Fluid self-balancing mechanism of inlet and outlet high-pressure medium conveying displacement pump

Abstract

The invention discloses a fluid self-balancing mechanism of an inlet and outlet high-pressure medium conveying displacement pump, which comprises a fluid end and a power end, a plurality of groups of sealing cavity structures are arranged in a plunger rod sealing seat, and a main plunger and an auxiliary plunger drive a hydraulic medium to balance the high-pressure working condition of an inlet, so that the real-time balance of a hydraulic cavity is ensured; lubricating oil at the power end can normally enter the clearance of the copper shaft sleeve to form a complete oil film under the working condition of suction of high pressure, the friction coefficient and abrasion are reduced, and the problem that the clearance is extruded in the same direction under the working conditions of high inlet and high outlet, and consequently an oil way is blocked and burnt is solved. When a medium is discharged in a working state, high-pressure oil acts on the ring surface of the auxiliary plunger to play a role in equal-ratio boosting, so that the thrust of the plunger is reduced on year-on-year basis, the operation load is reduced on year-on-year basis, the pressure peak valley difference generated in suction and discharge circulation is reduced, the pulsation impact is reduced, and the effective work is increased; a pressure balance overflow valve is arranged inside, overpressure overflow is achieved, and stepless balance needed by suction pressure of the main plunger and the auxiliary plunger and working conditions is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of positive displacement pumps, in particular to a fluid self-balancing mechanism of a positive displacement pump for conveying high-pressure media at the inlet and outlet. Background Art

[0002] A positive displacement pump is a pump that uses the change in volume within the pump cylinder to transport liquid, such as a reciprocating pump, a metering pump, etc. A reciprocating pump is a pump that uses the reciprocating motion of a piston or plunger to transport liquid, and relies on the reciprocating motion of the piston or plunger to directly transport liquid in the form of static pressure energy.

[0003] Under normal working conditions, the low compressibility of liquid media is utilized. When the piston or plunger conveys such media, the potential energy of the liquid increases sharply, and a high head is obtained to achieve the purpose of high-pressure transportation. The main body of the plunger (piston) reciprocating pump includes a power end and a hydraulic end, wherein the power end is composed of a body, a crankshaft, a connecting rod, a crosshead, a bearing seat cover, a sealing box, etc., and the hydraulic end is composed of a pump body, a casing, a plunger (piston), a seal, a valve group, a liquid inlet manifold, a liquid discharge manifold, etc.

[0004] In order to improve the delivery efficiency, reduce noise pollution and leakage pollution, and meet the increasing demand for high-efficiency, energy-saving and environmentally friendly products. There are many high-stability reciprocating pumps on the market, but the existing technology is generally implemented under the intervention of on-site personnel or the cooperation of peripheral network control and adjustment structure, which has lag and may even cause irreversible damage in severe cases. In addition, when the existing reciprocating pump is used to transport imported high-pressure media, it is difficult for the pump to match the oil supply balance in real time based on the random changes in on-site working conditions, which will cause the crankshaft group at the power end to burn out, and the life of the sealing components inside the plunger will be affected to varying degrees. The vibration and noise of the whole machine will increase, and the life of most of the vulnerable parts of the pumps in use on site has not reached the life specified by the national standard, which is not ideal for actual practical benefits. Under the situation of energy conservation and emission reduction, users have increasingly increased their requirements for the life of reciprocating pump wearing parts. It is imperative to increase the life of bearings, sleeves, plungers, and packings, reduce maintenance intensity, and achieve real-time working condition matching of reciprocating pumps, zero leakage of media, and long life of wearing parts. The positive displacement pump with a self-balancing mechanism is the design basis for increasing the life of the power end bearing / sleeve, the hydraulic end plunger and packing, and reducing the vibration and noise of the whole machine. Summary of the invention

[0005] The present application provides a fluid self-balancing mechanism for an inlet and outlet high-pressure medium transport displacement pump, which is used to improve the pressure balancing performance of the high-pressure medium in the pump, and uses a combined hydraulic and mechanical structure to overcome the burning protection of wearing parts, improve the service life of the packing seal group and the pump valve, etc.

[0006] The present application provides a fluid self-balancing mechanism of an inlet and outlet high-pressure medium conveying displacement pump, comprising a hydraulic end and a power end, a plunger rod of the power end connected to the hydraulic end, a sealing seat being arranged at the front end of the plunger rod, at least a first sealing group, a second sealing group, and a packing sleeve and a compression nut blocking the opening of the sealing seat being arranged in the sealing seat, a main plunger and a sub-plunger being arranged at the front end of the plunger rod, the inner holes of the first packing group and the second packing group being matched with the outer diameters of the main plunger and the sub-plunger respectively, radial fine holes being arranged on the first sealing group and the second sealing group, a radial flow hole being arranged on the sealing seat relative to the gap between the first packing group and the second packing group, and the radial flow hole being connected to the hydraulic cavity arrangement of the hydraulic end.

[0007] Preferably, the power end also includes a motor and an eccentric shaft driven by the motor. The end of the plunger rod is connected to a crosshead rod, and the other end of the crosshead rod is connected to a connecting rod through a radially inserted crosshead pin. The connecting rod sleeve is arranged on the eccentric shaft of the power end, and a first copper sleeve is arranged between the crosshead rod and the crosshead pin, and a second copper sleeve is arranged between the connecting rod and the eccentric shaft.

[0008] Preferably, the hydraulic end is provided with a one-way inlet valve, a one-way outlet valve and a diaphragm head, and the diaphragm head is provided with three-end openings, wherein the one-way inlet valve and the one-way outlet valve are connected to the two ends of the diaphragm head, and a diaphragm is provided at the third opening and is connected to a hydraulic cylinder, and an oil replenishing valve, an overflow safety valve and a limit valve structure are provided on the hydraulic cylinder.

[0009] Preferably, a hydraulic chamber is provided between the diaphragm head and the hydraulic cylinder, the hydraulic chamber is divided into a medium chamber and an oil chamber by a diaphragm, the oil chamber is connected to the hydraulic chamber, and the medium chamber is provided with a liquid inlet channel and a liquid outlet channel respectively connected to a one-way inlet valve and a one-way outlet valve.

[0010] Preferably, the limit valve structure includes a diaphragm connecting column fixed to the diaphragm, a diaphragm valve sleeve and a spring. The diaphragm valve sleeve is also provided with an oil hole and a limit hole. The oil hole is connected to the hydraulic chamber, and the diaphragm connecting column is provided with a radially arranged limit groove.

[0011] Preferably, the overflow safety valve comprises a rated adjustment nut and a pressure spring, and the hydraulic cylinder is provided with an overflow hole connected to an inner valve cavity of the overflow safety valve, and the other end of the overflow hole is connected to the overflow groove cavity of the hydraulic cylinder.

[0012] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0013] 1. The displacement pump of the present invention forms a pressure balance by arranging multiple groups of sealed cavities (hydraulic medium sealing cavities and pressure balance cavities) and sealing groups in the sealing seat at the front end of the plunger rod, and cooperates with the main plunger and the auxiliary plunger of the plunger rod and the radial pores; the main and auxiliary plungers drive the hydraulic medium to balance the imported high pressure working condition, which can not only ensure that the hydraulic cavity itself can achieve real-time balance, but also achieve the lubricating oil at the power end can normally enter the bearing / sleeve clearance under the suction high pressure working condition, and form a complete oil film on the copper bearing / sleeve at the power end, thereby reducing the friction coefficient and wear, and solves the problem that the clearance is squeezed in the same direction under high inlet and high outlet working conditions, causing oil circuit closure and burning of bearings, sleeves, eccentric shafts, etc.

[0014] 2. The internal oil pressure balance method of the hydraulic end is adopted, and the real-time balance is achieved by using its own hydraulic chamber, avoiding the pressure source changes caused by the traditional external pressure-inducing structure and the corrosion of the pressure supply medium to the system.

[0015] 3. When the medium is discharged, the high-pressure oil acts on the auxiliary plunger ring surface, which boosts the plunger in proportion, thereby reducing the plunger thrust and the operating load. This reduces the pressure peak-to-valley difference generated in the suction and discharge working cycles, reduces the pulsation impact, and increases the effective work.

[0016] 4. Built-in pressure balance relief valve. Within the rated working range of the pump, overpressure relief can be achieved by adjusting the safety relief valve according to the user's pressure conditions, ensuring the stepless (within the rated pressure range) balance between the main and auxiliary plunger suction pressures and the working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a schematic structural diagram of the high-pressure medium delivery displacement pump of the present invention.

[0019] Figure 2 It is a schematic diagram of the hydraulic end structure of the present invention.

[0020] Figure 3 It is a schematic diagram of the power end structure of the present invention.

[0021] Figure 4 It is a schematic diagram of the power end driving structure of the present invention.

[0022] Figure 5 It is a schematic diagram of the limit valve structure of the present invention.

[0023] Explanation of the reference numerals: 1. hydraulic end; 10. diaphragm head; 11. one-way inlet valve; 12. one-way outlet valve; 13. diaphragm; 14. hydraulic cylinder; 141. overflow hole; 142. overflow groove; 15. oil replenishing valve; 16. overflow safety valve; 161. rated adjustment nut; 162. pressure spring; 163. inner valve cavity; 17. limit valve structure; 171. protective film connecting column; 172. protective film valve sleeve; 173. spring; 174. oil hole; 175. limit hole; 176. limit groove; 18. hydraulic cavity; 2. power end; 20. motor; 21. plunger Rod; 211, main plunger; 212, auxiliary plunger; 213, step surface; 22, crosshead rod; 23, crosshead pin; 24, connecting rod; 25, eccentric shaft; 28, second copper sleeve; 29, first copper sleeve; 3, sealing seat; 30, oil flow channel; 31, first sealing group; 32, first packing group; 33, second sealing group; 34, second packing group; 35, packing sleeve; 36, clamping nut; 37, radial flow hole; 38, radial pore; 5, hydraulic chamber; 51, medium chamber; 511, liquid inlet channel; 512, liquid outlet channel; 52, oil chamber. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0025] like Figure 1-5 The fluid self-balancing mechanism of an inlet and outlet high-pressure medium conveying displacement pump of the present invention is shown, comprising a hydraulic end 1 and a power end 2, a plunger rod 21 of the power end 2 connected to the hydraulic end 1, a sealing seat 3 is arranged at the front end of the plunger rod 21, at least a first sealing group 31, a first packing group 32, a second sealing group 33, a second packing group 34 and a packing sleeve 35 and a clamping nut 36 blocked at the opening of the sealing seat 3 are arranged in the sealing seat 3, a main plunger 211 and a sub-plunger 212 are arranged at the front end of the plunger rod 21, the inner holes of the first packing group 32 and the second packing group 34 are matched with the outer diameters of the main plunger 211 and the sub-plunger 212 respectively, radial pores 38 are arranged on the first sealing group 31 and the second sealing group 33, radial flow holes 37 are arranged on the sealing seat 3 relative to the gap between the first packing group 32 and the second packing group 34, and the radial flow holes 37 are connected to the hydraulic chamber 18 of the hydraulic end 1.

[0026] As a further configuration of the above-mentioned invention scheme, the power end 2 also includes a motor 20, an eccentric shaft 25 driven by the motor 20, a cross rod 22 is connected to the end of the plunger rod 21, and the other end of the cross rod 22 is connected to a connecting rod 24 through a radially inserted cross pin 23, and the connecting rod 24 is sleeved on the eccentric shaft 25 of the power end 2, a first copper sleeve 29 is arranged between the cross rod 22 and the cross pin 23, and a second copper sleeve 28 is arranged between the connecting rod 24 and the eccentric shaft 25.

[0027] As a further configuration of the above-mentioned invention scheme, the hydraulic end 1 is provided with a one-way inlet valve 11, a one-way outlet valve 12 and a diaphragm head 10, and the diaphragm head 10 is provided with three-end openings, wherein the one-way inlet valve 11 and the one-way outlet valve 12 are connected to the two ends of the diaphragm head 10, and a diaphragm sheet 13 is provided at the third opening and is connected to a hydraulic cylinder 14, and an oil replenishing valve 15, an overflow safety valve 16 and a limit valve structure 17 are provided on the hydraulic cylinder 14.

[0028] As a further configuration of the above-mentioned invention scheme, a hydraulic chamber 5 is arranged between the diaphragm head 10 and the hydraulic cylinder 14, and the hydraulic chamber 5 is divided into a medium chamber 51 and an oil chamber 52 by a diaphragm sheet 13, and the oil chamber 52 is connected to the hydraulic chamber 18, and the medium chamber 51 is provided with a liquid inlet channel 511 and a liquid outlet channel 512 which are respectively connected to the one-way inlet valve 11 and the one-way outlet valve 12.

[0029] As a further configuration of the above-mentioned invention scheme, the limit valve structure 17 includes a diaphragm connecting column 171 fixed to the diaphragm 13, a diaphragm valve sleeve 172 and a spring 173. The diaphragm valve sleeve 172 is also provided with an oil hole 174 and a limit hole 175. The oil hole 174 is connected to the hydraulic chamber 18, and the diaphragm connecting column 171 is provided with a radially arranged limit groove 176.

[0030] As a further configuration of the above-mentioned invention scheme, the overflow safety valve 16 includes a rated adjustment nut 161 and a pressure spring 162. The hydraulic cylinder 14 is provided with an overflow hole 141 connected to an inner valve chamber 163 of the overflow safety valve 16. The other end of the overflow hole 141 is connected to the overflow groove chamber 142 of the hydraulic cylinder 14.

[0031] like Figure 1-5As shown, the displacement pump of this embodiment includes a hydraulic end 1 and a power end 2. The displacement pump of the present invention refers to the existing common technology, and the plunger rod 21 of the power end 2 is connected to the hydraulic end 1 as the basic structure. On the above-mentioned basic structure, a sealing seat 3 is arranged at the front end of the plunger rod 21 of this embodiment, and a first sealing group 31, a first packing group 32, a second sealing group 33, a second packing group 34, a packing gland 35 and a clamping nut 36 are arranged in sequence in the sealing seat 3, wherein the packing gland 35 is blocked behind the second packing group 34, forming an installation of the first sealing group 31, the first packing group 32, the second sealing group 33, and the second packing group 34 inside. The piston rod 21 is compressed and fixed by a clamping nut 36, and the front end of the piston rod 21 is located in the sealing seat 3, and is provided with a main piston 211 and a sub-plunger 212. The inner holes of the first packing group 32 and the second packing group 34 are respectively matched with the outer diameters of the main piston 211 and the sub-plunger 212. Driven by the motor 20, the piston rod 21 performs reciprocating telescopic activities relative to each other. The first sealing group 31 and the second sealing group 33 are both provided with radial pores 38. The sealing seat 3 is provided with a radial flow hole 37 in the gap between the first packing group 32 and the second packing group 34. The radial flow hole 37 is connected to the hydraulic chamber 18 of the hydraulic end 1.

[0032] As described above, the design features of the displacement pump of the present invention are included in the action of the plunger rod 21 as described above:

[0033] ① Driven by the motor 20, the plunger rod 21 moves to the right. The plunger rod 21 pulled to the right forms a negative pressure in the hydraulic chamber 18, the diaphragm 13 bulges to the right, the medium chamber 51 expands, the one-way outlet valve 12 is closed under the internal pressure, and the blocking ball of the one-way inlet valve 11 is adsorbed by the medium pressure and moves upward, so that the spring is compressed to release the flow channel, and the high-pressure medium flows in from the outside of the one-way inlet valve 11. At the plunger rod 21, based on the radial pores 38 on the second sealing group 33 and the radial flow holes 37 of the sealing seat 3, the oil between the second packing group 34 and the first packing group 32 flows out of the sealing seat 3 along the oil flow channel 30 and enters the hydraulic chamber 18.

[0034] ② In the state of ①, the motor 20 is continuously driven, the plunger rod 21 moves to the left, the oil in the hydraulic chamber 18 is squeezed by the plunger rod 21, and the oil flows to the oil chamber 52 and flows through the oil flow channel 30 to the area of ​​the sealing seat 3 relative to the first packing group 32 and the second packing group 34. The diaphragm 13 is driven by the oil to bulge toward the diaphragm head 10 side, and the pressure is transmitted to the medium chamber 51. The high-pressure medium in the medium chamber 51 flows from the one-way outlet valve 12 to reduce the oil pressure balance in the oil chamber 52. , the compression spring pushes open the blocking bead, and the high-pressure medium flows out. At the same time, the oil flowing into the sealing seat 3 also forms a certain pressure behind the step surface 213 of the main plunger 211 and the auxiliary plunger 212, which boosts the movement of the main plunger 211 and has a proportional boosting effect on the plunger rod 21, so that the thrust of the plunger rod 21 of the motor 20 is reduced year-on-year, the operating load is reduced year-on-year, the pressure peak-to-valley difference generated in the suction and discharge working cycles is reduced, the pulsation impact is reduced, and the effective work is increased.

[0035] The present invention adopts the structural arrangement of the main plunger 211 and the auxiliary plunger 212 of the plunger rod 21 in cooperation with the sealing seat 3. When in use, the plunger rod 21 reciprocates between ① and ②, and the oil flow channel 30 is connected, so that the pressure of the oil in the hydraulic chamber 18 on the moving plunger rod 21 itself is relatively small, and the plunger rod 21 in the prior art is reduced, which reduces the problem of difficulty in the movement of the plunger rod 21 caused by the reverse oil pressure of the high-pressure oil in the hydraulic chamber 18, and reduces the axial pressure of the plunger rod 21; and in this embodiment, the oil entering between the double packings from the oil flow channel 30 can also form lubrication on the surface of the plunger rod 21, and the friction and wear of the plunger rod 21 when sliding relative to the first packing group 32 and the second packing group 34 are reduced.

[0036] In addition, the hydraulic cylinder 14 of the present invention is provided with an overflow hole 141 at a relative position. Figure 2 As shown, the overflow hole 141 of the present invention is connected to the inner valve chamber 163 of the overflow safety valve 16, and the other end is connected to the overflow groove chamber 142 of the hydraulic cylinder 14. When the pressure in the hydraulic chamber 18 in the hydraulic cylinder 14 is over-pressured, the overflow safety valve 16 opens the flow channel of the inner valve chamber 163, so that the oil flows out through the inner valve chamber 163 and the overflow hole 141, and the pressure in the hydraulic chamber 18 is relieved to avoid the negative impact of overpressure on the device. When the overflow safety valve 16 of the present invention is in use, the rated cavity pressure of the pressure regulating device for the pressure spring 162 can be adjusted by rotating the rated adjusting nut 161. The setting of the overflow hole 141 can ensure automatic over-pressure balance protection in the pump.

[0037] Furthermore, the motor 20 of the power end 2 of the present invention is connected to the eccentric shaft 25, and the motor drives the eccentric shaft 25 to rotate, and the end of the plunger rod 21 is connected to the cross rod 22, and the other end of the cross rod 22 is connected to the connecting rod 24 sleeved on the eccentric shaft 25 through a radially inserted cross pin 23. The design different from the prior art is that a first copper sleeve 29 is provided between the cross rod 22 and the cross pin 23 of the present invention, and a second copper sleeve 28 is provided between the connecting rod 24 and the eccentric shaft 25;

[0038] As described above, the present invention sets a first copper sleeve 29 between the cross rod 22 and the cross pin 23 of the prior art, so that when the plunger rod 21 is reciprocatingly extended and retracted by the motor 20, the first copper sleeve 29 transmits the rotation between the cross rod 22 and the cross pin 23, thereby forming an alternative friction and wear between the cross rod 22 and the cross pin 23, and providing a buffer and a movable gap when the plunger rod 21 is located at the extreme position. Compared with the cross rod 22 and the cross pin 23 directly plug-in and tighten the structure of the prior art, the first copper sleeve 29 of this embodiment has movable gaps on both the inner and outer sides, which can form an oil film to reduce friction. The setting of the second copper sleeve 28 replaces the bearing set there in the prior art. The setting of the second copper sleeve 28 can not only reduce wear, but also solve the problem that the bearing is easily damaged. The second copper sleeve 28 of the present invention is easy to process with low cost and is not prone to wear and other problems.

[0039] As a further configuration of the above-mentioned invention scheme, the limit valve structure 17 includes a diaphragm connecting column 171 fixed to the diaphragm 13, a diaphragm valve sleeve 172 and a spring 173. The diaphragm valve sleeve 172 is also provided with an oil hole 174 and a limit hole 175. The oil hole 174 is connected to the hydraulic chamber 18, and the diaphragm connecting column 171 is provided with a radially arranged limit groove 176.

[0040] In summary, the displacement pump of the present invention adopts a copper sleeve to replace the original bearing and other structures, and forms a complete oil film on the copper bushing / sleeve at the power end. The oil film rotates to reduce the friction coefficient and wear. It not only has high wear resistance, but also has the characteristics of small structural space and simple maintenance compared to the existing structure, providing more precise support and positioning for the equipment. The lubricating oil can more effectively form an oil film on the friction surface, thereby reducing the friction coefficient and wear.

[0041] The main and auxiliary plungers drive the hydraulic medium to balance the imported high pressure, which can not only ensure the real-time balance of the hydraulic chamber itself, but also reduce the back pressure on the hydraulic side of the plunger rod, so that the oil pressure on both sides of the plunger rod is balanced, so that the copper sleeve at the power end will not have a back pressure limit that affects the bearing / sleeve clearance, so that the matching clearance between the copper sleeve and the matching parts is stable during the driving process, which is convenient for forming a complete oil film, and solves the problem that the clearance is squeezed in the same direction under high inlet and high outlet conditions, causing oil circuit closure and burning of bearings, sleeves, eccentric shafts, etc.; avoid the pressure source changes and pressure supply medium caused by the external pressure-inducing structure of the traditional solution, which will cause corrosion to the system and affect the stability of use, and secondary pollution caused by the leakage of the pressure-inducing medium, etc.

[0042] In addition, when the medium is discharged in the working state, that is, the plunger rod moves to the left, the high-pressure medium enters the rear of the main plunger from the oil flow channel and acts on the step surface of the auxiliary plunger, which has a proportional boosting effect on the plunger rod, thereby reducing the plunger thrust year-on-year, reducing the operating load year-on-year, reducing the pressure peak-to-valley difference generated in the suction and discharge working cycles, reducing the pulsation impact, and increasing the effective work; the positive displacement pump of the present invention has a built-in pressure balance relief valve. Within the rated working range of the pump, it only needs to adjust the safety relief valve according to the user's pressure working conditions to achieve overpressure relief regulation, thereby ensuring the stepless (within the rated pressure range) balance between the suction pressure of the main and auxiliary plungers and the working conditions.

[0043] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A fluid self-balancing mechanism of an inlet and outlet high-pressure medium delivery displacement pump, comprising a hydraulic end (1) and a power end (2), wherein a plunger rod (21) of the power end (2) is connected to the hydraulic end (1), characterized in that: The front end of the plunger rod (21) is provided with a sealing seat (3), and the sealing seat (3) is provided with at least a first sealing group (31), a first stuffing group (32), a second sealing group (33), a second stuffing group (34), and a stuffing sleeve (35) and a clamping nut (36) blocking the opening of the sealing seat (3). The front end of the plunger rod (21) is provided with a main plunger (211) and a secondary plunger (212), and the inner holes of the first stuffing group (32) and the second stuffing group (34) respectively match the outer diameters of the main plunger (211) and the secondary plunger (212), and the first sealing group (31) and the second sealing group (33) are both provided with radial fine holes (38), and the sealing seat (3) is provided with radial flow holes (37) in the gap between the first stuffing group (32) and the second stuffing group (34), and the radial flow holes (37) are connected to the hydraulic chamber (18) of the hydraulic end (1).

2. The fluid self-balancing mechanism of the inlet and outlet high-pressure medium delivery displacement pump according to claim 1, characterized in that: The power end (2) further comprises a motor (20), an eccentric shaft (25) driven by the motor (20), a cross rod (22) connected to the end of the plunger rod (21), the other end of the cross rod (22) connected to a connecting rod (24) via a radially inserted cross pin (23), the connecting rod (24) sleeved on the eccentric shaft (25) of the power end (2), a first copper shaft sleeve (29) arranged between the cross rod (22) and the cross pin (23), and a second copper shaft sleeve (28) arranged between the connecting rod (24) and the eccentric shaft (25).

3. The fluid self-balancing mechanism of the inlet and outlet high-pressure medium delivery displacement pump according to claim 1, characterized in that: The hydraulic end (1) is provided with a one-way inlet valve (11), a one-way outlet valve (12) and a diaphragm head (10); the diaphragm head (10) is provided with three openings, wherein the one-way inlet valve (11) and the one-way outlet valve (12) are connected to the two ends of the diaphragm head (10); a diaphragm sheet (13) is provided at the third opening and is connected to a hydraulic cylinder (14); and an oil replenishing valve (15), an overflow safety valve (16) and a limit valve structure (17) are provided on the hydraulic cylinder (14).

4. The fluid self-balancing mechanism of the inlet and outlet high-pressure medium delivery displacement pump according to claim 3, characterized in that: A hydraulic chamber (5) is provided between the diaphragm head (10) and the hydraulic cylinder (14); the hydraulic chamber (5) is divided into a medium chamber (51) and an oil chamber (52) by a diaphragm sheet (13); the oil chamber (52) is connected to the hydraulic chamber (18); the medium chamber (51) is provided with a liquid inlet channel (511) and a liquid outlet channel (512) which are respectively connected to a one-way inlet valve (11) and a one-way outlet valve (12).

5. The fluid self-balancing mechanism of the inlet and outlet high-pressure medium delivery displacement pump according to claim 4, characterized in that: The limit valve structure (17) comprises a diaphragm connecting column (171) fixed to the diaphragm (13), a diaphragm valve sleeve (172) and a spring (173); the diaphragm valve sleeve (172) is also provided with an oil hole (174) and a limit hole (175); the oil hole (174) is connected to the hydraulic chamber (18); and the diaphragm connecting column (171) is provided with a radially arranged limit groove (176).

6. The fluid self-balancing mechanism of the inlet and outlet high-pressure medium delivery displacement pump according to claim 3, characterized in that: The overflow safety valve (16) comprises a rated adjustment nut (161) and a pressure spring (162); the hydraulic cylinder (14) is provided with an overflow hole (141) connected to an inner valve cavity (163) of the overflow safety valve (16); the other end of the overflow hole (141) is connected to an overflow groove cavity (142) of the hydraulic cylinder (14).

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