A variable displacement mechanical pump

Abstract

The present invention provides a variable displacement mechanical pump, which belongs to the technical field of fluid machinery. The variable displacement mechanical pump comprises: a pump body and a drive unit arranged on the pump body, the pump body having a cylinder body, and is characterized in that it also comprises: a capsule, the capsule comprises two fixing parts and a sealing part located between the two fixing parts, the sealing part is in contact with the inner wall of the cylinder body and can slide up and down inside the cylinder body, the two fixing parts are symmetrically arranged, and extend from the edge of the sealing part to the middle part; a shaft body, which is installed at the output end of the drive unit and passes through the two fixing parts of the capsule; the capsule is squeezed by two clamping parts, and under the action of the internal atmospheric pressure, the sealing part is pressurized, and the sealing part can be pushed outward to always be in contact with the inner wall of the cylinder body, thereby ensuring the sealing effect of the internal chamber of the cylinder body.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid machinery, and in particular relates to a variable displacement mechanical pump. Background Art

[0002] A mechanical pump consists of two main components: a motor and a pump body. In standard mechanical pumps, the motor drives the pump shaft via a belt; in direct-connected mechanical pumps, the motor is directly connected to the pump shaft, without an intermediate transmission link. Mechanical pumps extract gas from a container using the principle of gas expansion, compression, and exhaust. They are called mechanical pumps because they mechanically periodically change the volume of the pump's suction chamber, causing the gas in the container to continuously expand into the suction chamber through the pump's inlet and then be compressed and discharged through the exhaust port. There are three methods for varying the suction chamber volume: piston reciprocating, stator, and rotary vane. These are called reciprocating, stator, and rotary vane mechanical pumps, respectively.

[0003] In the Chinese patent with the authorization announcement number CN117927444B, a screw piston pump is disclosed, comprising a piston pump body and a servo motor, wherein the upper end surface of the piston pump body is fixedly connected to a support frame, the upper end of the support frame is fixedly connected to the servo motor, the output end of the servo motor is fixedly connected to a screw lever, the arc surface of the limit rod and the screw lever is provided with an adjustment device, the adjustment device comprises a movable frame, the surface of the movable frame is evenly fixedly connected to fixed columns, the fixed columns are all hollow structures and the hollow part is connected to the inner wall of the movable frame, a position-adjustable extrusion column is slidably provided in the fixed column, and the end of the extrusion column close to the screw lever is fixedly connected to an auxiliary block coated with lubricating oil. The present invention solves the problem that after the screw piston pump is operated for a long time, the upper end screw lever of the piston pump body will become unlubricated due to long-term friction, which will easily lead to positional offset damage between the entire screw lever and the movable plug.

[0004] However, although the above technical solution can lubricate the screw, it does not have the effect of lubricating the piston. As a result, after long-term use, the piston body and the cylinder body will rub against each other for a long time, which can easily cause wear of the piston sealing ring, resulting in poor sealing effect of the piston and affecting the working efficiency of the pump body. Summary of the Invention

[0005] The object of the present invention is to provide a variable displacement mechanical pump, aiming to solve the problem in the prior art that the piston in the screw piston pump is prone to wear of the sealing ring after long-term use, thereby leading to a decrease in the working efficiency of the pump body.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solution: a variable displacement mechanical pump, comprising: a pump body and a drive unit provided on the pump body, wherein the pump body has a cylinder body, and is characterized in that it further comprises:

[0007] The capsule includes two fixing portions and a sealing portion located between the two fixing portions. The sealing portion is in contact with the inner wall of the cylinder body and can slide up and down inside the cylinder body. The two fixing portions are symmetrically arranged and extend from the edge of the sealing portion to the middle;

[0008] The shaft is installed at the output end of the drive unit and passes through the two fixed parts of the capsule;

[0009] Two symmetrically arranged clamping parts are mounted on the shaft body, and the two clamping parts are used to fix the two fixing parts on the capsule respectively. When the two clamping parts are close to each other, the cavity in the capsule can be squeezed;

[0010] A limit block is provided at the bottom end of the shaft body, which can limit the downward movement of the clamping part located below. An external thread is provided on the shaft body near the clamping part located above. A nut is threadedly connected to the external thread and is abutted against the clamping part located above. A torsion spring is provided on the shaft body to apply a rotational torsion force to the nut, which can drive the nut to rotate so that the nut can push the clamping part located above to approach the clamping part located below.

[0011] A further technical solution of the present invention is that a positioning ring is provided in the capsule, a plurality of docking joints are provided on the positioning ring, an oil filling port is provided on the joint, an elastic member is provided on the joint so that the joint is located in the middle of the two clamping parts, and the oil outlet is opposite to the joint on the capsule. In a natural state, the oil filling port and the oil outlet are staggered with each other. When the elastic member is compressed, the oil filling port and the oil outlet coincide with each other. An oil storage chamber is provided in the middle of the shaft body, and an oil pipe connecting the oil storage chamber and the oil filling port is provided on the joint.

[0012] A further technical solution of the present invention is that the clamping part includes a fixing plate and a clamping plate, the fixing plate is located inside the capsule, and a screw is provided on the fixing plate that penetrates to the outside of the capsule. The clamping plate can slide along the axis of the screw so that the fixing part is located between the clamping plate and the fixing plate, and the clamping plate and the fixing plate clamp and fix the fixing part of the capsule through bolts.

[0013] A further technical solution of the present invention is that the material of the capsule is rubber, and the thickness of the sealing part is greater than the thickness of the fixing part.

[0014] A further technical solution of the present invention is that a concave edge is provided at the edge of the clamping portion, and an oil storage cavity is formed between the concave edge and the inner side wall of the cylinder body.

[0015] A further technical solution of the present invention is that the elastic member is arranged obliquely so that the joint is located in the middle of the two clamping parts and the joint is pushed toward the oil outlet.

[0016] A further technical solution of the present invention is that the shaft is provided with a limiting groove arranged along the length direction of the shaft, and the screw located above is provided with a slider sliding on the limiting groove, which is used to limit the rotation between the shaft and the screw located above.

[0017] A further technical solution of the present invention is that the shaft body passes through the two screws, and a sealing ring is provided between the shaft body and the screws. The sealing ring is located below the limiting groove. When the screw slides on the shaft body, the positions of the sealing ring and the limiting groove are staggered.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The capsule is squeezed by two clamping parts, and under the action of the internal atmospheric pressure, the sealing part is pressurized, which can push the sealing part outward to always fit with the inner wall of the cylinder, thereby ensuring the sealing effect of the internal chamber of the cylinder.

[0020] 2. By setting the torsion spring, the air pressure inside the capsule can be automatically compensated, thus avoiding the problem of reduced air pressure inside the capsule leading to poor sealing effect.

[0021] 3. By setting up the lubrication structure, the inner wall of the cylinder can be oiled to avoid excessive friction between the inner wall of the cylinder and the capsule, which will cause the capsule to wear too quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 It is a structural schematic diagram of a specific embodiment of the present invention;

[0024] Figure 2 It is an axonometric cross-sectional view of a specific embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the cooperation between the caplet and the cylinder in a specific embodiment of the present invention;

[0026] Figure 4 It is an axonometric cross-sectional view of an extruded structure according to a specific embodiment of the present invention;

[0027] Figure 5 It is an axonometric cross-sectional view of the lubrication structure in a specific embodiment of the present invention;

[0028] Figure 6 for Figure 2 A schematic diagram of the structure at point A in the middle;

[0029] Figure 7It is a structural schematic diagram of a positioning ring in a specific embodiment of the present invention.

[0030] In the figure: 1. Pump body; 11. Base; 12. Feed inlet; 13. Discharge outlet; 14. One-way valve; 15. Cylinder body; 16. Housing; 2. Drive unit; 3. Capsule; 31. Sealing part; 32. Fixing part; 33. Opening; 34. Oil outlet; 35. Narrowing; 4. Extrusion structure; 41. Shaft; 411. Limit block; 412. External thread; 413. Limit groove; 414. Storage Oil chamber; 42. Clamping part; 421. Fixing plate; 422. Clamping plate; 423. Screw; 43. Nut; 44. Torsion spring; 45. Fixing platform; 46. Sealing ring; 47. Slider; 5. Lubrication structure; 51. Positioning ring; 511. Joint; 512. Oil filling port; 513. Elastic part; 52. Oil delivery pipe; 53. Concave edge; 54. Oil storage chamber; 6. Flexible tube; 7. Pressure relief hole. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] See also Figure 1-Figure 7 , the present invention provides the following technical solutions: a variable displacement mechanical pump, comprising a pump body 1, a drive unit 2, a capsule 3, an extrusion structure 4 and a lubrication structure 5;

[0033] The driving unit 2, the capsule 3, the extrusion structure 4 and the lubrication structure 5 are all installed inside the pump body 1. The extrusion structure 4 is installed at the output end of the driving unit 2, so that the driving unit 2 drives the extrusion structure 4 to move up and down inside the pump body 1. The extrusion structure 4 is used to squeeze the capsule 3 and form a closed capsule cavity in the capsule 3. The lubrication structure 5 is installed inside the capsule 3 and can lubricate the capsule 3 through the movement of the capsule 3, thereby reducing the friction of the capsule 3.

[0034] The pump body 1 includes a base 11 placed vertically on the ground. The interior of the base 11 is hollow, and an inlet 12 and an outlet 13 are provided on the base 11. Both the inlet 12 and the outlet 13 are provided with a one-way valve 14. The one-way valve 14 on the inlet 12 only allows the fluid to enter the interior of the base 11, and the one-way valve 14 on the outlet 13 only allows the fluid to be discharged to the outside of the base 11.

[0035] A cylinder 15 is provided on the base 11. The inner wall of the cylinder 15 is cylindrical and communicates with the interior of the base 11. The periphery of the capsule 3 fits with the inner wall of the cylinder 15 and can move up and down inside the cylinder 15.

[0036] A housing 16 is provided above the cylinder 15, and a driving unit 2 is installed inside the housing 16. The driving unit 2 is a hydraulic cylinder, and its telescopic end is fixed to the extrusion structure 4, which can drive the extrusion structure 4 to drive the capsule 3 to slide up and down inside the cylinder 15;

[0037] When the driving unit 2 drives the extrusion structure 4 and the capsule 3 to move downward, due to the seal formed between the capsule 3 and the cylinder body 15, the fluid inside the cylinder body 15 and the base 11 can be pushed out from the discharge port 13 through the one-way valve 14. When the driving unit 2 drives the extrusion structure 4 and the capsule 3 to move upward, the fluid can be sucked into the base 11 from the feed port 12 through the one-way valve 14.

[0038] See also Figure 3 and Figure 4 The material of the capsule 3 can be rubber material to improve the sealing effect between the capsule 3 and the cylinder body 15. The capsule 3 is composed of a sealing portion 31 and two fixing portions 32. The sealing portion 31 is located between the two fixing portions 32, and the sealing portion 31 and the fixing portion 32 are integrally formed. The two fixing portions 32 are symmetrically arranged with each other, extending from the edge of the sealing portion 31 to the middle, forming a tire shape, that is, the cross section is a C-shaped with two openings facing each other (see Figure 7 ), the sealing portion 31 fits against the inner wall of the cylinder body 15 and is used to seal the cylinder body 15. The fixing portion 32 is installed on the extrusion structure 4. The extrusion structure 4 can fix the fixing portion 32 and form a sealed chamber inside the capsule 3. The thickness of the sealing portion 31 is greater than that of the fixing portion 32, so that the capsule 3 is more wear-resistant, thereby improving the service life of the capsule 3.

[0039] See also Figure 3 and Figure 4 The extrusion structure 4 includes a shaft 41 connected to the output end of the drive unit 2, and the upper and lower ends of the middle portion of the capsule 3 have openings 33 (see Figure 7), the shaft body 41 passes through the capsule 3 through the opening 33, and two clamping parts 42 are provided on the shaft body 41. The two clamping parts 42 are symmetrically arranged. The clamping part 42 can clamp and fix the fixing part 32. The clamping part 42 includes a fixing plate 421 and a clamping plate 422. The fixing plate 421 is located inside the capsule 3 and fits with the fixing part 32. A screw 423 extending outward through the opening 33 is provided on the fixing plate 421. The screw 423 passes through the middle of the clamping plate 422, and the clamping plate 422 can be clamped along The axis of the screw 423 slides so that the fixing portion 32 is located between the clamping plate 422 and the fixing plate 421. A bolt is installed on the screw 423, and the clamping plate 422 is fixed by the bolt, so that the clamping plate 422 and the fixing plate 421 clamp the fixing portion 32 of the capsule 3. At this time, when the two clamping portions 42 approach each other, the cavity inside the capsule 3 can be squeezed. It should be noted that the outer periphery of the clamping plate 422 also fits against the inner wall of the cylinder body 15, which can further improve the sealing effect of the cavity inside the cylinder body 15.

[0040] The shaft 41 passes through the two screws 423 and is coaxially arranged with the two screws 423. A sealing ring 46 is provided between the shaft 41 and the screw 423 to improve the sealing of the internal chamber of the capsule 3. A limiting block 411 is provided at the bottom of the shaft 41. The limiting block 411 is stuck at one end of the screw 423 below, so that the shaft 41 and the screw 423 below do not rotate relative to each other, and the screw 423 below is abutted against the limiting block 411 to limit the downward movement of the screw 423 on the shaft 41. An external thread 412 is provided at one end of the shaft 411 close to the drive unit 2. A nut 43 is threadedly connected to the external thread 412. One side of the nut 43 is engaged with the top of the screw 423 above. The two screw rods 423 are offset from each other by rotating the nut 43, and the screw rod 423 at the top is pushed downward, while the screw rod 423 at the bottom is limited by the limit block 411, so that the two screw rods 423 are close to each other, so that the two clamping plates 422 and the fixing plate 421 are close to each other, thereby achieving the purpose of squeezing the chamber inside the capsule 3. When the capsule 3 is worn, resulting in a deterioration in the seal with the cylinder body 15, the two clamping parts 42 are close to each other by rotating the nut 43, and the chamber inside the capsule 3 is squeezed. Under the action of the internal atmospheric pressure, the sealing part 31 is pressurized, and the sealing part 31 can be pushed outward to always fit the inner wall of the cylinder body 15, thereby ensuring the sealing effect of the chamber inside the cylinder body 15.

[0041] Since there is friction between the nut 43 and the screw rod 423 located above, when the nut 43 rotates, the friction will cause the clamping portion 42 located above to rotate, while the clamping portion 42 located below will not rotate under the action of the limit block 411, thereby causing the two clamping portions 42 to rotate, causing the capsule 3 to twist. In order to avoid the above situation, a limit groove 413 is provided on the shaft body 41 along the length direction of the shaft body 41. The limit groove 41 3 is located above the sealing ring 46. When the screw 423 slides on the shaft 41, the sealing ring 46 does not overlap with the position of the limiting groove 413. A slider 47 is provided on the screw 423 located above and slides on the limiting groove 413. When the nut 43 rotates, it can push the screw 423 located above to slide on the shaft 41. The limiting groove 413 and the slider 47 can prevent the screw 423 from rotating with the shaft 41, thereby preventing the capsule 3 from twisting.

[0042] Due to the friction of the sealing portion 31, the thickness will become thinner, and the volume of the cavity inside the capsule 3 will become larger. When the distance between the two clamping portions 42 remains unchanged, the air pressure inside the capsule 3 will become smaller, and the pressure exerted by the sealing portion 31 on the inner wall of the cylinder 15 will also become smaller, resulting in a worse sealing effect of the internal chamber of the cylinder 15. Therefore, a torsion spring 44 is provided on the shaft 41, and a fixing platform 45 is also fixed on the shaft 41. One end of the torsion spring 44 is fixed on the fixing platform 45, and the other end is fixed on the nut 43, so that the torsion spring 44 applies a rotational torsion force to the nut 43. When the torsion drives the nut 43 to rotate, it can push the nut 43 to rotate. The screw rod 423 located at the top is close to the screw rod 423 located at the bottom. In the initial state, the air pressure inside the capsule 3 is constant. At this time, the torsion force of the torsion spring 44 is not enough to push the nut 43 to rotate and move the nut 43 downward. When the air pressure inside the capsule 3 decreases, the downward resistance of the clamping part 42 located at the top to the nut 43 decreases. At this time, the torsion spring 44 can drive the nut 43 to rotate through the torsion force, so that the two clamping parts 42 are close to each other, thereby compensating for the air pressure inside the capsule 3. Through the setting of the torsion spring 44, the air pressure inside the capsule 3 can be automatically compensated, avoiding the problem of poor sealing effect caused by the reduction of air pressure inside the capsule 3.

[0043] See also Figure 5-Figure 7The lubricating structure 5 can apply oil to the inner wall of the cylinder 15 to reduce the friction between the inner wall of the cylinder 15 and the capsule 3, thereby reducing the wear on the capsule 3 and improving the sealing of the internal chamber of the cylinder 15. The lubricating structure 5 includes a positioning ring 51 provided in the capsule 3, and a plurality of docking joints 511 are provided on the positioning ring 51. The upper and lower ends of the joints 511 are provided with elastic members 513. The elastic member 513 is a compression spring, one end of which is fixed on the fixing plate 421, and the other end is fixed to the joint 511, so that the joint 511 can be just in the middle of the two fixing plates 421. The middle part of the capsule 3 is provided with a docking joint 511. The oil outlet 34 is adapted to the head 511, and the oil outlet 34 is connected to the inside and outside of the capsule 3. An oil filling port 512 is provided on the side of the joint 511 opposite to the oil outlet 34. When the elastic member 513 is in the natural state, the oil filling port 512 and the oil outlet 34 are staggered with each other, and there are two oil filling ports 512, located on the upper and lower sides of the oil outlet 34 respectively. A constriction 35 is provided on the oil outlet 34. When the elastic member 513 is in the natural state, the constriction 35 can cover the oil filling port 512. When the capsule 3 moves up and down relative to the joint 511, the oil outlet 34 and the oil filling port 512 can be overlapped, so that the oil outlet 34 and the oil filling port 512 are connected;

[0044] An oil delivery pipe 52 is provided on a side of the joint 511 away from the oil filling port 512. The oil delivery pipe 52 is connected to the oil filling port 512 through the joint 511. The end of the oil delivery pipe 52 away from the joint 511 is connected to the shaft body 41. An oil storage chamber 414 is provided in the middle of the shaft body 41. The oil storage chamber 414 is used to temporarily store lubricating oil. The oil delivery pipe 52 is connected to the interior of the oil storage chamber 414, so that the lubricating oil in the oil storage chamber 414 enters the oil filling port 512 through the oil delivery pipe 52.

[0045] During use, when the friction between the capsule 3 and the cylinder 15 is relatively large, the sealing portion 31 of the capsule 3 will be offset upward or downward as a whole under the action of the friction. For example, when the extrusion structure 4 drives the capsule 3 to move downward, the friction between the sealing portion 31 of the capsule 3 and the cylinder 15 will cause the sealing portion 31 to be offset upward or downward relative to the extrusion structure 4. The greater the friction, the greater the offset distance. Under the action of the elastic member 513, the joint 511 is always kept in the middle of the extrusion structure 4. When the sealing portion 31 is offset, the oil outlet 34 and the oil filling port 512 will overlap, and the greater the offset, the greater the overlap range. The lubricating oil in the oil storage chamber 414 can contact the inner wall of the cylinder body 15 through the oil pipe 52 and the overlapping oil outlet 34 and oil filling port 512, and drive the capsule 3 to move up and down reciprocatingly through the extrusion structure 4, so that the lubricating oil can be applied to the inner wall of the cylinder body 15 to reduce the friction between the capsule 3 and the inner wall of the cylinder body 15, thereby improving the service life of the capsule 3.

[0046] See also Figure 6 A concave edge 53 is provided at the edge of the clamping portion 42, and an oil storage chamber 54 is formed between the concave edge 53 and the inner wall of the cylinder body 15. The excess lubricating oil flowing out of the oil outlet 34 will fall into the interior of the oil storage chamber 54. Due to the limited number of oil outlets 34, it is difficult for the lubrication area to completely cover the sealing portion 31, which may result in a part of the sealing portion 31 not being lubricated. At this time, there is still a large friction between the sealing portion 31 and the inner wall of the cylinder body 15. At this time, the excess lubricating oil in the oil outlet 34 will flow into the oil storage chamber 54. As the lubricating oil in the oil storage chamber 54 increases, the lubricating oil in the oil storage chamber 54 is accumulated. The internal flow of the cavity 54, when the liquid level of the lubricating oil forms a complete ring, as the extrusion structure 4 slides up and down inside the cylinder body 15, the lubricating oil can be evenly applied to the inner wall of the cylinder body 15. When the friction between the sealing portion 31 and the inner wall of the cylinder body 15 is reduced, the oil outlet 34 and the oil filling port 512 are staggered with each other, so that the lubricating oil no longer flows into the interior of the oil outlet 34, thereby avoiding the waste of lubricating oil. At this time, a part of the lubricating oil will remain in the oil storage cavity 54, which can be used for subsequent lubrication. In addition, the oil storage cavity 54 is also used to leave space for the upward and downward offset of the sealing portion 31.

[0047] When the thickness of the sealing portion 31 decreases, the position of the oil outlet 34 will gradually move away from the joint 511, resulting in a gap between the joint 511 and the sealing portion 31, thereby causing the lubricating oil to leak through the gap. Therefore, the elastic member 513 is arranged at an angle, with the end close to the joint 511 pointing to the oil outlet 34, so that the elastic member 513 also has a force to push the joint 511 close to the oil outlet 34, which can push the joint 511 to fit with the sealing portion 31, avoiding the problem of lubricating oil leakage. In order to allow the joint 511 to be close to the sealing portion 31, the material of the positioning ring 51 is flexible plastic, so that the elastic member 513 can overcome the elasticity of the positioning ring 51 and push the joint 511 close to the oil outlet 34.

[0048] A flexible tube 6 is provided above the shaft body 41. The flexible tube 6 is connected to the interior of the oil storage chamber 414 and extends to the outside of the shell 16. Lubricating oil can be injected into the interior of the oil storage chamber 414 through the flexible tube 6, and then the flexible tube 6 is sealed by a sealing plug to prevent impurities from entering the interior of the flexible tube 6. A pressure relief hole 7 is also provided on the shaft body 41. The pressure relief hole 7 is connected to the interior of the oil storage chamber 414 and is used to balance the air pressure in the oil storage chamber 414 and the external air pressure, so that the lubricating oil can flow smoothly into the oil outlet 34.

Claims

1. A variable displacement mechanical pump comprising: A pump body (1) and a drive unit (2) arranged on the pump body (1), wherein the pump body (1) has a cylinder (15), and is characterized in that it further comprises: The capsule (3) includes two fixing portions (32) and a sealing portion (31) located between the two fixing portions (32). The sealing portion (31) is in contact with the inner wall of the cylinder (15) and is capable of sliding up and down inside the cylinder (15). The two fixing portions (32) are symmetrically arranged and extend from the edge of the sealing portion (31) to the middle. A shaft (41) is mounted on the output end of the drive unit (2) and passes through the two fixing portions (32) of the capsule (3); Two symmetrically arranged clamping parts (42), the clamping parts (42) being mounted on the shaft body (41), the two clamping parts (42) being used to respectively fix the two fixing parts (32) on the capsular sheet (3), and when the two clamping parts (42) are brought close to each other, the cavity in the capsular sheet (3) can be squeezed; A limit block (411) is provided at the bottom end of the shaft body (41) to limit the downward movement of the clamping portion (42) located below. An external thread (412) is provided on the shaft body (41) near the clamping portion (42) located above. A nut (43) is threadedly connected to the external thread (412) and abuts against the clamping portion (42) located above. A torsion spring (44) is provided on the shaft body (41) to apply a rotational torsion force to the nut (43). When the nut (43) is driven to rotate, the nut (43) can push the clamping portion (42) located above to approach the clamping portion (42) located below. A positioning ring (51) is provided in the capsule (3), a plurality of joints (511) are provided on the positioning ring (51), an oil filling port (512) is provided on the joint (511), an elastic member (513) is provided on the joint (511) so that the joint (511) is located in the middle of the two clamping parts (42), an oil outlet (34) is opposite to the joint (511) on the capsule (3), in a natural state, the oil filling port (512) and the oil outlet (34) are staggered, when the elastic member (513) is compressed, the oil filling port (512) and the oil outlet (34) overlap with each other, an oil storage chamber (414) is provided in the middle of the shaft (41), and an oil delivery pipe (52) is provided on the joint (511) to connect the oil storage chamber (414) and the oil filling port (512); A concave edge (53) is provided at the edge of the clamping portion (42), and an oil storage cavity (54) is formed between the concave edge (53) and the inner side wall of the cylinder body (15).

2. A variable displacement mechanical pump according to claim 1, characterized in that: The clamping portion (42) includes a fixing plate (421) and a clamping plate (422), wherein the fixing plate (421) is located inside the capsule (3), and a screw (423) is provided on the fixing plate (421) and extends to the outside of the capsule (3). The clamping plate (422) can slide along the axis of the screw (423), so that the fixing portion (32) is located between the clamping plate (422) and the fixing plate (421), and the clamping plate (422) and the fixing plate (421) are clamped and fixed to the fixing portion (32) of the capsule (3) by bolts.

3. A variable displacement mechanical pump according to claim 2, characterized in that: The capsule (3) is made of rubber, and the thickness of the sealing portion (31) is greater than the thickness of the fixing portion (32).

4. A variable displacement mechanical pump according to claim 1, characterized in that: The elastic member (513) is arranged at an angle so that the joint (511) is located in the middle of the two clamping portions (42) and simultaneously pushes the joint (511) toward the oil outlet (34).

5. A variable displacement mechanical pump according to claim 2, characterized in that: The shaft (41) is provided with a limiting groove (413) arranged along the length direction of the shaft (41), and the screw (423) located above is provided with a slider (47) sliding on the limiting groove (413) for limiting the rotation between the shaft (41) and the screw (423) located above.

6. A variable displacement mechanical pump according to claim 5, characterized in that: The shaft (41) passes through the two screw rods (423), and a sealing ring (46) is provided between the shaft (41) and the screw rods (423). The sealing ring (46) is located below the limiting groove (413). When the screw rods (423) slide on the shaft (41), the positions of the sealing ring (46) and the limiting groove (413) are staggered.

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