Axial force balancing device and chemical volume charging pump

Abstract

The invention provides an axial force balancing device and a chemical volume charging pump, the axial force balancing device comprises a balancing disc, a balancing sleeve, a thrust bearing and a bearing seat, the balancing disc and the balancing sleeve are arranged on the outer side of a rotating shaft in a sleeving mode and installed on the medium side, and a first gap is formed between the balancing disc and the balancing sleeve in the axial direction of the rotating shaft; the thrust bearing is installed in the bearing seat, the rotating shaft is further sleeved with a non-driving-end bearing body and a non-driving-end bearing gland, one end of the bearing seat abuts against the non-driving-end bearing gland, and a second gap is formed between the other end of the bearing seat and the non-driving-end bearing body; at least one elastic piece is arranged in the second gap, the elastic piece is in a compressed state, and the two ends of the elastic piece abut against the bearing seat and the non-driving end bearing body respectively. According to the balancing device, the elastic piece is arranged in the second gap, the axial force is completely borne by the balancing disc, the thrust bearing does not bear the axial force of the pump and only bears the elastic force of the elastic piece, and therefore automatic adjustment of the first gap is achieved, and the axial force is dynamically balanced all the time.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear power plant control systems, and in particular to an axial force balancing device and a chemical volume charging pump. Background Art

[0002] In active and passive nuclear power plants and heating reactors, small flow and high head chemical volume charging pumps are one of the important equipment for chemical volume and volume control systems.

[0003] The chemical volume charging pump adopts a horizontal, double-shell structure multi-stage centrifugal pump, with a total of 12 closed impellers arranged in the same direction. Due to the closed impeller's own structural reasons, each stage of the impeller will generate a certain axial thrust. The axial forces generated by the impellers at each stage are combined to form a large axial thrust, which is finally balanced by the axial force balancing device.

[0004] Among them, the quality of the axial force balancing device design will directly affect the operating reliability of the multistage centrifugal pump. Among all kinds of failures of multistage pumps, more than half of the failures are caused by axial force problems. Therefore, the key factor of the reliability index of multistage centrifugal pumps lies in the rationality and reliability of the axial force balancing device design.

[0005] The existing chemical volume charging pump uses a balancing disc to balance more than 90% of the axial force, and the residual axial force is borne by the thrust bearing. The thrust bearing is generally in the form of a rolling bearing, which is lubricated by an oil slinger and cooled naturally by air. The thrust bearing is a fixed installation structure. Once installed, the bearing will be fixed in the non-drive end bearing body, and the gap between the balancing disc and the balancing sleeve will also be locked. The gap between the balancing disc and the balancing sleeve determines the ability of the balancing disc to balance the axial force. The larger the gap, the lower the ability to balance the axial force, and the greater the residual axial force borne by the bearing. When the gap is small enough, the risk of collision and wear between the balancing disc and the balancing sleeve increases. Once the collision and wear occur, the balancing disc and the balancing sleeve may bite together and cause a sudden shutdown accident. Since the design gap between the balancing disc and the balancing sleeve is generally between 0.05 and 0.10 mm, the tolerance band is very narrow and the adjustment is very difficult. Therefore, during the commissioning and operation of nuclear power plants, high temperatures of the thrust bearings of chemical volume charging pumps often occur, which seriously affects the commissioning progress of nuclear power plants and the reliability of system operation.

[0006] Based on this, the inventor of the present application proposes an axial force balancing device and a volumetric charging pump in order to solve the above-mentioned technical problems. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defect of low reliability of the axial force balancing device of the chemical volume charging pump in the prior art, and to provide an axial force balancing device and a chemical volume charging pump.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] The present invention provides an axial force balancing device, which is characterized in that it includes:

[0010] A balancing disc and a balancing sleeve are sleeved on the outside of the rotating shaft and installed on the medium side, and a first gap is formed between the balancing disc and the balancing sleeve along the axial direction of the rotating shaft;

[0011] A thrust bearing and a bearing seat, wherein the thrust bearing is installed in the bearing seat, and a non-drive end bearing body and a non-drive end bearing pressure cover are also sleeved on the rotating shaft, one end of the bearing seat is in contact with the non-drive end bearing pressure cover, and a second gap is formed between the other end and the non-drive end bearing body; wherein,

[0012] At least one elastic member is disposed in the second gap. The elastic member is in a compressed state and two ends of the elastic member are respectively in contact with the bearing seat and the non-driving end bearing body.

[0013] According to one embodiment of the present invention, the non-drive end bearing body is provided with a first conical surface on a side facing the bearing seat, and the non-drive end bearing gland is provided with a second conical surface on a side facing the bearing seat;

[0014] The opposite ends of the bearing seat are in sliding contact with the first conical surface and the second conical surface respectively.

[0015] According to an embodiment of the present invention, two opposite sides of the bearing seat have tapers, and the tapered outer end surface fits with the first tapered surface or the second tapered surface.

[0016] According to one embodiment of the present invention, the elastic member is a spring, the non-driving end bearing body is provided with a limiting groove on one side facing the bearing seat, one end of the spring is embedded in the limiting groove, and the other end is in contact with the bearing seat.

[0017] According to an embodiment of the present invention, there are multiple elastic members, and the multiple elastic members are evenly arranged around the circumference of the non-driving end bearing body.

[0018] According to one embodiment of the present invention, one end of the bearing seat is connected to the non-drive end bearing cover via an anti-rotation pin.

[0019] According to one embodiment of the present invention, a third gap is provided between the bearing seat and the non-drive end bearing cover.

[0020] According to an embodiment of the present invention, the first gap, the second gap and the third gap are all arranged in parallel along the axial direction of the rotating shaft.

[0021] According to an embodiment of the present invention, an oil slinger is further provided on one side of the thrust bearing. The oil slinger is sleeved on the outer side of the rotating shaft and the lower part of the oil slinger is immersed in lubricating oil.

[0022] The present invention also provides a chemical volume charging pump, which is characterized in that it includes the axial force balancing device as described above.

[0023] The positive and progressive effects of the present invention are:

[0024] The axial force balancing device of the present invention has elastic parts arranged in the bearing seat and the non-driving end bearing body, so that the axial force can be fully borne by the balancing disk, and the thrust bearing does not bear the axial force of the pump but only bears the elastic force of the elastic part. Regardless of whether it is under stable operating conditions or variable conditions, the gap between the balancing disk and the balancing sleeve can be automatically adjusted, so that the axial force always reaches a dynamic balance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0026] Figure 1 It is a cross-sectional view of the axial force balancing device of the present invention along the axial direction of the rotating shaft.

[0027] 1. Balance plate;

[0028] 2. Balancing sleeve; 21. First gap;

[0029] 3. Thrust bearing; 31. Oil slinger;

[0030] 4. Bearing seat; 41. Anti-rotation pin; 42. Third gap;

[0031] 5. non-driving end bearing body; 51. second gap; 52. first cone surface; 53. limiting groove;

[0032] 6. Non-drive end bearing gland; 61. Second cone surface;

[0033] 7. Elastic parts;

[0034] 8 reels. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0037] Please refer to Figure 1 The present invention proposes an axial force balancing device, including a balancing disc 1, a balancing sleeve 2, a thrust bearing 3 and a bearing seat 4. The balancing disc 1 and the balancing sleeve 2 are sleeved on the outside of a rotating shaft 8 and installed on the medium side. A first gap 21 is provided between the balancing disc 1 and the balancing sleeve 2 along the axial direction of the rotating shaft 8; the thrust bearing 3 is installed in the bearing seat 4, and a non-driving end bearing body 5 and a non-driving end bearing pressure cover 6 are also sleeved on the rotating shaft 8. One end of the bearing seat 4 abuts against the non-driving end bearing pressure cover 6, and a second gap 51 is formed between the other end and the non-driving end bearing body 5; wherein at least one elastic member 7 is provided in the second gap 51, and the elastic member 7 is in a compressed state and its two ends abut against the bearing seat 4 and the non-driving end bearing body 5 respectively.

[0038] It should be noted that, by arranging the elastic member 7 in the second gap 51, the axial force can be fully borne by the balancing disc 1, and the thrust bearing 3 does not bear the axial force of the pump, but only bears the elastic force of the spring assembly. Therefore, whether under stable operating conditions or under variable conditions, the gap (first gap 21) between the balancing disc 1 and the balancing sleeve 2 can be automatically adjusted, so that the axial force always reaches a dynamic balance.

[0039] In one embodiment, the non-drive end bearing body 5 is provided with a first conical surface 52 on the side facing the bearing seat 4, and the non-drive end bearing cover 6 is provided with a second conical surface 61 on the side facing the bearing seat 4; the opposite ends of the bearing seat 4 are respectively slidably abutted against the first conical surface 52 and the second conical surface 61.

[0040] Specifically, two opposite sides of the bearing seat 4 have tapers, and the tapered outer end surface fits with the first tapered surface 52 or the second tapered surface 61 .

[0041] That is, the two ends of the bearing seat 4 are tapered and matched with the tapered holes of the non-drive end bearing body 5 and the non-drive end bearing cover 6, so that when the thrust bearing 3 moves axially, the bearing seat 4 can always be automatically aligned, and the friction resistance encountered during the axial movement is smaller.

[0042] In one embodiment, the elastic member 7 is a spring, and a limiting groove 53 is provided on the side of the non-driving end bearing body 5 facing the bearing seat 4 . One end of the spring is embedded in the limiting groove 53 , and the other end is in contact with the bearing seat 4 .

[0043] The limiting groove 53 is used to limit one end of the spring to prevent the spring from being excessively offset relative to the non-driving end bearing body 5 and the bearing seat 4 when elastically compressed or relaxed, thereby improving the operational stability of the spring compression or relaxation movement.

[0044] Furthermore, there are multiple elastic members 7 , and the multiple elastic members 7 are evenly arranged around the circumference of the non-drive end bearing body 5 .

[0045] The present invention is described by taking 12 springs as an example, and the 12 springs are evenly spaced around the circumference of the non-driving end bearing body 5, so that the balance of the elastic force on the bearing seat 4 can be improved. It can be seen that the number of springs can also be 4, 8, etc., which is not limited here.

[0046] In the initial state, the spring is in a compressed state and provides an initial thrust to the bearing seat 4. The initial thrust can ensure that the balancing disc 1 is separated from the balancing sleeve 2 during shutdown, and can provide the minimum load requirement for the thrust bearing 3 during operation.

[0047] In one embodiment, one end of the bearing seat 4 is connected to the non-drive end bearing cover 6 via an anti-rotation pin 41 .

[0048] An anti-rotation pin 41 is provided on one side of the bearing seat 4 to prevent the bearing seat 4 from rotating due to the torque transmitted by the thrust bearing 3 .

[0049] Specifically, one end of the anti-rotation pin 41 is installed in the non-drive end bearing gland 6 and is tightened with the pin hole on the non-drive end bearing gland 6 through interference fit. The other end of the anti-rotation pin 41 is inserted into the pin hole of the bearing seat 4. The diameter of the pin hole on the bearing seat 4 is larger than the diameter of the anti-rotation pin 41, so that the bearing seat 4 can be ensured to be unobstructed when moving.

[0050] In one embodiment, a third gap 42 is provided between the bearing seat 4 and the non-drive end bearing cover 6 .

[0051] That is, the axial balancing device of the present invention has three axial gaps, namely, a first gap 21 between the balancing disc 1 and the balancing sleeve 2, a second gap 51 between the bearing seat 4 and the non-drive end bearing body 5, and a third gap 42 between the bearing seat 4 and the non-drive end bearing cover 6.

[0052] When the pump is in operation, the value of the first gap 21 changes dynamically, is automatically adjusted according to the magnitude of the axial force, and is at least greater than 0, thereby avoiding the risk of downtime caused by friction between the balancing disc 1 and the balancing sleeve 2.

[0053] The value range of the second gap 51 is 0-1mm. When the second gap 51 is 0, the first gap 21 reaches the minimum value of 0.05mm; the value range of the third gap 42 is 0-1mm. When the third gap 42 is 0, the first gap 21 reaches the maximum value, for example, 1.05mm.

[0054] Specifically, the state of the pump is divided into four stages, namely, the shutdown state, the startup moment, the normal operation period, and the idling shutdown period.

[0055] In the stopped state, the thrust bearing 3 is acted upon by the elastic force of the elastic member 7, and the thrust bearing 3 and the rotating shaft 8 are brought to rest against one end of the non-drive end bearing cover 6 via the bearing seat 4. At this time, the first gap 21 between the balancing disc 1 and the balancing sleeve 2 is 1.05 mm, the second gap 51 between the bearing seat 4 and the non-drive end bearing body 5 is 1 mm, and the third gap 42 between the bearing seat 4 and the non-drive end bearing cover 6 is 0 mm.

[0056] At the moment the pump is started, the rotating shaft 8 moves with the thrust bearing 3 toward one end of the non-drive end bearing cover 6 under the action of the dynamic reaction force. However, at this time, the third gap 42 between the bearing seat 4 and the non-drive end bearing cover 6 is 0 mm, so the bearing seat 4 abuts against the non-drive end bearing cover 6 and cannot move. The first gap 21, the second gap 51 and the third gap 42 are consistent with those in the shutdown state. Only the bearing load has changed due to the action of the dynamic reaction force.

[0057] During normal operation of the pump, an axial force has been established, which pulls the rotating shaft 8 to the right (medium side), and the thrust bearing 3 moves to the right synchronously. The compression amount of the elastic member 7 increases, and the elastic force gradually increases. The load of the thrust bearing 3 increases due to the increase in the elastic force. At this time, the balancing disc 1 bears all the axial force, and the first gap 21 between the balancing disc 1 and the balancing sleeve 2 is determined by the axial force generated by the working conditions and the balancing ability of the balancing disc 1, for example, 0.08-0.12mm. The second gap 51 can range from 0.03-0.07mm, and the third gap 42 can range from 0.93-0.97mm.

[0058] During the idling shutdown period, the axial force gradually decreases. When the value of the axial force is lower than the elastic force, the shaft 8 moves toward the non-drive end bearing cover 6 due to the elastic force, and the third gap 42 between the balancing disc 1 and the balancing sleeve 2 gradually increases. When the speed drops to 0, the values ​​of the first gap 21, the second gap 51 and the third gap 42 are the same as those in the shutdown state.

[0059] It should be noted that, in all states, the forces on the thrust bearing 3 are only the dynamic reaction force and the spring force. The dynamic reaction force is a transient force, the magnitude of which does not exceed 100kg, and the spring force is a lasting force, the magnitude of which is in the range of 120-150kg. Therefore, the load on the thrust bearing 3 is very low, the temperature rise of the thrust bearing 3 is also very low, and the service life of the thrust bearing 3 is greatly improved.

[0060] In one embodiment, an oil slinger 31 is further provided on one side of the thrust bearing 3. The oil slinger 31 is sleeved on the outer side of the rotating shaft 8 and the lower part thereof is immersed in lubricating oil.

[0061] The oil slinger 31 is hung on the oil ring seat and rotates with the rotating shaft 8. The lubricating oil is slingering from the oil slinger 31, and after lubricating the thrust bearing 3, it flows to the radial bearing through the tapered bearing seat 4, and finally returns to the oil tank of the non-driving end bearing body 5 through the oil return hole on one side of the radial bearing, forming a complete internal circulation system of the lubricating oil.

[0062] In summary, the axial force balancing device of the present invention, by arranging the elastic member 7 in the bearing seat 4 and the non-drive end bearing body 5, can realize that the axial force is fully borne by the balancing disc 1, and the thrust bearing 3 does not bear the axial force of the pump, but only bears the elastic force of the elastic member 7. Regardless of the stable operating condition or the variable operating condition, the automatic adjustment of the gap between the balancing disc 1 and the balancing sleeve 2 can be realized, so that the axial force always reaches a dynamic balance.

[0063] The present invention also provides a volumetric charging pump, comprising the above-mentioned axial force balancing device, which has all the beneficial effects of the axial force balancing device and will not be described in detail here.

[0064] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "install", "connect", "connect", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be a mechanical connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0065] The present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or multiple times in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0066] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. An axial force balancing device, characterized in that: include: A balancing disc and a balancing sleeve are sleeved on the outside of the rotating shaft and installed on the medium side, and a first gap is formed between the balancing disc and the balancing sleeve along the axial direction of the rotating shaft; A thrust bearing and a bearing seat, wherein the thrust bearing is installed in the bearing seat, and a non-drive end bearing body and a non-drive end bearing pressure cover are also sleeved on the rotating shaft, one end of the bearing seat is in contact with the non-drive end bearing pressure cover, and a second gap is formed between the other end and the non-drive end bearing body; wherein, At least one elastic member is disposed in the second gap. The elastic member is in a compressed state and two ends of the elastic member are respectively in contact with the bearing seat and the non-driving end bearing body.

2. The axial force balancing device according to claim 1, characterized in that: The non-driving end bearing body is provided with a first conical surface on the side facing the bearing seat, and the non-driving end bearing gland is provided with a second conical surface on the side facing the bearing seat; The opposite ends of the bearing seat are in sliding contact with the first conical surface and the second conical surface respectively.

3. The axial force balancing device according to claim 2, characterized in that: The bearing seat has tapers on opposite sides, and the tapered outer end surface is fitted with the first tapered surface or the second tapered surface.

4. The axial force balancing device according to claim 1, characterized in that: The elastic member is a spring, and a limiting groove is provided on the side of the non-driving end bearing body facing the bearing seat. One end of the spring is embedded in the limiting groove, and the other end is in contact with the bearing seat.

5. The axial force balancing device according to claim 4, characterized in that: There are multiple elastic members, and the multiple elastic members are evenly arranged around the circumference of the non-driving end bearing body.

6. The axial force balancing device according to claim 1, characterized in that: One end of the bearing seat is connected to the non-driving end bearing cover through an anti-rotation pin.

7. The axial force balancing device according to claim 1, characterized in that: A third gap is provided between the bearing seat and the non-drive end bearing cover.

8. The axial force balancing device according to claim 7, characterized in that: The first gap, the second gap and the third gap are all arranged in parallel along the axial direction of the rotating shaft.

9. The axial force balancing device according to claim 1, characterized in that: An oil slinger is also provided on one side of the thrust bearing. The oil slinger is sleeved on the outer side of the rotating shaft and the lower part of the oil slinger is immersed in lubricating oil.

10. A chemical volume charging pump, characterized in that: It comprises an axial force balancing device as described in any one of claims 1 to 9.

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