CN114934886A

CN114934886A - Ultrahigh-pressure high-speed swash plate type axial plunger variable displacement pump

Info

Publication number: CN114934886A
Application number: CN202210397592.XA
Authority: CN
Inventors: 胡敏; 谷学勇; 张宇; 胡静
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2022-04-15
Filing date: 2022-04-15
Publication date: 2022-08-23

Abstract

The invention provides an ultrahigh-pressure high-speed swash plate type axial plunger variable pump, which aims to solve the technical problem of the plunger pump under an ultrahigh-pressure high-speed working condition. The plunger pump cylinder body and the main shaft are in split design and are in transmission through spline connection, the front bearing and the rear bearing are used for carrying out composite support on the cylinder body, so that bending moment caused by unbalanced lateral force on the cylinder body can be borne by the front bearing and the rear bearing which are arranged on the cylinder body, the load force and bending moment on the cylinder body are more balanced, the main shaft only needs to transmit torque, deflection of the main shaft is greatly reduced, and the problems that the cylinder body is easy to overturn under the working condition of ultrahigh pressure and high rotating speed, the deflection of the main shaft greatly affects a flow distribution pair and a plunger pair which are closely related to the cylinder body, and the like are solved. The outer diameters of the front boss and the rear boss of the cylinder body can be optimally designed to be minimum, the relative rotation linear speed and the PV value between the outer surface of the cylinder body and the contact surface of the supporting bearing can be reduced to the maximum degree, and the bearing design difficulty caused by the overlarge outer diameter of the cylinder body of the plunger pump is reduced.

Description

Ultrahigh-pressure high-speed swash plate type axial plunger variable displacement pump

Technical Field

The invention relates to the technical field of fluid transmission and control, in particular to an ultrahigh-pressure high-speed swash plate type axial plunger pump.

Background

The hydraulic system occupies an important position in a plurality of key fields such as heavy industrial machinery, large-scale equipment, military industry and aerospace and the like, and the performance of the hydraulic pump which is used as a main power element of the hydraulic system directly influences the normal work of the hydraulic system. Compared with other types of hydraulic pumps, the axial plunger pump has the advantages of high pressure level, simple variable, large flow regulation range, compact structure size, high volumetric efficiency and the like, so that the axial plunger pump is widely applied to hydraulic systems of various mechanical equipment, and the performance of the axial plunger pump directly influences the performance of the various mechanical equipment.

With the development of science and technology, the performance requirements of the plunger pump in the industrial field are higher and higher, and the ultrahigh pressure, high efficiency and high power mass ratio become the main development trend of the current axial plunger pump. Increasing the rated pressure rating is the best solution to reduce energy consumption and increase the power to weight ratio. At the same power, high pressure can reduce load flow, meaning that hydraulic components and systems will be reduced in volume and weight, saving materials and manufacturing costs. In addition, the small flow rate not only reduces the pressure loss and improves the transmission efficiency, but also reduces the usage amount of petroleum-based transmission media and the environmental-friendly treatment cost. The 35MPa pressure grade system governs the hydraulic industry for more than 30 years, and has not been broken through all the time, and foreign academia and industry continuously study the rated pressure grade of the next generation of hydraulic elements in recent years, and the signs show that the development of the hydraulic elements with higher rated pressure grade is a necessary trend. The high rated pressure faces a series of difficult problems of increased cylinder overturning moment, increased internal leakage of a friction pair coupling part gap, increased PV value of a friction pair, aggravated vibration noise and the like, and brings a serious challenge to the design and manufacture of hydraulic elements, but also brings an opportunity to the domestic hydraulic industry, so the high pressure is a necessary way for independent innovation and sustainable development of domestic enterprises.

The high rated pressure induces the deflection of the main shaft to increase, the cylinder body to overturn and damage the normal work of the cylinder body valve plate friction pair and the cylinder body plunger piston friction pair, so that the internal leakage of the clearance between the cylinder body valve plate and the cylinder body plunger piston friction pair is increased, the friction pair is induced to generate eccentric wear until the wear failure, and the high-speed ultrahigh-pressure axial plunger pump is one of the key technical problems to be solved. The cylinder body structure of the ultrahigh pressure plunger pump at home and abroad is researched and researched, and mainly comprises two schemes, wherein one scheme is that the traditional axial plunger pump disc flow distribution is changed into a valve flow distribution type, the cylinder body adopts a fixed static structure instead of a structure that the cylinder body rotates along with a main shaft like the traditional axial plunger pump, and the other scheme is that a bearing redundancy support type is adopted on the outer ring of the cylinder body, so that the radial displacement of the cylinder body is forcibly limited. The two schemes are combined, the rated flow and variable control performance of the axial plunger pump in the first valve flow distribution scheme is greatly restricted by the performance of the flow distribution valve, the diameter of a cylinder body is often larger when the displacement of the axial plunger pump is larger in the second scheme, a bearing arranged on the outer ring of the cylinder body needs to bear a larger PV value, the radial size of the axial plunger pump is increased, and the rated working pressure and the rotating speed of the axial plunger pump are restricted by the design and the performance of the outer ring bearing.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides an ultrahigh-pressure high-speed swash plate type axial plunger variable displacement pump, and aims to solve the problems that the cylinder body of the plunger pump is easy to overturn under the working conditions of ultrahigh pressure and high rotating speed, and the working performance of a flow distribution pair and a plunger pair which are closely associated with the cylinder body is influenced by large deflection of a main shaft, and the like.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an ultrahigh-pressure high-speed swash plate type axial plunger variable displacement pump comprises a cylinder body, a front bearing, a rear bearing, a main shaft, a spring, a swing seat, a swash plate, a sliding shoe, a plunger, a shaft sleeve, a flow distribution plate, a return plate, an auxiliary pump, a servo piston, a control valve, a spring base, a compression spring, an adjusting screw, a limiting plug, a shifting block, a sealing element, a shaft end cover, a rear end cover, an O-shaped ring and a fixing screw; the cylinder body comprises a cylindrical cylinder body main body, a front boss and a rear boss, the cylindrical cylinder body main body, the front boss and the rear boss form a whole, a plurality of axial plunger holes are uniformly distributed in the cylinder body main body, plungers are arranged in the plunger holes and are parallel to the axis of the cylinder body, and a plurality of lubricating oil guide holes are formed in the side surface of the cylinder body main body; the sealing element is arranged between the main shaft and the front end cover, the shaft end cover is fixedly arranged on the front shell through a screw, and an O-shaped sealing ring is arranged between the shaft end cover and the sealing element; the front bearing inner ring is arranged on the main shaft and is axially limited by a shaft shoulder on the main shaft, the left end surface of the swing seat, a gasket and an elastic check ring; the plunger piston and the piston shoe are hinged through a spherical hinge pair to form a plunger piston shoe assembly, the return disc is buckled and pressed on the piston shoe through a spherical hinge support, and the swash plate is arranged on the swing seat; the inclination angle of the swash plate is changed by pushing a servo variable mechanism to carry out variable, the servo variable mechanism comprises a servo piston, a control valve, a shifting block, a large servo piston spring, a limiting block and an adjusting screw, the servo piston is positioned by a plug and the limiting block, the bottom of a compression spring is fixed on a spring seat and spirally wound along the direction of the piston, the motion of the servo piston is controlled by a power valve, the control valve and the adjusting screw, and the control valve is fixed on the upper part of a rear end cover through a bolt; the flow distribution plate is fixedly arranged on the rear end cover through a pin, the front surface of the flow distribution plate is attached to the bottom surface of the cylinder body, and the back surface of the flow distribution plate is attached to the rear end cover; an auxiliary pump, an oil inlet and outlet flow passage, a shaft sleeve and a sealing ring are arranged in the rear end cover, the flow passage in the rear end cover is streamline and is connected with a notch on the valve plate, a section of the center of the rear end cover is matched with an outer ring of a bearing on the main shaft, the diameter of a central hole of the rear end cover is set to be trapezoidal so as to be matched with the bearing, and the axial displacement of the bearing is limited; the rear end cover is connected with the outer shell through a fixing screw and supported on the main shaft through a needle bearing, a spline is arranged at the tail end of the main shaft and connected with the inner tooth shaft sleeve, a key groove is formed in the outer side of the inner tooth shaft sleeve and connected with a pinion in the auxiliary pump through a flat key;

the cylinder body is connected with the main shaft through a spline structure on a center hole of the cylinder body, and the main shaft is connected with the prime motor. The front boss comprises a first front boss section, a second front boss section and a third front boss section, the first front boss section and the cylinder body main body are of an integrated structure, the second front boss section and the first front boss section are of an integrated structure, the third front boss section and the second front boss section are of an integrated structure, the three boss sections are respectively installed and assembled with other parts of the pump, the shaft diameters of the three boss sections are gradually reduced according to the sizes of the other parts of the pump matched with the three boss sections, so that the precision installation and assembly with the other parts of the pump are realized, and the third front boss section is used for installing a bearing and realizing the precision assembly with the bearing; the front boss first section and the front boss second section are used for mounting and assembling with a spherical hinge part in the pump, and the rear boss is provided with a stepped structure and is used for mounting a gasket and a rear bearing so as to realize supporting and positioning of the cylinder body;

the main shaft is supported by a cylindrical roller bearing on the front side of the shaft end and a needle roller bearing on the rear end of the shaft end respectively, the cylinder body is supported and limited by the needle roller bearing on the front boss of the cylinder body and the needle roller bearing on the rear boss, and the needle roller bearings supporting the cylinder body are arranged and installed on the third section of the front boss and the rear boss extending out of the two sides of the cylinder body respectively.

The needle roller bearings for supporting the main shaft at the rear end of the main shaft, and the needle roller bearings for supporting the cylinder body on the front boss and the rear boss of the cylinder body can also be replaced by sliding bearings or bearing bushes.

The side surface of the cylinder body main body is provided with 9 radial lubrication oil guide holes along the radial direction of the cylinder body, and the 9 radial lubrication oil guide holes are uniformly distributed around the cylinder body for one circle and penetrate through the cylinder body to the center hole of the cylinder body; the bottom surface of the cylinder body which is attached to the thrust plate is also provided with 9 axial lubricating oil guide holes; the axial lubrication oil guide hole is communicated with the radial lubrication oil guide hole.

Compared with the prior art, the invention has the advantages that:

1. the cylinder body is supported by the front bearing arranged on the third section 2 of the front boss structure and the rear bearing arranged on the rear boss structure 9 together, so that the load force and the bending moment action of the cylinder body are more balanced, the problem that the friction and the abrasion are intensified due to the fact that a local area of lateral force between the bearing and the cylinder body subjected to the bending moment action is enlarged due to the fact that the bearing is completely supported by one bearing on the outer ring of the cylinder body in the existing scheme is solved, and the kinematics and the dynamic performance of the cylinder body under the working condition of ultrahigh pressure and high rotating speed are improved;

2. the third section 2 of the front boss structure and the rear boss structure 9 of the front bearing and the rear bearing used for installing and supporting the limiting cylinder body can be flexibly designed according to the ultrahigh pressure load required to be born by the bearing and the allowed high-speed rotation linear velocity, the design flexibility and the design space are larger than those of the existing scheme, compared with the existing cylinder body with the supporting bearing added on the outer ring of the cylinder body main body, the outer diameters of the third section 2 of the front boss structure and the rear boss structure 9 of the front boss structure can be designed to be far smaller than the outer diameter of the cylinder body main body, simultaneously, the discharge capacity of the pump is not influenced, the benefit of the great reduction of the outer diameter is realized, the relative rotation linear velocity required to be born by the bearing supporting the cylinder body is also remarkably reduced, the problems that the linear velocity of the bearing is very large due to the larger outer diameter of the cylinder body main body in the existing scheme and the highest working pressure which can be reached by the pump due to the limitation of the allowable linear velocity and the allowable PV value of the bearing are overcome, The difficulty that the maximum rotating speed and the maximum displacement are greatly restricted creates extremely favorable conditions for the design of an ultrahigh pressure high rotating speed pump, in particular a large displacement pump.

Drawings

Fig. 1 is a half sectional view of a plunger pump.

Fig. 2 is an external view of the plunger pump.

Fig. 3 is a schematic diagram of a servo variable mechanism of the plunger pump.

Fig. 4 is a schematic view of the plunger pump variable displacement mechanism installation.

Fig. 5 is a sectional view of a main shaft supporting scheme of a cylinder body of the plunger pump.

FIG. 6 is a partial cross-sectional view of the main shaft support of the plunger pump cylinder.

Fig. 7 is a sectional view of a cylinder of a plunger pump integrated structure.

Fig. 8 is a schematic view of the front face and front boss of the cylinder body of the plunger pump integrated structure.

Fig. 9 is a schematic view of the structure of the oil guide hole of the plunger pump cylinder body.

FIG. 10 is a schematic view of the bottom surface and rear boss of the cylinder body of the plunger pump.

FIG. 11 is a cross-sectional view of a cylinder with a copper jacket in the plunger pump cylinder bore.

FIGS. 1-11 are numbered: 1. front bearing (open type drawn cup needle roller bearing), 2, front boss third section, 3, front boss second section, 4, front boss first section, 5, spring hole, 6, spring, 7, cylinder body, 8, rear bearing, 9, rear boss, 10, internal spline, 11, oil suction and discharge waist-shaped groove, 12, cylinder hole, 13, plunger, 14, slipper, 15, outer shell, 16, shaft end cover, 17, swash plate, 18, rear end cover, 19, fixing bolt, 20, servo piston, 21, control valve, 22, shifting block, 23, spring base, 24, compression spring, 25, power valve, 26, adjusting screw, 27, main shaft, 28, limiting plug, 29, cylindrical roller bearing, 30, needle roller bearing, 31, shaft sleeve, 32, sealing piece, 33, swing seat, 34, clamp spring, 35, and flow distribution plate.

Detailed Description

As shown in fig. 1-11:

the invention provides an ultrahigh-pressure high-speed swash plate type axial plunger variable displacement pump which comprises a front bearing (an open type stamping outer ring needle roller bearing) 1, a front boss third section 2, a front boss second section 3, a front boss first section 4, a spring hole 5, a spring 6, a cylinder body 7, a rear bearing 8, a rear boss 9, an internal spline 10, an oil suction and discharge waist-shaped groove 11, a cylinder hole 12, a plunger 13, a sliding shoe 14, an outer shell 15, a shaft end cover 16, a swash plate 17, a rear end cover 18, a fixing bolt 19, a servo piston 20, a control valve 21, a shifting block 22, a spring base 23, a compression spring 24, a power valve 25, an adjusting screw 26, a main shaft 27, a limiting screw plug 28, a cylindrical roller bearing 29, a bearing 30, a shaft sleeve 31, a sealing element 32, a needle roller swing seat 33, a clamp spring 34 and a flow distribution plate 35.

The front of the cylinder body main body 7 is provided with 9

cylinder holes

12 and 9 spring holes 5, each spring hole is internally provided with a spring 6, the bottom surface of the cylinder body main body 7 is provided with 9 oil suction and discharge waist-shaped grooves 11, the 9 oil suction and discharge waist-shaped grooves 11 are communicated with the 9 cylinder holes 12, and the side surface of the cylinder body main body is provided with 9 lubricating oil guide holes. The cylinder body front boss 15 extends out from the front of the cylinder body main body 7, the front boss comprises a front boss first section 4, a front boss second section 3 and a front boss third section 2, the front boss first section 4 is connected with the cylinder body main body 7, the front boss second section 3 is connected with the front boss first section 4, the front boss third section 2 is connected with the front boss second section 3, the front boss third section 2 can be used for installing the front bearing 1, the rear boss 9 extends out from the bottom of the cylinder body main body 7, the rear boss 9 is used for installing the rear bearing 8, the shaft diameters of the front boss third section 2 and the rear boss 9 are allowed to be optimally designed to be the minimum, the linear velocity on the contact surface with the bearing is enabled to be the minimum, the PV value is the minimum, and the front boss, the cylinder body main body 7 and the rear boss 9 are of a complete integrated structure to jointly form the cylinder body. The middle of the cylinder body is provided with a through hole, the through hole is provided with an internal spline 10, the main shaft is connected with the cylinder body through the internal spline 10 and drives the cylinder body to rotate, and the cylinder body is supported by a front bearing 1 and a rear bearing 8 and is fixedly limited and arranged in an outer shell 15. The external motor drives the main shaft 27, the main shaft 27 drives the cylinder body 7 to rotate through a spline, the swash plate 17 and the thrust plate 35 are fixed during working, the piston 13 head is provided with the slipper 14, the slipper and the swash plate are in spherical contact, and a static pressure supporting structure is adopted to enable the slipper and the swash plate to be attached to each other all the time. When the cylinder 7 rotates, the plunger 13 is reciprocated under the combined action of the swash plate 17 and the low pressure oil, the volume of the seal cavity between each plunger 13 and the cylinder 7 is changed to increase or decrease, and oil is sucked and pressed through the window on the oil distribution disc 35. Wherein the swash plate 17 is inclined at a certain angle with the cylinder block 7; the servo variable mechanism can drive the change of the inclination angle of the swash plate to carry out variable, when the swing angle is zero, the pump has zero displacement (namely, the displacement is zero), the swing angle of the swash plate is changed by the movement of the servo piston, and the movement of the servo piston is controlled by the control valve 21, the power valve 25 and the adjusting screw 26.

The servo variable mechanism consists of a servo piston 20, a control valve body 21, a shifting block 22, a spring base 23, a compression spring 24, a power valve 25, an adjusting screw 26 and a limiting plug 28, and can push to change the inclination angle of the swash plate to carry out variable, and the specific structure is shown in figures 3 and 4.

The main shaft is supported by a cylindrical roller bearing and a needle bearing, the cylinder body is supported by a pair of needle bearings, and the supporting scheme of the cylinder body with double bosses and front and rear bearings is shown in figure 5.

The side surface of the cylinder body main body is provided with 9 radial lubrication oil guide holes along the radial direction of the cylinder body, and the 9 radial lubrication oil guide holes are uniformly distributed around the cylinder body for a circle and penetrate through the cylinder body main body to the center hole of the cylinder body; the bottom surface of the cylinder body which is attached to the thrust plate is also provided with 9 axial lubricating oil guide holes; the axial lubrication oil guide hole is communicated with the radial lubrication oil guide hole, so that the lubrication problem of the spline is solved, the abrasion of the spline is reduced, the service life of the spline is greatly prolonged, and the specific structure is shown in figure 8.

The working process of the invention is as follows:

as shown in fig. 1, 3, 4, and 6, a front boss 15 of the cylinder body extends from the front of a cylinder body main body 7, the front boss comprises three sections, namely a first section 4 of the front boss, a second section 3 of the front boss, and a third section 2 of the front boss, the first section 4 of the front boss is connected with the cylinder body main body 7, the second section 3 of the front boss is connected with the first section 4 of the front boss, the third section 2 of the front boss is connected with the second section 3 of the front boss, the third section 2 of the front boss can be used for installing a front bearing 1, the rear boss 9 extends from the bottom of the cylinder body main body 7, the rear boss 9 is used for installing a rear bearing 8, the axial diameters of the third section 2 of the front boss and the rear boss 9 are allowed to be optimally designed to be minimum, so that the linear velocity on the contact surface with the bearing is minimum, the PV value is minimum, and the front boss, the cylinder body main body 7 and the rear boss 9 are an integral structure to jointly form the cylinder body. The middle of the cylinder body is provided with a through hole, the through hole is provided with an internal spline 10, the main shaft is connected with the cylinder body through the internal spline 10 and drives the cylinder body to rotate, and the cylinder body is supported by a front bearing 1 and a rear bearing 8 and is fixedly and limitedly arranged in an outer shell 15. The external motor drives the main shaft 27, the main shaft 27 drives the cylinder body 7 to rotate through a spline, the swash plate 17 and the thrust plate 35 are fixed during working, the piston 13 head is provided with the slipper 14, the slipper and the swash plate are in spherical contact, and a static pressure supporting structure is adopted to enable the slipper and the swash plate to be attached to each other all the time. When the cylinder 7 rotates, the plunger 13 is reciprocated under the combined action of the swash plate 17 and the low pressure oil, the volume of the seal cavity between each plunger 13 and the cylinder 7 is changed to increase or decrease, and oil is sucked and pressed through the window on the oil distribution disc 35. When the cylinder hole rotates upwards from the lowest position, the plunger 17 moves leftwards, the sealing volume between the end part of the plunger and the cylinder body 7 is increased, and oil is sucked through the oil suction window of the oil distribution disc 37; when the cylinder hole is rotated downward from the uppermost position, the plunger 13 is gradually pressed into the cylinder block 7 by the swash plate 17, the sealed volume between the end of the plunger 13 and the cylinder block 7 is reduced, and oil is pressed through the oil window via the oil distribution plate 37. When the cylinder rotates one time, each plunger 13 finishes oil absorption and oil pressing once respectively, the cylinder rotates continuously, and the plungers continuously absorb and press oil. Wherein the swash plate 17 is inclined at a certain angle with the cylinder block 7; the servo variable mechanism can drive the change of the inclination angle of the swash plate to carry out variable, when the swing angle is zero, the pump has zero displacement (namely, the displacement is zero), the swing angle of the swash plate is changed by the movement of the servo piston, and the movement of the servo piston is controlled by the control valve 21, the power valve 25 and the adjusting screw 26.

The cylinder body front boss structure comprises a front boss first section, a front boss second section and a front boss third section, the front boss first section and the cylinder body main body are of an integrated structure, the front boss second section and the front boss first section are of an integrated structure, the front boss third section and the front boss second section are of an integrated structure, and the front bearing is installed on the front boss third section. The cylinder body front boss structure is composed of a front boss first section, a front boss second section and a front boss third section, the three sections of boss structures are respectively installed and assembled with other parts of the pump, and the shaft diameters of the three sections of boss structures are gradually reduced according to the sizes of the other parts of the pump matched with the boss structures, so that the cylinder body front boss structure and the other parts of the pump are precisely installed and assembled: the third section of the front boss is used for mounting a bearing to realize the precise assembly with the bearing; the first section of the front boss and the second section of the front boss are used for being mounted and assembled with a spherical hinge part in the pump, and the rear boss of the cylinder body is provided with a stepped structure for mounting a gasket and a rear bearing so as to support and position the cylinder body.

The front bearing of the cylinder body arranged on the third section 2 of the front boss structure and the rear bearing arranged on the rear boss structure 9 are supported together, so that the load force and the bending moment of the cylinder body are more balanced, the problem that in the existing scheme, one bearing is completely supported by the outer ring of the cylinder body, so that the local area of the lateral force between the bearing and the cylinder body subjected to the bending moment is increased, and the friction and the abrasion are intensified is solved, and the kinematics and the dynamics performance of the cylinder body under the working conditions of ultrahigh pressure and high rotating speed are improved; the third section 2 of the front boss structure and the rear boss structure 9 of the front bearing and the rear bearing for installing and supporting the limit cylinder body can be flexibly designed according to the ultrahigh pressure load born by the bearing and the allowed high-speed rotation linear velocity, and have greater design flexibility and design space than the existing scheme The difficulty that the maximum rotating speed and the maximum displacement are greatly restricted creates extremely favorable conditions for the design of an ultrahigh pressure high rotating speed pump, in particular a large displacement pump.

In summary, the invention can realize the maximum reduction of the relative rotation linear velocity and the PV value between the cylinder outer surface and the contact surface of the support bearing because the outer diameters of the cylinder front boss structure and the cylinder rear boss structure for mounting the front bearing and the rear bearing are allowed to be optimally designed to be minimum, overcomes the problem of large bearing design technical difficulty caused by the overlarge cylinder outer diameter in the existing single bearing support scheme of the plunger pump cylinder outer ring, improves the expected service life and the reliability of the bearing, can enable the load force and the bending moment of the plunger pump cylinder to be more balanced through the common fixed limit action of the front bearing and the rear bearing on the cylinder, simultaneously only needs the main spindle to transmit torque, greatly reduces the deflection of the main spindle and the overturn of the cylinder, solves the problems that the cylinder is easy to overturn under the high rotating speed and ultrahigh pressure working condition, the main spindle deflection influences the flow distribution pair and the plunger pair sealing under the close association with the cylinder, Lubrication, load bearing, etc.

The embodiments described in this specification are merely illustrative of implementation forms of the inventive concept, and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments, but also encompasses equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. The utility model provides a high-speed swash plate formula axial plunger variable displacement pump of superhigh pressure which characterized in that: the hydraulic control system comprises a cylinder body, a front bearing, a rear bearing, a main shaft, a spring, a swing seat, a swash plate, a sliding shoe, a plunger, a shaft sleeve, a flow distribution plate, a return plate, an auxiliary pump, a servo piston, a control valve, a spring base, a compression spring, an adjusting screw, a limiting plug, a shifting block, a sealing element, a shaft end cover, a rear end cover, an O-shaped ring and a fixing screw; the cylinder body comprises a cylindrical cylinder body main body, a front boss and a rear boss, the cylindrical cylinder body main body, the front boss and the rear boss form a whole, a plurality of axial plunger holes are uniformly distributed in the cylinder body main body, plungers are arranged in the plunger holes and are parallel to the axis of the cylinder body, and a plurality of lubricating oil guide holes are formed in the side surface of the cylinder body main body; the sealing element is arranged between the main shaft and the front end cover, the shaft end cover is fixedly arranged on the front shell through a screw, and an O-shaped sealing ring is arranged between the shaft end cover and the sealing element; the front bearing inner ring is arranged on the main shaft and is axially limited by a shaft shoulder on the main shaft, the left end surface of the swing seat, a gasket and an elastic check ring; the plunger piston and the piston shoe are hinged through a spherical hinge pair to form a plunger piston shoe assembly, the return disc is buckled and pressed on the piston shoe through a spherical hinge support, and the swash plate is arranged on the swing seat; the inclination angle of the swash plate is changed by pushing a servo variable mechanism to carry out variable, the servo variable mechanism comprises a servo piston, a control valve, a shifting block, a large servo piston spring, a limiting block and an adjusting screw, the servo piston is positioned by a plug and the limiting block, the bottom of a compression spring is fixed on a spring seat and spirally wound along the direction of the piston, the motion of the servo piston is controlled by a power valve, the control valve and the adjusting screw, and the control valve is fixed on the upper part of a rear end cover through a bolt; the flow distribution plate is fixedly arranged on the rear end cover through a pin, the front surface of the flow distribution plate is attached to the bottom surface of the cylinder body, and the back surface of the flow distribution plate is attached to the rear end cover; the rear end cover is internally provided with an auxiliary pump, an oil inlet and outlet flow passage, a shaft sleeve and a sealing ring, the flow passage in the rear end cover is streamline, the flow passage is connected with a notch on the valve plate, the center of the rear end cover is provided with a section matched with the outer ring of the bearing on the main shaft, and the diameter of the central hole of the rear end cover is set to be trapezoidal so as to be matched with the bearing and limit the axial displacement of the bearing; the rear end cover is connected with the outer shell through a fixing screw and supported on the main shaft through a needle bearing, a spline is arranged at the tail end of the main shaft and connected with the inner tooth shaft sleeve, a key groove is formed in the outer side of the inner tooth shaft sleeve and connected with a pinion in the auxiliary pump through a flat key;

the cylinder body is connected with the main shaft through a spline structure on a central hole of the cylinder body, the main shaft is connected with the prime motor, a front boss of the cylinder body comprises a first section of the front boss, a second section of the front boss and a third section of the front boss, the first section of the front boss and the cylinder body main body are of an integrated structure, the second section of the front boss and the first section of the front boss are of an integrated structure, the third section of the front boss and the second section of the front boss are of an integrated structure, the three sections of boss structures are respectively installed and assembled with other parts of the pump, and the shaft diameters of the three sections of boss structures are gradually reduced according to the sizes of the other parts of the pump matched with each other, so that the cylinder body and the other parts of the pump are accurately installed and assembled, wherein the third section of the front boss is used for installing a bearing, and the accurate assembly of the bearing is realized; the front boss first section and the front boss second section are used for mounting and assembling with a spherical hinge part in the pump, and the rear boss is provided with a stepped structure and is used for mounting a gasket and a rear bearing so as to realize supporting and positioning of the cylinder body;

2. The ultrahigh-pressure high-speed swash plate type axial plunger variable displacement pump according to claim 1, characterized in that: the needle roller bearing at the rear end of the main shaft for supporting the main shaft, and the needle roller bearings on the front boss of the cylinder body and the rear boss of the cylinder body for supporting the cylinder body are replaced by sliding bearings or bearing bushes.

3. The ultra-high pressure high speed swash plate axial plunger variable displacement pump of claim 1, wherein: the side surface of the main body of the plunger pump cylinder body is provided with 9 radial lubricating oil guide holes along the radial direction of the cylinder body, and the 9 radial lubricating oil guide holes are uniformly distributed around the cylinder body for a circle and penetrate to the central hole of the cylinder body; the bottom surface of the cylinder body which is attached to the thrust plate is also provided with 9 axial lubricating oil guide holes; the axial lubrication oil guide hole is communicated with the radial lubrication oil guide hole.