A voltage-stabilizing fuel tank device for construction machinery

Abstract

The present invention relates to the technical field of hydraulic oil tanks, and particularly to a pressure-stabilizing oil tank device for construction machinery, which includes a closed oil tank, a two-way air valve, a detection component, a pressure control component, and a central control module. In the present invention, a partition baffle is arranged inside the closed oil tank to divide the closed oil tank into an oil storage area and a pressure control area, and a pressure control component is arranged to control the extension and contraction operation of the oil pushing plug in the pressure control area, adjust the air pressure in the oil tank by changing the actual volume of the closed oil tank, and a two-way air valve is arranged to assist in adjusting the pressure in the closed oil tank, improve the range of pressure adjustment, and a detection component is arranged to detect the real-time parameters in the closed oil tank. The central control module intelligently selects the standard range and controls the oil pushing plug and the two-way air valve to adjust the pressure adjustment method, maintaining the internal pressure of the closed oil tank stable and reducing the generation of hydraulic oil bubbles on the basis of ensuring the rapid heat dissipation of the hydraulic oil temperature and allowing less gas to enter the oil tank.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic oil tanks, and particularly to a pressure-stabilizing oil tank device for construction machinery. Background Art

[0002] Construction machinery is an important part of the equipment industry and is the necessary mechanical equipment for various comprehensive mechanized construction projects required for construction engineering. It is widely used in fields such as transportation construction, energy industry construction and production, raw material industry construction and production in mines, forestry and water conservancy construction, industrial and civil construction, urban construction, environmental protection, etc. Construction machinery mostly uses a hydraulic system for corresponding driving, uses hydraulic oil to transmit power, and the hydraulic oil needs to be carried by a special hydraulic oil tank for filtering, heat dissipation and other treatments of the hydraulic oil.

[0003] Chinese Patent Publication No.: CN103629170A discloses a pressure-stabilizing oil tank device for construction machinery; its technical point is to start an electric air pump, and compressed air enters the storage oil tank through an air pipeline to keep the air pressure in the hydraulic oil tank stable. It can be seen that the method of inputting air into the oil tank to ensure the stability of the oil tank pressure in the prior art has great drawbacks. Not only is the hydraulic oil in the oil tank more likely to combine with air to generate a large number of bubbles due to the circulation of gas, but also the hydraulic oil is in contact with the continuously circulating air. Not only is it difficult to control impurities, but it is easier for the hydraulic oil to deteriorate and oxidize. Moreover, the input of air will generate a heat-insulating layer in the oil tank, which is not conducive to the heat dissipation of the hydraulic oil in the oil tank, and greatly reduces the service life of the hydraulic oil. Summary of the Invention

[0004] Therefore, the present invention provides a pressure-stabilizing oil tank device for construction machinery to overcome the problems that the hydraulic oil in the pressure-stabilizing oil tank in the prior art is prone to generate bubbles and the pressure control lacks accuracy.

[0005] To achieve the above object, the present invention provides a pressure-stabilizing oil tank device for construction machinery, including

[0006] A closed oil tank, which is a closed shell. An oil inlet is provided at the top of the closed oil tank, and a filter screen is provided below the oil inlet for filtering the hydraulic oil added through the oil inlet. A return oil port is also provided at the top of the closed oil tank, and a return oil filter element is provided at the bottom of the return oil port for filtering the returned hydraulic oil. The return oil filter element extends only inside the closed oil tank. An oil outlet is provided at the bottom of the closed oil tank, and an electric ball valve is provided in the oil outlet for controlling the oil outlet of the oil outlet. A partition baffle is provided inside the closed oil tank, and the partition baffle divides the closed oil tank into an oil storage area and a pressure control area;

[0007] A two-way air valve is provided on the side wall of the closed fuel tank to control the entry or discharge of gas from the closed fuel tank. An oxygen-permeable filter element is provided inside the two-way air valve, and the oxygen-permeable filter element is used to filter impurities and oxygen in the external air;

[0008] A detection assembly includes a pressure gauge, a thermometer, and a liquid level gauge. The pressure gauge is used to detect the real-time air pressure inside the closed fuel tank. The thermometer is used to detect the real-time temperature of the hydraulic oil in the closed fuel tank. The liquid level gauge is used to detect the real-time liquid level height of the hydraulic oil in the closed fuel tank. The pressure gauge, the thermometer, and the liquid level gauge are respectively connected to a display instrument, and the display instrument is provided on the side wall outside the closed fuel tank;

[0009] A pressure control assembly is provided at the bottom of the closed fuel tank. The pressure control assembly includes an oil pushing plug. The oil pushing plug is arranged inside the pressure control area. The side edge of the oil pushing plug is in closed fit with the inner wall of the pressure control area of the closed fuel tank and can slide. The oil pushing plug is connected to one end of an oil pushing rod. The oil pushing rod can drive the oil pushing plug to slide in the pressure control area through expansion and contraction to push out the hydraulic oil in the pressure control area. The other end of the oil pushing rod passes through the bottom of the closed fuel tank and is connected to a driving member, and the driving member is used to drive the oil pushing rod to expand and contract;

[0010] A central control module is respectively connected to the electric ball valve, the two-way air valve, the detection assembly, and the pressure control assembly. A preset liquid level height matrix and a standard pressure matrix are provided inside the central control module. The central control module can select the standard air pressure of the closed fuel tank corresponding to this state in the standard pressure matrix according to the comparison result between the real-time liquid level height detected by the liquid level gauge and the preset liquid level height matrix. The central control module will judge the real-time air pressure detected by the pressure gauge through the difference between the standard air pressure and the standard air pressure set inside the central control module, and control the oil pushing plug to advance or contract and control the two-way air valve to adjust the real-time pressure inside the closed fuel tank according to the real-time air pressure inside the closed fuel tank and the real-time temperature of the hydraulic oil.

[0011] Further, a preset liquid level height matrix H (H1, H2, H3) is provided inside the central control module, where H1 < H2 < H3. A standard pressure matrix P (P1, P2, P3, P4) is also provided inside the central control module, where P1 < P2 < P3 < P4. The liquid level gauge detects the real-time liquid level height Hs of the hydraulic oil in the closed fuel tank, and the central control module compares the real-time liquid level height Hs of the hydraulic oil in the closed fuel tank with the preset liquid level height matrix H.

[0012] When Hs < H1, the central control module selects P1 as the standard air pressure of the closed fuel tank in the standard pressure matrix P;

[0013] When H1 ≤ Hs < H2, the central control module selects P2 in the standard pressure matrix P as the standard air pressure of the closed fuel tank;

[0014] When H2 ≤ Hs < H3, the central control module selects P3 in the standard pressure matrix P as the standard air pressure of the closed fuel tank;

[0015] When Hs ≥ H3, the central control module selects P4 in the standard pressure matrix P as the standard air pressure of the closed fuel tank.

[0016] Further, a standard air pressure difference ΔPb is set in the central control module. When the central control module completes the selection of the standard air pressure Pi, where i = 1, 2, 3, 4, the pressure gauge will detect the real-time air pressure Ps inside the closed fuel tank and transmit the detection result to the central control module. The central control module calculates the real-time air pressure difference ΔPs according to the standard air pressure Pi and the real-time air pressure Ps, ΔPs = |Pi - Ps|. The central control module compares the real-time air pressure difference ΔPs with the standard air pressure difference ΔPb.

[0017] When ΔPs ≤ ΔPb, the central control module determines that the real-time air pressure difference inside the closed fuel tank does not exceed the standard air pressure difference, and the central control module does not adjust the air pressure inside the closed fuel tank;

[0018] When ΔPs > ΔPb, the central control module determines that the real-time air pressure difference inside the closed fuel tank has exceeded the standard air pressure difference, and the central control module compares the standard air pressure with the real-time air pressure to adjust the air pressure inside the closed fuel tank.

[0019] Further, when the central control module determines that the real-time air pressure difference inside the closed fuel tank has exceeded the standard air pressure difference, the central control module compares the real-time air pressure Ps inside the closed fuel tank with the standard air pressure Pi.

[0020] When Ps < Pi, the central control module determines that the real-time air pressure inside the closed fuel tank is lower than the standard air pressure, and the central control module will adjust the air pressure inside the closed fuel tank according to the advancing distance of the oil pushing plug;

[0021] When Ps > Pi, the central control module determines that the real-time air pressure inside the closed fuel tank is higher than the standard air pressure, and the central control module will determine the real-time temperature of the hydraulic oil inside the closed fuel tank to determine the method of adjusting the air pressure inside the closed fuel tank.

[0022] Furthermore, a maximum pushing distance La of the oil pushing plug is set in the central control module. When the central control module determines that the real-time air pressure inside the closed fuel tank is lower than the standard air pressure, the central control module obtains the real-time pushing distance Ls that the oil pushing plug has advanced. The central control module compares the real-time pushing distance Ls of the oil pushing plug with the maximum pushing distance La.

[0023] When Ls≥La, the central control module determines that the real-time pushing distance of the oil pushing plug has reached the maximum pushing distance, and the central control module will control the two-way air valve to adjust the air inside the closed fuel tank.

[0024] When Ls<La, the central control module determines that the real-time pushing distance of the oil pushing plug has not reached the maximum pushing distance. The central control module will control the driving member to drive the oil pushing rod to extend, pushing the oil pushing plug to advance into the pressure control area. The advancing distance is Le, and Le = Ls×[1 + (Pi - Ps) / Pi] - Ls. After the central control module completes the adjustment of the oil pushing plug, the liquid level gauge detects the real-time liquid level height of the hydraulic oil in the closed fuel tank after adjustment. The central control module repeats the above operations of selecting the standard air pressure according to the real-time liquid level height and determining and adjusting the real-time air pressure until the central control module determines that the difference between the real-time air pressures in the closed fuel tank after adjustment does not exceed the standard air pressure difference, and then the central control module completes the adjustment of the air pressure inside the closed fuel tank.

[0025] Furthermore, when the central control module determines that the real-time pushing distance of the oil pushing plug has not reached the maximum pushing distance, the central control module controls the oil pushing plug to advance, and the advancing distance is Le. The central control module will calculate the actual total advancing distance Lr according to the calculated advancing distance Le and the real-time pushing distance Ls of the oil pushing plug, and Lr = Le + Ls. The central control module compares the actual total advancing distance Lr with the maximum pushing distance La.

[0026] When Lr≤La, the central control module determines that the actual total advancing distance of the oil pushing plug does not exceed the maximum pushing distance, and the central control module does not adjust the control process of the oil pushing plug.

[0027] When Lr>La, the central control module determines that the actual total advancing distance of the oil pushing plug has exceeded the maximum pushing distance. The central control module will control the driving member to drive the oil pushing rod to extend, pushing the oil pushing plug to advance into the pressure control area, and correct the advancing distance to Le’, where Le’ = La - Ls.

[0028] Further, when the central control module determines that the real-time propulsion distance of the oil pushing plug has reached the maximum propulsion distance, the central control module will control the two-way air valve to open. The two-way air valve will conduct the air outside the closed fuel tank to the inside of the closed fuel tank. The pressure gauge will detect the real-time air pressure Ps' inside the closed fuel tank in the open state of the two-way air valve, and calculate the real-time air pressure difference ΔPs' in the open state of the two-way air valve according to the standard air pressure Pi. ΔPs' = |Pi - Ps'|. The central control module will compare the real-time air pressure difference ΔPs' with the standard air pressure difference ΔPb until ΔPs' ≤ ΔPb, and then the central control module will control the two-way air valve to close, completing the adjustment of the pressure inside the closed fuel tank.

[0029] Further, the standard working temperature Tb of the hydraulic oil inside the closed fuel tank is set in the central control module. When the central control module determines that the real-time air pressure inside the closed fuel tank is higher than the standard air pressure, the thermometer will detect the real-time temperature Ts of the hydraulic oil inside the closed fuel tank and transmit the detection result to the central control module. The central control module will compare the real-time temperature Ts of the hydraulic oil with the standard working temperature Tb.

[0030] When Ts ≤ Tb, the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank has not exceeded the standard working temperature. The central control module will control the two-way air valve to open. The two-way air valve will conduct the air inside the closed fuel tank to the outside of the closed fuel tank. The pressure gauge will detect the real-time air pressure Ps'' inside the closed fuel tank in the open state of the two-way air valve, and calculate the real-time air pressure difference ΔPs'' in the open state of the two-way air valve according to the standard air pressure Pi. ΔPs'' = |Pi - Ps''|. The central control module will compare the real-time air pressure difference ΔPs'' with the standard air pressure difference ΔPb until ΔPs'' ≤ ΔPb, and then the central control module will control the two-way air valve to close, completing the adjustment of the pressure inside the closed fuel tank.

[0031] When Ts > Tb, the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank has exceeded the standard working temperature. The central control module obtains the real-time propulsion distance Ls that the oil pushing plug has advanced in the pressure control area. The central control module will control the driving member to drive the push rod to contract, pulling the oil pushing plug to contract inside the pressure control area, and the contraction distance is Lc, Lc = Ls. The liquid level gauge detects the real-time liquid level height of the hydraulic oil in the adjusted closed fuel tank. The central control module repeats the above determination based on the real-time liquid level height, selects the standard air pressure, determines the real-time air pressure inside the closed fuel tank, and adjusts the pressure inside the closed fuel tank by controlling the gas inlet or outlet of the two-way air valve.

[0032] Furthermore, the central control module is also provided with the maximum working temperature and the maximum over-standard duration of the hydraulic oil. When the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank has exceeded the standard working temperature, the central control module starts the over-temperature timing of the hydraulic oil. When the duration of the over-temperature timing of the hydraulic oil is higher than the maximum over-standard duration, or when the real-time temperature of the hydraulic oil is higher than the maximum working temperature, the central control module controls the electric ball valve to close and determines that the external hydraulic system connected to the closed fuel tank needs to be restarted.

[0033] Furthermore, the inner wall of the pressure control area of the closed fuel tank is provided with a chamfer, and the partition baffle is provided with a check valve port at the connection with the bottom of the closed fuel tank, so as to discharge the hydraulic oil leaked under the push oil plug to the oil storage area when the push oil plug contracts.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: by arranging a partition baffle inside the closed fuel tank to divide the closed fuel tank into an oil storage area and a pressure control area, and arranging a pressure control component to control the elongation and contraction of the push oil plug in the pressure control area, the actual volume of the closed fuel tank is changed to adjust the air pressure in the fuel tank, and a two-way air valve is arranged to assist in adjusting the pressure in the closed fuel tank, so as to improve the range of pressure adjustment. At the same time, an over-oxygen filter element is arranged inside the two-way air valve to filter impurities and oxygen in the external air, further ensuring the performance of the hydraulic oil, and a detection component is arranged to detect the real-time air pressure, the real-time temperature of the hydraulic oil and the real-time liquid level height of the hydraulic oil inside the closed fuel tank respectively. The central control module intelligently selects the standard range and controls the push oil plug and the two-way air valve to adjust the pressure adjustment method, so as to accurately maintain the internal pressure of the closed fuel tank stable on the basis of ensuring the rapid heat dissipation of the hydraulic oil temperature and less gas entering the fuel tank, reduce the generation of hydraulic oil bubbles, thereby maintaining the stability of the self-pressure of the hydraulic oil and ensuring the continuous and efficient operation of the external hydraulic system.

[0035] In particular, by setting a preset liquid level height matrix and a standard pressure matrix in the central control module, comparing and determining the real-time liquid level height of the hydraulic oil in the closed fuel tank with the preset liquid level height matrix, and selecting the corresponding standard pressure in the standard pressure matrix. Since the operation of the multi-way hydraulic system of construction machinery will have a greater impact on the liquid level height in the hydraulic fuel tank, and at the same time, the arrangement of the push oil plug in the closed fuel tank will also have a direct impact on the liquid level height of the hydraulic oil in the closed fuel tank, therefore, selecting the corresponding standard air pressure according to the real-time liquid level height of the hydraulic oil in the closed fuel tank greatly ensures the original pressure state in the closed fuel tank and ensures the stable operation of the external hydraulic system.

[0036] In particular, by setting a standard air pressure difference within the central control module, the allowable pressure fluctuation range within the closed fuel tank is controlled. The real-time air pressure difference is calculated to represent the fluctuation of the real-time air pressure relative to the standard air pressure, and a judgment is made on it. When the real-time air pressure difference does not exceed the standard air pressure difference, it indicates that the real-time air pressure within the fuel tank is within the set range, so the internal pressure is not adjusted. When the real-time air pressure difference has exceeded the standard air pressure difference, the specific pressure situation within the closed fuel tank is determined by comparing the standard air pressure with the real-time air pressure to ensure the stability of the internal pressure of the closed fuel tank.

[0037] Furthermore, by comparing the real-time air pressure inside the closed fuel tank with the standard air pressure, the internal pressure situation of the closed fuel tank is determined. When the real-time air pressure is lower than the standard air pressure, it indicates that a pressure boosting operation needs to be carried out inside the fuel tank. When the real-time air pressure is higher than the standard air pressure, it indicates that a pressure reducing operation needs to be carried out inside the fuel tank. Since hydraulic oil is prone to combine with the internal control of the fuel tank both at lower and higher pressures, generating a large number of bubbles in the hydraulic oil. When this part of the hydraulic oil is transported to the external hydraulic end, it will seriously affect the self-pressure of the hydraulic oil, thereby reducing the operating efficiency of the construction machinery. Therefore, the pressure needs to be adjusted when the internal pressure of the closed fuel tank is too large or too small to reduce the generation of bubbles in the hydraulic oil.

[0038] In particular, when the real-time air pressure inside the closed fuel tank is lower than the standard air pressure, the central control module will increase the internal air pressure by pushing the oil plug to reduce the overall volume inside the closed fuel tank, and judge the real-time position of the oil plug in the pressure control area to determine whether the oil plug has reached the limit and cannot be pushed further. When the oil plug reaches the limit, the internal pressure of the closed fuel tank is flexibly adjusted by controlling the two-way air valve. When the oil plug has not reached the limit, the central control module will set the pushing distance of the oil plug according to the selected standard air pressure and real-time air pressure, and control the driving part to drive the push rod to extend to adjust the internal pressure of the closed fuel tank, reduce the generation of hydraulic oil bubbles, and ensure the stability of the pressure inside the closed fuel tank.

[0039] Furthermore, before the central control module controls the oil plug to be pushed, by calculating the actual total pushing distance and comparing it with the maximum pushing distance, it is judged whether the oil plug will reach the limit position halfway during this pushing process. When the actual total pushing distance has exceeded the maximum pushing distance, the central control module will control the oil plug to reach the limit position, and re-select the standard pressure for judgment according to the adjusted real-time liquid level height of the hydraulic oil, making the most of the oil plug for pressure adjustment, reducing the entry of external air, and at the same time reducing the generation of bubbles in the hydraulic oil.

[0040] Furthermore, by opening the two-way air valve to suck external air into the closed fuel tank, the real-time air pressure inside the closed fuel tank can be quickly adjusted. Through the real-time detection of the pressure gauge and the real-time determination of the central control module, when the real-time air pressure difference reaches the standard air pressure difference, the two-way air valve is promptly closed to prevent excessive air from entering the closed fuel tank and affecting the pressure balance again, and also to avoid the formation of more bubbles due to the excessive air combining with the hydraulic oil, which affects the performance of the hydraulic oil.

[0041] In particular, when the central control module determines that the real-time air pressure inside the closed fuel tank is higher than the standard air pressure, the thermometer will detect the real-time temperature of the hydraulic oil in the closed fuel tank. The central control module will compare the real-time temperature of the hydraulic oil with the standard working temperature to determine whether the pressure in the fuel tank has a significant impact on the temperature of the hydraulic oil. When the real-time temperature of the hydraulic oil does not exceed the standard working temperature, it indicates that the hydraulic oil can meet the normal usage requirements. Therefore, the pressure inside the closed fuel tank is directly adjusted by opening the two-way air valve. When the real-time temperature of the hydraulic oil has exceeded the standard working temperature, it indicates that the hydraulic oil in the closed fuel tank needs to be cooled. By retracting the oil pushing plug to the lower limit, the actual volume inside the closed fuel tank is increased. On the basis of reducing the air pressure inside the closed fuel tank, the contact area between the hydraulic oil and the closed fuel tank is increased to improve the heat dissipation effect, and the pressure is further adjusted through the two-way air valve to further maintain the pressure stability inside the closed fuel tank.

[0042] Furthermore, by setting the maximum working temperature and the maximum over-standard duration in the central control module, safety protection is provided for the hydraulic oil and the fuel tank as a whole. At the same time, by controlling the electric ball valve to close and determining the need for restart by the central control module, reminder indicator lights or other display devices can be set at the specific operation end to display the determination results of the central control module, further ensuring the safety of the pressure stabilizing fuel tank device and avoiding the long-term high-temperature operation of the hydraulic oil, thereby improving the service life of the hydraulic oil.

[0043] In particular, chamfers are provided on the inner wall of the pressure control area to ensure the smoothness of the cross-section of the pressure control area, improving the sealing performance between the oil pushing plug and the inner wall of the pressure control area. At the same time, a one-way valve port is provided at the position of the partition baffle close to the fuel tank bottom plate, which can discharge the hydraulic oil leaking from the lower part of the oil pushing plug to the oil storage area. This not only ensures the stability of the available hydraulic oil volume inside the closed fuel tank, but also ensures that when the oil pushing plug contracts, the hydraulic oil leaking from the lower part is squeezed, reducing the movable space of the oil pushing plug and avoiding the leakage of hydraulic oil at the connection between the oil pushing rod and the closed fuel tank. Description of the Drawings

[0044] Figure 1 It is a schematic structural diagram of the pressure stabilizing fuel tank device of the construction machinery described in this embodiment;

[0045] Figure 2This is a schematic structural diagram of the cross-section of the closed fuel tank in this embodiment. Detailed implementation manners

[0046] In order to make the objectives and advantages of the present invention clearer, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0047] The preferred implementation manners of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0048] It should be noted that in the description of the present invention, the terms indicating directions or positional relationships such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0049] In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0050] Please refer to Figure 1 and Figure 2 as shown, wherein, Figure 1 This is a schematic structural diagram of the pressure-stabilizing fuel tank device for construction machinery in this embodiment. Figure 2 This is a schematic structural diagram of the cross-section of the closed fuel tank in this embodiment. This embodiment discloses a pressure-stabilizing fuel tank device for construction machinery, including a closed fuel tank 1, an oil inlet 101, a filter screen 102, an oil return port 103, an oil return filter element 104, an oil outlet 105, an electric ball valve 106, a partition baffle 107, a one-way valve port 108, an oil storage area 11, a pressure control area 12, a two-way gas valve 2, a peroxide filter element 201, a detection component 3, a pressure gauge 301, a thermometer 302, a liquid level gauge 303, a display instrument 304, a pressure control component 4, a push oil plug 401, a push oil rod 402, a driving member 403, and a central control module (not shown in the figure). Among them,

[0051] Closed fuel tank 1, which is an enclosed housing. An oil inlet 101 is provided at the top of the closed fuel tank 1. A filter screen 102 is provided below the oil inlet 101. The filter screen 102 is used to filter the hydraulic oil added through the oil inlet 101. A return oil port 103 is also provided at the top of the closed fuel tank 1. A return oil filter element 104 is provided at the bottom of the return oil port 103 to filter the returned hydraulic oil. The return oil filter element 104 extends into the interior of the closed fuel tank. An oil outlet 105 is provided at the bottom of the closed fuel tank 1. An electric ball valve 106 is provided in the oil outlet 105 to control the oil discharge from the oil outlet 105. A partition baffle 107 is provided in the closed fuel tank 1. The partition baffle 107 divides the closed fuel tank 1 into an oil storage area 11 and a pressure control area 12;

[0052] Two-way air valve 2, which is provided on the side wall of the closed fuel tank 1 to control the entry or discharge of gas from the closed fuel tank 1. An oxygen-permeable filter element 201 is provided inside the two-way air valve 2. The oxygen-permeable filter element 201 is used to filter impurities and oxygen in the external air;

[0053] Detection assembly 3, which includes a pressure gauge 301, a thermometer 302, and a liquid level gauge 303. The pressure gauge 301 is used to detect the real-time air pressure inside the closed fuel tank 1. The thermometer 302 is used to detect the real-time temperature of the hydraulic oil in the closed fuel tank 1. The liquid level gauge 303 is used to detect the real-time liquid level height of the hydraulic oil in the closed fuel tank 1. The pressure gauge 301, the thermometer 302, and the liquid level gauge 303 are respectively connected to a display instrument 304. The display instrument 304 is provided on the side wall outside the closed fuel tank 1;

[0054] Pressure control assembly 4, which is provided at the bottom of the closed fuel tank 1. The pressure control assembly 4 includes a push oil plug 401. The push oil plug 401 is provided inside the pressure control area 12. The side edge of the push oil plug 401 is hermetically fitted and slidable with the inner wall of the pressure control area 12 of the closed fuel tank 1. The push oil plug 401 is connected to one end of a push oil rod 402. The push oil rod 402 can drive the push oil plug 401 to slide inside the pressure control area 12 through expansion and contraction to push out the hydraulic oil in the pressure control area 12. The other end of the push oil rod 402 passes through the bottom of the closed fuel tank 1 and is connected to a driving member 403. The driving member 403 is used to drive the push oil rod 402 to expand and contract;

[0055] The central control module is respectively connected to the electric ball valve 106, the two-way air valve 2, the detection component 3, and the pressure control component 4. A preset liquid level height matrix and a standard pressure matrix are set in the central control module. The central control module can select the standard air pressure of the closed fuel tank 1 corresponding to this state in the standard pressure matrix according to the comparison result between the real-time liquid level height detected by the liquid level gauge 303 and the preset liquid level height matrix. The central control module will judge the real-time air pressure detected by the pressure gauge 301 through the difference between the standard air pressure and the standard air pressure set inside the central control module, and control the push oil plug 401 to advance or retract and control the two-way air valve 2 to adjust the real-time pressure in the closed fuel tank 1 according to the real-time air pressure and the real-time temperature of the hydraulic oil inside the closed fuel tank 1.

[0056] The closed fuel tank 1 is divided into an oil storage area 11 and a pressure control area 12 by arranging a partition baffle 107 inside the closed fuel tank 1. The push oil plug 401 in the pressure control area 12 is controlled to extend and retract by setting the pressure control component 4, the air pressure in the fuel tank is adjusted by changing the actual volume of the closed fuel tank 1, and the two-way air valve 2 is set to assist in adjusting the pressure in the closed fuel tank 1 to increase the pressure adjustment range. At the same time, an oxygen filter element 201 is arranged inside the two-way air valve 2 to filter impurities and oxygen in the external air, further ensuring the performance of the hydraulic oil. The detection component 3 is set to detect the real-time air pressure, the real-time temperature of the hydraulic oil, and the real-time liquid level height of the hydraulic oil inside the closed fuel tank 1 respectively. The central control module intelligently selects the standard range and controls the push oil plug 401 and the two-way air valve 2 to adjust the pressure adjustment method, maintaining the stability of the internal pressure of the closed fuel tank 1 on the basis of ensuring the rapid heat dissipation of the hydraulic oil temperature and less gas entering the fuel tank, reducing the generation of hydraulic oil bubbles, thereby maintaining the stability of the self-pressure of the hydraulic oil and ensuring the continuous and efficient operation of the external hydraulic system.

[0057] Specifically, a preset liquid level height matrix H (H1, H2, H3) is set in the central control module, where H1 < H2 < H3. A standard pressure matrix P (P1, P2, P3, P4) is also set in the central control module, where P1 < P2 < P3 < P4. The liquid level gauge 303 detects the real-time liquid level height Hs of the hydraulic oil in the closed fuel tank 1, and the central control module compares the real-time liquid level height Hs of the hydraulic oil in the closed fuel tank 1 with the preset liquid level height matrix H.

[0058] When Hs < H1, the central control module selects P1 as the standard air pressure of the closed fuel tank 1 in the standard pressure matrix P;

[0059] When H1 ≤ Hs < H2, the central control module selects P2 as the standard air pressure of the closed fuel tank 1 in the standard pressure matrix P;

[0060] When H2 ≤ Hs < H3, the central control module selects P3 in the standard pressure matrix P as the standard air pressure of the closed fuel tank 1;

[0061] When Hs ≥ H3, the central control module selects P4 in the standard pressure matrix P as the standard air pressure of the closed fuel tank 1.

[0062] By setting a preset liquid level height matrix and a standard pressure matrix in the central control module, comparing and determining the real-time liquid level height of the hydraulic oil in the closed fuel tank 1 with the preset liquid level height matrix, and selecting the corresponding standard pressure in the standard pressure matrix. Since during the operation of the multi-way hydraulic system of construction machinery, it will have a great impact on the liquid level height in the hydraulic fuel tank, and at the same time, when the oil pushing plug 401 in the closed fuel tank 1 is pushed or retracted, it will also directly affect the liquid level height of the hydraulic oil in the closed fuel tank 1. Therefore, selecting the corresponding standard air pressure according to the real-time liquid level height of the hydraulic oil in the closed fuel tank 1 greatly guarantees the original pressure state in the closed fuel tank 1 and the stable operation of the external hydraulic system.

[0063] Specifically, a standard air pressure difference ΔPb is set in the central control module. When the central control module completes the selection of the standard air pressure Pi, where i = 1, 2, 3, 4, the pressure gauge 301 will detect the real-time air pressure Ps inside the closed fuel tank 1 and transmit the detection result to the central control module. The central control module calculates the real-time air pressure difference ΔPs according to the standard air pressure Pi and the real-time air pressure Ps, ΔPs = |Pi - Ps|. The central control module compares the real-time air pressure difference ΔPs with the standard air pressure difference ΔPb.

[0064] When ΔPs ≤ ΔPb, the central control module determines that the real-time air pressure difference in the closed fuel tank 1 does not exceed the standard air pressure difference, and the central control module does not adjust the air pressure inside the closed fuel tank 1;

[0065] When ΔPs > ΔPb, the central control module determines that the real-time air pressure difference in the closed fuel tank 1 has exceeded the standard air pressure difference, and the central control module compares the standard air pressure with the real-time air pressure to adjust the air pressure inside the closed fuel tank 1.

[0066] By setting a standard air pressure difference in the central control module, the allowable pressure fluctuation range in the closed fuel tank 1 is controlled. The real-time air pressure difference is calculated to represent the fluctuation of the real-time air pressure relative to the standard air pressure, and a judgment is made on it. When the real-time air pressure difference does not exceed the standard air pressure difference, it indicates that the real-time air pressure in the fuel tank is within the set range, so the internal pressure is not adjusted. When the real-time air pressure difference has exceeded the standard air pressure difference, the specific pressure condition in the closed fuel tank 1 is determined by comparing the standard air pressure with the real-time air pressure to ensure the stability of the internal pressure of the closed fuel tank 1.

[0067] Specifically, when the central control module determines that the real-time air pressure difference in the closed fuel tank 1 has exceeded the standard air pressure difference, the central control module compares the real-time air pressure Ps inside the closed fuel tank 1 with the standard air pressure Pi.

[0068] When Ps < Pi, the central control module determines that the real-time air pressure inside the closed fuel tank 1 is lower than the standard air pressure, and the central control module will adjust the air pressure inside the closed fuel tank 1 according to the advancing distance of the oil pushing plug 401.

[0069] When Ps > Pi, the central control module determines that the real-time air pressure inside the closed fuel tank 1 is higher than the standard air pressure, and the central control module will determine the real-time temperature of the hydraulic oil inside the closed fuel tank 1 to determine the method of adjusting the air pressure inside the closed fuel tank 1.

[0070] By comparing the real-time air pressure inside the closed fuel tank 1 with the standard air pressure, the internal pressure condition of the closed fuel tank 1 is determined. When the real-time air pressure is lower than the standard air pressure, it indicates that a pressure boosting operation needs to be carried out inside the fuel tank. When the real-time air pressure is higher than the standard air pressure, it indicates that a pressure reducing operation needs to be carried out inside the fuel tank. Since the hydraulic oil is prone to combine with the internal control of the fuel tank both at low and high pressures, generating a large number of bubbles in the hydraulic oil. When this part of the hydraulic oil is transported to the external hydraulic end, it will seriously affect the self-pressure of the hydraulic oil, thereby reducing the operating efficiency of the construction machinery. Therefore, it is necessary to adjust the pressure when the internal pressure of the closed fuel tank 1 is too large or too small to reduce the generation of bubbles in the hydraulic oil.

[0071] Specifically, the maximum advancing distance La of the oil pushing plug 401 is set in the central control module. When the central control module determines that the real-time air pressure inside the closed fuel tank 1 is lower than the standard air pressure, the central control module obtains the real-time advancing distance Ls that the oil pushing plug 401 has advanced, and the central control module compares the real-time advancing distance Ls of the oil pushing plug 401 with the maximum advancing distance La.

[0072] When Ls ≥ La, the central control module determines that the real-time advancement distance of the oil pushing plug 401 has reached the maximum advancement distance, and the central control module will control the two-way air valve 2 to adjust the air inside the closed fuel tank 1;

[0073] When Ls < La, the central control module determines that the real-time advancement distance of the oil pushing plug 401 has not reached the maximum advancement distance. The central control module will control the driving member 403 to drive the oil pushing rod 402 to elongate, pushing the oil pushing plug 401 into the pressure control area 12. The advancement distance is Le, and Le = Ls×[1 + (Pi - Ps) / Pi] - Ls. After the central control module completes the adjustment of the oil pushing plug 401, the liquid level gauge 303 detects the real-time liquid level height of the hydraulic oil in the closed fuel tank 1 after adjustment. The central control module repeats the above operations of selecting the standard air pressure according to the real-time liquid level height and determining and adjusting the real-time air pressure until the central control module determines that the adjusted real-time air pressure difference inside the closed fuel tank 1 does not exceed the standard air pressure difference, and then the central control module completes the adjustment of the air pressure inside the closed fuel tank 1.

[0074] When the real-time air pressure inside the closed fuel tank 1 is lower than the standard air pressure, the central control module will increase the internal air pressure by advancing the oil pushing plug 401 to reduce the overall volume inside the closed fuel tank 1, and determine the real-time position of the oil pushing plug 401 in the pressure control area 12 to determine whether the oil pushing plug 401 reaches the limit and cannot continue to advance. When the oil pushing plug 401 reaches the limit, the central control module will flexibly adjust the internal pressure of the closed fuel tank 1 by controlling the two-way air valve 2. When the oil pushing plug 401 does not reach the limit, the central control module will set the advancement distance of the oil pushing plug 401 according to the selected standard air pressure and the real-time air pressure, and control the driving member 403 to drive the oil pushing rod 402 to elongate to adjust the internal pressure of the closed fuel tank 1, reduce the generation of hydraulic oil bubbles, and ensure the stable pressure inside the closed fuel tank 1.

[0075] Specifically, when the central control module determines that the real-time advancement distance of the oil pushing plug 401 has not reached the maximum advancement distance, the central control module controls the oil pushing plug 401 to advance, and the advancement distance is Le. The central control module will calculate the actual total advancement distance Lr according to the calculated advancement distance Le and the real-time advancement distance Ls of the oil pushing plug 401, and Lr = Le + Ls. The central control module will compare the actual total advancement distance Lr with the maximum advancement distance La.

[0076] When Lr ≤ La, the central control module determines that the actual total advancement distance of the oil pushing plug 401 does not exceed the maximum advancement distance, and the central control module does not adjust the control process of the oil pushing plug 401;

[0077] When Lr > La, the central control module determines that the actual total propulsion distance of the oil pushing plug 401 has exceeded the maximum propulsion distance. The central control module will control the driving member 403 to drive the oil pushing rod 402 to elongate, push the oil pushing plug 401 into the pressure control area 12, and correct the propulsion distance to Le’, where Le’ = La - Ls.

[0078] Before the central control module controls the oil pushing plug 401 to advance, by calculating the actual total propulsion distance and comparing it with the maximum propulsion distance, it is determined whether the oil pushing plug 401 will reach the limit position during this propulsion process. When the actual total propulsion distance has exceeded the maximum propulsion distance, the central control module will control the oil pushing plug 401 to push against the limit position, and reselect the standard pressure for determination according to the adjusted real-time liquid level height of the hydraulic oil, making the most of the oil pushing plug 401 for pressure regulation, reducing the entry of external air, and at the same time reducing the generation of bubbles in the hydraulic oil.

[0079] Specifically, when the central control module determines that the real-time propulsion distance of the oil pushing plug 401 has reached the maximum propulsion distance, the central control module will control the two-way air valve 2 to open. The two-way air valve 2 will conduct the air outside the closed fuel tank 1 to the inside of the closed fuel tank 1. The pressure gauge 301 will detect the real-time air pressure Ps’ inside the closed fuel tank 1 in the open state of the two-way air valve 2, and calculate the real-time air pressure difference ΔPs’ in the open state of the two-way air valve 2 according to the standard air pressure Pi, where ΔPs’ = |Pi - Ps’|. The central control module will compare the real-time air pressure difference ΔPs’ with the standard air pressure difference ΔPb until ΔPs’ ≤ ΔPb, and then the central control module controls the two-way air valve 2 to close, completing the regulation of the pressure inside the closed fuel tank 1.

[0080] By opening the two-way air valve 2 to suck external air into the inside of the closed fuel tank 1, the real-time air pressure inside the closed fuel tank 1 can be quickly adjusted. Through the real-time detection of the pressure gauge 301 and the real-time determination of the central control module, when the real-time air pressure difference reaches the standard air pressure difference, the two-way air valve 2 is timely closed to avoid too much air entering the closed fuel tank 1 and affecting the pressure balance again, and also to avoid the formation of more bubbles due to the combination of too much entering air and hydraulic oil, which affects the performance of the hydraulic oil.

[0081] Specifically, the standard working temperature Tb of the hydraulic oil in the closed fuel tank 1 is set in the central control module. When the central control module determines that the real-time air pressure inside the closed fuel tank 1 is higher than the standard air pressure, the thermometer 302 will detect the real-time temperature Ts of the hydraulic oil in the closed fuel tank 1 and transmit the detection result to the central control module. The central control module will compare the real-time temperature Ts of the hydraulic oil with the standard working temperature Tb.

[0082] When Ts ≤ Tb, the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank 1 does not exceed the standard operating temperature. The central control module will control the two-way air valve 2 to open, and the two-way air valve 2 will conduct and discharge the air inside the closed fuel tank 1 to the outside of the closed fuel tank 1. The pressure gauge 301 will detect the real-time air pressure Ps” inside the closed fuel tank 1 when the two-way air valve 2 is open, and calculate the real-time air pressure difference ΔPs” when the two-way air valve 2 is open according to the standard air pressure Pi. ΔPs” = |Pi - Ps”|. The central control module will compare the real-time air pressure difference ΔPs” with the standard air pressure difference ΔPb until ΔPs” ≤ ΔPb, and then the central control module will control the two-way air valve 2 to close, completing the adjustment of the pressure inside the closed fuel tank 1;

[0083] When Ts > Tb, the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank 1 has exceeded the standard operating temperature. The central control module obtains the real-time propulsion distance Ls that the oil pushing plug 401 has advanced in the pressure control area 12. The central control module will control the driving member 403 to drive the oil pushing rod 402 to contract, pulling the oil pushing plug 401 to contract inside the pressure control area 12, and the contraction distance is Lc, Lc = Ls. The liquid level gauge 303 detects the real-time liquid level height of the hydraulic oil in the adjusted closed fuel tank 1. The central control module repeats the above determination based on the real-time liquid level height, selects the standard air pressure, determines the real-time air pressure inside the closed fuel tank 1, and adjusts the pressure inside the closed fuel tank 1 by controlling the gas inlet or outlet of the two-way air valve 2.

[0084] When the central control module determines that the real-time air pressure inside the closed fuel tank 1 is higher than the standard air pressure, the thermometer 302 will detect the real-time temperature of the hydraulic oil in the closed fuel tank 1. The central control module will compare the real-time temperature of the hydraulic oil with the standard operating temperature to determine whether the pressure in the fuel tank has a greater impact on the temperature of the hydraulic oil. When the real-time temperature of the hydraulic oil does not exceed the standard operating temperature, it means that the hydraulic oil can meet the normal use requirements. Therefore, the pressure inside the closed fuel tank 1 is directly adjusted by opening the two-way air valve 2. When the real-time temperature of the hydraulic oil has exceeded the standard operating temperature, it means that the hydraulic oil in the closed fuel tank 1 needs to be cooled. By shrinking the oil pushing plug 401 to the lower limit, the actual volume inside the closed fuel tank 1 is increased. On the basis of reducing the air pressure inside the closed fuel tank 1, the contact area between the hydraulic oil and the closed fuel tank 1 is increased to improve its heat dissipation effect, and the pressure is further adjusted through the two-way air valve 2 to further maintain the pressure stability inside the closed fuel tank 1.

[0085] Specifically, the maximum operating temperature of the hydraulic oil and the maximum over-standard duration are also set in the central control module. When the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank 1 has exceeded the standard operating temperature, the central control module starts the over-temperature timing of the hydraulic oil. When the duration of the over-temperature timing of the hydraulic oil is higher than the maximum over-standard duration, or when the real-time temperature of the hydraulic oil is higher than the maximum operating temperature, the central control module controls the electric ball valve 106 to close and determines that the external hydraulic system connected to the closed fuel tank 1 needs to be restarted.

[0086] By setting the maximum operating temperature and the maximum over-standard duration in the central control module, safety protection is provided for the hydraulic oil and the fuel tank as a whole. At the same time, by controlling the electric ball valve 106 to close and determining the need for restart through the central control module, reminder indicator lights or other display devices can be set at the specific operation end to display the determination results of the central control module, further ensuring the safety of the pressure stabilizing fuel tank device. At the same time, it avoids the long-term high-temperature operation of the hydraulic oil and improves the service life of the hydraulic oil.

[0087] Specifically, the inner wall of the pressure control area 12 of the closed fuel tank 1 is provided with a chamfer, and the partition baffle 107 is provided with a check valve port 108 at the connection with the bottom of the closed fuel tank 1 to discharge the hydraulic oil leaked from the lower part of the oil pushing plug 401 to the oil storage area 11 when the oil pushing plug 401 contracts.

[0088] The chamfer is provided on the inner wall of the pressure control area 12 to ensure that the cross-section of the pressure control area 12 is flat and smooth, improving the sealing performance between the oil pushing plug 401 and the inner wall of the pressure control area 12. At the same time, the check valve port 108 is provided at the position of the partition baffle 107 close to the fuel tank bottom plate, which can discharge the hydraulic oil leaked from the lower part of the oil pushing plug 401 to the oil storage area 11. This not only ensures the stability of the available hydraulic oil volume in the closed fuel tank 1, but also ensures that when the oil pushing plug 401 contracts, the leaked hydraulic oil at the lower part is squeezed, reducing the movable space of the oil pushing plug 401 and avoiding the leakage of hydraulic oil at the connection between the oil pushing rod 402 and the closed fuel tank 1.

[0089] So far, the technical solutions of the present invention have been described in combination with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0090] The above are only the preferred embodiments of the present invention and are not used to limit the present invention; for those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An engineering machinery voltage-stabilized fuel tank device, characterized in that, it includes, a closed fuel tank, which is a closed shell. An oil inlet is arranged at the top of the closed fuel tank. A filter screen is arranged below the oil inlet, and the filter screen is used to filter the hydraulic oil added through the oil inlet. A return oil port is also arranged at the top of the closed fuel tank. A return oil filter element is arranged at the bottom of the return oil port to filter the returned hydraulic oil. The return oil filter element extends into the interior of the closed fuel tank. An oil outlet is arranged at the bottom of the closed fuel tank. An electric ball valve is arranged in the oil outlet to control the oil outlet of the oil outlet. A partition baffle is arranged in the closed fuel tank, and the partition baffle divides the closed fuel tank into an oil storage area and a pressure control area; a two-way air valve, which is arranged on the side wall of the closed fuel tank to control the entry or discharge of gas from the closed fuel tank. An oxygen-permeable filter element is arranged inside the two-way air valve, and the oxygen-permeable filter element is used to filter impurities and oxygen in the external air; a detection component, which includes a pressure gauge, a thermometer and a liquid level gauge. The pressure gauge is used to detect the real-time air pressure inside the closed fuel tank. The thermometer is used to detect the real-time temperature of the hydraulic oil in the closed fuel tank. The liquid level gauge is used to detect the real-time liquid level height of the hydraulic oil in the closed fuel tank. The pressure gauge, the thermometer and the liquid level gauge are respectively connected to a display instrument, and the display instrument is arranged on the side wall outside the closed fuel tank; a pressure control component, which is arranged at the bottom of the closed fuel tank. The pressure control component includes a push oil plug. The push oil plug is arranged inside the pressure control area. The side edge of the push oil plug is in closed fit with the inner wall of the pressure control area of the closed fuel tank and can slide. The push oil plug is connected to one end of a push rod. The push rod can drive the push oil plug to slide in the pressure control area by telescoping to push out the hydraulic oil in the pressure control area. The other end of the push rod passes through the bottom of the closed fuel tank and is connected to a driving part, and the driving part is used to drive the push rod to telescope; a central control module, which is respectively connected to the electric ball valve, the two-way air valve, the detection component and the pressure control component. A preset liquid level height matrix and a standard pressure matrix are arranged in the central control module. The central control module can, according to the comparison result between the real-time liquid level height detected by the liquid level gauge and the preset liquid level height matrix, select the standard air pressure of the closed fuel tank corresponding to the real-time liquid level height in the standard pressure matrix. The central control module will judge the real-time air pressure detected by the pressure gauge through the difference between the standard air pressure and the standard air pressure set inside the central control module, and control the push oil plug to advance or retract and control the two-way air valve to adjust the real-time pressure inside the closed fuel tank according to the real-time air pressure inside the closed fuel tank and the real-time temperature of the hydraulic oil.

2. The engineering machinery voltage-stabilized fuel tank device according to claim 1, characterized in that, A preset liquid level height matrix H (H1, H2, H3) is set in the central control module, where H1 < H2 < H3. A standard pressure matrix P (P1, P2, P3, P4) is also set in the central control module, where P1 < P2 < P3 < P4. The liquid level gauge detects the real-time liquid level height Hs of the hydraulic oil in the closed fuel tank. The central control module compares the real-time liquid level height Hs of the hydraulic oil in the closed fuel tank with the preset liquid level height matrix H. When Hs < H1, the central control module selects P1 from the standard pressure matrix P as the standard air pressure of the closed fuel tank. When H1 ≤ Hs < H2, the central control module selects P2 from the standard pressure matrix P as the standard air pressure of the closed fuel tank. When H2 ≤ Hs < H3, the central control module selects P3 from the standard pressure matrix P as the standard air pressure of the closed fuel tank. When Hs ≥ H3, the central control module selects P4 from the standard pressure matrix P as the standard air pressure of the closed fuel tank.

3. The constant pressure fuel tank device for construction machinery according to claim 2, characterized in that a standard air pressure difference ΔPb is set in the central control module. When the central control module completes the selection of the standard air pressure Pi, where i = 1, 2, 3, 4, the pressure gauge will detect the real-time air pressure Ps inside the closed fuel tank and transmit the detection result to the central control module. The central control module calculates the real-time air pressure difference ΔPs according to the standard air pressure Pi and the real-time air pressure Ps, ΔPs = |Pi - Ps|. The central control module compares the real-time air pressure difference ΔPs with the standard air pressure difference ΔPb. When ΔPs ≤ ΔPb, the central control module determines that the real-time air pressure difference in the closed fuel tank does not exceed the standard air pressure difference, and the central control module does not adjust the air pressure inside the closed fuel tank. When ΔPs > ΔPb, the central control module determines that the real-time air pressure difference in the closed fuel tank has exceeded the standard air pressure difference, and the central control module compares the standard air pressure with the real-time air pressure to adjust the air pressure inside the closed fuel tank.

4. The constant pressure fuel tank device for construction machinery according to claim 3, characterized in that when the central control module determines that the real-time air pressure difference in the closed fuel tank has exceeded the standard air pressure difference, the central control module compares the real-time air pressure Ps inside the closed fuel tank with the standard air pressure Pi. When Ps < Pi, the central control module determines that the real-time air pressure inside the closed fuel tank is lower than the standard air pressure, and the central control module will adjust the air pressure inside the closed fuel tank according to the pushing distance of the oil pushing plug. When Ps > Pi, the central control module determines that the real-time air pressure inside the closed fuel tank is higher than the standard air pressure, and the central control module will determine the real-time temperature of the hydraulic oil inside the closed fuel tank to determine the method of adjusting the air pressure inside the closed fuel tank.

5. The constant pressure fuel tank device for construction machinery according to claim 4, characterized in that The maximum advancing distance La of the oil pushing plug is set in the central control module. When the central control module determines that the real-time air pressure inside the closed fuel tank is lower than the standard air pressure, the central control module obtains the real-time advancing distance Ls that the oil pushing plug has advanced. The central control module compares the real-time advancing distance Ls of the oil pushing plug with the maximum advancing distance La. When Ls≥La, the central control module determines that the real-time advancing distance of the oil pushing plug has reached the maximum advancing distance, and the central control module will control the two-way air valve to adjust the air inside the closed fuel tank. When Ls<La, the central control module determines that the real-time advancing distance of the oil pushing plug has not reached the maximum advancing distance. The central control module will control the driving part to drive the oil pushing rod to extend, pushing the oil pushing plug to advance into the pressure control area. The advancing distance is Le, and Le = Ls×[1 + (Pi - Ps) / Pi] - Ls. After the central control module completes the adjustment of the oil pushing plug, the liquid level gauge detects the real-time liquid level height of the hydraulic oil in the closed fuel tank. The central control module repeats the above operations of selecting the standard air pressure according to the real-time liquid level height and determining and adjusting the real-time air pressure until the central control module determines that the adjusted real-time air pressure difference inside the closed fuel tank does not exceed the standard air pressure difference, and the central control module completes the adjustment of the air pressure inside the closed fuel tank.

6. The engineering machinery pressure stabilizing fuel tank device according to claim 5, wherein, When the central control module determines that the real-time advancing distance of the oil pushing plug has not reached the maximum advancing distance, the central control module controls the oil pushing plug to advance, and the advancing distance is Le. The central control module will calculate the actual total advancing distance Lr according to the calculated advancing distance Le and the real-time advancing distance Ls of the oil pushing plug, and Lr = Le + Ls. The central control module compares the actual total advancing distance Lr with the maximum advancing distance La. When Lr≤La, the central control module determines that the actual total advancing distance of the oil pushing plug does not exceed the maximum advancing distance, and the central control module does not adjust the control process of the oil pushing plug. When Lr>La, the central control module determines that the actual total advancing distance of the oil pushing plug has exceeded the maximum advancing distance. The central control module will control the driving part to drive the oil pushing rod to extend, pushing the oil pushing plug to advance into the pressure control area, and correct the advancing distance to Le’, and Le’ = La - Ls.

7. The engineering machinery pressure stabilizing fuel tank device according to claim 5, wherein, When the central control module determines that the real-time propulsion distance of the oil pushing plug has reached the maximum propulsion distance, the central control module will control the two-way air valve to open. The two-way air valve will conduct the air outside the closed fuel tank to the inside of the closed fuel tank. The pressure gauge will detect the real-time air pressure Ps' inside the closed fuel tank in the open state of the two-way air valve, and calculate the real-time air pressure difference ΔPs' in the open state of the two-way air valve according to the standard air pressure Pi. ΔPs' = |Pi - Ps'|. The central control module will compare the real-time air pressure difference ΔPs' with the standard air pressure difference ΔPb until ΔPs' ≤ ΔPb, and then the central control module will control the two-way air valve to close, completing the regulation of the pressure inside the closed fuel tank.

8. The constant-pressure fuel tank device for construction machinery according to claim 4, characterized in that, the standard working temperature Tb of the hydraulic oil inside the closed fuel tank is set in the central control module. When the central control module determines that the real-time air pressure inside the closed fuel tank is higher than the standard air pressure, the thermometer will detect the real-time temperature Ts of the hydraulic oil inside the closed fuel tank and transmit the detection result to the central control module. The central control module will compare the real-time temperature Ts of the hydraulic oil with the standard working temperature Tb. When Ts ≤ Tb, the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank has not exceeded the standard working temperature. The central control module will control the two-way air valve to open. The two-way air valve will conduct the air inside the closed fuel tank to be discharged to the outside of the closed fuel tank. The pressure gauge will detect the real-time air pressure Ps'' inside the closed fuel tank in the open state of the two-way air valve, and calculate the real-time air pressure difference ΔPs'' in the open state of the two-way air valve according to the standard air pressure Pi. ΔPs'' = |Pi - Ps''|. The central control module will compare the real-time air pressure difference ΔPs'' with the standard air pressure difference ΔPb until ΔPs'' ≤ ΔPb, and then the central control module will control the two-way air valve to close, completing the regulation of the pressure inside the closed fuel tank; When Ts > Tb, the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank has exceeded the standard working temperature. The central control module obtains the real-time propulsion distance Ls that the oil pushing plug has advanced in the pressure control area. The central control module will control the driving part to drive the push rod to contract, pulling the oil pushing plug to contract inside the pressure control area, and the contraction distance is Lc, Lc = Ls. The liquid level gauge detects the real-time liquid level height of the hydraulic oil in the adjusted closed fuel tank. The central control module repeats the above operation of selecting the standard air pressure according to the real-time liquid level height and judging the real-time air pressure, and adjusts the pressure inside the closed fuel tank by controlling the gas inlet or outlet of the two-way air valve.

9. The constant-pressure fuel tank device for construction machinery according to claim 8, characterized in that, The central control module is also provided with the maximum working temperature of the hydraulic oil and the maximum over-standard duration. When the central control module determines that the real-time temperature of the hydraulic oil in the closed fuel tank has exceeded the standard working temperature, the central control module starts the over-temperature timing of the hydraulic oil. When the duration of the over-temperature timing of the hydraulic oil is higher than the maximum over-standard duration, or when the real-time temperature of the hydraulic oil is higher than the maximum working temperature, the central control module controls the electric ball valve to close and determines that the external hydraulic system connected to the closed fuel tank needs to be restarted.

10. The pressure stabilizing fuel tank device for construction machinery according to claim 1, characterized in that, The inner wall of the pressure control area of the closed fuel tank is provided with a chamfer. The partition baffle is provided with a one-way valve port at the connection with the bottom of the closed fuel tank, so as to discharge the hydraulic oil leaking from the push oil plug to the oil storage area when the push oil plug contracts.

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