Refueling pressure control device, method and working machine

Abstract

The embodiment of the application provides a kind of oil supplement pressure control device, method and engineering machinery, belong to hydraulic system control technical field.The present application includes: system oil circuit, oil supplement circuit, flushing circuit and control system;Oil supplement circuit includes oil supplement pump and oil supplement overflow valve, and oil supplement pump is used to pump the oil in oil tank to system oil circuit;Oil supplement overflow valve is used to adjust the pressure of oil pumped out from oil tank by oil supplement pump;Flushing circuit includes flushing reversing valve, flushing overflow valve and electromagnetic reversing valve, flushing reversing valve mid-position function is oil port full communication, flushing reversing valve is connected with system oil circuit and flushing overflow valve respectively, and flushing overflow valve is connected to oil tank;Electromagnetic reversing valve is connected with flushing overflow valve, and electromagnetic reversing valve is used to control flushing overflow valve to open or close according to control signal issued by control system.It can control oil supplement pressure to reduce the power consumption of oil supplement pump in the whole working condition cycle, and improve system working efficiency.

Description

Technical Field

[0001] This application relates to the field of hydraulic system control technology, specifically to a replenishing oil pressure control device, a replenishing oil pressure control method, and an engineering machinery. Background Technology

[0002] Two common types of hydraulic systems used in construction machinery (e.g., pumping equipment) are closed-loop and open-loop hydraulic systems. In a closed-loop hydraulic system, the oil returning from the cylinder returns to the pump, and the oil circulates in the oil circuit between the cylinder and the pump. Without considering leakage and cooling, no external oil replenishment is needed. However, leakage and cooling are unavoidable in practice; therefore, closed-loop hydraulic systems typically include a replenishment pump to supply oil to the closed circuit.

[0003] However, under both pumping and waiting-for-material conditions, the power consumed by the replenishing pump is significantly higher than the actual power required by the system, resulting in unnecessary fuel consumption. Furthermore, the excess power is converted into heat in the hydraulic oil, and the heat dissipation capacity of the hydraulic system also needs to be improved accordingly, leading to unnecessary cost increases. Summary of the Invention

[0004] The purpose of this application is to provide an oil replenishment pressure control device, an oil replenishment pressure control method, and an engineering machinery to at least solve the above-mentioned problems.

[0005] To achieve the above objectives, the first aspect of this application provides a replenishment pressure control device, comprising:

[0006] The system includes an oil circuit, a replenishment circuit, a flushing circuit, and a control system.

[0007] The oil replenishment circuit includes an oil replenishment pump and an oil replenishment overflow valve. The oil replenishment pump is used to pump oil from the oil tank to the system oil circuit. The oil replenishment overflow valve is used to regulate the pressure of the oil pumped out of the oil tank by the oil replenishment pump.

[0008] The flushing circuit includes a flushing directional valve, a flushing overflow valve, and a solenoid directional valve. The flushing directional valve has a fully open oil port in its neutral position. The flushing directional valve is connected to the system oil circuit and the flushing overflow valve, respectively. The flushing overflow valve is connected to the oil tank. The solenoid directional valve is connected to the flushing overflow valve. The solenoid directional valve is used to control the flushing overflow valve to open or close according to the control signal issued by the control system, so as to control the pressure of the oil delivered by the replenishing pump.

[0009] In this embodiment, the electromagnetic reversing valve is used to control the pressure in the spring pilot chamber of the flushing overflow valve according to the control signal issued by the control system, so as to control its opening or closing.

[0010] In this embodiment, the electromagnetic reversing valve is used to control the pressure in the pilot chamber opposite the spring chamber of the flushing overflow valve according to the control signal issued by the control system, so as to control the opening or closing.

[0011] In this embodiment, a cooler is also provided between the flushing overflow valve and the oil tank.

[0012] In this embodiment of the application, it further includes: an oil temperature sensor.

[0013] The oil temperature sensor is used to acquire the oil temperature in the oil tank and send it to the control system;

[0014] The controller generates a control signal based on the oil temperature in the oil tank and sends it to the solenoid directional valve.

[0015] In this embodiment, the system oil circuit includes a closed main pump, and the oil replenishment circuit also includes a servo valve. The oil replenishment pump provides a pressure oil source to the servo valve. The servo valve generates a pressure signal according to the control signal sent by the control system and sends it to the closed main pump to control the direction of oil in the system oil circuit.

[0016] In this embodiment, the oil replenishment circuit further includes multiple multi-functional valves, each of which is connected to the oil replenishment pump and the flushing reversing valve, and the multiple multi-functional valves are used to provide flushing flow oil source for the flushing overflow valve.

[0017] A second aspect of this application provides a method for controlling replenishing oil pressure, applied to the replenishing oil pressure control device described in the first aspect, comprising the following steps:

[0018] The control system sends a control signal to the solenoid directional valve;

[0019] The electromagnetic reversing valve controls the flushing overflow valve to open or close according to the control signal.

[0020] In this embodiment of the application, the following steps are also included:

[0021] The control system obtains the hydraulic oil temperature;

[0022] The hydraulic oil temperature is compared with a preset temperature threshold to obtain the comparison result;

[0023] A control signal is generated based on the comparison results and sent to the solenoid directional valve.

[0024] In this embodiment, the preset temperature thresholds include T1 and T2. The step of comparing the hydraulic oil temperature with the preset temperature thresholds to obtain a comparison result, and generating a control signal based on the comparison result and sending it to the solenoid directional valve, includes the following steps:

[0025] A1: Determine whether the hydraulic oil temperature is lower than T1. If yes, generate an energized control signal and send it to the solenoid directional valve; otherwise, execute A2.

[0026] A2: Determine whether the hydraulic oil temperature is less than or equal to T2. If yes, generate a control signal to energize the solenoid directional valve and send it to the solenoid directional valve. Determine whether to set the pump start. If yes, keep the solenoid directional valve energized. If not, repeat the cycle to determine whether the hydraulic oil temperature is less than or equal to T2. If the hydraulic oil temperature is greater than T2, execute A3.

[0027] A3: Determine whether pump start is enabled. If not, generate a control signal to de-energize the solenoid directional valve and send it to the solenoid directional valve. If yes, execute A4.

[0028] A4: Determine if there is a reversing signal. If not, generate a control signal to de-energize the solenoid reversing valve and send it to the solenoid reversing valve. If there is a reversing signal, generate a control signal to energize the solenoid reversing valve and send it to the solenoid reversing valve. Start timer t and repeatedly check the value of the timer until t is greater than or equal to the preset value t1, then end.

[0029] A third aspect of this application provides an engineering machinery, including an actuator; and a replenishing oil pressure control device according to the first aspect, wherein the system oil circuit is used to drive the actuator.

[0030] Through the above technical solution, the control system sends a control signal to the electromagnetic directional valve, which then controls the flushing overflow valve to open or close according to the control signal. This allows for secondary adjustment of the replenishing pump's working pressure via the flushing overflow valve, resulting in a 65% reduction in power consumption during the waiting period and a 50-62% reduction during the pumping cylinder's movement phase. By isolating the flushing overflow valve's pilot chamber from the return oil pressure, the flushing flow rate remains essentially consistent throughout the pump truck's lifespan, preventing hydraulic system overheating due to abnormal flushing flow. Furthermore, the electromagnetic directional valve's control over the opening and closing of the flushing overflow valve allows for increased replenishing pressure during the pumping cylinder's reversing phase, preventing damage from cavitation in the main pump. By simply changing the flushing directional valve to its neutral position function and adding a solenoid directional valve to provide control oil to the flushing relief valve, the opening and closing of the flushing relief valve can be controlled. This allows control of the replenishment oil pressure to reduce the power consumption of the replenishment pump throughout the entire operating cycle, thereby reducing the power loss of the closed hydraulic system, improving system efficiency, and making control simple and convenient.

[0031] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings:

[0033] Figure 1 A schematic diagram of a replenishment pressure control device according to an embodiment of this application is shown.

[0034] Figure 2 A schematic diagram of a flushing overflow valve and a solenoid directional valve according to an embodiment of this application is shown.

[0035] Figure 3 The schematic diagram illustrates a flowchart of a method for controlling replenishment pressure according to an embodiment of this application;

[0036] Figure 4 The diagram illustrates the oil temperature control logic in a low-temperature environment according to an embodiment of this application.

[0037] Explanation of reference numerals in the attached figures

[0038] 1-Maintenance pump; 2-Maintenance overflow valve; 3-Oil tank; 4-Closed main pump; 5-Servo valve; 6-Multi-function valve; 7-Flush directional valve; 8-Flush overflow valve; 9-Left pumping cylinder; 10-Displacement sensor; 11-Return oil filter; 12-Right pumping cylinder; 13-System oil circuit; 14-Cooler; 15-Oil temperature sensor; 16-Control system; 17-Solenoid directional valve; 18-Maintenance circuit; 19-Flushing circuit. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0040] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0041] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0042] Please refer to Figure 1 , Figure 1 This schematic diagram illustrates a replenishing oil pressure control device according to an embodiment of the present application. The replenishing oil pressure control device is used in a closed hydraulic system. For ease of understanding, this embodiment uses a type of pumping machinery, namely a concrete pump truck, as an example. The replenishing oil pressure control device includes: a system oil circuit 13, a replenishing oil circuit 18, a flushing circuit 19, and a control system 16.

[0043] The system oil circuit 13 includes a closed-loop main pump 4, used to control the direction of oil in the system oil circuit 13. In this embodiment, the system oil circuit 13 is used to drive the actuator in the construction machinery, such as a pumping cylinder in a concrete pump truck. The closed-loop main pump 4 can output pressure oil in both directions. In a concrete pump truck, the system oil circuit 13 mainly uses the oil pressure in the pipeline to drive the pumping cylinder to push the concrete to flow in the pipeline, including a left pumping cylinder 9 and a right pumping cylinder 12. The two pumping cylinders move in coordination; when one extends outward, the other cylinder retracts synchronously.

[0044] The replenishment circuit 18 includes a replenishment pump 1 and a replenishment overflow valve 2. The replenishment pump 1 is used to pump oil from the oil tank 3 to the system oil circuit 13. The replenishment overflow valve 2 is used to regulate the pressure of the oil pumped out of the oil tank 3 by the replenishment pump 1. In this embodiment, the replenishment pump 1 can be a fixed displacement gear pump. One end of the oil inlet of the replenishment pump 1 is connected to the oil tank 3, and one end of the oil outlet is connected to the closed main pump 4. The closed main pump 4 draws oil from the low-pressure side of the system oil circuit 13, pressurizes it, and then outputs it to the system oil circuit 13. In order to regulate the pressure of the oil discharged from the replenishment pump 1, one end of the replenishment overflow valve 2 can be connected to the oil outlet of the replenishment pump 1, and the other end of the replenishment overflow valve 2 can be connected to the oil tank 3, so that the pressure of the oil discharged by the replenishment pump 1 can be regulated by the replenishment overflow valve 2.

[0045] The oil replenishment circuit 18 further includes a servo valve 5. The oil replenishment pump 1 provides a pressure oil source to the servo valve 5. The servo valve 5 generates a pressure signal based on the control signal sent by the control system 16 and sends it to the closed main pump 4 to control the direction of the oil in the oil circuit of the control system 16. In this embodiment, the servo valve 5 is located between the closed main pump 4 and the oil replenishment pump 1, and the control system 16 is connected to the servo valve 5. The oil replenishment pump 1 provides a pressure oil source to the servo valve 5. After receiving the electrical analog signal, the servo valve 5 outputs modulated flow and pressure accordingly. It is both an electro-hydraulic conversion element and a power amplification element, capable of converting a low-power weak electrical input signal into a high-power hydraulic energy (flow and pressure) output to control the directional change of the closed main pump 4.

[0046] In the above example, the stroke of the pumping cylinder is usually between 1.5-2.5m. During operation, it needs to change direction constantly (the current maximum number of changes can reach 30 times / min, and the average number of changes during pumping is 10-12 times / min according to the big data of concrete pump truck). During the change of direction, the cylinder cannot perform external work. Therefore, in order to improve pumping efficiency, the concrete pump truck requires the cylinder to change direction as short as possible (usually ≤250ms). The cylinder changing speed mainly depends on the speed of the pressure oil direction change of the closed main pump 4. This speed is positively correlated with the oil source pressure entering the servo valve 5. This oil source is provided by the oil replenishment pump 1 and the pressure is regulated by the oil replenishment overflow valve 2.

[0047] Meanwhile, due to the short reversing time of the closed-loop main pump 4, but the inertia of the pumping cylinder, its reversing speed may not be able to keep up with the main pump. This can lead to the following situation: the closed-loop main pump 4 has completed the reversing, and the oil flow direction has changed, but the cylinder, due to inertia, has not yet completed the reversing, meaning the oil flow direction within the cylinder has not changed. This causes cavitation in one of the two working ports of the closed-loop main pump 4, while the other port experiences a pressure shock. To avoid cavitation damage to the closed-loop main pump 4, the replenishing overflow pressure is usually increased, thereby increasing the working pressure on the low-pressure side of the two working ports to resist cavitation, resulting in better reliability for the closed-loop main pump 4. For example, in the concrete pump truck field, to accelerate the reversing speed of the closed-loop main pump 4 and prevent cavitation at the working ports during the reversing process, which could damage the closed-loop main pump 4, the pressure value of the replenishing overflow valve 2 (currently 34 bar in the industry) is set higher than the pressure in other fields (such as 16-18 bar in tunnel boring machines).

[0048] The oil replenishment circuit 18 further includes multiple multi-functional valves 6, each of which is connected to the oil replenishment pump 1 and the flushing reversing valve 7. These multiple multi-functional valves 6 provide a flushing flow oil source for the flushing overflow valve 8. In this embodiment, two multi-functional valves 6 are included: an integrated high-pressure overflow valve and a low-pressure oil replenishment check valve.

[0049] It should be noted that the oil replenishment pump 1 can also provide oil to the system to replenish leaked and flush cooling oil through the multi-functional valve 6.

[0050] In the example above, to facilitate the detection of the stroke of the two pumping cylinders, displacement sensors 10 can be installed in the left pumping cylinder 9 and the right pumping cylinder 12 respectively. The control system 16 detects the stroke of the two pumping cylinders through the displacement sensors 10. After reaching the reversing position, it controls the electromagnets on both sides of the servo valve 5 to switch their energized states, thereby controlling the change of the pressure oil flow direction of the closed main pump 4. Ultimately, the movement direction of the left and right pumping cylinders 12 changes, and the cycle repeats continuously. It should be noted that the displacement sensor 10 can also be replaced by a proximity switch, which controls the servo valve 5 to be de-energized by detecting the piston position.

[0051] The flushing circuit 19 includes a flushing directional valve 7, a flushing overflow valve 8, and a solenoid directional valve 17. The flushing directional valve 7 has a fully open oil port in its neutral position. It is connected to both the system oil circuit 13 and the flushing overflow valve 8, which is connected to the oil tank 3. The solenoid directional valve 17 is connected to the flushing overflow valve 8 and controls the flushing overflow valve 8 to open or close according to a control signal from the control system 16. In this embodiment, the flushing circuit 19 is used to replace the oil in the system oil circuit 13. The flushing directional valve 7 is located between the high-pressure and low-pressure sides of the system oil circuit 13 and is connected to both sides.

[0052] In this embodiment, the neutral position function of the flushing reversing valve 7 is that all three oil ports of the flushing reversing valve 7 are connected, that is, the high pressure side of the system oil circuit 13 is connected to the flushing overflow valve 8, and the low pressure side of the system oil circuit 13 is connected to the flushing overflow valve 8.

[0053] By adding an electromagnetic reversing valve 17, a control oil source can be provided to the flushing overflow valve 8, which can control the opening and closing of the flushing overflow valve 8. The opening and closing of the flushing overflow valve 8 can be controlled in various ways. In this embodiment, the control includes the following two methods:

[0054] In the first method, the electromagnetic directional valve 17 is used to control the pressure in the spring pilot chamber of the flushing overflow valve 8 according to the control signal issued by the control system 16, thereby controlling its opening or closing. In this method, one end of the oil inlet of the electromagnetic directional valve 17 is connected to the oil tank 3, the control end of the electromagnetic directional valve 17 is connected to the control system 16, and the other end of the electromagnetic directional valve 17 is connected to the flushing overflow valve 8. By controlling the pressure entering the spring pilot chamber, the hydraulic pressure on both sides of the valve core is balanced, and the valve core of the flushing overflow valve 8 is closed by the spring force.

[0055] In the second type, the electromagnetic reversing valve 17 is used to control the pressure in the pilot chamber opposite the spring chamber of the flushing overflow valve 8 according to the control signal issued by the control system 16, so as to control its opening or closing. Please refer to... Figure 2 , Figure 2 The diagram illustrates a flushing overflow valve and a solenoid directional valve according to an embodiment of this application. In this configuration, the oil inlet of the solenoid directional valve 17 is connected to the system oil circuit 13, controlling the pressure to enter the pilot chamber opposite the spring chamber. If the pressure cannot enter this pilot chamber, the valve core will close under the action of the spring.

[0056] In this embodiment, since the pilot chamber of the flushing relief valve 8 is no longer connected to the return oil, but is connected to the valve front pressure or the oil tank 3 through the solenoid directional valve 17, the change in return oil pressure will no longer affect the set pressure of the flushing relief valve 8. Therefore, the pressure will no longer change with the working time of the construction machinery, and the flushing flow rate will remain basically consistent throughout the life cycle of the construction machinery, which can avoid hydraulic system overheating failure due to abnormal flushing flow rate.

[0057] The following sections explain how the replenishing pressure control device reduces unnecessary power consumption in the replenishing pump 1 under various operating conditions. For ease of understanding, a concrete pump truck will be used as an example.

[0058] In the waiting-for-materials condition, the flushing directional valve 7 is in the neutral position, and the solenoid directional valve 17 is de-energized and operates in the upper position. All the oil in the system oil circuit 13 can act on the flushing relief valve 8 through the neutral position of the directional valve. The relief pressure of this valve is set to P1. The pressure loss of the oil flowing through the multi-functional valve 6 is ΔP1, and the pressure loss through the neutral position valve port of the flushing directional valve 7 is ΔP2. As long as the value of P1 + ΔP1 + ΔP2 is less than the pressure value of 34 bar set by the replenishing relief valve 2, the replenishing relief valve 2 will no longer open. The flow rate of the replenishing pump 1 (approximately 65-70 L / min) will enter the system oil circuit 13 through the replenishing check valves in the two multi-functional valves 6, and then flow back to the hydraulic oil tank 3 after the flushing directional valve 7 is in the neutral position and the flushing relief valve 8 is opened. In this example, P1 is preferably 6 bar, ΔP1 is preferably 2 bar, and ΔP2 is preferably 4 bar. At this time, the working pressure of the replenishing pump 1 will decrease from 34 bar to 12 bar, reducing power consumption by 65%.

[0059] During pumping operation, when the pumping cylinder is in its stroke, the flushing directional valve 7 will be in either the upper or lower working position. The solenoid directional valve 17 is de-energized and operates in the upper position. The oil on the low-pressure side of the system oil circuit 13 can act on the flushing relief valve 8 through the working position of the directional valve. The relief pressure of this valve is set to P1. The pressure loss of the oil flowing through the multi-functional valve 6 is ΔP3, and the pressure loss of the oil flowing through the working position of the flushing directional valve 7 is ΔP4. After deducting the pressure oil source for the servo valve 5 and the replenishment of system leakage, the remaining flow of the replenishing pump 1 (90-130 L / min) will enter the system oil circuit 13 through the replenishing check valves in the two multi-functional valves 6, and then flow back to the hydraulic oil tank 3 after opening the flushing relief valve 8 through the working position of the flushing directional valve 7. In this example, P1 is preferably 6-8 bar (varying with flow rate, which is caused by changes in diesel engine speed, and the engine speed will change under different operating gears), ΔP3 is preferably 2 bar, and ΔP4 is preferably 5-7 bar (varying with flow rate). At this time, the working pressure of the supplementary fuel pump 1 will be reduced from 34 bar to 13-17 bar (varying with flow rate), and the power consumption will be reduced by 50-62%.

[0060] During the reversing phase of the pumping cylinders, to ensure the reversing speed and prevent cavitation, it is necessary to maintain the replenishing oil pressure. In this example, the control system 16 detects the stroke of the two pumping cylinders through the displacement sensor 10. After reaching the reversing position, the control system 16 sends a reversing signal. At this time, the electromagnet of the solenoid reversing valve 17 is energized, and the reversing valve operates in the lower position. At this time, the pressure before the flushing overflow valve 8 acts on the core control chamber of the flushing overflow valve 8 through the solenoid reversing valve 17. The hydraulic pressure at both ends of the valve core is equal. Under the action of the spring force, the flushing overflow valve 8 closes. At this time, the flow of the replenishing oil pump 1 can only return to the oil tank 3 through the replenishing overflow valve 2. At this time, the working pressure of the replenishing oil pump 1 is determined by the replenishing overflow valve 2, which is 34 bar. The solenoid reversing valve 17 is energized for a period of t1 (which can be adjusted according to the pumping gear and pumping pressure) and then de-energized. The flushing overflow valve 8 reopens, and the working pressure of the replenishing oil pump 1 is once again equal to P1 + ΔP3 + ΔP4. The replenishing overflow valve 2 closes synchronously. In this example, t1 is preferably 400ms.

[0061] This shows that:

[0062] 1. Under the condition of waiting for materials, the flow of the oil replenishment pump 1 no longer passes through the oil replenishment overflow valve 2, but flows back to the oil tank 3 through the neutral position of the flushing reversing valve 7 and the flushing overflow valve 8. The working pressure of the oil replenishment pump 1 can be reduced from 34 bar to 12 bar, and the power consumption can be reduced by about 2.9 kW, which is about 65%.

[0063] 2. During the pumping operation, in the normal movement phase of the pumping cylinder, the flow rate of the replenishing pump 1 flows back to the hydraulic oil tank 3 through the working position of the flushing directional valve 7 and the flushing relief valve 8. The working pressure of the replenishing pump 1 can be reduced from 34 bar to 13-17 bar (depending on the flow rate), and the power consumption can be reduced by up to 5.8-7.1 kW, a reduction of approximately 50-62%.

[0064] 3. During the pumping operation, when the pumping cylinder reverses direction, the flushing overflow valve 8 is electrically closed, and the flow of the replenishing pump 1 still flows back to the oil tank 3 through the replenishing overflow valve 2. The working pressure of the replenishing pump 1 rises again to 34 bar, and the working pressure on the low-pressure side of the two working ports of the closed main pump 4 rises synchronously, which can effectively prevent the main pump from being damaged by cavitation.

[0065] 4. Throughout the entire life cycle of the pump truck, the set pressure of the flushing overflow valve 8 will no longer change with the working time of the pump truck. The flushing flow rate will remain basically consistent under the pumping conditions of the pump truck, which can avoid hydraulic system overheating failure due to abnormal flushing flow rate.

[0066] In the above implementation process, the working pressure of the replenishing pump 1 is adjusted secondary by the flushing relief valve 8, reducing the power consumption of the replenishing pump 1 by 65% ​​in the waiting condition and by 50-62% during the pumping cylinder movement phase in the pumping condition. By isolating the pilot chamber of the flushing relief valve 8 from the return oil pressure, the flushing flow rate remains basically consistent throughout the pump truck's entire life cycle, avoiding hydraulic system overheating failures caused by abnormal flushing flow rate. The opening and closing of the flushing relief valve 8 is electrically controlled with an overriding function via the solenoid directional valve 17, increasing the replenishing oil pressure during the pumping cylinder reversing phase in the pumping condition, preventing damage to the main pump from cavitation. By simply changing the neutral position function of the flushing directional valve 7 and adding the solenoid directional valve 17 to provide control oil to the flushing relief valve 8, the opening and closing of the flushing relief valve 8 can be controlled, thereby controlling the replenishing oil pressure to reduce the power consumption of the replenishing pump 1 throughout the entire operating cycle. This reduces the power loss of the closed hydraulic system, improves system efficiency, and is simple and convenient to control.

[0067] In addition, a fixed mechanical back pressure can be set for the flushing overflow valve 8. Since the flushing overflow valve 8 is equipped with a fixed mechanical back pressure, even if the valve gets stuck, the back pressure (preferably 6 bar in this example), the pressure difference at the valve port of the flushing reversing valve 7 (preferably 4 bar in this example), and the pressure difference at the replenishing oil check valve (preferably 2 bar in this example) can ensure that the replenishing oil pump 1 will work at a pressure higher than 12 bar, so that the working oil port pressure of the closed main pump 4 is not lower than the usage requirement (10 bar), and the closed main pump 4 has good reliability.

[0068] It also includes a cooler 14 disposed between the flushing overflow valve 8 and the oil tank 3.

[0069] In closed-loop hydraulic systems, prolonged oil circulation can lead to excessively high oil temperatures and system failure. Therefore, closed-loop systems are typically equipped with flushing valves. The function of these flushing valves is to displace the high-temperature hydraulic oil circulating within the system and allow it to enter the cooler 14 for cooling, thus maintaining the oil temperature within a reasonable range. Based on design experience, the flow rate of oil displaced by the flushing valve is typically set to two-thirds of the flow rate of the replenishing pump 1. This is achieved by adjusting the pressure settings of the replenishing relief valve 2 (currently typically 34 bar in the pumping machinery industry) and the flushing relief valve 8 (currently typically 30 bar in the industry) to create a reasonable pressure difference.

[0070] To further filter impurities in the oil, a return oil filter 11 is also provided between the cooler 14 and the oil tank 3.

[0071] The system also includes an oil temperature sensor 15, which is used to acquire the oil temperature in the oil tank 3 and send it to the control system 16. In this embodiment, the oil temperature sensor 15 is installed in the oil tank 3 and connected to the control system 16.

[0072] The controller generates a control signal based on the oil temperature in the oil tank 3 and sends it to the solenoid directional valve 17. The control system 16 detects the hydraulic oil temperature through the oil temperature sensor 15 and generates a control signal based on the detected hydraulic oil temperature. The solenoid directional valve 17 is energized or de-energized according to the control signal, thereby controlling the opening or closing of the flushing overflow valve 8 to regulate the oil temperature.

[0073] For example: Please refer to Figure 4 , Figure 4 The schematic diagram illustrates a flowchart of a hydraulic oil replenishment pressure control method according to an embodiment of this application. In winter, after the pump truck is started for the first time, the control system 16 detects the hydraulic oil temperature via the oil temperature sensor 15. If the initial oil temperature is lower than T1, the control system 16 energizes the solenoid directional valve 17, which operates in the lower position. The flushing relief valve 8 is closed, and all replenishment flow passes through the replenishment relief valve 2 at a pressure of 34 bar to generate heat and quickly raise the system oil temperature. Pumping is not permitted during this period. When the system oil temperature rises to T1, pumping operations are permitted to begin. Before the oil temperature reaches the suitable temperature T2, the solenoid directional valve 17 remains energized, and the replenishment flow continues to pass through the replenishment relief valve 2 at a pressure of 34 bar to continue generating heat and quickly raise the oil temperature to the suitable temperature. In this example, T1 is 20°C, and T2 is 40°C.

[0074] By detecting the oil temperature of the hydraulic system and electrically controlling the unauthorized closure of the flushing overflow valve 8, the oil temperature can be raised to a suitable temperature as quickly as possible in low-temperature environments, thereby improving the construction efficiency of engineering machinery.

[0075] Based on the same inventive concept, this embodiment also provides a method for controlling replenishing oil pressure, applied to the aforementioned replenishing oil pressure control device. Please refer to [link / reference]. Figure 3 , Figure 3 This illustration schematically shows a flowchart of a method for controlling replenishing oil pressure according to an embodiment of the present application. This embodiment provides a method for controlling replenishing oil pressure, including the following steps:

[0076] Step 210: The control system 16 sends a control signal to the solenoid directional valve 17; In this embodiment, the control system 16 may be a controller, a microcontroller, an FPGA, or other control devices, and the control signal may be a control signal generated by the control system 16 based on the real-time oil temperature or displacement information of the actuator.

[0077] Step 220: The electromagnetic reversing valve 17 controls the flushing overflow valve 8 to open or close according to the control signal. The electromagnetic reversing valve 17 is energized or de-energized according to the control signal, thereby controlling the flushing overflow valve 8 to open or close.

[0078] The following sections explain how the replenishing pressure control device reduces unnecessary power consumption in the replenishing pump 1 under various operating conditions. For ease of understanding, a concrete pump truck will be used as an example.

[0079] In the waiting-for-materials condition, the flushing directional valve 7 is in the neutral position, and the solenoid directional valve 17 is de-energized and operates in the upper position. All the oil in the system oil circuit 13 can act on the flushing relief valve 8 through the neutral position of the directional valve. The relief pressure of this valve is set to P1. The pressure loss of the oil flowing through the multi-function valve 6 is ΔP1, and the pressure loss through the neutral position valve port of the flushing directional valve 7 is ΔP2. As long as the value of P1 + ΔP1 + ΔP2 is less than the pressure value of 34 bar set by the replenishing relief valve 2, the replenishing relief valve 2 will no longer open. The flow rate of the replenishing pump 1 (approximately 65-70 L / min) will enter the system oil circuit 13 through the replenishing check valve in both multi-function valves 6 and 7, and then flow back to the hydraulic oil tank 3 after the flushing directional valve 7 opens its relief valve in the neutral position. In this example, P1 is preferably 6 bar, ΔP1 is preferably 2 bar, and ΔP2 is preferably 4 bar. At this time, the working pressure of the replenishing pump 1 will decrease from 34 bar to 12 bar, reducing power consumption by 65%.

[0080] During pumping operation, when the pumping cylinder is in its stroke, the flushing directional valve 7 will be in either the upper or lower working position. The solenoid directional valve 17 is de-energized and operates in the upper position. The oil on the low-pressure side of the system oil circuit 13 can act on the flushing relief valve 8 through the working position of the directional valve. The relief pressure of this valve is set to P1. The pressure loss of the oil flowing through the multi-function valve 6 is ΔP3, and the pressure loss of the oil flowing through the working position of the flushing directional valve 7 is ΔP4. After deducting the pressure oil source for the servo valve 5 and the replenishment of system leakage, the remaining flow rate (90-130 L / min) of the replenishment pump 1 will enter the system oil circuit 13 through the two multi-function valves 6 or the replenishment check valve in the latter. Then, after passing through the working position of the flushing directional valve 7, the flushing relief valve 8 will open and flow back to the hydraulic oil tank 3. In this example, P1 is preferably 6-8 bar (varying with flow rate), ΔP3 is preferably 2 bar, and ΔP4 is preferably 5-7 bar (varying with flow rate). At this time, the working pressure of the replenishing pump 11 will be reduced from 34 bar to 13-17 bar (depending on the flow rate), and the power consumption will be reduced by 50-62%.

[0081] During the reversing phase of the pumping cylinders, to ensure the reversing speed and prevent cavitation, it is necessary to maintain the replenishing oil pressure. In this example, the control system 16 detects the stroke of the two pumping cylinders through the displacement sensor 10. After reaching the reversing position, the control system 16 sends a reversing signal. At this time, the electromagnet of the solenoid reversing valve 17 is energized, and the reversing valve operates in the lower position. At this time, the pressure before the flushing overflow valve 8 acts on the core control chamber of the flushing overflow valve 8 through the solenoid reversing valve 17. The hydraulic pressure at both ends of the valve core is equal. Under the action of the spring force, the flushing overflow valve 8 closes. At this time, the flow of the replenishing oil pump 1 can only return to the oil tank 3 through the replenishing overflow valve 2. At this time, the working pressure of the replenishing oil pump 1 is determined by the replenishing overflow valve 2, which is 34 bar. The solenoid reversing valve 17 is energized for a period of t1 (which can be adjusted according to the pumping gear and pumping pressure) and then de-energized. The flushing overflow valve 8 reopens, and the working pressure of the replenishing oil pump 1 is once again equal to P1 + ΔP3 + ΔP4. The replenishing overflow valve 2 closes synchronously. In this example, t1 is preferably 400ms.

[0082] This shows that:

[0083] 1. Under the condition of waiting for materials, the flow of the oil replenishment pump 1 no longer passes through the oil replenishment overflow valve 2, but flows back to the oil tank 3 through the neutral position of the flushing reversing valve 7 and the flushing overflow valve 8. The working pressure of the oil replenishment pump 1 can be reduced from 34 bar to 12 bar, and the power consumption can be reduced by about 2.9 kW, which is about 65%.

[0084] 2. During the pumping operation, in the normal movement phase of the pumping cylinder, the flow rate of the replenishing pump 1 flows back to the hydraulic oil tank 3 through the working position of the flushing directional valve 7 and the flushing relief valve 8. The working pressure of the replenishing pump 1 can be reduced from 34 bar to 13-17 bar (depending on the flow rate), and the power consumption can be reduced by up to 5.8-7.1 kW, a reduction of approximately 50-62%.

[0085] 3. During the pumping operation, when the pumping cylinder reverses direction, the flushing overflow valve 8 is electrically closed, and the flow of the replenishing oil pump 1 still flows back to the oil tank 3 through the replenishing oil overflow valve 2. The working pressure of the replenishing oil pump 1 rises again to 34 bar, and the working pressure on the low-pressure side of the two working oil ports of the main pump rises synchronously, which can effectively prevent the main pump from being damaged by cavitation.

[0086] 4. Throughout the entire life cycle of the pump truck, the set pressure of the flushing overflow valve 8 will no longer change with the working time of the pump truck. The flushing flow rate will remain basically consistent under the pumping conditions of the pump truck, which can avoid hydraulic system overheating failure due to abnormal flushing flow rate.

[0087] In the above implementation process, the control system 16 sends a control signal to the solenoid directional valve 17, and then the solenoid directional valve 17 controls the flushing overflow valve 8 to open or close according to the control signal. This allows for secondary adjustment of the working pressure of the replenishing pump 1 through the flushing overflow valve 8, reducing the power consumption of the replenishing pump 1 by 65% ​​in the waiting condition and by 50-62% in the pumping condition during the pumping cylinder movement phase. By isolating the pilot chamber of the flushing overflow valve 8 from the return oil pressure, the flushing flow rate remains basically consistent throughout the pump truck's entire life cycle, avoiding hydraulic system overheating failures caused by abnormal flushing flow rate. The solenoid directional valve 17 performs electronic overriding control over the opening and closing of the flushing overflow valve 8, increasing the replenishing oil pressure during the pumping cylinder reversing phase in the pumping condition, preventing damage to the main pump from cavitation. By simply changing the neutral position function of the flushing directional valve 7 and adding the solenoid directional valve 17 to provide control oil to the flushing relief valve 8, the opening and closing of the flushing relief valve 8 can be controlled. In turn, the replenishment pressure can be controlled to reduce the power consumption of the replenishment pump 1 throughout the entire working cycle, thereby reducing the power loss of the closed hydraulic system, improving the system's working efficiency, and making the control simple and convenient.

[0088] This also includes the following steps:

[0089] First: The control system 16 acquires the hydraulic oil temperature; in this embodiment, the control system 16 may acquire the hydraulic oil temperature by acquiring the temperature sensor installed in the oil tank 3.

[0090] Then: compare the hydraulic oil temperature with the preset temperature threshold to obtain the comparison result; there can be multiple preset temperature thresholds, which can be set according to the actual situation.

[0091] Finally, a control signal is generated based on the comparison results and sent to the solenoid directional valve 17.

[0092] The preset temperature thresholds include T1 and T2. The process of comparing the hydraulic oil temperature with the preset temperature thresholds to obtain a comparison result, and generating a control signal based on the comparison result and sending it to the solenoid directional valve 17 includes the following steps:

[0093] A1: Determine whether the hydraulic oil temperature is lower than T1. If yes, generate an energized control signal and send it to the solenoid directional valve 17; otherwise, execute A2.

[0094] A2: Determine whether the hydraulic oil temperature is less than or equal to T2. If so, generate a control signal to energize the solenoid directional valve 17 and send it to the solenoid directional valve 17. Determine whether to set the pump start. If so, keep the solenoid directional valve 17 energized. If not, repeat the cycle to determine whether the hydraulic oil temperature is less than or equal to T2. If the hydraulic oil temperature is greater than T2, execute A3.

[0095] A3: Determine whether the pumping start is set. If not, generate a control signal to de-energize the electromagnetic directional valve 17 and send it to the electromagnetic directional valve 17; if so, execute A4.

[0096] A4: Determine whether there is a commutation signal. If not, generate a control signal to de-energize the electromagnetic directional valve 17 and send it to the electromagnetic directional valve 17; if there is, generate a control signal to energize the electromagnetic directional valve 17 and send it to the electromagnetic directional valve 17, and start the timer t. Continuously judge the value of the timer until t is greater than or equal to the preset value t1, then end.

[0097] For example: In the above example, the temperature thresholds include T1 = 20°C and T2 = 40°C, T1 < T2. In winter, after the concrete pump truck is started for the first time, the control system 16 detects the hydraulic oil temperature through the oil temperature sensor 15. If the initial oil temperature is lower than T1, the control system 16 controls the electromagnetic directional valve 17 to be energized. The directional valve works in the lower position, the flushing relief valve 8 is closed, and all the oil replenishing flow overflows and generates heat at a pressure of 34 bar through the oil replenishing relief valve 2 to quickly increase the system oil temperature, and the concrete pump truck is not allowed to pump. When the system oil temperature rises to T1, the system allows the pumping operation to start. When the oil temperature has not reached the appropriate temperature T2, the electromagnetic directional valve 17 remains energized, and the oil replenishing flow continues to overflow and generate heat at a pressure of 34 bar through the oil replenishing relief valve 2 to quickly raise the oil temperature to the appropriate temperature. The specific logic block diagram is as Figure 4 shown. First, judge whether the hydraulic oil temperature is less than or equal to T1. If so, generate a control signal to energize the electromagnetic directional valve 17. After the electromagnetic directional valve 17 is energized, the pumping start is not allowed. If the hydraulic oil temperature is greater than T1, further judge whether the hydraulic oil temperature is less than or equal to T2. If so, generate a control signal to energize the electromagnetic directional valve 17, and then judge whether the pumping start is set. If so, keep the electromagnetic directional valve 17 energized. If not, judge again whether the hydraulic oil temperature is less than or equal to T2; if the hydraulic oil temperature is greater than T2, judge whether the pumping start is set. If not, generate a control signal to de-energize the electromagnetic directional valve 17. If so, further judge whether there is a commutation signal. If not, generate a control signal to de-energize the electromagnetic directional valve 17, and the electromagnetic directional valve 17 is de-energized; if there is, generate a control signal to energize the electromagnetic directional valve 17, the electromagnetic directional valve 17 is energized, and start the timer t. Continuously judge the value of the timer until t is greater than or equal to the preset value t1, then end.

[0098] By detecting the hydraulic system oil temperature and electronically overriding the closure of the flushing relief valve 8, it is possible to quickly raise the oil temperature to the appropriate temperature in a low-temperature environment, improving the construction efficiency of construction machinery.

[0099] Based on the same inventive concept, this embodiment also provides an engineering machinery, including an actuator; and the aforementioned oil replenishment pressure control device, wherein the system oil circuit 13 is used to drive the actuator. The engineering machinery includes pumping equipment. Understandably, the pumping equipment may include pump trucks, trailer pumps, vehicle-mounted pumps, etc.

[0100] Figure 3 This is a flowchart illustrating the steps of a method for controlling replenishment pressure in one embodiment. It should be understood that, although... Figure 3 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 3 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0101] In summary, the oil replenishment pressure control device, method, and engineering machinery provided in this embodiment, under the waiting-for-material condition, the flow rate of the oil replenishment pump 1 no longer flows through the oil replenishment overflow valve 2, but instead flows back to the oil tank 3 through the neutral position of the flushing directional valve 7 and the flushing overflow valve 8. The working pressure of the oil replenishment pump 1 can be reduced from 34 bar to 12 bar, and the power consumption can be reduced by approximately 2.9 kW, a reduction of approximately 65%. Under the pumping condition, during the normal movement phase of the pumping cylinder, the flow rate of the oil replenishment pump 1 flows back to the hydraulic oil tank 3 through the working position of the flushing directional valve 7 and the flushing overflow valve 8. The working pressure of the oil replenishment pump 1 can be reduced from 34 bar to 13-17 bar (varying with flow rate), and the power consumption can be reduced by up to 5.8-7.1 kW, a reduction of approximately 50-62%. During pumping operation, when the pumping cylinder reverses direction, the flushing relief valve 8 is electrically closed. The flow from the replenishing pump 1 continues to flow back to the oil tank 3 through the replenishing relief valve 2, and the working pressure of the replenishing pump 1 rises again to 34 bar. The working pressure on the low-pressure side of the two working ports of the main pump rises synchronously, effectively preventing damage from cavitation in the main pump. Throughout the pump truck's lifespan, the set pressure of the flushing relief valve 8 remains unchanged regardless of the pump truck's operating time. The flushing flow rate remains essentially consistent during pumping operations, preventing hydraulic system overheating due to abnormal flushing flow. In low-temperature environments, the flushing relief valve 8 is electrically closed, and the flow from the replenishing pump 1 continues to flow through the replenishing relief valve 2 at a pressure of 34 bar, rapidly raising the oil temperature to a suitable level and improving the pump truck's operational efficiency. Because the flushing overflow valve 8 is equipped with a fixed mechanical back pressure, even if the valve gets stuck, the back pressure, the pressure difference at the valve port of the flushing reversing valve 7, and the pressure difference at the replenishing oil check valve can ensure that the replenishing oil pump 1 will operate at a pressure higher than 12 bar, so that the working oil port pressure of the closed main pump 4 is not lower than the usage requirements, and the closed main pump 4 has good reliability.

[0102] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0103] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A replenishing pressure control device for a closed-loop hydraulic system, characterized in that, The replenishment pressure control device includes: a system oil circuit, a replenishment circuit, a flushing circuit, and a control system; The replenishment circuit includes a replenishment pump and a replenishment overflow valve. The replenishment pump is used to pump oil from the oil tank to the system oil circuit. The replenishment overflow valve is used to regulate the pressure of the oil pumped out of the oil tank by the replenishment pump. The flushing circuit includes a flushing directional valve, a flushing overflow valve, and a solenoid directional valve. The flushing directional valve has a fully open oil port in its neutral position. The flushing directional valve is connected to the system oil circuit and the flushing overflow valve, and the flushing overflow valve is connected to the oil tank. The solenoid directional valve is connected to the flushing overflow valve and is used to control the opening or closing of the flushing overflow valve according to the control signal issued by the control system, so as to control the pressure of the oil delivered by the replenishing pump. The electromagnetic reversing valve is used to control the pressure in the spring pilot chamber or the pressure in the pilot chamber opposite the spring chamber of the flushing overflow valve according to the control signal issued by the control system, so as to control the opening or closing of the flushing overflow valve.

2. The apparatus according to claim 1, characterized in that, It also includes a cooler disposed between the flushing overflow valve and the oil tank.

3. The apparatus according to claim 1, characterized in that, It also includes an oil temperature sensor, The oil temperature sensor is used to acquire the oil temperature in the oil tank and send it to the control system; The control system is used to generate a control signal based on the oil temperature in the oil tank and send it to the solenoid directional valve.

4. The apparatus according to claim 1, characterized in that, The system oil circuit includes a closed main pump, and the oil replenishment circuit also includes a servo valve. The oil replenishment pump is used to provide a pressure oil source to the servo valve. The servo valve is used to generate a pressure signal according to the control signal sent by the control system and send it to the closed main pump to control the direction of oil in the system oil circuit.

5. The apparatus according to claim 1, characterized in that, The oil replenishment circuit also includes multiple multi-functional valves, each of which is connected to the oil replenishment pump and the flushing reversing valve, and the multiple multi-functional valves are used to provide flushing flow oil source for the flushing overflow valve.

6. A method for controlling replenishing oil pressure, applied to the replenishing oil pressure control device according to any one of claims 1 to 5, characterized in that, Includes the following steps: The control system sends a control signal to the solenoid directional valve; The electromagnetic reversing valve controls the flushing overflow valve to open or close according to the control signal, thereby controlling the oil replenishment pressure. The electromagnetic reversing valve controls the flushing overflow valve to open or close according to the control signal, including: The electromagnetic reversing valve controls the pressure in the spring pilot chamber or the pressure in the pilot chamber opposite the spring chamber of the flushing overflow valve according to the control signal issued by the control system, so as to control the opening or closing of the flushing overflow valve.

7. The method according to claim 6, characterized in that, It also includes the following steps: The control system obtains the hydraulic oil temperature; The hydraulic oil temperature is compared with a preset temperature threshold to obtain the comparison result; A control signal is generated based on the comparison results and sent to the solenoid directional valve.

8. The method according to claim 7, characterized in that, The preset temperature thresholds include T1 and T2. The process of comparing the hydraulic oil temperature with the preset temperature thresholds to obtain a comparison result, and generating a control signal based on the comparison result and sending it to the solenoid directional valve, includes the following steps: A1: Determine if the hydraulic oil temperature is lower than T1. If yes, generate an energized control signal and send it to the solenoid directional valve; otherwise, execute A2. A2: Determine whether the hydraulic oil temperature is less than or equal to T2. If yes, generate a control signal to energize the solenoid directional valve and send it to the solenoid directional valve. Determine whether to set the pump start. If yes, keep the solenoid directional valve energized. If not, repeat the cycle to determine whether the hydraulic oil temperature is less than or equal to T2. If the hydraulic oil temperature is greater than T2, execute A3. A3: Determine whether pump start is enabled. If not, generate a control signal to de-energize the solenoid directional valve and send it to the solenoid directional valve. If yes, execute A4. A4: Determine if there is a reversing signal. If not, generate a control signal to de-energize the solenoid reversing valve and send it to the solenoid reversing valve. If there is a reversing signal, generate a control signal to energize the solenoid reversing valve and send it to the solenoid reversing valve. Start timer t and repeatedly check the value of the timer until t is greater than or equal to the preset value t1, then end.

9. An engineering machinery, characterized in that, It includes an actuator and a replenishing pressure control device according to any one of claims 1 to 5, wherein the replenishing pressure control device drives the actuator through the system oil circuit.

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