Long-life fracturing pump crankshaft assembly device

Abstract

The invention discloses a fracturing pump crankshaft assembly device with long service life, which relates to the technical field of fracturing equipment, and comprises a rolling bearing, a crankshaft, a helical gear and a bolt, the crankshaft can adopt an integral structure or a combined structure, two main journals on two sides of a middle crank pin are respectively provided with a concentric flange plate, and the flange plates are connected with the rolling bearing. The two bevel gears are symmetrically installed on the flange plate, the input torque of the bevel gears is transmitted to the crankshaft through the flange plate, the axial force of the bevel gears is borne by the middle crank pin, and the phenomena that due to the fact that herringbone gears are intensively arranged on one side of the middle crank pin, loads of the crank pins are uneven, and the torque and the bending moment of the middle crank pin are maximum are avoided. And the phenomena that the whole crankshaft bears the axial load and each crank pin bears the additional bending moment due to the fact that the two bevel gears are installed at the two ends of the crankshaft are avoided, the crank pins of the crankshaft assembly are balanced in load, and the crankshaft is high in strength, long in service life and convenient to machine.

Description

Technical Field

[0001] The present invention relates to the technical field of fracturing equipment, and particularly relates to a long-life fracturing pump crankshaft assembly device. Background Art

[0002] Fracturing is one of the key measures for increasing oil and gas production. A fracturing pump is the core equipment for fracturing operations. The working principle of the fracturing pump adopts a plurality of parallel crank-slider mechanisms with a certain motion phase difference. The crank of each crank-slider mechanism is arranged on the same shaft, constituting the crankshaft of the fracturing pump. The life of the crankshaft is the key component determining the overall life of the fracturing pump. The power required for the rotation of the crankshaft is usually input by a gear or a worm wheel installed on the crankshaft. In the early fracturing pumps, the installation position of the gear or the worm wheel on the crankshaft was generally in the middle position of the crankshaft. In order to obtain a relatively stable displacement and discharge pressure, the fracturing pump adopts an odd number of cylinders of 3, 5 or 7, that is, the crankshaft has 3, 5 or 7 cranks. When the input power on the crankshaft is transmitted to the cranks on both sides, the middle crank bears the maximum torque. In addition, due to the large width of the gear or the worm wheel, the position where the gear or the worm wheel is arranged cannot be provided with a supporting main journal, so that the crankshaft bears a large bending moment in the middle part. Therefore, the strength of the middle part is the lowest and the fatigue life is the shortest. In order to improve the loading condition of the crankshaft, in recent years, the crankshaft of the fracturing pump has more often adopted a structure with gears arranged at both ends of the crankshaft, making the loading condition of the crankshaft more uniform. In order to achieve a lower working stroke frequency of the fracturing pump, a relatively large transmission ratio (generally about 6-7) is often adopted between the gear on the crankshaft and the small gear meshing with it. In order to ensure the smoothness of the gear transmission, the two gears adopt helical gears with large helix angles and opposite helix directions. Therefore, the crankshaft will also be subjected to a huge axial pressure or tension. The cranks at both ends have to transmit a large torque and bear a large axial force, and their fatigue life may be lower than that of the crankshaft with gears arranged in the middle position of the crankshaft. The existing crankshaft generally adopts a casting or integral forging blank, and then is machined on a special lathe and grinder. The processing technology is complex and the cost is high.

[0003] For example, in a Chinese patent document, the publication date is April 2, 2014, the publication number is CN203515987U, and the name is a utility model patent for a five-cylinder pump. The five-cylinder pump includes a frame, a crankshaft arranged on the frame, a motor, and a pinion shaft connected to the motor; pinions are provided at both ends of the pinion shaft; bearings for supporting the crankshaft are provided on the crankshaft of the five-cylinder pump; two helical gears are provided at both ends of the crankshaft, and the helix directions of the helical gear teeth are opposite. A shrink disc is used to connect the helical gear and the crankshaft; a stepped hole is provided on the end face of the helical gear. The large hole of the stepped hole is the shrink disc installation hole, and the small hole of the stepped hole is the installation positioning hole of the crankshaft. The small hole of the stepped hole is located at the inner end face of the helical gear; a pressing plate is provided on the outer end face of the helical gear, and the pressing plate is connected to the helical gear by bolts and abuts against the bolts on the outer end face of the shrink disc; a kidney-shaped hole is provided on the end face of the helical gear, and the bolts pass through the kidney-shaped hole to connect the helical gear and the crankshaft; the helical gear and the pinion on the crankshaft mesh and drive each other. In order to overcome the above-mentioned disadvantages of the crankshaft of the fracturing pump, a long-life fracturing pump crankshaft assembly device of the present invention is specifically proposed. Summary of the Invention

[0004] Aiming at the above-mentioned deficiencies of the prior art, the present invention provides a long-life fracturing pump crankshaft assembly device, which solves the problems of large processing difficulty and low life of the existing fracturing pump crankshaft.

[0005] The present invention is realized through the following technical solutions: A long-life fracturing pump crankshaft assembly device includes rolling bearings, a crankshaft, and helical gears. It is characterized in that the rolling bearings include rolling bearing one, rolling bearing two, rolling bearing three, and rolling bearing four, and the helical gears include helical gear one and helical gear two; the crankshaft includes a plurality of concentric main journals and a plurality of eccentric crank pins arranged at a certain phase angle on the circumference; flange plates are respectively provided on the two main journals adjacent to both sides of the middle crank pin on the crankshaft. The largest diameter side of the flange plate is arranged close to the middle crank pin and is concentric with the main journal; the helical gear one and the helical gear two are installed on the flange plates from both ends of the crankshaft and are fixedly connected to the flange plates by bolts. Then, the rolling bearing two and the rolling bearing three are respectively installed on the two main journals in the middle of the crankshaft, and the rolling bearing one and the rolling bearing four are respectively installed on the main journals at both ends of the crankshaft; the helical gear one and the helical gear two are symmetrically arranged on the crankshaft and have the same size and opposite directions of helix angles. The axial forces of the helical gear one and the helical gear two are transmitted to the middle crank pin of the crankshaft through the flange plates on the crankshaft, and there is no axial load acting on the crank pins at both ends of the crankshaft.

[0006] Further, an inclined gear positioning shoulder is provided on the outer side of the flange. The diameter of the positioning shoulder is larger than the outer diameter of the main journal rolling bearing and forms a fit with the inner hole diameter of the corresponding inclined gear. A plurality of bolt connection light holes are evenly arranged on the circumference of the flange, and threaded holes with the same number as the bolt connection light holes and distributed in a circle are provided on the first inclined gear and the second inclined gear. The first inclined gear and the second inclined gear are installed on the positioning shoulders of the flange from both ends of the crankshaft. Bolts pass through the bolt connection light holes of the flange and are screwed into the threaded holes on the first inclined gear and the second inclined gear until the specified torque is met.

[0007] Further, the crankshaft is applicable to a three-cylinder fracturing pump, a five-cylinder fracturing pump, and a seven-cylinder fracturing pump. When the crankshaft is applicable to a three-cylinder fracturing pump, it includes four concentric main journals and three crank pins, and the phase angle between any two adjacent crank pins is 120°. When the crankshaft is applicable to a five-cylinder fracturing pump, it includes six concentric main journals and five crank pins, and the phase angle between any two adjacent crank pins is 144°. When the crankshaft is applicable to a seven-cylinder fracturing pump, it includes eight concentric main journals and seven crank pins, and the phase angle between any two adjacent crank pins is 102.85°.

[0008] Further, the crankshaft is of a combined structure, including a first short crankshaft, an intermediate crank pin, a locking nut, a double-headed nut, and a second short crankshaft. During the assembly process of the fracturing pump, the first short crankshaft, the second short crankshaft, and the intermediate crank pin are assembled into a crankshaft with the locking nut and the double-headed stud.

[0009] Further, tapered shaft sections are adopted at both ends of the intermediate crank pin, and threaded holes are provided on both end faces. The crank pins on the intermediate crank pin, the first short crankshaft, and the second short crankshaft have the same diameter as the main journal. The diameter of the crank pin is smaller than the major diameter of the flange. Flanges connected to the inclined gears are designed on one side of the first short crankshaft and the second short crankshaft, and the main journals on the first short crankshaft and the second short crankshaft are arranged on one side of the flange. Tapered blind holes are provided on the end faces of the large ends of the flanges of the first short crankshaft and the second short crankshaft, and smooth threaded holes are provided at the bottoms of the tapered blind holes.

[0010] Further, the taper of the tapered blind hole is the same as the taper of the tapered shaft section of the intermediate crank pin. The distance between the center line of the tapered blind hole and the axis of the main journal is the same as the eccentricity of the crank pins on the first short crankshaft and the second short crankshaft, and the position of the tapered blind hole in the circumference has a certain phase difference with the adjacent crank pins on the first short crankshaft and the second short crankshaft according to the number of liquid cylinders of the fracturing pump.

[0011] Further, for the combined structure of the crankshaft, when the diameters of the main journal and the crank pin are the same, the same rolling bearings can be used for the main journal and the crank pin. When the diameter of the crank pin is smaller than the diameter of the main journal, split-type sliding bearings are used for the crank pin, and rolling bearings are used for the main journal.

[0012] Furthermore, the first short crankshaft and the second short crankshaft each have one crankpin in a three-cylinder fracturing pump, two crankpins in a five-cylinder fracturing pump, and three crankpins in a seven-cylinder fracturing pump.

[0013] Furthermore, in the three-cylinder fracturing pump, the phase difference is 120°; in the five-cylinder fracturing pump, the phase difference is 144°; in the seven-cylinder fracturing pump, the phase difference is 102.85°. Furthermore, the crankshaft is of an integral structure. The main journal on the crankshaft uses a rolling bearing. The diameter of the crankpin is smaller than the major diameter of the flange, and the crankpin uses a split-type sliding bearing.

[0014] The beneficial effects of the present invention are as follows: 1. In the present invention, by symmetrically arranging two helical gears on both sides of the middle crankpin, it avoids the situation where the middle crankpin bears the maximum torque and bending moment when a single herringbone gear or worm gear is arranged on one side of the middle crankpin in the early fracturing pump, and the stress state of the crankshaft is more balanced. 2. In the present invention, by symmetrically arranging two helical gears on both sides of the middle crankpin, it avoids the situation where the crankpins at both ends bear the maximum torque when the two helical gears are arranged at both ends of the crankshaft, and the crankshaft as a whole bears tensile or compressive force, causing all crankpins to bear axial and additional bending moments. The axial forces of the two helical gears are transmitted to the middle crankpin through the flange, and only the middle crankpin bears the axial force but almost no additional bending moment, and the overall stress state of the crankshaft is more balanced. 3. In the present invention, the crankpins on both sides of the crankshaft are not affected by axial forces; compared with the case of arranging two helical gears at both ends of the crankshaft, the stress cycle times of the crankpins on both sides are significantly reduced and not affected by axial forces within the same working time, and the fatigue life of the crankpins on both sides can be significantly improved.

[0015] 4. The integral-structured crankshaft in the present invention is lighter in weight than the existing integral structure. 5. The combined crankshaft structure in the present invention enables the rolling bearing to be also applicable to the connection between the crank and the big end of the connecting rod. 6. The load of each crankpin of the crankshaft assembly in the present invention is balanced, and the crankshaft has high strength, long life, and is convenient for processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a three-dimensional schematic diagram of the crankshaft assembly of a three-cylinder fracturing pump; Figure 2 is a three-dimensional schematic diagram of the structure of the integral crankshaft of a three-cylinder fracturing pump; Figure 3 is a three-dimensional schematic diagram of the structure of the combined crankshaft of a three-cylinder fracturing pump; Figure 4 is a three-dimensional schematic diagram of the structure of the short crankshaft of the combined crankshaft of a three-cylinder fracturing pump; Figure 5 It is a three-dimensional schematic diagram of the structure of the middle crankpin of the combined crankshaft of a three-cylinder fracturing pump; Figure 6 It is a three-dimensional schematic diagram of the crankshaft assembly of a five-cylinder fracturing pump; Figure 7 It is a three-dimensional structural schematic diagram of the integral crankshaft of a five-cylinder fracturing pump; Figure 8 It is a three-dimensional structural schematic diagram of the combined crankshaft of a five-cylinder fracturing pump; Figure 9 It is a three-dimensional structural schematic diagram of the middle crankpin of the combined crankshaft of a five-cylinder fracturing pump; Figure 10 It is a three-dimensional structural schematic diagram of the short crankshaft of the combined crankshaft of a five-cylinder fracturing pump; Figure 11 It is a three-dimensional structural schematic diagram of the integral crankshaft of a seven-cylinder fracturing pump; Figure 12 It is a three-dimensional structural schematic diagram of the combined crankshaft of a seven-cylinder fracturing pump.

[0017] Reference numerals: 1 - first rolling bearing, 2 - crankshaft, 201 - first short crankshaft, 202 - middle crankpin, 203 - lock nut, 204 - stud, 205 - second short crankshaft, 3 - second rolling bearing, 4 - first helical gear, 5 - bolt, 6 - second helical gear, 7 - third rolling bearing, 8 - fourth rolling bearing, 9 - main journal, 10 - crankpin, 11 - flange. Detailed implementation manners

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] Embodiment 1 Refer to the attached drawings of the specification Figure 1As shown in the figure, this embodiment is a long-life crankshaft assembly device for a three-cylinder fracturing pump, which includes rolling bearings, a crankshaft 2, and helical gears. The rolling bearings include rolling bearing one 1, rolling bearing two 3, rolling bearing three 7, and rolling bearing four 8. The helical gears include helical gear one 4 and helical gear two 6. The crankshaft 2 includes four concentric main journals 9 and three eccentric crank pins 10 arranged at a 120° phase angle on the circumference. On the two main journals 9 adjacent to both sides of the middle crank pin 202 on the crankshaft 2, flange plates 11 are respectively provided. The side with the largest diameter of the flange plate 11 is arranged close to the middle crank pin 202 and is concentric with the main journal 9. The helical gear one 4 and the helical gear two 6 are installed on the flange plates 11 from both ends of the crankshaft 2 and are fixedly connected to the flange plates 11 through bolts 5. Then, the rolling bearing two 3 and the rolling bearing three 7 are respectively installed on the two main journals 9 in the middle of the crankshaft 2, and the rolling bearing one 1 and the rolling bearing four 8 are respectively installed on the main journals 9 at both ends of the crankshaft 2. The helical gear one 4 and the helical gear two 6 are symmetrically arranged on the crankshaft 2 and have the same magnitude and opposite-direction helix angles. The axial forces of the helical gear one 4 and the helical gear two 6 are transmitted to the middle crank pin 202 of the crankshaft 2 through the flange plates 11 on the crankshaft 2, and there is no axial load acting on the crank pins 10 at both ends of the crankshaft 2.

[0020] When the two outer liquid cylinders of the three-cylinder fracturing pump suck liquid, the torque on the outer crank pin 10 of the crankshaft 2 is almost zero. Only when the outer liquid cylinder discharges liquid, the outer crank pin 10 bears the load of the liquid cylinder it drives. When the two helical gears are arranged at both ends of the crankshaft 2, when any two liquid cylinders discharge liquid simultaneously, the crank pins 10 on both sides need to transmit the torque required by one liquid cylinder. Although the maximum torque on the crank pins 10 at both ends of the crankshaft 2 of the present invention is the same, the number of times of the maximum torque action is reduced by one-third. When the present invention arranges the two helical gears on both sides of the middle crank pin 202, when any two liquid cylinders discharge liquid simultaneously, the torque required by the outer crank pin 10 will not be transmitted through the middle crank pin 202. Even when the two adjacent liquid cylinders on the same side discharge liquid simultaneously, the torque borne by the middle crank pin 202 is only the load of the middle liquid cylinder, and the maximum torque on the middle crank pin 202 is reduced by at least half. In the case of having the same main journal 9 supporting bearings, since the helical gears are arranged on both sides of the middle crank pin 202, the bending moment on the middle crank pin 202 is also reduced. Therefore, under the same working conditions of the fracturing pump, compared with the crankshaft 2 with herringbone gears concentratedly arranged on one side of the middle crank pin 202, the maximum stress value of the middle crank pin 202 of the crankshaft 2 of the present invention is greatly reduced, and the average stress is also significantly reduced. The service life of the middle crank pin 202 of the crankshaft 2 can be effectively improved.

[0021] In this embodiment, during the working process, the externally input torque is transmitted to the flange 11 of the crankshaft 2 through the first helical gear 4 and the second helical gear 6. Part of the torque of the two flanges 11 is simultaneously transmitted to the intermediate crankpin 202 to drive the liquid cylinder in the middle of the fracturing pump to work. At the same time, the flange 11 transmits another part of the torque to the crankpins 10 on both sides. The additional bending moment of the intermediate crankpin 202 of the crankshaft 2 is small, which is beneficial to improving the service life of the intermediate crankpin 202 of the crankshaft 2. Compared with the prior art, it avoids the stress state in which when the herringbone gears are centrally arranged on one side of the intermediate crankpin 202, the intermediate crankpin 202 has to bear at least the torque when one liquid cylinder discharges and at most the torque when two liquid cylinders discharge, and the maximum torque it bears is greater than the force on the crankpins 10 on both sides. It also avoids the stress state in which when two helical gears are arranged at both ends of the crankshaft 2, the crankpins 10 on both sides have to bear the load of one liquid cylinder even when the liquid cylinders they drive do not discharge. According to the different rotation directions of the crankshaft 2, the axial force directions of the first helical gear 4 and the second helical gear 6 may be opposite or the same. When the axial force directions of the first helical gear 4 and the second helical gear 6 are opposite, the intermediate crankpin 202 of the crankshaft 2 is subjected to axial pressure. When the axial force directions of the first helical gear 4 and the second helical gear 6 are the same, the intermediate crankpin 202 of the crankshaft 2 is subjected to axial tension. Regardless of the axial force directions of the first helical gear 4 and the second helical gear 6, the crankpins 10 at both ends of the crankshaft 2 are not subjected to axial loads and do not bear additional bending moments. Compared with the case where two helical gears are arranged at both ends of the crankshaft 2, the stress cycle times of the crankpins 10 on both sides are significantly reduced and they are not subjected to axial forces within the same working time, and the fatigue life of the crankpins 10 on both sides can be significantly improved, which is beneficial to improving the strength and service life of the crankpins 10 at both ends of the crankshaft 2.

[0022] Embodiment 2 This embodiment further elaborates and supplements the implementation manner of the present invention on the basis of Embodiment 1.

[0023] An axial shoulder for helical gear positioning is provided on the outer side of the flange 11. The diameter of the axial shoulder is larger than the outer diameter of the rolling bearing of the main journal 9 and forms a fit with the inner hole diameter of the corresponding helical gear. A plurality of bolt 5 connection light holes are uniformly arranged on the circumference of the flange 11, and threaded holes with the same number as the bolt 5 connection light holes and distributed in a circle are provided on the first helical gear 4 and the second helical gear 6. The first helical gear 4 and the second helical gear 6 are installed on the axial shoulders of the flange 11 from both ends of the crankshaft 2. The bolt 5 passes through the bolt 5 connection light hole of the flange 11 and is screwed into the threaded holes on the first helical gear 4 and the second helical gear 6 until the specified torque is met.

[0024] Embodiment 3 This embodiment further elaborates and supplements the implementation manner of the present invention on the basis of Embodiment 2.

[0025] Refer to the attached drawings of the specificationFigures 3 - 5 As shown, the crankshaft 2 has a combined structure, including a first short crankshaft 201, an intermediate crankpin 202, a lock nut 203, a double-headed nut, and a second short crankshaft 205. During the assembly process of the fracturing pump, the first short crankshaft 201, the second short crankshaft 205, and the intermediate crankpin 202 are assembled into the crankshaft 2 using the lock nut 203 and the double-headed stud 204.

[0026] Both ends of the intermediate crankpin 202 adopt tapered shaft sections, and threaded holes are provided on both end faces. The crankpins 10 on the intermediate crankpin 202, the first short crankshaft 201, and the second short crankshaft 205 all have the same diameter as the main journal 9; the diameter of the crankpin 10 is smaller than the major diameter of the flange 11; on one side of the first short crankshaft 201 and the second short crankshaft 205, there is a flange 11 connected to the helical gear. The main journals 9 on the first short crankshaft 201 and the second short crankshaft 205 are arranged on one side of the flange, which can facilitate the installation of the rolling bearing of the main journal 9 onto the main journal 9 from one side; on the end face of the large end of the flange 11 of the first short crankshaft 201 and the second short crankshaft 205, a tapered blind hole is provided, and a smooth threaded hole is provided at the bottom of the tapered blind hole.

[0027] Furthermore, when the crankshaft 2 has a combined structure and the main journal 9 and the crankpin 10 have the same diameter, the main journal 9 and the crankpin 10 can adopt the same rolling bearing; when the diameter of the crankpin 10 is smaller than the diameter of the main journal 9, the crankpin 10 adopts a split-type sliding bearing, and the main journal 9 adopts a rolling bearing.

[0028] The taper of the conical blind hole is the same as that of the conical shaft section of the intermediate crankpin 202. The distance between the center line of the conical blind hole and the axis of the main journal 9 is the same as the eccentricity of the crankpins 10 of the first short crankshaft 201 and the second short crankshaft 205. And the position of the conical blind hole on the circumference has a 120° phase difference from the adjacent crankpins 10 on the first short crankshaft 201 and the second short crankshaft 205. During the assembly process, first, the inner ring of the rolling bearing at the large end of the intermediate hydraulic cylinder connecting rod is installed on the intermediate crankpin 202, and the large end of the connecting rod is assembled on the outer ring of the rolling bearing on the intermediate crankpin 202. One end of the stud 204 is screwed into the screw holes at both ends of the intermediate crankpin 202. Then, the conical shaft ends at both ends of the intermediate crankpin 202 are respectively inserted into the conical blind holes at the large ends of the flange plates 11 of the first short crankshaft 201 and the second short crankshaft 205. At the same time, the stud 204 passes through the smooth screw hole opened at the bottom of the conical blind hole at the large end of the flange plate 11. The nut is tightened on the other end of the stud 204 according to the designed torque. Under the tensile force of the tightened stud 204, a tight fit is formed between the conical shaft end sections at both ends of the intermediate crankpin 202 and the conical blind holes at the large ends of the flange plates 11 of the first short crankshaft 201 and the second short crankshaft 205. When the crankshaft 2 rotates, the torque is transmitted to the intermediate crankpin 202 by relying on this tight fit. If the axial forces on the two helical gears exert extrusion on the intermediate crankpin 202, it is also transmitted through this tight fit of the conical shaft section. If the axial forces on the two helical gears have a tensile effect on the intermediate crankpin 202, it is transmitted to the intermediate crankpin 202 through the tension of the stud 204. For the other rolling bearings on the two short crankshafts at both ends of the crankshaft 2 assembly, they are assembled on the main journal 9 and the crankpin 10 of the crankshaft 2 in sequence from the inside to the outside.

[0029] Refer to the attached drawings of the specification Figure 2 As shown, the crankshaft 2 can adopt an integral structure, generally using an integral forging or casting blank and then processed by cutting. At this time, to reduce the weight of the crankshaft 2 and facilitate the connection between the intermediate crankpin 202 and the large end of the connecting rod, the diameters of all the crankpins 10 of the crankshaft 2 are smaller than the large diameter of the flange plate 11. The crankpins 10 adopt split-type sliding bearings, and oil channels are opened on the crankshaft 2 to provide pressure oil supply for the sliding bearings to ensure the reliable operation of the sliding bearings. The main journals 9 on the crankshaft 2 adopt rolling bearings.

[0030] Embodiment 4 This embodiment further elaborates and supplements the implementation manner of the present invention on the basis of Embodiment 3.

[0031] Refer to the attached drawings of the specification Figures 6 - 10 As shown, this embodiment is an embodiment of the long-life fracturing pump crankshaft assembly device of the present invention in a five-cylinder fracturing pump.

[0032] The crankshaft 2 includes six concentric main journals 9 and five eccentric crank pins 10 arranged at a certain phase angle in the circumferential direction. The phase angle between any two adjacent crank pins 10 is 144°. Two flange plates 11 connected to the first helical gear 4 and the second helical gear 6 are arranged on the main journals 9 on both sides adjacent to the middle crank pin 202 of the crankshaft 2. When the crankshaft 2 is working, the axial forces of the first helical gear 4 and the second helical gear 6 only act on the middle crank pin 202, and the other four crank pins 10 do not bear axial forces, thus avoiding the additional bending moment generated by the axial forces on these four crank pins 10 and improving the strength and service life of these four crank pins 10.

[0033] When the crankshaft 2 is implemented in a five-cylinder fracturing pump, it can adopt an integral structure or a combined structure. When the crankshaft 2 adopts a combined structure, both the first short crankshaft 201 and the second short crankshaft 205 include two crank pins 10 with a phase angle of 144° and three concentric main journals 9. Flange plates 11 concentric with the main journals 9 are arranged on the main journals 9 on the side of the first short crankshaft 201 and the second short crankshaft 205 close to the middle crank pin 202. Tapered blind holes are opened on the large end faces of the flange plates 11, and the positions of the tapered blind holes in the circumferential direction have a 144° phase difference from the adjacent crank pins 10 on the first short crankshaft 201 and the second short crankshaft 205. During the assembly process of the fracturing pump, the first short crankshaft 201, the second short crankshaft 205 and the middle crank pin 202 are assembled into the crankshaft 2 with a lock nut 203 and a stud 204.

[0034] Other features of the crankshaft 2 when implemented in a five-cylinder fracturing pump are similar to those of a three-cylinder fracturing pump.

[0035] Embodiment 5 This embodiment further elaborates and supplements the implementation manner of the present invention on the basis of Embodiment 4.

[0036] Refer to the attached Figures 11 - 12 As shown, this embodiment is an embodiment of the long-life fracturing pump crankshaft assembly device of the present invention in a seven-cylinder fracturing pump.

[0037] The crankshaft 2 includes eight concentric main journals 9 and seven eccentric crank pins 10 arranged at a certain phase angle on the circumference. The phase angle between any two adjacent crank pins 10 is 102.85°. The two flange plates 11 connected to the first helical gear 4 and the second helical gear 6 are arranged on the main journals 9 on both sides adjacent to the middle crank pin 202 of the crankshaft 2. When the crankshaft 2 is working, the axial forces of the first helical gear 4 and the second helical gear 6 only act on the middle crank pin 202, and the other six crank pins 10 do not bear the axial force, which also avoids the additional bending moment generated by the six crank pins 10 bearing the axial force, and improves the strength and service life of the six crank pins 10. When the crankshaft 2 is implemented in a seven-cylinder fracturing pump, an integral structure or a combined structure can be adopted, and other features of the crankshaft 2 when implemented in a seven-cylinder fracturing pump are similar to those when implemented in a three-cylinder fracturing pump and a five-cylinder fracturing pump.

[0038] When the crankshaft 2 adopts a combined structure, both the first short crankshaft 201 and the second short crankshaft 205 include three crank pins 10 with a phase angle of 102.85° and four concentric main journals 9.

Claims

1. A long-life fracturing pump crankshaft assembly device, including rolling bearings, a crankshaft (2), and helical gears, characterized in that, The rolling bearings include rolling bearing one (1), rolling bearing two (3), rolling bearing three (7), and rolling bearing four (8), and the helical gears include helical gear one (4) and helical gear two (6); the crankshaft (2) includes a plurality of concentric main journals (9) and a plurality of eccentric crank pins (10) arranged at a certain phase angle on the circumference; on the two main journals (9) adjacent to both sides of the intermediate crank pin (202) on the crankshaft (2), flange plates (11) are respectively arranged, and the largest diameter side of the flange plate (11) is arranged at a position close to the intermediate crank pin (202) and is concentric with the main journal (9); the helical gear one (4) and the helical gear two (6) are installed on the flange plates (11) from both ends of the crankshaft (2) and are fixedly connected to the flange plates (11) by bolts (5), and then the rolling bearing two (3) and the rolling bearing three (7) are respectively installed on the two main journals (9) in the middle of the crankshaft (2), and the rolling bearing one (1) and the rolling bearing four (8) are respectively installed on the main journals (9) at both ends of the crankshaft (2); the helical gear one (4) and the helical gear two (6) are symmetrically arranged on the crankshaft (2) and have the same magnitude and opposite directions of helix angles, and the axial forces of the helical gear one (4) and the helical gear two (6) are transmitted to the intermediate crank pin (202) of the crankshaft (2) through the flange plates (11) on the crankshaft (2), and there is no axial load acting on the crank pins (10) at both ends of the crankshaft (2).

2. The long-life fracturing pump crankshaft assembly device according to claim 1, characterized in that, An helical gear positioning shoulder is arranged on the outer side of the flange plate (11), and the diameter of the positioning shoulder is larger than the outer diameter of the rolling bearing of the main journal (9) and forms a fit with the inner hole diameter of the corresponding helical gear; a plurality of bolt connection light holes are evenly arranged on the circumference of the flange plate (11), and the helical gear one (4) and the helical gear two (6) are provided with threaded holes having the same number as the bolt connection light holes and distributed in a circumference, and the helical gear one (4) and the helical gear two (6) are installed on the positioning shoulders of the flange plates (11) from both ends of the crankshaft (2), and the bolts (5) pass through the bolt connection light holes of the flange plates (11) and are screwed into the threaded holes on the helical gear one (4) and the helical gear two (6) until the specified torque is met.

3. A long-life fracturing pump crankshaft assembly device according to any one of claims 1 or 2, characterized in that, The crankshaft (2) can be applicable to a three-cylinder fracturing pump, a five-cylinder fracturing pump, and a seven-cylinder fracturing pump; when the crankshaft (2) is applicable to a three-cylinder fracturing pump, it includes four concentric main journals (9) and three crank pins (10), and the phase angle between any two adjacent crank pins (10) is 120°; when the crankshaft (2) is applicable to a five-cylinder fracturing pump, it includes six concentric main journals (9) and five crank pins (10), and the phase angle between any two adjacent crank pins (10) is 144°; when the crankshaft (2) is applicable to a seven-cylinder fracturing pump, it includes eight concentric main journals (9) and seven crank pins (10), and the phase angle between any two adjacent crank pins (10) is 102.85°.

4. A long-life fracturing pump crankshaft assembly device according to claim 3, characterized in that, The crankshaft (2) has a combined structure, including a first short crankshaft (201), an intermediate crankpin (202), a lock nut (203), a double-headed nut, and a second short crankshaft (205). During the assembly process of the fracturing pump, the first short crankshaft (201), the second short crankshaft (205), and the intermediate crankpin (202) are assembled into the crankshaft (2) using the lock nut (203) and the double-headed stud (204).

5. A long-life fracturing pump crankshaft assembly device according to claim 4, characterized in that, Both ends of the intermediate crankpin (202) adopt tapered shaft sections, and threaded holes are provided on both end faces. The crankpins (10) on the intermediate crankpin (202), the first short crankshaft (201), and the second short crankshaft (205) all have the same diameter as the main journal (9); the diameter of the crankpin (10) is smaller than the major diameter of the flange (11); on one side of the first short crankshaft (201) and the second short crankshaft (205), there are flanges (11) connected to the helical gears, and the main journals (9) on the first short crankshaft (201) and the second short crankshaft (205) are arranged on one side of the flange; on the end faces of the large ends of the flanges (11) of the first short crankshaft (201) and the second short crankshaft (205), tapered blind holes are provided, and smooth threaded holes are provided at the bottoms of the tapered blind holes.

6. A long-life fracturing pump crankshaft assembly device according to claim 5, characterized in that, The taper of the tapered blind hole is the same as the taper of the tapered shaft section of the intermediate crankpin (202), the distance between the center line of the tapered blind hole and the axis of the main journal (9) is the same as the eccentricity of the crankpin (10) of the first short crankshaft (201) and the second short crankshaft (205), and the position of the tapered blind hole in the circumferential direction has a certain phase difference with the adjacent crankpins (10) on the first short crankshaft (201) and the second short crankshaft (205) according to the number of liquid cylinders of the fracturing pump.

7. A long-life fracturing pump crankshaft assembly device according to claim 5, characterized in that, The crankshaft (2) has a combined structure. When the diameters of the main journal (9) and the crankpin (10) are the same, the main journal (9) and the crankpin (10) can adopt the same rolling bearing; when the diameter of the crankpin (10) is smaller than the diameter of the main journal (9), the crankpin (10) adopts a split-type sliding bearing, and the main journal (9) adopts a rolling bearing.

8. A long-life fracturing pump crankshaft assembly device according to claim 5, characterized in that, The first short crankshaft (201) and the second short crankshaft (205) have one crankpin (10), two crankpins (10), and three crankpins (10) respectively in a three-cylinder fracturing pump, a five-cylinder fracturing pump, and a seven-cylinder fracturing pump.

9. A long-life fracturing pump crankshaft assembly device according to claim 5, characterized in that, In the three-cylinder fracturing pump, the phase difference is 120°; in the five-cylinder fracturing pump, the phase difference is 144°; in the seven-cylinder fracturing pump, the phase difference is 102.85°.

10. The long-life fracturing pump crankshaft assembly device according to claim 3, characterized in that, The crankshaft (2) has an integral structure. The main journal (9) on the crankshaft (2) adopts a rolling bearing, the diameter of the crankpin (10) is smaller than the major diameter of the flange (11), and the crankpin (10) adopts a split-type sliding bearing.

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