Patent Application
20140170001
1. Field of the Invention
The invention relates to a vacuum system including a vacuum pump and at least one to-be-evacuated recipient.
2. Description of the Prior Art
The state of the art (DE 24 16 808 A1) discloses a sealing element for vacuum purposes. The known sealing element is formed of metal because sealing elements which are formed of an elastomeric material are not heat-resistant and, therefore, cannot be used at high temperatures. In particular, when the recipient becomes heated, the elastomeric sealing elements become unusable because these sealing elements either produce gas and, thus, “contaminate” the vacuum, or the elastomeric sealing elements become damaged upon being heated, whereby sealing is not any more effective.
The drawback of the state-of-the art metal sealing elements consists in that they, as a rule, can be used only once or, at most, several times because the metal does not have the advantage of the elastomeric material, namely, an elastic deformability. Therefore, with each strong deformation, a new sealing element should be used.
Because the metal sealing elements are often formed of an expensive material (copper, indium, gold or the like), the costs of the metal sealing elements are relatively high.
State of the art (DE 24 16 808 A1) suggests to form a metal sealing ring and a centering ring as a spring ring with a radial slot. However, this shape is very expensive and, therefore, this sealing element is very costly.
Known are UHV (ultra high vacuum)—flanges. These flanges have cutting edges and, e.g., copper sealing elements. Between two flanges, a copper ring is arranged. The concentrically extending cutting edges of the flanges penetrate in the copper and form a metal sealing which is characterized by an extremely low leakage and permeability and a high temperature resistance. These flanges are also called Conflat® flanges (registered trade mark of the firm Agilent Technologies Inc., U.S.A.) or CF-flanges. The drawback of these flanges consists in that they act on the metal sealing elements. Because of the lasting deformation of the metal sealing elements, their multiple use is not any possible. Thus, they can only be used once. In addition, for strength reasons, it is necessary to use stainless steel instead, e.g., of aluminum.
The object of the invention is to provide an interface of a vacuum system and which is optimal with respect to weight, costs, and vacuum capacity and which can be used with a heatable UHV-chamber. A further object of the invention is an O-ring sealing element for a vacuum system and which is formed of an elastomeric material and despite of that does not contaminate ultra high vacuum.
These and other objects of the present invention which will become apparent hereinafter, are achieved by providing a vacuum system including at least one recipient having a housing and at least one outlet opening for evacuating the recipient, a vacuum pump connected with the at least one outlet opening of the at least one recipient for evacuating same, an attachment provided between the vacuum pump and the recipient housing and formed as an intermediate piece, with the attachment being fixedly and vacuum-tightly secured on the recipient, and the vacuum pump being fixedly and releasably secured to the attachment at an end of the attachment opposite the recipient, and at least one O-ring sealing element provided between the attachment end opposite the recipient and the vacuum pump for sealing the vacuum pump, the O-ring sealing element being formed as an elastomeric O-ring.
The advantage of the inventive structure consists in that an economical elastomeric O-ring can be used as an O-ring sealing element which nevertheless does not contaminate the ultra vacuum.
The advantage of the inventive vacuum system consists in that by providing of an attachment on the recipient housing, the sealing element is displaced in the direction from forevacuum to a high pressure region. When the UHV-region becomes heated, the O-ring sealing element due to the axial spacing which results from the arrangement of the attachment between the recipient and the vacuum pump, is not stressed too much.
It is particularly advantageous when the attachment is formed of stainless steel or aluminum or any other material which has advantageously a low heat conductivity, so that the attachment does not transmit heat to the O-ring sealing element.
Advantageously, the attachment is formed as a tubular attachment, e.g., as a tube. Advantageously, the vacuum pump housing is also formed at least partially of aluminum. This makes the pump lighter because an aluminum housing is lighter than a conventional heavy stainless steel housing which is used, as is known from practice, with CF-sealing elements.
According to a further advantageous embodiment of the invention, at least the connection flange of the vacuum pump for connection with the recipient is formed of aluminum. With this, the reduction of weight also becomes possible. The formation of the connection flange of aluminum become possible as no CF-flange with a metal sealing element must be used, rather than O-ring sealing with at least one elastomeric O-ring is used.
The attachment, which is provided between the recipient housing the vacuum pump has advantageously a wall thickness from 1 mm to 10 mm.
In order to obtain an air-tight and fixed connection between the attachment and the recipient housing, the attachment is advantageously welded to the housing. However, it is also possible to provide other vacuum-tight connections between the attachment and the housing.
According to a further advantageous embodiment of the invention, it is also possible to form the attachment and the recipient housing as a one-piece member.
The attachment has at its end opposite the recipient a flange for connection with the vacuum pump. In this region at least one O-ring sealing element is provided. Thereby a conventional flange connection with the vacuum pump can be provided.
The attachment flange is connected with a connection flange of the vacuum pump by screw means. This is a very simple type of connection. It is also possible to use clip means and other connecting means for a releasable connection of flanges.
Advantageously, at least one O-ring is provided between the flanges of the attachment and the vacuum pump as a sealing element. The advantage of this consists in that the O-ring is displaced axially from the housing of the recipient in the direction of the vacuum pump so that heating of the recipient does not have any negative effect on the elastomering O-ring.
According to an advantageous embodiment of the invention, the vacuum pump has a tubular piece that is at least partially received in the attachment which is arranged between the recipient housing and the vacuum pump. The tubular piece additionally blocks fumigation and leakage which may occur in vacuum when an O-ring sealing element is used.
A higher pressure level in the region of the O-ring sealing has an advantage that consists in that the O-ring sealing has a noticeably smaller fumigation or not all.
In addition, it is advantageous when a clearance is provided between the tubular piece of the vacuum pump and the attachment which is arranged between the recipient and the vacuum pump. According to a particularly advantageous embodiment of the invention, an intermediate suction from this narrow clearance or slot is provided. To this end, the tubular piece is advantageously provided with at least one opening for suction of gases. Thereby, the number of particles which penetrates in the UHV-region as a result of fumigation can be minimized.
Advantageously, the tubular piece of the vacuum pump has at least one collection groove, and wherein the at least one or more openings for suction of gases is (are) provided in the at least one collection groove.
Advantageously, the tubular piece is formed of stainless steel or aluminum. The vacuum system according to the present invention has advantageously a vacuum pump that is formed as a turbomolecular pump. Particularly advantageously, the vacuum system has a pump that is formed as a split flow pump. It is particularly advantageous to use turbomolecular and split flow pumps in the UHV-region.
The inventive construction has an additional advantage that consists in that the pump can be placed closer to the recipient because in practice, with the use of CF-flanges, an axial length of the construction is reduced and thereby, the location for the screw connection can be provided in the region of the pump housing. Thereby, the volume of the construction is reduced, and the conductance with regard to an effective suction capacity is increased. A further advantage of the invention consists in the possibility to re-use the sealing element.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.
The drawings show:
Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and is not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is, therefore, not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102012112492.2 | Dec 2012 | DE | national |
