Sealing structure of a radial turbine

Abstract

The present application discloses a sealing structure for a radial turbine, which relates to the technical field related to radial turbines and is used to solve the problems of poor sealing effect, large axial length and difficult control of the axial force of the impeller in existing radial turbines. The sealing structure for the radial turbine provided in the present application, wherein the radial turbine includes a rotating shaft and an impeller sleeved outside the rotating shaft and connected to the rotating shaft. The sealing structure includes a sealing disk and a gas passage. The sealing disk is sleeved outside the rotating shaft and is located on the back of the impeller. The sealing disk sequentially includes a shaft end sealing portion, a balance chamber and a back-to-back sealing portion from its center to the edge. There is a gap used to form the balance chamber between the sealing disk and the back of the impeller. One end of the gas passage is communicated with the balance chamber, and the other end is used to be connected to a regulating valve for regulating the gas pressure in the balance chamber outside. The present application is used to reduce the gas leakage from the impeller chamber to the bearing chamber and from the front of the impeller to the back of the impeller, and to realize the adjustable pressure in the balance chamber.

Description

Technical Field

[0001] This application relates to the technical field of radial turbines, and more particularly to a sealing structure for a radial turbine. Background Art

[0002] The gas pressures in the impeller cavity and the bearing cavity of a radial turbine are different. To reduce gas leakage and improve the efficiency of the main engine, a shaft end sealing structure needs to be provided between the impeller cavity and the bearing cavity. The existing shaft end sealing structure usually adopts an axial comb tooth sealing form, but its sealing effect is poor. To improve the sealing effect, the number of comb teeth needs to be increased, which often leads to an increase in the axial length of the radial turbine.

[0003] Moreover, when the radial turbine is operating, the gas pressures on the front (blade side) and back (blade-free side) of the impeller are different. The gas pressure difference causes a large axial force on the impeller. Coupled with the high rotational speed of the impeller, the combination of large load and high rotational speed makes the bearing design difficult and the failure risk high.

[0004] Therefore, there is an urgent need to provide a sealing structure for a radial turbine to solve the above problems. Summary of the Invention

[0005] This application provides a sealing structure for a radial turbine, which can solve the problems of poor sealing effect, large axial length, and difficult control of the axial force of the impeller in the existing radial turbine.

[0006] To achieve the above object, the sealing structure of the radial turbine provided in this application, wherein the radial turbine includes:

[0007] A rotating shaft;

[0008] An impeller, sleeved outside the rotating shaft and connected to the rotating shaft;

[0009] The sealing structure includes:

[0010] A sealing disc, sleeved outside the rotating shaft and located on the back of the impeller. The sealing disc sequentially includes a shaft end sealing portion, a balance cavity, and a back of wheel sealing portion from its center to the edge. There is a gap for forming the balance cavity between the sealing disc and the back of the impeller;

[0011] A gas passage, one end of which is communicated with the balance cavity and the other end is used to be connected to a regulating valve for regulating the gas pressure in the balance cavity outside.

[0012] In some embodiments of this application, a balance through hole is formed on the sealing disc, and the balance through hole is configured as the gas passage.

[0013] In some embodiments of the present application, there are multiple balance through-holes, which are arranged at equal angles along the circumferential direction of the sealing disc.

[0014] In some embodiments of the present application, the sealing structure further includes:

[0015] A sealing shaft sleeve, which is sleeved outside the rotating shaft and located radially inside the sealing disc, and the shaft end sealing portion of the sealing disc seals and connects the sealing shaft sleeve and the impeller.

[0016] In some embodiments of the present application, both the shaft end sealing portion and the back of the wheel sealing portion include axial comb teeth and radial comb teeth.

[0017] In some embodiments of the present application, the axial comb teeth adopt a smooth structure, and the radial comb teeth adopt a zigzag structure.

[0018] In some embodiments of the present application, in the axial section of the sealing disc, the axial comb teeth are generally triangular and include multiple ones, and the tips of the multiple axial comb teeth face radially inside the sealing disc.

[0019] In some embodiments of the present application, in the axial section of the sealing disc, the radial comb teeth are generally triangular and include multiple ones, and the tips of the multiple radial comb teeth face the impeller, and multiple sealing grooves are provided on the back of the impeller corresponding to the radial comb teeth.

[0020] In some embodiments of the present application, an annular boss protruding towards the sealing disc is formed on the back of the impeller, a sealing groove is formed on the radially outer side of the annular boss, and the radially inner side is smoothly connected to the back of the impeller.

[0021] In some embodiments of the present application, the radial flow turbine further includes:

[0022] A casing, which is arranged on the outer periphery of the impeller and is coaxially arranged with the impeller;

[0023] A housing, which is sleeved on the outer periphery of the casing and is hermetically connected to the outer peripheries of the casing and the sealing disc.

[0024] In the specific use process, the gas pressures on the front and back of the impeller are different. In the present application, a balance chamber is arranged between the impeller and the sealing disc, and a gas channel is used to connect the balance chamber with a regulating valve for regulating the gas pressure of the balance chamber outside, so that the gas pressure in the balance chamber is regulated, the axial force received by the impeller due to the gas pressure difference between the front and back is reduced, and thus the total axial force of the shafting is reduced.

[0025] Moreover, in order to support and install the rotating shaft, a bearing is sleeved on the rotating shaft. The bearing is arranged on the side of the sealing disc facing away from the impeller. When the radial flow turbine is operating, the rotational speed of the impeller inside is relatively high. The superposition of the two factors of large load and high speed makes the bearing design difficult and the reliability poor. Therefore, by actively adjusting the pressure on the back of the impeller through the balance chamber, the load of the bearing can be ensured to be controllable, thereby improving the reliability of the bearing. In addition, the shaft end sealing part on the sealing disc seals the connection between the impeller and the rotating shaft, reducing the gas leakage from the front of the impeller to the back; the back seal part seals the connection between the impeller and the sealing disc, reducing the gas leakage from the impeller chamber to the bearing chamber, thereby reducing the leakage loss of the radial flow turbine main engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 is a schematic structural diagram of a radial flow turbine in an embodiment of the present application;

[0028] Figure 2 is Figure 1 an enlarged view of part A in

[0029] Figure 3 is a schematic structural diagram of the sealing disc in an embodiment of the present application.

[0030] The main reference numerals in the drawings of the present application specification are described as follows:

[0031] 1 - Rotating shaft;

[0032] 2 - Impeller;

[0033] 3 - Sealing disc; 31 - Shaft end sealing part; 311 - Axial shaft end comb teeth; 312 - Radial shaft end comb teeth; 32 - Balance chamber; 33 - Back seal part; 331 - Axial back comb teeth; 332 - Radial back comb teeth; 34 - Annular boss;

[0034] 4 - Gas passage; 41 - Axial hole section; 42 - Radial shaft section;

[0035] 5 - Bearing;

[0036] 6 - Sealing shaft sleeve;

[0037] 7 - Casing;

[0038] 8 - Housing;

[0039] 9 - Sealing ring;

[0040] 10 - End cover. Detailed implementation manners

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0042] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present application.

[0043] The terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0044] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0045] The present application provides a sealing structure for a radial turbine, which will be described in detail below. It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments of the present application. And in the following embodiments, each embodiment has its own emphasis. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0046] As a key component in a power cycle, the research on the turbine is also quite important. At present, turbines are mainly divided into axial-flow turbines and radial-flow turbines. Axial-flow turbines are generally designed as multi-stage, with large flow rates and large output powers. Radial-flow turbines are divided into two categories: centrifugal and centripetal.

[0047] Figure 1 It is a schematic structural diagram of a radial turbine in an embodiment of the present application; Figure 2 is Figure 1 an enlarged view of part A in Figure 3 It is a schematic structural diagram of a sealing disk in an embodiment of the present application. Referring to Figures 1 to 3 , the sealing structure of the radial turbine provided by the present application includes a rotating shaft 1 and an impeller 2. The impeller 2 is sleeved outside the rotating shaft 1 and is connected to the rotating shaft 1. The sealing structure includes a sealing disk 3 and a gas passage 4. The sealing disk 3 is sleeved outside the rotating shaft 1 and is located on the back of the impeller 2. The sealing disk 3 sequentially includes a shaft end sealing portion 31, a balance chamber 32, and a back of wheel sealing portion 33 from its center to the edge. There is a gap for forming the balance chamber 32 between the sealing disk 3 and the back of the impeller 2. One end of the gas passage 4 is communicated with the balance chamber 32, and the other end is used to be connected to a regulating valve for regulating the gas pressure in the balance chamber 32 outside. Among them, Figure 2 the arrow shown in Figure 2 is a schematic diagram of the gas flow in the gas passage 4. The direction shown by the arrow is only a schematic diagram of the gas flow direction. That is to say, the gas flow direction is usually

[0048] the flow direction indicated by the arrow, but there is also a reverse flow in some special cases.

[0049] Meanwhile, it should be noted that in order to support and install the rotating shaft 1, a bearing 5 is sleeved on the rotating shaft 1. The bearing 5 is arranged on the side of the sealing disc 3 facing away from the impeller 2. Moreover, when the radial flow turbine is operating, the rotational speed of the impeller 2 inside it is relatively high. The superposition of the two factors of large load and high speed makes the design of the bearing 5 difficult and its reliability poor. Therefore, by actively adjusting the pressure on the back of the impeller 2 through the balance chamber 32, the load of the bearing 5 can be ensured to be controllable, thereby improving the reliability of the bearing 5. In addition, the shaft end seal part 31 on the sealing disc 3 is sealingly connected to the impeller 2 and the rotating shaft 1 to reduce the gas leakage from the front side of the impeller 2 to the back side of the impeller 2; the back-to-back seal part 33 is sealingly connected to the impeller 2 and the sealing disc 3 to reduce the gas leakage from the impeller chamber (the chamber in the radial flow turbine for installing the impeller 2) to the bearing chamber (the chamber in the radial flow turbine for installing the bearing 5). Thus, the leakage loss of the radial flow turbine main engine can be reduced, and the efficient operation of the radial flow turbine can be ensured.

[0050] Among them, there is a gap between the sealing disc 3 and the back of the impeller 2 to form the balance chamber 32. That is to say, when the sealing disc 3 and the impeller 2 are assembled, the sealing disc 3 and the impeller 2 do not contact at the corresponding positions of the balance chamber 32. The above gap is obtained by the surface of the sealing disc 3 facing the back of the impeller 2 being recessed in a direction away from the impeller 2.

[0051] More specifically, balance through-holes are formed on the sealing disc 3, and the balance through-holes are configured as the gas channels 4. That is to say, the above balance through-holes are the gas channels 4. Compared with the embodiment of additionally providing a pipeline as the gas channel 4, in this application, the gas channel 4 is directly integrated on the sealing disc 3. On the one hand, no additional components are added, ensuring the simple structure of the above sealing structure; on the other hand, the volume of the sealing structure is not increased, thereby ensuring that the above radial flow turbine has a high space utilization rate.

[0052] Among them, there are multiple balance through-holes (i.e., gas channels 4) and they are arranged at equal angles along the circumferential direction of the sealing disc 3 to ensure that the gas pressure on the back of the impeller 2 is relatively balanced in its circumferential direction, and further reduce the axial force of the impeller 2. By way of example, referring to Figure 3 , the gas channel 4 in this application includes an axial hole section 41 and a radial shaft section 42 connected to the axial hole section 41. The radial shaft section 42 extends from the end of the axial hole section 41 in a direction away from the center of the sealing disc 3 and penetrates the outer peripheral surface of the sealing disc 3.

[0053] In some embodiments of the present application, the above-mentioned sealing structure further includes a sealing shaft sleeve 6. The sealing shaft sleeve 6 is sleeved outside the rotating shaft 1 and located radially inside the sealing disc 3. The shaft end sealing portion 31 of the sealing disc 3 seals and connects the sealing shaft sleeve 6 and the impeller 2, that is, the rotating shaft 1 and the sealing disc 3 are separated by the sealing shaft sleeve 6 to protect the rotating shaft 1 from being damaged when a failure occurs. Even if a failure occurs, only the sealing shaft sleeve 6 needs to be replaced.

[0054] Exemplarily, the above-mentioned sealing shaft sleeve 6 is in interference fit with the rotating shaft 1. One axial side of the sealing shaft sleeve 6 abuts against the shaft shoulder of the rotating shaft 1, and the other axial side abuts against the back surface of the impeller 2. Thus, the axial positioning of the sealing shaft sleeve 6 on the rotating shaft 1 is realized through the above-mentioned shaft shoulder and the back surface of the impeller 2. The end of the rotating shaft 1 extends into the impeller 2, that is, the fit between the two is a shaft-hole fit, and a shaft shoulder is formed on the shaft section of the rotating shaft 1 extending into the impeller 2. Correspondingly, the mating hole on the impeller 2 is a stepped hole. The axial positioning between the two is realized through the cooperation of the shaft shoulder and the stepped hole. The above-mentioned sealing disc 3 does not rotate with the rotating shaft 1.

[0055] Continuing to refer to Figure 2 and Figure 3 As shown in, both the shaft end sealing portion 31 and the back of the wheel sealing portion 33 include axial comb teeth and radial comb teeth. Exemplarily, the shaft end sealing portion 31 includes shaft end axial comb teeth 311 and shaft end radial comb teeth 312, and the back of the wheel sealing portion 33 includes back of the wheel axial comb teeth 331 and back of the wheel radial comb teeth 332. Since the sealing gap of the radial comb teeth is easily affected by the axial movement of the shafting, the sealing gap is not easy to control, and the sealing performance is poor. The shaft end sealing portion 31 of the present application adopts a composite structure of shaft end axial comb teeth 311 and shaft end radial comb teeth 312, and the back of the wheel sealing portion 33 adopts a composite structure of back of the wheel axial comb teeth 331 and back of the wheel radial comb teeth 332. Compared with the simple radial comb teeth seal, the sealing effect of the sealing disc 3 can be further improved, and while maintaining a sufficient number of sealing comb teeth to ensure the sealing effect, the axial dimension of the sealing disc 3 is greatly shortened, which is particularly beneficial for the dynamic design of the impeller 2.

[0056] Among them, the axial comb teeth (shaft end axial comb teeth 311 and back of the wheel axial comb teeth 331) adopt a smooth structure, which is convenient for processing, disassembly and assembly. The radial comb teeth (shaft end radial comb teeth 312 and back of the wheel radial comb teeth 332) adopt a zigzag structure, that is, the radial comb teeth (shaft end radial comb teeth 312 and back of the wheel radial comb teeth 332) are arranged in a high and low staggered manner to improve the sealing effect.

[0057] More specifically, on the axial section of the sealing disk 3, the axial comb teeth (axial comb teeth 311 at the shaft end and axial comb teeth 331 at the wheel back) are roughly triangular and include a plurality of them, and the tips of the plurality of axial comb teeth (axial comb teeth 311 at the shaft end and axial comb teeth 331 at the wheel back) face the radial inner side of the sealing disk 3, so as to reduce the damage to the impeller 2 and the sealing sleeve 6 when the plurality of axial comb teeth rub against the impeller 2 or the sealing sleeve 6 under abnormal conditions. Correspondingly, the impeller 2 and the sealing sleeve 6 are provided with tooth grooves corresponding to the axial comb teeth.

[0058] Similarly, on the axial section of the sealing disk 3, the radial comb teeth (the radial comb teeth 312 at the shaft end and the radial comb teeth 332 on the wheel back) are roughly triangular in shape and include a plurality of them, the tips of the plurality of radial comb teeth are facing the impeller 2, and a plurality of sealing grooves are provided on the back side of the impeller 2 corresponding to the radial comb teeth (the radial comb teeth 312 at the shaft end and the radial comb teeth 332 on the wheel back).

[0059] The sealing clearance value of the axial comb teeth (axial comb teeth 311 at the shaft end and axial comb teeth 331 at the wheel back) is determined according to the theoretical maximum radial amplitude and shape and position tolerance of the impeller 2 at the sealing surface during operation. The sealing clearance value of the radial comb teeth (radial comb teeth 312 at the shaft end and radial comb teeth 332 at the wheel back) is determined according to the axial movement and dimensional tolerance of the impeller 2 during operation.

[0060] Continue to refer to Figure 2 The back of the impeller 2 is formed with an annular boss 34 protruding toward the sealing disk 3, the radial outer side of the annular boss 34 is formed with the sealing groove, and the radial inner side is connected to the back of the impeller 2 by a smooth transition. In this way, not only can the strength of the impeller 2 be ensured not to be affected, but also the stress concentration caused by the sudden change of the thickness of the impeller 2 in the axial direction can be avoided through the smooth transition plane.

[0061] In some embodiments of the present application, the radial turbine further comprises a casing 7 and a housing 8, wherein the casing 7 is arranged at the periphery of the impeller 2 and is coaxially arranged with the impeller 2, and is used to install and fix the impeller 2 and is arranged at the front of the impeller 2. The housing 8 is sleeved on the periphery of the casing 7 and is sealed and connected with the periphery of the sealing disk 3. For example, a sealing ring 9 is arranged between the periphery of the casing 8 and the sealing disk 3.

[0062] The radial turbine further comprises an end cover 10, which is mounted on a side of the casing 8 and the casing 7 facing away from the sealing disk 3, and the casing 8 and the casing 7 are fastened to the end cover 10 by bolts.

[0063] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0064] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claimed rights. In addition, specific examples are used in the specification to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application, and the content of this specification should not be construed as a limitation to the present application.

Claims

1. A sealing structure of a radial turbine, characterized in that The radial turbine includes: A rotating shaft; An impeller, sleeved outside the rotating shaft and connected to the rotating shaft; The sealing structure includes: A sealing disc, sleeved outside the rotating shaft and located on the back of the impeller. The sealing disc sequentially includes a shaft-end sealing portion, a balance chamber, and a back-to-wheel sealing portion from its center to the edge. There is a gap between the sealing disc and the back of the impeller to form the balance chamber; A gas passage, one end of which is communicated with the balance chamber and the other end is used to be connected to a regulating valve for regulating the gas pressure in the balance chamber outside; A balance through-hole is formed on the sealing disc, and the balance through-hole is configured as the gas passage.

2. The sealing structure of the radial turbine according to claim 1, characterized in that There are multiple balance through-holes, and they are arranged at equal angles along the circumferential direction of the sealing disc.

3. The sealing structure of the radial flow turbine according to claim 1, characterized in that, The sealing structure further includes: A sealing shaft sleeve, sleeved outside the rotating shaft and located radially inside the sealing disc. The shaft-end sealing portion of the sealing disc seals and connects the sealing shaft sleeve and the impeller.

4. The sealing structure of the radial turbine according to claim 3, characterized in that, Both the shaft-end sealing portion and the back-to-wheel sealing portion include axial comb teeth and radial comb teeth.

5. The sealing structure of the radial turbine according to claim 4, characterized in that, The axial comb teeth adopt a smooth structure, and the radial comb teeth adopt a zigzag structure.

6. The sealing structure of the radial turbine according to claim 4, characterized in that, In the axial section of the sealing disc, the axial comb teeth are generally triangular and include multiple ones. The tips of the multiple axial comb teeth face radially inside the sealing disc.

7. The sealing structure of the radial turbine according to claim 4, characterized in that, In the axial section of the sealing disc, the radial comb teeth are generally triangular and include multiple ones. The tips of the multiple radial comb teeth face the impeller, and multiple sealing grooves are provided on the back of the impeller corresponding to the radial comb teeth.

8. The sealing structure of the radial flow turbine according to claim 7, characterized in that, A circular boss protruding towards the sealing disc is formed on the back of the impeller. The sealing groove is formed on the radially outer side of the circular boss, and the radially inner side is smoothly connected to the back of the impeller.

9. The sealing structure of the radial turbine according to claim 1, characterized in that The radial turbine further includes: A casing, arranged on the outer periphery of the impeller and coaxially arranged with the impeller; A housing, sleeved on the outer periphery of the casing and hermetically connected to the outer peripheries of the casing and the sealing disc.

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