Double-unit pulseless metering pump

Abstract

The invention relates to the field of metering pumps, in particular to a double-unit pulseless metering pump which comprises a first pump head, a second pump head and a transmission end assembly shared by the first pump head and the second pump head, and the transmission end assembly comprises a machine body, a cam shaft movably connected into the machine body and a cam piece installed on the cam shaft. The rotation angles of the two cam parts have the 180-degree phase difference, a gear motor is installed on the machine body, the output end of the gear motor is connected with one end of a cam shaft, the gear motor is used for driving the cam shaft to rotate, and the cam shaft is used for driving the two cam parts to rotate by keeping the rotation angle with the 180-degree phase difference. According to the metering pump, only double pump heads are used, namely only two pump heads are needed, the structure is simple, the number of parts such as the fluid end of the metering pump with the high failure rate is greatly reduced, use and loss of valve assembly quick-wear parts of the pump heads are reduced, and therefore the production, manufacturing and using cost is reduced, and economic benefits of customers are improved.

Description

Technical Field

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

[0002] A metering pump is a positive-displacement reciprocating pump that can meter and transport liquids, and is indispensable in many industrial fields. However, limited by the basic structure and working principle of the positive-displacement reciprocating pump, its power end generally still features a traditional crank-link mechanism, resulting in relatively fixed motion and power characteristics, which are manifested as inevitable flow and pressure pulsations in the medium it transports.

[0003] However, with the application of continuous flow micro-reaction technology and its technical advantages, such pulsation problems need to be solved urgently. Because this process technology has extremely strict requirements for flow pulsation. Although metering pumps with traditional structures have the characteristics of adjustable flow rate and accurate metering, they generally produce pulsating flow, which will cause instability of the fluid in the micro-reactor of the micro-reaction technology, thus greatly affecting the realization of the process or the stability of the quality of the finished product.

[0004] Although there are currently traditional means to solve the flow pulsation problem, such as using a buffer tank to suppress flow pulsation; or adopting a structure with three pumps in parallel, that is, through the superposition of instantaneous flows, so that the transported flow rate is relatively stable; or adopting design schemes such as reducing the medium flow velocity and selecting a larger pump model or increasing the size of the transport pipeline. Although the above can achieve certain technical effects, they also increase the procurement cost of the technical solution and the subsequent on-site operation and maintenance investment, etc. Summary of the Invention

[0005] In order to overcome the problem that traditional metering pumps generate flow pulsations, resulting in instability of the fluid in the micro-reactor.

[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 phase difference of 180°, 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 inhales 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 matched with 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 with 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 abuts 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-bottomed 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 member, 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 outside the axial diameter of the flat-bottom push rod. The head end of the guide assembly is provided with a groove, and the elastic cylindrical pin is embedded in the groove.

[0011] Preferably, the guide assembly includes a slideway fixedly connected to the body by a first hexagon socket screw and a guide sleeve fixedly connected to the slideway, the guide sleeve is connected to the slideway by a second hexagon socket screw, the flat-bottom push rod moves along the axial direction of the slideway, a plurality of axial oil guide holes are opened on the slideway, 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 arranged in the connector. 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 reciprocate 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, and the flat-bottom push rod drives the plunger member to reciprocate linearly in the hydraulic chamber through the assembly connection.

[0014] Preferably, the assembly connecting parts include 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 cylinder body is arranged on the guide assembly. The inner hole of the 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 inlet is provided at one end of the hydraulic end assembly, and a pump discharge outlet is provided at the other end, a suction check valve is installed on the pump suction inlet, and a discharge check valve is installed on the pump discharge outlet; the pump suction inlet of the first pump head and the pump suction inlet of the second pump head are connected by a set of pipes to form a common suction manifold, and the pump discharge outlet of the first pump head and the pump discharge outlet of the second pump head are connected by a set of pipes to form a common discharge manifold.

[0016] Beneficial effects of the present invention: 1. Only two pump heads are used, 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 the 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; 2. By utilizing a specially designed motion law and implementing it through the working surface of the outer contour of the cam part, the sinusoidal curve of the reciprocating motion is transformed into a linear velocity curve of uniform acceleration-uniform velocity-uniform deceleration, eliminating the flow rate and pressure pulsations in essence from the motion characteristics. 3. There is no need to additionally use an air damper to absorb and eliminate pulsations, greatly reducing the additional costs and operation and maintenance inputs. 4. The cam mechanism adopts the structure of a disk cam with a flat-bottomed push rod in direct-acting centricity, rather than the structure of a roller cam, making the pressure angle of the cam mechanism zero, thus improving the force-bearing condition of the transmission mechanism. 5. It is easier to form an oil film between the contact surfaces of the cam part and the flat-bottomed push rod, thus ensuring the lubrication between this friction pair, reducing the wear between high-pair parts, and increasing the service life of the core parts. 6. By adopting a cam mechanism in the form of force closure and combining a compression spring with specially designed high fatigue strength, the overall size of the cam mechanism is reduced, the structural layout is compact, and the space occupied by the equipment is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Shown is the first structural schematic diagram of the dual-unit non-pulsating metering pump of the present invention; Figure 2 Shown is the second structural schematic diagram of the dual-unit non-pulsating metering pump of the present invention; Figure 3 Shown is the third structural schematic diagram of the dual-unit non-pulsating metering pump of the present invention; Figure 4 Shown is the schematic diagram of the medium delivery system of the dual-unit non-pulsating metering pump of the present invention; Figure 5 Shown is the linear diagram of the cam rotation angle and the plunger part speed of the present invention; Figure 6 Shown is the linear diagram of the cam rotation angle and the displacement of the plunger part of the present invention.

[0018] Description of the reference numerals: 1, body; 7, cam member; 9, flat key; 11, end cover; 17, elastic cylindrical pin; 18, flat 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 screw Angle nut; 431, 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 pipeline; 35, discharge pipeline; 36, pump suction port; 37, pump discharge port; 38, common suction manifold; 39, common discharge manifold; 40, axial oil guide hole. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] 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°, 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, the camshaft 19 being 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 comprising a set of guide assemblies, a coupling assemblies movably connected in the guide assemblies The linkage module comprises a driving module and a plunger connecting 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, and the other end of the linkage module is installed with a plunger connecting assembly, and the linkage module 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.

[0021] See also Figures 1-3, in 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 respect to 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 shaft shoulder of the camshaft 19 abuts against the side end face of the cam member 7 and is used to prevent the axial movement of the cam member 7. The outer contour surface of the cam member 7 has a high-hardness coating. The contact surface between the cam member 7 and the flat-bottom 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 the service life; the linkage module includes a flat-bottom push rod 18 movably connected in the guiding 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 abuts against the flat bottom surface of the flat-bottom push rod 18, and the other end abuts against the guiding assembly; an elastic dowel pin 17 is mounted on the flat-bottom push rod 18. Both ends of the elastic dowel pin 17 protrude outside the shaft diameter of the flat-bottom push rod 18. A groove is provided at the head end of the guiding assembly, and the elastic dowel pin 17 is embedded in the groove; the output end of the camshaft 19 and the motor can be connected by a coupling (in practical applications, a worm and worm gear structure can also be used as the power transmission component between the camshaft 19 and the motor to achieve the function of built-in speed reduction transmission through the meshing of the worm and the worm gear). By using the design of the flat key 9 and the keyway, the vertically installed camshaft 19 is limited with respect to the cam member 7, so that the axes of the two cam members 7 are concentric (it should be noted that the position of the camshaft 19 relative to the cam member 7 is offset from the center to one side), and is perpendicular to the bottom surface of the body 1 and rotates at the same angular velocity (in practical applications, the lower bottom surface of the shaft shoulder of the camshaft 19 abuts against the upper end surface of the cam member 7 to prevent the axial movement of the cam member 7). The flat-bottom push rod 18 can be horizontally placed (perpendicular to the camshaft 19), and a compression spring 108 is mounted thereon. One end of the compression spring 108 abuts against one side of the flat bottom surface step of the flat-bottom push rod 18, and the other end abuts against the inner end surface of the guiding assembly. In this way, it can be ensured that the outer contour surface of the cam member 7 and the flat bottom surface of the flat-bottom push rod 18 (in accordance with this embodiment, an end cover 11 is mounted on the flat bottom surface of the flat-bottom push rod 18, and the end cover 11 can also be in close contact with the outer contour surface of the cam member 7) always remain in close contact to realize the force-closure function of the cam mechanism (the force-transmitting assembly composed of the cam member 7 and the flat-bottom push rod 18) (realize pre-tightening closure through the elastic force of the compression spring 108). The elastic dowel pin 17 (both ends of the pin protrude outside the shaft diameter of the flat-bottom push rod 18) mounted on the flat-bottom push rod 18 is inserted into the groove at the head end (the end close to the body 1) of the guiding assembly to form a limit.

[0022] Please refer to Figure 1In this embodiment, the guide assembly includes a slideway 102 fixedly connected to the body 1 by 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 by a second hexagon socket screw 109. The flat-bottom push rod 18 moves along the axial direction of the slideway 102. A plurality of axial oil guide holes 40 are provided on the slideway 102. The axial oil guide holes 40 adopt a multi-stage flow distribution structure (such as a tapered aperture or a spiral groove), combined with the polishing treatment of the inner wall of the guide sleeve 107, to ensure 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 connection assembly, and a cavity structure is arranged inside the connector 104. Lubricating oil flows from the guide assembly to the hydraulic end assembly and the plunger connection assembly through the cavity structure, and the cam drives the flat-bottom push rod 18 to reciprocate in the guide sleeve 107; the plunger connection 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 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 the hexagonal nut 337. The guide assembly is provided with a cylinder body 431, the inner hole of the cylinder body 431 is used to seal the outer circumferential surface of the plunger member 2, and a wave spring gasket can be set between the threaded sleeve 336 and the cap nut 335 to compensate for the small 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 hexagon socket screws (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-matched, and the inner cavity of the connecting body 104 (which can be regarded as a connecting kit between the liquid cylinder body 431 and the slideway 102, and its two ends are respectively adapted to the end faces of the liquid cylinder body 431 and the slideway 102) also serves as an oil guide passage for the lubricating oil to flow from the guide assembly to the hydraulic end and the plunger assembly, so that the flat-bottom push rod 18 drives the plunger assembly 2 to perform reciprocating linear motion together through the assembled connecting piece.

[0023] See also Figures 1-4, in this embodiment, one end of the hydraulic end assembly is provided with a pump suction port 36, and the other end is provided with a pump discharge port 37. An inhalation 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 ports 36 of the first pump head 30 and the second pump head 31 are connected and aggregated into a common suction manifold 38 through a set of pipelines (suction pipeline 34), and the pump discharge ports 37 of the first pump head 30 and the second pump head 31 are connected and aggregated into a common discharge manifold 39 through a set of pipelines (discharge pipeline 35); in actual application, the pump closer 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. When the plunger 2 is driven by the flat-bottom push rod 18 to penetrate into or move out of the corresponding hydraulic chamber 60, a hydraulic action is generated, changing the hydraulic oil volume in the hydraulic chamber 60 (as described above, the connecting body 104 seals the outer circumferential surface of the plunger 2, avoiding the leakage of the hydraulic oil in the hydraulic chamber 60 due to the reciprocating movement of the plunger 2 and maintaining the hydraulic volume in the hydraulic chamber 60 within a stable range). Through the hydraulic principle, the diaphragm 27 between the medium chamber 61 and the hydraulic chamber 60 is driven to reciprocate. Through the diaphragm 27, it is conducted to the medium chamber 61 to realize the discharge or inflow of the fluid, thus ensuring the pulsation-free metering and conveying of the medium.

[0024] Working principle: The motor drives the camshaft 19, 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 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 180° phase difference, thereby compressing the hydraulic oil volume and driving the diaphragm 27 to move, so that the conveying medium in the medium chamber 61 is alternately discharged to the common discharge manifold 39 through the discharge check valve 33 with the same 180° phase difference. In this way, after being superimposed in the common discharge manifold 39, the pulsation-free conveying and metering of the medium can be realized.

[0025] Next, through the change of the movement law of the plunger 2, that is, the displacement and speed of the plunger 2, and combined with the pressure change in the hydraulic chamber 60, the operating principle of the pulsation-free metering pump of the present invention will be further specifically described: First, consider that there is hydraulic oil in the hydraulic chamber 60, and the diaphragm between the medium chamber 61 and the hydraulic chamber 60 reciprocates 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 movement of the plunger member 2 in the hydraulic chamber 60 to form a hydraulic principle to drive the diaphragm 27 between the medium chamber 61 and the hydraulic chamber 60 to reciprocate. By compressing or expanding the hydraulic oil, the volume of the hydraulic oil is changed, and then the transportation and inhalation of the fluid in the medium chamber 61 are realized (the change in the volume of the hydraulic oil will cause a change in the pressure in the hydraulic chamber 60, and at the same time, it will be transmitted to the medium chamber 61 through the diaphragm 27 to realize the discharge of the fluid; or the pressure in the suction pipeline 34 will be transmitted to the diaphragm 27 and further complete the inhalation of the medium). Therefore, the stroke of the plunger member 2 when the cam member 7 rotates one circle is divided into four parts: compression stroke, discharge stroke, expansion stroke, and inhalation stroke. And in each rotation cycle of the cam member 7, the movement of the plunger member 2 will sequentially repeat these four strokes.

[0026] As Figure 5 shown, the thick solid line A represents the speed of the plunger member 2 of the first pump head 30 when the rotation angle of the cam member 7 is β. 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 member 2 of the second pump head 31.

[0027] Among them, when the displacement of the plunger member 2 in the direction of the compression stroke is taken as positive, similarly, the speed is also positive. At the same time, because during the subsequent discharge stroke, the plunger member 2 still moves in the same direction, so at this time Figure 5 the speed of the plunger member 2 in it is still positive, and at the end position of the discharge stroke, the stroke of the plunger member 2 reaches the maximum value (hereinafter referred to as this position: the front dead center); on the contrary, during the expansion stroke and the inhalation stroke, the movement direction of the plunger member 2 is opposite, and the cam member 7 also rotates to the return angle, so the speed of the plunger member 2 at this time is negative, that is, the plunger member 2 retreats to the starting position in the direction away from the diaphragm 27 (leaving the hydraulic chamber 60) (hereinafter referred to as this position: the rear dead center). At this time, it is also the process of inhaling fluid in the medium chamber 61 (it should be noted that: there will inevitably be bubbles in the hydraulic chamber 60 and the medium chamber 61. At the same time, considering that both the hydraulic oil and the fluid are compressible, so when the plunger member 2 starts to move from the rear dead center position, it always starts with the compression stroke first: after the cam member 7 pushes the flat-bottomed push rod 18, the flat-bottomed push rod 18 drives the plunger member 2 to move slightly in the direction close to the diaphragm 27, and then by compressing the hydraulic oil by the plunger member 2, the pressure in the hydraulic chamber 60 will rise rapidly, the hydraulic oil in the hydraulic chamber 60 is compressed, and at the same time, the bubbles in it are either discharged through the exhaust valve 29 provided on the pump head or have been burst by the increased pressure). As Figure 5As shown by the thick solid line A, between the rotation angles β0-β10 of the cam member 7, the first pump head 30 is in the above-mentioned compression stroke; between the rotation angles β10-β2, it is in the discharge stroke; between the rotation angles β2-β0 (all of the above are marked in the Figure 5 extension direction of the X-axis in), it is successively in the expansion stroke and the suction stroke; For another example, Figure 5 as shown by the thin dotted line B in, between the rotation angles β0-β11 of the cam member 7, the second pump head 31 is in the discharge stroke, between the rotation angles β11-β12, it is in the suction stroke, between β12-β13, it is in the compression stroke, and between β13-β0 (all of the above are marked in the Figure 5 extension direction of the X-axis in), it is in the discharge stroke.

[0028] Generally speaking, because there is a 180° phase difference in the rotation angles of the two cam members 7 on the second pump head 31 and the first pump head 30, the two pump heads independently and repeatedly perform the compression stroke, the discharge stroke, the expansion stroke, and the suction stroke within the range of 360° of the rotation angle of their respective cam members 7.

[0029] For example, Figure 5 as shown by the thick solid line A in, for the first pump head 30, during the compression stroke of the rotation angle β0-β10 of the cam member 7, by means of the specially designed outer contour surface of the cam member 7 (including the above-mentioned special structure and special material design), the flat-bottom push rod 18 is pushed to move according to a predetermined motion law, and further drives the plunger member 2 to move in the same motion characteristics and move towards the diaphragm 27 at the same time; when the rotation angle is 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 shown by the rotation angle β0-β10 in the thick solid line A of Figure 6 ; when the rotation angle starts from β10, the plunger member 2 continues to move towards the diaphragm 27, and will push the diaphragm 27 to move 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 both been compressed, and the bubbles in them have been squeezed and broken (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; Similarly, as shown in Figure 5As shown by the thin chain line B in the figure, starting from the rotation angle β10 of the second pump head 31, the speed of the plunger member 2 and its corresponding discharge flow rate both begin to decrease. Therefore, considering the instantaneous motion characteristics of the first pump head 30 and the second pump head 31 and their corresponding flow velocity performances, the discharge flow rate increased by the first pump head 30 starting from the rotation angle β10 will cancel out the discharge flow rate decreased by the second pump head 31 starting from the rotation angle β10, thereby keeping the superimposed discharge flow rate in the common discharge manifold 39 within a constant range at all times; at the same time, a constant discharge pressure is also maintained in the common discharge manifold 39. Next, during the rotation angle β10-β2, the speed of the plunger member 2 of the first pump head 30 successively maintains a state of uniformly accelerating-uniformly moving-uniformly decelerating, and its moving direction is always towards the diaphragm 27, pushing the diaphragm 27 to always move forward, that is, the first pump head 30 is in the discharge stroke. When the rotation angle is β2, the plunger member 2 moves to the aforementioned front dead center position, that is, the maximum stroke of the discharge of the first pump head 30; When Figure 5 the thick solid line A in the figure, 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, which also indicates that the plunger member 2 begins to move towards a position 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 will begin 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 successively maintains a state of uniformly accelerating-uniformly moving-uniformly decelerating and moves in a direction away from the hydraulic chamber 60, and the diaphragm 27 also continuously moves in the direction of the retreat of the plunger member 2; after a period of time, a negative pressure is formed in the hydraulic chamber 60, and the fluid medium begins to enter the medium chamber 61 through the suction pipeline 34. During this period, the plunger member 2 always moves in a direction away from the diaphragm 27, and the suction stroke ends when the rotation angle of the cam member 7 is 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 continuously repeated.

[0030] Because the rotation angle of the cam member 7 of the second pump head 31 is exactly 180° out of phase with the rotation angle of the cam member 7 of the first pump head 30, so as Figure 5 and Figure 6 shown by the thick solid line A and the thin chain line B in the figure, the moving speeds and displacements of the plunger member 2 of the second pump head 31 and the plunger member 2 of the first pump head 30 are also 180° out of phase. The stroke of the plunger member 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, and the rotation angle of the cam member 7 corresponding to the rear dead center is Figure 5In β11; thus, the plunger 2 of the second pump head 31 will reciprocate simultaneously with the plunger 2 of the first pump head 30 with a rotational angle lag of 180°, and the pressure in its hydraulic chamber 60 will also change accordingly. The pressure change pattern is the same as that of the first pump head 30 during the compression stroke, discharge stroke, expansion stroke, and suction stroke.

[0031] As Figure 5 shown, at the rotational 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 starts the discharge stroke, and the fluid immediately enters the common discharge manifold 39. At this rotational angle β10, the second pump head 31 is at the end of the discharge stroke. Also as Figure 5 shown, the increased discharge flow of the first pump head 30 is exactly offset by the decreased discharge flow of the second pump head 31. Therefore, the superimposed flow curve is as Figure 5 shown by the dotted line in, and it is always a constant flow. Similarly, the pressure pulsation in the common discharge manifold 39 is also eliminated.

[0032] 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 angular 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 rotational angle, satisfying that the superimposed speed is a constant value and is equal to the speed value of the uniform speed section when the speed does not change. Similarly, in the present invention, it can also be evolved that at the end of the compression stroke, the speed of the plunger 2 is not set to zero; or at the end of the expansion stroke, the speed of the plunger 2 is set to zero.

Claims

1. A double-unit pulsation-free metering pump, characterized in that: It includes a first pump head (30) and a second pump head (31), as well as a drive end assembly shared by the first pump head (30) and the second pump head (31). The drive end assembly includes a body (1), a camshaft (19) movably connected within the body (1), and cam members (7) mounted on the camshaft (19). The rotation angles of the two cam members (7) have a 180° phase difference. A reduction motor is mounted on the body (1), and the 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 with a rotation angle having a ° phase difference; Both the first pump head (30) and the second pump head (31) include a set of guiding assemblies, a linkage module movably connected within the guiding assembly, a plunger connection assembly, and a hydraulic end assembly mounted at the end of the guiding assembly; One end of the linkage module abuts against the corresponding cam member (7). The two cam members (7) respectively drive the corresponding linkage modules to move within the guiding 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) mounted between the hydraulic chamber (60) and the medium chamber (61); When the plunger connection assembly enters the hydraulic chamber (60), the hydraulic oil is compressed, and the medium chamber (61) discharges fluid; When the plunger connection assembly moves away from within the hydraulic chamber (60), the hydraulic oil expands, and the medium chamber (61) sucks in 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) form a limit with the camshaft (19) through the flat key (9) and the keyway. 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 face of the cam member (7) and is used to prevent the cam member (7) from axially moving. The outer contour surface of the cam member (7) has a high-hardness coating.

2. The double-unit pulsation-free metering pump according to claim 1, characterized in that: The linkage module includes a flat-bottom push rod (18) movably connected within the guiding 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) abuts against the flat bottom surface of the flat-bottom push rod (18), and the other end abuts against the guiding assembly.

3. The double-unit pulsation-free metering pump according to claim 2, characterized in that: An elastic cylindrical pin (17) is mounted on the flat-bottom push rod (18). 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 guiding assembly, and the elastic cylindrical pin (17) is embedded in this groove.

4. A double-unit pulsation-free metering pump according to claim 3, characterized in that: The guiding assembly includes a slideway (102) fixedly connected to the machine body (1) by a first hexagon socket head cap screw (103) and a guiding sleeve (107) fixedly connected to the slideway (102). The guiding sleeve (107) is connected to the slideway (102) by a second hexagon socket head cap screw (109). The flat-bottom push rod (18) moves along the axial direction of the slideway (102), and a number of axial oil guiding through holes (40) are provided on the slideway (102).

5. A double-unit pulsation-free metering pump according to claim 4, characterized in that: A connecting body (104) is installed between the slideway (102) and the plunger connecting assembly. The connecting body (104) is provided with a cavity structure, and lubricating oil flows from the guiding 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 reciprocate in the guiding sleeve (107).

6. A double-unit pulsation-free metering pump according to claim 5, characterized in that: The plunger connecting assembly includes a plunger part (2) movably connected in the hydraulic end assembly. One end of the plunger part (2) is connected to the flat-bottom push rod (18) through an assembly connecting part. The flat-bottom push rod (18) drives the plunger part (2) to reciprocate linearly in the hydraulic cavity through the assembly connecting part.

7. A double-unit pulsation-free metering pump according to claim 6, characterized in that: The assembly connecting part includes a cap nut (335) screwed on the flat-bottom push rod (18), a threaded compression sleeve (336) screwed on the piston part, and a flat washer (334) arranged between the plunger part (2) and the cap nut (335). The threaded compression sleeve (336) is connected to the cap nut (335) and is fixedly connected through a hexagon nut (337). A hydraulic cylinder body (431) is arranged on the guiding assembly, and the inner hole of the hydraulic cylinder body (431) is used for sealing the outer circumferential surface of the plunger part (2).

8. A double-unit pulsation-free metering pump according to claim 7, characterized in that: One end of the hydraulic end assembly is provided with a pump suction port (36), and the other end is provided with a pump discharge port (37). 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 ports (36) of the first pump head (30) and the second pump head (31) are connected and aggregated into a common suction manifold (38) through a set of pipelines. The pump discharge ports (37) of the first pump head (30) and the second pump head (31) are connected and aggregated into a common discharge manifold (39) through a set of pipelines.

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