Abstract
A retaining device for an impeller of a centrifugal pump, including: a pump shaft with a recess formed substantially parallel to the axis of rotation of the pump shaft; a fastening bolt, which is insertable into the recess such that a first channel is defined between the inserted fastening bolt and the pump shaft and which is connected to the pump shaft on one end thereof and provides a retainer for fixing the impeller on the other end thereof; wherein the pump shaft includes at least one further channel extending from the circumferential surface of the pump shaft up to and into the recess and allowing the first channel to be emptied.
Claims
1. A retaining device for an impeller of a centrifugal pump, comprising: a pump shaft with an opening formed substantially parallel to an axis of rotation of the pump shaft; a fastening bolt insertable into the opening such that a channel is defined between the inserted fastening bolt and the opening of the pump shaft, wherein the fastening bolt is connected to the pump shaft on one end thereof and provides a retainer for fixing the impeller on an other end thereof, wherein the pump shaft comprises at least one further channel extending from a circumferential surface of the pump shaft up to and into a recess and allowing the channel defined between the inserted fastening bolt and the opening of the pump shaft to be emptied.
2. The retaining device according to claim 1, wherein the fastening bolt is a threaded bolt having a thread on at least one of its ends.
3. The retaining device according to claim 1, wherein the retainer is provided with a thread and bracing is accomplished by screwing.
4. The retaining device according to claim 1, wherein the fastening bolt is insertable into and removable from a bore from at least one end of the pump shaft.
5. The retaining device according to claim 1, wherein the opening formed substantially parallel to the axis of rotation of the pump shaft extends through a length of the pump shaft.
6. The retaining device according to claim 1, wherein the opening formed substantially parallel to the axis of rotation of the pump shaft does not extend through a length of the pump shaft.
7. A centrifugal pump for use in plants for producing foodstuff, cosmetics and pharmaceutical products, comprising: a pump casing; an impeller with impeller blades for feeding a medium in the pump casing; and a retaining device comprising: a pump shaft with an opening formed substantially parallel to an axis of rotation of the pump shaft; a fastening bolt insertable into the opening such that a channel is defined between the inserted fastening bolt and the opening of the pump shaft, wherein the fastening bolt is connected to the pump shaft on one end thereof and provides a retainer for fixing the impeller on an other end thereof, and wherein the pump shaft comprises at least one further channel extending from a circumferential surface of the pump shaft up to and into a recess and allowing the channel defined between the inserted fastening bolt and the opening of the pump shaft to be emptied.
8. The centrifugal pump according to claim 7, wherein, measured along the axis of rotation of the pump shaft, the channel in the pump shaft is longer than a thickness of the impeller and of an area which one or a plurality of mechanical seals on the pump shaft overlap.
9. The centrifugal pump according to claim 7, further comprising one or a plurality of mechanical seals for sealing the pump shaft against the pump casing.
10. The centrifugal pump according to claim 9, wherein an area between the plurality of mechanical seals is configured to be rinsed.
11. The centrifugal pump according to claim 7, wherein the pump shaft is provided with one or a plurality of channels in an area in which the pump casing overlaps the pump shaft, the channels extending from the circumferential surface of the pump shaft up to the opening, which is formed substantially parallel to the axis of rotation of the pump shaft, and allowing access to the channel defined between the inserted fastening bolt and the opening of the pump shaft.
12. The centrifugal pump according to claim 11, wherein the plurality of channels in the area in which the pump casing overlaps the pump shaft allow communication between the channel defined between the inserted fastening bolt and the opening of the pump shaft and an area behind the internal sealing elements.
13. The centrifugal pump according to claim 7, wherein the pump casing and/or the impeller are replaceable.
14. The centrifugal pump according claim 7, wherein the pump shaft is connectable to a motor shaft.
15. The centrifugal pump according to claim 7, wherein the pump shaft is adapted to be braced onto a motor shaft via a clamping element.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0024] In the following, embodiments of the present invention will be described making reference to the figures. The embodiments described are to be regarded as being merely illustrative in all respects and as being non-limiting, and various combinations of the features disclosed are comprised in the present invention.
[0025] FIG. 1A: a schematic view of a centrifugal pump according to an embodiment.
[0026] FIG. 1B: a schematic side view of the centrifugal pump according to FIG. 1A.
[0027] FIG. 2: a schematic side view of a detail of a known centrifugal pump.
[0028] FIG. 3: a schematic view of a detail of FIG. 1B concerning the pump shaft according to an embodiment.
[0029] FIG. 4 a schematic view of a pump with a retaining device according to an embodiment, the embodiment in question having two mechanical seals and the possibility of cleaning the interior of the mechanical seals by flushing them with a liquid.
DETAILED DESCRIPTION
[0030] FIGS. 1-4 show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example. It will be appreciated that one or more components referred to as being “substantially similar and/or identical” differ from one another according to manufacturing tolerances (e.g., within 1-5% deviation).
[0031] FIG. 1A shows a schematic view of a centrifugal pump 100. The centrifugal pump 100 comprises a motor 101 with a motor housing 102. The motor may be mounted on or with a base 103. The motor of the centrifugal pump may drive a motor shaft 1. The motor shaft 1 may be connectable to a pump shaft 2. The pump shaft 2 is connected to an impeller 5. The pump blades of the impeller 5 are not shown in FIG. 1A. In FIG. 1A, the motor shaft 1 and the pump shaft 2 are connected to each other. For the connection, the pump shaft 2 is configured as a hollow shaft at one end thereof. In addition, the motor shaft is configured as a stub shaft. The pump shaft 2 is pushed over the stub shaft of the motor shaft 1. To this end, the stub shaft of the motor shaft 1 and the pump shaft 2 are configured such that the pump shaft 2 surrounds the stub shaft of the motor shaft 1. An overlap area is formed. Over at least part of the overlap area between the pump shaft 2 and the motor shaft 1, a clamping element 3 may be provided (see FIG. 3). The clamping element 3 and the pump shaft 2 typically form a unit. The clamping element encompasses the pump shaft 2 and thus the motor shaft 1. The clamping element 3 creates a very large non-slip connection surface between the motor shaft 1 and the pump shaft 2, thus providing a stable, high concentricity of the pump shaft 2.
[0032] FIG. 1B shows a side view of the centrifugal pump 100 of FIG. 1A. On the right hand side of this FIG. 1B, the motor 101 is shown, at the center of the figure the motor shaft 1 and on the left hand side of the figure the pump shaft 2. In the area of the pump shaft 2, in particular of the impeller 5, an area Z is highlighted. This area Z is shown enlarged in FIG. 3.
[0033] FIG. 2 shows a detail Z′ of a known centrifugal pump 200. The detail Z′ in a known centrifugal pump corresponds approximately to the location of detail Z of FIG. 1B. FIG. 2 shows a pump shaft 202 having a pump impeller 205 with blades 211 attached thereto. The pump shaft 202 would continue to the right and may then be connected to a motor shaft, which is not shown here. The detail Z′ also shows a pump casing 204. FIG. 2 shows seals 215. The seals 215.1, 215.3 seal the parts mounted on the pump shaft, viz. the impeller 205 and the impeller nut 206, against the product area 225, and the seal 215.2 seals the movable part of the mechanical seal against the pump shaft. The seal 215.2 is in particular required for pumps having a mechanical seal capable of being cleaned by flushing with a liquid. The area 225 close to the product in question may also be referred to as product side or end side or suction side. In a purely illustrative area 201, which is drawn by dashed lines without regard to actual size ratios, a dead space may be formed between the pump shaft 202, the pump impeller 205 and the impeller nut 206. This dead space is very difficult to access in the known centrifugal pump 200 and therefore very difficult or impossible to clean in case of ingress of leakage. In addition, leakage occurring in this area cannot be detected from the outside. Furthermore, in this dead space there is the risk that pressure may build up when the temperature changes, and this pressure may return leakages, back into the product and thus lead to recontamination of further product batches.
[0034] FIG. 3 shows the area Z of FIG. 1B in an enlarged representation. FIG. 3 with the area Z shown is comparable to FIG. 2 and the area Z′ shown there. FIG. 3 essentially shows a pump shaft 2. In addition, it shows the pump shaft 2 in relation to a pump casing/pump cover 4, in which the impeller 5 of the centrifugal pump 100 rotates. The impeller 5 may have a number of blades or delivery elements 5.1. The pump shaft 2 is connected to the motor shaft 1. The pump shaft 2 is configured as a hollow shaft. The hollow end, shown here in the drawing on the right and identified by reference numeral 2.1, accommodates the stub shaft of the motor shaft 2. The impeller 5 is driven by the pump shaft 2 connected to the motor shaft 1. The pump shaft 2 is braced onto the motor shaft 2 by means of the clamping element 3.
[0035] FIG. 1B already indicates and FIG. 3 shows in detail that the pump shaft 2 is hollow and has a bolt or rod 17 inside. This bolt may be a fastening bolt. The bolt 17 is oriented along the axis of rotation of the pump shaft 2 and cylinder-symmetric thereto. The bolt 17 comprises two ends, 17.1 and 17.2. One of the ends of the bolt, in the drawing the end 17.2, faces the motor 101, the other one, in the drawing the end 17.1, faces away from the motor 101. The end 17.2 of the bolt is held by a retainer 23 in the motor-side end of the pump shaft bore. The end 17.1 may protrude beyond the pump shaft 2 and receives, by means of a retainer 21, the impeller nut 7 thereon, thus fixing the pump impeller 5 on the pump shaft. In particular, the fastening bolt 17 may be configured as a threaded bolt and the retainers 21 and 23, respectively, may have threads for retaining the bolt 17 by means of the thread. The fastening bolt 17 is thus oriented along the pump shaft 2 so that the center axis of the fastening bolt 17 and of the pump shaft 2 coincide.
[0036] In FIG. 3, it is additionally shown that the fastening bolt 17 extends in a channel 18. The channel 18 is a venting channel. The venting channel 18 has a slightly larger diameter than the fastening bolt 17 and is otherwise formed essentially concentrically around the fastening bolt 17. Similar to FIG. 2, the area 201 is also indicated in this case, again in a purely illustrative manner and not to scale. In the area 201, internal sealing elements, such as the seals 15.1, 15.2 and 15.3, are indicated. In contrast to FIG. 2, the venting channel 18 in FIG. 3 now allows access to the area 201, i.e. to the space that was practically inaccessible in FIG. 2. Hence, the venting channel 18 creates between the pump shaft 2 and the fastening bolt 17 a gap, which makes the area 201 accessible. This gap, i.e. the venting channel 18, can be used to discharge leakage in the event of a partial failure of a sealing element. The leakage can here enter the venting channel 18 on the end side or via one or a plurality of additional channels. Such additional channels are identified by reference numerals 19.2 and 19.3 in FIG. 3. Furthermore, in the bottom of the pump shaft 2, another channel is shown, which is identified by reference numeral 19.1 and through which leakage can exit in the area of the lantern between the pump casing and the motor.
[0037] In other words, FIG. 3 shows a centrifugal pump 100 and a pump shaft 2 for this centrifugal pump 100 with a recess in the pump shaft 2 formed substantially parallel to the axis of rotation of the pump shaft 2. The pump shaft 2 has provided therein a fastening bolt 17. This fastening bolt 17 can be inserted into the recess, so that a channel 18 will be formed between the fastening bolt 17 and the pump shaft 2, when the fastening bolt has been inserted into the bore. This means that, at least in an area of the recess, the channel 18 is equal to a venting gap, when the fastening bolt 17 has been inserted into the bore. The fastening bolt 17 is braced with the pump shaft 2 at one end of the pump shaft making use of a respective retainer 23. At least one channel 19.1 is provided in the pump shaft 2 at at least one end of the recess, the channel starting on the circumferential surface of the pump shaft 2. This channel 19.1 extends up to and into the venting channel 18, so that the channel 18 can be emptied.
[0038] The long clamping length of the threaded connection between the pump shaft 2 and the impeller nut 7 via the fastening bolt 17 increases the safety against loosening of the impeller nut 7 and thus of the impeller 5 from the pump shaft 2. In addition, the leakage channels/venting channels 18 and 19.1, 19.2, 19.3 allow detection of a defect of the internal sealing elements 15.1, 15.2 and 15.3. By venting the interior in the area 201, a pressure build-up in this area is prevented and thus the risk of recontamination in the event of failure of a seal is minimized.
[0039] FIG. 4 shows a detail, comparable to detail Z in FIG. 3, of a pump provided with the retaining device described, but in a version with two mechanical seals 8, 9. Where identical elements are identified, FIG. 4 uses the same reference numerals as FIG. 3. The two mechanical seals 8 and 9 may be alike. Furthermore, there is the possibility of cleaning the inside of the mechanical seals by flushing them with a liquid. For this purpose, a flushing channel 403 is indicated in the figure. In FIG. 4 it can also be seen that the venting channel 18 penetrates the pump impeller 5 and both mechanical seals 8, 9 along the longitudinal axis and is then vented to the outside via the channel 19.1 and through a driver 401.
