Backrest of seat and seat

Abstract

The utility model discloses a backrest of a seat and the seat. The backrest of the seat comprises a backrest main body and a backrest body, a waist support; the lower end of the sleeve assembly and the lower end of the outer sleeve piece are rotationally connected with the backrest body, the upper end of the inner sleeve piece and the waist support, the inner sleeve piece is movably arranged in the outer sleeve piece and selectively extends out of the upper end of the outer sleeve piece, a first locking part is arranged on the inner sleeve piece, and a second locking part is arranged in the outer sleeve piece; and the first locking part and the second locking part are selectively locked and matched. Therefore, the lower end of the outer sleeve part is rotatably connected with the backrest main body, the upper end of the inner sleeve part is rotatably connected with the waist support, and the inner sleeve part is movably arranged in the outer sleeve part and selectively extends out of the upper end of the outer sleeve part, so that the waist support is selectively allowed to move forwards or backwards relative to the backrest main body; and the inner sleeve piece and the outer sleeve piece are selectively locked and matched, so that the front-back position adjustment of the waist support can be realized, the comfort of a user is improved, the structure is simple and reliable, and the operation is convenient and stable.

Description

Technical Field

[0001] This utility model relates to the field of seating technology, and in particular to a seat back and seat. Background Technology

[0002] With the development of technology and the improvement of users' living standards, people have higher and higher requirements for seat comfort. Some seat structures are equipped with lumbar support on the backrest. Lumbar support can provide better lumbar support, reduce the pressure on the back muscles when sitting for a long time, and thus improve the user's comfort.

[0003] In related technologies, some seats have an integrated backrest and lumbar support design, which only allows adjustment of the overall angle of the backrest and lumbar support; while some seats have an adjustable lumbar support structure on the backrest, their structure is relatively complex, takes up a lot of space, and the ease of adjustment and stability of the lumbar support are poor, resulting in a low user experience. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one objective of the present invention is to provide a seat back that is not only simple in structure and stable and reliable, but also allows for fore-and-aft adjustment of lumbar support.

[0005] This utility model further proposes a seat.

[0006] The seat backrest according to this utility model includes: a backrest body, the backrest body being provided with an avoidance groove; a lumbar support, the lumbar support being disposed in the avoidance groove; and a sleeve assembly, the sleeve assembly including an outer sleeve and an inner sleeve, the lower end of the outer sleeve being rotatably connected to the backrest body, the upper end of the inner sleeve being rotatably connected to the lumbar support, the inner sleeve being movably disposed within the outer sleeve and selectively extending from the upper end of the outer sleeve to selectively allow the lumbar support to move forward or backward relative to the backrest body, the inner sleeve being provided with a first locking part, and the outer sleeve being provided with a second locking part, the first locking part and the second locking part being selectively locked together.

[0007] Therefore, by rotatably connecting the lower end of the outer sleeve to the backrest body and the upper end of the inner sleeve to the lumbar support, and by movably setting the inner sleeve inside the outer sleeve and selectively extending it from the upper end of the outer sleeve, the lumbar support can be selectively allowed to move forward or backward relative to the backrest body, and the inner sleeve and outer sleeve can be selectively locked together. This not only allows for the adjustment of the lumbar support's position, improving user comfort, but also results in a simple and reliable structure that is convenient and stable to operate.

[0008] In some examples of this utility model, one of the first locking part and the second locking part is a locking groove and the other is a locking claw. There are multiple locking grooves, which are spaced apart on the inner sleeve. When the lumbar support moves relative to the backrest body to a preset position, the locking claw selectively locks into at least one of the multiple locking grooves.

[0009] In some examples of this utility model, the locking claw is provided with at least two locking protrusions, which are spaced apart in the vertical direction, and the at least two locking protrusions selectively engage with at least two of the plurality of locking grooves.

[0010] In some examples of this utility model, the locking claw is provided with a guide protrusion, the inner sleeve is provided with a guide groove extending in the vertical direction, the guide protrusion and the guide groove are slidably guided and engaged, and a plurality of locking grooves are respectively located on the left and right sides of the guide groove.

[0011] In some examples of this utility model, the locking claws are spaced apart behind the outer sleeve, the locking groove is located on the rear side of the inner sleeve, and the opening of the locking groove extends obliquely downwards and backwards.

[0012] In some examples of this utility model, a pivot is provided between the locking pawl and the outer tube, the locking pawl is rotatable relative to the outer tube via the pivot, and the left and right sides of the outer tube are provided with sliding grooves, the left and right ends of the pivot are respectively disposed in the sliding grooves and are slidable relative to the sliding grooves.

[0013] In some examples of this utility model, a first elastic element is provided between the rear side of the locking claw and the rear side of the outer sleeve.

[0014] In some examples of this utility model, the sleeve assembly further includes a second elastic element connected between the outer sleeve and the inner sleeve.

[0015] In some examples of this utility model, the backrest of the seat further includes a connecting assembly. The connecting assembly is spaced above the sleeve assembly and includes a first connecting plate, a second connecting plate, and a third elastic member. The first connecting plate is disposed on the backrest body, the second connecting plate is disposed on the lumbar support, the first connecting plate and the second connecting plate are rotatable relative to each other, and the third elastic member is connected between the first connecting plate and the second connecting plate.

[0016] The seat according to an embodiment of the present utility model includes: the backrest of the seat described above.

[0017] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0019] Figure 1 This is a schematic diagram of the backrest of a seat according to an embodiment of the present utility model;

[0020] Figure 2 This is a cross-sectional view of the backrest of a seat according to an embodiment of the present utility model;

[0021] Figure 3 This is a partial sectional view of the backrest of a seat according to an embodiment of the present utility model;

[0022] Figure 4 This is a cross-sectional view of the sleeve assembly according to an embodiment of the present utility model;

[0023] Figure 5 This is a cross-sectional view of the sleeve assembly according to an embodiment of the present utility model;

[0024] Figure 6 This is an exploded view of the sleeve assembly according to an embodiment of the present utility model;

[0025] Figure 7 This is a schematic diagram of the outer sleeve fitting according to an embodiment of the present utility model;

[0026] Figure 8 This is a schematic diagram of the inner sleeve fitting according to an embodiment of the present utility model.

[0027] Figure label:

[0028] 100. The backrest of the seat;

[0029] 10. Backrest main body;

[0030] 20. Lumbar support;

[0031] 30. Sleeve assembly; 301. Outer sleeve fitting; 302. Inner sleeve fitting;

[0032] 3011, Second locking part; 3012, Guide protrusion; 3013, Slide groove; 3014, Locking protrusion;

[0033] 3021, First locking part; 3022, Guide groove;

[0034] 40. Shaft;

[0035] 501. First elastic element; 502. Second elastic element;

[0036] 60. Connecting component; 601. First connecting plate; 602. Second connecting plate; 603. Third elastic element. Detailed Implementation

[0037] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0038] The following is for reference. Figures 1-8 The present invention describes a seat back 100 according to an embodiment of the present invention, which can be applied to a seat.

[0039] Combination Figures 1-8 As shown, the backrest 100 of the seat according to this utility model mainly includes: a backrest body 10, a lumbar support 20, and a sleeve assembly 30. The backrest body 10 is provided with a clearance groove to allow space for the lumbar support 20, thus providing a certain installation space and position for the lumbar support 20.

[0040] Furthermore, the lumbar support 20 is set in the clearance groove, which not only facilitates the installation and removal of the lumbar support 20 and prevents interference between the lumbar support 20 and the backrest, but also improves space utilization and prevents the overall structure of the backrest body 10 and the lumbar support 20 from occupying too much space, thus helping to improve the aesthetics of the seat back.

[0041] Furthermore, the sleeve assembly 30 includes an outer sleeve 301 and an inner sleeve 302. The lower end of the outer sleeve 301 is rotatably connected to the backrest body 10, and the upper end of the inner sleeve 302 is rotatably connected to the lumbar support 20. The inner sleeve 302 is movably disposed inside the outer sleeve 301 and selectively extends from the upper end of the outer sleeve 301 to selectively allow the lumbar support 20 to move forward or backward relative to the backrest body 10. Specifically, if the lumbar support 20 is pulled forward, the lower end of the outer sleeve 301 rotates relative to the backrest body 10, and the upper end of the inner sleeve 302 rotates relative to the lumbar support 20, causing relative movement between the inner sleeve 302 and the outer sleeve 301. The inner sleeve 302 extends a certain distance from the upper end of the outer sleeve 301, thus achieving the forward movement of the lumbar support 20. Conversely, if the lumbar support 20 is pulled or pushed backward, the lower end of the outer sleeve 301 rotates relative to the backrest body 10, and the upper end of the inner sleeve 302 rotates relative to the lumbar support 20, causing relative movement between the inner sleeve 302 and the outer sleeve 301. The inner sleeve 302 retracts a certain distance from the upper end of the outer sleeve 301, thus achieving the backward movement of the lumbar support 20. This allows for manual adjustment of the lumbar support 20's position to suit different users' needs.

[0042] Furthermore, the inner sleeve 302 is provided with a first locking part 3021, and the outer sleeve 301 is provided with a second locking part 3011. The first locking part 3021 and the second locking part 3011 are selectively locked together. Specifically, when the lumbar support 20 is adjusted, the first locking part 3021 and the second locking part 3011 are in the unlocked state; when the lumbar support 20 adjustment is completed, that is, after the lumbar support 20 position is selected, the first locking part 3021 and the second locking part 3011 are in the locked state. In this way, the locking engagement of the first locking part 3021 and the second locking part 3011 can fix the position of the lumbar support 20 after adjustment, so as to ensure that the position of the lumbar support 20 remains unchanged after adjustment, and prevent the lumbar support 20 from shifting due to external force after adjustment, which would cause the fixed position of the lumbar support 20 to change. This can improve the stability and reliability of the lumbar support 20 structure and prevent adjustment failure.

[0043] With this design, the lumbar support 20 has an adjustable position, which can meet the different user needs for the position of the lumbar support 20, thereby providing extra support for the waist, reducing the pressure on the back muscles when the user sits for a long time, and improving the user's comfort.

[0044] Therefore, by rotatably connecting the lower end of the outer sleeve 301 to the backrest body 10 and rotatably connecting the upper end of the inner sleeve 302 to the lumbar support 20, and by movably setting the inner sleeve 302 inside the outer sleeve 301 and selectively extending it from the upper end of the outer sleeve 301, the lumbar support 20 is selectively allowed to move forward or backward relative to the backrest body 10. The first locking part 3021 of the inner sleeve 302 is selectively locked to the second locking part 3011 inside the outer sleeve 301. This not only enables the separate design of the backrest and the lumbar support 20 and the adjustment of the lumbar support 20's front and rear positions to improve user comfort, but also results in a simple and reliable structure and convenient and stable operation.

[0045] Combination Figure 2 and Figure 4 As shown, one of the first locking part 3021 and the second locking part 3011 is a locking groove and the other is a locking claw. There are multiple locking grooves, which are spaced apart on the inner sleeve 302. When the lumbar support 20 moves to a preset position relative to the backrest body 10, the locking claw selectively locks into at least one of the multiple locking grooves.

[0046] Specifically, the locking claw can slide and engage in the locking groove to lock, thereby preventing the movement of the locked component, i.e., the waist support 20; conversely, in the unlocked state, the locking claw will retract from the locking groove, thereby allowing the first locking part 3021 and the second locking part 3011 to move relative to each other.

[0047] Furthermore, when the lumbar support 20 moves to a preset position relative to the backrest body 10, the locking claw engages with the corresponding locking groove to fix the position of the lumbar support 20. This not only improves the stability of the lumbar support 20 structure and prevents accidental unlocking due to vibration, impact or other external factors, but also enables high-precision adjustment of the lumbar support 20 position, improving the uniformity and rationality of the lumbar support 20 position adjustment. Moreover, the structure is simple and easy to operate, and occupies little space, which can improve the convenience of using the lumbar support 20, improve the compactness of the lumbar support 20 structure, and help reduce the manufacturing cost of the lumbar support 20.

[0048] Combination Figure 2 and Figure 4 As shown, the locking claw is provided with at least two locking protrusions 3014, which are spaced apart in the vertical direction. The at least two locking protrusions 3014 selectively lock with at least two of the multiple locking grooves.

[0049] Specifically, when only a single locking protrusion 3014 is provided on the locking pawl, not only is the stability and reliability of locking lower, and there may be a risk of non-human unlocking, but there is also a problem of stress concentration, and the locking pawl is more prone to wear or fatigue damage.

[0050] Furthermore, by providing at least two locking protrusions 3014 spaced apart in the vertical direction of the locking pawl, and selectively engaging at least two of the multiple locking grooves with the at least two locking protrusions 3014, the other locking protrusions 3014 can still maintain a locked state with the locking groove even if one of the locking protrusions 3014 fails or is damaged. This avoids damage to the locking pawl caused by stress concentration and prevents the risk of the locking pawl shaking or loosening. It improves the stability and reliability of the locking engagement between the locking pawl and the locking groove, and helps to extend the service life of the lumbar support 20.

[0051] Combination Figure 3 , Figure 5 , Figure 7 and Figure 8 As shown, the locking claw is provided with a guide protrusion 3012, and the inner sleeve 302 is provided with a guide groove 3022 extending in the vertical direction. The guide protrusion 3012 and the guide groove 3022 are slidably guided and engaged, and multiple locking grooves are located on the left and right sides of the guide groove 3022 respectively.

[0052] Specifically, the guide protrusion 3012 slides within the guide groove 3022, and the guide groove 3022 restricts the sliding direction and trajectory of the guide protrusion 3012. Through the slidable guiding engagement between the guide protrusion 3012 and the guide groove 3022, it is ensured that the locking pawl can move smoothly in the vertical direction along the locking groove on the inner tube assembly without deviating from the expected path. This also facilitates the positioning and installation of the locking pawl structure. Furthermore, when the guide protrusion 3012 moves to the lowermost end of the guide groove 3022, the locking pawl moves out of the locking groove range, which helps to achieve the unlocked state of the locking pawl and the locking groove.

[0053] Furthermore, multiple locking grooves are located on the left and right sides of the guide groove 3022, which prevents the locking pawl from wobbling or shifting in the left and right directions after locking, thus improving the stability of the locking structure in the left and right directions. The cooperation between the locking structure and the guide structure can improve the accuracy and stability of the locking engagement between the locking pawl and the locking groove.

[0054] Combination Figure 2 and Figure 4 As shown, the locking claws are spaced apart behind the inner sleeve 302, and the locking groove is located on the rear side of the inner sleeve 302. The opening of the locking groove extends obliquely downwards and backwards.

[0055] Specifically, by setting the locking claws at intervals behind the inner sleeve 302 and setting the locking groove on the rear side of the inner sleeve 302, it is not only convenient to install and disassemble the entire locking structure, but also convenient to inspect and maintain the locking structure in the future. It also ensures that the locking claws and locking groove have enough room to move, preventing interference between the sleeve assembly 30 and the waist support 20 from causing the waist support 20 to be restricted in adjustment. This ensures the rationality and reliability of the waist support 20 structure.

[0056] Furthermore, the locking groove moves forward and upward relative to the locking pawl, and the locking pawl moves backward and downward relative to the locking groove. The opening of the locking groove is tilted and extended backward and downward, which can guide the locking pawl to a certain extent, increase the smoothness of the relative movement between the locking pawl and the locking groove, and at the same time ensure the locking effect between the locking pawl and the locking groove, and ensure the stability of the waist support 20 after adjustment.

[0057] Combination Figure 2 , Figure 4 and Figure 6 As shown, a rotating shaft 40 is provided between the locking pawl and the outer tube 301. The locking pawl can rotate relative to the outer tube 301 via the rotating shaft 40. Slide grooves 3013 are provided on the left and right sides of the outer tube 301. The left and right ends of the rotating shaft 40 are respectively provided in the slide grooves 3013 and can slide relative to the slide grooves 3013.

[0058] Specifically, by setting the left and right ends of the rotating shaft 40 in the slide groove 3013 and allowing them to slide relative to the slide groove 3013, the slide groove 3013 can provide the rotating shaft 40 with a movement path and range of motion. The locking pawl can rotate relative to the outer sleeve 301 through the rotating shaft 40, thereby controlling the angle range and position of the locking pawl through the cooperation between the slide groove 3013 and the rotating shaft 40.

[0059] Furthermore, when the rotating shaft 40 is at the uppermost end of the slide groove 3013, the locking pawl and the locking groove are in an unlocked state, allowing adjustment of the lumbar support 20's position. When the rotating shaft 40 is at the lowermost end of the slide groove 3013, and the locking pawl rotates relative to the outer sleeve 301, with the upper rotating shaft 40 at the frontmost point of the lower side of the slide groove 3013, the locking pawl and the locking groove are in a locked state, securing the lumbar support 20. When the rotating shaft 40 is at the lowermost end of the slide groove 3013, and the locking pawl does not rotate relative to the outer sleeve 301, with the upper rotating shaft 40 at the rearmost point of the lower side of the slide groove 3013, the locking pawl and the locking groove remain unlocked. This configuration not only allows for adjustment of the lumbar support 20's position according to its adjustment requirements but also ensures its stability once the adjusted position is determined.

[0060] In addition, when the guide protrusion 3012 moves to the lowest end of the guide groove 3022, the locking pawl moves out of the locking groove range. At this time, with the cooperation of the guide groove 3022, the upper rotating shaft 40 can slide to the rear end of the lower side of the slide groove 3013, which can realize the unlocked state of the locking pawl and the locking groove.

[0061] It should be noted that the rotating shaft 40 is slidably connected to the outer sleeve 301, and the rotating shaft 40 is fixedly connected to the locking pawl.

[0062] Combination Figure 2 , Figure 3 , Figure 4 and Figure 6As shown, a first elastic element 501 is provided between the rear side of the locking pawl and the rear side of the outer sleeve 301. Specifically, by providing the first elastic element 501 between the rear side of the locking pawl and the rear side of the outer sleeve 301, the first elastic element 501 can provide an initial preload to the locking pawl, or increase the pressure of the locking pawl on the locking groove. The elasticity of the first elastic element 501 not only ensures a tight contact between the locking pawl and the locking groove, making the locking fit between the locking pawl and the locking groove more stable and reliable, preventing accidental unlocking due to vibration or external force, but also helps the locking pawl quickly return to its original position, preparing for the next locking action, which can simplify the operation process and improve adjustment efficiency. In addition, the first elastic element 501 can also play a certain role in buffering and vibration reduction, absorbing impact energy and providing a certain degree of protection for the locking pawl and other related components.

[0063] Combination Figure 2 and Figure 3 As shown, the sleeve assembly 30 also includes a second elastic element 502, which is connected between the outer sleeve 301 and the inner sleeve 302. Specifically, by connecting the second elastic element 502 between the outer sleeve 301 and the inner sleeve 302, when the inner sleeve 302 extends from the upper end of the outer sleeve 301, the second elastic element 502 stretches, and the inner sleeve 302 is subjected to a contraction force. This not only effectively reduces the swaying of the lumbar support 20 in its fixed position, but also increases the stability of the lumbar support 20 during adjustment, preventing the lumbar support 20 from moving excessively forward or backward. This helps to improve the adjustment accuracy of the lumbar support 20, reduce the difficulty of adjusting the lumbar support 20, enhance the manual adjustment experience of the lumbar support 20, and improve user comfort.

[0064] Combination Figure 1 and Figure 2 As shown, the seat back 100 also includes a connecting assembly 60. The connecting assembly 60 is spaced above the sleeve assembly 30 and includes a first connecting plate 601, a second connecting plate 602 and a third elastic member 603. The first connecting plate 601 is disposed on the backrest body 10, and the second connecting plate 602 is disposed on the lumbar support 20. The first connecting plate 601 and the second connecting plate 602 can rotate relative to each other. The third elastic member 603 is connected between the first connecting plate 601 and the second connecting plate 602.

[0065] Specifically, by setting the first connecting plate 601 on the backrest body 10 and the second connecting plate 602 on the lumbar support 20, and by connecting the first connecting plate 601 and the second connecting plate 602 in a way that allows relative rotation, the connection between the upper end of the lumbar support 20 and the backrest body 10 can be achieved. This helps to realize the separate design of the lumbar support 20 and the backrest body 10. At the same time, it also allows the upper end of the lumbar support 20 to move in coordination with the lower end of the lumbar support 20, thereby realizing the overall front-back position adjustment of the lumbar support 20.

[0066] Furthermore, a third elastic element 603 is connected between the first connecting plate 601 and the second connecting plate 602. This allows the third elastic element 603 to balance the effect of the second elastic element 502, enabling the upper end of the lumbar support 20 to better coordinate with the movement of the lower end. This effectively reduces the swaying of the lumbar support 20 in its fixed position, improves the stability of the lumbar support 20 after it is fixed, enhances the manual adjustment experience of the lumbar support 20, and improves user comfort.

[0067] In addition, the combined action of the first elastic element 501, the second elastic element 502 and the third elastic element 603 helps to reduce the vibration amplitude of the lumbar support 20 caused by external factors, increase the comfort of the lumbar support 20 structure, improve the toughness and stability of the sleeve assembly 30 and the connecting assembly 60, and prevent the sleeve assembly 30 from breaking.

[0068] The specific operation of adjusting the front and rear positions of the lumbar support 20 according to this utility model is as follows: If it is necessary to move the lumbar support 20 forward, simply pull the lumbar support 20, that is, apply a forward force to the lumbar support 20, causing the locking pawl to move backward and downward along the locking groove. The inner sleeve 302 extends a certain distance from the upper end of the outer sleeve 301, and the second elastic element 502 is in a stretched state. Then, under the action of the first elastic element 501 and the second elastic element 502, the locking pawl will lock with the locking groove again, thereby realizing the forward movement of the lumbar support 20. If the lumbar support 20 has already been adjusted forward, and it is necessary to move the lumbar support 20 backward, a forward force must first be applied to the lumbar support 20 to pull it to the adjustable position. At the foremost position of the range, the locking pawl is located at the lowermost end of the guide groove 3022. At this time, the locking pawl disengages from the locking groove, and under the combined action of the guide groove 3022 and the second elastic element 502, the rotating shaft 40 is located at the uppermost end of the slide groove 3013. There is no locking engagement between the locking pawl and the locking groove, and the locking pawl is in an unlocked state. Then, the first locking part 3021 will quickly return to the initial position under the action of the second elastic element 502 and the thrust, thereby causing the inner sleeve 302 to retract relative to the protruding part of the outer sleeve 301, so that the lumbar support 20 moves to the rearmost position of the adjustable range, and then the forward movement operation of the lumbar support 20 is performed again, thus realizing the relative backward movement of the lumbar support 20.

[0069] The seat according to this utility model mainly includes: the seat back 100 mentioned above. Specifically, because the seat back 100 has a more stable and reliable structure, is simple and easy to operate, and has good working performance, applying the seat back 100 to the seat allows for adjustment of the fore-and-aft position of the lumbar support 20 to meet the usage needs of different users in different scenarios, thereby enhancing the product competitiveness of the seat and improving the user experience.

[0070] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0072] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and purpose of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A seat back, characterized in that, include: Backrest body (10), the backrest body (10) is provided with a clearance groove; Lumbar support (20), the lumbar support (20) is disposed in the clearance groove; The sleeve assembly (30) includes an outer sleeve (301) and an inner sleeve (302). The lower end of the outer sleeve (301) is rotatably connected to the backrest body (10), and the upper end of the inner sleeve (302) is rotatably connected to the lumbar support (20). The inner sleeve (302) is movably disposed inside the outer sleeve (301) and selectively extends from the upper end of the outer sleeve (301) to selectively allow the lumbar support (20) to move forward or backward relative to the backrest body (10). The inner sleeve (302) is provided with a first locking part (3021), and the outer sleeve (301) is provided with a second locking part (3011). The first locking part (3021) and the second locking part (3011) are selectively locked together.

2. The backrest of the seat according to claim 1, characterized in that, One of the first locking part (3021) and the second locking part (3011) is a locking groove and the other is a locking claw. There are multiple locking grooves, which are spaced apart on the inner sleeve (302). When the lumbar support (20) moves relative to the backrest body (10) to a preset position, the locking claw selectively locks into at least one of the multiple locking grooves.

3. The backrest of the seat according to claim 2, characterized in that, The locking claw is provided with at least two locking protrusions (3014), which are spaced apart in the vertical direction. The at least two locking protrusions (3014) selectively engage with at least two of the plurality of locking grooves.

4. The backrest of the seat according to claim 3, characterized in that, The locking claw is provided with a guide protrusion (3012), and the inner sleeve (302) is provided with a guide groove (3022) extending in the vertical direction. The guide protrusion (3012) and the guide groove (3022) are slidably guided and engaged. The multiple locking grooves are respectively located on the left and right sides of the guide groove (3022).

5. The backrest of the seat according to claim 2, characterized in that, The locking claws are spaced apart behind the outer sleeve (301), and the locking groove is located on the rear side of the inner sleeve (302). The opening of the locking groove extends obliquely downwards and backwards.

6. The backrest of the seat according to claim 2, characterized in that, A pivot (40) is provided between the locking pawl and the outer tube (301). The locking pawl can rotate relative to the outer tube (301) via the pivot (40). Slide grooves (3013) are provided on the left and right sides of the outer tube (301). The left and right ends of the pivot (40) are respectively located in the slide grooves (3013) and can slide relative to the slide grooves (3013).

7. The backrest of the seat according to claim 2, characterized in that, A first elastic element (501) is provided between the rear side of the locking claw and the rear side of the outer sleeve (301).

8. The backrest of the seat according to claim 1, characterized in that, The sleeve assembly (30) further includes a second elastic element (502) connected between the outer sleeve (301) and the inner sleeve (302).

9. The backrest of the seat according to claim 1, characterized in that, It also includes a connecting component (60), which is spaced above the sleeve assembly (30) and includes a first connecting plate (601), a second connecting plate (602) and a third elastic element (603). The first connecting plate (601) is disposed on the backrest body (10), and the second connecting plate (602) is disposed on the lumbar support (20). The first connecting plate (601) and the second connecting plate (602) are rotatable relative to each other, and the third elastic element (603) is connected between the first connecting plate (601) and the second connecting plate (602).

10. A type of seat, characterized in that, include: The backrest of the seat according to any one of claims 1-9.

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