Patent Application
20230070087
The object of the present invention is a housing for a vacuum pump and in particular for a non-evaporable getter pump (NEG) or an ion getter pump (IGP)-NEG combination, a vacuum pump with such a housing and a vacuum system with such a vacuum pump.
In numerous industrial and scientific instruments and systems an ultrahigh vacuum is required with pressures below 10-7 mbar. For the generation of such a vacuum in a vacuum apparatus it is known to use combinations of different pump types. Thus, a main pump or backing pump is used to generate pressures from last to 10-1 mbar to 10-3 mbar as low vacuum. Usually, the main pump or backing pump is combined with another vacuum pump to generate a high vacuum or even ultrahigh vacuum including pressures below 10-7 mbar. Ultrahigh vacuum pumps encompass absorption pumps in order to generate the desired pressures. This absorption pumps encompass ion getter pumps (IGP) and volume getter pumps, i.e. evaporable getter material pumps (NEG). Both types of pumps comprise a getter material, wherein for example during operation of the NEG molecules and gas particles from the vessel of the vacuum apparatus are bound to the surface of the NEG material and are thus do not participate anymore to the pressure inside the vacuum apparatus. Due to this deposition the active surface of the NEG material which contributes to the pump performance of the NEG pump is reduced. If no active surface of the NEG is available anymore, the pump performance of the NEG tends to zero and the NEG pump must be regenerated. Regeneration of the getter material is usually made by heating up the getter material. Therein, a part of the bound molecules and gas particles is set free during the regeneration process and must be removed from the vacuum apparatus by an additional vacuum pump. In particular, during regeneration of the getter material, the pressure inside the vessel of the vacuum apparatus may be contaminated by the molecules and gas particles set free from the getter material. Consequently, the pressure increases which is not desirable. Therefore, it is well known to include a valve between the vacuum pump and the vessel to separate the vacuum pump from the vessel of the vacuum apparatus during regeneration of the NEG material. However, due to this valve the distance between the vacuum pump and the vessel is increased, thereby reducing the conductance of the connection and thereby reducing the pump performance of the vacuum pump since in the molecular flow regime the probability for a molecule or gas particle is to enter the vacuum pump is reduced for a low conductance.
It is an object of the present invention to provide a housing for a vacuum pump, improving the conductance of the vacuum pump and avoiding contamination of the vacuum inside the vessel during regeneration of the vacuum pump.
A solution to the given program is provided by the housing according to claim 1, the vacuum pump according to claim 6 and the vacuum system according to claim 7.
The housing for a vacuum pump in accordance to the present invention in particular for a NEG or an IGP comprises a body defining an interior space to accommodate the vacuum pump. In particular, the interior space contains the NEG material or the iron getter material of the NEG or IGP, respectively. Further, a first flange is connected to the housing comprising an opening to connect the vacuum pump to a vessel. Thus, molecules or gas particles from the vessel can enter the interior space through the opening and then interact with the vacuum pump in the interior space. Further, the body comprises a second flange to connect the housing to an additional vacuum pump at least during regeneration. Thus, the second flange might be connected to another vacuum pump only during regeneration in order to pump the gas particles and molecules set free during the regeneration process or alternatively the second flange is used to connect the housing to a backing pump during operation.
In accordance with the present invention, a movable shielding element is used, wherein the shielding element is movable from a first position to a second position, wherein in the first position the opening of the first flange is unobstructed and in the second position the opening is blocked and preferably completely blocked. The shielding element is disposed inside the interior space and in front of the opening of the first flange if in the second position. By the shielding element the conductance is reduced considerably between the vacuum pump and the vessel. Thus, during regeneration of the NEG, the shielding element is moved into the second position. Molecules or gas particles set free from the vacuum pump during regeneration cannot re-enter the vessel and contaminate the vacuum inside the vessel due to the low conductance. It is more likely, and the probability is much higher that the gas particles or molecules are pumped by the additional vacuum pump connected to the second flange.
Preferably, there is no valve arranged at the first flange preferably between the vacuum pump and the vessel or incorporated between the body and the flange. Due to the shielding element, the housing for the vacuum pump can be directly connected to the vessel in order to enhance and improve the conductance during operation if the shielding element is in the first position. No further element needs to be employed between the vacuum pump and the vessel.
Preferably, the shielding element is a sheet element that can be easily manufactured, wherein the requirements to the shielding elements are low since no complete sealing is required by the shielding element.
Preferably, the shielding element is guided by a guiding track or guide rails to be movable from the first position to a second position.
Preferably, the shielding element comprises no sealing elastomer or the like in order to provide a vacuum tight sealing. It is an object of the present invention that by the shielding element it is only necessary to reduce the conductance between the vacuum pump and the vessel to avoid contamination of the vacuum in the vessel during regeneration of the vacuum pump since vacuum pump and vessel are in the molecular flow regime. Complete sealing between the interior space of the housing and the vessel of the vacuum apparatus is neither necessary nor required.
Preferably, the shielding element comprises a magnetic element or alternatively the shielding element itself might be magnetic and made from a magnetic material. The magnetic element is connected with a magnetic handle outside the body of the housing in order to transfer the movement of the magnetic handle to the shielding element. Thus, by the magnetic handle the shielding element can be moved from the first position to the second position inside the interior space. It is not necessary to provide any mechanical contact of feedthrough between the handle outside the body and the shielding element that would cause a leakage and would require additional efforts for sealing the movable parts. Thus, due to the magnetic attraction between the magnetic handle and the magnetic element of the shielding element, the magnetic shielding element itself can be moved in an easy way to control the position of the shielding element.
Further, the present invention relates to a vacuum pump comprising an NEG and/or IGP vacuum pump in a housing as previously described.
Further, the present invention relates to a vacuum system comprising a vacuum pump as previously described and a vacuum vessel, wherein the vessel is directly connected to the vacuum pump. In particular, no valve is disposed between the vacuum pump and the valve in order to enhance the conductance between the vessel and the vacuum pump.
The summary is provided to introduce a selection of concepts in a simplified form that are further described in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Further, the housing comprises a shielding element 18 which is movable from a first position as shown in the figure to a second position in front of an opening 20 of the first flange 14. Therein, the shielding element 18 is guided by guiding tracks 22. If the shielding element 18 is in the second position in front of the opening 20 of the first flange 14, the direct way between the vessel connected to the first flange 14 and the interior space 12 of the housing is obstructed. During the regeneration of the vacuum pump inside the housing, gas particles or molecules set free from the vacuum pump are more likely leaving the interior space 12 through an opening 24 of the second flange 16 than through the opening 20 of the first flange 14. If the opening 20 of the first flange 14 is obstructed by the shielding element 18, the shielding element 18 reduces the conductance between the interior space 12 and the vessel connected to the first flange 14. Flow of the gas particles and molecules inside the housing of the vacuum pump, the flanges 14, 16 and the vessel is in the molecular flow regime. Thus, the shielding element 18 is not necessarily completely sealing the interior space 12 from the housing to the vacuum vessel. Instead, the shielding element just reduces the conductance between the interior space 12 and the vessel reasonably that it is more likely that the gas particles and molecules leave the interior space 12 through the opening 24 of the second flange 16 than returning to the vessel connected to the first flange 14 contaminating the vacuum inside. Therefore, the shielding element, built as shield metal element, neither comprises a sealing nor requires a gap-free design to provide a leak tight configuration.
The shielding 18 is connected to a magnetic element 26 disposed within the interior space 12 of the housing. The magnetic element 26 is connected to a magnetic handle 28 outside the housing and connected to the magnetic element 26 by a magnetic force such that movement of the magnetic handle 28 is transferred to the magnetic element 26 and thereby to the shielding element 18. Thus, by moving the magnetic handle 28 outside the housing, the shielding element 18 can be moved from the first position to the second position. No mechanical feedthrough is necessary in order to move the shielding element 18. In particular, the body of the housing is made from a non-magnetic material to allow magnetic coupling of the magnetic handle 28 to the magnetic element 26.
By the present design of the housing, the vacuum pump inside the interior space 12 of the housing can be placed in close proximity to the vacuum vessel connected to the first flange 14. No additional valve needs to be placed between the first flange 14 and the vacuum vessel in order to separate the interior space 12 from the vacuum vessel to avoid contamination of the vacuum inside the vacuum vessel during regeneration of the vacuum pump. Thereby, the conductance is enhanced, enhancing the pump performance of the vacuum pump inside the housing.
Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2001783.6 | Feb 2020 | GB | national |
This application is a Section 371 National Stage Application of International Application No. PCT/IB2021/051079, filed Feb. 10, 2021, and published as WO 2021/161188 A1 on Aug. 19, 2021, the content of which is hereby incorporated by reference in its entirety and which claims priority of British Application No. 2001783.6, filed Feb. 10, 2020.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2021/051079 | 2/10/2021 | WO |
