The present invention relates to a device for pumping highly- viscous material, in particular thick oil, said device being adapted to at least partial immersion in the material and comprising a rotary helical screw, and a shell surrounding said screw and being partially open to permit entry of the material, said shell being adapted to rotate in an opposite direction with respect to the screw and being provided with means for promoting feed of material towards the screw.

Screw conveyors are very well known and are employed for the transport of both fluid liquids and granular material. A con¬ veyor of ^" the type defined above, and particularly designed for conveying granulate material is disclosed in the SE-patent 322,161. In connection with e.g. escapes of oil, however, it has been observed that the handling of the oil after it has been collected into a tank requires a disproportionate expenditure of time and energy and that neither conventional liquid pumps nor screw conveyors function in a satisfactory manner in this application. In the case of conventional screw conveyors the cause is principally the fact that the flow of thick oil at low temperature is so poor that the screw very soon forms a cavity in the mass of oil within which cavity the screw rotates without raising any appreciable amount of additional material. Consequently, it is necessary to warm the collected oil several degrees which requires a disporportionate expenditure of energy and time so that this stage can often be decisive in determining the capacity of the entire oil combating operation.

The purpose of the present invention is accordingly to provide a new device based on the principle of the screw conveyor, which device is adapted to pumping thick collected oil in particular but also other materials having poor flow. The invention is characterized in that the feed promoting means comprises at least one vane attached to the shell and extending outwardly

in a curved or inclined fashion so as to feed the material towards the shell as the shell rotates, and that in the shell at the foot of the feeding vane, on the collection side thereof, is an aperture for the delivery of the material to the screw within the shell.

The essential idea in the invention is thus the arrangement .of forced feeding of the material to the inlet apertures of the screw. The feed vanes are preferably larger than the screw in their radial projection and are naturally dimension¬ ed on the basis of experience so as to achieve the optimum result. For example, with a single vane its projection may be of the same order of magnitude as the diameter of the feed screw. The- shell may have several vanes, but an advan¬ tageous ..embodiment is one having two vanes diametrically opposed. In this embodiment the rotation of the shell is balanced and there are not too many apertures, which is important for the operation of the screw conveyor. Since the shell rotates in the opposite direction with respect to the screw the oil does not appreciably escape out of the apertures. The screw and shell are preferably fitted with their own hydraulic motors which are separately ad¬ justable as to their speed of rotation.

The invention together with its other advantages and embodi¬ ments is described in greater detail in the following by means of an -example and with reference to the accompanying drawings, in which

Figure 1 shows diagrammatically a device according to the invention as seen from the side and partially sectioned;

Figure 2 shows the lower part of the device as seen from above and partially sectioned;

Figure 3 shows the lower part of the device as seen from the side; and

Figure 4 shows a perspective view of the shell of the device.

In the embodiment shown in the figures there are two cir¬ cular, rigid horizontal plates 1 and 2 joined to each other by vertical rods 3 distributed around the periphery. On top of this structure is located a cylindrical exten¬ sion 4. joined by a flange 5 to said upper plate 1 and by a flange 6 to an outlet pipe 7.

Within said cylindrical extension 4 is located a screw 8 comprising a central shaft and a helix 8a joined to said shaft in known manner. Said screw is attached centrally to lower plate 2 by a bearing 10 and to outlet pipe sec¬ tion 7 by a bearing 11. The screw is rotated by a hydrau¬ lic motor 12.

Supported by plates 1 and 2 and fitted so as to be capable of rotation there is also a shell 9 surrounding said screw. The socket-shaped upper section 4 thus forms an extension of said shell 9. The shell 9 is rotated by a hydraulic motor 13 via a gearwheel 1. and a toothed ring 16 (Fig. .) on the periphery of the shell. Attached to shell 9 there are also two outwardly-directed scoop-shaped feeding vanes 15, which as said shell rotates collect the oil and feed it towards the shell. Screw 8 and shell 9 are rotated by motors 12 and 13 in opposite directions, as indicated by arrows in Fig. 2. Further, the speeds of motors 12 and 13 are preferably adjustable separately so that a suitable rate of feed-to the screw is obtained depending on the pro¬ perties of the particular material to be pumped.

The structure of the shell itself and of the feed vanes is most readily apparent from Fig. 4. The vanes 15 are fitted at their ends with stiffening plates 15a and are thus scoop- shaped. At the root of the vane and extending its entire length is an aperture 17 through which the material is led into the screw as shell 9 rotates.

It is obvious that the embodiment described above and shown in the figures can be modified in many ways within the con¬ cept of the invention. The feed screw and shell need not necessarily be cylindrical but could taper conically towards the top. The surrounding supporting structure..could also be entirely different from the one described above formed by plates 1 and 2 and rods 3. The same applies to extension socket -i and outlet section 7• The ^' drive equipment of the feed screw and the shell could differ entirely from that shown in the figures, the essential point being that the shell ^*' nd the screw rotate in opposite directions. The width of the slot 17 relative to the other parts of the device should naturally be chosen on the basis of exper _¬ ience and the slots could also be adjustable. Other details could also be varied in an appropriate fashion.