Chair frame

Abstract

Chair frame, including: a seat cushion; a footrest which is pivotably connected to a front end of the seat cushion about a first axis of rotation; a backrest pivotably connected to a rear end of the seat cushion about a second axis of rotation, the backrest being designed to fold relative to the seat cushion along a front-to-back direction of the seat cushion, and the footrest being designed to extend or retract relative to the seat cushion along the front-to-back direction; and a synchronizing element for synchronizing the movement of the footrest and the backrest, wherein the synchronizing element comprises: a rod body that extends along the front-to-back direction of the seat cushion; a front oblique arm connected to the rod body and extending forward and obliquely towards the front of the seat cushion relative to the rod body; and a rear oblique arm that is connected to the rod body and extends rearward and obliquely towards the back of the seat cushion relative to the rod body; wherein one of the rear and front inclined arms is oriented upwards, while the other is oriented downwards; the front inclined arm is pivotably connected to the footrest about a third axis of rotation; and The rear inclined arm is connected to the backrest in a way that allows it to pivot around a fourth axis.

Description

AREA OF USE PATTERN

[0001] The present utility model relates to the field of furniture, in particular a chair frame. BACKGROUND OF THE USAGE SAMPLE

[0002] With the continuous development of the economy and the progress of society, an increasing variety of consumer goods is provided to improve people's lives, with chairs being one such product.

[0003] Existing chair frames are adjustable between sitting and reclining positions to better meet the functional needs of users. However, while current designs synchronize the folding / unfolding movement of the footrest and the forward / backward tilting of the backrest, the coupling mechanism enabling this synchronization is poorly designed. Due to the excessive height difference between the pivot axis of the footrest and the pivot axis of the backrest, the tilt angle of the coupling structure becomes too large, preventing it from being installed within the seat cushion in the forward-backward direction. Consequently, the chair frame lacks a sleek design, and the synchronization between the footrest and backrest is less smooth.

[0004] Additionally, the existing chair frames lack an adjustable headrest tilt and a sliding extension function for the footrest.

[0005] Therefore, there is an urgent need for an improved chair frame to address one or more of these shortcomings. SUMMARY OF THE USAGE SAMPLE

[0006] The purpose of the present utility model is to provide a chair frame that ensures a more even synchronization between the backrest and footrest, while also allowing the connecting rod to be installed inside the seat cushion to achieve a more compact configuration.

[0007] To solve this problem, a chair frame of the present utility model comprises a seat cushion; a footrest pivotably mounted at a front end of the seat cushion about a first axis of rotation; a backrest pivotally mounted at a rear end of the seat cushion about a second axis of rotation, the backrest being designed to fold relative to the seat cushion along a front-back direction of the seat cushion, and the footrest being designed to extend or retract relative to the seat cushion along the front-back direction; and a synchronizing element for synchronizing the movement of the footrest and the backrest.The synchronizing link comprises a rod body extending along the front-to-back direction of the seat cushion; a front inclined arm connected to the rod body extending forward and obliquely relative to the rod body toward the front of the seat cushion; and a rear inclined arm connected to the rod body extending backward and obliquely relative to the rod body toward the back of the seat cushion. One of the rear and one of the front inclined arms are oriented upwards, while the other is oriented downwards; the front inclined arm is pivotally connected to the footrest about a third axis, and the rear inclined arm is pivotally connected to the backrest about a fourth axis.

[0008] In contrast to the prior art, the front inclined arm of the present application extends obliquely relative to the rod body towards the front of the seat cushion, while the rear inclined arm extends obliquely relative to the rod body towards the back of the seat cushion. The front and rear inclined arms are arranged such that one points upwards and the other downwards. This reduces the inclination of the rod body of the synchronizing link caused by the height difference between the third and fourth hinge center lines. This allows the rod body of the synchronizing link to pass through the seat cushion in a front-to-back direction, resulting in a more compact structure for the chair frame of the present utility model.On the other hand, this arrangement improves the pivoting action of the synchronizing link during the coupling process between the backrest and footrest, making the synchronous coupling between the backrest 30 and the footrest more sensitive and uniform.

[0009] Preferably, the rear inclined arm has a greater length than the front inclined arm.

[0010] Preferably, the rod body is arranged inside the seat cushion, and the rear inclined arm is located outside the seat cushion.

[0011] Preferably, a thickened reinforcement structure is provided at a corner between the rod body and the front inclined arm and / or at a corner between the rod body and the rear inclined arm; a positioning notch is provided at the corner between the rod body and the rear inclined arm; the backrest is accordingly provided with a positioning support post designed to engage in the positioning notch from below to support the synchronizing link, and the second axis of rotation coincides with a central axis of the positioning support post.

[0012] Preferably, the first axis of rotation, the second axis of rotation, the third axis of rotation and the fourth axis of rotation are parallel to each other; the distance between the first axis of rotation and the second axis of rotation is smaller than the distance between the fourth axis of rotation and the third axis of rotation and larger than the distance between the fourth axis of rotation and the second axis of rotation; and the distance between the fourth axis of rotation and the second axis of rotation is larger than the distance between the third axis of rotation and the first axis of rotation.

[0013] Preferably, the chair frame further comprises a base and a connecting rod, which is pivotably connected to the base about a fifth axis of rotation and pivotably connected to the backrest about a sixth axis of rotation. The seat cushion is pivotably connected to the base about a seventh axis of rotation, so that the base, the connecting rod, the backrest, and the seat cushion together form a planar four-bar linkage; and during a folding movement of the backrest relative to the seat cushion, the backrest drives the seat cushion, via the connecting rod, to pivot synchronously relative to the base.

[0014] Preferably, the base is arranged adjacent to the backrest; the first, second, third, fourth, fifth, sixth and seventh axes of rotation are parallel to each other; the fifth axis of rotation is located behind the seventh axis of rotation and in front of the second axis of rotation; and the sixth axis of rotation is located in front of and above the second axis of rotation and above the fifth axis of rotation.

[0015] Preferably, the distance between the seventh axis of rotation and the second axis of rotation is greater than the distance between the seventh axis of rotation and the fifth axis of rotation, and the distance between the seventh axis of rotation and the fifth axis of rotation is greater than both the distance between the sixth axis of rotation and the second axis of rotation and the distance between the fifth axis of rotation and the sixth axis of rotation.

[0016] Preferably, the footrest comprises a folding base frame which is pivotably mounted at the front end of the seat cushion about the first axis of rotation; a sliding frame which is slidably mounted on the folding base frame; and a coupling assembly which is arranged between the sliding frame and the seat cushion and is designed to extend or retract the sliding frame relative to the folding base frame when the folding base frame pivots about the first axis of rotation.

[0017] Preferably, the coupling assembly comprises a first rod, a second rod, a push-pull rod, and a folding base. The first rod is pivotably connected to the sliding frame and the second rod; the second rod is further pivotably connected to the folding base frame and, together with the folding base frame, the first rod, the second rod, and the sliding frame, forms a crank-slide mechanism; the folding base is pivotably connected to the seat cushion about a folding axis parallel to the first axis of rotation; and the push-pull rod is pivotally connected to the folding base and the second rod.

[0018] Preferably, the second rod is pivotably connected to a left or right side of the folding base frame; the push-pull rod is pivotably connected to a central section of the second rod; the first rod is pivotably connected to a central section of the sliding frame; and a low-noise slide rail is provided between the sliding frame and the folding base frame.

[0019] Preferably, the chair frame further comprises a headrest, a hinge, a spring, and a handle. The headrest is mounted to the backrest via the hinge; the spring is arranged between the footrest and the seat cushion and is designed to pre-tension the footrest towards a retracted position; the handle extends in the left-right direction of the seat cushion through the rear end of the seat cushion and the synchronizing link; and the rod body is provided with an arc-shaped slot through which the handle can be passed, thereby allowing the handle to selectively lock or release the synchronizing link. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a top view of the chair frame according to the present utility model in the seated position, viewed along the direction from left to right of the seat cushion. Fig. Figure 2 is a top view of the chair frame according to the present utility model in a reclining position, viewed along the direction from left to right of the seat cushion. Fig. 3 is a top view of Fig. 2, with the headrest adjusted to align with the backrest. Fig. Figure 4 is a perspective view of the chair frame in Fig. 1. Fig. 5 is a perspective view of Fig. 4 from a different angle, with the footrest hidden. Fig. 6 is a perspective view of Fig. 4, with the footrest, spring and seat cushion hidden. Fig. Figure 7 is a perspective view of the footrest in Fig. 1. Fig. Figure 8 is a perspective view of the chair frame in Fig. 3. Fig. 9 is a perspective view of Fig. 8, with the footrest, spring and seat cushion hidden. Fig. Figure 10 is a perspective view of the footrest in Fig. 8, with the folding base hidden. Fig. Figure 11 is a perspective view of the synchronization element. Fig. Figure 12 is a perspective view of the synchronization element from a different angle. Fig. Figure 13 is a top view of the synchronization element along the direction of the arrow in Fig. 11. DETAILED DESCRIPTION OF THE EXECUTION FORMS SHOWN

[0020] In order to provide a detailed explanation of the technical content and structural features of the present utility model, the implementation method is further explained below in conjunction with the accompanying drawings.

[0021] The preferred embodiments of the present utility model are described below with reference to the drawings.

[0022] With reference to Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 8 The chair frame 100 of the present utility model comprises a seat cushion 10, a footrest 20 which is pivotably connected about a first pivot axis C1 to a front end 11 of the seat cushion 10, a backrest 30 which is pivotably connected about a second pivot axis C2 to a rear end 12 of the seat cushion 10, and a synchronizing element 40 for synchronizing the movement between the footrest 20 and the backrest 30.

[0023] Specifically, the backrest 30 is designed to fold relative to the seat cushion 10 along the front-to-back direction of the seat cushion 10, in order to meet the requirement that the backrest 30 be able to fold forward or backward about the second axis of rotation C2. Optionally, the backrest 30 is, as shown in Fig. 4 shown, pivotable on both the left and right sides about the second axis of rotation C2 connected to the rear end 12 of the seat cushion 10 in order to further improve the reliability of the folding movement of the backrest relative to the seat cushion 10.

[0024] Furthermore, the footrest 20 can fold and extend / retract relative to the seat cushion 10 along the front-to-back direction. When not in use, the footrest 20 can be folded under the seat cushion 10 (as shown in Fig. (shown in Figure 1), which prevents the footrest 20 from protruding forward from the seat cushion 10 when the chair frame 100 is in the seated position and obstructing the user's feet. The footrest 20 is optional, as shown in Figure 1. Fig. 4 shown, connected to the front end 11 of the seat cushion 10 on both the left and right sides about the first axis of rotation C1, in order to further increase the reliability of the folding movement of the footrest relative to the seat cushion 10.

[0025] The rear inclined arm 43 is oriented upwards, while the front inclined arm 42 is oriented downwards, ensuring that they are not on the same side (e.g., top or bottom) of the rod body 41. The front inclined arm 42 is pivotally connected to the footrest 20 about a third pivot axis C3, and the rear inclined arm 43 is pivotally connected to the backrest 30 about a fourth pivot axis C4. Optionally, as shown in Fig. As shown in Figure 1, the seat cushion 10, the footrest 20, the backrest 30, and the synchronizing link 40 together form a planar four-bar linkage. Specifically, as shown in Figure 1, the seat cushion 10, the footrest 20, the backrest 30, and the synchronizing link 40 together form a planar four-bar linkage. Fig. 1, Fig. 4, Fig. 5, Fig. 6 and Fig. Figure 9 shows the first axis of rotation C1, the second axis of rotation C2, the third axis of rotation C3, and the fourth axis of rotation C4 parallel to each other. The distance between the fourth axis of rotation C4 and the second axis of rotation C2 is greater than the distance between the third axis of rotation C3 and the first axis of rotation C1 (as shown in Figure 9). Fig. 1 shown). Thus, during the transition of the chair frame 100 between the sitting and reclining positions, the folding speed of the footrest 20 relative to the seat cushion 10 is greater than the synchronized folding speed of the backrest 30 relative to the seat cushion 10. This ensures that the folding angle of the backrest is smaller than the folding angle of the footrest, so that the footrest 20 extends into the forward upper position of the seat cushion 10 when in use (as shown in Figure 1). Fig. 2 and Fig. 3 shown) and folds up under the seat cushion 10 when not in use (as shown in Fig. 1 shown).

[0026] It should be noted that, although Fig. 11, Fig. 12 to Fig. 13 showing the front inclined arm 42 pointing downwards and the rear inclined arm 43 pointing upwards; the reverse arrangement (front inclined arm 42 pointing upwards and rear inclined arm 43 pointing downwards) is also possible depending on actual requirements and therefore does not refer to the one in Fig. 11, Fig. 12 to Fig. The configuration shown in 13 is limited.

[0027] Specifically, as in Fig. As shown in Figure 1, the distance between the first axis of rotation C1 and the second axis of rotation C2 is smaller than the distance between the fourth axis of rotation C4 and the third axis of rotation C3, while the distance between the first axis of rotation C1 and the second axis of rotation C2 is larger than the distance between the fourth axis of rotation C4 and the second axis of rotation C2. In such an arrangement, it is ensured that the synchronizing link 40 and the seat cushion 10 form the two long links of the planar four-bar linkage, while the footrest 20 and the backrest 30 form the two short links.

[0028] As in Fig. 11, Fig. 12 to Fig. As shown in Figure 13, the length L2 of the rear inclined arm 43 is greater than the length L1 of the front inclined arm 42 in order to further improve the pivoting effect of the synchronizing link 40 during coupling between the backrest 30 and the footrest 20. Additionally, as shown in Fig. 4 and Fig. As shown in Figure 5, the rod body 41 is arranged within the seat cushion 10, thus protecting the rod body 41 and avoiding potential lateral crushing hazards for users should it be exposed. The rear inclined arm 43 is located outside the seat cushion 10 to better facilitate its side-by-side arrangement and pivotable connection with the backrest 30. As shown in Figure 5, the following options are available: Fig. 1, Fig. 2, Fig. 3 to Fig. As shown in Figure 4, the rear inclined arm 43 is pivotally connected to the backrest 30 from the outside to avoid potential pressure sores on the user if it were connected from the inside. It should be noted that if the footrest 20 and the backrest 30 are pivotally connected to the seat cushion 10 on both the left and right sides, the synchronizing links 40 are positioned accordingly on the left and right to connect the respective synchronizing link 40 to the footrest 20 and the backrest 30.

[0029] What's next in Fig. 11, Fig. 12 to Fig. As shown in Figure 13, thickened reinforcing structures 44 are provided at the corners between the rod body 41 and the front inclined arm 42, as well as between the rod body 41 and the rear inclined arm 43. These structures increase the strength at these corners, allowing the backrest 30 to achieve a larger folding angle relative to the seat cushion 10, while simultaneously maintaining sufficient strength of the synchronizing link 40. The maximum folding angle α2 is shown in Figure 13. Fig. 2 shown, which enables the chair frame 100 to achieve a zero-gravity function. Additionally, a downward-facing positioning groove 45 is provided at the corner between the rod body 41 and the rear inclined arm 43. The backrest 30 is accordingly equipped with a positioning support column 31 that engages in the positioning groove 45 to support the synchronizing element 40 from below (as shown in Fig. (9 shown), which ensures stability when the chair frame 100 is in the reclining position. Here, the second pivot axis C2 coincides with the central axis of the positioning support column 31 to simplify the structure. Specifically, when the chair frame 100 is in the sitting position ( Fig. 1) The angle α2 between the backrest (30°) and the seat cushion (10°) is 105°. In the reclining position ( Fig. 2 and Fig. 3) This angle α2 is 130 degrees. It should be noted that, although Fig. 11 the thickened reinforcement structures 44 at both corners shows, depending on the actual need, only one corner may be provided with such a structure and therefore not on the in Fig. The configuration shown in 11 is limited.

[0030] As in Fig. 5, Fig. 6 and Fig. As shown in Figure 9, the chair frame 100 further comprises a base 50 and a connecting rod 60. The connecting rod 60 is pivotally connected to the base 50 about a fifth pivot axis C5 and to the backrest 30 about a sixth pivot axis C6. The seat cushion 10 is pivotally connected to the base 50 about a seventh pivot axis C7 and, together with the base 50, the connecting rod 60, and the backrest 30, forms a planar four-bar linkage mechanism. Thus, when the backrest 30 folds relative to the seat cushion 10, it drives the seat cushion 10, via the connecting rod 60, to fold synchronously relative to the base 50. When transitioning from the sitting position to the reclining position, the seat cushion 10, the backrest 30 and the footrest 20 tilt backwards together relative to the base 50, causing the footrest 20 to be higher and the backrest 30 to be lower in the reclining position, which further improves the zero-gravity function of the chair frame 100.Specifically, as in . Fig. 6 and Fig. As shown in Figure 9, the base 50 is arranged directly in front of the backrest 30. The first to seventh axes of rotation (C1-C7) are parallel to each other, with the fifth axis of rotation C5 located behind the seventh axis of rotation C7 and in front of the second axis of rotation C2. The sixth axis of rotation C6 is located in front of and above the second axis of rotation C2 and above the fifth axis of rotation C5 (as shown in Figure 9). Fig. 6 and Fig. (9 shown). Additionally, the distance between the seventh axis of rotation C7 and the second axis of rotation C2 is greater than the distance between the seventh axis of rotation C7 and the fifth axis of rotation C5. The latter distance is also greater than both the distance between the sixth axis of rotation C6 and the second axis of rotation C2 and the distance between the fifth axis of rotation C5 and the sixth axis of rotation C6 ( Fig. 6 and Fig. 9) This arrangement ensures that the seat cushion 10 undergoes a small-angle folding process relative to the base 50 during the transition between sitting and reclining positions, thus preventing excessive tilting relative to the horizontal plane. More precisely, in Fig. 6 and Fig. 9 The distance between the sixth pivot axis C6 and the second pivot axis C2 is equal to the distance between the fifth pivot axis C5 and the sixth pivot axis C6. It should be noted that if the footrest 20 is pivotably connected to the front end 11 of the seat cushion 10 on both the left and right sides, the base 50 and the connecting rod 60 are positioned accordingly on the left and right to meet the requirement of an symmetrical connection with the seat cushion 10 and the backrest 30. A foot stand 93 is connected to the base 50 below the seat cushion 10 so that the chair frame 100 can stand stably on the floor.

[0031] As in Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. As shown in Figure 10, the footrest 20 comprises a folding base frame 21, which is pivotably connected to the front end 11 of the seat cushion 10 about the first axis of rotation C1, a sliding frame 22, which is slidably mounted on the folding base frame 21, and a coupling arrangement 23 between the sliding frame 22 and the seat cushion 10. The coupling arrangement 23 drives the sliding frame 22 to extend or retract relative to the folding base frame 21 when the latter folds relative to the seat cushion 10 about the first axis of rotation C1. The extended state of the sliding frame 22 is shown in Fig. 2, Fig. 3, Fig. 8, Fig. 9 and Fig. 10 shown, while the retracted state in Fig. 1, Fig. 5 and Fig. Figure 7 is shown. In the reclining position, the extended sliding frame 22 increases the length of the footrest for improved comfort.

[0032] Specifically, the coupling arrangement comprises 23 with reference to Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9 to Fig. 10 a first rod 231, a second rod 232, a folding base 234, a push-pull rod 233, and a folding base 234. The first rod 231 is pivotally connected to both the sliding frame 22 and the second rod 232. The second rod 232 is also pivotally connected to the folding base frame 21 and, together with the folding base frame 21, the first rod 231, the second rod 232, and the sliding frame 22, forms a crank-slider mechanism. The folding base 234 is pivotally connected to the seat cushion 10 about a folding axis 235, the folding axis 235 being parallel to the first pivot axis C1 to allow folding in the front-to-back direction. The push-pull rod 233 is pivotally connected to both the folding base 234 and the second rod 232.Thus, when the folding base 234 rotates around the folding axis 235, it drives the second rod 232 to oscillate via the push-pull rod 233, which in turn moves the sliding frame 22 via the first rod 231. More precisely, in . Fig. 8, Fig. 9 to Fig. 10. The second rod 232 is pivotally connected to the right side of the folding base frame 21 (the left side is also possible). The push-pull rod 233 is pivotally connected to the center of the second rod 232, and the first rod 231 is pivotally connected to the center of the sliding frame 22. This central force application ensures smooth movement of the sliding frame 22. A noiseless guide rail 24 (e.g., made of POM plastic) is installed between the sliding frame 22 and the folding base frame 21 to enable smooth, quiet, and self-lubricating movement. Optionally, as shown in Fig. Figure 10 shows three spaced noiseless slide rails 24 used, and the push-pull rod 233 uses a ball joint for compact and smooth operation.

[0033] For resetting the footrest, headrest and maintaining posture, the chair frame comprises 100 with reference to Fig. Figures 1-6 and 8-9 further include a headrest 70, a hinge 80, a spring 91, and a handle 92. The headrest 70 is adjustable via the hinge 80 to the backrest 30 to ensure optimal head support. The spring 91 is arranged between the footrest 20 and the seat cushion 10 to pre-tension the footrest 20 towards the folded position (front end hooked onto a post 25 of the folding base frame 21, rear end attached to the seat cushion 10). In other embodiments, two springs 91 are arranged on the right and left sides to ensure reliability. The handle 92 extends laterally through the rear end 12 of the seat cushion 10 and the synchronizing element 40. The rod body 41 has an arc-shaped slot 411, via which the handle 92 selectively locks or unlocks the synchronizing element 40 to prevent or enable transitions between the sitting position and the lying position.It should be noted that the hinge 80 and the handle 92 use conventional structures which are not described in detail here.

[0034] With reference to Fig. 1-10 describes the change of the chair frame 100 of the present utility model between the sitting position and the lying position as follows.

[0035] If the chair frame 100 of the present utility model is placed in the Fig. When the seat position shown in Figure 1 is set, the synchronizing link 40 is locked by the handle 92, preventing the seat cushion 10, the backrest 30, and the footrest 20 from rotating. At this point, the angle α2 between the seat cushion 10 and the backrest 30 is 105 degrees, the angle α1 between the seat cushion 10 and the horizontal plane is 9 degrees, and the angle α3 between the seat cushion 10 and the footrest 20 is 40 degrees. Additionally, the headrest 70 can be adjusted relative to the backrest 30 via the hinge 80 within a range of 40 degrees.

[0036] If necessary, the chair frame 100 from the in Fig. 1 shown seating position in the in Fig. To adjust the reclining position shown in section 2, the synchronizing link 40 is released from the locking mechanism using the handle 92. The backrest 30 is then moved into position 2. Fig. 1 rotated clockwise, whereby the footrest 20 is also turned via the synchronizing link 40 in Fig. 1 is rotated clockwise while at the same time the seat cushion 10 is moved over the connecting rod 60 into Fig. 1 is turned clockwise until the in Fig. The state shown in section 2 has been reached.

[0037] In Fig. 2. The angle α2 between the backrest 30 and the seat cushion 10 is 130 degrees, the angle α4 between the footrest 20 and the horizontal plane is 13 degrees, the footrest 20 can be extended by 145 mm, and the angle α5 between the headrest 70 and the backrest 30 is 40 degrees, which means that the headrest 70 is set forward by 40 degrees. Additionally, the angle α6 between the backrest 30 and the horizontal plane is 25 degrees. It is further explained that during the clockwise rotation of the footrest 20 in Fig.1 the coupling arrangement 23 also drives the sliding frame 22 to extend and slide relative to the folding base frame 21.

[0038] In contrast to the prior art, the front inclined arm 42 of the present application extends obliquely relative to the rod body 41 towards the front of the seat cushion 10, the rear inclined arm 43 extends obliquely relative to the rod body 41 towards the back of the seat cushion 10, and the front inclined arm 42 and the rear inclined arm 43 are arranged such that one is oriented upwards and the other downwards. This reduces the inclination of the rod body 41 of the synchronizing element 40, which is caused by the height difference between the third hinge centerline C3 and the fourth hinge centerline C4. This allows the rod body 41 of the synchronizing element 40 to pass through the seat cushion 10 in a front-to-back direction, thus ensuring a more compact structure of the chair frame 100 of the present utility model.On the other hand, this arrangement improves the pivoting effect of the synchronizing link 40 during the coupling process between the backrest 30 and the footrest 20, making the synchronous coupling between the backrest 30 and the footrest 20 more sensitive and uniform.

[0039] The foregoing disclosure merely presents preferred embodiments of the present utility model and cannot be used to limit the scope of protection of the present utility model. Therefore, all equivalent modifications made according to the claims of the present utility model are within the scope of protection of the present utility model.

Claims

[1] Chair frame, comprising: a seat cushion; a footrest which is pivotably connected to a front end of the seat cushion about a first axis of rotation; a backrest which is pivotably connected to a rear end of the seat cushion about a second axis of rotation, wherein the backrest is designed to fold relative to the seat cushion along a front-back direction of the seat cushion, and the footrest is designed to extend or retract relative to the seat cushion along the front-back direction; and a synchronizing element for synchronizing the movement of the footrest and the backrest, wherein the synchronizing element comprises: a rod body that extends along the front-to-back direction of the seat cushion; a front oblique arm connected to the rod body and extending forward and obliquely towards the front of the seat cushion relative to the rod body; and a rear oblique arm that is connected to the rod body and extends rearward and obliquely towards the back of the seat cushion relative to the rod body; wherein one of the rear and front inclined arms is oriented upwards, while the other is oriented downwards; the front inclined arm is pivotably connected to the footrest about a third axis of rotation; and The rear inclined arm is connected to the backrest in a way that allows it to pivot around a fourth axis. [2] Chair frame according to claim 1, wherein the rear inclined arm has a greater length than the front inclined arm, the rod body is arranged inside the seat cushion and the rear inclined arm is arranged outside the seat cushion. [3] Chair frame according to claim 1, wherein a thickened reinforcing structure is provided at a corner between the rod body and the front inclined arm and / or at a corner between the rod body and the rear inclined arm; wherein a positioning groove is provided at the corner between the rod body and the rear inclined arm; wherein the backrest is provided accordingly with a positioning support column designed to engage with the positioning groove from below to support the synchronizing element, and wherein the second axis of rotation coincides with a central axis of the positioning support column. [4] Chair frame according to claim 1, wherein the first axis of rotation, the second axis of rotation, the third axis of rotation and the fourth axis of rotation are parallel to each other, wherein a distance between the first axis of rotation and the second axis of rotation is less than a distance between the fourth axis of rotation and the third axis of rotation and is greater than a distance between the fourth axis of rotation and the second axis of rotation, and wherein the distance between the fourth axis of rotation and the second axis of rotation is greater than a distance between the third axis of rotation and the first axis of rotation. [5] Chair frame according to claim 1, further comprising a base and a connecting rod which is pivotably connected to the base about a fifth axis of rotation and which is pivotably connected to the backrest about a sixth axis of rotation, wherein the seat cushion is pivotably connected to the base about a seventh axis of rotation, such that the base, the connecting rod, the backrest and the seat cushion together form a planar four-bar linkage mechanism; and wherein, during a folding movement of the backrest relative to the seat cushion, the connecting rod drives the seat cushion to pivot synchronously relative to the base. [6] Chair frame according to claim 5, wherein the base is arranged directly in front of the backrest, wherein the first, second, third, fourth, fifth, sixth and seventh axes of rotation are parallel to each other, wherein the fifth axis of rotation is arranged behind the seventh axis of rotation and in front of the second axis of rotation, and wherein the sixth axis of rotation is arranged in front of and above the second axis of rotation and above the fifth axis of rotation; wherein a distance between the seventh axis of rotation and the second axis of rotation is greater than a distance between the seventh axis of rotation and the fifth axis of rotation, and wherein the distance between the seventh axis of rotation and the fifth axis of rotation is greater than both a distance between the sixth axis of rotation and the second axis of rotation and a distance between the fifth axis of rotation and the sixth axis of rotation. [7] Chair frame according to claim 1, wherein the footrest comprises: a folding base frame which is pivotably connected to the front end of the seat cushion around the first axis of rotation; a sliding frame that is mounted to slide on the folding base frame; and a coupling arrangement located between the sliding frame and the seat cushion, designed to extend or retract the sliding frame relative to the folding base frame when the folding base frame pivots about the first axis of rotation. [8] Chair frame according to claim 7, wherein the coupling arrangement comprises a first rod, a second rod, a push-pull rod and a folding base; wherein the first rod is pivotably connected to the sliding frame and the second rod; wherein the second rod is further pivotably connected to the folding base frame and together with the folding base frame, the first rod, the second rod and the sliding frame forms a crank-slider mechanism; wherein the folding base is pivotably connected to the seat cushion about a folding axis, the folding axis being parallel to the first axis of rotation; and wherein the push-pull rod is pivotably connected to the folding base and the second rod. [9] Chair frame according to claim 8, wherein the second rod is pivotably connected to a left or right side of the folding base frame; wherein the push-pull rod is pivotably connected to a central section of the second rod; wherein the first rod is pivotably connected to a central section of the sliding frame; and wherein a noiseless slide rail is provided between the sliding frame and the folding base frame. [10] Chair frame according to claim 1, further comprising a headrest, a hinge, a spring and a handle, wherein the headrest is mounted on the backrest via the hinge; wherein the spring is arranged between the footrest and the seat cushion and is designed to bias the footrest towards a retracted position; wherein the handle extends in a left-right direction of the seat cushion through the rear end of the seat cushion and the synchronizing element; and wherein the rod body is provided with an arc-shaped slot through which the handle is passed, so that the handle can selectively lock or release the synchronizing element.

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