A negative pressure sampling head and a non-contact labyrinth sealing structure

Abstract

A negative pressure sampling head and a non-contact labyrinth seal structure are disclosed, belonging to the field of labyrinth seals for gearboxes or transmissions. The negative pressure sampling head has an arc-shaped windward surface perpendicular to the airflow, with the upper part of the arc-shaped windward surface being horizontal and the lower part inclined upward, thereby forming a negative pressure sampling area at the bottom of the arc-shaped windward surface. The non-contact labyrinth seal structure includes a sealing body and several sealing teeth. The sealing body is provided with a suction hole connecting the sealing cavity and the outside, and the suction hole is connected to the negative pressure sampling area of ​​the negative pressure sampling head through an air pipe to balance the pressure on both sides of the sealing body along the axis. The negative pressure sampling head of this invention, by designing an arc-shaped windward surface to form a negative pressure sampling area, makes full use of the airflow generated when the shaft rotates inside the gearbox or transmission, forming a negative pressure area inside the gearbox or transmission. Then, this negative pressure area is used to balance the air pressure inside and outside the non-contact labyrinth seal, ultimately solving the problem of preventing leakage of the non-contact labyrinth seal.

Description

Technical Field

[0001] This invention relates to the field of sealing gearboxes or transmission boxes, specifically a negative pressure sampling head and a non-contact labyrinth sealing structure. Background Technology

[0002] Non-contact labyrinth seals utilize a series of sequentially arranged annular sealing teeth around the rotating shaft. These teeth create a series of flow-blocking gaps and expansion cavities, causing a throttling effect as the sealed medium passes through the labyrinthine gaps, thus preventing leakage. However, in high-speed gearboxes, the high-speed rotation of the rotor causes an increase in internal pressure, leading to leakage of the oil-gas mixture through the flow-blocking gaps and reducing the sealing performance of the non-contact labyrinth seal. Summary of the Invention

[0003] To address the leakage problem caused by the pressure difference between the inside and outside of the sealing structure in existing non-contact labyrinth seals, this invention provides a negative pressure sampling head and a non-contact labyrinth seal structure. The negative pressure sampling head of this invention can generate negative pressure when the shaft rotates inside the gearbox or transmission box, and collect this negative pressure to balance the pressure difference on both sides of the non-contact labyrinth seal, effectively preventing seal leakage, improving the performance of the non-contact sealing structure, and extending the service life of the non-contact labyrinth seal structure.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a negative pressure sampling head, wherein the negative pressure sampling head has an arc-shaped windward surface perpendicular to the airflow, and the upper part of the arc-shaped windward surface is horizontal and the lower part is inclined upward, thereby forming a negative pressure sampling area at the bottom of the arc-shaped windward surface.

[0005] As an optimized solution for the aforementioned negative pressure sampling head, the curvature of the arc-shaped windward surface gradually increases from top to bottom.

[0006] As another optimized solution for the aforementioned negative pressure sampling head, the negative pressure sampling head is a hollow plate-shaped component with a horizontal upper surface and an inclined slope lower surface, thus forming a pointed tip on one side. The side opposite the pointed tip is an arc-shaped windward surface with a gradually increasing curvature from top to bottom, and the area near the lower surface at the bottom of the arc-shaped windward surface forms a negative pressure sampling zone. Several air holes connecting the internal cavity of the plate-shaped component are distributed on the negative pressure sampling zone. The negative pressure sampling head is located on one side of the shaft, and the tangent of the arc-shaped windward surface is perpendicular to the rotation direction of the shaft, so that the airflow generated by the high-speed rotation of the shaft forms a negative pressure sampling zone at the bottom of the arc-shaped windward surface.

[0007] As another optimized solution for the aforementioned negative pressure sampling head, the negative pressure sampling head is a cavity formed by a horizontal plate, an inclined plate, an arc-shaped plate, and two vertical sealing plates. One side of the inclined plate is connected to one side of the horizontal plate to form a pointed part, and the other sides of the inclined plate and the horizontal plate are respectively connected to the arc-shaped plate to form a triangular cavity with openings on both sides. The two vertical sealing plates close the triangular cavity.

[0008] As another optimization scheme of the above-mentioned negative pressure collection head, the curvature of the arc plate gradually increases from the side connected to the horizontal plate to the side connected to the inclined plate. The arc plate is perpendicular to the tangent of the shaft rotation direction, so that the airflow generated by the high-speed rotation of the shaft impacts the surface of the arc plate and forms a negative pressure collection area in the junction area of ​​the arc plate and the inclined plate. Several air holes with connected cavities are distributed in the negative pressure collection area.

[0009] As another optimized solution for the negative pressure acquisition head, the included angle of the tip 703 formed by the horizontal plate 702 and the inclined plate 701 is 15°.

[0010] As another optimization of the aforementioned negative pressure acquisition head, the curvature of the arc plate 704 gradually increases from 1 / 90 at the top to 1 / 30.

[0011] A non-contact labyrinth sealing structure includes a sealing body and several sealing teeth, with a sealing cavity formed between adjacent sealing teeth. A sealing gap is formed between the inner wall of the through hole of the sealing tooth and the shaft on which it is installed. The sealing body is provided with a suction hole that connects the sealing cavity and the outside. The suction hole is connected to the negative pressure collection area of ​​the negative pressure collection head through an air pipe to balance the pressure on both sides of the sealing body along the axis.

[0012] As an optimized solution for the aforementioned non-contact labyrinth sealing structure, the suction port is connected to an external air pressure source via an air pipe.

[0013] As another optimized solution for the aforementioned non-contact labyrinth sealing structure, the upper surface of the negative pressure collection head is connected to the air tube via a fixed tube.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1) The negative pressure sampling head of the present invention, by designing an arc-shaped windward surface, forms a negative pressure sampling area at the bottom of the arc-shaped windward surface, making full use of the airflow generated when the shaft rotates inside the gearbox or transmission box, forming a negative pressure area inside the gearbox or transmission box, and then using this negative pressure area to balance the air pressure inside and outside the non-contact labyrinth seal, ultimately solving the problem of preventing leakage of the non-contact labyrinth seal.

[0016] 2) The non-contact labyrinth seal of the present invention prevents leakage by setting a suction hole on the sealing body that connects the sealing cavity and the outside, and then using the suction hole to connect to a negative pressure air source or a negative pressure sampling head. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the non-contact labyrinth seal of the present invention;

[0018] Figure 2 for Figure 1 A side view diagram;

[0019] Figure 3 for Figure 1 A diagram illustrating the connection of the trachea;

[0020] Figure 4 for Figure 1 A schematic diagram of connecting the negative pressure sampling head;

[0021] Figure 5 This is a schematic diagram of the negative pressure acquisition head.

[0022] Figure 6 A schematic diagram illustrating the negative pressure acquisition zone generated by the interaction between the negative pressure acquisition head and the shaft.

[0023] Figure 7 The pressure cloud map of negative pressure acquisition head 7 under simulated conditions (0 corresponds to standard atmospheric pressure);

[0024] Figure 8 This is a velocity contour plot of negative pressure acquisition head 7 under simulated conditions;

[0025] Figure 9 The graph shows the variation of the minimum negative pressure of negative pressure sensor 7 with airflow velocity.

[0026] Reference numerals: 1. Sealing body; 101. Suction hole; 2. Sealing tooth; 201. Through-shaft hole; 3. Shaft; 4. Sealing cavity; 5. Sealing gap; 6. Air tube; 7. Negative pressure collection head; 701. Inclined plate; 702. Horizontal plate; 703. Tip; 704. Arc plate; 705. Cavity; 706. Negative pressure collection area; 707. Fixed tube. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not described in the following embodiments of the present invention should be understood as technologies well known to those skilled in the art, such as the structure of gearboxes and transmission boxes, the installation position and installation method of non-contact labyrinth seals, etc.

[0028] Example 1

[0029] A negative pressure sampling head, such as Figure 5As shown, the negative pressure sampling head 7 is a triangular prism, with one side opposite to one of its edges being arc-shaped, thus forming an arc-shaped windward surface perpendicular to the airflow. At this time, the upper side connected to the arc-shaped side is in a horizontal state, and the lower side connected to the arc-shaped side is in an upward tilting state, thereby forming a negative pressure sampling area 706 at the bottom of the arc-shaped windward surface.

[0030] In this embodiment, the upper and lower sides refer to the higher and lower sides, respectively, when the curved windward surface is in perpendicular contact with the airflow and is considered to be in a horizontal state.

[0031] The above are basic embodiments of the present invention. Further improvements, optimizations, and limitations can be made based on the above to obtain the following embodiments:

[0032] Example 2

[0033] This embodiment is a further limitation based on embodiment 1. Its main structure is the same as that of embodiment 1. The further limitation is that the curvature of the arc-shaped windward surface gradually increases from top to bottom, thereby forming a negative pressure collection area 706 at the connection between the section with relatively large curvature at the bottom and the upwardly inclined lower side.

[0034] Example 3

[0035] This embodiment is a further limitation based on Embodiment 1. Its main structure is the same as that of Embodiment 1. The further limitation is that the negative pressure collection head 7 is a hollow plate-shaped part with a certain thickness, which is finally formed into a triangular prism shape. The upper surface of the plate-shaped part is horizontal, and the lower surface is an upward sloping surface, thus forming a tip 703 on one side. The side opposite to the tip 703 is an arc-shaped windward surface with a curvature that gradually increases from top to bottom. The area near the lower surface at the bottom of the arc-shaped windward surface forms a negative pressure collection area 706. Several air holes connected to the internal cavity 705 of the plate-shaped part are distributed on the negative pressure collection area 706. The negative pressure collection head 7 is located on one side of the shaft 3. Here, the shaft 3 refers to the output shaft or input shaft of the gearbox or transmission box, that is, the shaft that passes through the center of the non-contact labyrinth seal. The tangent of the arc-shaped windward surface is perpendicular to the rotation direction of the shaft 3, so that the airflow generated by the high-speed rotation of the shaft 3 forms a negative pressure collection area 706 at the bottom of the arc-shaped windward surface.

[0036] Example 4

[0037] This embodiment is a further limitation based on embodiment 1. Its main structure is the same as that of embodiment 1. The further limitation is that the negative pressure collection head 7 is a cavity 705 formed by a horizontal plate 702, an inclined plate 701, an arc plate 704 and two vertical sealing plates. One side of the inclined plate 701 is connected to one side of the horizontal plate 702 to form a tip 703. The other sides of the inclined plate 701 and the horizontal plate 702 are respectively connected to the arc plate 704 to form a triangular cavity with openings on both sides. The two vertical sealing plates close the triangular cavity.

[0038] Example 5

[0039] This embodiment is a further limitation based on embodiment 4. Its main structure is the same as that of embodiment 4. The further limitation is that the curvature of the arc plate 704 gradually increases from the side connected to the horizontal plate 702 to the side connected to the inclined plate 701. The arc plate 704 is perpendicular to the tangent of the rotation direction of the shaft 3, so that the airflow generated by the high-speed rotation of the shaft 3 impacts the surface of the arc plate 704 and forms a negative pressure collection area 706 in the junction area of ​​the arc plate 704 and the inclined plate 701. Several air holes with connecting cavities 705 are distributed on the negative pressure collection area 706.

[0040] Example 6

[0041] This embodiment is a further limitation based on embodiment 4. Its main structure is the same as that of embodiment 4. The further limitation is that the included angle between the tip 703 formed by the horizontal plate 702 and the inclined plate 701 is 15°.

[0042] Example 7

[0043] This embodiment is a further limitation based on embodiment 4. Its main structure is the same as that of embodiment 4. The further limitation is that the curvature of the arc plate 704 gradually increases from 1 / 90 at the top to 1 / 30.

[0044] The idea behind this invention, which utilizes the negative pressure acquisition head 7 to generate negative pressure within a gearbox or transmission box, is as follows:

[0045] High-speed gearboxes operate at high speeds, resulting in high gear pitch circular velocity. The lubricating oil inside the gearbox is agitated by the gears, splashing and forming an oil-air mixture. This mixture permeates the gearbox, creating a highly complex flow field and resulting in localized negative and high-pressure areas. Due to the high gear pitch circular velocity, the oil-air mixture at the gear tips also exhibits a high velocity due to the high-speed rotation and agitation of the gears.

[0046] According to the basic principles of fluid mechanics, when a fluid flows over a solid surface, it generates pressure on that surface. Based on Bernoulli's equation (as shown below), which describes the relationship between pressure, density, and velocity, we know that the faster the flow, the lower the pressure, and vice versa.

[0047]

[0048] In the formula, p, ρ, and v are the pressure, density, and velocity of the fluid, respectively; h is the vertical height; g is the acceleration due to gravity; and c is a constant.

[0049] Based on this, the present invention designs a negative pressure sampling head 7. When the high-speed airflow in the gearbox passes through the surface of the negative pressure sampling head 7, a negative pressure area is formed at the bottom of the arc-shaped windward surface. The upper surface is connected to a non-contact labyrinth seal cavity through an air pipe.

[0050] To verify the effectiveness of the negative pressure sampling head 7, a simulation analysis was performed. A two-dimensional model was created using simulation software, neglecting material deformation, and the negative pressure sampling head 7 was placed in a stable flow field with a certain velocity. Boundary conditions were simplified, assuming the entire flow field computational domain to be a stable laminar flow. The wall of the negative pressure sampling head 7 was a regular wall, and a triangular structured mesh was used to directly mesh the wall region. A standard turbulence model was used for simulation calculations. The air surrounding the negative pressure sampling head 7 was set as an ideal gas with a pressure of standard atmospheric pressure and flow velocities of 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 m / s. Simulation analysis software was used to simulate the negative pressure sampling head 7 according to the boundary conditions and governing equations, thereby obtaining the pressure contour map of the negative pressure sampling head 7 (e.g., ...). Figure 7 As shown in the figure, 0 corresponds to standard atmospheric pressure) and velocity contour plot (as shown in the figure). Figure 8 (As shown).

[0051] Figure 7 The image shows the pressure cloud map of the negative pressure sampling head 7 when the airflow velocity is 70 m / s. Figure 7 It can be seen that the pressure on the upper surface of the negative pressure sampling head 7 is relatively stable with small variations. The area with the greatest curvature on the lower surface of the negative pressure sampling head 7 forms a negative pressure region. The area of ​​the negative pressure sampling head 7 facing the airflow direction forms a positive pressure region.

[0052] Figure 8 A velocity contour plot of the negative pressure sampling head 7 at an airflow velocity of 70 m / s is presented. The plot shows that the airflow velocity on the upper surface of the negative pressure sampling head 7 is relatively stable and low. The airflow velocity on the lower surface of the negative pressure sampling head 7 is higher, forming a high-speed region in the area of ​​greatest curvature on the lower surface, reaching a maximum velocity of 200 m / s. This is because the different radii of curvature on the lower surface of the negative pressure sampling head 7 cause changes in airflow velocity, resulting in a negative pressure region on the lower surface according to Bernoulli's principle.

[0053] Changing the airflow velocity causes a corresponding change in pressure on the surface of the negative pressure sampling head 7. The table below shows the minimum pressure data for the negative pressure sampling head 7 under different airflow velocities. Based on the table, a graph illustrating the pressure variation of the negative pressure sampling head 7 under different airflow velocities is plotted. Figure 9 As shown, it can be seen that the amount of negative pressure that can be collected by the lower surface of the negative pressure sampling head 7 gradually decreases as the airflow velocity increases.

[0054] Pressure data table in airflow at different speeds

[0055]

[0056] Example 8

[0057] A non-contact labyrinth sealing structure, such as Figure 1 As shown, it includes a sealing body 1 and several sealing teeth 2. Figure 1 The diagram shows three sealing teeth 2 and two sealing cavities 4 (the actual number depends on the needs). The sealing body 1 is annular, and the sealing teeth 2 are arranged axially at intervals along the inner wall of the sealing body 1. Figure 1 The three sealing teeth 2 shown are merely an example. In practice, the number of sealing teeth 2 should be appropriately selected based on the axial length of the sealing body 1. The sealing teeth 2 are also annular and coaxial with the sealing body 1. The center of each sealing tooth 2 has a through-hole 201 for mounting the shaft 3, and a sealing cavity 4 is formed between adjacent sealing teeth 2. Because it is a non-contact labyrinth seal, a sealing gap 5 is formed between the inner wall of the through-hole 201 of the sealing tooth 2 and the mounted shaft 3. Figure 2 and 3 As shown, the sealing body 1 is provided with a suction hole 101 that connects the sealing cavity 4 and the outside. The suction hole 101 is connected to the negative pressure collection area 706 of the negative pressure collection head 7 through the air pipe 6 to balance the pressure on both sides of the sealing body 1 in the axial direction.

[0058] In this embodiment, the pressure inside the non-contact labyrinth seal is greater than the pressure outside, and the pressure outside is greater than the pressure at the suction hole 101. Under the action of the pressure difference, the airflow inside the seal (inside the gearbox or transmission box) flows into the sealing cavity 4 inside the non-contact labyrinth seal through the sealing gap 5. The airflow outside the seal also flows into the sealing cavity 4 inside the non-contact labyrinth seal through the sealing gap 5. The airflow flowing in from both sides eventually flows out from the suction hole 101, thus avoiding the leakage problem on the outside of the seal.

[0059] In this embodiment, the sealing teeth 2 are arranged sequentially in the circular hole channel inside the sealing body 1. An oil slinger ring can be set between two sealing teeth 2, or it can be omitted. The sealing body 1, sealing teeth 2 and shaft 3 are installed coaxially.

[0060] Example 9

[0061] This embodiment is a further limitation based on embodiment 8. Its main structure is the same as that of embodiment 8. The further limitation is that the suction hole 101 is connected to an external air pressure source through the air pipe 6. The external air pressure source is generally a negative pressure air source, such as a negative pressure exhaust fan. Moreover, the negative pressure generated by the negative pressure air source must ensure the following conditions: the pressure inside the non-contact labyrinth seal is greater than the pressure outside, and the pressure outside is greater than the pressure of the negative pressure air source at the suction hole 101.

[0062] Example 10

[0063] This embodiment is a further limitation based on embodiment 8. Its main structure is the same as that of embodiment 8, but the further limitation is as follows: Figure 4 , 5 As shown in Figure 6, the upper surface of the negative pressure sampling head 7 is connected to the air pipe 6 through a fixing tube 707. The fixing tube 707 generally has a certain strength, and its purpose is to fix it to the outer shell of the transmission box or gear box, thereby fixing the negative pressure sampling head 7 to one side of the shaft 3.

Claims

1. A negative pressure sampling head, characterized in that: The negative pressure sampling head (7) is a hollow plate-shaped component with a cavity (705) formed by a horizontal plate (702), an inclined plate (701), an arc-shaped plate (704), and two vertical sealing plates. The horizontal plate (702), the inclined plate (701), and the arc-shaped plate (704) form a triangular cavity with openings on both sides. The two vertical sealing plates close the triangular cavity. The upper surface of the hollow plate-shaped component is a horizontal plate (702), and the lower surface is an inclined plate (701) with an inclined slope. One side of the inclined plate (701) is connected to one side of the horizontal plate (702), thereby forming a pointed part (703) on one side. The inclined plate (701) and the horizontal plate (702) The other side of the arc is connected to the arc plate (704), so that the arc plate (704) is on the side opposite to the tip (703) and forms an arc-shaped windward surface with gradually increasing curvature from top to bottom. The arc-shaped windward surface is perpendicular to the airflow. The area near the lower surface of the bottom of the arc-shaped windward surface forms a negative pressure collection area (706). Several air holes connecting the internal cavity (705) of the plate-shaped component are distributed on the negative pressure collection area (706). The negative pressure collection head (7) is located on one side of the shaft (3), and the arc-shaped windward surface is perpendicular to the tangent of the rotation direction of the shaft (3), so that the airflow formed by the high-speed rotation of the shaft (3) forms a negative pressure collection area (706) at the bottom of the arc-shaped windward surface.

2. The negative pressure acquisition head according to claim 1, characterized in that: The curvature of the arc plate (704) gradually increases from the side connected to the horizontal plate (702) to the side connected to the inclined plate (701). The arc plate (704) is perpendicular to the tangent of the rotation direction of the shaft (3), so that the airflow generated by the high-speed rotation of the shaft (3) impacts the surface of the arc plate (704) and forms a negative pressure collection area (706) at the junction of the arc plate (704) and the inclined plate (701).

3. The negative pressure acquisition head according to claim 1, characterized in that: The included angle between the tip (703) formed by the horizontal plate (702) and the inclined plate (701) is 15°.

4. The negative pressure acquisition head according to claim 1, characterized in that: The curvature of the arc plate (704) gradually increases from 1 / 90 at the top to 1 / 30.

5. A non-contact labyrinth seal structure, comprising a sealing body (1) and a plurality of sealing teeth (2), wherein a sealing cavity (4) is formed between adjacent sealing teeth (2), and a sealing gap (5) is formed between the inner wall of the through hole (201) of the sealing teeth (2) and the installed shaft (3), characterized in that: The sealing body (1) is provided with a suction hole (101) that connects the sealing cavity (4) and the outside. The suction hole (101) is connected to the negative pressure collection area (706) of the negative pressure collection head (7) of any one of claims 1-4 through the air pipe (6) to balance the pressure on both sides of the sealing body (1) in the axial direction.

6. The non-contact labyrinth sealing structure according to claim 5, characterized in that: The suction port (101) is connected to an external air pressure source through the air pipe (6).

7. The non-contact labyrinth sealing structure according to claim 5, characterized in that: The upper surface of the negative pressure collection head (7) is connected to the air tube (6) through a fixed tube (707).

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