ring (12) and the fixing ring (11), the lifting plate (13) is horizontally arranged in the shell (1), the lifting plate (13) is located below the driving disc (5), the magnet block (14) is located between the driving disc (5) and the lifting plate (13), the magnet block (14) is arranged on the driving disc (5), the lifting plate (13) is made of iron, the magnet block (14) and the lifting plate (13) are both arranged right opposite to the ball (9), and the connecting assembly is circumferentially and uniformly distributed by taking the axis of the push rod (10) as the center;

coupling assembling includes first spring (15), stopper (16), guide arm (17) and guide hole, the guide hole sets up the bottom in casing (1), the vertical guide hole that passes of guide arm (17), guide arm (17) slide and sealing connection with the inner wall of guide hole, the top of guide arm (17) sets up the bottom at lifter plate (13), the bottom of guide arm (17) sets up the top at lifter ring (12), the bottom of lifter plate (13) is connected through the bottom in first spring (15) and casing (1), first spring (15) are in tensile state, stopper (16) set up the top at lifter ring (12), stopper (16) support with the bottom of casing (1) and lean on.

2. The portable lawn mowing apparatus according to claim 1, wherein the lifting assembly comprises an electromagnet (18), a second spring (19) and a stop (20), the stop (20) is disposed on an inner wall of the fixed pipe (7), the stop (20) abuts against a bottom of the driven disc (6), the electromagnet (18) is disposed on an inner wall of the fixed pipe (7), the electromagnet (18) is located between the driving disc (5) and the driven disc (6), a gap is provided between the electromagnet (18) and the driven disc (6), the driven disc (6) is made of iron, the second spring (19) is located between the driving disc (5) and the driven disc (6), and the driving disc (5) is connected with the driven disc (6) through the second spring (19).

3. Portable lawn mowing device according to claim 1, characterized in that at least two air blowing assemblies are provided on the housing (1), said air blowing assemblies corresponding one-to-one to the transmission rod (8), said air blowing assemblies comprising a first air hole provided at the bottom of the housing (1), a second air hole provided at the fixed tube (7), a first one-way valve (21) and a second one-way valve (22), said first air hole being provided in the bottom of the housing (1), said bottom end of the fixed tube (7) communicating with the first air hole, said second air hole being provided at the fixed tube (7), said first one-way valve (21) being mounted in the first air hole, said second one-way valve (22) being mounted in the second air hole, said first one-way valve (21) and said second one-way valve (22) being located below the driven disc (6), a through hole being provided at one side of the housing (1).

4. Portable lawn-trimming apparatus according to claim 3, characterized in that a sieve (23) is mounted in the through-going hole.

5. Portable lawn-trimming device according to claim 1, wherein the push rod (10) is provided with anti-slip threads.