Abstract:
An electric cleaner head including a first bank of a plurality of spaced apart nozzles each including an interior passage having a narrower width than length slit. Sources of air flow including at least one suction source are connected to spaces between the subnozzles to generate air flow around a lowest edge of the subnozzles between the subnozzles and spaces between the subnozzles wherein the interior passages of the subnozzles are isolated from the suction source.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to an electric cleaner, and particularly to an electric cleaner efficient for cleaning dust embedded in carpet. 
     BACKGROUND OF THE INVENTION 
     Various approaches to improve the efficiency of electric cleaners for removing dust embedded in carpet have been reported and also marketed. However, none of the approaches is satisfactory and their cleaning efficiency cannot exceed a certain limitation. In particular, they are very poor for cleaning long pile carpet. 
     The following discussion reviews known approaches and comments on the reasons for their low efficiency. 
     A simple approach involves a straight air suction head. The suction head includes a rectangular suction box having a long left to right, hereafter abbreviated as “L-R”, dimension and a short fore to back, hereafter abbreviated as “F-B”, dimension. The lower face of the suction head has a long L-R opening for sucking dust. The lowest ends of the front and back walls of the suction head contact a carpet surface and suction flows through the pile just under the walls removing dust in the flow path. 
     In this simple case, air flow path in the pile is located near the lowest ends of the walls in a short-circuited manner between the outer and inner air of the wall and cannot extend to the deep or bottom region of carpet pile. This is the reason for the low efficiency. Increased fan motor power can increase flow speed/volume in the short-circuit path, but cannot extend the path to deeper regions. Dust can be dislodged and removed from the pile at a flow speed over a certain threshold velocity: Vth. Too much of an increase in flow velocity over Vth is meaningless. 
     A second known approach to carpet cleaning incorporates mechanical agitation such as vibration or beating. However, cleaners including mechanical agitation are not currently on the market due to their noise. Mechanical agitation is basically ineffective, because such agitation cannot reach to deep/bottom regions of carpet. Additionally, the air flow to convey the dislodged dust cannot reach to the deep/bottom regions of the carpet. 
     A third widely used approach incorporates a rotating brush made of rubber or bristles, driven by a motor or an air turbine. It is expected that such agitation with the brush may be effective to dislodge dust in pile. 
     It is, in fact, fairly effective, but cannot extend beyond certain limitations. For example, such agitation also cannot reach to the deep/bottom regions. Furthermore, a powerful high-speed rotating brush very easily removes pile fibers from carpet. This defect is fatal for a high-grade, expensive carpet. 
     A fourth approach includes many slender finger-like pipes (hereafter referred to as “finger pipes”) vertically arranged in a cleaning head. In such a device, pressurized fan-afterflow is fed to the top of the pipes. The pipes&#39; flow blows out from the bottom end of the pipes to clean the pile. 
     Similarly, L-R extending slits are vertically arranged in the head and the blowing flow is directed to the surface of the carpet. The finger-pipe example, disclosed in Japanese Laid Open Pat. SHOU 50-155057 (Negishi), is shown in FIG.  14 . 
     Examples of finger-pipes fed with room air (atmospheric pressure) are disclosed in Japanese Laid Open Pat. SHOU 63-122415 (Ariyoshi), HEI 1-256920 (Kadowaki). An example of small holes fed with room air is disclosed in Japanese Laid Open Utility Pat. SHOU 51-95266 (Nagasima). An example of a slit fed with room air is disclosed in Japanese Laid Open Utility Pat. SHOU 54-138467 (Urusibara). 
     In the above examples that include air either pressurized or room air directed to carpet, the bottom ends of the finger-pipes, the small holes, and the slit do not extend downward beneath the lowest ends of the head walls and only blow on the carpet surface. 
     These means that merely blow air toward the carpet surface are not effective, as the blowing air cannot penetrate into the deep regions of the pile due to the high flow resistance of pile. 
     The inventor of the present invention also disclosed a fifth approach in U.S. Pat. No. 5,647,092, including Pile Gorge Forming by means of mechanical contact with pile top. This gorge also has the effect of directing air flow reaching the bottom of the pile. However, its expected effect is decreased due to the following two reasons. The recirculated air jet, directed to the gorge, blows out the dust in the gorge bottom into suction air flow, but, unfortunately, also into the piles constituting both side walls of the gorge. An upflowing stream in the piles functioning to take out the dust is to be formed incorporating with the incoming flow through the piles just under the front and back walls. However, the flow resistance of pile is too high to form such an upstream. 
     A sixth approach to improve cleaning efficiency includes finger pipes extending downward into piles beneath the lowest ends of the walls at the cleaning head. An example of the sixth approach fed with pressurized air, as shown in FIGS. 15A and 15B, is disclosed in U.S. Pat. No. 3,268,942 to Rossnan. Another example fed with room air, as shown in FIGS. 17A and 17B, is disclosed in U.S. Pat. No. 4,594,749 to Waterman. A finger pipe array used solely for sucking air in piles, as shown in FIGS. 16A and 16B, is disclosed in U.S. Pat. No. 3,611,473 to Johnson. 
     This sixth approach can be expected to overcome the limitation that other known approaches discussed above cannot generate air flow to reach to the deep/bottom region of the carpet, because the tip or lowest end of the finger pipe can enter deep into the carpet. 
     However, this sixth approach is still insufficient. The fault is due to the finger pipe shape. The air just blowing out from the tip or lowest end of the finger pipe may have sufficient speed to dislodge the dues in the pile. However, the air speed decreases rapidly below the threshold Vth, as the air flows away from the tip in a two dimensional manner near the tip and then immediately diffuses upward in a three-dimensional manner. As a result, cleanable area is very localized to a region (δ in diameter) near the tip. Additionally, too greatly decreased flow speed cannot convey the dislodged dust through pile. 
     Furthermore, during the cleaning head stroke (stroke speed: Vst), an exposed time (Tex) of specific pile fiber to a speed flow higher than Vth (Tex=δ/Vst) is too short to dislodge any dust in the pile. Such exposed time Tex has to be longer than a certain threshold value Tth. 
     A seventh approach to improve cleaning efficiency is disclosed by Takemura (Japanese Laid Open Pat. SHOU 54-158066, and SHOU 55-153). Takemura discloses a head that has plural downwardly opening slits partly provided, as shown in FIGS. 18 B- 1  and B- 2 , on a front wall lower face and fed with room air from openings provided in the foreside of the front wall, as shown in FIG.  18 A. 
     At first glance, these slits may lead air flow into piles. However, the lower face of the front wall is flat, as shown in FIG. 18A, so the lower face cannot sink deep into piles. Takemura is only aiming to distribute suction power, P, more uniformly along an L-R direction as illustrated by curve “a” than the conventional distribution illustrated by curve “b”, as shown in FIG.  18 C. 
     SUMMARY OF THE INVENTION 
     The basic concept of the present invention is to generate direct air flow to reach the deep/bottom region of carpet and keep its blow speed in the pile over Vth over a period of time Tth. Hereafter, this concept is called “DARB”. 
     Inventions utilizing the DARB concept are discussed below in greater detail. 
     One embodiment of the present invention employs subnozzles  1  and/or slits  13 . Through the subnozzles and/or slits, blowing flow from pressurized or room air directed into the deep/bottom region of carpet, or sucking flow directly from deep/bottom pile can be provided, without obstruction of the pile flow resistance as shown in FIGS. 1A,  8 A and  8 B. 
     The subnozzles are arrayed in a bank. Each subnozzle includes a hollow rectangular pipe having a horizontal cross sectional shape having a narrow L-R dimension and a long F-B dimension. The front end and back end of the pipe are sharpened like a ship&#39;s bow and stern so as to decrease stroke resistance due to the pile, as shown in FIGS. 1B and 1C. 
     The slit has a long L-R dimension and is provided at the peak of the cross section of a front/back wall having an inverted mountain-like cross section, so as to locate it at the deepest part of the front wall in the pile, as shown in FIGS. 8A and 8B. The inverted mountain shape cross section allows the bottom ends of the wall to sink into carpet pile. 
     Preferably, subnozzles  1  are utilized for blowing air  3  and spacing intervals  2  of the subnozzles are utilized for suction flow  5  and generating turning flow  4  in the deep/bottom region of the carpet piles. 
     The blowing flow, turning flow, and suction flow have almost the same cross sectional flow area. Namely, diffusion is one dimensional. Therefore, high flow velocity is maintained in the pile along the F-B length of the subnozzles. The F-B length assures enough exposed time Tex over threshold time period Tth during the cleaning head stroke. 
     Dust larger than the nozzle width is arranged to be cleaned through the L-R long suction room  12  provided just in front or back of the subnozzle bank, as shown in FIGS. 3D and 3E. Dust much larger than the L-R long suction room  12  is arranged to be cleaned through a suction pipe prestage room  18 , as shown in FIG.  4 . 
     The front and/or back walls of the subnozzles is/are formed to have an inverted mountain-like cross sectional shape, so that their peak ridges can easily sink as deep as possible into carpet pile. The slit(s)  13  is/are provided at the peak ridge so that the air flow can reach directly to deeper/near-bottom regions of the carpet pile as shown in FIGS. 8A,  8 B,  2 B,  10 , and  11 . 
     These slits also play a role of conventional by-pass flow openings. By-pass flow opening is usually provided at the extreme of both left and right ends of a head to reduce stronger suction to the pile and the attendant too high stroke resistance. The conventional by-pass flow is a waste of fan power. However, according to the present invention, a part of the power for the conventional by-pass flow is utilized not only for stroke resistance reduction but also for enhancing the cleaning efficiency. 
     An additional slit can also be provided inside a head, as shown in FIG.  8 B. 
     The front and/or back wall can include the subnozzle bank. FIGS. 6A and 6B shows an example where a back wall is replaced with a subnozzle bank. 
     Insertion of subnozzle tip or slit into deep/bottom region of carpet pile causes high flow resistance due to longer path length in the pile. Plural fan operation in serial or in parallel can solve this problem. 
     The means of pile gorge forming, a modified version of U.S. Pat. No. 5,647,802, can be another means for carrying out the DARB concept, as the sucking or blowing flow can reach to the bottom of the gorge directly. 
     According to the present invention, it is preferable that the head is arranged so that the flow in the gorge is suction flow, as described below. According to this embodiment, air is sucked through the pile under the front/back walls of the suction head, reaches to the gorge, and is sucked further into L-R long suction room over the pile. The velocity of the leaving flow from the gorge should be high enough to convey the dislodged dust. Conventional mechanical contact means for gorge forming is so large that the suction room enclosing the contact means has too large a cross section to keep the flow velocity high enough. 
     In order to decrease the cross section, the present invention may include a cylinder shown in FIGS. 2A,  2 B and  10 , or a belt, shown in FIG. 11, as the contacter. Most of the cylinder extends out of the head or into its ceiling. 
     The present invention may also include openings in the lowest part of the left and/or right side wall(s) of the head located at a corresponding position to the gorge. Such openings provide sufficient high speed flow along the gorge in L-R direction to remove dust in the bottom of the gorge. 
     A gorge forming means also incorporating pressurized air such as recirculated flow is also disclosed in FIG.  2 B. 
     Jet  3  is directed to the shoulder of the gorge instead of the gorge bottom as in the prior art shown in FIG.  2 C. The penetrated jet flow into the pile turns fore and back. The fore flow also reaches into the gorge  10 . The fore flow, together with the flow  14  from the slit  13  forms the up-stream. The flows  4  and  14  dislodge dust in pile and convey the dust away. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     These and other more detailed and specific objects and features of the present invention will be more fully disclosed in the following, in which: 
     FIG. 1A is a left-right cross-sectional view of sub nozzles showing the principle of the DARB concept according to the present invention; 
     FIG. 1B is a front-back cross-sectional view of the subnozzle; 
     FIG. 1C is a top cross-sectional view of the subnozzle shown in FIG. 1B showing a ship-like shape; 
     FIG. 2A is a front-back cross-sectional view of a suction-type gorge forming cleaner head showing the DARB conceptual principle according to the present invention; 
     FIG. 2B is a front-back cross-sectional view of a suction or pressurized-air gorge forming cleaner head showing the DARB conceptual principle according to the present invention; 
     FIG. 2C is a cross-sectional view of a prior art nozzle design in the process of being utilized to clean carpet; 
     FIG. 3A is a perspective exploded view of a portion of recirculating flow head according to one embodiment of the present invention; 
     FIG. 3B is a top view of the embodiment shown in FIG. 3A; 
     FIGS. 3C,  3 D and  3 E are various cross-sectional view of the embodiment shown in FIG. 3A; 
     FIG. 4 is a partial left-right cross-sectional front view of a head of the embodiment shown in FIG. 3A; 
     FIG. 5A is a top view of a portion of a suction head, the subnozzles of which are fed with room air, according to another embodiment of the present invention; 
     FIG. 5B is a cross-sectional view of a head of the embodiment shown in FIG. 5A; 
     FIG. 6A is a cross-sectional view of a subnozzle provided at the back wall of a head of a further embodiment according to the present invention; 
     FIG. 6B is a cross-sectional view of an interval between the subnozzles of the embodiment shown in FIG. 6A; 
     FIG. 7A is a cross-sectional view of a subnozzle provided in the mid front-back space of a head and pushed down by springs according to a still further embodiment of the present invention; 
     FIG. 7B is a cross-sectional view of a suction interval between the subnozzles of the embodiment shown in FIG. 7A; 
     FIG. 8A is a cross-sectional view of a suction head, both walls of which have slits, according to yet another embodiment of the present invention; 
     FIG. 8B is a cross-sectional view of a suction head that has slits in both walls and also in the center according to a further additional embodiment of the present invention; 
     FIGS. 9A,  9 B and  9 C are schematic diagrams of plural fan/motor combinations according to the embodiment of the present invention; 
     FIG. 10 is a cross-sectional view of a suction head that has a pile gorge forming rigid cylinder according to another embodiment of the present invention; 
     FIG. 11 is a cross-sectional view of a recirculating flow head that has a pile gorge forming elastic cylinder according to yet another embodiment of the present invention; 
     FIGS. 12A,  12 B,  12 C and  13 A,  13 B,  13 C show cross-sectional views of prior art recirculating flow heads, which have pile gorge forming means; 
     FIG. 13D shows a cross-sectional view of a prior art suction head, which has a pile gorge forming means; 
     FIG. 14 shows a cross-sectional view of a prior art recirculating flow head, which has an array of finger pipes within the lowest wall level of a head; 
     FIGS. 15A and 15B show cross-sectional views of a prior art recirculating flow head that has an array of finger pipes extending beneath the lowest wall level; 
     FIGS. 16A and 16B show, respectively, a front and a sectional view of a prior art flow head that is constructed with only an array of fmger nozzles; 
     FIGS. 17A and 17B show, respectively, a partial cut-away front view and a cross-sectional view of a prior art head that has plural banks of finger pipes around a rotating cylinder, only the lowest bank is selected, extends beneath the lowest wall level, and is fed with room air; and 
     FIGS. 18A,  18 B- 1 ,  18 B- 2 , and  18 C show a prior art head, which has plural slits in the flat lowest face of the front wall, as shown in the bottom views FIGS. 18B-1 and  18 B- 2 , and wherein their slits are fed with room air, as shown in cross-sectional view FIG. 18A; and 
     FIG. 18C shows the effect of the slits to flatten the suction power distribution along a left-right direction. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Some embodiments of the present invention utilize subnozzles as a duct for direct air flow reach towards or from the bottom region of carpet pile. Other embodiments of the present invention utilize slits instead of or together with the subnozzles. 
     Additional embodiments of the present invention utilize the pile gorge as the duct for direct suction flow from the bottom of the gorge. 
     The following describes preferred embodiments of the present invention. 
     FIGS.  3 A- 3 E show a first embodiment; its operating principle is shown in FIG.  1 A. In FIGS.  1 A- 1 C and  3 A- 3 E, elements  1  are subnozzles and elements  2  are their spacing intervals. Usually, the width of spacing intervals  2  is chosen several times wider than the width of subnozzles  1 . Also in these figures, arrows  3  represent blowing flow, arrows  5  represent suction flow and arrows  4  represent turning flow. The lowest ends or tips of the subnozzles are inserted into deep/bottom region of pile. The turning flow  4  and sucked flow  5  created by the subnozzles in the carpet pile have nearly same high speed as the blowing flow  3 , since the flow from  3  to  5  is almost one dimensional due to the longer front-to-back length of subnozzles in comparison with the left-to-right width. Therefore, the flow  4  and  5  successfully remove dust embedded in pile. 
     Each subnozzle has the shape shown in FIGS. 1B and 1C. The front width of the subnozzles is narrow and the front and back ends are sharpened like a ship bow and stern in order to lessen stroke resistance as shown in FIGS. 1B and 1C. For carpet without a loop pile structure, a nose can be provided on the outer lowest portion of each of the front and back ends. The nose helps the subnozzles to sink into carpet pile. 
     If the stroke resistance is still high, a power assisted or power driven stroke will be included. 
     FIGS.  3 A- 3 E and  4  show an actual embodiment of a suction head including subnozzles according to the present invention. The suction head shown in FIGS.  3 A- 3 E and  4  includes a pressurized room  17  prestage to the subnozzles. The pressurized room  17  is elongated in a left-right direction and is connected to the after-flow of a suction fan or a separately provided pressure fan. The suction interval  2  shown in FIGS.  3 A- 3 E and  4  also conducts to a suction room  16  post to the subnozzles. The suction room  16  is elongated in a left-right direction. The sucked flow from the interval  2  moves to suction room  16  through passages  2 - 1 . Another left-right elongated and lower-face-open suction room  12  is provided for dust larger than the interval width. The flows of both suction rooms  16  and  12  jointly lead to a suction-pipe prestage room  18 , and then into suction pipe  19 . The suction-pipe prestage room  18  also serves as a suction port for dust much larger than room  12 . 
     FIGS. 5A and 5B show another embodiment of the present invention. According to the embodiment shown in FIGS. 5A and 5B, subnozzles are fed with room air through the filter  21 . Other aspects of the embodiment shown in FIGS. 5A and 5B are quite similar to the embodiment shown in FIGS.  3 A-E and  4 . 
     FIGS. 6A and 6B show another embodiment of the present invention that includes a bank of subnozzles in place of the back wall of a head. This is simpler than the embodiments shown in FIGS.  3 A- 3 E,  4 ,  5 A, and  5 B. In the embodiment shown in FIGS. 6A and 6B the bank of subnozzles can slide upward or downward so as to adapt to various lengths of pile. The bank can sink into pile under its own weight and suction force. Of course, this construction of up-down slidable subnozzle bank can also be applied to the embodiments shown in FIGS.  3 A- 3 E,  5 A and  5 B. 
     FIGS. 7A and 7B show a fourth embodiment of the present invention, where a bank of subnozzles is provided in the middle of a head and can also slide up/down. A flexible bellows-like member  37  is provided to seal the gap of the sliding surface and also to force the bank to sink into the pile. The bank can be motor-controlled to sink into appropriate depth. In this embodiment the rooms  12  and  16  are joined into one room  12 / 16 , simplifying the design. 
     For cleaning a flat floor, it is desirable for the subnozzle bank to be pulled up manually or automatically with a motor so as not to contact or damage the floor. 
     FIG. 8A illustrates a fifth embodiment of the present invention. Slits directly introducing room air into the pile are provided in both front and back walls at the lowest peak ridge of inverted-mountain-like cross-section. The room air can enter deep near the pile bottom without any flow resistance, which otherwise would be encountered as shown by the flow path  11 , and can penetrate through the pile as illustrated by the effective flow  14 . The experiments for a single slit only in the front wall provided almost the same cleaning efficiency as a conventional rotating brush cleaner for carpet-embedded dust and almost twice the efficiency for dust in a narrow deep groove. The flow in slit is an alternative of the conventional by-pass flow usually provided through the opening at both left and right ends of a simple suction type head and lessens stroke resistance without losing fan power in vain due to by-passing. 
     Another central slit can be provided as shown in FIG.  8 B. 
     Any head of this invention utilizing only room air can be used as an alternative to a conventional cleaning head. 
     FIGS.  9 A- 9 C illustrates a sixth embodiment of the present invention. The embodiment shown in FIGS.  9 A- 9 C includes combined operation of plural fan/motors  22  and  23 . The embodiment depicted in FIGS.  9 A- 9 C, includes flow control valves  24 ,  25 , and  26 . 
     High flow resistance caused by deep insertion of the subnozzle tips near the carpet pile can be solved by serial operation of the fan/motors and control valves, as shown in FIG.  9 B. The serial operation shown in FIG. 9B can provide a higher flow rate for a certain flow resistance than the parallel operation shown in FIG.  9 C. 
     The modified arrangement shown in FIG. 9A, where the fan/motor  23  is inversed, is effective to optimally control the suction flow  16  of the subnozzle bank and the flow of suction room  12  in FIGS.  3 A- 3 E,  4 ,  5 A and  5 B in a mutually independent manner. 
     The arrangement shown in FIG. 9A is effective for the cleaner of the present invention utilizing both pressurized air to blow and vacuum to suck from room air. Each blowing flow and suction flow can be provided and controlled by independent fan/motors respectively to optimize each condition. 
     FIG. 10 illustrates a seventh embodiment of the present invention. The embodiment shown in FIG. 10 includes a rotating cylinder  9  penetrating the ceiling  8  of the cleaning head. The lower surface of the cylinder  9  contacts the pile. The pile is bent forward by contact with front wall  6  during the stroke direction  30 . The pile is inversely bent backward by the contact with cylinder  9 . Thus, a gorge  10  is formed. Suction rooms  12  and their cross-sectional area are reduced by extending the cylinder beyond the head ceiling in comparison with the designs shown in FIGS.  12 A- 12 C and  13 A- 13 D. Higher flow speed can thereby be obtained. The cylinder can be of hollow mesh, allowing air flow through the surface. Alternatively the cylinder can have a solid surface not allowing the air flow through the surface. In the latter case, the cross-section of the suction room becomes much smaller. Driving wheel  31  turns the cylinder  9  in direction  28  and is belt-coupled via wheel  35 , belt  36  and wheel  34  to a stroke wheel  33  so as to change its driving direction according to the stroke direction. Idle roller  32  supports the cylinder in position. The slits  13  in front wall  6  and back wall  7  serve the same function as the slits in the embodiment shown in FIGS. 8A and 8B. The air leaking through the gap  29  at the cylinder-penetrating part of the ceiling can prevent the gap  29  from being clogged with dust dislodged in the head. 
     An eighth embodiment of the present invention may also be explained by referring to FIG.  10 . According to the eighth embodiment, the openings (not shown) to admit air toward the gorge  10  can be provided on the bottom of both side walls of the head at locations corresponding to the gorge F-B position. Thus, air admitted by openings in the side walls sweeps out bottom-dust in L-R direction, with minimum dust-blow-out into gorge shoulders. 
     FIG. 11 illustrates a ninth embodiment of the present invention. In the embodiment shown in FIG. 11, pressurized room  17  is provided to feed a jet stream  3  through the mesh surface of the cylinder  9  into pile. The jet is directed to the shoulder of the gorge and penetrates into pile to form a flow  4 . The flow  4  meets the flow  14  from the slit  13  at the gorge  10  and goes up into suction room  12  through the open gorge. The cylinder  9  is made elastic and deforms as shown in FIG. 11, for enhancing better contact with carpet pile. 
     Others of the ninth embodiment are quite similar to the embodiment shown in FIG.  10 . 
     Additional variations to the present invention may include introducing agents for flavoring, static charge eliminating, cleaning, sterilizing, anti-fungus processing, etc. in the flow path of room air or pressurized air into the pile. 
     Advantages of the present invention include realization of high cleaning efficiency even for long piled carpet; eliminating rotating brushes, agitating beaters, etc.; silent operation; no damage to precious carpet; simple design; light weight; washable; usable for both carpet and flat floors; and usable for both dry dust and liquids.