Patent Application
20220139689
Applicant claims priority under 35 U.S.C. § 119 of German Application No. 10 2020 128 646.5 filed Oct. 30, 2020, the disclosure of which is incorporated by reference.
The invention relates to a multipole with mounting rings arranged on its end faces for mounting the multipole in a mass spectrometer, wherein the multipole has two electrode half-shells each with at least two electrodes, which can be joined together by positive connections arranged on the longitudinal edges of the electrode half-shells. Each of the positive connections comprises a fitting and a mating fitting matched to it, with the fitting being integrally formed on one of the two electrode half-shells and the mating fitting on the other of the two electrode half-shells.
The invention also relates to a mounting ring for such a multipole.
The invention relates to multipoles such as those used in mass spectrometers. Multipoles are multi-polar electrode devices and are well known, for example from the German patent specification DE 944900.
As stated in EP 3 385 979 A1, on the one hand, precise alignment of the electrodes of the electrode device relative to each other is essential for the analytical measuring accuracy so that the electrodes are normally fixed to a carrier element designed as a half-shell. Such half-shells can be assembled with high accuracy, so that a high analytical measuring accuracy of a mass spectrometer can be achieved.
On the other hand, the installation of a multipole in a mass spectrometer must be carried out with the highest possible accuracy in order to achieve a high measuring accuracy.
This conventional multipole 10 comprises two electrode half-shells 16, 18, each with two rod-shaped electrodes 20, 22 and 24, 26, which are each fixed in pairs on a carrier 28, 30, connected together by insulating bodies 32, 36, 38.
The lower electrode half-shell 16 can be joined to the upper electrode half-shell 18 via positive-fitting connections 40, 42, 44, arranged on the longitudinal edges 46, 48, 50, 52 of the electrode half-shells 16, 18.
In this case, the term longitudinal edge is not to be understood in a one-dimensional sense, but rather in such a way that the longitudinal edges 46, 48, 50, 52 form narrow surfaces, the width of which corresponds to the thickness of the carriers 28, 30.
In
The electrode half-shells 16, 18 are structured and shaped identically. Therefore, the lower electrode half-shell 16 also has mating fittings 66, 68, 70 on its rear longitudinal edges 48, which are integrally formed with corresponding fittings (not visible in the figures) on the rear longitudinal edge 52 of the upper electrode half-shell 18 and form further positive-fitting connections in pairs.
All of these positive-fitting connections are secured with screws 72, 74, 76, 78, 80, 82.
In the present context, a positive-fitting connection is understood to mean a connection that eliminates a relative displacement of two components, at least in one dimension. This means that the positive-fitting connections described in this document between the fitting and the mating fitting are designed in such a way that, after being joined, the two electrode half-shells 16, 18 can be moved in the longitudinal direction of the multipole 10 until the screws 72, 74, 76, 78, 80, 82 are installed. However, due to these positive-fitting connections, displacement of the electrode half-shells 16, 18 in the radial direction of the multipole 10 is not possible.
The two front and rear end faces 84, 86 are terminated by the mounting rings 12, 14, which are clamped to clamping lugs 88—provided on the electrode half-shells 16, 18—by turning the mounting rings 12, 14.
These mounting rings 12, 14 are used to mount the multipole 10 in the mass spectrometer. The alignment and positioning of the multipole 10 in the mass spectrometer can therefore only be achieved with an accuracy limited by the attachment of the mounting rings 12, 14 to the multipole 10. To achieve a high degree of accuracy, it is therefore necessary to adapt the mounting rings 12, 14 to the clamping lugs 88, which often requires individual reworking of the mounting rings 12, 14 and/or the electrode half-shells 16, 18 in the area of the clamping noses 88. A high degree of accuracy can therefore only be achieved with significant processing effort.
The object of the invention is therefore to enable the mounting of a multipole in a mass spectrometer with high accuracy but at the same time with little effort.
This object is achieved by means of the features of a multipole according to one aspect of the invention and by means of a mounting ring having the features of another aspect of the invention.
The multipole according to the invention therefore has mounting rings arranged on its end faces for mounting the multipole in a mass spectrometer, wherein the multipole has two electrode half-shells each with at least two electrodes, which can be joined together by positive-fitting connections arranged on the longitudinal edges of the electrode half-shells, each positive-fitting connection comprising a fitting and a mating fitting matched to it, wherein the fitting is integrally formed on one of the two electrode half-shells and the mating fitting is integrally formed on the other of the two electrode half-shells. According to the invention, each of the mounting rings has two mounting ring fittings, wherein each of the two mounting ring fittings can be joined to a mating fitting integrally formed on one of the two electrode half-shells and the other of the two mounting ring fittings can be joined to a mating fitting integrally formed on the other of the two electrode half-shells.
The mounting ring according to the invention for such a multipole therefore has two mounting ring fittings which are designed so as to be joined to correspondingly designed mating fittings that are integrally formed on the electrode half-shells.
In this way, according to the invention, the mounting rings can also form precisely fitting positive-fit connections with the electrode half-shells, which guarantee a high accuracy when installing the multipole in the mass spectrometer with little installation effort.
This design of the mounting rings and the multipole makes it possible to manufacture the fittings and mating fittings of the electrode half-shells by grinding the electrodes jointly with the fittings and mating fittings of the electrode half-shells. In this way, the mating parts on the electrode half shells—as well as their fittings—are manufactured with the high accuracy of the electrodes. This means that the mating fittings into which the mounting ring fittings engage are machined with the same high accuracy as the electrodes. This processing is carried out in a common processing step and is therefore possible with minimal effort. The surfaces of the mounting ring fittings can be produced separately with high precision, for example by milling the mounting rings.
Overall, the invention therefore allows a very accurate mounting of the multipole in the mass spectrometer to be achieved with relatively little effort.
The mating part of one of the electrode half-shells, which can be joined to a mounting ring fitting, is preferably part of one of the positive-fitting connections for joining the two electrode half-shells together. This is advantageous because a mating fitting of the electrode half-shells can thus be used for a connection of a mounting ring to the multipole and thus no separate additional mating fitting needs to be provided on the multipole for joining it to a mounting ring.
An alternative embodiment of the invention provides that the mating fitting of one of the electrode half-shells, which can be joined to a mounting ring fitting, is designed separately from the mating fittings of the electrode half-shells, which are provided for the positive-fitting connections for joining the two electrode half-shells together.
An extension of the invention provides that the fittings each have a roof structure and the mating fittings each have a prism structure, so that each fitting and the mating piece joined to it form a roof-and-prism connection. The invention has recognized that such flat structures can be ground with high accuracy and low effort, while still allowing reliable and precise positioning of the parts to be assembled.
According to an extension of the invention, each fitting can be screwed to the mating piece which is joined to it by means of a screw to form a screw connection. Such screw connections have proved to be particularly reliable.
An extension of the invention provides that each electrode half-shell has a plurality, preferably three, of mating fittings on a longitudinal edge, with the two outer mating fittings each having two drilled holes for screws. Each of the two outer screws can be screwed to a different one of the two mounting ring fittings.
An extension of the invention also provides that the fittings on the electrode half-shells and the mounting ring fittings each have a threaded hole for receiving one of the screws. This construction can be produced with little effort and assembled with little effort, and is therefore particularly advantageous.
An extension of the invention provides that the mounting ring fittings are integrally formed on the respective mounting ring in a rotationally symmetric manner. The mounting ring fittings are preferably arranged to be rotationally symmetric by 180°. On account of this design, identical mounting rings can advantageously be used on both end faces.
This enables the electrode half-shells also to be designed identically. This means that the upper electrode half-shell is designed in the same way as the lower electrode half-shell. In addition, both mounting rings are the same and are rotationally symmetric by 180°. Due to these designs, only one electrode half-shell type and only one mounting ring type is required for a multipole to be produced. Therefore, two different electrode half-shells or two different mounting rings do not need to be produced and stocked. This reduces manufacturing and storage costs while maintaining the same quality of the parts that are identical in construction.
Extensions of the invention are derived from the patent claims, the description and the drawings. The advantages of features and combinations of multiple features mentioned above are only exemplary and may have an alternative or cumulative effect without the advantages necessarily having to be obtained from embodiments according to the invention. Further features can be found in the drawings—in particular the illustrated geometries and dimensions of several components relative to each other as well as their relative arrangement and effective connection. The combination of features of different embodiments of the invention or of features of different claims is also possible in deviation from the chosen cross references of the claims and is thereby encouraged. This also applies to those features which are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different claims. Likewise, the features listed in the claims may be omitted for other embodiments of the invention.
Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.
In the drawings,
The multipole 110 comprises two electrode half-shells 116, 118. Each of these electrode half-shells 116, 118 has a plurality, namely in the example two, of rod-shaped electrodes 120, 122 and 124, 126. Each pair of these electrodes 120, 122 or 124, 126 is fixed on a carrier 128, 130, connected together by insulating bodies 132, 136, 138. These insulating bodies 132, 136, 138 electrically insulate the electrodes 120, 122, 124, 126 from the carriers 128, 130. For example, the insulating bodies 132, 136, 138 can be made of quartz or quartz glass.
Each of the carriers 128, 130 is essentially shaped like a half-hollow cylinder fitted with recesses and holes, i.e. a hollow cylinder cut open lengthwise. These carriers 128, 130 are made of metal or a metal alloy and are electrically conductive and have a specified wall thickness.
The electrodes 120, 122, 124, 126 in the illustrated exemplary embodiment are each designed in three parts. They each have a longer central section and two shorter outer sections. The outer sections are used, for example, to form a pre-filter and a post-filter. Alternatively, the electrodes 120, 122, 124, 126 (contrary to the exemplary embodiment shown) can each be designed as one piece.
The lower electrode half-shell 116 can be joined to the upper electrode half-shell 118 via positive-fitting connections 140, 142, 144, arranged along the longitudinal edges 146, 148, 150, 152 of the electrode half-shells 116, 118. As already mentioned above, these longitudinal edges 146, 148, 150, 152 form narrow surfaces, the width of which corresponds to the wall thickness of the carriers 128, 130.
Analogous to
The electrode half-shells 116, 118 are structured and shaped in the same way. Therefore, the lower electrode half-shell 116 on its rear longitudinal axis 148 also has mating fittings 166, 168, 170, which are integrally formed with corresponding fittings (not visible in
A mounting ring 112 is provided on the front end face 184. A mounting ring 114 is provided on the rear end face 186 in the same way. The mounting of these mounting rings 112, 114 on the multipole 110 differs considerably from the prior art according to
The mating fitting 160 of the electrode half-shell 118, which can be joined to the mounting ring fitting 190 of the mounting ring 112, is part of the positive-fitting connection 140 with which the two electrode half-shells 116, 118 are joined together. A further, not shown, mounting ring fitting of the mounting ring 112 is joined together with the mating fitting 166 of the electrode half-shell 116 and is also part of a positive connection between the two electrode half-shells 116, 118.
In the same way, the mating fitting 164 of the electrode half-shell 118, which can be joined to the mounting ring fitting 194 of the mounting ring 114, is part of the positive-fitting connection 144 with which the electrode half-shells 116, 118 are connected. The further mounting ring fitting 196 of the mounting ring 114 is joined to the mating fitting 170 of the electrode half-shell 118 and is also part of a positive-fitting connection between the two electrode half-shells 116, 118.
These positive-fitting connections between the mounting rings 112, 114 and the electrode half-shells 116, 118 are secured with screws 198, 200, 202, 204 to form screw connections. Additional drilled holes 206, 208, 210, 212 are provided in the mating fittings 160, 164, 166, 170 for this purpose, through which holes these screws 198, 200, 202, 204 are passed. The mounting ring fittings 190, 194, 196 of the mounting rings 112, 114 have threaded holes for receiving these screws 198, 200, 202, 204.
The mounting fittings 190, 194, 196 of the mounting rings 112, 114 each have a roof structure and can be joined to matching prism structures of the mating fittings 160, 164, 166, 170 to form roof-and-prism connections.
As stated above, a positive-fitting connection is a connection which excludes a relative displacement of two components at least in one dimension, so that the positive connections described in this document are formed by a fitting with a mating fitting in such a way that, after being joined to the electrode half-shells 116, 118, the mounting rings 112, 114 can be moved in the longitudinal direction of the multipole 110 until the screws 172, 174, 176, 178, 180, 182 are installed. However, such a displacement of the electrode half-shells 116, 118 and the mounting rings 112, 114 in the radial direction of the multipole 110 is then also not possible, on account of these positive-fitting connections. After these screws are tightened, the longitudinal displacements of the multipole 110 are also excluded.
The fixing according to the invention of the mounting rings 112, 114 to the multipole 110 contributes to enabling the alignment and positioning of the multipole 110 in a mass spectrometer with very high accuracy, since the surfaces of the roof structures and prism structures can be produced with very high accuracy and at the same time with little effort. The prism structures of the mating fittings 160, 164, 166, 170 on the electrode half-shells 116, 118 are ground together with the electrodes, wherein this grinding is a highly accurate machining process with an accuracy in the range of a few microns. While the surfaces of the mounting ring fittings 190, 194, 196 of the mounting rings 112, 114 cannot be ground at the same time, they can also be machined with high precision in a separate processing step.
Overall, the invention therefore allows mounting rings to be provided for mounting a multipole in a mass spectrometer, which ensure a high accuracy of the positioning and alignment of the multipole in the mass spectrometer.
Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.
The figures use the following reference numbers:
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 128 646.5 | Oct 2020 | DE | national |
