Plunger pump capable of preventing fluid from hanging drops and drawing wires

Abstract

The utility model discloses a fluid hanging drop and wire drawing prevention plunger pump which comprises a plunger pump body and a first driving mechanism, the plunger pump body comprises a plunger and a pump body, one end of the plunger is arranged in a plunger cavity of the pump body, the pump body is further provided with a liquid suction hole and a liquid drainage hole, and the plunger pump further comprises a control mechanism. The control mechanism comprises a valve element installed on the pump body and a second driving mechanism, and a second communicating hole is formed in the valve element. The valve element can move in the mode that in the first state, an orifice in the other end of the second communicating hole is communicated with the liquid suction hole; in the second state, an orifice in the other end of the second communicating hole is communicated with the liquid discharging hole; the first driving mechanism is a servo motor or a stepping motor. Due to the structural arrangement of the plunger pump, the plunger pump has a back suction function, and when the plunger pump is applied to viscous fluid, fluid conveying precision can be effectively controlled by reducing or avoiding fluid dripping and wire drawing, and unnecessary fluid waste is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of fluid conveying equipment, in particular to a plunger pump capable of preventing fluid from dripping and drawing. Background Art

[0002] In the food industry, medical industry, chemical industry, pharmaceutical industry, daily necessities industry, etc., plunger pumps are used for precise fluid delivery functions for the purpose of filling and adding materials, and are particularly suitable for quantitative delivery of viscous liquids.

[0003] Taking the use of a plunger pump to achieve the purpose of filling as an example, a filling machine is provided in the patent application document with patent application number CN201611206459.2, whose structural components include a plunger pump, a first cylinder, a first switch device and a second switch device, etc. When working, the first cylinder drives the plunger in the piston pump to move in the plunger pump body, and controls the connection state of the plunger cavity in the plunger pump with the first liquid holding device and the second liquid holding device respectively through the first switch device and the second switch device. The above switch devices include baffles, springs and support plates. The specific working process of the filling machine is: the cylinder can control the piston to move in the plunger pump body, thereby changing the piston pump cylinder body. Air pressure, when the piston is away from the first liquid holding device, the air pressure in the plunger pump body is low, the first switch device is opened, and the liquid in the first liquid holding device is sucked into the plunger pump body. When the piston located in the plunger pump body moves close to the first liquid holding device, the air pressure in the plunger pump cylinder becomes high, and the liquid in the cylinder is pressed into the second liquid holding device through the connecting pipe. The second switch device is opened, and the liquid can be input from the liquid outlet into the bottle to be filled. The specific working process of the switch device is: the liquid pressure acts on the baffle and pushes the baffle to move to open the connecting hole. During this process, the spring supported on the support plate is compressed; when the liquid pressure becomes smaller, the spring rebounds to push the baffle to move in the opposite direction and block the connecting hole.

[0004] Plunger pumps play an important role in the precise delivery of liquids in various industries. It is necessary to further optimize the plunger pumps so that they can better serve various industries. Utility Model Content

[0005] In response to the above-mentioned technical problem of optimizing the plunger pump, the utility model provides a plunger pump that prevents fluid dripping and stringing. The structural setting of the plunger pump enables it to have a back-suction function. When used for viscous fluids, it can effectively control the fluid delivery accuracy and reduce unnecessary fluid waste by reducing or avoiding fluid dripping and stringing.

[0006] In view of the above problems, the utility model provides a plunger pump that prevents fluid dripping and wire drawing to solve the problems through the following technical points: a plunger pump that prevents fluid dripping and wire drawing, comprising a plunger pump body, a first driving mechanism for driving the plunger pump body to move, the plunger pump body comprising a plunger and a pump body, one end of the plunger is arranged in the plunger cavity of the pump body, the first driving mechanism is connected to the plunger, the pump body is also provided with a suction hole and a discharge hole, and also comprises a control mechanism, the control mechanism is used to control the conduction state between the plunger cavity and the suction hole, and between the plunger cavity and the discharge hole, the control mechanism comprises a valve core installed on the pump body and a second driving mechanism for driving the valve core to move, the valve core is provided with a second communicating hole, and the orifice at one end of the second communicating hole is communicated with the plunger cavity;

[0007] The valve core can move as follows:

[0008] In the first state, the opening at the other end of the second communication hole is connected to the liquid suction hole;

[0009] In the second state, the orifice at the other end of the second communication hole is connected to the drainage hole;

[0010] The first driving mechanism is a servo motor or a stepping motor.

[0011] As the technical solution provided by the patent application document with patent application number CN201611206459.2, in the prior art, the plunger pump mostly uses a cylinder to drive the plunger movement of the plunger pump, and controls the conduction state between the plunger cavity on the plunger pump and the suction hole and the discharge hole through a control mechanism with a spring and pressure control to open or close. When such a plunger pump is used for quantitative delivery of viscous fluid, after the plunger completes a specified number of reciprocating motions to achieve quantitative delivery, if there is a liquid with dripping or drawing at the end of the outlet pipe connected to the outlet pipe on the discharge hole, it is difficult to control the cylinder to drive the plunger movement with a smaller stroke to achieve the back suction of the dripping or drawing liquid. At the same time, the control mechanism with a spring and pressure control to open or close is mostly a one-way valve mechanism, which does not allow the fluid to flow in the opposite direction after the control mechanism is opened, so the pipe fittings on the fluid flow path do not allow the fluid to be reversely conducted to achieve the back suction of the dripping or drawing liquid when the plunger moves, which causes the problem of uncontrollable falling of the dripping or drawing fluid. When the dripping or wire-drawing fluid falls below the liquid outlet pipe into the fluid collection container used for quantitative fluid collection, the fluid collection container collects different amounts of fluid in the two collections compared to the fluid collection container into which the dripping or wire-drawing fluid does not fall. This situation is not conducive to controlling the accuracy of fluid delivery. When the dripping or wire-drawing fluid falls outside the fluid collection container, fluid waste will occur. In addition, when the plunger pump is used for quantitative delivery of viscous fluid, a feeding device is generally connected to the suction hole through a liquid inlet pipe. The feeding device is connected to the liquid inlet pipe by a liquid supply pipe, and the feeding device provides pressurized fluid to the suction hole. When the feeding device pressurizes the fluid too much, the control mechanism of the one-way valve mechanism will be opened unplanned. At this time, the suction hole and the discharge hole on the plunger pump are directly connected, and the plunger pump will discharge fluid unplanned.

[0012] In view of the above problems, a plunger pump as described above is provided, specifically, the first driving mechanism drives the plunger to reciprocate in the plunger cavity, so that the plunger pump body sucks and squeezes the fluid, specifically: when the valve core moves to connect the plunger cavity and the suction hole through the second connecting hole under the action of the second driving mechanism (in the first state), the plunger performs a suction action, so that the fluid is sucked into the plunger cavity, and the plunger cavity and the discharge hole are cut off by the valve core at this stage; when the valve core moves to connect the plunger cavity and the discharge hole through the second connecting hole under the action of the second driving mechanism (in the second state), the plunger performs an extrusion action, so that the fluid is squeezed from the plunger cavity into the discharge hole, and the plunger cavity and the suction hole are cut off by the valve core at this stage.

[0013] Therefore, when the above scheme is applied to the transportation of viscous fluids and there is fluid dripping and wire drawing at the end of the liquid outlet pipe, the first driving mechanism of the servo motor or the stepping motor can accurately adjust the number of rotations and the rotation angle, so that the plunger moves a smaller stroke after squeezing out the fluid to suck back the fluid dripping and wire drawing at the end of the liquid outlet pipe, and the movement amount of the plunger in the back-sucking action can be accurately adjusted according to the inner diameter of the liquid outlet pipe, the properties of the fluid, etc. At the same time, the structural form of the control mechanism makes the conduction and cutoff of the suction hole and the plunger cavity, and the conduction and cutoff of the plunger cavity and the discharge hole controlled by the second driving mechanism, and the conduction state of the suction hole and the plunger cavity, and the conduction state of the discharge hole and the plunger cavity can be controlled in any movement direction and position of the plunger, so as to provide a structural basis for sucking back the fluid through the plunger on the basis of the inherent flow path (there is no need to use a separate fluid to realize the function of sucking back the dripping and wire drawing fluid). For example, when sucking back the dripping and wire-drawing fluid, the plunger cavity and the suction hole are cut off and the plunger cavity and the discharge hole are connected, and the plunger retreats to suck the dripping and wire-drawing fluid into the liquid outlet pipe to reduce or avoid the dripping and wire-drawing fluid falling so as to ensure the accuracy of fluid delivery and reduce unnecessary fluid waste; in addition, since the maintenance of the above first state and the second state is controlled by the second driving mechanism, the pressure of the fluid in the suction hole and the discharge hole cannot or is not easy to cause unplanned changes in the connection state between the plunger cavity and the suction hole and the discharge hole. Therefore, when this scheme is used in the working condition where the fluid upstream of the suction hole needs to be pre-pressurized, the plunger pump can effectively avoid unplanned fluid output; at the same time, this scheme can also make the discharge hole and the suction hole switchable in function: the discharge hole can be switched to the suction hole that performs the suction function, and the suction hole can be switched to the discharge hole that performs the discharge function.

[0014] In the specific implementation, under the action of the control mechanism, the valve core is used to change the conduction between the plunger cavity and the suction hole and the discharge hole through the second connecting hole thereon, so the movement of the valve core can be movement or rotation. For example, when the valve core moves to different positions or rotates to different angles, the orifice at the other end of the second connecting hole has a different docking state with the suction hole and the discharge hole. Therefore, one of the control parameters of this scheme is the movement amount of the valve core. In order to better realize the control of the movement amount, the second driving mechanism can use a stepping motor, a servo motor, or a hydraulic cylinder or a pneumatic cylinder. For example, when a hydraulic cylinder or a cylinder is used, when the corresponding piston moves to the front and rear dead point positions, at one of the dead point positions, the suction hole and the plunger cavity are connected and the plunger cavity and the discharge hole are cut off, and at the other dead point position, the suction hole and the plunger cavity are cut off and the plunger cavity and the discharge hole are connected. In addition, the linear motion or rotation output by the second driving mechanism can be converted into driving the valve core to move or rotate through a motion state conversion mechanism. Since the relevant motion state conversion mechanism is a prior art, no further specific description is made in this scheme.

[0015] As a further technical solution of the plunger pump for preventing fluid dripping and wire drawing:

[0016] The pump body is also provided with an installation cavity, the valve core is installed in the installation cavity, the liquid suction hole and the liquid discharge hole are both connected with the installation cavity, and the liquid suction hole and the liquid discharge hole have different communication positions on the installation cavity that are connected with the installation cavity;

[0017] The second driving mechanism is used to drive the valve core to move or rotate in the installation cavity. Through the movement or rotation, the valve core is adjusted to switch between the first state and the second state. In this scheme, the outlet end of the suction hole and the inlet end of the discharge hole are both connected to the installation cavity, and the outlet end and the inlet end are distributed at different positions of the installation cavity. When the valve core moves or rotates in the installation cavity under the action of the second driving mechanism, the valve core at different positions or angles is adjusted to use the second connecting hole to realize the connection between the plunger cavity and the suction hole and cut off from the discharge hole, and to use the second connecting hole to realize the connection between the plunger cavity and the discharge hole and cut off from the suction hole.

[0018] It also includes a first communicating hole provided on the pump body and communicating the installation cavity with the plunger cavity, wherein an orifice at one end of the first communicating hole is located at the front end of the plunger cavity;

[0019] The second communicating hole is composed of an axial hole and a radial hole, the axial hole is connected to the radial hole, the orifice of the axial hole is located on the end surface of the valve core, the orifice of the radial hole is located on the side surface of the valve core, and the orifice of the axial hole is connected to the orifice of the other end of the first communicating hole;

[0020] The second driving mechanism is used to drive the valve core to rotate in the installation cavity, and by controlling the rotation angle of the valve core under the action of the second driving mechanism, the orifice of the radial hole is adjusted to be connected with the suction hole and the discharge hole. When the orifice of the radial hole is connected with the suction hole, the valve core is in the first state, and when the orifice of the radial hole is connected with the discharge hole, the valve core is in the second state. In the present solution, the first connecting hole is used to connect the installation cavity and the plunger cavity, so as to realize the connection between the front end of the plunger cavity and the second connecting hole and make the installation cavity a channel on the pump body away from the plunger cavity. The shape of the second connecting hole and the distribution position of the hole opening are a technical solution that is convenient for processing, simple in structure and easy to ensure processing accuracy; it is a technical solution that can always keep the axial hole opening connected with the first connecting hole during the rotation of the valve core, and realize the connection between the radial hole and the suction hole or the discharge hole at different rotation angles; it is a technical solution that, compared with the valve core realizing the switching between the first state and the second state by moving, the valve core is rotated to avoid the pressure change in the flow path causing the stability of the valve core to be affected or causing unnecessary force on the second drive mechanism.

[0021] It also includes a sleeve mounted on the pump body, wherein the valve core is mounted in the inner hole of the sleeve;

[0022] The sleeve is fixed in the mounting cavity on the pump body, and the second driving mechanism drives the valve core to move relative to the sleeve, so that the surface of the valve core contacts the hole wall of the inner hole;

[0023] A communication channel is provided on the side wall of the sleeve, and the communication channel includes a first channel for realizing the communication between the second communication hole and the suction hole and a second channel for realizing the communication between the second communication hole and the discharge hole. In the above scheme, since the valve core is a moving part on the pump body and directly contacts the fluid, in order to ensure the performance of the plunger pump, it is necessary to consider the wear problem of the valve core and the fluid leakage problem at the position of the valve core. It is set to also include the sleeve and install the valve core in the inner hole of the sleeve. Compared with directly installing the valve core on the pump body, the sleeve can be manufactured separately as a part on the pump body. For example, the pump body is made of stainless steel material to provide good pressure bearing capacity, and the sleeve is made of composite materials, polymer materials or metal materials with good wear resistance and easy processing of the inner hole wall into a smooth wall. In this way, in the process of relative movement between the valve core and the sleeve, the good wear resistance of the sleeve and the good matching accuracy of the valve core and the sleeve can effectively ensure the performance and life of the plunger pump. In the specific implementation, the better application is that the pump body is made of stainless steel material, the plunger and the valve core are made of ceramic material, and the sleeve is made of polymer material resistant to organic solvents.

[0024] The second driving mechanism is used to drive the valve core to rotate;

[0025] The inner hole has a tapered hole section, and the valve core has a tapered section that fits the tapered hole section;

[0026] Of the two openings of the second connecting hole, one opening is located on the side of the tapered section, and the other opening is located on the end face of the valve core, and the opening on the side is located between the end face and the end with a smaller diameter of the tapered section. This scheme is a technical scheme in which the valve core changes the conduction state between the plunger cavity and the suction hole and the discharge hole by rotating, and specifically is a technical scheme in which the tapered hole section and the tapered section are arranged so that after the valve core and / or the inner wall of the sleeve have a wear less than the maximum wear amount (the maximum wear amount is that the tapered hole section cannot provide axial support for the tapered section), during the fluid extrusion process of the plunger pump, the pressure exerted on the valve core by the fluid can make the valve core move toward the end with a smaller diameter of the tapered hole section, and the axial sealing of the valve core and the inner hole matching surface is achieved with the assistance of the pressure. In a specific implementation, the conical section is the section with the largest diameter on the valve core, and the valve core and the second driving mechanism for the driving motor are driven through a gear set. After removing the constraint of the sleeve on the valve core, the valve core can move toward the end with a smaller diameter of the conical section to achieve the purpose of the movement.

[0027] In specific application, when it is not necessary to pressurize the fluid upstream of the suction hole or the pressurized pressure is low, it is easy to maintain the axial sealing of the gap between the sleeve and the valve core during fluid suction and extrusion through the matching state of the sleeve and the valve core, and prevent the fluid in the suction hole from directly entering the discharge hole from the gap. However, when it is necessary to pressurize the fluid upstream of the suction hole to a higher pressure, such as during the plunger suction process, the fluid may still enter the discharge hole from the suction hole through the gap. In order to solve this problem, a certain positive pressure can always be maintained between the tapered hole section and the tapered section to prevent the fluid in the suction hole from directly entering the discharge hole from the gap or axial leakage through the gap. A pre-tightening structure is also included, which acts on the valve core and is used to apply a force relative to the sleeve to the valve core, and the direction of the force is: toward the side with a smaller diameter of the tapered section. In this solution, the pre-tightening structure is used to provide the valve core with a continuous force toward the small end of the tapered hole section, and the force is used to maintain the positive pressure between the tapered hole section and the tapered section, thereby avoiding the axial leakage and the problem that the fluid in the suction hole directly enters the discharge hole from the gap. A preferred application is that the tapered hole section and the tapered section have the same size.

[0028] The pre-tightening structure includes a retaining ring fixed on the valve core, and the pre-tightening structure also includes an elastic member clamped between the inner end of the retaining ring and the outer end of the sleeve and in a compressed and deformed state. This scheme is a specific implementation method of the pre-tightening structure, specifically: the compressed elastic member provides thrust for the retaining ring, and after the thrust is transmitted to the valve core through the retaining ring, the valve core obtains a force to move toward the small end of the tapered hole section. In this scheme, the elastic member can be a metal elastic pad. Other applications also include setting an elastic member between one end of the valve core that penetrates into the pump body and the pump body, but this method needs to consider the influence of the fluid on the elastic member, which is not conducive to the selection of the elastic member and the ability to maintain performance.

[0029] The first driving mechanism includes a rotor, and the rotor is connected to the plunger through a transmission mechanism;

[0030] The transmission mechanism includes a nut and an anti-rotation restraint member;

[0031] The rotor is threadedly connected to a nut via an external thread thereon, and the nut is connected to a plunger;

[0032] The anti-rotation restraint is used to prevent the nut from rotating. In this solution, the rotor with external threads is a screw, and the nut is threadedly connected to the screw. In this way, when the rotor rotates, the nut cannot rotate because it is blocked by the anti-rotation restraint. Therefore, according to the rotation direction of the rotor, the nut produces a linear motion in a specific direction on the axis of the rotor, and the plunger connected to the nut produces a synchronous linear motion. The characteristics of this solution are: the plunger movement is indirectly driven by the nut, so that the setting of transmission threads on the plunger can be avoided, the plunger can be set to use ceramic materials to be suitable for various fluid conveying, and the good wear resistance maintains long-term performance stability.

[0033] In order to ensure the matching accuracy of the rotor and the nut, so that the position of the plunger in the plunger cavity can be accurately adjusted, the transmission efficiency is improved and the wear rate of the corresponding structure is reduced, and at the same time, the structure formed by the rotor and the nut is a ball screw structure. It is easy to understand that the rotor is used as a screw in the ball screw structure, and the nut is a nut in the ball screw structure. There is also a ball between the screw and the nut. Others include a reverser set on the nut.

[0034] It also includes a connecting sleeve, one end of which is fixed on the nut, and the other end of which is fixed on the plunger;

[0035] The stator of the first driving mechanism is connected to the pump body through a guide sleeve, the connecting sleeve is arranged on the inner side of the guide sleeve, and the outer wall of the connecting sleeve is in contact with the inner wall of the guide sleeve;

[0036] The plunger is provided with a blind hole whose opening is located at the rear end of the plunger, and the front end of the rotor can extend into the blind hole. The present invention provides a technical solution for connecting the nut and the plunger through a connecting sleeve, specifically: when the nut moves linearly, the connecting sleeve drives the plunger and the nut to move synchronously, and the specific fixing method can be that a shear pin is provided between the connecting sleeve and the nut, which are both made of metal materials. In order to prevent the connecting parts such as pins from damaging the plunger made of ceramic materials, a clamping protrusion is provided on the inner wall of the connecting sleeve, and a clamping groove is provided on the outer wall of the plunger. The rear end of the plunger is provided with a guide groove starting from the end of the plunger and extending along the axial direction of the plunger. The clamping groove is connected to the front end of the guide groove and is located on the side of the guide groove. The cam is sleeved onto the plunger through the guide groove on the plunger and is embedded in the cam groove by rotation when reaching the front end position; the present invention provides a technical solution that connects the pump body and the stator of the first driving mechanism through a guide sleeve, and uses the inner wall of the guide sleeve to provide support for the outer wall of the connecting sleeve, thereby reducing the radial displacement of the front end of the rotor to optimize the force on the plunger; the present invention provides a technical solution that provides a blind hole at the rear end of the plunger, and the front end of the rotor can be extended into the blind hole, so that the plunger has a longer length to ensure the axial sealing of the plunger, and the plunger pump as a whole has a shorter length.

[0037] The utility model has the following beneficial effects:

[0038] When the present solution is applied to the transportation of viscous fluids and there is fluid dripping and stringing at the end of the liquid outlet pipe, the first driving mechanism of the servo motor or the stepping motor can accurately adjust the number of rotations and the rotation angle, so that the plunger moves a smaller stroke after squeezing out the fluid to suck back the fluid dripping and stringing at the end of the liquid outlet pipe, and the movement amount of the plunger in the back-sucking action can be accurately adjusted according to the inner diameter of the liquid outlet pipe, the properties of the fluid, etc. At the same time, the structural form of the control mechanism makes the conduction and cutoff of the suction hole and the plunger cavity, and the conduction and cutoff of the plunger cavity and the discharge hole controlled by the second driving mechanism, and the suction hole can be controlled in any movement direction and position of the plunger. The conduction state between the plunger cavity and the discharge hole and the plunger cavity is realized to provide a structural basis for the fluid to be sucked back through the plunger on the basis of the inherent flow path, so as to reduce or avoid the occurrence of dripping and drawing fluid falling, so as to ensure the accuracy of fluid delivery and reduce unnecessary fluid waste; in addition, the pressure of the fluid in the suction hole and the discharge hole cannot or is not easy to cause unplanned changes in the conduction state between the plunger cavity and the suction hole and the discharge hole. Therefore, when this scheme is used in the working condition where the fluid upstream of the suction hole needs to be pre-pressurized, this plunger pump can effectively avoid unplanned fluid output; at the same time, this scheme also allows the discharge hole and the suction hole to switch functions with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1It is a front view of a specific embodiment of a plunger pump for preventing fluid dripping and wire drawing described in this scheme;

[0040] Figure 2 for Figure 1 a side view of the structure shown;

[0041] Figure 3 for Figure 2 The structure shown is a cross-sectional view obtained by cutting along the AA direction;

[0042] Figure 4 for Figure 3 A partial enlarged view of section A is shown.

[0043] The reference numerals in the figure are respectively: 1. first driving mechanism, 2. rotor, 3. nut, 4. connecting sleeve, 5. plunger, 6. pump body, 7. first connecting hole, 8. suction hole, 9. axial hole, 10. radial hole, 11. discharge hole, 12. sleeve, 13. valve core, 14. second driving mechanism, 15. transmission mechanism, 16. plunger pump body, 17. elastic member, 18. liquid inlet pipe, 19. liquid outlet pipe, 20. retaining ring, 21. guide sleeve. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with the embodiments, but the present invention is not limited to the following embodiments:

[0045] Embodiment 1:

[0046] like Figures 1 to 4 As shown, a plunger pump for preventing fluid dripping and wire drawing comprises a plunger pump body 16, a first driving mechanism 1 for driving the plunger pump body 16 to move, the plunger pump body 16 comprises a plunger 5 and a pump body 6, one end of the plunger 5 is arranged in the plunger cavity of the pump body 6, the first driving mechanism 1 is connected to the plunger 5, the pump body 6 is also provided with a suction hole 8 and a discharge hole 11, and also comprises a control mechanism, the control mechanism is used to control the conduction state between the plunger cavity and the suction hole 8, and between the plunger cavity and the discharge hole 11, the control mechanism comprises a valve core 13 installed on the pump body 6 and a second driving mechanism 14 for driving the valve core 13 to move, the valve core 13 is provided with a second communicating hole, and the orifice at one end of the second communicating hole is communicated with the plunger cavity;

[0047] The valve core 13 can move as follows:

[0048] In the first state, the opening at the other end of the second communication hole is connected to the liquid suction hole 8;

[0049] In the second state, the opening at the other end of the second communication hole communicates with the drainage hole 11;

[0050] The first driving mechanism 1 is a servo motor or a stepping motor.

[0051] As shown in the technical solution provided in the patent application document with patent application number CN201611206459.2, in the prior art, plunger pumps mostly use a cylinder to drive the movement of the plunger 5 of the plunger pump, and control the conduction state of the plunger cavity on the plunger pump and the suction hole 8 and the discharge hole 11 through a control mechanism with a spring and pressure-controlled opening or closing. When such a plunger pump is used for quantitative delivery of viscous fluid, after the plunger 5 completes the specified number of reciprocating motions to achieve quantitative delivery, if there is dripping or wire-drawing liquid at the end of the liquid outlet pipe connected to the liquid outlet pipe 19 on the discharge hole 11, it is difficult to control the cylinder to drive the plunger 5 to move with a smaller stroke to achieve the back suction of the dripping or wire-drawing liquid. At the same time, the control mechanism with a spring and pressure-controlled opening or closing is mostly a one-way valve mechanism. Such a mechanism does not allow the fluid to flow in the opposite direction after the control mechanism is opened. Therefore, the pipe fittings on the fluid flow path do not allow the fluid to be reversely conducted to achieve the back suction of the dripping or wire-drawing liquid when the plunger 5 moves, which causes the uncontrollable falling of the dripping or wire-drawing fluid. When the dripping or wire-drawing fluid falls into the fluid collection container used for quantitative fluid collection below the liquid outlet pipe, the fluid collection container collects different amounts of fluid in the two collections compared to the fluid collection container into which the dripping or wire-drawing fluid does not fall. This situation is not conducive to controlling the accuracy of fluid delivery. When the dripping or wire-drawing fluid falls outside the fluid collection container, fluid waste will be caused. In addition, when the plunger pump is used for quantitative delivery of viscous fluid, a feeding device is generally connected to the suction hole 8 through the liquid inlet pipe 18. The feeding device is connected to the liquid inlet pipe 18 by a liquid supply pipe, and the feeding device provides pressurized fluid to the suction hole 8. When the feeding device pressurizes the fluid too much, the control mechanism of the one-way valve mechanism will be opened unplanned. At this time, the suction hole 8 and the discharge hole 11 on the plunger pump are directly connected, and the plunger pump will discharge fluid unplanned.

[0052] In view of the above problems, a plunger pump as described above is provided. Specifically, the first driving mechanism 1 drives the plunger 5 to reciprocate in the plunger cavity so that the plunger pump body 16 sucks and squeezes the fluid. Specifically, when the valve core 13 is moved to connect the plunger cavity and the suction hole 8 through the second connecting hole under the action of the second driving mechanism 14 (in the first state), the plunger 5 performs a suction action, so that the fluid is sucked into the plunger cavity, and at this stage the plunger cavity and the discharge hole 11 are cut off by the valve core 13; when the valve core 13 is moved to connect the plunger cavity and the discharge hole 11 through the second connecting hole under the action of the second driving mechanism 14 (in the second state), the plunger 5 performs an extrusion action, so that the fluid is squeezed from the plunger cavity into the discharge hole 11, and at this stage the plunger cavity and the suction hole 8 are cut off by the valve core 13.

[0053] Therefore, when the above scheme is applied to the delivery of viscous fluids and there is a phenomenon of fluid dripping and wire drawing at the end of the liquid outlet pipe, the first driving mechanism 1 of the servo motor or the stepping motor can accurately adjust the number of rotations and the rotation angle, so that the plunger 5 moves a smaller stroke after squeezing out the fluid to suck back the fluid dripping and wire drawing at the end of the liquid outlet pipe, and the movement amount of the plunger 5 in the back-suction action can be accurately adjusted according to the inner diameter of the liquid outlet pipe, the properties of the fluid, etc., to avoid excessive suction causing the plunger pump efficiency to decrease. At the same time, the structural form of the control mechanism makes the conduction and cutoff of the suction hole 8 and the plunger cavity, and the conduction and cutoff of the plunger cavity and the discharge hole 11 controlled by the second driving mechanism 14, and the conduction state of the suction hole 8 and the plunger cavity, and the conduction state of the discharge hole 11 and the plunger cavity can be controlled in any movement direction and position of the plunger 5, so as to realize the provision of a fluid for sucking back through the plunger 5 on the basis of the inherent flow path (it is not necessary to use a separate fluid to realize the function of dripping and wire drawing fluid back-suction). Structural basis, for example, when sucking back the dripping and drawing fluid, the plunger cavity and the suction hole 8 are cut off and the plunger cavity and the discharge hole 11 are connected, and the plunger 5 retreats to suck the dripping and drawing fluid into the liquid outlet pipe to reduce or avoid the dripping and drawing fluid falling so as to ensure the accuracy of fluid delivery and reduce unnecessary fluid waste; in addition, since the maintenance of the above first state and the second state is controlled by the second driving mechanism 14, the pressure of the fluid in the suction hole 8 and the discharge hole 11 cannot or is not easy to cause unplanned changes in the connection state between the plunger cavity and the suction hole 8 and the discharge hole 11. Therefore, when this scheme is used in the working condition where the fluid upstream of the suction hole 8 needs to be pre-pressurized, the plunger pump can effectively avoid unplanned fluid output; at the same time, this scheme can also make the discharge hole 11 and the suction hole 8 switchable in function: the discharge hole 11 can be switched to the suction hole 8 that performs the suction function, and the suction hole 8 can be switched to the discharge hole 11 that performs the discharge function.

[0054] In a specific implementation, under the action of the control mechanism, the valve core 13 is used to change the conduction between the plunger cavity and the suction hole 8 and the discharge hole 11 through the second connecting hole thereon, so the movement of the valve core 13 can be movement or rotation. For example, when the valve core 13 moves to different positions or rotates to different angles, the orifice at the other end of the second connecting hole has a different docking state with the suction hole 8 and the discharge hole 11. Therefore, one of the control parameters of this scheme is the movement amount of the valve core 13. In order to better realize the control of the movement amount, the second driving mechanism 14 can use a stepping motor, a servo motor, or a A hydraulic cylinder or a pneumatic cylinder can be used. For example, when a hydraulic cylinder or a pneumatic cylinder is used, when the corresponding piston moves to two front and rear dead point positions, at one of the dead point positions, the suction hole 8 is connected to the plunger cavity and the plunger cavity and the discharge hole 11 are cut off; at the other dead point position, the suction hole 8 is cut off from the plunger cavity and the plunger cavity and the discharge hole 11 are connected. In addition, the linear motion or rotation output by the second drive mechanism 14 can be converted into a drive valve core 13 to move or rotate through a motion state conversion mechanism. Since the relevant motion state conversion mechanism is a prior art, no further specific description is made in this scheme.

[0055] Embodiment 2:

[0056] This embodiment is further refined on the basis of embodiment 1:

[0057] The pump body 6 is also provided with an installation cavity, the valve core 13 is installed in the installation cavity, the suction hole 8 and the discharge hole 11 are both connected to the installation cavity, and the suction hole 8 and the discharge hole 11 have different communication positions on the installation cavity that are connected to the installation cavity;

[0058] The second driving mechanism 14 is used to drive the valve core 13 to move or rotate in the installation cavity. Through the movement or rotation, the valve core 13 is adjusted to switch between the first state and the second state. In this solution, the outlet end of the suction hole 8 and the inlet end of the discharge hole 11 are both connected to the installation cavity, and the outlet end and the inlet end are distributed at different positions of the installation cavity. When the valve core 13 moves or rotates in the installation cavity under the action of the second driving mechanism 14, the valve core 13 at different positions or angles is adjusted to use the second connecting hole to realize the connection between the plunger cavity and the suction hole 8 and cut off from the discharge hole 11, and to use the second connecting hole to realize the connection between the plunger cavity and the discharge hole 11 and cut off from the suction hole 8.

[0059] Embodiment 3:

[0060] This embodiment is further refined on the basis of Embodiment 2:

[0061] It also includes a first communicating hole 7 disposed on the pump body 6 and communicating the installation cavity with the plunger cavity, wherein an opening at one end of the first communicating hole 7 is located at the front end of the plunger cavity;

[0062] The second communication hole is composed of an axial hole 9 and a radial hole 10, the axial hole 9 is connected to the radial hole 10, the opening of the axial hole 9 is located on the end surface of the valve core 13, the opening of the radial hole 10 is located on the side of the valve core 13, and the opening of the axial hole 9 is connected to the opening of the other end of the first communication hole 7;

[0063] The second driving mechanism 14 is used to drive the valve core 13 to rotate in the installation cavity, and by controlling the rotation angle of the valve core 13 under the action of the second driving mechanism 14, the orifice of the radial hole 10 is adjusted to be connected with the suction hole 8 and the discharge hole 11. When the orifice of the radial hole 10 is connected with the suction hole 8, the valve core 13 is in the first state, and when the orifice of the radial hole 10 is connected with the discharge hole 11, the valve core 13 is in the second state. In the present solution, the first connecting hole 7 is used to connect the installation cavity and the plunger cavity, so as to realize the connection between the front end of the plunger cavity and the second connecting hole and make the installation cavity a channel on the pump body 6 away from the plunger cavity. The shape of the second connecting hole and the distribution position of the hole opening are a technical solution that is convenient for processing, simple in structure and easy to ensure processing accuracy; it is a technical solution that can always keep the hole opening of the axial hole 9 connected with the first connecting hole 7 during the rotation of the valve core 13, and realize the connection between the radial hole 10 and the suction hole 8 or the discharge hole 11 at different rotation angles; it is a technical solution that is compared with the valve core 13 realizing the switching between the first state and the second state by moving, and adopts the method of rotating the valve core 13 to avoid the pressure change in the flow path causing the stability of the valve core 13 to be affected or causing unnecessary force on the second drive mechanism 14.

[0064] Embodiment 4:

[0065] This embodiment is further refined on the basis of embodiment 1:

[0066] It also includes a sleeve 12 mounted on the pump body 6, and the valve core 13 is installed in the inner hole of the sleeve 12;

[0067] The sleeve 12 is fixed in the mounting cavity on the pump body 6, and the second driving mechanism 14 drives the valve core 13 to move relative to the sleeve 12, and the surface of the valve core 13 contacts the hole wall of the inner hole;

[0068] A communication channel is provided on the side wall of the sleeve 12, and the communication channel includes a first channel for realizing communication between the second communication hole and the suction hole 8 and a second channel for realizing communication between the second communication hole and the discharge hole 11. In the above scheme, since the valve core 13 is a moving part on the pump body 6 and directly contacts the fluid, in order to ensure the performance of the plunger pump, it is necessary to consider the wear problem of the valve core 13 and the fluid leakage problem at the position of the valve core 13. It is set to also include the sleeve 12 and install the valve core 13 in the inner hole of the sleeve 12. Compared with directly installing the valve core 13 on the pump body 6, the sleeve 12 can be manufactured separately as a part on the pump body 6. For example, the pump body 6 is made of stainless steel to provide good pressure bearing capacity, and the sleeve 12 is made of composite materials, polymer materials or metal materials with good wear resistance and easy processing of the inner hole wall into a smooth wall. In this way, in the process of relative movement between the valve core 13 and the sleeve 12, the good wear resistance of the sleeve 12 and the good matching accuracy of the valve core 13 and the sleeve 12 can effectively ensure the performance and life of the plunger pump. In specific implementation, it is better to use stainless steel for the pump body 6, ceramic for the plunger 5 and the valve core 13, and a polymer material resistant to organic solvents for the sleeve 12.

[0069] Embodiment 5:

[0070] This embodiment is further refined on the basis of Embodiment 4:

[0071] The second driving mechanism 14 is used to drive the valve core 13 to rotate;

[0072] The inner hole has a tapered hole section, and the valve core 13 has a tapered section that fits the tapered hole section;

[0073] Of the two openings of the second connecting hole, one opening is located on the side of the tapered section, and the other opening is located on the end face of the valve core 13. The opening on the side is located between the end face and the end with a smaller diameter of the tapered section. This scheme is a technical scheme in which the valve core 13 changes the conduction state between the plunger cavity and the suction hole 8 and the discharge hole 11 by rotating. Specifically, it is a technical scheme in which the tapered hole section and the tapered section are arranged so that the inner wall of the valve core 13 and / or the sleeve 12 is worn less than the maximum wear amount (the maximum wear amount is that the tapered hole section cannot provide axial support for the tapered section). During the fluid extrusion process of the plunger pump, the pressure exerted on the valve core 13 by the fluid can make the valve core 13 move toward the end with a smaller diameter of the tapered hole section, and the axial sealing of the valve core 13 and the inner hole matching surface is achieved with the help of the pressure. In a specific implementation, the conical section is the section with the largest diameter on the valve core 13, and the valve core 13 and the second driving mechanism 14 which is a driving motor are driven through a gear set. After removing the constraint of the sleeve 12 on the valve core 13, the valve core 13 can move toward the end with a smaller diameter of the conical section to achieve the purpose of the movement.

[0074] Embodiment 6:

[0075] This embodiment is further refined on the basis of Embodiment 5:

[0076] In specific application, when it is not necessary to pressurize the fluid upstream of the suction hole 8 or the pressurized pressure is low, it is easy to maintain the axial sealing of the gap between the sleeve 12 and the valve core 13 during fluid suction and extrusion through the matching state of the sleeve 12 and the valve core 13, and prevent the fluid in the suction hole 8 from directly entering the discharge hole 11 from the gap. However, when it is necessary to pressurize the fluid upstream of the suction hole 8 to a higher pressure, the fluid may still enter the discharge hole 11 from the suction hole 8 through the gap during the suction process of the plunger 5. In order to solve this problem, a certain positive pressure can always be maintained between the tapered hole section and the tapered section to prevent the fluid in the suction hole 8 from directly entering the discharge hole 11 from the gap or axial leakage through the gap. A pre-tightening structure is also included, which acts on the valve core 13 and is used to apply a force relative to the sleeve 12 to the valve core 13, and the direction of the force is: toward the side with a smaller diameter of the tapered section. In this solution, the pre-tightening structure is used to provide the valve core 13 with a continuous force toward the small end of the tapered hole section, and the force is used to maintain the positive pressure between the tapered hole section and the tapered section, thereby avoiding the axial leakage and the problem that the fluid in the suction hole 8 directly enters the discharge hole 11 from the gap. A preferred application is that the tapered hole section and the tapered section have the same size.

[0077] Embodiment 7:

[0078] This embodiment is further refined on the basis of Embodiment 6:

[0079] The pre-tightening structure includes a retaining ring 20 fixed on the valve core 13, and the pre-tightening structure also includes an elastic member 17 clamped between the inner end of the retaining ring 20 and the outer end of the sleeve 12 and in a compressed and deformed state. This scheme is a specific implementation method of the pre-tightening structure, specifically: the compressed elastic member 17 provides thrust for the retaining ring 20, and after the thrust is transmitted to the valve core 13 through the retaining ring 20, the valve core 13 obtains a force to move toward the small end of the tapered hole section. In this scheme, the elastic member 17 can be a metal elastic pad. Other applications also include setting an elastic member 17 between one end of the valve core 13 that penetrates into the pump body 6 and the pump body 6, but this method needs to consider the influence of the fluid on the elastic member 17, which is not conducive to the selection of the elastic member 17 and the ability to maintain performance.

[0080] Embodiment 8:

[0081] This embodiment is further refined on the basis of embodiment 1:

[0082] The first driving mechanism 1 comprises a rotor 2, and the rotor 2 is connected to a plunger 5 via a transmission mechanism 15;

[0083] The transmission mechanism 15 includes a nut 3 and an anti-rotation restraint member;

[0084] The rotor 2 is threadedly connected to the nut 3 via an external thread thereon, and the nut 3 is connected to the plunger 5;

[0085] The anti-rotation restraint is used to prevent the nut 3 from rotating. In this solution, the rotor 2 with external threads is a screw rod, and the nut 3 is threadedly connected to the screw rod. In this way, when the rotor 2 rotates, the nut 3 cannot rotate because it is blocked by the anti-rotation restraint. Therefore, according to the rotation direction of the rotor 2, the nut 3 generates a linear motion in a specific direction on the axis of the rotor 2, and the plunger 5 connected to the nut 3 generates a synchronous linear motion. The characteristics of this solution are: the plunger 5 is indirectly driven to move by the nut 3, so that the setting of a transmission thread on the plunger 5 can be avoided, and the plunger 5 can be set to use a ceramic material to be suitable for various fluid conveying, and maintain long-term performance stability with good wear resistance.

[0086] Embodiment 9:

[0087] This embodiment is further refined on the basis of Embodiment 8:

[0088] In order to ensure the matching accuracy between the rotor 2 and the nut 3, so that the position of the plunger 5 in the plunger cavity can be accurately adjusted, the transmission efficiency is improved and the wear rate of the corresponding structure is reduced, and at the same time, the structure formed by the rotor 2 and the nut 3 is a ball screw structure, which is easy to understand. The rotor 2 is used as a screw in the ball screw structure, and the nut 3 is a nut in the ball screw structure. There is also a ball between the screw and the nut 3, and other parts include a reverser set on the nut 3.

[0089] Embodiment 10:

[0090] This embodiment is further refined on the basis of Embodiment 8:

[0091] It also includes a connecting sleeve 4, one end of which is fixed on the nut 3, and the other end of which is fixed on the plunger 5;

[0092] The stator of the first driving mechanism 1 is connected to the pump body 6 through the guide sleeve 21, the connecting sleeve 4 is arranged on the inner side of the guide sleeve 21, and the outer wall of the connecting sleeve 4 is in contact with the inner wall of the guide sleeve 21;

[0093] The plunger 5 is provided with a blind hole whose opening is located at the rear end of the plunger 5, and the front end of the rotor 2 can extend into the blind hole. The present invention provides a technical solution for connecting the nut 3 and the plunger 5 through a connecting sleeve 4, specifically: when the nut 3 moves linearly, the connecting sleeve 4 drives the plunger 5 and the nut 3 to move synchronously. The specific fixing method can be that a shear pin is provided between the connecting sleeve 4 and the nut 3, which are both made of metal materials. In order to prevent the connecting parts such as pins from damaging the plunger 5 made of ceramic materials, the inner wall of the connecting sleeve 4 is provided with a clamping protrusion, and the outer wall of the plunger 5 is provided with a clamping groove. The rear end of the plunger 5 is provided with a guide groove starting from the end of the plunger 5 and extending along the axial direction of the plunger 5. The clamping groove is connected to the front end of the guide groove and is located on the side of the guide groove. The cam is sleeved onto the plunger 5 through the guide groove on the plunger 5 and is embedded in the cam groove by rotation when reaching the front end position; the present solution provides a technical solution that connects the pump body 6 and the stator of the first drive mechanism 1 through the guide sleeve 21, and uses the inner wall of the guide sleeve 21 to provide support for the outer wall of the connecting sleeve 4, thereby reducing the radial displacement of the front end of the rotor 2 to optimize the force on the plunger 5; the present solution provides a technical solution that provides a blind hole at the rear end of the plunger 5, and the front end of the rotor 2 can extend into the blind hole, so that the plunger 5 has a longer length to ensure the axial sealing of the plunger 5, and the plunger pump as a whole has a shorter length.

[0094] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and the specific embodiments of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, other embodiments derived without departing from the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A plunger pump for preventing fluid dripping and wire drawing, comprising a plunger pump body (16), and a first driving mechanism (1) for driving the plunger pump body (16) to move, wherein the plunger pump body (16) comprises a plunger (5) and a pump body (6), one end of the plunger (5) is arranged in a plunger cavity of the pump body (6), the first driving mechanism (1) is connected to the plunger (5), and the pump body (6) is further provided with a liquid suction hole (8) and a liquid discharge hole (11), and further comprising a control mechanism, wherein the control mechanism is used to control the conduction state between the plunger cavity and the liquid suction hole (8), and between the plunger cavity and the liquid discharge hole (11), and the characteristics are as follows: The control mechanism comprises a valve core (13) mounted on the pump body (6) and a second driving mechanism (14) for driving the valve core (13) to move, the valve core (13) being provided with a second communicating hole, an orifice at one end of the second communicating hole being in communication with the plunger cavity; The valve core (13) can move: In the first state, the opening at the other end of the second communicating hole is in communication with the liquid suction hole (8); In the second state, the opening at the other end of the second communication hole is in communication with the drainage hole (11); The first driving mechanism (1) is a servo motor or a stepping motor.

2. A plunger pump for preventing fluid dripping and wire drawing according to claim 1, characterized in that: The pump body (6) is also provided with an installation cavity, the valve core (13) is installed in the installation cavity, the liquid suction hole (8) and the liquid discharge hole (11) are both connected to the installation cavity, and the liquid suction hole (8) and the liquid discharge hole (11) have different communication positions on the installation cavity that are connected to the installation cavity; The second driving mechanism (14) is used to drive the valve core (13) to move or rotate in the installation cavity, and through the movement or rotation, the valve core (13) is adjusted to switch between the first state and the second state.

3. A plunger pump for preventing fluid dripping and wire drawing according to claim 2, characterized in that: It also includes a first communication hole (7) provided on the pump body (6) and communicating the installation cavity with the plunger cavity, wherein an opening at one end of the first communication hole (7) is located at the front end of the plunger cavity; The second communicating hole is composed of an axial hole (9) and a radial hole (10), the axial hole (9) is connected to the radial hole (10), the opening of the axial hole (9) is located on the end surface of the valve core (13), the opening of the radial hole (10) is located on the side surface of the valve core (13), and the opening of the axial hole (9) is connected to the opening of the other end of the first communicating hole (7); The second driving mechanism (14) is used to drive the valve core (13) to rotate in the installation cavity, and by controlling the rotation angle of the valve core (13) under the action of the second driving mechanism (14), the orifice of the radial hole (10) is adjusted to be in communication with the suction hole (8) and the discharge hole (11). When the orifice of the radial hole (10) is in communication with the suction hole (8), the valve core (13) is in the first state, and when the orifice of the radial hole (10) is in communication with the discharge hole (11), the valve core (13) is in the second state.

4. A plunger pump for preventing fluid dripping and wire drawing according to claim 1, characterized in that: It also includes a sleeve (12) mounted on the pump body (6), the valve core (13) being mounted in the inner hole of the sleeve (12); The sleeve (12) is fixed in a mounting cavity on the pump body (6), and the second driving mechanism (14) drives the valve core (13) to move relative to the sleeve (12), so that the surface of the valve core (13) contacts the hole wall of the inner hole; A communication channel is provided on the side wall of the sleeve (12), and the communication channel comprises a first channel for enabling the second communication hole to communicate with the liquid suction hole (8) and a second channel for enabling the second communication hole to communicate with the liquid discharge hole (11).

5. A plunger pump for preventing fluid dripping and wire drawing according to claim 4, characterized in that: The second driving mechanism (14) is used to drive the valve core (13) to rotate; The inner hole has a tapered hole section, and the valve core (13) has a tapered section that fits the tapered hole section; Of the two openings of the second connecting hole, one opening is located on the side surface of the tapered section, and the other opening is located on the end surface of the valve core (13), and the opening on the side surface is located between the end surface and an end of the tapered section with a smaller diameter.

6. A plunger pump for preventing fluid dripping and wire drawing according to claim 5, characterized in that: It also comprises a pre-tightening structure, which acts on the valve core (13) and is used to apply a force to the valve core (13) relative to the sleeve (12), wherein the direction of the force is towards the side of the tapered section with a smaller diameter.

7. A plunger pump for preventing fluid dripping and wire drawing according to claim 6, characterized in that: The pre-tightening structure comprises a clamping ring (20) fixed on the valve core (13), and the pre-tightening structure also comprises an elastic member (17) clamped between the inner end of the clamping ring (20) and the outer end of the sleeve (12) and in a compressed and deformed state.

8. A plunger pump for preventing fluid dripping and wire drawing according to any one of claims 1 to 7, characterized in that: The first driving mechanism comprises a rotor (2), and the rotor (2) is connected to the plunger (5) via a transmission mechanism (15); The transmission mechanism (15) comprises a nut (3) and an anti-rotation restraint member; The rotor (2) is threadably connected to the nut (3) via an external thread thereon, and the nut (3) is connected to the plunger (5); The anti-rotation restraint member is used to prevent the nut (3) from rotating.

9. A plunger pump for preventing fluid dripping and wire drawing according to claim 8, characterized in that: The structure formed by the rotor (2) and the nut (3) is a ball screw structure.

10. The plunger pump for preventing fluid dripping and wire drawing according to claim 8, characterized in that: It also comprises a connecting sleeve (4), one end of the connecting sleeve (4) is fixed on the nut (3), and the other end of the connecting sleeve (4) is fixed on the plunger (5); The stator of the first driving mechanism (1) is connected to the pump body (6) via a guide sleeve (21), the connecting sleeve (4) is arranged on the inner side of the guide sleeve (21), and the outer wall of the connecting sleeve (4) is in contact with the inner wall of the guide sleeve (21); The plunger (5) is provided with a blind hole whose opening is located at the rear end of the plunger (5), and the front end of the rotor (2) can extend into the blind hole.

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