A lumbar support angle adjustment mechanism

Abstract

This utility model relates to a lumbar support angle adjustment mechanism, including a back support, a back frame, and a lumbar frame; a connecting seat is formed downwards at the lower part of the back frame, and the upper part of the lumbar frame is hinged to the connecting seat by bolts; an assembly groove facing the lumbar frame is formed on the connecting seat, and an assembly block corresponding to the groove opening is formed downwards at the upper part of the lumbar frame, with a spring abutting between the back of the assembly block and the bottom surface of the opposite assembly groove; a through hole is opened on one side wall of the assembly groove, and a handle is inserted through the through hole, the handle including a gripping part extending out of the assembly groove and a connecting part extending into the assembly groove and hinged to the connecting seat; a boss is provided on the back of the assembly block corresponding to the connecting part, and at least two steps are formed on the side of the boss facing the connecting part; when the handle is rotated around the hinge end under force, the upper outer end of the connecting part can correspond to and be locked with different steps respectively, so that the lower part of the lumbar frame can make different steps abut against the connecting part under the push of external force, realizing multi-level adjustment of the lumbar support angle.

Description

Technical Field

[0001] This utility model relates to the field of seat technology, and in particular to a lumbar support angle adjustment mechanism. Background Technology

[0002] For chairs, especially office chairs and other chairs that require sitting for long periods of time, the design of the lumbar support is crucial for the user's comfort and spinal health. An ergonomic, adjustable lumbar support can effectively support the user's lumbar spine, relieve lower back fatigue, and prevent lumbar muscle strain.

[0003] Most existing lumbar supports are designed with a fixed structure. For example, a Chinese utility model patent with publication number CN223529161U discloses a chair back assembly that is easy to install, including a back support assembly and a back support component. The back support assembly includes a main support member and a connector. The main support member includes two upwardly extending and spaced-apart arms, forming an upwardly open receiving space between the two arms. The back support component has a connecting part with two spaced-apart mounting holes. The two arms are respectively inserted into the two mounting holes and protrude upward from the connecting part. The receiving part is formed between the two mounting holes and is located in the receiving space. The connector is located above the connecting part, and its two ends are connected to the two arms respectively, closing the receiving space. In this design, the lumbar support is fixed and cannot be adjusted for people of different heights and body types, which may cause discomfort for some users.

[0004] In addition, some chairs offer adjustable lumbar support angles. A Chinese utility model patent (CN223585545U) discloses an office chair lumbar support that automatically conforms to the backrest. It includes a connecting seat, a pressure relief rod located below the connecting seat, and an angle adjustment rod also located below the connecting seat. The outer side of the pressure relief rod is connected to a gas spring, the bottom end of which is threaded to the center of the top of a base roller. Two sets of adjustable back pads are provided below the surface of the reinforcing frame, with the back of the adjustable back pads connected to the reinforcing frame via an elastic inner lining. A headrest is provided at the top of the fixed seat. This automatically conforming office chair lumbar support features an elastic latch, one end of which is hinged to one side of the reinforcing frame, and the other end fixed to the back of the adjustable back pad. This alleviates lumbar fatigue for office chair users. The angle adjustment rod allows adjustment of the reinforcing frame angle, accommodating different user angles. In this design, adjusting the lumbar support requires moving an angle adjustment lever under the seat cushion, which is inconvenient. Furthermore, the adjustment structure is complex and prone to failure due to its elastic adjustment mechanism. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a lumbar support angle adjustment mechanism. The lumbar frame is hinged to the back frame, and a handle is mounted on the back frame, allowing the user to easily reach and adjust the lumbar support angle while leaning against the seat. The handle, located within the back frame, abuts against different steps on the raised platform on the back of the lumbar frame, thereby controlling the rotation of the lumbar frame angle and achieving multi-level adjustment of the lumbar support angle. Users can flexibly adjust the lumbar support angle as needed, improving the comfort and adaptability of the seat. This solution is easy to operate, simple in structure, and provides a stable and reliable adjustment method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A lumbar support angle adjustment mechanism includes a back support, a back frame, and a waist frame; characterized in that: the back frame is fixedly installed at the front end of the back support, a connecting seat is formed downward at the lower part of the back frame, the waist frame is located below the back frame and the upper part of the waist frame is hinged to the connecting seat by bolts; an assembly groove facing the waist frame is formed on the connecting seat, and an assembly block corresponding to the opening of the assembly groove is formed downward at the upper part of the waist frame, and a spring is provided between the back of the assembly block and the bottom surface of the opposite assembly groove;

[0008] A through hole is provided on one side wall of the assembly slot, and a handle is inserted through the through hole. The handle includes a gripping part that extends out of the assembly slot and a connecting part that extends into the assembly slot and is hinged to the connecting seat. A boss is provided on the back of the assembly block corresponding to the connecting part, and at least two steps are formed on the side of the boss facing the connecting part. When the handle is rotated around the hinge end under force, the upper outer end of the connecting part can correspond to different steps and be locked. In this way, the lower part of the waist frame can make different steps abut against the connecting part under the push of external force, so as to realize multi-level adjustment of the waist support angle.

[0009] In the above technical solution, a connecting seat is set downwards at the lower part of the back frame, and the upper part of the connecting seat is hinged to the upper part of the waist frame by bolts, so that the waist frame can rotate relative to the back frame. An assembly block is set on the waist frame, which is opposite to the assembly groove of the connecting seat. A spring is set between the assembly block and the assembly groove to provide elastic support and reset. A handle is set on the side wall of the connecting seat, which extends into the assembly groove. A boss is set on the back of the assembly block, forming multiple steps. During rotation, the handle is locked at multiple positions corresponding to the steps. At these positions, the upper part of the handle corresponds to different steps. When the user leans against the lumbar support, he pushes the lower part of the waist frame so that different steps can abut against the handle, thereby controlling the size of the waist frame angle rotation and realizing multi-level adjustment of the lumbar support angle. The user can flexibly adjust the lumbar support angle as needed to improve the comfort and adaptability of the seat. This solution is easy to operate, simple in structure, and stable and reliable in adjustment method.

[0010] In addition, the handle is located on the connecting seat at the back of the waist frame, which is very convenient for users to reach out and touch when leaning against it.

[0011] Preferably, the back of the connecting part is provided with multiple positioning grooves, the bottom surface of the assembly groove is provided with a mounting post, the side of the mounting post facing the positioning groove is provided with a mounting groove, the bottom surface of the mounting groove is provided with an elastic protrusion, the positioning post is inserted into the mounting groove, the positioning groove is semi-circular, the front end of the positioning post is provided with a hemispherical protrusion protruding from the mounting post, and the multiple positioning grooves are respectively engaged with the hemispherical protrusion and locked during the rotation of the handle.

[0012] Preferably, a screw seat is provided on the bottom surface of the assembly groove, and a first countersunk hole is provided at the outer end of the connecting part corresponding to the screw seat. A first screw is screwed into the first countersunk hole and the screw seat to hinge the connecting part to the screw seat.

[0013] Preferably, the end of the connecting part facing the screw seat is formed with an abutting ring that abuts against the edge of the screw seat, and a gap is formed between the inner and outer ends of the connecting part and the through hole.

[0014] Preferably, a limiting plate that mates with the upper end of the connecting part is provided on the bottom surface of the assembly groove above the screw seat.

[0015] Preferably, the boss has three steps, and a clearance slope perpendicular to the outer end face of the connecting part is formed between adjacent steps.

[0016] Preferably, the bottom surface of the assembly groove is provided with a limiting ring opposite to the back surface of the assembly block, the inner side of the limiting ring is provided with a cross rib, and the two ends of the spring are respectively sleeved on the outer side of the cross rib.

[0017] Preferably, the assembly block has a hinge seat protruding from the back of the waist frame, and the upper two sides of the assembly groove have mating seats protruding into the assembly groove. The hinge seat extends between the two mating seats, and the outer end of the mating seat has a second countersunk hole. The bolt passes through the mating seat and the hinge seat, and the threaded end of the bolt is screwed with a nut located in the second countersunk hole.

[0018] Preferably, the connecting part is provided with a weight-reducing groove on the side facing the boss.

[0019] Preferably, the connecting seat is formed on the lower part of the back frame, the upper part of the connecting seat is on the back frame, and a plurality of bolt seats are provided in the mounting groove of the connecting seat. A plurality of third countersunk holes are provided on the back side of the back bracket, and second screws are screwed into the bolt seats and the third countersunk holes to fix the back bracket and the back frame.

[0020] The present invention adopts the above technical solution and has the following technical effects:

[0021] A connecting seat is installed at the lower part of the back frame. The upper part of the connecting seat is hinged to the upper part of the waist frame via bolts and nuts, allowing the waist frame to rotate relative to the back frame. An assembly block is installed on the waist frame, corresponding to the assembly groove of the connecting seat. A spring is installed between the assembly block and the assembly groove for elastic support and reset. A handle extending into the assembly groove is installed on the side wall of the connecting seat. A boss is installed on the back of the assembly block, forming multiple steps. During rotation, the handle locks itself at several positions corresponding to the steps through positioning grooves on the handle engaging with hemispherical protrusions in the assembly groove. At these positions, the upper part of the handle corresponds to different steps. When the user leans against the lumbar support, pushing the lower part of the waist frame causes different steps to engage with the handle, thereby controlling the rotation angle of the waist frame and achieving multi-level adjustment of the lumbar support angle. Users can flexibly adjust the lumbar support angle as needed, improving the comfort and adaptability of the seat. This solution is easy to operate, simple in structure, and the adjustment method is stable and reliable.

[0022] In addition, the handle is located on the connecting seat at the back of the waist frame, which is very convenient for users to reach out and touch when leaning against it. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of a lumbar support angle adjustment mechanism.

[0024] Figure 2 This is a front structural diagram of a lumbar support angle adjustment mechanism.

[0025] Figure 3 This is a side view of a lumbar support angle adjustment mechanism.

[0026] Figure 4 This is a schematic diagram of the three-dimensional structure of the waist frame.

[0027] Figure 5 This is a schematic diagram showing the arrangement of multiple steps on the back boss of the waist frame assembly block.

[0028] Figure 6 This is a schematic diagram showing the arrangement of the mounting slots on the lower connecting seat of the back frame.

[0029] Figure 7 This is a schematic diagram showing the relationship between the handle and the first step at the innermost end.

[0030] Figure 8 This is a schematic diagram showing the relationship between the handle and the second step.

[0031] Figure 9 This is a schematic diagram showing the relationship between the handle and the third step.

[0032] Figure 10 This is a schematic diagram showing the arrangement of the limiting plate and spring in the assembly slot.

[0033] Figure 11This is a schematic diagram showing the arrangement of the first countersunk hole and the weight reduction groove on the outer end face of the handle connection part.

[0034] Figure 12 This is a schematic diagram showing the arrangement of the positioning groove and the abutment ring on the inner end face of the handle connection part.

[0035] Figure 13 This is a schematic diagram showing the arrangement of the limit rings and positioning posts within the assembly slot.

[0036] Figure 14 This is a three-dimensional structural diagram of the positioning column.

[0037] Figure 15 This is a schematic diagram showing the arrangement of the screw seats in the assembly slot and the elastic protrusions inside the mounting column.

[0038] Figure 16 This is a schematic diagram showing the connection between the back support and the back frame. Detailed Implementation

[0039] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0040] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying 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 this utility model, unless otherwise stated, "a plurality of" means two or more, unless otherwise expressly defined.

[0042] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0043] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0044] like Figures 1-16 The lumbar support angle adjustment mechanism shown includes a back support 1, a back frame 2, and a waist frame 3. The back frame 2 is fixedly installed at the front end of the back support 1. A connecting seat 4 is formed downward on the lower part of the back frame 2. The waist frame 3 is located below the back frame 2, and the upper part of the waist frame 3 is hinged to the connecting seat 4 by bolts 31. An assembly groove 5 facing the waist frame 3 is formed on the connecting seat 4. An assembly block 6 corresponding to the groove opening of the assembly groove 5 is formed downward on the upper part of the waist frame 3. A spring 7 is provided between the back of the assembly block 6 and the bottom surface of the opposite assembly groove 5.

[0045] A through hole 8 is provided on one side wall of the assembly groove 5, and a handle 9 is provided through the through hole 8. The handle 9 includes a gripping part 10 extending out of the assembly groove 5 and a connecting part 11 extending into the assembly groove 5 and hinged to the connecting seat 4. A boss 12 is provided on the back of the assembly block 6 corresponding to the connecting part 11. At least two steps 13 are formed on the side of the boss 12 facing the connecting part 11. When the handle 9 is rotated around the hinge end under force, the upper outer end of the connecting part 11 can correspond to and be locked with different steps 13 respectively. In this way, the lower part of the waist frame 3 can make different steps 13 abut against the connecting part 11 under the push of external force, so as to realize the multi-level adjustment of the waist support angle.

[0046] In the above technical solution, a connecting seat is set downwards at the lower part of the back frame, and the upper part of the connecting seat is hinged to the upper part of the waist frame by bolts, so that the waist frame can rotate relative to the back frame. An assembly block is set on the waist frame, which is opposite to the assembly groove of the connecting seat. A spring is set between the assembly block and the assembly groove to provide elastic support and reset. A handle is set on the side wall of the connecting seat, which extends into the assembly groove. A boss is set on the back of the assembly block, forming multiple steps. During rotation, the handle is locked at multiple positions corresponding to the steps. At these positions, the upper part of the handle corresponds to different steps. When the user leans against the lumbar support, he pushes the lower part of the waist frame so that different steps can abut against the handle, thereby controlling the size of the waist frame angle rotation and realizing multi-level adjustment of the lumbar support angle. The user can flexibly adjust the lumbar support angle as needed to improve the comfort and adaptability of the seat. This solution is easy to operate, simple in structure, and stable and reliable in adjustment method.

[0047] In addition, the handle is located on the connecting seat at the back of the waist frame, which is very convenient for users to reach out and touch when leaning against it.

[0048] It should be noted that in this case, there are two bosses symmetrically arranged on the back of the assembly block, that is, the handle can be installed on the left or right side to accommodate whether the user is left-handed or right-handed.

[0049] Furthermore, the back of the connecting part 11 is provided with multiple positioning grooves 14, the bottom surface of the assembly groove 5 is provided with a mounting post 15, the side of the mounting post 15 facing the positioning groove 14 is provided with a mounting groove 16, the bottom surface of the mounting groove 16 is provided with an elastic protrusion 17, and a positioning post 18 is inserted into the mounting groove 16. The positioning groove 14 is semi-circular, and the front end of the positioning post 18 is provided with a hemispherical protrusion 19 protruding from the mounting post 15. The multiple positioning grooves 14 respectively cooperate with the hemispherical protrusion 19 to lock during the rotation of the handle 9. In this technical solution, the cooperation between the positioning groove and the hemispherical protrusion enhances the reliability and feel of the handle angle locking, prevents the handle from accidentally sliding, and achieves the purpose of positioning and limiting the handle's position. When moving from one positioning groove to another, the positioning post is squeezed and compressed by the elastic protrusion. When the handle rotates to the point where the positioning groove and the hemispherical protrusion of the positioning post correspond, the elastic protrusion acts on the positioning post to make the hemispherical protrusion engage in the positioning groove. The design of the elastic protrusion and the positioning post makes the locking mechanism adaptive, reduces wear, and improves service life.

[0050] Furthermore, a screw seat 20 is provided on the bottom surface of the assembly groove 5, and a first countersunk hole 21 is provided at the outer end of the connecting part 11 corresponding to the screw seat 20. A first screw 22 is screwed into the first countersunk hole 21 and the screw seat 20 to hinge the connecting part 11 to the screw seat 20. In this technical solution, the handle is stably hinged by screw connection, which simplifies the assembly process, reduces production costs, improves the rigidity and durability of the structure, and ensures that the handle remains stable after multiple operations. In addition, the head of the screw is located in the first countersunk hole to prevent the screw from protruding from the surface of the handle and interfering with the rotation of the handle.

[0051] Furthermore, the end of the connecting part 11 facing the screw seat 20 is formed with an abutment ring 23 that abuts against the edge of the screw seat 20, and a gap is formed between the inner and outer ends of the connecting part 11 and the through hole 8. In this technical solution, the abutment ring abuts against the edge of the screw seat to prevent the handle from moving back and forth, avoids direct contact between the connecting part and the through hole, makes the handle rotate more smoothly, and at the same time reduces friction with the screw seat, prevents handle wear, and reduces handle rotation jamming.

[0052] Furthermore, a limiting plate 24, which mates with the upper end of the connecting part 11, is provided on the bottom surface of the assembly groove 5 above the screw seat 20. This technical solution limits the rotation range of the handle, preventing excessive rotation from causing damage to the mechanism or loss of angle adjustment control, improving operational safety, and ensuring that angle adjustment is performed within a reasonable range. It should be noted that two limiting plates are symmetrically arranged on the left and right sides, meaning the handle can be installed on either the left or right side to accommodate whether the user is left-handed or right-handed.

[0053] Furthermore, the boss 12 has three steps 13, with a clearance slope 25 perpendicular to the outer end face of the connecting part 11 formed between adjacent steps 13. In this technical solution, the three steps provide three distinct adjustment levels to meet the user's needs for different angles. Figure 7 As shown, the first step 13.1 corresponds to the upper part of the outer end face of the handle connector; as Figure 8 As shown, the second step 13.2 corresponds to the upper part of the outer end face of the handle connection, and the upper clearance slope is roughly parallel to the upper end of the handle. This results in a large mating area and good limiting effect when the second step 13.2 contacts the handle; similarly, as... Figure 9 As shown, the third step 13.3 corresponds to the upper part of the outer end face of the handle connection part, and the lower avoidance slope is also roughly parallel to the upper end of the handle. In this way, when the second step 13.3 abuts against the handle, the mating area is large and the limiting effect is good.

[0054] Furthermore, the avoidance of the slope ensures a smooth transition between steps, preventing the handle from bumping and wearing down against the edges of the steps, thus improving the user experience.

[0055] Furthermore, a limiting ring 26 is provided on the bottom surface of the assembly groove 5, and a limiting groove 36 is provided on the opposite back side of the assembly block 6. A cross-shaped rib 27 is provided on the inner side of the limiting ring 26 and the limiting groove 36, and both ends of the spring 7 are respectively fitted onto the outer side of the cross-shaped rib 27. In this technical solution, the limiting ring and the cross-shaped rib ensure the correct positioning of the spring, prevent the spring from shifting or twisting during compression, improve the working stability of the spring, extend the spring life, and ensure the consistency of the waist frame's reset.

[0056] Furthermore, a hinge seat 28 protrudes from the back of the waist frame 3 above the assembly block 6, and mating seats 29 protrude from both sides of the upper part of the assembly groove 5. The hinge seat 28 extends between the two mating seats 29, and a second countersunk hole 30 is formed at the outer end of the mating seat 29. The bolt 31 passes through the mating seat 29 and the hinge seat 28, and a nut 32 located in the second countersunk hole 30 is screwed onto the threaded end of the bolt 31. In this technical solution, the waist frame is hinged to the connecting seat of the back frame by bolts and nuts. The nut of the bolt is located in the second countersunk hole on one side, and the nut on the other side is screwed onto the threaded end of the bolt and recessed into the second countersunk hole on the other side, which serves as a limit and prevents the bolt from coming off. The hinge seat extends between the two mating seats and abuts against the mating seats at both ends, which greatly improves the torsional resistance of the hinge point and makes the waist frame more stable during adjustment.

[0057] Furthermore, the connecting part 11 is provided with a weight-reducing groove 33 on the side facing the boss 12. This technical solution reduces the weight of the handle connecting part, making its rotation easier and less strenuous, thus improving user comfort. It also facilitates the positioning pin locking the connecting part through the positioning groove; saving materials and reducing manufacturing costs without affecting structural strength.

[0058] Furthermore, the connecting seat 4 is partially formed on the lower part of the back frame 2, and the upper part of the connecting seat 4 is on the back frame 2. Multiple bolt seats 34 are provided in the assembly groove 5 of the connecting seat 4. Multiple third countersunk holes 35 are correspondingly provided on the back side of the back support 1. Second screws 37 are screwed into the bolt seats 34 and the third countersunk holes 35 to fix the back support 1 and the back frame 2. In this technical solution, the connection strength between the back support and the back frame is improved by using multiple bolt seats and third countersunk holes in conjunction with second screws for fixation. Specifically, six bolt seats are assembled with the back frame, and four bolt seats are on the connecting seat. This greatly improves the structural strength of the connecting seat and enhances the assembly stability of the waist frame and the connecting seat, preventing loosening.

[0059] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is 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. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A lumbar support angle adjustment mechanism, comprising a back support (1), a back frame (2), and a lumbar frame (3); characterized in that: The back frame (2) is fixedly installed at the front end of the back bracket (1). A connecting seat (4) is constructed downward on the lower part of the back frame (2). The waist frame (3) is located below the back frame (2) and the upper part of the waist frame (3) is hinged to the connecting seat (4) by bolts (31). An assembly groove (5) facing the waist frame (3) is formed on the connecting seat (4). An assembly block (6) corresponding to the groove opening of the assembly groove (5) is formed downward on the upper part of the waist frame (3). A spring (7) is provided between the back of the assembly block (6) and the bottom surface of the opposite assembly groove (5). The assembly slot (5) has a through hole (8) on one side wall, and a handle (9) is provided through the through hole (8). The handle (9) includes a gripping part (10) extending out of the assembly slot (5) and a connecting part (11) extending into the assembly slot (5) and hinged to the connecting seat (4). The back of the assembly block (6) is provided with a boss (12) corresponding to the connecting part (11). The boss (12) has at least two steps (13) on the side facing the connecting part (11). When the handle (9) is subjected to force and rotates around the hinge end, the upper outer end of the connecting part (11) can correspond to and be locked with different steps (13). In this way, the lower part of the waist frame (3) can be pushed by external force so that different steps (13) abut against the connecting part (11) to realize multi-level adjustment of the waist support angle.

2. The lumbar support angle adjustment mechanism according to claim 1, characterized in that: The back of the connecting part (11) is provided with multiple positioning grooves (14), the bottom surface of the assembly groove (5) is provided with mounting posts (15), the side of the mounting posts (15) facing the positioning grooves (14) is provided with mounting grooves (16), the bottom surface of the mounting grooves (16) is provided with elastic protrusions (17), the mounting grooves (16) are inserted with positioning posts (18), the positioning grooves (14) are semi-circular, the front end of the positioning posts (18) is provided with hemispherical protrusions (19) protruding from the mounting posts (15), and the multiple positioning grooves (14) respectively cooperate with the hemispherical protrusions (19) to lock during the rotation of the handle (9).

3. The lumbar support angle adjustment mechanism according to claim 1, characterized in that: The bottom surface of the assembly groove (5) is provided with a screw seat (20), and the outer end of the connecting part (11) is provided with a first countersunk hole (21) corresponding to the screw seat (20). The first screw (22) is screwed into the first countersunk hole (21) and the screw seat (20) to hinge the connecting part (11) to the screw seat (20).

4. The lumbar support angle adjustment mechanism according to claim 3, characterized in that: The connecting part (11) has an abutment ring (23) formed at one end facing the screw seat (20) that abuts against the edge of the screw seat (20), and a gap is formed between the inner and outer ends of the connecting part (11) and the through hole (8).

5. The lumbar support angle adjustment mechanism according to claim 3, characterized in that: On the bottom surface of the assembly groove (5), above the screw seat (20), there is a limiting plate (24) that cooperates with the upper end of the connecting part (11).

6. The lumbar support angle adjustment mechanism according to claim 1, characterized in that: The boss (12) has three steps (13) formed on it, and a clearance slope (25) perpendicular to the outer end face of the connecting part (11) is formed between adjacent steps (13).

7. The lumbar support angle adjustment mechanism according to claim 1, characterized in that: The bottom surface of the assembly groove (5) is provided with a limiting ring (26), and the back side of the assembly block (6) is provided with a limiting groove (36). The inner side of the limiting ring (26) and the limiting groove (36) is provided with a cross rib (27), and the two ends of the spring (7) are respectively sleeved on the outside of the cross rib (27).

8. The lumbar support angle adjustment mechanism according to claim 1, characterized in that: A hinge seat (28) is provided above the waist frame (3) on the back side. A mating seat (29) is provided on both sides of the upper part of the assembly groove (5) protruding into the assembly groove (5). The hinge seat (28) extends between the two mating seats (29). A second countersunk hole (30) is constructed at the outer end of the mating seat (29). A bolt (31) passes through the mating seat (29) and the hinge seat (28). A nut (32) is screwed into the second countersunk hole (30) at the threaded end of the bolt (31).

9. The lumbar support angle adjustment mechanism according to claim 3, characterized in that: The connecting part (11) is provided with a weight-reducing groove (33) on the side facing the boss (12).

10. The lumbar support angle adjustment mechanism according to claim 1, characterized in that: The connecting seat (4) is partially formed on the lower part of the back frame (2), the upper part of the connecting seat (4) is on the back frame (2), and multiple bolt seats (34) are provided in the mounting groove (5) of the connecting seat (4). Multiple third countersunk holes (35) are provided on the back side of the back bracket (1). Second screws (37) are screwed into the bolt seats (34) and the third countersunk holes (35) to fix the back bracket (1) and the back frame (2).

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