Abstract
The invention relates to a magnetically-driven pump (1) with a pump housing (3), a housing cover (4) which closes the pump housing (3), and a containment can (5) which has a metal inner shell (6) and a ceramic outer shell (7) on which a flange (8) is formed. The object of the invention is to devise a pump which is improved in comparison with the prior art, which offers a simple and safe structure and makes uncomplicated and rapid manufacture, assembly and maintenance possible. In particular, a safe and energy-efficient pump is to be devised. To this end, the invention proposes that the inner shell (6) be welded to the housing cover (4) and the outer shell (7) be braced against the housing cover (4) by way of a clamping ring (9) on the flange (8).
Claims
1. Magnetically-driven pump with a pump housing, a housing cover which closes the pump housing, and a containment can which has a metal inner shell and a ceramic outer shell on which a flange is formed, wherein the inner shell is welded to the housing cover and the outer shell is braced against the housing cover by way of a clamping ring on the flange.
2. Magnetically-driven pump according to claim 1, wherein the pump comprises a driver and a rotor between which the containment can is arranged, wherein the rotor is mounted in the containment can by way of a pump bearing, wherein the pump bearing is fastened to the housing cover.
3. Magnetically-driven pump according to claim 2, wherein the pump bearing is fastened to the housing cover by way of a screw connection.
4. Magnetically-driven pump according to claim 1, wherein a flat seal is arranged between the flange of the outer shell and the housing cover.
5. Magnetically-driven pump according to claim 4, wherein the clamping ring exerts a prestress on the flat seal.
6. Magnetically-driven pump according to claim 1, wherein a pressure monitoring line is formed in the housing cover, which line runs in a gap between the inner shell and the outer shell.
7. Magnetically-driven pump according to claim 6, wherein a pressure sensor for monitoring the pressure in the gap is connected to the pressure monitoring line.
8. Magnetically-driven pump according to claim 1, wherein the inner shell is formed from a nickel-based alloy.
9. Magnetically-driven pump according to claim 1, wherein the outer shell is formed from zirconium oxide.
10. Magnetically-driven pump according to claim 1, wherein a flat seal is arranged between the housing cover and the pump housing, wherein a fastening of the housing cover to the pump housing exerts a prestress on the flat seal.
Description
[0018] Further features, details and advantages of the invention will become apparent on the basis of the following description and with reference to the drawings, which show an example of embodiment. Objects or elements which correspond to one another are provided with the same reference numerals in all the figures. These show:
[0019] FIG. 1 a sectional view of a pump according to the invention,
[0020] FIG. 2 a view of the containment can,
[0021] FIG. 3 a sectional view of the containment can,
[0022] FIG. 4 a side view of the containment can, and
[0023] FIG. 5 a detail of the containment can.
[0024] In FIG. 1, a pump according to the invention is illustrated, designated overall by the reference numeral 1. The pump 1 illustrated is designed as a magnetically-driven pump 1. In the example of embodiment shown, the pump 1 is designed as a centrifugal pump. The pump 1 has a housing 3 in which an impeller 2 driven by way of the magnetic coupling 10, 11 is accommodated. The pump housing 3 is closed on its right-hand side by a housing cover 4, on which there is arranged a containment can 5 which is positioned between the driver 10 and the rotor 11 of the magnetic coupling 10, 11. The containment can 5 has a metal inner shell 6 and a ceramic outer shell 7. A flange 8 is formed on the ceramic outer shell 7. By way of this flange 8, the outer shell 7 is braced against the housing cover 4 by means of a clamping ring 9. The clamping ring 9 to this end has a screw ring 20, by means of which the clamping ring 9 is screwed to the housing cover 4. The flange 8 on the outer shell 7 is fixed on the housing cover 4 by way of the screw connection of the screw ring 20. The metal inner shell 6 is welded to the housing cover 4 and thus forms a unit with the housing cover 4. The welding is applied around the opening of the inner shell 6 and thus fastens the housing cover 4 hermetically on the inner shell 6. Between the housing cover 4 and the flange 8 of the outer shell 7 there is arranged a flat seal 14 which seals off the gap between the inner shell 6 and outer shell 7 against the housing cover 4. To this end, the clamping ring 9 exerts a prestress on the flat seal 14 and thus ensures a strong sealing action. With the fixing of the outer shell 7 on the housing cover 4 by way of the bracing with the clamping ring 9, a containment can 5 which has a metal inner shell 6 and an outer shell 7 of ceramic material slipped over it can be produced very easily. The sealing by means of the flat seal 14 between the housing cover 4 and outer shell 7 brings about reliable sealing even in the event of temperature fluctuations which have different effects on the materials of the outer shell 7 and the inner shell 6. Preferably the inner shell 6 is formed of a nickel-based alloy. This may for example be Alloy 718, Inconel 718 or Nicofer 5219 Nb or Hastelloy C-4. The outer shell 7 is preferably formed of zirconium oxide (ZrO.sub.2). As can further be seen from FIG. 1, the rotor 10 of the magnetic coupling 10, 11 is mounted in the containment can 5 by way of a pump bearing 12. The pump bearing 12 is connected to the housing cover 4. With the fastening of the pump bearing 12 to the housing cover 4, a particularly compact overall form of the pump shown here can be produced, since the pump bearing 12 is arranged within the double-shell containment can 5. As a result, the pump shaft 21, which transmits the rotary movement from the rotor 10 to the impeller 2, can be made particularly short. This compact overall form makes it possible to make a magnetically-driven pump 1 equipped with a double-shell containment can 5 so compact that the chemical standard DIN/ISO 2858 is complied with. As a result, the pump 1 shown is particularly suitable for increasing operating safety in production plants in the chemical industry. The pump 1 shown may be used here in a connection-compatible manner as a replacement for other pumps, e.g. those with a single-shell containment can. The pump bearing 12 is fastened to the housing cover 4 by way of a screw connection 13. As a result, the pump bearing 12 can be mounted very easily. Even in the event of maintenance work, the pump bearing 12 can be separated from the containment can 5 very easily. It is furthermore shown in FIG. 1 that a pressure monitoring line 15 is set into the housing cover 4. The pressure monitoring line 15 leads into the gap 16 which is formed between the inner shell 6 and the outer shell 7. The pressure in the gap 16 can be monitored by way of the pressure monitoring line 15 which leads into the gap 16. As a result, leaks or damage to the inner shell 6 and the outer shell 7 can be detected easily. A pressure sensor 17 which permits automatic pressure monitoring may be connected to the pressure monitoring line 15 for monitoring the pressure in the gap 16. To seal off the pump 1, a further flat seal 18 is arranged between the housing cover 4 and the pump housing 3. Due to the fastening 19 of the housing cover 4, said cover is pressed against the pump housing 3 and thus exerts a prestress on the flat seal 18 arranged between the pump housing 3 and housing cover 4. This makes reliable sealing of the pump housing 3 possible.
[0025] The containment can 5 of FIG. 1 can be seen in a perspective view in FIG. 2. It can be recognized that the clamping ring 9 produces the prestress with which the flange 8 of the outer shell 7 is braced against the housing cover 4 by way of a screw ring 20. Guided laterally out of the housing cover 4 there is a pressure transmission line 22, to which a pressure sensor 17 is connected. The pressure transmission line 22 is guided by way of a pressure monitoring line 15 (FIG. 1), which is formed in the housing cover 4, into the gap 16 between the inner shell 6 and the outer shell 7. This makes it possible to monitor the pressure in the gap 16.
[0026] FIG. 3 shows a portion of a sectional view through the containment can 5 of FIG. 2. It can be seen from this representation that the clamping ring 9 braces the flange 8 of the outer shell 7 against the housing cover 4, which is welded to the inner shell 6 by way of a welded joint 23. The clamping ring 9 exerts a prestress on the flat seal 14 arranged between the housing cover 4 and the outer shell 7. The prestress of the clamping ring 9 is produced by way of the screws of the screw ring 20.
[0027] FIG. 4 shows a further view of the containment can 5. In the side view, a part is illustrated cut away, so that it is possible to view the pressure monitoring line 15 formed in the housing cover 4.
[0028] This cut-away region is illustrated more precisely in FIG. 5. It can be recognized how the pressure monitoring line 15 is guided into the gap 16 between the inner shell 6 and the outer shell 7. This makes it possible to monitor the pressure in the gap 16 between the inner shell 6 and the outer shell 7 of the containment can 5. In this detail view, the flat seal 14 arranged between the flange 8 of the outer shell 7 and the housing cover 4 can also be clearly recognized, on which seal the clamping ring 9 exerts a prestress through the screw connection by way of the screw ring 20. The weld seam 23 between the inner shell 6 and housing cover 4 can also be clearly recognized in FIG. 5. It is apparent from this that the weld seam 23 is formed as a fillet weld and therefore is simple to manufacture. In addition, the fillet weld offers reliable sealing and fastening between the housing cover 4 and the inner shell 6.
List of Reference Numerals
[0029] 1 pump [0030] 2 impeller [0031] 3 pump housing [0032] 4 housing cover [0033] 5 containment can [0034] 6 inner shell [0035] 7 outer shell [0036] 8 flange [0037] 9 clamping ring [0038] 10 driver [0039] 11 rotor [0040] 12 pump bearing [0041] 13 screw connection [0042] 14 first flat seal [0043] 15 pressure monitoring line [0044] 16 gap [0045] 17 pressure sensor [0046] 18 second flat seal [0047] 19 fastening [0048] 20 screw ring [0049] 21 pump shaft [0050] 22 pressure transmission line [0051] 23 welded joint
