The present invention relates to vacuum cleaners and the like and in particular to such cleaners which are, to some degree _* self-emptying.

Background of the invention

Typical vacuum cleaners have an electrically-powered motor which drives a fan. Rotation of the fan induces an airflow which entrains dust and other trash. Typically a filter or a cyclonic separator is used to separate the entrained dust and other trash from the airflow. (Throughout this specification, including the claims, such material is referred to as

"particulate matter".) This separated particulate matter is accumulated in a dust-collecting chamber,- dust bag, filter bag or the like and must, sooner or later, be removed so that the cleaner can continue to operate. It is desirable that human intervention in this removal of particulate matter from the cleaner be reduced or eliminated.

Summary of the invention

The present invention accordingly provides a vacuum cleaner or the like comprising a closure clement which; is biased towards a position in which the closure element acts to retain accumulated particulate matter within the cleaner; and which is influenced by the weight of accumulated particulate matter to move to a position in which the closure element does not act to retain accumulated particulate matter within the cleaner,

It is preferred that the closure element is a flap on which at least a portion of the particulate matter accumulates.

It is preferred .that the vacuum cleaner or the like further comprises a housing and in which: the flap further comprises a counterweight; and the flap is hingedly mounted to the housing to allow movement of the flap between: the position in which the closure element acts to retain accumulated particulate matter within the cleaner and the position in which the closure element does not act to retain accumulated particulate matter within the cleaner

It is preferred that the housing comprises an open-ended frustro-conical portion and the flap acts to retain accumulated particulate matter within the cleaner by substantially occluding the open end of the frustro-conical portion of the housing.

It is preferred that centripetal forces on air-entrained particulate matter as it moves around the inner surface of the open-ended frustro-conical portion influence that particulate matter to accumulate on the flap.

It is preferred that the vacuum cleaner or the like further comprises a filter which is substantially conical and which carries ballast in the vicinity of the tip of the cone which acts to counteract the effect of pressure differential forces across the filter.

It will accordingly be seen that embodiments of the present invention reduce the amount of human intervention involved in emptying the cleaner.

Brief description of the drawings So that the present invention may be more readily understood, preferred embodiments of it are described in conjunction with the accompanying drawings in which: figure 3 is a view, partly in front elevation and partly in section, of a vacuum cleaner according to one embodiment of the present invention; figure 2 is a view, partly in rear elevation and partly in cross-section, of the embodiment of figure 1 ; figure 3 is a view, partly in elevation when viewed from the left hand side of figure 1 and partly in cross section, of the embodiment of figure 1; figure 4 is a view, partly in elevation when viewed from the right hand side of figure L and partly in cross-section, illustrating operation, of the embodiment of figure 1; and figure 5 is a view, partly in elevation when viewed from the left hand side of figure 1 and partly in cross-section* illustrating the embodiment of figure 1 when mounted to a mounting; figure 6 illustrates a component of the embodiment of figure 1. Description of preferred embodiments of the invention

Components

Figure 1 illustrates a vacuum cleaner 1 according lo preferred embodiments of the present invention. The vacuum cleaner 1 comprises an upper casing portion 2 and a separable lower casing portion 3. The separable lower casing portion 3 is readily detachably mounted on the upper casing portion 2, by use of over-the-centre lever connections 6 and 7. The preferred material for the casing is mild steel,

The upper casing portion 2 is substantially cylindrical in configuration while the lower casing portion 3 comprises a cylindrical portion 9 which is formed integrally with a frustro-conical portion 8.

A closure flap 4 is hingedly mounted on the frustro-conical portion 8 by hinge 10. The flap 4 is formed integral with a counter-weight 15. The action of the counter- weight 15 biases the flap 4 into a position in which it closes off the open lower end of the frustro- conical portion 8.

An inwardly-projecting circumferential shoulder 5 is formed at the upper end of the lower casing portion 3.

An airflow inlet 1 1 is substantially tangentially mounted on the cylindrical portion 9 of the lower casing 3, in the vicinity of the transition to the upper end of the frustro-conical portion 8, An airflow outlet 12 is substantially tangentially mounted on the motor 14,

An air-cooling inlet 13 protrudes from the upper end of the upper casing portion 2, and is mounted substantially coaxially with that upper casing portion 2. The air-cooling inlet 13 functions as an inlet of cooling air, such as air from outside or from an air-conditioning system.

As is illustrated in figure 2, an electric motor 14 is mounted substantially coaxially within the upper casing portion 2 and is directly coupled to a fan 16. Preferred forms of motor and fan combination are two or three stage 24 volt or 240 volt units. Especially preferred forms include 24 volt, Lamb Electric vacuum motor, model numbers 116515-13, 1 16515- 29 or 116515-32.

As is illustrated in figure 6, the filter 21 comprises filter fabric 22 which is sewn into a substantially conical shape. The circumference of the filter fabric 22 is in turn sewn into a rubber skin 23 which is formed integrally with a seal 26. Preferred materials for the filter fabric arc denim, Gove-Tex, calico, rubber-backed cotton material avid felt. The seal 26 functions as a seal between upper casing portion 2 and lower casing portion 3, The filter 21 is simply retained in place by the retention of the seal 26 between upper casing portion 2 and lower casing portion 3.

As is illustrated in figure 6, a closed pocket 24 is sewn onto the filter fabric 22. The pocket 24 is formed to lie on the outside of the cone that is formed from the filter fabric 22 and is in a position which is substantially at the base of that cone. The pocket 24 i$ charged with ballast. Preferred forms of ballast include lead shot and rice.

Assembly

The vacuum cleaner 1 is assembled for use with the filter 21 in place, The ballast which is within the pocket 24 biases the filter 21dowπwards. The filter seal 26 reposes in the circumferential shoulder 5 at the upper end of lower casing portion 3 and is retained in that position by the lower circumferential edge of the upper casing portion 2.

As is illustrated in figure 5, when in use the vacuum cleaner 1 is mounted so that its central axis is substantially vertical. In the embodiment of figure 5, this is achieved by use of a mounting bracket 27 which is attached to the upper casing portion 2. The mounting bracket 27 is in turn attached to a wall 31 or the like by use of upper and lower fasteners 28 and 2S which pass through the mounting bracket 37 and into the wall 31 ,

Operation

In use, the vacuum cleaner 2 is mounted with its axis substantially vortical on a wall or the like. An air inlet hose 20 is attached to the airflow inlet 11 in the conventional manner. Energization of the electric motor 14 causes induction of air into the cleaner 2 through the airflow inlet 1 1, The tangential orientation of the airflow inlet 1 1 promotes movement of entrained particulate matter around the inner circumference of the frustro-conical portion 8. Centripetal action causes heavier entrained particles stay close to the inside wall of the frustro-eonical portion 8 and also gravitate to the lower end of that portion where they accumulate on the closure flap 4. The weight of particulate matter 32 resting on the closure flap 4 tends to be counteracted by two forces: the closing moment on the flap 4 which is generated by the counter weight 15; and the moment of force generated by the air pressure differential on opposite flat faces of the flap 4.

The closure flap 4 opens to void particulate matter 32 from the cleaner 2 in either of two circumstances: when the power is turned off, and the weight of particulate matter 32 generates a moment of force which is greater than the moment which is generated by the counterweight 15; or when the power is turned on, and the weight of particulate matter 32 generates a moment of force which is greater than the sum of the moments generated by the counterweight 15 and the pressure differential acting on opposite flat faces of the ' flap 4.

According to the embodiment of figure 1 to 6, the motor and fan generate a vacuum pressure of 15 kilopascals and the effective diameter of the closure flap 4 which is exposed to the vacuum is 56mm, The closing force on the flap 4 generated by the pressure differential across it by a vacuum pressure of 15 kilopascals is the equivalent of 3.7 kilograms weight. Thus the weight of particulate matter 32 accumulated on the flap 4 in order to cause self-emptying of the cleaner when the cleaner is turned on wouJd need to exceed 3.7 kilograms, plus the counter-balancing effect of the counterweight 15.

While the present invention has been described with reference to a few specific embodiments, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications may occur to those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims,

"Comprises/comprising" when used in this specification is taken to specify the presence of slated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof,

In the claims, each dependent claim is to be read as being within the scope of ks parent claim or claims, in the sense that a dependent claim is not to be interpreted as infringed unless its parent claims are also infringed.