Guide device, refrigerant duct, and diffusion vacuum pump

Abstract

A guide device for a diffusion vacuum pump includes a plurality of annular guide plates arranged radially, with at least one guide plate having a first section beginning at a connection point and a second section beginning at the connection point. The first section extends axially in a first direction, and the second section extends axially in an opposite second direction. The first section is designed to be inclined radially and / or the second section is designed to be inclined radially.

Description

[Technical Field]

[0001] The present invention relates to a guide device for a diffusion vacuum pump, a coolant duct for a vacuum pump, and a diffusion vacuum pump equipped with such a guide device and coolant duct. [Background technology]

[0002] Known diffusion vacuum pumps have a housing with an inlet and an outlet, with one or more nozzles arranged in the housing. Furthermore, a heating element is provided for vaporizing a propellant, specifically oil. The vaporized propellant exits the nozzle. This propellant transports gas molecules from the vacuum toward the outlet of the diffusion vacuum pump. The propellant condenses on the outer wall of the diffusion vacuum pump and returns to the storage space, which also contains the heating element. As a result, the propellant vaporizes, creating a propellant transport circuit, transporting the gas medium from the inlet of the diffusion vacuum pump to the outlet of the diffusion vacuum pump.

[0003] However, a drawback of this process is that oil molecules from the propellant can enter the receptacle connected to the inlet of the diffusion vacuum pump, contaminating the vacuum in the receptacle and potentially damaging the vacuum equipment.

[0004] It is known to provide a vapor barrier at the inlet or high-vacuum nozzle of a diffusion vacuum pump to prevent oil backflow into the receptacle. These vapor barriers provide an additional condensation surface on which the propellant condenses, preventing it from entering the receptacle. However, this has the disadvantage of significantly reducing the conductance of the diffusion vacuum pump and, therefore, the pumping speed. When such a vapor barrier has a small area, particularly smaller than the inlet cross-sectional area of ​​the diffusion vacuum pump, it is usually directly connected to the inlet nozzle. This complicates the construction in the nozzle area and makes cleaning the vapor barrier more difficult. When such a vapor barrier is provided across the entire inlet surface or cross-sectional area, it is known to provide it as a separate vacuum element with a separate housing. The housing thus has a first flange for connection to the diffusion vacuum pump and a second flange for connection to the receptacle. This makes the structure unnecessarily large. In particular, when replacing the vapor barrier, it is necessary to adapt the available installation space.

[0005] Also, known vapor barriers operate at temperatures between 0 and -196°C (liquid nitrogen). Being directly coupled to the nozzle, this leads to an unnecessary transfer of cooling energy to the nozzle itself. Furthermore, in known solutions, the supply of cooling water is ensured by the housing of the diffusion vacuum pump itself. This leads to a significant transfer of cold air from the cooling water to the housing of the diffusion vacuum pump. Moisture in the surrounding air condenses and freezes on the outside of the diffusion vacuum pump, thus depositing as an ice layer. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to create an integrated guide device for a diffusion vacuum pump that can be cooled in a simple manner and that prevents oil from flowing back into the receptacle. [Means for solving the problem]

[0007] This object is achieved by a guide device according to claim 1, a cooling device according to claim 11 and a diffusion vacuum pump according to claim 13.

[0008] The guide device for a diffusion vacuum pump according to the present invention comprises a plurality of annular guide plates, which are arranged radially relative to one another. At least one guide plate has a first section starting from a connection point and a second section starting from the connection point. The first section extends axially in a first direction, and the second section extends axially in an opposite or second direction. In the installed state, the first direction points toward the receptacle or inlet of the guide device, and the second direction points toward the diffusion vacuum pump. The first section is designed to taper radially. Alternatively or additionally, the second section is designed to taper radially. Thus, starting from the common connection point, the radius changes along the axial direction, and the first and second sections form a condensation surface of one guide plate that is angled relative to the condensation surface of the other guide plate. The enlarged angled condensation surface formed by the first and second sections effectively prevents backflow of vaporized propellant oil molecules.

[0009] Preferably, all guide plates are designed identically, and thus each guide plate preferably has a first section and a second section designed to be radially inclined along the first and second axial directions. This effectively prevents the backflow of oil molecules. At the same time, the individual guide plates can be spaced far apart from each other, simplifying the structure of the guide device and making it easier to clean. At the same time, the conductance of the guide device is increased without reducing its barrier function.

[0010] The axial end point of the first section of one of the plurality or all of the guide plates is preferably located radially above or further radially inward than the connection point of the immediately adjacent guide plate, particularly the radially inner immediately adjacent guide plate. The axial end point of the first section is the axial end point of the guide plate in the first direction opposite the connection point of the target guide plate. Thus, the first section extends from the connection point to its axial end point. Alternatively or additionally, the axial end point of the second section of one of the plurality or all of the guide plates is located radially above or further radially inward than the axial end point of the guide plate in the second direction opposite the connection point of the target guide plate. Thus, the second section extends from the connection point to its axial end point. This configuration therefore forms an optically clear guide device. This means that there is no direct line of sight into the guide device, and there is no direct path for oil molecules to pass through the guide device. Therefore, oil molecules can only pass through the guide device by coming into contact with one of the condensation surfaces formed by the guide plates. However, since the oil molecules condense here, they do not enter the receptacle. In this way, backflow of oil molecules can be completely or at least almost completely prevented.

[0011] Preferably, 3 to 5 guide plates are provided, this number covering the entire inlet or inlet cross section of the diffusion vacuum pump.

[0012] At least one, some or all of the guide plates are preferably connected to cooling elements, in particular designed as refrigerant lines, for cooling the guide plates, which allow the temperature of the guide plates to be reduced to -196°C, thereby achieving efficient condensation of the propellant vapor on the guide plates.

[0013] Preferably, a first section of the at least one cooled guide plate is formed by a first guide plate element, and a second section of the at least one cooled guide plate is formed by a second guide plate element. The first and second guide plate elements are connected to each other by a cooling element. Therefore, only a connection, specifically a refrigerant line, exists between the first guide plate element and the cooling element. Similarly, only a connection exists between the second guide plate and the cooling element. Specifically, no direct connection exists between the first and second guide plate elements. This results in a particularly simple structure that is easy and inexpensive to manufacture.

[0014] Preferably, the first and / or second guide plate elements of at least one cooled guide plate have a substantially, preferably exclusively, radially extending section for coupling to the cooling element. This results in a large-area coupling of the first or second guide plate element to the cooling element. Furthermore, the structure is simplified to allow for easy and inexpensive production.

[0015] Preferably, at least one, more than one, preferably all, first and / or second guide plate elements of the guide plate comprise at their respective axial ends substantially, preferably exclusively, axially extending sections, which increase the stability of the respective first and / or second guide plate elements.

[0016] The axial length of the second section preferably decreases from the outer guide plate to the inner guide plate. Thus, the radially outermost guide plate has a second section that extends axially further in the direction of the nozzle than the radially innermost guide plate. This ensures that the radially innermost guide plate does not interfere with, and thus adversely affect, the propellant jet exiting the nozzle of the diffusion vacuum pump. At the same time, the outermost guide plate ensures that sufficient condensation surface is available to prevent oil backflow.

[0017] The guide device preferably has exactly one flange for connection to the diffusion vacuum pump. In particular, the guide device does not have a housing, but can be positioned in the housing of the diffusion vacuum pump by means of one flange. In this way, a particularly space-saving design is achieved.

[0018] The guide plate is preferably connected to the flange by webs, in particular extending radially, which ensures sufficient stability of the guide device, while at the same time keeping the installation space of the guide device small.

[0019] Preferably, the web has a thermal decoupling element, in particular made of plastic material, which ensures that the low temperature of the guide device is not transmitted to the flange and consequently to the vacuum pump, so that the guide device can be operated at temperatures as low as -196°C.

[0020] Furthermore, the present invention relates to a refrigerant duct for a vacuum pump, particularly a diffusion vacuum pump, as an independent invention. The refrigerant duct has a flange, which has a recess opening to the interior, and a refrigerant line disposed in the recess. The recess has a first diameter, and the refrigerant line has a second diameter, which is smaller than the first diameter, so that the refrigerant line is guided without contact within the recess. Because the interior of the flange is under vacuum, the refrigerant line is guided without contact within the flange, ensuring that cold is not transferred from the refrigerant in the refrigerant line to the flange. Therefore, the refrigerant duct of the present invention ensures that the low temperature of the refrigerant in the refrigerant line is not transferred to the outside of the vacuum pump through the flange, reducing or preventing ice formation outside the vacuum pump.

[0021] Preferably, the refrigerant lines are bonded to the flange on the outside of the flange. For example, the flange and the refrigerant lines can be welded to create a vacuum tight seal. Bonding on the outside of the flange creates only a small cold bridge through which cold is transferred from the cooling line to the flange. In particular, when the bond is made by welding, the bond does not extend into the recess of the flange, or extends only to a minimal extent, thereby keeping the cold bridge small.

[0022] Preferably, a sealing element, particularly made of a plastic material, is at least partially arranged between the refrigerant line and the flange, whereby thermal insulation between the refrigerant line and the flange can be achieved, since the plastic material has a significantly lower thermal conductivity than stainless steel or other metals, and at the same time, the sealing element ensures the vacuum tightness of the refrigerant duct.

[0023] The present invention also relates to a diffusion pump having at least one nozzle, through which a propellant is transferred to carry a gaseous medium from the inlet to the outlet of the diffusion vacuum pump. The diffusion vacuum pump has a guide device disposed directly above the inlet nozzle, i.e., toward the receptacle, as described above. For example, if the diffusion pump has only one nozzle, the guide device is disposed directly above this nozzle. However, if the diffusion vacuum pump has multiple nozzles, the guide device is disposed directly above the nozzle located in the high vacuum region, i.e., the nozzle located furthest toward the inlet or receptacle of the diffusion vacuum pump.

[0024] Preferably, the diffusion vacuum pump comprises a coolant duct, as described above, which is arranged on a flange of the guide device.

[0025] Preferably, there is no contact between the inlet nozzle and the guide device, preventing the transfer of cold air from the guide device to the inlet nozzle. In this way, the guide device is arranged in a thermally insulated manner within the vacuum pump, which ensures efficient cooling of the guide device and at the same time prevents the transfer of cold air from the guide device to other parts of the diffusion vacuum pump.

[0026] Preferably, the diffusion pump has a connecting flange, and the flange of the guide device is connected to the connecting flange of the diffusion vacuum pump. In particular, since the guide device does not have its own housing, the guide device having the flange is directly connected to the connecting flange of the vacuum pump and is consequently disposed within the housing of the diffusion pump.

[0027] Preferably, the guide device covers the entire cross-sectional area of ​​the inlet of the diffusion vacuum pump.

[0028] The invention is explained in more detail below on the basis of preferred embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a perspective view of a guide device according to the present invention; [Figure 2] 2 is a cross-sectional view of the guide device according to FIG. 1; [Figure 3] 2 is a top view of the guide device of FIG. 1. FIG. [Figure 4] 1 shows a diffusion vacuum pump according to the present invention. [Figure 5] 1 shows a refrigerant duct according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The guide device 10 according to the invention according to Fig. 1 has a flange 12 by means of which the guide device 10 can be connected to a diffusion vacuum pump 40. In this case, no components protrude beyond the upper side 14 of the flange 12. The components of the guide device 10 are therefore arranged below the upper side 14 of the flange 12 and consequently protrude into the housing 42 of the diffusion vacuum pump 40. In particular, the guide device 10 does not have its own housing. In this way, a particularly compact design is achieved. The diffusion vacuum pump 40 can therefore be connected to a receptacle or a vacuum device by means of the flange 12 of the guide device.

[0031] In the illustrated example, the guide device 10 has four guide plates 16 arranged radially from one another. The guide plates 16 are connected to the flanges 12 of the guide device 10 by radial webs 18. The radial webs 18 are indirectly connected to the flanges 12 via insulating elements 20 that merely provide thermal isolation between the flanges 12 and the guide plates 16. In this way, heat and cold are prevented from being transferred from the guide plates 16 to the flanges 12.

[0032] As can be seen from FIG. 3 , the guide plate 16 has a first section 22 extending from a common connection point 24 in a first direction 23, or toward a guide device inlet 26. The radius of the first section 22 decreases starting from the common connection point 24, such that the first section 22 has a smaller radius at its axial end 28 than at the common connection point 24. Similarly, the second section 30 extends in a direction opposite to the axial extension or first direction 23 of the first section 22, or in a second direction 31. The radius of the second section 30 also decreases starting from the common connection point 24, such that the second section 30 has a smaller radius at its axial end 32 than at the common connection point 24. The first section 22 and the second section 30 join together only at the common connection point 24. The first section 22 extends radially to be located above the common connection point 34 of the immediately adjacent guide plate 16. The second section 30 also extends such that an axial end 32 of the second section 30 is located radially below a common connection point 34 of the immediately adjacent guide plate 16. This forms an impermeable configuration for the guide device 10, so that oil molecules cannot pass directly through the guide device 10 but always collide with the condensation surface and, as a result, cannot enter the receptacle.

[0033] 3, at the axial ends 28, 32 of the first section 22 and / or the second section 30, the guide plate 16 comprises an axially extending section 33. The axially extending section 33 enhances the mechanical stability of the individual guide plates, thus avoiding damage to the guide plates 16 during assembly and disassembly.

[0034] As can be seen in Figure 3, the guide plate 16 located further inwards has a smaller axial extent in the second section, which ensures that the propellant vapor emerging from the nozzle 60 does not impinge on the guide plate 16 but can instead be guided unhindered in the transport direction.

[0035] Furthermore, the first section 22 is indirectly connected to the second section 30 via a cooling element 36, which is specifically a refrigerant line. To achieve effective condensation of oil molecules on the condensation surface of the guide plate 16, cooling energy is transferred to the guide plate 16 by the cooling element 36. The cooling element 36 is connected to a refrigerant duct 50. Here, the flange 12 has a recess or depression 52 opening into the interior. The recess 52 has a first diameter D1. Furthermore, the refrigerant line 36 has a second diameter D2, which is smaller than the first diameter D1, so that the refrigerant line 36 is at least partially guided within the flange 12 without contact. Furthermore, the refrigerant line 36 is connected to the outside of the flange 12, so that a vacuum-tight connection is formed between the refrigerant line 36 and the flange 12. For example, the refrigerant line 36 can be connected to the outside of the flange 12 by welding. In this case, the refrigerant line 36 is guided largely contactlessly through the recess 52 of the flange 12, and a cold bridge is formed only in the area of ​​the weld seam 54. However, since this cold bridge has a small cross-section, the transfer of cold from the refrigerant line 36 to the flange 12 is reduced. Alternatively or additionally, a sealing element (not shown) can be provided at least partially between the flange 12 and the refrigerant line 36, specifically in the recess or recess 52 of the flange 12. The sealing element, specifically made of a plastic material, has a lower thermal conductivity than the stainless steel or other metal from which the flange 12 is made. Therefore, the transfer of cold from the refrigerant line 36 to the flange 12 is reduced. This is because, due to the presence of a vacuum in the area of ​​the recess 52, no or only little heat transfer occurs in this area. Of course, the guide device 10 may have one or more refrigerant ducts. For example, according to FIG. 2, an inlet 60 and a return 62 for the refrigerant can be provided, both of which are formed as described above and shown in FIG.

[0036] 4 shows a diffusion vacuum pump according to the present invention. The diffusion vacuum pump has a housing 42 and an outlet 41. Furthermore, an inlet 43 of the diffusion vacuum pump 40 is provided, the inlet 43 being formed by a flange 44. The flange 12 of the guide device 10 is connected to the flange 44 of the diffusion vacuum pump 40, so that the guide device is completely disposed within the housing 42 of the diffusion vacuum pump 40. Furthermore, the inlet 26 of the guide device 10 forms the inlet of the diffusion vacuum pump 40.

[0037] The diffusion vacuum pump 40 has a storage space 45 for storing a propellant. A heating element is provided in the storage space 45, which vaporizes the propellant and causes it to flow again through a nozzle 46. In the process, gas molecules are carried away from the vacuum and transported in the direction of the outlet 41. The propellant condenses on the inner wall 47 of the housing 42 and consequently returns to the storage space 45.

[0038] The guide device 10 is positioned above the inlet nozzle 46, i.e., in the direction from the inlet nozzle 46 to the receptacle. There is no contact between the inlet nozzle 46 and the guide device 10, so no cold or heat is transferred from the guide device to the nozzle.

[0039] Thus, a guide device or vapor barrier is created that is integrated into the housing of the diffusion vacuum pump, yet is easy to install and remove and is completely impermeable. Furthermore, the coolant duct according to the invention allows the guide device to be cooled even at very low temperatures down to -196°C without adversely affecting the functionality of the diffusion pump.

Claims

1. 1. A guide device for a diffusion vacuum pump having a plurality of radially arranged annular guide plates, comprising: At least one of the guide plates has a first section beginning at a connection point and a second section beginning at the connection point; the first section extends axially in a first direction and the second section extends axially in an opposite second direction; the first section is designed to be radially tapered and / or the second section is designed to be radially tapered; at least one of the guide plates is coupled to a cooling element for cooling the guide plate; each of the first section and the second section of the at least one cooled guide plate is formed by a first guide plate element and a second guide plate element, and the first guide plate element and the second guide plate element are coupled to each other by the cooling element; A guide device, wherein the first guide plate element and / or the second guide plate element of at least one cooled guide plate has a radially extending portion for coupling to the cooling element.

2. 2. The guide apparatus of claim 1, wherein an axial end point of one of the guide plates is located radially inwardly of a connection point of an immediately adjacent guide plate.

3. The guide device according to claim 1 or 2, wherein the number of the guide plates is three to five.

4. 4. The guide device of claim 1, wherein the axial length of the second section decreases from the outer guide plate to the inner guide plate.

5. 5. The guide device according to claim 1, wherein the guide plate is connected to the flange by a radially extending web.

6. A guide device as described in any one of claims 1 to 5, further comprising a refrigerant duct for supplying refrigerant to the cooling element.

7. A diffusion pump having at least one nozzle, wherein the guide device according to any one of claims 1 to 6 is arranged directly above the inlet nozzle.

8. 8. The diffusion pump of claim 7, wherein there is no contact between the inlet nozzle and the guide device.

9. A diffusion pump as described in claim 5 or claim 6 which cites claim 5, or claim 7 or 8 which cites claim 5, wherein the diffusion pump further comprises a connecting flange, and the flange of the guide device is connected to the connecting flange.

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