Stepped hydraulic oil tank with long runner and three-phase separation method

Abstract

The invention provides a stepped hydraulic oil tank with a long runner and a three-phase separation method, and relates to the technical field of hydraulics, the stepped hydraulic oil tank comprises a stepped hydraulic oil tank internally provided with runner combination unit bodies, a stepped hydraulic oil tank externally connected with pipeline combination unit bodies and an integrated hydraulic oil tank, and an oil return area, a gas and impurity removal area and a flow stabilization area are arranged in the oil tank. In the built-in flow channel combination unit bodies, the seventh oil tank unit is the lowest column oil tank unit, and the first oil tank unit, the second oil tank unit, the third oil tank unit, the fourth oil tank unit, the fifth oil tank unit and the sixth oil tank unit form an inner step column oil tank unit. In the external pipeline combination unit bodies, the twelfth oil tank unit is the lowest-row oil tank unit, and the eighth oil tank unit, the ninth oil tank unit, the tenth oil tank unit and the eleventh oil tank unit form outer step row oil tank units respectively. The invention has the advantages of miniaturization, efficient heat dissipation, degassing and impurity removal, high space utilization rate and suitability for various volume requirements.

Description

Technical Field

[0001] This invention relates to the field of hydraulic technology, specifically to a stepped hydraulic oil tank with a long flow channel and a three-phase separation method. Background Technology

[0002] In the field of factory machinery and equipment, mobile hydraulic equipment such as automated guided vehicles and small forklifts, due to limitations in vehicle height and chassis space, requires reserving as much layout space as possible for the system. Miniaturizing the hydraulic oil tank helps reduce the weight and size of the equipment, thereby improving mobility and space utilization. In the field of agricultural machinery and equipment, such as tractors, rice transplanters, and seeders, mobile field machinery has a limited working width and tight internal space. Using miniaturized hydraulic oil tanks can make the structure compact, which is conducive to improving space utilization, operating efficiency, and endurance. In the field of construction machinery and equipment, such as loaders, excavators, and aerial work platforms, construction machinery often operates in confined spaces, requiring the equipment to be small and flexible. Miniaturizing the hydraulic oil tank can optimize the weight distribution of the whole machine and improve the mobility and economy of the equipment.

[0003] However, in the process of meeting the miniaturization requirements, the internal gas-liquid-solid three-phase separation efficiency of hydraulic oil tanks faces severe challenges. The working medium of a hydraulic system is a liquid phase (hydraulic oil), but during circulation, a gas phase (free or dissolved air) and a solid phase (wear particles, external dust, and other impurities) inevitably mix in. One of the core functions of the oil tank is to achieve effective separation of these three phases to ensure the cleanliness of the system's working medium and extend its service life. Miniaturization design leads to the following defects: First, the gas-phase separation effect decreases. The reduced tank volume leads to a shorter residence time of the oil in the tank, making it difficult for air bubbles to rise and escape fully, resulting in residual air in the oil. This can easily cause cavitation, noise, and system vibration, affecting the operational stability of the hydraulic system and the lifespan of components. Second, the heat dissipation efficiency is low: the shortened oil flow path results in insufficient heat exchange time between the oil and the tank wall, making it difficult for heat to dissipate effectively. This leads to increased oil temperature, reduced oil viscosity and lubrication performance, and accelerated aging of hydraulic components. Third, the solid sedimentation effect is limited: traditional miniaturized oil tanks have simple flow channels and fast oil flow rates, resulting in insufficient sedimentation time for solid impurities. Particles are easily drawn into the system, exacerbating component wear. Deposits are difficult to clean, and long-term accumulation may clog the flow channels or cause corrosion.

[0004] For example, CN112943713A discloses a labyrinth-type hydraulic oil tank, which can reduce the volume and weight of the oil tank, increase the heat exchange intensity, and improve the heat dissipation effect; however, this labyrinth-type hydraulic oil tank is a miniaturized oil tank with a fixed volume, which cannot be changed according to different application scenarios, and its application field is limited; CN202370916U discloses an irregularly shaped hydraulic oil tank, which overcomes the defect of poor internal pressure resistance of the irregular shape, but this utility model ignores the design of three-phase separation function; CN115559947A discloses a pressure-constant elastic hydraulic oil tank, which discloses a pressure-constant elastic hydraulic oil tank, but this invention also does not involve the separation of three phases.

[0005] Therefore, researching a short-process, high-efficiency three-phase separation method for stepped hydraulic oil tanks applicable to multiple fields, optimizing the hydraulic oil tank structure, and significantly reducing the oil consumption of the hydraulic system are key to achieving oil saving and emission reduction in hydraulic systems. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention aims to provide a stepped hydraulic oil tank with a long flow channel and a three-phase separation method. In the internal flow channel assembly unit, arc-shaped baffles and vertical baffles are respectively installed inside the second and third oil tank units, forming a degassing and impurity removal zone between adjacent second and third oil tank units. In the external pipeline assembly unit, arc-shaped baffles are respectively installed inside the ninth, tenth, and eleventh oil tank units. In the same row of oil tank units, one ninth oil tank... The unit, the tenth oil tank unit, and the eleventh oil tank unit are arranged sequentially from top to bottom, with adjacent oil tank units forming a degassing and impurity removal zone. In the integrated hydraulic oil tank, arc-shaped baffles and straight baffles are set in the third and second step units respectively to form a degassing and impurity removal zone. By setting oil return zone, degassing and impurity removal zone, and flow stabilization zone in the built-in flow channel assembly unit, the external pipeline assembly unit, and the integrated hydraulic oil tank, the oil flow channel is extended and heat dissipation is enhanced, thereby promoting the escape of air bubbles and the sedimentation of impurities in the oil and reducing cavitation.

[0007] Specifically, on the one hand, the present invention provides a stepped hydraulic oil tank with a long flow channel, which includes a seventh oil tank unit and an inner stepped row of oil tank units. The inner stepped oil tank unit includes a first oil tank unit, a second oil tank unit, a third oil tank unit, a fourth oil tank unit, a fifth oil tank unit, and a sixth oil tank unit. The second and third oil tank units are respectively provided with arc-shaped partitions and vertical partitions. The arc-shaped partitions include arc segments, horizontal segments, and inclined segments. The cut of the arc segment is located at the oil inlet of the oil tank unit, and the cut of the inclined segment is located at the oil outlet of the oil tank unit. The horizontal segment contacts the lower wall of the oil tank unit. In the second oil tank unit, the vertical partition is located at the inclined segment. In the third oil tank unit, the vertical partition is located at the arc segment. The fifth and sixth oil tank units are provided with vertical partitions inside. The first oil tank unit is located at the first position of the highest row of oil tank units in the inner stepped oil tank unit, and the fourth oil tank unit is located at the first position of the second-highest row of oil tank units in the inner stepped oil tank unit. In the inner stepped oil tank unit, the first column of oil tank units is arranged from the first position to the last position as the fourth oil tank unit, the second oil tank unit, and the sixth oil tank unit. In the inner stepped oil tank unit, the second column of oil tank units is arranged from the first position to the last position as the fourth oil tank unit, the second oil tank unit, the third oil tank unit, and the fifth oil tank unit. Starting from the third oil tank unit, including the third oil tank unit, for each additional column, a second or third oil tank unit is added to the second-to-last position of the next column. The second and third oil tank units alternate. The sixth and fifth oil tank units alternate at the end of each column. In each column of the inner stepped oil tank unit, the second and third oil tank units alternate, and there is one sixth or fifth oil tank unit. The expression for the number of columns of the built-in flow channel assembly unit is: ; In the formula, a is the volume of a single oil tank unit in the built-in flow channel assembly unit, and x is the number of columns of the built-in flow channel assembly unit.

[0008] Based on the installation positions of the return oil pipe and suction oil pipe in the stepped hydraulic oil tank of the built-in flow channel assembly unit and the stepped hydraulic oil tank of the external pipeline assembly unit, as well as the return oil flow rate, the expression for the maximum volume is: ; In the formula, c is the inner diameter of the return oil pipe.

[0009] Preferably, in the built-in flow channel assembly unit, the seventh oil tank unit is provided with an oil suction pipe on its left side, the first oil tank unit is provided with an oil filler cap and an air filter on its upper side, the first oil tank unit is provided with an oil return pipe on its left side, and starting from the third row of oil tank units in the inner stepped row, the second oil tank unit, the highest in each row, is provided with a level gauge on one side; the first oil tank unit is provided with an oil outlet on its lower side, the fourth oil tank unit is provided with an oil outlet on its lower side, the second and third oil tank units are provided with an oil inlet and an oil outlet on their upper and lower sides respectively, the fifth and sixth oil tank units are provided with an oil inlet on their upper side, the oil outlet and the oil inlet form an inter-row oil port, and the fifth and sixth oil tank units are provided with a connector on their front side.

[0010] Preferably, in the inner stepped row of fuel tank units, except for the first two rows, if the second-to-last position in the previous row is the second fuel tank unit, then the second-to-last position in the next row is the third fuel tank unit; if the second-to-last position in the previous row is the third fuel tank unit, then the second-to-last position in the next row is the second fuel tank unit; if the last position in the previous row is the fifth fuel tank unit, then the last position in the next row is the sixth fuel tank unit; if the second-to-last position in the previous row is the sixth fuel tank unit, then the last position in the next row is the fifth fuel tank unit.

[0011] On the other hand, the present invention provides a three-phase separation method for a stepped hydraulic oil tank with a long flow channel, the specific implementation process of which is as follows: The oil enters the return oil zone of the first oil tank unit through the return oil pipe on the first oil tank unit in the highest row of the inner stepped oil tank unit. It then flows sequentially into the second and third oil tank units arranged alternately in the same row through the oil outlet on the first oil tank unit. The flow path passes from top to bottom through the degassing and impurity removal zone composed of the second and third oil tank units, and then enters the sixth oil tank unit at the end of the second highest row of the inner stepped oil tank unit through the connector on the fifth oil tank unit.

[0012] The oil enters from the connector of the sixth oil tank unit and rises to the fourth oil tank unit. It then passes through the degassing and impurity removal zone composed of the second and third oil tank units in the second highest row of oil tank units. In the same way, it enters the fifth oil tank unit at the end of the second second highest row of oil tank units in the inner stepped row of oil tank units to perform degassing and impurity removal. The above process is repeated until the oil passes through all the oil tank units in the inner stepped row of oil tank units.

[0013] After the oil enters the steady flow zone formed by the seventh oil tank unit from the joint of the lowest row of the inner stepped oil tank unit, it leaves the built-in flow channel assembly unit through the oil suction pipe, thus completing the three-phase separation of the oil.

[0014] Specifically, on one hand, the present invention provides a stepped hydraulic oil tank with a long flow channel, which includes a twelfth oil tank unit and an outer stepped row of oil tank units. The outer stepped row of oil tank units includes an eighth oil tank unit, a ninth oil tank unit, a tenth oil tank unit, and an eleventh oil tank unit. The ninth, tenth, and eleventh oil tank units are provided with arc-shaped partitions inside. The arc-shaped partitions include arc segments, horizontal segments, and inclined segments. The inner arc surface of the arc segment is located below the oil inlet of the oil tank unit, and the outer arc surface of the arc segment is located above the oil outlet of the oil tank unit. The horizontal segment is located on the side wall of the oil tank unit and is at a certain distance from the lower wall surface. The eighth oil tank unit is located at the first position of the highest row in the outer stepped row of oil tank units, and the ninth oil tank unit is located at the first position of the second stepped row of oil tank units in the outer stepped row of oil tank units. In the outer stepped row of fuel tank units, the first row of fuel tank units is arranged from the first position to the last position as the ninth fuel tank unit and the eleventh fuel tank unit. In the outer stepped row of fuel tank units, the second row of fuel tank units is arranged from the first position to the last position as the ninth fuel tank unit, the tenth fuel tank unit, and the eleventh fuel tank unit. Starting from the third row of fuel tank units, for each additional row in the outer stepped row of fuel tank units, a tenth fuel tank unit is added to the second-to-last position of the next row.

[0015] The expression for the number of columns of the external pipeline assembly unit is: ; In the formula, b is the volume of a single oil tank unit in the external pipeline assembly unit, and y is the number of columns in the external pipeline assembly unit.

[0016] Based on the installation positions of the return oil pipe and suction oil pipe in the stepped hydraulic oil tank of the external pipeline assembly unit and the return oil flow rate, the expression for the maximum volume is: ; In the formula, c is the inner diameter of the return oil pipe.

[0017] Preferably, in the external pipeline assembly unit, the right side of the twelfth oil tank unit is provided with an oil suction pipe, the upper side of the eighth oil tank unit is provided with an oil filler cap, an air filter and an oil return pipe in sequence, and starting from the second column, the eighth oil tank unit and the ninth oil tank unit at the top of each column are provided with a liquid level gauge on one side.

[0018] Preferably, in the outer stepped row of oil tank units, the lower side of the eighth oil tank unit is provided with an oil outlet, the upper and lower sides of the ninth and tenth oil tank units are respectively provided with oil inlets and oil outlets, the upper and left sides of the eleventh oil tank unit are respectively provided with oil inlets and oil outlets, and the upper side of the twelfth oil tank unit is provided with an oil inlet. In two adjacent rows of the outer stepped row of oil tank units, the oil outlet of the eleventh oil tank unit is connected to the oil inlet of the ninth oil tank unit through a hose, and the oil outlet of the eleventh oil tank unit in the lowest row of the outer stepped row of oil tank units is connected to the oil inlet of the twelfth oil tank unit through a hose.

[0019] On the other hand, the present invention provides a three-phase separation method for a stepped hydraulic oil tank with a long flow channel, the specific implementation process of which is as follows: The oil enters the return oil zone of the eighth oil tank unit in the highest row of the outer stepped oil tank unit through the return oil pipe. It then flows sequentially into the tenth and eleventh oil tank units arranged in the same row through the oil outlet of the eighth oil tank unit. The flow path passes from top to bottom through the degassing and impurity removal zone formed by the tenth and eleventh oil tank units connected in the same row. Finally, it enters the oil inlet of the ninth oil tank unit, which is located at the first position in the second highest row of the outer stepped oil tank unit, through the hose connected to the oil outlet of the eleventh oil tank unit.

[0020] The oil enters the ninth oil tank unit in the second-highest row of oil tank units through a hose. After passing through the degassing and impurity removal zone composed of the ninth, tenth, and eleventh oil tank units connected in sequence in this row, the oil enters the inlet of the ninth oil tank unit, which is the first position in the second-highest row of oil tank units in the outer stepped oil tank unit, through the hose connected to the oil outlet of the eleventh oil tank unit. The above process is repeated until the oil passes through all the oil tank units in the outer stepped oil tank unit.

[0021] After the oil enters the steady flow zone formed by the twelfth oil tank unit from the joint of the lowest oil tank unit in the outer stepped oil tank unit, it leaves the outer pipeline assembly unit through the oil suction pipe, thus completing the three-phase separation of the oil.

[0022] Specifically, on one hand, the present invention provides a stepped hydraulic oil tank with a long flow channel, which includes an integrated metal shell. The upper side of the third stepped unit of the integrated metal shell is provided with a return oil pipe, an oil filler cap and an air filter in sequence. The left side of the third stepped unit is provided with a level gauge. The interior of the third stepped unit is provided with two arc-shaped partitions with the same structure, which are arranged alternately. The interior of the second stepped unit of the integrated metal shell is provided with three vertical partitions that alternate between upper and lower. The left side of the first stepped unit of the integrated metal shell is provided with a suction pipe. The position where the third stepped unit, the second stepped unit and the first stepped unit are connected to each other is provided with a square interface.

[0023] On the other hand, the present invention provides a three-phase separation method for a stepped hydraulic oil tank with a long flow channel, the specific implementation process of which is as follows: The oil enters the third-stage unit through the return pipe of the integrated metal shell. After passing through the degassing and impurity removal zone composed of arc baffles, it enters the degassing and impurity removal zone composed of vertical baffles in the second-stage unit through the square interface on the third-stage unit. Then, it enters the flow stabilization zone of the first-stage unit through the square interface on the second-stage unit. Finally, it leaves the integrated hydraulic oil tank through the oil suction pipe of the first-stage unit, thus completing the three-phase separation of the oil.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention, while meeting the requirements of lightweighting and miniaturization, has the ability to extend the oil flow channel, enhance heat dissipation, remove gas and impurities, improve installation space utilization, and adapt to various needs. The arc-shaped baffle in the gas and impurity removal zone extends the residence time of the oil in the tank, promotes the escape of air bubbles and the sedimentation of impurities in the oil, and reduces cavitation, noise, and system vibration; the extended flow channel of the adjacent two rows of tank units increases the contact area between the oil and the tank wall and the heat exchange time, effectively reducing the oil temperature and preventing oil oxidation and aging of hydraulic components.

[0025] 2. The built-in flow channel assembly unit of the present invention includes vertical baffles in the second, third, fifth, and sixth oil tank units to form oil rising channels. These channels maintain a certain width to ensure that the oil's ascent is not affected by resistance from the cross-sectional width. All connections within the rising channels utilize inter-row ports. In the fourth oil tank unit, guide baffles are provided to guide the oil within the rising channels, ensuring smooth oil flow and successful circulation. The first, fifth, sixth, and seventh oil tank units do not have arc-shaped baffles, saving tank space and ensuring smooth connection between adjacent rows of tanks. Through holes are provided on the outer side of the tank units for easy bolt connection.

[0026] 3. In the external pipeline assembly unit of the present invention, in the outer stepped oil tank unit except for the ninth, tenth and eleventh units of the highest oil tank unit, the arc-shaped partitions are arranged in the same direction and have a certain height to facilitate the flow of oil into the next oil tank unit; the height of the eighth oil tank unit in the highest oil tank unit is doubled to provide pressure to facilitate the flow of oil into the next row through the hose; a semi-circular opening is provided on the outside of the oil tank unit to guide the hose arrangement. Attached Figure Description

[0027] Figure 1 This is a structural diagram of the built-in flow channel assembly unit in the stepped hydraulic oil tank with a long flow channel according to the present invention; Figure 2 This is a top view of the built-in flow channel assembly unit in the stepped hydraulic oil tank with long flow channels of the present invention; Figure 3 This is a flow channel diagram of the highest column in the built-in flow channel assembly unit of the stepped hydraulic oil tank with long flow channels of the present invention; Figure 4 This is a flow channel diagram of the second row of tank units in the built-in flow channel assembly unit body of the stepped hydraulic oil tank with long flow channels of the present invention. Figure 5 This is a flow channel diagram of the first row of tank units in the built-in flow channel assembly unit body of the stepped hydraulic oil tank with long flow channels of the present invention. Figure 6 This is a flow channel diagram of the lowest column of the built-in flow channel assembly unit in the stepped hydraulic oil tank with long flow channels of the present invention; Figure 7 This is a structural diagram of the combined unit of the inner and outer pipelines of the stepped hydraulic oil tank with a long flow channel according to the present invention. Figure 8 This is a top view of the external pipeline assembly unit of the stepped hydraulic oil tank with a long flow channel according to the present invention; Figure 9 This is a flow channel diagram of the highest column in the external pipeline assembly unit of the stepped hydraulic oil tank with long flow channels of the present invention; Figure 10 This is a flow channel diagram of the middle row of the external pipeline assembly unit in the stepped hydraulic oil tank with long flow channels of the present invention; Figure 11 This is a structural diagram of the integrated configuration of the stepped hydraulic oil tank with a long flow channel in this invention; Figure 12 This is a perspective view of the integrated configuration of the stepped hydraulic tank with a long flow channel according to the present invention.

[0028] Key reference numerals: 1. Filler cap, 2. Air filter, 3. Return oil pipe, 4. Level gauge, 5. Suction pipe, 6. Connector, 7. Hose, 8. Arc baffle, 9. Inter-row oil port, 10. Vertical baffle, 11. Straight baffle, 12. Return oil zone, 13. Degassing and impurity removal zone, 14. Flow stabilization zone, 15. Integrated metal casing, 16. First oil tank unit, 17. Second oil tank unit, 18. Third oil tank unit, 19. Fourth oil tank unit, 20. Fifth oil tank unit, 21. Sixth oil tank unit, 22. Seventh oil tank unit, 23. Eighth oil tank unit, 24. Ninth oil tank unit, 25. Tenth oil tank unit, 26. Eleventh oil tank unit, 27. Twelfth oil tank unit. Detailed Implementation

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0030] A stepped hydraulic oil tank with a long flow channel includes a stepped hydraulic oil tank with an internal flow channel assembly unit, a stepped hydraulic oil tank with an external pipeline assembly unit, and a one-piece stepped hydraulic oil tank, on which components such as a fixed displacement pump and servo motor can be installed. In the internal flow channel assembly unit and the external pipeline assembly unit, oil is connected between each pair of tank units via inter-row ports 9, with sealing rings installed at the inter-row ports 9 to prevent leakage. The tank unit with the internal flow channel assembly unit has an internal oil rising flow channel. Between adjacent tank units, oil is supplied from the bottom via a connector 6, and then transported to the top along the rising flow channel by flow pressure. Between adjacent tank units in the external pipeline assembly unit, oil is transported from the bottom of the previous row to the top of the next row by flow pressure through a hose 7.

[0031] The built-in flow channel assembly unit consists of the highest row of oil tank units, the second-tier row of oil tank units, and the seventh oil tank unit, such as... Figures 1 to 6 As shown, it includes a first fuel tank unit 16, a second fuel tank unit 17, a third fuel tank unit 18, a fourth fuel tank unit 19, a fifth fuel tank unit 20, a sixth fuel tank unit 21, and a seventh fuel tank unit 22, as follows: Figure 6 As shown, the seventh oil tank unit 22 is the lowest row of oil tank units. An oil suction pipe 5 is provided on the left side of the seventh oil tank unit 22. The first oil tank unit 16, the second oil tank unit 17, the third oil tank unit 18, the fourth oil tank unit 19, the fifth oil tank unit 20, and the sixth oil tank unit 21 respectively form an inner stepped row of oil tank units. In the inner stepped row of oil tank units, each row is a vertically stacked oil tank unit structure, forming a stepped structure that ensures the oil can flow from bottom to top. The number of oil tank unit rows and the quantity per row can be increased or decreased according to volume requirements. The first oil tank unit 16 is located at the first position of the highest row of oil tank units in the inner stepped row of oil tank units. Figure 1 and Figure 2 As shown, the upper side of the first oil tank unit 16 is provided with a filler cap 1 and an air filter 2. The filler cap 1 is used as the oil filling port and cleaning hole of the hydraulic oil tank. The left side of the first oil tank unit 16 is provided with a return oil pipe 3. The fourth oil tank unit 19 is located at the first position of the second-step oil tank unit in the inner stepped oil tank unit. Starting from the third column, the side of the highest second oil tank unit 17 in each column is provided with a level gauge 4. The lower side of the first oil tank unit 16 is provided with an oil outlet. The lower side of the fourth oil tank unit 19 is provided with an oil outlet. The upper and lower sides of the second oil tank unit 17 and the third oil tank unit 18 are respectively provided with an oil inlet and an oil outlet. The upper side of the fifth oil tank unit 20 and the sixth oil tank unit 21 is provided with an oil inlet. The oil outlet and the oil inlet form an inter-row oil port 9. The front side of the fifth oil tank unit 20 and the sixth oil tank unit 21 is provided with a connector 6.

[0032] like Figure 3 , Figure 4 and Figure 5As shown, the second oil tank unit 17 and the third oil tank unit 18 are respectively provided with an arc-shaped partition 8 and a vertical partition 10 inside, and the fifth oil tank unit 20 and the sixth oil tank unit 21 are provided with a vertical partition 10 inside. In the second fuel tank unit 17, the horizontal section of the arc-shaped partition 8 coincides with the inner wall surface at the lower end of the fuel tank unit; in the third fuel tank unit 18, the horizontal section of the arc-shaped partition 8 coincides with the inner wall surface at the lower end of the fuel tank unit; the distance between the lower oil outlet edge of the first fuel tank unit 16 and the fourth fuel tank unit 19 and the nearest inner wall surface of the fuel tank unit or the vertical partition 10 is 10mm; the distance between the upper and lower oil inlet or outlet edges of the second fuel tank unit 17 and the third fuel tank unit 18 and the nearest inner wall surface of the fuel tank unit or the vertical partition 10 is 10mm; the distance between the front and rear oil inlet or outlet edges of the fifth fuel tank unit 20 and the sixth fuel tank unit 21 and the nearest inner wall surface of the fuel tank unit is 10mm; the distance between the front oil inlet edge of the seventh fuel tank unit 22 and the nearest inner wall surface of the fuel tank unit is 10mm.

[0033] like Figure 3 As shown, in the inner stepped fuel tank unit, the first column of fuel tank units, from the first position to the last position, is arranged with the fourth fuel tank unit 19, the second fuel tank unit 17, and the sixth fuel tank unit 21 in sequence. In the second column of the inner stepped fuel tank unit, the fourth fuel tank unit 19, the second fuel tank unit 17, the third fuel tank unit 18, and the fifth fuel tank unit 20 in sequence, from the first position to the last position. Starting from the third column of the inner stepped fuel tank unit, for each additional column, a second fuel tank unit 17 or a third fuel tank unit 18 is added to the second-to-last position of the next column. Based on the name of the fuel tank unit at the second-to-last position in the previous column, the second fuel tank unit 17 and the third fuel tank unit 18 appear alternately. If the second-to-last position in the previous column is the second fuel tank unit... If the first oil tank unit is 17, then the second-to-last position in the next column is the third oil tank unit 18. If the second-to-last position in the previous column is the third oil tank unit 18, then the second-to-last position in the next column is the second oil tank unit 17. If the last position in the previous column is the fifth oil tank unit 20, then the last position in the next column is the sixth oil tank unit 21. If the second-to-last position in the previous column is the sixth oil tank unit 21, then the last position in the next column is the fifth oil tank unit 20. In the inner stepped column of oil tank units, the sixth oil tank unit 21 and the fifth oil tank unit 20 alternate. In each column of the inner stepped column of oil tank units, the second oil tank unit 17 and the third oil tank unit 18 alternate, and there is one sixth oil tank unit 21 or one fifth oil tank unit 20. If the last column after the third column of oil tank units is the last column of oil tank units in the inner stepped column of oil tank units, then it is the highest column of oil tank units. At this time, the first position of the highest column of oil tank units is the first oil tank unit 16.

[0034] Let the volume of the second oil tank unit 17 and the third oil tank unit 18 both be 'a'. Since the second oil tank unit 17 and the third oil tank unit 18 have an arc-shaped partition 8 and a vertical partition 10 inside, their volume is taken as 85%, which is 0.85a. The first oil tank unit 16, the fourth oil tank unit 19, the fifth oil tank unit 20, and the sixth oil tank unit 21 do not have arc-shaped partitions 8 due to flow channel conflicts. To save volume, their height is set to half the height of the second oil tank unit 17 and the third oil tank unit 18, and their volume is 0.425a. The seventh oil tank unit 22, being the flow stabilization zone 14 connected to the suction pipe 5, has no internal structure, and its length is set to half the length of the second oil tank unit 17 and the third oil tank unit 18, with a volume of 0.425a. Let the number of columns be an unknown x, then we have: ; In the formula, 'a' represents the volume of the second fuel tank unit 17 and the third fuel tank unit 18, respectively. The dimensions of the fuel tank unit are: L×W×H, where L is between 500mm and 1500mm, W is between 100mm and 250mm, and H is between 200mm and 250mm.

[0035] The external pipeline assembly unit consists of the highest-ranking oil tank unit, the second-ranking oil tank unit, and the twelfth-ranking oil tank unit, such as... Figures 7 to 10 As shown, the system includes an eighth oil tank unit 23, a ninth oil tank unit 24, a tenth oil tank unit 25, an eleventh oil tank unit 26, and a twelfth oil tank unit 27. The twelfth oil tank unit 27 is the lowest row of oil tank units. An oil suction pipe 5 is provided on the right side of the twelfth oil tank unit 27. The eighth oil tank unit 23, the ninth oil tank unit 24, the tenth oil tank unit 25, and the eleventh oil tank unit 26 respectively form an outer stepped row of oil tank units. The eighth oil tank unit 23 is located at the first position of the highest row of the outer stepped oil tank units. The upper side of the eighth oil tank unit 23 is provided with a filler cap 1, an air filter 2, and a return oil pipe 3 in sequence. The ninth oil tank unit 24 is located at the first position of the second stepped row of the outer stepped oil tank units. Starting from the second row, a level gauge 4 is provided on one side of the highest eighth oil tank unit 23 and the highest ninth oil tank unit 24 in each row.

[0036] The lower side of the eighth oil tank unit 23 is provided with an oil outlet. The upper and lower sides of the ninth and tenth oil tank units 24 and 25 are provided with oil inlets and oil outlets, respectively. The upper and left sides of the eleventh oil tank unit 26 are provided with oil inlets and oil outlets, respectively. The upper side of the twelfth oil tank unit 27 is provided with an oil inlet. In the two adjacent rows of the outer stepped oil tank units, the oil outlet of the eleventh oil tank unit 26 is connected to the oil inlet of the ninth oil tank unit 24 through a hose 7. The oil outlet of the eleventh oil tank unit 26 in the lowest row of the outer stepped oil tank units is connected to the oil inlet of the twelfth oil tank unit 27 through a hose 7.

[0037] The ninth fuel tank unit 24, the tenth fuel tank unit 25, and the eleventh fuel tank unit 26 are equipped with arc-shaped partitions 8 inside. The horizontal section of the arc-shaped partition 8 in the ninth fuel tank unit 24, the tenth fuel tank unit 25, and the eleventh fuel tank unit 26 is 40mm away from the lower inner wall of the fuel tank unit. The lower oil outlet edge of the eighth fuel tank unit 23 and the ninth fuel tank unit 24 is 45mm away from the inner wall of the fuel tank unit. The upper and lower oil inlet or oil outlet edges of the tenth fuel tank unit 25 are 45mm away from the inner wall of the fuel tank unit. The upper oil inlet edge of the eleventh fuel tank unit 26 is 45mm away from the inner wall of the fuel tank unit, and the left oil outlet edge is 12mm away from the lower wall of the fuel tank unit.

[0038] In the outer stepped oil tank unit, the first column of oil tank units is arranged from the first position to the last position as the ninth oil tank unit 24 and the eleventh oil tank unit 26. In the outer stepped oil tank unit, the second column of oil tank units is arranged from the first position to the last position as the ninth oil tank unit 24, the tenth oil tank unit 25 and the eleventh oil tank unit 26. Starting from the third column of oil tank units, for each additional column, a tenth oil tank unit 25 is added to the second-to-last position of the next column.

[0039] Let the volumes of the ninth oil tank unit 24, the tenth oil tank unit 25, and the eleventh oil tank unit 26 be *b*, respectively. Since there is an internal arc-shaped partition 8, its volume is taken as 90%, which is 0.9 *b*. To ensure sufficient pressure, the height of the eighth oil tank unit 23 is set to twice the height of the tenth oil tank unit 25, and its volume is 1.8 *b*. The twelfth oil tank unit 27, being the flow stabilization zone 14 connected to the oil suction pipe 5, has no internal structure; its length is set to half the length of the tenth oil tank unit 25, and its volume is 0.45 *b*. Let the number of columns be an unknown y, then we have: .

[0040] Based on the return oil flow rate, the internal flow channel assembly unit and the external pipeline assembly unit are divided into minimum intermediate units with dimensions of L × W × H (L is recommended to be between 500mm and 1500mm, W is recommended to be between 100mm and 250mm, and H is recommended to be between 200mm and 250mm), ensuring that the flow channel has a certain length and the unit height meets the normal arrangement of the arc baffle 8. Based on the arrangement principle of return oil pipe 3 and suction oil pipe 5—the distance between return oil pipe 3 and suction oil pipe 5 and the bottom and wall of the oil tank unit respectively is generally not less than 3 times the pipe diameter. For an oil tank unit with a width of W, the nominal pipe diameter of return oil pipe 3 should not be greater than W / 3. The inner diameter c used is determined according to the standard pipe diameter model. The flow velocity of return oil pipe 3 is generally not greater than 2m / s. The maximum return oil flow rate is determined by the flow velocity. The volume of the hydraulic oil tank generally does not exceed three times the return oil flow rate. Under the maximum volume limitation condition, the maximum number of columns in the internal flow channel combination unit and the external pipeline combination unit is determined. Let the inner diameter of the used return oil pipe 3 be c, then the maximum volume calculation formula is: .

[0041] In a preferred embodiment of the present invention, the arc-shaped baffle 8 is designed for jet-flow degassing, wherein the quarter-circular arc structure is tangent to the inner hole of the oil outlet to reduce the impact of the oil on the baffle and form a vortex flow field to precipitate bubbles and settle impurities; the horizontal structure is used to extend the flow channel and increase the residence time of the oil, thereby increasing the static degassing and impurity removal capacity; the inclined plane structure is used to form an upward-throwing structure to stabilize the flow field and allow free bubbles to merge and escape, and its height is less than the height of the quarter-circular arc structure. In the built-in flow channel assembly unit, the arc-shaped baffles 8 are arranged in an alternating left-right layout from top to bottom to form a serpentine flow channel, that is, the quarter-circular arc structure and the inclined plane structure of adjacent baffles are mirror-symmetrically distributed, and the oil jetted out by the inclined plane structure is tangent to the quarter-circular arc structure of the next layer; in the external pipeline assembly unit, the arc-shaped baffle 8 forms a serpentine flow channel with the bottom surface of the oil tank unit, and the oil is tangent to the quarter-circular arc structure of the next layer through the oil inlet.

[0042] like Figure 11 and Figure 12As shown, the integrated hydraulic oil tank is composed of an integrated metal shell, which is formed by cutting, bending and welding with gas metal arc welding. The upper side of the third step unit of the integrated metal shell is provided with a return oil pipe 3, an oil filler cap 1 and an air filter 2 in sequence. The left side of the third step unit is provided with a level gauge 4. The interior of the third step unit is provided with two arc baffles 8 with the same structure. The first side of the arc baffle 8 is a quarter arc structure, the middle is a horizontal structure, and the second side is a sloping structure. This structure can extend the flow channel to promote the escape of oil bubbles and the sedimentation of solid particles. The two arc baffles 8 are arranged alternately. The interior of the second step unit of the integrated metal shell is provided with three vertical baffles 11 that alternate between upper and lower. The left side of the first step unit of the integrated metal shell is provided with an oil suction pipe 5. The third step unit, the second step unit and the first step unit are connected by square interfaces.

[0043] The following describes in further detail, with reference to embodiments, a stepped hydraulic oil tank with a long flow channel and a three-phase separation method according to the present invention: The specific process of the three-phase separation method for a stepped hydraulic oil tank with built-in flow channel assembly unit is as follows: like Figure 3 As shown, the oil enters the return oil zone 12 within the first oil tank unit 16, which is the highest oil tank unit in the inner stepped oil tank unit, through the return oil pipe 3 on the first oil tank unit 16. It then flows sequentially into the second oil tank unit 17 and the third oil tank unit 18, which are arranged alternately in the same row, through the oil outlet on the first oil tank unit 16. The flow path is from top to bottom through the degassing and impurity removal zone 13 formed by the second oil tank unit 17 and the third oil tank unit 18. In the degassing and impurity removal zone 13, the oil flows along a serpentine flow channel formed by a circular arc baffle 8 with a quarter-circle structure at the first end and an inclined plate structure at the second end. The circular arc structure can promote the aggregation and separation of air bubbles in the oil through the vortex effect, and the inclined plate structure can guide the sedimentation of solid particles. At the same time, the circular arc baffle 8 can significantly prolong the residence time of the oil in the tank, improving the degassing, impurity removal and heat dissipation functions of the oil tank. The oil then enters the sixth oil tank unit 21, which is located at the end of the second highest oil tank unit in the inner stepped oil tank unit, through the connector 6 on the fifth oil tank unit 20.

[0044] like Figure 4 and Figure 5 As shown, the oil enters from the connector of the sixth oil tank unit 21 and rises to the fourth oil tank unit 19, prolonging the residence time of the oil in the oil tank. It then passes through the serpentine flow channel formed by the arc baffle 8 in the degassing and impurity removal zone 13 composed of the second oil tank unit 17 and the third oil tank unit 18 in the second highest row of oil tank units. In the same way, it enters the fifth oil tank unit 20 at the end of the second highest row of oil tank units in the inner stepped row of oil tank units to perform degassing and impurity removal. The above process is repeated until the oil passes through all rows of oil tank units in the inner stepped row of oil tank units.

[0045] like Figure 6 As shown, the oil enters the steady flow zone 14 formed by the seventh oil tank unit 22 from the connector 6 of the lowest oil tank unit in the inner stepped oil tank unit. In the steady flow zone 14, the oil velocity decreases in the straight flow channel and the flow becomes smooth. It leaves the built-in flow channel combination unit through the oil suction pipe 5, thereby completing the three-phase separation of the oil.

[0046] The specific process of the three-phase separation method for a stepped hydraulic oil tank with an external pipeline assembly unit is as follows: like Figure 9 As shown, the oil enters the return oil zone 12 within the eighth oil tank unit 23 of the highest column of the outer stepped oil tank unit via the return oil pipe 3. It then flows sequentially through the outlet of the eighth oil tank unit 23 into the tenth oil tank unit 25 and the eleventh oil tank unit 26 arranged in the same column. The flow path passes from top to bottom through the degassing and impurity removal zone 13 formed by the tenth and eleventh oil tank units 25 and 26 connected in sequence. Under the action of the quarter-circle structure in the degassing and impurity removal zone 13, the oil forms a vortex flow field. Centrifugal force promotes the rising and precipitation of bubbles and the settling of solid impurity particles. The oil is guided through the inclined plane structure to the lower arc baffle 8 for repeated degassing and impurity removal. Finally, it enters the inlet of the ninth oil tank unit 24, the first unit in the second-highest column of the outer stepped oil tank unit, through the hose 7 connected to the outlet of the eleventh oil tank unit 26. The hose 7 extends the residence time of the oil in the tank.

[0047] like Figure 10 As shown, the oil enters the ninth oil tank unit 24 in the second-highest oil tank unit through the hose 7, prolonging the residence time of the oil in the tank. After passing through the degassing and impurity removal zone 13 composed of the ninth oil tank unit 24, the tenth oil tank unit 25 and the eleventh oil tank unit 26 connected in sequence, the oil enters the inlet of the ninth oil tank unit 24, which is the first position in the second-highest oil tank unit in the outer stepped oil tank unit, through the hose 7 connected to the oil outlet on the eleventh oil tank unit 26. The above process is repeated until the oil passes through all the oil tank units in the outer stepped oil tank unit.

[0048] The oil enters the steady flow zone 14 formed by the twelfth oil tank unit 27 from the joint 7 of the lowest oil tank unit in the outer stepped oil tank unit. In the steady flow zone 14, the oil velocity decreases in the straight flow channel, the flow is gentle, the local eddies are reduced, and the oil leaves the outer pipeline assembly unit through the oil suction pipe 5, thereby completing the three-phase separation of the oil.

[0049] The specific process of the three-phase separation method for a stepped hydraulic oil tank with an integrated configuration is as follows: The oil enters the third-stage unit through the return pipe 3 of the third-stage unit of the integrated metal shell 15. After passing through the degassing and impurity removal zone 13 composed of arc baffles 8, it enters the degassing and impurity removal zone 13 composed of vertical baffles 11 in the second-stage unit through the square interface on the third-stage unit. Then, it enters the flow stabilization zone 14 of the first-stage unit through the square interface on the second-stage unit. Finally, it leaves the integrated hydraulic oil tank through the oil suction pipe 5 of the first-stage unit, thus completing the three-phase separation of the oil.

[0050] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A stepped hydraulic oil tank with a long flow channel, comprising an inner stepped row of oil tank units and a seventh oil tank unit, characterized in that, The inner stepped oil tank unit includes a first oil tank unit, a second oil tank unit, a third oil tank unit, a fourth oil tank unit, a fifth oil tank unit, and a sixth oil tank unit. The second and third oil tank units are respectively provided with arc-shaped partitions and vertical partitions inside. The arc-shaped partitions include arc segments, horizontal segments, and inclined segments. The cut of the arc segment is located at the oil inlet of the oil tank unit, and the cut of the inclined segment is located at the oil outlet of the oil tank unit. The horizontal segment contacts the lower wall of the oil tank unit. In the second oil tank unit, the vertical partition is located at the inclined segment. In the third oil tank unit, the vertical partition is located at the arc segment. The fifth and sixth oil tank units are provided with vertical partitions inside. The first oil tank unit is located at the first position of the highest row of oil tank units in the inner stepped oil tank unit, and the fourth oil tank unit is located at the first position of the second-highest row of oil tank units in the inner stepped oil tank unit. In the inner stepped oil tank unit, the first column of oil tank units is arranged from the first position to the last position as the fourth oil tank unit, the second oil tank unit, and the sixth oil tank unit. In the inner stepped oil tank unit, the second column of oil tank units is arranged from the first position to the last position as the fourth oil tank unit, the second oil tank unit, the third oil tank unit, and the fifth oil tank unit. Starting from the third oil tank unit, including the third oil tank unit, for each additional column, a second or third oil tank unit is added to the second-to-last position of the next column. The second and third oil tank units alternate. The sixth and fifth oil tank units alternate at the end of each column. In each column of the inner stepped oil tank unit, the second and third oil tank units alternate, and there is one sixth or fifth oil tank unit. The expression for the number of columns of the built-in flow channel assembly unit is: ； In the formula, a is the volume of a single oil tank unit in the built-in flow channel assembly unit, and x is the number of columns of the built-in flow channel assembly unit. Based on the installation positions of the return oil pipe and suction oil pipe in the stepped hydraulic oil tank of the built-in flow channel assembly unit and the stepped hydraulic oil tank of the external pipeline assembly unit, as well as the return oil flow rate, the expression for the maximum volume is: ； In the formula, c is the inner diameter of the return oil pipe.

2. The stepped hydraulic oil tank with a long flow channel according to claim 1, characterized in that: In the built-in flow channel assembly unit, the seventh oil tank unit has an oil suction pipe on its left side, the first oil tank unit has an oil filler cap and an air filter on its upper side, and the first oil tank unit has a return oil pipe on its left side. Starting from the third row of oil tank units in the inner stepped row, the second oil tank unit, the highest in each row, has a level gauge on one side. The first oil tank unit has an oil outlet on its lower side, the fourth oil tank unit has an oil outlet on its lower side, the second and third oil tank units have an oil inlet and an oil outlet on their upper and lower sides, respectively, the fifth and sixth oil tank units have an oil inlet on their upper side, and the oil outlet and oil inlet form an inter-row oil port. The fifth and sixth oil tank units have a connector on their front side.

3. The stepped hydraulic oil tank with a long flow channel according to claim 1, characterized in that: In the inner stepped row of fuel tank units, starting from the third column, if the second-to-last position in the previous column is the second fuel tank unit, then the second-to-last position in the next column is the third fuel tank unit; if the second-to-last position in the previous column is the third fuel tank unit, then the second-to-last position in the next column is the second fuel tank unit; if the last position in the previous column is the fifth fuel tank unit, then the last position in the next column is the sixth fuel tank unit; if the second-to-last position in the previous column is the sixth fuel tank unit, then the last position in the next column is the fifth fuel tank unit.

4. A three-phase separation method for a stepped hydraulic oil tank with a long flow channel as described in any one of claims 1 to 3, characterized in that, It includes: The oil enters the return oil zone of the first oil tank unit through the return oil pipe on the first oil tank unit in the highest row of the inner stepped oil tank unit. It then flows sequentially into the second and third oil tank units arranged alternately in the same row through the oil outlet on the first oil tank unit. The flow path passes from top to bottom through the degassing and impurity removal zone composed of the second and third oil tank units, and then enters the sixth oil tank unit at the end of the second highest row of the inner stepped oil tank unit through the connector on the fifth oil tank unit. The oil enters from the connector of the sixth oil tank unit and rises to the fourth oil tank unit. It then passes through the degassing and impurity removal zone composed of the second and third oil tank units in the second highest column of the oil tank unit. In the same way, it enters the fifth oil tank unit at the end of the second second highest column of the inner stepped oil tank unit to perform degassing and impurity removal. The above process is repeated until the oil passes through all columns of oil tank units in the inner stepped oil tank unit. After the oil enters the steady flow zone formed by the seventh oil tank unit from the joint of the lowest row of the inner stepped oil tank unit, it leaves the built-in flow channel assembly unit through the oil suction pipe, thus completing the three-phase separation of the oil.

5. A stepped hydraulic oil tank with a long flow channel, comprising an outer stepped oil tank unit and a twelfth oil tank unit, characterized in that, The outer stepped oil tank unit includes an eighth, ninth, tenth, and eleventh oil tank unit. The ninth, tenth, and eleventh oil tank units are equipped with arc-shaped partitions inside. The arc-shaped partitions include arc segments, horizontal segments, and inclined segments. The inner arc surface of the arc segment is located below the oil inlet of the oil tank unit, and the outer arc surface of the arc segment is located above the oil outlet of the oil tank unit. The horizontal segment is located on the side wall of the oil tank unit and is a certain distance away from the lower wall. The eighth oil tank unit is located at the first position of the highest row in the outer stepped oil tank unit, and the ninth oil tank unit is located at the first position of the second stepped oil tank unit in the outer stepped oil tank unit. In the outer stepped oil tank unit, the first column of oil tank units is arranged from the first position to the last position as the ninth oil tank unit and the eleventh oil tank unit. In the outer stepped oil tank unit, the second column of oil tank units is arranged from the first position to the last position as the ninth oil tank unit, the tenth oil tank unit, and the eleventh oil tank unit. In the outer stepped oil tank unit, starting from the third column of oil tank units, for each additional column, a tenth oil tank unit is added to the second-to-last position of the next column. The expression for the number of columns of the external pipeline assembly unit is: ； In the formula, b is the volume of a single oil tank unit in the external pipeline assembly unit, and y is the number of columns in the external pipeline assembly unit; Based on the installation positions of the return oil pipe and suction oil pipe in the stepped hydraulic oil tank of the external pipeline assembly unit and the return oil flow rate, the expression for the maximum volume is: ； In the formula, c is the inner diameter of the return oil pipe.

6. The stepped hydraulic oil tank with a long flow channel according to claim 5, characterized in that: In the external pipeline assembly unit, the right side of the twelfth oil tank unit is equipped with an oil suction pipe, and the upper side of the eighth oil tank unit is equipped with an oil filler cap, an air filter and an oil return pipe in sequence. Starting from the second column, the eighth oil tank unit and the ninth oil tank unit, which are the highest in each column, are equipped with a liquid level gauge on one side.

7. The stepped hydraulic oil tank with a long flow channel according to claim 5, characterized in that: In the outer stepped row of oil tank units, the lower side of the eighth oil tank unit is provided with an oil outlet, the upper and lower sides of the ninth and tenth oil tank units are provided with oil inlets and oil outlets respectively, the upper and left sides of the eleventh oil tank unit are provided with oil inlets and oil outlets respectively, and the upper side of the twelfth oil tank unit is provided with an oil inlet. In two adjacent rows of the outer stepped row of oil tank units, the oil outlet of the eleventh oil tank unit is connected to the oil inlet of the ninth oil tank unit through a hose, and the oil outlet of the eleventh oil tank unit in the lowest row of the outer stepped row of oil tank units is connected to the oil inlet of the twelfth oil tank unit through a hose.

8. A three-phase separation method for a stepped hydraulic oil tank with a long flow channel as described in any one of claims 5 to 7, characterized in that, It includes: The oil enters the return oil zone of the eighth oil tank unit in the highest row of the outer stepped oil tank unit through the return oil pipe on the eighth oil tank unit. It then flows into the tenth and eleventh oil tank units arranged in the same row through the oil outlet on the eighth oil tank unit. The flow path passes from top to bottom through the degassing and impurity removal zone formed by the tenth and eleventh oil tank units connected in the same row. Finally, it enters the oil inlet of the ninth oil tank unit, which is located at the first position in the second highest row of the outer stepped oil tank unit, through the hose connected to the oil outlet on the eleventh oil tank unit. The oil enters the ninth oil tank unit in the second-highest row of oil tank units through a hose. After passing through the degassing and impurity removal zone composed of the ninth, tenth, and eleventh oil tank units connected in sequence in this row, the oil enters the inlet of the ninth oil tank unit, which is the first position in the second-highest row of oil tank units in the outer stepped oil tank units, through the hose connected to the oil outlet of the eleventh oil tank unit. The above process is repeated until the oil passes through all the oil tank units in the outer stepped oil tank units. After the oil enters the steady flow zone formed by the twelfth oil tank unit from the joint of the lowest oil tank unit in the outer stepped oil tank unit, it leaves the outer pipeline assembly unit through the oil suction pipe, thus completing the three-phase separation of the oil.

9. A stepped hydraulic oil tank with a long flow channel, characterized in that, It includes an integrated metal casing. The upper side of the third step unit of the integrated metal casing is provided with an oil return pipe, an oil filler cap and an air filter in sequence. The left side of the third step unit is provided with a level gauge. The interior of the third step unit is provided with two arc-shaped partitions with the same structure, which are arranged alternately. The interior of the second step unit of the integrated metal casing is provided with three vertical partitions that alternate between upper and lower. The left side of the first step unit of the integrated metal casing is provided with an oil suction pipe. The connection between the third step unit, the second step unit and the first step unit is provided with a square interface.

10. A three-phase separation method for a stepped hydraulic oil tank with a long flow channel as described in claim 9, characterized in that, It includes: The oil enters the third-stage unit through the return pipe of the integrated metal shell. After passing through the degassing and impurity removal zone composed of arc baffles, it enters the degassing and impurity removal zone composed of vertical baffles in the second-stage unit through the square interface on the third-stage unit. Then, it enters the flow stabilization zone of the first-stage unit through the square interface on the second-stage unit. Finally, it leaves the integrated hydraulic oil tank through the oil suction pipe of the first-stage unit, thus completing the three-phase separation of the oil.

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