DUST AND DIRT SEPARATION ASSEMBLY

Abstract: A dust and dirt separation assembly (10; 50) for use in a vacuum cleaner, includes a dirty air inlet (12; 52) and a clean air outlet (13; 53) with an airflow path passing firstly through a cyclonic separator (11; 55) for separating larger particles of dirt from the dirty air and secondly through a filtration element (20; 66) for separating smaller particles of dust from the dirty air, a dirt collection chamber (16; 56) to receive dirt from the cyclonic separator and dust from the filter element, and a striker mechanism (30; 70) including a striker member (31; 78) which is operable to strike the filter element to dislodge the dust from the filter element so that the dust enters the collection chamber with the larger particles of dirt. The striker member may be operated in response to cessation of air-flow within a section (32-35) of the air-flow path or by a mechanical actuator (72).

Description: Title: Dust and Dirt Separation Assembly Description of Invention This invention relates to a dust and dirt separation assembly for use in vacuum cleaners of the kind in which dust and other debris is picked up by suction and entrained in an airflow, and subsequently separated from the air in which it is enti'ained at least in part by causing the airflow to pass through a filter element. It is to be understood that such dust and dirt separation may be achieved entirely by passage of dirty air tlirough one or more filter elements, or partly by passage of the air through other separation devices, such as a cyclone, and partly by passage through one or more filters, and the assembly in accordance with the present invention may be used alone or in combination with other filters or other separation devices. Dust filter elements by their very nature tend to become clogged by the dust they are designed to collect and there have been various proposals for mechanisms intended to shake or otherwise agitate filter elements for the purpose of dislodging collected dust therefrom. By way of example, EP-A-860554 discloses the use of an intermittently powered actuator to operate an element which moves a filter in a self-propelled street sweeping machine to shake the filter and remove collected dust; GB-A- 1471035 discloses a vacuum cleaner with a solenoid operated shaker which is activated by a pressure switch in response to a drop in exhaust air pressure caused by partial blockage of the filter; US-A-5090083 discloses a commercial carpet cleaner with filter tubes that are normally maintained in an extended state by means of springs which are compressible under the action of a manually operable depressor plate so as to enable the filter tubes to be shaken, thereby allowing the collected matter to fall into a hopper; and US-A-5681363 discloses a filter shaking arrangement in which a vacuum cleaner dust bag is held within an elastically deformable frame which is expanded by virtue of air pressure in the filter bag, so that when the airflow is inteirupted elastic contraction of the frame shakes the bag to dislodge dust from the filter material. It is an object of the present invention to provide a simple and effective mechanism for dislodging dust from a filter element and into a dirt collection chamber, particularly in a vacuum cleaner. According to a first aspect of the invention there is provided a dust and dirt separation assembly having a dirt collection chamber, a dirty air inlet and a clean air outlet with an airflow path therebetween, the air flow path passing through a first separation means for separating larger particles of dirt from the dirty air such that it is collected in the dirt collection chamber, and a second separation means for separating smaller particles of dust from the dirty air, wherein the second separation means is a filter element and the assembly further includes a striker member which is activatable to strike the filter element to dislodge the dust from the filter element and such that the dust is collected in the dirt collection chamber with the larger particles of dirt. •Preferably the first separation means is a cyclonic separator. The filter element may comprise a filter body made of a filter material which has non-stick properties to facilitate separation of the dust from the surface thereof the filter element is struck. Conveniently the filter material has a coating of PTFE or the like. Preferably the filter element further comprises an impact member on which the striker member impacts when striking the filter element. Ideally, when the filter element is struck by the striker member, the dust falls down into the dirt collection chamber and mixes with the larger dirt already collected there. The striker member may be disposed in said airflow path so as to be movable in response to airflow in said airflow path and to be held in spaced relation to said filter element, but allowed to impact on said filter element when said airflow ceases so as thereby to dislodge the dust from said filter element. Further the striker member may be held in spaced relation above said impact member by the airflow and allowed to fall gravitationally onto said impact member when airflow ceases. The assembly may further comprise a guide tube which forms part of the airflow path downstream of said filter element within which said striker member is located. The guide tube preferably includes a constriction through which said striker member can pass with a clearance such that the striker member is held in a substantially stable position relative to said constriction for a wide range of airflows. In such embodiments the striker member is preferably of generally spherical form and the guide tube is of generally cylindrical form. In an alternative embodiment the striker member comprises a resilient element arranged in an over-centre mechanism. The resilient element may be spaced from the impact member until actuated, when it passes through an over-centre condition and strikes the impact member before returning to its original position. Conveniently the assembly further comprises an actuation member which is manually operated to engage the resilient element and cause it to be displaced through the over-centre condition. The dirt collecting chamber may be releasably secured by catch means to enable removal for emptying, and the activation member may be activated when the catch means re released. According to a second aspect of the invention there is provided a filter assembly comprising a filter element and a striker member which is arranged to be movable so as to strike the filter element to dislodge the dust from the filter element. According to a third aspect of the invention there is provided a filter assembly comprising a housing having an air inlet and an air outlet, a filter element disposed in an airflow path between said air inlet and said air outlet, a striker member disposed in said airflow path so as to be movable in response to airflow in said airflow path and to be held in spaced relation to said filter element, but allowed to impact on said filter element when said airflow ceases to dislodge dust from said filter element. According to a further aspect of the invention there is provided a filter assembly comprising a housing having an air inlet and an air outlet, a filter element disposed in an airflow path between said air inlet and said air outlet, a striker member arranged to be held normally in spaced relation to said filter element, and being movable into contact with the filter element and, an actuating member to cause said striker member to move into contact with, and impact on, said filter element so as to dislodge dust from said filter element. According to a still further aspect of the invention there is provided a vacuum cleaner including a dust and dirt separation assembly or a filter assembly according to the any of the previous aspects of the invention. The invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 diagramatically illustrates a first embodiment of dirt and dust separation assembly in transverse section; Figure 2 diagramatically illustrates a second embodiment of dirt and dust assembly in transverse section; Figure 3 is a top plan view corresponding to Figure 2, and Figures 4 and 5 illustrate the action of a filter cleaning mechanism of the second embodiment. Referring to Figure 1 , a dirt and dust separating assembly 10 as illustrated is formed as a unit for incorporation in a vacuum cleaner apparatus in the air-flow path between a suction head, which is adapted to pick up dirt and dust from a surface being cleaned, and a source of suction, such as a motor-driven impeller disposed within the apparatus or externally thereof. The assembly 10 comprises an outer housing 1 1 with a tangentially arranged air mlet 12 at the upper end theieof and an axially located aii outlet 13 formed in a top wall 14 At its lower end the housing 1 1 affords a downwardly directed discharge outlet 15 leading to a dirt collection chamber 16, which for emptying may be removable from the outei housing 1 1, or have a bottom closure flap which can be opened or removed The outer housing 1 1 , with the tangential aii inlet 12, acts as a first separator having a cyclonic action such that largei particles of dirt or other debris in the air entering thiough the mlet 12, as shown by arrow A, are separated from the airflow and fall into the dirt collecting chamber 16 through the discharge outlet 15. A second separator in the form of a filter element 20 is disposed centrally within the outer housing 10, and may be located m an inner housing (not shown) geneially in the mannei of the Figure 2 embodiment described below The filter element compnses a geneially frusto-conical (oi cylindrical) filtei body 21 formed fi om pleated filtei mateπal which has secured thereto at its lower end a bottom closui e plate 22 whei eby duty an, aftei entering through an inlet 12 and ciiculat g ai ound the outei housing 1 1. is constiamed to flow thiough the filtei body 21 and to the an outlet 13, thiough an opening 23 formed in a top closui e plate 24 also seemed to the filtei body. Thus smallei particles of dust still contained within the airflow aftei the fust stage of sepaiation by the cyclone ai e entiapped on the filtei body 21 In accoi dance with the invention a stπkei mechanism 30 is piovided to pioduce an impact on the filtei element in such a mannei as to shake the body 21 of filtei matenal bπefly and thei eby dislodge the collected dirt In the embodiment shown in Figui e 1 , this is an anged to occui automatically when an flow thi ough the assembly 10 ceases Foi this purpose, a stiikei membei 31 is provided. Adjacent to the air outlet opening 23 in the top plate 24 and depending therefrom there is a short tubular body 32 with an annular end plate 33 spaced downwardly from the air outlet opening 23. The annular end plate 33 defines a central opening 34 of a diameter such as to allow the striker member 31, which in the illustiated embodiment is of hollow spherical form, to pass through with limited clearance. A guide tube 35 extends downwardly from the end plate 33 and terminates at a position spaced above the bottom closure plate 22 of the filter element 20. As can be seen, the internal diameter of the guide tube 35 is substantially greater than that of the central opening 34. The arrangement is such that airflow passing into the interior of the filter element 20 through the filter body 21 is constrained to flow around the lower end of the guide tube 35 towards the air outlet 13. Initially, the spherical striker member 31 will rest on the bottom closure plate 22, but the airflow through the guide tube 35 is such as to lift the striker member 31 towards and through the opening 34 and into the tubular body 32, as illustrated. Because the clearance between the striker member 31 and the opening 34 is limited, the striker member 31 will be held in substantially the same position over a wide range of airflow rates while the assembly 10 is in operation. However, when the airflow ceases the striker member 31 is allowed to fall gravitationally and impact on the bottom closure plate 22 so as to apply a brief shaking movement to the filter body 21 , thereby dislodging dust from the exterior surface thereof to fall through the discharge outlet 15 into the dirt collection chamber 16 which already contains the larger particles of dirt. The fine dust falls into the larger particles of dirt and to some extent mixes with them, rather than lying as a separate layer. This provides a very significant and practical advantage when the dirt collection chamber 16 is emptied, as the fine dust is less likely to fly up as a cloud to engulf the person emptying the chamber making the process cleaner and more pleasant than previously. It will be understood that airflow through the assembly 10 is normally generated by a motor-driven impeller which is ananged downstream of the air outlet 13 (either within the body of the apparatus or externally thereto for connection to the apparatus in any convenient manner) to draw air from a suction cleaning head (not shown) when the assembly 10 is incorporated in a vacuum cleaner apparatus, and that normally a cleaning operation is terminated by de-energising the motor which drives the impeller. However, the impeller does not stop instantaneously, but slows down over a period of several seconds, during which the airflow it creates gradually falls away. The throttling effect of the opening 34 relative to the striker member 31 is such that the striker member 31 remains suspended substantially in the position as illustrated until the airflow falls to such a low rate that the ball is allowed to drop through the opening 34. Having passed though the opening 34, because the guide tube 35 is wider than the opening, the striker member 31 encounters reduced resistance and is therefore allowed to fall substantially freely, with a minimum of air resistance, until it contacts the bottom closure plate 22 so as to apply a shaip impact thereto. By contrast, if the opening in the end plate 33 of the tubular body 32 were of the same diameter as the guide tube 35, the striker member 31 would descend relatively slowly down the length of the guide tube 35 as the airflow decreased, and accordingly it would strike the bottom closure plate 22 with a much reduced impact. In practice, it has been found that a spherical striker member weighing 120 grams and falling through a drop of 20 centimetres is sufficient to dislodge dust from the surface of filter material coated with PTFE, whilst absorbing only about 0.5 air-watt of power whilst being held within the tubular body 32. Whilst it is particularly convenient for the striker member 3 1 to be in the form of a hollow sphere, other forms could be used. Moreover, whilst it is particularly convenient for the striker member to be held up by virtue of the airflow alone, it would alternatively be possible to provide some form of mechanical support, such as a light leaf spring, which would serve positively to hold the striker member in the raised position and to provide a manually, or automatically, operable release mechanism to drop the striker member when required. One example of a manually operable release mechanism is utilised in the second embodiment as now described. Referring to Figures 2 to 4, a second embodiment of a dirt and dust separating assembly 50 is illustrated. The assembly 50 comprises an outer housing 5 1 with a tangential air inlet 52 and an axial air outlet 53 in a top wall 54 . An upper part 55 of the outer housing 51 acts as a cyclonic separator and a widened, lower part 56 of the outer housing 51 acts as a dirt and dust collection container, which for emptying may be removable from the upper part 55 of the outer housing 51, or have a bottom closure flap which can be opened or removed. An inner filter housing 60 is located below and around the outlet 53. The filter housing includes an upper cylindrical part 61 , which comprises a solid wall, and a lower cylindrical part 62, which comprises a mesh wall thiough which air can flow from the outer housing 51. The bottom of the filter housing is closed by a bottom plate 63, but below the mesh wall part 62 there are openings 64, and around the bottom plate there is a frusto-conical baffle 65. Located within the filter housing 60 is a filter member 66 which comprises a generally cylindrical filter body 67 formed of corrugated filter material having non-stick properties, such as may be provided by a coating of PTFE or other similar material. At its upper end, the filter body 67 is attached to an annular top plate 68, which defines a central opening 69 in register with the outlet 53. Dirty air is drawn into the outer housing 51 through the inlet 52, and in the upper part 55 the larger particles of dirt and other debris, such as hairs and fibres, are separated due to cyclonic separation, and fall down into the lower part 56 which acts as a dirt collection chamber similar to that of the Figure 1 embodiment previously described. The air then passes tluough the mesh wall part 62 of the filter housing 60 and through the filter body 67 in which the fine dust in the air becomes entrapped. The clean air then passes out of the housing 50 via the outlet 53. In time the filter body 67 may become clogged with the dust entrapped within it, and require cleaning, but in any event it is desirable to ensure that it is cleaned whenever the container 56 is to be emptied. For this purpose a striker assembly 70 is mounted on the top wall 54 of the outer housing 51, as shown in greater detail in Figures 3 and 4. The top plate 68 of the filter body 67 is formed or provided with an upwardly extending protrusion 71 which, as will become clear below, acts as an impact member for the transmission of a striking force to the filter body 67. The top wall 54 of the outer housing 51 has a rectangular recess 57 with a central opening 58 through which the upwardly extending protrusion 71 protrudes. The recess 57 has stepped end walls which define shoulders 59 which provide location means for a resilient member in the form of a leaf spring 72. As can be seen from Figure 4, the ends of the leaf spring 72 are located in the comers at the junction between the shoulders 59 and the end walls of the recess 57, and the length of the leaf spring is such that it is held in a stressed condition in which it is bent convexly upwards as shown in Figure 4 so as to be spaced away foπu the protrusion 71. The striker assembly 70 further includes an actuation member 73 which is manually operable by a user of the apparatus as and when required, preferably at least prior to emptying of the container 56. The actuation member 73 comprises a lever 74 mounted at one end on a pivot pin 75 which extends between a pair of raised lugs 76 adjacent to the longitudinal edges of the recess 57. At its other end, the lever 74 is formed with an upwardly directed finger- piece 77 and a downwardly extending nose 78. When the actuation membei 73 is opeiated by downwaid pressure applied to the fingei -piece 77 thei e is initial lesistance to movement due to the contact of the nose 78 with the leaf spiing 72, but when sufficient pressuie is applied to oveicome that lesistance to leaf spπng snaps thiough an ovei-cenrre condition and the cential legion moves sharply down, as shown in Figure 5, into a downwardly convex configuiation in which it impacts on the protrusion 71 earned by the top plate 68 of the filtei element 66 This iesults in the filter body 67 being shaken biiefly to dislodge the dust entiapped The dislodged dust is then allowed to fall within the filtei housing 60 and out thiough the openings 64 so as to be dehvei ed o\ eι the baffle 65 into the container 56 The dust shaken fiom the filtei body 61 falls to the bottom of the filter support 53 and then thiough the opening 54 and down into the dirt collection chamber 57 Theie it falls into the dirt and debus pi eviously collected and at least to some extent mixes into it In any event when the vacuum cleanei of which the assembly forms a part is used again befoi e the contamei is emptied further laigei dirt will be collected on top of the fine dust This means that, as before foi the pi eviously descnbed embodiment, the fine dust is less likely to puff up in a cloud when the collection contamei 56 is emptied The leaf spiing 72 is not stable with the central iegion in the downwaidly convex configuiation as shown in Figuie 4, and thus it ietums to its oπgmal upwaidly convex configui ation, as shown in Figuie 3, when the fingei -piece 77 is l eleased. thei eb) l etui ng the actuation membei 73 to its ongmal position, as shown in Figui e 4 While only the cential iegion of the leaf spnng 72 is deflected downw ai dl) into an unstable configuiation it would be possible foi the whole leaf spnng to adopt a downwaidly convex configuiation aftei passing thi ough an ovei -centi e condition but without ieaching a stable condition by aπ anging foi contact with the piotiusion 71 to occui befoie a stable configuiation is l eached Altematn ely oi additionally, the actuation membei ma e a sepai ate l etuin spnng It will be appieciated that othei forms of stiikei mechanism may be employed, such as a plungei that is spnng biased away fiom the protrusion 71 and held in spaced lelation theieto by detent means 01 the like to piovide additional lesistance to downwai d movement of the stiikei which yields suddenly, or a plungei that is biased into contact with the protrusion 71 and arranged to be lifted away fiom the pioti usion by an actuation member and released, either automatically of voluntanly, so as to shike the protrusion While, as descπbed above, the actuation membei 73 is piovided at the top of the dirt and dust sepaiating assembly 50 (which is removable from the vacuum cleanei appaiatus foi emptying) and is piefeiably ananged so as to be accessible foi opeiation at any time by the usei, and especially when the assembly is iemoved foi emptying, the anangement may be such that the actuation membei can be opeiated alternatively oi additionally by means of a button piovided foi that purpose on the exteπoi of the appaiatus Alternatively it may conveniently be incorpoi ated into a mechanism by which the assembly 50 is ieleased fiom a body consti uction of the vacuum cleanei appaiatus when it is desued to empty the collection contamei 56 This means that the filtei 67 is always cleaned befoi e the contamei 56 is emptied, and does not requne the usei to iemembei to do so In the piesent specification "compnse" means "includes oi consists of and "compπsing" means "including oi consisting of The featuies disclosed in the foiegomg descπption, oi the following claims, oi the accompanymg di aw nigs expi essed in then specific forms oi in terms of a means foi pei foπrting the disclosed function oi a method oi piocess foi attaining the disclosed lesult as appiopnate may, sepaiately, oi in any combination of such featui es be utilised foi leahsmg the invention in diveise forms theieof

Claims: CLAIMS 1. A dust and dirt separation assembly for use in a vacuum cleaner, the assembly having a dirt collection chamber, a dirty air inlet and a clean air outlet with an aiiflow path therebetween, the air flow path passing through a first separation means for separating larger particles of dirt from the dirty air such that it is collected in the dirt collection chamber, and a second separation means for separating smaller particles of dust from the dirty air, wherein the second separation means is a filter element and the assembly further includes a striker member which is activatable to strike the filter element to dislodge the dust from the filter element and such that the dust is collected in the dirt collection chamber with the larger particles of dirt. 2. An assembly according to claim 1 wherein the first separation means is a cyclonic separator. 3. An assembly according to claim 1 or 2 wherein the filter element comprises a filter body made of a filter material which has non-stick properties to facilitate separation of the dust from the surface thereof when the filter element is struck. 4. An assembly according to claim 3 wherein the filter material has a coating of PTFE or the like. 5. Aa assembly according to claim 3 or 4 wherein the filter element further comprises an impact member on which the striker member impacts when striking the filter element. 6. An assembly according to any one of the preceding claims wherein when the filter element is struck by the striker member the dust falls down into the dirt collection chamber and mixes with the larger dirt already collected there. 7. An assembly according to any one of the preceding claims wherein the striker member is ananged to be opei ated in response to cessation of airflow in said airflow path 8. An assembly according to Claim 7 wherein the striker member is airanged so as to be movable in lesponse to airflow in said airflow path and to be held in spaced relation to said filter element when the air-flow exceeds a predetermined minimum value, but is caused to impact on said filter element when said airflow ceases thereby to dislodge the dust from said filter element 9 An assembly accoiding to claim 8 wheiein the stiikei member is held in spaced l elation above said impact member by the airflow and is allowed to fall gravitationally onto said impact member when airflow ceases. 10. An assembly accoiding to claim 9 wheiein a guide tube is provided, which forms part of the aiiflow path downstieam of said filter element, and within which said sti ikei membei is located 1 1 An assembly accoiding to claim 10 wheiein the guide tube includes a constiiction thi ough which said sti ikei membei can pass with a clearance such that the stiikei membei is held in a substantially stable position lelative to said consti iction foi a wide iange of airflows 12. An assembly according to claim 10 wherein the striker member is of generally spherical form and the guide tube is of generally cylindrical form. 13. An assembly according to any one of claims 1 to 6 wherein a mechanical actuation mechanism is provided to operate the striker member. 14. An assembly according to Claim 13 wherein the actuation mechanism includes a snap-acting resilient element which changes from a first, stable condition to a second condition when a sufficient force is applied. 15. An assembly according to claim 14 wherein the resilient element is spaced from the impact member until actuated, when it snaps into its second condition to strike the impact member before returning to its first condition. 16. An assembly according to claim 14 or 15 wherein the assembly further comprises an actuation member which is operable manually. 17. A filter assembly for a vacuum cleaner, the assembly comprising a filter element and a striker member which is ananged to be movable so as to strike the filter element to dislodge the dust from the filter element. 18 A filter assembly for a vacuum cleaner, the assembly comprising a housing having an air inlet and an air outlet, a filter element disposed in an airflow path between said air inlet and said air outlet, a striker member disposed in said airflow path so as to be movable in response to airflow in said airflow path and to be held in spaced relation to said filter element, but allowed to impact on said filter element when said airflow ceases to dislodge dust from said filter element. 19. A filter assembly for a vacuum cleaner, the assembly comprising a housing having an air inlet and an air outlet, a filter element disposed in an airflow path between said air inlet and said air outlet, a striker member arranged to be held normally in spaced relation to said filter element, and being movable into contact with the filter element and, an actuating member to cause said striker member to move into contact with, and impact on, said filter element so as to dislodge dust from said filter element. 20. A vacuum cleaner incorporating an assembly according to the any of the preceding claims. 21. A dust and dirt separation assembly according to Claim 1 and substantially as hereinbefore described with reference to Figure 1 or Figures 2 to 4 of the accompanying drawings 22. A filter assembly according to any one of Claims 17 - 19 and substantially as hereinbefore described with reference to Figure 1 or Figures 2 to 4 of the accompanying drawings. 23. A vacuum cleaner incorporating an assembly according to Claim 21 or Claim 22. 24. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.

Inventors: GREY NICHOLAS GERALD, KENT ANDREW JOHN, GREY, NICHOLAS, GERALD, KENT, ANDREW, JOHN
Applicants: GREY NICHOLAS GERALD, KENT ANDREW JOHN, VAX LTD, GREY, NICHOLAS, GERALD, KENT, ANDREW, JOHN, VAX LIMITED
Application year: 2000
Main classification: A47L9
IPC codes: A47L9, B01D46, B01D50, B04C5, B04C9