GB2298598A - Cyclone dust separator for vacuum cleaner with dust-settling fins or baffles - Google Patents

Description

IMPROVED DUST SEPARATION APPARATUS The invention relates to apparatus for separating dirt or dust particles from an airflow by cyclonic means. The invention relates particularly, but not exclusively, to cyclonic dust separation apparatus for use in a vacuum cleaner.

Cyclonic dust separation apparatus typically comprises an outer bin or container having a cylindrical or frusto-conical outer wall. A tangential air inlet supplies a dirty airflow to the interior of the bin or container such that the airflow is set into a swirling motion within the bin or container. By this swirling motion, dirt and dust particles are separated from the airflow and the particles collect in the lower portion of the bin or container whilst the airflow exits via an outlet located radially inwardly of the outer wall.

Sometimes, the airflow is then passed to a second cyclone designed to separate from the airflow fine dust particles which are not separated in the first cyclone.

Vacuum cleaners incorporating such dust separation apparatus are known. However, it has been found that, when the height of the bin or container is reduced or when the bin or container becomes full of collected dirt and dust, then some of the separated dirt and dust can become re-entrained in the airflow so that it passes out of the container again. When no second cyclone is provided the airflow exhausted from the bin or container carries with it more dirt and dust particles than is desirable. In cases where a second cyclone is provided, the re-entrained dirt and dust particles are separated from the airflow downstream of the bin or container but this then fills the collecting chamber of the second cyclone unacceptably quickly.

It is an object of the present invention to provide cyclonic dust separating apparatus wherein the risk of re-entrainment of separated dirt and dust into the airflow is reduced.

The invention provides apparatus for separating dirt or dust entrained in an airflow therefrom as set out in claim 1. Preferable and advantageous features of the invention are set out in the subsidiary claims. The invention also provides a vacuum cleaner comprising apparatus as set out in claims 1 to 21.

The provision of settling means inside the bin, particularly in the form of inwardly extending projections, fins or baffles, encourages the separated dirt and dust to settle at the bottom of the bin. It is thought that pockets of relative stillness are created in the area of these projections which allow the separated dirt and dust to settle rather than becoming re-entrained into the airflow. Furthermore, experimentation has shown that the provision of this type of settling means does not adversely affect the separation efficiency of the apparatus as a whole.

However, the percentage of dirt and dust particles exiting from the bin or cylinder has been found to reduce in the presence of these settling means.

Embodiments of the invention will now be described with reference to the accompanying drawings wherein: Figure la is a schematic perspective view of a bin or container forming part of dust separation apparatus according to the present invention; Figure ib is a schematic plan view of the bin or container shown in Figure la and illustrating the likely airflow pattern when the apparatus is in use; Figure 2 is a sectional side view through a bin or container forming part of apparatus according to the invention; Figures 3a and 3b are sectional side and plan views respectively of the bin or container shown in Figure 2 in use; Figures 4a and 4b are vertical and horizontal partial sections through a first alternative fin; and Figures 5a and 5b are horizontal sectional views through second and third alternative fins.

Figures la and ib illustrate schematically the principle behind the present invention. Dust separating apparatus incorporates a bin or container 12 having an outer wall 14 which has a circular cross-section. The bin or container 12 is normally generally cyclindrical in shape although conical or frusto-conical bins are not excluded. The bin 12 has an air inlet 16 which admits an airflow carrying dirt and dust particles into the bin or cylinder 12. The airflow enters the bin 12 tangentially so that the airflow adopts a swirling motion around the interior of the outer wall 14. By virtue of this swirling motion, the dirt and dust particles entrained within and carried by the airflow are separated out from the airflow and collect in the lower region 18 of the bin 12.The airflow moves towards the centre of the bin 12 and exits from the bin 12 by passing through small holes or perforations in a central shroud 20. The airflow then passes from the illustrated separation apparatus either direct to an exhaust port or to a second, high-efficiency cyclone for cyclonic separation of very fine dust particles which may remain in the airflow.

In order to prevent dirt and dust particles collected in the lower portion 18 of the bin 12 from becoming re-entrained into the airflow, fins or baffles 22 are arranged to project inwardly from the outer wall 14 into the interior of the bin 12. Four fins 22 are provided in the lower region 18 of the bin 12 and the fins 22 are equispaced about the circumference of the outer wall 14. As illustrated in Figure 1b it is believed that the provision of these fins 22 creates pockets immediately on the upstream side of each fin 22 wherein the airflow is relatively still compared to the remainder of the interior of the bin 12. Small eddies may occur in these regions.Any dirt and dust particles which collect in these regions appear to remain separate from the main airflow and the dirt and dust particles are encouraged to settle and discouraged from becoming re-entrained in the main airflow.

Figure 2 shows in more detail a bin 12 which forms part of the separation apparatus according to the invention. The bin 12 has an outer wall 14 which is cylindrical in shape and has a handle 24 formed integrally therewith or attached thereto. The lower portion 18 of the bin 12 is frusto-conical in shape and forms a collector for a high-efficiency cyclone positioned upstream of the bin 12. An upstanding wall 26 mates with a frusto-conical fine dust collector (not shown) to form part of the highefficiency cyclone.

Webs or fins 22 are positioned at the lower end of the outer wall 14 and project into the interior of the bin 12 from the outer wall 14. Each fin 22 has a generally horizontally extending upper edge 28 and a generally vertical inner edge 30. The fins 22 can be moulded integrally with the bin 12 or manufactured separately and fixedly attached thereto during the manufacturing process.

In the embodiment illustrated in Figure 2, four equispaced fins 22 are provided. Different numbers of fins 22 can be provided as desired. A plan view of the bin illustrated in Figure 2 is shown in Figure 3b.

Figure 3a illustrates the bin 12 in use, and in particular in combination with high-efficiency cyclone apparatus located centrally inside the outer wall 14.

Tests have shown that the effect of the dust settling apparatus varies according to the dimensions of the fins 22. The effect has been found to be particularly advantageous if the fins 22 project into the bin 12 to a depth d of between 10mm and 40mm, particularly 20mm. Also, it has been found that the height h of the fins 22 is advantageously between 50mm and lOOmm, particularly 66mm.

The shape of the fins 22 has also been found to affect the amount of dust which successfully settles in the lower region 18 of the bin 12. Figure 4 illustrates one embodiment of a fin 22. Both the upper edge 28 and the inner edge 30 are chamfered such that the sharp or acutely-angled edge lies on the upstream side of the fin 22.

Alternative embodiments are of course possible.

Figure 5a is a horizontal cross-section through a web having a tongue 32 extending from the inner edge 30 of the fin 22 in the downstream direction. However, the preferred embodiment is illustrated in Figure 5b. In this embodiment, the upper edge 28 is radiussed and the thickness of the fin 22 increases with distance from the upper edge 28. This is illustrated in Figure 2. Also, the inner edge 30 is partially chamfered and partially radiussed. In the lower region of the fin 22, the inner edge 30 has a chamfered portion 30' and a radiussed portion 30''. As the thickness of the fin 22 decreases in the vicinity of the upper edge 28, the size of the chamfered portion 30' decreases and, at or near the junction with the upper edge 28, the inner edge 30 becomes completely radiussed.

It will be appreciated by a skilled reader that adaptations and variations will achieve the same effect.

Claims (22)

1. Apparatus for separating dirt or dust entrained in an airflow therefrom, comprising a bin having an outer wall with a circular cross-section, a tangential airflow inlet for introducing the airflow to the bin substantially tangentially to the outer wall, and an airflow outlet, wherein settling means, for encouraging dirt and dust collected in the bin to settle, are provided inside the bin.

2. Apparatus as claimed in claim 1, wherein the settling means comprise at least one projection extending radially inwardly from the outer wall.

3. Apparatus as claimed in claim 2, wherein a plurality of projections are provided.

4. Apparatus as claimed in claim 3, wherein the projections are equispaced about the outer wall.

5. Apparatus as claimed in claim 3 or 4, wherein four projections are provided.

6. Apparatus as claimed in any one of the preceding claims, wherein the or each projection takes the form of a fin or baffle.

7. Apparatus as claimed in claim 6, wherein the or each projection is substantially planar and extends inwardly from the outer wall along a diameter of the bin.

8. Apparatus as claimed in claim 6 or 7, wherein the or each projection has an upper edge which extends substantially perpendicular to the longitudinal axis of the bin.

9. Apparatus as claimed in claim 8, wherein the upper edge is radiussed.

10. Apparatus as claimed in claim 8, wherein the upper edge is chamfered.

11. Apparatus as claimed in any one of claims 6 to 10, wherein the or each projection has an inner edge which extends substantially parallel to the longitudinal axis of the bin.

12. Apparatus as claimed in claim 11, wherein the inner edge is at least partially chamfered.

13. Apparatus as claimed in claim 11 or 12, wherein the inner edge is at least partially radiussed.

14. Apparatus as claimed in any one of claims 11 to 13, wherein the inner edge has a tongue protruding from the downstream side thereof.

15. Apparatus as claimed in any one of the preceding claims, wherein the or each projection extends inwardly from the outer wall for between 10mm and 40mm.

16. Apparatus as claimed in claim 15, wherein the or each projection extends inwardly from the outer wall by substantially 20mm.

17. Apparatus as claimed in any one of the preceding claims, wherein the or each projection has a height of between 50mm and 100mm.

18. Apparatus as claimed in claim 17, wherein the or each projection has a height of between 60mm and 80mm.

19. Apparatus as claimed in claim 18, wherein the or each projection has a height of substantially 66mm.

20. Apparatus as claimed in any one of the preceding claims, wherein the outer wall of the bin is substantially cylindrical.

21. Apparatus substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings.

22. A vacuum cleaner comprising apparatus as claimed in any one of the preceding claims.