Vacuum cleaner

Abstract

 A vacuum cleaner including a cyclone style dust box provided in a vacuum cleaner main body, an outer filter portion provided within the dust box which forms a first cyclone space between the outer filter portion and an inner wall of the dust box, an inner filter portion provided within the outer filter portion which forms a second cyclone space between the inner filter portion and an inner wall of the outer filter portion, and a flange portion provided to the outer filter portion which extends towards an inner wall of the dust box. It is possible to achieve a high dust collection efficiency since two cyclone spaces are provided in a dust box interior.

Description

[0001] The present invention relates to a vacuum cleaner. More particularly, it relates to a vacuum cleaner provided with a dust box of cyclone style.

[0002] There is known a conventional vacuum cleaner, especially an upright type (longitudinal type) vacuum cleaner, which does not utilize disposable paper bags for dust collection but employs a dust collection device of cyclone style in which a tubular filter is provided within a dust collection case which is attached to a suction path of a vacuum cleaner main body in a freely attachable and detachable manner for generating a spiral flow of air (so-called cyclone) in the interior thereof, and in which dust that has been filtered by this filter might be accumulated in the dust collection case. Such a dust collection device is economical when compared to disposable paper bags since it can be used semi-permanently upon performing maintenance of the filter.

[0003] A known type of a vacuum cleaner of cyclone style is a vacuum cleaner provided with a dust separation device related to the invention by Dyson (e.g. Japanese Published Patent Publication No. 511880/1998). The vacuum cleaner of cyclone style as illustrated in Fig. 10 is so arranged to generate a double cyclone by providing an inner cyclone case 52 inside a dust box 51. A lower portion of the inner cyclone case 52 is air-tightly closed by a cyclone tube 53 with respect to a first cyclone space 54 of the dust box 51. An upper portion of the inner cyclone case 52 communicates to the first cyclone space 54 of the dust box 51 through a shroud 60 exhibiting permeability.

[0004] Through negative pressure generated by an air blower (not shown) or similar connected to an exhaust outlet 58 at an upper end of the inner cyclone case 52, air containing therein dust is introduced from the exterior through a suction tube 55 to the first cyclone space 54 inside the dust box 51 and is circulated within the first cyclone space 54 so that large pieces of dust fall down to be accumulated above the cyclone tube 53. Air is further introduced into a second cyclone space 56 within the inner cyclone case 52 through the shroud 60 and is circulated within the second cyclone space 56 so that slightly large pieces of dust fall down to be accumulated in a space portion 57 below the cyclone tube 53. Air removed of dust will be exhausted through the exhaust outlet 58 at the upper end of the inner cyclone case 52.

[0005] However, the prior art vacuum cleaner as illustrated in Fig. 10 is of complicated structure, which is due to the provision of the cyclone tube 53 which air-tightly partitions the interior of the dust box 51. However, removing of dust which is accumulated on the upper side and on the lower side of the cyclone tube 53 needs to be performed by separating and taking out all of the inner cyclone case 52, the cyclone tube 53 and the shroud 60 from the dust box 51, and a drawback is accordingly presented that cleaning of the dust box interior is extremely difficult.

[0006] The present invention has been made for solving such problems, and it is an object thereof to provide a canister type vacuum cleaner of cyclone style with which it is possible to easily perform cleaning of the dust box interior.

[0007] The vacuum cleaner of the present invention is so arranged that a cyclone style dust box is provided in a vacuum cleaner main body,
   an outer filter portion is provided within the dust box which forms a first cyclone space between the same and an inner wall of the dust box,
   an inner filter portion is provided within the outer filter portion which forms a second cyclone space between the same and an inner wall of the outer filter portion, and
   the outer filter portion is provided with a flange portion extending towards an inner wall of the dust box.

[0008] It is preferable that a flange portion is further provided at a lower portion of the inner filter portion towards the inner wall of the outer filter portion.

[0009] It is preferable that a tip end portion of the flange portion is bent downward.

Fig. 1 is a perspective explanatory view illustrating one embodiment of the vacuum cleaner of the present invention;

Fig. 2 is a planar explanatory view of the vacuum cleaner of Fig. 1;

Fig. 3 is an explanatory view when the vacuum cleaner of Fig. 1 is seen from a left-hand side;

Fig. 4 is a perspective explanatory view of a dust box of Fig. 1;

Fig. 5 is a front view of the dust box of Fig. 1;

Fig. 6 is a longitudinal sectional view of the dust box of Fig. 1;

Fig. 7 is a longitudinal sectional view of the vacuum cleaner of Fig. 1;

Fig. 8 is a sectional view taken along the line VIII-VIII of Fig. 6;

Fig. 9 is a sectional explanatory view for explaining dimensions of the dust box of Fig. 6; and

Fig. 10 is a sectional view illustrating a conventional dust separation device of cyclone style.

[0010] The vacuum cleaner according to the present invention will now be explained with reference to the drawings.

[0011] The vacuum cleaner according to the present embodiment is so arranged, as illustrated in Figs. 1 to 8, that a cyclone style dust box 2 is provided to be freely attachable and detachable to and from a front portion of a vacuum cleaner main body 1 of canister type upon being inserted therein from above, and that a blower 3 is incorporated in a rear portion of the vacuum cleaner main body 1. Although not shown in the drawings, a series of a suction hose, a suction tube and a suction device is connected to a connection aperture 4 at a front end surface of the vacuum cleaner main body 1. The vacuum cleaner main body 1 is further provided with a front wheel 1a and a pair of rear wheels 1b and 1c so as to be movable on floor surfaces.

[0012] As illustrated in Figs. 4 to 6 and Fig. 8, the dust box 2 is so arranged that an outer filter portion 6 and an inner filter portion 7, which are respectively of substantially cylindrical shape, are arranged inside a transparent or semi-transparent dust box main body 5 of substantially cylindrical shape formed of, for instance, transparent synthetic resin, to be concentric with the dust box main body 5.

[0013] As illustrated in Fig. 6, the outer filter portion 6 is composed of an outer tubular member 8 and an outer filter 9 which is formed to cover a periphery of a plurality of slits 8a formed along a longitudinal direction of a side surface of the outer tubular member 8.

[0014] A flange portion 10 extending towards an inner wall of the dust box main body 5 is provided to be projecting from an outer peripheral side surface of the outer tubular member 8. A clearance 34 is formed between the inner wall of the dust box main body 5 and the flange portion 10. Accordingly, there are respectively formed, between the inner wall of the dust box main body 5 and the outer filter portion 6, a first cyclone space 25 which is enclosed by the inner wall of the dust box main body 5, the outer filter 9 and the flange portion 10 as well as a space portion 26 which communicates with the first cyclone space 25 through the clearance 34 for catching dust therein.

[0015] A tip end portion 10a of the flange 10 is bent downward, so that dust will hardly hung up at the tip end portion 10a when dust moves from the first cyclone space 25 to the space portion 26 through the clearance 34.

[0016] Similarly, the inner filter portion 7 is composed of an inner tubular member 11 and an inner filter 12 which is formed to cover a periphery of a plurality of slits 11a formed along a longitudinal direction of a side surface of the inner tubular member 11.

[0017] A flange portion 13 extending towards an inner wall of the outer tubular member 8 is provided to be projecting from an outer peripheral side surface of the inner tubular member 11. A clearance 35 is formed between the inner wall of the outer tubular member 8 and the flange portion 13. Accordingly, there are respectively formed, between the inner wall of the outer tubular member 8 and the inner filter portion 7, a second cyclone space 27 which is enclosed by the inner wall of the outer tubular member 8, the inner filter 12 and the flange portion 13 as well as a space 28 which communicates with the second cyclone space 27 through the clearance 35 for catching dust therein.

[0018] Similar to the flange portion 10, a tip end portion 13a of the flange 13 is also bent downward, so that dust will hardly hung up at the tip end portion 13a when dust moves from the second cyclone space 27 to the space portion 28 through the clearance 35.

[0019] As illustrated in Fig. 6, the outer filter portion 6 and the inner filter portion 7 are fixedly and suspendedly attached to a lower surface of an upper lid portion 14 for closing an upper end aperture of the dust box main portion 5.

[0020] More particularly, an intermediate lid portion 8b provided to be projecting from an upper portion of the outer tubular member 8 is fitted into an inner wall of the upper lid portion 14 with a seal ring 8c being pinched therebetween. The intermediate lid portion 8b and the dust box main body 5 are sealed in an airtight manner through a seal ring 8d which is provided at a stepped portion of the intermediate lid portion 8b. On the other hand, a cylindrical holder 11b with a plurality of slits which is provided to be projecting from an upper portion of the inner tubular member 11 is housed in the interior of the upper lid portion 14 while holding a cylindrical filter 29. The cylindrical holder 11b and the intermediate lid portion 8b are sealed in an airtight manner through a seal ring 11c provided at a lower end of an outer peripheral surface of the cylindrical holder 11b.

[0021] A suction tube 15 is provided to project from a side surface of the dust box 2, wherein a tip end side aperture 16 of the suction tube 15 is formed proximate of substantially the center of a width direction of the dust box 2 so that it might be directly connected to the connection aperture 4 formed in the center of a width direction of the vacuum cleaner main body (refer to Figs. 1 and 7).

[0022] A guide rib 18 is provided to project in a direction which is in line with an inner surface of the dust box 2 in proximity of an aperture 17 on a root side of the suction tube 15 at the inner surface of the dust box 2 so that air flowing into the dust box 2 through the suction tube 15 might be guided through this guide rib 18 in a flowing direction of the cyclone generated inside the dust box 2 (which is a clockwise direction in the case of Fig. 8). With this arrangement, air containing therein dust which is sucked through the suction tube 15 illustrated in Fig. 8 will be circulated in the dust box 2 so as to achieve high dust collecting efficiencies.

[0023] Further, a bottom lid 21, which is arranged to be freely openable and closable through a hinge 20 provided at a lower portion of a handle 19, is mounted to a bottom portion of the dust box main body 5 as illustrated in Fig. 6. The bottom lid 21 is so arranged that, upon pressing an upper portion of a lever 22 provided downward of the suction tube 15, a clamp 23 formed at a lower end of the lever 22 is detached from an engaging claw 24 on the bottom lid 21 side for releasing the lower end aperture of the dust box main body 5.

[0024] Accordingly; since dust which has been accumulated in the space portion 26 and the space portion 28 inside of the dust box main body 5 will fall down upon opening the bottom lid 21, it is possible to easily clean the interior of the dust box 2.

[0025] While types or materials of the outer filter 9 and the inner filter 12 are not particularly limited in the present invention, it is possible to employ, for instance, a filter in which a mesh filter is disposed in a tubular manner on an outer periphery of a tubular body which forms a passage for filtered air. It is also possible to employ other filters such as a filter in which a filter made of filter paper which is folded in a pleated manner (accordion-like manner) is provided in a tubular form.

[0026] Respective flows of dust and air within the vacuum cleaner according to the present embodiment will now be explained.

[0027] Air containing therein dust which has been sucked from outside of the vacuum cleaner main body 1 enters, as illustrated in Figs. 6 and 7, the dust box 2 through the connection aperture 4 and the suction tube 15, and circulates along the inner wall of the dust box main body 5. More particularly, in the interior of the first cyclone space 25, air flows to inside of the outer filter 9 while circulating, and dust is pulled downward upon passing through the clearance 34 to be accumulated in the space portion 26 at the bottom portion of the dust box main body 5.

[0028] Similarly, air which has flown to the interior of the outer filter 9 also circulates. More particularly, in the second cyclone space 27, air flows to inside of the inner filter 7 while circulating, and since the space portion 28 below the flange portion 13 will become of negative pressure accompanying the circulation, dust of a size which cannot pass through the inner filter 12 will be pulled downward through the clearance 35 to be accumulated on the space portion 28 at the bottom portion of the dust box main body 5.

[0029] It should be noted that a packing 36 for plugging a clearance between a lower end edge of the outer tubular member 8 and the bottom lid 21 is provided at the bottom lid 21, thereby preventing air from leaking out from the space 26 to the space 28 along the bottom lid 21.

[0030] Air of which dust has been filtered in the dust box main body 5 is further filtered by the circular filter 29 inside the upper lid portion 14, exists the dust box 2 through an exhaust outlet 30 at a rear end of the upper lid portion 14, is taken in by the blower 3 through a communication path 31 illustrated in Fig. 7, is filtered from the blower 3 through an exhaust filter 32, and is exhausted to the exterior through a meshed exhaust outlet 33 formed at a side surface of the vacuum main body 1 and a mesh of the rear wheel 1b or 1c.

[0031] Since the present embodiment employs a cylindrical filter 29, it is possible to achieve a large superficial area with a small outer radius when compared to a plate-like filter. It is accordingly possible to achieve downsizing when compared to a plate-like filter while it is further possible to reduce occurrence of plugging since dust will hardly enter inside of the filter owing to a reduction in wind velocity which is due to the large superficial area.

[0032] Distances between the outer filter 9 and the inner filter 12 of Fig. 9 in vertical directions will now be explained.

[0033] In the course of eliminating dust which has entered from the suction tube 15 of the dust box 2 by the outer filter 9 of the outer filter portion 6, a distance H₁ between a suction area of the meshed outer filter 9 and a suction area of the inner filter 12 will be defined.

[0034] Evaluation of catching efficiencies has been performed while setting the distance H₁ to 9.5 mm, 0 mm and -9.5 mm, respectively. It was found that the catching efficiency was higher in the order of 9.5 mm > 0 mm > -9.5 mm.

[0035] Such differences in catching efficiencies are considered to be due to the following reasons. That is, rotational force of wind will become weaker in the inner second cyclone space 27 when compared to that of the outer first cyclone space 25. Thus, when the inner filter 12 is provided in a sucking direction of the outer filter 9, air containing therein dust will flow in a linear manner from the outer filter 9 to the inner filter 12 without circulating in the interior of the second cyclone space 27 which might be a cause for the reduction in dust collecting efficiency. It is accordingly preferable that the outer filter 9 is disposed to be slightly higher than the inner filter 12, preferably higher by approximately 9.5 mm.

[0036] It should be noted that while the catching efficiency is improved with the increase of the distance H₁, approximately 9.5 mm will be the upper limit since the height is restricted due to the design of the vacuum cleaner main body.

[0037] A relationship of distance D₁ between the inner wall of the dust box main body 5 and the suction portion (which are the slits 8a in Fig. 9) of the outer filter portion 6 illustrated in Fig. 9 will now be explained.

[0038] The distance D₁ largely affects the catching efficiency and a suction rate (suction work rate) of dust in the first cyclone space 25. The larger the distance D₁ becomes, the more effectively will centrifugal force act so that dust will be hardly sucked by the suction portion of the outer filter portion 6 so as to improve catching efficiency.

[0039] On the other hand, the larger the distance D₁ is set, the smaller will an outer radius of the suction portion of the outer filter portion 6 as well as an area proportional thereto become (provided that the inner radius of the dust box main body 5 is constant), thereby causing a reduction in air capacity and weakening sucking power.

[0040] The inner radius of the dust box main body 5 was set to be, for instance, 130 mm, and the outer radius of the suction portion of the outer filter portion 6 was changed to measure catching efficacies and suction work rates. The results are indicated as follows.

TABLE 1

outer radius of suction portion of the outer filter portion 6 (mm)	90	80	70	60
catching efficiency (%)	93	95	97	98
suction work rate (W)	375	365	360	355

[0041] Catching efficiency: JIS Z8901; 10g of 4 types of dust for testing (talc powder) are sucked

[0042] Suction work rate: Measuring was performed by employing a measuring method as defined by JIS C9802

[0043] It is evident from the results in Table 1 that the suction work rate becomes maximum while securing a catching efficiency which is equivalent to that of a vacuum cleaner of paper bag style (97 to 78 %), which is the standard of currently available vacuum cleaners, when the outer diameter of the suction portion of the outer filter portion 6 is in the range from 60 to 70 mm (provided that the inner diameter of the dust box main body 5 is 130 mm). Accordingly, it is most appropriate to set the outer diameter of the suction portion of the outer filter portion 6 to be 54 to 56 % of the inner diameter of the dust box main body 5 in a vacuum cleaner of a type which collects dust utilizing centrifugal force.

[0044] A relationship of distance D₂ between the inner wall of the outer tubular member 8 of the outer filter portion 6 and the suction portion (which are the slits 11a in Fig. 9) of the inner filter portion 7 illustrated in Fig. 9 will now be explained.

[0045] The distance D₂ largely affects the catching efficiency of dust in the second cyclone space 27. The smaller the distance D₂ becomes, the less will dust be centrifuged in a satisfactory manner so that dust will be sucked by the suction portion of the inner filter portion 7 so as to reduce catching efficiency.

[0046] The inner radius of the outer tubular member 8 of the outer filter portion 6 was set to be 60 mm, and the outer radius of the suction portion of the inner filter portion 7 was varied to measure catching efficiencies. The results are indicated as follows.

TABLE 2

outer radius of suction portion of the inner filter portion 7 (mm)	35	30
catching efficiency (%)	96	98

[0047] It is evident from the results in Table 2 that the outer diameter of the suction portion of the inner filter portion 7 is preferably not more than 30 mm (provided that the inner diameter of the outer tubular member 8 of the outer filter portion 6 is 60 mm) for securing a catching efficiency which is equivalent to that of a vacuum cleaner of paper bag style (97 to 98 %), which is the standard of currently available vacuum cleaners. Accordingly, it is possible to achieve a high catching efficiency which is equivalent to that of a vacuum cleaner of paper bag style when the outer diameter of the suction portion of the inner filter portion 7 is set to be not more than 50 % of the inner diameter of the outer tubular member 8 of the outer filter portion 6.

[0048] A relationship of distance D₃ between the inner wall of the dust box main body 5 and the flange portion 10 illustrated in Fig. 9 will now be explained. Evaluation of catching efficiencies have been performed in a condition of an air capacity of 1.6 to 1.7 m³/mm wherein the distance D₃ was set to be 7 mm and 10 mm, respectively.

[0049] When the distance D₃ was 10 mm, dust would not fall down but remain circulating in the first cyclone space 25 above the flange portion 10 and hardly accumulated in the space portion 26 below the flange portion 10. Moreover, continuous circulation of dust within the first cyclone space 25 caused reductions in catching efficiencies since fluffs would adhere to the mesh of the outer filter 9 or enter inside of the outer filter portion 6. On the other hand, problems found when the distance was 10 mm were solved when setting the distance D₃ to 7 mm, thereby achieving a high catching efficiency.

[0050] While it might be considered on the basis of the above descriptions that the catching efficiency could be improved with the decrease of the distance D₃, the distance D₃ should be determined also in view of the size of dust since a distance D₃ which is too small will cause easy plugging of dust in the clearance 34 between the inner wall of the dust box main body 5 and the flange portion 10.

[0051] A relationship of distance D₄ between the inner wall of the outer tubular member 8 of the outer filter portion 6 and the flange portion 13 of the inner filter portion 7 as well as the distance H₂ between the upper surface of the flange portion 13 and the bottom lid 21 shown in Fig. 9 will now be explained.

[0052] The distance D₄ and H₂ largely affect catching efficiency of dust in the second cyclone space 27. Dust which has passed through the outer filter portion 6 will undergo separation of dust and air again in the second cyclone space 27. Dust which has been separated at this time will be sucked to the clearance 35 between the inner wall of the outer tubular member 8 and the flange portion 13 (which is due to a small distance D₄ and a high flow velocity). Since dust which is separated in the second cyclone space 27 is relatively fine, the catching efficiency is not affected as long as the distance D₄ is not less than 1 mm. A problem that dust which has been accumulated in the space portion 28 is sucked up again to the intake portion of the inner filter portion 7 is caused when the distance H₂ becomes too short.

[0053] For securing a catching efficiency which is equivalent to that of a vacuum cleaner of paper bag style (97 to 98 %), which is the standard of currently available vacuum cleaners, it is possible to achieve a high catching efficiency which is equivalent of a vacuum cleaner of paper bag style when the distance D₄ is set in the range of 1 to 3 mm and the distance H₂ not less than 30 mm.

[0054] According to the present invention, it is possible to achieve a high dust collection efficiency since two cyclone spaces are provided in a dust box interior. Moreover, the provision of a flange portion extending towards an inner wall of a dust box in an outer filter portion has enabled forming of cyclone spaces and spaces for catching dust which communicate with each other through a simple structure. It is accordingly possible to easily remove dust which has accumulated in space portions in the dust box so that cleaning of the dust box becomes easy.

[0055] A vacuum cleaner including a cyclone style dust box provided in a vacuum cleaner main body, an outer filter portion provided within the dust box which forms a first cyclone space between the outer filter portion and an inner wall of the dust box, an inner filter portion provided within the outer filter portion which forms a second cyclone space between the inner filter portion and an inner wall of the outer filter portion, and a flange portion provided to the outer filter portion which extends towards an inner wall of the dust box. It is possible to achieve a high dust collection efficiency since two cyclone spaces are provided in a dust box interior.

Claims

1. A vacuum cleaner comprising: a cyclone style dust box provided in a vacuum cleaner main body; an outer filter portion provided within the dust box which forms a first cyclone space between the outer filter portion and an inner wall of the dust box; an inner filter portion provided within the outer filter portion which forms a second cyclone space between the inner filter portion and an inner wall of the outer filter portion; and a flange portion provided to the outer filter portion which extends towards an inner wall of the dust box.

2. The vacuum cleaner of Claim 1, wherein a flange portion is further provided at a lower portion of the inner filter portion towards the inner wall of the outer filter portion.

3. The vacuum cleaner of any one of Claims 1 to 2, wherein a tip end portion of the flange portion is bent downward.

Drawing