CN114275137B - A Shafting Structure for a Compact Axial-Flow Water Jet - Google Patents

Abstract

The invention discloses a shafting structure for a compact axial-flow water-jet propeller, which comprises a main shaft, an impeller, a supporting component and a sealing component, wherein the impeller is arranged on the main shaft; the supporting assembly comprises a rolling bearing group, a front bearing seat, a front filler cover plate, a front oil seal cover plate, a self-aligning ball bearing, a rear bottom plate and a rear cover plate, wherein the rolling bearing group, the front bearing seat, the front filler cover plate and the front oil seal cover plate are arranged at the front end of the main shaft; the rolling bearing group comprises two angular contact ball bearings which are configured back to back and used for bearing axial load and radial load and used as a support of the main shaft; the inner ring of the angular contact ball bearing is arranged on one side of the main shaft through a locking nut, and the outer ring of the angular contact ball bearing is arranged in the front bearing seat; the front bearing seat is arranged at a reserved shaft outlet hole on a water inlet flow channel of the water-jet propeller; the rear bottom plate and the rear cover plate are respectively arranged on two sides of the self-aligning ball bearing and used for fixing the axial position of the self-aligning ball bearing. The invention has compact structure and gives consideration to operation stability, high rotating speed and high power.

Description

A Shafting Structure for a Compact Axial-Flow Water Jet

technical field

The invention relates to the field of fluid machinery and mechanical transmission, in particular to a shafting structure for a compact axial-flow water-jet propeller.

Background technique

In the axial flow water jet, the main function of the shafting structure is to transmit the power of the driving machine (including electric motors, diesel engines, etc.) to drive the impeller to rotate, so that the rotating impeller blades push and squeeze the working medium (usually water). The action of the medium is sucked in and pressed out, thereby generating thrust. As shown in Figure 1, the water jet drive shaft system is usually composed of a drive flange (or coupling), a main shaft, a front sealing device, a front bearing group, an impeller, a rear bearing group, a rear sealing device, etc. type support structure. These components are more complex in structure and larger in size, and are more suitable for large water jets. However, this type of shafting structure is often not well adapted and applied when facing small-sized and compact axial-flow water jet propulsion (especially those with high requirements on shafting performance), usually as follows:

(1) The front sealing device has a large volume and a long axial length, which is difficult to arrange in the water inlet channel of a small water jet. It needs to occupy space inward or outward, which will affect the performance of the water jet: occupy the pump inward. runner space. Causes a large loss of flow channel performance; corresponding structures need to be added to the outside, which is not conducive to the overall structural strength, volume miniaturization and weight reduction.

(2) The maximum diameter of the impeller and guide vane hub of the small water jet is usually small, and the minimum diameter of the main shaft is strictly limited by the strength and cannot be too small. In this case, the volume of the rear bearing group and the rear sealing device is often Exceeding the allowable space of the hub, resulting in installation.

(3) The wall thickness and strength of the fasteners cannot meet the requirements, and they are easily damaged.

Some of the existing shafting structures for small-sized axial-flow water jets, some of which use a simpler single-point support structure cantilever beam design, are prone to vibration and friction during high-speed operation. The phenomenon of bumping and so on is not conducive to the smooth operation of the water jet; the other part adopts the main shaft-sleeve design. Although the existing design belongs to a double-point support structure, it also limits the maximum diameter of the main shaft, otherwise it will occupy a large number of flow channels. Internal space leads to compromised performance and is not suitable for high-speed, high-power compact waterjets.

SUMMARY OF THE INVENTION

Aiming at the deficiency that the existing water jet drive shaft system cannot be applied to small and compact axial-flow water jet propulsion or cantilever beam type drive shaft system, which is not conducive to the smooth operation of the water jet propeller, the present invention aims at high speed and high speed. The compact water jet propulsion with high power is designed with a set of shafting structure with small size, small space occupation, light weight, no great influence on the performance of the flow channel, and high strength and running stability. Compared with the existing solution, the biggest advantage of the present invention is that it takes into account the operational stability and the high rotational speed and high power performance indicators of the water jet, that is, the applicable water jet has a wider performance range (corresponding to high power and high rotational speed). ).

The object of the present invention is achieved through the following technical solutions:

A shafting structure for a compact axial-flow water-jet propeller, the shafting structure comprising a main shaft, an impeller, a support assembly, and a sealing assembly;

The main shaft is connected with the upper-level power output shaft through a coupling, and rotates under the action of driving power;

The impeller is connected to the main shaft by a key, and the two ends of the impeller are respectively locked by a shaft sleeve and a locking nut; the impeller rotates with the main shaft and generates a stable working water flow, thereby generating thrust;

The support assembly includes a rolling bearing group, a front bearing seat, a front packing cover, a front oil seal cover installed at the front end of the main shaft, and a self-aligning ball bearing installed at the rear end of the main shaft, a rear bottom plate, and a rear cover plate;

The rolling bearing group includes two angular contact ball bearings arranged back-to-back, which are used to bear the axial load and radial load, and serve as the support of the main shaft; the inner ring of the angular contact ball bearing is installed on the On one side of the main shaft, the outer ring of the angular contact ball bearing is installed in the front bearing seat; the front bearing seat is installed at the shaft outlet hole reserved on the water inlet channel of the water jet;

The rear bottom plate and the rear cover plate are respectively installed on both sides of the self-aligning ball bearing to fix the axial position of the self-aligning ball bearing;

The sealing assembly is used to isolate the lubricating oil working medium in the front bearing seat cavity and the water outside the cavity, and specifically includes a front oil seal, a rear oil seal and a sealing packing, and the front oil seal and the rear oil seal are installed on the front bearing. The sealing packing is located in the front bearing seat to prevent water from entering the bearing seat cavity; the front oil seal cover The plate and the front packing cover are respectively installed on the front and rear sides of the front bearing group, and are respectively used for fixing the front oil seal and the sealing packing.

Further, the main shaft is a solid long main shaft, and the material is 3Cr13, and the main shaft is processed by a surface nitriding process.

Further, the rolling bearing set is lubricated and cooled by oil.

Further, the lock nut for locking the inner ring of the rolling bearing group is a pair of locking round nuts.

Further, an underflow channel for adding lubricating oil is processed in the front bearing seat, which is connected to an external lubricating oil tank, and then through the height difference, flow rate and pressure control of the oil inlet and outlet, the lubricating oil can be in the closed system of the front bearing seat. The inner circulation flows, and the lubricating oil is always immersed in 40% of the bearing cavity when the rolling bearing set is working.

Further, the self-aligning ball bearing adopts ceramic material.

Further, the self-aligning ball bearing is located in the hub of the guide vane body of the water jet, and serves as a support for the main shaft.

Further, the lock nut for locking the impeller is a pair of anti-loosening round nuts.

Further, the impeller has 4 blades.

Further, the packing seal adopts polytetrafluoroethylene soft seal.

The beneficial effects of the present invention are as follows:

(1) The present invention overcomes the complexity of the existing support structure and the sealing structure and cannot be applied to compact shafts by simplifying the support structure and the sealing structure, and designing a dark channel in the bearing seat to maintain the circulation of the lubricating oil through an external oil tank. to the shortcomings of the structure. And after simplifying the support structure and the sealing structure, the shafting can still have good supporting effect and sealing effect, and the rolling bearing group can still obtain good lubricating and cooling effects.

(2) The rear end of the main shaft of the present invention adopts the rear bottom plate and the rear cover to replace the traditional bearing seat design, so that the entire shafting structure is more compact, and can adapt to the limited hub space of the small-sized water jet propulsion, disassembly and assembly Convenient and maintain good maintenance performance.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the shafting structure of a typical large water jet;

2 is a schematic diagram of the overall structure of the shafting structure of the present invention for a compact axial-flow water jet;

Figure 3 is a partial enlarged view of the front end of the main shaft;

Figure 4 is a partial enlarged view of the rear end of the main shaft;

Figure 5 is a cross-sectional view of the front bearing housing.

In the figure, the main shaft 1, the rolling bearing group 2, the front bearing seat 3, the positioning ring 4, the front oil seal cover plate 5, the front packing cover plate 6, the self-aligning ball bearing 7, the rear bottom plate 8, the rear cover plate 9, the lock nut pair 10. Sealing packing 11, front skeleton oil seal 12, rear skeleton oil seal 13, sealing ring 14, impeller 15, flat key 16, shaft sleeve 17, lock nut pair 2 18, guide vane body 19, water inlet channel 20, lubrication Oil underflow channel 21 , lubricating oil tank 22 .

Detailed ways

The present invention will be described in detail below according to the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become clearer.

The present invention is oriented towards a compact axial-flow water-jet propulsion, and provides a shafting structure for transmitting driving power, which is applied to the fields of fluid machinery and mechanical transmission. The specific technical scheme is as follows:

As shown in FIG. 2 , the shafting structure of the present invention for a compact axial-flow water jet specifically includes a main shaft 1, a rolling bearing group 2, a front bearing seat 3, a front sealing device, a self-aligning ball bearing 7, and a rear seal device and impeller 15.

The main shaft 1 is connected with the upper-level power output shaft through the driving flange (or coupling), and rotates under the action of driving power to transmit the driving power; the main shaft 1 is a solid long main shaft, the material is 3Cr13, and the surface is nitrided after processing. Process treatment; 3Cr13 material has good machinability. After heat treatment, it has high strength, excellent corrosion resistance, wear resistance and polishing performance. After surface nitriding process, it can further improve the surface hardness of spindle 1 , wear resistance, fatigue strength, anti-seizure, corrosion resistance, etc., are conducive to maintaining the working performance of the main shaft 1 at high speed and high power.

Rolling bearing set 2 is mainly used to bear axial load and radial load, and serves as the support of main shaft 1; rolling bearing set 2 includes a pair of angular contact ball bearings arranged back-to-back; It is locked on the front end side of the main shaft 1, and the interference fit of k6 is used between the inner ring of the rolling bearing group 2 and the main shaft 1; Fitting; the front bearing seat 3 is installed at the shaft outlet hole reserved on the water inlet channel of the water jet. The back-to-back bearing set can provide relatively high rigidity of the cantilever end, and the shaft is not easy to be stuck and damaged when it is heated and extended, which is suitable for the environment where the bearing space is small and it is not suitable for heat dissipation.

The front bearing seat 3, the positioning ring 4, the front oil seal cover plate 5, the front packing cover plate 6, the sealing packing 11, the front frame oil seal 12, the rear frame oil seal 13, and the sealing ring 14 together form the front sealing device of the solution of the present invention. As shown in Figure 3, it is used to isolate the lubricating oil working medium in the cavity of the front bearing seat 3 and the water outside the cavity. The front skeleton oil seal 12 and the rear skeleton oil seal 13 are installed in the front bearing seat 13 and are located on both sides of the rolling bearing group 2 respectively to prevent the lubricating oil from leaving the bearing seat cavity; the sealing packing 11 is located in the front bearing seat, and from the front The packing cover 6 is pressed tightly to prevent water from entering the bearing housing cavity. Compared with the large water jet propulsion, the front sealing device has been greatly simplified, and the axial length and overall volume have been greatly shortened, so as to adapt to the compact water jet propulsion.

PTFE soft sealing material has extremely low friction coefficient, self-lubrication, suitable for oil-free lubrication, good surface non-sticking, good mechanical properties in a wide temperature range of -196 ~ 260 ° C, and chemical corrosion resistance. , resistance to atmospheric aging, insulation, etc., the present invention uses the characteristics of the PTFE soft sealing material to make the sealing packing 11 to separate the water in the flow channel and the working cavity of the front bearing seat 3;

In the working cavity of the front bearing seat 3 , lubricating oil is filled between the front skeleton oil seal 12 and the rear skeleton oil seal 13 to lubricate and cool the rolling bearing set 2 . In the solution of the present invention, the sealing lip of the front skeleton oil seal 12 is in direct contact with the surface of the lock nut pair 10. Correspondingly, the surface of the pair of round nuts of the lock nut pair 10 needs to be processed with high precision to meet the sealing requirements; The simplified design greatly reduces the length of the front sealing device extending out of the flow channel, so that the volume of the water jet can be more compact;

The actual volume of the working cavity of the above simplified front bearing seat 3 is small, and the lubricating oil that can be accommodated is limited, so the present invention also adds a set of lubricating oil filling system, which is as follows: The present invention is in the front bearing seat 3. The lubricating oil underflow channel 21 is processed, and the inlet and outlet are arranged on the flange of the front bearing seat 3, forming a closed circuit of lubricating oil with the external lubricating oil tank 22, as shown in Figure 5; and pressure, so that the lubricating oil can circulate in the closed circuit, and keep the lubricating oil immersed in 40% of the bearing cavity when the rolling bearing set 2 is working, so as to optimize the working environment and performance of the rolling bearing set 2 and prolong the service life of the product;

The self-aligning ball bearing 7 is installed on the rear end side of the main shaft 1 and in the hub of the guide vane body 19 of the water jet propeller to support the main shaft 1; the inner ring of the self-aligning ball bearing 7 and the main shaft 1 adopts a k6 The interference fit, the H7 interference fit is used between the outer ring and the hub of the guide vane body 19; the self-aligning ball bearing 7 adopts a double-row ceramic self-aligning ball bearing; the ceramic bearing has corrosion resistance, long service life, self-lubricating without The performance characteristics such as extra lubricant are suitable for installation in the guide vane hub and other places where it is difficult to arrange the lubrication system, which can reduce the maintenance times of the self-aligning ball bearing 7 in the product life cycle; the ceramic bearing also provides a certain dry grinding performance, which can be used in It will not be damaged when idling in the air medium for a certain period of time, which broadens the use scene and environmental adaptability of the water jet; the self-aligning bearing also allows the main shaft to have a certain eccentricity (1°) for easy installation;

Usually, the traditional rear sealing device is composed of the rear bearing seat, the sealing ring, the skeleton oil seal, the rear sealing cover plate and other components, and can be simplified and decomposed into two parts: the bottom plate and the sealing base; Under most working conditions (except for extremely harsh environments such as a large amount of mud), the rear sealing device can no longer be installed, which greatly saves space; after sufficient simplification, the present invention uses the rear bottom plate 8 and the rear cover plate 9 to replace The traditional rear sealing device; the function of the rear bottom plate 8 is mainly to tighten the outer ring of the rear bearing and facilitate disassembly during maintenance (the guide vane hub is opened, and the plug is usually installed to seal it, and the bottom plate is pressed against the bottom plate from the rear end during maintenance, so as to prevent Push out the rear bearing); the flange outer edge of the rear cover plate 9 is flush with the hub of the guide vane body 19, that is, the flange outer edge of the rear cover plate 9 becomes a part of the hub of the guide vane body 19. This design is beneficial to It is convenient to arrange the threaded holes for fixing the rear cover plate 9, increase the diameter, depth and minimum wall thickness of the threaded holes, thereby improving the structural strength and reliability;

The impeller 15 is fixed on the corresponding position of the main shaft 1 through the flat key 16 , the shaft sleeve 17 and the pair of lock nuts 18 .

The lock nut pair 1 10 and the lock nut pair 2 18 are both composed of locking round nuts used in pairs.

Those of ordinary skill in the art can understand that the above are only preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still understand the Modifications are made to the technical solutions described in the foregoing examples, or equivalent replacements are made to some of the technical features. All modifications and equivalent replacements made within the spirit and principle of the invention shall be included within the protection scope of the invention.

Claims (7)

1. A shafting structure for a compact axial-flow water jet, characterized in that the shafting structure comprises a main shaft, an impeller, a support assembly, and a sealing assembly; The main shaft is connected with the upper-level power output shaft through a coupling, and rotates under the action of driving power; The impeller is connected to the main shaft by a key, and the two ends of the impeller are respectively locked by a shaft sleeve and a locking nut; the impeller rotates with the main shaft and generates a stable working water flow, thereby generating thrust; The support assembly includes a rolling bearing group, a front bearing seat, a front packing cover, a front oil seal cover installed at the front end of the main shaft, and a self-aligning ball bearing installed at the rear end of the main shaft, a rear bottom plate, and a rear cover plate; The rolling bearing group includes two angular contact ball bearings arranged back-to-back, which are used to bear the axial load and radial load, and serve as the support of the main shaft; the inner ring of the angular contact ball bearing is installed on the On one side of the main shaft, the outer ring of the angular contact ball bearing is installed in the front bearing seat; the front bearing seat is installed at the shaft outlet hole reserved on the water inlet channel of the water jet; The rear bottom plate and the rear cover plate are respectively installed on both sides of the self-aligning ball bearing to fix the axial position of the self-aligning ball bearing; The sealing assembly is used to isolate the lubricating oil working medium in the front bearing seat cavity and the water outside the cavity, and specifically includes a front oil seal, a rear oil seal and a sealing packing, and the front oil seal and the rear oil seal are installed on the front bearing. The sealing packing is located in the front bearing seat to prevent water from entering the bearing seat cavity; the front oil seal cover The plate and the front packing cover are respectively installed on the front and rear sides of the front bearing group, and are respectively used to fix the front oil seal and the sealing packing; The rolling bearing group is lubricated and cooled by oil; The front bearing seat is machined with an underflow channel for adding lubricating oil, which is connected to the external lubricating oil tank, and then the lubricating oil can be circulated in the closed system of the front bearing seat through the height difference, flow and pressure control of the oil inlet and outlet. , and keep the lubricating oil always submerged 40% of the bearing cavity when the rolling bearing set is working. 2. The shafting structure for a compact axial-flow water jet propeller according to claim 1, wherein the main shaft is a solid long main shaft, and the material is 3Cr13, and the main shaft is processed by surface infiltration Nitrogen process treatment. 3. The shafting structure for a compact axial water jet propeller according to claim 1, wherein the self-aligning ball bearing is made of ceramic material. 4. The shafting structure for a compact axial water jet propeller according to claim 1, wherein the self-aligning ball bearing is located in the hub of the vane body of the water jet as a support for the spindle. 5 . The shafting structure for a compact axial-flow water jet propeller according to claim 1 , wherein the locking nut for locking the impeller is a pair of locking round nuts. 6 . 6 . The shafting structure for a compact axial water jet propeller according to claim 1 , wherein the impeller has 4 blades. 7 . 7 . The shafting structure for a compact axial-flow water jet propeller according to claim 1 , wherein the packing seal adopts a polytetrafluoroethylene soft seal. 8 .

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