Pump stand for vacuum pump

Abstract

To prevent vibrations originating from a vacuum pump, particularly a spare vacuum pump, from being transmitted to a pump stand in a vacuum pump stand, and similarly to prevent external impact from being transmitted to the vacuum pump, particularly the spare vacuum pump, of the pump stand.SOLUTION: A pump stand 10 has a base element 22. The base element 22 is provided with a bearing unit for vibrationally separating a vacuum pump 14 from the pump stand. The bearing unit has a carrier element 16 for at least indirectly supporting the vacuum pump, at least one spring element 20, a mounting element 24 having a shaft part 26, and a spacer sleeve 32.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pump stand for a vacuum pump, in particular for a diaphragm vacuum pump. [Background technology]

[0002] A vacuum pump stand is used to accommodate a number of vacuum pumps, which are connected to one another in terms of flow, in particular in series, and thus complement each other in terms of the pressure stages that can be achieved. For example, a vacuum pump stand may have a diaphragm vacuum pump as the auxiliary vacuum pump and a turbomolecular pump as the high vacuum pump. In this case, if the diaphragm vacuum pump is rigidly attached to the pump stand for accommodating the diaphragm vacuum pump or to a base element of the pump stand, vibrations emanating from the diaphragm vacuum pump may possibly be transmitted in an undesirable manner to the turbomolecular vacuum pump during operation of the diaphragm vacuum pump, which may cause malfunctions of the turbomolecular pump.

[0003] Furthermore, during transport of the pump stand, shocks resulting from the transport can be transmitted to the pre-vacuum pump, e.g. configured as a diaphragm vacuum pump or as a rotary vane pump, if the pre-vacuum pump is rigidly attached to the pump stand, which can result in damage to the pre-vacuum pump. Summary of the Invention [Problem to be solved by the invention]

[0004] The problem underlying the invention is therefore to ensure that in a vacuum pump stand, vibrations originating from the vacuum pump, in particular the spare vacuum pump, are not transmitted to the pump stand, and likewise that external shocks cannot be transmitted to the vacuum pump, in particular the spare vacuum pump, of the pump stand. Furthermore, an additional transport lock for the vacuum pump should not be necessary, which would otherwise have to be released explicitly when starting up the pump stand. [Means for solving the problem]

[0005] This problem is solved by a pump stand having the features of claim 1, in particular in that the pump stand has at least one bearing unit, via which vibration-technical decoupling of the vacuum pump from the pump stand can be achieved.

[0006] The bearing unit in this case has a carrier element supporting the vacuum pump, which can be, for example, a flat plate or one or more bending beams supporting the vacuum pump. Furthermore, the bearing unit has at least one spring element, for example in the form of a compression coil spring, via which the carrier element is spring-resilient supported on the base element of the pump stand, for which the spring element extends between the opposing sides of the carrier element and the base element. If the carrier element is, for example, a rectangular carrier plate, the carrier plate can be spring-resilient supported at its four corners on the base element of the pump stand via the spring elements present therein.

[0007] In order to hold the carrier element on the base element so as not to get lost and to secure it against lifting forces during transportation of the pump stand, the support unit further has at least one mounting element, for example in the form of a screw with an axial portion, which extends through the spring element and by means of which the carrier element is fastened to the base element, in particular in which case it can be envisaged that the carrier element is fastened to the base element by means of the mounting element against the preload of the spring element.

[0008] Since at least one spring element should not exert a preload or force on the carrier element in the unloaded state of the support unit, thereby allowing all mounting elements (via which the carrier elements are supported on the base element of the pump stand) to be tightened with the same strength, the support unit further has a spacer sleeve, which is surrounded by the spring element and which itself surrounds the shaft of the mounting element over its extension length which extends as a result of tightening between the base element and the carrier element.

[0009] The shank of the mounting element, the spacer sleeve and the spring element are therefore arranged essentially concentrically with one another, the spacer sleeve having an extension length which corresponds to the clamping length of the mounting element and thus to the length of the shank which extends as a result of the clamping of the carrier element with the base element. In other words, the length of the spacer sleeve corresponds to the part of the shank which extends as a result of the clamping of the carrier element with the base element. For this purpose, the axial length of the spacer sleeve must be selected such that the shank of the mounting element is already clamped in the unloaded state of the bearing unit. Similarly, the axial length of the spacer sleeve should be adjusted to the axial extension length of the spring element so that the spring element does not exert a force or preload in the unloaded state of the bearing unit, i.e. in the absence of a vacuum pump on the carrier element.

[0010] The spacer sleeve thus sets the mutual distance between the carrier element and the base element in the unloaded state of the bearing unit, which likewise ensures that the spring element does not exert a preload on the unloaded state of the bearing unit, in other words, the mounting element can be tightened up until a predefined distance between the carrier element and the base element is achieved.

[0011] In the following, preferred embodiments of the invention are described, further embodiments may be evident from the dependent claims, the description of the drawings and the drawings themselves.

[0012] Thus, according to one embodiment, at least one guide for the spring element is formed on the carrier element and / or the base element, which can ensure that the spring element is compressed purely axially during operation of the pump. Possible lateral displacements of the spring element can thus be prevented by the guide. In turn, such a guide serves as a position fixation for the spring element, so that the spring element retains its concentric position relative to the mounting element and the spacer sleeve surrounding the shank of the mounting element. This prevents the spring element from coming into contact with the spacer sleeve, which would otherwise lead to undesirable rattling noises during operation of the vacuum pump.

[0013] According to one embodiment, the guide referred to here may for example be a dome formed on the base element and / or the carrier element, which is surrounded by the spring element and on which the respective ends of the spacer sleeve contact, in which case it may be envisaged in particular that the end of the shank of the mounting element is screwed into the dome, so that a hollow space with a corresponding internal thread may be formed in the dome.

[0014] Since the spring element surrounds the dome, thereby fixing the radial positioning of the spring element relative to the spacer sleeve standing on the dome, the spring element desirably does not contact the spacer sleeve, which could otherwise cause undesirable rattle noise.

[0015] Additionally or alternatively to the above-mentioned embodiment, the guides may be recesses in the form of blind holes formed in the base element and / or the carrier element, which recesses receive the respective ends of the spring elements, again preventing misalignment of the spring elements with respect to the spacer sleeve and thus preventing undesirable rattle noises that may otherwise occur when the spring elements abut against the spacer sleeve.

[0016] According to yet another embodiment, a dome is formed on the base element for guiding the spacer sleeve, the dome being surrounded by the spring element and on which one end of the spacer sleeve stands, while a corresponding recess is formed in the carrier element, which receives the other end of the spring element. However, alternatively, the dome can also be formed in the carrier element and the recess in the base element.

[0017] According to yet another embodiment, it may be provided that the spacer sleeve is manufactured from a plastic material, since this ensures that even if contact occurs between the spring element and the spacer element when the vibrations do not proceed strictly axially, this does not cause undesirable rattle noises. Similarly, the spacer sleeve is constructed from a plastic material, which prevents undesirable rattle noises due to contact between the spacer sleeve and the shank of the mounting element and the carrier element. The construction of the spacer sleeve from a plastic material proves to be advantageous when no guide for the spring element is provided, since in this case undesirable rattle noises are prevented even if the spring element and the spacer sleeve come into contact.

[0018] As already briefly mentioned above, the carrier element can be, for example, a carrier plate on which a vacuum pump can be mounted. Alternatively to this, according to another embodiment, the carrier element has at least one bending beam, which is supported at one end on the base element, respectively via a spring element, and the shank of the spring element, which extends through the spacer sleeve, is fastened to the base element by a mounting element. The bending beam is therefore supported at both ends by the bearing units as described above, so that the bending beam forms a simple beam in a static sense. Preferably, the carrier element has two such bending beams which extend approximately parallel to each other. In this case, a vacuum pump can be mounted on the two bending beams, which bridge the gap between the two bending beams. The two bending beams are therefore separated from each other in vibration technology, so that the deflection of one bending beam has no effect on the deflection of the other bending beam and vice versa.

[0019] For example, in order to ensure that even very large displacements of the spring elements are not transmitted to the pump stand, according to a preferred embodiment it can be envisaged that each spring element of each support unit has a spring constant selected to a value such that the spring elements do not come into contact with each other during operation of the vacuum pump.

[0020] In order to provide vibration-technical isolation between the vacuum pump and the pump stand both in the vertical and horizontal directions, according to another embodiment it can further be envisaged that the pump stand has at least two bearing units, the spring elements, spacer sleeves and mounting elements of the bearing units being oriented perpendicular to one another.

[0021] The invention will now be described, by way of example only, with reference to the drawings in which: [Brief description of the drawings]

[0022] [Figure 1] 1 shows a part of a pump stand according to the invention from one observation direction. [Diagram 2]1 shows a first embodiment of a bearing unit according to the invention; [Diagram 3] 2 shows a second embodiment of a bearing unit according to the invention. [Figure 4] 3 shows a third embodiment of a bearing unit according to the invention. [Diagram 5] 4 shows a fourth embodiment of a bearing unit according to the invention. [Figure 6] 1 shows an embodiment having two bearing units oriented perpendicular to each other. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Figure 1 shows a part of a pump stand 10 according to the invention from one viewing direction. In particular, Figure 1 shows a part of a housing 12 of the pump stand 10. In the housing 12 a pre-vacuum pump 14 in the form of a diaphragm vacuum pump is accommodated. A high vacuum pump, for example in the form of a turbomolecular pump, supported by the pump stand 10, in particular by the housing 12 of the pump stand 10, is not shown. The high vacuum pump is connected upstream of the pre-vacuum pump 14 in the flow direction.

[0024] As can be seen from Fig. 1, the auxiliary vacuum pump 14 is located on a carrier element 16, which may be a carrier plate on which the auxiliary vacuum pump 14 stands. Alternatively to this, the carrier element 16 may have two bending beams 18 extending parallel to one another and spaced apart perpendicularly to the drawing plane, on which the auxiliary vacuum pump 14 is mounted so as to bridge the gap between the two bending beams 18.

[0025] As can already be seen from FIG. 1, each bending beam 18 is elastically supported at both ends by spring elements 20 on a base element 22 of the housing 12, thereby preventing vibrations caused by the operation of the pre-vacuum pump 14 from being transmitted to the housing 12 and from there to a turbomolecular vacuum pump (not shown) supported in the housing 12.

[0026] As can be seen from the enlarged view of Fig. 2, the carrier element 16 or the bending beam 18 is supported on the base element 22 via a spring element 20 in the form of a compression coil spring 20, which extends between two mutually facing faces of the carrier element 16 and the base element 22. In order to be able to secure the carrier element 16 or the bending beam 18 against lifting forces during transportation of the pump stand 10, the carrier element 16 is fastened to the base element 22 by means of a fastening element 24 in the form of a bolt 24, the shank 26 of the bolt 24 extending through the compression coil spring 20. To fasten the carrier element 16 to the base element 22, the free end of the shank 26 of the bolt 24 can be screwed into an internal thread formed in the base element 22 or into a nut located below and against the base element 22. In the illustrated embodiment, on the other hand, the screw head 28 rests against the upper side of the carrier element 16 via a washer 30, so that the carrier element 16 is secured to the base element 22 against lifting forces. However, the washer 30 is not necessarily required if the hole 34 in the carrier element 16 is too small for the screw head 28 to pass through or if flange-head screws are used. The mounting element 24 thus provides a transport lock, which prevents the carrier element 16 from bouncing off the spring element 20 during transport of the pump stand 10. A separate transport lock is therefore not required, with which the carrier element 16 can be fastened to the base element 22 for transport until the spring element 20 is in close contact. In the case of such a separate transport lock, it may happen that the release of the transport lock is forgotten after transport, which would lead to undesirable vibration transmission to the high vacuum pump during operation. The mounting element 24 of the bearing unit according to the invention therefore does not need to be removed after transport of the pump stand 10, so that a transport lock that is not prone to misuse is provided.

[0027] Since the preload starting from the spring element 20 is greater the more the carrier element 16 is clamped to the base element 22 by the mounting element 24, the shank 26 of the mounting element 24 is surrounded by a spacer sleeve 32. The spacer sleeve 32 may preferably be manufactured from a plastic material. In this case, in particular, the spacer sleeve 32 extends between the underside of the washer 30 and the side of the base element 22 facing the carrier element 16. In particular, the spacer sleeve 32 extends through an opening 34 formed in the carrier element 16, through which the shank 26 of the mounting element 24 also extends. The axial extension of the spacer sleeve 32 thus sets the maximum distance between the carrier element 16 and the base element 22. This ensures that the mounting element 24 can be clamped exactly until the spring element 20 exerts a pre-determined amount of preload force.

[0028] The axial extension of the spacer sleeve 32 thus sets the stressed length of the threaded shank 26, since the spacer sleeve 32 extends between the underside of the washer 30 and the side of the base element 22 facing the carrier element 16. The stressed length of the threaded shank is usually called the clamping length, which in technical mechanics means the thickness of the parts to be joined, including any washers present.

[0029] In this case, the axial length of the spacer sleeve 32 should be selected such that in the unloaded state of the bearing unit, when the pump has not yet been placed on the carrier element 16, the spring element 20 exerts no preload and therefore the shank 26 of the mounting element 24 is clamped exclusively by the clamping moment of the mounting element 24. In contrast, the spring constant of the spring element 20 should be selected such that the spring element 20 does not come into contact with the support even during operation of the auxiliary vacuum pump mounted on the carrier element 16.

[0030] As mentioned above, it is recommended to manufacture the spacer sleeve 32 from a plastic material, since this ensures that no undesirable rattle noises occur when the spring element 20 comes into contact with the spacer sleeve 32.

[0031] However, in order to be able to preclude such contact between the spring element 20 and the spacer sleeve 32 from the outset, the embodiment shown in Fig. 3 envisages that the carrier element 16 is formed on its side facing the base element 22 with a hollow cylindrical recess 36 which receives the corresponding end of the spring element 20 and is coaxially aligned with the opening 34 in the carrier element 16. The spring element 20 is thus held radially in the recess 36, so that the coaxial arrangement of the spring element 20, the spacer sleeve 32 and the mounting element 24 is permanently maintained.

[0032] As an alternative to the embodiment shown in Fig. 3, the embodiment shown in Fig. 4 provides that the base element 22 is provided on its side facing the carrier element 16 with a dome 38 in the form of a hollow cylindrical protuberance, the compression spring 20 then surrounding the dome 38, so that it is held in place radially. Furthermore, in the embodiment shown in Fig. 4, the lower end of the spacer sleeve 32, again made of plastic material, stands on the dome 38. This means that the length of the stem 26 of the mounting element 24, which is expanded as a result of the tightening of the carrier element 20 with the base element 22, and the axial extension height of the dome 38 are smaller than in the embodiment of Fig. 2.

[0033] In the embodiment of FIG. 4, the dome 38 is provided with an internal thread (not shown) into which the free end of the shank 26 is screwed, whereas, alternatively, the dome 38 may only define a through opening through which the shank 26 extends, in which case a nut may be provided below the base element 22 or above the carrier element 16 which abuts against the base element 22 or the carrier element 16 and into which the free end of the shank 26 is screwed.

[0034] The embodiment of Figure 5 is in some way a combination of the embodiment of Figure 3 and the embodiment of Figure 4, since according to the embodiment of Figure 5 the base element 22 is formed with a dome 38 and the carrier element 16 is formed with a recess 36 for securing the respective spring end.

[0035] The aforementioned bearing unit therefore makes it possible to provide a vibration-technical decoupling between the vacuum pump 14 and the pump stand 10 in the vertical direction. But in order that horizontal pump vibrations can also be suppressed or at least damped, according to the embodiment shown in Fig. 6, the carrier element 16 is a bent beam 18 with an angled cross section, with a vertical angle leg 40 secured to the vertical base element part 22' in a manner corresponding to the horizontal angle leg for the bearing unit consisting of the spring element 20, the spacer sleeve 32 and the mounting element 24. [Explanation of symbols]

[0036] 10 Pump Stand 12. Housing 14 Auxiliary Vacuum Pump 16 Career Elements 18 Bending beam 20 Spring elements 22 Base Elements 22' Base element part 24 Mounting elements / threaded bolts 26 Shaft 28 Screw head 30 Washer 32 Spacer sleeve 34 Aperture 36 Recess 38 Dome 40 Vertical angle leg 42 Horizontal angle leg

Claims

1. A pump stand (10) for a vacuum pump (14), in particular an auxiliary vacuum pump, comprising: the pump stand (10) has a base element (22) on which a bearing unit is provided for vibrationally isolating a vacuum pump (14), in particular an auxiliary vacuum pump, from the pump stand (10), The support unit includes: a carrier element (16) for at least indirectly supporting the vacuum pump (14); at least one spring element (20), via which the carrier element (16) is supported on the base element (22), so that the spring element (20) extends between the opposing sides of the carrier element (16) and the base element (22); a mounting element (24), in particular in the form of a screw, having a shaft (26), by means of which the carrier element (16) is fastened to the base element (22); a spacer sleeve (32) surrounded by the spring element (20) and itself surrounding the shaft portion (26) of the mounting element (24) over an extension length that extends as a result of the tightening of the base element (22) and the carrier element (16); A pump stand (10).

2. 2. A pump stand (10) as described in claim 1, wherein the axial length of the spacer sleeve (32) is selected to be such that, in the unloaded state of the bearing unit, the shaft portion (26) of the mounting element (24) is clamped solely based on the clamping moment of the mounting element (24).

3. 3. The pump stand (10) according to claim 1 or 2, wherein the spring element (20) is only subjected to the load of the carrier element (16) in the unloaded state of the bearing unit.

4. The pump stand (10) according to any one of claims 1 to 3, wherein the spring element (20) is a compression coil spring (20).

5. 5. The pump stand (10) according to any one of the preceding claims, wherein the carrier element (16) and / or the base element (22) are formed with at least one guide for the spring element (20).

6. the guide being a dome (38) formed on the base element (22) and / or the carrier element (16), the dome (38) being surrounded by the spring element (20) and on which the end of the spacer sleeve (32) stands, A pump stand (10) according to claim 5, in particular, in which it is envisaged that the stem (26) of the mounting element (24) is screwed into the dome (38).

7. 6. A pump stand (10) as claimed in claim 5, wherein the guide is a recess (36) formed in the base element (22) and / or the carrier element (16), the recess (36) accommodating each end of the spring element (20).

8. The pump stand (10) according to any one of the preceding claims, wherein the spacer sleeve (32) is made from a plastic material.

9. 9. The pump stand (10) according to claim 1, wherein the carrier element (16) has at least one bending beam (18), which is supported at a plurality of ends on the base element (22) via one of the spring elements (20) in each case and is fastened to the base element (22) by means of a mounting element (24), the shaft portion (26) of which extends through the spacer sleeve (32).

10. 10. The pump stand (10) according to claim 9, wherein the carrier element (16) has two bending beams (18) extending parallel to each other.

11. 11. The pump stand (10) according to claim 10, wherein a vacuum pump (14), in particular a diaphragm vacuum pump (14) or a rotary vane pump, is mounted on the two bending beams (18) bridging the gap between the two bending beams (18).

12. 12. The pump stand (10) of claim 1, wherein the spring element (20) has a spring constant selected such that the spring element (20) does not seal during operation of the vacuum pump (14).

13. The pump stand (10) according to any one of claims 1 to 12, wherein the pump stand (10) has at least two bearing units, the spring elements, the spacer sleeves (32) and the mounting elements (24) of which are oriented perpendicular to each other.

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