A multi-stage filtering device for waste mineral oil

Abstract

The present invention relates to the field of filtering technology, and in particular provides a multi-stage filtering device for waste mineral oil, comprising a filter tank, a filter plate, and a plurality of filter assemblies. The filter tank contains waste mineral oil to be filtered, and an oil outlet is provided at the bottom of the filter tank. The filter plate is provided at the bottom of the filter tank and is located above the oil outlet. A plurality of filter assemblies are stacked above the filter plate in a vertical direction. Each filter assembly is in the shape of a round cake, and each filter assembly includes a support frame and a filter cloth covering the support frame; wherein a sliding assembly is provided on the support frame, and the sliding assembly is configured to move along the support frame to push the filter cloth. The solution of the present invention, by providing a movable sliding assembly on the support frame inside the filter cloth, uses the sliding assembly to push the filter cloth, so that the shape of the filter cloth is constantly changed, thereby reducing the risk of hardening of the oil residue accumulated on the filter cloth, thereby improving the filtering efficiency of the device and ensuring the filtering effect.

Description

Technical Field

[0001] The present invention relates to the field of filtering technology, in particular to a multi-stage filtering device for waste mineral oil. Background Art

[0002] Waste mineral oil recycling requires a multi-stage process involving oil-water separation, filtration, sedimentation, and heating. To ensure optimal filtration, multiple stages are typically used. However, impurities such as oil residue in the waste mineral oil can easily accumulate on the filter cloth and form a compaction, leading to clogging. This not only severely impacts filtration effectiveness and efficiency, but also makes cleaning difficult and increases cleaning costs. Summary of the Invention

[0003] The purpose of the present invention is to reduce the risk of clogging of the filter cloth and improve the filtering efficiency.

[0004] In particular, the present invention provides a multi-stage filtering device for waste mineral oil, comprising: a filter tank, which contains waste mineral oil to be filtered and is provided with an oil outlet at its bottom; a filter plate, which is arranged at the bottom of the filter tank and is located above the oil outlet; a plurality of filter assemblies stacked above the filter plate in a vertical direction; each filter assembly is in the shape of a round cake, and each filter assembly includes a support frame and a filter cloth covering the support frame; wherein a sliding assembly is provided on the support frame, and the sliding assembly is configured to move along the support frame to push the filter cloth.

[0005] Furthermore, the support frame is bent on a horizontal plane and connected end to end.

[0006] Furthermore, the support frame is configured in a spiral shape.

[0007] Furthermore, the sliding assembly includes: a slip ring, which is mounted on the support frame and is configured to slide along the support frame; a spring plate, which is mounted on the outside of the slip ring and is used to push the filter cloth; and a connecting rod, which is arranged between the slip ring and the spring plate and is used to connect the slip ring and the spring plate.

[0008] Furthermore, the sliding assembly also includes: a first roller, rotatably disposed on the slip ring and abutting against the support frame; a driving element, disposed on the slip ring and connected to the first roller, for driving the first roller to rotate.

[0009] Furthermore, the sliding assembly further includes: a second roller, which is rotatably disposed on the slip ring and abuts against the support frame; wherein the axis of the second roller is staggered with the axis of the first roller.

[0010] Furthermore, the shrapnel is configured in an olive shape.

[0011] Furthermore, the bottom wall of the filter tank is funnel-shaped, and the oil outlet is arranged at the bottom end of the bottom wall.

[0012] Furthermore, the multi-stage filtering device for waste mineral oil further includes: a pressurizing component for pressurizing the filter tank.

[0013] Furthermore, a connecting piece is provided on the filter cloth, and the connecting piece is connected to a connecting pipe to discharge part of the filtered liquid in the filter cloth out of the filter tank.

[0014] The beneficial effects of the present invention are:

[0015] The multi-stage filtration device for waste mineral oil of the present invention employs a movable sliding assembly disposed on a support frame within the filter cloth. This sliding assembly pushes against the filter cloth, causing the cloth's shape to continuously change. This reduces the risk of oil residue clumping on the filter cloth, leading to clogging, thereby improving the device's filtration efficiency and ensuring effective filtration. Furthermore, oil residue is less likely to clump on the filter cloth, making cleaning the filter cloth easier.

[0016] Furthermore, in the multi-stage filtering device for waste mineral oil of the present invention, the support frames are arranged to be connected end to end, so that when the sliding component moves on the support frame, it can move cyclically along the support frame, thereby ensuring the pushing effect of the sliding component on the filter cloth and improving the filtering efficiency.

[0017] Furthermore, in the multi-stage filtering device for waste mineral oil of the present invention, the component for pushing the filter cloth in the sliding assembly is set as a spring sheet, and the characteristics of its elastic material are utilized to ensure the pushing effect on the filter cloth while reducing the risk of wear and breakage of the filter cloth. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. In the accompanying drawings:

[0019] Figure 1 2 is a schematic structural diagram of a multi-stage filtering device for waste mineral oil according to an embodiment of the present invention;

[0020] Figure 2 is a schematic structural diagram from another angle of a multi-stage filtering device for waste mineral oil according to one embodiment of the present invention;

[0021] Figure 3 It is along Figure 2 A schematic cross-sectional view taken along the cutting line AA in FIG.

[0022] Figure 4 yes Figure 3 Schematic enlarged view of middle region B;

[0023] Figure 5 is a schematic structural diagram of a filter assembly according to one embodiment of the present invention;

[0024] Figure 6 It is along Figure 5 A schematic cross-sectional view taken along the cutting line CC in FIG.

[0025] Figure 7 yes Figure 6 Schematic enlarged view of middle region D;

[0026] Figure 8 yes Figure 6 Schematic enlargement of the middle region E;

[0027] Figure 9 is a schematic structural diagram of a filter assembly according to another embodiment of the present invention;

[0028] Figure 10 It is along Figure 9 A schematic cross-sectional view taken along the cutting line FF in FIG.

[0029] Figure 11 is a structural diagram of a sliding assembly according to an embodiment of the present invention;

[0030] Figure 12 It is along Figure 11 A schematic cross-sectional view taken along the cutting line GG in FIG.

[0031] Figure 13 is a schematic structural diagram of a slip ring and a connecting rod according to an embodiment of the present invention;

[0032] Figure 14 2 is a schematic structural diagram of a spring according to an embodiment of the present invention.

[0033] in:

[0034] 100, filter tank; 110, oil outlet; 120, support plate; 130, base; 131, first oil pipe; 132, second oil pipe; 140, bottom wall; 150, end cover; 151, locking block; 152, high-pressure air inlet; 153, pressure relief port; 154, pressure gauge; 160, oil outlet pipe; 170, third oil pipe; 180, switch; 200, filter plate; 300, filter assembly; 310, support frame; 320, filter Cloth; 330, connecting part; 331, first component; 332, first through hole; 333, second component; 334, second through hole; 335, fastener; 340, connecting pipe; 400, sliding assembly; 410, slip ring; 411, first roller; 412, driving element; 413, second roller; 420, spring; 430, connecting rod; 500, pressurizing assembly; 600, oil delivery assembly; 610, oil inlet pipe; 620, oil delivery pipe. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] The terms "first" and "second" in this document are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features, that is, include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. When a feature "includes or contains" one or more of the features it covers, unless otherwise specifically described, this indicates that other features are not excluded and may further include other features.

[0037] It should be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] Refer to the following Figures 1 to 14 The multi-stage filtering device for waste mineral oil provided by the present invention is described.

[0039] This embodiment provides a multi-stage filtering device for waste mineral oil, which generally includes: a filter tank 100 , a filter plate 200 , and a plurality of filter assemblies 300 .

[0040] The filter tank 100 contains waste mineral oil to be filtered, and an oil outlet 110 is provided at the bottom of the filter tank 100. A filter plate 200 is provided at the bottom of the filter tank 100, above the oil outlet 110. A plurality of filter assemblies 300 are stacked vertically above the filter plates 200. Each filter assembly 300 is in the shape of a circular pancake and includes a support frame 310 and a filter cloth 320 covering the support frame 310. A sliding assembly 400 is provided on the support frame 310 and is configured to move along the support frame 310 to push the filter cloth 320.

[0041] like Figure 3-4As shown, after the waste mineral oil passes through multiple filter assemblies 300 and filter plates 200 for multi-stage filtration, the resulting filtrate flows out of the oil outlet 110 at the bottom end of the filter tank 100. During the filtration process, as the waste mineral oil flows from the outside of the filter cloth 320 to the inside of the filter cloth 320, the filter cloth 320, driven by the flowing waste mineral oil, approaches the support frame 310. Simultaneously, impurities such as oil residue in the waste mineral oil gradually accumulate on the filter cloth 320. As the oil residue continues to accumulate, it tends to become compacted, causing clogging of the filter cloth 320, thereby affecting the filtration effect.

[0042] In this embodiment, a sliding assembly 400 is disposed on the support frame 310, so that the area of ​​the filter cloth 320 corresponding to the sliding assembly 400 is pushed and supported by the sliding assembly 400. The sliding assembly 400 is configured to move along the support frame 310, so that the area of ​​the filter cloth 320 that is pushed and supported continuously changes with the movement of the sliding assembly 400. The continuous change in the shape of the filter cloth 320 prevents impurities such as oil residue from accumulating on the filter cloth 320 from becoming compacted, thereby reducing the risk of clogging the filter cloth 320, ensuring filtration effectiveness, and improving filtration efficiency.

[0043] like Figure 3-4 As shown, an annular support plate 120 may be provided at the bottom of the filter tank 100. The support plate 120 extends from the inner wall surface of the side wall of the filter tank 100 to the interior of the filter tank 100 to support the filter plate 200. The filter plate 200 is placed directly on the support plate 120, which not only has a stable structure, but also is easy to install and disassemble, reducing the difficulty of subsequent cleaning. A base 130 may be provided below the filter tank 100 to support the filter tank 100. A first oil drain pipe 131 may be provided on the base 130, and the first oil drain pipe 131 is connected to the oil outlet 110 to discharge the filtered liquid to the outside. In some embodiments, the base 130 may be integrally formed with the filter tank 100.

[0044] The support frame 310 is bent on a horizontal plane and connected end to end.

[0045] In the solution of this embodiment, the support frame 310 is bent, which increases the moving path of the sliding component 400 and the area of ​​the filter cloth 320 that the sliding component 400 can push, further reducing the risk of clogging of the filter cloth 320 and improving the filtering effect.

[0046] The support frame 310 is arranged end to end so that the sliding assembly 400 can continuously move in a circular motion on the support frame 310, thereby ensuring the pushing effect. Moreover, there is no problem of turning around, and moving in one direction makes the operation more stable, the pushing efficiency is higher, and the pushing effect is better.

[0047] The support frame 310 is configured in a scroll shape.

[0048] In the solution of this embodiment, the support frame 310 is configured into a spiral shape that is more compatible with the circular shape of the filter cloth 320, so that the area where the sliding component 400 can be pushed is maximized, and the curvature of the spiral support frame 310 is smaller, so that the movement of the sliding component 400 is smoother, thereby improving the pushing efficiency.

[0049] The sliding assembly 400 generally includes a slip ring 410, a spring clip 420, and a connecting rod 430. The slip ring 410 is mounted on the support frame 310 and is configured to slide along the support frame 310. The spring clip 420 is mounted on the outside of the slip ring 410 and is used to push the filter cloth 320. The connecting rod 430 is disposed between the slip ring 410 and the spring clip 420 to connect the slip ring 410 and the spring clip 420.

[0050] In this embodiment, the structure in the sliding assembly 400 that directly contacts the filter cloth 320 is provided as a spring 420. By utilizing its elastic properties, the risk of wear on the filter cloth 320 is reduced, thereby increasing the service life of the filter cloth 320. The spring 420 is preferably made of an elastic metal material, which not only has excellent elasticity and recovery capabilities, but also has good corrosion resistance.

[0051] The sliding assembly 400 is structured as two layers, the inner layer being a slip ring 410 sleeved on the support frame 310, and the outer layer being a spring plate 420 abutting against the filter cloth 320. The slip ring 410 and the spring plate 420 are connected by a connecting rod 430. While ensuring that the spring plate 420 can move synchronously with the slip ring 410, a gap is created between the slip ring 410 and the spring plate 420, allowing the spring plate 420 to deform relative to the slip ring 410. When the spring plate 420 is subjected to a large amount of pressure from the filter cloth 320, the spring plate 420 becomes flat, increasing the contact area between the spring plate 420 and the filter cloth 320, thereby reducing the unit contact stress between the spring plate 420 and the filter cloth 320. This, while ensuring that the spring plate 420 pushes the filter cloth 320, reduces the risk of wear and tear on the filter cloth 320.

[0052] In some preferred embodiments, the slip ring 410 and the spring sheet 420 can be connected by only one connecting rod 430, thereby ensuring that the spring sheet 420 can move synchronously with the slip ring 410 while increasing the deformation range of the spring sheet 420 and making the deformation of the spring sheet 420 smoother. The connecting rod 430 and the slip ring 410 can be fixedly connected or integrally formed, and the connecting rod 430 and the spring sheet 420 can be snapped together to reduce the difficulty of installation. The slip ring 410 can be formed with an opening, and the slip ring 410 is preferably made of a material that has both rigidity and elasticity, thereby ensuring its structural stability while reducing the difficulty of installation and removal of the slip ring 410.

[0053] like Figure 7As shown, in some embodiments, the sliding assembly 400 may generally further include a first roller 411 and a driving element 412. The first roller 411 is rotatably disposed on the slip ring 410 and abuts against the support frame 310. The driving element 412 is disposed on the slip ring 410 and connected to the first roller 411 for driving the first roller 411 to rotate.

[0054] This embodiment employs a first roller 411 disposed on the slip ring 410 to abut against the support frame 310, and a drive element 412 to drive the first roller 411 to rotate, thereby driving the slip ring 410 to move along the support frame 310. The first roller 411 is preferably disposed in the upper portion of the slip ring 410, and the connecting rod 430 is preferably disposed in the lower portion of the slip ring 410. This utilizes the weight of the slip ring 410 to better abut the first roller 411 against the support frame 310, thereby reducing the risk of the first roller 411 slipping. The drive element 412 can preferably be a motor, such as a submersible motor.

[0055] In other embodiments, the sliding assembly 400 may be magnetic. The support frame 310 may be provided with an electromagnetic device that can be intermittently energized in both positive and negative directions to generate an attractive force or a repulsive force to attract or push the sliding assembly 400 to move on the support frame 310 .

[0056] like Figure 7 As shown, in some embodiments, the sliding assembly 400 may further include a second roller 413. The second roller 413 is rotatably disposed on the slip ring 410 and abuts against the support frame 310; wherein the axis of the second roller 413 is staggered with the axis of the first roller 411.

[0057] In the solution of this embodiment, a first roller 411 and a second roller 413 with staggered axes are simultaneously provided on the slip ring 410, so that under the joint support of the first roller 411 and the second roller 413, there is a certain gap between the slip ring 410 and the support frame 310, thereby reducing the frictional resistance between the slip ring 410 and the support frame 310 when the slip ring 410 moves, making the movement of the slip ring 410 smoother and improving the structural stability.

[0058] like Figure 7 As shown, in some embodiments, the cross-section of the support frame 310 is a diamond shape, with one diagonal line arranged vertically. The slip ring 410 is arranged in a suitable diamond shape, with an opening formed at its top. The upper half of the slip ring 410 is provided with a rotatable first roller 411 and a second roller 413, respectively. The first roller 411 and the second roller 413 are located at both ends of the opening and respectively abut against two edge surfaces of the support frame 310.

[0059] In some preferred embodiments, the spring 420 is configured in an olive shape.

[0060] like Figure 11-12 As shown, the spring piece 420 is composed of two curved surfaces symmetrical with respect to the horizontal plane, which can be connected by welding. The olive-shaped shape formed by the spring piece 420 can effectively reduce the resistance between the spring piece 420 and the filtrate during movement, thereby improving the movement efficiency of the spring piece 420 and further reducing the risk of clogging of the filter cloth 320.

[0061] The bottom wall 140 of the filter tank 100 is funnel-shaped, and the oil outlet 110 is disposed at the bottom end of the bottom wall 140 .

[0062] In this embodiment, the bottom wall 140 of the filter canister 100 is designed in a funnel shape, and the oil outlet 110 is located at the very bottom of the bottom wall 140. This utilizes the mineral oil's own gravity to assist its flow, thereby improving the efficiency of mineral oil discharge. Furthermore, before cleaning the filter assembly 300, the mineral oil in the filter canister 100 must be drained. The funnel-shaped bottom wall 140 reduces the risk of residual mineral oil in the filter canister 100, improving both the effectiveness and efficiency of the discharge.

[0063] The multi-stage filtering device for waste mineral oil may generally further include a pressurizing component 500 . The pressurizing component 500 is used to pressurize the inside of the filter tank 100 .

[0064] The solution of this embodiment increases the flow efficiency of the mineral oil and thus the filtration efficiency by providing a pressurizing assembly 500 to pressurize the filter tank 100. The pressurizing assembly 500 can be provided on the base 130, and the pressurizing assembly 500 can preferably be provided as an air pump. A removable end cap 150 is provided at the top of the filter tank 100, and the end cap 150 seals the filter tank 100 under the action of a plurality of locking blocks 151. The end cap 150 is provided with a high-pressure air inlet 152 connected to the air pump, a pressure relief port 153 for pressure relief, and a pressure gauge 154.

[0065] A connecting piece 330 is provided on the filter cloth 320 , and the connecting piece 330 is connected to a connecting pipe 340 to discharge the filtered liquid in the filter cloth 320 out of the filter tank 100 .

[0066] The solution of this embodiment is to provide a connector 330 on the filter cloth 320 and a connecting pipe 340 connected to the outside world on the connector 330, so that part of the filtered liquid in the filter cloth 320 is discharged from the filter tank 100 through the connecting pipe 340, thereby increasing the discharge path of the filtered liquid and improving the filtration efficiency.

[0067] like Figure 8As shown, the connector 330 includes a first member 331 and a second member 333. The first and second members 331, 333 are located on the inner and outer sides of the filter cloth 320, respectively, and together clamp the filter cloth 320. A first through-hole 332 is formed in the first member 331, located on the outer side of the filter cloth 320, and a second through-hole 334 is formed in the second member 333, located on the inner side. One end of the first through-hole 332 is connected to the connecting pipe 340, and the other end faces the second through-hole 334. Filtrate in the filter cloth 320 passes through the second through-hole 334, then flows through the first through-hole 332, and finally flows into the connecting pipe 340. In some embodiments, the first and second members 331, 333 can be connected by fasteners 335 (such as screws, studs, etc.). In other embodiments, the first and second members 331, 333 can be directly snapped together, and a sealing ring can be provided between the first and second members 331, 333.

[0068] like Figure 8 As shown, the exterior of the filter tank 100 is provided with multiple oil outlet pipes 160, which are connected one-to-one to the multiple connecting pipes 340. A second oil drain pipe 132 can be provided on the base 130, with each oil outlet pipe 160 leading to the second oil drain pipe 132. Filtrate produced by different filtration paths is discharged from the first and second oil drain pipes 131 and 132, respectively, to facilitate subsequent classification processing. A third oil drain pipe 170 is also provided at the bottom of the filter tank 100. This third oil drain pipe 170 is located above the filter plate 200 and is used to discharge unfiltered waste mineral oil before cleaning the filter cloth 320.

[0069] An oil delivery assembly 600 is also provided on the base 130. One end of the oil delivery assembly 600 is connected to the filter tank 100 via an oil delivery pipe 620, and the other end is connected to the outside world via an oil inlet pipe 610. Waste mineral oil flows through the oil inlet pipe 610 to the oil delivery assembly 600. Then, under the action of the oil delivery assembly 600, it flows into the filter tank 100 through the oil delivery pipe 620. The oil delivery assembly 600 is preferably configured as an oil pump. A switch 180 can be provided on the base 130 to control the start and stop of the air pump and the oil pump.

[0070] In some preferred embodiments, a control valve for controlling the on-off of the pipeline can be provided on the first oil drain pipe 131, the second oil drain pipe 132, the third oil drain pipe 170, the oil delivery pipe 620 and each oil outlet pipe 160 to control the filtering process of the waste mineral oil.

[0071] The specific working process of the multi-stage filtering device for waste mineral oil provided by the present invention is described in combination with the above embodiments:

[0072] The oil pump is started, and the waste mineral oil flows through the oil inlet pipe 610 and the oil delivery pipe 620 in sequence under the action of the oil pump, and is injected into the filter tank 100.

[0073] The air pump starts and injects high-pressure gas into the filter tank 100 through the high-pressure air inlet 152, forcing the waste mineral oil to pass through the filter cloth 320 and into the filter cloth 320. Part of the filtrate in the filter cloth 320 flows through the connector 330, the connecting pipe 340, the oil outlet pipe 160, and the second oil drain pipe 132 in sequence before being discharged. The remaining filtrate passes through the multiple layers of filter cloth 320 and the filter plate 200, flows to the bottom end of the filter tank 100, and then flows through the oil outlet 110 and the first oil drain pipe 131 before being discharged.

[0074] During the filtration process, the drive element 412 drives the first roller 411 to rotate, causing the slip ring 410 to move along the support frame 310, thereby driving the spring plate 420 to move, causing it to continuously push against the filter cloth 320. The filter cloth 320 continuously deforms, reducing the risk of oil residue compacting and clogging on the filter cloth 320, thereby ensuring effective filtration and improving filtration efficiency. As impurities such as oil residue accumulate on the filter cloth 320 and the pressure within the filter canister 100 rises, the pressure exerted by the filter cloth 320 against the spring plate 420 gradually increases. Under the pressure of the filter cloth 320, the spring plate 420 deforms and gradually approaches the support frame 310. As the spring plate 420 flattens, the contact area between the spring plate 420 and the filter cloth 320 increases, reducing the specific contact stress. This ensures the spring plate 420's pushing effect on the filter cloth 320 while reducing the risk of wear and tear on the filter cloth 320.

[0075] After the filtration is completed, after the liquid in the filter tank 100 is completely discharged through the first oil drain pipe 131, the second oil drain pipe 132 and the third oil drain pipe 170, the end cover 150 of the filter tank 100 is opened, the filter assembly 300 and the filter plate 200 are taken out, and the oil residue attached thereto is cleaned.

[0076] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above-described embodiments merely illustrate several embodiments of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A multi-stage filtering device for waste mineral oil, characterized in that: include: A filter tank containing waste mineral oil to be filtered and having an oil outlet at its bottom; A filter plate is arranged at the bottom of the filter tank and located above the oil outlet; Multiple filter assemblies are stacked vertically above the filter plate; each filter assembly is in the shape of a circular pancake and includes a support frame and a filter cloth covering the support frame; wherein a sliding assembly is provided on the support frame and is configured to move along the support frame to push the filter cloth; the support frame is curved on a horizontal plane and connected end to end so that the sliding assembly can continuously circulate on the support frame without turning around, and the support frame is configured in a vortex shape; the sliding assembly includes: A slip ring is sleeved on the support frame and is configured to slide along the support frame; The spring piece is sleeved on the outside of the slip ring and is used to push the filter cloth; A connecting rod is provided between the slip ring and the spring piece and is used to connect the slip ring and the spring piece; A first roller is rotatably disposed on the slip ring and abuts against the support frame; a driving element, disposed on the slip ring and connected to the first roller, for driving the first roller to rotate; The second roller is rotatably mounted on the slip ring and abuts against the support frame; wherein the axis of the second roller is staggered with the axis of the first roller; The structure of the sliding assembly is set to an inner and outer layer. The inner layer is a slip ring set on the support frame, and the outer layer is a spring plate set to abut against the filter cloth. The slip ring and the spring plate are connected by a connecting rod. While ensuring that the spring plate can move synchronously with the slip ring, a gap is maintained between the slip ring and the spring plate. The cross-section of the support frame is rhombus-shaped, and one of the diagonals is vertically arranged. The slip ring is arranged into an adaptive rhombus with an opening formed at the top. The first roller and the second roller are located at both ends of the opening and respectively abut against the two edge surfaces of the support frame.

2. The multi-stage filtering device for waste mineral oil according to claim 1, characterized in that: The shrapnel is configured in an olive shape.

3. The multi-stage filtering device for waste mineral oil according to claim 1, characterized in that: The bottom wall of the filter tank is funnel-shaped, and the oil outlet is arranged at the bottom end of the bottom wall.

4. The multi-stage filtering device for waste mineral oil according to claim 1, characterized in that: Also includes: The pressurizing component is used to pressurize the filter tank.

5. The multi-stage filtering device for waste mineral oil according to claim 1, characterized in that: A connecting piece is provided on the filter cloth, and the connecting piece is connected with a connecting pipe to discharge part of the filtered liquid in the filter cloth out of the filter tank.

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