VACUUM CLEANER

Abstract

A vacuum cleaner includes an electric blower that sucks dust through a suction connecting port, a first dust separating unit for separating the dust and air sucked into the suction connecting port from each other, and a pleat filter for separating the dust and air passing through a first dust separating unit. The vacuum cleaner further includes an external-air introducing air passage for introducing external air toward an upstream side of the pleat filter, a rotational fan for dropping off dust adhering to the pleat filter by the introduced external air, and a return air passage for returning the dust dropped off from the rotating fan toward the upstream side of the first dust separating unit by the introduced external air.

Description

TECHNICAL FIELD

The present invention relates to a vacuum cleaner, and more particularly, to a vacuum cleaner that prevents dust dropped off from a collecting unit, such as a filter, for collecting dust, from re-adhering to this collecting unit.

BACKGROUND OF THE INVENTION

There has hitherto been known a vacuum cleaner including a cleaner body provided with a dust collecting container chamber formed therein, a dust collection container detachably mounted to the dust collecting container chamber, an electric blower provided on the downstream side of the dust collecting container chamber, a secondary filter, such as a pleat filter, detachably mounted to a rear port of the dust collecting container, for collecting dust, and a dust removal unit for dropping off dust adhering to the pleat filter (refer to Japanese Unexamined Patent Application Publication No. 2004-358135).

This dust removal unit includes a ring rotatably provided at a position opposite to the pleat filter, and a projection provided to a ring so as to abut against the pleat filter.

In this conventional vacuum cleaner, when a cord reel is rewinding a power cord, the ring is rotated, and under the rotation of the ring, the protrusion moves getting over mountain portions of pleats of the pleat filter, to thereby give vibration to the pleat filter so as to drop dust adhering to the pleat filter.

However, in such a vacuum cleaner, a problem was posed such that dust dropped off from the pleat filter adheres again to the pleat filter when the electric blower is driven.

DISCLOSURE OF THE INVENTION

Accordingly, it is an object of the present invention to provide a vacuum cleaner that prevents dust dropped off from a collecting unit, such as a secondary filter, for collecting dust, from re-adhering to the secondary filter.

To achieve the above described object, a vacuum cleaner according to one embodiment of the present invention includes: an electric blower that sucks dust through a suction connecting port; a dust separating. unit for separating the dust and air sucked into the suction connecting port from each other to thereby collect the dust; a collecting unit for collecting the dust passing through the dust separating unit, the collecting unit being provided separately from the dust separating unit; a dust removal unit for dropping off the dust collected by the collecting unit; and a return mechanism for returning the dust dropped off from the collecting unit by the dust removal unit toward an upstream side of the dust separating unit, the dust returned by the return mechanism being collected by the dust separating unit.

According to the present invention, since the dust dropped off from the collecting unit such as a secondary filter is returned to and collected by the dust separating unit, it is possible to prevent the dropped-off dust from re-adhering to the collecting unit.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] a perspective view showing an appearance of a vacuum cleaner according to a first embodiment of the present invention.

[FIG. 2] a longitudinal sectional view showing a structure of a cleaner body shown in FIG. 1.

[FIG. 3] a perspective view showing a dust collecting unit of the vacuum cleaner.

[FIG. 4] a perspective view showing a main part of the dust collecting unit.

[FIG. 5] a cross-sectional view showing a structure of the dust collecting unit shown in FIG. 4.

[FIG. 6] a perspective view of the dust collecting unit (in FIG. 3), as viewed from a different direction.

[FIG. 7] a diagram showing an orientation of blades of a rotating fan of a dust removal unit in the vacuum cleaner.

[FIG. 8] a conceptual diagram showing air passages in the cleaner body shown in FIG. 1.

[FIG. 9] a longitudinal sectional view showing a structure of the cleaner body according to a second embodiment of the present invention.

[FIG. 10] a conceptual diagram showing air passages in the cleaner body according to the second embodiment of the present invention.

REFERENCE NUMERAL

• 24 - - - electric blower
• 27a - - - suction connecting port
• 52 - - - dust separation portion
• 55 - - - first dust separation unit
• 104 - - - pleat filter
• 640 - - - return air passage
• 650 - - - outside air introduction passage
• 800 - - - rotating fan

BEST MODE FOR EMBODYING THE INVENTION

Hereunder, embodiments of a vacuum cleaner according to the present invention will be specifically described with reference to the accompanying drawings.

FIRST EMBODIMENT

FIG. 1 shows a vacuum cleaner according to a first embodiment of the present invention. A vacuum cleaner 10 in the first embodiment includes: a cleaner body 11; a dust collecting hose 12 having one end detachably connected to a connection port 11a of the cleaner body 11 and the other end provided with a hand operating tube 13; an extension tube 14 detachably connected to the hand operating tube 13; and a suction port body 15 detachably connected to the front end of the extension tube 14. The hand operation tube 13 has an operating portion 13A, which includes a drive/stop changeover switch 13a for switching between the drive and the stop of the electric blower 24, and a strong/weak changeover switch 13b for controlling the power of the electric blower 24, described below. The cleaner body 1 has a body case 20, which incorporates a dust collecting unit 50 and the electric blower 24 (refer to FIG. 2). These dust collecting unit 50 and electric blower 24 will be described hereinlater.

The suction port body 15 includes a dust suction port, not shown, opened in the bottom surface of the suction port body 15 so as to suck dust lying on a floor or the like, and a suction chamber (not shown) communicating with the dust suction port. The suction chamber communicates with a suction connecting port 57a of the dust collecting unit 50 (refer to FIG. 3) provided within the cleaner body 11, via the extension tube 14, the dust collecting hose 12, and the connection port 11a.

A shutter 600 is provided within the connection port 11a of the cleaner body 11, as shown in FIG. 2. The shutter 600 is configured to block or open the connection port 11a.

As shown in FIG. 2, a dust collecting unit chamber 22 is provided inside a front portion of the body case 20. The dust collecting unit 50 is located in the dust collecting unit chamber 22.

The electric blower 24 is located inside a rear portion of the body case 20 (i.e., on the left side in FIG. 2). In front of the electric blower 24, a large-diameter connection air passage portion 25 having a front opening 25B is provided. In a rear wall 25A of the connection air passage portion 25, there is formed a connection opening 25b, which is connected with an air passage tube 500 having a small-diameter. The air passage tube 500 communicates with a suction opening 24A of the electric blower 24. The air passage tube 500 incorporates a first blocking unit, which is constituted of, for example, a shutter 501. By the opening/closing of the shutter 501, the suction opening 24A of the electric blower 24 and the inside of the connection air passage portion 25 takes a communication state or a non-communication state.

Between the shutter 501 and the suction opening 24A, the air passage tube 500 connects with one end of the detour air passage tube 502, to thereby communicate with the detour air passage tube 502.

As shown in FIGS. 3 to 6, the dust collecting unit 50 includes a dust separation unit 400 and a dust collecting container 410.

The dust separation unit 400 includes a dust separation portion 52 capable of separating the dust and air and collecting the dust, and a collecting unit for collecting dust that has passed through the dust separation portion 52. The collecting unit is composed of, for example, a filter unit 80 and a lid case 21A provided on the filter unit 80. The dust separation portion 52 is configured to swirl air containing dust and separates the dust and the air by virtue of inertia force. Details of these dust separation portion 52 and filter unit 80 will be described later.

The dust collecting container 410 is composed of a transparent dust collecting portion 70 made of a resin and a lid case 21B provided on the dust collecting portion 70.

As shown in FIG. 4, the dust separation portion 52 includes a separating chamber 54 cylindrically formed by an outer peripheral wall 53, a substantially conical first dust separating unit 55 provided in the separating chamber 54 along the axis line thereof, a suction air passage portion 56 provided outside a right side wall 54A of the separating chamber 54, and a guide air passage tube 57 for guiding air to the separating chamber 54 from the suction connecting port 57a through which the dust is sucked.

As shown in FIG. 2, the suction connecting port 57a communicates with the connection port 11a of the cleaner body 11 via the shutter 600.

As shown in FIG. 5, in an upper portion of the outer peripheral wall 53 of the separating chamber 54, there is provided an introducing opening 53A for introducing the dust separated from the air to the dust collecting portion 70.

Further, in the right side wall 54A of the separating chamber 54, as shown in FIG. 4, a circular opening 154A and a fan-shaped opening 154B are provided. To the opening 154A, the first dust separating unit 55 is mounted, and to the opening 154B, a net filter NF2 (not shown) is mounted. In the right side wall 54A, there is provided a connection opening 54Aa, to which a guide air passage tube 57 is connected. Thus, the separating chamber 54 and the guide air passage tube 57 are communicated with each other.

The first dust separating unit 55 is composed of a plurality of frames 55a and a net filter NF1 bonded to the periphery of the frames 55a. The suction air passage portion 56 communicates with the separating chamber 54 via the opening 154A in the right side wall 54A and the net filter NF1 (refer to FIG. 5), and also communicates with the separating chamber 54 via the net filter NF2 (not shown) of the opening 154B in the right side wall 54A.

The suction air passage portion 56 communicates with the inside of an accommodating case 81 of the filter unit 80 and also communicates with a dust collecting chamber 73 (described later) of a dust collecting case portion 74 via a connection opening 56A formed in a right side wall portion 156 (refer to FIG. 5) of the suction air passage portion 56.

The bottom of the suction air passage portion 56 is connected with the other end of the detour air passage tube 502, and the suction air passage portion 56 and the air passage tube 500 of the cleaner body 11 communicate with each other via the detour air passage tube 502. On the other end side of the detour air passage tube 502, there is provided a third blocking unit, which is constituted of, for example, a solenoid valve 503. This solenoid valve 503 serves to block or open the detour air passage tube 502.

As shown in FIG. 5, the dust collecting portion 70 includes a communication case portion 72 having a communicating passage 71 which laterally extends in an upper portion thereof and a dust collecting case portion 74 having the dust collecting chamber portion 73 which extends downward from the right end of the communication case portion 72 so as to collect the dust.

In the left bottom surface of the communication case portion 72, there is provided an opening 72A, which is communicated with the introducing opening 53A of the dust separation portion 52 as shown in FIG. 5. A connection opening 75 is provided in a left side wall portion 74A of the dust collecting case portion 74, and a net filter NF3 is mounted to the connection opening 75.

A cover plate 170 is mounted on the outer wall portion of the dust collecting case portion 74 to a position located outside the net filter NF3 and apart from the net filter NF3 by a predetermined distance, a. An opening 170A is provided in a lower portion of the cover plate 170.

The opening 170A of the cover plate 170 is connected to the connection opening 56A of the suction air passage portion 56.

Upon mounting the dust collecting container 410 to the dust collecting unit chamber 22 of the cleaner body 11, as shown in FIG. 5, the introduction opening 53A of the dust separation portion 52 is connected to the opening 72A of the dust collecting container 410, and the opening 170A in the cover plate 170 of the dust collecting container 410 is connected to the connection opening 56A of the suction air passage portion 56 in the dust separation unit 400.

As shown in FIGS. 3 to 6, the filter unit 80 is opened in the rear surface, and includes a cylindrical accommodating case 81 and a pleat filter portion 100 mounted therein. On the front surface of a front wall portion 84 of the accommodating case 81, the dust separation portion 52 is integrally mounted. The pleat filter portion 100 has a pleat filter 104 having a plurality of mountain portions extending radially.

The front wall portion 84 (refer to FIG. 2) of the accommodating case 81 has a connection opening 84A (shown in FIG. 6), which is connected to the suction air passage portion 56 (refer to FIG. 5). The inside of the accommodating case 81 and the suction air passage portion 56 are communicated with each other via the connection opening 84A. The connection opening 84A has a second blocking unit, which is constituted of, for example, a shutter 700. The shutter 700 is operative to block or open the connection opening 84A.

Further, the accommodating case 81 has therein side a return mechanism for returning air in the accommodating case 81 to the dust separation portion 52. This return mechanism is constituted of, for example, a return air passage 640 constituting an air passage. One end of the return mechanism is connected to a lower portion of the front wall portion 84 of the accommodating case 81, while the other end thereof is connected to the guide air passage tube 57 of the dust separation portion 52. To the other end of the returning air passage 640, there is provided, for example, a solenoid valve 641, which is operative to block or open the return air passage 640.

An external-air introducing air passage 650 (refer to FIG. 2) for introducing external air into the accommodating case 81 is formed at an upper portion of the accommodating case 81. The external-air introducing air passage 650 includes, for example, a solenoid valve 651, which serves to to block or open the external-air introducing air passage 650.

A dust removal unit for removing dust from the pleat filter portion 100 is disposed inside the accommodating case 81. As shown in the illustration of the embodiment, the dust removal unit is located between the pleat filter portion 100 and the front wall portion 84 of the accommodating case 81 and constitutes a rotating fan 800 that pivots on a central axis 101A of the pleat filter portion 100. The rotating fan 800 is configured to be rotated, for example, by external air introduced from the external-air introducing air passage 650. A frame 801 of the rotating fan 800 has at least one protrusion 802 in contact with one of the mountain portions of the pleat filter 104.

Upon rotating the rotating fan 800, the protrusion 802 gets over the mountain portions of the pleat filter 104, and accordingly, it is possible to provide vibrations to the pleat filter 104 to thereby shake off dust adhering to the pleat filter 104. As shown in FIG. 7, the orientation of the blades 803 of the rotating fan 800 is set so as to receive the external air introduced from the external-air introducing air passage 650 to thereby flow the external air toward the pleat filter portion 100. As described above, the dust removal unit is configured to remove the dust from the pleat filter by means of the rotating fan 800 that is rotated by the external air introduced from the external-air introducing air passage 650. The present invention is, however, not limited to this way of removing the dust. For example, the dust may be removed by rotating the pleat filter portion 100 by a motor (not shown) or the like, and the dust is dropped off from the pleat filter portion 100, for example, by bringing a fixed leaf spring (not shown) into contact with the mountain portions and causing the leaf spring to pick these mountain portions. In this case, since it is not necessary to rotate the fan 800, the more smooth air flow from the external-air introducing air passage into the filter unit may be achieved.

The control of the closing/opening operations of the shutters 501, 600, and 700, or the solenoid valves 503, 641, and 651 is performed by a control unit, which is not shown in the figure.

[Operation]

Hereunder, the operations of the vacuum cleaner of the structure mentioned above will be described with respect to FIG. 8 as a conceptual diagram.

First, as shown in FIG. 2, the dust collecting unit 50 is mounted to the dust collecting unit chamber 22 of the cleaner body 11, and the dust collecting hose 12 is connected to the connection port 11a of the cleaner body 11, and the suction port body 15 is also connected to the hand operation tube 13 via the extension tube 14 as sown in FIG. 1. At this time, the shutters 501, 600 and 700 are each in an opened state, and the solenoid valves 503, 641 and 651 are each in a closed state.

Upon operating the switch 13b of the operation portion 13A, the electric blower 24 is driven. When this electric blower 24 is driven, air is sucked from the suction opening 24A of the electric blower 24. As a result, a negative pressure operates on the inside of the accommodating case 81 of the dust collecting unit 50 via the air passage tube 500 and the connection air passage portion 25, and further operates on the inside of the dust collecting case portion 74 or the separating chamber portion 54 of the dust separation portion 52 via the suction air passage portion 56. This negative pressure acts to the dust collecting hose 12, the extension tube 14 and the suction port body 15 via the guide air passage tube 57 to thereby suck the dust through the suction port body 15 together with air.

The thus sucked dust and air are guided into the suction connecting port 57a of the dust collecting unit 50 via the extension tube 14 and the dust collecting hose 12. The dust and the air that have been sucked into the suction connecting port 57a are introduced into the separating chamber 54 of the dust separation portion 52 through the guide air passage tube 57, and the dust and air are then counterclockwisely rotated in the separating chamber 54 as shown in FIG. 4.

Under the rotation of the air, the dust and the air are separated from each other by inertias, and the air is sucked into the accommodating case 81 of the filter unit 80, through the net filter NF1 (refer to FIG. 5) of the first dust separating unit 55 or the net filter NF2 (not shown) of the opening 154B and further through the suction air passage portion 56.

On the other hand, the separated dust is introduced into the communication case portion 72 in the dust collecting portion 70 of the introducing opening 53A in the separating chamber 54 by an inertia force, together with a part of air. These introduced dust and air are sucked into the dust collecting chamber 73 through the communicating passage 71 in the communication case portion 72, and the dust is collected into the dust collecting chamber 73.

The air that sucked into the dust collecting chamber 73 is then sucked into the suction air passage portion 56 through the net filter NF3 and the opening 170A located below the cover plate 170, and further sucked into the accommodating case 81 of the filter unit 80.

The air sucked into the accommodating case 81 is then sucked into the connection air passage portion 25 of the cleaner body 11 through the pleat filter 104 of the pleat filter portion 100, and further sucked into the suction opening 24A of the electric blower 24.

The air sucked into the suction opening 24A of the electric blower 24 is then exhausted from an exhaust port 20H of the cleaner body 11 shown in FIG. 2, through the inside of the electric blower 24. That is, the air flows as indicated by a chain line with arrows in FIG. 8.

Upon completing the cleaning and operating of the switch 13a of the hand operation tube 13, the shutters 501, 600 and 700 are closed and the solenoid valves 503, 641 and 651 are opened. The electric blower 24 is driven at a predetermined power for a predetermined time period.

By closing the shutters 501, 600 and 700 and opening the solenoid valves 503, 641 and 651, the external air is introduced from the external-air introducing air passage 650 into the accommodating case 81 (refer to FIG. 2) of the dust collecting unit 50 as shown in FIG. 8. Under such introduction of the air, the rotating fan 800 is rotated, and the vibration is caused to the pleat filter 104 by the location of the protrusion, thereby dropping off dust adhering to the pleat filter 104.

Further, since the external air abutting against the blades 803 of the rotating fan 800 flows toward the pleat filter 104, the dust adhering to the pleat filter 104 can be effectively dropped off.

As indicated by broken lines with an arrow in FIG. 8, the external air introduced into the accommodating case 81 is sucked into the upstream side of the dust separating portion 55, that is, into the guide air passage tube 57 (refer to FIG. 2) of the dust collecting unit 50 through the return air passage 640, and further sucked into the separating chamber 54 of the dust collecting unit 50 shown in FIG. 5.

The dust dropped off from the pleat filter 104 passes through the return air passage 640, moves with the flow of the external air, and is carried into the separating chamber 54 of the dust collecting unit 50.

The dust is separated from the external air in the separating chamber 54 and carried into the dust collecting chamber 73, while the external air is sucked into the suction air passage portion 56 through the net filter NF1 (refer to FIG. 5) of the first dust separating unit 55, or the net filter NF2 (not shown) of the opening 154B.

As indicated by the broken lines each with arrow in FIG. 8, the external air introduced into the suction air passage portion 56 is sucked into the downstream side portion of the shutter 501, i.e., the air passage tube 500 shown in FIG. 2 through the detour air passage tube 502 and further sucked into the suction opening 24A of the electric blower 24. Then, the drive of the electric blower 24 is stopped after a predetermined time period.

In this manner, the dust dropped off from the pleat filter 104 is carried into the separating chamber 54 of the dust collecting unit 50. Therefore, when the electric blower 24 is driven for performing cleaning, the dust that has been dropped off from the pleat filter 104 is prevented from being sucked up and re-adhering to the pleat filter 104.

SECOND EMBODIMENT

FIGS. 9 and 10 show a vacuum cleaner according to a second embodiment of the present invention. In the vacuum cleaner of the second embodiment, the air passage tube 500 and the inside of the accommodating case 81 are communicated through the detour air passage 900 constituting a detour passage, and the detour air passage tube 900 has a third dust separating unit. The third dust separating unit includes, for example, a filter 901 and a solenoid valve 902.

In the vacuum cleaner of the second embodiment, when the cleaning is performed; the shutters 501 and 700 are opened and the solenoid valve 902 is closed, air flows as indicated by a chain line with arrows in FIG. 10, and dust is collected into the dust collecting chamber portion 73 as in the case of the first embodiment.

When the switch 13a (refer to FIG. 1) of the operation portion 13A is operated by using the hand operation tube 13, the shutters 501 and 700 are closed, and the solenoid valves 902 is opened. The electric blower 24 is driven at a predetermined power for a predetermined time period.

When the shutters 501 and 700 are closed, external air is introduced from the external-air introducing air passage 650 into the accommodating case 81 of the dust collecting unit 50. This introduction of the air causes dust adhering to the pleat filter 104 to drop off therefrom as in the case of the first embodiment. The external air introduced into the accommodating case 81 is sucked into the air passage tube 500 through the detour air passage 900, and further sucked into the suction opening 24A of the electric blower 24, as indicated by the broken lines each with arrow in FIG. 10.

The dust dropped off from the pleat filter 104 passes through the detour air passage 900 and moves with the flow of the external air, as in the case of the first embodiment. Because the detour air passage tube 900 has a filter 901, the dust is caught by the filter 901, and only the air is sucked into the air passage tube 500.

In this way, the dust dropped off from the pleat filter 104 is carried into the detour air passage tube 900 and caught by the filter 901. Therefore, when the electric blower 24 is driven for performing cleaning, the dust that has been dropped off the pleat filter 104 is prevented from being sucked up and re-adhering to the pleat filter 104.

According to the second embodiment, the shutter 600, it is not necessary to locate the return air passage 640 or the solenoid valve 641.

The present invention is not limited to the above-described first and second embodiments, and a vacuum cleaner of a type using a paper pack filter may be utilized instead of the dust separation portion 52 and the dust collecting portion 70.

It is to be noted that the present invention is not limited to the described embodiment and many other changes and modifications may be made without departing from the scopes of the appended claims.

In the above-described embodiments, although the present invention has been applied to a vacuum cleaner, the present invention is not restricted thereto. For example, the present invention is also applicable to an air-conditioning system and the like in such a way as to drop off dust from a filter in the air-conditioning system and the like.

Claims

1. A vacuum cleaner comprising:

an electric blower for sucking dust through a suction connecting port;

a dust separating unit for separating the dust and air sucked into the suction connecting port from each other to thereby collect the dust;

a collecting unit for collecting the dust passing through the dust separating unit, the collecting unit being provided separately from the dust separating unit;

a dust removal unit for dropping off the dust collected by the collecting unit; and

a return mechanism for returning the dust dropped off from the collecting unit by the dust removal unit toward an upstream side of the dust separating unit,

the dust returned by the return mechanism being collected by the dust separating unit.

2. The vacuum cleaner according to claim 1, further comprising an external-air introducing air passage provided for introducing external air toward the upstream side of the dust separating unit, wherein the return mechanism has a return air passage configured to return the dust dropped off from the collecting unit by the dust removal unit toward the upstream side of the dust separating unit by the external air introduced through the external-air introducing air passage.

3. The vacuum cleaner according to claim 2, wherein the collecting unit has a pleat filter, and the dust removal unit is provided with a rotating fan contacting the pleat filter and driven by the external air introduced from the external-air introducing air passage to thereby drop off dust collected by the pleat filter.

4. A vacuum cleaner comprising:

an electric blower for sucking dust through a dust suction port;

a first dust separating unit for separating the dust and air sucked into the dust suction port from each other;

a second dust separating unit for separating the dust and air passing through the first separating unit;

a first blocking unit for blocking an air passage located on a downstream side of the second dust separating unit and on an upstream side of the electric blower;

a second blocking unit for blocking an air passage between the first dust separating unit and the second dust separating unit;

a detour air passage communicating an upstream portion of the electric blower with a downstream portion of the first dust separating unit;

a third blocking unit for blocking the detour air passage;

a dust removal unit for dropping off the dust adhering to the second dust separating unit;

an external-air introducing air passage for introducing external air toward the upstream side of the second dust separating unit;

a control unit for controlling the first, second and third blocking units; and

a return air passage for returning the dust dropped off by the dust removal unit toward the upstream side of the first dust separating unit by the external air introduced from the external-air introducing air passage so that the returned dust is collected by the first dust separating unit.

5. The vacuum cleaner according to claim 4, wherein the second dust separating unit is provided with a pleat filter, and the dust removal unit is provided with a rotating fan contacting to the pleat filter and driven by the external air introduced from the external-air introducing air passage to thereby drop off dust collected by the pleat filter.

6. A vacuum cleaner comprising:

an electric blower for sucking dust through a dust suction port;

a first dust separating unit for separating the dust and air sucked into the dust suction port from each other;

a second dust separating unit for separating the dust and air passing through the first separating unit;

a first blocking unit for blocking an air passage located on a downstream side of the second dust separating unit and on an upstream side of the electric blower;

a second blocking unit for blocking an air passage between the first dust separating unit and the second dust separating unit;

a dust removal unit for introducing external air toward an upstream side of the second dust separating unit and dropping off dust adhering to the second dust separating unit by the external air;

a detour air passage flowing the introduced external air to a downstream side of the second dust separating unit; and

a third blocking unit for catching the dust passing through the detour air passage together with the external air.

7. The vacuum cleaner according to claim 6, wherein the second dust separating unit is provided with a pleat filter, and the dust removal unit is provided with a rotating fan contacting to the pleat filter and driven by the external air introduced by an external-air introducing air passage to thereby drop off dust collected by the pleat filter.