Three-section synchronous slide rail and drawer

Abstract

The present application discloses a three-section synchronous slide rail and a drawer, wherein the three-section synchronous slide rail includes a movable rail, a middle rail, a fixed rail, a gear assembly, an upper rack and a lower rack assembly; the upper rack is fixed in the movable rail, the middle rail is embedded in the movable rail movably along the length direction, the lower rack assembly is arranged in the middle rail movably along the length direction, and the lower rack assembly is connected to the fixed rail movably along the length direction; the gear assembly is arranged on the middle rail and passes through the top surface of the middle rail, the gear assembly is located between the upper rack and the lower rack assembly, the gear assembly includes a bevel gear, and the upper rack and the lower rack are respectively meshed with the bevel gear. According to the inclination of the bevel gear and the module or pitch of the upper rack and the lower rack, the speed ratio required for the movement of the upper rack and the lower rack is achieved. Compared with the existing two relatively rotating spur gears, the bevel gear is an integral body, which avoids the misalignment between the rack and the bevel gear, and improves the synchronous stability of the movement of the slide rail.

Description

Technical Field

[0001] The invention relates to the technical field of slide rails, and in particular to a three-section synchronous slide rail. Background Art

[0002] A drawer usually includes a slide rail, a drawer box and a box body, and the drawer box is set in the box body by pulling and moving the slide rail. Among the existing slide rails, Chinese patent document No. CN104352095B discloses a three-section synchronous hidden slide rail, which specifically discloses a movable rail, a middle rail, a fixed rail and a damping mechanism; an upper rack and an upper roller holder with rollers are arranged between the movable rail and the middle rail; a split lower roller holder with rollers is arranged between the middle rail and the fixed rail, and a rack is arranged on its surface; a gear assembly is meshed between the upper rack and the lower roller holder, and the gear assembly controls the movable rail and the middle rail to run synchronously or dislocated according to the magnitude of the force; the damping mechanism is assembled on the fixed rail; the gear assembly consists of gear A, gear B and a gear rack; gear A and gear B are assembled by a polygonal column and a polygonal hole in close cooperation, when the rotational force is greater than a certain value, the polygonal hole of gear B is enlarged, and the two gears slip and rotate, and when the rotational force is less than a certain value, the two gears rotate synchronously. The A gear and the B gear in this structure are tightly assembled through the polygonal column and the polygonal hole, and the misalignment adjustment function is achieved through the slipping and rotating effect of the two gears. However, due to the possibility of slippage between the two gears, the synchronization of the slide rail is unstable, and the force between the two gears needs to be precisely controlled to achieve both synchronization and adjustment. This places high demands on the manufacturing process, resulting in high production costs. In addition, the two gears are small in size, which is not conducive to assembly and has low assembly efficiency.

[0003] In summary, how to solve the problem of unstable synchronization of slide rail movement has become an urgent problem to be solved by technical personnel in this field. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a three-section synchronous slide rail to improve the synchronous stability of the slide rail movement.

[0005] Another object of the present invention is to provide a drawer comprising the three-section synchronous slide rail to improve the synchronous stability of the slide rail movement.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A three-section synchronous slide rail comprises a movable rail, a middle rail, a fixed rail, a gear assembly, an upper rack assembly and a lower rack assembly; the upper rack assembly is fixed in the movable rail, the middle rail is embedded in the movable rail movably along the length direction, the lower rack assembly is arranged in the middle rail movably along the length direction, and the lower rack assembly is connected to the fixed rail movably along the length direction; the gear assembly is arranged on the middle rail and passes through the top surface of the middle rail, the gear assembly is located between the upper rack assembly and the lower rack assembly, the gear assembly comprises a bevel gear, and the upper rack and the lower rack are respectively meshed with the bevel gear.

[0008] Preferably, in the above-mentioned three-section synchronous slide rail, the gear assembly further comprises a gear rack, the bevel gear is rotatably connected to the gear rack, and the gear rack is fixed to the top surface of the middle rail.

[0009] Preferably, the above-mentioned three-section synchronous slide rail further includes an upper roller assembly, which is movably arranged on the top surface of the middle rail along the length direction of the middle rail, and the movable rail and the middle rail move relative to each other through the upper roller assembly.

[0010] Preferably, in the above-mentioned three-section synchronous slide rail, the lower rack assembly includes a frame and a plurality of rollers arranged around the frame, the frame is provided with the lower rack, and the lower rack assembly moves relative to the middle rail and the fixed rail through the rollers.

[0011] Preferably, in the above-mentioned three-section synchronous slide rail, the frame body includes a lower rack frame body and a roller frame body which are assembled separately, the roller is arranged on the roller frame body, and the lower rack is arranged on the lower rack frame body.

[0012] Preferably, in the above three-section synchronous slide rail, it also includes:

[0013] An upper synchronization bar, integrally or separately arranged on the middle rail;

[0014] A lower synchronization bar, integrally or separately arranged on the fixed rail;

[0015] The synchronous gear is rotatably connected to the lower rack assembly, and the upper synchronous bar and the lower synchronous bar are both in transmission cooperation with the synchronous gear.

[0016] Preferably, in the above-mentioned three-section synchronous slide rail, the upper synchronization bar is provided with a plurality of equally spaced mating holes or mating teeth, and the lower synchronization bar is provided with a plurality of equally spaced mating holes or mating teeth, and the mating holes and the mating teeth are both used to cooperate with the synchronous gear.

[0017] Preferably, in the above-mentioned three-section synchronous slide rail, an anti-drop hook is provided on the side wall of the middle rail and is in limiting contact with the inner lower edge of the movable rail.

[0018] Preferably, in the above-mentioned three-section synchronous slide rail, the upper rack includes a main rack and an embedded rack that are separately assembled, and the tail of the movable rail is provided with an embedding hole for inserting the embedded rack.

[0019] The present invention also provides a drawer, comprising a slide rail, a drawer box and a box body, wherein the drawer box is drawably arranged in the box body, and the drawer box and the box body are drawably connected via a slide rail, characterized in that the slide rail is a three-section synchronous slide rail as described in any of the above items.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The three-section synchronous slide rail provided by the present invention comprises a movable rail, a middle rail, a fixed rail, a gear assembly, an upper rack assembly and a lower rack assembly; the upper rack is fixed in the movable rail, the middle rail is embedded in the movable rail movably along the length direction, the lower rack assembly is arranged in the middle rail movably along the length direction, and the lower rack assembly is connected to the fixed rail movably along the length direction; the gear assembly is arranged on the middle rail and passes through the top surface of the middle rail up and down, the gear assembly is located between the upper rack assembly and the lower rack assembly, the gear assembly comprises a bevel gear, and the upper rack and the lower rack are respectively meshed with the bevel gear. During operation, the movable rail moves, and the upper rack fixed on the movable rail drives the bevel gear of the gear assembly to rotate. Since the gear assembly is fixed on the middle rail, the bevel gear meshes with the lower rack of the lower rack assembly, so the middle rail and the movable rail move synchronously, and the lower rack assembly moves relative to the fixed rail under the overall force, and the bevel gear meshes with the upper rack and the lower rack respectively. According to the inclination of the bevel gear and the module or pitch of the upper rack and the lower rack, the speed ratio required for the movement of the upper rack and the lower rack is achieved, and the synchronous movement between the movable rail, the middle rail and the lower rack assembly is achieved. Compared with the existing two rotating tight-fitting spur gears, the bevel gear is a whole and will not slip, thereby avoiding misalignment between the rack and the bevel gear, and improving the synchronous stability of the movement of the slide rail. In addition, the bevel gear has a simple structure, fewer parts, and does not require high matching accuracy, thereby reducing the manufacturing cost and facilitating assembly.

[0022] The drawer provided by the present invention adopts the three-section synchronous slide rail in the present application, thereby improving the synchronous stability of the slide rail movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 A schematic structural diagram of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0025] Figure 2 An exploded schematic diagram of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0026] Figure 3 A schematic structural diagram of a lower rack assembly of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0027] Figure 4 for Figure 3 A local enlarged schematic diagram in FIG.

[0028] Figure 5 A schematic structural diagram of an upper synchronization bar of a three-section synchronization slide rail provided in an embodiment of the present invention;

[0029] Figure 6 A schematic diagram of the structure of a middle rail of a three-section synchronous slide rail provided in an embodiment of the present invention from a bottom view;

[0030] Figure 7 A schematic structural diagram of a lower synchronization bar of a three-section synchronization slide rail provided in an embodiment of the present invention;

[0031] Figure 8 A bottom view structural schematic diagram of a fixed rail of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0032] Fig. 9 A cross-sectional schematic diagram of the cooperation between a middle rail, a lower rack assembly and a fixed rail of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0033] Fig.10 A schematic structural diagram of a bevel gear of a gear assembly of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0034] Fig.11 A schematic structural diagram of a gear rack of a gear assembly of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0035] Fig.12 A schematic diagram of the combined structure of a gear assembly of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0036] Fig.13 A schematic side view of the structure of a bevel gear meshing with an upper rack and a lower rack of a three-section synchronous slide provided by an embodiment of the present invention;

[0037] Fig.14 A schematic diagram of the main structure of a three-section synchronous slide provided by an embodiment of the present invention, in which a bevel gear is meshed with an upper rack and a lower rack, and a synchronous gear cooperates with an upper synchronous bar and a lower synchronous bar;

[0038] Fig.15 A schematic diagram of the arrangement structure of an upper roller assembly of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0039] Fig.16 A schematic diagram of the structure of a three-section synchronous slide rail installed with an embedded rack provided by an embodiment of the present invention;

[0040] Fig.17 for Fig.16 The main view;

[0041] Fig.18 A schematic diagram of the structure for inserting the embedded rack;

[0042] Fig.19 A schematic structural diagram of a middle rail of a three-section synchronous slide rail provided in an embodiment of the present invention;

[0043] Fig. 20 A schematic structural diagram of the anti-unhooking cooperation between the movable rail and the middle rail of a three-section synchronous slide rail provided in an embodiment of the present invention.

[0044] Among them, 1 is a movable rail, 2 is a middle rail, 3 is a fixed rail, 4 is an upper rack, 5 is an upper roller assembly, 6 is a lower rack assembly, 7 is a damping mechanism, and 9 is a gear assembly;

[0045] 21 is the upper synchronization bar, 22 is the anti-unhooking, 31 is the lower synchronization bar, 41 is the main rack, 42 ​​is the embedded rack, 61 is the lower rack frame, 62 is the lower rack, 63 is the roller frame, 64 is the synchronization gear, 91 is the bevel gear, 92 is the gear frame, and 93 is the guide protrusion. DETAILED DESCRIPTION

[0046] The core of the present invention is to provide a three-section synchronous slide rail, which improves the synchronous stability of the slide rail movement.

[0047] The present invention also provides a drawer comprising the three-section synchronous slide rail, which improves the synchronous stability of the slide rail movement.

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Please refer to Figure 1-Figure 14The embodiment of the present invention provides a three-section synchronous slide rail, including a movable rail 1, a middle rail 2, a fixed rail 3, a gear assembly 9, an upper rack 4 and a lower rack assembly 6; wherein the upper rack 4 is fixed in the movable rail 1, and the upper rack 4 and the movable rail 1 move together; the middle rail 2 is embedded in the movable rail 1 and moves relative to the movable rail 1 along the length direction; the lower rack assembly 6 is arranged in the middle rail 2 and moves relative to the middle rail 2 along the length direction, and the lower rack assembly 6 is connected to the fixed rail 3 so as to move relative to the fixed rail 3 along the length direction. On the fixed rail 3; the gear assembly 9 is arranged on the middle rail 2 and passes through the top surface of the middle rail 2 up and down, the gear assembly 9 is located inside the movable rail 1, the gear assembly 9 and the middle rail 2 move together, and the gear assembly 9 is located between the upper rack 4 and the lower rack assembly 6; the gear assembly 9 includes a bevel gear 91, and the upper rack 4 and the lower rack 62 of the lower rack assembly 6 are respectively meshed with the bevel gear 91. Preferably, the meshing top surface of the upper rack 4 and the meshing top surface of the lower rack 62 are both inclined to better mesh with the bevel gear 91.

[0050] The working principle of the three-section synchronous slide rail is as follows: when working, the movable rail 1 moves, and the upper rack 4 fixed on the movable rail 1 moves relative to the middle rail 2, and the upper rack 4 drives the bevel gear 91 of the gear assembly 9 to rotate. Since the gear assembly 9 is fixed on the middle rail 2, the bevel gear 91 is meshed with the lower rack 62 of the lower rack assembly 6. Therefore, the bevel gear 91 drives the middle rail 2 to move relative to the lower rack assembly 6. The middle rail 2 and the movable rail 1 move synchronously at different speeds, and the lower rack assembly 6 moves relative to the fixed rail 3 under the overall force, and is respectively meshed with the upper rack 4 and the lower rack 62 through the bevel gear 91. The inclination of the bevel gear 91 and the module or pitch of the upper rack 4 and the lower rack 62 realize the speed ratio required for the movement of the upper rack 4 and the lower rack 62, thereby driving the movable rail 1, the middle rail 2 and the lower rack assembly 6 to move at this speed ratio, realizing the synchronous movement between the movable rail 1, the middle rail 2 and the lower rack assembly 6, and compared with the existing gear assembly composed of two relatively rotating and tightly matched spur gears, the gear assembly in the present application has only one bevel gear, which is a whole and will not slip, thereby avoiding misalignment between the rack and the bevel gear 91, and improving the synchronous stability of the movement of the slide rail. In addition, the bevel gear 91 has a simple structure, few parts, and does not require high matching accuracy, thereby reducing manufacturing costs and facilitating assembly.

[0051] like Figure 10-12 As shown, further, in this embodiment, the gear assembly 9 also includes a gear rack 92, the bevel gear 91 is rotatably connected to the gear rack 92, and the gear rack 92 is fixed to the top surface of the middle rail 2. The bevel gear 91 passes through the top surface of the middle rail 2 from top to bottom, and is respectively engaged with the upper rack 4 above the middle rail 2 and the lower rack 62 inside the middle rail 2. The gear rack 92 is preferably fixed to the middle rail 2 by snap-fitting, so as to facilitate overall disassembly and assembly.

[0052] Furthermore, in this embodiment, a guide protrusion 93 is provided at the lower end of the gear rack 92, and a guide groove is provided on the lower rack assembly 6 along the length direction. The guide protrusion 93 and the guide groove are movably matched, and the upper and lower limit functions of the guide protrusion 93 and the guide groove prevent the lower rack assembly 6 from falling relative to the middle rail 2 during the movement, thereby ensuring that the bevel gear 91 and the lower rack 62 are always in a state of precise meshing. Of course, the gear assembly 9 can also only include the bevel gear 91, and the bevel gear 91 is directly rotatably arranged on the top surface of the middle rail 2.

[0053] like Figure 2 and Fig.15 As shown, in this embodiment, the three-section synchronous slide rail also includes an upper roller assembly 5, which is arranged on the top surface of the middle rail 2 and moves along the length direction of the middle rail 2, and the movable rail 1 and the middle rail 2 move relative to each other through the upper roller assembly 5. The upper roller assembly 5 includes a roller bracket and a plurality of rollers arranged on the roller bracket, and the rolling surface of the roller is in contact with the movable rail 1. Balls are also arranged on both sides of the roller bracket, and the movable rail 1 and the middle rail 2 move by rolling with the balls. The upper roller assembly 5 realizes the smooth movement between the movable rail 1 and the middle rail 2, the friction resistance of the rolling friction is small, and the movement is more labor-saving. Of course, sliding friction can also be realized between the movable rail 1 and the middle rail 2.

[0054] like Figure 3 As shown, in this embodiment, the lower rack assembly 6 includes a frame body and a plurality of rollers arranged around the frame body, a lower rack 62 is arranged on the frame body, and the lower rack assembly 6 moves relative to the middle rail 2 and the fixed rail 3 through the rollers. The rollers located at the upper part of the frame body are used to roll and support the inner top surface of the middle rail 2, the rollers located on one side wall of the frame body are used to roll and contact with the side wall of the middle rail 2, the rollers located on the other side wall of the frame body are used to roll and contact with the side wall of the fixed rail 3, and the rollers located at the lower part of the frame body are used to roll and contact with the horizontal wall surface of the fixed rail 3. The rollers of the lower rack assembly 6 realize smooth movement between the lower rack assembly 6, the middle rail 2 and the fixed rail 3.

[0055] Furthermore, in this embodiment, the frame includes a lower rack frame 61 and a roller frame 63 which are assembled separately, the roller is arranged on the roller frame 63, and the lower rack 62 is arranged on the lower rack frame 61. The roller frame 63 and the lower rack frame 61 are connected by plug-in combination, which is convenient for disassembly and assembly. The frame adopts a split structure to facilitate processing, production and assembly.

[0056] like Figure 3-Figure 9As shown, since the existing slide rail is repeatedly stretched when the drawer is not fully pulled out, the center of gravity of the drawer is at the front end when it is pulled out, causing the tail of the lower rack assembly 6 to slightly tilt up. When closing the drawer, the roller of the lower rack assembly 6 will slide backward relative to the fixed rail 3, causing a slight misalignment between the lower rack assembly 6 and the fixed rail 3. The misaligned lower rack assembly 6 will prematurely press against the tail stop on the fixed rail 3 and cannot continue to move, resulting in the problem that the drawer cannot be completely closed. In order to solve this problem, in the present embodiment, the three-section synchronous slide rail further includes an upper synchronous bar 21, a lower synchronous bar 31 and a synchronous gear 64, wherein the upper synchronous bar 21 is arranged on the middle rail 2, specifically, the upper synchronous bar 21 is arranged on the inner top surface of the middle rail 2 along the length direction of the middle rail 2, the upper synchronous bar 21 and the middle rail 2 can be fixed separately or can be an integrally formed structure; the lower synchronous bar 31 is arranged on the fixed rail 3, specifically, the lower synchronous bar 31 is arranged on the outside of the fixed rail 3 along the length direction of the fixed rail 3, the lower synchronous bar 31 and the fixed rail 3 can be fixed separately or can be an integrally formed structure, and the upper synchronous bar 21 and the lower synchronous bar 31 are parallel; the synchronous gear 64 is rotatably connected to the lower rack assembly 6, specifically, the synchronous gear 64 is rotatably connected to the side of the frame 62, the synchronous gear 64 is located between the upper synchronous bar 21 and the lower synchronous bar 31, and the upper synchronous bar 21 and the lower synchronous bar 31 both cooperate with the synchronous gear 64 for transmission. When closing the drawer, the middle rail 2 moves relative to the lower rack assembly 6, and the lower rack assembly 6 moves relative to the fixed rail 3. Since the middle rail 2 is provided with an upper synchronization bar 21, the fixed rail 3 is provided with a lower synchronization bar 31, and the lower rack assembly 6 is provided with a synchronization gear 64, the upper synchronization bar 21, the synchronization gear 64 and the lower synchronization bar 31 cooperate with each other, so that the relative position relationship of the middle rail 2, the lower rack assembly 6 and the fixed rail 3 will not be misaligned during the movement, and the drawer can be completely closed.

[0057] Further, in the present embodiment, the upper synchronization bar 21 is provided with a plurality of matching holes or matching teeth arranged at equal intervals along the length direction of the upper synchronization bar 21, and the lower synchronization bar 31 is also provided with a plurality of matching holes or matching teeth arranged at equal intervals along the length direction of the lower synchronization bar 31. The matching holes or matching teeth can be directly provided on the middle rail 2 and the fixed rail 3, or can be provided separately on the bar structure and then fixed on the middle rail 2 and the fixed rail 3. The matching holes and matching teeth are both used to cooperate with the synchronization gear 64. As long as the upper synchronization bar 21 and the lower synchronization bar 31 can be synchronized with the synchronization gear 64, the upper synchronization bar 21 and the lower synchronization bar 31 are not limited to the structures listed in the present embodiment.

[0058] like Fig.19 and Fig. 20As shown, in this embodiment, an anti-detachment hook 22 is provided on the side wall of the middle rail 2 and is in limited contact with the inner lower edge of the movable rail 1. The purpose of such a setting is that when the force on the front end of the movable rail 1 is too large, the anti-detachment hook 22 on the middle rail 2 hooks the rear end of the movable rail 1 to prevent the movable rail 1 from tilting upward and falling out of the middle rail 2.

[0059] like Figure 16-18 As shown, further, in this embodiment, the upper rack 4 includes a main rack 41 and an embedded rack 42 which are assembled separately, and the tail of the movable rail 1 is provided with an embedded hole for inserting the embedded rack 42. Such an arrangement is to prevent the bevel gear 91 from being misaligned with the upper rack 4 and the lower rack 62, so the tail end of the upper rack 4 is provided with a separate embedded rack 42. When assembling, the slide rail is first opened and pulled to the final point, at which time the main rack 41 and the bevel gear 91 are in a disengaged state, and the lower rack 62 is in a meshing state; then the embedded rack 42 is inserted into the embedded hole, and docked with the main rack 41 to form a complete upper rack 4, at which time the embedded rack 42 is meshed with the bevel gear 91, so that the upper rack 4, the bevel gear 91 and the lower rack 62 are meshed in the correct position.

[0060] like Figure 2 As shown, in this embodiment, the three-section synchronous slide rail further includes a damping mechanism 7 to achieve damped movement of the slide rail. A specific structure of the damping mechanism 7 can be found in the description of patent CN104352095B, ​​which will not be repeated here.

[0061] Based on the three-section synchronous slide rail described in any of the above embodiments, an embodiment of the present invention further provides a drawer, including a slide rail, a drawer box and a box body, wherein the drawer box is drawably arranged in the box body, and the drawer box and the box body are drawably connected via the slide rail, wherein the slide rail is a three-section synchronous slide rail as described in any of the above embodiments. Preferably, a three-section synchronous slide rail is arranged on both sides of the bottom of the drawer box to improve the stability of movement.

[0062] Since the drawer adopts the three-section synchronous slide rail in the present application, the synchronous stability of the slide rail movement is improved.

[0063] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0064] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A three-section synchronous slide rail, characterized in that: It comprises a movable rail, a middle rail, a fixed rail, a gear assembly, an upper rack assembly and a lower rack assembly; the upper rack assembly is fixed in the movable rail, the middle rail is embedded in the movable rail movably along the length direction, the lower rack assembly is arranged in the middle rail movably along the length direction, and the lower rack assembly is connected to the fixed rail movably along the length direction; the gear assembly is arranged on the middle rail and passes through the top surface of the middle rail, the gear assembly is located between the upper rack assembly and the lower rack assembly, the gear assembly comprises a bevel gear, and the upper rack assembly and the lower rack assembly are respectively meshed with the bevel gear; The top surface of the teeth of the upper rack and the top surface of the teeth of the lower rack are both inclined; The gear assembly also includes a gear rack, the bevel gear is rotatably connected to the gear rack, the gear rack is fixed to the top surface of the middle rail, and the gear rack is fixed to the middle rail by snap-fitting.

2. The three-section synchronous slide rail according to claim 1, characterized in that: A guide protrusion is arranged at the lower end of the gear frame, and a guide groove is arranged on the lower rack assembly along the length direction. The guide protrusion is movably matched with the guide groove and is limited up and down.

3. The three-section synchronous slide rail according to claim 1, characterized in that: It also includes an upper roller assembly, which is used to move the top surface of the middle rail along the length direction of the middle rail, and the movable rail and the middle rail move relatively through the upper roller assembly.

4. The three-section synchronous slide rail according to claim 1, characterized in that: The lower rack assembly comprises a frame body and a plurality of rollers arranged around the frame body, the frame body is provided with the lower rack, and the lower rack assembly moves relative to the middle rail and the fixed rail through the rollers.

5. The three-section synchronous slide rail according to claim 4, characterized in that: The frame body comprises a lower rack frame body and a roller frame body which are assembled separately, the roller is arranged on the roller frame body, and the lower rack is arranged on the lower rack frame body.

6. The three-section synchronous slide rail according to claim 1, characterized in that: Also includes: An upper synchronization bar, integrally or separately arranged on the middle rail; A lower synchronization bar, integrally or separately arranged on the fixed rail; The synchronous gear is rotatably connected to the lower rack assembly, and the upper synchronous bar and the lower synchronous bar are both in transmission cooperation with the synchronous gear.

7. The three-section synchronous slide rail according to claim 6, characterized in that: The upper synchronization bar is provided with a plurality of matching holes or matching teeth at equal intervals, and the lower synchronization bar is provided with a plurality of matching holes or matching teeth at equal intervals, and the matching holes and the matching teeth are both used to match with the synchronization gear.

8. The three-section synchronous slide rail according to claim 1, characterized in that: An anti-drop hook is arranged on the side wall of the middle rail and is in limiting contact with the inner lower edge of the movable rail.

9. The three-section synchronous slide rail according to claim 1, characterized in that: The upper rack comprises a main rack and an embedded rack which are assembled in parts, and the tail of the movable rail is provided with an embedded hole for clamping the embedded rack.

10. A drawer, comprising a slide rail, a drawer box and a box body, wherein the drawer box is drawably arranged in the box body, and the drawer box and the box body are drawably connected via the slide rail, characterized in that: The slide rail is a three-section synchronous slide rail as described in any one of claims 1-9.

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