A pump head pump body structure of a liquid chromatography infusion pump with pump head pulsation damping

Abstract

The application provides a pump head pump body structure of a liquid chromatography infusion pump with pump head pulsation damping, and belongs to the technical field of liquid chromatography infusion pumps. In the pump head pump body structure, the pump head is a series structure pump head, the pump head cavity with a one-way valve is a main pump cavity, and the pump cavity without a one-way valve is a vice pump cavity. The rear end of the plunger in the vice pump cavity is in contact with an elastic column. Since the pulsation of the liquid chromatography infusion pump is the change of pressure, when the pulsation occurs, the plunger in the vice pump cavity is subjected to the pressure change in the pump cavity, the elastic column is compressed or released, the push rod has additional movement, the pressure change in the vice pump cavity is reduced, and thus the pulsation is reduced. The pulsation damping structure has no additional cavity, reduces the delay volume, has no flow circulation dead angle, improves the mixing and solvent replacement effect, has a simple structure, has no additional high-pressure sealing structure, improves reliability, does not need to additionally consider the chemical resistance of the material, can freely select the elastic material according to the pressure range of the infusion pump, and is low in cost.

Description

Technical Field

[0001] This invention relates to the field of liquid chromatography infusion pump technology, and more particularly to a pump head and pump body structure of a liquid chromatography infusion pump with pump head pulsation damping. Background Technology

[0002] The function of a liquid chromatography (LC) infusion pump is to deliver liquid at a constant flow rate. High-pressure liquid chromatography (HPLC) infusion pumps often employ a dual-pump-head tandem plunger structure. The main pump head in the tandem pump is equipped with check valves at the inlet and outlet for active liquid aspiration, while the auxiliary pump head passively aspirates and delivers liquid. The main and auxiliary pump heads alternate in aspiration and delivery, coordinating their work to achieve stable infusion. However, the operating characteristics of reciprocating plunger pumps inevitably result in significant infusion pulsations.

[0003] Typically, damping chambers or valves are installed in the infusion pump pipeline, such as elastic material pipeline damping devices, diaphragm chamber dampers, and compressible fluid dampers. When the liquid flows through the damping device, the elastic object compresses and deforms when the liquid pressure increases, and when the liquid pressure decreases, the elastic object recovers its deformation, increasing the liquid pressure. In this way, the pressure of the infusion pump system is stabilized through the accumulation and release of elastic potential energy.

[0004] In Chinese patent application CN110425102A, the applicant disclosed an adjustable infusion pump pulsation damper. This pulsation damper includes a top cover, an elastic diaphragm, a body, and an adjustment device. The top cover and body are cylindrical and coaxially fixedly connected. Two flow paths are axially arranged on the end face of the top cover away from the body, located on the same circumference. A first inner cavity is formed at the center of the end face of the body near the top cover. The first inner cavity is cylindrical, and its diameter is larger than the outer diameter of a circular groove. A distance is provided between the center of the end face of the body away from the top cover and the first inner cavity. The device includes a second cylindrical inner cavity that coincides with the axis of the first inner cavity, with a diameter smaller than that of the first inner cavity. An upper positioning pad is located in the first inner cavity, and a lower positioning pad is located in the second inner cavity. An elastic element is fixedly disposed between the upper and lower positioning pads. The upper positioning pad is spherical, with its circular end face fixedly connected to the elastic element. The diameter of the circular surface of the upper positioning pad is equal to the diameter of the first inner cavity. A circular elastic diaphragm, with a diameter larger than that of the first inner cavity, is fixedly positioned at the center between the opposing end faces of the upper cover and the main body. An adjustment device is in contact with the lower positioning pad and is used to adjust the deformation of the elastic element. This pulsation damper is an independent cavity structure, large in size, prone to dead zones, requiring a high-pressure sealing structure design, and susceptible to leakage.

[0005] In Chinese patent application CN111336078A, the applicant disclosed a dual-plunger liquid chromatography infusion pump. The pump head consists of a main pump head and a secondary pump head connected in series. The lower end of the main pump head body is provided with a fluid inlet and an inlet check valve, while the upper end is provided with a fluid outlet and an outlet check valve. The rear end of the pump head body is connected to a positioning plate by screws. A cylindrical inlet groove is provided inside the pump head body. The cylindrical inlet groove has openings on its upper and lower inner surfaces near the bottom, which are respectively connected to the fluid outlet and the fluid inlet. A plunger rod is slidably installed in the cylindrical inlet groove of the pump head body. The rear end of the plunger rod is inserted into and fixed in a plunger rod sleeve, and the front end of the plunger rod is inserted into and passes through the plunger rod positioning sleeve. A groove is provided at the rear end of the pump head body, and a plunger rod positioning sleeve is embedded therein. A primary sealing ring is provided between the front end face of the plunger rod positioning sleeve and the pump head body, and a secondary sealing assembly is provided at the rear end face. The plunger rod, the primary sealing ring, and the secondary sealing assembly form a... The pump head features a double-sealed floating plunger structure. A plunger spring is fitted onto the plunger rod, positioned between the plunger rod sleeve and the secondary sealing assembly. The plunger rod sleeve is embedded in a guide sleeve, one end of which is installed between the pump head body and the positioning plate, while the other end has a through hole through which the plunger rod sleeve protrudes. The auxiliary pump head has a fluid inlet and outlet at its upper and lower ends, respectively, neither of which is equipped with a check valve; the remaining structure is identical to the main pump head. The main and auxiliary pump heads are placed side-by-side and fixedly connected. The fluid outlet of the main pump head is connected to the fluid inlet of the auxiliary pump head. The push rod assembly consists of two independent movable optical shafts. The top ends of the plunger rod sleeves of the main and auxiliary pump heads respectively contact one end of the two optical shafts of the push rod assembly, while the other end of the push rod assembly is in close contact with a cam. The push rod assembly is supported by two sets of self-lubricating linear bearings, and the cam is supported by two sets of bearings. The cam is connected to a camshaft pulley, which is connected to a motor shaft pulley via a rubber synchronous belt. The motor shaft pulley is driven by a stepper motor. This scheme uses a rigid reciprocating plunger to achieve constant flow pumping of high-pressure liquid, but an additional pulsation damper is still needed to suppress flow pulsation.

[0006] The existing technology has at least the following shortcomings:

[0007] 1. Pulsation damping devices with independent cavity or valve bodies are larger in size, increasing the infusion delay volume and making the gradient response time of the liquid chromatography system longer.

[0008] 2. Pulsating damping devices with independent cavity or valve bodies are prone to creating dead zones in the flow, affecting the gradient mixing of the mobile phase and the solvent replacement effect.

[0009] 3. Pulsation damping devices that use independent cavity or valve bodies require additional high-pressure sealing structure design and high-pressure connection design, which can easily lead to leakage failure points.

[0010] 4. Pulsation damping devices that use independent cavity or valve bodies require chemically resistant materials, often making it impossible to use the best materials suitable for the pump pressure range, and are expensive.

[0011] 5. The infusion pump described above, which uses a cam to drive the push rod assembly to move, and then the push rod assembly to drive the plunger rod, can pump high-pressure fluids, but fluid pulsation cannot be avoided or reduced. Therefore, an additional pulsation damper is needed to reduce flow pulsation. Summary of the Invention

[0012] To address the problems existing in the prior art, this invention provides a pump head and pump body structure for a liquid chromatography infusion pump with pump head pulsation damping. The structure includes a pump head assembly and a pump body assembly. The pump head is a series-connected structure, with a main pump chamber equipped with a one-way valve and a secondary pump chamber without a one-way valve. The rear end of the plunger in the secondary pump chamber contacts an elastic column. Since the pulsation of the liquid chromatography infusion pump is a pressure change, when pulsation occurs, the plunger in the secondary pump chamber is subjected to the pressure change within the pump chamber, compressing or releasing the elastic column, causing the push rod to move additionally, reducing the pressure change within the secondary pump chamber, thereby reducing pulsation. This pulsation damping structure has no additional chamber, reducing the delay volume; no dead zones, improving mixing and solvent displacement effects; a simple structure, no additional high-pressure sealing structure, improving reliability; no need to consider the chemical resistance of materials, the elastic material can be freely selected according to the pressure range of the infusion pump, and the cost is low.

[0013] This invention provides a pump head and pump body structure for a liquid chromatography infusion pump with pump head pulsation damping, comprising:

[0014] The infusion pump is a reciprocating plunger pump; the pump head and pump body structure of the infusion pump includes a pump head assembly and a pump body assembly.

[0015] The pump head assembly includes: a pump head body, an outlet check valve, two positioning sleeves, two springs, two spring positioning sleeves, two plungers, two guide sleeves, and an inlet check valve;

[0016] The pump head body includes two pump chambers, namely a main pump chamber and a secondary pump chamber. The upper and lower ends of the main pump chamber are respectively equipped with an outlet check valve and an inlet check valve. The secondary pump chamber is connected to the liquid chromatography system to deliver liquid to the liquid chromatography system.

[0017] The spring is connected to the plunger via a spring positioning sleeve;

[0018] The pump body assembly includes: a front pump body, an elastic column, a positioning column, a damping push rod, a push rod bearing, a motor, a synchronous belt, and a cam;

[0019] The elastic column is installed at the foremost end of the damping push rod and is supported by the positioning column;

[0020] One end of the plunger passes through the spring positioning sleeve and the positioning sleeve and extends into the auxiliary pump chamber. The rear end of the plunger in the auxiliary pump chamber contacts the elastic column. The other plunger in the main pump chamber contacts the push rod.

[0021] When the motor moves, the rotation of the cam is controlled by a synchronous belt. The cam is connected to a push rod bearing, which is connected to a damping push rod.

[0022] The damping push rod is connected to the front pump body.

[0023] Preferably, the pump head assembly further includes: a pump head connecting pipe, an outlet pressure cap, a sealing ring seat, a pressure plate, a secondary sealing ring, a primary sealing ring, an inlet pressure cap, and a pump head lower connecting pipe.

[0024] Preferably, the guide sleeve is fitted over the plunger, the plunger extends from the hole at the tail of the guide sleeve, and the other end of the guide sleeve is fixed to the positioning sleeve by a pressure plate; the pressure plate is fixed to the pump head body by screws, thus fixing the pump head assembly together.

[0025] Preferably, the outlet check valve and the inlet check valve are fixed to the pump head body by outlet pressure cap and inlet pressure cap, respectively; the primary sealing ring is pressed onto the pump head body by one end of the positioning sleeve, and the secondary sealing ring is fixed to the other end of the positioning sleeve by the sealing ring seat; one end of the spring is fixedly installed on the sealing ring seat, and the other end of the spring is press-fitted with a spring positioning sleeve, and the elastic positioning sleeve is snapped onto the plunger.

[0026] Preferably, the pump body assembly further includes: a push rod, a long support plate, a short support plate, a base plate, a push rod guide sleeve, and a push rod shaft.

[0027] Preferably, another plunger in the main pump chamber passes through the guide sleeve and contacts the push rod, which is connected to the front pump body; the push rod is connected to the push rod bearing, which is fixed by the push rod shaft, and the other end of the push rod shaft is equipped with a push rod guide sleeve; the front pump body is fixed to the long support plate and the short support plate by screws; the base plate is fixed to the long support plate and the short support plate by screws.

[0028] Preferably, the pump body assembly further includes a camshaft pulley and a motor shaft pulley.

[0029] Preferably, a motor is mounted on the long support plate, a motor shaft pulley is mounted on the motor shaft, a camshaft pulley is mounted on the same side of the cam and the motor shaft pulley, and the motor shaft pulley and the camshaft pulley are connected by a synchronous belt.

[0030] Preferably, the pump body assembly further includes: a self-lubricating bearing, a felt, a lubricating oil box, and a cam bearing. The self-lubricating bearing is press-fitted into the front pump body. Cam bearings are press-fitted into both ends of the cam. The cam bearings are respectively press-fitted into the corresponding bearing mounting holes in the long support plate and the short support plate. A lubricating oil box is installed on the base plate. A felt is placed in the lubricating oil box, and the felt is in contact with the cam.

[0031] Preferably, the plunger is made of a rigid material; the positioning pin is made of a rigid material.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The pump head pulsation damping elastic column of the present invention does not come into contact with the liquid, does not increase the volume of the liquid pipeline, and has no pulsation damping delay volume.

[0034] (2) The elastic column of the present invention deforms at the secondary plunger as the pump head pressure changes, thereby reducing the gradient mixing delay volume;

[0035] (3) In this invention, the elastic column at the front end of the push rod assembly is directly connected to the rear end of the auxiliary plunger. The flow path of the auxiliary plunger is always connected to the liquid outlet of the infusion pump, with no dead corners in the flow, thus improving the mixing and solvent replacement effect.

[0036] (4) The present invention consists of only a push rod assembly in the pulsating damping structure. The push rod is driven by a drive cam, which is simple in structure and has no additional high-pressure sealing structure, thus improving reliability.

[0037] (5) In this invention, the elastic column does not come into contact with the liquid inside the infusion pump, so there is no need to consider the chemical resistance of the material. The elastic material can be freely selected according to the pressure range of the pump and the cost is low. Attached Figure Description

[0038] Figure 1 This is a perspective view of the pump head and pump body according to an embodiment of the present invention;

[0039] Figure 2 This is a split view of the pump head and pump body according to an embodiment of the present invention;

[0040] Figure 3 This is a front view of a pump head according to an embodiment of the present invention;

[0041] Figure 4 This is a top view of a pump head according to an embodiment of the present invention;

[0042] Figure 5 This is an exploded view of a pump head according to an embodiment of the present invention;

[0043] Figure 6 This is a left view of the pump body according to an embodiment of the present invention;

[0044] Figure 7 This is a right view of the pump body according to an embodiment of the present invention;

[0045] Figure 8 This is a top view of the pump body according to an embodiment of the present invention;

[0046] Figure 9 This is an exploded view of the pump body according to an embodiment of the present invention;

[0047] Figure 10 This is a top cross-sectional view of the pump head and pump body structure according to an embodiment of the present invention;

[0048] Figure 11 This is a schematic diagram of a liquid flow path according to an embodiment of the present invention;

[0049] The components include: 1. Pump head assembly; 2. Pump body assembly; 3. Pump head body; 4. Pump head connecting pipe; 5. Outlet pressure cap; 6. Outlet check valve; 7. Positioning sleeve; 8. Sealing ring seat; 9. Spring positioning sleeve; 10. Guide sleeve; 11. Pressure plate; 12. Plunger; 13. Spring; 14. Secondary sealing ring; 15. Primary sealing ring; 16. Inlet pressure cap; 17. Pump head lower connecting pipe; 18. Inlet check valve; 19. Front pump body; 20. Self-lubricating bearing; 21. Elastic column; 22. Positioning column; 23. Damping push rod; 24. Camshaft pulley; 25. Synchronous belt; 26. Motor shaft pulley; 27. Long support plate; 28. Cam; 29. ​​Felt; 30. Lubricating oil box; 31. Cam bearing; 32. Motor; 33. Short support plate; 34. Base plate; 35. Push rod bearing; 36. Push rod guide sleeve; 37. Push rod shaft; 38. Push rod; 39. Main pump chamber; 40. Auxiliary pump chamber; 41. Liquid storage bottle; 42. Liquid chromatography system. Detailed Implementation

[0050] The following is in conjunction with the appendix Figure 1-11 The specific embodiments of the present invention will be described in detail below.

[0051] This invention provides a pump head and pump body structure for a liquid chromatography infusion pump with pump head pulsation damping, comprising:

[0052] The infusion pump is a reciprocating plunger pump; the pump head and pump body structure of the infusion pump includes a pump head assembly 1 and a pump body assembly 2;

[0053] The pump head assembly 1 includes: a pump head body 3, an outlet check valve 6, two positioning sleeves 7, two springs 13, two spring positioning sleeves 9, two plungers 12, two guide sleeves 10, and an inlet check valve 18.

[0054] The pump head body includes two pump chambers, namely a main pump chamber 39 and a secondary pump chamber 40. The main pump chamber 39 has an outlet check valve 6 and an inlet check valve 18 at its upper and lower ends, respectively. The secondary pump chamber 40 is connected to the liquid chromatography system 42 to deliver liquid to the liquid chromatography system 42. The liquid chromatography system is generally a high-pressure system that uses the liquid delivered by the pump as a carrier to perform component analysis on the liquid sample in the system.

[0055] The spring 13 is connected to the plunger 12 via the spring positioning sleeve 9;

[0056] The pump body assembly 2 includes: a front pump body 19, an elastic column 21, a positioning column 22, a damping push rod 23, a push rod bearing 35, a motor 32, a synchronous belt 25, and a cam 28;

[0057] The elastic column 21 is installed at the foremost end of the damping push rod 23 and is supported by the positioning column 22;

[0058] One end of the plunger 12 passes through the spring positioning sleeve 9 and the positioning sleeve 7 and extends into the auxiliary pump chamber 40. The rear end of the plunger 12 in the auxiliary pump chamber 40 is in contact with the elastic column 21. The other plunger 12 in the main pump chamber 39 is in contact with the push rod 38.

[0059] The pulsation damping is achieved through the coordinated action of four components within the auxiliary pump chamber 40: plunger 12, elastic column 21, positioning column 22, and damping push rod 23.

[0060] From the appendix Figure 11 It can be seen that the liquid chromatography system 42 is always connected to the auxiliary pump chamber 40 in the liquid circuit. The liquid chromatography system 42 is a relatively stable high-pressure system, meaning that the auxiliary pump chamber 40 is always under high pressure, assuming a pressure of approximately 10 MPa. If the pump flow rate is unstable, the pressure is assumed to be in the range of 9.5-10.5 MPa. With the addition of pulsation damping, this pressure fluctuation can be offset, maintaining the pressure at 10 MPa. The main pump chamber 39 has no pressure when drawing liquid from the reservoir, but is under high pressure when discharging liquid. The pressure range of the main pump chamber 39 is from atmospheric pressure to 10 MPa. It can be seen that the main pump head 39 itself has significant pressure fluctuations, but these fluctuations are normal and do not need to be eliminated. When the pressure in the main pump chamber 39 is less than 10 MPa, a one-way valve isolates the auxiliary pump chamber 40 from the liquid chromatography system. Pressure changes in the main pump chamber 39 will not affect the liquid chromatography system 42, so pulsation damping is not required.

[0061] When the motor 32 moves, it controls the rotation of the cam 28 through the synchronous belt 25. The cam 28 is connected to the push rod bearing 35, which is connected to the damping push rod 23.

[0062] The damping push rod 23 is connected to the front pump body 19.

[0063] In a preferred embodiment, the pump head assembly 1 further includes: a pump head connecting pipe 4, an outlet pressure cap 5, a sealing ring seat 8, a pressure plate 11, a secondary sealing ring 14, a primary sealing ring 15, an inlet pressure cap 16, and a pump head lower connecting pipe 17.

[0064] In a preferred embodiment, the guide sleeve 10 is fitted over the plunger 12, the plunger 12 extends out from the hole at the tail of the guide sleeve 10, and the other end of the guide sleeve 10 is fixed to the positioning sleeve 7 by the pressure plate 11; the pressure plate 11 is fixed to the pump head body 3 by screws, thus fixing the pump head assembly 1 together.

[0065] In a preferred embodiment, the outlet check valve 6 and the inlet check valve 18 are fixed to the pump head body 3 by the outlet pressure cap 5 and the inlet pressure cap 16, respectively; the primary sealing ring 15 is pressed onto the pump head body 3 by one end of the positioning sleeve 7, and the secondary sealing ring 14 is fixed to the other end of the positioning sleeve 7 by the sealing ring seat 8; one end of the spring 13 is fixedly installed on the sealing ring seat 8, and the other end of the spring 13 is press-fitted with a spring positioning sleeve 9, which is snapped onto the plunger 12.

[0066] In a preferred embodiment, the pump body assembly 2 further includes: a push rod 38, a long support plate 27, a short support plate 33, a base plate 34, a push rod guide sleeve 36, and a push rod shaft 37.

[0067] In this invention, of the two plungers, only the plunger 12 of the auxiliary pump chamber 40 contacts the elastic column 21, which is installed at the front end of the damping push rod 23. The other plunger 12 contacts the push rod 38. This design is because the liquid chromatography system 42 is a high-pressure system. The auxiliary pump chamber is always connected to the liquid chromatography system, and the pressure remains consistent. Suppressing the pressure pulsation in the auxiliary pump chamber can suppress the pressure pulsation in the liquid chromatography system. The main pump chamber, on the other hand, is connected to a normal-pressure storage bottle at one end and a high-pressure auxiliary pump chamber at the other end. During the liquid aspiration and discharging process, the pressure changes are huge. Moreover, there is a one-way valve between the main pump chamber 39 and the auxiliary pump chamber 40, so the pressure change in the main pump chamber 39 will not affect the pressure in the auxiliary pump chamber 40. Therefore, adding the elastic column 21 only after the push rod of the auxiliary pump chamber 40 can suppress the pressure change in the liquid chromatography system 42 and achieve a good pulsation damping effect.

[0068] In a preferred embodiment, another plunger 12 in the main pump chamber 39 passes through the guide sleeve 10 and contacts the push rod 38, which is connected to the front pump body 19. The push rod 38 is connected to the push rod bearing 35, which is fixed by the push rod shaft 37. The other end of the push rod shaft 37 is equipped with a push rod guide sleeve 36. The front pump body 19 is fixed to the long support plate 27 and the short support plate 33 by screws. The base plate 34 is fixed to the long support plate 27 and the short support plate 33 by screws.

[0069] In a preferred embodiment, the pump body assembly 2 further includes a camshaft pulley 24 and a motor shaft pulley 26.

[0070] In a preferred embodiment, a motor 32 is mounted on the long support plate 27, a motor shaft pulley 26 is mounted on the motor shaft, a cam shaft pulley 24 is mounted on the same side of the cam 28 and the motor shaft pulley 26, and the motor shaft pulley 26 and the cam shaft pulley 24 are connected by a synchronous belt 25.

[0071] In a preferred embodiment, the pump body assembly 2 further includes: a self-lubricating bearing 20, a felt 29, a lubricating oil box 30, and a cam bearing 31. The self-lubricating bearing 20 is press-fitted into the front pump body 19. Cam bearings 31 are press-fitted into both ends of the cam 28. The cam bearings 31 are respectively press-fitted into the corresponding bearing mounting holes in the long support plate 27 and the short support plate 33. A lubricating oil box 30 is installed on the base plate 34. A felt 29 is placed in the lubricating oil box 30. The felt 29 contacts the cam 28 to provide lubricating oil to the cam 28.

[0072] In a preferred embodiment, the plunger 12 is made of a rigid material; the positioning post 22 is made of a rigid material; when the elastic post 21 deforms to the front end position of the positioning post 22, the damping push rod 23 is in rigid contact with the positioning post 22 and no longer squeezes the elastic post 21, preventing the elastic post 21 from being squeezed beyond the elastic deformation range.

[0073] When the pressure in the liquid chromatography system 42 increases, the elastic column 21 is compressed, the plunger 12 in the auxiliary pump chamber 40 moves backward relative to the pump head body 3, and the volume inside the auxiliary pump chamber 40 increases, which is used to reduce the pressure in the liquid chromatography system 42.

[0074] When the pressure in the liquid chromatography system 42 decreases, the elastic column 21 is released, the plunger 12 in the auxiliary pump chamber 40 extends forward relative to the pump head body 3, and the volume inside the auxiliary pump chamber 40 decreases to replenish the pressure in the liquid chromatography system 42.

[0075] Example 1

[0076] According to a specific embodiment of the present invention, in conjunction with the appendix Figure 1-11 The present invention will be described in detail below.

[0077] This invention provides a pump head and pump body structure for a liquid chromatography infusion pump with pump head pulsation damping, wherein the infusion pump is a reciprocating plunger pump;

[0078] The infusion pump head and pump body structure includes the pump head assembly 1 and the pump body assembly 2;

[0079] The pump head assembly 1 includes: pump head body 3, pump head connecting pipe 4, outlet pressure cap 5, outlet check valve 6, positioning sleeve 7, sealing ring seat 8, spring positioning sleeve 9, guide sleeve 10, pressure plate 11, plunger 12, spring 13, secondary sealing ring 14, primary sealing ring 15, inlet pressure cap 16, pump head lower connecting pipe 17, and inlet check valve 18.

[0080] The positioning sleeve, sealing ring seat, spring positioning sleeve, guide sleeve, plunger, spring, secondary sealing ring, and primary sealing ring are all in pairs.

[0081] The pump head body 3 includes two pump chambers, namely the main pump chamber 39 and the auxiliary pump chamber 40. The difference between the two pump chambers is that the main pump chamber 39 has an outlet check valve 6 and an inlet check valve 18 at the top and bottom, respectively, while the auxiliary pump chamber 40 is directly connected to the liquid chromatography system 42.

[0082] The pulsation damping is achieved through the coordinated action of four components within the auxiliary pump chamber 40: plunger 12, elastic column 21, positioning column 22, and damping push rod 23.

[0083] The outlet check valve 7 and the inlet check valve 18 are respectively fixed to the pump head body 3 by the outlet pressure cap 5 and the inlet pressure cap 16.

[0084] The primary sealing ring 15 is pressed onto the pump head body 3 by the positioning sleeve 7, and the secondary sealing ring 14 is fixed to the other side of the positioning sleeve 7 by the sealing ring seat 8.

[0085] The spring 13 is mounted on the sealing ring seat 8, and the other end of the spring 13 is press-fitted with a spring positioning sleeve 9.

[0086] The plunger 12 passes through the spring positioning sleeve 9, the spring 13, the sealing ring seat 8, the secondary sealing ring 14, the primary sealing ring 15, and extends into the pump head body 3.

[0087] The guide sleeve 10 is fitted onto the plunger 12, the plunger 12 extends out from the hole at the tail of the guide sleeve 10, and the other end of the guide sleeve 10 is fixed to the positioning sleeve 7 by the pressure plate 11.

[0088] The pressure plate 11 is fixed to the pump head body 3 by screws, thus fixing the entire pump head assembly 1;

[0089] The pump body assembly 2 includes: a front pump body 19, a self-lubricating bearing 20, an elastic column 21, a positioning column 22, a damping push rod 23, a camshaft pulley 24, a synchronous belt 25, a motor shaft pulley 26, a long support plate 27, a cam 28, a felt 29, a lubricating oil box 30, a cam bearing 31, a motor 32, a short support plate 33, a base plate 34, a push rod bearing 35, a push rod guide sleeve 36, a push rod shaft 37, and a push rod 38;

[0090] The elastic column 21 is installed at the foremost end of the damping push rod 23 and is supported by the positioning column 22;

[0091] The rear end of one plunger 12 in the auxiliary pump chamber 40 contacts the elastic column 21, and the other plunger 12 in the main pump chamber 39 contacts the push rod 38; the other plunger 12 in the main pump chamber 39 passes through the guide sleeve 10 and contacts the push rod 38, and the push rod 38 is connected to the front pump body 19; the push rod 38 is connected to the push rod bearing 35, and the other end of the push rod shaft 37 is equipped with a push rod guide sleeve 36;

[0092] The self-lubricating bearing 20 is press-fitted into the front pump body 19;

[0093] The front pump body 19 is fixed to the long support plate 27 and the short support plate 33 by screws;

[0094] The base plate 34 is fixed to the long support plate 27 and the short support plate 33 by screws;

[0095] Cam bearings 31 are press-fitted at both ends of the cam 28, and the cam bearings 31 are respectively press-fitted into the corresponding bearing mounting holes in the long support plate 27 and the short support plate 33.

[0096] A lubricating oil box 30 is installed on the base plate 34. A felt 29 is placed in the lubricating oil box 30. The felt 29 contacts the cam 28 to provide it with lubricating oil.

[0097] A motor 32 is mounted on the long support plate 27, and a motor shaft pulley 26 is mounted on the motor shaft;

[0098] The cam 28 and the motor shaft pulley 26 are mounted on the same side of the cam shaft pulley 24, and the motor shaft pulley 26 and the cam shaft pulley 24 are connected by a synchronous belt 25.

[0099] Both the damping push rod 23 and the push rod 38 have push rod bearings 35 at their tail ends. The push rod bearings 35 are fixed by the push rod shaft 37, and the other end of the push rod shaft 37 is equipped with a push rod guide sleeve 36.

[0100] When the pressure in the liquid chromatography system 42 increases, the elastic column 21 is compressed, the plunger 12 in the auxiliary pump chamber 40 moves backward relative to the pump head body 3, and the volume inside the auxiliary pump 40 increases, which is used to reduce the pressure in the liquid chromatography system 42.

[0101] When the pressure of the liquid chromatography system decreases, the elastic column 21 is released, the plunger 12 in the auxiliary pump chamber 40 extends forward relative to the pump head body 3, and the volume inside the auxiliary pump 40 decreases to replenish the pressure in the liquid chromatography system 42.

[0102] The positioning post 22 is made of rigid material. When the elastic post 21 deforms to the front end position of the positioning post 22, the damping push rod 23 makes rigid contact with the positioning post 22 and no longer squeezes the elastic post 51, preventing the elastic post 51 from being squeezed beyond the elastic deformation range.

[0103] Working principle:

[0104] When the motor 32 moves, it drives the cam 28 to rotate via the synchronous belt 25. The cam 28 then pushes the push rod 38 and the damping push rod 23 to move.

[0105] Push rod 38 and damping push rod 23 respectively transmit the thrust to the two plungers 12 in the main pump chamber 39 and the auxiliary pump chamber 40. The plungers 12 reciprocate under the combined action of the thrust of push rod 38 and the elastic force of spring 13.

[0106] The main pump chamber 39 has an outlet check valve 6 and an inlet check valve 18 at the top and bottom, respectively. The reciprocating motion of the plunger 12 can draw liquid from the storage bottle 41 into the main pump chamber and discharge it. Part of the liquid discharged from the main pump chamber 39 directly enters the liquid chromatography system 42, and part of it is drawn into the auxiliary pump chamber 40. When the main pump chamber 39 draws liquid, the auxiliary pump chamber 40 discharges the liquid to prevent flow interruption.

[0107] The auxiliary pump chamber 40 is always connected to the liquid chromatography system 42 and maintains a consistent pressure. During pump operation, the plunger 12 in the auxiliary pump chamber 40 is in contact with the elastic column 21. When the system pressure changes, the elastic column 21 deforms, thereby altering the position of the plunger 12 within the auxiliary pump chamber 40, adjusting the volume of the auxiliary pump chamber 40, suppressing system pressure changes, and achieving a pulsation damping effect.

[0108] The elastic column 21 is fitted onto the positioning column 22. The positioning column 22 is made of rigid material, which can ensure that when the pressure increases abnormally and exceeds the limit value, when the elastic column 21 deforms to the front end position of the positioning column 22, the push rod 13 is in rigid contact with the positioning column 22 and no longer squeezes the elastic column 21, preventing the elastic column 21 from being squeezed beyond the elastic range and causing irreversible deformation.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A pump head and pump body structure for a liquid chromatography infusion pump with pump head pulsation damping, characterized in that: The infusion pump is a reciprocating plunger pump; the pump head and pump body structure of the infusion pump includes a pump head assembly and a pump body assembly. The pump head assembly includes: a pump head body, an outlet check valve, two positioning sleeves, two springs, two spring positioning sleeves, two plungers, two guide sleeves, and an inlet check valve; The pump head body includes two pump chambers, namely a main pump chamber and a secondary pump chamber. The main pump chamber has an outlet check valve and an inlet check valve at its upper and lower ends, respectively. The secondary pump chamber does not have a check valve. The secondary pump chamber is connected to the liquid chromatography system and delivers the liquid to the liquid chromatography system. The spring is connected to the plunger via a spring positioning sleeve; The pump body assembly includes: a front pump body, an elastic column, a positioning column, a damping push rod, a push rod bearing, a motor, a synchronous belt, and a cam; The elastic column is installed at the foremost end of the damping push rod and is supported by the positioning column; One end of the plunger passes through the spring positioning sleeve and the positioning sleeve and extends into the auxiliary pump chamber. The rear end of one plunger in the auxiliary pump chamber contacts the elastic column, and the other plunger in the main pump chamber contacts the push rod. The motor is connected to a synchronous belt, which is connected to a cam. When the motor is working, the rotation of the cam is controlled by the synchronous belt. The cam is connected to a push rod bearing, which is connected to a damping push rod. The damping push rod is connected to the front pump body; pulsation damping is achieved through the coordinated operation of four components in the auxiliary pump chamber: plunger, elastic column, positioning column, and damping push rod.

2. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 1, characterized in that, The pump head assembly also includes: a pump head connecting pipe, an outlet pressure cap, a sealing ring seat, a pressure plate, a secondary sealing ring, a primary sealing ring, an inlet pressure cap, and a pump head lower connecting pipe.

3. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 2, characterized in that, The guide sleeve is fitted over the plunger, which extends from the hole at the tail of the guide sleeve. The other end of the guide sleeve is fixed to the positioning sleeve by a pressure plate. The pressure plate is fixed to the pump head body by screws, thus fixing the pump head assembly together.

4. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 2, characterized in that, The outlet check valve and the inlet check valve are respectively fixed to the pump head body by the outlet cap and the inlet cap; the primary sealing ring is pressed onto the pump head body by one end of the positioning sleeve, and the secondary sealing ring is fixed to the other end of the positioning sleeve by the sealing ring seat; one end of the spring is fixedly installed on the sealing ring seat, and the other end of the spring is press-fitted with a spring positioning sleeve, which is then clamped onto the plunger.

5. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 1, characterized in that, The pump body assembly also includes: a push rod, a long support plate, a short support plate, a base plate, a push rod guide sleeve, and a push rod shaft.

6. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 5, characterized in that, Another plunger in the main pump chamber passes through the guide sleeve and contacts the push rod, which is connected to the front pump body; the push rod is connected to the push rod bearing, which is fixed by the push rod shaft, and the other end of the push rod shaft is equipped with a push rod guide sleeve; the front pump body is fixed to the long support plate and the short support plate by screws; the base plate is fixed to the long support plate and the short support plate by screws.

7. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 5, characterized in that, The pump assembly also includes a camshaft pulley and a motor shaft pulley.

8. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 7, characterized in that, A motor is mounted on the long support plate, and a motor shaft pulley is mounted on the motor shaft. A cam shaft pulley is mounted on the same side of the cam and the motor shaft pulley. The motor shaft pulley and the cam shaft pulley are connected by a synchronous belt.

9. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 7, characterized in that, The pump body assembly also includes: a self-lubricating bearing, a felt, a lubricating oil box, and a cam bearing. The self-lubricating bearing is press-fitted into the front pump body. Cam bearings are press-fitted into both ends of the cam. The cam bearings are press-fitted into the corresponding bearing mounting holes in the long support plate and the short support plate, respectively. A lubricating oil box is installed on the base plate. A felt is placed in the lubricating oil box, and the felt is in contact with the cam.

10. The pump head and pump body structure of the liquid chromatography infusion pump with pump head pulsation damping according to claim 1, characterized in that, The plunger is made of a rigid material; the positioning pin is made of a rigid material.

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