CN217447185U

CN217447185U - Sofa with extensible armrests

Info

Publication number: CN217447185U
Application number: CN202221276159.2U
Authority: CN
Inventors: 王炳坤
Original assignee: Dongguan Aimu Bedroom Supplies Co Ltd
Current assignee: Dongguan Aimu Bedroom Supplies Co Ltd
Priority date: 2022-05-25
Filing date: 2022-05-25
Publication date: 2022-09-20
Anticipated expiration: 2032-05-25

Abstract

The utility model belongs to the technical field of the sofa, a sofa that handrail can expand is disclosed, which comprises a backrest, a pedestal, the handrail subassembly, supporting mechanism and positioning mechanism, the back is connected in the base, the base upper berth is equipped with the cushion, the first handrail of handrail subassembly is rotated through first pivot and is connected in the base, the one end that the second handrail deviates from the base is rotated through the second pivot and is connected in first handrail, first handrail is located one side that the second handrail deviates from the cushion, supporting mechanism's linkage subassembly transmission joint support pole and second pivot, the bracing piece rotates and sets up in first handrail, the linkage subassembly can make second pivot and bracing piece antiport, positioning mechanism is used for fixing second handrail and first handrail, and it is fixed with first handrail and base. Through rotating first handrail, then rotate the second handrail, the bracing piece rotates thereupon and supports in ground to can prolong the length of leaning on of sofa, satisfied user's diversified user demand.

Description

Sofa with extensible armrests

Technical Field

The utility model relates to a sofa technical field especially relates to a sofa that handrail can expand.

Background

The sofa is a backrest chair provided with springs or thick foam plastics and the like, and the two sides of the sofa are provided with armrests, so that the sofa is one kind of soft furniture. In the prior art, the length of the sofa is generally fixed, when the number of people sitting and leaning on is large, the using requirement cannot be met, when the number of people sitting and leaning on is small, the sofa which is too long occupies too much space, and the requirement of a user cannot be flexibly met.

Based on the above situation, it is desired to design a sofa with an extendable armrest to solve the above problems.

SUMMERY OF THE UTILITY MODEL

The utility model discloses an aim at: the sofa with the extensible armrests can flexibly adjust the seating and leaning length and meet the diversified use requirements of users.

To achieve the purpose, the utility model adopts the following technical proposal:

a sofa with extendable arms, comprising:

a backrest for resting;

the backrest is connected with the base, and a cushion is laid on the base;

the armrest assembly is arranged at the end part of the base and comprises a first armrest, a first rotating shaft, a second armrest and a second rotating shaft, the first armrest is rotatably connected to the base through the first rotating shaft, one end, away from the base, of the second armrest is rotatably connected to the first armrest through the second rotating shaft, and the first armrest is positioned on one side, away from the seat cushion, of the second armrest;

the supporting mechanism comprises a supporting rod and a linkage assembly, the linkage assembly is in transmission connection with the supporting rod and the second rotating shaft, the supporting rod is rotatably arranged in the first handrail, the linkage assembly can enable the second rotating shaft and the supporting rod to rotate reversely, and when the second rotating shaft and the second handrail rotate in a direction departing from the first handrail to be unfolded, the supporting rod can rotate in a direction departing from the second handrail to be supported on the ground;

and the positioning mechanism is used for fixing the second handrail and the first handrail and fixing the first handrail and the base.

As a preferable scheme, the positioning mechanism includes a first locking component, the first locking component is mounted on the first armrest, the base is provided with a plurality of first positioning holes, distances from the first positioning holes to the first rotating shaft are equal, and the first locking component can be selectively inserted into the first positioning hole to limit the rotation of the first armrest.

As a preferable aspect, the first locking member includes:

the sleeve is connected to the first handrail, a first jack is formed in one end, close to the first handrail, of the sleeve, and a second positioning hole corresponding to the first jack is formed in the first handrail;

the lock shaft penetrates through the sleeve, and an outer folded eaves are arranged on the periphery of the lock shaft;

the elastic piece is sleeved on the locking shaft, one end of the elastic piece is abutted to the outer folded eaves, the other end of the elastic piece is abutted to the sleeve to deviate from the bottom of the first handrail, and the elastic piece can drive the locking shaft to sequentially penetrate through the first insertion hole and the second positioning hole and be inserted into the first positioning hole.

As a preferred scheme, the lock shaft includes grafting portion and knob portion, the sleeve deviates from the one end of first handrail has seted up the second jack, grafting portion wears to locate the sleeve and the one end that deviates from first handrail extends the second jack, knob portion with grafting portion extends the part of second jack can be dismantled and be connected, knob portion can butt the sleeve and spacing in the telescopic outside.

Preferably, the insertion part is in threaded connection with the knob part.

As a preferable scheme, a stopping part is arranged on the first handrail, a limiting column is installed on the base, the distance from the stopping part to the first rotating shaft is greater than the distance from the limiting column to the first rotating shaft, and when the stopping part is stopped against the limiting column, the lock shaft is aligned with the first positioning hole.

As a preferable scheme, the positioning mechanism further includes a second locking assembly, the second locking assembly is mounted on the second armrest, the first armrest is provided with a plurality of third positioning holes, distances from the plurality of third positioning holes to the second rotating shaft are equal, and the second locking assembly can be selectively inserted into the third positioning holes to limit rotation of the second armrest.

As a preferable scheme, the linkage assembly comprises a first gear and a second gear, the first gear is sleeved on the second rotating shaft in a transmission manner, the second gear is meshed with the first gear, and the second gear is in transmission connection with the supporting rod and can drive the supporting rod to rotate.

Preferably, the number of teeth of the second gear is less than that of the teeth of the first gear, and when the second armrest rotates to be perpendicular to the first armrest, an included angle between the support rod and the first armrest is an obtuse angle.

As a preferred scheme, the bracing piece includes first mobile jib and second mobile jib, the one end of first mobile jib with second mobile jib telescopic connection, the other end of first mobile jib with second gear drive is connected, the second mobile jib can be relative first mobile jib is flexible.

The utility model has the advantages that: when the number of people sitting and leaning on is large, the first handrail is rotated, then the second handrail is rotated, the second handrail drives the supporting rod to rotate so as to enable the supporting rod to be supported on the ground, and the positioning mechanism fixes the second handrail and the first handrail as well as the first handrail and the base, so that the sitting and leaning length of the sofa can be prolonged; when the number of people sitting and leaning on is small, the sofa can be reset by reversely rotating the first handrail and the second handrail, the structure is compact, the occupied space is small, and the diversified use requirements of users can be met.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and examples.

FIG. 1 is a schematic illustration of a sofa with deployable armrests (right side armrest assembly in cross-section);

FIG. 2 is a partial schematic view at the positioning mechanism;

fig. 3 is a cross-sectional view of the first locking assembly or the second locking assembly.

In fig. 1 to 3:

1. a backrest;

2. a base; 21. a cushion; 22. a first positioning hole; 23. a limiting column;

3. an armrest assembly; 31. a first armrest; 311. a stopping part; 312. a second positioning hole; 313. a third positioning hole; 32. a first rotating shaft; 33. a second handrail; 34. a second rotating shaft;

4. a support mechanism; 41. a support bar; 411. a first main bar; 412. a second main bar; 42. a linkage assembly; 421. a first gear; 422. a second gear;

5. a positioning mechanism; 51. a first locking assembly; 511. a sleeve; 5111. a first jack; 5112. a second jack; 512. a lock shaft; 5121. a plug-in part; 5122. a knob portion; 513. an elastic member; 52. a second locking assembly.

Detailed Description

In order to make the technical problems, the adopted technical solutions and the achieved technical effects of the present invention clearer, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, detachably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact between the first and second features, or may comprise contact between the first and second features not directly. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The technical solution of the present invention is further explained by the following embodiments with reference to the accompanying drawings.

As shown in fig. 1, the present embodiment provides a sofa with extendable armrests, which includes a backrest 1, a base 2, armrest assemblies 3 and a supporting mechanism 4, wherein the backrest 1 is used for leaning, the backrest 1 and the base 2 are arranged at an angle and connected to the base 2, a seat cushion 21 is laid on the base 2, the seat cushion 21 is used for carrying a human body, two armrest assemblies 3 are respectively and symmetrically installed at two ends of the base 2, or the armrest assemblies 3 are only arranged at one end of the base 2, a single armrest assembly 3 includes a first armrest 31, a first rotating shaft 32, a second armrest 33 and a second rotating shaft 34, the first armrest 31 is rotatably connected to the base 2 through the first rotating shaft 32 in a direction close to or far away from the seat cushion 21, the first rotating shaft 32 is arranged in parallel with the second rotating shaft 34, one end of the second armrest 33, far away from the base 2, is rotatably connected to the first armrest 31 through the second rotating shaft 34 in a direction close to or far away from the first armrest 31, the first armrest 31 is located on a side of the second armrest 33 away from the seat cushion 21, the second armrest 33 can rotate around the second rotating shaft 34 to be folded on the first armrest 31 or unfolded to be perpendicular to the first armrest 31, the supporting mechanism 4 includes a supporting rod 41 and a linkage assembly 42, the linkage assembly 42 is in transmission connection with the supporting rod 41 and the second rotating shaft 34, the supporting rod 41 is rotatably disposed in the first armrest 31, the supporting rod 41 can rotate in a direction close to the second armrest 33 to retract into the first armrest 31 or rotate in a direction away from the second armrest 33 to extend out of the first armrest 31, the linkage assembly 42 can enable the second rotating shaft 34 and the supporting rod 41 to rotate in opposite directions, when the second rotating shaft 34 and the second handrail 33 rotate in the direction away from the first handrail 31, the supporting rod 41 can rotate in the direction away from the second handrail 33, and the positioning mechanism 5 is used for limiting the relative rotation of the second handrail 33 and the first handrail 31 and the relative rotation of the first handrail 31 and the base 2. When a large number of people need to sit on, the first armrest 31 is rotated in a direction away from the seat cushion 21 to horizontally align the first armrest 31 with the seat cushion 21, then the second armrest 33 is rotated in a direction away from the first armrest 31, meanwhile, the linkage assembly 42 drives the support rod 41 to rotate in a direction away from the second armrest 33 to be supported on the ground, the positioning mechanism 5 fixes the second armrest 33 and the first armrest 31 to the base 2, and prevents the second armrest 33 and the first armrest 31 from continuing to rotate, so that the use length of the sofa can be prolonged; when the number of people sitting and leaning on is less, the first handrail 31 is rotated along the direction close to the seat cushion 21, so that the first handrail 31 is perpendicular to the base 2, then the second handrail 33 is rotated along the direction close to the first handrail 31, the linkage component 42 drives the supporting rod 41 to retract into the first handrail 31 along the direction close to the second handrail 33, and the second handrail 33 is folded on the first handrail 31 and is perpendicular to the base 2.

As shown in fig. 1 and fig. 2, in the present embodiment, the positioning mechanism 5 includes a first locking component 51, the first locking component 51 is installed on the first armrest 31, the base 2 is provided with a plurality of first positioning holes 22, the specific number can be set according to actual requirements, the present embodiment is provided with two first positioning holes 22, the distances from the two first positioning holes 22 to the first rotating shaft 32 are equal, the two first positioning holes 22 respectively correspond to 0 ° and 90 ° rotating angles, and when the first locking component 51 is selected to be inserted into the first positioning hole 22, the first armrest 31 cannot continue to rotate. It will be appreciated that when the first handle 31 is retracted onto the base 2, the first locking member 51 is inserted into the 0 ° corresponding first positioning hole 22 to fix the first handle 31, and when the first handle 31 is unfolded to be aligned with the seat cushion 21, the first locking member 51 is inserted into the 90 ° corresponding first positioning hole 22 to fix the first handle 31.

In the present embodiment, the positioning mechanism 5 further includes a second locking component 52 for fixing the second handrail 33, the structure of the second locking component 52 is the same as that of the first locking component 51, the first handrail 31 is provided with a plurality of third positioning holes 313, the specific number of the second locking components can be set according to actual requirements, the present embodiment is provided with two third positioning holes 313, the distances from the two third positioning holes 313 to the second rotating shaft 34 are equal, the two third positioning holes 313 correspond to rotation angles of 0 ° and 90 ° respectively, and when the second locking component 52 is inserted into the third positioning hole 313 alternatively, the second handrail 33 cannot rotate continuously. It is understood that when the second armrest 33 is folded into the first armrest 31, the second locking member 52 is inserted into the third positioning hole 313 corresponding to 0 ° to fix the second armrest 33, and when the second armrest 33 is unfolded to be perpendicular to the first armrest 31, the second locking member 52 is inserted into the third positioning hole 313 corresponding to 90 ° to fix the second armrest 33.

As shown in fig. 3, taking the first locking assembly 51 as an example for specific description, the first locking assembly includes a sleeve 511, a locking shaft 512 and an elastic member 513, the sleeve 511 is fixedly connected to the first handrail 31, and specifically may be fixed to the first handrail 31 through a screw connection or a welding manner, one end of the sleeve 511 close to the first handrail 31 is provided with a first insertion hole 5111, the first handrail 31 is provided with a second positioning hole 312 corresponding to and communicating with the first insertion hole 5111, the locking shaft 512 is disposed through the sleeve 511 and one end of the locking shaft can extend out of the first insertion hole 5111 and the second positioning hole 312, an outer folding ledge is disposed on a peripheral portion of the locking shaft 512, the elastic member 513 may be a spring or a rubber pad, the elastic member 513 in this embodiment is a spring, the spring is sleeved on the locking shaft 512, and two ends of the spring are respectively abutted against the outer folding ledge and a bottom of the sleeve 511 departing from the first handrail 31. It can be understood that when the first armrest 31 rotates to the preset inclination angle, the spring can drive the locking shaft 512 to automatically penetrate through the first insertion hole 5111 and the second positioning hole 312 and be inserted into the first positioning hole 22 on the base 2, and the operation is simple. In other embodiments of the present invention, the locking shaft 512 may be disposed outside, and when the first armrest 31 rotates to a preset inclination angle, the locking shaft 512 is inserted into the first positioning hole 22 and the second positioning hole 312 from the outside.

Specifically, the lock shaft 512 includes an insertion portion 5121 and a knob portion 5122, a second insertion hole 5112 is formed in an end of the sleeve 511 facing away from the first armrest 31, the insertion portion 5121 is disposed in the sleeve 511 in a penetrating manner and extends out of the second insertion hole 5112 from an end of the sleeve 511 facing away from the first armrest 31, an end close to the first armrest 31 can be inserted into the first positioning hole 22, the knob portion 5122 and a portion of the insertion portion 5121 extending out of the second insertion hole 5112 are detachably connected, specifically, the connection manner may be a clamping manner or a threaded manner, the knob portion 5122 of the present embodiment is provided with an internal thread, the insertion portion 5121 is provided with an external thread, the knob portion 5122 and the insertion portion 5121 are connected by a thread, a maximum contour size of the knob portion 5122 is greater than a maximum contour size of the second insertion hole 5112, and the knob portion 5122 can abut against the sleeve 511 and is limited to an outer side of the sleeve 511. On the other hand, when the inclination angle of the first armrest 31 is adjusted, the knob portion 5122 can be pulled outward to disengage the lock shaft 512 from the first positioning hole 22; on the other hand, when assembling the lock shaft 512, the lock shaft 512 can be divided into two sections, that is, the insertion part 5121 is first inserted into the sleeve 511, and then the knob part 5122 is screwed to the insertion part 5121, which is convenient for assembly.

As shown in fig. 2, as a preferred embodiment, the first handrail 31 is provided with an abutting portion 311, the base 2 is provided with the stop post 23, and the distance from the abutting portion 311 to the first rotating shaft 32 is greater than the distance from the stop post 23 to the first rotating shaft 32. When the first armrest 31 rotates around the first rotating shaft 32 on the base 2, the abutting portion 311 can abut against the limiting post 23 to limit the first armrest 31 to continue rotating, so as to improve reliability, the locking shaft 512 at this time just aligns with the first positioning hole 22, and the elastic element 513 drives the locking shaft 512 to be inserted into the first positioning hole 22, thereby facilitating operation.

As shown in fig. 1, the linkage assembly 42 includes a first gear 421 and a second gear 422, the first gear 421 is connected to the transmission sleeve and is disposed on the second rotating shaft 34, the second gear 422 is connected to the transmission sleeve and is disposed on the third rotating shaft, the third rotating shaft is rotatably disposed in the first armrest 31, and the third rotating shaft is fixedly connected to the supporting rod 41, the second gear 422 is directly engaged with the first gear 421, so as to realize the reverse rotation of the supporting rod 41 and the second rotating shaft 34, when the second armrest 33 rotates along the direction away from the first armrest 31, the supporting rod 41 can rotate along the direction away from the second armrest 33, and the structure is simple.

Specifically, the module of the second gear 422 is the same as that of the first gear 421, the number of teeth of the second gear 422 is less than that of the first gear 421, and the reference circle diameter of the second gear 422 is smaller than that of the first gear 421. When the linear speeds are equal, the rotation speed of the second gear 422 is greater than that of the first gear 421, and when the second handrail 33 rotates to be perpendicular to the first handrail 31, the linkage assembly 42 drives the supporting rod 41 to rotate to be arranged at an obtuse angle with the first handrail 31 and to be supported on the ground, so that the supporting structure is more reliable.

Specifically, the supporting rod 41 includes a first main rod 411 and a second main rod 412, one end of the first main rod 411 is connected to the second main rod 412 in a retractable manner, a plurality of fixing holes are formed in the second main rod 412 in the embodiment, a fastener can be selectively inserted through the fixing holes and connected to the first main rod 411, and the other end of the first main rod 411 is in transmission connection with the second gear 422. It can be understood that, when the armrest assembly 3 is not deployed, the fixing hole close to the second gear 422 is selected to connect the first main rod 411 and the second main rod 412 so as to partially retract the second main rod 412 into the first main rod 411, so that the support rod 41 can be completely hidden in the first armrest 31, and the structure is compact and the appearance is beautiful.

In the description herein, it is to be understood that the terms "upper," "lower," "left," "right," and the like are used in an orientation or positional relationship based on what is shown in the drawings for convenience of description and simplicity of operation, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be considered limiting. Furthermore, the terms "first" and "second" are used merely for descriptive purposes and are not intended to have any special meaning.

In the description herein, references to the description of "an embodiment," "an example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example.

In addition, the foregoing is only the preferred embodiment of the present invention and the technical principles applied thereto. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims

1. A sofa with extendable arms, comprising:

a backrest (1) for leaning against;

the backrest (1) is connected with the base (2), and a cushion (21) is laid on the base (2);

the armrest component (3) is mounted at the end of the base (2), the armrest component (3) comprises a first armrest (31), a first rotating shaft (32), a second armrest (33) and a second rotating shaft (34), the first armrest (31) is rotatably connected to the base (2) through the first rotating shaft (32), one end, away from the base (2), of the second armrest (33) is rotatably connected to the first armrest (31) through the second rotating shaft (34), and the first armrest (31) is located on one side, away from the seat cushion (21), of the second armrest (33);

the supporting mechanism (4) comprises a supporting rod (41) and a linkage component (42), the linkage component (42) is in transmission connection with the supporting rod (41) and the second rotating shaft (34), the supporting rod (41) is rotatably arranged in the first handrail (31), the linkage component (42) can enable the second rotating shaft (34) and the supporting rod (41) to rotate in the opposite direction, and when the second rotating shaft (34) and the second handrail (33) rotate in the direction departing from the first handrail (31) to be unfolded, the supporting rod (41) can rotate in the direction departing from the second handrail (33) to be supported on the ground;

and the positioning mechanism (5) is used for fixing the second handrail (33) with the first handrail (31) and fixing the first handrail (31) with the base (2).

2. The sofa with extendable armrests according to claim 1, wherein the positioning mechanism (5) comprises a first locking member (51), the first locking member (51) is mounted to the first armrest (31), the base (2) defines a plurality of first positioning holes (22), the plurality of first positioning holes (22) are spaced apart from the first rotation shaft (32) by an equal distance, and the first locking member (51) can be selectively inserted into the first positioning holes (22) to limit the rotation of the first armrest (31).

3. The sofa with extendable armrests according to claim 2, wherein the first locking assembly (51) comprises:

the sleeve (511) is connected to the first handrail (31), a first insertion hole (5111) is formed in one end, close to the first handrail (31), of the sleeve (511), and a second positioning hole (312) corresponding to the first insertion hole (5111) is formed in the first handrail (31);

the lock shaft (512) penetrates through the sleeve (511), and an outer folded brim is arranged on the periphery of the lock shaft (512);

elastic component (513), the cover is located locking shaft (512), the one end butt of elastic component (513) the eaves of turning over outward, the other end butt sleeve (511) deviate from the bottom of first handrail (31), elastic component (513) can drive locking shaft (512) run through in proper order first jack (5111) with second locating hole (312) insert in first locating hole (22).

4. The sofa with the extendable armrests according to claim 3, wherein the lock shaft (512) includes an insertion portion (5121) and a knob portion (5122), a second insertion hole (5112) is formed in an end of the sleeve (511) facing away from the first armrest (31), the insertion portion (5121) is inserted into the sleeve (511) and extends out of the second insertion hole (5112) from an end of the sleeve (511) facing away from the first armrest (31), the knob portion (5122) is detachably connected to a portion of the insertion portion (5121) extending out of the second insertion hole (5112), and the knob portion (5122) can abut against the sleeve (511) and is limited to the outer side of the sleeve (511).

5. The sofa with extendable armrests, according to claim 4, wherein the plug-in part (5121) is threadedly connected with the knob part (5122).

6. The sofa with extendable armrests according to claim 3, wherein the first armrest (31) is provided with an abutting portion (311), the base (2) is provided with a limiting post (23), the distance from the abutting portion (311) to the first rotating shaft (32) is greater than the distance from the limiting post (23) to the first rotating shaft (32), and when the abutting portion (311) abuts against the limiting post (23), the locking shaft (512) is aligned with the first positioning hole (22).

7. The sofa with extendable armrests according to claim 2, wherein the positioning mechanism (5) further comprises a second locking assembly (52), the second locking assembly (52) is mounted to the second armrest (33), the first armrest (31) has a plurality of third positioning holes (313), the plurality of third positioning holes (313) are equidistant from the second axis of rotation (34), and the second locking assembly (52) can be selectively inserted into the third positioning holes (313) to limit the rotation of the second armrest (33).

8. The sofa with extendable armrests according to claim 1, wherein the linkage assembly (42) includes a first gear (421) and a second gear (422), the first gear (421) is disposed on the second rotating shaft (34) in a driving manner, the second gear (422) is engaged with the first gear (421), and the second gear (422) is in a driving connection with the supporting rod (41) and can drive the supporting rod (41) to rotate.

9. The sofa with extendable armrests according to claim 8, wherein the number of teeth of the second gear (422) is less than that of the first gear (421), and when the second armrest (33) is rotated to be perpendicular to the first armrest (31), the supporting rod (41) forms an obtuse angle with the first armrest (31).

10. The sofa with extendable armrests, according to claim 8, wherein the support rod (41) comprises a first main rod (411) and a second main rod (412), one end of the first main rod (411) is telescopically connected with the second main rod (412), the other end of the first main rod (411) is drivingly connected with the second gear (422), and the second main rod (412) is telescopically connected with respect to the first main rod (411).