CN108167151A - A kind of symmetrical shaft type quantifies axial plunger pump and its control method - Google Patents

Abstract

A kind of symmetrical shaft type quantifies axial plunger pump and its control method, belongs to hydraulic pump unit technical field, is made of transmission shaft, bearing, axial positioning sleeve, housing unit, middle casing, drive ball pair, part of cylinder block, plunger bearing, plunger and valve plate；Plunger pump structure is novel, control method clear principle, the number of plunger is increased in the case where not increasing volume, simplify pump body structure, plunger quantity is more and is arranged symmetrically relative to plunger bearing, form self-lubricating and self sealing structure, pump housing pulsation is small, effectively reduces noise, compared with traditional swash plate pump, inclined shaft pump, its quality is lighter, and the cost of production is lower, and key is that it efficiently solves the technological deficiencies such as pressure fluctuation, axial force, output is more steady, further reduced production cost.

Description

A symmetrical through-shaft quantitative axial piston pump and its control method

technical field

The invention belongs to the technical field of hydraulic pump equipment, and relates to a plunger pump and a control method thereof, in particular to a symmetrical through-shaft quantitative axial plunger pump and a control method thereof.

Background technique

A complete machine is mainly composed of three parts: prime mover, transmission mechanism and working machine. Transmission mechanisms are usually divided into mechanical transmission, electrical transmission and fluid transmission; fluid transmission is a transmission in which fluid is used as the working medium for energy conversion, transmission and control, including liquid transmission and gas transmission. The hydraulic pumps that realize fluid transmission include gear pumps, screw pumps, vane pumps, and piston pumps.

The plunger pump is a positive displacement pump. Through the reciprocating movement of the plunger in the cylinder, the size of the closed space in the cylinder is changed to realize the suction and discharge of liquid. Because its main moving parts are cylindrical, it is easy to process and guarantees high matching precision, so it can ensure high volumetric efficiency under high working pressure. Radial plunger pumps and axial plunger pumps are the most common types of plunger pumps. Axial plunger pumps are important equipment in hydraulic systems. They are widely used in industrial equipment and engineering machinery due to their high efficiency and convenient variables. , Walking vehicles and other fields. Among them, axial piston pumps can be further divided into swash plate axial piston pumps and inclined axis axial piston pumps. When the axis of the cylinder block and the axis of the drive shaft coincide, it is called a swash plate axial piston pump; when the axis of the cylinder block and the axis of the drive shaft form an angle, it is called an inclined axis axial piston pump.

The advantages of the axial piston pump are high parameters, high efficiency, long life, convenient variable and many forms, light weight per unit power, the main parts of the piston pump are under compressive stress and the strength of the material can be fully utilized. The disadvantages of axial piston pumps are complex structure, large number of parts, poor self-priming and large pressure fluctuations, high manufacturing process requirements, high cost, and high noise.

Contents of the invention

The purpose of the present invention is to propose a symmetrical through-shaft quantitative axial plunger in view of the shortcomings of the existing axial plunger pump, such as high noise level, large flow and pressure fluctuations, large axial force, etc., and high production costs. The pump and its control method increase the number of plungers without increasing the volume, adopt a self-sealing structure, simplify the structure of the pump body, reduce the axial force, make the output more stable, and effectively solve the pressure pulsation, etc. Technical defects can effectively reduce noise and further reduce production costs.

The technical solution of the present invention is: a symmetrical through-shaft quantitative axial piston pump, characterized in that: the quantitative axial piston pump consists of a transmission shaft, a bearing, an axial positioning sleeve, a housing assembly, an intermediate housing , transmission ball pair, cylinder parts, plunger support, plunger and flow plate; holes, the cylindrical through hole is evenly arranged with a left spherical hinge support and a right spherical hinge support, the left end of the plunger support is provided with a left drive ball pair, and the right end of the plunger support is provided with a right Transmission ball pair, the outside of the left transmission ball pair is provided with a left cylinder part, and the outside of the right transmission ball pair is provided with a right cylinder part; the left cylinder part and the right cylinder part are both composed of cylinder liners, cylinder , the axial positioning ring and the axial positioning part of the ball pair. The axial positioning part of the ball pair is arranged inside the cylinder body. The screw connection is fixed on the right end surface of the cylinder block, and several cylinder liner installation holes are arranged on the left end surface of the cylinder block in the circumferential direction, and the cylinder liner is arranged in the cylinder liner installation holes, and the left cylinder body part A left plunger is provided between the cylinder liner in the right cylinder block and the left ball joint support, and a right plunger is provided between the cylinder liner in the right cylinder part and the right ball joint support, and the left side of the left transmission ball pair A left axial positioning sleeve is provided, a right axial positioning sleeve is provided on the right side of the right transmission ball pair, a left bearing is provided on the left side of the left axial positioning sleeve, and a right bearing is provided at the right end of the right axial positioning sleeve , the left housing assembly is sleeved on the left bearing, the right housing assembly is sleeved on the right bearing, and the inner end surfaces of the left housing assembly and the right housing assembly are equipped with inclined structures of swash plates, The upper end of the swash plate of the left housing assembly is provided with a left housing oil pressure window, and the other end is provided with a left housing oil suction window; the upper end of the swash plate of the right housing assembly is provided with a right housing oil pressure window, and the other end is provided with a There is an oil suction window on the right end shell, and the pressure oil window on the left end shell forms a phase angle with the pressure oil window on the right end shell; a left flow plate is arranged between the left shell assembly and the left cylinder part, and the right shell assembly and the right A right distribution plate is arranged between the cylinder parts, and the left and right distribution plates are respectively connected with the swash plate structure on the left housing assembly and the right housing assembly through elastic cylindrical pins, and the middle housing is connected by The bolts are connected and fixed between the left housing assembly and the right housing assembly. The outside of the middle housing is provided with an oil inlet and an oil outlet. The inside of the middle housing is provided with a middle oil suction groove and a middle pressure oil groove. The oil inlet is connected with the middle oil suction groove, the oil outlet is connected with the middle oil pressure groove, the left end of the middle oil suction groove is connected with the oil suction window of the left end shell, the right end of the middle oil suction groove is connected with the The oil suction window of the right end casing is connected, the left end of the middle oil pressure groove is connected with the oil pressure window of the left end casing, and the right end of the middle oil pressure groove is connected with the oil pressure window of the right end casing.

The middle part of the transmission shaft is provided with a spline, and the centers of the plunger support, the left drive ball pair and the right drive ball pair are all provided with spline holes.

The structure of the left plunger and the right plunger is the same, one end of the left and right plungers is a spherical structure, and the other end is a hemispherical structure, and the inside of the spherical structure and the hemispherical structure are provided with interconnected elongated holes, and the spherical structure is connected to the left and right. The spherical joint support is hinged and self-lubricating, and the hemispherical structure forms a sliding and sealed connection with the cylinder liner.

A washer and a sealing ring are arranged on the left outer side of the left bearing.

The left cylinder part and the right cylinder part, the left transmission ball pair and the right transmission ball pair, the left plunger and the right plunger, the left spherical joint support and the right spherical joint support are all centered on the plunger support. Axisymmetric setup.

The pressure oil window of the left end shell and the pressure oil window of the right end shell form a phase angle, and the range of the phase angle is 3° to 15°.

The numbers of the left plunger and the right plunger are the same, 7-12.

The inclination angles of the left and right distribution plates are the same, and the inclination angles are 3° to 9°.

A method for controlling a symmetrical through-shaft quantitative axial piston pump, characterized in that it comprises the following steps:

(1) The mechanism movement process of the axial piston pump;

(1-1) When external power provides power to the transmission shaft, the transmission shaft forms a rotational motion, and the transmission shaft transmits torque to the left drive ball pair, the right drive ball pair and the plunger support;

(1-2) The left drive ball pair, the right drive ball pair, and the plunger support respectively drive the left cylinder body part and the right cylinder body part to rotate and slightly swing, and the left and right plungers rotate at the same speed;

(1-3) The cylinder liner and the left and right plungers move and swing relative to each other at the same time to complete the oil suction and oil pressure actions;

(2) Suction oil process of axial piston pump;

(2-1) Oil suction is formed from plunger X ₁ to plunger X ₆ in the right housing assembly, and the cavity formed by each plunger and cylinder liner gradually increases from small to large, and the oil suction process is completed in the oil suction window;

(2-2) The pressure oil is formed from the plunger P ₁ to the plunger P ₆ in the right housing assembly, and the cavity formed by each plunger and the cylinder liner gradually becomes smaller, and the oil pressure process is completed in the oil pressure window ;

(2-3) Since the middle shell is equipped with a middle oil suction groove and a middle oil pressure groove, the left end of the middle oil suction groove is connected with the oil suction window of the left end shell, the right end of the middle oil suction groove is connected with the oil suction window of the right end shell, and the middle oil pressure groove is connected with the oil suction window of the right end shell. The left end is connected with the oil pressure window of the left end shell, and the right end of the middle oil pressure tank is connected with the oil pressure window (27) of the right end shell, and the process of oil suction and pressure is realized through the oil circuit connected with the middle pressure oil tank;

(2-4) The phase angle of the leading or lagging action formed between the pressure oil process of the left housing assembly and the pressure oil process of the right housing;

(3) Lubrication and sealing process of axial piston pump;

During the oil pressure process, the pressure increases from small to large, forcing the inner cavity of the plunger to slightly expand along its radial direction under the action of oil pressure, and the outer spherical surface of the plunger forms a sliding line contact with the inner wall of the cylinder liner to achieve sealing; at the same time, The self-lubrication of the plunger and the ball joint support is realized through the slender hole in the middle of the plunger.

The beneficial effects of the present invention are: the present invention provides a symmetrical through-shaft quantitative axial plunger pump and its control method. The number of the pump body simplifies the structure of the pump body. The number of plungers is large and symmetrically arranged with respect to the plunger support, forming a self-lubricating and self-sealing structure. The pump body has small pulsation, effectively reduces noise and axial force, and is different from traditional Compared with swash plate pumps and inclined shaft pumps, its weight is lighter and its production cost is lower. The key is that it effectively solves technical defects such as pressure pulsation, and its output is more stable, which further reduces production costs.

Description of drawings

Fig. 1 is a schematic diagram of the overall full-section structure of the present invention.

Fig. 2 is a schematic diagram of a full sectional structure of the housing assembly in the present invention.

Fig. 3 is a schematic diagram of the cross-sectional structure of the intermediate case removed from the direction A-A in Fig. 2 .

Fig. 4 is a schematic diagram of the cross-sectional structure of the left housing assembly in the B-B direction in Fig. 2 .

Fig. 5 is a schematic diagram of the cross-sectional structure of the right housing assembly in the direction C-C in Fig. 2 .

Fig. 6 is a schematic diagram of the structure of the intermediate casing rotated by 90° after being sectioned along the D-D direction in Fig. 3 .

Fig. 7 is a schematic diagram of a full cross-sectional structure in the E-E direction in Fig. 5 .

Fig. 8 is a schematic diagram of a full cross-section of the plunger support in the present invention together with the plunger and the spherical joint support.

FIG. 9 is a schematic diagram of a full cross-section of the F-F direction in FIG. 8 .

Fig. 10 is a schematic diagram of the assembly structure of the spherical joint support and the plunger support in the present invention.

Fig. 11 is a schematic structural view of the cylinder parts in the present invention.

Fig. 12 is a schematic diagram of the action sequence of the plunger in the present invention.

In the figure: drive shaft 1, sealing ring 2, gasket 3, left bearing 4, left valve plate 5, left drive ball pair 6, left cylinder part 7, middle housing 8, plunger support 9, right cylinder part 10. Right transmission ball pair 11, right valve plate 12, right bearing 13, right axial positioning sleeve 14, right housing assembly 15, connecting bolt 16, right plunger 17, left plunger 18, left housing assembly 19, Left axial positioning sleeve 20, oil inlet 21, oil outlet 22, middle oil suction groove 23, middle oil pressure groove 24, left end casing oil pressure window 25, left end casing oil suction window 26, right end casing oil pressure window 27, right end casing oil suction Window 28, swash plate 29, elastic cylindrical pin 30, left spherical joint support 31, right spherical joint support 32, spline hole 33, cylindrical through hole 34, cylinder liner 35, cylinder body 36, countersunk head screw 37, shaft To the positioning ring 38, the axial positioning part 39 of the ball pair, the cylinder liner installation hole 40, and the elongated hole 41.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing:

As shown in Figures 1 to 11, a symmetrical through-shaft quantitative axial piston pump consists of a transmission shaft 1, a bearing, an axial positioning sleeve, a housing assembly, an intermediate housing 8, a transmission ball pair, and a cylinder block , the plunger support 9, the plunger and the distribution plate; The left spherical hinge support 31 and the right spherical hinge support 32 are evenly staggered, the left end of the plunger support 9 is provided with the left transmission ball pair 6, the right end of the plunger support 9 is provided with the right transmission ball pair 11, and the left transmission ball The outside of ball pair 6 is provided with left cylinder part 7, and the outside of right drive ball pair 11 is provided with right cylinder part 10; The ring 38 and the ball pair axial positioning part 39 are formed. The ball pair axial positioning part 39 is arranged inside the cylinder body 36. The axial positioning ring 38 axially positions the ball pair axial positioning part 39 and passes the countersunk screw 37 It is connected and fixed on the right end face of the cylinder block 36. Several cylinder liner mounting holes 40 are arranged on the left end face of the cylinder block 36 in the circumferential direction, and the cylinder liner 35 is arranged in the cylinder liner mounting holes 40. A left plunger 18 is provided between the cover 35 and the left ball hinge support 31, a right plunger 17 is provided between the cylinder liner 35 in the right cylinder part 10 and the right spherical hinge support 32, and the left transmission ball pair 6 left A left axial positioning sleeve 20 is provided on the side, a right axial positioning sleeve 14 is provided on the right side of the right transmission ball pair 11, a left bearing 4 is provided on the left side of the left axial positioning sleeve 20, and a right axial positioning sleeve 14 is provided at the right end of the right axial positioning sleeve 14. Bearing 13, the left housing assembly 19 is sleeved on the left bearing 4, the right housing assembly 15 is sleeved on the right bearing 13, and the inner end surfaces of the left housing assembly 19 and the right housing assembly 15 all have the inclination of the swash plate 29 One end of the swash plate 29 of the left housing assembly 19 is provided with a left housing pressure oil window 25, and the other end is provided with a left housing oil suction window 26; the upper end of the swash plate 29 of the right housing assembly 15 is provided with a right housing pressure oil window. Window 27, the other end is provided with the oil suction window 28 of the right end shell, and the pressure oil window of the left end shell forms a phase angle with the pressure oil window of the right end shell; a left valve plate 5 is provided between the left housing assembly 19 and the left cylinder part 7, A right distribution plate 12 is arranged between the right housing assembly 15 and the right cylinder part 10, and the left distribution plate 5 and the right distribution plate 12 are respectively connected to the inclined pins on the left housing assembly 19 and the right housing assembly 15 through elastic cylindrical pins 30. The disc structure is connected, and the middle casing 8 is connected and fixed between the left casing assembly 19 and the right casing assembly 15 through connecting bolts 16. The outside of the middle casing 8 is provided with an oil inlet 21 and an oil outlet 22. The middle casing The body 8 is provided with a middle oil suction groove 23 and a middle oil pressure groove 24, the oil inlet 21 is connected with the middle oil suction groove 23, the oil outlet 22 is connected with the middle oil pressure groove 24, the left end of the middle oil suction groove 23 is connected with the oil suction window of the left end shell 26 is connected, the right end of the middle oil suction groove 23 is connected with the oil suction window 28 of the right end shell, the left end of the middle oil pressure groove 24 is connected with the oil pressure window 25 of the left end shell, and the right end of the middle oil pressure groove 24 is connected with the oil pressure window 27 of the right end shell .

As shown in Figure 1, a symmetrical through-shaft quantitative axial plunger pump, the middle part of the transmission shaft 1 is provided with a spline, and the plunger support 9, the left transmission ball pair 6 and the right transmission ball pair are connected with it. 11 centers are provided with spline holes 33. The left and right cylinder parts 7, the plunger support 9 and the left and right transmission ball pairs 8 are driven by the transmission shaft 1 to rotate at constant angular speeds to ensure that the left and right plungers and cylinder liners 35 rotate at constant angular speeds; the ball pair axial positioning parts 39 make the cylinder The body part and the transmission ball pair swing left and right along the surface of the ball pair, and the inner spline of the cylinder body part meshes with the outer spline of the transmission ball pair to realize the transmission of circular power. The number of splines of the drive shaft, left and right cylinder parts, plunger and left and right drive ball pairs depends on the number of double hinge plunger assemblies installed on the plunger parts; The phase angle between them is also related to the number of splines between the transmission shaft, the left and right cylinder parts, the plunger parts and the left and right transmission ball pairs. For example, when the number of double-hinge plunger components on the left and right of the plunger support is 12, if there is a phase difference, such as a difference of 15°, the number of splines is 12 teeth.

As shown in Figure 8, a symmetrical through-shaft quantitative axial piston pump, the left plunger 18 and the right plunger 17 have the same structure, one end of the left and right plungers is a spherical structure, the other end is a hemispherical structure, and the spherical structure Interconnected elongated holes 41 are provided inside the hemispherical structure, the spherical structure is hingedly connected with the left and right spherical hinge supports, and the hemispherical structure forms a sliding and sealed connection with the cylinder liner. When the high-pressure liquid is filled, the inner cavity of the left and right plungers (one end of the hemispherical structure) is forced to slightly expand along its radial direction under the action of oil pressure, and the outer spherical surface of the plunger forms a sliding line contact seal with the inner wall of the cylinder liner.

As shown in Figure 1, a symmetrical through-shaft quantitative axial piston pump, the left outer side of the left bearing is provided with a gasket 3 and a sealing ring 2; the left cylinder part 7 and the right cylinder part 10, the left transmission ball pair 6 And the right transmission ball pair 11, the left plunger 18 and the right plunger 17, the left spherical hinge support 31 and the right spherical hinge support 32 are all axisymmetrically arranged with the plunger support 9 as the center. The cylinder liner is fixedly connected to the cylinder body through interference fit, and the movement of the cylinder body parts is realized through the cooperation of the axial positioning part of the ball pair and the transmission ball pair, and the relative movement between the double-hinged plunger and the cylinder liner and the pumping of liquid within a circle are completed. , pump out; the left and right cylinder parts and the left and right flow plates form the flow distribution pair and the oil circuit.

As shown in Figure 1, a symmetrical through-shaft quantitative axial piston pump has a phase angle formed by the suction oil window of the left end casing and the suction pressure oil window of the right end casing, and the value range of the phase angle is 3° to 15°.

As shown in Figure 8, a symmetrical through-shaft quantitative axial plunger pump has the same number of left plunger 18 and right plunger 17, which are 7 to 12; The inclination angle is the same, and the inclination angle is 3-9°.

As shown in Figure 1, a control method for a symmetrical through-shaft quantitative axial piston pump includes the following steps:

(1) The mechanism movement process of the axial piston pump;

(1-1) When external power provides power to the transmission shaft 1, the transmission shaft 1 forms a rotary motion, and the transmission shaft 1 transmits torque to the left drive ball pair 6, the right drive ball pair 11 and the plunger support 9;

(1-2) The left transmission ball pair 6, the right transmission ball pair 11, and the plunger support 9 respectively drive the left cylinder body part 7 and the right cylinder body part 10 to rotate and slightly swing; the constant angular velocity of the plunger and the constant angular velocity of the cylinder liner Rotation realization path: the transmission shaft is connected with the plunger support and the transmission ball pair through splines, and at the same time drives the plunger support, the transmission ball pair and their rotation at the same angular velocity; and the transmission ball pair and the cylinder parts are also connected through splines. They also rotate at constant angular velocities. Therefore, when the transmission shaft 1 rotates, the plunger fixed on the plunger support rotates at the same angular velocity as the cylinder part at the same angular velocity.

(1-3) The path of the axial swing of the cylinder parts: no matter whether the valve plate is fixed or the angle is changed, the end face of the cylinder part always cooperates with the valve plate, and there is a relative rotational movement between them and a sealing effect , to achieve the needs of liquid pumping, pumping out or flow change. The transmission ball pair cooperates with the axial positioning part of the ball pair, and the axial positioning part of the ball pair is fixedly connected to the cylinder body through the axial positioning ring. When the transmission shaft drives the transmission ball pair and the distribution plate to produce relative rotation, the distribution plate pushes the axial positioning part of the ball pair and then drives the cylinder parts to swing relative to each other to realize the relative movement between the plunger and the cylinder liner, and then through the valve on the distribution plate The oil suction window, the oil pressure window and related oil circuits realize the pumping and pumping of liquid. The cylinder liner and the left and right plungers move and swing relative to each other at the same time to complete the oil suction and oil pressure actions;

(2) The oil suction process of the axial piston pump (take the right housing assembly in Figure 4 and the white plunger in Figure 12 as examples);

(2-1) Oil suction is formed from plunger X ₁ to plunger X ₆ in the right housing assembly 15, and the cavity formed by each plunger and cylinder liner 35 gradually increases from small to large, and the oil suction process is completed in the oil suction window;

(2-2) The pressure oil is formed from the plunger _P1 to the plunger _P6 in the right housing assembly 15, and the cavity formed by each plunger and the cylinder liner 35 gradually becomes smaller, and the pressure is completed in the oil pressure window. oil process;

(2-3) Since the middle shell 8 is provided with a middle oil suction groove 23 and a middle pressure oil groove 24, the left end of the middle oil suction groove 23 communicates with the oil suction window 26 of the left end shell, and the right end of the middle oil suction groove 23 communicates with the oil suction window 28 of the right end shell. The left end of the middle oil pressure groove 24 is connected with the oil pressure window 25 of the left end shell, the right end of the middle oil pressure groove 24 is connected with the oil pressure window 27 of the right end shell, and the oil suction process is realized through the oil circuit connected by the middle pressure oil groove;

(2-4) The phase angle of the leading or lagging action formed between the pressure oil process of the left housing assembly and the pressure oil process of the right housing;

(3) Lubrication and sealing process of axial piston pump;

During the oil pressure process, the pressure increases from small to large, forcing the inner cavity of the plunger to slightly expand along its radial direction under the action of oil pressure, and the outer spherical surface of the plunger forms a sliding line contact with the inner wall of the cylinder liner to achieve sealing; at the same time, The self-lubrication of the plunger and the ball joint support is realized through the slender hole in the middle of the plunger.

Example 1

A symmetrical through-shaft quantitative axial plunger pump, the displacement per revolution is 120ml, the number of plungers is 24, the inclination angle of the oil distribution plate is 9°, and the rotation speed is 2000r/min.

The running effect is as follows:

(1) The output of the pump is more stable and the pulsation is small: only 1/4 of the flow pulsation of the swash plate pump and the inclined shaft pump.

(2) High efficiency: at the speed of 2000r/min, the transmission efficiency is 92.4%.

(3) Low noise: about 67dbA.

(4) Light weight: about 20KG, while the inclined shaft pump is about 26KG, and the swash plate pump is about 50KG.

Claims (9)

1. A symmetrical through-shaft quantitative axial piston pump, characterized in that: the quantitative axial piston pump consists of a drive shaft (1), a bearing, an axial positioning sleeve, a housing assembly, and an intermediate housing (8 ), a transmission ball pair, a cylinder block, a plunger support (9), a plunger and a flow plate; The circumferential direction of the seat (9) is provided with several cylindrical through holes (34), and the left spherical joint support (31) and the right spherical joint support (32) are evenly interlaced in the said cylindrical through holes (34). The left end of the plunger support (9) is provided with a left transmission ball pair (6), the right end of the plunger support (9) is provided with a right transmission ball pair (11), and the left transmission ball pair (6) The outside is provided with a left cylinder part (7), and the outside of the right transmission ball pair (11) is provided with a right cylinder part (10); the left cylinder part (7) and the right cylinder part (10) are composed of Cylinder liner (35), cylinder body (36), axial positioning ring (38) and ball pair axial positioning part (39), and described ball pair axial positioning part (39) is arranged on the cylinder body (36) Inside, the axial positioning ring (38) is connected and fixed on the right end surface of the cylinder (36) through the countersunk screw (37) after axially positioning the ball pair axial positioning member (39), and the cylinder (36) is provided with several cylinder liner mounting holes (40) in the circumferential direction on the left end surface, and the cylinder liner (35) is arranged in the cylinder liner mounting hole (40), and the left cylinder body part (7) A left plunger (18) is arranged between the cylinder liner (35) in the middle and the left ball joint support (31), and the cylinder liner (35) in the right cylinder part (10) and the right ball joint support ( 32) is provided with a right plunger (17), the left axial positioning sleeve (20) is provided on the left side of the left transmission ball pair (6), and the right shaft is provided on the right side of the right transmission ball pair (11). To the positioning sleeve (14), the left bearing (4) is provided on the left side of the left axial positioning sleeve (20), the right bearing (13) is provided at the right end of the right axial positioning sleeve (14), and the left bearing (4) The left housing assembly (19) is sleeved on the upper part, the right housing assembly (15) is sleeved on the right bearing (13), and the left housing assembly (19) and the right housing assembly (15) ) has an inclined structure with a swash plate (29) on the inner end surface, and the upper end of the swash plate (29) of the left housing assembly (19) is provided with a left end shell pressure oil window (25), and the other end is provided with a left end shell The oil suction window (26); the upper end of the swash plate (29) of the right housing assembly (15) is provided with the right end shell oil pressure window (27), the other end is provided with the right end shell oil suction window (28), and the left end shell suction pressure The oil window and the suction pressure oil window of the right end shell form a phase angle; a left valve plate (5) is arranged between the left housing assembly (19) and the left cylinder part (7), and the right housing assembly (15) A right valve plate (12) is arranged between the right cylinder part (10), and the left valve plate (5) and the right valve plate (12) are respectively connected to the left housing assembly (19) through elastic cylindrical pins (30) , the swash plate structure on the right housing assembly (15), the middle housing (8) through The connecting bolt (16) is connected and fixed between the left housing assembly (19) and the right housing assembly (15), and the outside of the middle housing (8) is provided with an oil inlet (21) and an oil outlet ( 22), the middle housing (8) is provided with a middle oil suction groove (23) and a middle pressure oil groove (24), the oil inlet (21) is connected with the middle oil suction groove (23), and the oil outlet The port (22) communicates with the middle oil pressure groove (24), the left end of the middle oil suction groove (23) communicates with the left end shell oil suction window (26), and the right end of the middle oil suction groove (23) communicates with the The oil suction window (28) of the right end shell is connected, the left end of the middle oil pressure groove (24) is connected with the oil pressure window (25) of the left end shell, and the right end of the middle oil pressure groove (24) is connected with the right end shell. The oil window (27) is connected. 2. A symmetrical through-shaft quantitative axial piston pump according to claim 1, characterized in that: the middle part of the transmission shaft (1) is provided with a spline, and the plunger support ( 9), the centers of the left drive ball pair (6) and the right drive ball pair (11) are all provided with spline holes (33). 3. A symmetrical through-shaft quantitative axial piston pump according to claim 1, characterized in that: the left plunger (18) and the right plunger (17) have the same structure, and one end of the left and right plungers It is a spherical structure, and the other end is a hemispherical structure. The interior of the spherical structure and the hemispherical structure are provided with interconnected elongated holes (41). Sealed connection. 4. A symmetrical through-shaft quantitative axial piston pump according to claim 1, characterized in that: a washer (3) and a sealing ring (2) are provided on the left outer side of the left bearing. 5. A symmetrical through-shaft quantitative axial piston pump according to claim 1, characterized in that: the left cylinder part (7) and the right cylinder part (10), the left drive ball pair (6 ) and the right transmission ball pair (11), the left plunger (18) and the right plunger (17), the left spherical joint support (31) and the right spherical joint support (32) are all based on the plunger support (9) Axisymmetrically arranged as the center. 6. A symmetrical through-shaft quantitative axial piston pump according to claim 1, characterized in that: the suction oil window of the left end shell and the pressure oil window of the right end shell form a phase angle, and the value of the phase angle is The range is 3-15°. 7. A symmetrical through-shaft quantitative axial plunger pump according to claim 1, characterized in that: the number of the left plunger (18) and the right plunger (17) are the same, both are 7～ 12. 8. A symmetrical through-shaft quantitative axial piston pump according to claim 1, characterized in that: the inclination angles of the left valve plate (5) and the right valve plate (12) are the same, and the inclination angle is 3 ~9°. 9. A control method for a symmetrical through-shaft quantitative axial piston pump, characterized in that using the symmetrical through-axial quantitative axial piston pump according to any one of claims 1-8 comprises the following steps: (1) The mechanism movement process of the axial piston pump; (1-1) When external power provides power to the transmission shaft (1), the transmission shaft (1) forms a rotary motion, and the transmission shaft (1) transmits torque to the left transmission ball pair (6) and the right transmission ball pair (11) And plunger support (9); (1-2) The left transmission ball pair (6), the right transmission ball pair (11), and the plunger support (9) respectively drive the left cylinder body part (7) and the right cylinder body part (10) to rotate and slightly swing ; (1-3) Relatively move and swing between the cylinder liner (35) and the left and right plungers at the same time to complete the oil suction and oil pressure actions; (2) Suction oil process of axial piston pump; (2-1) Oil suction is formed from plunger X ₁ to plunger X ₆ in the right housing assembly (15), and the cavity formed by each plunger and cylinder liner (35) gradually increases from small to large, within the oil suction window Complete the oil absorption process; (2-2) Pressure oil is formed from plunger P ₁ to plunger P ₆ in the right housing assembly (15). The oil pressure process is completed in the window; (2-3) Since the middle shell (8) is provided with a middle oil suction groove (23) and a middle pressure oil groove (24), the left end of the middle oil suction groove (23) is connected with the left end shell oil suction window (26), and the middle oil suction The right end of the groove (23) communicates with the oil suction window (28) of the right end shell, the left end of the middle oil pressure groove (24) communicates with the oil pressure window (25) of the left end shell, and the right end of the middle oil pressure groove (24) communicates with the oil pressure window (28) of the right end shell. The windows (27) are connected together, and the oil pressure suction process is realized through the oil circuit connected by the middle pressure suction oil tank; (2-4) The phase angle of the leading or lagging action formed between the pressure oil process of the left housing assembly and the pressure oil process of the right housing; (3) Lubrication and sealing process of axial piston pump; During the oil pressure process, the pressure increases from small to large, forcing the inner cavity of the plunger to slightly expand along its radial direction under the action of oil pressure, and the outer spherical surface of the plunger forms a sliding line contact with the inner wall of the cylinder liner to achieve sealing; at the same time, The self-lubrication of the plunger and the ball joint support is realized through the slender hole in the middle of the plunger.