CN210810082U - Chair back and chair with same - Google Patents

Abstract

The utility model relates to a seat field especially relates to a back of the chair to and have seat of this back of the chair. A chair back comprising a chair back frame and two back units; the lower end part of the chair back frame is used for being connected to the rear end part of the chair seat or the tilting tray below the chair seat, the two backrest units are respectively connected to the front end surface of the chair back frame through elastic twisting components, and the front end surfaces of the two backrest units are respectively attached to muscles on two sides of the spinal column of a seated person; the backrest unit can be elastically twisted along the elastic twisting component, and the twisting range of the backrest unit is limited by the backrest rear frame. The chair back can twist on the backrest unit, so that the use comfort of a user is improved, and the back is prevented from being sore due to the fact that the back keeps the same posture for a long time; the twisting range of the backrest unit is limited, and the use of the seat by the seat occupant is more relieved.

Description

Chair back and chair with same

Technical Field

The utility model relates to a seat field especially relates to a back of the chair to and have seat of this back of the chair.

Background

The seat is one of furniture varieties and is a seat with a long history. With the development of industrial technology, the chair is not only greatly improved in the aspects of attractive appearance and use comfort, but also greatly changed in the production mode. Modern chairs are mainly produced in a modular manner, so that the survival efficiency of the chair is greatly improved, and the chair generally comprises a base, a chair seat and a chair back, wherein the chair back is used for supporting the back of a seated person. The traditional chair back generally comprises a fixed type and an adjustable angle type, wherein the adjustable angle type means that the tilting angle of the chair back can be adjusted so as to provide different support angles corresponding to different riding requirements; the adjustable angle seat back is also fixed during a particular ride, otherwise it does not provide effective support. However, maintaining the same seating position for a long period of time can be tiring and the seat back of such seats can no longer be seated with fine adjustment of the swing.

A chair with an adjustable chair back is described in the patent document of the Chinese utility model with the publication number of 'CN 203468073U', which discloses that the chair back is composed of a backrest, an elastic plug-in, an upper frame of the chair back and a lower frame of the chair back, and the backrest is fixed at two sides of the upper frame of the chair back through the elastic plug-in; the upper end of the lower frame of the chair back is provided with a chair back connecting part which is provided with a round convex block; the chair back connecting part is matched with the lower end part of the chair back upper frame, the lower end part of the chair back upper frame is provided with a circular bulge protruding outwards, the circular bulge is matched with the circular bump, and the chair back connecting part of the chair back lower frame is sleeved in the lower end part of the chair back upper frame and clamps the circular bump into the circular bulge. Referring to fig. 1 of the drawings, the double-back chair structure disclosed by the scheme is characterized in that a T-shaped frame is formed by a chair back upper frame and a chair back lower frame, and a backrest is connected to the T-shaped frame through an elastic insert. The laminating of person's back is on the terminal surface before the back during the use, and elasticity plug-in components have certain elasticity, and the back can wrench movement to promote person's use comfort, avoid the back to keep same posture for a long time and ache. However, in the scheme, the T-shaped frame only plays a supporting role for the backrest, and the twisting effect of the elastic twisting piece is good, so that when the back of the rider twists, the twisting range of the backrest is not restricted. Generally, whether the twisting in the left-right direction is limited or not affects the use, but when the user twists upward, that is, when the back of the user leans back backward, the angle at which the back can twist backward is large, and the user may have a possibility that the seat is afraid of falling, so that the user unconsciously limits the range of stretching the body, and cannot obtain a better relaxation effect.

Disclosure of Invention

In order to solve the above problems, a first object of the present invention is to provide a chair back, which can be twisted on a backrest unit, thereby improving the comfort level of the rider and avoiding the back from being sore due to keeping the same posture for a long time; the twisting range of the backrest unit is limited, and the use of the seat by the seat occupant is more relieved. A second object of the present invention is to provide a seat having the above-mentioned back.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a chair back, characterized in that: the chair back comprises a chair back frame and two backrest units; the lower end part of the chair back frame is used for being connected to the rear end part of the chair seat or the tilting tray below the chair seat, the two backrest units are respectively connected to the front end surface of the chair back frame through elastic twisting components, and the front end surfaces of the two backrest units are respectively attached to muscles on two sides of the spinal column of a seated person; the backrest unit can be elastically twisted along the elastic twisting component, and the twisting range of the backrest unit is limited by the backrest rear frame.

The utility model adopts the technical scheme, which relates to a chair back, comprising a chair back frame and two backrest units, wherein the two backrest units are respectively connected with the front end surface of the chair back frame through elastic twisting components; the chair back frame limits the twist range of the back unit. The back of the chair that this technical scheme relates combines the steadiness of present cycle racing chair back of the chair frame and the travelling comfort of two back of the body chairs to have above-mentioned steadiness and travelling comfort concurrently. When the chair back frame is used, the front end surfaces of the two back units are used for respectively fitting muscles on two sides of the spinal column of a user, when the user twists the back, the chair back frame limits the back units, and therefore the situation that the user is worried about twisting transition to cause the chair to topple over is avoided. In conclusion, the chair back can twist the backrest units, so that the use comfort of the passengers is improved, and the back is prevented from being sore due to the fact that the back keeps the same posture for a long time; the twisting range of the backrest unit is limited, and the use of the seat by the seat occupant is more relieved.

Preferably, the seat back frame is higher than the backrest unit in the height direction, and a headrest is provided on the seat back frame above the backrest unit. Among this technical scheme, be equipped with the headrest on the back of the chair after-frame of back unit top, the headrest can support with the head laminating of person of taking, and the support that the person of messenger experienced when leaning on is more stable.

Preferably, the front end surface of the backrest unit is in an arc shape that the right inner end gradually deviates to the front from the outer end; the arc shape conforms to the shape of the sides of the spine of the user's back.

Preferably, the seat back frame has side wings extending forward at both side edges thereof, and the outer ends of the back unit extend forward of the side wings to limit a twisting range of the back unit in the outer rear direction.

Preferably, the elastic twisting component comprises a base which is embedded in the back frame of the chair, and an elastic rubber part of which the middle part is connected to the base; the elastic rubber piece comprises an upper connecting end and a lower connecting end which are respectively connected to the rear end face of the backrest unit, and the upper connecting end and the lower connecting end are respectively positioned at the upper side and the lower side of the middle connecting part.

Preferably, the seat back frame comprises a seat back frame forming a main body shape of the seat back frame, the seat back frame comprises a cross member, and the base of the elastic twisting assembly is fixed on the cross member. In the technical scheme as in the chinese utility model patent document of bulletin number "CN 203468073U", the back is connected on T style of calligraphy frame through elastic rubber spare, and this T style of calligraphy frame has guaranteed the joint strength of elastic rubber spare's base, and in this scheme, though omitted T style of calligraphy frame and replaced it for the chair back frame, the back of the chair back frame inside crossbeam has guaranteed the installation intensity of base, has also further guaranteed the stability of elastic rubber spare wrench movement process.

A seat, characterized by: comprising a chair back as claimed in any one of the preceding claims.

Preferably, the lower end of the chair back frame is connected to the rear end of the chair seat through an angle adjusting mechanism, and the chair back frame can rotate relative to the chair seat along the angle adjusting mechanism. In this technical scheme, adopted the chair back frame to replace the T style of calligraphy frame among the technical scheme of the chinese utility model patent text record of bulletin number "CN 203468073U" to make two back of the body chairs can combine together with angle adjustment mechanism, like the scheme that records in above-mentioned patent document, two back of the body chair structures can' T realize inclining and facing upward the regulation with angle adjustment mechanism combination at all, thereby the hypsokinesis in-process must lead to the seat to overturn. In the scheme, the double-back chair and the angle adjusting mechanism are combined, when the chair back is adjusted to the position of 120-150 degrees, a rider leans on the chair back, the back is supported by the two backrest units, the head is supported by the headrest, and the backrest units can be twisted, so that the use comfort is greatly improved.

Preferably, the angle adjusting mechanism comprises a chassis fixed on the side surface of the seat, a rocker arm hinged with the chassis, a torsion spring for providing resetting force for the rocker arm, and a handle limiting assembly for limiting the rotation of the rocker arm; the center end of the torsion spring is fixed on a hinged point of the rocker arm and the chassis, and the movable end of the torsion spring is connected to the rocker arm.

Preferably, the rocker arm is provided with an arc-shaped tooth block, and the arc-shaped tooth block takes a hinged point of the rocker arm and the chassis as a circle center; the handle limiting assembly comprises a limiting plate hinged to the chassis, a handle driving the limiting plate to swing along the hinged end of the handle and a tension spring driving the handle to reset; a tooth part arranged on the limiting plate is matched with the arc-shaped tooth block on the rocker arm; when the tooth part of the limiting plate is meshed with the arc-shaped tooth block of the rocker arm, the rocker arm is locked and positioned; when the tooth part of the limiting plate is separated from the arc-shaped tooth block of the rocker arm, the rocker arm is movably arranged relative to the chassis. The inner end part of the handle is provided with a clamping plate assembly, one end of the clamping plate assembly is hinged on the chassis, and the handle can rotate along the hinged end; the other end of the clamping plate component is connected with the chassis through a tension spring; the movable end of the limiting plate is located between the two end portions of the clamping plate assembly, and the clamping plate assembly acts on the movable end of the limiting plate to drive the limiting plate to swing.

In the angle adjusting mechanism, the rocker arm is hinged with the chassis, the arc-shaped tooth block and the rocker arm concentrically and synchronously rotate, a limiting plate in the handle limiting assembly is provided with a tooth part which is meshed with the arc-shaped tooth block, and a rider can adjust the limiting plate through the handle so as to control whether to lock the arc-shaped tooth block and the chair back; and the handle can be reset mechanically through the arranged tension spring, so that the rider can use the electric bicycle more conveniently. The tilting mechanism provides resetting elasticity through the torsion spring, so that the resetting flexibility of the chair back is better; and the handle limit component can timely and effectively limit the angle of the chair back.

Drawings

Fig. 1 is a schematic view of a chair back structure described in embodiment 1.

Fig. 2 is a schematic view of the assembly of the chair back described in embodiment 1.

Fig. 3 is a schematic view of a seat structure in embodiment 2.

Fig. 4 is a schematic structural view of the angle adjustment mechanism.

Fig. 5 is a schematic diagram of the angle adjustment mechanism.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and to simplify the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "a plurality" means two or more unless explicitly defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by 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.

Example 1:

a chair back as shown in figures 1 to 2, the chair back comprising a back frame 1 and two back units 2. The lower tip of chair back frame 1 is used for connecting on the seat support rear end portion or on the tray of inclining of seat support below, and two back units 2 are connected on the preceding terminal surface of chair back frame 1 through elasticity wrench movement subassembly respectively, and the preceding terminal surface of two back units 2 is used for laminating the muscle of person's backbone both sides respectively. The backrest unit 2 can be elastically twisted along the elastic twisting component, and the twisting range of the backrest unit 2 is limited by the chair back frame 1. The chair back frame 1 is higher than the backrest unit 2 in the height direction, and a headrest 3 is arranged on the chair back frame 1 above the backrest unit 2. Among this technical scheme, be equipped with headrest 3 on the back of the chair back rear frame 1 of back unit 2 top, headrest 3 can support with the head laminating of person of taking, and the support that the person of taking experienced when making the person of taking back is leaned on is more stable.

The above-mentioned chair back frame 1 limits the twisting range of the back unit 2, and it can be understood from the accompanying drawings that the frame body of the chair back frame 1 blocks the twisting of the back unit 2, thereby limiting the twisting range. If the backrest unit 2 is twisted upward, the upper end of the backrest unit 2 abuts against the backrest rear frame 1 after being twisted to a certain angle, so that the backrest unit cannot be twisted backward. As shown, the back unit 2 is also restrained by this method when it is twisted inward and outward. In a specific embodiment, the front end surface of the backrest unit 2 has an arc shape that the right inner end gradually deviates to the front from the outer end, and the arc shape fits the two sides of the spine of the back of the user. As shown in the figures, two side edges of the chair back frame 1 are provided with side wings 4 extending forwards, the outer side end of the backrest unit 2 extends to the front of the side wings 4, and the side wings 4 limit the twisting range of the backrest unit 2 at the outer side and the rear.

The elastic twisting component can adopt various elastic structures such as rubber pieces, springs and the like, and can be referred to as a spring connecting structure recorded in a Chinese utility model patent text with the publication number of "CN 203468072U", namely the invention creation name of 'a seat back connecting structure'; the invention also refers to an elastic rubber piece structure recorded in Chinese patent text with the publication number of 'CN 104072822B', namely 'an elastic rubber piece for connecting chair backs and a processing technology thereof'. In the embodiment shown in the figure, the structure of the elastic rubber member described in the patent document with the publication number "CN 104072822B" is used, and specifically, the technical solution described in the patent document with the publication number "CN 203468073U" of the chinese utility model can be also used. Specifically, the elastic twist assembly includes a base 51 provided in the seat back frame 1, and an elastic rubber member 52 having a middle portion connected to the base 51. The elastic rubber member 52 includes an upper connection end 52a and a lower connection end 52b connected to the rear end surface of the back unit 2, respectively, and the upper connection end 52a and the lower connection end 52b are located at the upper and lower sides of the middle connection portion 52c, respectively.

On the basis of the scheme, the chair back frame 1 comprises a chair back frame which forms the main body shape of the chair back frame 1, and a core and a surface layer are coated on the chair back frame during production so as to form the chair back frame 1. The back frame 11 comprises an outer frame 11a forming the main body outline of the back frame 1, a side frame 11b forming the main body outline of the side wing 4 and a cross beam 11c arranged inside the outer frame, and the base 51 of the elastic twisting component is fixed on the cross beam 11 c. Like in the technical scheme of the chinese utility model patent document of publication number "CN 203468073U", the back is connected on T-shaped frame through elastic rubber 52, and this T-shaped frame has guaranteed the joint strength of base 51 of elastic rubber 52, in this scheme, though omitted T-shaped frame and replaced it for chair back frame 1, the inside crossbeam 11c of chair back frame 1 has guaranteed the mounting strength of base 51, has also further guaranteed the stability of elastic rubber 52 process of wriggling.

The embodiment relates to a chair back which comprises a chair back frame 1 and two backrest units 2, wherein the two backrest units 2 are respectively connected to the front end surface of the chair back frame 1 through elastic twisting components. The seat back frame 1 limits the twisting range of the back unit 2. The back that this technical scheme relates combines the steadiness of present cycle racing chair back frame 11 and the travelling comfort of two back chairs to have above-mentioned steadiness and travelling comfort concurrently. During the use, the preceding terminal surface of two back units 2 is used for laminating the muscle of person's backbone both sides respectively, and when the person of taking wrench movement back, back of the chair frame 11 is restricted back unit 2 to avoided the person of taking worry to twist the transition and lead to the condition emergence that the seat topples over. In conclusion, the chair back can twist the backrest unit 2, so that the use comfort of the seat occupant is improved, and the back is prevented from being sore due to the fact that the back keeps the same posture for a long time. The twisting range of the back unit 2 is limited, and the use of the seat by the occupant is more relieved.

Example 2:

as shown in fig. 3, the present embodiment relates to a seat including the seat back described in embodiment 1.

In a specific embodiment, the lower end of the chair back frame 1 is connected to the rear end of the seat 7 via an angle adjusting mechanism 6, and the chair back frame 1 can rotate relative to the seat 7 along the angle adjusting mechanism 6. In this technical scheme, adopted back of the chair back after-frame 1 to replace the T style of calligraphy frame in the technical scheme of the chinese utility model patent text of bulletin number "CN 203468073U" record to make two back of the body chairs can combine together with angle adjustment mechanism 6, like the scheme that records in the above-mentioned patent document, two back of the body chair structures can' T realize inclining and facing upward the regulation with angle adjustment mechanism 6 combination at all, thereby the back of the body chair in-process must lead to the seat to overturn. In the scheme, the double-back chair is combined with the angle adjusting mechanism 6, when the chair back is adjusted to the position of 120-150 degrees, a rider leans on the chair back, the back is supported by the two backrest units 2, the head is supported by the headrest 3, and the backrest units 2 can be twisted, so that the use comfort is greatly improved.

The angle adjusting mechanism 6 may adopt various angle adjusting mechanisms used in the field, and the disclosure number is "CN 208624979U", the invention provides the angle adjusting mechanism 6 described in the patent text of the chinese utility model named "angle adjusting mechanism and electronic contest chair"; or the invention is a seat back angle adjusting mechanism recorded in the Chinese utility model patent document with the publication number of CN2618805Y and the name of seat back angle adjusting mechanism.

In the embodiment shown in fig. 4 and 5, the angle adjustment mechanism 6 comprises a bottom plate 61 fixed on the side of the seat 7, a rocker arm 62 hinged to the bottom plate 61, a torsion spring 63 providing a return force to the rocker arm 62, and a handle stop assembly limiting the rotation of the rocker arm 62. The center end of the torsion spring 63 is fixed on the hinge point of the rocker arm 62 and the chassis 61, and the movable end of the torsion spring 63 is connected to the rocker arm 62.

The rocker arm 62 is provided with an arc-shaped tooth block 64, and the arc-shaped tooth block 64 takes a hinge point of the rocker arm 62 and the chassis 61 as a circle center. The handle limiting assembly comprises a limiting plate 65 hinged to the chassis 61, a handle 66 driving the limiting plate 65 to swing along the hinged end of the handle, and a tension spring 67 driving the handle 66 to reset. The limiting plate 65 is provided with a tooth part which is matched with the arc-shaped tooth block 64 on the rocker arm 62. When the toothed part of the retainer plate 65 is engaged with the arc-shaped toothed block 64 of the rocker arm 62, the rocker arm 62 is locked in position. When the toothed part of the limit plate 65 is disengaged from the arc-shaped toothed block 64 of the rocker arm 62, the rocker arm 62 is movably arranged relative to the chassis 61. The handle 66 is provided at its inner end with a cleat assembly 68, one end of the cleat assembly 68 being hinged to the chassis 61, the handle 66 being able to rotate along this hinged end. The other end of the clamping plate assembly 68 is connected with the bottom plate 61 through a tension spring 67. The movable end of the limiting plate 65 is located between the two ends of the clamping plate assembly 68, and the clamping plate assembly 68 acts on the movable end of the limiting plate 65 to drive the limiting plate 65 to swing.

In the angle adjusting mechanism 6, the rocker arm 62 is hinged to the chassis 61, the arc-shaped tooth block 64 and the rocker arm 62 rotate concentrically and synchronously, a tooth part is arranged on a limit plate 65 in a limit component of the handle 66 and meshed with the arc-shaped tooth block 64, and a rider can adjust the limit plate 65 through the handle 66 so as to control whether to lock the arc-shaped tooth block 64 and the chair back. And the handle 66 can be reset mechanically through the arranged tension spring 67, so that the use of the rider is more convenient. The tilting mechanism provides resetting elasticity through the torsion spring 63, and the resetting flexibility of the chair back is better. And the chair back angle can be timely and effectively limited by the handle 66 limiting component.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., 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. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the principles and spirit of the present invention.

Claims (10)

1. A chair back, characterized in that: the chair back comprises a chair back frame (1) and two backrest units (2); the lower end part of the chair back frame (1) is used for being connected to the rear end part of the chair seat (7) or a tilting tray below the chair seat (7), the two backrest units (2) are respectively connected to the front end surface of the chair back frame (1) through elastic twisting components, and the front end surfaces of the two backrest units (2) are respectively attached to muscles on two sides of the spine of a seat occupant; the backrest unit (2) can elastically twist along the elastic twisting component, and the twisting range of the backrest unit (2) is limited by the backrest rear frame (1).

2. The chair back of claim 1, wherein: the chair back frame (1) is higher than the backrest unit (2) in the height direction, and a headrest (3) is arranged on the chair back frame (1) above the backrest unit (2).

3. The chair back of claim 1, wherein: the front end face of the backrest unit (2) is in an arc shape that the right inner side end gradually deflects to the front from the outer side end.

4. A chair back as claimed in claim 3, wherein: the chair back frame is characterized in that two side edges of the chair back frame (1) are provided with side wings (4) extending forwards, the outer side end of the backrest unit (2) extends to the front of the side wings (4), and the side wings (4) limit the twisting range of the backrest unit (2) in the rear of the outer side.

5. A chair back according to any one of claims 1 to 3, wherein: the elastic twisting component comprises a base (51) embedded in the chair back frame (1) and an elastic rubber piece (52) with the middle part connected to the base (51); the elastic rubber piece (52) comprises an upper connecting end (52a) and a lower connecting end (52b) which are respectively connected to the rear end face of the backrest unit (2), and the upper connecting end (52a) and the lower connecting end (52b) are respectively positioned at the upper side and the lower side of a middle connecting part (52 c).

6. The chair back of claim 5, wherein: the chair back frame (1) comprises a chair back frame (11) forming a main body shape of the chair back frame (1), the chair back frame (11) comprises a cross beam (11c), and a base (51) of the elastic twisting component is fixed on the cross beam (11 c).

7. A seat, characterized by: comprising a chair back as claimed in any one of claims 1 to 6.

8. A seat according to claim 7, wherein: the lower tip of chair back frame (1) passes through angle adjustment mechanism (6) and connects on seat support (7) rear end portion, and back of the chair back frame (1) can be followed angle adjustment mechanism (6) rotates relative seat support (7).

9. A seat according to claim 8, wherein: the angle adjusting mechanism (6) comprises a chassis (61) fixed on the side surface of the seat (7), a rocker arm (62) hinged with the chassis (61), a torsion spring (63) providing a resetting force for the rocker arm (62), and a handle (66) limiting component limiting the rotation of the rocker arm (62); the center end of the torsion spring (63) is fixed on a hinged point of the rocker arm (62) and the chassis (61), and the movable end of the torsion spring (63) is connected to the rocker arm (62).

10. A seat according to claim 9, wherein: an arc-shaped tooth block (64) is arranged on the rocker arm (62), and the arc-shaped tooth block (64) takes the hinged point of the rocker arm (62) and the chassis (61) as the center of a circle; the handle (66) limiting assembly comprises a limiting plate (65) hinged to the chassis (61), a handle (66) driving the limiting plate (65) to swing along the hinged end of the limiting plate, and a tension spring (67) driving the handle (66) to reset; the limiting plate (65) is provided with a tooth part which is matched with an arc-shaped tooth block (64) on the rocker arm (62); when the tooth part of the limit plate (65) is meshed with the arc-shaped tooth block (64) of the rocker arm (62), the rocker arm (62) is locked and positioned; when the tooth part of the limiting plate (65) is separated from the arc-shaped tooth block (64) of the rocker arm (62), the rocker arm (62) is movably arranged relative to the chassis (61).

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