Oil-gas separator with variable flow section

Abstract

According to the oil-gas separator with the variable circulation section, gas can enter a first-stage channel cavity forwards in the axial direction from a channel inlet, then enters a second-stage channel cavity outwards in the radial direction through a vent hole, is subjected to adsorption separation of a first-stage filter element on one side of the second-stage channel cavity, enters a third-stage channel cavity forwards in the axial direction, and enters a third-stage channel cavity through a second-stage filter element; one side of the fourth-stage channel cavity is subjected to adsorption separation of the second-stage filter element, and the other side of the fourth-stage channel cavity is subjected to adsorption separation of the second-stage filter element to the channel outlet in the axial direction and is finally sprayed outwards from the channel outlet from back to front; and two oil dripping and returning positions are correspondingly arranged, one position is located under the first-stage filter element, and the other position is directly used as a channel outlet close to the second-stage filter element. The device is simple in structure and convenient to disassemble and assemble, and the flow section of the channel is automatically adjusted according to pressure difference; through the structural design of the three-stage sleeve, the two-stage filter element and two oil outlets, the fine separation effect and efficiency are improved on the premise that the size is minimized.

Description

Technical Field

[0001] The utility model belongs to the technical field of engines, and in particular relates to an oil-gas separator with a variable flow section. Background Art

[0002] When an engine is operating, the high-pressure combustible mixture and burned gas in the combustion chamber enter the crankcase through the gap between the piston and cylinder, among other processes. This mixture primarily consists of unburned fuel, air, hydrocarbons, and engine oil. This mixture dilutes the engine oil, reducing its performance and accelerating its oxidation and deterioration. Oil mixed with other impurities can easily clog the oil circuits. Acidic gases in the exhaust gas can enter the lubrication system, causing corrosion and accelerated wear of engine parts. Blow-by gas can also cause excessive crankcase pressure, disrupting the crankcase seal and causing oil leakage. Therefore, crankcase ventilation systems are now commonly used in automotive designs to address these issues. The oil-gas separator, a key component of the crankcase ventilation system, separates the oil from the mixed gas and returns it to the oil sump, preventing "burning oil" and the resulting adverse consequences of increased carbon deposits in the combustion chamber, unstable idling, and excessive exhaust emissions.

[0003] The oil-gas separation structure of the valve cover passes through the baffle and the orifice plate with felt. First, multiple baffles are set at the inlet to separate large oil droplets. Secondly, the fine separation orifice plate is used to separate small oil droplets through the felt. Under the action of gravity, the oil droplets return to the crankcase through the oil return port.

[0004] At present, most common crankcase ventilation systems adopt a passive oil-gas separation structure. The disadvantage of this structure is that the amount of blowby changes with the engine speed. From the principles of fluid mechanics, the higher the amount of blowby and the faster the flow rate, the greater the pressure loss inside the valve cover, resulting in a greater pressure difference between the inlet and outlet ends of the valve cover. According to the formula for liquid pressure, the internal pressure of the liquid is related to the height, so if the pressure difference is too large, the required oil return height will be higher, which is often more likely to cause poor oil return. When the gas flows, it is easy to carry oil into the engine, affecting the separation efficiency. On the other hand, excessive pressure difference will also affect the internal pressure of the crankcase. This situation is most likely to occur on large-displacement engines. Utility Model Content

[0005] In response to the problems existing in the prior art, the utility model provides an oil-gas separator with a variable flow section, which can make the pressure difference at the inlet and outlet ends of the valve chamber cover within a set range, thereby solving the technical problem of affecting the oil-gas separation efficiency due to excessive pressure difference at the inlet and outlet ends of the valve chamber cover.

[0006] The technical solutions are as follows:

[0007] A variable flow cross-section oil-gas separator, comprising a shell, wherein a channel formed in the shell consists of a channel inlet, a first-stage, a second-stage, a third-stage, a fourth-stage channel cavity and a channel outlet which are connected in sequence, the first-stage channel cavity being coaxially connected to the channel inlet, the second-stage channel cavity surrounding the periphery of the first-stage channel cavity and the two being connected by a plurality of vents, the size of the first-stage channel cavity and the number of vents being controlled by the axial movement of the piston, and when there is no pressure difference between the front and rear of the piston, the piston can move forward to block the channel inlet under the action of the resetting elastic force of the elastic unit; the fourth-stage channel cavity surrounding the periphery of the third-stage channel cavity and the two being connected by a plurality of vents, the second-stage channel cavity A first-stage filter element is provided, and a second-stage filter element is provided in the fourth-stage channel cavity; gas can enter the first-stage channel cavity axially forward from the channel inlet, and then enter the second-stage channel cavity radially outward through the vent hole, while receiving adsorption and separation by the first-stage filter element in the second-stage channel cavity, enter the third-stage channel cavity axially forward, and then enter the fourth-stage channel cavity radially outward through the vent hole, while receiving adsorption and separation by the second-stage filter element in the fourth-stage channel cavity, while moving axially backward to the channel outlet, and finally ejected outward from the channel outlet from back to front; two dripping return oil positions are correspondingly provided, one is the oil outlet hole located directly below the first-stage filter element, and the other is directly served by the channel outlet adjacent to the second-stage filter element.

[0008] Furthermore, the housing includes first-stage, second-stage, and third-stage sleeves, and the piston is installed in the first-stage sleeve. The piston can block the channel entrance, and when the piston moves backward, the first-stage channel cavity between the channel entrance and the front end surface of the piston in the first-stage sleeve can be expanded;

[0009] The front portion of the second-stage sleeve is sleeved outside the first-stage sleeve, and a gap is left between the inner wall of the front sleeve and the outer wall of the first-stage sleeve to form an annular second-stage passage cavity. A plurality of vent holes are formed through the wall of the first-stage sleeve to connect the first-stage passage cavity and the second-stage passage cavity. As the piston moves backward or forward in the first-stage sleeve, the number of exposed vent holes on the circumference of the first-stage passage cavity increases or decreases accordingly, thereby achieving variable adjustment to increase or decrease the flow cross-section between the first-stage passage cavity and the second-stage passage cavity.

[0010] The first-stage filter element is arranged in the second-stage channel cavity;

[0011] The rear portion of the second-stage sleeve is located behind the first-stage sleeve, and the third-stage passage cavity is located in the inner space of the sleeve at the rear portion of the second-stage sleeve;

[0012] The third-stage sleeve is fixedly mounted on the rear portion of the second-stage sleeve. An annular fourth-stage channel cavity is formed and maintained fixed between the inner wall of the third-stage sleeve and the outer wall of the rear portion of the second-stage sleeve. A plurality of vents for connecting the third-stage channel cavity and the fourth-stage channel cavity are provided on the rear wall of the second-stage sleeve. The second-stage filter element is disposed in the fourth-stage channel cavity.

[0013] A channel outlet is formed at the axial front end of the fourth-stage channel cavity between the inner wall of the third-stage sleeve at the barrel opening and the outer wall of the second-stage sleeve.

[0014] Furthermore, the multiple vent holes on the first-stage sleeve are arranged in a uniform pattern along the circumferential and axial directions of the sleeve wall.

[0015] Furthermore, a plurality of support ribs are formed on the outer wall of the first-stage sleeve, which are arranged at intervals in the circumferential direction and extend axially. The first-stage filter element is supported by the support ribs to maintain a fixed channel gap between the first-stage filter element and the outer wall of the first-stage sleeve.

[0016] Furthermore, the oil outlet hole is opened at the bottom of the second-stage sleeve wall and is adjacent to the channel entrance.

[0017] Furthermore, the channel outlet is shaped to gradually tilt outward from back to front, so that the gas coming out of the channel outlet is tilted and sprayed out of the shell from back to front, and the oil droplets adsorbed and collected by the second-stage filter element automatically drip from the lowest point of the channel outlet by gravity.

[0018] Furthermore, an annular sleeve is formed in the middle of the inner wall of the third-stage sleeve cover, and the rear end of the second-stage sleeve is embedded in the annular sleeve, thereby fixing the third-stage sleeve to the rear of the second-stage sleeve.

[0019] Furthermore, the elastic unit that provides the reset elastic force for the piston in the first-stage sleeve is partially accommodated in the inner space of the sleeve at the rear of the second-stage sleeve. The piston rod passes backward through the through hole of the sleeve cover at the rear of the first-stage sleeve. The second-stage sleeve extends forward from the center of the rear sleeve cover to form a support column. The support column is formed with a receiving groove for accommodating the piston rod. The spring is sleeved on the piston rod and its two ends respectively press against the piston and the bottom of the receiving groove.

[0020] Furthermore, the cover of the first-stage sleeve is detachable, and the front end surface of the support column abuts against the cover of the first-stage sleeve to prevent it from moving backward and falling out.

[0021] Furthermore, a plurality of support ribs are formed on the outer wall of the second-stage sleeve, which are arranged at intervals in the circumferential direction and extend axially. The second-stage filter element is supported by the support ribs to maintain a fixed channel gap between the second-stage filter element and the outer wall of the second-stage sleeve.

[0022] The utility model has a simple structure, is easy to disassemble and assemble, and can automatically adjust the flow cross-section of the channel according to the pressure difference; the structural design of the three-stage sleeve, two-stage filter element and two oil outlets effectively improves the effect and efficiency of fine separation while minimizing the volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings that constitute part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without making any creative efforts.

[0024] Figure 1 It is a cross-sectional schematic diagram of the oil-gas separation structure using the utility model;

[0025] Figure 2 for Figure 1 An enlarged schematic diagram of the dotted circle portion;

[0026] Figure 3 It is a three-dimensional schematic diagram of the utility model;

[0027] Figure 4 This is a partially exploded perspective view of the present invention from another perspective.

[0028] Reference numerals in the figures:

[0029] 1-valve cover; 2-oil-gas separation channel; 21-baffle; 31-coarse separation oil return hole; 32-fine separation oil return hole;

[0030] 4-Oil and gas separator;

[0031] 400 - channel entrance; 401 - first-stage channel cavity; 402 - second-stage channel cavity; 403 - third-stage channel cavity; 404 - fourth-stage channel cavity; 405 - channel exit; 406 - oil outlet;

[0032] 41-first stage sleeve; 411-vent; 412-exhaust hole; 413-cylinder cover; 414-support rib; 415-anti-error protrusion;

[0033] 42-piston; 421-piston rod; 422-spring;

[0034] 43-first stage filter element;

[0035] 44-second stage sleeve; 441-vent; 442-support column; 445-error proofing groove;

[0036] 45-third-stage sleeve; 450-annular ferrule; 451-connecting plate; 452-connecting piece;

[0037] 46-second stage filter element;

[0038] 47-partition. DETAILED DESCRIPTION

[0039] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0040] In the description of the embodiments of the present invention, it should be noted that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are only for the convenience of describing the present invention or simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operate in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0041] The term "plurality" in the present invention refers to more than two (including two). The terms "first", "second", etc. are only used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0042] Unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0044] like Figure 1 As shown, the utility model is placed inside the oil-gas separation channel 2 inside the valve chamber cover 1, and the oil-gas separation channel 2 is divided into a coarse separation area on the front side and a fine separation area on the rear side by a partition 47. The unseparated mixed gas enters the coarse separation area, and after hitting the baffle 21, the large particle oil droplets are adsorbed on the baffle 21, and flow into the coarse separation return oil tank under the action of gravity, and then flow into the crankcase through the coarse separation return oil hole 31; the remaining mixed gas enters the fine separation area after passing through the utility model installed on the partition, and the particle oil droplets after fine separation by the utility model flow into the fine separation return oil tank under the action of gravity, and then flow into the crankcase through the fine separation return oil hole 32.

[0045] like Figure 2 As shown, the shell of the utility model is composed of a three-stage sleeve, which constructs an internal channel composed of four-stage channel cavities connected in sequence, and utilizes the two-stage filter element in the channel to successively adsorb small particle oil droplets in the gas, thereby realizing fine oil and gas separation of the mixed gas; and, utilizing the movement of the piston 42 in the first-stage channel cavity under the action of the pressure difference, the size of the first-stage channel cavity is adjusted, thereby realizing the adjustment of the connecting area between the first-stage channel cavity and the second-stage channel cavity, so that the pressure loss of the separation structure is maintained within the design range.

[0046] Specifically, in this embodiment, the shell includes a first-stage sleeve 41, a second-stage sleeve 44 and a third-stage sleeve 45. A piston 42 is installed on the slide inside the first-stage sleeve 41. The piston 42 can slide between the front barrel mouth and the rear barrel cover 413 under the action of the pressure difference and the elastic unit. When the pressure is balanced, the piston 42 moves forward to the channel entrance 400 formed by the barrel mouth under the elastic force of the elastic unit and blocks the channel entrance 400. When the pressure difference between the front and rear ends of the piston 42 is greater than the elastic force of the elastic unit, the piston 42 moves backward, thereby expanding the first-stage channel cavity 401 in the first-stage sleeve 41 between the channel entrance 400 and the front end face of the piston 42.

[0047] In order to prevent the movement of the piston 42 from being blocked due to the sealing of the gas in the cylinder behind the piston, an exhaust hole 412 is further opened on the wall of the first-stage sleeve 41 to connect the air in the cylinder behind the piston with the outside of the cylinder.

[0048] The front portion of the second-stage sleeve 44 is sleeved outside the first-stage sleeve 41, and a gap is left between the inner wall of the front portion of the second-stage sleeve 44 and the outer wall of the first-stage sleeve 41 to form an annular second-stage channel cavity 402. A plurality of air vents 411 are provided through the wall of the first-stage sleeve 41 to connect the first-stage channel cavity 401 and the second-stage channel cavity 402. Preferably, in order to enhance the controllability and accuracy of the adjustment, the air vents 411 are arranged in a pattern of uniformly arranging the plurality of air vents 411 along the circumferential and axial directions of the wall of the first-stage sleeve 41. As the pressure difference between the front and rear ends of the piston 42 increases or decreases, the piston 411 moves backward or forward in the first-stage sleeve 41, and the number of exposed air vents 411 on the peripheral side of the first-stage channel cavity 401 increases or decreases accordingly, thereby realizing variable adjustment of increasing or decreasing the flow cross-section between the first-stage channel cavity 401 and the second-stage channel cavity 402.

[0049] The structure with adjustable flow cross-section is only provided between the first-stage channel cavity 401 and the second-stage channel cavity 402 in the shell, while the flow cross-sections between other adjacent channel cavities and the overall channel inlet 400 and channel outlet 405 are fixed.

[0050] In addition, an annular first-stage filter element 43 is fixed to the outside of the second-stage channel cavity 402. Specifically, a filter element receiving groove is formed on the inner wall of the second-stage sleeve 44 and is connected to the second-stage channel cavity 402. The first-stage filter element 43 is installed in the filter element receiving groove. A channel gap is fixedly maintained between the inner side surface of the first-stage filter element 43 and the outer wall of the first-stage sleeve 41. All air vents 411 on the wall of the first-stage sleeve 41 are directly opposite the inner side surface of the first-stage filter element 43. In other words, after passing through the channel gap between the inner side surface of the first-stage filter element 43 and the outer wall of the first-stage sleeve 41, the mixed gas exiting each air vent 411 can basically be adsorbed and separated by the first-stage filter element 43, and then flows into the third-stage channel cavity 403 through the channel gap.

[0051] In this embodiment, combined with Figure 4 As shown, a plurality of support ribs 414 are formed on the outer wall of the first-stage sleeve 41, which are arranged circumferentially at intervals and each extends axially (front-to-back). The first-stage filter element 43 is supported by the support ribs 414 to maintain a fixed channel gap between the first-stage filter element 43 and the outer wall of the first-stage sleeve 41.

[0052] An oil outlet hole 406 is formed at the bottom of the wall of the second-stage sleeve 44 and near the channel inlet 400. The oil droplets adsorbed and collected by the first-stage filter element 43 can automatically flow out from here by relying on gravity; the oil outlet hole 406 is provided here for the purpose of facilitating the outflow of oil droplets by relying on gravity, and secondly, the filter element near the channel inlet 400 adsorbs the most oil droplets.

[0053] The rear portion of the second stage sleeve 44 is located behind the first stage sleeve 41. In this embodiment, the elastic unit that provides the return elastic force for the piston 42 in the first stage sleeve 41 is partially accommodated in the inner space of the rear portion of the second stage sleeve 44. Figure 2 As shown, the piston rod 421 of the piston 42 passes backward through the through hole of the cylinder cover 413 behind the first-stage sleeve 41, and the second-stage sleeve 44 extends forward from the center of the rear cylinder cover to form a support column 442. The support column is formed with a receiving groove for accommodating the piston rod 421. The spring 422 is sleeved on the piston rod 421 and its two ends respectively press against the piston and the bottom of the receiving groove.

[0054] To facilitate loading and unloading, the cylinder cover 413 of the first-stage sleeve 41 is detachable, so that the piston 42 can be installed into the cylinder from here, and then the cylinder cover 413 can cover the cylinder mouth; to prevent the cylinder cover 413 from detaching and to limit the backward movement of the piston by the cylinder cover 413, the front end face of the support column 442 presses against the cylinder cover 413 of the first-stage sleeve 41 to prevent it from moving backward and falling out.

[0055] The inner space at the rear of the second-stage sleeve 44 constitutes a third-stage passage cavity 403 , and the front side of the third-stage passage cavity 403 is connected to the second-stage passage cavity 402 .

[0056] The third-stage sleeve 45 is fixedly mounted on the rear outside of the second-stage sleeve 44. In this embodiment, an annular sleeve 450 is formed in the middle of the inner wall of the third-stage sleeve 45 cover, and the rear end of the second-stage sleeve 44 is embedded in the annular sleeve 450, thereby fixing the third-stage sleeve 45 to the rear outside of the second-stage sleeve 44. In addition, an annular fourth-stage channel cavity 404 is formed and maintained fixed between the inner wall of the third-stage sleeve 45 and the outer wall of the rear part of the second-stage sleeve 44. A plurality of air vents 441 for connecting the third-stage channel cavity 404 and the fourth-stage channel cavity 404 are provided on the rear wall of the second-stage sleeve 44, and a second-stage filter element 46 is also provided in the fourth-stage channel cavity 404. The mixed gas enters the fourth-stage channel cavity 404 through the air vents 441 and is further refined by the second-stage filter element 46 for oil and gas separation.

[0057] Preferably, a plurality of supporting ribs (not shown in the figure) are formed on the outer wall of the second-stage sleeve 44, which are arranged circumferentially at intervals and each extend in the axial direction (forward and backward direction). The second-stage filter element 46 is supported by the supporting ribs to maintain a fixed channel gap between the second-stage filter element 46 and the outer wall of the second-stage sleeve 44.

[0058] At the axial front end of the fourth-stage channel cavity 404, a channel outlet 405 is formed between the inner wall of the third-stage sleeve 45 at the tube mouth and the outer wall of the second-stage sleeve 44. Preferably, the channel outlet 405 is in a shape that is gradually tilted outward from back to front, so that the gas coming out of the channel outlet 405 is tilted and ejected from the shell from back to front. This can not only reduce the overall diameter of the shell, but also utilize the divergent tilted ejection method to make full use of the gas entering the fine separation area to collide with each corner of the fine separation area. At the same time, it is also convenient for the oil droplets adsorbed and collected by the second-stage filter element 46 to automatically drip down from the lowest point of the outward-tilted channel outlet 405 by gravity.

[0059] Therefore, the gas path of the overall channel of the present invention is from the channel inlet 400 axially forward into the first-stage channel cavity 401, and then radially outward through the vent 411 into the second-stage channel cavity 402, while receiving adsorption and separation of the first-stage filter element 43 in the second-stage channel cavity 402, axially forward into the third-stage channel cavity 403, and then radially outward into the fourth-stage channel cavity 404 through the vent 441, while receiving adsorption and separation of the second-stage filter element 46 in the fourth-stage channel cavity 404, while axially backward to the channel outlet 405, and finally ejected outward from the channel outlet 405 from back to front; two dripping return oil positions are correspondingly set, one is located directly below the first-stage filter element 43 and close to the channel inlet 400, and the other is located near the channel outlet 405 of the second-stage filter element.

[0060] The front end of the whole shell can be fixed on the partition 47, or the front end of the first-stage sleeve 41 and the partition 47 can be made into one piece; the rear end of the whole shell can be fixed to the inner wall of the fine separation zone. In this embodiment, Figure 2 、 Figure 3 and Figure 4 As shown, a connecting plate 451 is integrally fixed to the cylinder cover at the rear end of the third-stage sleeve 45, a connecting piece 452 is fixed on the connecting plate 451, and a mounting sleeve matching the connecting piece 452 is formed on the inner wall of the fine separation area. The connecting piece 452 is inserted into the mounting sleeve to achieve quick and convenient installation and fixation.

[0061] See also Figure 4 and Figure 2 As shown, in order to prevent the error of the oil outlet hole 406 not being at the lowest point during installation, the first-stage sleeve 41 is provided with an anti-error protrusion 415, and the second-stage sleeve 44 is formed with a matching anti-error groove 444. Preferably, the anti-error groove 444 is connected to the oil outlet hole 406, which is more convenient for processing.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A variable flow section oil-gas separator, characterized in that: The invention comprises a shell, wherein a channel formed in the shell is composed of a channel inlet, a first-stage, a second-stage, a third-stage, a fourth-stage channel cavity and a channel outlet which are connected in sequence, wherein the first-stage channel cavity is coaxially connected to the channel inlet, the second-stage channel cavity surrounds the periphery of the first-stage channel cavity and the two are connected by a plurality of vents, the size of the first-stage channel cavity and the number of vents are controlled by the axial movement of the piston, and when there is no pressure difference between the front and rear of the piston, the piston can move forward to block the channel inlet under the action of the resetting elastic force of the elastic unit; the fourth-stage channel cavity surrounds the periphery of the third-stage channel cavity and the two are connected by a plurality of vents, and the second-stage channel cavity is provided with a first-stage filter element The fourth-stage channel cavity is provided with a second-stage filter element; the gas can enter the first-stage channel cavity axially forward from the channel inlet, and then enter the second-stage channel cavity radially outward through the vent hole, while receiving adsorption and separation of the first-stage filter element in the second-stage channel cavity, while entering the third-stage channel cavity axially forward, and then enter the fourth-stage channel cavity radially outward through the vent hole, while receiving adsorption and separation of the second-stage filter element in the fourth-stage channel cavity, while axially backward to the channel outlet, and finally ejected outward from the channel outlet from back to front; two dripping return oil positions are set accordingly, one is the oil outlet hole located directly below the first-stage filter element, and the other is directly served by the channel outlet adjacent to the second-stage filter element.

2. The variable flow cross-section oil-gas separator according to claim 1, characterized in that: The housing comprises first-stage, second-stage and third-stage sleeves, the piston is installed in the first-stage sleeve, the piston can block the channel entrance, and when the piston moves backward, the first-stage channel cavity between the channel entrance and the front end surface of the piston in the first-stage sleeve can be expanded; The front part of the second-stage sleeve is sleeved outside the first-stage sleeve, and a gap is left between the inner wall of the front sleeve and the outer wall of the first-stage sleeve to form an annular second-stage channel cavity. A plurality of vent holes that can connect the first-stage channel cavity and the second-stage channel cavity are opened through the wall of the first-stage sleeve; as the piston moves backward or forward in the first-stage sleeve, the number of exposed vent holes on the peripheral side of the first-stage channel cavity increases or decreases accordingly, thereby realizing variable adjustment of increasing or decreasing the flow cross section between the first-stage channel cavity and the second-stage channel cavity; The first-stage filter element is disposed in the second-stage channel cavity; The rear part of the second stage sleeve is located behind the first stage sleeve, and the third stage passage cavity is located in the inner space of the sleeve at the rear part of the second stage sleeve; The third-stage sleeve is fixedly mounted on the rear of the second-stage sleeve, and a fourth-stage channel cavity is formed and maintained fixedly between the inner wall of the third-stage sleeve and the outer wall of the rear of the second-stage sleeve. A plurality of vents for connecting the third-stage channel cavity and the fourth-stage channel cavity are provided on the rear wall of the second-stage sleeve, and the second-stage filter element is arranged in the fourth-stage channel cavity. A channel outlet is formed at the axial front end of the fourth-stage channel cavity between the inner wall of the third-stage sleeve at the barrel mouth and the outer wall of the second-stage sleeve.

3. The variable flow cross-section oil-gas separator according to claim 2, characterized in that: The multiple vent holes on the first-stage sleeve are arranged evenly along the circumferential and axial directions of the sleeve wall.

4. The variable flow cross-section oil-gas separator according to claim 2, characterized in that: A plurality of support ribs are formed on the outer wall of the first-stage sleeve, which are arranged at intervals in the circumferential direction and extend axially. The first-stage filter element is supported by the support ribs to maintain a fixed channel gap between the first-stage filter element and the outer wall of the first-stage sleeve.

5. The variable flow cross-section oil-gas separator according to claim 2, characterized in that: The oil outlet hole is arranged at the bottom of the second-stage sleeve wall and is adjacent to the channel entrance.

6. A variable flow cross-section oil-gas separator as claimed in claim 1 or 2, characterized in that: The channel outlet is in a shape that gradually tilts outward from back to front, so that the gas from the channel outlet tilts and sprays out of the shell from back to front, and the oil droplets adsorbed and collected by the second-stage filter element automatically drip from the lowest point of the channel outlet by gravity.

7. The variable flow cross-section oil-gas separator according to claim 2, characterized in that: An annular sleeve is formed in the middle of the inner wall of the third-stage sleeve cover, and the rear end of the second-stage sleeve is embedded in the annular sleeve, so that the third-stage sleeve is fixed outside the rear part of the second-stage sleeve.

8. The variable flow cross-section oil-gas separator according to claim 2, characterized in that: The elastic unit that provides the reset elastic force for the piston in the first-stage sleeve is partially accommodated in the inner space of the sleeve at the rear of the second-stage sleeve. The piston rod passes backward through the through hole of the sleeve cover at the rear of the first-stage sleeve. The second-stage sleeve extends forward from the center of the rear sleeve cover to form a support column. The support column is formed with a receiving groove for accommodating the piston rod. The spring is sleeved on the piston rod and the two ends respectively press against the piston and the bottom of the receiving groove.

9. The variable flow cross-section oil-gas separator according to claim 8, characterized in that: The cylinder cover of the first-stage sleeve is detachable, and the front end surface of the support column abuts against the cylinder cover of the first-stage sleeve to prevent the cylinder cover from moving backward and falling out.

10. The variable flow cross-section oil-gas separator according to claim 2, characterized in that: A plurality of support ribs are formed on the outer wall of the second-stage sleeve, which are arranged circumferentially and extend axially. The second-stage filter element is supported by the support ribs to maintain a fixed channel gap between the second-stage filter element and the outer wall of the second-stage sleeve.

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