VACUUM CLEANER

Abstract: A vacuum cleaner comprising: a fan motor (6) disposed in a main body case (1) thereof and having a motor (10) arranged in such a manner that its rotor (13) or its stator (14) uses a permanent magnet (12) and a fan arranged to be rotated by the motor; a dust-­ collecting chamber (1a) for collecting dust sucked into the main body case due to the rotation of the fan motor; and a dust-collecting filter (5) for causing the dust sucked into the main body case to be caught in the dust-­ collecting chamber, wherein magnetic material adhesion preventing device (20) (21) (22) (25) (26) (27) (29) (30) is provided in a passage through which air flows due to rotation of the fan motor, the magnetic material adhesion preventing device acting to prevent adhesion of fine dust composed of magnetic materials included in the air flow to a portion in the vicinity of the permanent magnet. As a result, the sticking taken place between the rotor and the stator due to adhesion of fine dust between them can be prevented, causing the life to be elongated and the reliability to be improved.

Description: The present invention relates to a vacuum cleaner having a motor fan whose rotor or stator uses a permanent magnet. Prior Art A known vacuum cleaner of the type described above and as disclosed, for example, in JP-A-60-242827, has been structured in such a manner that a brushless motor formed by securing a magnet to its rotational shaft via a yoke is positioned in a case for the main body of the vacuum cleaner. In the above-described structure, dust absorbed from the surface to be cleaned such as the surface of a floor is accumulated in a dust case by means of a dust collecting filter. Furthermore, an exhaust air flow from the fan is caused to pass through the brushless motor so that the rotor and the stator of the brushless motor are cooled. According to the above-described conventional technology, fine dust which has passed through the dust collecting filter is introduced into the brushless motor. Therefore, the thus introduced fine dust adheres to the magnet of the brushless motor if the fine dust is composed of magnetic materials such as iron dust. It leads to a problem in that the magnet and the stator inevitably become stuck if the space disposed between the magnet serving as the rotor and the stator is filled with the fine dust. US-A-4 476 607 discloses a vacuum cleaner comprising all features of the precharacterizing part of claim 1. The magnetic material adhesion preventing means of said known vacuum cleaner is mounted on a covering plate closing the end of a tube means contacting a surface to be cleaned, and said adhesion preventing means serves to pick up metal articles located on said surface, but does not prevent fine magnetic material dust from entering said tube means. SUMMARY OF THE INVENTION Accordingly, an object of the invention is to provide a vacuum cleaner in which fine dust composed of magnetic materials such as iron dust cannot be stuck to a permanent magnet even if the permanent magnet is used in the rotor or the stator of a fan motor. Said object is achieved, according to the present invention, by a vacuum cleaner as claimed in claim 1. Advantageous further features are claimed in the sub-claims. The magnetic material adhesion preventing means comprises a fine-dust catching filter capable of catching the fine dust composed of magnetic materials which has passed through the dust-collecting filter and/or an insulating wall for hermetically insulating the rotor from an air flow generated due to rotation of the fan motor. When the fan motor is rotated at the time of the cleaning work, dust is sucked from the surface to be cleaned such as the surface of a floor into the dust-collecting chamber in the main body case. The dust sucked into the dust-collecting chamber is caught by the dust-collecting filter in the dust-collecting chamber. If fine dust composed of magnetic materials is included in the dust sucked into the main body case, it can pass through the dust-collecting filter. The fine dust which has passed through the dust-collecting filter is caught by the dust filter in a structure according to the present invention in which the fine dust filter is provided. As a result, the fine dust cannot reach the fan motor. On the other hand, in the case according to the present invention in which the insulating wall capable of hermetically insulating the rotor comprising the permanent magnet, the fine dust does not reach the outer surface of the rotor of the fan motor by the action of the insulating wall. Therefore, adhesion of the fine dust to the magnet portion of the fan motor can be prevented. Other and further objects, features and advantages of the invention will be appear more fully from the following description. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a vertical cross sectional view which illustrates a first embodiment of the present invention; Fig. 2 is a vertical cross sectional view which illustrates a second embodiment of the present invention; Fig. 3 is a vertical cross sectional view which illustrates an essential portion of a third embodiment of the present invention; Fig. 4 is a vertical cross sectional view which illustrates an essential portion of a fourth embodiment of the present invention; Fig. 5 is a vertical cross sectional view which illustrates an essential portion of a fifth embodiment of the present invention; and Fig. 6 is a vertical cross sectional view which illustrates an essential portion of a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described with reference to the drawings. Referring to Fig. 1 which illustrates a first embodiment of the present invention, a main body case 1 of a vacuum cleaner is sectioned into a dust-collecting chamber 1a and a fan-motor accommodating chamber 1b by means of a partition body 1c. A grid-shape communicating port 1d is formed in the partition body 1c. A hose 2 connected to the dust-collecting chamber 1a is detachably fastened to the front surface of the main body case 1. An extension pipe 3 is detachably connected to the hose 2. A nozzle 4 is detachably fastened to the extension pipe 3. A dust-collecting filter 5 in the form of paper back or a cloth back container and having a shape maintaining characteristic is placed in the dust-collecting chamber 1a. Thus, dust sucked into the dust-collecting chamber 1a is introduced into the dust-collecting filter 5 after the dust has passed through the nozzle 4, the extension pipe 3 and the hose 2. The dust-collecting filter 5 can be withdrawn from the dust-collecting chamber 1a after the cleaning work with the vacuum cleaner has been ended. A fan motor 6 is placed in the fan-motor accommodating chamber 1b by using rubber cushions 7 and 8. The fan motor comprises a fan 9 and a motor 10. The motor 10 comprises: a rotor 13 formed by securing a permanent magnet 12 to the rotational shaft 11; a stator 14 disposed around the rotor 13; a housing 15 covering the stator 14 and the rotor 13; and an end bracket 16. The stator 14 comprises a stator core 14a and a wire 14b to be wound. The fan 9 comprises: a centrifugal blade 17 secured to the rotational shaft 11; a fixed guide blade 18 positioned between the centrifugal blade 17 and the motor 10; and a fan casing 19 for covering the fixed guide blade 18 and the centrifugal blade 17. The fan casing 19 is secured around the end bracket 16 by press-fitting. A fine-dust catching filter 20, which serves as means for preventing sticking of magnetic material, is fastened to the communicating port 1d in the partition body 1c. The fine-dust catching filter 20 is made of a filter material or a filter material which has been processed, the filter material being capable of absorbing and catching fine dust composed of magnetic materials such as iron dust. Furthermore, the fine-dust catching filter 20 is arranged in structure so that a proper ventilation resistance level is obtained. Fig. 2 illustrates a second embodiment of the present invention, where the same reference numerals as those shown in Fig. 1 represent the same elements as those of Fig. 1. According to the second embodiment shown in Fig. 2, an absorbing body 21 is placed in a nozzle 4 for the purpose of preventing the sticking of the magnetic material to the rotor 13 of the motor 10. The absorbing body 21 is structured in such a manner that the magnetic material such as iron dust which is being sucked by the nozzle 14 can be absorbed and caught. The absorbing body 21 may be formed by a strong permanent magnet so as to catch thumb tacks or needles. Fig. 3 illustrates a third embodiment of the present invention, where the same reference numerals as those shown in Fig. 1 represent the same elements as those of Fig. 1. According to the third embodiment shown in Fig. 2, a fine-dust catching filter 22, which serves as means for preventing sticking of magnetic material, is fastened to an air inlet port 16a formed in the end bracket 16 of the motor 10. The fine-dust catching filter 22 is formed by a mesh whose size is so arranged as to cause a proper ventilation resistance level to be generated. The rotational shaft 11 is borne by a bearing 23 provided for the housing 15 and a bearing 24 provided for the end bracket 16. The fine-dust catching filter 22 absorbs and catches fine dust composed of magnetic materials such as iron dust flowed from the fan 9 so that the rotor 13 is protected from sticking of the magnetic materials. Fig. 4 illustrates a fourth embodiment of the present invention, where the same reference numerals as those shown in Fig. 1 represent the same elements as those of Fig. 1. According to the fourth embodiment shown in Fig. 4, two insulating walls 25 and 26 surrounding the rotor 13 are provided. Each of the two insulating walls 25 and 26 is in the form of a cylinder. The first insulating wall 25 is positioned in contact with the end bracket 16 and the end surface of the fixed core 14a. Thus, the rotor 13 is hermetically closed by the two insulating walls 25 and 26 so that introduction of an air flow from the fan 9 into the portion around the rotor 13 is prevented. Therefore, even if fine dust composed of magnetic materials such as iron dust reaches from the fan 9, it cannot be stuck to the surface of the rotor 13. The fine dust is exhausted through an exhaust port formed in the housing to the outside of the fan motor 6. Therefore, according to the fourth embodiment, fine dust composed of magnetic materials such as iron dust which has passed through the dust-collecting filter 5 cannot stick to the outer surface of the rotor with eliminating a necessity of providing the fine dust filter 20 according to the first embodiment. Fig. 5 illustrates a fifth embodiment of the present invention, where the same reference numerals as those shown in Fig. 4 represent the same elements as those of Fig. 4. According to the fifth embodiment shown in Fig. 5, an insulating wall 27 for insulating the rotor 13 from an air flow from the fan 9 is provided in such a manner that it passes through a space 28 disposed between the stator 14 and the rotor 13. The insulating wall 27 is, as a cylindrical body, held between the housing 15 and the end bracket 16. According to the above-described structure, the number of components can be reduced in comparison to the fourth embodiment. Fig. 6 illustrates a sixth embodiment of the present invention, where the same reference numerals as those shown in Fig. 5 represent the same elements as those of Fig. 5. Insulating walls 29 and 30 for insulating the rotor 13 from an air flow from the fan 9 are formed integrally with the housing 15 or the end bracket 16. That is, an annular reduction portion 15a is formed in the housing 15 so that the insulating wall 29 is created. The front end portion of the insulating wall 29 is positioned in contact with the stator core 14a. An annular reduction portion 16b is formed in the end bracket 16 so that the insulating wall 30 is created. The front end portion of the insulating wall is positioned in contact with the stator core 14a. According to the above-described structure, the number of components can be reduced in comparison to the fourth and the fifth embodiments. Furthermore, according to the structure employed in the sixth embodiment, the rotor 13 can be reliably and hermetically closed by the housing 15 and the end bracket 16. The stator 14 can be supplied with cooling air by forming an opening, which is connected to only the stator 14, in the end bracket 16 and in the housing 15. According to each of the structures employed in the fifth and the sixth embodiments, the rotor 13 can be perfectly insulated from an air flow from the fan 9 by the insulating wall 27 or the insulating walls 29 and 30. Therefore, even if fine dust composed of magnetic materials such as iron dust is flowed from the fan 9, the fine dust cannot stick to the outer surface of the rotor 13. Each of the above-described embodiments is structured in such a manner that the fine-dust collecting filters 20 and 22, the absorbing body 21 and the insulating walls 25, 26, 27, 29 and 30 are independently provided. The present invention is not limited to the description above. A structure may be employed in which the above-described components are properly combined with one another. In this case, the fine dust composed of magnetic materials such as iron dust cannot stick to the space disposed between the rotor 13 and the stator 14. Furthermore, the ventilation resistance can be easily controlled to an extent with which the cleaning performance cannot be deteriorated. According to the present invention, fine dust composed of magnetic materials such as iron dust and included in an air flow generated by the rotation of the fan motor is caught by the fine dust catching filter. Alternatively, even if the fine dust is introduced into the fan motor, the magnet portion in the rotor or the like is insulated from the air flow by the insulating wall. As a result, the adhesion of the fine dust between the rotor and the stator causing the rotor and the stator to be stuck can be prevented. Consequently, a vacuum cleaner having a fan motor which exhibits a long life and a satisfactory reliability can be provided.

Claims: A vacuum cleaner comprising: a fan motor (6) disposed in a main body case (1) thereof and having a motor (10) arranged in such a manner that its rotor (13) or its stator (14) uses a permanent magnet (12) and a fan (9) arranged to be rotated by said motor; a dust-collecting chamber (1a) for collecting dust sucked into said main body case due to rotation of said fan motor; a dust-collecting filter (5) for causing said dust sucked into said main body case to be caught in said dust-collecting chamber; and magnetic material adhesion preventing means provided in a passage through which air flows due to rotation of said fan motor, characterized in that said magnetic material adhesion preventing means (20) (21) (22) (25) (26) (27) (29) (30) acts to prevent adhesion of fine dust composed of magnetic materials included in said air flow to a portion in the vicinity of said permanent magnet (12). A vacuum cleaner according to claim 1, wherein said magnetic material adhesion preventing means is a fine-dust catching filter (20 (22) capable of catching said fine dust made of said magnetic materials and which has passed through said dust-collecting filter (5). A vacuum cleaner according to claim 2, wherein said magnetic material adhesion preventing means is positioned between said dust-collecting filter (5) and said fan motor (6). A vacuum cleaner according to claim 2, wherein said magnetic material adhesion preventing means is positioned between said fan (9) and said motor (10). A vacuum cleaner according to claim 1, wherein said magnetic material adhesion preventing means is an absorbing body (21) disposed in a nozzle (4) communicated with said main body case (1) and capable of absorbing and catching said dust composed of said magnetic materials which is being sucked into said suction port. A vacuum cleaner according to claim 1 or 2, its rotor (13) using a permanent magnet (12), wherein the dust-collecting chamber (1a) is disposed in the suction side of said fan motor (6). A vacuum cleaner according to claim 6, wherein said magnetic material adhesion preventing means is an insulating wall (25) (26) (27) (29) (30) for hermetically insulating said rotor (13) from said air flow generated due to rotation of said fan motor (6). A vacuum cleaner according to claim 7, wherein said insulating wall is formed by two cylindrical bodies (25) (26) (29) (30), either of said two cylindrical bodies is disposed between a housing (15) of said motor (10) and the stator (14), and the other cylindrical body is disposed between an end bracket (16) of said motor (10) and said stator (14). A vacuum cleaner according to claim 8, wherein said cylindrical body disposed between said housing (15) of said motor (10) and said stator (14) is formed integrally with said housing and said cylindrical body disposed between said end bracket (16) of said motor (10) and said stator (14) is formed integrally with said end bracket (16). A vacuum cleaner according to claim 6, wherein said magnetic material adhesion preventing means is a fine-dust catching filter (27) in the form of a cylinder covering said rotor (13) of said motor (10) and capable of catching said fine dust composed of magnetic materials. A vacuum cleaner according to claim 1, wherein said dust-collecting filter (5) also serves as said magnetic material adhesion preventing means by arranging its structure to be capable of catching said fine dust composed of said magnetic materials.

Inventors: ARAI, JIRO, ISHII, YOSHITARO, JYORAKU, FUMIO, KAWAMATA, MITSUHISA, TOYOSHIMA, HISANORI
Applicants: HITACHI, LTD.
Application year: 1990
Main classification: A47L9
IPC codes: A47L9, A47L5