Vacuum pump housing

Abstract

Vacuum pump housing (100,fig.1), in particular for a multistage 2-shaft vacuum pump comprising a housing element 10 having an upper side 11 and an opposite lower side (13.fig.1). The housing comprises

Description

The present invention relates to a vacuum pump housing and in particular for multistage 2-shaft vacuum pump. Further, the present invention relates to a vacuum pump comprising such a vacuum pump housing. Common vacuum pumps comprise a pump housing defining at least one pump chamber and having an inlet and an outlet. If the vacuum pump is built as multistage vacuum pump, by the housing a plurality of consecutive pump chambers are defined separated by respective chamber walls. A rotor assembly is rotatably supported by the pump housing, wherein the rotor assembly comprises a rotor shaft and at least one rotor element. The at least one rotor element is arranged in the pump chamber. In the case of a multistage vacuum pump a corresponding number of pump elements are connected to the rotor shaft such that in each pump chamber at least one rotor element of the rotor assembly is arranged. In the case of a 2-shaft vacuum pump, the vacuum pump comprises two rotor assemblies rotated synchronously such that in each pump chamber by the interaction of the respective rotor elements a gaseous medium is conveyed from the inlet of the vacuum pump towards the outlet of the vacuum pump. For multistage 2-shaft vacuum pumps, the individual pump chambers are separated by chamber walls separating the adjacent pump chambers. The chamber walls comprise openings such that the shaft of each rotor assembly can extend from one pump chamber into the adjacent pump chamber through a respective opening. In case of a 2-shaft vacuum pump, correspondingly the chamber wall comprises two openings. In order to separate the pressure of adjacent pump chamber a shaft seal might be arranged in or close to each opening in order to prevent backflow of the gaseous medium from a pump chamber with higher pressure towards a pump chamber with lower pressure against the intended direction of flow of the gaseous medium through the vacuum pump. Therein the shaft seal might be provided by a small gap between the chamber wall and the shaft. Due to compression; heat is generated in the individual pump chambers. An intermediate section of the chamber wall located in between the respective openings is the most distant part of the chamber wall from any cooling elements or the outer surface of the vacuum pump. At the same time the intermediate section is exposed to the heat generated by the compression. Since the intermediate section is also directly connected to the area of shaft seals, excessive heat is not desired in this area and may cause malfunction of the shaft seal. In addition, insufficient heat dissipation away from the intermediate section of each chamber wail will cause a temperature gradient which may lead to thermal stress and localized thermal expansion in the chamber wall and may have an impact of the clearance between the vacuum pump housing and the rotor in particular in the area of the small gap forming the shaft seal. To avoid contact between the rotor elements / rotor shaft and the vacuum pump housing and in particular the chamber walls, larger clearances are implemented taking into account the larger temperatures of the intermediate sections as a precaution, leading to a decrease of performance due to an increase of backflow through the enlarged clearances. It is an objective of the present invention to provide a sufficient cooling of the chamber walls of a vacuum pump. The problem is solved by a vacuum pump housing according to claim 1 and a vacuum pump according to claim 13. The vacuum pump housing according to the present invention is in particular a vacuum pump housing for a multistage 2-shaft vacuum pump. However, the present invention can also be implemented in a vacuum pump housing for other pumps like single stage vacuum pumps, single shaft vacuum pumps and / or multi-shaft vacuum pumps comprising more than two shafts. The vacuum pump housing according to the present invention comprises a housing element having an upper side and an opposite lower side. A plurality of chamber wails are defined by the housing element. By the chamber walls, at least one pump chamber and preferably a plurality of pump chambers are defined separated / deiim-ited by respective chamber walls and configured to receive at least one rotor element connected to one of the pump shafts. In particular, more than one pump element, each connected to a different rotor shaft may be arranged in each of the pump chambers acting together by synchronous rotation in order to convey a gaseous medium from an inlet of the vacuum pump housing to an outlet. The chamber walls extend at ieast partially and preferably completely between the upper side and the lower side of the housing element. At least one chamber wall comprises openings through the chamber wall such that the rotor shaft may extend into the pump chamber through the openings. In particular, the openings may extend from one pump chamber to a directly adjacent pump chamber such that respective pump shafts can extend from one pump chamber to the neighboring pump chamber through the openings. In particular, the number of openings may correspond to the number of shafts of the vacuum pump. In particular, each chamber wail may comprise respective openings or alternatively all chamber walls comprise respective openings except the last chamber wall forming an outer wall of the housing, wherein at the opposite end the shafts may extend through the chamber wall outside the housing to be connected to a gear or electric motor. Therein, the openings of the at least one chamber wall are separated by an intermediate section of the chamber wall. Preferably, each chamber wall having openings may have a respective intermediate section in between these openings. The intermediate section is thus located between adjacent openings. In other words, the intermediate section may form a part of the chamber wall which may be integral with the chamber wall and located between adjacent openings. The intermediate section is the part of the chamber wall. The chamber wall is exposed to the heat generated due to the compression of the gaseous medium in the vacuum pump. In particular, heat would accumulate in the intermediate section which would cause an undesired increase of temperature of this area due to the reduced cross-sectional area of the intermediate section and distance to one of the outer surfaces of the vacuum pump housing. Thus, heat conductance and consequent!1 / heat dissipation away from the intermediate section towards other parts of the vacuum pump, such as any outer surface of the vacuum pump housing, is decreased. According to the present invention at least one heat spreading element is arranged in the intermediate section and extends from the intermediate section towards the upper side and / or the Sower side of the housing element. By the heat spreading element heat is dissipated away from the intermediate section of the chamber wall towards the upper side and / or the lower side and can be dissipated from the upper side and the lower side of the housing element. Thus, by the heat spreading element temperature in the are of the intermediate section can be effectively reduced, in particular by more than 30K, preferably more than 20K and more preferably by more than 10K. Preferably, the chamber walls are integrally formed with the housing element. Preferably, the at least one heat spreading element extends from the intermediate section substantially to the upper side and / or lower side of the housing element. Consequently, heat of the intermediate section is provided by the heat spreading elements directly to the upper side and / or lower side and can be effectively dissipated from there. Preferably, the at least one heat spreading elements extends in a direction substantially perpendicular to the shafts. Thus, by the heat spreading element the shortest distance between the intermediate section and the outer surface of the housing element is taken in order to effectively conduct the heat away from the intermediate section. Preferably, the at least one heat spreading element is made of a material having a heat conductance higher than the heat conductance of the materia! of the chamber wall and / or the housing element. In particular, the chamber wall and / or the housing element are made from cast iron having a poor heat conductance. In particular, the heat spreading element may be made from aluminum or copper providing improved heat conductance compared to the material of the chamber wall and / or housing element. Preferably, the housing element comprises a plurality of housing parts which are consecutively arranged along the axial axis of the rotor shaft. Therein, by each housing part at least one and more preferably exactly one pump chamber is defined. In addition, also the chamber wall of the respective pump chamber may be formed by the housing part (maybe except for the first and / or last housing part which may be closed by a plate forming the respective chamber wall), including the intermediate section. Thus, assembly of the vacuum pump is carried out by alternating assembly of a rotor element to the respective rotor shafts and assembly of one housing part, or vice versa, such that the rotor elements are arranged in the pump chamber defined by the respective housing part. Thereby, a stacked design of the vacuum pump housing is achieved. Preferably, the housing element comprises a first section and a second section, wherein by the first section and second section the pump chambers may be defined, i.e. the housing element is separated in an upper section and a lower section along an intersection. The at least one chamber wall is separated by the first section and the second section at the intersection and a first intermediate part of the first section is in direct contact with a second intermediate part of the second section. By the first intermediate part and the second intermediate part the intermediate section of the at least one chamber wall is formed. Hence, by the first section and the second section the housing element is separated, wherein upon assembly of the first section with the second section the chamber walls and the pump chambers are defined. In addition, the first section and the second section may combinedly define the respective openings through the at least one chamber wall. For example, the first section may comprise respective upper halves of the openings, wherein the second section may comprise respective lower halves of the openings such that upon assembly of the first section with the second section, the openings are formed. Therein, the at ieast one heat spreading element is arranged within the first intermediate part and / or second intermediate part. Thus, the heat spreading eiement is provided either by the first section, the second section, or both. Preferably, by the first section the upper side of the housing element is defined, wherein by the second section the lower side of the housing element is defined. In the case of a heat spreading element only the first intermediate part, heat is conducted away from the intermediate section towards the upper side of the housing element. Alternatively, if the heat spreading element is only arranged in the second intermediate part, heat is conducted away from the intermediate section towards the lower side of the housing element. In case of a heat spreading element in the first intermediate part as well as in the second intermediate part, heat from the intermediate section is conducted towards the upper side as well as the lower side of the housing and can be effectively dissipated. Preferably, the at least one heat spreading element extends from the first section at least partially into the second section. Hence, the heat spreading element can transfer heat from the first intermediate part towards the second intermediate part and thus thermal contact between the first section and the second section may be improved. In particular, if more than one heat spreading elements are implemented, a first heat spreading element may extend from the first section at least partially into the second section and a second heat spreading element may extend from the second section at ieast partially into the first section. Thus, thermal contact between the first section and the second section in the area of the intermediate section is improved allowing efficient heat dissipation away from the intermediate section. Preferably, the at least one heat spreading element arranged in the first intermediate part or the first section is contacting the at least one heat spreading element of the second section, i. e. arranged in the second intermediate part, at the intersection of the first section and the second section. Hence, the at least one heat spreading element of the first section flushes with the intersection surface of the first section which comes into contact with a corresponding intersection surface of the second section. Thereby, assembly of the first section and the second section is simplified due to omitting of interlocking or nested features or elements. Preferably, the at least one heat element of the first section, i, e, arranged in the first intermediate part and / or the at least one heat element of the second section, i. e. arranged in the second intermediate part, end in a distance from the intersection of the first section and the second section. Hence, the heat spreading element is fully enclosed by the material of the chamber wall and does not fully extends up to the intersection. In addition, the heat spreading element of one section does not come into contact with the other section, respectively. Consequently, the complete inner surface of the first section and / or the second section defining the contact surface of the intersection as well as the pump chambers may be made from the material of the chamber wall, i. e. the housing element. Therein, the at least one heat spreading element may be inserted into a blind hole provided from the upper surface or the lower surface, respectively. In this case, the heat spreading element does not come into contact with corrosive contaminants contained in the gaseous medium conveyed by the vacuum pump, which would otherwise degrade the at least one heat spreading element. In addition, an additional interface is prevented connecting the low pressure area of the vacuum pump with the environment which may cause leakage. In particular, the at least one heat spreading element may end before the intersection by a distance of less than 1mm, preferably less than 5mm and more preferably less than 10mm. Preferably, the at least one heat spreading element extends beyond the upper side and / or lower side of the housing element. Hence, the at least one heat spreading element extends from the upper side and / or the lower side. Thus, the at least one heat spreading element may be in direct contact with the environment surrounding the housing element of the vacuum pump housing in order to efficiently dissipate heat away from the intermediate section. Preferably, a cooling element is attached to the upper side and / or the lower side of the housing element. The cooling element may be a passive cooling element such as cooling fins or the like. Alternatively, the cooling element is an actively cooled cooling element for example comprising channels through which a coolant can flow to cool the housing element. Therein, the at least one heat spreading element is in direct with one of the cooling elements. In particular, if the at least one heat spreading element extends above the upper side and / or lower side of the housing element, the at least one heat spreading element may extend into one of the cooling elements increasing the contact surface between the at least one heat spreading element and the cooling element. Thus, improved thermal contact between the at least one heat spreading element and the cooling element is achieved and heat from the intermediate section can be directly transferred and dissipated via the cooling element. Preferably, a cross-section of the at least one heat spreading element is round, rectangular, oval or elliptic. By a rectangular or oval or elliptic cross-section an increased cross-sectional area can be achieved. By a round cross-section the respective recess in the chamber wall can be easily manufactured by drilling. Therein, if more than one heat spreading element is implemented, all heat spreading elements may have the same cross-sectional shape or at least two of the heat spreading elements may be different. Thus, by different cross-sections, tailored heat conduction can be achieved leading a homogeneous temperature distribution within the intermediate section. Preferably, more than one heat spreading element is implemented. In particular, one heat spreading element may be implemented in the first section and another one may be implemented in the second section. In addition, one or more heat spreading elements may be implemented in the first section and / or one or more heat spreading elements may be implemented in the second section. If the housing element is built as one part without a first section and a second section one or more heat spreading elements may be arranged in the respective chamber wall extending from the intermediate section towards the upper side and / or the lower side. Preferably, at least one of the pump chambers are at least partially surrounded by connecting channels, wherein by the connecting channels subsequent pump chambers are connected such that a gaseous medium can flow sequentially through all pump chambers. Consequently, the pump chambers are separated from an outer surface of the vacuum pump housing by the connecting channels. Thereby heat dissipation via the outer surface from the intermediate section is further reduced. In this case the at least one heat spreading element provides an effective way in order to reduce the temperature of the intermediate section. Preferably, in more than one chamber wall at least one heat spreading element is arranged. Therein, the heat spreading elements in each of the chamber walls may be formed identical of differently. In particular, in all chamber walls at least one heat spreading element is arranged. In other words, a heat spreading element may be arranged in one or more and preferably all chamber walls and in particular in one or more and preferably all internal chamber walls which do not form an outer surface of the vacuum pump. Therein, internal chamber walls are chamber walls separating two pump chambers and not only adjacent to a single pump chamber. In another aspect of the present invention a vacuum pump is provided. The vacuum pump comprises a vacuum pump housing as described before. In addition, the vacuum pump comprises at least one rotor assembly having a shaft extending through the openings in the chamber walls. Rotor elements connected to the shaft are arranged in the respective pump chambers. In particular, the vacuum pump is a 2-shaft vacuum pump such that the vacuum pump comprises two rotor assemblies and in each pump chamber two rotor elements of different rotor assemblies are arranged and acting together in order to convey a gaseous medium from an inlet of the vacuum pump housing towards the outlet. In particular, the vacuum pump is a roots pump, a claw pump or the like. In the following the present invention is described in more detail with reference to the accompanying figures. The figures show: Figure 1 a schematic drawing of a vacuum pump housing accord ing to the present invention, Figure 2 a detailed view of a first section of the vacuum pump housing according to the present invention, Figures 3A-3G different embodiments of the vacuum pump housing ac cording to the present invention in a section view and Figures 4A-4G corresponding top views of the embodiments of Figures 3A-3G. The vacuum pump housing 100 according to the present invention shown in Figure 1 shows a housing element 10. Therein, the housing element 10 comprises a first section 12 and a second section 14. The housing element 10 comprises an upper side 11 which is formed by the first section 10. Further, the housing element 10 has a lower side 13 opposite to the upper side 11 which is formed by the second section 14. Therein, the terms "lower" and "upper" shall not be construed as limiting and therefore, the present invention is not limited to a specific orientation of the vacuum pump housing. The terms "upper" and "lower" are only used for simplicity and with reference to the figures without limitation of the invention. In particular, the vacuum pump housing 100 of the present invention is a multistage 2-shaft vacuum pump. The housing element comprises a plurality of chamber walls 31 (see Figure 2) defining a plurality of pump chambers 20 (indicated by the dash lines in Figure 1). Further, a first opening 16 and a second opening 18 is formed by the housing element 10 in at least one of the chamber wails 31 such that a shaft can extend through the first opening 16 or the second opening 18 from one pump chamber 20 to an adjacent pump chamber 20. Therein, according to the embodiment of Figure 1, the opening 16 and the second opening 18 are partially formed by the first section 12 and the second section 14. Therein, a recess in the form of a semicircle is formed within the first section 12 and a corresponding recess is formed in the second section 14. Upon assembly of the first section 12 with the second section 14, the first section 12 and the second section 14 forming the first opening 16 and the second opening 18. Therein, the first section 12 and the second section 14 are contacting each other at an intersection 15. Between the first opening 16 and the second opening 18 an intermediate section 26 of the chamber wall 31 is formed. Therein, the intermediate section 26 of the chamber wall 31 is formed by a first intermediate part 22 of the first section 12 and a corresponding second intermediate part 24 of the second section 14. The first intermediate part 22 and the second intermediate part 24 are in contact along the intersection 15 and together form the intermediate section 26 of the housing element 10. Upon operation of the vacuum pump the temperature in the intermediate section 26 increases since heat dissipation away from the intermediate section 26 is reduced due to the reduced cross section towards the outer surfaces of the housing element 10. In Figure 2 it is shown that the housing element 10 may form a plurality of pump chambers 20 limited by respective chamber walls 31. In Figure 2 only the first section 12 is shown for simplicity. Each chamber wall 31 is substantially identically forming the first opening 16 and second opening 18 such that the respective pump shafts can extend from one pump chamber 20 to an adjacent pump chamber 20. For assembly of the housing element 10, the first section 12 is connected to the second section 14 for example by bolts or the like. Therein, as shown in Figure 1, a first cooling element 28 may be connected to the upper side 11 of the housing element 10. A second cooling element 30 may be additionally or alternatively connected to the lower side 13 of the housing element 10. These cooling elements are not shown in Figure 2 for simplicity. By the multiple pump chambers 20 a multi-stage vacuum pump is formed. Therein, a gaseous medium may enter the vacuum pump housing via an inlet (not shown) and may subsequently flow through each of the pump chambers 20 consecutively towards an outlet of the vacuum pump housing (not shown). The gaseous medium is more and more compressed towards the outlet by rotor elements connected to the shafts extending through each of the pump chambers 20 via the respective chamber walls 31 and rotated synchronously to each other. In particular, the vacuum pump may be a roots pump, a claw pump or the like. Therein, in the embodiments as shown in the figures, connecting channels 36, 36' arranged outside, i. e. around the pump chambers 20. Via the connecting channels 36, 36' individual pump chambers 20are connected to each other such that the gaseous medium can flow from one pump chamber 20 to the next. However, by the connecting channels 36, 36’ surrounding the pump chambers 20 heat dissipation away from the intermediate section 26 is further reduced. In order to efficiently dissipate heat from the intermediate section 26, heat spreading elements 34 are arranged in one or more of the chamber walls 31 and extending from the intermediate section 26 towards the upper side 11 and / or the lower side 13. In particular, the heat spreading element 34 may extend from close to the intersection 15 (but distant from the intersection) completely up to the upper side 11 or close to the upper side 11 as described in more detail below. Alternatively or additionally a heat spreading element 34 may extend from the intersection 15 completely to the lower side 13 or in the vicinity of the lower side 13 as described in more detail below. Further, the heat spreading elements 34 are made from a material having an increased or improved heat conductance which is higher than the heat conductance of the material of the housing element 10 is made from. Therein, the housing element 10 may be made from cast iron or stainless steel. The heat spreading element 34 may be made from copper or aluminum Therein, it is shown in the figures that the heat spreading element 34 may not be exposed to the interior of one of the pump chambers 20 and thus it is not exposed to any corrosive substances contained in the gaseous medium. By the heat spreading element 34, heat which would otherwise accumulate in the area of the intermediate section 26 can effectively dissipated towards the upper side 11 and / or the lower side 13, In particular, if a first cooling element 28 is connected to the upper side 11 of the housing element 10 and / or a second cooling element 30 is connected to the lower side 13 of the housing element 10, heat from the intermediate section 26 can be conducted towards the first cooling element 28 and / or the second cooling element 30. Thus, the temperature of the intermediate section can be reduced and higher compression ratios can be achieved without overheating of the vacuum pump. Therein, the heat spreading element 34 may have any form and may be round, rectangular, oval or elliptic. Figures 3A-3G show sectional views as indicated in Figure 2 of a respective chamber wall 31. Correspondingly, Figures 4A-4G show top views of the respective chamber wall 31 seen from the intersection 15 as exemplarily indicated in Figure 3A. Therein, the embodiments of Figures 3A-3G and, correspondingly. Figures 4A-4G may show a first section 12 or may show a second section 14. Therein, first section 12 and second section 14 may be shaped identically or differently. Also, the heat spreading element 34 in different chamber walls 31 may be shaped identically or differently. Figures 3A and 4A show the embodiment according to Figure 2A, Therein, the heat spreading element 34 has a rectangular shape extending along the full length of the first section 12 or second section 14 from the intersection 15 towards the upper side 11 and / or the lower side 13. In the embodiment of Figures 3B and 4B the upper end 38 of the heat spreading element 34 ends prior to the intersection 15 such that a distance between the upper end 38 and the intersection 15 occurs. In other words, the heat spreading element 34 is arranged in a blind hole accessible from the upper side 11 or the lower side 13, respectively. Consequently, interfaces connecting the low pres-sure / high vacuum area and environment are reduced since there is no connecting interface in the embodiment of Figures 3B and 4B. Thereby leakage is reduced. In the embodiment of Figures 3C and 4C more than one heat spreading element 34 is provided including three heat conducting rods 40, 40', 40" extending from the intersection 15 towards the upper side 11 or lower side 13, respectively. The heat conducting rods 40, 40', 40" come into contact with the respective other section at the interface 15. If the first section 12 and the section 14 are identical in terms of the heat spreading element 34, heat conducting rods are extending from the lower surface 13 to the upper surface 11 improving heat conductance away from the intermediate section 26. Therein, the heat conducting rods 40, 40', 40" may be separated at the intersection 15 and in direct with the heat conducting rods of the other section. In the embodiment of Figures 3C and 4C the heat conducting rods 40, 40', 40" extend beyond the intersection 15. Hence, the heat conducting rods 40, 40', 40" may extend into the other section by a first protruding part 42. Hence, by the first protruding part 42 formed by the heat conducting rods 40, 40', 40" the heat spreading element 34 is connected to the heat spreading element 34 of the other section in an interlocking manner. Therein, it is shown in Figure 3D that all three heat conducting rods 40, 40', 40" extend beyond the intersection 15 in particular by the same amount. Of course, the invention is not limited hereto and the first protruding part 42 of each conducting rod 40, 40',40" may be different. At least one or more of the heat conducting rods 40, 40', 40" may extend beyond the intersection 15 of the first section 12 or second section 14, In the embodiment of figures 3E and 4E the heat conducting rods 40, 40', 40" extend beyond the upper surface 11 or the lower surface 13, respectively, by a second protruding part 44. Therein, the second protruding part 44 of the heat conducting rods 40, 40', 40" may extend into the first cooling element 28 when arranged at the upper side 11, or into the second cooling element 30 when arranged at the lower side 13. Thereby, improved heat transfer from the heat spreading element 34 towards the first cooling element 28 and / or the second cooling element 30 is facilitated to efficiently dissipate heat from the intermediate section 26 away towards the cooling elements 28, 30. In the embodiment of figures 3F and 4F the heat conducting rods 40, 40', 40" extend by a first protruding part 42 as described before with respect to the embodiments of figures 3D and 4D and also extend by a second protruding part 44 as described before with respect to the embodiment of Figures 3E and 4E. In the embodiment of Figures 3G and 4G, the heat conducting rods 40, 40', 40" may not extend up to the intersection 15 but may form a recess 46 in the respective chamber wall 31. The recess 46 is formed in order to receive a corresponding heat conduction rod 40, 40', 40" from the other section upon assembly of the first section 12 with the second section 14. Although shown in the Figures 3C-3G and 4C to 4G, the heat spreading element 34 is provided by three heat conducting rods 40, 40', 40". However, the present invention is not limited to the number of heat conducting rods such that more than three and less than three can also be implemented in a single chamber wail and are encompassed by the present invention. Further, the heat conducting rods 40, 40', 40" of the embodiments of the Figures 3C-3G and 4C-4G are shown to have a round cross section. The present invention is not limited to this specific shape and also squared, rectangular, oval or elliptic cross-sectional area of each of the heat conducting rods 40, 40', 40" would be possible. Hence, the temperature of the intermediate section 26 in particular of a multistage 2-shaft vacuum pump can be effectively reduced by up to 20K, decreasing thermal load of the vacuum pump housing and at the same time reducing degradation of the shaft seals located in the chamber wall, as well as reducing thermal stress. Reference List 10 housing element 11 upper side 12 first section 13 lower side 14 second section 15 intersection 16 first opening 18 second section 20 pump chamber 22 first intermediate part 24 second intermediate part 26 intermediate section 28 first cooling element 30 second cooiing element 31 chamber wall 34 heat spreading element 36, 36' connecting channel 38 upper end 40, 40', 40' heat conducting rods 42 first protruding part 44 second protruding part 46 recess 100 vacuum pump housing

Claims

1. Vacuum pump housing, in particular for a multistage 2-shaft vacuum pump, comprising:a housing element having an upper side and an opposite lower side,a plurality of chamber walls defining at least one pump chamber configured to receive at least one rotor element connected to one of the pump shafts, wherein the chamber walls extend at least partially between the upper side and the lower side of the housing element,wherein at least one chamber wall comprises openings through the chamber wall, wherein the openings are separated by an intermediate section of the chamber wall,wherein at least one heat spreading element extends from the intermediate section towards the upper side and / or lower side.

2. Vacuum pump housing according to claim 1, wherein the at least one heat spreading element extends in a direction substantially perpendicular to the shafts.

3. Vacuum pump housing according to claim 1 or 2, wherein the at least one heat spreading element is made of a material having a heat conductance higher than the heat conductance of the material of the chamber wall.

4. Vacuum pump housing according to any of claims 1 to 3, wherein the housing element comprises a first section and a second section, wherein the at least one chamber wall is separated by the first section and second section at an intersection, and wherein a first intermediate part of first section isin direct contact with a second intermediate part of the second section, wherein the first intermediate part and the second intermediate part form the intermediate section of the at least one chamber wall, wherein the at least one heat spreading element is arranged within the first intermediate part and / or second intermediate part.

5. Vacuum pump housing according to claim 4, wherein the at least one heat spreading element extends from the first section at least partially into the second section and / or the at least one heat spreading element extends from the second section at ieast partially into the first section.

6. Vacuum pump housing according to claim 4, wherein the at least one heat spreading element of the first section is contacting the at least one heat spreading element of the second section at the intersection of the first section and the second section.

7. Vacuum pump housing according to claim 4, wherein the at least one heatspreading element of the first section and / or the at least one heat element of the second section end in a distance from the intersection of the first section and the second section.

8. Vacuum pump housing according to any of claims 1 to 7, wherein the at least one heat spreading element extends beyond the upper side and / or lower side of the housing element.

9. Vacuum pump housing according to any of claims 1 to 8, wherein a cooling element is attached to the upper side and / or lower side of the housing element, wherein the at least one heat spreading element is in direct contact with at least one of the cooling elements.

10. Vacuum pump housing according to any of claims 1 to 9, wherein a cross section of the at least one heat spreading element is round, rectangular, oval, or elliptic.

11. Vacuum pump housing according to any of claims 1 to 10, comprising more than one heat spreading element.12, Vacuum pump housing according to any of claims 1 to 11, wherein at least one of the pump chambers are at least partially surrounded by connecting channels, connecting subsequent pump chambers.

13. Vacuum pump comprising a vacuum pump housing according to any of claims 1 to 12 and a rotor assembly, wherein the rotor assembly comprises at least two shafts rotated synchronously, wherein at least one rotor element is attached to each shaft and arranged in one of the chambers.

Images