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United States Patent 3,731,465
Ohira ,   et al. May 8, 1973

ELECTRIC VACUUM CLEANER

Abstract

An electric vacuum cleaner wherein a first air passageway for a dust-containing air flow and a second air passageway for an air flow to rotate an air turbine which drives a dust removing device, are formed upstream of an electrically operated fan within the body of the vacuum cleaner, and the first and second air passageways are selectively switched from one another, whereby the normal cleaning operation and an operation to remove the dust deposited on a dust filter disposed in the first air passageway are selectively obtained.


Inventors: Ohira; Mitsuo (Hitachi, JA), Sagawa; Kouiti (Hitachi, JA), Hata; Ikuo (Hitachi, JA), Sasai; Goro (Hitachi, JA)
Assignee: Hitachi, Ltd. (Tokyo, JA)
Appl. No.: 05/106,816
Filed: January 15, 1971


Foreign Application Priority Data

Jan 19, 1970 [JA] 45/4444
May 13, 1970 [JA] 45/40106

Current U.S. Class: 55/299 ; 137/625.41; 15/327.6; 15/327.7; 55/300; 55/305; 55/418; 55/482
Current International Class: A47L 5/36 (20060101); A47L 9/20 (20060101); A47L 5/22 (20060101); B01d 046/00 ()
Field of Search: 55/300,418,304,305,299,482 15/327,347,352,327D,327E 137/625.41

References Cited

U.S. Patent Documents
1139084 May 1915 Templin
2158717 May 1939 Broch
2400217 May 1946 White
2522882 September 1950 Lofgren
2591567 April 1952 Lofgren et al.
3609946 October 1971 Nakagawa et al.
Primary Examiner: Nozick; Bernard

Claims



What is claimed is:

1. An electric vacuum cleaner comprising suction means mounted on a base plate, a dust collecting case being open at its upper side and removably mounted on said base plate to enclose said suction means, an openable cover provided on the opening on the upper side of said dust collecting case, means defining a first air passageway for a dust-containing air flow in said case extending from a first suction opening provided in the dust collecting case on the upstream side of said suction means and communicating therewith, means defining a second air passageway in said case for an air flow created by said suction means extending from a second air intake opening in said cover member provided centrally of the upper surface of said cover to the upstream side of said suction means and communicating therewith, an air turbine rotatably disposed in said second air passageway, filter means provided in said first air passageway for collecting the dust in the air flow passing in said first air passageway, a dust removing device provided on the inner surface of the cover adjacent said filter means and driven by said air turbine to deflect the filter means to remove the dust deposited on said filter means, and switching means provided on a hollow shaft formed on the inner surface of said cover for directing the air flow selectively into said first and second air passageway by closing flow communication of said suction means to said second air passageway during the filtering operation and closing flow communication of said suction means to said first air passageway during the dust removing operation, said switching means being composed of a cylinder having a flat portion at the lower end thereof, said flat portion having formed therein a plurality of outer sectral air passage holes and a plurality of inner sectral air passage holes, and a filter supporting plate in contact with said flat portion of said cylinder and having outer air passage holes and inner passage holes formed therein at locations corresponding to and in the same shape as said outer air passage holes and inner passage holes in said flat portion, and further said cylinder being rotatably mounted on said hollow shaft provided on the cover and said switching means further including means for rotating said cylinder.

2. An electric vacuum cleaner according to claim 1, wherein said first and second air passageways are joined upstream of the suction means.

3. An electric vacuum cleaner according to claim 2, wherein said switching means are provided in the vicinity of the point where said first and second air passageways are joined.

4. An electric vacuum cleaner according to claim 1, wherein a transparent window is provided at a portion of said second air passageway in which the air turbine is disposed.
Description



The present invention relates to an electric vacuum cleaner wherein the dust sucked into the body of the vacuum cleaner by an electrically operated fan is collected by a dust filter, and more particularly to an electric vacuum cleaner of the type described wherein means is provided to effectively remove the dust deposited on the dust filter, thereby to recover the suction ability of the cleaner.

In electric vacuum cleaners of the type described, it is generally necessary to remove the dust deposited on a cloth dust filter from time to time because otherwise the meshes of said cloth filter would be clogged with the dust during operation of the cleaner for an extended period to time.

The removal of the dust from the cloth filter has been effected manually by the use of a brush or the like, or automatically by giving a vibration to the filter. The former method is not only inefficient since the dust filter must be removed from the body of the cleaner and the dust deposited thereon is removed manually with the brush, but also very unsanitary because the dust-attached filter must be handled directly by hand.

On the other hand, the latter method has the disadvantage that an electric motor for the dust removing operation must be provided in addition the fan driving electric motor, which renders the suction cleaner not only complicated in construction but also large in size and expensive.

An object of the present invention is to provide an electric vacuum cleaner in which the dust deposited on a dust filter is effectively removed by a dust removing device which is operated by an air turbine rotating under the force of air sucked by an electrically operated fan, and which is simple in construction, inexpensive and convenient in handling.

Another object of the invention is to provide an electric vacuum cleaner of the character described above, in which a first air passageway for a dust-containing air flow and a second air passageway for an air flow to drive the air turbine are formed upstream of the electrically operated fan within the body of the vacuum cleaner, and said dust filter is disposed in said first air passageway, while said air turbine is disposed in said second air passageway, and further said first and second air passageways are selectively switched from one another by switching means, whereby the normal cleaning operation and an operation to remove the dust from the dust filter are selectively obtained.

Still another object of the invention is to provide an electric vacuum cleaner of the character described above, in which said dust removing device includes means which is in contact with the dust filter and operated by the air turbine to remove the dust deposited on said dust filter.

Still another object of the invention is to provide an electric vacuum cleaner of the character described above, in which the switching between the first and second air passages is effected by a cylindrical switching valve of simple construction which can be operated exteriorly of the vacuum cleaner.

Still another object of the invention is to provide an electric vacuum cleaner of the character described above, in which the sucking force of said electrically operated fan can optionally be adjusted by the switching means, whereby the cleaning operation efficiency is enhanced.

Still another object of the invention is to provide an electric vacuum cleaner of the character described above, in which a transparent window is provided at a portion of a turbine chamber in which said air turbine is housed, so that the state of rotation of said air turbine may be visible from the outside, whereby the condition of the dust removing operation can be readily inspected.

The other objects of the invention will become apparent from the following detailed description on the embodiments thereof when taken in conjunction with the accompanying drawings.

A characteristic feature of the present invention resides in the fact that a first air passageway for a dust-containing air flow and a second air passageway for an air flow to drive a dust removing device are formed upstream of an electrically operated fan with the body of the vacuum cleaner and a dust filter to collect dust is disposed in said first air passageway, while an air turbine to drive the dust removing device for removing the dust deposited on the dust filter is disposed in said second air passageway, and further, means for selectively switching said first and second air passages from one another is provided in the body of the suction cleaner to selectively obtain the normal cleaning operation and an operation to remove the dust from the dust filter.

Another characteristic feature of the invention resides in each of the embodiments to be described and illustrated herein, in which a first air passageway for a dust-containing air flow having a dust filter disposed therein and a second air passageway for an air flow to drive an air turbine for operating a dust removing device are formed, and means is provided for selectively switching said first and second air passageways from one another.

FIG. 1 is a vertical cross-sectional view of an embodiment of the electric vacuum cleaner according to the present invention;

FIG. 2 is a cross-sectional view showing, in an enlarged scale, the driving portion of the dust removing device of the invention;

FIG. 3 is a cross-sectional view taken along the line III-III' of FIG. 2;

FIG. 4 is a set of views showing the operation of switching means, of which FIG. 4a is a fragmentary cross-sectional view of the switching means in a position closing a first air passageway, and FIG. 4b is a fragmentary cross-sectional view of the same in a position closing a second air passageway;

FIG. 5 is a perspective view showing in explosion the mechanism in a compartment on one side of the casing of the cleaner;

FIG. 6 is a perspective view showing in explosion the mechanism in a compartment on the other side of the casing;

FIG. 7 is a vertical cross-sectional view of another embodiment of the electric vacuum cleaner according to the invention;

FIG. 8 is a cross-sectional view taken along the line VIII-VIII' of FIG. 7;

FIG. 9 is a cross-sectional view showing, in an enlarged scale, a portion of another form of the switching means of the invention; and

FIG. 10 is a set of views illustrating the operation of the switching means shown in FIG. 9, of which FIG. 10a is a plan view showing the position of the switching means in the normal cleaning operation, FIG. 10b is a plan view of the same in a position to adjust the sucking force, and FIG. 10c is a plan view showing the position of the same in a dust removing operation.

The present invention will be described by way of practical example as applied to a cylinder-type electric vacuum cleaner, with reference to the accompanying drawings.

Referring to FIGS. 1 - 6, a boat-shaped casing 1 of the electric vacuum cleaner is provided with a swivel wheel 2 and fixed wheels 3 at the bottom thereof, and the interior thereof is divided into a compartment 6 for accommodating a dust case 20 and a compartment 8 for accommodating suction means 7, by means of a partition wall 4.

The suction means 7 disposed in the compartment 8 is composed of an electric motor 9 and a fan 10, and is integrally secured in said compartment 8 by means of bolts or other fixing means with a vibration damping rubber element 11 interposed therebetween. In the compartment 8 is also provided adjacent the suction means 7 a cord chamber 13 for accommodating cord winding means 12 therein. Above the compartment 8 and the cord chamber 13 is provided a cover 14 which is secured to the casing 1 by bolts 5, so as to cover the suction means 7 and the cord winding means 12. The cover 14 is provided with a handle 15 on the upper surface thereof and has an exhaust outlet 16 formed therein rearwardly of said handle 15, which is covered with an exhaust cover 18 having a plurality of exhaust openings formed therein.

In the compartment 6 of the casing 1 is removably mounted a dust case 20 having a handle 19 secured to the upper surface thereof, and a connecting member 22 having a suction inlet 21 formed therein is connected to the forward end of said dust case 20 by bolts or other fixing means. The dust case 20 is formed with an air inlet opening 23 formed in one side wall thereof for communication with the suction inlet 21, and an openable cover 24 is provided on the opposite wall for discharging the dust accumulated in said dust case 20 therethrough. The interior of the dust case 20 is divided into two chambers by a partition plate 26 having a plurality of air passage holes 25 formed therein, and also has a first air passageway A and a second air passageway B formed therein. The upper chamber constitutes a turbine chamber 28 for accommodating an air turbine 27 therein, while the lower chamber constitutes a dust chamber 29 for accommodating coarse filter means to catch relatively large dusts such as flue of paper chips, entrained in the suction air and fine filter means to catch relatively small dusts such as sand which passed through said coarse filter means. The coarse filter means may be a screen filter 32 of coarse mesh stretched over a window 31 formed in a barrier plate 30 made of a synthetic resin or the like, and said coarse screen filter may be a filter plate having a plurality of punched holes perforated therethrough. The coarse filter means is removable from the dust case 20. The fine filter means provided downstream of the coarse filter means is a cloth filter 33 in the embodiment shown.

The air turbine 27 disposed in the turbine chamber 28 is rotatably mounted on the partition plate 26, with its rotary shaft 35 journaled in a bearing 34 integrally formed with said partition plate 26, and a gear 36 of small diameter is provided on the lower end of the rotary shaft 35. An air inlet 37 is provided at the front portion of the turbine chamber 28 and the air turbine 27 is driven by flow of air sucked through said air inlet 37. The rotation of the air turbine 27 is transmitted through the rotary shaft 35 to the small gear 36 to drive the same, which in turn drives an internal gear 38 of large diameter engaging therewith.

The internal gear 38 is rotatably mounted on the underside of the partition plate 26, with its shaft 40 journaled in a bearing 39 integrally formed with said partition plate 26. A dust removing device 41 is secured to the underside of the internal gear 38 by fixing means such as an adhesive or screws. The dust removing device 41 consists of a resilient dust removing element 42 made of rubber or synthetic resin and is arranged so as to be in sliding engagement with the surface of the cloth filter 33 opposite to the dust depositing surface. An air space is formed at the front portion of the turbine chamber 28 of the dust case 20 and a bracket 44 is secured in said air space by means of screws 45, which supports pivotably a valve body 43 to open and close the air inlet 37 of the turbine chamber 28. The valve body 43 is connected to one end of an operating lever 46, and opens or closes the air inlet 37 when said operating lever 46 is moved up or down. The other end of the operating lever 46 extends through a deflector 47 provided at the forward end of the dust case 20, and a knob 48 is provided at the projecting end of said operating lever. Further, a shutter plate 49 to open and close the air passage holes 25 in the partition plate 26 is connected to the operating lever 46, so that it is operated simultaneously as the valve body 43 is operated by the operating lever 46.

The operating lever 46 also has a check valve 50 connected thereto, which check valve opens and closes the air inlet opening 23 formed in the dust case 20. By operating the operating lever 46 upwardly or downwardly, the valve body 43, the shutter plate 49 and the check valve 50 are operated to open or close the air inlet 37 of the turbine chamber 28, the air passage holes 25 in the partition plate 26 and the air inlet opening 23 in the dust case 20.

Namely, when the normal cleaning operation is desired, the operating lever 46 is moved upward, whereby the check valve 50 closing the air inlet opening 23 is opened as indicated by the dotted line in FIG. 3, the valve body 43 closes the air inlet 37 and the shutter plate 49 opens the air passage openings 25.

When the suction means 7 is set in motion under such condition, a dust-containing air is sucked into the suction inlet 21 through a floor nozzle, an extension pipe and a flexible hose, not shown, and thence into the dust chamber 29 in the dust case 20 through the air inlet opening 23. The flow of dust-containing air thus sucked into the dust case 20 passes through the coarse filter means, i.e., the coarse mesh screen filter 32 stretched over the window 31 of the barrier plate 30, provided in said dust case 20, and at this time, relatively large dusts, such as flue or paper chips, are caught by the meshes of said screen filter.

Then, relatively small dusts, such as sand, are caught by the meshes of the fine filter means, i.e., the cloth filter 33. The dusts entrained in the air flow are completely removed therefrom by the coarse filter means and the fine filter means, and clean air only flows into the compartment 8 through the air passage openings 25 in the partition plate 26, an opening 52 formed in a side wall 51 at the rear end of the partition plate 26, an opening 54 formed in a packing 53 provided rearwardly of said opening 52 and a plurality of air passage openings 55 formed in the side wall of the cover 14 at locations corresponding to said openings 52, 54, as indicated by the solid line arrow shown in FIG. 3, and thence is exhausted to the outside of the cover 14 through the suction means 7, silencer means 56 covering the electric motor 9 of said suction means 7, the exhaust outlet 16 and the exhaust openings 17.

In the path of such air flow, the first air passageway A extending from the suction inlet 21 to the air passage openings 55 in the cover 14 is substantially formed by the partition 26 in the dust case 20.

After the continuous cleaning operation for an extended period of time in the manner described above, the suction ability of the cleaner becomes reduced by the deposition of a large amount of dust on the coarse filter means and the fine filter means, and thus it becomes necessary to remove the dust. However, the dust such as flue or paper chips deposited on the coarse filter means, i.e., the coarse screen filter 32, can be compressed into a sufficient small volume, though the apparent volume thereof is large, and does not substantially impair the air flow through the cleaner. The suction ability is reduced mainly by the sand or other small particles caught in the mesh of the fine filter means, i.e., the cloth filter 33, which provides a large resistance to the air passing through the cleaner. In the present invention, therefore, the dust removing device 41 is provided which is operated by the air turbine 27 provided in the upper portion of the dust case 20.

For operating the dust removing device 41, the operating lever 46 is first pushed down to the position shown in FIG. 4a, whereby the valve body 43 closing the air inlet 37 of the turbine chamber 28 is opened as shown in FIG. 4b and the shutter plate 49 closing the air passage openings 25 in the partition plate 26 is closed and further the check valve 50 operatively associated with said valve body and said shutter plate closes the air inlet opening 23 of the dust case 20. Then, the suction means 7 is set in motion, whereupon air flows into the turbine chamber 28 through the deflector 47 and the air inlet 37 as indicated by the dotted line arrow in FIGS. 2 and 4, and the air turbine 27 in said turbine chamber 28 is driven by the force of air.

The rotation of the air turbine 27 is transmitted through the rotary shaft 35 to the small diameter gear 36 to rotate the same and said gear 36 in turn drives the internal gear 38 meshing therewith. The internal gear 38 carries the dust removing device 41 consisting of the dust removing element 42, so that said dust removing element 42 slides, incident to the rotation of said internal gear 38, on the surface of the cloth filter 33 opposite to the dust depositing surface in pressure engagement therewith, whereby the dusts caught in the mesh of the cloth filter 33 can be simply removed therefrom.

On the other hand, the air passing through the turbine chamber 28 is exhausted to the outside of the cover 14 through the opening 52 formed in the side wall 51 of the partition plate 26, the opening 54 in the packing 53 and thence through the silencer means 56, the exhaust outlet 16 and the exhaust openings 17 while cooling the electric motor 9 of said suction means 7.

Namely, the air turbine 27 to drive the dust removing device 41 is disposed in the second air passageway B extending from the deflector 47 to the air passage openings 55 in the cover 14, and is driven by an air flow substantially free of dust.

In the embodiment described above, the removal of dust is effected by the dust removing element 42 made of a resilient material, such as rubber or synthetic resin, and secured to the underside of the internal gear 38. However, the removal of dusts may also be attained simply without using such dust removing element, by arranging such that the internal gear 38 and the cloth filter 33 are connected with each other at a point a predetermined distance offset from the center of the internal gear supporting shaft 40 as by a rotary shaft, and a vibration is imparted to the cloth filter 33 by the circular motion of said rotary shaft.

The suction ability of the cleaner can be recovered by removing the dust deposited on the cloth filter 33 therefrom by the dust removing device in the manner described above. However, after repetition of the above-described operation, a large amount of dust is accumulated in the dust case 20, which must be removed from said dust case.

In this case, the dust case 20 is demounted from the casing 1 and the handle 19 is provided on the dust case 20 to facilitate the demounting. The handle 19 is provided with locking means 57 which is engaged with or disengaged from the handle 15 of the suction cleaner to secure the dust case 20 to or to provide for removal of the same from the casing 1. Therefore, the dust case 20 can be simply removed from the casing 1 by releasing the locking means 57 from the locked position, when the dust accumulated in the dust case 20 is desired to be removed therefrom.

The dust case 20 thus removed from the casing 1 is carried to a desired location and the dust therein is removed therefrom upon removing the cover 24, whereby the dust can be treated simply and sanitarily. The dust case 20 and the cover 24 must be maintained in a substantially sealed condition. To this end, the packing 58 is provided along the edge of the cover 24. Further, the cover 24 is provided with a projecting knob 59 to facilitate removal of said cover.

The dust case 20 is provided with a transparent window 60 at that portion of the upper surface thereof which is located in the turbine chamber 28, so that the state of rotation of the air turbine 27 during the dust removing operation may be observed exteriorly, whereby a proper dust removing operation can be simply made known to the user.

Now, another embodiment of the present invention will be described with reference to FIGS. 7 - 10, in which the invention is applied to a pot-type electric suction cleaner.

In FIGS. 7 - 10, a mounting plate 72 is integrally secured to the upper surface of a substantially circular casing 70 through a support 71 by means of bolts or other fixing means, and exhaust outlets 73 are formed between the upper edge of said casing 70 and said mounting plate 72. The casing 70 is provided at the bottom thereof with a swivel wheel 74 and fixed wheels 75. A supporting cylinder 76 having an inwardly flexed edge is formed at the center of the mounting plate 72, and suction means 78 is mounted on said supporting cylinder 76 with a vibration damping rubber 77 interposed therebetween. The suction means 78 comprises an electric motor 79 and a fan 80 which are integrally mounted on the supporting cylinder 76. A dust case 81 provided on the upper surface of the casing 70 has a doughnut-like shape open at the upper side and removably disposed around the suction means 78. The outer wall of the dust case 81 is provided with a suction inlet 82 and the upper edge thereof is bent outwardly to form a flange 83 and the inner wall 85 thereof is formed to surround the fan 80, with the upper edge thereof bent inwardly to form a flange 84. A cover 86 is provided in opposed relation to the open upper side of the dust case 81 to define a dust collecting cavity 87 together with said dust case 81.

A trumpet-shaped filter element 88 is provided in the dust case 81 to divide the dust collecting cavity 87 into a first dust chamber 89 and a second dust chamber 90. The filter element 88 is of such character that it blocks relatively large dust particles such as flue or paper chips, but permits relatively small dust particles, such as sand, to pass therethrough. Above the filter element 88 is provided a dust filter 92 which is made of a cloth of fine mesh and adapted to block sand or the like passing through the filter element 88. The dust filter 92 has the outer edge thereof secured to the outer edge of the cover 86 through an annular packing 91, with the inner edge thereof secured to a filter supporting plate 93 provided at the center of the inner surface of said cover 86. Further, the cover 86 is provided with a dust removing device 94 for automatically removing the dust deposited on the dust filter 92 therefrom. The dust removing device 94 comprises a plurality of radial dust removing elements 95 adapted to slide on the surface of the dust filter 92 opposite to the dust depositing surface in pressure engagement therewith, driving means 97 for imparting a rotating force to said dust removing elements 95 through a speed reduction mechanism under the suction force created by the suction means 78 and a suction switching mechanism 98.

The driving means 97 comprises a rotary shaft 100 supporting an air turbine 99 on the upper surface of the cover 86, a cover 103 connected to the cover 86 in such a manner as to shield the air turbine 99 and having an air inlet opening 102 therein for leading effectively air to blades 101 of said air turbine 99, a transparent window 104 formed in the upper face of said cover 103 for visually inspecting the rotation of the air turbine 99 exteriorly, an air guide plate 105 disposed in said air inlet opening 102 and a bearing 106 formed integrally with said cover 86 and supporting the rotary shaft 100.

The speed reduction mechanism 96 comprises a small diameter gear 107 provided at the lower end of the rotary shaft 100, an intermediate gear 111 rotatably mounted on a shaft 108 supported on the inner surface of the cover 86 and having a large diameter gear 109 formed at the upper portion and a small diameter gear 110 formed at the lower portion thereof integrally with said large diameter gear 109, said large diameter gear 109 intermeshing with said small diameter gear 107, and a sliding collar 114 rotatably mounted on a hollow shaft 112 formed at the center of the inner surface of said cover 86 and having a large diameter gear 113 integrally formed therewith at a portion of the outer surface thereof and intermeshing with said small diameter gear 110. The aforesaid dust removing elements 95 are carried on the sliding collar 114.

The hollow shaft 112 formed at the center of the inner surface of the cover 86 is communicated with a turbine chamber 115 which is defined by the upper surface of the cover 86 and the cover 103 covering the air turbine 99, and the suction switching mechanism 98 is rotatably disposed in the hollow of the hollow shaft 112.

The suction switching mechanism 98 comprises a switching valve 122, a supporting shaft 123 for securing said switching valve 122 on the inner surface of the cover 86 through a filter supporting plate 93 and operating means 124 for externally operating said switching valve 122, said switching valve 122 having a cylindrical portion 116 and a flat portion 117 formed at the lower end of said cylindrical portion 116 and having a plurality of sectoral air passage holes 119 formed in the outer portion at locations corresponding to and in the same shape as a plurality of sectoral air passage holes 118 formed in the filter supporting plate 93 respectively and a plurality of sectoral air passage holes 121 formed in the inner portion at locations corresponding to and in the same shape as a plurality of sectoral air passage holes 120 formed in the central portion of said filter supporting plate 93 respectively.

The operating means 124 consists of a shifting lever 127 which is secured to the cylindrical portion 116 of the switching valve 122 at one end and pivotably connected to the supporting shaft 123 at the central portion thereof for pivotal movement about said supporting shaft 123, and a connecting rod 126 having one end secured to the other end of said shifting lever 127, with the other end thereof extending outwardly through the cover 103 and provided with a knob 125.

The gap between the upper edge of the inner wall 85 of the dust case 81 and the suction means 78 is sealed by a packing 128. Further, a cylindrical silencer plate 129 having a plurality of exhaust openings formed therein is provided around the electric motor 79 of the suction means 78 and the inner surface of said silencer plate 129 is lined with silencing material 131.

The outer peripheral edge of the cover 86 is sealed by the annular packing 91 and a damper 132 is provided along said edge to secure the dust filter 92. A handle 133 is provided on the upper surface of the cover 86 to facilitate the transportation of the suction cleaner. A coil spring 134 is disposed in the cylindrical portion 116 of the switching valve 122 to maintain sealing between the filter supporting plate 93 and the flat portion 117 of said switching valve 122.

In the Figures, the dotted line arrow C indicates a first air passageway for a dust-containing air and the solid line arrow D a second air passageway for an air flow to operate the air turbine.

The pot-type electric vacuum cleaner constructed as described above operates in the following manner: When a cleaning operation is desired, the knob 125 is rotated to rotate the shifting lever 127 about the supporting shaft 123 through the connecting rod 126. Since the shifting lever 127 has the switching valve 122 connected to one end thereof, said switching valve 122 and the filter supporting plate 93 are placed in the relative position shown in FIG. 10c. Namely, the air passage holes 119 in the outer portion of the flat portion 117 of the switching valve 122 are brought into registration with the air passage holes 118 formed in the filter supporting plate 93, but the air passage holes 121 formed in the inner portion of said flat portion 117 and the air passage holes 120 in said filter supporting plate 93 are closed with the unperforated portions of said filter supporting plate and said flat portion.

Then, attachments, e.g., a flexible hose, an extension pipe and a floor nozzle, are connected to the suction inlet 82 in the order mentioned, following which the suction means 78 is set in motion. Upon actuation of the suction means 78, a negative pressure appears in the dust collecting cavity 87 and a dust-containing air is sucked into the second dust chamber 90 in the dust case 81 through the floor nozzle, the extension pipe, the flexible hose and the suction inlet 82, wherein relatively large dusts, e.g., flue or paper chips, are filtered by the filter element 88. Fine dusts, which are not caught by the filter element 88 pass through the first air passageway C indicated by the dotted line arrow and are completely caught by the dust filter 92. The dusts thus caught are accomulated in the first dust chamber 89 and the second dust chamber 90 in the dust case 81. The clean air passing through the dust filter 92 flows through the outer air passage holes 119 in the switching valve 122 and the air passage holes 118 in the filter supporting plate 93 and thence through the silencing material 131 and the exhaust openings 130 in the silencer plate 129, while cooling the suction means 78, and finally is exhausted to the outside from the exhaust outlet 73. As the cleaning operation continues, a large amount of dust is deposited on the filter element 88 and the dust filter 92. The dusts deposited on the filter element 88 are flue, paper chips, etc. which are relatively large in size and hence do not substantially adversely affect the suction ability of the cleaner even when they are accumulated in a large amount. However, the dust deposited on the dust filter 92 consist essentially of relatively fine dust such as sand, which clog the mesh of the dust filter 92 and reduce the suction ability of the cleaner, so that these dust must be removed from time to time.

To effect the removal of the dust deposited on the dust filter 92, the knob 125 is turned to shift the switching valve 122 through the connecting rod 126 and the shifting lever 127, so that the inner air passage holes 121 formed in the flat portion 117 of the switching valve 122 may be brought into registration with the air passage holes 120 formed in the central portion of the filter supporting plate 93 and the outer air passage holes 119 in the flat portion of said switching valve 122 and the air passage holes 118 in said filter supporting plate 93 may be closed as shown in FIG. 10e. When the suction means 78 is again set in motion under such condition, air sucked into the cleaner through the suction inlet 102 flows through the guide plate 105 to the blades 101 of the air turbine 99, to rotate said air turbine 99 at a high speed. Therefore, the rotary shaft 100 supporting said air turbine 99 also rotates at a high speed and the rotation thereof is transmitted to the small diameter gear 107 at the lower end of said rotary shaft 100 and thence to the large diameter gear 109 and the small diameter gear 110 of the intermediate gear 111 and the large diameter gear 113 meshing with said small diameter gear 110, with the result that the sliding collar 114 is driven around the hollow shaft 112 at a reduced speed suitable for dust-removing.

Since the sliding collar 114 carries the dust removing elements 95, said dust removing elements 95 slide on the back surface of the dust filter 92 while depressing the same to expand the meshes of said dust filter 92, and thus the dusts are removed efficiently.

On the other hand, the air passing through the turbine chamber 115 flows through the second air passageway D indicated by the solid line arrow in FIG. 9. Namely, the air flows through the cylindrical portion 116 of the switching valve 122, the inner air passage holes 121 in the flat portion 117 of said switching valve 122 and the air passage holes 120 in the filter supporting plate 118 and thence through the silencing material 131 and the exhaust openings 130 in the silencer plate 129 while cooling the suction means 78, and finally is exhausted to the outside from the exhaust outlet 73. In this case, the sucking force of the suction means 78 is not reduced since the flat portion 117 of the switching valve 122 and the sliding surface of the filter supporting plate 93 are maintained in sealing engagement under the biasing force of the coil spring 134.

The dust thus removed from the dust filter 92 falls on the upper surface of the filter element 88 and accumulates at a portion of the dust case 81 adjacent the inner wall 85 thereof as the filter element 88 has a trumpet-like shape in cross section. Where it is desired to remove the dust accumulated in the dust case 81, clamp means which is provided on the casing 70 and by which the dust case 81 and the cover 86 are secured to each other, though not apparent in the drawings, is released and the cover 86 is removed from the dust case 81, whereby said dust case can be simply demounted from the casing 1.

The dust case thus demounted is carried to a desired location and the dust therein is removed therefrom. In this case, the dust case is separated from the casing 70 integral with the suction means 70 and the cover 86 integral with the dust removing device 94, so that it can be handled easily and the dust can be disposed in a simple manner. If, in the cleaning operation, the air passage holes 120 and 118 in the filter supporting plate 93 are half-opened by the air passage holes 121 and 119 in the switching valve respectively as shown in FIG. 10d upon shifting said switching valve 122 by operating the knob 125, air is sucked by the suction means 78 flows into the cleaner from both the suction inlet 82 and the air inlet openings 102, and thereby the sucking force can be simply adjusted. Namely, the sucking force can be continuously varied optionally by varying the degree of opening of each air passage opening by manipulating the knob 125, so as to obtain the optimum sucking force for the specific condition of cleaning.

Moreover, since the adjustment of the sucking force can be achieved by adjusting the relative position of the filter supporting plate 93 and the switching valve 122 in sliding engagement therewith and yet such adjustment is possible exteriorly of the suction cleaner, there is no necessity of providing special sucking force adjusting means and a very effective cleaning operation can be obtained.

In the present invention, as described above, use is made as a driving source for the dust removing device, of the air turbine which is driven by the sucking force of the suction means and, therefore, it is unnecessary to provide an additional electric motor for driving the dust removing device as has been necessary heretofore, which is advantageous economically. Further, since the dust removing device is provided in the space defined by the cover, it is unnecessary to increase the size of the suction cleaner for the provision of such dust removing device and the suction cleaner can be provided in a compact form.

The electric vacuum cleaner of the invention is highly convenient in operation, owing to the facts that the air passage switching mechanism is simple in construction, including only the filter supporting plate and the switching valve slidably mounted on said filter supporting plate, and the switching between the first air passageway and the second air passageway can be easily effected exteriorly, and that the adjustment of the sucking force can also be attained in a simple manner.

Further, in the present invention the rotating state of the air turbine is visible from the outside through the transparent window. Therefore, whether or not the dust removing operation is carried out properly, can be readily inspected from the outside, and further the condition of the suction cleaner for the cleaning operation or dust removing operation can be identified, not only by the position of the knob but also by state of the air turbine, which is advantageous in ensuring the proper operation of the cleaner.

As described above, according to the present invention the first air passageway for a dust-containing air flow and the second air passageway for an air flow to rotate the dust removing air turbine are formed upstream of the suction means and the filter means is provided in said first air passage to catch the dust entrained in said first air flow, and further means is provided to selectively switch said first and second air passageways from one another. Therefore, the filter means is not subjected to an unnecessary force during the dust removing operation and the dust removing effect can be enhanced.

Further, since the air turbine is driven by making use of the sucking force of the suction means and the dust removing device is operated by the rotation of said air turbine, a positive dust removing operation can be obtained with a simple construction. Furthermore, the suction cleaner is low in cost and easy to handle.

In the case when the present invention is applied to a pot-type electric vacuum cleaner as shown in FIGS. 7 - 10, the dust collecting capacity of the dust collecting cavity can be increased by providing the air turbine-driven dust removing device on the underside of the cover and accordingly the period of continuous use of the cleaner can be prolonged, with excellent dust removing effect.

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