Improved gas deoiling element for rotary vane vacuum pumps.

Abstract

The present invention relates to a gas deoiling element (1), particularly an air deoiling element, and to an oil separation and recirculation device (3) including the gas deoiling element for separating oil droplets from gas, preferably air. The oil separation and recirculation device (3) is provided with a cross-sectional restriction, for example in the form of an orifice plate (2), in the area where the gas / oil mixture enters the gas deoiling element. The present invention also relates to an oil-lubricated rotary vane vacuum pump (4) equipped with the gas deoiling element (1) of the present invention, thereby extending the service life of its plain bearings. The present invention also relates to a method for operating the oil-lubricated rotary vane vacuum pump (4), a method for replacing the gas deoiling element (1) provided in the oil-lubricated rotary vane vacuum pump (4), the use of a cross-sectional restriction, particularly an orifice plate, in the gas deoiling element of the present invention to extend the service life of the plain bearing in the oil-lubricated rotary vane vacuum pump, and the use of the gas deoiling element of the present invention in an oil-lubricated rotary vane vacuum pump to extend the service life of the plain bearing.

Description

[Technical Field]

[0001] The present invention relates to a gas deoiling element, particularly an air deoiling element, or to an oil separation and recirculation device for separating oil droplets from a gas (preferably air, etc.) that includes the above deoiling element and is improved compared to devices of the prior art. [Background technology]

[0002] This type of separation device is used, for example, in vacuum pumps, in particular oil-lubricated rotary vane pumps. The invention therefore also relates to an oil-lubricated rotary vane vacuum pump, comprising a pump stage including a rotary vane chamber and a rotary vane rotor, and an oil separation and recirculation device, in which separation of oil and gas, preferably oil and air, takes place.

[0003] Oil-lubricated rotary vane vacuum pumps are known. They typically have a pump stage comprising a housing with a cylindrical rotor eccentrically disposed within a cylindrical rotary vane chamber. The cylinder, together with a cylindrical cover, forms the rotary vane chamber housing, through which the working medium flows, is compressed, and then discharged. The axis of the eccentric rotor is offset parallel to the axis of the cylindrical rotary vane chamber. The rotor includes one or more vanes. These vanes are slidably disposed within slots formed in the rotor with a generally radial cross section. Centrifugal force generated by the rotor rotation presses the vanes against the inner walls defining the rotary vane chamber. During operation, the rotor rotates radially offset from the central axis of the cylindrical rotary vane chamber, thereby forming a closed transfer chamber defined by the radially displaceable vanes. The volume of the transfer chamber changes during one rotation of the rotor. As the volume of the transport chambers changes during operation of the vacuum pump, pressure differences arise between the individual transport chambers and thus between the intake and exhaust sides of the blower thus formed.

[0004] An example rotary vane vacuum pump has three vanes in three slots, creating three transfer chambers. Rotary vane vacuum pumps with more or fewer vanes, slots, and transfer chambers are also contemplated. For example, a rotary vane vacuum pump with two vanes, two slots, and two transfer chambers is also contemplated.

[0005] In oil-lubricated rotary vane vacuum pumps, oil is introduced into the pumping stages or rotary vane chambers. This oil seals the gaps between the components, especially between the vanes and the walls of the rotary vane chamber. This prevents gas exchange between the chambers. In this way, a higher vacuum can be achieved during operation than with dry-running rotary vane vacuum pumps. A rotary vane vacuum pump with two pumping stages can achieve a higher vacuum than a rotary vane vacuum pump with only one pumping stage. Oil is also used to lubricate the rotor, which is rotatably mounted in a plain bearing.

[0006] Due to the design, the oil is transported from the last transport chamber to the outlet together with the transported gas. Furthermore, the oil is heated by the compression enthalpy in the system. Furthermore, the oil may become contaminated or undergo chemical reactions and change its properties when in contact with the discharged medium. For this reason, the oil must be subjected to suitable treatment after leaving the pump stage. In this respect, it is known to circulate the oil within the device.

[0007] Furthermore, it is known that the oil processing process can be carried out in several sub-steps. For example, the oil and gas separation can be carried out first. This can be done in several stages, for example by coarse separation of large oil droplets, and further by gravity and / or impact separation. Further sub-steps include filtering the oil in a gas de-oiling element equipped with a filter element.

[0008] It is further known to house an oil separation device, preferably in combination with a reprocessing device, within an oil separation and recirculation housing, which is separate from but connectable to the rotary vane housing.

[0009] The gas deoiling element provided herein is replaceably housed within an oil separation and recirculation housing disposed adjacent to the rotary vane housing, and the gas deoiling element is substantially inserted into the oil separation and recirculation housing by one or more retaining walls.

[0010] If an oil-lubricated rotary vane vacuum pump is not used for a long period of time, the oil level will be low when the pump is started, and the sliding bearings will not be sufficiently lubricated when the pump is started. This will damage the sliding bearing surfaces and shorten their service life.

[0011] SUMMARY OF THE INVENTION It is therefore an object of the present invention to extend the service life of the plain bearings in oil-lubricated rotary vane vacuum pumps.

[0012] This problem has not been disclosed or solved in the prior art. An oil-lubricated rotary vane vacuum pump is known, for example, from US Pat. No. 5,649,999. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Publication No. 2022 / 078591 Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention aims to further improve prior art rotary vane vacuum pumps so as to extend the service life of the plain bearings. [Means for solving the problem]

[0015] In this solution, the cross section of the gas deoiling element is constricted on the inlet side of the gas / oil mixture. In conventional gas deoiling elements, this cross section is usually selected to minimize the pressure loss on the inlet side. In contrast, in the present invention, the cross section of the gas deoiling element is reduced on the inlet side of the gas / oil mixture. The diameter of this constricted section is preferably 40% to 75%, particularly preferably 45% to 70%, and most preferably 50% of the diameter of a conventional gas deoiling element without a cross-sectional constriction. The cross-sectional constriction can be adjusted appropriately depending on the pump and the degree of vacuum to be generated.

[0016] According to the invention, this cross-sectional restriction is preferably achieved by inserting an orifice plate into the gas de-oiling element on the inlet side of the gas / oil mixture. The orifice plate can be constructed as a separate part and is preferably attached to the gas de-oiling element by form-fitting. Furthermore, a connection by force or material connection is also conceivable. The key is the pressure buildup in the oil separation and recirculation device. Alternatively, the inlet section of the gas de-oiling element can be selected so that it itself has a cross-sectional restriction.

[0017] If an orifice plate is used on the inlet side of the gas / oil mixture, it can be easily attached, for example by clipping.

[0018] In a preferred embodiment, the gas deoiling element and the orifice plate are preferably integrally formed.

[0019] The gas de-oiling element of the present invention can also be easily replaced. To this end, in one embodiment of the present invention, the gas de-oiling element is removed from the discharge side of the gas / oil mixture. In a preferred embodiment, the gas de-oiling element is inserted and retained by one or more retaining walls within the oil separation and recirculation device, allowing for easy removal. Therefore, to access and replace the gas de-oiling element, it is only necessary to remove the exhaust gas cover.

[0020] The cross-sectional restriction, achieved by an orifice plate, for example, reduces the pressure chamber size, allowing back pressure to build up more quickly. This overpressure in the oil separator quickly creates a high pressure gradient compared to the pressure in the rotary vane chamber, causing the oil to flow quickly to the plain bearing. In this way, the plain bearing is lubricated more quickly by the oil, minimizing the risk of bearing damage. This is particularly advantageous in oil-lubricated rotary vane vacuum pumps used to generate vacuums with final pressures of up to 50 mbar, and particularly preferably up to 15 mbar.

[0021] The subject of the invention therefore also relates to the use of cross-sectional constrictions in a gas deoiling element according to the invention in order to increase the service life of slide bearings in oil-lubricated rotary vane vacuum pumps.

[0022] The subject of the present invention further relates to the use of an orifice plate in a gas deoiling element according to the invention to extend the service life of a plain bearing in an oil-lubricated rotary vane vacuum pump.

[0023] The subject of the invention likewise relates to the use of a gas deoiling element according to the invention in an oil-lubricated rotary vane vacuum pump in order to extend the service life of the plain bearings.

[0024] In the gas deoiling element, oil is filtered. An oil-laden gas stream flows into the inlet of the housing in which the gas deoiling element is mounted, circulates to the outlet, and is discharged from the outlet without oil mist. The gas deoiling element is usually a cylindrical cartridge type, and is generally provided with an inlet section and a closing lid. Thus, the air stream passes through a cylindrical filter wall before being sent to the exhaust gas cover. In a preferred embodiment, the inlet section, the cylindrical filter element, and the closing lid are inseparably connected, in particular glued together.

[0025] That is, the oil flow direction can be along the longitudinal direction of the oil separation and recirculation housing or gas deoiling element. This mainly means a flow along the longitudinal direction of the housing from one end region to the other, but the flow from one end of the housing to the other can deviate from a strictly linear flow direction. Here, the presence of a cross-sectional restriction causes a large change in flow velocity, which additionally provides pre-separation of the oil.

[0026] The subject of the present invention therefore also relates to an improved oil separation and recirculation device provided with a gas deoiling element according to the invention.

[0027] Further details of the invention will become apparent from the following description of preferred embodiments thereof, as illustrated in the accompanying drawings, from which further advantages of the invention will be understood, as well as suggestions and suggestions as to how the subject matter of the invention may be modified or further developed within the scope of the claims.

[0028] Additionally, throughout this specification, the claims, and the drawings, features of the invention are disclosed in specific embodiments and combinations, and those skilled in the art will be able to consider these features individually and combine them in different combinations and subcombinations to adapt the invention, as defined in the claims, to their needs and particular technical field. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a cross-sectional view of the pump including the oil supply and the arrangement of the plain bearings. [Figure 2A] FIG. 1 is a perspective view of an oil-lubricated rotary vane vacuum pump. [Figure 2B] FIG. 2B is a top view of the oil-lubricated rotary vane vacuum pump shown in FIG. 2A. [Figure 3] This is a partial cross-sectional view of an oil-lubricated rotary vane vacuum pump, showing the oil separation and recirculation device. [Figure 4]1 is a cross-sectional view of an oil separation and recirculation device according to the present invention. [Figure 5A] FIG. 1 is a cross-sectional view of a gas deoiling element with an orifice plate inserted. [Figure 5B] FIG. 1 is a perspective view of a gas deoiling element with an orifice plate inserted. DETAILED DESCRIPTION OF THE INVENTION

[0030] <Preferred embodiment of the present invention> The cross-sectional view of the pump stage, including the oil supply and bearing arrangement, shown in Figure 1 reveals the oil supply to the plain bearing 23 in an oil-lubricated rotary vane vacuum pump. Reference numeral 00 denotes the oil level at pump start-up, and reference numeral 01 denotes the oil level in the electric motor 12 during operation. This means that the plain bearing is not lubricated with oil when the pump is started. Therefore, to prevent the pump from "seizing," the plain bearing 23 must be quickly lubricated with oil, just as it is during operation. This rapid lubrication of the plain bearing 23 is achieved by narrowing the cross-section of the gas de-oiling element on the inlet side of the gas / oil mixture. This is because the greater the pressure difference between the pump stage 5 and the oil separation and recirculation device 3, the more quickly the oil supply to the plain bearing begins. This ensures that the plain bearing 23 is quickly and sufficiently lubricated, extending its service life.

[0031] The flow of oil within the pump stages during start-up and operation of the pump is shown by arrows in FIG.

[0032] FIG. 1 further shows a cylindrical rotary vane rotor 9 within the rotary vane chamber 8 and an electric motor 12 .

[0033] 2A is a perspective view of an oil-lubricated rotary vane vacuum pump 4 according to the present invention, showing the electric motor 12 and the oil separation and recirculation device 3. Also shown is the exhaust gas cover 7.

[0034] FIG. 2B is a top view of the oil-lubricated rotary vane vacuum pump 4 shown in FIG. 2A, showing the pump stage 5, the electric motor 12, and the oil separation and recirculation device 3 according to the present invention. As can be seen, an orifice plate 2 is inserted into the gas deoiling element 1 on the inlet side of the gas / oil mixture. The gas deoiling element 1 preferably comprises a filter element 29, a closing lid 27, and an inlet 28. These three components can be inseparably connected to one another. Specifically, the three components 27, 28, and 29 are glued together. The figure also shows an exhaust gas cover 7, through which the cleaned gas is discharged to the outside.

[0035] 3 is a partial cross-sectional view of an oil-lubricated rotary vane vacuum pump 4 according to the present invention, showing the oil separation and recirculation device 3 and its housing 14. The housing 14 comprises a ceiling wall 16, a floor wall 17, and side walls 15 and 26. The gas de-oiling element 1 can be replaced through an opening 6 created by removing the exhaust gas cover 7. In this example, the gas de-oiling element 1, which includes an orifice plate 2, an inlet portion 28, a filter element 29, and a closing lid portion 27, is substantially inserted into the oil separation and recirculation device 3, preferably by a plurality of retaining walls 19.

[0036] The oil is transported from the last pump stage 5 to the discharge port together with the exhaust gas. Furthermore, the oil heats up due to the compression enthalpy within the system. Furthermore, the oil may become contaminated or undergo chemical reactions that change its properties due to contact with the exhaust medium. Therefore, after the oil leaves the vacuum zone, it must undergo a suitable treatment. In this regard, it is known to circulate the oil within the system. This is shown in Figure 3. The gas / oil mixture periodically passes through a gas de-oiling element 1, which has a cross-sectional restriction in its inlet region. The cross-sectional restriction is preferably formed by an orifice plate 2. In the figure, the white arrows indicate the gas flow during pumping, and the black arrows indicate the oil flow during pumping.

[0037] The oil separation and recirculation device may comprise a chamber, preferably integrally formed with the oil separation and recirculation device. With reference to the installation shown in the drawings, a lower chamber 20 and an upper chamber 21 are formed in relation to the direction of gravity. The chambers 20 and 21 are separated by a partition floor 22 which extends transversely to the side walls 15 and 26 in the cross-sectional view of FIG. 3.

[0038] The upper chamber 21 primarily serves to house the gas deoiling element 1. The upper chamber 21 can, and preferably does, extend in approximately the same direction as the rotor axis. The longitudinal ends of the upper chamber 21 can be defined by retaining walls 19.

[0039] During operation of the rotary vane vacuum pump 4, the oil / gas mixture flows from the pump stage 5 into the oil separation and recirculation device 3 through a passage opening 24 provided in the area of ​​the outer wall 18 (see FIG. 4). This passage opening 24 therefore serves as the inlet to the oil separation and recirculation device.

[0040] First, a gravity separator and / or an impact separator can be used to roughly separate large oil droplets. Within the housing 14 of the oil separation and recirculation device, a housing section 25 formed below the passage opening 24 can function as an oil pan (oil sump) for collecting oil. Therefore, a possible oil level 30 is also shown in FIG. 3. This allows the lower chamber 20 to form an oil reservoir.

[0041] Furthermore, the lower chamber 20 defines a flow path along the length of the housing 14. This flow is directed primarily towards the sidewall 26, where it changes direction and flows into the upper chamber 21.

[0042] The gas deoiling element 1 housed in the upper chamber 21 typically comprises a filter element 29. For example, the filter element 29 is provided in particular in the form of a fine separator.

[0043] The oil / gas mixture guided from the lower chamber 20 to the upper chamber 21 passes through the gas de-oiling element 1 in a predetermined direction, during which a pressure difference may occur between the upstream and downstream sides of the gas de-oiling element 1. This pressure difference depends on the discharge pressure of the pump stage 5 and, depending on the type of pump, may reach a maximum of 800 mbar when the pump is started.

[0044] As shown by the arrows in the figure, a flow occurs in the gas deoiling element 1 in the direction of the central axis. As a result, the cleaned gas passes through the exhaust gas cover 7 and is discharged from the housing 14 of the oil separation and recirculation device. The oil droplets separated in this way in the gas deoiling element 1 are returned to the oil sump.

[0045] 4 is a cross-sectional view of an oil separation and recirculation apparatus according to the present invention. In particular, the orifice plate 2 of the gas deoiling element and the insertion retaining mechanism using the retaining wall 19 are shown. Also shown are the components that make up the housing 14 of the oil separation and recirculation apparatus, namely, the side wall 15, the ceiling wall 16, the floor wall 17, and the outer wall 18. Also shown are the lower chamber 20, the passage opening 24, the housing portion 25, the upper chamber 21, the partition floor 22, and the oil level 30.

[0046] FIG. 5A is a cross-sectional view of a gas de-oiling element 1 according to the present invention, showing the inserted orifice plate 2, inlet section 28, and filter element 29. The orifice plate 2 is preferably arranged on the inlet side, where the gas / oil mixture enters the oil separation and recirculation device. The orifice plate 2 can be constructed as a separate part, as shown. In this case, it is preferably attached to the gas de-oiling element 1 by a form fit. Furthermore, a connection by a force or material bond is also conceivable. The key is the pressure buildup in the oil separation and recirculation device. Alternatively, the inlet section 28 of the gas de-oiling element can be selected to have a cross-sectional restriction of its own.

[0047] 5B is a perspective view of the gas de-oiling element 1 according to the present invention, showing the inlet section 28, the filter element 29, and the inserted orifice plate 2. The orifice plate 2 is preferably located on the inlet side where the gas / oil mixture enters the oil separation and recirculation device.

[0048] Finally, it should be reiterated that the embodiment examples described in this specification are merely examples of possible forms for implementing the ideas of the present invention and should not be construed as limiting the present invention. As will be understood by those skilled in the art, other embodiments of the present invention and the addition of additional elements are possible without departing from the essential characteristics of the present invention. [Explanation of symbols]

[0049] 00...Oil level when pump starts 01...Oil level in the electric motor during operation 1...Gas deoiling element 2...Orifice plate 3…Oil separation / recirculation device 4...Oil-lubricated rotary vane vacuum pump 5...Pump stage 6...Opening 7...Exhaust gas cover 8...Rotary vane chamber 9...Rotary vane rotor 12...Electric motor 13...Transportation room 14...Oil separator and recirculation unit housing 15…Side wall 16...Ceiling wall 17...Floor and wall 18...Exterior wall 19…Retaining wall 20...Lower chamber 21...Upper chamber 22...Partition floor 23...Slide bearing 24…Aisle opening 25...Housing section 26…Side wall 27...Closing lid part 28…Inlet part 29...Filter element 30...Oil level

Claims

1. A gas de-oiling element (1), characterized in that it is provided with a cross-sectional constriction in the region where the gas / oil mixture enters the gas de-oiling element (1).

2. 2. The gas de-oiling element (1) according to claim 1, characterized in that the cross-sectional restriction is realized by an orifice plate (2) arranged in the area where the gas / oil mixture enters the gas de-oiling element.

3. 3. The gas de-oiling element (1) according to claim 1 and / or 2, characterized in that the cross-sectional constriction reduces the diameter of the gas de-oiling element, preferably to 40% to 75% of its initial value, particularly preferably to 45% to 70% of its initial value, and very particularly preferably to 50% of its initial value.

4. 4. The gas deoiling element according to claim 1, wherein the gas deoiling element and the orifice plate are integrally formed.

5. 1. An oil separation and recirculation device (3) for separating oil droplets from gas, comprising a gas deoiling element (1), characterized in that the gas deoiling element is a gas deoiling element according to any one or more of claims 1 to 4.

6. a pump stage (5) comprising a rotary vane chamber (8) and a rotary vane rotor (9) in a plain bearing (23); an oil separation and recirculation device (3); An oil-lubricated rotary vane vacuum pump (4) comprising: In the oil separation and recirculation device (3), separation of gas and oil, in particular air and oil, is preferably carried out by a gas de-oiling element (1), An oil-lubricated rotary vane vacuum pump (4), characterized in that the gas deoiling element (1) is a gas deoiling element according to any one or more of claims 1 to 4.

7. 7. An oil-lubricated rotary vane vacuum pump (4) according to claim 6, characterized in that the oil-lubricated rotary vane vacuum pump is used to generate a vacuum in the range of a final pressure of up to 50 mbar, in particular up to 15 mbar.

8. A method for operating an oil-lubricated rotary vane vacuum pump (4) according to claims 6 and / or 7.

9. A method for replacing the gas deoiling element (1) according to any one or more of claims 1 to 4 in an oil-lubricated rotary vane vacuum pump (4).

10. Use of a cross-sectional constriction in a gas deoiling element (1) according to any one or more of claims 1 to 4 for increasing the service life of a plain bearing (23) in an oil-lubricated rotary vane vacuum pump (4).

11. Use of an orifice plate (2) in a gas deoiling element (1) according to any one or more of claims 2 to 4 for extending the service life of a plain bearing (23) in an oil-lubricated rotary vane vacuum pump (4).

12. Use of a gas deoiling element (1) according to any one or more of claims 1 to 4 in an oil-lubricated rotary vane vacuum pump (4) to extend the service life of a plain bearing (23).

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