Constant force structure for reducing distance of elastic piece

Abstract

The invention discloses a constant force structure capable of reducing the distance of an elastic part, an arm main body, a swivel seat, a supporting plate and an adjusting seat are sequentially hinged to form a parallel four-bar linkage structure, an elastic assembly comprises a first connecting piece, a second connecting piece and an elastic element capable of elastically stretching out and drawing back, and the lower end of the first connecting piece is hinged to a connecting hole of the supporting plate; the upper end of the first connecting piece is hinged to the rear end of the second connecting piece through a sixth horizontal rotating shaft, the sixth horizontal rotating shaft can be inserted into a long-strip-shaped arm sliding groove in the side wall of the front section of the arm body in a sliding mode, the front end of the second connecting piece is hinged to an arm positioning hole in the side wall of the front section of the arm body, and the front end of the elastic element is hinged to the middle of the first connecting piece. By means of the display height adjusting device, the fine adjusting distance of stretching lengthening or shortening of the elastic element in the arm can be effectively reduced, the spring constant force output state can be better achieved, and the stability of a display after height adjustment is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a display support, in particular to a constant force structure for reducing the distance of elastic members. BACKGROUND

[0002] Displays are used in many occasions, such as at home, in the office, in public places, etc., and are often installed on a display support.

[0003] In the conventional display height and horizontal angle adjustment, plastic spacers are clamped between the arm body to achieve the adjustment by friction. The plastic spacers are easily damaged in the long-term use, resulting in poor stability of the display height and horizontal angle adjustment after long-term use, and it is difficult to maintain stable support and state for a long time. Moreover, the adjustment often requires loosening and tightening screws, which is tedious and is affected by the friction value. The display bearing range is small, and the assembly is tedious.

[0004] Currently, some display supports are provided with elastic components inside, and the elastic force of the elastic components is used to support the display. In the existing structure for supporting the display by using the elastic components, the springs of the elastic components are directly fixed on the rotating head seat. When the arm moves up and down, the springs in the arm will have different pull-up distances at different positions, so that the constant force state cannot be optimized, and the display will appear to drop up or pop down after being loaded. SUMMARY

[0005] In order to overcome the above defects, the present application provides a constant force structure for reducing the distance of elastic members, which can better achieve the spring constant force output state during the arm lifting process.

[0006] The technical solution adopted by this invention to solve its technical problem is as follows: a constant force structure for reducing the distance of elastic elements, comprising an adjusting seat, a rotating head seat, an arm body, a support plate, and an elastic component. The front and rear ends of the arm body are respectively rotatable around a first horizontal axis and a second horizontal axis and are mounted on the upper ends of the rotating head seat and the adjusting seat. The front and rear ends of the support plate are respectively rotatable around a third horizontal axis and a fourth horizontal axis and are mounted on the lower ends of the rotating head seat and the adjusting seat. The adjusting seat, the arm body, the rotating head seat, and the support plate together form a parallel four-bar linkage structure. The front sidewall of the support plate is provided with a support plate connecting hole and a support plate arc-shaped hole, and the arc-shaped hole and the support plate connecting hole are concentrically arranged. The front sidewall of the arm body is provided with an arm positioning... The elastic component includes a first connecting piece, a second connecting piece, and an elastic element capable of elastic extension and retraction. The lower end of the first connecting piece is hinged to the support plate connecting hole via a fifth horizontal pivot, and the upper end of the first connecting piece is hinged to the rear end of the second connecting piece via a sixth horizontal pivot. The sixth horizontal pivot is slidably inserted into the elongated arm slot on the front side wall of the arm body. The front end of the second connecting piece is hinged to the arm positioning hole on the front side wall of the arm body via a seventh horizontal pivot. The front end of the elastic element is hinged to the middle of the first connecting piece via an eighth horizontal pivot, and the rear end of the elastic element is mounted on the second horizontal pivot, an adjustment seat, or the inner side wall of the rear end of the arm body.

[0007] As a further improvement of the present invention, a cavity structure is formed on the inner side of the arm body, and the support plate and elastic component are both accommodated in the cavity structure of the arm body. The front end and rear end of the arm body are respectively formed with clearance notches. The rotating head seat and the adjusting seat can be rotatably inserted into the cavity structure of the arm body through the clearance notches. The arm positioning hole and the arm sliding groove are provided on the inner sidewalls of the left and right sides of the arm body.

[0008] As a further improvement of the present invention, the arm groove is an inverted U-shaped open groove with an open bottom or a closed elongated groove.

[0009] As a further improvement of the present invention, the elastic element includes a spring, an adjusting bolt, and a connecting block. A hook is formed at the front end of the spring, and the hook is sleeved on the outside of the eighth horizontal rotating shaft. The connecting block is fixedly installed on the rear end of the spring. The stud of the adjusting bolt is movably screwed to the connecting block. The stud of the adjusting bolt can be extended and retracted to be accommodated in the inner ring of the spring. A bolt through hole extending radially is provided on the second horizontal rotating shaft. The adjusting bolt passes through the bolt through hole, and the head of the adjusting bolt stops at the rear side of the outer circumference of the second horizontal rotating shaft. An avoidance adjustment hole is formed at the rear end of the arm body, which is directly opposite the head of the adjusting bolt. Hardware tools can be inserted into the arm body through the avoidance adjustment hole and rotate the adjusting bolt. Rotating the adjusting bolt can change the initial elastic force value of the elastic element.

[0010] As a further improvement of the present application, the second horizontal rotating shaft is provided with a flat-bottomed groove with a meat-removing structure on the rear side wall in the circumferential direction, the head of the adjusting bolt is accommodated in the flat-bottomed groove, and the head of the adjusting bolt is tightly abutted on the flat bottom of the flat-bottomed groove.

[0011] As a further improvement of the present application, the upper end of the adjusting seat is formed in a U-shaped structure, the two side walls of the U-shaped structure of the adjusting seat are respectively provided with first horizontal hinge holes, the rear end of the arm body is sleeved outside the U-shaped structure of the upper end of the adjusting seat, the two side walls of the rear end of the arm body are respectively provided with second horizontal hinge holes, the second horizontal rotating shaft includes an adjusting bolt limiting shaft and connecting screws, the bolt hole is located at the middle part of the adjusting bolt limiting shaft, the two ends of the adjusting bolt limiting shaft are respectively inserted into the first horizontal hinge hole and the second horizontal hinge hole, and the two connecting screws are respectively threaded through the second horizontal hinge hole and the first horizontal hinge hole and are screwed with the two ends of the adjusting bolt limiting shaft, and the heads of the two connecting screws are respectively tightly abutted on the left and right side surfaces of the rear end of the arm body.

[0012] As a further improvement of the present application, the bottom surface of the U-shaped structure on the adjusting seat is a sharp bottom structure with a middle height higher than the front and rear heights, and the screw rod part and the head part of the adjusting bolt are respectively stopped on the front and rear sides of the bottom surface of the U-shaped structure on the adjusting seat.

[0013] As a further improvement of the present application, the first connecting piece, the second connecting piece and the supporting plate are all U-shaped structures, the supporting plate is sleeved outside the lower end of the first connecting piece, the rear end of the second connecting piece is sleeved outside the upper end of the first connecting piece, the elastic element is accommodated inside the U-shaped structure of the supporting plate, and the front end of the elastic element extends into the inside of the first connecting piece, the two side walls of the rotating head seat are respectively formed with meat-removing thinned step surfaces, and the front end of the second connecting piece and the front end of the supporting plate are both sleeved outside the thinned step surfaces of the rotating head seat.

[0014] As a further improvement of the present application, the arm body is further provided with an adjusting bolt guide piece, the adjusting bolt guide piece is formed with an open slot, the adjusting bolt passes through the open slot, and the bottom surface of the open slot is stopped on the upper side of the adjusting bolt.

[0015] The beneficial effects of the present application are that the tension point of the elastic element is through the first connecting piece and the second connecting piece, and the force value is applied to the supporting plate; when the arm is raised and lowered, the first connecting piece and the second connecting piece can effectively reduce the fine adjustment distance of the elastic element in the arm, so that the spring constant output state is better achieved, and the stability after the height of the display is adjusted is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a perspective view of the present application;

[0017] Figure 2 isometric view of the elastic assembly of the present application;

[0018] Figure 3 front view of the elastic assembly of the present application;

[0019] Figure 4 top view of the elastic assembly of the present application;

[0020] Figure 5 isometric view of Figure 4 sectional view along A-A direction;

[0021] Figure 6 isometric view of the first connecting piece of the present application;

[0022] Figure 7 isometric view of the second connecting piece of the present application;

[0023] Figure 8 front view of the support plate of the present application;

[0024] Figure 9 front view of the right arm cover of the present application;

[0025] Figure 10 isometric view of the swivel head base of the present application;

[0026] Figure 11 isometric view of the adjusting base of the present application;

[0027] Figure 12 isometric view of the adjusting bolt limiting shaft of the present application;

[0028] Figure 13 front view of the present application in a downward position;

[0029] Figure 14 top view of the present application in a downward position;

[0030] Figure 15 isometric view of Figure 14 sectional view along B-B direction;

[0031] Figure 16 isometric view of Figure 14 sectional view along C-C direction;

[0032] Figure 17 front view of the present application in a top position;

[0033] Figure 18 top view of the present application in a top position;

[0034] Figure 19 isometric view of Figure 18 sectional view along D-D direction;

[0035] Figure 20The front view of the application in the level state. DETAILED DESCRIPTION

[0036] The embodiment is a constant force structure for reducing the distance of elastic member, which comprises an adjusting seat 1, a rotating head seat 2, an arm body 3, a support plate 4 and an elastic assembly 5. The front and rear ends of the arm body 3 are respectively rotatably installed on the upper ends of the rotating head seat 2 and the adjusting seat 1 about first and second horizontal rotating shafts 6 and 7. The front and rear ends of the support plate 4 are respectively rotatably installed on the lower ends of the rotating head seat 2 and the adjusting seat 1 about third and fourth horizontal rotating shafts 7 and 8. The adjusting seat 1, the arm body 3, the rotating head seat 2 and the support plate 4 jointly form a parallel four-bar linkage structure. The support plate 4 is provided with a support plate connecting hole 9 and a support plate arc-shaped hole 10 on the side wall of the front section. The support plate arc-shaped hole 10 is concentrically arranged with the support plate connecting hole 9. The arm body 3 is provided with an arm positioning hole 11 and a long strip-shaped arm sliding groove 12 on the side wall of the front section. The elastic assembly 5 comprises a first connecting piece 13, a second connecting piece 14 and an elastic force element capable of elastic expansion and contraction. The lower end of the first connecting piece 13 is hingedly connected with the support plate connecting hole 9 through a fifth horizontal rotating shaft 15. The upper end of the first connecting piece 13 is hingedly connected with the rear end of the second connecting piece 14 through a sixth horizontal rotating shaft 16. The sixth horizontal rotating shaft 16 is slidably inserted into the long strip-shaped arm sliding groove 12 on the side wall of the front section of the arm body 3. The front end of the second connecting piece 14 is hingedly connected with the arm positioning hole 11 on the side wall of the front section of the arm body 3 through a seventh horizontal rotating shaft 17. The front end of the elastic force element is hingedly connected with the middle of the first connecting piece 13 through an eighth horizontal rotating shaft 18. The rear end of the elastic force element is installed on the inner side wall of the second horizontal rotating shaft or the rear end of the adjusting seat 1 or the arm body 3.

[0037] When adjusting the height of the display, only the arm body 3 needs to be rotated to make the rotating head seat 2 produce lifting movement without rotation, so that the display is only adjusted in height and the pitch angle of the display is not affected. When the arm is lifted and rotated, the arm synchronously rotates the first connecting piece 13 and the second connecting piece 14. The second connecting piece 14 rotates with the seventh horizontal rotating shaft 17 as the center. The first connecting piece 13 rotates with the fifth horizontal rotating shaft 15 as the center. Meanwhile, the first connecting piece 13 synchronously swings with the support plate 4. The second connecting piece 14 synchronously swings with the arm body 3. The eighth horizontal rotating shaft 18 on the first connecting piece 13 makes a small distance movement in the support plate arc-shaped hole 10.

[0038] The front end of the elastic element is synchronous with the eighth horizontal rotating shaft 18 and moves in the support plate arc-shaped hole 10 of the support plate 4 in the up and down lifting movement of the arm. The elastic element is driven to produce slight stretching and contraction movement, the first connecting piece 13 drives the elastic element to change the tension value, and the tension point of the elastic element acts on the support plate 4 through the first connecting piece 13 and the second connecting piece 14; the above structure can reduce the stretching and contraction adjustment distance of the elastic element in the up and down swing adjustment process of the arm body 3, so that the constant force output state is more easily achieved.

[0039] Further, the rotating head seat 2 can be suspended to display the stable up and down movement hovering state under the constant force of the arm body 3, and the up and down phenomenon is avoided.

[0040] The inside of the arm body 3 is formed as a cavity structure, the support plate 4 and the elastic assembly 5 are accommodated in the cavity structure of the arm body 3, the front end and the rear end of the arm body 3 are respectively formed with avoiding notches, the rotating head seat 2 and the adjusting seat 1 are respectively inserted into the cavity structure of the arm body 3 through the avoiding notches, and the arm positioning hole 11 and the arm sliding groove 12 are arranged on the inner side walls of the left and right sides of the arm body 3.

[0041] The above structure hides each hinged joint part of the parallelogram in the cavity structure of the arm body 3, which is beneficial to improve the overall appearance and protect the hinged joint part. The arm body 3 can be designed as a butt joint structure of the left arm cover 31 with a U-shaped cross section and the right arm cover 32 with a U-shaped cross section, and the two together form a hollow cavity structure. The arm body 3 is designed as a plug-in splicing structure, which is convenient for assembling the elastic assembly 5 and the support plate 4. The left arm cover and the right arm cover are respectively provided with a convex column 33 on the bottom surface of the front end, a T-shaped through hole 34 with an inner diameter of the convex column larger in the opening direction of the U-shaped structure than in the direction away from the U-shaped structure is formed in the inside of the convex column, and a bushing 35 is installed in one end of the convex column with a larger inner diameter.

[0042] The arm sliding groove 12 is a downward U-shaped opening sliding groove or a closed long groove type sliding groove. When the arm body 3 swings up and down, the sixth horizontal rotating shaft 16 slides up and down along the downward U-shaped opening sliding groove or the closed long groove type sliding groove.

[0043] The elastic element comprises a spring 19, an adjusting bolt 20 and a connecting block 21, the front end of the spring 19 is formed with a hook 22, the hook 22 is sleeved outside the eighth horizontal rotating shaft 18, the connecting block 21 is fixedly installed on the rear end of the spring 19, the threaded shank of the adjusting bolt 20 is movably screwed with the connecting block 21, the threaded shank of the adjusting bolt 20 can be telescopically accommodated in the inner ring of the spring 19, the second horizontal rotating shaft is provided with a threaded hole 23 extending in the radial direction thereof, the adjusting bolt 20 is arranged in the threaded hole 23, and the head of the adjusting bolt 20 is stopped at the rear side of the outer side surface of the second horizontal rotating shaft, the rear end of the arm body 3 is formed with an avoiding adjusting hole 24 opposite to the head of the adjusting bolt 20, a tool can be inserted into the arm body 3 through the avoiding adjusting hole 24 and rotate the adjusting bolt 20, and rotating the adjusting bolt 20 can change the initial elastic value of the elastic element. Rotating the adjusting bolt 20 can change the compression amount of the spring 19 in the initial state, so as to realize the adjustment of the elastic value output by the elastic element in the initial state, so that it can adapt to the stable support of the display with different weights.

[0044] The rear side wall of the second horizontal rotating shaft in the circumferential direction is provided with a flat-bottomed groove 25 with a meat-removing structure, the head of the adjusting bolt 20 is accommodated in the flat-bottomed groove 25, and the head of the adjusting bolt 20 is tightly abutted on the flat bottom of the flat-bottomed groove 25. In this way, the head of the adjusting bolt 20 and the rear side surface of the adjusting bolt limiting shaft 28 can be smoothly contacted.

[0045] The upper end of the adjusting seat 1 is formed in a U-shaped structure, the two side walls of the U-shaped structure of the adjusting seat 1 are respectively provided with first horizontal hinge holes 26, the rear end of the arm body 3 is sleeved outside the U-shaped structure of the upper end of the adjusting seat 1, the two side walls of the rear end of the arm body 3 are respectively provided with second horizontal hinge holes 27, the second horizontal rotating shaft comprises an adjusting bolt limiting shaft 28 and connecting screws 29, the threaded hole 23 is located at the middle part of the adjusting bolt limiting shaft 28, the two ends of the adjusting bolt limiting shaft 28 are respectively inserted into the first horizontal hinge hole 26 and the second horizontal hinge hole 27, and the two connecting screws 29 are respectively threaded through the second horizontal hinge hole 27 and the first horizontal hinge hole 26 and are screwed with the two ends of the adjusting bolt limiting shaft 28, and the heads of the two connecting screws 29 are respectively tightly abutted on the left and right side surfaces of the rear end of the arm body 3.

[0046] The adjusting bolt 20 is accommodated in the opening of the U-shaped structure of the upper end of the adjusting seat 1, the adjusting bolt limiting shaft 28 is used for limiting the position of the adjusting bolt 20 on the one hand, and is screwed with the connecting screws 29 on the other hand to form an integrated structure, which can be used as the second horizontal rotating shaft, and the friction pad is preferably arranged between the arm body 3 and the adjusting seat 1, the arm body 3 and the adjusting seat 1 form a larger friction force through the locking of the connecting screws 29, which assists the positioning of the angle of the arm body 3, and can prevent the arm body 3 from instantaneously and rapidly swinging when the adjusting bolt 20 is rotated.

[0047] The bottom surface of the U-shaped structure on the adjusting seat 1 is a pointed bottom structure with a middle height higher than the height of the front and rear sides, and the screw rod part and head part of the adjusting bolt 20 are respectively stopped on the front and rear sides of the bottom surface of the U-shaped structure on the adjusting seat 1. By setting the front and rear inclined surfaces on the bottom surface of the U-shaped structure of the adjusting seat 1 with the second horizontal pivot as a boundary, the swing of the adjusting bolt 20 with the arm body 3 and the range of the swing angle are limited.

[0048] The first connecting piece 13, the second connecting piece 14 and the support plate 4 are all U-shaped structures, the support plate 4 is sleeved on the outer side of the lower end of the first connecting piece 13, the rear end of the second connecting piece 14 is sleeved on the outer side of the upper end of the first connecting piece 13, the elastic element is contained in the inside of the U-shaped structure of the support plate 4, and the front end of the elastic element extends into the inside of the first connecting piece 13, the stepped surface 30 is formed on the axial two side walls of the rotating head seat 2, the front end of the second connecting piece 14 and the front end of the support plate 4 are both sleeved on the outside of the thinned stepped surface 30 of the rotating head seat 2.

[0049] The above structure makes the arm form a left-right symmetrical structure, so that the fifth horizontal pivot 15, the sixth horizontal pivot 16, the seventh horizontal pivot 17 and the eighth horizontal pivot 18 are both supported at both ends, the tension is centered, the second connecting piece 14 moves while taking the stepped surface 30 of the rotating head seat 2 as a guide surface, and the movement of the arm is stable.

[0050] The arm body 3 is also provided with an adjusting bolt guide piece 36, the adjusting bolt guide piece 36 is formed with an open slot, the adjusting bolt 20 passes through the open slot, and the bottom surface of the open slot is stopped on the upper surface of the adjusting bolt 20. The open slot on the adjusting bolt guide piece 36 can guide, limit and support the adjusting bolt 20, and prevent the spring 19 from being radially deformed to cause deflection.

Claims

1. A constant force structure for reducing the distance between elastic elements, comprising an adjusting seat (1), a rotating head seat (2), an arm body (3), a support plate (4), and an elastic component (5), wherein the front and rear ends of the arm body are respectively rotatable around a first horizontal rotating axis (6) and a second horizontal rotating axis and are mounted on the upper ends of the rotating head seat and the adjusting seat, and the front and rear ends of the support plate are respectively rotatable around a third horizontal rotating axis (7) and a fourth horizontal rotating axis (8) and are mounted on the lower ends of the rotating head seat and the adjusting seat, wherein the adjusting seat, the arm body, the rotating head seat, and the support plate together form a parallel four-bar linkage structure, characterized in that: The front side wall of the support plate is provided with a support plate connection hole (9) and a support plate arc hole (10), and the support plate arc hole and the support plate connection hole are concentrically arranged. The front side wall of the arm body is provided with an arm positioning hole (11) and a long arm slide groove (12). The elastic component includes a first connecting piece (13), a second connecting piece (14) and an elastic element that can elastically extend and retract. The lower end of the first connecting piece is hinged to the support plate connection hole through a fifth horizontal pivot (15). The upper end of the first connecting piece is hinged to the rear end of the second connecting piece through a sixth horizontal pivot (16). The sixth horizontal pivot can be slidably inserted into the long arm slide groove on the front side wall of the arm body. The front end of the second connecting piece is hinged to the arm positioning hole on the front side wall of the arm body through a seventh horizontal pivot (17). The front end of the elastic element is hinged to the middle of the first connecting piece through an eighth horizontal pivot (18). The rear end of the elastic element is installed on the second horizontal pivot, an adjustment seat, or the inner side wall of the rear end of the arm body.

2. The constant force structure for reducing the distance between elastic elements according to claim 1, characterized in that: The inner side of the arm body forms a cavity structure, and the support plate and elastic components are both accommodated in the cavity structure of the arm body. The front end and rear end of the arm body are respectively formed with clearance notches. The rotating head seat and the adjusting seat can be rotatably inserted into the cavity structure of the arm body through the clearance notches. The arm positioning hole and the arm sliding groove are provided on the inner sidewalls of the left and right sides of the arm body.

3. The constant force structure for reducing the distance between elastic elements according to claim 1 or 2, characterized in that: The arm groove is either an inverted U-shaped opening groove with an open bottom or a closed elongated groove.

4. The constant force structure for reducing the distance between elastic elements according to claim 2, characterized in that: The elastic element includes a spring (19), an adjusting bolt (20), and a connecting block (21). A hook (22) is formed at the front end of the spring and is sleeved on the outside of the eighth horizontal rotating shaft. The connecting block is fixedly installed on the rear end of the spring. The stud of the adjusting bolt is movably screwed to the connecting block. The stud of the adjusting bolt can be extended and accommodated in the inner ring of the spring. A bolt through hole (23) extending radially is provided on the second horizontal rotating shaft. The adjusting bolt passes through the bolt through hole, and the head of the adjusting bolt stops at the rear side of the outer circumference of the second horizontal rotating shaft. An avoidance adjustment hole (24) is formed at the rear end of the arm body, which is directly opposite to the head of the adjusting bolt. Hardware tools can be inserted into the arm body through the avoidance adjustment hole and rotate the adjusting bolt. Rotating the adjusting bolt can change the initial elastic force value of the elastic element.

5. The constant force structure for reducing the distance between elastic elements according to claim 4, characterized in that: The rear side wall of the second horizontal rotating shaft in the circumferential direction is provided with a flat-bottomed groove (25) with a desliming structure. The head of the adjusting bolt is accommodated in the flat-bottomed groove, and the head of the adjusting bolt is tightly pressed against the flat bottom of the flat-bottomed groove.

6. The constant force structure for reducing the distance between elastic elements according to claim 4, characterized in that: The upper end of the adjustment seat forms a U-shaped structure. The two side walls of the U-shaped structure of the adjustment seat are respectively provided with first horizontal hinge holes (26). The rear end of the arm body is sleeved on the outside of the U-shaped structure at the upper end of the adjustment seat. The two side walls of the rear end of the arm body are respectively provided with second horizontal hinge holes (27). The second horizontal rotating shaft includes an adjustment bolt limiting shaft (28) and a connecting screw (29). The bolt through hole is located in the middle part of the adjustment bolt limiting shaft. The two ends of the adjustment bolt limiting shaft are respectively inserted into the first horizontal hinge hole and the second horizontal hinge hole. The two connecting screws pass through the second horizontal hinge hole and the first horizontal hinge hole and are screwed to the two ends of the adjustment bolt limiting shaft. The heads of the two connecting screws are respectively pressed against the left and right side surfaces of the rear end of the arm body.

7. The constant force structure for reducing the distance between elastic elements according to claim 6, characterized in that: The bottom surface of the U-shaped structure on the adjusting seat is a pointed structure with a height in the middle that is higher than the height on the front and rear sides. The screw part and the head of the adjusting bolt are respectively stopped on the front and rear sides of the bottom surface of the U-shaped structure on the adjusting seat.

8. The constant force structure for reducing the distance of elastic elements according to claim 2, characterized in that: The first connecting piece, the second connecting piece, and the support plate are all U-shaped structures. The support plate is sleeved on the outer side of the lower end of the first connecting piece, and the rear end of the second connecting piece is sleeved on the outer side of the upper end of the first connecting piece. The elastic element is accommodated inside the U-shaped structure of the support plate, and the front end of the elastic element extends into the inner side of the first connecting piece. The rotating head seat has a thinning step surface (30) formed on both axial side walls. The front end of the second connecting piece and the front end of the support plate are both sleeved on the outer side of the thinning step surface of the rotating head seat.

9. The constant force structure for reducing the distance between elastic elements according to claim 4, characterized in that: The arm body is also provided with an adjusting bolt guide plate (36), an opening groove is formed on the adjusting bolt guide plate, the adjusting bolt passes through the opening groove, and the bottom surface of the opening groove stops on the upper side surface of the adjusting bolt.

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