SWING CHASSIS DEVICE

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serial no. 202420678320.1, filed on Apr. 3, 2024 and China application serial no. 202422597415.3 filed on Oct. 26, 2024. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The disclosure relates to the field of furniture, and in particular, to a swing chassis device.

Description of Related Art

As one of the most common pieces of furniture, chairs accompany us for a large amount of time during the day. Especially in offices, users spend most of their day sitting on chairs. However, prolonged sitting has led to increasing comfort and health-related issues. In terms of comfort, maintaining the same sitting posture for extended periods may cause people to feel more fatigued, experience neck and back discomfort, and numbness in the buttocks and legs. This discomfort may make it difficult for people to keep a pleasant mood and focus on work. Regarding health issues, maintaining the same posture for long periods of sitting may lead to compression of the lumbar spine and legs, thereby increasing the incidence of diseases such as lumbar spine disorders.

People have found that standing up after prolonged sitting may alleviate fatigue, and while seated, changing sitting postures may also effectively eliminate fatigue and reduce the harmful effects of prolonged sitting. Therefore, how to achieve greater flexibility in changing postures and make the transition more comfortable is the key to solving the aforementioned problems and achieving a more comfortable and healthy sitting experience.

SUMMARY

To solve the above technical problems, the disclosure provides a swing chassis device including a base, a first swing seat, and a second swing seat. The first swing seat is hinged onto the base through a first rotating shaft. The second swing seat is hinged onto the first swing seat through a second rotating shaft. The second swing seat swings back and forth. The first swing seat drives the second swing seat to swing left and right together. An elastic buffer member for providing buffering and a restoring force is disposed between the first swing seat and the base. The base is configured to be connected a chair leg air rod. Under the action of the first swing seat, the first swing seat swings left and right on the base, and the second swing seat swings back and forth on the first swing seat and swings left and right together with the first swing seat under the driving of the first swing seat. In this way, a chair seat connected to the second swing seat swings back and forth and left and right. Further, the flexibility of swinging is increased, a user can change his/her sitting posture flexibly and freely, and more sitting postures can be adapted, so the user is able to enjoy improved comfort. The elastic buffering member further enhances the comfort during swinging.

The technical solution of the disclosure is achieved in this way:

The disclosure provides a swing chassis device including a base, a first swing seat, and a second swing seat. The first swing seat is hinged onto the base through a first rotating shaft arranged in a front-rear direction. The second swing seat is hinged onto the first swing seat through a second rotating shaft arranged in a left-right direction. The first swing seat is configured to drive the second swing seat to swing left and right on the base, and the second swing seat is configured to be connected to a chair seat and swing back and forth on the first swing seat. An elastic buffer member is provided between the first swing seat and the base and is configured to provide swing buffering and a restoring force for the first swing seat.

The disclosure adopting the above technical solutions exhibits the following design starting point, concepts, and beneficial effects.

The base is configured to be connected a chair leg air rod. Under the action of the first swing seat, the first swing seat swings left and right on the base, and the second swing seat swings back and forth on the first swing seat and swings left and right together with the first swing seat under the driving of the first swing seat. In this way, a chair seat connected to the second swing seat swings back and forth and left and right. Further, the flexibility of swinging is increased, a user can change his/her sitting posture flexibly and freely, and more sitting postures can be adapted, so the user is able to enjoy improved comfort. The elastic buffering member further enhances the comfort during swinging.

An overall floating swing chassis (such as when springs are mounted at the four corners of the chassis) has less favorable dynamic capabilities. When there is a main beam fixed between two components, the components on both sides of the main beam are able to rotate relative to each other, and a spring is arranged between the two components, improved flexibility is provided, and the range of swing increases. Taking the function of swinging left and right as an example, in the swing chassis device, the first rotating shaft is used as the main beam between the base and the first swing seat. Elastic buffer members are disposed on both sides of the first rotating shaft, and the first swing seat rotates relative to the base through the first rotating shaft. That is, the first swing seats on both sides of the first rotating shaft swing relative to the base. Such an arrangement brings improved flexibility, the swing feeling is more obvious, and it can better meet the user's needs to switch sitting postures.

To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a schematic view one of a three-dimensional structure of a swing chassis device in Embodiment 1 of the disclosure.

FIG. 2 is a schematic view two of the three-dimensional structure of the swing chassis device in Embodiment 1 of the disclosure.

FIG. 3 is an exploded view of the swing chassis device in Embodiment 1 of the disclosure.

FIG. 4 is a schematic view of a three-dimensional structure of an inner portion of a base in Embodiment 1 of the disclosure.

FIG. 5 is a top view of the inner portion of the base in Embodiment 1 of the disclosure.

FIG. 6 is an exploded view of the swing chassis device in Embodiment 2 of the disclosure.

FIG. 7 is an exploded view of the swing chassis device in Embodiment 3 of the disclosure.

FIG. 8 is a top view of the inner portion of the base in Embodiment 3 of the disclosure.

FIG. 9 is a schematic view of the three-dimensional structure of the swing chassis device in Embodiment 4 of the disclosure.

FIG. 10 is an exploded view of the swing chassis device in Embodiment 4 of the disclosure.

FIG. 11 is a schematic view of a three-dimensional structure of a gear seat in Embodiment 4 of the disclosure.

FIG. 12 is a schematic view one of a three-dimensional structure of a back connecting member rotatably arranged on a first swing seat in Embodiment 5 of the disclosure.

FIG. 13 is a schematic view two of the three-dimensional structure of the back connecting member rotatably arranged on the first swing seat in Embodiment 5 of the disclosure.

FIG. 14 is a schematic view one of the three-dimensional structure of the swing chassis device in Embodiment 6 of the disclosure.

FIG. 15 is a schematic view two of the three-dimensional structure of the swing chassis

device in Embodiment 6 of the disclosure.

FIG. 16 is a schematic view one of a three-dimensional structure of the base in Embodiment 6 of the disclosure.

FIG. 17 is a schematic view two of the three-dimensional structure of the base in Embodiment 6 of the disclosure.

FIG. 18 is a schematic view of a three-dimensional structure of the first swing seat arranged on the base in Embodiment 6 of the disclosure.

FIG. 19 is a side view of the first swing seat in Embodiment 6 of the disclosure.

FIG. 20 is a schematic view of a three-dimensional structure of a gap provided between the first swing seat and a second swing seat in Embodiment 6 of the disclosure.

The reference numerals in each accompanying drawing are: base 1, first swing seat 2, second swing seat 3, first rotating shaft 4, second rotating shaft 5, spring 6, first mounting hole 7, first locking hole 8, first locking member 9, operating rod 10, push-pull torsion spring 11, bent portion 12, convex portion 13, end plate 14, rotation slot 15, second locking hole 16, second locking member 18, second mounting hole 19, buffer restoring torsion spring 20, gear seat 21, gear member 22, gear slot 23, first gear 231, second gear 232, back connecting member 24, slidable rotating member 25, slidable rotating slot 26, connecting seat 27, bottom shell 28, bottom plate 281, shaft seat 29, insertion hole 30, longitudinal protruding portion 31, lateral protruding portion 32, positioning groove 33, positioning portion 34, opening 35, limiting portion 36, main body portion 37, horizontal supporting portion 371, tilt supporting portion 372, first support protruding seat 38, and second support protruding seat 39.

DESCRIPTION OF THE EMBODIMENTS

The specific embodiments of disclosure are as follows:

Embodiment 1

As shown in FIG. 1 to FIG. 3, the disclosure provides a swing chassis device including a base 1, a first swing seat 2, and a second swing seat 3. The first swing seat 2 is hinged on the base 1 through a first rotating shaft 4 arranged in a front-rear direction, and the second swing seat 3 is hinged on the first swing seat 2 through a second rotating shaft 5 arranged in a left-right direction. The first swing seat 2 is configured to drive the second swing seat 3 to swing left and right on the base 1, and the second swing seat 3 is configured to be connected to a chair seat and swing back and forth on the first swing seat 2. An elastic buffer member is provided between the first swing seat 2 and the base 1 and is configured to provide swing buffering and a restoring force for the first swing seat 2.

The base 1 is configured to be connected a chair leg air rod. Under the action of the first swing seat 2, the first swing seat 2 may swing left and right on the base 1, and the second swing seat 3 may swing back and forth on the first swing seat 2 and may swing left and right together with the first swing seat 2 under the driving of the first swing seat 2. This allows the chair seat connected to the second swing seat 3 to swing back and forth and left and right, and flexibility of swing is thereby improved. In this way, a user can change his/her sitting posture flexibly and freely, and more sitting postures can be adapted, so the user is able to enjoy improved comfort. The elastic buffering member further enhances the comfort during swinging.

To be specific, as shown in FIG. 3 to FIG. 5, there are two first rotating shafts 4, which hinged to a front portion of the base 1 with a front portion of the first swing seat 2 and a rear portion of the base 1 with a rear portion of the first swing seat 2. The elastic buffering member is a spring 6, and there are four springs 6 in total. The springs 6 are vertically arranged and symmetrically distributed on both sides of the first rotating shafts 4, that is, there are two springs 6 on each side, and the springs 6 on both sides are symmetrically distributed to maintain the balance of force.

A first mounting hole 7 is formed on one of the first swing seat 2 and the base 1, and a first locking hole 8 is formed on the other one of the first swing seat 2 and the base 1. In this embodiment, two first mounting holes 7 are formed on the base 1, one first locking hole 8 is formed on the first swing seat 2, and the two first mounting holes 7 are coaxial and distributed in the left-right direction. A first locking member 9 disposed in the left-right direction is inserted in the first mounting hole 7. The first locking member 9 is selectively slidably disposed on the base 1, and selectively enters or leaves the first locking hole 8. The first locking member 9 is configured to selectively enter the first locking hole 8 to lock the first swing seat 2 and the base 1 or selectively leave the first locking hole 8 to unlock the first swing seat 2 and the base 1.

Movement of the first locking member 9 is controlled by an operating rod 10. The operating rod 10 is inserted in the base 1 in the left-right direction. The operating rod 10 is connected to the first locking member 9 through a push-pull torsion spring 11. When the operating rod 10 slides left and right on the base 1, the operating rod 10 drives the push-pull torsion spring 11 to move, which in turn drives the first locking member 9 to move. Furthermore, one of torsion spring arms of the push-pull torsion spring 11 is fixed onto the operating rod 10, and the other torsion spring arm of the push-pull torsion spring 11 is disposed on the first locking member 9. The push-pull torsion spring 11 is located inside the base 1 and the first swing seat 2. The push-pull torsion spring 11 has a bent portion 12, and the bent portion 12 is bent downward and abuts against the base 1. A convex portion 13 is disposed on the base 1, and the convex portion 13 is disposed on a movement path of the push-pull torsion spring 11. When the operating rod 10 drives the push-pull torsion spring 11 and thus drives the first locking member 9 to slide, the push-pull torsion spring 11 abutting against the base 1 passes through the convex portion 13. When the push-pull torsion spring 11 moves towards the first locking hole 8 and passes through the convex portion 13, the first locking member 9 enters the locking hole. The fitting between the push-pull torsion spring 11 and the convex portion 13 gives the user a tactile feedback of locking the first swing seat 2 and the base 1. Conversely, feedback can also be received when unlocking. In this way, through the combination of the elasticity of the push-pull torsion spring 11 and the convex portion 13, the unlocking and locking operations can be completed in one step, and the completion of unlocking and locking is fed back to the user, allowing the user to clearly understand the current state of the chassis device.

In the above solution, the pull-out operating rod 10 is convenient for the user to operate, so as to drive the first locking member 9 to slide. The first locking member 9 may be slidably disposed on the first swing seat 2 and the base 1, and the first locking member 9 is inserted in the first mounting hole 7 and slidably fitted to the first mounting hole 7. Further, when the first locking member 9 slides towards the first locking hole 8 and enters the first locking hole 8, it can lock the first swing seat 2 with the base 1, so the first swing seat 2 is prevented from moving on the base 1. Similarly, when the first locking member 9 leaves the first locking hole 8, the first swing seat 2 and the base 1 are unlocked, so the first swing seat 2 is able to move on the base 1.

The second swing seat 3 includes two end plates 14 located on the left and right sides, the two end plates protrude downward and are positioned on both sides of the first swing seat 2. The second swing seat 3, the first swing seat 2, and the base 1 are arranged from top to bottom in sequence. The second rotating shaft 5 is disposed in the middle of the end plates 14 and passes through the first swing seat 2 and the two end plates 14. A rotation slot 15 is formed on one of the end plates 14 beside the second rotating shaft 5, and a second locking hole 16 is correspondingly formed on the other end plate 14. Relative rotation between the second swing seat 3 and the first swing seat 2 is unlocked or locked by a second locking member 18. A second mounting hole 19 is provided on the first swing seat 2, and the second locking member 18 is inserted in the rotation slot 15 and the second mounting hole 19. The second locking member 18 is selectively slidably disposed on the first swing seat 2 and the second swing seat 3 in the left-right direction. The second locking member 18 is configured to selectively enter the second locking hole 16 to lock the first swing seat 2 and the second swing seat 3 or selectively leave the second locking hole 16 to unlock the second swing seat 3 and the first swing seat 2. When the second locking member 18 leaves the second locking hole 16 and the second swing seat 3 rotates relative to the first swing seat 2, the second locking member 18 moves in the rotation slot 15.

In an up-down direction, there are gaps between both left and right ends of the first swing seat 2 and the base 1, and these gaps allow clearance for the first swing seat 2 to swing left and right on the base 1.

Embodiment 2

The difference between this embodiment and Embodiment 1 lies only in the number of springs 6, specifically as follows:

As shown in FIG. 6 and FIG. 7, in this embodiment, there are two springs 6 in total, and the two springs 6 are vertically and symmetrically distributed on both sides of the first rotating shaft 4.

Embodiment 3

The difference between this embodiment and Embodiment 1 lies only in the elastic buffering member and its arrangement method, specifically as follows:

As shown in FIG. 8, the elastic buffering member is a buffering restoring torsion spring 20 sleeved on the first rotating shaft 4. The number of buffering restoring torsion springs 20 is at least an even number. In this embodiment, considering the costs, two buffering restoring torsion springs 20 are selected. The two buffering restoring torsion springs 20 are sleeved on the two first rotating shafts 4. The two torsion spring arms of the buffering restoring torsion spring 20 act on the base 1 and the first swing seat 2 and face opposite directions to maintain the force balance on both left and right sides of the first rotating shaft 4.

When more buffering restoring torsion springs 20 are selected, in order to maintain the force balance on both left and right sides of the first rotating shaft 4, and to ensure that the number of torsion spring arms on both sides of the first rotating shaft 4 is the same, the number of buffering restoring torsion springs 20 with torsion spring arms facing the left side is equal to the number of buffering restoring torsion springs 20 with torsion spring arms facing the right side.

Embodiment 4

The difference between this embodiment and Embodiment 1 lies in the locking and unlocking operation method between the first swing seat 2 and the base 1, specifically as follows:

As shown in FIG. 9 to FIG. 11, this solution drives the movement of the first locking member 9 through the rotatable operating rod 10 to achieve locking and unlocking of the first swing seat 2. The operating rod 10 is provided on the first swing seat 2 and is selectively rotatable. The operating rod 10 is arranged in the left-right direction, the first locking member 9 is arranged in the front-rear direction. The operating rod 10 is connected to the first locking member 9 and is configured so that the operating rod 10 rotates to drive the first locking member 9 to leave or enter the first locking hole 8. There are two first locking members 9 in total, and the two first locking members 9 are symmetrically arranged on both sides of the first rotating shaft 4. Since the first locking member 9 in this solution is slidably arranged in the front-back direction, when both sides of the first swing seat 2 and the base 1 are acted upon by the first locking members 9, balance and stability when locked is maintained.

The push-pull torsion spring 11 is sleeved on the operating rod 10. One of torsion spring arms of the push-pull torsion spring 11 is fixed onto the operating rod 10, and the other torsion spring arm of the push-pull torsion spring 11 is disposed on the first locking member 9. The push-pull torsion spring 11 is configured so that the operating rod 10 drives the first locking member 9 to move via the push-pull torsion spring 11. The push-pull torsion spring 11 may convert the rotation of the operating rod 10 into a sliding driving force for the first locking member 9. Further, a gear seat 21 is provided on the first swing seat 1. The operating rod 10 is provided with a synchronously rotating gear member 22. A gear slot 23 is provided on the gear seat 21, and the gear member 22 is inserted into the gear slot 23. The gear slot 23 has a first gear 231 and a second gear 232. A convex portion 13 protruding toward the gear slot 23 is provided between the first gear 231 and the second gear 232. The gear member switches between the first gear 231 and the second gear 232 by crossing the convex portion 13. The convex portion 13 provides inertia during gear switching to enhance the operational feel. The user may sense the completion of gear switching, and after the gear switching is completed, the gear member 22 remains in the current gear position.

Embodiment 5

The difference between this embodiment and Embodiment 4 lies in the arrangement of a back connecting member 24 to achieve seat-back linkage, specifically as follows:

As shown in FIG. 12 and FIG. 13, this solution allows a chair back and the chair seat to swing left and right together: A back connecting member 24 is provided on the first swing seat 2 and is configured to be connected to the chair back and swing with the swing of the first swing seat 2. A front end of the back connecting member 24 is rotatably connected onto the first swing seat 2. The back connecting member 24 and the second swing seat 3 are linked by a linkage structure configured to drive the second swing seat 3 to swing back and forth when the back connecting member 24 rotates on the first swing seat 2. The back connecting member 24 is linked with the second swing seat 3, so that when the chair back reclines, the second swing seat 3 may also swing backward and tilt up at the front, and overall comfort is thereby enhanced. The back-and-forth swinging of the second swing seat 3 may be directly applied to the seat-back linkage when the chair back reclines.

Further, the linkage structure includes a slidable rotating member 25 and a slidable rotating slot 26. A connecting seat 27 is extended obliquely downward from the rear of the second swing seat 3. The connecting seat 27 is connected to the slidable rotating member 25 arranged in the left-right direction. The slidable rotating slot 26 is provided on the back connecting member 24, and the slidable rotating member 25 is inserted into the slidable rotating slot 26. When the back connecting member 24 rotates on the first swing seat 2, the slidable rotating member 25 and the slidable rotating slot 26 move and rotate relative to each other and drive the second swing seat 3 to swing back and forth. This solution achieves the linkage between the back connecting member 24 and the second swing seat 3, so seat-back linkage is achieved with a simpler structure.

Embodiment 6

The difference between this embodiment and Embodiment 2 lies only in the removal of the locking structure for the left-right swinging direction. That is, the first locking hole 8, the first locking member 9, the operating rod 10, and the push-pull torsion spring 11 are removed, allowing the first swing seat 2 to swing freely. Meanwhile, the structures of the base 1 and the first swing seat 2 are modified, specifically as follows:

As shown in FIG. 14 to FIG. 20, the base 1 includes a bottom shell 28 and a shaft seat 29. The bottom shell 28 is an open-top shell body and includes a bottom plate 281. The shaft seat 29 is fixedly disposed in the bottom shell 28 and located above the bottom plate 281. The shaft seat 29 may be fixed to the bottom shell 28 by welding. One end of the first rotating shaft 4 is disposed on the shaft seat 29 and remains stationary relative to the shaft seat 29, while the other end of the first rotating shaft 4 protrudes outward from the bottom shell 28 and is rotatably connected to the first swing seat 2. The rotation limit between the first rotating shaft 4 and the shaft seat 29 is achieved by turning and milling the end portion of the first rotating shaft 4 to form an irregular cross-section and creating a corresponding irregular hole on the shaft seat 29. There are two first rotating shafts 4, protruding from the front and rear ends of the base 1. The two first rotating shafts 4 are coaxial and spaced apart. At this interval, an insertion hole 30 for inserting an air rod is formed on the base 1, specifically extending from the bottom plate 281 through the shaft seat 29. The first rotating shaft 4 is not a single rotating shaft penetrating the base 1. The gap between the two shafts naturally avoids the air rod, preventing the chassis from being forced to increase in thickness due to conflicts between the air rod and the first rotating shaft 4 positions, making the overall structure thinner. A distance between a seat surface and a bottom surface of the chassis is reduced, and a lowest height of the seat surface is thus lowered, making it more comfortable. If the lowest height of the seat surface is excessively high, the front end of the chair seat may easily hit the thigh when the chair seat tilts backward, thereby reducing comfort.

As shown in FIG. 15 to FIG. 17, a bottom portion of the base 1 has a protruding portion protruding upward or downward, specifically disposed on the bottom plate 281 of the bottom shell 28. In this embodiment, the protruding portion protrudes downward on the bottom plate 281. To be specific, the protruding portion includes a longitudinal protruding portion 31 and a lateral protruding portion 32. The longitudinal protruding portion 31 is configured to provide support when the first swing seat 2 swings left and right, and the lateral protruding portion 32 is configured to provide support when the second swing seat 3 swings back and forth. The protruding portion is arranged to increase the strength of the base 1, and as the base 1 serves as the main support of the chassis for connecting the air rod, increasing its strength can ensure the structural strength and support stability of the chassis. Since this chassis has a swinging function, the stress conditions during actual use are different from a conventional chassis, and the base 1 consequently is subjected to forces from multiple directions. Therefore, higher strength requirements are needed, especially for forces in different directions. Although the first swing seat 2 only swings left and right, the chair seat connected to the second swing seat 3 produces movements in more directions when both the first swing seat 2 and the second swing seat 3 swing freely. Simply setting up reinforcing ribs cannot meet the requirements. The longitudinal protruding portion 31 and the lateral protruding portion 32 are arranged for the two swinging directions of this swinging chassis, decomposing the forces generated when the chair seat moves in other directions into left-right and front-back forces for support, thus providing simple and low-cost support for the complex movements of the swing chassis.

The longitudinal protruding portion 31 is arranged in the front-rear direction, and the lateral protruding portion 32 is arranged in the left-right direction. The longitudinal protruding portion 31 and the lateral protruding portion 32 intersect to form a cross shape. The intersection of the longitudinal protruding portion 31 and the lateral protruding portion 32 coincides with a center position of the bottom plate 281. The insertion hole 30 is opened at the center position of the bottom plate 281. An intersection point of projections of axes of the first rotating shaft 4 and the second rotating shaft 5 on the bottom plate 281 falls within a coverage of the insertion hole 30. That is, the intersection point of the projections of the axes of the first rotating shaft 4 and second rotating shaft 5 is also located at the middle position of the protruding portion, to achieve a more balanced effect of force stability.

The longitudinal protruding portion 31 and the lateral protruding portion 32 achieve increased support strength for swinging in different directions through their different extension arrangement directions. Meanwhile, the protruding portion as a whole forms a cross shape, which simplifies the structure and reduces manufacturing difficulty and costs. The insertion hole 30 is located at the center of the bottom plate 281, which is also at the middle of the protruding portion. When the base 1 transmits force to the air rod or receives a reaction force from the air rod, the protruding portion can also serve to increase the strength of the base 1, so structural strength and service life are ensured.

Further, the protruding portion protrudes downward from the bottom plate 281, and a positioning groove 33 is formed on an upper surface of the bottom plate 281 at a position of the protruding portion. The positioning groove 33 is also cross-shaped. The lower end of the shaft seat 29 is provided with four downwardly protruding positioning portions 34 disposed in the positioning grooves 33 in four directions. Only a single spring 6 is disposed on one side of the first rotating shaft 4, and the spring 6 is vertically arranged in the positioning groove 33 formed by the lateral protruding portion 32. The bottom plate 281 is stamped downward to form the protruding portion, which is more cost-effective than mold-making. Further, this means that except for the insertion hole 30 and the protruding portion, other parts of the bottom of the base 1 are relatively recessed upward, so material costs are saved. With the function of the positioning groove 33, the installation and connection of the shaft seat 29 and the spring 6 are more convenient.

Widths of the longitudinal protruding portion 31 and the lateral protruding portion 32 range from 30 mm to 40 mm. The widths of the longitudinal protruding portion 31 and the lateral protruding portion 32 are both relatively wide, while a length and a width of the bottom plate 281 are generally between 80 mm to 100 mm. The protruding portion occupies a large proportion on the bottom plate 281, resulting in a larger overall force-bearing area of the protruding portion, so stress concentration problems are prevented and the strength-increasing effect of the protruding portion is improved. In this embodiment, the width of the longitudinal protruding portion 31 is 32 mm, the width of the lateral protruding portion 32 is 37 mm, the length of the bottom plate 281 in the front-back direction is 85 mm, and the length of the bottom plate 281 in the left-right direction is 98 mm.

Further, a lower end of each spring 6 abuts against the base 1, and an upper end of each spring 6 abuts against the first swing seat 2. A bottom portion of the base 1 is provided with an opening 35, and the opening 35 is coaxial with the spring 6. The spring 6 is disposed at the opening 35 and is located above the opening 35. An anti-detachment rod (not shown) may be inserted into the spring 6 through the opening 35 to prevent the upper and lower ends of the spring 6 from detaching. The base 1 is formed with an upwardly protruding limiting portion 36 around the opening 34, and the limiting portion 36 protrudes upwardly to enter the spring 6. The limit portion 36 is formed by stamping simultaneously with the opening 35, and the opening 35 is located on the protruding portion at the bottom portion of the base 1. The opening 35 is disposed at the bottom of the base 1, and the part around the edge of the opening 35 is stamped upward and enters the spring 6, providing positioning for the mounting of the spring 6 and also serving as a limit during use to prevent the spring 6 from detaching.

In addition, as shown in FIG. 18 to FIG. 20, the first swing seat 2 includes a main body portion 37 and a support seat protruding from an upper surface of the main body portion 37. A gap is provided between the second swing seat 3 and the main body portion 37 for accommodating the forward and backward tilt of the second swing seat 3. To be specific, the main body portion 37 includes a horizontal supporting portion 371 and a tilt supporting portion 372. The support seat includes a first support protruding seat 38 and a second support protruding seat 39. The horizontal supporting portion 371 is arranged horizontally, and the tilt supporting portion 372 is arranged at a rear end of the horizontal supporting portion 371 in a downwardly inclined manner. The first support protruding seat 38 is disposed on the horizontal supporting portion 371 and protrudes from an upper surface of the horizontal supporting portion 371. The second support protruding seat 39 is disposed on the tilt supporting portion 372 and protrudes from an upper surface of the tilt supporting portion 372. When the second swing seat 3 is horizontal, it abuts against the first support protruding seat 38. When the second swing seat 3 tilts backward, it abuts against the second support protruding seat 39. The first support protruding seat 38 is located at a front end of the horizontal supporting portion 371, supporting and limiting the second swing seat 3 underneath when it is horizontal. The second support protruding seat 39 is located on the inclined tilt supporting portion 372 and is also in an inclined state. When the second swing seat 3 tilts backward to the maximum, the second support protruding seat 39 supports and limits it underneath.

Under the premise of retaining the front and rear tilting, the left and right tilting effect is added to the swing chassis device, and the required cost is low. Only one swing seat and the corresponding internal parts are added to the original basic chassis. There is no need to make major changes to other components of the chassis, and there is no need to add extended parts on the left and right sides to mount the spring 6. The same effect is achieved through less changes, and both mold opening costs and material costs are reduced.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.