Special power distribution cabinet for frequency converter
By designing a sealable and open-closed installation structure and an adjustable air ventilation structure in a dedicated power distribution cabinet for the inverter, the contradiction between heat dissipation of electrical components and environmental exposure is solved, and good heat dissipation effect and safety are achieved.
Patent Information
- Application Number
- CN202510416502.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-05-16
AI Technical Summary
While improving the heat dissipation of electrical components, existing electrical cabinets can easily cause the components to be exposed to the environment, increasing dust pollution and safety hazards.
A special power distribution cabinet for inverters is designed, adopting a sealable and open-closed installation structure, and an adjustment device is provided at the mouth of the air-guided ventilation structure, and the position of the ventilation port is adjusted according to the installation status of the electrical components in the box to form a suitable air duct to promote heat dissipation.
It realizes that while maintaining the heat dissipation effect of electrical components, avoiding the components being exposed to the environment, reducing dust pollution and safety hazards.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of electrical equipment, and in particular to a special power distribution cabinet for a frequency converter. Background Art
[0002] When installing electrical engineering equipment, in order to ensure the safety of components and the safety of subsequent use, the corresponding installation cabinet will be used to install the equipment. However, this puts the electrical components in a relatively sealed environment. The inability to circulate air normally will make the heat dissipation of the electrical components a major problem, causing the electrical components to work in an overheated state for a long time, which will shorten the service life of the electrical components and even cause damage to the electrical components in some extreme cases, leading to safety accidents. Therefore, existing electrical cabinets will be provided with structural vents, but this will make the electrical components installed in the cabinet in an environmentally exposed working state, which will pose certain safety hazards due to pollution such as dust. Therefore, it is necessary to design a new electrical cabinet that can solve the above problems. Summary of the invention
[0003] The purpose of the present invention is to address the defects and shortcomings of the prior art and provide a special power distribution cabinet for inverters. The cabinet provides a sealing and opening mounting structure, and a corresponding air guide and ventilation structure is arranged for the opening and closing nose of the mounting structure. The mouth of the air guide and ventilation structure is adjustable, so that electrical components can be installed in the mounting structure, and the position of the mouth of the ventilation structure can be adjusted according to the opening and closing state of the mounting structure, so as to form a correct air duct in the box, so that a ventilation structure for dissipating heat from the electrical components is formed in the box.
[0004] In order to achieve the above object, the present invention adopts the following technical solutions: The utility model comprises a box body and a box door, wherein the box door is hingedly arranged on the side of the front port of the box body, and the utility model further comprises: A mounting mechanism, wherein the mounting mechanism is arranged inside the box; The air guide mechanism is arranged on the box body, and the air guide mechanism and the mounting mechanism are arranged in a one-to-one correspondence.
[0005] Preferably, the mounting mechanism comprises: Partitions, the number of which is plural and the partitions are arranged equidistantly up and down and fixed on the inner wall of the box body; An installation box, the installation box is fixedly arranged on the upper surface of the partition; A top cover, which is arranged above the installation box; A lifting slide rail, wherein the lifting slide rail is fixedly arranged on the outer side wall of the installation box; A lifting slider, wherein the lifting slider is fixedly arranged on the outer side wall of the top cover, and the lifting slider is slidably arranged on the lifting rail; The opening and closing assembly is arranged in the box body, and the opening and closing assembly is arranged in cooperation with the top cover.
[0006] Preferably, the opening and closing assembly comprises: An opening and closing screw rod, the opening and closing screw rod is screwed through the box body through a bearing, and the opening and closing screw rod is screwed through the partition through a bearing, and the opening and closing screw rod is arranged at the rear of the installation box; An opening and closing guide rod, which is arranged at the rear of the installation box and is passed through and fixed on the partition; An opening and closing guide seat, wherein the opening and closing guide seat is fixedly arranged on the rear side wall of the top cover, and the opening and closing guide seat is movably sleeved on the opening and closing guide rod; An opening and closing threaded sleeve, wherein the opening and closing threaded sleeve is sleeved on the opening and closing screw rod through a threaded connection, and the opening and closing threaded sleeve is movably sleeved on the opening and closing guide rod; The opening and closing tension spring is fixedly arranged on the opening and closing threaded sleeve, and the upper end of the opening and closing tension spring is fixedly arranged on the opening and closing guide seat.
[0007] Preferably, the air guide mechanism comprises: An air guide cover, wherein two air guide covers form a group and are symmetrically arranged on the left and right sides of the installation box, an air guide port is opened on the side wall of the box, and the air guide cover is fixedly arranged on the inner wall of the box, and the air guide cover is arranged to cover the air guide port; An adjusting cover, wherein the adjusting cover is sleeved on the upper port of the air guide cover; An adjusting guide rod, wherein the adjusting guide rod is passed through and fixed on the partition; An adjusting guide sleeve, wherein the adjusting guide sleeve is fixedly arranged on the rear side wall of the adjusting cover, and the adjusting guide sleeve is movably arranged on the adjusting guide rod; The lifting component is arranged in the box body, and the lifting component is arranged in cooperation with the air guide cover.
[0008] Preferably, the lifting assembly comprises: A connecting frame, wherein the connecting frame is arranged at the rear side of the installation box, and both ends of the connecting frame are respectively fixedly arranged on the adjustment guide sleeves on both sides; Lifting screw rods, the lifting screw rods are two and symmetrically connected to the box body through bearings, and the lifting screw rods are connected to the partition through bearings; A lifting guide sleeve, wherein the lifting guide sleeve is fixedly arranged on the connecting frame, and the lifting guide sleeve is movablely arranged on the lifting screw rod; A lifting threaded sleeve, wherein the lifting threaded sleeve is arranged on the lifting screw rod through a threaded connection sleeve; A guide block, wherein the guide block is fixedly arranged on the lifting threaded sleeve, and the guide block is movably arranged against the inner wall of the box body; The lifting tension spring is fixedly arranged on the lifting threaded sleeve, and the upper end of the lifting tension spring is fixedly arranged on the lifting guide sleeve.
[0009] Preferably, a limiting guide sleeve is fixedly provided on the outer side wall of the installation box, a limiting guide frame is movably inserted into the limiting guide sleeve, and a limiting block is fixedly provided at the rear end of the limiting guide frame.
[0010] Preferably, an opening and closing drive shaft is rotatably provided on the inner wall of the box body through a bearing, and the rear end of the opening and closing drive shaft is connected to the lower end of the opening and closing screw rod through a bevel gear set.
[0011] Preferably, a lifting drive shaft is rotated on the inner wall of the box body through a bearing, and the rear end of the lifting drive shaft is connected to the lower end of one of the lifting screw rods through a bevel gear set. A transmission shaft is rotated on the inner wall of the box body through a bearing, and both ends of the transmission shaft are respectively connected to the lower ends of the lifting screw rods on both sides through a bevel gear set.
[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The device is provided with an installation box in the box body, and a top cover is provided on the upper port of the installation box, air guide ports are provided on the two side walls of the box body, and an air guide cover and an adjustment cover are provided, so that the opening and closing state of the installation box can be controlled by adjusting the positions of the top cover and the adjustment cover respectively, and the position of the air outlet of the adjustment cover can be adjusted; 2. The device sets a limit block between the top cover and the connecting frame for installing the adjustment cover, and installs the limit block through the limit guide sleeve and the limit guide frame, so as to realize the limit control of the top cover or the connecting frame. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a schematic diagram of the ground structure of the present invention.
[0014] Figure 2 yes Figure 1 Front side view.
[0015] Figure 3 It is a structural schematic diagram of the installation mechanism and the air guide mechanism in the present invention.
[0016] Figure 4 It is a schematic diagram of the connection of the installation box, the connecting sleeve and the fiber guide sleeve in the present invention.
[0017] Figure 5 It is a structural schematic diagram of the installation box, top cover, and opening and closing screw rod in the present invention.
[0018] Figure 6 It is a schematic diagram of the connection of the air guide cover, the adjustment cover, the connecting frame and the adjustment screw rod in the present invention.
[0019] Figure 7 It is a structural schematic diagram of the installation box, the limiting guide frame and the limiting block in the present invention.
[0020] Description of reference numerals: Box body 1, box door 2, installation mechanism 3, partition 3-1, installation box 3-2, top cover 3-3, lifting slide rail 3-4, lifting slider 3-5, opening and closing assembly 4, opening and closing guide rod 4-1, opening and closing guide seat 4-2, opening and closing screw rod 4-3, opening and closing threaded sleeve 4-4, opening and closing tension spring 4-5, air guide mechanism 5, air guide cover 5-1, air guide port 5-2, adjustment cover 5-3, adjustment guide rod 5-4, adjustment guide sleeve 5-5, lifting assembly 6, connecting frame 6-1, lifting screw rod 6-2, lifting guide sleeve 6-3, lifting threaded sleeve 6-4, guide block 6-5, lifting tension spring 6-6, limit guide sleeve 7, limit guide frame 8, limit block 9, opening and closing drive shaft 10, lifting drive shaft 11, transmission shaft 12. DETAILED DESCRIPTION
[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. The preferred embodiments in the description are only used as examples, and all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of the present invention.
[0022] like Figure 1-7 As shown, this specific implementation adopts the following technical solutions: It comprises a box body 1 and a box door 2, wherein the box door 2 is hingedly arranged on the side of the front port of the box body 1, and it also comprises: A mounting mechanism 3, wherein the mounting mechanism 3 is arranged inside the box body 1; An air guide mechanism 5, wherein the air guide mechanism 5 is arranged on the box body 1, and the air guide mechanism 5 is arranged in a one-to-one correspondence with the mounting mechanism 3; The mounting mechanism 3 comprises: Partitions 3-1, there are several partitions 3-1, and the partitions 3-1 are arranged equidistantly up and down and fixedly arranged on the inner wall of the box body 1; An installation box 3-2, wherein the installation box 3-2 is fixedly arranged on the upper surface of the partition 3-1; A top cover 3-3, wherein the top cover 3-3 is arranged above the installation box 3-2; A lifting rail 3-4, wherein the lifting rail 3-4 is fixedly arranged on the outer side wall of the installation box 3-2; A lifting slider 3-5, wherein the lifting slider 3-5 is fixedly arranged on the outer side wall of the top cover 3-3, and the lifting slider 3-5 is slidably arranged on the lifting rail 3-4; An opening and closing component 4, wherein the opening and closing component 4 is disposed in the box body 1, and the opening and closing component 4 is disposed in cooperation with the top cover 3-3; The opening and closing component 4 comprises: The opening and closing screw rod 4-3 is screwed through the box body 1 through a bearing, and the opening and closing screw rod 4-3 is screwed through the partition 3-1 through a bearing, and the opening and closing screw rod 4-3 is arranged at the rear of the installation box 3-2; An opening and closing guide rod 4-1, wherein the opening and closing guide rod 4-1 is arranged at the rear of the installation box 3-2, and the opening and closing guide rod 4-1 is passed through and fixed on the partition plate 3-1; An opening and closing guide seat 4-2, wherein the opening and closing guide seat 4-2 is fixedly arranged on the rear side wall of the top cover, and the opening and closing guide seat 4-2 is movably sleeved on the opening and closing guide rod 4-1; An opening and closing threaded sleeve 4-4, wherein the opening and closing threaded sleeve 4-4 is sleeved on the opening and closing screw rod 4-3 through a threaded connection, and the opening and closing threaded sleeve 4-4 is movably sleeved on the opening and closing guide rod 4-1; An opening and closing tension spring 4-5, wherein the opening and closing clamping spring is fixedly arranged on the opening and closing threaded sleeve 4-4, and the upper end of the opening and closing tension spring 4-5 is fixedly arranged on the opening and closing guide seat 4-2; An opening and closing drive shaft 10, wherein the opening and closing drive shaft 10 is rotatably mounted on the inner wall of the housing 1 through a bearing, and the rear end of the opening and closing drive shaft 10 is connected to the lower end of the opening and closing screw rod 4-3 through a bevel gear set; The gas guide mechanism 5 comprises: Air guide covers 5-1, two of which are arranged in a group and are symmetrically arranged on the left and right sides of the installation box 3-2, an air guide port 5-2 is opened on the side wall of the box body 1, and the air guide covers 5-1 are fixedly arranged on the inner wall of the box body 1, and the air guide covers 5-1 are arranged to cover the air guide port 5-2; An adjusting cover 5-3, wherein the adjusting cover 5-3 is sleeved on the upper port of the air guide cover 5-1; An adjusting guide rod 5-4, wherein the adjusting guide rod 5-4 is inserted and fixed on the partition plate 3-1; An adjusting guide sleeve 5-5, wherein the adjusting guide sleeve 5-5 is fixedly arranged on the rear side wall of the adjusting cover 5-3, and the adjusting guide sleeve 5-5 is movably sleeved on the adjusting guide rod 5-4; A lifting assembly 6, wherein the lifting assembly 6 is disposed in the box body 1, and the lifting assembly 6 is disposed in cooperation with the air guide cover 5-1; The lifting assembly 6 comprises: A connecting frame 6-1, wherein the connecting frame 6-1 is arranged at the rear side of the installation box 3-2, and both ends of the connecting frame 6-1 are respectively fixedly arranged on the adjustment guide sleeves 5-5 on both sides; The lifting screw rods 6-2 are two and symmetrically connected to the box body 1 through bearings, and the lifting screw rods 6-2 are connected to the partition plate 3-1 through bearings; A lifting guide sleeve 6-3, wherein the lifting guide sleeve 6-3 is fixedly arranged on the connecting frame 6-1, and the lifting guide sleeve 6-3 is movably sleeved on the lifting screw rod 6-2; A lifting thread sleeve 6-4, wherein the lifting thread sleeve 6-4 is arranged on the lifting screw rod 6-2 through a threaded connection; A guide block 6-5, wherein the guide block 6-5 is fixedly arranged on the lifting threaded sleeve 6-4, and the guide block 6-5 is movably arranged against the inner wall of the box body 1; A lifting tension spring 6-6, wherein the lifting tension spring 6-6 is fixedly arranged on the lifting threaded sleeve 6-4, and the upper end of the lifting tension spring 6-6 is fixedly arranged on the lifting guide sleeve 6-3; A lifting drive shaft 11, wherein the lifting drive shaft 11 is rotatably mounted on the inner wall of the housing 1 through a bearing, and the rear end of the lifting drive shaft 11 and the lower end of one of the lifting screw rods 6-2 are driven by a bevel gear set; The transmission shaft 12 is rotatably mounted on the inner wall of the housing 1 through a bearing, and the left and right ends of the transmission shaft 12 are respectively connected to the lower ends of the lifting screws 6-2 on the left and right sides through a bevel gear set; A limiting guide sleeve 7, wherein two limiting guide sleeves 7 form a group and are respectively fixedly arranged on the left and right side walls of the installation box 3-2; A position limiting guide frame 8, wherein the position limiting guide frame 8 is movably inserted into the position limiting guide sleeve 7; The limiting block 9 is fixedly arranged at the rear end of the limiting guide frame 8 .
[0023] When using the device, the box door 2 is opened, and the opening and closing drive shaft 10 drives the opening and closing screw rod 4-3 to rotate forwardly, and then the opening and closing screw rod 4-3 pushes the opening and closing threaded sleeve 4-4 upward, that is, the opening and closing guide seat 4-2 is pushed upward by the opening and closing threaded sleeve 4-4, and then the opening and closing guide seat 4-2 pushes the top cover 3-3 upward, so that the top cover 3-3 moves upward and opens, that is, the equipment in the installation box 3-2 is operated; when the top cover 3-3 is closed and buckled on the installation box 3-2, the adjustment cover 5-3 is placed on the upper part, and when the top cover 3-3 is opened, the adjustment cover 5-3 is lowered so that the outlet end of the air guide cover 5-1 is placed between the installation box 3-2 and the top cover 3-3; a group of two limiting guide frames 8 are synchronously slid, and then the position of the limiting block 9 is adjusted, so that the limiting block 9 abuts against the connecting frame 6-1 to prevent the connecting frame 6-1 from descending, or The limit block 9 is pressed against the top cover 3-3 to prevent the top cover 3-3 from descending; the opening and closing threaded sleeve 4-4 is pushed downward by the opening and closing screw rod 4-3, and then the opening and closing threaded sleeve 4-4 pulls the top cover 3-3 down through the opening and closing tension spring 4-5, and then when the top cover 3-3 is pressed against by the limit block 9, the opening and closing tension spring 4-5 is tensioned, and the lifting threaded sleeve 6-4 is pushed downward by the lifting screw rod 6-2, and then the lifting threaded sleeve 6-4 pulls the connecting frame 6-1 down through the lifting tension spring 6-6, and then when the connecting frame 6-1 is pressed against by the limit block 9, the lifting tension spring 6-6 is tensioned, and a group of two limit blocks 9 can only press against the top cover 3-3 or the connecting frame 6-1; when one lifting screw rod 6-2 is driven to rotate by the lifting drive shaft 11, the lifting screw rod 6-2 is driven by the transmission shaft 12 to drive the two lifting screw rods 6-2 to rotate synchronously.
[0024] Compared with the prior art, the present invention has the following beneficial effects: 1. The device is provided with an installation box 3-2 in a box body 1, and a top cover 3-3 is provided on the upper port of the installation box 3-2, an air guide port 5-2 is provided on the two side walls of the box body 1, and an air guide cover 5-1 and an adjustment cover 5-3 are provided, so that the opening and closing state of the installation box 3-2 can be controlled, and the position of the air outlet of the adjustment cover 5-3 can be adjusted by adjusting the positions of the top cover 3-3 and the adjustment cover 5-3 respectively; 2. The device sets a limit block 9 between the top cover 3-3 and the connecting frame 6-1 for installing the adjustment cover 5-3, and installs the limit block 9 through the limit guide sleeve 7 and the limit guide frame 8, thereby realizing the limit control of the top cover 3-3 or the connecting frame 6-1.
[0025] For those skilled in the art, they can modify the technical solutions described in the aforementioned embodiments and make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A power distribution cabinet for a frequency converter, comprising a cabinet (1) and a cabinet door (2), wherein the cabinet door (2) is hingedly mounted on a side edge of a front port of the cabinet (1); characterized in that: It also contains: A mounting mechanism (3), wherein the mounting mechanism (3) is arranged inside the box (1); An air guide mechanism (5), wherein the air guide mechanism (5) is arranged on the box body (1), and the air guide mechanism (5) and the mounting mechanism (3) are arranged in a one-to-one correspondence.
2. The inverter-specific power distribution cabinet according to claim 1, characterized in that: The mounting mechanism (3) comprises: Partitions (3-1), wherein there are a plurality of partitions (3-1), and the partitions (3-1) are arranged equidistantly up and down and fixedly arranged on the inner wall of the box body (1); An installation box (3-2), wherein the installation box (3-2) is fixedly arranged on the upper surface of the partition (3-1); A top cover (3-3), wherein the top cover (3-3) is arranged above the installation box (3-2); A lifting slide rail (3-4), wherein the lifting slide rail (3-4) is fixedly arranged on an outer side wall of the installation box (3-2); A lifting slider (3-5), wherein the lifting slider (3-5) is fixedly arranged on the outer side wall of the top cover (3-3), and the lifting slider (3-5) is slidably arranged on the lifting slide rail (3-4); An opening and closing component (4), wherein the opening and closing component (4) is arranged in the box body (1), and the opening and closing component (4) is arranged in cooperation with the top cover (3-3).
3. The inverter-specific power distribution cabinet according to claim 2 is characterized in that: The opening and closing assembly (4) comprises: An opening and closing screw rod (4-3), the opening and closing screw rod (4-3) is screwed through the box body (1) through a bearing, and the opening and closing screw rod (4-3) is screwed through the partition plate (3-1) through a bearing, and the opening and closing screw rod (4-3) is arranged at the rear of the installation box (3-2); An opening and closing guide rod (4-1), wherein the opening and closing guide rod (4-1) is arranged at the rear of the installation box (3-2), and the opening and closing guide rod (4-1) is passed through and fixed on the partition plate (3-1); An opening and closing guide seat (4-2), wherein the opening and closing guide seat (4-2) is fixedly arranged on the rear side wall of the top cover (3-3), and the opening and closing guide seat (4-2) is movably sleeved on the opening and closing guide rod (4-1); An opening and closing threaded sleeve (4-4), wherein the opening and closing threaded sleeve (4-4) is sleeved on the opening and closing screw rod (4-3) through a threaded connection, and the opening and closing threaded sleeve (4-4) is movably sleeved on the opening and closing guide rod (4-1); An opening and closing tension spring (4-5), wherein the opening and closing clamping spring is fixedly arranged on the opening and closing threaded sleeve (4-4), and the upper end of the opening and closing tension spring (4-5) is fixedly arranged on the opening and closing guide seat (4-2).
4. The inverter-specific power distribution cabinet according to claim 3 is characterized in that: The air guide mechanism (5) comprises: An air guide cover (5-1), wherein two of the air guide covers (5-1) form a group and are symmetrically arranged on the left and right sides of the installation box (3-2), an air guide port (5-2) is opened on the side wall of the box body (1), the air guide cover (5-1) is fixedly arranged on the inner wall of the box body (1), and the air guide cover (5-1) is arranged to cover the air guide port (5-2); An adjusting cover (5-3), wherein the adjusting cover (5-3) is sleeved on an upper port of the air guide cover (5-1); An adjusting guide rod (5-4), wherein the adjusting guide rod (5-4) is passed through and fixed on the partition plate (3-1); An adjusting guide sleeve (5-5), wherein the adjusting guide sleeve (5-5) is fixedly arranged on the rear side wall of the adjusting cover (5-3), and the adjusting guide sleeve (5-5) is movably sleeved on the adjusting guide rod (5-4); A lifting component (6), wherein the lifting component (6) is arranged in the box body (1), and the lifting component (6) is arranged in cooperation with the air guide cover (5-1).
5. The inverter-specific power distribution cabinet according to claim 4 is characterized in that: The lifting assembly (6) comprises: A connecting frame (6-1), wherein the connecting frame (6-1) is arranged on the rear side of the installation box (3-2), and both ends of the connecting frame (6-1) are respectively fixedly arranged on the adjustment guide sleeves (5-5) on both sides; Lifting screw rods (6-2), wherein the lifting screw rods (6-2) are two and symmetrically disposed on the box body (1) through rotational connection with bearings, and the lifting screw rods (6-2) are rotationally connected with bearings and disposed on the partition plate (3-1); A lifting guide sleeve (6-3), wherein the lifting guide sleeve (6-3) is fixedly arranged on the connecting frame (6-1), and the lifting guide sleeve (6-3) is movably sleeved on the lifting screw rod (6-2); A lifting threaded sleeve (6-4), wherein the lifting threaded sleeve (6-4) is arranged on the lifting screw rod (6-2) through a threaded connection sleeve; A guide block (6-5), wherein the guide block (6-5) is fixedly arranged on the lifting threaded sleeve (6-4), and the guide block (6-5) is movably arranged against the inner wall of the box body (1); A lifting tension spring (6-6), wherein the lifting tension spring (6-6) is fixedly arranged on the lifting threaded sleeve (6-4), and the upper end of the lifting tension spring (6-6) is fixedly arranged on the lifting guide sleeve (6-3).
6. The inverter-specific power distribution cabinet according to claim 5, characterized in that: A limiting guide sleeve (7) is fixedly arranged on the outer wall of the installation box (3-2), a limiting guide frame (8) is movably inserted into the limiting guide sleeve (7), and a limiting block (9) is fixedly arranged at the rear end of the limiting guide frame (8).
7. The inverter-specific power distribution cabinet according to claim 6, characterized in that: An opening and closing drive shaft (10) is rotatably mounted on the inner wall of the box body (1) via a bearing, and the rear end of the opening and closing drive shaft (10) is connected to the lower end of the opening and closing screw rod (4-3) via a bevel gear set.
8. The inverter-specific power distribution cabinet according to claim 7, characterized in that: A lifting drive shaft (11) is rotatably mounted on the inner wall of the housing (1) via a bearing, the rear end of the lifting drive shaft (11) is connected to the lower end of one of the lifting screw rods (6-2) via a bevel gear set, and a transmission shaft (12) is rotatably mounted on the inner wall of the housing (1) via a bearing, the two ends of the transmission shaft (12) are connected to the lower ends of the lifting screw rods (6-2) on both sides via a bevel gear set.