Labyrinth piston for reducing heat mixing for mine cooling system
By using labyrinth pistons in the mine cooling system, the problems of fluid thermal mixing and jamming were solved, the cooling efficiency and device stability were improved, safety hazards were avoided, and safe and stable pressure energy conversion was achieved.
Patent Information
- Application Number
- CN202422899773.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-27
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2034-11-27
AI Technical Summary
The mine suffers from severe heat damage. Existing pressure exchange cylinders have severe fluid thermal mixing, leading to reduced cooling efficiency or unstable operation of the equipment. Furthermore, the physical piston is prone to jamming, posing a safety hazard.
The labyrinth piston is used, and by setting arc-shaped protrusions and staggered flow channels on the piston body, axial isolation of the fluid is achieved and thermal mixing is reduced, jamming is avoided, and the maintenance-free period of the device is increased.
It effectively reduces the heat mixing process, improves the cooling efficiency, reduces the frequency of valve switching, avoids the risk of piston jamming and pressure buildup, and ensures the safe and stable operation of the unit.
Smart Images
Figure CN223648189U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of mine cooling technology, specifically, it relates to a piston for a mine cooling system. Background Technology
[0002] With the increasing depth of coal mining, the problem of heat hazards in mines is becoming increasingly serious. Ground-based centralized cooling systems, as a key technology for preventing and controlling heat hazards in mines, are widely used. This system involves fluids of different pressures and temperatures, requiring the conversion of high-pressure cold water (e.g., 3°C) to low-pressure cold water and low-pressure warm water (e.g., 18°C) to high-pressure warm water. Generally, a valve-controlled pressure energy conversion device is used, which mainly consists of a pressure exchange cylinder and switching valve groups and check valve groups at both ends.
[0003] The pressure exchange cylinder is the primary location for pressure conversion. Currently, most pressure exchange cylinders lack a physical piston, meaning the two fluids are in direct contact for pressure transfer. However, a temperature difference exists between the two fluids, leading to heat transfer and the presence of fluids with temperatures between 3°C and 18°C – a process known as thermal mixing. This thermal mixing process, without piston isolation, is quite severe. To control the chilled water outlet temperature rise, measures such as reducing the flow rate, increasing valve switching frequency, or altering the flow equivalence of the two fluids are necessary. These methods can reduce system cooling efficiency or shorten system lifespan. Conversely, using a physical piston to completely isolate the two fluids and only transfer pressure also presents problems. For example, the piston may become stuck within the pressure exchange cylinder. If stuck, it can cause abnormal fluid flow, posing a risk of pressure buildup, damage to the device structure, and affecting the safe and stable operation of the entire system. Utility Model Content
[0004] This utility model aims to provide a labyrinth piston for use as a pressure energy conversion device in a mine cooling system. Installed in a pressure exchange cylinder, it effectively reduces the thermal mixing process of fluids at different temperatures, improves the cooling efficiency of the device, reduces the frequency of valve switching, and increases the maintenance-free period of the device. At the same time, multiple strategies avoid potential risks such as piston jamming, impact, and fluid pressure buildup, which is conducive to the safe and stable operation of the device.
[0005] To solve the above-mentioned technical problems, this utility model is achieved through the following technical solution:
[0006] This utility model provides a labyrinth piston for reducing heat mixing in a mine cooling system, which is installed inside a pressure exchange cylinder; it includes a piston body; a central flow plate and an outer circulation plate are respectively installed at both ends of the piston body;
[0007] The piston body has an axially penetrating cavity inside. The outer rotating surface of the piston body is provided with several circumferentially distributed arc-shaped protrusions, each extending axially. The outermost edges of all the arc-shaped protrusions are located on the same cylindrical surface, and the outer diameter of this cylindrical surface is smaller than the inner diameter of the pressure exchange cylinder. This allows the labyrinth piston to move axially in a suspended state within the pressure exchange cylinder without overturning. A row of connecting holes is provided between adjacent arc-shaped protrusions in the piston body, with several connecting holes in each row spaced apart axially along the piston body. These connecting holes connect the axially penetrating cavity inside the piston body with the gap between the labyrinth piston and the pressure exchange cylinder.
[0008] The central flow plate is a circular plate with a central flow area, which is a through-hole portion in the center of the circular plate; the radial cross-section of the central flow area is smaller than the radial cross-section of the axial through-hole of the piston body.
[0009] The outer circulation plate is a circular plate with an outer circulation area, which is a segmented and continuous part of the circular plate. The radial distance between the outer circulation area and the outer periphery of the outer circulation plate is less than the radial distance between the outer circulation area and the central axis of the outer circulation plate. The inner diameter of the outer circulation area is greater than the diameter of the central circulation area of the central flow plate and less than the diameter of the axial through cavity of the piston body.
[0010] The central flow plate and the outer annular flow plate are connected to both ends of the piston body by a number of circumferentially distributed connecting bolts, and the central flow plate is fixed to the piston body and the outer annular flow plate is fixed to the piston body by pins.
[0011] The central flow plate is used to enable fluid to flow axially from its center, and the outer circulation plate is used to enable fluid to flow axially from its outer ring. An interleaved flow channel is formed between the central flow plate and the outer circulation plate.
[0012] Furthermore, the piston body is also provided with a central flow plate and an outer circulation plate, and the central flow plate and the outer circulation plate at the end and inside are arranged alternately.
[0013] Furthermore, the outer diameters of the internal central flow plate and the outer annular flow plate are smaller than the diameter of the axial through cavity of the piston body, and they are fixed by a shoulder and nut provided in the middle of the connecting bolt.
[0014] Furthermore, a first groove and a second groove are respectively provided at both axial ends of the piston body. The diameters formed by the first groove and the second groove are both smaller than the outer diameter of the piston body and larger than the diameter of the axial through cavity. The first groove is used to limit the installation of the central flow plate at the end, and the pin is installed on the opposite end face of the central flow plate at the end and the first groove. The second groove is used to limit the installation of the outer flow plate at the end, and the pin is installed on the opposite end face of the outer flow plate at the end and the second groove.
[0015] Furthermore, the axial ends of the arc-shaped protrusion of the piston body are respectively provided with rounded edges.
[0016] Furthermore, the outermost edge of a portion of the arcuate protrusion in the piston body forms line contact with the inner wall of the pressure exchange cylinder.
[0017] Furthermore, the several connecting holes in each row are arranged at equal intervals along the axial direction of the piston body.
[0018] Furthermore, the annular segmented through portion of the outer ring flow area is a ring opening separated by several stiffeners, and the stiffeners are evenly distributed circumferentially on the circular body of the outer ring flow plate.
[0019] Furthermore, buffer rings are respectively installed between the central flow plate at the end and the piston body, and between the outer annular flow plate at the end and the piston body. The buffer rings are formed by an inner ring portion and an outer ring portion forming a right-angled cross section. The two buffer rings are symmetrical to each other and are respectively disposed in the outer circumferential grooves of the central flow plate at the end and the outer annular flow plate at the end. A part of the outer circumferential groove is located inside the piston body and another part is located outside the piston body, so that the inner ring portion of the buffer ring is fixed while its outer ring portion is pressed against the end face of the piston body.
[0020] Furthermore, a position sensor is installed on the labyrinth piston.
[0021] The beneficial effects of this utility model are:
[0022] The mine cooling system of this utility model uses a labyrinth piston to reduce thermal mixing, which can effectively reduce the thermal mixing process of fluids at different temperatures, improve the cooling efficiency of the device, reduce the frequency of valve switching, and increase the maintenance-free period of the device. At the same time, multiple strategies avoid potential risks such as piston jamming, impact and fluid pressure buildup, which is conducive to the safe and stable operation of the device. Attached Figure Description
[0023] Figure 1 This is a cross-sectional view of the labyrinth piston of this utility model located in the middle of the pressure exchange cylinder.
[0024] Figure 2This is a cross-sectional schematic diagram of the labyrinth piston of this utility model at its extreme position inside the pressure exchange cylinder.
[0025] Figure 3 This is a cross-sectional schematic diagram of the labyrinth piston of this utility model;
[0026] Figure 4 The following are (a) a three-dimensional schematic diagram, (b) an axial cross-sectional schematic diagram, and (c) a radial cross-sectional schematic diagram of the piston body in the labyrinth piston of this utility model.
[0027] Figure 5 These are (a) a front view and (b) a cross-sectional view (A-A) of the central flow plate of the labyrinth piston of this utility model.
[0028] Figure 6 Here are (a) front view and (b) B-B sectional view of the outer annulus plate of the labyrinth piston of this utility model.
[0029] Figure 7 This is a schematic diagram of the fluid flow channel formed by the central flow plate and the outer annular flow plate of the labyrinth piston of this utility model; wherein, (a) is a pair of baffles, and (b) is multiple pairs of baffles.
[0030] In the above figure: 1: Labyrinth piston; 11: Central flow plate; 111: Central flow area; 12: Piston body; 121: First groove; 122: Second groove; 123: Arc-shaped protrusion; 124: Flow hole; 13: Outer annular flow plate; 131: Outer annular flow area; 14: Connecting bolt; 15: Buffer ring; 2: Pressure exchange cylinder; 3: First flange; 4: Second flange. Detailed Implementation
[0031] The present invention will be further described in detail below through specific embodiments. These embodiments will enable those skilled in the art to have a more comprehensive understanding of the present invention, but will not limit the present invention in any way.
[0032] like Figure 1 and Figure 2 As shown, the labyrinth piston 1 is installed inside the pressure exchange cylinder 2 of the pressure energy conversion device and can reciprocate along the axial direction of the pressure exchange cylinder 2. Both ends of the pressure exchange cylinder 2 are connected to a second flange 4 via a first flange 3. Generally, the first flange 3 is welded to the pressure exchange cylinder 2, and the second flange 4 is connected to the first flange 3 by circumferentially distributed bolts. The inner diameter of the first flange 3 is the same as the inner diameter of the pressure exchange cylinder 2, so the labyrinth piston 1 can also move axially within the first flange 3. The inner diameter of the second flange 4 is smaller than the inner diameter of the first flange 3, which limits the axial movement of the labyrinth piston 1 and is used to connect other components of the pressure energy conversion device.
[0033] In addition, the inner diameter of the second flange 4 can also be the same as that of the first flange 3. In this case, in order to limit the extreme position of the labyrinth piston 1, a groove needs to be provided on the mating surface of the first flange 3 and the second flange 4, and a retaining ring needs to be provided in the groove. The inner diameter of the retaining ring is smaller than that of the first flange 3, which serves to limit the axial position of the labyrinth piston 1.
[0034] like Figure 3 As shown, the labyrinth piston 1 is mainly composed of a piston body 12 and at least a pair of central flow plates 11 and outer flow plates 13, with the central flow plates 11 and outer flow plates 13 arranged alternately.
[0035] In one embodiment of the present invention, the labyrinth piston 1 includes a pair of central flow plates 11 and outer annular flow plates 13, which are respectively installed at both ends of the piston body 12.
[0036] In other embodiments of the present invention, the labyrinth piston 1 includes at least two pairs of central flow plates 11 and outer circulation plates 13. In addition to the central flow plates 11 and outer circulation plates 13 installed at both ends of the piston body 12, the piston body 12 is also provided with central flow plates 11 and outer circulation plates 13.
[0037] like Figure 4 As shown in (a), (b), and (c), the piston body 12 has a cylindrical main structure with an axially penetrating cylindrical cavity inside. The radial cross-section of the axially penetrating cavity is a regular circle. The outer rotating surface of the piston body 12 is provided with several circumferentially distributed arc-shaped protrusions 123, each extending axially. Therefore, the outer radial cross-section of the piston body 12 is an irregular arc. The outermost edges of the arc-shaped protrusions 123 are located on the same cylindrical surface. The outer diameter of this cylindrical surface is slightly smaller than the inner diameter of the pressure exchange cylinder 2, allowing the labyrinth piston 1 to move axially in a suspended state inside the pressure exchange cylinder 2 without overturning. In other words, the labyrinth piston 1 can also move radially within a small range inside the pressure exchange cylinder 2. At this time, only the outermost edges of some of the arc-shaped protrusions 123 of the piston body 12 form line contact with the inner wall of the pressure exchange cylinder 2, thereby reducing the contact area, lowering the frictional resistance of the axial reciprocating motion of the labyrinth piston 1, and preventing jamming.
[0038] The piston body 12 has a row of connecting holes 124 between adjacent arc-shaped protrusions 123. The number of rows of connecting holes 124 is equal to the number of arc-shaped protrusions 123, so each row of connecting holes 124 is also evenly distributed around the circumference of the piston body 12. Furthermore, several connecting holes 124 in each row are arranged in a straight line at intervals along the axial direction of the piston body 12, preferably at equal intervals. The connecting holes 124 allow the fluid in the axial through-cavity of the piston body 12 to communicate with the fluid in the gap between the labyrinth piston 1 and the pressure exchange cylinder 2. This has the effect of evenly distributing the fluid around the circumference, enhancing the central suspension of the labyrinth piston 1 within the pressure exchange cylinder 2, and also preventing jamming.
[0039] Furthermore, the two ends of the arc-shaped protrusion 123 are respectively rounded to prevent the labyrinth piston 1 from getting stuck when passing through the gap between the flanges during its axial reciprocating motion.
[0040] A first groove 121 and a second groove 122 are respectively provided at both axial ends of the piston body 12. The diameters formed by the first groove 121 and the second groove 122 are both larger than the diameter of the axial through cavity of the piston body 12. The first groove 121 is used to limit the installation of the central flow plate 11 at the end, so the outer diameter of the central flow plate 11 matches the diameter of the first groove 121. The second groove 122 is used to limit the installation of the outer annular flow plate 13 at the end, so the outer diameter of the outer annular flow plate 13 matches the diameter of the second groove 122. The central flow plate 11 and the outer annular flow plate 13 at the end are connected to each other by a plurality of circumferentially distributed connecting bolts 14, so that the central flow plate 11 and the outer annular flow plate 13 are respectively fixed to both ends of the piston body 12.
[0041] like Figure 5 As shown in (a) and (b), the central flow plate 11 is a circular plate structure with a central flow area 111, which is a through-hole portion in the center of the circular plate structure. The central flow plate 11 is used to allow fluid to flow axially from its center and to form staggered flow channels with the outer annular flow plate 13 to increase flow resistance. The radial cross-section of the central flow area 111 is generally circular, and its diameter is smaller than the diameter of the axial through-hole of the piston body 12, so as to change the direction of fluid flow. The outer diameter of the central flow plate 11 at the end is smaller than the outer diameter of the piston body 12 and matches the diameter of the first groove 121 of the piston body 12 so as to limit its installation in the first groove 121; the central flow plate 11 is provided with a plurality of bolt holes evenly distributed along the same circle for the installation of connecting bolts 14. In addition to being fixed by connecting bolts 14, the central flow plate 11 at the end is also fixed to the piston body 12 by pins. At least one pin is installed on the opposite end face of the central flow plate 11 and the first groove 121 to restrict the circumferential rotation of the central flow plate 11. The outer diameter of the internal central flow plate 11 is smaller than the diameter of the axial through cavity of the piston body 12. The central flow plate 11 is fixed by a shoulder and nut added in the middle of the connecting bolts 14.
[0042] like Figure 6As shown in (a) and (b), the outer annular flow plate 13 is a circular plate structure with an outer annular flow area 131, which is a segmented, continuous section formed within the circular plate structure. The outer annular flow area 131 is closer to the outer periphery of the outer annular flow plate 13, meaning the radial distance between the outer annular flow area 131 and the outer periphery of the outer annular flow plate 13 is less than its radial distance from the central axis of the outer annular flow plate 13. The outer annular flow plate 13 is used to allow fluid to flow axially from its outer ring and to form staggered flow channels with the central flow plate 11, thereby increasing flow resistance. The segmented, continuous section of the outer annular flow area 131 consists of annular openings separated by several ribs; these ribs are evenly distributed circumferentially to ensure the integrity of the outer annular flow plate 13. The inner diameter of the outer annular flow area 131 is larger than the diameter of the central flow area 111 of the central flow plate 11 and smaller than the diameter of the axially continuous cavity of the piston body 12, thus changing the direction of fluid flow. Generally, the outer diameter of the outer annular flow area 131 is the same as the diameter of the axial through cavity of the piston body 12. The outer diameter of the end outer annular plate 13 is smaller than the outer diameter of the piston body 12 and matches the diameter of the second groove 122 of the piston body 12, so as to limit its installation in the second groove 122; the outer annular plate 13 preferably has several bolt holes evenly distributed along the same circle at the location of each rib for the installation of connecting bolts 14. In addition to being fixed by connecting bolts 14, the end outer annular plate 13 and the piston body 12 are also fixed by pins, with at least one pin installed on the opposite end face of the outer annular plate 13 and the second groove 122 to limit the circumferential rotation of the outer annular plate 13. The outer diameter of the inner outer annular plate 13 is smaller than the diameter of the axial through cavity of the piston body 12, and the outer annular plate 13 is fixed by a shoulder and nut added to the middle of the connecting bolt 14.
[0043] Buffer rings 15 are installed between the central flow plate 11 and the piston body 12 at the end, and between the outer annular flow plate 13 and the piston body 12 at the end. Both buffer rings 15 have a right-angled cross-section formed by an inner ring and an outer ring. The two buffer rings 15 are symmetrically positioned within the outer circumferential grooves of the central flow plate 11 and the outer annular flow plate 13 at the end, respectively. A portion of these outer circumferential grooves is located inside the piston body 12, while another portion is located outside the piston body 12, thus fixing the inner ring of the buffer ring 15 while pressing its outer ring against the end face of the piston body 12. The buffer rings 15 are made of a soft material, such as rubber, and serve to buffer the piston when it moves to its limit position within the pressure exchange cylinder 2, preventing damage from direct impact.
[0044] Compared to ordinary solid pistons, the labyrinth piston 1 has a complex internal fluid flow channel. This avoids the drawbacks of complete fluid isolation at both ends of a solid piston, which could lead to safety hazards such as pressure buildup, and also prevents the two fluid streams from directly contacting and mixing axially, effectively reducing the thermal mixing process. Therefore, a complex fluid flow channel is constructed through the piston body 12 and its two ends, namely the central flow plate 11 and the outer annular flow plate 13. Figure 7 The complex fluid flow channel shown in (a) (only one flow direction is shown in the figure, but the reverse direction is also possible) requires the fluid to change its flow direction when flowing through this channel, increasing the axial flow resistance. This facilitates the synchronous axial movement of the labyrinth piston 1 with the fluid, reducing the heat transfer process caused by macroscopic mixing of the fluid; this is the meaning of the "labyrinth" piston. A central flow plate 11 and an outer annular flow plate 13 are added inside the labyrinth piston 1, as shown... Figure 7 As shown in (b) (only one flow direction is shown in the figure, but the reverse direction is also possible), the flow resistance of the fluid through this axial flow channel can be further increased.
[0045] During normal operation, the fluid pushes the labyrinth piston 1 to move synchronously along the axial direction of the pressure exchange cylinder 2. The thermal mixing between the two fluids at different temperatures is limited to heat conduction caused by the direct and limited contact between the inner cavity and outer periphery of the labyrinth piston 1 and the fluid in the gaps within the pressure exchange cylinder 2. The heat transfer process is greatly weakened, effectively reducing the thermal mixing process. When the labyrinth piston 1 is about to reach its limit position, the device will switch the valve during the execution of the normal control strategy to change the fluid flow direction in time. Therefore, the labyrinth piston 1 will also move in the opposite axial direction, repeating the cycle within the pressure exchange cylinder 2. However, when the device is in an abnormal operating state for some reason, even after the labyrinth piston 1 reaches its limit position, the valve has not switched, and the fluid flow direction has not changed. The fluid will flow through the inner cavity of the labyrinth piston 1 with greater resistance until the device returns to normal operation, without dangerous phenomena such as flow stoppage or pressure buildup, thus avoiding damage to the device and safety accidents.
[0046] To obtain the real-time position of the labyrinth piston 1 within the pressure exchange cylinder 2, or simply to determine when the labyrinth piston 1 reaches its limit position, a position sensor can be installed on the labyrinth piston 1 to accurately obtain the relative position of the labyrinth piston 1 and the pressure exchange cylinder 2.
[0047] In addition, the outer diameter of the central flow plate 11 or the outer annular flow plate 13 of the labyrinth piston 1 is smaller than the inner diameter of the second flange 4. Therefore, its outer periphery will enter the second flange 4, and the fluid at the outer periphery is forced to flow towards the center, which actually forms a damping structure and can also play a role in preventing impact and buffering.
[0048] The material used to manufacture the labyrinth piston 1 is not unique. Preferably, it is a material with a density lower than that of the fluid medium (usually water) transported inside the pressure exchange cylinder 2. This helps the labyrinth piston 1 to suspend in the fluid medium and avoid jamming. When the labyrinth piston 1 is made entirely of soft material, the buffer ring 15 can be omitted, which also helps to prevent direct impact.
[0049] In the pressure energy conversion device of the mine cooling system, a labyrinth piston 1 is installed inside the pressure exchange cylinder 2. The orderly conversion of fluid flow direction is rationally controlled by the switching action of the valve.
[0050] When the labyrinth piston 1 is at its extreme position at one end of the pressure exchange cylinder 2, the cylinder is filled with low-pressure warm water, which is then converted to high-pressure warm water after a pre-pressurization process. As the valve switches, high-pressure cold water flows into the pressure exchange cylinder 2 from the end where the labyrinth piston 1 is located, and the labyrinth piston 1 moves axially in sync with the fluid flow direction. The high-pressure cold water discharges the high-pressure warm water from the pressure exchange cylinder 2, and the thermal mixing process between the two is relatively weak. This entire process constitutes the pressure conversion process that transforms low-pressure warm water into high-pressure warm water.
[0051] When the labyrinth piston 1 moves to its limit position at the other end of the pressure exchange cylinder 2, the pressure exchange cylinder 2 is filled with high-pressure cold water. After a pre-depressurization process, it is converted to low-pressure cold water. At this time, with the switching of the valve, low-pressure warm water flows into the pressure exchange cylinder 2 from the other end where the labyrinth piston 1 is located. The labyrinth piston 2 moves axially in sync with the fluid flow direction (this direction is opposite to the direction described above). The low-pressure warm water discharges the low-pressure cold water from the pressure exchange cylinder 2, and the thermal mixing process between the two is weak. The entire process described above is the pressure conversion process of converting high-pressure cold water into low-pressure cold water.
[0052] When the labyrinth piston 1 moves to the limit position at one end of the pressure exchange cylinder 2, the device repeats the above process, continuously and orderly carrying out the pressure energy conversion process.
[0053] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many specific modifications under the guidance of the present invention without departing from the spirit of the invention and the scope of protection of the claims, and these modifications all fall within the scope of protection of the present invention.
Claims
1. A labyrinth piston for reducing heat mixing in a mine cooling system, installed inside a pressure exchange cylinder; characterized in that, It includes a piston body; a central flow plate and an outer annular flow plate are respectively installed at both ends of the piston body; The piston body has an axially penetrating cavity inside. The outer rotating surface of the piston body is provided with several circumferentially distributed arc-shaped protrusions, each extending axially. The outermost edges of all the arc-shaped protrusions are located on the same cylindrical surface, and the outer diameter of this cylindrical surface is smaller than the inner diameter of the pressure exchange cylinder. This allows the labyrinth piston to move axially in a suspended state within the pressure exchange cylinder without overturning. A row of connecting holes is provided between adjacent arc-shaped protrusions in the piston body, with several connecting holes in each row spaced apart axially along the piston body. These connecting holes connect the axially penetrating cavity inside the piston body with the gap between the labyrinth piston and the pressure exchange cylinder. The central flow plate is a circular plate with a central flow area, which is a through-hole portion in the center of the circular plate; the radial cross-section of the central flow area is smaller than the radial cross-section of the axial through-hole of the piston body. The outer circulation plate is a circular plate with an outer circulation area, which is a segmented and continuous part of the circular plate. The radial distance between the outer circulation area and the outer periphery of the outer circulation plate is less than the radial distance between the outer circulation area and the central axis of the outer circulation plate. The inner diameter of the outer circulation area is greater than the diameter of the central circulation area of the central flow plate and less than the diameter of the axial through cavity of the piston body. The central flow plate and the outer annular flow plate are connected to both ends of the piston body by a number of circumferentially distributed connecting bolts, and the central flow plate is fixed to the piston body and the outer annular flow plate is fixed to the piston body by pins. The central flow plate is used to enable fluid to flow axially from its center, and the outer circulation plate is used to enable fluid to flow axially from its outer ring. An interleaved flow channel is formed between the central flow plate and the outer circulation plate.
2. The labyrinth piston for reducing heat mixing in a mine cooling system according to claim 1, characterized in that, The piston body is also equipped with a central flow plate and an outer circulation plate, and the central flow plate and the outer circulation plate at the end and inside are arranged alternately.
3. A labyrinth piston for reducing heat mixing in a mine cooling system according to claim 2, characterized in that, The outer diameters of the internal central flow plate and the outer annular flow plate are smaller than the diameter of the axial through cavity of the piston body, and they are fixed by a shoulder and nut provided in the middle of the connecting bolt.
4. A labyrinth piston for reducing heat mixing in a mine cooling system according to any one of claims 1-3, characterized in that, The piston body has a first groove and a second groove at its two axial ends, respectively. The diameters of the first groove and the second groove are both smaller than the outer diameter of the piston body and larger than the diameter of the axial through cavity. The first groove is used to limit the installation of the central flow plate at the end, and the pin is installed on the opposite end face of the central flow plate at the end and the first groove. The second groove is used to limit the installation of the outer flow plate at the end, and the pin is installed on the opposite end face of the outer flow plate at the end and the second groove.
5. A labyrinth piston for reducing heat mixing in a mine cooling system according to any one of claims 1-3, characterized in that, The piston body has rounded ends at both axial ends of the arc-shaped protrusion.
6. A labyrinth piston for reducing heat mixing in a mine cooling system according to any one of claims 1-3, characterized in that, The outermost edge of the arc-shaped protrusion in the piston body forms a line contact with the inner wall of the pressure exchange cylinder.
7. A labyrinth piston for reducing heat mixing in a mine cooling system according to any one of claims 1-3, characterized in that, Several connecting holes in each row are arranged at equal intervals along the axial direction of the piston body.
8. A labyrinth piston for reducing heat mixing in a mine cooling system according to any one of claims 1-3, characterized in that, The annular segmented through-section of the outer ring flow area consists of annular openings separated by several stiffeners, which are evenly distributed circumferentially on the circular body of the outer ring flow plate.
9. A labyrinth piston for reducing heat mixing in a mine cooling system according to any one of claims 1-3, characterized in that, Buffer rings are installed between the central flow plate at the end and the piston body, and between the outer annular flow plate at the end and the piston body, respectively. Each buffer ring has a right-angled cross-section consisting of an inner ring and an outer ring. The two buffer rings are symmetrical to each other and are respectively disposed in the outer circumferential grooves of the central flow plate at the end and the outer annular flow plate at the end. A portion of the outer circumferential groove is located inside the piston body and another portion is located outside the piston body, so that the inner ring of the buffer ring is fixed while its outer ring is pressed against the end face of the piston body.
10. A labyrinth piston for reducing heat mixing in a mine cooling system according to any one of claims 1-3, characterized in that, The labyrinth piston is equipped with a position sensor.