A backrest chair

Abstract

This utility model provides a backrest chair, belonging to the technical field of daily necessities. It solves the problem of insufficient structural stability in existing backrest chairs made of plastic materials. The backrest chair includes a seat, a backrest, two front legs, and two rear legs. The two rear legs are respectively located on the left and right sides of the backrest and fixedly connected to the seat. The backrest has a horizontally arranged crossbar made of plastic material. The chair also includes a reinforcing rod, which is a round metal rod with bolt holes on both ends. The outer circumference of the reinforcing rod has protrusions. The crossbar is straight and has an internal hole extending through both ends axially. The reinforcing rod passes through the crossbar and fits tightly with the hole wall. Both ends of the crossbar abut against the inner surfaces of the two rear legs. Each rear leg has a fastener threaded through the bolt hole on the end face of the reinforcing rod. This utility model is not only easy to assemble but also has high structural stability.

Description

Technical Field

[0001] This utility model belongs to the field of daily necessities technology and relates to a backrest chair. Background Technology

[0002] A backrest chair is a common type of seating, characterized by a backrest that provides back support for the user. Backrest chairs are widely used in various environments such as homes, offices, schools, and restaurants, meeting different sitting and reclining needs. In addition, some backrest chairs can be mounted on swings and used as swing chairs.

[0003] Currently, the backrest chairs used on conventional swings typically employ a metal frame structure to meet specific load-bearing and safety requirements. This frame is then covered with materials such as plastic, metal, or fabric to provide a comfortable seating experience. For example, a dual-purpose swing chair disclosed in patent literature (application number: 201220648157.1) includes a support frame with horizontal bars at the top. The swing chair has a frame structure composed of a seat tube, a middle tube, and a back tube, with the lower end of the suspension device connected to the frame. Another example is a portable children's swing chair disclosed in patent literature (application number: 200710067969.0), whose seat also features a frame structure composed of a support tube, seat tube, and backrest tube. While the frame structure of existing conventional swing chairs ensures strength and durability, the large amount of steel used results in high costs.

[0004] In some chairs designed for everyday sitting or reclining, where the high-intensity dynamic loads of a swing chair are not required, metal frames are often omitted in favor of large areas of plastic. For example, a hollow blow-molded bench disclosed in Chinese patent literature (application number: 200920197454.7) features a backrest, seat panel, and left and right armrests. All components—backrest, seat panel, and armrests—are hollow blow-molded parts. The left and right armrests extend downwards to form leg frames, and slightly rearwards to form positioning frames that engage with the backrest. The backrest and seat panel are secured to the left and right armrests via connectors to form the entire bench. This design reduces costs by minimizing steel usage; however, because both the backrest and the positioning frames are made of plastic and connected only by bolts, overall stability is insufficient. After prolonged use, external forces can cause deformation of the plastic at the connection between the backrest and the positioning frames. Moreover, this type of chair with a backrest cannot withstand the large dynamic load generated when a swing is swinging, thus limiting its applicability as a swing chair or in other diverse usage scenarios. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a backrest chair. This invention solves the problem of insufficient structural stability in existing backrest chairs made of plastic materials while ensuring easy assembly.

[0006] The purpose of this utility model can be achieved through the following technical solution: A backrest chair includes a seat, a backrest, two front legs and two rear legs. The two rear legs are respectively disposed on the left and right sides of the backrest and fixedly connected to the seat. The backrest has a horizontally arranged crossbar made of plastic material. The chair is characterized in that it also includes a reinforcing rod. The reinforcing rod is a round metal rod with bolt holes on both ends. The outer circumference of the reinforcing rod has protrusions. The crossbar is straight and has an inner hole that passes through both ends along the axial direction. The reinforcing rod passes through the crossbar and fits tightly with the hole wall of the inner hole. The two ends of the crossbar abut against the inner sides of the two rear legs. Each rear leg is provided with a fastener threadedly connected to the bolt hole on the end face of the reinforcing rod.

[0007] Based on the technical problems solved, this chair features an improved backrest installation method to enhance both the stability of the backrest and the overall structural stability of the chair. Specifically, the applicant designed a specially structured reinforcing rod. This rod is round with bolt holes at both ends and protrusions on its outer circumference. Simultaneously, an axial through-hole is formed on the crossbar of the chair. During installation, the reinforcing rod is first inserted into the through-hole of the crossbar, and then the protrusions are driven into the hole by tapping, ultimately ensuring a tight fit between the reinforcing rod and the hole wall. Next, the two rear support legs are placed against the ends of the crossbar, bolts are inserted and tightened, completing the assembly of the support legs and the backrest.

[0008] When the chair is used as a swing chair, the rear support legs are connected to swing cables, causing the rear support legs to bear significant external forces. The reinforcing rod's design transfers this force to it, and the protrusions on its outer surface cause deformation at the contact point between the crossbar and the protrusions, creating an "interlocking" effect that restricts the axial displacement of the reinforcing rod. This allows the force on the support legs to be distributed more evenly across the entire backrest structure, preventing deformation, loosening, or damage to the chair due to excessive stress on the support legs. Furthermore, during assembly, since the reinforcing rod is located inside the crossbar, the protrusions prevent it from rotating with the bolts, simplifying the assembly process. Therefore, the protruding structure on the reinforcing rod serves two purposes: it restricts rotation during bolt tightening for easy installation and limits axial displacement, improving the structural stability of the chair.

[0009] In summary, this chair is not only easy to assemble, but also has high structural stability, which means that it can meet the stability requirements for daily sitting and lying use, as well as the high dynamic load requirements for use in special scenarios such as a swing chair.

[0010] In the aforementioned chair backrest, the protrusion is strip-shaped and its length is aligned with the axis of the reinforcing rod. The top surface of the protrusion is arc-shaped and smoothly transitions to the outer circumference of the reinforcing rod. The reinforcing rod requires a hammering motion to insert the protrusion into the inner hole of the crossbar. The fact that the protrusion's length is aligned with the axis of the reinforcing rod allows it to enter the inner hole more smoothly during hammering. The arc-shaped design of the protrusion's top surface and its smooth transition to the outer circumference of the reinforcing rod further reduce hammering resistance, allowing the reinforcing rod to enter the inner hole of the crossbar more smoothly. Furthermore, the strip-shaped protrusion ensures sufficient contact area between the protrusion and the crossbar, thus ensuring convenient installation of the reinforcing rod and providing a good fastening effect between them, thereby improving the structural stability of the chair backrest.

[0011] In the aforementioned backrest chair, the reinforcing rod has two protrusions, both located at the same end and symmetrically arranged on both sides of the reinforcing rod. The fact that both protrusions are located at the same end means that during installation, only a short distance needs to be hammered into the crossbar, eliminating the need for prolonged hammering of the entire reinforcing rod. This not only improves installation efficiency but also reduces the risk of damage to the crossbar or reinforcing rod due to excessive hammering. The two protrusions also enhance the fastening force between the reinforcing rod and the crossbar, allowing the reinforcing rod to significantly improve the structural stability of the backrest chair.

[0012] In the aforementioned chair backrest, the reinforcing rod has only one protrusion located at one end. This design allows the reinforcing rod to be driven into the crossbar only a short distance during installation, eliminating the need for prolonged hammering of the entire reinforcing rod. This not only improves installation efficiency but also reduces the risk of damage to the crossbar or reinforcing rod due to excessive hammering.

[0013] In the aforementioned chair backrest, the reinforcing rod is a solid rod, and the protrusion is a structure formed by stamping the outer circumference of the reinforcing rod. The solid reinforcing rod has high strength and stability, effectively bearing external loads, thereby improving the structural stability of the chair backrest. The protrusion, formed by stamping, is not only easy to manufacture but also possesses high structural strength, allowing the reinforcing rod to be more stably fixed within the crossbar, restricting its axial displacement and circumferential rotation, ultimately effectively improving the structural stability of the chair backrest.

[0014] In the aforementioned chair backrest, the outer circumferential surface of the reinforcing rod abuts against the wall of the inner hole on the crossbar, and the length of the reinforcing rod is the same as the length of the crossbar. This design allows for a large contact area between the outer circumferential surface of the reinforcing rod and the wall of the inner hole on the crossbar, enabling a tight fit between the reinforcing rod and the crossbar. This allows the reinforcing rod to be more stably fixed within the crossbar, ultimately effectively improving the structural stability of the chair backrest.

[0015] In the aforementioned chair, each rear support leg has an insertion groove on its inner side at the upper end. The sides of both ends of the horizontal bar are formed with stepped surfaces. The ends of the horizontal bars are inserted into the corresponding insertion grooves on the rear support legs, with the stepped surfaces abutting against the inner sides of the rear support legs. The end faces of the horizontal bars abut against the bottom of the corresponding insertion grooves. The insertion grooves allow the horizontal bars to be accurately inserted, making installation more convenient and providing stable support for the ends of the horizontal bars, thus enhancing the connection stability between the backrest and the rear support legs. The stepped surfaces abutting against the inner sides of the rear support legs, and the end faces of the horizontal bars abutting against the bottom of the insertion grooves, increase the contact area between the horizontal bars and the rear support legs, further enhancing the connection stability and improving the overall structural stability of the chair.

[0016] In the aforementioned chair, two front support legs are fixedly connected to the front ends of the left and right sides of the seat, respectively, and an armrest is fixedly connected to the upper end of each front support leg and the rear support leg on the same side. The armrest design not only provides a more comfortable seating experience, but also improves the overall integrity of the chair and further enhances its structural stability because the armrests connect the front and rear support legs respectively.

[0017] In the aforementioned chair, each armrest has a hook hole at its front end, and each rear support leg has a hanging ring fixedly attached to its outer side in the middle. This design allows users to connect the swing ropes to the hook holes and hanging rings, enabling the chair to function as a swing chair. Simultaneously, the hook holes and hanging rings provide stable connection points for the swing chair's suspension, ensuring stability and safety during use.

[0018] In the aforementioned chair with a backrest, the lower ends of each front and rear support leg extend downwards relative to the seat. This design allows the chair to meet the needs of daily sitting and reclining.

[0019] Compared with existing technologies, this chair has the following advantages: This chair is not only easy to assemble, but also has high structural stability, which makes it not only able to meet the stability requirements of daily sitting and lying use, but also meet the high dynamic load requirements when used as a swing chair or other special scenarios. Attached Figure Description

[0020] Figure 1This is a three-dimensional structural diagram of Embodiment 1 of this backrest chair.

[0021] Figure 2 This is a left view of Embodiment 1 of this chair.

[0022] Figure 3 yes Figure 2 Sectional view of AA.

[0023] Figure 4 yes Figure 3 Enlarged view of point A in the middle.

[0024] Figure 5 yes Figure 3 Enlarged view of point B in the middle.

[0025] Figure 6 This is a three-dimensional structural diagram of the reinforcing rod in Embodiment 1.

[0026] Figure 7 This is a partial cross-sectional view of the reinforcing rod in Embodiment 1.

[0027] Figure 8 This is a three-dimensional structural diagram of the rear support leg in Embodiment 1.

[0028] Figure 9 This is a three-dimensional structural diagram of the horizontal bar in Embodiment 1.

[0029] Figure 10 yes Figure 2 A cross-sectional view of BB.

[0030] Figure 11 This is a partial cross-sectional view of the reinforcing rod in Embodiment 2.

[0031] Figure 12 This is a three-dimensional structural diagram of Embodiment 3 of this backrest chair.

[0032] In the diagram, 1 is the seat plate; 2 is the backrest; 21 is the horizontal bar; 211 is the inner hole; 212 is the stepped surface; 22 is the vertical bar; 3 is the rear support leg; 31 is the insertion groove; 32 is the mounting hole; 4 is the reinforcing rod; 41 is the bolt hole; 42 is the protrusion; 5 is the fastener; 6 is the front support leg; 7 is the armrest; 71 is the hanging hole; and 8 is the hanging ring. Detailed Implementation

[0033] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0034] Example 1

[0035] like Figure 1 and Figure 2As shown, this chair includes a seat 1, a backrest 2, two rear support legs 3, and two front support legs 6. The two rear support legs 3 are respectively located on the left and right sides of the backrest 2 and are fixedly connected to the seat 1. The two front support legs 6 are respectively fixedly connected to the front ends of the left and right sides of the seat 1. An armrest 7 is fixedly connected to the upper end of each front support leg 6 and the rear support leg 3 on the same side. The two ends of the armrest 7 are respectively connected to the upper end of the front support leg 6 and the rear support leg 3 on the same side by bolts. The backrest 2 is made of plastic material and has horizontal bars 21 and several vertical bars 22. The upper ends of the vertical bars 22 are inserted and fixed to the horizontal bars 21, and the lower ends are inserted and fixed to the seat 1. Each armrest 7 has a hanging hole 71 at its front end, and a hanging ring 8 is fixedly connected to the outer surface of the middle part of each rear support leg 3. Users can connect the swing rope to the hanging hole 71 and the hanging ring 8 respectively, so that this chair can be used as a swing chair.

[0036] like Figures 3 to 6 As shown, this backrest chair also includes a reinforcing rod 4. The reinforcing rod 4 is a round metal rod with bolt holes 41 on both ends. A protrusion 42 is formed on the outer circumference of the reinforcing rod 4. The crossbar 21 is straight and has an inner hole 211 extending through both ends axially. The length of the reinforcing rod 4 is the same as the length of the crossbar 21, and the reinforcing rod 4 is fixedly inserted into the crossbar 21. During installation, the reinforcing rod 4 is first inserted into the inner hole 211 of the crossbar 21. Simultaneously, the protrusion 42 is driven into the inner hole 211 by tapping. Finally, the outer circumference of the reinforcing rod 4 abuts against the wall of the inner hole 211 on the crossbar 21, and the protrusion 42 causes deformation of the crossbar, resulting in a tight fit between the reinforcing rod 4 and the wall of the inner hole 211 of the crossbar 21. The two ends of the crossbar 21 abut against the inner sides of the two rear support legs 3, and each rear support leg 3 is fitted with a fastener 5 that is threaded into the bolt hole 41 at the end of the reinforcing rod 4.

[0037] like Figure 6 and Figure 7 As shown, the reinforcing rod 4 is a solid rod, and the protrusion 42 is a structure formed by stamping the outer peripheral surface of the reinforcing rod 4. There are two protrusions 42 on the reinforcing rod 4, and both protrusions 42 are located on the outer peripheral surface of the same end of the reinforcing rod 4 and are symmetrically arranged on both sides of the reinforcing rod 4. Each protrusion 42 is strip-shaped and its length direction is along the axis of the reinforcing rod 4. The top surface of the protrusion 42 is arc-shaped and smoothly transitions to the outer peripheral surface of the reinforcing rod 4.

[0038] Combination Figure 4 , Figure 8 and Figure 9 As shown, each rear support leg 3 has an insertion groove 31 on its inner side at the upper end, and the sides of both ends of the crossbar 21 are formed with stepped surfaces 212, as shown. Figure 10As shown, the end of the horizontal bar 21 is fitted into the corresponding insertion groove 31 on the rear support leg 3, and the stepped surface 212 abuts against the inner side of the rear support leg 3. The end face of the horizontal bar 21 abuts against the bottom of the corresponding insertion groove 31. The fastener 5 is a bolt, and a mounting hole 32 with both ends through is provided on the bottom of the insertion groove 31. The fastener 5 passes through the mounting hole 32 and is threadedly connected to the bolt hole 41 at the end of the reinforcing rod 4.

[0039] Example 2

[0040] This embodiment is basically the same as embodiment one in structure and principle, except that: Figure 11 As shown, the reinforcing rod 4 has one protrusion 42 located on the outer circumferential surface of one end of the reinforcing rod 4. This design allows the reinforcing rod 4 to be driven into the crossbar only a short distance during installation, eliminating the need for prolonged hammering of the entire reinforcing rod 4. This not only improves installation efficiency but also reduces the risk of damage to the crossbar or reinforcing rod 4 due to excessive hammering.

[0041] Example 3

[0042] This embodiment is basically the same as embodiment one in structure and principle, except that: Figure 12 As shown, the lower ends of each front support leg 6 and each rear support leg 3 extend downwards relative to the seat plate 1 by a certain distance, while the hanging rings 8 and the hanging holes 71 on the armrests 7 are omitted. This design of the chair back can meet the needs of daily sitting and reclining.

[0043] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

[0044] Although this document frequently uses terms such as 1. seat plate; 2. backrest; 21. horizontal bar; 211. inner hole; 212. stepped surface; 22. vertical bar; 3. rear support leg; 31. insertion groove; 32. mounting hole; 4. reinforcing rod; 41. bolt hole; 42. protrusion; 5. fastener; 6. front support leg; 7. armrest; 71. hanging hole; 8. hanging ring, etc., the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any kind of additional limitation would contradict the spirit of this utility model.

Claims

1. A chair with a backrest, comprising a seat (1), a backrest (2), two front support legs (6) and two rear support legs (3), wherein the two rear support legs (3) are respectively disposed on the left and right sides of the backrest (2) and fixedly connected to the seat (1), the backrest (2) having horizontally arranged crossbars (21) made of plastic material, characterized in that, The chair also includes a reinforcing rod (4), which is a round metal rod with bolt holes (41) on both ends. The reinforcing rod (4) has a protrusion (42) on its outer circumference. The crossbar (21) is straight and has an inner hole (211) that runs through both ends along the axial direction. The reinforcing rod (4) passes through the crossbar (21) and fits tightly with the hole wall of the inner hole (211). The two ends of the crossbar (21) abut against the inner side of the two rear support legs (3). Each rear support leg (3) is provided with a fastener (5) that is threaded to the bolt hole (41) on the end face of the reinforcing rod (4).

2. The chair with a backrest according to claim 1, characterized in that, The protrusion (42) is strip-shaped and its length direction is along the axis of the reinforcing rod (4). The top surface of the protrusion (42) is arc-shaped and smoothly transitions to the outer peripheral surface of the reinforcing rod (4).

3. The backrest chair according to claim 1 or 2, characterized in that, The reinforcing rod (4) has two protrusions (42), both of which are located at the same end of the reinforcing rod (4) and are symmetrically arranged on both sides of the reinforcing rod (4).

4. The backrest chair according to claim 1 or 2, characterized in that, The reinforcing rod (4) has one protrusion (42) located at one end of the reinforcing rod (4).

5. The backrest chair according to claim 1 or 2, characterized in that, The reinforcing rod (4) is a solid rod, and the protrusion (42) is a structure formed by stamping the outer circumferential surface of the reinforcing rod (4).

6. The backrest chair according to claim 1 or 2, characterized in that, The outer circumferential surface of the reinforcing rod (4) is in contact with the wall of the inner hole (211) on the crossbar (21), and the length of the reinforcing rod (4) is the same as the length of the crossbar (21).

7. The backrest chair according to claim 1 or 2, characterized in that, Each rear support leg (3) has an insertion groove (31) on its inner side at the upper end. The two sides of the crossbar (21) are formed with stepped surfaces (212). The ends of the crossbar (21) are matched and inserted into the insertion groove (31) on the corresponding rear support leg (3), and the stepped surfaces (212) abut against the inner side of the rear support leg (3). The end face of the crossbar (21) abuts against the bottom of the corresponding insertion groove (31).

8. The backrest chair according to claim 1 or 2, characterized in that, Two front support legs (6) are fixedly connected to the front ends of the left and right sides of the seat plate (1), and the upper end of each front support leg (6) is fixedly connected to the rear support leg (3) on the same side with a handrail (7).

9. The chair with a backrest according to claim 8, characterized in that, Each handrail (7) has a hanging hole (71) at the front end, and each rear support leg (3) has a hanging ring (8) fixedly connected to the outer side of the middle part.

10. The chair with a backrest according to claim 8, characterized in that, The lower ends of each front support leg (6) and each rear support leg (3) extend downward relative to the seat plate (1) by a certain distance.

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