Centrifugal compressor and diffuser interface structure

Abstract

The invention discloses a centrifugal compressor and diffuser interface structure, and relates to the technical field of centrifugal compressors, the centrifugal compressor and diffuser interface structure comprises a diffuser, an impeller rotatably arranged on the axis of the diffuser, and a connecting piece located between the diffuser and the impeller, and a plurality of contact rollers are arranged on the connecting piece in a circumferential array; the connecting piece comprises an outer wall face used for guiding airflow to the diffuser; the inner wall face is opposite to the impeller, and an annular oil way used for containing lubricating oil is defined by the inner wall face and the outer side of the impeller. According to the connector structure of the centrifugal compressor and the diffuser, the flow of lubricating oil is increased in the high-speed rotating state of the impeller, and an oil film with a certain thickness is formed between the impeller and the inner wall face through the lubricating oil, so that the vibration of the impeller is buffered; and when the speed of the impeller is too high, lubricating oil in the supply cavity is squeezed into the annular oil way to be automatically supplemented, and the thickness of an oil film is maintained.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal compressors, and in particular to an interface structure between a centrifugal compressor and a diffuser. Background Art

[0002] The outlet of a centrifugal compressor is usually connected to the inlet of a diffuser, in which the impeller that operates as a rotor is generally coaxially sleeved in the diffuser. As the impeller rotates relative to the diffuser, the high-frequency oscillations generated by the high-speed rotation of the impeller will cause friction with the diffuser. At this time, some lubricating fluid needs to be injected to reduce friction.

[0003] In conjunction with the authorization (announcement) number CN104895807B, the authorization (announcement) date is 2018-04-03, and a centrifugal compressor is disclosed, including: a motor, a support housing, a second transmission shaft and a diffuser. The motor has a motor housing and a first transmission shaft, the portion of the first transmission shaft located in the support housing is covered with a sliding bearing, the portion of the second transmission shaft located in the support housing is covered with a roller bearing, the diffuser includes a diffuser housing, a partition and an impeller, the peripheral wall of the portion of the second transmission shaft extending into the diffuser is formed into a non-circular shape, the central hole of the impeller is formed into a non-circular hole, and a floating seal is provided on the impeller.

[0004] However, in the prior art including the above-mentioned patent, the portion of the second transmission shaft located in the support shell can be covered with two roller bearings in sequence along the length direction. In this way, compared with the existing sliding bearings, the amount of lubricating oil required for the bearings can be effectively reduced. However, the reduction in the amount of lubricating oil reduces the thickness of the oil film, and the roller is prone to further thinning of the oil film under high-speed rotation, affecting the lubrication effect. Summary of the invention

[0005] The object of the present invention is to provide a centrifugal compressor and diffuser interface structure for solving the above-mentioned problems.

[0006] In order to achieve the above-mentioned object, the present invention provides the following technical solutions: a centrifugal compressor and diffuser interface structure, comprising a diffuser and an impeller rotatably arranged on its axis, comprising a connecting piece between the diffuser and the impeller, on which a plurality of contact rollers are arranged in a circumferential array; The connecting piece comprises: Used to guide the airflow toward the outer wall surface of the diffuser; An inner wall surface opposite to the impeller, and the inner wall surface and the outer side of the impeller enclose an annular oil passage for containing lubricating oil; Wherein, the connecting piece has a contracted state that shortens the distance between the inner wall surface and the outer wall surface.

[0007] Preferably, a predetermined gap is maintained between the side surface of the contact roller and the outer side of the impeller, and the contact roller rotates with the impeller so that the lubricating oil forms a vortex.

[0008] Preferably, the device further comprises a stabilizing roller which is rotatably arranged on the connecting member and moves synchronously with the contact roller.

[0009] Preferably, it also includes a sealing ring and a circumferential array fixedly arranged on the impeller, and a memory metal movably arranged in the sealing ring interval, and the angle between the memory metal and the annular oil passage is adjustable.

[0010] Preferably, a cutting blade pointing in the direction of oil flow is fixedly provided on the memory metal.

[0011] Preferably, a folded portion is provided on the inner wall surface of the connecting piece, and the memory metal angle is smallest when the spacing between the folded portions is smallest.

[0012] Preferably, the outer wall surface of the connecting member and the end surface of the impeller are of a stepped structure, and a shift plate is provided on the connecting member.

[0013] Preferably, an arc surface is arranged on the outer wall surface of the connecting member, and a channel with decreasing inner diameter is formed between the arc surface and the shifting plate.

[0014] Preferably, a heat-sensitive block is provided at a first end of the paddle plate close to the diffuser, and a protrusion for guiding condensation is provided at a second end opposite thereto.

[0015] Preferably, the device further comprises a transmission shaft for driving the impeller, on which an adjustment unit for controlling the connecting member is arranged, and the adjustment unit comprises an extension rod which moves radially with temperature changes.

[0016] In the above technical scheme, a centrifugal compressor and diffuser interface structure provided by the present invention has the following beneficial effects: the flow rate of the lubricating oil is increased when the impeller rotates at a high speed, and an oil film with a certain thickness formed between the impeller and the inner wall surface by the lubricating oil has a buffering effect on the oscillation of the impeller, and when the speed of the impeller is too fast, the lubricating oil in the supply chamber is squeezed into the annular oil circuit for automatic replenishment to maintain the thickness of the oil film. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0018] Figure 1 An overall three-dimensional schematic diagram provided for an embodiment of the present invention; Figure 2 A schematic diagram of the overall cross-section structure provided by an embodiment of the present invention; Figure 3 A schematic diagram of the structure of a connecting piece and an adjusting unit provided in an embodiment of the present invention; Figure 4 A schematic diagram of an internal explosion structure provided by an embodiment of the present invention; Figure 5 A schematic diagram of the structure of the pressure diffuser chamber, impeller and transmission shaft provided in an embodiment of the present invention; Figure 6 The embodiment of the present invention provides Figure 3 A schematic diagram of the enlarged structure in the middle; Figure 7 A schematic diagram of the connecting member and contact roller structure provided in an embodiment of the present invention; Figure 8 A schematic diagram of a folding portion and a memory metal structure provided in an embodiment of the present invention; Fig. 9 A schematic diagram of a memory metal structure provided by an embodiment of the present invention; Fig.10 The embodiment of the present invention provides Figure 2 A magnified schematic diagram of structure B in the middle.

[0019] Description of reference numerals: 1. Air inlet; 11. Impeller; 12. Contact roller; 13. Stabilizing roller; 14. Guide groove; 15. Limit block; 16. Drive belt; 2. Diffuser chamber; 21. Diffuser; 22. Sealing ring; 23. Throat; 3. Casing; 4. Cooling channel; 5. Drive shaft; 51. Heat-conducting rod; 52. Sealed chamber; 53. Extension rod; 6. Oil inlet channel; 61. Control chamber; 62. Oil delivery channel; 63. Piston; 64. Spring; 7. Oil outlet channel; 8. Thrust bearing; 9. Connector; 91. Dial plate; 92. Heat-sensitive block; 93. Protrusion; 94. Air port; 95. Arc surface; 96. Supply chamber; 97. Folding part; 98. Memory metal; 981. Cutting disc; 982. Movable plate. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] like Figure 1-Figure 10 As shown, a centrifugal compressor and diffuser interface structure includes a diffuser 21 and an impeller 11 rotatably arranged on its axis, and includes a connecting member 9 located between the diffuser 21 and the impeller 11, on which a plurality of contact rollers 12 are arranged in a circumferential array; The connecting member 9 comprises: Used to guide the airflow toward the outer wall surface of the diffuser 21; An inner wall surface opposite to the impeller 11, wherein the inner wall surface and the outer side of the impeller 11 enclose an annular oil passage for containing lubricating oil; The connecting member 9 has a contracted state that shortens the distance between the inner wall surface and the outer wall surface.

[0022] Specifically, it also includes an air inlet 1 and a diffusion chamber 2 arranged at a corresponding position of the diffuser 21, and the diffusion chamber 2 is connected to a cooling channel 4 to cool the airflow in the diffusion chamber 2. An oil inlet channel 6 and a control chamber 61 connected to the oil inlet channel 6 are provided in the impeller 11, wherein a piston 63 is movably provided in the control chamber 61, and a predetermined distance is maintained between the piston 63 and the port of the oil inlet channel 6 by providing a spring 64.

[0023] Furthermore, Figure 5 The direction shown is used as a reference. During the assembly process, the connecting piece 9 is first assembled in the diffuser 21, and then the impeller 11 is inserted along the connecting piece 9. The direction of inserting the impeller 11 is opposite to the air inlet direction, so that the outer side surface of the impeller 11 is opposite to the inner wall of the connecting piece 9.

[0024] Furthermore, the impeller 11 rotates and sucks gas from the air inlet 1, and the gas is diffused radially by the centrifugal force generated during high-speed rotation. During the diffusion process, the gas enters the diffuser 21 along the outer wall surface of the connector 9. During the rotation of the impeller 11, centrifugal force is generated on the piston 63, so that the piston 63 moves radially and moves away from the port of the oil inlet channel 6, and the spring 64 contracts. As the distance between the piston 63 and the port of the oil inlet channel 6 increases, the flow rate of the lubricating oil increases and enters the annular oil path through the oil delivery channel 62. When the impeller 11 rotates at high speed, it automatically enters the annular oil path. The oil film with a certain thickness formed between the impeller 11 and the inner wall surface by the lubricating oil alleviates the vibration generated by the high-speed rotation of the impeller 11, and the inner wall surface of the connector 9 is flushed by the lubricating oil with centrifugal force, so that the inner wall surface of the connector 9 is close to the outer wall surface. Between the inner wall and the outer wall of the connecting member 9 is a supply cavity 96 containing some lubricating oil. The lubricating oil in the supply cavity 96 is squeezed into the annular oil path for automatic replenishment to maintain the thickness of the oil film.

[0025] In the above technology, the flow rate of the lubricating oil increases when the impeller 11 rotates at a high speed, and an oil film with a certain thickness is formed between the impeller 11 and the inner wall surface by the lubricating oil, which has a buffering effect on the oscillation of the impeller 11. When the speed of the impeller 11 is too fast, the lubricating oil in the supply chamber 96 is squeezed into the annular oil circuit for automatic replenishment to maintain the thickness of the oil film.

[0026] As an embodiment further provided by the present invention, a predetermined gap is maintained between the side surface of the contact roller 12 and the outer side of the impeller 11, and the contact roller 12 rotates with the impeller 11 to form a vortex of the lubricating oil.

[0027] Specifically, the end of the contact roller 12 facing the annular oil path is a wide part, and the end opposite thereto is a narrow part. The side surface of the contact roller 12 is an inclined surface parallel to the impeller 11, and the predetermined gap between the contact roller 12 and the impeller 11 is not greater than 1 mm to prevent oil leakage. When the impeller 11 rotates, the contact roller 12 is driven to rotate by the oil film. Since the contact roller 12 is a truncated cone structure, such as Figure 7 In the structure shown, the side of the contact roller 12 will generate shear force on the oil film. Combined with the centrifugal force generated on the attached oil film when the contact roller 12 rotates, the two work together to generate eddy currents. A threaded guide groove 14 is provided on the contact roller 12 to guide the oil flow. The eddy current spreads in a spiral path away from the contact roller 12, that is, it flows from the narrow part to the wide part of the contact roller 12. The leakage of the oil film at the narrow part of the contact roller 12 can be effectively reduced through the eddy current.

[0028] As another embodiment further provided by the present invention, it also includes a stabilizing roller 13 which is rotatably disposed on the connecting member 9 and keeps synchronous movement with the contact roller 12 .

[0029] Specifically, the stabilizing roller 13 is located at the radial periphery of the contact roller 12, and the stabilizing roller 13 is vertically arranged at the contact position between the outer wall and the impeller 11, and the contact surfaces of the stabilizing roller 13 and the contact roller 12 are parallel to each other, so that the stabilizing roller 13 can provide the contact roller 12 with a supporting force perpendicular to the contact roller 12.

[0030] Furthermore, a limit block 15 is fixedly provided on the contact roller 12, and the limit block 15 is connected to the rotating shaft of the stabilizing roller 13 through a transmission belt 16, so that when the contact roller 12 rotates, the stabilizing roller 13 is driven to rotate synchronously in the same direction. At the closest point between the contact roller 12 and the stabilizing roller 13, the rotation directions of the contact roller 12 and the stabilizing roller 13 are opposite, and the oil flow moves toward the stabilizing roller 13 along the eddy current generated by the contact roller 12. Since the rotation directions are opposite and the gap between the contact roller 12 and the stabilizing roller 13 is narrow, The oil flow mainly flows with the wall at the closest point mentioned above, while the deceleration near the wall is obvious due to the viscous force. The wall close to the contact roller 12 and the stabilizing roller 13 is the inner layer, in which the inner layer fluid micro-groups can obtain more momentum supplement from the outer layer through the additional turbulent eddy viscosity force, thereby maintaining a farther distance without backflow, further preventing leakage, and reducing the oil flow speed in the annular oil circuit through the deceleration effect, offsetting part of the centrifugal force to accelerate the oil flow, avoiding the problem of oil film oscillation in the annular oil circuit.

[0031] As another embodiment further provided by the present invention, it also includes a sealing ring 22 fixedly arranged on the impeller 11 and a memory metal 98 in a circumferential array and movably arranged in the interval of the sealing ring 22, and the angle between the memory metal 98 and the annular oil passage is adjustable.

[0032] Specifically, the sealing ring 22 is a labyrinth sealing structure with multiple fixed intervals arranged linearly, and the memory metal 98 is rotatably set in the interval. When the oil speed in the annular oil circuit is too fast, the memory metal 98 is impacted by the oil flow and swings, and an angle is formed between the oil flow direction, so that the oil flow generates turbulence in the interval, thereby reducing the oil flow speed and providing support for the force of the sealing ring 22 through the turbulence, further avoiding the problem of oil film oscillation. The impeller 11 rotates relative to the memory metal 98, and the memory metal 98 has a breaking effect on the oil flow in the annular oil circuit during the swinging process, thereby avoiding the agglomeration of coked residues in the oil flow.

[0033] As another embodiment further provided by the present invention, a cutting piece 981 pointing in the direction of oil flow is fixedly provided on the memory metal 98 .

[0034] Specifically, the inner wall surface of the connector 9 is provided with folding portions 97, and the angle of the memory metal 98 is the smallest when the spacing between the folding portions 97 is the smallest. The memory metal 98 also includes a movable plate 982. The two ends of the memory metal 98 are respectively provided on both sides of the folding portion 97. When the spacing between the folding portions 97 is the smallest, the plurality of memory metals 98 are connected end to end and overlapped with each other, such as Figure 8 As shown. The distance between the inner wall and the outer wall of the folding portion 97 is maintained by the inclined side wall. When the distance is shortened, the side wall swings from the inclined direction to the horizontal direction, and the outer wall moves in the direction away from the impeller 11, so that the folding portion 97 is unfolded, the memory metal 98 is pulled, and the multiple memory metals 98 are switched to a state of being parallel to each other, and the angle between the movable plate 982 and the memory metal 98 increases, and the bending angle between the movable plate 982 and the memory metal 98 increases, so that the cutting piece 981 extends along the bending direction and cuts the coke in the oil circuit.

[0035] As another embodiment further provided by the present invention, the outer wall surface of the connecting member 9 and the end surface of the impeller 11 are of a stepped structure, and a shifting plate 91 is provided on the connecting member 9 .

[0036] Specifically, the ladder structure is as follows Figure 5As shown, the airflow direction is consistent with the guidance of the connecting member 9, preventing the airflow from flowing back during the diffusion process in the diffuser chamber 2, and the paddle 91 is an arc-shaped structure. The connection part between the air inlet 1 and the diffuser chamber 2 is the pharynx 23. The paddle 91 is located at the pharynx 23 and divides the pharynx 23 into a first channel close to the inner wall of the air inlet 1 and a second channel close to the connecting member 9. During the ventilation process, the airflow flows along the inner wall of the air inlet 1. Due to the shear force of the inner wall on the airflow, the speed of this part of the airflow is relatively slow, and it enters the diffuser chamber 2 along the inner wall through the first channel. Moreover, due to the lack of acceleration of the impeller 11, the speed of this part of the airflow is relatively slow, while the speed of the airflow in the second channel is relatively fast after the centrifugal acceleration of the impeller 11, so that the air pressure in the second channel is relatively low, and the end of the paddle 91 swings toward the second channel, so that the airflow flowing along the inner wall is guided to the first channel and accelerated under the impetus of the original airflow in the first channel, so as to further improve the diffusion effect and prevent the airflow at the boundary position from entering the diffuser chamber 2 without being fully accelerated.

[0037] As another embodiment further provided by the present invention, an arc surface 95 is provided on the outer wall surface of the connecting member 9 , and a channel with a decreasing inner diameter is formed between the arc surface 95 and the shifting plate 91 .

[0038] Specifically, the connector 9 is provided with a plurality of air ports 94 corresponding to the arc surface 95, which are used to connect the channel and the diffuser chamber 2. The airflow is accelerated when flowing along the arc surface 95, so that a local low-pressure area is generated on the arc surface 95, and the end of the paddle 91 swings into the second channel, so that the airflow flowing along the inner wall is guided to the first channel, so that the airflow provides a force to push the connector 9 when passing through the connector 9, so as to prevent the connector 9 from slipping off under the action of the oil film running at high speed.

[0039] As another embodiment further provided by the present invention, a heat-sensitive block 92 is disposed at a first end of the dial plate 91 close to the diffuser 21, and a protrusion 93 for guiding condensation is disposed at a second end opposite thereto.

[0040] Specifically, due to the increase in the inner diameter of the diffusion chamber 2, the speed of the airflow in the diffusion chamber 2 is reduced, and the mechanical energy provided to the airflow by the impeller 11 during operation is converted into thermal energy, the temperature in the diffusion chamber 2 rises, and the pharynx 23 is directly connected to the diffusion chamber 2, so that the temperature of the heat-sensitive block 92 is affected by the temperature in the diffusion chamber 2 and rises. However, since a channel with a decreasing inner diameter is formed between the curved surface 95 and the paddle plate 91, the airflow in the channel maintains a high flow rate under the action of the impeller 11, so the temperature inside the channel is relatively low. There is a temperature difference on both sides of the paddle plate 91, so that the airflow flowing through the curved surface 95 will contact the paddle plate 91 with a higher temperature, and the water vapor in the airflow will condense on the side of the paddle plate 91, and will slide along the paddle plate 91 to the protrusion 93, and will be condensed by the protrusion 93 to form condensation, and then weathered by the high-speed airflow to form a circulation in the pharynx, thereby reducing the probability of water vapor directly entering the diffusion chamber 2, and preventing water vapor from expanding in the high-temperature diffusion chamber 2 and affecting the air pressure stability in the diffusion chamber 2.

[0041] As another embodiment further provided by the present invention, it also includes a transmission shaft 5 for driving the impeller 11, on which an adjustment unit for controlling the connecting member 9 is arranged, and the adjustment unit includes an extension rod 53 that moves radially with temperature changes.

[0042] Specifically, a thrust bearing 8 is provided on the transmission shaft 5, and an oil outlet 7 is provided on the thrust bearing 8. A plurality of closed chambers 52 are provided in a circumferential array on the transmission shaft 5, and the closed chambers 52 are filled with gas that is significantly affected by thermal expansion and contraction. An extension rod 53 is slidably provided in the closed chamber 52. When the transmission shaft 5 runs too fast, high heat is generated. At this time, the temperature is transferred to the closed chamber 52 through the heat-conducting rod 51 provided on the transmission shaft 5, so that the gas in the closed chamber 52 expands and pushes the extension rod 53. The extension rod 53 moves radially and presses against the inner wall surface of the connector 9, so that the distance between the inner wall surface and the outer wall surface is shortened.

[0043] Working principle: When in use, the impeller 11 rotates and sucks gas from the air inlet 1. The gas is diffused radially by the centrifugal force generated by high-speed rotation. During the diffusion process, the gas enters the diffuser 21 along the outer wall of the connecting piece 9. During the rotation of the impeller 11, centrifugal force is generated on the piston 63, so that the piston 63 moves radially and moves away from the port of the oil inlet channel 6, and the spring 64 contracts. As the distance between the piston 63 and the port of the oil inlet channel 6 increases, the flow rate of the lubricating oil increases and enters the annular oil path through the oil delivery channel 62.

[0044] As the speed of the impeller 11 increases, the transmission shaft 5 generates high heat when running too fast. At this time, the temperature is transferred to the closed chamber 52 through the heat-conducting rod 51 arranged on the transmission shaft 5, so that the gas in the closed chamber 52 expands and pushes the extension rod 53. The extension rod 53 moves radially and presses against the inner wall surface of the connecting piece 9, so that the distance between the inner wall surface and the outer wall surface is shortened. Between the inner wall surface and the outer wall surface of the connecting piece 9 is a supply chamber 96 with some lubricating oil stored. The lubricating oil in the supply chamber 96 is squeezed into the annular oil circuit for automatic replenishment to maintain the oil film thickness.

[0045] When the impeller 11 rotates, the contact roller 12 is driven to rotate through the oil film. Since the contact roller 12 is a truncated cone structure, Figure 7 In the structure shown, the side of the contact roller 12 will generate shear force on the oil film, combined with the centrifugal force generated on the attached oil film when the contact roller 12 rotates, the two work together to generate eddy currents, and a threaded guide groove 14 is provided on the contact roller 12 to guide the oil flow. The eddy current is a diffuse spiral path in the direction away from the contact roller 12, that is, it flows from the narrow part to the wide part of the contact roller 12. The eddy current can effectively reduce the leakage of the oil film at the narrow part of the contact roller 12. Since the rotation directions are opposite and the gap between the contact roller 12 and the stabilizing roller 13 is narrow, the oil flow mainly flows with the wall at the closest point mentioned above, and the deceleration near the wall due to the viscous force is obvious, which further prevents leakage, and the oil flow speed in the annular oil circuit is reduced through the deceleration effect, offsetting part of the acceleration effect of the centrifugal force on the oil flow, avoiding the problem of oil film oscillation in the annular oil circuit.

[0046] The distance between the inner wall surface and the outer wall surface of the folding portion 97 is maintained by the inclined side wall. When the distance is shortened, the side wall swings from the inclined to the horizontal, and the outer wall moves in the direction away from the impeller 11, so that the folding portion 97 is unfolded, the memory metal 98 is pulled, and the multiple memory metals 98 are switched to a state of being parallel to each other, and the angle between the movable plate 982 and the memory metal 98 is increased, and the bending angle between the movable plate 982 and the memory metal 98 becomes larger, so that the cutting piece 981 extends along the bending direction and cuts the coke in the oil circuit.

[0047] During the ventilation process, the airflow flows along the inner wall of the air inlet 1. Due to the shear force of the inner wall on the airflow, the speed of this part of the airflow is relatively slow. It enters the diffusion chamber 2 along the inner wall through the first channel. The airflow is accelerated when flowing along the curved surface 95, so that a local low-pressure area is generated on the curved surface 95. In combination with the end of the paddle plate 91 swinging into the second channel, the airflow flowing along the inner wall is guided to the first channel, so that the airflow provides a force to push the connecting member 9 when passing through the connecting member 9. There is a temperature difference on both sides of the paddle plate 91, so that the airflow flowing through the curved surface 95 will contact the paddle plate 91 with a higher temperature. The water vapor in the airflow will condense on the side of the paddle plate 91, and will slide along the paddle plate 91 to the protrusion 93, condensed by the protrusion 93 to form condensation, and then weathered by the high-speed airflow to form a circulation in the pharynx, reducing the probability of water vapor directly entering the diffusion chamber 2.

[0048] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A centrifugal compressor and diffuser interface structure, comprising a diffuser (21) and an impeller (11) rotatably arranged on its axis, characterized in that: It comprises a connecting member (9) located between a diffuser (21) and an impeller (11), on which a plurality of contact rollers (12) are arranged in a circumferential array; The connecting member (9) comprises: for guiding the airflow toward the outer wall surface of the diffuser (21); An inner wall surface opposite to the impeller (11), wherein the inner wall surface and the outer side of the impeller (11) enclose an annular oil passage for containing lubricating oil; The connecting member (9) has a contracted state that shortens the distance between the inner wall surface and the outer wall surface.

2. The centrifugal compressor and diffuser interface structure according to claim 1, characterized in that: A predetermined gap is maintained between the side surface of the contact roller (12) and the outer side of the impeller (11), and the contact roller (12) rotates with the impeller (11) so that the lubricating oil forms a vortex.

3. The centrifugal compressor and diffuser interface structure according to claim 1, characterized in that: It also includes a stabilizing roller (13) which is rotatably arranged on the connecting member (9) and keeps synchronous movement with the contact roller (12).

4. The centrifugal compressor and diffuser interface structure according to claim 1, characterized in that: It also includes a sealing ring (22) fixedly arranged on the impeller (11) and a memory metal (98) in a circumferential array and movably arranged in the interval of the sealing ring (22); the angle between the memory metal (98) and the annular oil passage is adjustable.

5. The centrifugal compressor and diffuser interface structure according to claim 4, characterized in that: A cutting blade (981) pointing in the direction of oil flow is fixedly arranged on the memory metal (98).

6. The centrifugal compressor and diffuser interface structure according to claim 5, characterized in that: The inner wall surface of the connecting piece (9) is provided with a folded portion (97), and the angle of the memory metal (98) is the smallest when the spacing between the folded portions (97) is the smallest.

7. The centrifugal compressor and diffuser interface structure according to claim 1, characterized in that: The outer wall surface of the connecting member (9) and the end surface of the impeller (11) are in a stepped structure, and a shifting plate (91) is provided on the connecting member (9).

8. The centrifugal compressor and diffuser interface structure according to claim 7, characterized in that: The outer wall surface of the connecting member (9) is provided with a curved surface (95), and a channel with a decreasing inner diameter is formed between the curved surface (95) and the shifting plate (91).

9. The centrifugal compressor and diffuser interface structure according to claim 7, characterized in that: A heat-sensitive block (92) is provided at a first end of the dial plate (91) close to the diffuser (21), and a protrusion (93) for guiding condensation is provided at a second end opposite thereto.

10. The centrifugal compressor and diffuser interface structure according to claim 1, characterized in that: It also comprises a transmission shaft (5) for driving an impeller (11), on which an adjustment unit for controlling the connecting member (9) is arranged, the adjustment unit comprising an extension rod (53) that moves in a radial direction as the temperature changes.

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