A chair that can tilt forward and backward

Abstract

The present invention discloses a chair that can tilt forward and backward, comprising a base, a seat, a backrest frame, and a tilting frame. The front and rear ends of the seat are hinged to the upper end of the tilting frame and the middle section of the backrest frame, respectively. The front and rear ends of the base are hinged to the lower end of the tilting frame and the front end of the backrest frame, respectively. The rear end of the backrest frame is fixedly connected to the backrest frame. The bottom of the rear end of the base is fixedly connected to the chair leg frame. The base is tilted downward from the front to the rear end, such that the vertical gap between the seat and the base gradually increases from front to back. The backrest frame is tilted upward from the front to the rear end, such that the vertical gap between the seat and the backrest frame gradually decreases from front to back. The seat is used to fix and install a seat cushion. The present invention has the beneficial effect of improving comfort.

Description

Technical Field

[0001] The present invention relates to a chair, in particular to a chair which can be tilted forward and backward. Background Art

[0002] Currently, many office chairs used in offices or leisure chairs used for daily leisure have the function of tilting forward and backward, and also have the function of locking the tilt angle and adjusting the tilt tightness.

[0003] For example, a patent application with prior art publication number CN109393798A discloses a wire-controlled device for adjusting the tilt and tightness of a seat back frame. A wire-controlled device for adjusting the tilt and tightness of a seat back frame includes a wire-controlled device for adjusting the tilt of a seat back frame and a wire-controlled device for adjusting the tightness of a seat back frame, both of which are provided in the seat; the wire-controlled device for adjusting the tilt of the seat back frame includes a back frame connecting tail plate, a tilt adjustment mechanism, a tilt pull cord, and a tilt adjustment handle, one end of the tilt pull cord is connected to the tilt adjustment mechanism, and the other end is connected to the tilt adjustment handle; the wire-controlled device for adjusting the tightness of the seat back frame includes a tightness adjustment control rod, a first tightness pull cord, a second tightness pull cord, and a tightness adjustment mechanism. This patent application designs a wire-controlled device for adjusting the tilt of the seat back frame and a wire-controlled device for adjusting the tightness of the seat back frame, and a simple mechanical mechanism allows the user to easily adjust the back frame to a comfortable angle.

[0004] A patent application, filed with publication number CN111528639A, optimizes the tension adjustment capabilities of the aforementioned prior art. It discloses an adjustable backrest and seat connection device, belonging to the field of swivel chair technology. The device comprises a backrest tension control assembly, which includes a rotationally adjustable control handle, a universal joint, a transmission rod, a first bevel gear, a second bevel gear, a lifter, a mounting base for the lifter, and a tension adjustment rod. This patent application replaces the traditional pull cord with a universal joint for transmission, improving the responsiveness of force transmission during backrest tension adjustment and enhancing the precision and controllability of backrest tension adjustment. Furthermore, compared to pull cord adjustment, the device also effectively reduces the lever arm, the force transmission required during adjustment, and the required force transmission, thereby reducing the user's strength requirements and effectively reducing the likelihood of damage to the adjustment mechanism due to excessive input force during adjustment, thereby extending the product's service life.

[0005] First, both patent applications use knobs to adjust the reclining tightness. Although rotating the knob allows for stepless adjustment, making the adjustment more precise, this adjustment method has the following three drawbacks:

[0006] First, it is more troublesome to adjust the tightness over a large span. Users cannot directly adjust across it, but need to repeatedly turn the knob to adjust it step by step, which is more troublesome to use. Moreover, the fineness of this adjustment mode is proportional to the degree of rotation of the knob, resulting in a contradiction between performance and ease of use.

[0007] Second, the tightness of the knob is directly proportional to the tightness of the forward and backward tilt adjustment. As the user adjusts from loose to tight, the force required to rotate the knob gradually increases, which is poor for the user experience.

[0008] Third, the tensioning devices described in these two patent applications, regardless of how the tension is adjusted, gradually tighten during the reclining process, i.e., the damping gradually increases, acting like a brake to reduce the jerkiness caused by stopping at the maximum reclining angle. However, the damping is always present during the reclining process and is linear. When the user is relaxing, such as when leaning back and forth (swinging back and forth), especially when the swinging speed is fast, the ideal experience is to have less damping (looser) or even no damping in the first half of the reclining process, and more damping (tighter) in the second half of the reclining process to achieve a braking effect. The two existing tensioning devices cannot achieve this experience. If adjusted too loosely, rapid forward and backward leaning will result in poor braking effect, and the jerkiness when leaning back to the maximum angle will be stronger. If adjusted too tight, the braking effect can be guaranteed, but the damping is too high when leaning forward and backward, making it impossible to lean forward and backward quickly.

[0009] Secondly, in these two patent applications, locking of the forward and backward tilt angles is achieved by plugging and fitting an arc-shaped plate structure. The arc-shaped plate structure occupies the vertical space, resulting in almost no structural gap between the seat located above and the base located below. The base is basically directly supported on the bottom surface of the seat, making the seat a rigid structure. When the user sits on the seat cushion, the pressure on the seat gradually increases from the edge to the center, resulting in a tendency to deform downward in a pit-like shape. The seat cushion has no room for deformation, resulting in a hard texture at the center, which is less comfortable. The lack of gap makes it easy for the seat to get stuck due to local aging and deformation after long-term use. In addition, in the prior art CN111528639A, the seat (seat connector) and the base (tray) are connected directly, so the seat cannot tilt forward and backward synchronously, resulting in a poor user experience. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a chair which can be tilted forward and backward to improve comfort.

[0011] The present invention is achieved through the following technical solutions.

[0012] A chair that can be tilted forward and backward comprises a base, a seat, a backrest frame, and a tilt frame. The front and rear ends of the seat are hinged to the upper end of the tilt frame and the middle section of the backrest frame respectively. The front and rear ends of the base are hinged to the lower end of the tilt frame and the front end of the backrest frame respectively. The rear end of the backrest frame is fixedly connected to the backrest frame. The bottom of the rear end of the base is fixedly connected to the chair leg frame.

[0013] The base is tilted downward from the front end to the rear end, so that the vertical gap between the seat and the base gradually increases from the front to the rear end; the chair back frame is tilted upward from the front end to the rear end, so that the vertical gap between the seat and the chair back frame gradually decreases from the front to the rear end; the chair seat is used for fixing the seat cushion.

[0014] As a further improvement of the present invention, the base is a hollow box-shaped structure, and its left and right side walls are located at the upper part of the rear section and have a first hinge point respectively. The chair back frames are provided with two, and the upper parts of the front ends of the two chair back frames are hinged to the two first hinge points respectively; a swing rod extending left and right is connected between the lower parts of the front ends of the two chair back frames, and the left and right side walls of the base respectively have an arc groove that allows the swing rod to pass through and limits the forward and backward swing range of the swing rod.

[0015] As a further improvement of the present invention, a main push rod extending forward and backward is provided in the base, the front end of which slides through a first ring structure provided in the base, and the rear end of which is movably connected to the swing rod; the main push rod is provided with a first elastic compression structure, and its two ends are respectively supported on the first ring structure and the swing rod.

[0016] As a further improvement of the present invention, the seat back frame is expanded laterally from the front end to the rear end, so that the left and right distance between the two seat back frames gradually increases from the front to the rear, and defines the width of the seat back frame.

[0017] As a further improvement of the present invention, the chair back frame includes two chair back connecting sections fixedly connected to the rear end of the chair back frame and along the extension direction thereof, two side frames extending upward from the rear ends of the two chair back connecting sections, a top frame extending laterally from the top ends of the two side frames and closed, and a bottom frame connected between the bottom ends of the two side frames; the side frames first tilt forward from the bottom end to the middle part and tilt backward from the middle to the top part; the top frame tilts backward from the two sides to the middle; the frame structure formed by the top frame, the top frame, and the two side frames is used to fix the back of the chair.

[0018] As a further improvement of the present invention, the chair back connecting section and the outer side edges from the bottom end to the middle of the side frame are fixedly connected with an armrest fixing frame extending along the extension direction of the two, and the top end of the armrest fixing frame is fixedly connected with an armrest extending forward.

[0019] As a further improvement of the present invention, the seat is a flat plate structure, and the rear ends of the left and right sides thereof respectively have a third hinge point. The middle section of the chair back frame has a bracket extending to its side, and the ends of the two brackets are hinged to the two third hinge points.

[0020] As a further improvement of the present invention, the front ends of the left and right side walls of the base respectively have a second hinge point, and the front ends of the left and right sides of the seat respectively have a fourth hinge point; the flip frame is provided with two, and its lower end and upper end are hinged to the second hinge point and the fourth hinge point respectively.

[0021] As a further improvement of the present invention, a cushion support plate is fixed to the top surface of the seat, and the area of the cushion support plate is larger than the seat; the bottom surface of the cushion support plate has an inwardly recessed mounting surface, and the seat is embedded in the mounting surface; the top surface of the cushion support plate fixes the cushion.

[0022] As a further improvement of the present invention, the entire front end of the seat cushion support plate and the seat cushion is curved downward in an arc shape.

[0023] Beneficial effects of the present invention:

[0024] The present invention arranges the base, chair back frame, seat and flip frame into an inverted triangle-shaped overall structure, so that there is a larger gap between the seat located above and the base and chair back frame located below. This not only increases the maximum range of the chair back frame that can be reclined, but also allows the seat to have space to deform and sink downward, providing a certain amount of cushioning space when the user sits down, thereby improving comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to help understand the objects and advantages of the present invention, wherein:

[0026] Figure 1 This is a schematic diagram of the structure of the base and backrest frame of Implementation Case 1;

[0027] Figure 2 This is a structural diagram of the base of implementation case 1;

[0028] Figure 3 This is a schematic diagram of the internal structure of the base of implementation case 1;

[0029] Figure 4 This is a schematic diagram of the structure of the swing rod, main push rod and auxiliary push rod in implementation case 1;

[0030] Figure 5 This is a structural diagram of the base plate of implementation case 1;

[0031] Figure 6 This is a structural diagram of the first locking mechanism, the second locking mechanism, and the base in Example 1;

[0032] Figure 7 This is a structural diagram of Example 1 in which the first locking mechanism and the second locking mechanism are engaged with the main push rod and the locking seat respectively;

[0033] Figure 8 This is a schematic diagram of the structure of a chair that can be tilted forward and backward in implementation case 2;

[0034] Figure 9 This is a side view of the base, back frame, seat, and flip frame of Example 2;

[0035] Figure 10 This is a schematic diagram of a chair that can tilt forward and backward in the forward tilt position in implementation case 2;

[0036] Figure 11 This is a schematic diagram of a reclining chair in the reclining position in Example 2;

[0037] Figure 12 This is a structural diagram of the chair back frame in implementation case 2;

[0038] Figure 13 This is a schematic diagram of the structure of the seat support plate and seat cushion for implementation case 2. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and implementation examples.

[0040] In this specification, directional terms such as up, down, left, right, front, back, front, back, top, and bottom, which are mentioned or may be mentioned, are defined relative to the configurations shown in the accompanying drawings. The terms "inside" and "outside" refer to directions toward or away from the geometric center of a specific component, respectively. These are relative concepts and may vary depending on the location and usage of the component. Therefore, these or other directional terms should not be construed as restrictive.

[0041] Implementation Case 1:

[0042] Reference Figure 1 and Figure 2 A chair back adjustment mechanism includes a base 1 and a chair back frame 2; the base 1 is a box-shaped structure and is used to fix the seat, and two chair back frames 2 are provided, which are symmetrically arranged on the rear sections of the left and right side walls of the base 1. Specifically, the upper part of the front end of the chair back frame 2 is hinged to the base 1 through a rotating shaft passing through the side wall of the base 1, and a swing rod 2-1 extending left and right is connected between the lower parts of the front ends of the two chair back frames 2. The left and right side walls of the base 1 are provided with an arc groove 1-h allowing the swing rod 2-1 to pass through. The front end and the rear end of the arc groove 1-h limit the range of the swing rod 2-1 to swing back and forth.

[0043] It should be noted that in this application, the front, back, left and right mentioned above and below are all referenced to the chair, and the direction facing the chair is defined as the front, and the direction facing the back is defined as the back.

[0044] Reference Figure 3 、 Figure 4 The part of the swing rod 2-1 located in the base 1 is slidably sleeved with a sleeve 2-11, and the sleeve 2-11 is fixedly connected to the main push rod 61. When the chair back frame 2 leans back, the swing rod 2-1 swings forward accordingly within the range constrained by the arc groove 1-h. The sleeve 2-11 will passively rotate around the axis of the swing rod 2-1, thereby driving the main push rod 61 to move in a straight line along the front and rear directions. The reclining of the chair back frame 2 occurs by the user leaning back.

[0045] Reference Figure 3 、 Figure 4 The front section of the main push rod 61 is equipped with multiple first locking nodes 6-A spaced apart along the front-to-back direction. These first locking nodes 6-A occupy 1 / 4-1 / 3 of the total length of the main push rod 61. This section, which is the length for the main push rod 61 to move forward and backward, corresponds to the arc length of the arc-shaped slot 1-h of the base 1. A movable first locking mechanism is provided within the base 1. The first locking mechanism can engage or disengage with the first locking nodes 6-A within its range of motion. When engaged, the first locking mechanism prevents the main push rod 61 from moving forward or backward, thereby locking the reclining angle of the seat back frame 2. When disengaged, the main push rod 61 can move freely forward and backward, allowing the reclining angle of the seat back frame 2 to be adjusted. When the first locking mechanism engages with the first locking nodes 6-A located at the front and rear ends, the seat back frame 2 is in the most forward or rearward tilt state.

[0046] Reference Figure 3 、 Figure 4 Within the base 1, and located on the left and right sides of the main push rod 61, are a set of locking seats 73, a second elastic compression structure 72, and a movable second locking mechanism. The front and rear ends of the second elastic compression structure 72 are supported on the locking seat 73 and the swing rod 2-1, respectively. The second elastic compression structure 72 is made of elastic material and can be compressed and exert an elastic force when subjected to the front and rear squeezing force of the locking seat 73 and the swing rod 2-1. The second locking mechanism functions similarly to the first locking mechanism and can be engaged or disengaged with the locking seat 73. When engaged, as the swing rod 2-1 swings forward, the second elastic compression structure 72 is squeezed by the locking seat 73 and the swing structure into a compressed state, thereby exerting an elastic force on the swing rod 2-1. When disengaged, the second elastic compression structure 72 is not squeezed and therefore does not exert an elastic force on the swing rod 2-1.

[0047] From the perspective of its structural shape and movement pattern, the main push rod 61 is an elongated structure extending forward and backward, and moves linearly along its length. Due to this characteristic, the main push rod 61 requires only a limited amount of space from the base 1 in terms of its front-to-back length, with relatively low vertical height requirements, requiring only that no mechanical interference occur. Therefore, the base 1 can be configured as a flat, box-like structure with a specific width (to accommodate the left-rear span of the main push rod 61 and the second elastic compression structure 72 and locking seat 73 located on its sides), a specific length (to accommodate the length of the main push rod 61 and its range of movement), and a relatively narrow thickness (to ensure that no mechanical interference occurs between the main push rod 61, the second elastic compression structure 72, and the locking seat 73 in the vertical space). This allows for more structural space to be reserved for other components of the chair (e.g., the seat and cushion). Furthermore, the seat and cushion structures located above the base 1 are more easily concealed, resulting in a more aesthetically pleasing design.

[0048] The two sets of locking seats 73 and the second elastic compression structure 72 are used to adjust the tightness of the seat back frame 2 when it is reclined. By controlling whether the second locking mechanism is engaged with the locking seat 73, the tightness of the reclining position can be adjusted in two levels.

[0049] Reference Figure 3 、 Figure 4 A first collar structure 63 is provided within the front section of the base 1. The front end of the main push rod 61 slides through the first collar structure 63. The collar structure provides support and guidance for the front section of the main push rod 61, allowing the main push rod 61 to move in the axial direction, thereby preventing radial deflection or movement when the main push rod 61 moves forward and backward. A first elastic compression structure 62 is provided on the portion of the main push rod 61 located between the first collar structure 63 and the swing rod 2-1. The front and rear ends of the first elastic compression structure 62 are supported by the first collar structure 63 and the swing rod 2-1, respectively. When the swing rod 2-1 swings forward, the first elastic compression structure 62 is squeezed and compressed by the first collar structure 63 and the swing rod 2-1, thereby applying an elastic force to the swing rod 2-1. The backward elastic force of the first elastic compression structure 62 on the swing rod 2-1 can make the chair back frame 2 quickly tilt forward and reset without the action of external force, thereby realizing forward and backward tilting; in addition, the first elastic compression structure 62 cooperates with the two second elastic compression structures 72 to make the backward tilt of the chair back frame 2 have three levels of tightness. The first elastic compression structure 62 always plays a role in the forward and backward swinging process of the swing rod 2-1, that is, the tightness level provided by the first elastic compression structure 62 is permanent, and the two tightness levels provided by the two second elastic compression structures 72 are selectable based on the engagement or separation of the second locking mechanism and the locking seat 73.

[0050] Reference Figure 3 、 Figure 4The locking seat 73 has multiple second locking nodes 7-A arranged at intervals along the front-to-back direction. The second locking mechanism can engage or disengage with the second locking nodes 7-A within its range of motion. When the second locking mechanism engages with different second locking nodes 7-A, the compression amount of the second elastic compression structure 72 of the swinging rod 2-1 is different when the swinging rod 2-1 swings, thereby causing the elastic force applied by the second elastic compression structure 72 to the swinging rod 2-1 to also be different. Therefore, based on the above, the two locking seats 73 provide two adjustable large tension levels for reclining based on the combination or disengagement of the second locking mechanism and the locking seat 73. The large tension level is divided into multiple selectable small tension levels depending on which second locking node 7-A of the locking seat 73 the second locking mechanism engages with. This allows for more precise adjustment of the reclining tension of the seat back frame 2.

[0051] When the swing lever 2-1 is at the rearmost end of its forward-backward swing range and the second elastic compression structure 72 is in its neutral position, the second locking mechanism can engage with the second locking node 7-A at the frontmost end of the locking seat 73. Taking the swing lever 2-1's swing from the rearmost end to the frontmost end of its swing range as a reference, when the second locking mechanism engages with the frontmost second locking node 7-A, the second elastic compression structure 72 remains compressed, constantly applying an elastic force to the swing lever 2-1. The magnitude of the elastic force is proportional to the swing lever 2-1's forward swing range. When the second locking mechanism engages with the other second locking nodes 7-A, the swing lever 2-1 will not begin to compress the second elastic structure until it has swung forward a certain distance. In other words, the swing lever 2-1 will not experience the gradually increasing elastic force applied by the second elastic compression structure 72 until it has swung forward a certain distance. Therefore, by combining two locking seats 73 with second locking nodes 7-A in different positions, the tension changes during the recline process can vary, while maintaining a roughly similar tension when approaching the maximum recline angle.

[0052] For example, the second locking node 7-A at the front end is set to gear 1, and from front to back, they are gear 2, gear 3, etc., and two combination modes are adopted. In the first combination mode, the two locking seats 73 select gear 2 and gear 4 respectively, and in the second combination mode, gear 3 is selected. When the chair back frame 2 reaches the maximum reclining angle (the swing rod 2-1 swings to the front end), the damping (generated by the elastic force) of the two combination modes is roughly the same, but the change in damping during the reclining process is different: in the first combination mode, when the swing rod 2-1 swings forward, the elastic force of gear 2 intervenes first and then gear 4; in the second combination mode, the time when the elastic forces of the two gears 3 intervene is between gear 2 and gear 4; therefore, in the first combination mode, the damping intervention time is earlier and the average change in damping is smaller, and in the second combination mode, the damping intervention time is later and the average change in damping is larger.

[0053] In summary, assuming the sum of the two gears is the same, a larger span between the two gears results in earlier damping engagement and a smoother overall damping. A smaller span between the two gears results in a later damping engagement and a more intense overall damping. Therefore, users can freely choose a combination of the two gears to adjust the tension to their optimum level.

[0054] Reference Figure 3 、 Figure 4 The locking seat 73 is structurally semi-cylindrical, with a second collar structure 731 at its rear end. Two auxiliary push rods 71 corresponding to the locking seat 73 are provided in the base 1. The auxiliary push rod 71 extends in the front-to-back direction, with its rear end fixedly connected to the sleeve 2-11 and its front end slidingly passing through the second collar structure 731. The second elastic compression structure 72 is sleeved outside the locking seat 73 and supported between the second collar structure 731 and the sleeve 2-11. The auxiliary push rod 71 can act as a skeleton when the swing arm 2-1 swings forward and the second elastic compression structure 72 is compressed, thereby preventing the second elastic compression structure 72 from bending radially along the auxiliary push rod 71, making it more stable and reliable. In addition, a nut 711 is threadedly sleeved on the front end of the auxiliary push rod 71, which abuts against the second collar structure 731 and serves as a limiting structure to prevent it from slipping off the second collar structure 731. When the second locking mechanism is not engaged with the locking seat 73 and the swing arm 2-1 swings backward, the auxiliary push rod 71 can pull the locking seat 73 back to its original position.

[0055] Reference Figure 3 、 Figure 5 、 Figure 6 、 Figure 7A support 11 is provided between the main push rod 61 and the two auxiliary push rods 71. The support 11 and the base 1 are an integral structure, formed by the upward protrusion of the bottom plate of the base 1, and extending in the front-to-back direction. A fixed shaft 12 extending forward and backward is provided on the top of the support 11. The front and rear ends of the top of the support 11 respectively have support structures 111 that support the two ends of the fixed shaft 12 and allow the fixed shaft 12 to be suspended in the air. The second locking mechanism includes a second swing arm 91, a second pull wire 93, and a second elastic return member 94. The second swing arm 91 spans the locking seat 73, one end of which is rotatably sleeved on the fixed shaft 12, and the other end has a second locking structure 92. The second locking nodes 7-A are arranged at intervals along the front-to-back direction on one side of the locking seat 73 close to the side wall of the base 1. The second locking structure 92 and the second locking node 7-A are configured as a tongue and a slot, and the two are connected by a snap fit. The second pull wire 93 passes through the top plate of the base 1, with one end fixedly connected to the second locking structure 92 and the other end connected to a handle, which can be installed on the base or the seat. The second elastic reset member 94 is a torsion spring, which is sleeved on the fixed shaft 12, with one end supported on the support 11 and the other end supported on the second swing arm 91. The structure of the handle is the same as the tilt adjustment handle in the applicant's prior application publication number CN109393798A, and will not be repeated here. Pulling the handle with the second pull wire 93 can pull the second locking structure 92 upward, thereby separating it from the second locking node 7-A. After pulling it to a certain angle, the handle is stuck, which can maintain the separation state of the second locking structure 92 and the second locking node 7-A. When the handle is pulled back to release the stuck state, under the action of the second elastic reset member 94, the second swing arm 91 resets and rotates, so that the second locking structure 92 and the second locking node 7-A are engaged.

[0056] The second locking mechanism uses a handle to control the engagement or disengagement of the second locking structures 92 and the second locking node 7-A, which is relatively flexible and simple to operate. When the swing lever 2-1 is at the rearmost end of its swing range, the handle is pulled and locked to separate the two second locking structures 92 from the locking seat 73. The swing lever 2-1 is then tilted back to swing it forward. During the forward swing of the swing lever 2-1, the handle can be pulled back at any time to engage the second locking structures 92 and the second locking node 7-A, thereby locking the gear position.

[0057] Reference Figure 3 、 Figure 5 、 Figure 6 、 Figure 7The first locking mechanism and the second locking mechanism on the left or right side share the same fixed axis 12. The first locking mechanism includes a first swing arm 81, a first pull wire 83, and a first elastic reset member 84. One end of the first swing arm 81 is rotatably sleeved on the fixed axis 12, and the other end has a first locking structure 82 that can engage with the first locking node 6-A. The end of the first swing arm 81 that is rotatably sleeved on the fixed axis 12 is arranged into a forked structure to avoid the second swing arm 91, so that the first swing arm 81 and the second swing arm 91 can be rotatably sleeved on the fixed axis 12 at the same time. The first locking structure 82 and the first locking node 6-A are also configured as a tongue and a slot for snap-fitting. The top of the first collar structure 63 has a support plate structure 631 that extends forward to above the first locking structure 82. The first pull wire 83 passes through the top plate of the base 1 and the support plate structure 631. One end of the first swing arm 81 is fixedly connected to the first locking structure 82, and the other end is connected to a handle. The first elastic return member 84 is a compression spring, which is sleeved outside the first pull wire 83 and supported at both ends on the first locking structure 82 and the support plate structure 631. The operation method is the same as the second locking mechanism and will not be repeated here.

[0058] A support seat 13 is provided between the two supports 11 and directly below the first locking mechanism. The support seat 13 and the base 1 are an integrated structure, formed by the upward protrusion of the bottom plate of the base 1, and is used to support the front section of the main push rod 61. The support seat 13 applies an upward force to it to balance the downward force applied by the first locking structure 82 to the main push rod 61, which can prevent the rear end of the main push rod 61 from tilting upward so that the swing rod 2-1 will not be stuck.

[0059] A slide rail 14 extending forward and backward is provided in the base 1. The slide rail 14 and the base 1 are an integrated structure, formed by the protrusion of the bottom plate of the base 1. The two sides of the slide rail 14 support the two sides of the locking seat 73, so that the locking seat 73 can slide forward and backward along the slide rail 14, and the slide rail 14 acts as a limit for the locking seat 73 to avoid lateral deviation during the forward and backward sliding process.

[0060] The locking seat 73 has a guide slot 73-h extending vertically and forward and backward in the middle. The bottom plate of the base 1 has an upwardly protruding guide rod 15 located in the middle of the slide rail 14. This rod 15 is inserted into the guide slot 73-h and serves to guide the forward and backward sliding movement of the locking seat 73. Furthermore, when the guide rod 15 is positioned at the front and rear ends of the guide slot 73-h, the second locking mechanism can engage with the second locking nodes 7-A at the front and rear ends of the locking seat 73. The guide rod 15 and the guide slot 73-h define the forward and backward sliding range of the locking seat 73, ensuring that the second locking mechanism always has a second locking node 7-A within its range of motion for engagement.

[0061] Implementation Case 2:

[0062] Reference Figure 8A chair capable of reclining forward and backward includes a base 1, a seat 3, a backrest frame 2, and a tilting frame 5. The front and rear ends of the seat 3 are hinged to the upper end of the tilting frame 5 and the middle section of the backrest frame 2, respectively. The front and rear ends of the base 1 are hinged to the lower end of the tilting frame 5 and the front end of the backrest frame 2, respectively. The rear end of the backrest frame 2 is fixedly connected to the backrest frame 4. The bottom of the rear end of the base 1 is fixedly connected to the chair leg frame. The structure of the base 1 and backrest frame 2 is the same as that of Example 1. The base 1 contains at least a main push rod 61, a first ring structure 63, and a first elastic compression structure 62, enabling the chair to be tilted back and then reset.

[0063] Reference Figure 8 、 Figure 9 The base 1, the backrest 2, the seat 3 and the flip frame 5 form a planar four-link structure. The seat 3 is used to fix the seat cushion 32. Figure 10 、 Figure 11 When the chair back frame 2 leans back, the seat 3 also flips back synchronously, so that the angle between the seat cushion 32 and the chair back frame 4 changes less, so that the user's sitting posture can remain basically unchanged during the process of leaning back and forth, especially when the user swings back and forth freely and relaxedly, the waist does not need to twist back and forth, which improves the comfort of the chair.

[0064] The base 1 is tilted downward from the front end to the rear end, so that the vertical gap between the seat 3 and the base 1 gradually increases from the front to the rear end, and the back frame 2 is tilted upward from the front end to the rear end, so that the vertical gap between the seat 3 and the back frame 2 gradually decreases from the front to the rear end.

[0065] When a user sits on the cushion, the pressure on the seat 3 gradually increases from the edges to the center. Under the influence of this pressure distribution, the seat 3 tends to deform downward, forming a pit-like shape at the center. In the prior art, since there is almost no gap between the seat 3 and the base 1, under the direct support of the base 1, even if the seat cushion 32 is elastic, if the seat 3 is completely rigid and has no room for deformation and cushioning, the degree of compression on the seat cushion 32 will gradually increase from the edges to the center, making the center of the seat cushion 32 harder and less comfortable. In the present application, except for the front and rear ends of the seat 3, which are supported by the flip frame 5 and the backrest frame 2 respectively, the rest of the seat 3 is suspended, providing space for the seat 3 to deform slightly, which provides a good cushioning effect when the user sits down and improves comfort, especially for heavier users.

[0066] In the prior art, since there is virtually no clearance between the seat 3 and the base 1, the reclining range of the chair back frame 2 is significantly limited to prevent mechanical interference. Furthermore, due to long-term use and localized deformation, the back frame 2 is prone to jamming and interference when tilting forward and backward. Compared to the prior art, the present invention provides a significant margin of clearance between the base 1 and the seat 3, thus preventing negative impacts on the reclining range and localized deformation caused by prolonged use.

[0067] In addition, the overall structure composed of the seat 3, the tilt frame 5, the base 1, and the backrest frame 2 is in the shape of a triangle, and thus has good overall structural strength and structural stability.

[0068] Reference Figure 9 The seat 3, tilt frame 5, base 1, and backrest frame 2 form a planar four-bar linkage structure. Two backrest frames 2 and two tilt frames 5 are provided, and they are bilaterally symmetrical. The upper portions of the left and right side walls of the base 1, located at the rear section, each have a first hinge point J1. The upper portions of the front ends of the two backrest frames 2 are hinged to the two first hinge points J1. The front ends of the left and right side walls of the base 1 each have a second hinge point J2. The front ends of the left and right sides of the seat 3 each have a fourth hinge point J4. The lower and upper ends of the two tilt frames 5 are hinged to the two second hinge points J2 and the fourth hinge point J4, respectively. The seat 3 is a flat plate-like structure, with third hinge points J3 at its left and right rear ends. The middle section of the backrest frame 2 has brackets 21 extending laterally therefrom. The ends of the two brackets 21 are hinged to the two third hinge points J3.

[0069] The flip frame 5 is roughly triangular in structure. When the chair back frame 2 is tilted forward to the front end (the swing rod 2 - 1 is at the rear end of the swing range), the lower side of the flip frame 5 is flush with the bottom edge of the base 1.

[0070] The back frames 2 expand laterally from front to back, gradually increasing the left-right spacing between the two back frames 2 from front to back, forming an "eight"-shaped expansion structure. This defines the width of the back frame 4, meaning that the width between the two back frames 2 naturally transitions to the width of the back frame 4, resulting in a smoother structural transition and improved overall structural strength and stability of the back frames 2 and 4, while also enhancing the aesthetics. The back frames 2 and the bracket located midway between them are integrally formed, and the bracket's arrangement ensures that the back frames 2 and 4 are sufficiently clear of the rear end of the seat 3.

[0071] Reference Figure 12The backrest frame 4 comprises two backrest connecting sections 41 fixedly connected to the rear end of the backrest frame 2 and extending along its length; two side frames 42 extending upward from the rear end of the two backrest connecting sections 41; a top frame 43 extending laterally from the top ends of the two side frames 42 and closing therewith; and a bottom frame 44 connected between the bottom ends of the two side frames 42. The side frames 42 tilt forward from the bottom to the middle and then tilt backward from the middle to the top; the top frame 43 tilts backward from both sides to the middle; the frame structure formed by the top frame 43, the top frame 43, and the two side frames 42 is used to secure the backrest (not shown). The shape of the side frames 42 gives the backrest a vertically convex angled shape. The upper half of the backrest effectively supports the user's back and waist. The space between the lower half of the backrest and the seat cushion 32 allows the user's buttocks to move deeper into the seat cushion 32, allowing the user to sit straighter and avoid slouching, thereby correcting and protecting the waist, particularly the lumbar spine. The shape change of the top frame 43 causes the middle of the upper half of the back of the chair to be concave inward, so that the left and right sides thereof can better wrap the user's neck and improve comfort.

[0072] The backrest connecting section 41 and the outer edges from the bottom to the middle of the side frame 42 are fixedly connected with an armrest fixing frame 45 extending along the extension direction of the two. The top of the armrest fixing frame 45 is fixedly connected with an armrest 46 extending forward. The fixed connection between the armrest fixing frame 45 and the backrest frame 4 allows the armrest 46 to tilt forward and backward synchronously. When the user uses it, the torso, upper limbs and lower limbs can tilt forward and backward synchronously.

[0073] Reference Figure 13 A cushion support plate 31 is fixed to the top surface of the seat 3. The area of the cushion support plate 31 is larger than that of the seat 3. The bottom surface of the cushion support plate 31 has an inwardly recessed mounting surface 31-A, into which the seat 3 is inserted. A seat cushion 32 is fixed to the top surface of the cushion support plate 31. The cushion support plate 31 increases the mounting area, allowing the seat cushion 32 to be larger, providing greater comfort for the user. Furthermore, the entire front end of the cushion support plate 31 and the seat cushion 32 are curved downward, allowing the user's calves to hang down more naturally.

[0074] Finally, it should be noted that the above implementation cases are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above implementation cases, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above implementation cases, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the implementation cases of the present invention.

Claims

1. A chair that can be tilted forward and backward, comprising a base (1), a seat (3), a backrest frame (2), and a tilt frame (5), wherein the front end and the rear end of the seat (3) are respectively hinged to the upper end of the tilt frame (5) and the middle section of the backrest frame (2), and the front end and the rear section of the base (1) are respectively hinged to the lower end of the tilt frame (5) and the front end of the backrest frame (2); the rear end of the backrest frame (2) is fixedly connected to the backrest frame (4); the bottom of the rear section of the base (1) is fixedly connected to the chair leg frame; characterized in that The base (1) is tilted downward from the front end to the rear end, so that the vertical gap between the seat (3) and the base (1) gradually increases from the front to the rear end; the chair back frame (2) is tilted upward from the front end to the rear end, so that the vertical gap between the seat (3) and the chair back frame (2) gradually decreases from the front to the rear end; the chair seat (3) is used to fix and install the seat cushion (32); The base (1) is a hollow box-shaped structure, and the left and right side walls thereof are respectively provided with a first hinge point (J1) at the upper portion of the rear section. The seat back frames (2) are provided with two, and the upper portions of the front ends of the two seat back frames (2) are respectively hinged to the two first hinge points (J1). A swing rod (2-1) extending left and right is connected between the lower portions of the front ends of the two seat back frames (2). The left and right side walls of the base (1) are respectively provided with an arc groove (1-h) that allows the swing rod (2-1) to pass through and limits the forward and backward swing range of the swing rod (2-1). The front ends of the left and right side walls of the base (1) respectively have second hinge points (J2), and the front ends of the left and right sides of the seat (3) respectively have fourth hinge points (J4); two flip frames (5) are provided, and their lower ends and upper ends are hinged to the second hinge point (J2) and the fourth hinge point (J4).

2. The chair that can be tilted forward and backward according to claim 1, characterized in that: A main push rod (61) extending forward and backward is provided in the base (1), the front end of which slides through a first sleeve ring structure (63) provided in the base (1), and the rear end of which is movably connected to the swing rod (2-1); the main push rod (61) is sleeved with a first elastic compression structure (62), and the two ends of which are respectively supported on the first sleeve ring structure (63) and the swing rod (2-1).

3. The chair capable of reclining forward and backward according to claim 1, characterized in that: The chair back frames (2) are extended sideways from the front end to the rear end, so that the left-right spacing between the two chair back frames (2) gradually increases from the front to the rear, and defines the width of the chair back frame (4).

4. The chair capable of reclining forward and backward according to claim 3, characterized in that: The backrest frame (4) comprises two backrest connecting sections (41) fixedly connected to the rear end of the backrest frame (2) and extending in the direction thereof, two side frames (42) extending upward from the rear ends of the two backrest connecting sections (41), a top frame (43) extending transversely from the top ends of the two side frames (42) and closing together, and a bottom frame (44) connected between the bottom ends of the two side frames (42); the side frames (42) are inclined forward from the bottom end to the middle and then inclined backward from the middle to the top end; the top frame (43) is inclined backward from both sides to the middle; the frame structure formed by the top frame (43), the top frame (43) and the two side frames (42) is used to fix the back of the chair.

5. The chair capable of reclining forward and backward according to claim 4, characterized in that: The outer edges of the chair back connecting section (41) and the side frame (42) from the bottom end to the middle are fixedly connected to an armrest fixing frame (45) extending along the extension direction of the two, and the top end of the armrest fixing frame (45) is fixedly connected to an armrest (46) extending forward.

6. The chair capable of reclining forward and backward according to claim 1, characterized in that: The seat (3) is a flat plate-like structure, and the rear ends of the left and right sides thereof respectively have third hinge points (J3). The middle section of the seat back frame (2) has brackets (21) extending to the sides thereof, and the ends of the two brackets (21) are hinged to the two third hinge points (J3).

7. The chair capable of reclining forward and backward according to claim 1, wherein: A cushion support plate (31) is fixed to the top surface of the seat (3), and the area of the cushion support plate (31) is larger than that of the seat (3); the bottom surface of the cushion support plate (31) has a mounting surface (31-A) formed by an inward depression, and the seat (3) is embedded in the mounting surface (31-A); the top surface of the cushion support plate (31) fixes the seat cushion (32).

8. The chair capable of reclining forward and backward according to claim 7, characterized in that: The entire front ends of the seat cushion support plate (31) and the seat cushion (32) are curved downward.

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