High-speed high-pressure large-flow fuel centrifugal pump and dismounting method thereof

Abstract

The application belongs to the technical field of centrifugal pumps, and particularly relates to a high-speed high-pressure large-flow fuel centrifugal pump and a dismounting method thereof. The designed fuel centrifugal pump is composed of a shaft impeller, a main shaft shell, a roller bearing, a bearing outer ring bushing, a bearing inner ring bushing, a ball bearing, a pressing plate, a locking nut, a transmission rod, an inlet shell, a plug cover, a circular stop block and a sealing assembly. Through integrated design of the impeller and the impeller shaft, the circumferential gap existing in the traditional structure does not exist in the circumferential direction of the impeller and the impeller shaft, and the wear problem caused by circumferential micro-motion of the impeller in operation is eliminated in structure, so that the problem that the reliability and service life of the high-speed high-pressure large-flow fuel centrifugal pump are not high can be effectively solved. Meanwhile, considering the actual engineering application characteristics, the application also proposes a dismounting method of the integrated design fuel pump, and the fuel pump can be dismounted by using a simple tool, the dismounting process is simple, the constituent parts are not damaged, and the application prospect is wide.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of centrifugal pump, especially relates to the design of a fuel centrifugal pump of an aero-engine fuel control system, and the high-speed, high-pressure and high-flow fuel centrifugal pump is used in an engine fuel system. BACKGROUND

[0002] At present, the fuel centrifugal pump used in an aero-fan (jet) engine has a high rotating speed (up to 30000r / min), a high outlet fuel pressure (up to 15MPa) and a large flow (up to 50000kg / h), and the driving power is up to about 300kw. Compared with the fuel centrifugal pump used before, in addition to the same rotating speed (about 30000r / min), the outlet fuel pressure is increased from about 7.5MPa to about 15MPa, the flow is increased from about 30000kg / h to about 50000kg / h, and the driving power of the fuel centrifugal pump is increased by more than three times. Under such a large load, the strength requirement of the structure of the centrifugal pump is very high, and considering the actual assembly difficulty and machining difficulty, the components are generally manufactured in parts and then assembled into an integral structure. The impeller and the impeller shaft of the traditional fuel centrifugal pump are generally connected through conventional and reliable spline, key and the like. For the high-speed, high-pressure and high-flow fuel centrifugal pump, it is found in practical application that the service life of these traditional centrifugal pump design structures is difficult to meet the specified requirements. SUMMARY

[0003] The present application aims at providing a high-speed, high-pressure and high-flow fuel centrifugal pump with an integrated design of an impeller and an impeller shaft. The impeller and the impeller shaft are designed in an integrated manner, which completely avoids the circumferential micro-motion between the impeller and the impeller shaft during operation, and greatly improves the reliability and service life of the fuel centrifugal pump.

[0004] Technical scheme: the present application provides a high-speed, high-pressure and high-flow fuel centrifugal pump with an integrated design of an impeller and an impeller shaft, which is composed of a shafted impeller, a main shaft shell, a roller bearing, a bearing outer ring bushing, a bearing inner ring bushing, a ball bearing, a pressing plate, a locking nut, a transmission rod, an inlet shell, a plug, a circular stopper and a sealing assembly.

[0005] The shafted impeller is integrally formed by a front-end impeller and a transmission shaft section; the transmission shaft section is designed as a stepped structure; the left end of the main shaft shell is fixed with the inlet shell, and the space between the two is used as an impeller installation space of the shafted impeller; the main shaft shell is provided with a first installation cavity for installing a larger diameter section of the transmission shaft, and a second installation cavity for assembling the roller bearing, the bearing outer ring bushing, the bearing inner ring bushing and the ball bearing.

[0006] The transmission shaft section of the impeller with shaft is installed into the main shaft shell through a hole on the main shaft shell and is supported in the main shaft shell by a roller bearing and a ball bearing, inner and outer rings of the roller bearing and the ball bearing are supported by bearing inner ring bushing and bearing outer ring bushing respectively, the outer ring of the ball bearing is pressed by a pressing plate and a screw, the inner ring of the ball bearing is locked by a locking nut, the left end face of the roller bearing is abutted against the stepped end face of the transmission shaft section of the impeller with shaft to limit the radial and axial positions of the impeller with shaft; the circular block is installed on the left side of the roller bearing; the cross section of the circular block is L-shaped annular structure, the outer ring root of the circular block is abutted against the outer ring of the roller bearing to limit the left side of the roller bearing in the axial direction; the inner ring diameter of the circular block is slightly larger than the outer diameter of the shaft section of the impeller with shaft and slightly smaller than the outer diameter of the inner ring of the roller bearing, a certain gap is left between the inner ring of the circular block and the side surface of the inner ring of the roller bearing; the outer ring thickness D of the circular block also satisfies D+L1=L2-H2; wherein, L1 is the length of the first installation cavity of the main shaft shell, L2 is the length of the larger diameter section of the transmission shaft section of the impeller with shaft, and H2 is the gap between the impeller with shaft 1 and the end of the main shaft shell 2 when working.

[0007] The main shaft shell and the transmission shaft neck of the impeller with shaft are provided with a sealing assembly; the left end of the impeller with shaft is sealed by a plug and a sealing ring to ensure that the imported fuel cannot flow to the right end through the inner hole of the impeller with shaft; the right end of the impeller with shaft is provided with a transmission rod, and external power drives the impeller with shaft to rotate and work; when the high-speed high-pressure large-flow fuel centrifugal pump works, the impeller with shaft is driven to rotate by the transmission rod, fuel enters from the "RYJ" port, flows out from the "RYC" port after being pressurized by the impeller with shaft, and in this process, part of the fuel after being pressurized flows back to the "RYJ" port through the gap "H1", and the other part of the fuel flows to the "DP" cavity through the gap "X" between "H2", ΦB1 and ΦC1 first, the "DP" cavity communicates with the "RYJ" port through the "HYG" flow channel, ensures that the pressure of the "DP" cavity is close to that of the "RYJ" port, and ensures that the sealing assembly works in a lower fuel pressure environment; lubricating oil enters the main shaft shell from the "HYJ" port, flows through the internal flow channel, and then cools and lubricates the roller bearing and the ball bearing through the "PZ1" and "PZ2" two nozzles respectively, and the lubricated lubricating oil flows out of the main shaft shell through the "HYC" port.

[0008] Further, the first installation cavity of the main shaft shell is a stepped structure, the diameter near the impeller side is slightly smaller, and the larger diameter installation cavity is provided with a sealing assembly to divide the two sides of the installation cavity.

[0009] Further, the sealing assembly comprises shaft seals and a spacer, and the spacer is installed between the two shaft seals.

[0010] Further, the two shaft seals are both ring-shaped structures with U-shaped cross section, and the U-shaped openings of the two shaft seals are arranged in opposite directions in the axial direction during installation.

[0011] Further, the import shell is equipped with an O-shaped sealing ring, and is screwed to the left end of the main shaft shell, so that the impeller part of the impeller with shaft works in the cavity formed by the import shell and the main shaft shell.

[0012] Further, the impeller with shaft is a variable-diameter hollow structure, and the impeller end is sealed by a plug; the diameter of the transmission shaft section of the impeller with shaft gradually increases from the impeller end to the tail end.

[0013] Further, the inner cavity of the transmission shaft of the impeller with shaft is engaged with the transmission rod through gears to realize transmission.

[0014] The application also provides a disassembling method for the high-speed high-pressure large-flow fuel centrifugal pump, which adopts a set of disassembling tool, and the disassembling tool comprises a disassembling sleeve and a sleeve shaft, wherein the disassembling sleeve is a flange-shaped, tapered thin-walled circular elastic structural member designed according to the inner hole of the circular block, and a plurality of grooves are formed on the taper in the axial direction, so that the size of the flange can be reduced after a circumferential force is applied; the sleeve shaft is a stepped shaft, the front end of which is a larger-diameter conical guide head, and the rear end of which is a shaft section.

[0015] The disassembling process of the fuel centrifugal pump comprises the following steps.

[0016] First step: the import shell, screw, pressing plate, locking nut and transmission rod are disassembled;

[0017] Second step: the left end surface of the main shaft shell is used as a supporting force receiving surface, a force F1 is applied, and another force F2 is applied to the right end surface of the impeller with shaft to the left; in this process, the left end surface of the roller bearing inner ring is attached to the right end surface of the circular block, until the roller bearing inner ring is pressed out of the shaft neck of the impeller with shaft;

[0018] Third step: the circular block is used as a support to disassemble the roller bearing, bearing outer ring bushing, bearing inner ring bushing and ball bearing; in this process, the disassembling tool is used, the disassembling sleeve is inserted into the main shaft shell mounting cavity along one end of the import shell, a circumferential force is applied to the disassembling sleeve to reduce the size of the flange to the size that can be put into the roller bearing inner ring, when the right end surface of the flange moves to the left and passes over the left end surface of the circular block, the circumferential force acting on the circular block is released, and the size of the flange is restored; at this time, the right end surface of the flange is attached to the left end surface of the circular block; the sleeve shaft is inserted into the inner hole of the disassembling sleeve; the force F3 is continuously applied to the left end of the sleeve shaft, and the force F4 is also applied to the right end of the main shaft shell, so that the circular block, the roller bearing, the bearing outer ring bushing, the bearing inner ring bushing and the ball bearing are taken out of the main shaft shell;

[0019] Fourth step: the same method is adopted, and the disassembling tool with a suitable size is used to take out the shaft seal; the disassembling of the whole fuel pump is completed.

[0020] Beneficial technical effect: After long-term research and demonstration, it is found that the traditional fuel centrifugal pump impeller and the impeller shaft are connected by spline or key, and there is a gap between the impeller and the impeller shaft in the circumferential direction, which causes a large deviation between the instantaneous speed of the impeller and the impeller shaft when the fuel centrifugal pump starts and stops working quickly, and a circumferential micro-motion will be generated between the impeller and the impeller shaft; the right end face of the impeller mounted on the outer circle of the impeller shaft ΦA connected by two keys and compressed by a nut will rub and wear with the adjusting gasket (or the left end face of the impeller will rub and wear with the nut), when the wear exceeds the required assembly gap, the high-speed rotating impeller will easily collide and wear with the shell, causing the fuel centrifugal pump to fail, and seriously shortening the service life.

[0021] The present application integrates the impeller and the impeller shaft, and there is no circumferential gap between the impeller and the impeller shaft in the circumferential direction, which eliminates the wear problem caused by circumferential micro-motion during the operation of the impeller, and effectively solves the problem of low reliability and short service life of high-speed high-pressure large-flow fuel centrifugal pumps; at the same time, considering the actual engineering application characteristics, the present application also provides a disassembly method for the fuel pump with integrated impeller and impeller shaft, which can realize the disassembly of the fuel pump by using simple tooling, and the disassembly process is simple and does not damage the components, which has a broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 is a structural diagram of a high-speed high-pressure large-flow fuel centrifugal pump with integrated impeller and impeller shaft of the present application;

[0024] Figure 2 is a schematic diagram of a traditional fuel centrifugal pump impeller (YL) and an impeller shaft (YLZ) connected by a key (PJ);

[0025] Figure 3 is a structural diagram of a main shaft shell 2;

[0026] Figure 4 is a schematic diagram of a shaft impeller structure;

[0027] Figure 5 is a schematic diagram of an inlet shell 15 structure;

[0028] Figure 6 is a schematic diagram of a drive rod 11 structure;

[0029] Figure 7Structure diagram of the cover 16;

[0030] Figure 8 Structure diagram of the lock nut 10;

[0031] Figure 9 Structure diagram of the bearing inner ring bushing 6;

[0032] Figure 10 Structure diagram of the bearing outer ring bushing 5;

[0033] Figure 11 High-speed high-pressure large-flow fuel centrifugal pump with integrated impeller and impeller shaft design in disassembly process (remove the inlet shell 15, screw 9, pressing plate 8, lock nut 10 and transmission rod 11);

[0034] Figure 12 High-speed high-pressure large-flow fuel centrifugal pump with integrated impeller and impeller shaft design in disassembly process (remove the impeller 1 with shaft);

[0035] Figure 13 Special tool for disassembling the circular stop block 18, roller bearing 4, bearing outer ring bushing 5, bearing inner ring bushing 6 and ball bearing 7;

[0036] Figure 14 Special tool for disassembling the circular stop block 18, roller bearing 4, bearing outer ring bushing 5, bearing inner ring bushing 6 and ball bearing 7;

[0037] Figure 15 Front shaft neck torsion stress calculation diagram for integrated impeller and impeller shaft design;

[0038] Figure 16 Back shaft neck torsion stress calculation diagram for integrated impeller and impeller shaft design. DETAILED DESCRIPTION

[0039] To make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, any person skilled in the art can obtain all other embodiments without creative work, which are within the protection scope of the present application.

[0040] The features and illustrative embodiments of various aspects of the present application are described below in detail. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one of ordinary skill in the art that the present application can be practiced without some or all of these specific details. In other instances, well known structures and functions have not been described in detail in order to not obscure the understanding of this description. The description of the embodiments is merely meant to provide a better understanding of the present application. The present application is not limited to any particular setting and method as set forth below, but covers any modifications, equivalents, and alternatives falling within the spirit of the present application. In the drawings and the following description, well-known structures and techniques have not been shown or described in detail in order not to obscure the understanding of this description.

[0041] It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict, and each embodiment can be referred to and cited by the other embodiments. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0042] The high-speed high-pressure large-flow fuel centrifugal pump with integrated design of impeller and impeller shaft according to the present application has a structure as shown in Figure 1 The high-speed high-pressure large-flow fuel centrifugal pump with integrated design of impeller and impeller shaft according to the present application has a structure as shown in

[0043] In Figure 1In the middle, the ΦC1 section of the shafted impeller 1 is installed into the main shaft housing 2 through the ΦB1 hole on the main shaft housing 2 and is supported in the main shaft housing 2 by the roller bearing 4 and the ball bearing 7, the inner and outer rings of the roller bearing 4 and the ball bearing 7 are supported by the bearing inner ring bushing 6 and the bearing outer ring bushing 5 respectively, the outer ring of the ball bearing 7 is pressed by the pressing plate 8 and the screw 9, the inner ring of the ball bearing 7 is locked by the locking nut 10, the radial and axial positions of the shafted impeller 1 are limited; at the same time, in order to facilitate disassembly and assembly, a circular block 18 is designed and installed on the left side of the roller bearing 4; the circular block 18 is in L-shaped annular structure, the outer ring root of the circular block 18 abuts against the outer ring of the roller bearing 4 to limit the left side of the roller bearing 4 in the axial direction; the inner ring diameter of the circular block 18 is slightly larger than the outer diameter of the shafted impeller shaft section and slightly smaller than the inner ring outer diameter of the roller bearing 4, a certain gap is left between the inner ring of the circular block and the side surface of the roller bearing inner ring. The ΦB2 hole of the main shaft housing 2 and the ΦC1 shaft neck of the shafted impeller 1 are installed with two shaft seals 3, and the spacer sleeve 12 is installed between the shaft seals; the left end of the shafted impeller 1 is sealed by the plug 16 and the O-shaped sealing ring 17 to ensure that the imported fuel cannot flow to the right end through the inner hole of the shafted impeller 1; the right end of the shafted impeller 1 is installed with the transmission rod 11, and the external power drives the shafted impeller 1 to rotate and work through the transmission rod 11; the inlet housing 15 is installed on the left end of the main shaft housing 2 through the screw 14 after the O-shaped sealing ring 13 is installed, so that the impeller part of the shafted impeller 1 works in the cavity formed by the inlet housing 15 and the main shaft housing 2; in order to facilitate assembly, a stepped groove is opened at the right end of the main shaft housing 2 for installing and fixing the pressing plate 8.

[0044] In the design of the application, in order to realize the accurate installation of the shafted impeller 1 in the installation cavity of the main shaft shell 2, on the one hand, the drive shaft section of the shafted impeller 1 is designed as a stepped structure including two diameter sections, and the diameter of the section close to the impeller is slightly larger; and on the other hand, a circular block 18 is designed and installed at the root of the larger diameter installation cavity of the main shaft shell 2; the design of the circular block 18 can effectively ensure the gap between the front end of the shafted impeller 1 and the shell during installation, and facilitate the disassembly and assembly of the fuel pump later; the circular block 18 is designed as a ring structure with an L-shaped cross section, the outer ring of the circular block 18 has the same diameter as the outer ring of the roller bearing 4, and the inner ring of the circular block 18 has a slightly larger diameter than the outer diameter of the larger diameter section of the drive shaft section of the shafted impeller 1 and is slightly smaller than the inner diameter of the outer ring of the roller bearing 4; at the same time, the thickness D (i.e. the thickest position of the L-shaped cross section) of the outer ring of the circular block 18 satisfies D+L1=L2-H2; wherein L1 is the length of the first installation cavity of the main shaft shell 2, L2 is the length of the larger diameter section of the drive shaft section of the shafted impeller 1, and H2 is the gap between the shafted impeller 1 and the end of the main shaft shell 2 during work; such design can ensure that the shafted impeller 1 is inserted into the installation cavity of the main shaft shell 2 to a limited position during installation, at which time the right end surface of the impeller of the shafted impeller 1 abuts against the left end surface of the installation cavity of the main shaft shell 2; then the roller bearing 4, the bearing outer ring bushing 5, the bearing inner ring bushing 6, the ball bearing 7 and the pressing plate 8 are sequentially sleeved along the installation cavity of the main shaft shell 2; when the outer ring of the roller bearing 4 abuts against the outer ring of the circular block 18, the outer ring of the roller bearing 4 is pressed to the limit position, and the inner ring of the roller bearing 4 abuts against the stepped end surface of the drive shaft section of the shafted impeller 1; during the pressing process, the roller bearing 4 pushes the shafted impeller 1 to move leftward by H2; so that the position of the shafted impeller 1 in the installation cavity is ensured, i.e. the gap between the front end of the impeller and the inlet shell 15 is H1, and the gap between the rear end of the impeller and the end of the main shaft shell 2 is H2.

[0045] During the work of the high-speed high-pressure large-flow fuel centrifugal pump, the shafted impeller 1 is driven to rotate by the drive rod 11, fuel enters from the "RYJ" port, is pressurized by the shafted impeller 1 and then flows out from the "RYC" port, and in this process, part of the pressurized fuel flows back to the "RYJ" port through the gap "H1", and the other part of the pressurized fuel flows to the "DP" cavity through the gap "X" between "H2" and ΦB1, ΦC1 first, the "DP" cavity communicates with the "RYJ" port through the "HYG" flow channel, so as to ensure that the pressure of the "DP" cavity is close to that of the "RYJ" port, and to ensure that the shaft seal 3 works in a low fuel pressure environment; lubricating oil enters the main shaft shell 2 from the "HYJ" port, is cooled and lubricated through the internal flow channel and then flows out of the main shaft shell 2 through the "PZ1" and "PZ2" two nozzles for cooling and lubricating the roller bearing 4 and the ball bearing 7.

[0046] The integrated design of the impeller and impeller shaft not only eliminates the wear problem caused by circumferential fretting during impeller operation from a structural perspective, but also allows for a significant increase in the journal diameter. Furthermore, it eliminates the need to consider lubrication between the impeller and impeller shaft, as well as any additional sealing designs required for lubrication. For example, in... Figure 2 In the original design, the impeller (YL) and impeller shaft (YLZ) are connected by a flat key (PJ). At this point, the journal diameter (ΦA) is Φ20mm, which is the weakest point of the impeller shaft (YLZ). After the integrated design, the journal size at ΦA in the original structure increased from Φ20 to Φ37. After deducting the influence of the hollow groove size ΦC2 (Φ17), the torsional resistance of the shaft at this location increased by 6 times. This significantly improves the product's service life and reliability. In traditional centrifugal pumps, due to assembly and disassembly limitations, the impeller and impeller shaft are connected by a flat key (PJ) or spline. This connection method requires consideration of lubrication at the connection point and the heat generated during the meshing motion. The design incorporates oil from the DP chamber, which serves both lubrication and heat dissipation during operation. However, this design also presents sealing challenges, particularly since the connecting cavity between the impeller shaft and the drive rod cannot be made into a completely hollow cavity, making it difficult to achieve weight reduction to some extent.

[0047] While the integrated impeller and impeller shaft design is a relatively common design approach, significantly improving the lifespan and reliability of high-speed, high-pressure, high-flow fuel centrifugal pumps, its limited practical application in current engineering projects stems primarily from the higher assembly requirements imposed by this integrated design. For instance, ensuring proper spatial positioning of the impeller within the mounting cavity—specifically, maintaining a clearance of H1 between the impeller's front end and the inlet housing, and H2 between the impeller's rear end and the main shaft housing—is crucial. Poor control of these clearances can drastically impact product lifespan. Furthermore, it presents challenges for disassembly and maintenance, particularly for high-speed, high-pressure, high-flow fuel centrifugal pumps. This is a significant reason why such integrated designs are rarely used in practical applications within the industry. Figure 1 As shown, during disassembly, the inlet housing 15 and locking nut 10 must be removed first, and then the impeller 1 with shaft must be pressed out from right to left. During this process, due to the certain interference fit between the inner ring of the roller bearing and the journal, the inner ring of the roller bearing 4 will move to the left along with the impeller 1 with shaft, first damaging the shaft seal 3 until the inner ring of the roller bearing 4 abuts against the right end face of the ΦB1 hole on the main shaft housing 2. Only then can the inner ring of the roller bearing 4 be removed from the impeller 1 with shaft. Each disassembly will damage the shaft seal 3. After removing the impeller 1 with shaft, other parts and ball bearings 7 are also difficult to disassemble.

[0048] This invention proposes a high-speed, high-pressure, high-flow-rate fuel centrifugal pump with an integrated impeller and impeller shaft design. It also fully considers assembly and disassembly issues. In practical implementation, the method for solving the disassembly problem is as follows:

[0049] First step: remove the inlet housing 15, screw 9, pressure plate 8, lock nut 10 and transmission rod 11, see Figure 11 .

[0050] Second step: take the left end face of the main shaft housing 2 as the supporting force surface, apply force F, and at the same time, press the right end face of the impeller 1 with force F to the left. During this process, the left end face of the inner ring of the roller bearing 4 is in contact with the right end face of the circular block 18 ( Figure 12 -a), until the inner ring of the roller bearing 4 is pressed out of the shaft neck of the impeller 1 ( Figure 12 -b). Of course, in actual implementation, the size of the applied force on both sides can be determined according to specific circumstances.

[0051] Third step: take the circular block 18 as the support, and remove the roller bearing 4, bearing outer ring bushing 5, bearing inner ring bushing 6 and ball bearing 7. A special tool (TZGZ) is needed during this process, which is composed of a special sleeve (TZGZ-T) and a special sleeve shaft (TZGZ-Z), as shown in Figure 13 . Among them, TZGZ-T is a flanged, tapered thin-walled elastic part designed according to the inner hole of the circular block 18. A number of grooves are machined on the cone in the axial direction. After applying a circumferential force, the flange size can be reduced; TZGZ-Z is a stepped shape, which functions to insert the tapered outer circle into the left end inner hole of the special sleeve, so that the flange on the special sleeve will not have a size reduction phenomenon during the force process, realizing the disassembly function.

[0052] The disassembly method is shown in Figure 14 . The specific process is as follows: apply a circumferential force to the special sleeve (TZGZ-T) to reduce the size of the flange to the size that can be put into the inner ring of the roller bearing 4. When the right end face of the flange moves to the left and passes over the left end face of the circular block 18, release the circumferential force acting on the circular block 18, and the flange size returns to its original size. The right end face of the flange is in close contact with the left end face of the circular block 18; insert the special sleeve shaft (TZGZ-Z) into the inner hole of the special sleeve (TZGZ-T); apply force F3 to the left end of the sleeve shaft (TZGZ-Z), and apply force F4 to the right end of the main shaft housing 2. Figure 15 Take out the circular block 18, roller bearing 4, bearing outer ring bushing 5, bearing inner ring bushing 6 and ball bearing 7 from the main shaft housing 2.

[0053] Fourth step: use the same method and appropriate size similar tools to remove the shaft seal 3.

[0054] In order to ensure that the disassembly process does not damage the fuel pump components, the disassembly process of the fuel centrifugal pump is carried out on the same horizontal platform, and the coaxiality during the disassembly process needs to be ensured.

[0055] Example: Taking a high-speed, high-pressure, high-flow-rate fuel centrifugal pump as an example, its rotational speed is 30,000 r / min, inlet fuel pressure is 0.5 MPa, outlet fuel pressure is 15 MPa, and flow rate is up to 50,000 kg / h. Before the impeller and impeller shaft were integrated, the journal dimension at ΦA was Φ20; after the impeller and impeller shaft were integrated, the journal dimension increased to Φ37 (the empty groove dimension is Φ17). The torsional stress at the journal before and after the improvement was calculated to evaluate the beneficial effects of the improvement.

[0056] Calculate the power of the impeller:

[0057] In the formula: P----power of the impeller (W), μ----hydraulic efficiency of the high-speed, high-pressure, high-flow fuel centrifugal pump, which is taken as 0.85 here.

[0058] Calculate the torque borne at the impeller journal:

[0059]

[0060] Where: T----torque borne at the impeller journal (Nm), μ----hydraulic efficiency of high-speed, high-pressure, high-flow fuel centrifugal pump, taken as 0.85 here.

[0061] Calculate the torsional stress τ at the impeller journal:

[0062] Before integrated design:

[0063] like Figure 15 As shown, assuming the torsional stress on the journal surface is τ1, the stress distribution on the journal cross-section is as follows:

[0064] In the formula: R----journal radius (m), r----radius of any point on the journal section (m), τ----stress distribution expression of the journal cross section.

[0065] The calculated value is τ1 = 63.7 (MPa).

[0066] After adopting the integrated design of this invention:

[0067] like Figure 16 As shown, let the torsional stress on the inner surface of the journal be τ2 and the torsional stress on the outer surface be τ3. Then the stress distribution on the journal cross section is: τ=100rτ3-100rτ2+1.85τ2-0.85τ3. According to the condition that the straight line passes through the origin of the coordinate system, when r=0, τ=0, so τ2=0.46τ3. Therefore, τ=54rτ3.

[0068]

[0069] In the formula: r----radius of any point on the journal section (m), τ----stress distribution expression of the journal cross section.

[0070] The calculated value is τ3 = 10.53 (MPa).

[0071] Calculation results show that after the impeller and impeller shaft are integrated into a single design, the torsional stress at the journal is reduced by 83.46% under the same operating conditions. This integrated design avoids wear caused by circumferential fretting of the impeller and impeller shaft during operation, improving the load-bearing capacity at the journal and the reliability of the fuel pump. Therefore, the integrated design eliminates the circumferential clearance present in traditional structures, structurally eliminating wear caused by circumferential fretting during impeller operation. This effectively solves the problem of low reliability and service life of high-speed, high-pressure, high-flow-rate fuel centrifugal pumps. Combined with the disassembly and assembly method specifically designed in this invention, it has significant engineering application prospects.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A high speed, high pressure, high flow fuel centrifugal pump characterized by, The impeller with shaft, the main shaft shell, the roller bearing, the bearing outer ring bushing, the bearing inner ring bushing, the ball bearing, the pressing plate, the locking nut, the transmission rod, the inlet shell, the plug, the circular block and the sealing assembly are composed; The impeller with shaft includes a front end impeller and a transmission shaft section, which are integrally formed; the transmission shaft section is designed as a stepped structure; the left end of the main shaft shell is fixed with the inlet shell, and the space between the two is used as an impeller installation space of the impeller with shaft; the main shaft shell is provided with a first installation cavity for installing a larger diameter section of the transmission shaft section and a second installation cavity for assembling the roller bearing, the bearing outer ring bushing, the bearing inner ring bushing and the ball bearing; the first installation cavity of the main shaft shell is a stepped structure, and the diameter of the side close to the impeller is slightly smaller; the larger diameter installation cavity is provided with a sealing assembly, which divides the larger diameter installation cavity into two cavities, and the left side of the sealing assembly is a "DP" cavity; The transmission shaft section of the impeller with shaft is installed into the main shaft shell through a hole in the main shaft shell and is supported by the roller bearing and the ball bearing in the main shaft shell; the inner and outer rings of the roller bearing and the ball bearing are supported by the bearing inner ring bushing and the bearing outer ring bushing respectively; the outer ring of the ball bearing is pressed by the pressing plate and the screw, and the inner ring of the ball bearing is locked by the locking nut; the left end face of the roller bearing abuts against the stepped end face of the transmission shaft section of the impeller with shaft, so as to limit the radial and axial positions of the impeller with shaft; the circular block is installed on the left side of the roller bearing; the cross section of the circular block is an L-shaped ring structure; the root of the outer ring of the circular block abuts against the outer ring of the roller bearing, so as to limit the left side of the roller bearing in the axial direction; the inner ring diameter of the circular block is slightly larger than the outer diameter of the shaft section of the impeller with shaft and slightly smaller than the outer diameter of the inner ring of the roller bearing; a certain gap is left between the inner ring of the circular block and the side face of the inner ring of the roller bearing; the outer ring thickness D of the circular block also satisfies D+L1=L2-H2; wherein, L1 is the length of the first installation cavity of the main shaft shell; L2 is the length of the larger diameter section of the transmission shaft section of the impeller with shaft; H2 is the gap between the end of the main shaft shell and the impeller with shaft when the impeller with shaft works; The sealing assembly is installed at the transmission shaft neck of the main shaft shell and the impeller with shaft; the left end of the impeller with shaft is plugged by the plug matched with the sealing ring, so as to ensure that the inlet fuel does not flow to the right end through the inner hole of the impeller with shaft; the right end of the impeller with shaft is provided with the transmission rod, and the external power drives the impeller with shaft to rotate and work through the transmission rod; The fuel inlet is defined as "RYJ" port, the fuel inlet is located at the center of the inlet shell, the fuel outlet is "RYC" port, the fuel outlet is located at the lower end of the main shaft shell; the lubricating oil inlet is "HYJ" port, the lubricating oil outlet is "HYC" port, the gap between the inlet shell and the front end of the impeller with shaft is gap "H1", and the flow channel between the "DP" cavity and the fuel inlet is "HYG" flow channel. When the high-speed, high-pressure and high-flow fuel centrifugal pump is working, the impeller with shaft is driven to rotate by the driving rod, fuel enters from "RYJ" port, and flows out from "RYC" port after being pressurized by the impeller with shaft, in the process, part of the fuel after being pressurized flows back to "RYJ" port through gap "H1", and the other part of the fuel after being pressurized flows to "DP" cavity through gap "H2" and gap "X" between the first installation cavity of the main shaft shell and the larger diameter section of the impeller with shaft, "DP" cavity communicates with "RYJ" port through "HYG" flow channel, so that the pressure of "DP" cavity is similar to that of "RYJ" port, and the sealing assembly works in a lower fuel pressure environment; lubricating oil enters the main shaft shell from "HYJ" port, and then flows out from the main shaft shell through "HYC" port after passing through the internal flow channel and then passing through two nozzles "PZ1" and "PZ2" to cool and lubricate the roller bearing and the ball bearing respectively.

2. A high speed high pressure high flow fuel centrifugal pump as claimed in claim 1 wherein, The sealing assembly comprises shaft seals and a spacer.

3. A high speed high pressure high flow fuel centrifugal pump as claimed in claim 2 wherein, The two shaft seals are both ring-shaped structures with U-shaped cross sections, and the U-shaped openings of the two shaft seals are arranged in opposite directions along the axial direction.

4. A high speed high pressure high flow fuel centrifugal pump as claimed in claim 1 wherein, After the O-shaped sealing ring is installed on the inlet shell, the inlet shell is screwed to the left end of the main shaft shell, so that the impeller part of the impeller with shaft works in the cavity formed by the inlet shell and the main shaft shell.

5. A high speed high pressure high flow fuel centrifugal pump as claimed in claim 1 wherein, A stepped groove is formed in the right end of the main shaft shell for mounting and fixing the pressing plate.

6. A high speed high pressure high flow fuel centrifugal pump as claimed in claim 5 wherein, The impeller with shaft is a hollow structure with variable diameters, and the impeller end is blocked by a plug; the diameter of the transmission shaft section of the impeller with shaft gradually increases from the impeller end to the tail end.

7. A high speed high pressure high flow fuel centrifugal pump as claimed in claim 6 wherein, The inner cavity of the transmission shaft of the impeller with shaft is engaged with the driving rod through gears to realize transmission.

8. The dismantling method of the high-speed, high-pressure, high-flow-rate fuel centrifugal pump as described in any one of claims 1 to 7, characterized in that, The disassembly method adopts a set of disassembly tool, and the disassembly tool comprises a disassembly sleeve and a sleeve shaft, wherein the disassembly sleeve is a flange-shaped, tapered thin-walled circular elastic structure with a hole in the circular block, and a plurality of grooves are formed on the tapered body in the axial direction, so that the size of the flange can be reduced after a circumferential force is applied; the sleeve shaft is a stepped shaft with a larger diameter conical guide head at the front end and a shaft section at the rear end; The disassembly process of the fuel centrifugal pump comprises the following steps: First step: remove the inlet shell, screw, pressing plate, locking nut and driving rod; Second step: take the left end surface of the main shaft shell as a supporting force receiving surface, and apply a force F1 and another force F2 to the right end surface of the impeller with shaft to the left; in this process, the left end surface of the inner ring of the roller bearing is in contact with the right end surface of the circular block, and the inner ring of the roller bearing is pressed out of the shaft neck of the impeller with shaft until the inner ring of the roller bearing is pressed out of the shaft neck of the impeller with shaft; Third step: with the round block as support, disassemble the roller bearing, bearing outer ring bushing, bearing inner ring bushing and ball bearing; in this process, use the disassembly tool to insert the disassembly sleeve into the main shaft housing installation cavity along the inlet housing one end, apply a circumferential force to the disassembly sleeve to reduce the size of the flange to be able to put into the roller bearing inner ring, when the right end of the flange moves left and passes the left end of the round block, release the circumferential force acting on the round block, the size of the flange is restored; at this time, the right end of the flange is attached to the left end of the round block; then insert the sleeve shaft into the disassembly sleeve hole; continue to apply force F3 to the left end of the sleeve shaft, at the same time, apply force F4 to the right end of the main shaft housing, take out the round block, roller bearing, bearing outer ring bushing, bearing inner ring bushing and ball bearing from the main shaft housing; Fourth step: use the same method, use the appropriate size of the disassembly tool to take out the shaft seal; complete the disassembly of the entire fuel centrifugal pump.

9. The method of disassembly of the high-speed high-pressure high-flow fuel centrifugal pump according to claim 8, characterized in that, The fuel centrifugal pump disassembly process is carried out on the same horizontal platform to ensure the coaxiality during disassembly.

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