A dual-unit pulsation-free metering pump

Abstract

The present invention relates to the field of metering pumps, and in particular to a dual-unit pulsation-free metering pump, comprising a first pump head, a second pump head, and a transmission end assembly shared by the first pump head and the second pump head, wherein the transmission end assembly comprises a body, a camshaft movably connected in the body, and a cam member mounted on the camshaft, wherein the rotation angles of the two cam members have a phase difference of 180°, and a reduction motor is mounted on the body, wherein the output end of the reduction motor is connected to one end of the camshaft, the reduction motor is used to drive the camshaft to rotate, and the camshaft is used to drive the two cam members to rotate while maintaining a rotation angle of 180° phase difference; the present invention only uses dual pump heads, i.e., only two pump heads are needed, which not only has a simple structure, but also greatly reduces the parts with high failure rates such as the hydraulic end of the metering pump, reduces the use and loss of wearing parts of the valve assembly of the pump head, thereby reducing the cost of production and use, and improving the economic benefits of customers.

Description

Technical Field

[0001] The present invention relates to the field of metering pumps, in particular to a dual-unit pulsation-free metering pump. Background Art

[0002] Metering pumps are positive displacement reciprocating pumps that measure and deliver liquids, making them indispensable in many industrial fields. However, due to their basic structure and operating principle, they generally rely on a traditional crank-connecting rod mechanism. This results in relatively fixed motion and dynamic characteristics, which inevitably manifest as flow and pressure pulsations in the medium they are conveying.

[0003] However, with the application and technological advantages of continuous flow microreactor technology, this pulsation problem urgently needs to be solved. Because this process technology has extremely strict requirements for flow pulsation, although traditional metering pumps have the characteristics of adjustable flow and precise metering, they generally produce pulsating flow. This will cause fluid instability in the microreactor of microreactor technology, which greatly affects the implementation of the process and the stability of the finished product quality.

[0004] While there are traditional solutions to flow pulsation, such as using a buffer tank to suppress flow pulsation, or employing three pumps in parallel to achieve a relatively stable flow rate by superimposing instantaneous flow rates, or reducing the flow rate by using larger pumps and increasing the size of the delivery pipeline, these solutions can achieve certain technical results but also increase procurement costs and subsequent on-site operations and maintenance. Summary of the Invention

[0005] In order to overcome the problem that traditional metering pumps will produce flow pulsation and cause fluid instability in the microreactor.

[0006] The technical solution of the present invention is: a dual-unit pulsation-free metering pump, comprising a first pump head and a second pump head and a transmission end assembly shared by the first pump head and the second pump head, the transmission end assembly comprising a body, a camshaft movably connected in the body and a cam member installed on the camshaft, the rotation angles of the two cam members have a 180° phase difference, a reduction motor is installed on the body, the output end of the reduction motor is connected to one end of the camshaft, the reduction motor is used to drive the camshaft to rotate, and the camshaft is used to drive the two cam members to rotate with a rotation angle of 180° phase difference; the first pump head and the second pump head each comprise a set of guide assemblies, a linkage module and a plunger connection assembly movably connected in the guide assembly, and a hydraulic end assembly installed at the end of the guide assembly; one end of the linkage module abuts against the corresponding cam member, the two cam members respectively drive the corresponding linkage module to move in the guide assembly, and the other end of the linkage module is installed with a plunger The connecting component and the linkage module are used to drive the plunger connecting component to move on the corresponding hydraulic end assembly; the hydraulic end assembly includes a hydraulic chamber filled with hydraulic oil, a medium chamber for conveying fluid, and a diaphragm installed between the hydraulic chamber and the medium chamber; when the plunger connecting component enters the hydraulic chamber, the hydraulic oil is compressed and the medium chamber discharges the fluid; when the plunger connecting component moves out of the hydraulic chamber, the hydraulic oil expands and the medium chamber absorbs the fluid. The diaphragm can adopt shape memory polymer SMP, which can restore the preset shape under a specific temperature or electric field, and trigger rapid deformation through hydraulic pressure. The deformation mode is preset according to the hydraulic changes in actual applications, and the synchronization between the plunger and the diaphragm is optimized. For the metering pump field in the present invention, the SMP diaphragm actively adjusts the deformation amplitude during the compression / expansion stroke to reduce the hysteresis effect, and the hydraulic force transmission response effect is very good, realizing the coordination of hydraulic drive and active material response, breaking the traditional passive mechanical transmission mode.

[0007] Preferably, a flat key is provided on the camshaft, and a keyway adapted to the flat key is provided on each of the two cam members. The two cam members are limited by the flat key and the keyway and the camshaft. The axes of the two cam members are concentric, and the camshaft drives the two cam members to rotate at the same preset angular velocity.

[0008] Preferably, the shoulder of the camshaft rests against the side end face of the cam member and is used to prevent the cam member from axial movement. The outer contour surface of the cam member has a high-hardness coating, and the contact surface of the cam member and the flat-bottom push rod adopts a high-hardness, low-friction coefficient surface treatment process (such as nitriding, chrome plating or ceramic coating) to reduce wear and extend service life.

[0009] Preferably, the linkage module includes a flat-bottom push rod movably connected in the guide assembly and a compression spring installed on the flat-bottom push rod, the flat bottom surface of the flat-bottom push rod is in close contact with the outer contour surface of the cam part, one end of the compression spring rests on the flat bottom surface of the flat-bottom push rod, and the other end rests on the guide assembly.

[0010] Preferably, an elastic cylindrical pin is installed on the flat-bottom push rod, and both ends of the elastic cylindrical pin protrude beyond the shaft diameter of the flat-bottom push rod. A groove is provided at the head end of the guide assembly, and the elastic cylindrical pin is embedded in the groove.

[0011] Preferably, the guide assembly includes a slide fixedly connected to the body by a first hexagon socket screw and a guide sleeve fixedly connected to the slide, the guide sleeve is connected to the slide by a second hexagon socket screw, the flat-bottom push rod moves along the axial direction of the slide, and a plurality of axial oil guide holes are opened on the slide. The axial oil guide holes adopt a multi-stage diversion structure (such as a tapered aperture or a spiral groove), combined with the polishing treatment of the inner wall of the guide sleeve to ensure that the lubricating oil flows evenly and covers the surface of the flat-bottom push rod.

[0012] Preferably, a connector is installed between the slide and the plunger connecting assembly, and a cavity structure is provided in the connector. The lubricating oil flows from the guide assembly to the hydraulic end assembly and the plunger connecting assembly through the cavity structure, and the cam drives the flat-bottom push rod to move back and forth in the guide sleeve.

[0013] Preferably, the plunger connection assembly includes a plunger member movably connected in the hydraulic end assembly, one end of the plunger member is connected to the flat-bottom push rod through an assembly connection member, and the flat-bottom push rod drives the plunger member to reciprocate linearly in the hydraulic chamber through the assembly connection member.

[0014] Preferably, the assembly connection includes a cap nut tightened on the flat-bottom push rod, a threaded sleeve tightened on the piston member, and a flat washer arranged between the plunger member and the cap nut. The threaded sleeve is connected to the cap nut and fixed by a hexagonal nut. A liquid cylinder body is provided on the guide assembly. The inner hole of the liquid cylinder body is used to seal the outer circumferential surface of the plunger member. A wave spring gasket can be arranged between the threaded sleeve and the cap nut to compensate for the slight gap of the thread fit, ensure the coaxiality of the crosshead and the plunger member, and reduce eccentric wear.

[0015] Preferably, a pump suction port is provided at one end of the hydraulic end assembly, and a pump discharge port is provided at the other end. A suction check valve is installed on the pump suction port, and a discharge check valve is installed on the pump discharge port. The pump suction port of the first pump head and the pump suction port of the second pump head are connected through a set of pipes to form a common suction manifold, and the pump discharge port of the first pump head and the pump discharge port of the second pump head are connected through a set of pipes to form a common discharge manifold.

[0016] Beneficial effects of the present invention:

[0017] 1. Only two pump heads are used, which not only simplifies the structure but also greatly reduces the parts with high failure rates such as the hydraulic end of the metering pump, reduces the use and loss of wearing parts of the pump head valve assembly, thereby reducing the cost of production and use, and improving the economic benefits of customers;

[0018] 2. By utilizing specially designed motion laws and implementing them through the outer contour working surface of the cam, the sinusoidal curve of reciprocating motion is transformed into a linear velocity curve of uniform acceleration-uniform speed-uniform deceleration, eliminating flow and pressure pulsations from the essence of motion characteristics;

[0019] 3. No additional air dampers are needed to absorb and eliminate pulsation, which greatly reduces additional costs and operation and maintenance investment;

[0020] 4. The cam mechanism adopts the structure of concentric linear flat push rod disc cam instead of roller cam structure, so that the pressure angle of the cam mechanism is zero, thereby improving the force condition of the transmission mechanism;

[0021] 5. An oil film is more easily formed between the contact surfaces of the cam and the flat-bottom push rod, thereby ensuring lubrication between the friction pairs, reducing wear between high-pair parts, and increasing the service life of core parts;

[0022] 6. The force-enclosed cam mechanism, combined with a specially designed high-fatigue-strength compression spring, reduces the overall size of the cam mechanism, makes the structure compact, and saves equipment space. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a schematic diagram of a first structure of a dual-unit pulsation-free metering pump of the present invention;

[0024] Figure 2 Shown is a schematic diagram of a second structure of a dual-unit pulsation-free metering pump of the present invention;

[0025] Figure 3 Shown is a schematic diagram of a third configuration of the dual-unit pulsation-free metering pump of the present invention;

[0026] Figure 4 Shown is a schematic diagram of a dual-unit pulsation-free metering pump medium delivery system of the present invention;

[0027] Figure 5 Shown is a linear diagram of the cam rotation angle and plunger speed of the present invention;

[0028] Figure 6 Shown is a linear diagram of the cam rotation angle and plunger displacement of the present invention.

[0029] Explanation of reference numerals: 1, body; 7, cam member; 9, flat key; 11, end cover; 17, elastic cylindrical pin; 18, flat bottom push rod; 19, camshaft; 102, slideway; 103, first hexagon socket screw; 107, guide sleeve; 108, compression spring; 109, second hexagon socket screw; 104, connector; 334, flat washer; 335, cap nut; 336, threaded sleeve; 337, hexagon socket Angle nut; 431, hydraulic cylinder body; 2, plunger; 29, exhaust valve; 60, hydraulic chamber; 61, medium chamber; 27, diaphragm; 30, first pump head; 31, second pump head; 32, suction check valve; 33, discharge check valve; 34, suction line; 35, discharge line; 36, pump suction port; 37, pump discharge port; 38, common suction manifold; 39, common discharge manifold; 40, axial oil guide hole. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and examples.

[0031] See also Figures 1-6 The present invention provides an embodiment: a dual-unit pulsation-free metering pump, comprising a first pump head 30 and a second pump head 31, and a transmission end assembly shared by the first pump head 30 and the second pump head 31, the transmission end assembly comprising a body 1, a camshaft 19 movably connected in the body 1, and a cam member 7 mounted on the camshaft 19, the rotation angles of the two cam members 7 having a phase difference of 180 degrees, a reduction motor being mounted on the body 1, the output end of the reduction motor being connected to one end of the camshaft 19, the reduction motor being used to drive the camshaft 19 to rotate, and the camshaft 19 being used to drive the two cam members 7 to rotate while maintaining a rotation angle of 180 degrees of phase difference; the first pump head 30 and the second pump head 31 each comprising a set of guide assemblies, a coupling assembly movably connected in the guide assembly The linkage module and the plunger connecting assembly are arranged at the end of the guide assembly; one end of the linkage module rests on the corresponding cam member 7, and the two cam members 7 respectively drive the corresponding linkage module to move in the guide assembly, and the other end of the linkage module is equipped with a plunger connecting assembly, which is used to drive the plunger connecting assembly to move on the corresponding hydraulic end assembly; the hydraulic end assembly includes a hydraulic chamber 60 filled with hydraulic oil, a medium chamber 61 for conveying fluid, and a diaphragm 27 installed between the hydraulic chamber 60 and the medium chamber 61; when the plunger connecting assembly enters the hydraulic chamber 60, the hydraulic oil is compressed and the medium chamber 61 discharges the fluid; when the plunger connecting assembly moves out of the hydraulic chamber 60, the hydraulic oil expands and the medium chamber 61 inhales the fluid.

[0032] See also Figure 1-Figure 3In this embodiment, a flat key 9 is provided on the camshaft 19, and a keyway adapted to the flat key 9 is provided on each of the two cam members 7. The two cam members 7 are limited by the flat key 9 and the keyway with the camshaft 19. The axes of the two cam members 7 are concentric, and the camshaft 19 drives the two cam members 7 to rotate at the same preset angular velocity; the shoulder of the camshaft 19 abuts against the side end surface of the cam member 7 and is used to prevent the cam member 7 from axial movement. The outer contour surface of the cam member 7 has a high hardness coating, and the contact surface of the cam member 7 and the flat push rod 18 adopts a surface treatment process with high hardness and low friction coefficient (such as nitriding, chrome plating or ceramic coating) to reduce wear and extend service life; the linkage module includes a movable The flat-bottom push rod 18 in the guide assembly and the compression spring 108 installed on the flat-bottom push rod 18 are dynamically connected. The flat bottom surface of the flat-bottom push rod 18 is in close contact with the outer contour surface of the cam member 7. One end of the compression spring 108 rests on the flat bottom surface of the flat-bottom push rod 18, and the other end rests on the guide assembly; an elastic cylindrical pin 17 is installed on the flat-bottom push rod 18, and both ends of the elastic cylindrical pin 17 protrude beyond the shaft diameter of the flat-bottom push rod 18. A groove is provided at the head end of the guide assembly, and the elastic cylindrical pin 17 is embedded in the groove; the camshaft 19 and the output end of the motor can be connected through a coupling (in actual application, a worm gear structure can also be adopted as a power transmission component between the camshaft 19 and the motor, through The built-in reduction transmission function is realized through the engagement of the worm and the worm wheel), and the flat key 9 and keyway design are used to limit the vertically installed camshaft 19 and the cam member 7, so that the axes of the two cam members 7 are concentric (it is worth noting that the position of the camshaft 19 relative to the cam member 7 is deviated from its center), and are perpendicular to the bottom surface of the body 1 and rotate at the same angular velocity (in actual application, the lower bottom surface of the shoulder of the camshaft 19 is against the upper end surface of the cam member 7 to prevent axial movement of the cam member 7). The flat-bottom push rod 18 can be placed horizontally (perpendicular to the camshaft 19), and a compression spring 108 is installed on it. One end of the compression spring 108 is against the flat-bottom push rod 18. One end of the flat bottom step is against the inner end surface of the guide assembly, so as to ensure that the outer contour surface of the cam member 7 and the flat bottom surface of the flat bottom push rod 18 (according to this embodiment, the end cover 11 is installed on the flat bottom surface of the flat bottom push rod 18, and the end cover 11 can also be made to be in close contact with the outer contour surface of the cam member 7) at all times, thereby realizing the force sealing function of the cam mechanism (the force transmission component composed of the cam member 7 and the flat bottom push rod 18) (pre-tightening and sealing are achieved by the elastic force of the compression spring 108), and the elastic cylindrical pin 17 installed on the flat bottom push rod 18 (the two ends of the cylindrical pin protrude out of the axial diameter of the flat bottom push rod 18) is inserted into the groove at the first end (the end close to the body 1) of the guide assembly to form a limit.

[0033] See also Figure 1In this embodiment, the guide assembly includes a slide 102 fixedly connected to the body 1 by a first hexagon socket screw 103 and a guide sleeve 107 fixedly connected to the slide 102. The guide sleeve 107 is connected to the slide 102 by a second hexagon socket screw 109. The flat-bottom push rod 18 moves along the axial direction of the slide 102. The slide 102 is provided with a plurality of axial oil guide holes 40. The axial oil guide holes 40 adopt a multi-stage diversion structure (such as a tapered aperture or a spiral groove). Combined with the polishing treatment of the inner wall of the guide sleeve 107, it ensures that the lubricating oil flows evenly and covers the flat-bottom push rod 18. Surface; A connector 104 is installed between the slide 102 and the plunger connecting assembly, and a cavity structure is provided in the connector 104. The lubricating oil flows from the guide assembly to the hydraulic end assembly and the plunger connecting assembly through the cavity structure. The cam drives the flat-bottom push rod 18 to move back and forth in the guide sleeve 107; The plunger connecting assembly includes a plunger member 2 movably connected to the hydraulic end assembly, one end of the plunger member 2 is connected to the flat-bottom push rod 18 through an assembly connector, and the flat-bottom push rod 18 drives the plunger member 2 to reciprocate linearly in the hydraulic cavity through the assembly connector; The assembly connector includes a cap screw tightened on the flat-bottom push rod 18 The nut 335, the threaded sleeve 336 tightened on the piston member, the flat washer 334 set between the plunger member 2 and the cap nut 335, the threaded sleeve 336 is connected to the cap nut 335, and is fixed by a hexagonal nut 337. A liquid cylinder body 431 is provided on the guide assembly. The inner hole of the liquid cylinder body 431 is used to seal the outer circumferential surface of the plunger member 2. A wave spring gasket can be set between the threaded sleeve 336 and the cap nut 335 to compensate for the slight gap of the thread fit, ensure the coaxiality of the crosshead and the plunger member 2, and reduce eccentric wear; the slideway 102 can be connected to the body by bolts 1, the guide sleeve 107 is completely fixed to the slideway 102 by means of a hexagon socket screw (other bolt connectors may be used in actual applications). The inner hole of the guide sleeve 107 and the outer axial surface of the flat-bottom push rod 18 are clearance-fitted. The internal cavity of the connector 104 (which can be regarded as a connecting kit between the hydraulic cylinder body 431 and the slideway 102, with its two ends respectively adapted to the end surfaces of the hydraulic cylinder body 431 and the slideway 102) also serves as an oil guide passage for lubricating oil to flow from the guide assembly to the hydraulic end and the plunger assembly. In this way, a structure is achieved in which the flat-bottom push rod 18 drives the plunger assembly 2 to perform reciprocating linear motion through the assembled connector.

[0034] See also Figures 1-4In this embodiment, a pump suction port 36 is provided at one end of the hydraulic end assembly, and a pump discharge port 37 is provided at the other end. A suction check valve 32 is installed on the pump suction port 36, and a discharge check valve 33 is installed on the pump discharge port 37. The pump suction port 36 of the first pump head 30 and the pump suction port 36 of the second pump head 31 are connected to form a common suction manifold 38 through a set of pipes (suction pipe 34), and the pump discharge port 37 of the first pump head 30 and the pump discharge port 37 of the second pump head 31 are connected to form a common discharge manifold 39 through a set of pipes (discharge pipe 35). In actual application, the pump close to the motor side is used as the first pump head 30, and the other pump is used as the second pump head 31. The first pump head 30 and the second pump head 31 themselves have a hydraulic end assembly. (Hydraulic chamber 60, medium chamber 61 and diaphragm 27), the hydraulic chamber 60 and the medium chamber 61 are separated by the diaphragm 27, and when the plunger 2 is driven by the flat-bottom push rod 18 to enter or move out of the corresponding hydraulic chamber 60, a hydraulic action is generated to change the hydraulic oil volume of the hydraulic chamber 60 (as mentioned above, the connector 104 seals the outer circumferential surface of the plunger 2, thereby avoiding leakage of the hydraulic oil in the hydraulic chamber 60 due to the reciprocating motion of the plunger 2, and maintaining the hydraulic volume in the hydraulic chamber 60 within a stable range), the diaphragm 27 between the medium chamber 61 and the hydraulic chamber 60 is driven to reciprocate through the hydraulic principle, and is transmitted to the medium chamber 61 through the diaphragm 27 to realize the discharge or inflow of the fluid, thereby ensuring the pulsation-free metering and transportation of the medium.

[0035] Working principle: The camshaft 19 is driven by a motor, so that the camshaft 19 drives the cam member 7 to rotate synchronously under the design of a predetermined reduction ratio, and then pushes or pulls back the flat-bottom push rod 18 with the help of the compression spring 108, and then drives the plunger member 2, so that the two plungers 2 in the first pump head 30 and the second pump head 31 reciprocate in their respective hydraulic chambers 60 with a phase difference of 180°, thereby compressing the hydraulic oil volume and pushing the diaphragm 27 to move, so that the conveying medium in the medium chamber 61 is discharged alternately through the discharge check valve 33 to the common discharge manifold 39 with the same 180° phase difference. In this way, after superposition in the common discharge manifold 39, pulsation-free conveying and metering of the medium can be achieved.

[0036] The operating principle of the pulsation-free metering pump of the present invention will be further described below by referring to the changes in the movement pattern of the plunger 2, i.e., the displacement and speed of the plunger 2, and combining the pressure changes in the hydraulic chamber 60.

[0037] First, consider that hydraulic oil is stored in the hydraulic chamber 60 and that the reciprocating motion of the diaphragm between the medium chamber 61 and the hydraulic chamber 60 is driven by the hydraulic principle. That is, the cam member 7 drives the flat-bottomed push rod 18, and the flat-bottomed push rod 18 drives the reciprocating motion of the plunger member 2 in the hydraulic chamber 60, thereby driving the reciprocating motion of the diaphragm 27 between the medium chamber 61 and the hydraulic chamber 60. By compressing or expanding the hydraulic oil, the volume of the hydraulic oil is changed, thereby achieving the delivery and suction of fluid in the medium chamber 61 (the change in the volume of the hydraulic oil will cause the pressure in the hydraulic chamber 60 to change, and will also be transmitted through the diaphragm 27 to the medium chamber 61 to discharge the fluid; or the pressure in the suction line 34 is transmitted to the diaphragm 27 to further complete the suction of the medium). Therefore, the stroke of the plunger member 2 during one rotation of the cam member 7 can be divided into four parts: compression stroke, discharge stroke, expansion stroke, and suction stroke. The movement of the plunger member 2 will repeat these four strokes in each rotation cycle of the cam member 7.

[0038] like Figure 5 As shown, the thick solid line A represents the speed of the plunger 2 of the first pump head 30 when the rotation angle of the cam member 7 is β, and the rotation angle of the cam member 7 is also the rotation angle of the camshaft 19; the thin dotted line B represents the speed of the plunger 2 of the second pump head 31.

[0039] Among them, the displacement of the plunger 2 when it is in the compression stroke direction is positive, and similarly the speed is also positive. At the same time, because the plunger 2 still moves in the same direction during the subsequent discharge stroke, Figure 5 The speed of the middle plunger 2 is still positive, and at the end position of the discharge stroke, the stroke of the plunger 2 reaches the maximum value (hereinafter referred to as the front dead center); on the contrary, during the expansion stroke and the suction stroke, the movement direction of the plunger 2 is opposite, and the cam member 7 also rotates to the return angle, so the speed of the plunger 2 at this time is negative, that is, the plunger 2 retreats to the starting position (hereinafter referred to as the back dead center) in the direction away from the diaphragm 27 (leaving the hydraulic chamber 60). This is also the process of sucking fluid into the medium chamber 61 (it is worth noting that the hydraulic chamber Air bubbles are inevitably present in the hydraulic chamber 60 and the medium chamber 61. Considering that both the hydraulic oil and the fluid are compressible, the plunger 2 always begins its compression stroke when it starts moving from the rear dead center position: after the cam 7 pushes the flat-bottomed push rod 18, which drives the plunger 2 to move slightly toward the diaphragm 27, the plunger 2 compresses the hydraulic oil, causing the pressure in the hydraulic chamber 60 to rise rapidly. As the hydraulic oil in the hydraulic chamber 60 is compressed, the air bubbles therein are either discharged through the exhaust valve 29 provided on the pump head or burst by the increased pressure.

[0040] like Figure 5As shown by the thick solid line A, when the cam member 7 rotates at an angle β0-β10, the first pump head 30 is in the compression stroke; when the cam member 7 rotates at an angle β10-β2, it is in the discharge stroke; when the cam member 7 rotates at an angle β2-β0 (the above are all based on Figure 5 The X-axis extension direction mark) is in the expansion stroke and the suction stroke respectively;

[0041] Another example Figure 5 As shown by the thin dotted line B, when the rotation angle of the cam member 7 is between β0 and β11, the second pump head 31 is in the discharge stroke, when the rotation angle is between β11 and β12, it is in the suction stroke, when the rotation angle is between β12 and β13, it is in the compression stroke, and when the rotation angle is between β13 and β0 (the above are all based on Figure 5 X-axis extension direction mark), in the discharge stroke.

[0042] In summary, because there is a 180° phase difference in the rotation angles of the two cam parts 7 on the second pump head 31 and the first pump head 30, the two pump heads independently and repeatedly perform compression stroke, discharge stroke, expansion stroke, and suction stroke within the 360° rotation angle range of their respective cam parts 7.

[0043] like Figure 5 As shown by the thick solid line A, for the first pump head 30, during the compression stroke of the cam member 7 with a rotation angle of β0-β10, the specially designed outer contour surface of the cam member 7 (including the special structure and special material design mentioned above) drives the flat-bottom push rod 18 to move according to a predetermined motion pattern, further driving the plunger member 2 to maintain the same motion characteristics and move toward the diaphragm 27. When the rotation angle reaches β10, the compression stroke ends and the first pump head 30 enters the discharge stroke. At this time, the displacement process of the plunger member 2 is as follows: Figure 6 As shown by the rotation angle β0-β10 in the thick solid line A; when the rotation angle starts from β10, the plunger 2 continues to move toward the diaphragm 27 and pushes the diaphragm 27 forward, starting the fluid discharge process of the first pump head 30. At this time, the hydraulic oil in the hydraulic chamber 60 and the fluid in the medium chamber 61 have been compressed, and the bubbles therein have been squeezed out (or the bubbles in the hydraulic chamber 60 have been discharged through the exhaust valve 29). At this time, the pressure in the hydraulic chamber 60 is equal to the pressure in the medium chamber 61, and is equal to the discharge pressure of the common discharge manifold 39.

[0044] Similarly, if Figure 5As shown by the thin dotted line B in the figure, the speed of the plunger 2 and its corresponding discharge flow rate begin to decrease from the rotation angle β10 of the second pump head 31. Therefore, considering the instantaneous motion characteristics and corresponding flow rate performance of the first pump head 30 and the second pump head 31, the discharge flow rate of the first pump head 30, which increases from the rotation angle β10, will offset the discharge flow rate of the second pump head 31, which decreases from the rotation angle β10, thereby maintaining the superimposed discharge flow rate in the common discharge manifold 39 within a constant range. At the same time, the common discharge manifold 39 also maintains a constant discharge pressure. Next, at the rotation angle β10-β2, the speed of the plunger 2 of the first pump head 30 maintains a uniform acceleration-uniform speed-uniform deceleration motion state in sequence, and its motion direction is always toward the diaphragm 27, pushing the diaphragm 27 forward all the time, that is, the first pump head 30 is in the discharge stroke. When the rotation angle is β2, the plunger 2 moves to the front dead center position mentioned above, which is the maximum discharge stroke of the first pump head 30.

[0045] when Figure 5 The thick solid line A shows that when the rotation angle of the cam member 7 is β2, the speed of the plunger member 2 of the first pump head 30 begins to become negative, indicating that the plunger member 2 begins to move away from the diaphragm 27, that is, the first pump head 30 enters the expansion stroke. At this time, the pressure in the hydraulic chamber 60 begins to decrease. After a short period of time, the pressure in the hydraulic chamber 60 decreases from the discharge pressure to the suction pressure. At this time, the expansion stroke ends and the plunger member 2 enters the suction stroke. At this time, the speed of the plunger member 2 maintains a uniform acceleration-uniform speed-uniform deceleration motion state in sequence, and moves in the direction away from the hydraulic chamber 60. The diaphragm 27 It also continues to move in the direction of the plunger 2 retreating; after a period of time, the hydraulic chamber 60 becomes negative pressure, and the fluid medium begins to enter the medium chamber 61 through the suction pipe 34. During this period, the plunger 2 always moves in the direction away from the diaphragm 27, and the suction stroke ends when the cam member 7 rotates at an angle of β0. After that, the process is the same as described above. The cam member 7 continues the next rotation cycle from β0, and the first pump head 30 will start the compression stroke, discharge stroke, expansion stroke and suction stroke again until the rotation angle is β0 again. In this way, the entire four-stroke process will be repeated continuously.

[0046] Because the rotation angle of the cam member 7 of the second pump head 31 is exactly 180° away from the rotation angle of the cam member 7 of the first pump head 30, Figure 5 and Figure 6 As shown by the thick solid line A and the thin dot-dash line B in FIG, the movement speed and displacement of the plunger 2 of the second pump head 31 and the plunger 2 of the first pump head 30 are also staggered by 180 degrees. The stroke of the plunger 2 of the second pump head 31 is also between the front dead center and the rear dead center, and the rotation angle of the cam member 7 corresponding to the front dead center is Figure 5 β12 in the figure, the rotation angle of the cam member 7 corresponding to the rear dead center is Figure 5Therefore, the plunger 2 of the second pump head 31 will reciprocate simultaneously with the plunger 2 of the first pump head 30 with a rotation angle lagging by 180°, and the pressure in its hydraulic chamber 60 will also change accordingly, and the pressure change pattern is the same as that of the first pump head 30 in the compression stroke, discharge stroke, expansion stroke and suction stroke.

[0047] like Figure 5 As shown, at the rotation angle β10, the compression stroke of the first pump head 30 ends. At this time, the pressure in the hydraulic chamber 60 of the first pump head 30 is equal to the pressure in the medium chamber 61, and is equal to the pressure in the common discharge manifold 39. At this time, the first pump head 30 begins the discharge stroke, and the fluid immediately enters the common discharge manifold 39. The second pump head 31 is at the end of the discharge stroke at this rotation angle β10, as shown in FIG. Figure 5 As shown, the increased discharge flow of the first pump head 30 is just eliminated by the reduced discharge flow of the second pump head 31, so the superimposed flow curve is as follows: Figure 5 As shown by the dotted line in , the flow rate is always constant. Similarly, the pressure pulsation of the common discharge manifold 39 is also eliminated.

[0048] In this embodiment, the phase difference between the two unit pumps is 180° for illustration. In actual applications, the phase difference can also be set to other angle values. The key point is to ensure that the rising section of the speed curve of the plunger 2 of the first pump head 30 and the falling section of the speed curve of the plunger 2 of the second pump head 31 always cancel each other out within the same rotation angle, so that the superimposed speed is a constant value and equal to the speed value of the uniform speed section when the speed does not change. Similarly, the present invention can also evolve into the case where the speed of the plunger 2 is not set to zero at the end of the compression stroke; or the speed of the plunger 2 is set to zero at the end of the expansion stroke.

Claims

1. A dual-unit pulsation-free metering pump, characterized in that: The invention comprises a first pump head (30), a second pump head (31), and a transmission end assembly shared by the first pump head (30) and the second pump head (31), wherein the transmission end assembly comprises a body (1), a camshaft (19) movably connected in the body (1), and a cam member (7) mounted on the camshaft (19), wherein the rotation angles of the two cam members (7) have a phase difference of 180°, a reduction motor is mounted on the body (1), an output end of the reduction motor is connected to one end of the camshaft (19), the reduction motor is used to drive the camshaft (19) to rotate, and the camshaft (19) is used to drive the two cam members (7) to rotate while maintaining a rotation angle of 180° phase difference; The first pump head (30) and the second pump head (31) each include a guide assembly, a linkage module and a plunger connection assembly movably connected in the guide assembly, and a hydraulic end assembly installed at the end of the guide assembly; One end of the linkage module abuts against the corresponding cam member (7), and the two cam members (7) respectively drive the corresponding linkage module to move in the guide assembly. The other end of the linkage module is equipped with a plunger connection assembly, and the linkage module is used to drive the plunger connection assembly to move on the corresponding hydraulic end assembly. The hydraulic end assembly includes a hydraulic chamber (60) filled with hydraulic oil, a medium chamber (61) for conveying fluid, and a diaphragm (27) installed between the hydraulic chamber (60) and the medium chamber (61); When the plunger connecting assembly enters the hydraulic chamber (60), the hydraulic oil is compressed and the medium chamber (61) discharges the fluid; When the plunger connecting assembly moves out of the hydraulic chamber (60), the hydraulic oil expands and the medium chamber (61) draws in the fluid; A flat key (9) is provided on the camshaft (19), and a keyway adapted to the flat key (9) is provided on each of the two cam members (7). The two cam members (7) are limited by the flat key (9) and the keyway with the camshaft (19). The axes of the two cam members (7) are concentric, and the camshaft (19) drives the two cam members (7) to rotate at the same preset angular velocity. The shoulder of the camshaft (19) abuts against the side end surface of the cam member (7) and is used to prevent the cam member (7) from axial movement. The outer contour surface of the cam member (7) has a high hardness coating; The linkage module includes a flat bottom push rod (18) movably connected to the guide assembly and a compression spring (108) mounted on the flat bottom push rod (18), the flat bottom surface of the flat bottom push rod (18) is in close contact with the outer contour surface of the cam member (7), one end of the compression spring (108) rests on the flat bottom surface of the flat bottom push rod (18), and the other end rests on the guide assembly; An elastic cylindrical pin (17) is mounted on the flat-bottom push rod (18), and both ends of the elastic cylindrical pin (17) protrude outside the shaft diameter of the flat-bottom push rod (18). A groove is provided at the head end of the guide assembly, and the elastic cylindrical pin (17) is embedded in the groove; The guide assembly includes a slideway (102) fixedly connected to the body (1) via a first hexagon socket screw (103) and a guide sleeve (107) fixedly connected to the slideway (102). The guide sleeve (107) is connected to the slideway (102) via a second hexagon socket screw (109). The flat-bottom push rod (18) moves along the axial direction of the slideway (102). The slideway (102) is provided with a plurality of axial oil guide holes (40). A connector (104) is installed between the slideway (102) and the plunger connecting assembly. A cavity structure is provided in the connector (104). Lubricating oil flows from the guide assembly to the hydraulic end assembly and the plunger connecting assembly through the cavity structure. The cam drives the flat-bottom push rod (18) to move back and forth in the guide sleeve (107).

2. A dual-unit pulsation-free metering pump according to claim 1, characterized in that: The plunger connection assembly comprises a plunger member (2) movably connected to the hydraulic end assembly, one end of the plunger member (2) is connected to a flat-bottom push rod (18) via an assembly connection member, and the flat-bottom push rod (18) drives the plunger member (2) to reciprocate linearly in the hydraulic chamber via the assembly connection member.

3. A dual-unit pulsation-free metering pump according to claim 2, characterized in that: The assembly connection includes a cap nut (335) tightened on the flat-bottom push rod (18), a threaded pressing sleeve (336) tightened on the piston member, and a flat washer (334) arranged between the plunger member (2) and the cap nut (335). The threaded pressing sleeve (336) is connected to the cap nut (335) and is fixed by a hexagonal nut (337). A liquid cylinder body (431) is provided on the guide assembly. The inner hole of the liquid cylinder body (431) is used to seal the outer circumferential surface of the plunger member (2).

4. A dual-unit pulsation-free metering pump according to claim 3, characterized in that: A pump suction port (36) is provided at one end of the hydraulic end assembly, and a pump discharge port (37) is provided at the other end. A suction check valve (32) is installed on the pump suction port (36), and a discharge check valve (33) is installed on the pump discharge port (37). The pump suction port (36) of the first pump head (30) and the pump suction port (36) of the second pump head (31) are connected through a set of pipes to form a common suction manifold (38), and the pump discharge port (37) of the first pump head (30) and the pump discharge port (37) of the second pump head (31) are connected through a set of pipes to form a common discharge manifold (39).

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