WO2009069274A1

WO2009069274A1 - Electric vacuum cleaner

Info

Publication number: WO2009069274A1
Application number: PCT/JP2008/003438
Authority: WO
Inventors: Toshinobu Hidaka; Minoru Murakami; Chie Sugiyama; Makio Hanzawa
Original assignee: Toshiba Corp; Toshiba Consumer Electronics Holdings Corp; Toshiba Home Appliances Corp
Current assignee: Toshiba Corp; Toshiba Lifestyle Products and Services Corp
Priority date: 2007-11-26
Filing date: 2008-11-21
Publication date: 2009-06-04
Anticipated expiration: 2010-05-26
Also published as: EG25887A; EP2211678A4; KR20120003955A; CN101820806B; CN101820806A; KR20100063810A; JP2009125399A; KR101165898B1; RU2424758C1; EP2211678B1; KR101216909B1; JP5112022B2; EP2211678A1

Abstract

In a vacuum cleaner main body 1 with electric blowers 5A, 5B housed therein, a common dust collecting chamber 4 is provided which communicates with a suction side of each of the electric blowers 5A, 5B. A controlling means 6 is provided which is capable of controlling the driving of the electric blowers 5A, 5B independently. Check valve units 43A, 43B for preventing air from flowing backward to the dust collecting chamber 4 side are provided in accordance with the electric blowers 5A, 5B. Even if either of the electric blowers 5A, 5B is driven, the check valve unit 43A, 43B prevents air from being sucked into the dust collecting chamber 4 side from the stopping electric blower 5B, 5A, and suction force can be secured.

Description

Description ELECTRIC VACUUM CLEANER

Technical Field

[0001] The present invention relates to an electric vacuum cleaner including a plurality of electric blowers. Background Art

[0002] Such kinds of electric vacuum cleaners have conventionally included a vacuum cleaner main body with a plurality of electric blowers housed in parallel therein. In the vacuum cleaner main body, a dust collecting chamber is provided with which suction sides of the electric blowers commonly communicate. Additionally, in the vacuum cleaner main body, a controlling portion as a controlling means for making the electric blowers independently drive is provided (see, for example, Patent Citation 1). Patent Citation 1 : Japanese Laid-Open Patent Publication No. 2007-20765 Disclosure of Invention Technical Problem

[0003] However, there has been a problem that, in the above electric vacuum cleaner, in the case where, for example, either of the electric blowers is driven and the other electric blower is stationary, negative pressure of the driving electric blower makes air flow backward from an exhaust side to a suction side of the non-driving electric blower and forms an air passage, through which the air is sucked into a suction side of the driving electric blower, and suction power cannot be secured.

[0004] The present invention has been made in view of the above problem, and aims at providing an electric vacuum cleaner capable of securing the suction power even in the case where any one of the plurality of electric blowers is driven. Technical Solution

[0005] An electric vacuum cleaner of the present invention includes: a vacuum cleaner main body with a plurality of electric blowers housed therein; a common dust collecting chamber which communicates with a suction side of each of the electric blowers; a controlling means capable of making the electric blowers independently drive; and backflow preventing means which are provided in accordance with the electric blowers and prevent air from flowing backward to the dust collecting chamber side.

[0006] Additionally, an electric vacuum cleaner of the present invention includes: a controlling means capable of performing control for driving only any one of the plurality of electric blowers and stopping the other electric blowers, and control for driving all of the plurality of the electric blowers; and backflow preventing means which are provided in accordance with the other electric blowers and prevent air from flowing backward to the dust collecting chamber side.

[0007] Further, an electric vacuum cleaner of the present invention includes a controlling means capable of, when driving one of the plurality of electric blowers, driving the other electric blowers so that no air flows backward to the dust collecting chamber side.

Advantageous Effects

[0008] According to the present invention, even in the case where any one of a plurality of electric blowers is driven, backflow preventing means provided in accordance with the electric blowers prevent air from being sucked into a dust collecting chamber side from the other stationary electric blowers, and suction power can be secured.

[0009] Additionally, according to the present invention, even in the case where only one of the plurality of electric blowers is driven, backflow preventing means provided in accordance with the other electric blowers prevent air from being sucked into the dust collecting chamber side from the other stationary electric blowers, and the suction power can be secured.

[0010] Further, according to the present invention, even in the case where one of the plurality of electric blowers is driven, the other electric blowers are driven so that no air flows backward to the dust collecting chamber side, and thus the suction power can be secured. Brief Description of the Drawings

[0011] [fig.1] Fig. 1 is an explanatory plan view showing an electric vacuum cleaner of a first embodiment of the present invention in which only one of electric blowers is driven. [fig.2]Fig. 2 is an explanatory plan view showing the electric vacuum cleaner in which only the other electric blower is driven.

[fig.3]Fig. 3 is an explanatory plan view showing the electric vacuum cleaner in which all the electric blowers are driven.

[fig.4]Fig. 4(a) is a vertical cross sectional view showing a backflow preventing means of the electric vacuum cleaner. Fig. 4(b) is an enlarged vertical cross sectional view showing a part of the backflow preventing means. [fig.5]Fig. 5 is a perspective view of the backflow preventing means, [fig.6] Fig. 6 is a perspective view of the electric vacuum cleaner. [fig.7]Fig. 7 is an explanatory plan view showing an electric vacuum cleaner of a second embodiment of the present invention in which only one of the electric blowers is driven.

[fig.8]Fig. 8 is an explanatory plan view showing the electric vacuum cleaner in which only the other electric blower is driven. [fig.9]Fig. 9 is an explanatory plan view showing the electric vacuum cleaner in which all the electric blowers are driven.

[fig.10] Fig. 10 is an explanatory plan view showing an electric vacuum cleaner of a third embodiment of the present invention in which only one of the electric blowers is driven.

[fig.1 l]Fig. 11 is an explanatory plan view showing the electric vacuum cleaner in which all the electric blowers are driven.

[fig.12] Fig. 12 is an explanatory plan view showing an electric vacuum cleaner of a fourth embodiment of the present invention in which only one of the electric blowers is driven.

[fig.l3]Fig. 13 is an explanatory plan view showing the electric vacuum cleaner in which all the electric blowers are driven.

[fig.14] Fig. 14 is an explanatory plan view showing an electric vacuum cleaner of a fifth embodiment of the present invention in which one of the electric blowers is driven and the other electric blower is subjected to backflow-preventing-driving. [fig.l5]Fig. 15 is an explanatory plan view showing the electric vacuum cleaner in which one of the electric blowers is subjected to the backflow-preventing-driving and the other electric blower is driven.

[fig.16] Fig. 16 is an explanatory plan view showing the electric vacuum cleaner in which all the electric blowers are driven. Explanation of Reference [0012] 1 Vacuum cleaner main body

4 Dust collecting chamber

5A, 5B Electric blower

6 Controlling means

43 A, 43B, 43C Check valve unit being opening-closing means as backflow preventing means

46 Opening-closing valve body Best Mode for Carrying Out the Invention [0013] Hereinafter, an electric vacuum cleaner of a first embodiment of the present invention will be described with reference to Figs. 1 to 6.

[0014] In Figs. 1 to 3 and 6, the reference symbol 1 denotes a vacuum cleaner main body, and the vacuum cleaner main body 1 includes a hollow main body case 2. The inside of the main body case 2 is partitioned, by a partitioning wall 8, into a dust collecting chamber 4 which is located at the front end of the inside and to/from which a dust collecting pack 3 as a filter is attached/detached, electric blowers 5A, 5B located at the rear side thereof (hereinafter, at least either of the electric blowers 5 A, 5B, or as a whole, will be sometimes simply referred to as an electric blower 5) and an electric blower chamber 7 with a controlling means 6 and a cord reel (not shown) housed therein. Additionally, a main body suction port 11 communicating with the dust collecting chamber 4 is opened in the front of the main body case 2, and a hose body 12 as a slender and approximately cylindrical connection tube capable of bending is communication-connected with the main body suction port 11. Further, a hand operating part 13 for selecting an operation mode of the electric blower 5 is provided at the top end of the hose body 12, a plurality of setting buttons 14 each for setting a driving state, operation mode, of the electric blower 5 and the like to a predetermined state are provided on the hand operating part 13, and a gripping part 15 to be gripped by a worker in cleaning is protruded on a base end side of the hand operating part 13. Further, a slender and approximately cylindrical extension tube 16 capable of telescoping is attachably/detachably communication-connected with the top end of the hand operating part 13. Further, a floor brush 17 as a suction port body, which is put on, for example, a carpet to be cleaned on a floor surface and sucks dust on the carpet, is attachably/detachably communication-connected with the top end of the extension tube 16.

[0015] The main body case 2 includes: a lower case 21 with a partitioning wall 8 and an opened upper side; a lid body 22 for opening and closing an upper portion of the dust collecting chamber 4 located at the front side of the lower case 21; and an upper case 23 for closing an upper portion of the electric blower chamber 7 located at the rear side of the lower case 21. Additionally, many exhaust holes 24 are bored in the main body case 2.

[0016] Traveling wheels 25 having a large diameter for traveling the vacuum cleaner main body 1 on the floor surface are rotatably and pivotally supported on both sides of the electric blower chamber 7 located at the rear side of the lower case 21, and a turn wheel (not shown) as a driven wheel is turnably provided on a bottom, which faces the floor surface, of the dust collecting chamber 4 located at the front side of the lower case 21.

[0017] The dust collecting pack 3 is, for example, a disposable paper pack, and includes a mouth frame (not shown) to be fixed to the dust collecting chamber 4 and a pack body 28 in the form of pouch attached to the mouth frame.

[0018] The dust collecting chamber 4 is formed commonly to the electric blowers 5 A, 5B.

[0019] The electric blower 5 includes a centrifugal fan 31 and a motor 32 for rotating the centrifugal fan 31, and the centrifugal fan 31 and the motor 32 are housed in a cylindrical body case 33. Additionally, the electric blowers 5A, 5B have centrifugal fans 31 on the front side and motors 32 on the rear side respectively, and juxtaposed in the electric blower chamber 7 in its width direction.

[0020] The motor 32 is driven by electric power fed from the outside. [0021] The cylindrical body case 33 includes an approximately cylindrical case main body 33a having a closed rear side and an opened front side, and a fan cover 33b engaged with the end of the opened front side of the case main body 33a. The motor 32 is housed in the case main body 33a, and the centrifugal fan 31 is housed in the fan cover 33b. Additionally, a plurality of quadrangular exhaust ports 33c communicating with the electric blower chamber 7 are opened in the case main body 33 a, and a circlular suction port 33d communicating with the dust collecting chamber 4 is opened at the center of the front end of the fan cover 33b. Further, in the cylindrical body case 33, the rear end of the case main body 33a is elastically supported on the main body case 2 (lower case 21) by a rear portion supporting rubber (not shown) as an elastic supporting member, a circumferential edge of the fan cover 33b is elastically supported on the main body case 2 (lower case 21) by an annular front portion supporting rubber 36 which is a sealing member as an elastic supporting member, and the suction port 33d is airtightly connected to the dust collecting chamber 4 via the partitioning wall 8 so as not to communicate with the electric blower chamber 7.

[0022] The controlling means 6 is a circuit board including a switching element such as a triac, and the like, and can make the electric blowers 5A, 5B independently drive by phase angle control in accordance with an operation mode input with the setting button 14. For example, in an operation mode, such as a weak mode, for applying relatively small suction power (operation mode for applying suction power half or less of full power), the controlling means 6 drives either of the electric blowers 5A, 5B and stops the other, and in an operation mode, such as a strong mode, for applying relatively large suction power (operation mode for applying suction power half or more of full power), the controlling means 6 drives both the electric blowers 5 A, 5B.

[0023] A power cord (not shown) having a plug portion at its top end is wound around the cord reel so as to be freely pulled out.

[0024] On the other hand, the electric blower chamber 7 is formed commonly to the electric blowers 5A, 5B and communicates with the outside of the main body case 2 via the exhaust holes 24.

[0025] Round communication holes 41A, 41B making the dust collecting chamber 4 and the electric blower chamber 7 communicate with each other and each having a large diameter are opened in the partitioning wall 8 at positions facing the front sides of the electric blowers 5A, 5B respectively. Filters 42A, 42B are attached to the upstream sides, front portions, of the communication holes 41A, 41B respectively, and check valve units 43 A, 43B are attached to the rear portions of the communication holes 4 IA, 4 IB respectively, the valve unit being an opening-closing means as a backflow preventing means.

[0026] Moreover, hereinafter, at least either of the communication holes 4 IA, 4 IB, or as a whole, will be sometimes simply referred to as a communication hole 41, at least either of the filters 42A, 42B, or as a whole, will be sometimes simply referred to as a filter 42, and at least either of the check valve units 43 A, 43B, or as a whole, will be sometimes simply referred to as a check valve unit 43.

[0027] The upstream side, front portion, of the communication hole 41 is covered with the filter 42.

[0028] The filter 42 collects dust which cannot be collected by the dust collecting pack 3.

[0029] As shown in Figs. 4 and 5, in the check valve unit 43, a plurality of opening-closing valve bodies 46 are rotatably attached to a frame 45.

[0030] The frame 45 includes, integrally in an axis direction, front and rear direction, a cylindrical frame 48 as a cylindrical first frame located at the upstream side and an angular tube-shaped frame 49 as an angular tube-shaped second frame located at the downstream side.

[0031] The cylindrical frame 48 is airtightly connected to the downstream side of the communication hole 41.

[0032] The angular tube-shaped frame 49 communicates with the downstream side of the cylindrical frame 48, faces the suction port 33d of the electric blower 5, is to be airtightly connected to the suction ports 33d, and includes upper wall 49a and lower wall 49b for vertically partitioning the inside of the main body case 2, and side walls 49c, 49c continuing to the upper wall 49a and lower wall 49b and for horizontally partitioning the inside.

[0033] Round holes 51 each for pivotally supporting the opening-closing valve body 46 rotatably are bored in the side walls 49c, 49c. The holes 51 are vertically arranged approximately in a straight line.

[0034] Each opening-closing valve body 46 is a flap portion formed of a relatively light member such as synthetic resin and in a laterally-long and quadrilateral plate shape, and the upper portions of both sides thereof are respectively inserted into the hole 51 so that the valve body 46 is pivotally supported so as to be rotatable in the front and rear direction (vertical direction). Further, the opening-closing valve bodies 46 are successively arranged vertically at an approximate interval, and the vertical size thereof is set so as to be larger than an interval between the holes 51, 51. Accordingly, a lower end 46a of the upper opening-closing valve body 46 can come into contact with a rear portion on the upper end side of the lower opening-closing valve body 46.

[0035] The lower end 46a side of each opening-closing valve body 46, as indicated by imaginary lines in Figs. 4(a) and 4(b), rotates backward and upward so as to be approximately horizontal by negative pressure of the corresponding driving electric blower 5, and opens the angular tube- shaped frame 49. When the corresponding electric blower 5 is stopped, the lower end 46a side, as indicated by solid lines in Figs. 4(a) and 4(b), rotates forward and downward by its own weight and the valve body 46 closes. In this state, when the other electric blower 5 is driven, the lower end 46a side is sucked to an upper portion of the underlying opening-closing valve body 46 by negative pressure of the other driving electric blower 5 via the communication hole 41 and the dust collecting chamber 4 so that the inside of the frame 45 is closed. At this time, the lower end 46a of the lowest opening-closing valve body 46 is sucked to a step part 49d between the lower wall 49b and the cylindrical frame 48. In other words, each opening-closing valve body 46 can be opened and closed by a pressure difference (wind power) between the upstream side and downstream side.

[0036] Next, operation of the first embodiment will be described.

[0037] In the case of using a new dust collecting pack 3, it is first attached to the dust collecting chamber 4 exposed by opening the lid body 22, the lid body 22 is closed, and then the power cord is pulled out and the plug portion at the top end of the cord is connected to an outlet. In the case of not using the new dust collecting pack 3, the lid body 22 is neither opened nor closed, the power cord is pulled out and the plug portion is connected to the outlet.

[0038] The gripping part 15 of the hand operating part 13 of the hose body 12 connected to the main body suction port 11 is gripped, and a predetermined setting button 14 is operated. Thus, a control circuit in the vacuum cleaner main body 1 drives the motor 32 and rotates the centrifugal fans 31 so that the negative pressure is generated. The floor brush 17 connected to the top end side of the hose body 12 via the extension tube 16 is moved backward and forward on the floor surface with the gripping part 15.

[0039] At this time, for example, in the case where a mode, such as a weak mode, for applying relatively small suction power is selected with the setting button 14, the controlling means 6 drives either of the electric blowers 5A or 5B in a predetermined order.

[0040] For example, the controlling means 6 drives not the electric blower 5 first driven in the preceding drive but the other electric blower 5. That is, in the case where the electric blower 5A is first driven in the preceding drive, the electric blower 5B is first driven in this drive, and in the case where the electric blower 5B is first driven in the preceding drive, the electric blower 5A is first driven in this drive. Moreover, in the case where both the electric blowers 5A, 5B are simultaneously driven in the preceding drive, whichever of the electric blowers 5A, 5B may be first driven.

[0041] As shown in Fig. 1, for example, in the case where the electric blower 5 A is driven, the electric blower 5B is stationary, and negative pressure generated by the driving of the electric blower 5A starts acting on the electric blower 5B side from the dust collecting chamber 4 via the communication holes 4 IA, 4 IB.

[0042] At this time, in the check valve unit 43B, since the pressure of the downstream side of each opening-closing valve body 46 is larger than that of the upstream side thereof, each opening-closing valve body 46 closed by rotation downward of the lower end 46a by its own weight is sucked to the upstream side, the lower end 46a of each opening- closing valve body 46 is sucked to the upper end side of the underlying opening- closing valve body 46, the lower end 46a of the lowest opening-closing valve body 46 is sucked to the step part 49d, the inside of the frame 45 is closed, as indicated by the solid lines in Figs. 4(a) and 4(b), and air is prevented from flowing backward from the exhaust port 33c to the suction port 33d of the electric blower 5B.

[0043] Additionally, since the pressure of the upstream side of each opening-closing valve body 46 is larger than that of the downstream side thereof in the check valve unit 43A, the lower end 46a of each opening-closing valve body 46 rotates backward and upward around the upper end side thereof until each opening-closing valve body 46 becomes approximately horizontal, the inside of the frame 45 is opened, and air is sucked into only the electric blower 5A from the main body suction port 11 side via the dust collecting chamber 4, as indicated by the imaginary lines in Figs. 4(a) and 4(b).

[0044] Similarly, as shown in Fig. 2, in the case where the electric blower 5B is driven, the electric blower 5A is stationary, and negative pressure generated by the electric blower 5B acts on the hose body 12, the extension tube 16 and the floor brush 17 via the main body suction port 11 side, and starts acting on the electric blower 5A side from the dust collecting chamber 4 via the communication holes 4 IB, 4 IA.

[0045] At this time, in the check valve unit 43A, since the pressure of the downstream side of each opening-closing valve body 46 is larger than that of the upstream side thereof, each opening-closing valve body 46 closed by rotation downward by its own weight of the lower end 46a is sucked to the upstream side, the lower end 46a of each opening- closing valve body 46 is sucked to the upper end side of the underlying opening- closing valve body 46, the lower end 46a of the lowest opening-closing valve body 46 is sucked to the step part 49d, the inside of the frame 45 is closed, as indicated by the solid lines in Figs. 4(a) and 4(b), and air is prevented from flowing backward from the exhaust port 33c to suction port 33d of the electric blower 5A.

[0046] Additionally, since the pressure of the upstream side of each opening-closing valve body 46 is larger than that of the downstream side thereof in the check valve unit 43B, the lower end 46a of each opening-closing valve body 46 rotates backward and upward around the upper end side thereof until each opening-closing valve body 46 becomes approximately horizontal, the inside of the frame 45 is opened, and air is sucked into only the electric blower 5B from the main body suction port 11 side via the dust collecting chamber 4, as indicated by the imaginary lines in Figs. 4(a) and 4(b).

[0047] Further, for example, in the case where an operation mode, such as a strong mode, for applying relatively large suction power is selected by the setting button 14, the con- trolling means 6 drives both the electric blowers 5 A, 5B as shown in Fig. 3.

[0048] Consequently, since the pressure of the downstream side of each opening-closing valve body 46 becomes larger than that of the upstream side thereof in the check valve units 43 A, 43B, the lower end 46a of each opening-closing valve body 46 rotates backward and upward around the upper end side thereof until each opening-closing valve body 46 becomes approximately horizontal, the inside of the frame 45 is opened, and air is sucked into the electric blowers 5A, 5B from the main body suction port 11 side via the dust collecting chamber 4, as indicated by the imaginary lines in Figs. 4(a) and 4(b).

[0049] Then, air sucked together with dust from the top end of the floor brush 17 by the negative pressure of the electric blower 5 becomes suction air and is sucked together with the dust into the dust collecting pack 3 via the extension tube 16, the hose body 12 and the main body suction port 11, and the contained dust is collected when the air containing the dust passes through the pack body 28 of the dust collecting pack 3.

[0050] The air, which has passed through the pack body 28, passes through the filters, is then sucked into the suction ports 33d of the electric blower 5 via the communication holes, passes through the inside of the cylindrical body cases 33 of the electric blower 5, is exhausted as exhaust air from the exhaust ports 33c while cooling the motors 32, and exhausted from the electric blower chamber 7 to the outside of the main body case 2 via the exhaust holes 24.

[0051] As described above, according to the first embodiment, even in the case where any one of the plurality of electric blowers 5, either of the electric blowers 5 A, 5B, is driven, the check valve unit 43B or 43A as a backflow preventing means, the units 43A, 43B being provided on the electric blowers 5A, 5B respectively, prevents air from being sucked into the dust collecting chamber 4 side from the other stationary electric blower 5, electric blower 5B or 5 A, the negative pressure of the electric blower 5 can be completely applied to the floor brush 17 side from the main body suction port 11, and thus suction power can be secured.

[0052] Additionally, since the check valve unit 43, which is an opening-closing means, is adopted as a backflow preventing means, the backflow preventing means can be easily realized.

[0053] Further, since the check valve unit 43 is opened and closed by the pressure difference between the upstream side and downstream side, no power source, such as a motor, for opening and closing the check valve unit 43 is required to be provided separately, the structure of the electric vacuum cleaner can be simplified, costs are reduced, and power can be saved.

[0054] Specifically, since the check valve unit 43 includes the flap-shaped opening-closing valve body 46, which rotates downward by its own weight by stopping of the electric blower 5 and closes, the check valve unit 43 can be easily realized.

[0055] The check valve unit 43 can be easily built in the vacuum cleaner main body 1 since the frame 45 and each opening-closing valve body 46 are integrally made as a unit.

[0056] Additionally, the electric blowers 5A, 5B are driven at a predetermined order, for example alternately, for each start of the electric vacuum cleaner, and thus the lives of the electric blowers 5A, 5B can be made approximately twice.

[0057] Further, since the electric vacuum cleaner is equipped with, a plurality of, for example, two electric blowers 5A, 5B, the suction power can be improved compared with the case where one electric blower is used, and efficiency is improved compared with the case where the same suction power is obtained by one electric blower.

[0058] Additionally, when the suction power of the electric vacuum cleaner is lowered, since the electric blowers 5A, 5B are controlled so that inputs of the electric blowers 5A, 5B are not simultaneously lowered, that is, only one of the electric blowers 5 is driven and the other electric blower 5 is stopped, the efficiency is further improved.

[0059] Moreover, even if the check valve units 43 are respectively provided at the exhaust port 33c sides of the electric blowers 5 or are respectively provided on the suction port 33d side of one of the electric blowers 5 and at the exhaust port 33c side of the other electric blower 5 in the first embodiment, an operation-effect similar to that of the first embodiment can be obtained.

[0060] Next, a second embodiment will be described with reference to Figs. 7 to 9.

Moreover, the same reference symbol is attached to each part having the same constitution and operation as that of the first embodiment, and description thereof will be omitted.

[0061] In the second embodiment, the electric blower chamber 7 is partitioned into electric blower chambers 7A, 7B corresponding to the electric blowers 5A, 5B respectively, and the check valve units 43A, 43B are attached to the upstream sides of the electric blower chambers 7A, 7B respectively in the first embodiment.

[0062] That is, a partitioning wall 55 is formed on the partitioning wall 8 so as to continue approximately straight from the rear portion of the partitioning wall 8 to the rear portion of the main body case 2, and the electric blower chamber 7 is partitioned into the electric blower chambers 7A, 7B by the partitioning wall 55.

[0063] Accordingly, the electric blower chambers 7A, 7B communicate with the exhaust sides (downstream sides) of the electric blowers 5A, 5B via the exhaust ports 33c respectively.

[0064] Similar to the first embodiment, in the case where the operation mode, such as a weak mode, for applying relatively small suction power is selected with setting button 14, the controlling means 6 drives the electric blower 5 A as shown in Fig. 7, or drives the electric blower 5B as shown in Fig. 8, and thus the pressure of the downstream side becomes larger than that of the upstream side in the check valve unit 43B or 43A, each opening-closing valve body 46 rotates downward to close, and air is prevented from flowing backward from the electric blower 5B or 5A and sucked into only the electric blower 5A or 5B from the main body suction port 11 side via the dust collecting chamber 4. Additionally, in the case where the operation mode, such as a strong mode, for applying relatively large suction power is selected with the setting button 14, the controlling means 6 drives both the electric blowers 5A, 5B as shown in Fig. 9, and thus the pressure of the upstream side becomes larger than that of the downstream side in the check valve units 43A, 43B, each opening-closing valve body 46 opens, and air is sucked into the electric blowers 5A, 5B from the main body suction port 11 side via the dust collecting chamber 4.

[0065] Consequently, even in the case where any one of the plurality of electric blowers 5, either of the electric blowers 5 A, 5B, is driven, the check valve units 43 A or 43B, the units 43A, 43B being provided in accordance with the electric blowers 5A, 5B respectively, prevents air from being sucked into the dust collecting chamber 4 side from the other stationary electric blower 5, electric blower 5B or 5 A, the negative pressure of the electric blower 5 can be completely applied to the floor brush 17 side from the main body suction port 11, and the operation-effect similar to that of the first embodiment can be obtained.

[0066] Additionally, since the electric blower chamber 7 is partitioned into the electric blower chambers 7 A, 7B in accordance with the electric blowers 5 A, 5B, airtightness between the electric blowers 5A, 5B and the electric blower chamber 7 can be easily secured and air leakage in the driving of the electric blower 5 can be more reliably prevented.

[0067] Moreover, even if the check valve units 43A, 43B are provided at the exhaust sides of the electric blowers 5A, 5B in the electric blower chambers 7A, 7B respectively or the check valve units 43 are provided at the suction side of one of the electric blowers 5 and the exhaust side of the other electric blower 5 in the second embodiment, an operation-effect similar to that of the third embodiment can be obtained.

[0068] Additionally, although the two electric blowers 5 are used in each embodiment, for example, three electric blowers can be similarly used.

[0069] Next, a third embodiment will be described with reference to Figs. 10 and 11.

Moreover, the same reference symbol is attached to each part having the same constitution and operation as that of each of the above embodiments, and description thereof will be omitted.

[0070] In the third embodiment, the controlling means 6 can perform control for driving either of the electric blowers 5 and stopping the other electric blower 5, and control for driving all the electric blowers 5 in the first embodiment. In other words, the con- trolling means 6 drive-controls the electric blowers 5 so that either of the electric blowers 5 is driven prior to the other electric blower 5. The check valve unit 43 is arranged in accordance with the other electric blower 5.

[0071] In the third embodiment, the controlling means 6, for example in the case where the electric blower 5A is constantly driven and shifting to the operation mode for applying relatively large suction power is made in cleaning, can properly drive the electric blower 5B additionally as necessary, and a check valve unit 43C, which is an opening- closing means as a backflow preventing means, is arranged in accordance with only the electric blower 5B. In other words, driving order is set to the electric blower 5.

[0072] Additionally, the check valve unit 43C is similar in constitution to the check valve unit 43 of the first embodiment.

[0073] For example, in the case where the operation mode, such as a weak mode, for applying relatively small suction power is selected with setting button 14, the controlling means 6, as shown in Fig. 10, drives the electric blower 5A, and thus the pressure of the downstream side becomes larger than that of the upstream side in the check valve unit 43C, each opening-closing valve body 46 rotates downward to close, and air is prevented from flowing backward from the electric blower 5B and sucked into only the electric blower 5A from the main body suction port 11 side via the dust collecting chamber 4. Additionally, for example, in the operation mode, such as a strong mode, for applying relatively large suction power is selected with the setting button 14, the controlling means 6 drives both the electric blowers 5 A, 5B as shown in Fig. 11, and thus the pressure of the upstream side becomes larger than that of the downstream side in the check valve units 43C, each opening-closing valve body 46 opens, and air is sucked into the electric blowers 5A, 5B from the main body suction port 11 side via the dust collecting chamber 4.

[0074] Consequently, even in the case where only one of the plurality of the electric blowers 5 (electric blower 5A) is driven, the check valve unit 43C provided in accordance with the other electric blower 5 (electric blower 5B) prevents air from being sucked into the dust collecting chamber 4 side from the other stopping electric blower 5 (electric blower 5B), the negative pressure of the electric blower 5 is completely applied to the floor brush 17 side from the main body suction port 11, the suction power can be secured, for example, and the operation-effect similar to that of the first embodiment can be obtained.

[0075] Additionally, since the electric blower 5A is constantly driven in cleaning, control of the driving of the electric blower 5 by the controlling means 6 can be simplified and the check valve unit 43 may be provided on either of the electric blowers 5, compared with the case where drive switching is made between the electric blowers 5 A, 5B. Thus, the electric vacuum cleaner can be simplified. [0076] Moreover, even if the check valve unit 43C is provided at each exhaust port 33c side of the electric blower 5B in the third embodiment, an operation-effect similar to that of the third embodiment can be obtained in constitution.

[0077] Next, a fourth embodiment will be described with reference to Figs. 12 and 13.

[0078] In the fourth embodiment, the controlling means 6 can perform control for driving either of the electric blowers 5 and stopping the other electric blower 5, and the check valve unit 43 is arranged in accordance with the downstream side of the other electric blower 5, in the second and third embodiments.

[0079] In the fourth embodiment, similar to the third embodiment, the controlling means 6 drives the electric blower 5 A prior to the electric blower 5B, and the check valve unit 43C is arranged on the downstream side of the electric blower 5B of the electric blower chamber 7B corresponding to the electric blower 5B.

[0080] That is, the controlling means 6, for example, in the case of constantly driving the electric blower 5A and shifting to the operation mode for applying relatively large suction power in cleaning, can properly drive the electric blower 5B additionally as necessary.

[0081] In the case where the operation mode, such as a weak mode, for applying relatively small suction power is selected with setting button 14, the controlling means 6 drives the electric blower 5A as shown in Fig. 12, and thus the pressure of the downstream side becomes larger than that of the upstream side in the check valve unit 43C, each opening-closing valve body 46 rotates downward to close, and air is prevented from flowing backward from the electric blower 5B and sucked into only the electric blower 5A from the main body suction port 11 side via the dust collecting chamber 4. Additionally, in the case where the operation mode, such as a strong mode, for applying relatively large suction power is selected with the setting button 14, the controlling means 6 drives both the electric blowers 5 A, 5B as shown in Fig. 13, and thus the pressure of the upstream side becomes larger than that of the downstream side in the check valve unit 43C, each opening-closing valve body 46 opens, and air is sucked into the electric blowers 5A, 5B from the main body suction port 11 side via the dust collecting chamber 4.

[0082] Moreover, even if the check valve unit 43C is provided on the suction side of the electric blower 5B in the electric blower chamber 7B in the fourth embodiment, an operation-effect similar to that of the fourth embodiment can be obtained.

[0083] Additionally, although only the two electric blowers 5 are used in the third and fourth embodiments, three or more electric blowers 5 can be similarly used. For example, control can be performed that one of the electric blowers 5 is constantly driven and the other plurality of electric blowers 5 are stopped, or that the plurality of electric blowers 5 are constantly driven and the other electric blowers 5 are stopped. In this case, backflow preventing means can be provided in accordance with the other plurality of electric blowers 5 respectively. Additionally, in the case where the some of the plurality of other electric blowers 5 are simultaneously driven, one backflow preventing means can be provided for a group of the electric blowers 5.

[0084] Further, in each of the above embodiments, if anything is capable of preventing air from flowing backward to the dust collecting chamber 4 side of the non-driving electric blower 5, it is applicable to the backflow preventing means in addition to the check valve unit 43.

[0085] Next, a fifth embodiment will be described with reference to Figs. 14 to 16.

[0086] In the fifth embodiment, in place of the check valve unit 43 of the first embodiment, the controlling means 6 drives, in driving any of the electric blowers 5, the other electric blower 5 so that air is prevented from flowing backward.

[0087] That is, in the case where the operation mode, such as a weak mode, for applying relatively small suction power is selected with the setting button 14, the controlling means 6, as shown in Figs. 14 or 15, drives the electric blower 5B (electric blower 5A) at a low speed so that air is prevented from flowing backward to the dust collecting chamber 4 side via the electric blower 5B (electric blower 5A).

[0088] Specifically, the controlling means 6 detects the pressure in the electric blower chamber 7 by a blower chamber inner pressure detecting means (not shown) provided in the electric blower chamber 7, detects the pressure in the dust collecting chamber 4 by a dust collecting chamber inner pressure detecting means (not shown) provided in the dust collecting chamber 4, and drives, in driving either of the electric blowers 5 (electric blower 5A or 5B), the other electric blower 5 (electric blower 5B or 5A) so that a difference between the detected pressures in the dust collecting chamber 4 and electric blower chamber 7 is controlled. Thus, air is sucked into the electric blower 5 A or 5B from the main body suction port 11.

[0089] Additionally, in the case where the operation mode, such as a strong mode, for applying relatively large suction power is selected with the setting button 14, the controlling means 6, as shown in Fig. 16, drives both the electric blowers 5 A, 5B so that air is sucked into the electric blowers 5 A, 5B from the main body suction port 11.

[0090] Consequently, even in the case where one of the plurality of electric blowers 5 is driven, the controlling means 6 drives the other electric blower 5 so that air is prevented from flowing backward, and thus the air is prevented from being sucked into the dust collecting chamber 4 side and the negative pressure of the electric blower 5 is completely applied to the floor brush 17 side from the main body suction port 11. Therefore, an operation-effect, such as securing of the suction power, similar to that of each of the above embodiments can be obtained.

[0091] Additionally, since air is prevented from flowing backward from the non-driving electric blower 5 as long as the driving of the electric blower 5 is controlled by the controlling means 6, no check valve is required to be provided and the electric vacuum cleaner can be simplified.

[0092] Moreover, in the fifth embodiment, even if the controlling means 6 is adapted to be capable of driving any of the electric blower 5 constantly and stopping the other electric blower 5 in cleaning in the fifth embodiment similar to the third embodiment or fourth embodiment, not only can the same operation-effect be obtained but also a controlling method of the controlling means 6 can be simplified in constitution.

[0093] Additionally, although two electric blowers 5 are used in the fifth embodiment, three or more electric blowers 5 can be similarly provided.

[0094] Further, even if the electric blower chamber 7 is partitioned into the electric blower chambers 7A, 7B similar to the second embodiment or fourth embodiment, control similar to that of the second or fourth embodiment can be performed, and the same operation-effect can be obtained.

[0095] In each of the above embodiments, a sealing member which, when the opening- closing valve bodies 46 are closed, comes into airtight contact with the upstream sides of the closed opening-closing valve bodies 46 may be provided in the angular tube- shaped frame 49.

[0096] Additionally, details of the electric blower are not limited to those disclosed above. Industrial Applicability

[0097] The present invention is used for, for example, household electric vacuum cleaners.

Claims

[1] An electric vacuum cleaner comprising: a vacuum cleaner main body with a plurality of electric blowers housed therein; a common dust collecting chamber which is provided in the vacuum cleaner main body and communicates with a suction side of each of the electric blowers; a controlling means capable of making the electric blowers independently drive; and backflow preventing means which are provided in accordance with the electric blowers and prevent air from flowing backward to the dust collecting chamber side. [2] An electric vacuum cleaner comprising: a vacuum cleaner main body with a plurality of electric blowers housed therein; a common dust collecting chamber which is provided in the vacuum cleaner main body and communicates with a suction side of each of the electric blowers; a controlling means capable of performing control for driving only any one of the plurality of electric blowers and stopping the other electric blowers, and control for driving all of the plurality of the electric blowers; and backflow preventing means which are provided in accordance with the other electric blowers and prevent air from flowing backward to the dust collecting chamber side. [3] The electric vacuum cleaner according to claim 1 or 2, wherein the backflow preventing means is an opening-closing means for opening and closing at least either the upstream side or downstream side of the corresponding electric blower. [4] The electric vacuum cleaner according to claim 3, wherein the opening-closing means is opened and closed by a pressure difference between the upstream side and downstream side. [5] The electric vacuum cleaner according to claim 4, wherein the opening-closing means includes opening-closing valve bodies each of which has an upper end rotatably supported and rotates downward by its own weight by stopping of the electric blower and closes. [6] An electric vacuum cleaner comprising: a vacuum cleaner main body with a plurality of electric blowers housed therein; a common dust collecting chamber which is provided in the vacuum cleaner main body and communicates with a suction side of each of the electric blowers; and a controlling means capable of, when driving one of the plurality of electric blowers, driving the other electric blowers so that no air flows backward to the dust collecting chamber side.