CN219115538U

CN219115538U - Baby carriage frame

Info

Publication number: CN219115538U
Application number: CN202223267831.4U
Authority: CN
Inventors: 廖文平
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-12-03
Filing date: 2022-12-03
Publication date: 2023-06-02
Anticipated expiration: 2032-12-03

Abstract

The utility model discloses a baby carriage frame, wherein a front leg (11) is connected with a rear leg (12) which can rotate around a first axis (A) relative to the front leg, a supporting rod assembly (2) which can rotate around a second axis (B) relative to the front leg is also connected with the front leg (11), a supporting seat (4) which can rotate around a third axis (C) relative to the front leg and can be used for installing a seat assembly (3) is also arranged on the front leg (11), a linkage assembly (5) which can enable the front leg (11) and the rear leg (12) to be unfolded and fixed when a locking device is in a locking state and can drive the rear leg (12) to rotate and fold the front leg (11) when the supporting rod assembly (2) rotates and folds relative to the front leg (11) is arranged between the supporting rod assembly (2), a front wheel (111) is arranged on the front leg (11), and a rear wheel (121) is arranged on the rear leg (12). The folding structure is simple and convenient to fold.

Description

Baby carriage frame

[ field of technology ]

The utility model relates to a stroller frame.

[ background Art ]

With the development of society, the baby carriage has become a necessary tool for infants to travel. Parents pay more attention to the characteristics of easy folding, small size, convenient storage and the like of the child cart besides pursuing the basic requirements of safety and stability of the child cart. In view of this, at present, the child cart generally has a foldable function, and when in use, the cart is unfolded, and when not in use, the cart is folded, so that the child cart is convenient to carry, and the occupied space is reduced. The utility model further provides a novel embodiment.

The present utility model has been developed in response to the above-described drawbacks.

[ utility model ]

The utility model aims to overcome the defects of the prior art and provide the child cart frame which is simple in folding structure and convenient to fold.

The utility model is realized by the following technical scheme:

the utility model provides a children's shallow frame can follow the expansion position and remove to folding position after unlocking locking device, includes front leg 11, front leg 11 on be connected with relative its back leg 12 of rotating around first axis A, front leg 11 on still be connected with relative its stay bar subassembly 2 of rotating around second axis B, front leg 11 on still be equipped with relative its supporting seat 4 of rotating around third axis C and installing seat subassembly 3, stay bar subassembly 2, back leg 12 and front leg 11 between be equipped with and can make front leg 11 and back leg 12 expand fixedly and can drive the back leg 12 to the linkage subassembly 5 of forward leg 11 rotation folding when the relative front leg 11 rotation of stay bar subassembly 2, front leg 11 on be equipped with front wheel 111, back leg 12 on be equipped with rear wheel 121.

The linkage assembly 5 comprises a linkage piece 51 movably connected between the front leg 11 and the stay bar assembly 2, the linkage assembly 5 further comprises a transverse shaft 52 which is slidably connected on the rear leg 12 and transversely penetrates through the front leg 11, the stay bar assembly 2 and the linkage piece 51, and the stay bar assembly 2 is provided with a pushing part 21 which can push the transverse shaft 52 when rotating relative to the front leg 11, so that the transverse shaft 52 pushes the rear leg 12 to rotate towards the front leg 11.

The brace assembly 2 on be equipped with the horizontal axis of rotation 22 of wearing to establish preceding leg 11 and being connected to on the back leg 12, the linkage piece 51 include around the linkage piece body 511 of fourth axis D rotation connection on the brace assembly 2, the cross axle 52 establish in linkage piece body 511 front side, linkage piece body 511 rear side be equipped with the convex bulge 513 in preceding leg 11, preceding leg 11 on be equipped with and hold and supply the spout 112 that bulge 513 slided in, linkage piece body 511 on still be equipped with the first groove 5111 of stepping down that can step down for axis of rotation 22, fourth axis D and second axis B parallel.

The rear leg 12 is provided with a bar-shaped groove 122 which can enable the cross shaft 52 to slide in, the front leg 11 is provided with a second abdicating groove 113 which can abdicate the cross shaft 52 when the support rod assembly 2 pushes the cross shaft 52 to slide, the support rod assembly 2 is provided with a containing groove 23 which enables the cross shaft 52 to move in, and the pushing part is formed by the inner side wall of the containing groove 23.

The strip-shaped groove 122 is radially disposed on the rear leg 12.

The inner side wall of the accommodating groove 23 is an arc surface.

The locking device comprises a first locking component 61 arranged between the stay bar component 2 and the front leg 11, and a second locking component 62 arranged between the supporting seat 4 and the front leg 11 and capable of being unlocked by the stay bar component 2 when the stay bar component 2 rotates relative to the front leg 11.

The supporting rod assembly 2 comprises a supporting rod 24 rotatably connected to a front leg 11, a handle rod 25 capable of sliding relative to the supporting rod 24 is connected to the supporting rod 24, the first locking assembly 61 comprises a first locking position 611 arranged on the supporting rod 24, a first locking block 612 capable of sliding relative to the front leg 11 and being locked into or separated from the first locking position 611 is arranged on the front leg 11, a pushing sliding block 613 capable of sliding relative to the supporting rod 24 and pushing the first locking block 612 to be separated from the first locking position 611 is arranged in the supporting rod 24, a driving piece 614 capable of driving the pushing sliding block 613 to slide when being pushed is further arranged on the supporting rod 24, a driving part 251 capable of pushing the driving piece 614 to slide when the handle rod slides downwards relative to the supporting rod 24 is arranged on the handle rod 25, a first elastic reset piece 615 capable of resetting the pushing sliding block 613 is arranged between the front leg 11 and the first locking block 612, and a second elastic reset piece 616 capable of resetting the driving piece 614 is arranged between the driving piece 614 and the supporting rod 24.

The second locking component 62 comprises a locking rod 621 arranged on the supporting seat 4, a clamping hook 622 which can rotate relative to the front leg 11 and is locked or separated with the locking rod 621 is arranged on the front leg 11, a pushing component 623 which can slide relative to the front leg and push the clamping hook 622 to rotate is also arranged on the front leg 11, a pushing part 624 which can push the pushing component 623 to slide when the supporting rod component 2 rotates is arranged on the supporting rod component 2, and a fourth elastic reset component 625 which can reset the pushing component 623 is arranged between the pushing component 623 and the supporting rod component 2.

The lower end of the stay bar assembly 2 is provided with a driving groove 27, the bottom of the driving groove 27 is a cam surface, and the pushing part 624 is formed by the cam surface.

Compared with the prior art, the utility model has the following advantages:

1. when the folding support is required to be folded, the stay bar assembly is rotated and folded relative to the front leg, in the process, the linkage assembly enables the rear leg to be rotated and folded towards the front leg, and the support seat and the seat assembly are rotated and folded towards the front leg under the action of dead weight, so that the stay bar assembly and the rear leg are both folded onto the front leg finally. In actual operation, after the stay bar assembly rotates a certain angle relative to the front leg, the frame of the baby stroller can be lifted upwards, the stay bar assembly and the rear leg are both rotated towards the front leg to be close under the action of gravity, and the whole frame of the baby stroller is folded, so that the folding operation is simple and the folding operation is smoother.

2. When the supporting rod assembly rotates and folds relative to the front leg, the pushing part on the supporting rod assembly pushes the transverse shaft to slide relative to the rear leg, and the transverse shaft pushes the wall surface in the rear leg to enable the rear leg to rotate relative to the front leg and fold towards the front leg.

3. When the brace rod assembly is folded and rotated relative to the front leg, the pushing part on the brace rod assembly pushes the transverse shaft, the transverse shaft slides relative to the rear leg after being pushed, the linkage piece body and the protruding part are driven to move relative to the brace rod assembly in the sliding process of the transverse shaft, and at the moment, the protruding part is matched with the sliding groove to limit the sliding direction of the transverse shaft, so that the transverse shaft can push the rear leg to rotate towards the front leg.

[ description of the drawings ]

FIG. 1 is a perspective view of a child stroller frame of the present utility model;

FIG. 2 is one of the side views of the child stroller frame of the present utility model;

FIG. 3 is a second side view of the child stroller frame of the present utility model;

FIG. 4 is one of the cross-sectional views of the child stroller frame of the present utility model;

FIG. 5 is one of the exploded views of the child stroller frame of the present utility model;

FIG. 6 is a second exploded view of the stroller frame of the present utility model;

FIG. 7 is a third exploded view of the child stroller frame of the present utility model;

FIG. 8 is a second cross-sectional view of the child stroller frame of the present utility model;

FIG. 9 is one of the perspective views of the linkage in the stroller frame of the present utility model;

FIG. 10 is a second perspective view of the linkage in the stroller frame of the present utility model;

FIG. 11 is a third cross-sectional view of the child stroller frame of the present utility model;

FIG. 12 is a fourth cross-sectional view of the child stroller frame of the present utility model;

FIG. 13 is a fifth cross-sectional view of the child stroller frame of the present utility model;

FIG. 14 is a fifth exploded view of the stroller frame of the present utility model;

FIG. 15 is a sixth exploded view of the child stroller frame of the present utility model;

FIG. 16 is a seventh exploded view of the stroller frame of the present utility model;

FIG. 17 is an exploded view eighth of the stroller frame of the present utility model;

FIG. 18 is a ninth exploded view of the stroller frame of the present utility model;

FIG. 19 is one of the cross-sectional views of the mid-height adjustment assembly of the stroller frame of the present utility model;

FIG. 20 is a second cross-sectional view of the mid-height adjustment assembly of the stroller frame of the present utility model;

FIG. 21 is a state diagram of the stroller frame of the present utility model when folded;

fig. 22 is a state diagram of the stroller frame of the present utility model when the stroller frame is folded.

[ detailed description ] of the utility model

The utility model is further described below with reference to the accompanying drawings:

as shown in fig. 1 to 22, a stroller frame movable from an unfolded position to a folded position after unlocking a locking device, characterized in that: including preceding leg 11, preceding leg 11 on be connected with can be relative its back leg 12 around first axis A pivoted, preceding leg 11 on still be connected with can be relative its around second axis B pivoted vaulting pole subassembly 2, preceding leg 11 on still be equipped with can be relative its around third axis C pivoted and can install seat subassembly 3's supporting seat 4, vaulting pole subassembly 2, back leg 12 and preceding leg 11 between be equipped with can make preceding leg 11 and back leg 12 expand fixedly when locking device is in the locked state and can drive back leg 12 to the linkage subassembly 5 of preceding leg 11 pivoted when the relative preceding leg 11 of vaulting pole subassembly 2 is rotated and is folded, preceding leg 11 on be equipped with front wheel 111, back leg 12 on be equipped with rear wheel 121. When the folding support is required to be folded, the stay bar assembly 2 is rotated and folded relative to the front leg 11, in the process, the linkage assembly 5 enables the rear leg 12 to be rotated and folded towards the front leg 11, and the support seat 3 and the seat assembly 4 are rotated and folded towards the front leg 11 under the action of dead weight, so that the stay bar assembly 2 and the rear leg 12 are both folded onto the front leg 11 finally. In actual operation, after the stay bar assembly 2 rotates a certain angle relative to the front leg, the stroller frame can be lifted upwards, the stay bar assembly 2 and the rear leg 12 rotate towards the front leg 11 to be close under the action of gravity, and the whole stroller frame is folded, so that the folding operation is simple and the folding is smoother.

As shown in fig. 4 to 10, the linkage assembly 5 includes a linkage member 51 movably connected between the front leg 11 and the strut assembly 2, the linkage assembly 5 further includes a transverse shaft 52 slidably connected to the rear leg 12 and passing through the front leg 11, the strut assembly 2 and the linkage member 51, and the strut assembly 2 is provided with a pushing portion 21 capable of pushing the transverse shaft 52 when rotating relative to the front leg 11, so that the transverse shaft 52 pushes the rear leg 12 to rotate toward the front leg 11. When the brace rod assembly 2 rotates and folds relative to the front leg 11, the pushing part 21 on the brace rod assembly 2 pushes the transverse shaft 52 to slide relative to the rear leg 12, and the transverse shaft 52 pushes the wall surface in the rear leg 12 to enable the rear leg 12 to rotate relative to the front leg 11 and close and fold towards the front leg 11.

As shown in fig. 4 to 10, the brace assembly 2 is provided with a rotation shaft 22 transversely penetrating through the front leg 11 and connected to the rear leg 12, the linkage member 51 includes a linkage piece body 511 rotatably connected to the brace assembly 2 around a fourth axis D, the transverse shaft 52 is provided at the front side of the linkage piece body 511, the rear side of the linkage piece body 511 is provided with a protruding portion 513 protruding into the front leg 11, the front leg 11 is provided with a sliding groove 112 capable of accommodating and allowing the protruding portion 513 to slide inside, the linkage piece body 511 is further provided with a first abdicating groove 5111 capable of abdicating the rotation shaft 22, and the fourth axis D is parallel to the second axis B. When the brace rod assembly 2 is folded and rotated relative to the front leg 11, the pushing portion 21 on the brace rod assembly 2 pushes the transverse shaft 52, the transverse shaft 52 slides relative to the rear leg 12 after being pushed, the linkage piece body 511 and the protruding portion 512 are driven to move relative to the brace rod assembly 2 in the sliding process of the transverse shaft 52, and at the moment, the protruding portion 512 is matched with the sliding groove 122 to limit the sliding direction of the transverse shaft 52, and the transverse shaft 52 can push the rear leg 12 to rotate towards the front leg 11.

As shown in fig. 4 to 10, the rear leg 12 is provided with a bar-shaped groove 122 capable of sliding the transverse shaft 52, the front leg 11 is provided with a second yielding groove 113 capable of yielding the transverse shaft 52 when the brace rod assembly 2 pushes the transverse shaft 52 to slide, the brace rod assembly 2 is provided with a containing groove 23 for the transverse shaft 52 to move inside, and the pushing part is formed by the inner side wall of the containing groove 23. The inner side wall is an arc surface or an inclined surface, and the fourth axis D is parallel to the second axis B, so that the pushing portion 21 can push the transverse shaft 52 to slide when the stay rod assembly 2 rotates. The bar-shaped groove 122 is used for limiting the sliding range of the cross shaft 52, the inner wall of the bar-shaped groove 122 is used for pushing the cross shaft 52 to lean against to push the rear leg 12 to approach the front leg 11, and the second abdication groove 113 abdies the cross shaft 52, so that the situation that the cross shaft 52 is blocked with the front leg 11 is avoided.

As shown in fig. 5 to 7, the strip-shaped groove 122 is provided radially on the rear leg 12. So that the rear leg 12 rotates toward the front leg 11 as the rear leg 12 is urged by the transverse shaft 52.

As shown in fig. 4 to 10, the inner side wall of the accommodating groove 23 is an arc surface.

As shown in fig. 11 to 18, the locking means comprises a first locking assembly 61 provided between the stay assembly 2 and the front leg 11. The first locking assembly 61 is used to lock the strut assembly 2 and the front leg 11 in the deployed state, so that the stroller frame is more stable and safer when deployed.

As shown in fig. 11 to 18, the locking device further comprises a second locking assembly 62 between the support seat 4 and the front leg 11 and capable of being unlocked by the stay assembly 2 when the stay assembly 2 is rotated relative to the front leg 11. The second locking assembly 62 is used for locking the support seat 4 and the front leg 11 in the unfolded state, so that the stroller frame is more stable and safer when unfolded.

As shown in fig. 11 to 18, the brace rod assembly 2 includes a support rod 24 rotatably connected to the front leg 11, a handle rod 25 capable of sliding relative to the support rod 24 is connected to the support rod 24, the first locking assembly 61 includes a first locking position 611 provided on the support rod 24, the front leg 11 is provided with a first locking block 612 capable of sliding relative to the front leg and locking into or separating from the first locking position 611, the support rod 24 is internally provided with a pushing slider 613 capable of sliding relative to the support rod to push the first locking block 612 out of the first locking position 611, the support rod 24 is further provided with a driving member 614 capable of driving the pushing slider 613 to slide when being pushed, the handle rod 25 is provided with a driving portion 251 capable of pushing the driving member 614 to slide when the handle rod slides downwards relative to the support rod 24, a first elastic reset member 615 capable of resetting the sliding the slider 613 is provided between the front leg 11 and the first locking block 612, and the support rod 24 is provided with a second elastic reset member 616 capable of resetting the driving member 614. When the support rod assembly 2 needs to be rotated, the handle rod 25 is pushed to slide downwards, the driving part 251 on the handle rod 25 pushes the pushing sliding block 613 to slide downwards, so that the first locking block 612 slides transversely relative to the front leg 11, the first locking block 612 is gradually separated from the first locking position 611 during sliding, at the moment, the first locking assembly 61 is unlocked, and the support rod 24 can rotate relative to the front leg 11.

As shown in fig. 11 to 18, the pushing slider 613 is provided with a protruding column 6131 protruding outwards, and the driving member 614 is provided with a pushing slot 6141 capable of accommodating the protruding column 6131 and pushing the protruding column 6131 to slide when the driving member 614 slides. The inclined surface on the pushing slot 6141 pushes the convex column 6131 to move forward when the driving member 614 slides downward, and pushes the convex column 6131 to move backward when the driving member 614 slides upward, and the pushing slider 613 can be pushed by the driving member 614 to slide forward and backward when the driving member 614 moves.

As shown in fig. 19 to 20, a height adjusting assembly 26 capable of adjusting the height between the handle bar 25 and the support bar 23 is provided between the support bar 23 and the handle bar 25, the height adjusting assembly 26 comprises a plurality of adjusting positions 261 provided on the support bar 23, a clamping tongue 262 capable of sliding transversely relative to the handle bar 25 is provided in the handle bar 25, a sliding seat 263 capable of sliding relative to the handle bar to push the clamping tongue 262 out of the adjusting positions 261 is further provided on the handle bar 25, an operating member 264 is further provided on the handle bar 25, an operating member 265 is provided between the operating member 264 and the sliding seat 263, and a third elastic reset member 266 is provided between the clamping tongue 262 and the handle bar 25. When the position between the handle bar 25 and the support bar 23 needs to be adjusted, the operation member 264 is operated, the operation member 264 pulls the sliding seat 263 to slide through the pull rope, the sliding seat 263 drives the clamping tongue 262 to slide when sliding so as to enable the clamping tongue 262 to be separated from the adjusting position 261, then the position of the handle bar 25 relative to the support bar 23 is adjusted, the operation member 264 is released, and the third elastic reset member 266 pushes the clamping tongue 262 to reset and clamp into the corresponding adjusting position 261.

As shown in fig. 11 to 18, the second locking assembly 62 includes a latch rod 621 disposed on the support base 4, the front leg 11 is provided with a hook 622 capable of rotating relative to the front leg to latch or separate from the latch rod 621, the front leg 11 is further provided with a pushing member 623 capable of sliding relative to the front leg to push the hook 622 to rotate, and the support rod assembly 2 is provided with a pushing portion 624 capable of pushing the pushing member 623 to slide when the support rod assembly rotates. The pushing portion 624 is a cambered surface provided on the supporting rod assembly 2, so that when the supporting rod assembly 2 rotates, the pushing portion 624 gradually abuts against the wall surface of the pushing member 623 to push the pushing member 623 to slide transversely, when the pushing member 623 slides, the hook 622 is pushed to rotate relative to the front leg 11, when the hook 622 rotates, the hook 622 is separated from the locking rod 621 on the supporting seat 4, and at the moment, the supporting seat 4 can rotate towards the front leg 11.

As shown in fig. 11 to 18, the lower end of the brace assembly 2 is provided with a driving groove 27, the bottom of the driving groove 27 is a cam surface, and the pushing portion 624 is formed by the cam surface. The cam surface slides the pusher 623 as the strut assembly 2 rotates, unlocking the second locking assembly 62.

The pushing member 623 is provided with a protruding positioning portion 6231, and the strut assembly 2 is further provided with a positioning groove 28 into which the positioning portion 6231 can be clamped when the strut assembly 2 moves to the folded position. The positioning groove 28 is used for locking the positioning part 6231 when the stroller frame is in a folded state, so that the support base 4 is fixed with the front leg 11, and a certain force needs to be applied when the support base 4 needs to be unfolded, so that the positioning part 6231 is extruded out of the positioning groove 28 through the arc surface on the positioning part 6231.

Claims

1. The utility model provides a children's shallow frame, can remove to the folding position from the unfolding position after unlocking locking device which characterized in that: comprises a front leg (11), the front leg (11) on be connected with relative its back leg (12) of rotating around first axis (A), front leg (11) on still be connected with relative its back leg (11) pivoted vaulting pole subassembly (2) around second axis (B), front leg (11) on still be equipped with relative its back seat (4) of rotating around third axis (C) and installing seat subassembly (3), vaulting pole subassembly (2), back leg (12) and front leg (11) between be equipped with and can make front leg (11) and back leg (12) expand fixedly and can drive back leg (12) to link subassembly (5) of front leg (11) pivoted when vaulting pole subassembly (2) are rotated relative front leg (11), front leg (11) on be equipped with front wheel (111), back leg (12) on be equipped with rear wheel (121), subassembly (5) including the swing joint be in front leg (11) and the linkage subassembly (2) and link subassembly (51) that link and front leg (12) are worn in the linkage (51) of front leg (2) and link subassembly (51), the brace rod assembly (2) is provided with a pushing part (21) which can push the transverse shaft (52) when the brace rod assembly rotates relative to the front leg (11) so that the transverse shaft (52) pushes the rear leg (12) to rotate towards the front leg (11).

2. The stroller frame of claim 1, wherein: the utility model provides a bracing subassembly (2) on be equipped with horizontal front leg (11) of wearing and being connected to axis of rotation (22) on back leg (12), linkage (51) including link piece body (511) on bracing subassembly (2) are connected in rotation around fourth axis (D), cross axle (52) establish in link piece body (511) front side, link piece body (511) rear side be equipped with bulge (513) forward leg (11) internal convex, front leg (11) on be equipped with can hold and can supply bulge (513) including gliding spout (112), link piece body (511) on still be equipped with first groove (5111) of stepping down for axis of rotation (22), fourth axis (D) and second axis (B) parallel.

3. The stroller frame of claim 2, wherein: the rear leg (12) on be equipped with can supply cross axle (52) to slide bar groove (122) including, front leg (11) on be equipped with can be for the second groove (113) of stepping down of cross axle (52) when vaulting pole subassembly (2) top pushes away cross axle (52) slip, vaulting pole subassembly (2) on be equipped with and supply cross axle (52) to move about holding tank (23), the top push away the portion and constitute by the inside wall of holding tank (23).

4. A stroller frame according to claim 3, characterized in that: the strip-shaped groove (122) is radially arranged on the rear leg (12).

5. A stroller frame according to claim 3, characterized in that: the inner side wall of the accommodating groove (23) is an arc surface.

6. The stroller frame of claim 1, wherein: the locking device comprises a first locking component (61) arranged between the stay bar component (2) and the front leg (11), and a second locking component (62) arranged between the supporting seat (4) and the front leg (11) and capable of being unlocked by the stay bar component (2) when the stay bar component (2) rotates relative to the front leg (11).

7. The stroller frame of claim 6, wherein: the supporting rod assembly (2) comprises a supporting rod (24) connected to the front leg (11) in a rotating manner, a handle rod (25) capable of sliding relative to the supporting rod is connected to the supporting rod (24), the first locking assembly (61) comprises a first locking position (611) arranged on the supporting rod (24), the front leg (11) is provided with a first locking block (612) capable of sliding relative to the front leg and clamping or separating from the first locking position (611), the supporting rod (24) is internally provided with a pushing sliding block (613) capable of sliding relative to the supporting rod and pushing the first locking block (612) to separate from the first locking position (611), the supporting rod (24) is further provided with a driving piece (614) capable of driving the pushing sliding block (613) to slide when being pushed, the handle rod (25) is provided with a driving part (251) capable of pushing the driving piece (614) to slide when the handle rod (24) slides downwards, and the front leg (11) and the first locking block (612) are provided with a first locking block (612) capable of clamping or separating from the first locking block, and the supporting rod (24) is provided with a first elastic reset piece (614) capable of resetting the driving piece (614) when the first elastic reset piece (616) is provided with the driving piece (614).

8. The stroller frame of claim 6, wherein: the second locking component (62) comprises a clamping rod (621) arranged on the supporting seat (4), a clamping hook (622) which can rotate relative to the front leg (11) and is clamped or separated from the clamping rod (621) is arranged on the front leg (11), a pushing component (623) which can slide relative to the front leg and push the clamping hook (622) to rotate is further arranged on the front leg (11), a pushing part (624) which can push the pushing component (623) to slide when the pushing component rotates is arranged on the supporting rod component (2), and a fourth elastic reset component (625) which can enable the pushing component (623) to reset is arranged between the pushing component (623) and the supporting rod component (2).

9. The stroller frame of claim 8, wherein: the lower end of the stay bar assembly (2) is provided with a driving groove (27), the bottom of the driving groove (27) is a cam surface, and the pushing part (624) is formed by the cam surface.