Guide device, coolant duct and diffusion vacuum pump

Abstract

A kind of guide device for diffusion vacuum pump has multiple annular guide plates. The guide plates are arranged in a radial direction, wherein at least one guide plate has a first portion from a connection point and a second portion from the connection point. Wherein, the first portion extends axially in a first direction, and the second portion extends axially in a second opposite direction. Wherein, the first portion is designed to be tapered in a radial direction and / or the second portion is designed to be tapered in a radial direction.

Description

[0001] The invention relates to a guide device for a diffusion vacuum pump, a coolant duct for a vacuum pump and a diffusion vacuum pump having such a guide device and a coolant duct.

[0002] Known diffusion vacuum pumps have a housing with an inlet and an outlet, wherein one or more nozzles are arranged in the housing. Furthermore, a heating element is provided, through which a propellant, in particular oil, is vaporized. This vaporized propellant is discharged through the nozzles. The propellant transports gas molecules from the vacuum in the direction of the outlet of the diffusion vacuum pump. The propellant condenses on the outer wall of the diffusion vacuum pump, so that it returns to a storage space which is also provided with a heating element. The propellant is thus vaporized again, forming a transport circuit for the propellant, so that a gaseous medium is transported from the inlet to the outlet of the diffusion vacuum pump.

[0003] However, one disadvantage of this process is that oil molecules of the propellant can enter the container connected to the inlet of the diffusion vacuum pump. This contaminates the vacuum in the container and can damage the vacuum equipment.

[0004] In order to prevent the backflow of oil into the container, it is known to provide a vapor barrier on the inlet-side nozzle or the high-vacuum-side nozzle of the diffusion vacuum pump. These vapor barriers have an additional condensation surface on which the propellant condenses and thus cannot enter the container. However, this has the disadvantage that the conductance and the pumping speed of the diffusion vacuum pump are significantly reduced. If the area of such a vapor barrier is small, in particular smaller than the inlet cross-section of the diffusion vacuum pump, these vapor barriers are usually directly connected to the inlet-side nozzle. This makes the structure of the nozzle area complex and makes the cleaning of the vapor barrier more difficult. If such a vapor barrier is to be provided over the entire inlet surface or the entire inlet cross-section, it is known to provide such a vapor barrier 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 container. This makes the structure unnecessarily large. In particular, the available installation space has to be adjusted when replacing the vapor barrier.

[0005] The known vapor barriers also operate at temperatures between 0 and -196°C (liquid nitrogen). Due to the direct connection to the nozzle, this leads to an undesirable transfer of cooling energy to the nozzle itself. Furthermore, in the known solution, the supply of coolant is ensured by the housing of the diffusion vacuum pump itself. This leads to a large amount of cold energy being transferred from the coolant to the housing of the diffusion vacuum pump. Moisture from the surrounding air condenses and freezes on the outside of the diffusion vacuum pump, thus depositing as a layer of ice.

[0006] It is an object of the invention to create an integrated guide device for a diffusion vacuum pump which can be cooled in a simple manner and which prevents the backflow of oil into the container.

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

[0008] The guiding device for a diffusion vacuum pump according to the application has a plurality of annular guiding plates, which are arranged radially with respect to one another. In this case, at least one guiding plate has a first portion starting from a connection point and a second portion starting from the connection point. The first portion extends axially in a first direction and the second portion extends axially in an opposite direction or second direction. In the installed state, the first direction is directed in the direction of the inlet of the guiding device or of the container and the second direction is directed in the direction of the diffusion vacuum pump. The first portion is designed to taper radially. Alternatively or additionally, the second portion is designed to taper radially. Thus, starting from the common connection point, the radius changes in the axial direction and the condensation surface of one guiding plate is angled with respect to the condensation surface of another guiding plate, which is produced by the first portion and the second portion. The enlarged, angled condensation surface formed by the first portion and the second portion effectively prevents the backflow of oil molecules of the vaporized propellant.

[0009] All guiding plates are preferably designed in the same way, so that preferably each guiding plate has a first portion and a second portion, which are designed to taper radially in the first and second axial directions. This effectively prevents the backflow of oil molecules. At the same time, the individual guiding plates can be far apart from one another, simplifying the construction of the guiding device and making it easy to clean the guiding device. At the same time, the conductivity of the guiding device is increased without reducing the barrier function.

[0010] The axial end point of the first portion of one of the guiding plates, several of the guiding plates or all of the guiding plates is preferably arranged radially above or radially further inwards of the connection point of the directly adjacent guiding plate, in particular of the directly adjacent guiding plate radially inwards. The axial end point of the first portion is the axial end point of the guiding plate in the first direction, which is opposite the connection point of the guiding plate in question. The first portion thus extends from the connection point to its axial end point. Alternatively or additionally, the axial end point of the second portion of one of the guiding plates, several of the guiding plates or all of the guiding plates is arranged radially above or radially further inwards of the connection point of the directly adjacent guiding plate, in particular of the directly adjacent guiding plate radially inwards. The axial end point of the second portion is the axial end point of the guiding plate in the second direction, which is opposite the connection point of the guiding plate in question. The second portion thus extends from the connection point to its axial end point. An optically sealed guiding device is thus produced by this configuration. This means that it is not possible to look directly through the guiding device, so that there is also no direct path for oil molecules through the guiding device. The oil molecules thus only pass through the guiding device by coming into contact with one of the condensation surfaces formed by the guiding plates. Here, however, the oil molecules are condensed and thus do not enter the container. In this way, the backflow of oil molecules can be completely or at least almost completely prevented.

[0011] Preferably, three to five guide plates are provided such that the number of guide plates covers the entire inlet or inlet cross section of the diffusion vacuum pump.

[0012] The at least one guide plate, several or all guide plates are preferably connected to a cooling element, in particular designed as a coolant line, for cooling the guide plates. This makes it possible for the temperature of the guide plates to be reduced to -196°C, so that efficient condensation of propellant vapour on the guide plates is achieved.

[0013] The first portion of the at least one cooled guide plate is preferably formed by a first guide plate element. The second portion of the at least one cooled guide plate is also formed by a second guide plate element. The first guide plate element and the second guide plate element are connected to one another by means of the cooling element. Thus, there is only a connection, in particular designed as a coolant line, between the first guide plate element and the cooling element. Likewise, there is only a connection between the second guide plate element and the cooling element. In particular, there is no direct connection between the first guide plate element and the second guide plate element. This results in a particularly simple structure, which is simple and inexpensive to manufacture.

[0014] Preferably, the first guide plate element and / or the second guide plate element of the at least one cooled guide plate has a substantially and preferably only radially extending portion for connecting to the cooling element. This results in a large-area connection of the first guide plate element or the second guide plate element to the cooling element. Furthermore, the structure is simplified to achieve a simple and inexpensive manufacture.

[0015] Preferably, the first guide plate element and / or the second guide plate element of the at least one, of several and preferably of all guide plates comprises a substantially and preferably only axially extending portion at their respective axial end. This axial extension portion increases the stability of the independent first and / or second guide plate element.

[0016] The axial length of the second portion preferably decreases from the outer guide plate to the inner guide plate. Thus, the guide plates arranged radially further out have a second portion which extends further in the axial direction than the guide plates arranged radially further in, in the direction of the nozzle. This ensures that the guide plates arranged further radially inwards do not interfere and thus adversely affect the propellant jet exiting from the nozzle of the diffusion vacuum pump. At the same time, the guide plates are positioned further out, ensuring that sufficient condensation surface is available in order to prevent oil backflow.

[0017] The guide device preferably has exactly one flange in order to be connected to the diffusion vacuum pump. In particular, the guide device has no housing, but can be installed inside the housing of the diffusion vacuum pump by means of the one flange. In this way, a particularly space-saving structure is achieved.

[0018] The guide plate is preferably connected to the flange, in particular by a web, which extends in particular radially. This ensures sufficient stability of the guide device. At the same time, the installation space of the guide device can be kept small.

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

[0020] Furthermore, as an independent invention, the application relates to a coolant duct for a vacuum pump, in particular a diffusion vacuum pump. The coolant duct has a flange, wherein the flange has a recess opening into the interior, and a coolant line is arranged in the recess. The recess has a first diameter and the coolant line has a second diameter, wherein the second diameter is smaller than the first diameter, so that the coolant line is guided contactlessly in the recess. Since there is a vacuum inside the flange, the contactless guidance of the coolant line inside the flange ensures that no cold energy is transmitted from the coolant in the coolant line to the flange. The coolant duct according to the application thus ensures that the low temperature of the coolant in the coolant line is not transmitted through the flange to the outside of the vacuum pump and also reduces or prevents the formation of ice on the outside of the vacuum pump.

[0021] The coolant line is preferably connected to the flange on the outside of the flange. For example, the flange and the coolant line can be welded in order to form a vacuum-tight connection. The connection on the outside of the flange only forms a small cold bridge through which cold energy can be transmitted from the cooling line to the flange. In particular, if the connection is made by welding, this connection does not extend or only very little into the recess of the flange, so that the cold bridge can be kept small.

[0022] A sealing element, in particular made of plastic material, is preferably arranged at least partially between the coolant line and the flange. Here, the thermal conductivity of the plastic material is significantly lower than that of stainless steel or other metals, so that thermal insulation can be achieved between the coolant line and the flange. At the same time, the sealing element ensures that the coolant channel is vacuum-tight.

[0023] Furthermore, as an independent invention, the application relates to a diffusion pump having at least one nozzle, wherein a propellant is conveyed through the nozzle in order to convey a gaseous medium from an inlet to an outlet of the diffusion vacuum pump. As described above, the diffusion vacuum pump has a guide device which is arranged directly above the inlet-side nozzle, i.e. in the direction of the container. For example, if the diffusion pump has only one nozzle, the guide device is arranged directly above this one nozzle. However, if the diffusion vacuum pump has a plurality of nozzles, the guide device is arranged directly above the nozzle which is arranged in the high-vacuum region, i.e. furthest in the direction of the inlet of the diffusion vacuum pump or the container.

[0024] As mentioned above, the diffusion vacuum pump preferably has a coolant duct. The coolant duct is arranged in the flange of the guide device.

[0025] There is preferably no contact between the inlet-side nozzle and the guide device, so that a transfer of cold from the guide device to the inlet-side nozzle is prevented. The guide device is thus arranged in a thermally insulated manner within the vacuum pump, which ensures an effective cooling of the guide device and at the same time prevents a transfer of cold from the guide device to other parts of the diffusion vacuum pump.

[0026] The diffusion pump preferably has a connection flange, to which the flange of the guide device is connected. In particular, the guide device does not have its own housing, so that the guide device with the flange is directly connected to the connection flange of the vacuum pump and is thus arranged within the housing of the diffusion pump.

[0027] The guide device preferably covers the entire cross-sectional area of the inlet of the diffusion vacuum pump.

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

[0029] In the drawings:

[0030] Figure 1 is a perspective view of a guide device according to the application,

[0031] Figure 2 is a sectional view of a guide device according to Figure 1

[0032] Figure 3 is a top view of a guide device according to Figure 1

[0033] shows a diffusion vacuum pump according to the application, and Figure 4

[0034] Figure 5 shows a coolant duct according to the application.

[0035] The guide device 10 according to the application according to Figure 1 has a flange 12, by 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 individual components of the guide device 10 are thus arranged below the upper side 14 of the flange 12 and thus project into the housing 42 in 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. And the diffusion vacuum pump 40 can thus be connected to a container or a vacuum device by the flange 12 of the guide device.

[0036] ​​In the example shown in the figures, the guiding device 10 has four guiding plates 16 arranged radially to each other. The guiding plates 16 are connected to the flange 12 of the guiding device 10 by radial webs 18. The radial webs 18 are only indirectly connected to the flange 12 by a thermal insulation element 20 for thermal insulation between the flange 12 and the guiding plates 16. Thereby, a transfer of cold energy from the guiding plates 16 to the flange 12 is prevented.

[0037] In Figure 3 It can be seen in that the guiding plates 16 have a first portion 22, which extends from a common connection point 24 in a first direction 23 or towards the direction of the inlet 26 of the guiding device. The radius of the first portion 22 decreases from the common connection point 24, so that the radius of the first portion 22 at its axial end 28 is smaller than at the common connection point 24. Likewise, a second portion 30 extends in a second direction 31 opposite to the axial extension direction or first direction 23 of the first portion 22. The radius of the second portion 30 also decreases from the common connection point 24, so that the radius of the second portion 30 at its axial end 32 is smaller than at the common connection point 24. The first portion 22 and the second portion 30 are only connected to each other at the common connection point 24. The first portion 22 extends in a radial direction, so that it is located above the common connection point 34 of the directly adjacent guiding plate 16. The second portion 30 also extends, so that the axial end 32 of the second portion 30 is located radially below the common connection point 34 of the directly adjacent guiding plate 16. This forms an impermeable construction of the guiding device 10, so that oil molecules cannot directly pass through the guiding device 10, but always hit a condensation surface and thus cannot enter the container.

[0038] As Figure 3 can be seen, at the axial ends 28, 32 of the first portion 22 and / or the second portion 30, the guiding plates 16 comprise an axial extension 33. By means of the axial extension 33, the mechanical stability of the individual guiding plates is enhanced. Damage to the guiding plates 16 during assembly and disassembly is thereby avoided.

[0039] As Figure 3 can be seen, the guiding plates 16 located more inwardly have a second portion with a smaller axial extent. This ensures that the propellant vapour exiting through the nozzle 60 does not collide with the guiding plates 16, but can be guided unhindered in the direction of transport.

[0040] Furthermore, the first part 22 is indirectly connected to the second part 30 by means of a cooling element 36, wherein the cooling element 36 is in particular a coolant line. Cooling energy is transferred to the deflector plate 16 by means of the cooling element 36 in order to achieve an effective condensation of oil molecules on the condensation surface of the deflector plate 16. The cooling element 36 is connected to a coolant duct 50. Here, the flange 12 has a recess or indentation 52 leading into the interior. The recess 52 has a first diameter D1. Furthermore, the coolant line 36 has a second diameter D2, wherein the second diameter D2 is smaller than the first diameter D1, so that the coolant line 36 is at least partially guided contactlessly within the flange 12. Furthermore, the coolant line 36 is connected to the outer side of the flange 12, so that a vacuum-tight connection is formed between the coolant line 36 and the flange 12. For example, the coolant line 36 can be connected to the outer side of the flange 12 by means of welding. In this case, the coolant line is guided contactlessly over a large part of the recess 52 of the flange 12 and only produces a cold bridge in the region of the weld seam 54. However, this cold bridge has a small cross section, so that the transfer of cold energy from the coolant line 36 to the flange 12 is reduced. Alternatively or in addition thereto, a sealing element (not shown) can be provided at least partially, which is arranged between the flange 12 and the coolant line 36, in particular within the indentation or recess 52 of the flange 12. The sealing element is in particular composed of a plastic material and thus has a lower thermal conductivity than stainless steel or other metals from which the flange 12 is made. The cold energy transferred from the coolant line 36 to the flange 12 is thus reduced. This is because there is a vacuum in the region of the recess 52 and thus no or only a small degree of heat transfer takes place in this region. Of course, the deflector device 10 has more than one coolant duct. For example, according to Figure 2 , an inlet 60 and a return 62 for the coolant can be provided, wherein the inlet 60 and the return 62 are each formed as described above and as shown in Figure 5 .

[0041] Figure 4 A diffusion vacuum pump according to the application is shown. This has a housing 42 and an outlet 41. Furthermore, an inlet 43 of the diffusion vacuum pump 40 is provided and is formed by a flange 44. The flange 12 of the deflector device 10 is connected to the flange 44 of the diffusion vacuum pump 40, so that the deflector device is arranged completely within the housing 42 of the diffusion vacuum pump 40. Furthermore, the inlet 26 of the deflector device 10 forms the inlet of the diffusion vacuum pump 40.

[0042] The diffusion vacuum pump 40 has a storage space 45 for storing a propellant. A heating element is provided in the storage space 45, by means of which the propellant is evaporated and discharged again through a nozzle 46. In the process, gas molecules are carried away from the vacuum and are transported in the direction of the outlet 41. The propellant condenses on the inner wall 47 of the housing 42, so that it returns to the storage space 45.

[0043] The guide device 10 is arranged above the inlet-side nozzle 46, i.e. in the direction of the container from the inlet-side nozzle 46. There is no contact between the inlet-side nozzle 46 and the guide device 10, so that no cold energy can be transferred from the guide device to the nozzle.

[0044] Thus, a guide device or vapor barrier is formed which is integrated into the housing of the diffusion vacuum pump, is however easy to install and to remove again and is completely impermeable. Furthermore, due to the coolant duct according to the application, the guide device can be cooled even at very low temperatures down to -196°C without this having a negative effect on the function of the diffusion pump.

Claims

1. A guiding device for a diffusion vacuum pump, comprising: Multiple annular guide plates, the guide plates being arranged radially, At least one of the guide plates has a first portion starting from the connection point and a second portion starting from the connection point. The first part extends axially along a first direction, and the second part extends axially along the opposite second direction. The first part is designed to be radially tapered and / or the second part is designed to be radially tapered. The axial length of the second part decreases from the outer guide plate to the inner guide plate.

2. The guiding device according to claim 1, characterized in that, All guide plates are designed in the same way.

3. The guiding device according to claim 1, characterized in that, The axial end point of one of the guide plates is located radially above or further inward of the connection point of the directly adjacent guide plates.

4. The guiding device according to any one of claims 1 to 3, characterized in that, Set up 3 to 5 guide plates.

5. The guiding device according to any one of claims 1 to 3, characterized in that, At least one of the guide plates is connected to a cooling element for cooling the guide plate to form at least one cooled guide plate.

6. The guiding device according to claim 5, characterized in that, The first and second portions of the at least one cooled guide plate are each formed by a first guide plate element and a second guide plate element, wherein the first guide plate element and the second guide plate element are interconnected by a cooling element.

7. The guiding device according to claim 6, characterized in that, The first guide plate element and / or the second guide plate element of the at least one cooling guide plate have a substantially radially extending portion for connection to the cooling element.

8. The guiding device according to any one of claims 1 to 3, characterized in that, The guide plate is connected to the flange via a radially extending web.

9. The guiding device according to claim 7, characterized in that... Includes coolant conduits for supplying coolant to the cooling element.

10. The guiding device according to claim 9, characterized in that, The coolant conduit includes a flange having a recess of a first diameter, in which a coolant conduit is disposed, and the coolant conduit having a second diameter smaller than the first diameter, such that the coolant conduit is guided without contact within the recess.

11. The guiding device according to claim 10, characterized in that, The coolant line is connected to the flange on the outside of the flange.

12. A diffusion pump having at least one nozzle, wherein the guide device according to any one of claims 1 to 11 is arranged directly above the inlet-side nozzle.

13. The diffusion pump according to claim 12, characterized in that, The nozzle on the inlet side does not contact the guide device.

14. The diffusion pump according to claim 12 or 13, characterized in that... Includes a connecting flange, wherein the flange of the guide device is connected to the connecting flange.

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