Peristaltic pumpheads

Abstract: A peristaltic pumphead (31) comprises a pumphead body (311), a flexible tube which extends through the body, a rotor (314) which engages with the tube, and a hub (318) which supports the rotor (314) for rotation within the pumphead body. The hub (318) is directly connected to or is integrally formed with the pumphead body. The pumphead body or the hub is adapted to support directly a drive assembly (33, 35).

Description: The present invention relates to peristaltic pumpheads. Peristaltic pumps generally comprise a drive motor connected via a gearbox to drive a rotor housed in a pumphead. The rotor carries a pair of shoes or other means for engagement with a flexible tube. As the rotor rotates, the shoes deform the flexible tube to form an occlusion in the tube. As the occlusion moves along the length of the tube, fluid in the tube is forced from one end to the other. Conventional pump drive systems either require highly accurate alignment of the rotor with the gearbox and motor which is time consuming and expensive, or do not allow straight-forward exchange of the gearbox and or motor without disturbance being caused to the pumphead itself. US 4832585 discloses a peristaltic pump comprising a pumphead and a drive assembly, the pumphead comprising a rotor and a pumphead casing, the rotor being supported by a hub of the pumphead casing for rotation within the pumphead casing, a drive shaft extending through the hub so as to connect the drive assembly and the rotor, the drive assembly being secured independently of the drive shaft to a mounting portion of the pumphead casing such that the rotor and drive assembly are supported by the pumphead casing independently of each other. According to the present invention, the drive shaft extends unsupported through the hub, and the rotor is supported on bearings on an outer surface of the hub. In such a pumphead the flexible tube preferably extends out of the body to provide inlet and outlet ports of the pumphead, and the rotor acts to compress the tube. The driveshaft may extend unsupported through the hub. The rotor preferably comprises a main portion which carries tube engaging lobe portions and a central portion which carries the said driveshaft. A seal may be provided between the hub and the rotor, and a wear ring may be located between the seal and the rotor, the wear ring being rotatable with the rotor. Such a pumphead may include a lubricant drain path for allowing lubricant held in the pumphead body to drain away from the bearing in the event of seal failure. In a peristaltic pump in accordance with the present invention, the rotor is supported by the hub which is fixed to or is part of the pumphead body. For example, it may comprise part of the pumphead casing. In this way, the rotor can remain in place even if the drive assembly is removed. The provision of bearings which support the rotor on the outside of the hub allows the rotor driveshaft to be unsupported as it extends through the hub. The gearbox can be bolted directly to the pumphead casing or to the hub itself, so that its output shaft can engage with the rotor driveshaft. This enables quick and simple alignment of the gearbox shaft with the rotor shaft, while allowing easy replacement of the gearbox/drive assembly. For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 shows a side section view of a first prior art peristaltic pump; Figure 2 shows a sectioned side view of a second prior art pump; Figure 3 shows a section side view of a first pump embodying the present invention; Figure 4 shows an enlarged section view of the pumphead of Figure 3; Figure 5 shows an exploded view of the pumphead of Figures 3 and 4; Figure 6 shows a side sectioned view of part of a second pump according to the present invention; Figure 7 shows a sectional side view of a third pump embodying the present invention; The prior art peristaltic pump 1 shown in Figure 1 comprises a pumphead 11 which is driven by a motor 13 via a gearbox 15 and a drive coupling 16. The motor 13, gearbox 15, coupling 16 and pumphead 11 are mounted on a base plate 10. The pumphead 11 includes a rotor 110 which is rotatable by the drive arrangement 13, 15 and 16. The rotor carries shoes for engagement with a flexible tube 112, which carries a fluid to be pumped through the tube as the rotor rotates. An occlusion is caused to move along the tube in order to pump the fluid. The rotor and tube are contained within the pumphead housing by a cover plate 118. The rotor 110 is supported on integral bearings 116 and has a male input shaft 114. The shaft 114 is coupled to a gear motor assembly 13 and 15 by way of a drive coupling 16. The coupling is usually covered with a safety guard 161. The gear motor assembly 13, 15 must be accurately aligned with the input shaft and this is achieved using shims 151 under the gearbox mounting. The shims are individually machined or selected to size dependent upon the variation in height or alignment of the gear motor assembly to the input shaft. This alignment is required to be of high accuracy and is both time consuming and expensive to achieve. However, the advantage of this sort of pump arrangement is that the gear motor assembly can be exchanged without disturbing the pumphead assembly. A second prior art pump is shown in Figure 2. In the pump assembly 2 a pumphead 21 is mounted on a base plate 20. The pumphead includes a rotor 210 which operates to a engage with a flexible tube 212, as in the previous example. A motor 23 drives the rotor by way of a gearbox 25 which is also attached to the base plate 20. The gearbox 25 has an output shaft 251 which engages with the centre of the rotor 210 and is held in place by way of a bolt 214. Such a pump has the advantage that there is no difficulty in aligning the gearbox 10 and the rotor. However, changing of the gear motor assembly 23, 25 requires the cover 216 of the pumphead 21 to be removed, which requires the lubricating fluid within the pumphead to be drained and the pressing shoes and rotor to be removed. The rotor must be removed since it is held in position only by the shaft 251. A first pump 3 embodying the present invention is shown in Figures 3, 4 and 5, and comprises a pumphead 31 which is driven by a motor 33 via a gearbox 35. The pump arrangement is carried by a base plate 30. The pumphead 31 includes a rotor 313 which carries shoes 315 in conventional manner. The rotor 313 has a central region 314 for mounting a drive plate 316 from which extends a driveshaft 317. A mounting hub 318 projects from the pumphead body 311 and supports bearings 319 about which the central region 314 of the rotor 313 rotates. The driveshaft 317 extends, unsupported except by the drive plate 316, through the hub 318. A cover plate 312 attaches to the pumphead body 311 to provide a sealed unit in which the rotor rotates. The sealed unit contains lubricant to reduce wear on the rotor shoes 315 and the tube 322. The gear motor assembly 33, 35 is bolted to the outer side of the hub 318 by way of a mounting flange 351. The mounting flange 351 is integral with the gearbox 35 and so the gearbox 35 and motor 33 are rigidly attached to the pumphead assembly 31. An output shaft from the gear box extends into the hub 318 to engage with the driveshaft 317 at a splined connection. The rotor 313 is rotated about the hub 318 on the bearings 319 by the motor and gearbox arrangement 33 and 35. The gearbox output shaft is readily aligned with the driveshaft 317 of the rotor 313 by virtue of the fixed nature of the flange 351 and the hub 318. In addition, it is simple to remove the gear drive assembly 33 and 35 from the pumphead assembly 31, since the gear box is directly mounted to the outside of the pumphead assembly. Removal of the gearbox does not in any way affect the positioning of the rotor 313 since the rotor 313 is held rotatably on the hub 318. A seal 323 and wear ring 324 are provided between the central mounting portion 314 of the rotor 313 and the hub 318. The seals 323 prevent leakage of internal lubricant into the bearings 319. The wear ring 324 is provided on the rotor 313 in order to prevent undue wear of the rotor's central portion 314. The ring 324 is relatively easily replaced. In addition, a controlled leak path 325, 326 is provided so that if the seal 323 fails there is an immediate and obvious indication provided by controlled leaking of lubricant. This early warning of seal failure means that excessive wear of the bearings 319 can be prevented by early replacement of the seal 323. Thus, a pumphead embodying the present invention includes a rotor which is supported on integral bearings on a hub which is fixedly attached to the pumphead body. A driveshaft extends from the rotor and a gearbox is bolted to the outer surface of the hub in order that its output driveshaft can engage with the rotor driveshaft. Figure 6 shows a partial side view of a second embodiment of the present invention, in which a standard helical drive gearbox 35' is fitted to a rotor embodying the present invention. The rotor carries drive plate 316 from which driveshaft 317 extends as before. A conversion plate 40 is provided between the hub 318' and the flange 351' of the gearbox 35'. A conversion driveshaft 317' and a helical output shaft 352' allow the pumphead embodying the present invention to be used with a conventional helical gearbox 35'. Figure 7 shows a pump similar to the Figure 1 pump, including a converter 400 enabling use with a pumphead embodying the present invention. The converter allows such a pumphead to be driven, by a bareshaft drive system. The converter 400 includes a flange portion for attachment to the outer surface of the hub, and a set of bearings for aligning the driveshaft 317 from the rotor 31. The gearbox and motor assembly is attached to the driveshaft via a coupling, as in the Figure 1 pump.

Claims: A peristaltic pump comprising a pumphead (31) and a drive assembly (33, 35), the pumphead (31) comprising a rotor (313) and a pumphead casing (311, 318), the rotor (313) being supported by a hub (318) of the pumphead casing (311, 318) for rotation within the pumphead casing (311, 318), a drive shaft (317) extending through the hub (318) so as to connect the drive assembly (33, 35) and the rotor (313), the drive assembly (33, 35) being secured independently of the drive shaft (317) to a mounting portion of the pumphead casing (311, 318) such that the rotor (313) and drive assembly (33) are supported by the pumphead casing (311, 318) independently of each other, characterised in that the drive shaft (317) extends unsupported through the hub (318), and in that the rotor (313) is supported on bearings (319) on an outer surface of the hub (318). A peristaltic pump as claimed in claim 1, characterised in that the drive shaft (317) engages the drive assembly (33, 35) at a splined connection. A peristaltic pump as claimed in claim 2, characterised in that the drive shaft (317') is hollow and receives an output shaft (352') of the drive assembly (33, 35'). A peristaltic pump as claimed in any one of the preceding claims, characterised in that the rotor (313) comprises a main portion (314) which carries tube engaging lobe portions (315) and a central portion (316) which carries the said drive shaft (317). A peristaltic pump as claimed in any one of the preceding claims, characterised in that a seal (323) is provided between the hub (318) and the rotor (313). A peristaltic pump as claimed in claim 5, characterised in that a wear ring (324) is located between the seal (323) and the rotor (313), the wear ring being rotatable with the rotor (313). A peristaltic pump as claimed in claim 5 or 6, characterised in that a lubricant drain path (325, 326) is situated between the seal (323) and a bearing (319) supporting the rotor (313) with respect to the hub (318) for allowing lubricant passing the seal (323) to flow from the pumphead casing (311, 318) before reaching the bearing (319). A peristaltic pump as claimed in any one of the preceding claims, characterised in that the mounting portion comprises an abutment surface of the pumphead casing (311, 318) which is engaged by a mounting flange (351) of the drive assembly (33, 35). A peristaltic pump as claimed in any one of the preceding claims, characterised in that the pumphead casing (311, 318) comprises a pumphead body (311) to which a hub element (318) is secured, the mounting portion to which the drive assembly (33, 35) is secured being provided on the hub element (318).

Inventors: KOSTERS JOHAN G M, KOSTERS, JOHAN G.M.
Applicants: BREDEL HOSE PUMPS B V, BREDEL HOSE PUMPS B.V.
Application year: 1998
Main classification: F04B43
IPC codes: F04C5, F04B43