Vacuum cleaner having silencer mechanism

Abstract: A blower cover (43) is provided so as to surround an electric driven blower (7). The blower cover (43) comprises an upper blower cover (43a) and a lower blower cover (43b). An exhaust air duct (42) as a silencer mechanism is provided on the upper blower cover (43a) and is disposed between a blower receiving room (40) and a cord receiving room (41). The exhaust air duct (42) comprising an outer peripheral wall portion (42a) and a side wall portion (42b). The outer peripheral wall portion has a partitioning rib (42d) and a curved guiding rib (42c). The exhaust air duct (42) forms a U-shaped exhaust air flow passage. An expansion room (23) is disposed air flow passage. An expansion room (23) is disposed at a down stream of the exhaust air duct (42). The exhaust air from an inhale port (45) of the exhaust air duct (42) flows the U-shaped flow passage and is led to the expansion room (23). The sucked air is expanded in the blower receiving room (40). The exhaust air is compressed in the exhaust air duct (42) and is expanded again in the expansion room (23). By these expansion and compression effects, the reduction effect for the exhaust air noise can attained.

Description: The present invention relates to a vacuum cleaner according to the preamble of claim 1. Such a vacuum cleaner having a silencer mechanism is disclosed in, JP-U-62115853, wherein a vacuum cleaner main body of the vacuum cleaner provides a sound absorption box which is positioned between a blower receiving room and a cord winding apparatus receiving room. The sound absorption box has an intake port and a plurality of exhaust air ports. As a result, a resonance type silencer mechanism for the vacuum cleaner main body is constituted between an outer peripheral surface portion of the sound absorption box and an inner wall portion of the vacuum cleaner main body. In the above-mentioned publication another conventional vacuum cleaner is explained. This vacuum cleaner has a structure in which a partial flow of an exhaust air flow from a side of an electric driven blower receiving room is bypassed through a partial portion of the inner wall portion of the vacuum cleaner main body. Namely, this inner wall portion of the vacuum cleaner main body is positioned between the blower receiving room and an exhaust air flow passage being adjacent the blower receiving room. However, in the vacuum cleaner having the resonance type silencer mechanism comprising the sound absorption box, the exhaust air flow from the side of the blower receiving room is exhausted into a comparatively large space in the vacuum cleaner main body via a plurality of exhaust air ports provided on the sound absorption box. By this conventional vacuum cleaner structure, the exhaust air noise level can be reduced at a particular frequency band. However, according to the results of the frequency analysis by the inventors of the present invention, the peaks of of the exhaust air noise level occur at a plurality of frequencies. Therefore, the exhaust air noise reduction effect in the vacuum cleaner main body cannot be obtained sufficiently in the vacuum cleaner having the resonance type silencer mechanism. Further, the electric driven blower used in the vacuum cleaner adopts a commutator motor as a driving means for the blower and the rotation number of the commutator motor is varied in accordance with the variation of the load. To put it concretely, in the initial condition of the cleaning operation of the vacuum cleaner in which the dust is not sucked into the vacuum cleaner main body, the commutator motor adopts a low rotation number of generally 20,000 - 27,000 rpm. When the dust is sucked into the vacuum cleaner main body and as the ventilation resistance in the vacuum cleaner main body increases, the commutator motor adopts a high rotation number of generally 28,000 - 36,000 rpm. Accordingly, the frequency of the rotative vibrating exhaust air noise in accordance with the rotation number of the commutator motor is not a constant but varies. Since in the vacuum cleaner having the resonance type silencer mechanism only the exhaust air noise level at the particular frequency band can be reduced, the exhaust air noise reduction effect in the vacuum cleaner main body is lowered in practical use of the vacuum cleaner. Besides, in the conventional vacuum cleaner having the resonance type silencer mechanism structure the vacuum cleaner adopts a structure in which a partial flow of an exhaust air flow from the side of an electric driven blower receiving room is bypassed through a partial portion of an inner wall of the vacuum cleaner main body. In other words, this inner wall portion of the vacuum cleaner main body is positioned between the electric driven blower receiving room and the exhaust air flow passage being adjacent the electric driven blower receiving room. In the above stated vacuum cleaner having the resonance type silencer mechanism structure the exhaust air flow is not directly exhausted to the outside from the side of the electric driven blower receiving room, since the partial flow of the exhaust air flow is bypassed, the sound energy is converted to heat energy during passing through the exhaust air flow bypass passage in the vacuum cleaner main body. Accordingly, the exhaust air noise reduction effect in the vacuum cleaner main body may be expected to some degree. However, in the above stated conventional vacuum cleaner having the resonance type silencer mechanism structure, since the length of the exhaust air flow passage is merely increased, the exhaust air noise passing through the vacuum cleaner main body still remains large. Therefore there is room for improving the the vacuum cleaner structure so that a sufficient silencing effect for the exhaust air in the vacuum cleaner main body can be obtained. DE-C-641 371 discloses a vacuum cleaner, in which the exhaust air from a motor driven blower is guided through labyrinth channels surrounding the driving motor of the blower. The labyrinth channels are defined by sound absorbing walls concentric with the rotation axis of the driving motor. DE-A-34 02 603 discloses a vacuum cleaner comprising a casing for accomodating a motor and a blower. The motor is surrounded by a cup-shaped insulation housing having air outlet openings on the upper and lower side. The exhaust air from the blower passing through the outlet openings on the upper side is guided by a guide wall to a flow channel in the lower portion of the casing. In order to reduce the noise level of this known vacuum cleaner an insulating slab is provided on the bottom portion of the casing along which the air flowing through the air outlet openings on the lower side of the insulation housing is guided. Moreover, at the air outlet opening of the casing a latticed air guide plate made of foam material is provided. In a vacuum cleaner known from EP-A-0 099 466 the exhaust air of the blower and the cooling air of the motor are separately guided through longer channels and chambers with multiple changes of direction. The channels are concentrically disposed around the motor and are covered with a sound absorbing material. In a vacuum cleaner disclosed in EP-A-0 257 606 the exhaust air from a motor driven blower is guided into an exhaust air chamber at the rear portion of the blower receiving chamber via an air passage formed in an intermediate wall between the exhaust air chamber and the blower receiving chamber. The exhaust air chamber is surrounded by an intermediate exhaust air port and a first air passage is formed to guide the air from the intermediate exhaust air port to an outlet opening. A second air passage is formed to guide the exhaust air to a further opening to which a hose may be coupled. The object of the invention is to provide a vacuum cleaner having a highly integrated silencer mechanism with an improved noise reduction and a facilitated assembly of the silencer mechanism. This object is solved by the features of claim 1. Dependent claims are directed on preferred embodiments of the invention. The exhaust air duct is provided between the blower cover and the cord winding apparatus receiving room and forms a resistance type silencer mechanism for the exhaust air flow passage in which the exhaust air flow bypasses from the side of the blower receiving room. In the exhaust air flow from the side of the blower receiving room, since the sound energy of the exhaust air flow is converted to heat energy during the passing time in the resistance type silencer mechanism for the exhaust air flow bypass passage, accordingly the exhaust air flow noise in the vacuum cleaner main body can be widely reduced. In the noise level reduction technique field, in comparison with the resonance type silencer mechanism, there has been known that the resistance type silencer mechanism can reduce the noise level peaks at a plurality of the frequency bands. Due to this it is preferable to put the resistance type silencer mechanism into the vacuum cleaner main body and therefore the exhaust air noise at the vacuum cleaner main body can be reduced widely. Further since the exhaust air duct, which is provided between the blower cover surrounding the electric driven blower and the cord winding apparatus receiving room, is integrally formed with the blower cover, the integration of the parts of the silencer mechanism for the vacuum cleaner main body can be attained easily. Therefore, the number of the parts required for noise reduction can be restrained and also the assembly of the silencer mechanism can be facilitated. Further, the production costs of the vacuum cleaner can be reduced. Since the sound absorption cover comprising the sound absorption material member is disposed between the blower cover surrounding the electric driven blower and the blower, the reduction effect for the exhaust air noise can be effectively attained. Since the sound absorption material member is put in the inner side wall of the exhaust air duct, the reduction effect for the exhaust air noise in the vacuum cleaner main body can be effectively attained. The expansion room is provided between the exhaust air duct and the exhaust air port of the vacuum cleaner main body. Furthermore the expansion room has a cross-sectional area larger than a cross-sectional area of the exhaust air port of the exhaust air duct. As a result thereof, the exhaust air from the electrically driven blower is expanded in the electric driven blower receiving room and thereafter is compressed in the exhaust air duct. The exhaust air is further reexpanded in the expansion room, which is provided between the exhaust air port of the exhaust air duct and the exhaust air port of the vacuum cleaner main body. Due to this expansion effect and the compression effect of the resistance type silencer mechanism, the reduction for exhaust air noise in the vacuum cleaner main body can be effectively attained. Brief Description of the Drawings: Fig. 1 is a plane view showing one embodiment of a vacuum cleaner main body having a silencer mechanism according to the present invention; Fig. 2 is a vertical cross-sectional front view showing one embodiment of a vacuum cleaner main body having a silencer mechanism according to the present invention; Fig. 3 is a horizontal cross-sectional view showing a partial portion of a vacuum cleaner main body having a silencer mechanism according to the present invention; Fig. 4 is a cross-sectional side view showing a partial portion of a vacuum cleaner main body having a silencer mechanism according to the present invention; Fig. 5 is an outside appearance showing one embodiment of an electric driven blower cover of a vacuum cleaner main body having a silencer mechanism according to the present invention; Fig. 6 is an outside appearance showing an upper blower cover of an electric driven blower cover according to the present invention; and Fig. 7 is another outside appearance showing an upper blower cover of an electric driven blower cover according to the present invention. One embodiment of a vacuum cleaner having a silencer mechanism according to the present invention will be now explained. A vacuum cleaner having a silencer mechanism comprises a flat-type vacuum cleaner main body 1 having a lower main case 2 and an upper main case 4 both made of a synthetic resin material. A dust collecting cover 3 is positioned at the upper main case 4, a handle portion 5 is positioned at a front portion of the vacuum cleaner main body 1, and a shock absorbing bumper member 6 is provided at an outer peripheral portion of the vacuum cleaner main body 1. In the interior of the vacuum cleaner main body 1, an electrically driven blower 7, a cord winding apparatus 8 and a dust collecting bag 9 etc. are disposed. A caster 10 is provided at a front bottom portion of the lower main case 2, and two wheels 11 are provided at a rear bottom portion of the lower main case 2. Further, a receiving portion 12 for holding an extension pipe is provided at the front bottom portion of the lower main case 2. A receiving portion 13 for receiving various attachment suction nozzles is provided at a rear upper portion of the upper main case 4. A lid 14 for opening or closing the attachment suction nozzle receiving portion 13 is mounted at an upper portion of the attachment suction nozzle receiving portion 13. The attachment suction nozzles comprise a convergent nozzle 15 for cleaning the clearance, a suction nozzle 16 having a brush 17 at a tip thereof for cleaning the shelf, and a T-shaped suction nozzle 18 for cleaning the clothes. Three suction nozzles 15, 16, and 18 are accomodated respectively in the attachment suction nozzle receiving portion 13. Between the attachment suction nozzle receiving portion 13 and an exhaust air port 19 of the vacuum cleaner main body 1, a filter case 21 having an exhaust air filter member 20 is received and can be taken out freely from the vacuum cleaner main body 1. The exhaust air filter member 20 is designed such that the dust is caught through utilizing static electricity. An exhaust air-tight packing member 22 is provided on the filter case 21 in order to maintain an air tight state between the filter case 21 having the exhaust air filter member 20 and the upper main case 4. A rectifying filter member 50 is provided at an opening portion of the vacuum cleaner main body 1 and is disposed at the front side of the filter case 21. The attachment suction nozzle receiving portion 13 is positioned between an exhaust air duct 42 and the exhaust air port 19 of the vacuum cleaner main body 1 and has a comparatively wide space. This space portion is constituted to work as an expansion room 23 for the exhaust air flow. Namely, between an exhaust air port 46 of the exhaust air duct 42 and the exhaust air port 19 of the vacuum cleaner main body 1, the expansion room 23 is provided. The expansion room 23 has a cross-sectional area larger than that of the exhaust air port 46 of the exhaust air duct 42. A dust indicator 24, for indicating a time for throwing the dust in the dust collecting bag 9, is provided on the upper portion of the upper main case 4. Further, a dust indicator cover 25 for holding the dust indicator 24 from outside is provided on the upper portion of the upper main case 4. On both sides of the dust indicator cover 25 a switch pedal 26 for opening or closing a power source switch and a reel pedal 27 for operating the stopping or the starting for the cord winding apparatus 8 are provided. At the front portion of the dust collecting cover 3 a cramp 28 is supported by a cramp spring member 29 in an elasticity state for opening or closing the dust collecting cover 3. At the upper portion of the dust collecting cover 3 a hose inserting port 30 is provided. A hose inserting portion 31 of the hose inserting port 30 is pivotally held by the dust collecting cover 3 and a dust collecting inner side lid 32 so as to pivotally support the hose inserted in the hose inserting portion 31. At the upper portion of the hose inserting port 30 a hose inserting port cover 33 is provided to close the hose collecting port 30 when the vacuum cleaner is not in use. Further, at the hose inserting portion 31 an air-tight packing member 34 is provided to maintain an air-tight state between the hose inserted in the hose inserting portion 31 and the hose collecting port 30. A lid packing member 35 is provided between the dust collecting cover 3 and the dust collecting inner side lid 32 to maintain an air-tight state between the dust collecting cover 3 and the dust collecting inner side lid 32. The dust collecting bag 9 is held by longitudinal ribs 36 provided on the lower main case 2 and by a filter stand member 37. The dust collecting cover 3 is pivotally supported by the upper main case 4 and is constituted to cause the opening operation or the closing operation by a buffer spring member 38 during the lid opening or lid closing operation. A secondary filter member 39 is mounted between the dust collecting bag 9 and the electrically driven blower 7. The blower 7 is disposed in an blower receiving room 40 and the cord winding apparatus 8 is disposed in a cord winding apparatus receiving room 41, respectively. The exhaust air duct 42 is positioned between the blower receiving room 40 and the cord winding apparatus receiving room 41 and is provided so as to introduce the exhaust air flowing from the side of the blower receiving room 40. The blower receiving room 40 is constituted with an inner wall portion of the lower main case 2 and an outer peripheral portion of a blower cover 43 made of a sythetic resin material. In this embodiment of the present invention the blower cover 43 is constituted integrally with the exhaust air duct 42. At the inner side of the exhaust air duct 42 a sound absorption member 44 made of a polyurethane foam material etc. is adhered. The exhaust air duct 42 has a U-shaped exhaust air flow passage and comprises an intake port 45 for introducing the exhaust air flow at an inlet portion thereof from the blower 7, and an exhaust air port 46 at an outlet portion thereof. A rectifying filter member 51 is provided at the front side of the intake port 45 and is disposed inside the blower cover 43. The blower 7 has respectively rubber cushion insulator members 47 and 48 at the front portion and the rear portion thereof and also has a silencer cover 49 made of a sound absorption material at the outer peripheral portion thereof. One embodiment of the silencer mechanism for the vacuum cleaner according to the present invention will be explained in detail as follows. The silencer mechanism for the vacuum cleaner main body 1 mainly comprises the exhaust air duct 42. The exhaust air duct 42 made of a synthetic resin material is constituted integrally with the electric driven blower cover 43 made of a synthetic resin material at the side portion thereof. The blower cover 43 comprises an upper blower cover 43a and a lower blower cover 43b. The upper blower cover 43a of the blower cover 43 is mainly received in the upper main case 4 of the vacuum cleaner main body 1. The lower blower cover 43b of the electric driven blower cover 43 is received in the lower main case 2 of the vacuum cleaner main body 1. The upper blower cover 43a of the blower cover 43 substantially has a box form having a downwardly semicircular opening at the front portion thereof. The lower blower cover 43b of the blower cover 43 substantially has a box form having an upwardly semicircular opening at the front portion thereof. Two semicircular openings of the upper blower cover 43a and the lower blower cover 43b form a substantially circular opening for introducing the sucked air flow from the dust collecting portion between the outer wall portion of the blower 7 and the inner wall portion of blower cover 43. The upper blower cover 43a of the blower cover 43 has the intake port 45 with a rectangular opening for the exhaust air duct 42 at the rear upper portion thereof. The exhaust air duct 42 comprises a side wall portion of the upper blower cover 43a having the intake port 45 of the exhaust air duct 42, an outer peripheral wall portion rib 42a projecting toward the side of the cord winding apparatus receiving room 41, and a side wall portion rib 42b, so that the exhaust air duct 42 forms a U-shaped exhaust air flow passage. The outer peripheral wall portion rib 42a of the exhaust air duct 42 is designed to surround the outer peripheral portion of the upper blower cover 43a of the blower cover 43, except for one front side part of the lower outer peripheral portion of the upper blower cover 43a, and further, to extend downwardly toward the side of the lower blower cover 43b of the blower cover 43. The outer peripheral wall portion rib 42a of the exhaust air duct 42 is formed projectingly and integrally with the upper blower cover 43a of the blower cover 43. The side wall portion rib 42b of the exhaust air duct 42 extends toward the front side directions of both the upper blower cover 43a and the lower blower cover 43b of the blower cover 43. The side wall portion rib 42b of the exhaust air duct 42 is formed integrally with the upper blower cover 43a of the blower cover 43 in parallel with the side wall portions of the upper blower cover 43a and the lower blower cover 43b. The exhaust air duct 42 further comprises a vertical, rectangularly shaped rib 52 on the upper main case 4 and a vertical, rectangularly shaped rib 53 on the lower main case 2. The exhaust air duct 42 is partitioned with the two vertical ribs 52 and 53 of the vacuum cleaner main body 1 at the cord winding apparatus receiving room 41 side. The exhaust air duct 42 is formed at the side wall of the blower cover 43 and the side of the cord winding apparatus receiving room 41. Namely, the exhaust air duct 42 is formed between the outer side wall of the upper blower cover 43a and the outer side wall of the lower blower cover 43b of the blower cover 43. The outer peripheral wall portion rib 42a of the exhaust air duct 42 has a partition rib 42d for partitioning the exhaust air flow, and a guide rib 42c for guiding the exhaust air flow. The partition rib 42d of the exhaust air duct 42 is disposed directly below the intake port 45 of the exhaust air duct 42. The partition rib 42d of the exhaust air duct 42 is formed so as to partition the exhaust air flow in the exhaust air duct 42. The partition rib 42d of the exhaust air duct 42 leads the exhaust air flow from the rear side of the vacuum cleaner main body 1 to the front side of the vacuum cleaner main body 1 at the side wall portion of the upper blower cover 43a of the blower cover 43. The partition rib 42d of the exhaust air duct 42 leads the exhaust air flow from the front side of the vacuum cleaner main body 1 to the rear side of the vacuum cleaner main body 1 at the side wall portion of the lower blower cover 43b. The guide rib 42c of the exhaust air duct 42, which is formed integrally with the outer peripheral wall portion rib 42a, has a curved portion so as to smoothly guide the exhaust air flow toward the downstream side in the exhaust air duct 42. The guide rib 42c of the exhaust air duct 42 projects and extends to the lower side of the upper blower cover 43a. The lowermost portion of the guide rib 42c of the exhaust air duct 42 is positioned at the bottom portion of the lower blower cover 43b. If the above stated vacuum cleaner is in the power source switch-on condition, the sucked air flows into the dust collecting portion and the outer peripheral portion of the electric driven blower 7 and is discharged into the blower receiving room 40 or into the blower cover 43. Next, the exhaust air from the blower receiving room 40 flows into the intake port 45 of the exhaust air duct 42, into which the exhaust air from the blower 7 is passed, and is compressed at the intake port 45 of the exhaust air duct 42, and further flows into the downstream side of the exhaust air duct 42. Due to the U-shaped flow passage of the exhaust air duct 42, the exhaust air is guided from the rear side of the vacuum cleaner main body 1 to the front side of the vacuum cleaner main body 1 along the side wall portion of the upper blower cover 43a of the blower cover 43 by the outer peripheral wall portion rib 42a of the exhaust air duct 42 in cooperation with the partition rib 42d of the exhaust air duct 42 and the vertical rib 52 of the upper main case 4. The exhaust air is guided from the upper side of the upper blower cover 43a to the lower side of the lower blower cover 43b by the guide rib 42c of the exhaust air duct 42 in cooperation with the side wall portion rib 42b of the exhaust air duct 42 and the vertical rib 52 of the upper main case 4. Thereafter, the exhaust air is passed from the front side of the vacuum cleaner main body 1 to the rear side of the vacuum cleaner main body 1 to the rear side of the vacuum cleaner main body 1 along the side wall portion of the lower blower cover 43b of the blower cover 43, in cooperation with the guide rib 42c of the exhaust air duct 42 and the vertical rib 53 of the lower main case 2. The exhaust air flows into the expansion room 23 from the exhaust air port 46 of the exhaust air duct 42. The exhaust air from the lower blower cover 43b is guided upwardly to the rear wall portions of the lower blower cover 43b and the upper blower cover 43a. After the exhaust air has been expanded in the expansion room 23 the exhaust air passes through the rectifying filter member 50 and the exhaust air filter member 20, and is then discharged from the exhaust air port 19 of the vacuum cleaner main body 1 at an outside portion. Since the blower cover 43 surrounding the outer peripheral portion of the blower 7 is provided as a means for holding the blower 7, the vacuum cleaner main body 1 has a double structure comprising the blower cover 43 and the upper main case 4. The vacuum cleaner main body 1 further has a triple structure comprising the dust indicator cover 25 and the opening or closing lid 14 in addition to the blower cover 43 and the upper main case 4. Accordingly, the noise caused by the exhaust air passing through the vacuum cleaner main body 1 and generated by the electrically driven blower 7, can be widely reduced. In addition to the above stated structure, the exhaust air duct 42 is provided between the blower cover 43 and the cord winding apparatus receiving room 41. The exhaust air duct 42 forms a resistance type silencer mechanism for the exhaust air flow passage in which the exhaust air flow bypasses from the side of the blower receiving room 40. In the exhaust air flow from the side of the blower receiving room 40 the sound energy of the exhaust air flow is converted to heat energy while passing through the resistance type silencer mechanism for the exhaust air flow bypass passage. Accordingly, the exhaust air noise in the vacuum cleaner main body 1 can be widely reduced. Further, since the exhaust air duct 42 provided between the blower cover 43 and the cord winding apparatus receiving room 41 is integrally formed with the electric driven blower cover 43, an integration of the parts of the silencer mechanism of the vacuum cleaner main body 1 can be easily attained. Therefore, the number of parts required for noise reduction in the vacuum cleaner main body 1 can be kept to a minimum. More over, the assembly of the silencer mechanism is facilitated, and, furthermore the production costs for the vacuum cleaner can be reduced. Since the sound absorption cover 49 comprising the sound absorption material member is disposed between the blower cover 43 and the blower 7, the reduction effect for the exhaust air noise in the vacuum cleaner main body 1 can be effectively attained. Since the sound absorption material member 44 is put inside of the exhaust air duct 42 the reduction effect for the exhaust air noise in the vacuum cleaner main body 1 can be effectively attained. The expansion room 23 is provided between the exhaust air port 46 of the exhaust air duct 42 and the exhaust air port 19 of the vacuum cleaner main body 1. Furthermore, the expansion room 23 has a cross-sectional area larger than the cross-sectional area of the exhaust air port 46 of the exhaust air duct 42. As a result thereof the exhaust air from the electrically driven blower 7 is expanded in the electric driven blower receiving room 40 and thereafter is compressed in the exhaust air duct 42. The exhaust air is further reexpanded in the expansion room 23, which is provided between the exhaust air port 46 of the exhaust air duct 42 and the exhaust air port 19 of the vacuum cleaner main body 1. Due to this expansion effect and the compression effect by the resistance type silencer mechanism, the reduction effect for the exhaust air noise in the vacuum cleaner main body 1 can be attained effectively.

Claims: A vacuum cleaner having a silencer mechanism comprising a vacuum cleaner main body (1) having an upper main case (4) and a lower main case (2), an electric driven blower (7) provided between said upper and said lower main case (4, 2), a cord winding apparatus (8) provided between said upper and said lower main case (4, 2) at a side portion of said blower (7), a dust collecting apparatus (9) provided between said upper and lower main case (4, 2) in a front portion of said main body (1), a blower receiving room (40) for receiving said electric driven blower (7) provided between said upper and lower main case (4, 2), a cord winding apparatus receiving room (41) for receiving said cord winding apparatus (8) provided between said upper and lower main case (4, 2) at a side portion of said blower receiving room (40), an expansion room (23) provided at a rear portion of said electric driven blower receiving room (40), a blower cover (43) disposed between said blower receiving room (40), and said expansion room (23), and an exhaust air duct (42) disposed between said blower cover (43) and said cord winding apparatus receiving room (41), said exhaust air duct (42) communicating through an intake port (45) with said blower receiving room (40) and by an exhaust air port (46) with said expansion room (23), said expansion room (23) being disposed between said exhaust air port (46) and an exhaust air port (19) of said main body (1), characterized in that the exhaust air duct (42) is formed integrally with said blower cover (43) at a side portion of said blower cover (43), said exhaust air duct (42) is partitioned with a rib (52) of said upper main case (4) and a rib (53) of said lower main case (2) at a side of said cord winding apparatus receiving room (41), and said exhaust air duct (42) forms an exhaust air flow passage for bypassing exhaust air from a side of said blower receiving room (40) to a side of said expansion room (23). Vacuum cleaner according to claim 1, characterized in that said exhaust air flow passage in said exhaust air duct (42) is formed with a flow passage bypassing from said intake port (45) to said exhaust air port (46) of said exhaust air duct (42) in a U-shaped form. Vacuum cleaner according to claim 2, characterized in that said exhaust air duct (42) comprises a partitioning rib (42d) and a guiding rib (42c), said partitioning rib (42d) partitions the exhaust air flow from a rear side of said exhaust air duct (42) to a front side of said exhaust air duct (42) at an upper portion of said exhaust air duct (42) and further the exhaust air flow from the front side of said exhaust air duct (42) to the rear side of said exhaust air duct (42) at a lower portion of said exhaust air duct (42), said guiding rib (42c) guides the exhaust air flow from an upper side of said exhaust air duct (42) to a lower side of said exhaust air duct (42), and said partitioning rib (42d) leads the exhaust air flow passing through said guiding rib (42c) from the front side of said exhaust air duct (42) to the rear side of said exhaust air duct (42), thereby the exhaust air is bypassed in the U-shaped form from said intake port (45) of said exhaust air duct (42) to said exhaust air port (46) of said exhaust air duct (42). Vacuum cleaner according to claim 3, characterized in that each of said partitioning rib (42d) and said guiding rib (42c) of said exhaust air duct (42) is formed integrally respectively with said blower cover (43). Vacuum cleaner according to claim 4, characterized in that said blower cover (43) comprises an upper blower cover (43a) and a lower blower cover (43b), and each of said partitioning rib (42d) and said guiding rib (42c) of said exhaust air duct (42) is formed integrally respectively with said upper blower cover (43a). Vacuum cleaner according to claim 5, characterized in that said partitioning rib (42d) of said exhaust air duct (42) is formed integrally with said upper blower cover (43a), said guiding rib (42c) of said exhaust air duct (42) is formed integrally with said upper blower cover (43a) and said guiding rib (42c) of said exhaust extends downwardly toward said lower blower cover (43b). Vacuum cleaner according to any one of the claims 1 to 6, characterized in that a sound absorption cover (49) comprising a sound absorption material member is disposed between said blower cover (43) and said electric driven blower (7). Vacuum cleaner according to any one of the claims 1 to 7, characterized in that a sound absorption material member (44) is put in an inner side of said exhaust air duct (42). Vacuum cleaner according to claim 1, characterized in that the expansion room (23) formed between said exhaust air port (46) of said exhaust air duct (42) and the exhaust air port (19) of said main body (1) has a cross-sectional area larger than a cross-sectional area of said exhaust air port (46) of said exhaust air duct (42).

Inventors: IWAO AKIRA, SUNAGAWA MASAO, IWAO, AKIRA, SUNAGAWA, MASAO
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1989
Main classification: A47L9
IPC codes: A47L9