Plunger pump system, control method and filter press

Abstract

The invention relates to a plunger pump system, a control method and a filter press. The plunger pump system comprises an oil storage container, an oil pump device, a plunger device and a hydraulic device. The hydraulic device comprises two hydraulic assemblies, each hydraulic assembly comprises an oil cylinder and a piston, the piston divides the oil cylinder into a rod cavity and a rodless cavity, and the rod cavities of the two hydraulic assemblies or the rodless cavities of the two hydraulic assemblies are communicated with each other. The oil pump device and the hydraulic device are connected through an oil supply pipeline, a liquid flow reversing device and a one-way valve are connected to the oil supply pipeline, the flow direction of hydraulic oil in two branch pipelines of the oil supply pipeline is controlled by the liquid flow reversing device to be periodically switched, and the flow directions of the hydraulic oil in the branch pipelines are opposite at the same moment. One end of the electric control overflow device is connected between an oil pump device and a one-way valve, the other end of the electric control overflow device is connected with an oil storage container, and the electric control overflow device is controlled to conduct an oil outlet of the oil pump device and the oil storage container during reversing of the liquid flow reversing device and discharge impact of hydraulic oil reversing on the plunger pump system.

Description

Technical Field

[0001] This application relates to the technical field of slurry conveying equipment, and particularly to a plunger pump system, a control method, and a filter press. Background Art

[0002] As the core power unit of equipment such as filter presses, the performance of the plunger pump system directly affects the working efficiency and stability of the equipment. Traditional plunger pump systems usually use single or double oil cylinders to drive the plunger to reciprocate, and the oil circuit direction is switched by a reversing valve to achieve the pushing and pulling actions of the plunger. However, during the liquid flow commutation process, due to the sudden cut-off or opening of the oil circuit, the instantaneous pressure of the hydraulic oil will surge, generating a severe hydraulic shock. This shock not only causes system vibration and noise, but also accelerates the wear of seals, pipelines, and valve bodies, and leads to an increase in oil temperature, reducing the system reliability. To solve the above problems, some solutions in the prior art relieve the shock by adding multi-stage buffer valves, throttling devices, or independent pressure relief circuits in the oil circuit. However, such passive buffer structures cannot accurately match the commutation timing, and have obvious hysteresis, resulting in poor buffering effects. There are also some prior arts. For example, in the Chinese invention patent application with the application publication number CN118564576A and the name "An electro-hydraulic control system for a disc brake device", a disc brake device electro-hydraulic control system is disclosed in its technical solution. The disc brake device electro-hydraulic control system reduces the commutation shock by adding power units such as a boosting plunger and a pressure-reducing plunger. However, the added components will introduce additional complexity and maintenance costs, resulting in a bloated system structure, reduced system reliability, and increased costs.

[0003] In view of this, it is necessary to propose a new technical solution to overcome the deficiencies of the prior art. Summary of the Invention

[0004] Based on this, this application provides a plunger pump system, a control method, and a filter press, which can dynamically respond to the commutation shock and achieve the purpose of buffering vibration and improving system stability.

[0005] To this end, this application adopts the following technical solution: A plunger pump system includes an oil storage container, an oil pump device, a plunger device, and a hydraulic device. The oil pump device is used to extract hydraulic oil from the oil storage container and transport it to the hydraulic device to drive the plunger device to move through the hydraulic device, wherein: The hydraulic device includes a first hydraulic component and a second hydraulic component. Both the first hydraulic component and the second hydraulic component include an oil cylinder and a piston that can reciprocate in the oil cylinder driven by hydraulic oil. The piston has a piston rod acting on the plunger device. Wherein, the piston divides the oil cylinder into a rod chamber and a rodless chamber, and the two rod chambers or the two rodless chambers of the first hydraulic component and the second hydraulic component are communicated with each other; The oil pump device and the hydraulic device are connected by an oil supply pipeline. A flow direction reversing device is connected to the oil supply pipeline. The oil supply pipeline includes a main pipeline located between the oil pump device and the flow direction reversing device, and two branch pipelines located between the flow direction reversing device and the hydraulic device. One of the two branch pipelines is connected to the oil cylinder of the first hydraulic component, and the other is connected to the oil cylinder of the second hydraulic component. Among them, the flow direction of the hydraulic oil in the two branch pipelines is periodically switched under the control of the flow direction reversing device, and the flow directions of the hydraulic oil in the two branch pipelines are opposite at the same moment; Among them, a check valve is arranged on the main pipeline. The check valve allows the hydraulic oil to flow from the oil pump device to the flow direction reversing device and prevents the hydraulic oil from flowing in the reverse direction; Among them, the plunger pump system further includes an electronically controlled overflow device with one end connected between the oil pump device and the check valve and the other end connected to the oil storage container. The electronically controlled overflow device is controlled to conduct the oil outlet of the oil pump device and the oil storage container when the flow direction reversing device switches the flow direction of the hydraulic oil in the two branch pipelines, so as to discharge the impact on the plunger pump system caused by the hydraulic oil flow direction change.

[0006] As a further improved technical solution, the electronically controlled overflow device is an electromagnetic overflow valve.

[0007] As a further improved technical solution, the electronically controlled overflow device is a normally open electromagnetic overflow valve. In the powered state, it disconnects the connection between the oil outlet of the oil pump device and the oil storage container and can conduct the oil outlet of the oil pump device and the oil storage container by the oil supply pressure of the oil pump device to achieve overflow.

[0008] As a further improved technical solution, when the flow direction reversing device switches the flow direction of the hydraulic oil in the two branch pipelines, the electronically controlled overflow device is controlled to be powered off to conduct the oil outlet of the oil pump device and the oil storage container.

[0009] As a further improved technical solution, the duration of the electronically controlled overflow device being controlled to be powered off is 5 - 25 ms.

[0010] As a further improved technical solution, the oil pump device includes a motor and a large-displacement pump and a small-displacement pump driven by the motor. Among them, in one oil supply cycle, it successively experiences the stages of the large-displacement pump and the small-displacement pump jointly supplying oil, the large-displacement pump being idle and the small-displacement pump supplying oil, and both the large-displacement pump and the small-displacement pump being idle. After the hydraulic oil in the two branch pipelines changes its flow direction, a new oil supply cycle begins.

[0011] As a further improved technical solution, the main pipeline includes two shunt sections and one confluence section. The two shunt sections are respectively connected to the large-displacement pump and the small-displacement pump, and the two shunt sections merge into the confluence section. Among them, there are two one-way valves, which are respectively arranged on the two shunt sections.

[0012] As a further improved technical solution, the plunger pump system further includes an accumulator, and the accumulator is connected in parallel between the confluence section and the liquid flow reversing device.

[0013] The present application also adopts the following technical solution: A control method for a plunger pump system, the control method is applied to the plunger pump system as described above, and the control method includes: Controlling the oil pump device to continuously operate to deliver hydraulic oil into the oil cylinders of the first hydraulic component and the second hydraulic component, and making the movement directions of the pistons of the first hydraulic component and the second hydraulic component opposite at the same time; Controlling the liquid flow reversing device to switch the flow direction of the hydraulic oil delivered into the oil cylinders of the first hydraulic component and the second hydraulic component; and When the liquid flow reversing device switches the flow direction of the hydraulic oil delivered into the oil cylinders of the first hydraulic component and the second hydraulic component, controlling the electro-hydraulic overflow device to conduct the oil outlet of the oil pump device and the oil storage container to discharge the impact of the hydraulic oil commutation on the plunger pump system.

[0014] The present application also adopts the following technical solution: A filter press, including an inlet valve, a discharge valve and the plunger pump system as described above. The inlet valve and the discharge valve are connected to the pump body of the plunger device of the plunger pump system. The plunger device sucks the slurry through the inlet valve and presses and discharges the liquid in the slurry through the discharge valve.

[0015] The plunger pump system provided by the present application realizes the phase complementarity of the piston movement through the chamber connection design of the first hydraulic component and the second hydraulic component, reducing the fluctuation of the flow demand; the sequential linkage control of the liquid flow reversing device and the electro-hydraulic overflow device accurately matches the pressure release window during the commutation process, and can dynamically respond to the commutation impact, solving the vibration and component loss problems caused by the commutation impact in the traditional system, and achieving the purpose of buffering vibration and improving the system stability. Further, the introduction of the dual-pump combination and the accumulator optimizes the energy efficiency performance on the premise of ensuring the output power, significantly improving the reliability of the overall operation of the system. Brief Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 It is a schematic diagram of the system connection of an embodiment of the plunger pump system of the present application.

[0018] Figure 2 It is a sectional view of the hydraulic device and the plunger device in an embodiment of the plunger pump system of the present application.

[0019] The reference numerals of each component are as follows: 1, oil storage container; 11, oil filter; 12, cooler; 2, oil pump device; 21, motor; 22, large-displacement pump; 23, small-displacement pump; 3, hydraulic device; 31, oil cylinder; 311, rod chamber; 312, rodless chamber; 32, piston; 321, piston rod; 4, liquid flow reversing device; 5, accumulator; 61, one-way valve; 62, electronically controlled overflow device; 7, pressure sensor; 81, main pipeline; 82, branch pipeline; 9, plunger device. Detailed implementation manners

[0020] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will make a detailed description of the specific implementation manners of the present application with reference to the drawings. Many specific details are set forth in the following description in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0021] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or there can also be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of the present application are only for the purpose of illustration and do not represent the only implementation manner.

[0022] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0023] In this application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may mean that the first feature is in direct contact with the second feature or the first feature is in indirect contact with the second feature through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0024] Unless otherwise defined, all technical and scientific terms used in the description of this application have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the description of this application includes any and all combinations of one or more of the related listed items.

[0025] Please refer to Figure 1 and Figure 2 As shown, this application provides a plunger pump system, including an oil storage container 1, an oil pump device 2, a plunger device 9, and a hydraulic device 3. The oil pump device 2 is used to extract hydraulic oil from the oil storage container 1 and transport it to the hydraulic device 3 to drive the plunger device 9 to move through the hydraulic device 3. The hydraulic device 3 includes a first hydraulic component and a second hydraulic component. Both the first hydraulic component and the second hydraulic component include an oil cylinder 31 and a piston 32 that can reciprocate in the oil cylinder 31 driven by hydraulic oil. The piston 32 has a piston rod 321 acting on the plunger device 9. Wherein, the piston 32 divides the oil cylinder 31 into a rod chamber 311 and a rodless chamber 312, and the two rod chambers 311 or the two rodless chambers 312 of the first hydraulic component and the second hydraulic component communicate with each other.

[0026] The oil pump device 2 and the hydraulic device 3 are connected by an oil supply pipeline. A fluid flow reversing device 4 is connected to the oil supply pipeline. The oil supply pipeline includes a main pipeline 81 between the oil pump device 2 and the fluid flow reversing device 4, and two branch pipelines 82 between the fluid flow reversing device 4 and the hydraulic device 3. One of the two branch pipelines 82 is connected to the oil cylinder 31 of the first hydraulic component, and the other is connected to the oil cylinder 31 of the second hydraulic component. Among them, the flow direction of the hydraulic oil in the two branch pipelines 82 is periodically switched by the fluid flow reversing device 4, and the flow directions of the hydraulic oil in the two branch pipelines 82 are opposite at the same moment. A check valve 61 is provided on the main pipeline 81. The check valve 61 allows the hydraulic oil to flow from the oil pump device 2 to the fluid flow reversing device 4 and prevents the reverse flow of the hydraulic oil.

[0027] Among them, the plunger pump system further includes an electronically controlled overflow device 62 with one end connected between the oil pump device 2 and the check valve 61 and the other end connected to the oil storage container 1. The electronically controlled overflow device 62 is controlled to conduct the oil outlet of the oil pump device 2 and the oil storage container 1 when the fluid flow reversing device 4 switches the reversal of the hydraulic oil in the two branch pipelines 82, so as to discharge the impact on the plunger pump system caused by the hydraulic oil reversal.

[0028] The plunger pump system provided by the present application realizes the phase complementarity of the piston 32 movement through the chamber communication design of the first hydraulic component and the second hydraulic component, reducing the fluctuation of the flow demand; the sequential linkage control of the fluid flow reversing device 4 and the electronically controlled overflow device 62 accurately matches the pressure release window during the reversing process, and can dynamically respond to the reversing impact, solving the problems of vibration and component loss caused by the reversing impact in the traditional system, and achieving the purpose of buffering vibration and improving the system stability. Further, the introduction of the double pump combination and the accumulator 5 optimizes the energy efficiency performance on the premise of ensuring the output power, significantly improving the reliability of the overall operation of the plunger pump system.

[0029] As Figure 1 shown, the plunger pump system of this embodiment mainly includes an oil storage container 1, an oil pump device 2, a hydraulic device 3, a fluid flow reversing device 4, a plunger device 9, and supporting pipelines and valve bodies. The oil storage container 1 serves as the basis for the storage and circulation of the hydraulic oil. A filter 11 and a cooler 12 are further provided inside it, which are respectively used to filter impurities in the hydraulic oil and regulate the oil temperature to ensure the oil cleanliness and viscosity stability.

[0030] In this embodiment, the oil pump device 2 includes a motor 21, a large-displacement pump 22 and a small-displacement pump 23 driven by the motor 21. Among them, in one oil supply cycle, it successively experiences the stages of the large-displacement pump 22 and the small-displacement pump 23 jointly supplying oil, the large-displacement pump 22 being idle and the small-displacement pump 23 supplying oil, and both the large-displacement pump 22 and the small-displacement pump 23 being idle. Driven by the motor 21, hydraulic oil is pumped from the oil storage container 1, pressurized and conveyed to the hydraulic device 3, thereby driving the plunger device 9 to perform reciprocating motion.

[0031] Please refer to Figure 1 and Figure 2 As shown, in this embodiment, the hydraulic device 3 includes a first hydraulic component and a second hydraulic component, the two having symmetric structures and their oil circuits being interconnected. Through the liquid flow direction-changing device 4, the oil supply direction is periodically switched to achieve bidirectional drive of the plunger device 9. Both the first hydraulic component and the second hydraulic component in the hydraulic device 3 include an oil cylinder 31 and a piston 32 that can reciprocate along the inner wall of the oil cylinder 31. The piston 32 is mechanically connected to the plunger device 9 through a piston rod 321, transmitting its linear motion to the plunger device 9. The piston 32 divides the interior of the oil cylinder 31 into a rod chamber 311 and a rodless chamber 312. The rod chamber 311 is the side where the piston rod 321 is located, and the rodless chamber 312 is the side opposite to the piston rod 321. In this embodiment, the plunger device 9 is located below the hydraulic device 3, and the piston rod 321 extends downward to connect to the plunger device 9. Therefore, the rodless chamber 312 is located above the rod chamber 311. The volumes of the two chambers, the rod chamber 311 and the rodless chamber 312, change with the movement of the piston 32. To form a linkage effect of the hydraulic components, an oil fluid interaction channel is formed between the two rod chambers 311 or the two rodless chambers 312 of the first hydraulic component and the second hydraulic component through a connecting pipeline. With such a setting, when the rod chamber 311 or the rodless chamber 312 of the first hydraulic component is compressed and the hydraulic oil flows out, the hydraulic oil can enter the rod chamber 311 or the rodless chamber 312 of the second hydraulic component, reducing the amount of hydraulic oil flowing back into the oil storage container 1 and reducing the oil supply amount of the oil pump device 2. In Figure 2 In the shown embodiment, the rodless chambers 312 of the two hydraulic components are respectively connected to the hydraulic device 3 through pipelines, and the rod chambers 311 of the two hydraulic components are directly connected through a bypass pipeline. This design enables when the piston 32 of one of the hydraulic components extends outward under the thrust of the hydraulic oil, the piston 32 of the other hydraulic component to retract synchronously due to the oil fluid flow in the connected chambers, thereby achieving the phase difference motion of the two pistons 32.

[0032] The liquid flow direction-changing device 4, as the core component for switching the oil circuit direction, is arranged between the oil pump device 2 and the hydraulic device 3. Please refer to Figure 1As shown, in this embodiment, the oil supply pipeline is divided into a main pipeline 81 and two branch pipelines 82. The main pipeline 81 extends from the oil outlet of the oil pump device 2 to the oil inlet port of the flow direction reversing device 4, and the two branch pipelines 82 are respectively connected to the two oil outlet ports of the flow direction reversing device 4 and the rodless chambers 312 of the two hydraulic components. The flow direction reversing device 4 can periodically switch the oil supply directions of the two branch pipelines 82 through control methods such as solenoid valves or hydraulic pilot valves. In some embodiments, the flow direction reversing device 4 is an electromagnetic reversing valve. The flow direction reversing device 4 has an oil return port connected to the oil storage container 1. At a certain moment, one of the branch pipelines 82 introduces high-pressure oil into the rodless chamber 312 of the first hydraulic component, pushing its piston 32 to move outward, while the other branch pipeline 82 serves as an oil return channel to guide the oil in the rodless chamber 312 of the second hydraulic component back to the oil storage container 1; vice versa. When the flow direction reversing device 4 switches its state, the oil flow directions of the two branch pipelines 82 are reversed, realizing the synchronous switching of the moving directions of the pistons 32 of the two hydraulic components. In this embodiment, the flow direction reversing device 4 is controlled by a controller, such as a PLC controller, and a proximity sensor to cooperate with the control action to achieve the switching. The proximity sensor is arranged on the hydraulic device 3 and triggers the commutation according to the displacement feedback of the piston 32.

[0033] Please continue to refer to Figure 1 As shown, in this embodiment, the oil pump device 2 adopts a double-pump combined structure, that is, a double-pump is used, which includes a large-displacement pump 22 and a small-displacement pump 23 driven by the same motor 21. The main pipeline 81 includes two shunt sections and one confluence section. The two shunt sections are respectively connected to the large-displacement pump 22 and the small-displacement pump 23, and the two shunt sections merge into the confluence section. That is, the outlets of the two pumps are respectively connected to the confluence section through the shunt sections and converge in the confluence section and then lead to the flow direction reversing device 4. A check valve 61 is provided on each of the shunt sections to prevent the hydraulic oil from flowing back to the pump body. A pressure sensor 7 is connected to the confluence section to detect the oil supply pressure on the confluence section. This double-pump layout combined with pressure detection allows the system to flexibly adjust the oil supply volume at different working stages. Specifically: in the initial stage when the plunger device 9 needs to be quickly pushed forward, the large-displacement pump 22 and the small-displacement pump 23 supply oil together to meet the high-flow demand; when the plunger is close to the end of the stroke, the electronically controlled overflow device 62 with a pressure matching setting connected to the large-displacement pump 22 controls the large-displacement pump 22 to be no-load, and only the small-displacement pump 23 maintains low-pressure oil replenishment, thereby reducing power consumption; and at the moment of commutation, the electronically controlled overflow devices 62 connected to the two pumps are controlled to completely conduct the oil outlet of the oil pump device 2 and the oil storage container 1, so that the two pumps are briefly completely unloaded to avoid pressure shock.

[0034] One of the innovative points of this system lies in the introduction of the electro-hydraulic overflow device 62 and its interlocking control with the fluid flow reversing device 4. One end of the electro-hydraulic overflow device 62 is connected to the shunt section of the main pipeline 81 between the oil outlet of the oil pump device 2 and the check valve 61, and the other end is communicated with the oil storage container 1. In this embodiment, the electro-hydraulic overflow device 62 is an electromagnetic overflow valve, and preferably, the electro-hydraulic overflow device 62 is a normally open electromagnetic overflow valve, which disconnects the communication between the oil outlet of the oil pump device 2 and the oil storage container 1 in the energized state and can conduct the communication between the oil outlet of the oil pump device 2 and the oil storage container 1 by the oil supply pressure of the oil pump device 2 to achieve overflow. That is, in the normal working state, the electromagnetic overflow valve is in the energized closed state, and the hydraulic oil output by the oil pump device 2 flows through the check valve 61 to the fluid flow reversing device 4. Of course, in this process, due to the different oil supply pressures of the oil pump device 2, the electromagnetic overflow valve can be conducted under pressure, that is, it plays the same role as the traditional mechanical overflow valve. When the fluid flow reversing device 4 switches the oil flow direction, that is, when the electro-hydraulic overflow device 62 switches the hydraulic oil in the two branch pipelines 82 during the oil flow reversal of the fluid flow reversing device 4, it is controlled to be de-energized to conduct the communication between the oil outlet of the oil pump device 2 and the oil storage container 1. That is, at the moment of commutation, the controller sends a de-energization signal to the electromagnetic overflow valve to completely conduct the channel between the shunt section of the main pipeline 81 and the oil storage container 1. At this time, the output oil of the oil pump device 2 directly returns to the oil storage container 1 to realize system unloading. This design not only simplifies the commutation unloading control logic but also retains the overload protection function of the traditional overflow valve. This process lasts for a very short time. In some embodiments, the duration of the electro-hydraulic overflow device 62 being controlled to be de-energized is 5 - 25 ms (milliseconds), which matches the oil circuit closing period caused by the movement of the commutation spool of the fluid flow reversing device 4, so as to effectively discharge the commutation impact pressure. The fluid flow reversing device 4 and the electro-hydraulic overflow device 62 are triggered by related signals to ensure the consistency of their action relationships.

[0035] ‌To further optimize the system pressure stability, the plunger pump system further includes an accumulator 5, and the accumulator 5 is connected in parallel between the confluence section and the fluid flow reversing device 4. Specifically, the accumulator 5 is connected in parallel between the confluence section of the main pipeline 81 and the fluid flow reversing device 4. The accumulator 5 can absorb the pressure pulsation output by the oil pump device 2 and release the stored hydraulic energy at the moment of commutation to compensate for the instantaneous flow demand and reduce the load fluctuation of the motor 21. At the same time, the accumulator 5 and the electro-hydraulic overflow device 62 work together to ensure that the system pressure is always within the safe range.

[0036] The working process of an embodiment of the plunger pump system provided by this application is as follows. When the system is running, the motor 21 continuously drives the large-displacement pump 22 and the small-displacement pump 23 to operate. The hydraulic oil is filtered by the oil filter 11 and then enters the pump body for pressurization. The two pressurized oil flows respectively pass through the one-way valves 61, converge at the confluence section, are buffered by the accumulator 5, and finally reach the fluid flow reversing device 4. The fluid flow reversing device 4 switches the conduction directions of the two branch pipelines 82 according to a preset period or an external signal, driving the pistons 32 of the two hydraulic components to reciprocate alternately.

[0037] In a complete oil supply cycle, the propulsion process of the plunger device 9 is roughly divided into three stages: The high-speed propulsion stage. In this stage, the large-displacement pump 22 and the small-displacement pump 23 supply oil together. The rodless cavity 312 of the hydraulic device 3 is quickly filled with oil, pushing the piston 32 to extend outward at high speed, and the plunger quickly squeezes the slurry. The low-pressure oil replenishment stage, that is, when the plunger is close to the end of the stroke, the large-displacement pump 22 unloads and runs idly, and only the small-displacement pump 23 maintains low-pressure oil supply to compensate for the internal leakage of the system and keep the plunger pressure stable. The commutation stage, that is, after the fluid flow reversing device 4 receives the commutation instruction, the controller immediately triggers the electro-hydraulic overflow device 62 to conduct briefly. The oil output by the oil pump device 2 returns to the oil storage container 1 through the overflow valve. The pressure peak generated during the switching process of the spool of the fluid flow reversing device 4 is effectively released. After the commutation is completed, the electro-hydraulic overflow device 62 resumes closing, and enters a new oil supply cycle, that is, the oil pump device 2 supplies oil to the reverse branch pipeline 82 again, starting the next cycle of movement.

[0038] This application also provides a control method for a plunger pump system. The control method is applied to the plunger pump system as described above. The control method includes: Controlling the oil pump device 2 to run continuously to deliver hydraulic oil into the oil cylinders 31 of the first hydraulic component and the second hydraulic component, and making the movement directions of the pistons 32 of the first hydraulic component and the second hydraulic component opposite to each other at the same moment; Controlling the fluid flow reversing device 4 to switch the flow direction of the hydraulic oil delivered into the oil cylinders 31 of the first hydraulic component and the second hydraulic component; and When the fluid flow reversing device 4 switches the flow direction of the hydraulic oil delivered into the oil cylinders 31 of the first hydraulic component and the second hydraulic component, controlling the electro-hydraulic overflow device 62 to conduct the oil outlet of the oil pump device 2 and the oil storage container 1 to discharge the impact of the hydraulic oil commutation on the plunger pump system.

[0039] The present application further provides a filter press, which integrates the above-mentioned plunger pump system and operates under the control of the above-mentioned control method. The filter press includes a liquid inlet valve and a liquid discharge valve. The plunger device 9 sucks the slurry through the liquid inlet valve and presses and discharges the liquid in the slurry through the liquid discharge valve. That is, when the above-mentioned plunger pump system is integrated into the filter press, the pump body of the plunger device 9 sucks the slurry through the liquid inlet valve, and presses and discharges the liquid in the slurry by the thrust of the piston 32. Since the hydraulic system has the capabilities of efficient commutation and impact suppression, the filter press can achieve continuous operation with high frequency and low vibration, significantly improving the dehydration efficiency and extending the service life of the sealing parts.

[0040] From the description of the above specific embodiments, it can be seen that for the plunger pump system provided by the present application, through the chamber communication design of the first hydraulic component and the second hydraulic component, the phase complementarity of the movement of the piston 32 is realized, and the fluctuation of the flow demand is reduced; the sequential linkage control of the liquid flow commutation device 4 and the electronically controlled overflow device 62 accurately matches the pressure release window during the commutation process, and can dynamically respond to the commutation impact, solving the problems of vibration and component loss caused by the commutation impact in the traditional system, and achieving the purpose of buffering vibration and improving the system stability. Further, the introduction of the double-pump combination and the accumulator 5 optimizes the energy efficiency performance on the premise of ensuring the output power, significantly improving the reliability of the overall operation of the system.

[0041] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0042] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A plunger pump system, comprising an oil storage container, an oil pump device, a plunger device and a hydraulic device. The oil pump device is used to extract hydraulic oil from the oil storage container and deliver it to the hydraulic device, so as to drive the plunger device to move through the hydraulic device. It is characterized in that: The hydraulic device includes a first hydraulic component and a second hydraulic component. Both the first hydraulic component and the second hydraulic component include an oil cylinder and a piston that can reciprocate in the oil cylinder driven by hydraulic oil. The piston has a piston rod acting on the plunger device. Wherein, the piston divides the oil cylinder into a rod chamber and a rodless chamber, and the two rod chambers or the two rodless chambers of the first hydraulic component and the second hydraulic component communicate with each other; The oil pump device and the hydraulic device are connected by an oil supply pipeline. A liquid flow reversing device is connected to the oil supply pipeline. The oil supply pipeline includes a main pipeline located between the oil pump device and the liquid flow reversing device, and two branch pipelines located between the liquid flow reversing device and the hydraulic device. One of the two branch pipelines communicates with the oil cylinder of the first hydraulic component, and the other communicates with the oil cylinder of the second hydraulic component. Wherein, the flow direction of the hydraulic oil in the two branch pipelines is periodically switched by the liquid flow reversing device, and the flow directions of the hydraulic oil in the two branch pipelines are opposite at the same moment; Wherein, a check valve is arranged on the main pipeline, and the check valve allows the hydraulic oil to flow from the oil pump device to the liquid flow reversing device and prevents the hydraulic oil from flowing in the reverse direction; Wherein, the plunger pump system further includes an electronically controlled overflow device with one end connected between the oil pump device and the check valve and the other end connected to the oil storage container. The electronically controlled overflow device is controlled to conduct the oil outlet of the oil pump device and the oil storage container when the liquid flow reversing device switches the hydraulic oil in the two branch pipelines to reverse, so as to discharge the impact of the hydraulic oil reversing on the plunger pump system.

2. The plunger pump system according to claim 1, characterized in that, The electronically controlled overflow device is an electromagnetic overflow valve.

3. The plunger pump system according to claim 1 or 2, characterized in that, The electronically controlled overflow device is a normally open electromagnetic overflow valve, which disconnects the connection between the oil outlet of the oil pump device and the oil storage container in the powered-on state and can conduct the connection between the oil outlet of the oil pump device and the oil storage container by the oil supply pressure of the oil pump device to achieve overflow.

4. The plunger pump system according to claim 3, wherein, When the liquid flow reversing device switches the hydraulic oil in the two branch pipelines to reverse, the electronically controlled overflow device is controlled to be powered off to conduct the oil outlet of the oil pump device and the oil storage container.

5. The plunger pump system according to claim 4, wherein The duration of the electronically controlled overflow device being controlled to be powered off is 5 - 25 ms.

6. The plunger pump system according to claim 1, wherein The oil pump device includes a motor and a large-displacement pump and a small-displacement pump driven by the motor. Wherein, in one oil supply cycle, it successively experiences the stage of the large-displacement pump and the small-displacement pump jointly supplying oil, the stage of the large-displacement pump being idle and the small-displacement pump supplying oil, and the stage of both the large-displacement pump and the small-displacement pump being idle. After the hydraulic oil in the two branch pipelines is reversed, a new oil supply cycle is entered.

7. The plunger pump system according to claim 6, wherein, The main pipeline includes two shunt sections and one confluence section. The two shunt sections are respectively connected to the large-displacement pump and the small-displacement pump, and the two shunt sections converge to the confluence section. Wherein, there are two check valves, which are respectively arranged on the two shunt sections.

8. The plunger pump system according to claim 7, wherein, The plunger pump system further includes an accumulator, and the accumulator is connected in parallel between the confluence section and the liquid flow direction changing device.

9. A control method for a plunger pump system, characterized in that, The control method is applied to the plunger pump system according to any one of claims 1 to 8, and the control method includes: Controlling the oil pump device to continuously operate to deliver hydraulic oil into the oil cylinders of the first hydraulic component and the second hydraulic component, and making the movement directions of the pistons of the first hydraulic component and the second hydraulic component opposite to each other at the same moment; Controlling the liquid flow direction changing device to switch the flow direction of the hydraulic oil delivered into the oil cylinders of the first hydraulic component and the second hydraulic component; and When the liquid flow direction changing device switches the flow direction of the hydraulic oil delivered into the oil cylinders of the first hydraulic component and the second hydraulic component, controlling the electro-hydraulic overflow device to conduct the oil outlet of the oil pump device and the oil storage container to discharge the impact of the hydraulic oil commutation on the plunger pump system.

10. A filter press, characterized in that, It includes an inlet valve, a discharge valve and the plunger pump system according to any one of claims 1 to 8. The inlet valve and the discharge valve are communicated with the pump body of the plunger device of the plunger pump system. The plunger device sucks the slurry through the inlet valve and presses and filters out the liquid in the slurry through the discharge valve.

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