Vacuum cleaner

An upright vacuum cleaner includes a floor nozzle having a rotatable brush housed therein for operative contact with a surface to be cleaned, a main cleaner assembly coupled with the floor nozzle and accommodating a motor-driven fan having a motor shaft and a filter therein, a flexible power transmitting shaft for transmitting rotative power from the motor-driven fan to the rotatable brush along a power transmitting path between the motor shaft and the rotatable brush, and an intermediate power transmitting mechanism including a torque limiter mechanism disposed in the power transmitting path for cutting off power transmission from the motor shaft to the rotatable brush when the rotatable brush is subjected to a torque greater than a preset torque.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an upright vacuum cleaner having a main 
cleaner assembly to which a floor nozzle having a rotatable brush or 
agitator is coupled. 
2. Description of the Prior Art 
Prior upright vacuum cleaners include, among other things, a motor-driven 
air blower or fan in a main cleaner assembly for drawing in dust and dirt, 
and a motor in a floor nozzle for rotating a rotatable brush or agitator. 
Since the conventional upright vacuum cleaner requires two separate 
motors, it has been disadvantageous in that it is heavy and costly, and 
the floor nozzle itself is large in size, rendering cleaning a tedious and 
time-consuming operation. 
To eliminate the above shortcomings, it has been proposed to have the 
motor-driven fan positioned in a lower portion of the main cleaner 
assembly, with the agitator driven by a belt trained around a rotating 
shaft of the motor-driven fan. However, the proposed vacuum cleaner 
suffers the following difficulties: 
Since it is necessary to draw air from the floor nozzle up to an upper 
portion of the main cleaner assembly, because of the low position of the 
motor-driven fan, an air suction passage through the main cleaner assembly 
is necessarily long and presents increased resistance to air flow, 
reducing the ability of the vacuum cleaner to draw dust and dirt. Another 
drawback is that the motor-driven fan has an axis extending transversely 
across the main cleaner assembly, which is therefore of increased width. 
The wide main cleaner assembly cannot be handled with ease for cleaning. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a vacuum cleaner which 
is compact, of high performance, and easily handled in use. 
A vacuum cleaner according to the present invention includes a floor nozzle 
housing a rotatable brush or agitator therein, a main cleaner assembly 
coupled to the floor nozzle and accommodating a motor-driven air blower or 
fan and a filter, and a shaft for transmitting rotative power from the 
motor-driven fan to the rotatable brush through an intermediate power 
transmitting mechanism. Since the motor-driven fan disposed in the main 
cleaner assembly is used for both drawing dust and dirt and driving the 
rotatable brush, the vacuum cleaner is small in size and lightweight in 
its entirety, and can be handled with increased ease. The motor-driven fan 
has its suction side located downwardly with a dust collection chamber 
therein, so that an air suction passage from the floor nozzle up to the 
dust collection chamber is shortened.

DETAILED DESCRIPTION 
Like or corresponding parts are denoted by like or corresponding reference 
characters throughout the views. 
FIGS. 1 through 5 illustrate a vacuum cleaner according to an embodiment of 
the present invention. As shown in FIGS. 1 through 3, the vacuum cleaner 
includes a floor nozzle 1 housing a rotatable brush or agitator 2, and a 
main cleaner assembly 3 of a substantially square cross section (FIG. 5) 
coupled vertically and angularly movable to the floor nozzle 1 through a 
coupling cylinder 3'. The main cleaner assembly 3 accommodates a 
motor-driven air blower or fan 4 supported by vibroisolating members 4a, 
4b as of rubber in an upper portion of the main cleaner assembly 3. The 
main cleaner assembly 3 has a dust collection chamber 6 positioned in a 
lower suction side of the motor-driven fan 4, the dust collection chamber 
6 being opened and closed by a cover 5 and housing a filter 7 adjacent to 
the motor-driven fan 4. An intermediate power transmitting mechanism 8 
including a clutch is disposed in the main cleaner assembly 3 at one of 
four corners of the the main cleaner assembly 3 of substantially square 
cross section. The intermediate power transmitting mechanism 8 has an 
attachment base 9 fastened by a bolt 9a on the motor-driven fan 4, as 
shown in FIGS. 2 and 4. The motor-driven fan 4 includes a motor shaft 10 
extending upwardly. 
As shown in FIG. 4, the intermediate power transmitting mechanism 8 is 
composed of bearings 12 in which a clutch shaft 11 parallel to the motor 
shaft 10 is rotatably journalled, a drive pulley 13 fixed on the clutch 
shaft 11, and an idler pulley 14 rotatably mounted on the clutch shaft 11. 
The bearings 12 are mounted in the attachment base 9. A flat belt 15 is 
trained under an adjusted tension around the motor shaft 10 and 
selectively around the pulleys 13 or 14. The belt 15 can axially be 
shifted to pulley 13 or 14 by means of a belt shifter 16 including an 
actuator lever 16a pivotably mounted by a pivot pin 16b in an upper front 
portion of the main cleaner assembly 3. As shown in FIGS. 1 through 4, a 
handle 17 projects upwardly from an upper end of the main cleaner assembly 
3. In FIG. 1, a grip 25 is fixed to an upper end of the handle 17. The 
main cleaner assembly 3 has air outlet ports 18 defined in a side wall 
thereof. 
As best illustrated in FIG. 3, the floor nozzle 1 accommodates therein a 
bearing 20 in which a pulley shaft 19 parallel to the agitator 2 is 
rotatably journalled, the pulley shaft 19 having a pulley 21 on an end 
thereof, a pulley 22 mounted on an end of the agitator 2, and a flat belt 
23 trained around the pulleys 21, 22. A flexible power transmitting shaft 
24 has one end coupled to the clutch shaft 11 in substantial alignment 
therewith and an opposite end to the pulley shaft 19 in substantial 
alignment therewith. The flexible power transmitting shaft 24 extends 
through the corner of the main cleaner assembly 3 in which the 
intermediate power transmitting mechanism 8 is located, is arcuately 
curved in its portion extending substantially between the main cleaner 
assembly 3 and the floor nozzle 1, and lies in a rear side portion of the 
floor nozzle remote from the corner of the main cleaner assembly 3 
accommodating the shaft 24 and in which rear side portion the shaft 24 is 
connected to the pulley shaft 19. Therefore, rotative power from the 
clutch shaft 11 can be smoothly be transmitted via the shaft 24 to the 
pulley shaft 19 without imposing undue load on the shaft 24. 
Operation of the vacuum cleaner thus constructed is as follows: When the 
belt 15 is shifted to the drive pulley 13 and the motor-driven fan 4 is 
actuated, rotative power from the motor-driven fan 4 is transmitted 
through the motor shaft 10, the belt 15, the drive pulley 13, and thence 
through the clutch shaft 11 and the power transmitting shaft 24 to the 
pulley shaft 19 in the floor nozzle 1. Then, the rotative power is 
transmitted from the pulley 21 through the belt 23 and the pulley 22 to 
the agitator 2 to thereby rotate the same about its own axis. 
Dust is now agitated by the rotating agitator 2 from a material being 
cleaned such as a rug into the floor nozzle 1 from which the dust is 
carried by a suction air stream into the dust collection chamber 6. 
When a bare floor such as a wooden floor is to be cleaned with the vacuum 
cleaner, the lever 16a is turned to depress the belt shifter 16 to shift 
the belt 15 from the drive pulley 13 to the idler pulley 14. Rotative 
power is then transmitted from the motor shaft 10 through the belt 15 to 
the idler pulley 14. Since the idler pulley 14 rotates idly on the clutch 
shaft 11, the clutch shaft 11 is not rotated, and hence the agitator 2 is 
not rotated. 
The intermediate power transmitting mechanism 8 will be described in 
detail. When the agitator 2 is stopped due for example to biting 
engagement with a rug while cleaning the latter, the motor-driven fan 4 
would be stopped and subjected to the danger of a burnout. Therefore, it 
is necessary to interrupt the rotative power from the motor-driven fan 4 
when the agitator 2 is forcibly stopped. To meet such a requirement, the 
intermediate power transmitting mechanism 8 has a torque limiting 
capability for cutting off power transmission when a torque greater than a 
predetermined level is applied to the agitator 2. More specifically, while 
the agitator 2 is in rotation, the belt 15 is trained around the motor 
shaft 10 and the drive pulley 13. When the agitator 2 is forcibly stopped, 
the drive pulley 13 is also brought to a stop. Since the belt 15 is 
subjected to an adjusted tension, a slippage occurs between the motor 
shaft 10 and the belt 15, thus allowing the motor shaft 10 to be 
continuously rotated without being stopped. 
The clutch shaft 11, the bearings 12, the drive pulley 13, and the idler 
pulley 14 of the intermediate power transmitting mechanism 8 are assembled 
together in fixed positional relationship to the attachment base 9 which 
is fastened to the motor-driven fan 4. The interaxial distance of the belt 
15 between the motor shaft 10 and the pulley 13 or 14 can be adjusted to a 
nicety for suitably tensioning the belt 15 by positioning the attachment 
base 9 with respect to the motor-driven fan 4. In addition, the 
intermediate power transmitting mechanism 8 can easily be assembled in 
position. 
With the foregoing arrangement, dust and dirt can be drawn and the agitator 
2 can be driven by the single motor. Therefore, the floor nozzle 1 may be 
small in size and the main cleaner assembly 3 may be small in width. Since 
the dust collection chamber 6 is located below the motor-driven fan 4, an 
air suction passage from the floor nozzle 1 up to the dust collection 
chamber 6 is short. 
The intermediate power transmitting mechanism 8 and the power transmitting 
shaft 24 are disposed together in series in one corner of the main cleaner 
assembly 3, and hence require no excessive installation space in the main 
cleaner assembly 3, a feature which contributes to a further reduction in 
the width and weight of the main cleaner assembly 3. Furthermore, since 
there is no sharp bend in the flexible power transmitting shaft 24 at its 
connecting ends and anywhere intermediate therebetween, any loss in the 
power transmitted by the shaft 24 is held to a minimum. 
The intermediate power transmitting mechanism 8 also has a speed-change 
capability achieved by the belt 15 in addition to the clutch and torque 
limiter capabilities. 
The vacuum cleaner illustrated in FIGS. 1 through 5 has the following 
advantages: 
The vacuum cleaner is lightweight reduced cost since dust and dirt can be 
collected and the agitator 2 can be driven by a single motor. Since the 
intermediate power transmitting mechanism 8 has a torque limiter 
capability, the vacuum cleaner can be used with safety. Because the floor 
nozzle 1 is small in size and the main cleaner assembly 3 is small in 
width, the vacuum cleaner can easily be handled in cleaning operation. The 
air suction passage from the floor nozzle to the dust collection chamber 
is short and hence produces only a small pressure loss, with the result 
that the vacuum cleaner is of high dust drawing performance. No special 
space, other than the space defined in and by the shape of the main 
cleaner assembly 3, is required for the installation of the intermediate 
power transmitting mechanism 8 and the power transmitting shaft 24. This 
is also effective in allowing the main cleaner assembly 3 to be small in 
width, lightweight, and easy to use. Since the power transmitting shaft 24 
is connected in series to the intermediate power transmitting mechanism 8, 
is curved gradually arcuately, and connected to the pulley shaft 19 in 
substantial alignment therewith, any loss in rotative power transmitted by 
the shaft 24 is minimized. Therefore, the vacuum cleaner is highly 
effifcient in operation. 
A vacuum cleaner according to another embodiment will be described with 
reference to FIG. 6. A shift lever 26 is pivotably connected to the belt 
shifter 16 and has one end pivotably coupled to a control rod 27 extending 
through the handle 17 and connected to a control lever 27a (FIG. 6A) 
mounted on the grip 25. When the shift lever 26 is in the solid-line 
position of FIG. 6, the belt 15 is trained around the drive pulley 13 to 
rotate the agitator 2 (FIGS. 2 and 3) in response to rotation of the 
motor-driven fan 4. When the shift lever 26 is turned to the broken-line 
position, the belt 15 is shifted to the idler pulley 14 to stop the 
agitator. 
With the construction of FIG. 6, the agitator can be rotated and stopped by 
operating the control lever on the grip 25, and hence cleaning modes can 
easily be selected on the grip 25. The control lever on the grip 25 may be 
operatively associated with an ON-OFF switch coupled with a power supply 
for the motor-driven fan 4. Other arrangements may be employed to actuate 
the belt shifter 16 in response to operation of the control lever on the 
grip 25. For example, the belt shifter 16 may be actuated by a solenoid 
which is energizable and de-energizable by operation of the control lever. 
FIG. 7 illustrates still another embodiment of the present invention. The 
intermediate power transmitting mechanism 8 shown in FIG. 7 is of 
substantially the same construction as that of the intermediate power 
transmitting mechanism according to the first embodiment shown in FIGS. 1 
through 5. The power transmitting shaft 24 is coupled to the clutch shaft 
11 of the intermediate power transmitting mechanism 8 within the main 
cleaner assembly 3. The power transmitting shaft 24 has a substantial 
elongate portion, below the intermediate power transmitting mechanism 8, 
which is positioned outside of the main cleaner assembly 3. The 
arrangement of FIG. 7 is advantageous for various reasons. Since the power 
transmitting shaft 24 does not extend through the dust collection chamber 
in the main cleaner assembly 3, it is not necessary to provide a 
hermetical seal within the dust collection chamber with respect to the 
shaft 24. The main cleaner assembly 3 can therefore be constructed of 
simple parts and assembled with ease. As the substantial length of the 
shaft 24 is disposed outside of the main cleaner assembly 3, these 
components can easily be assembled. Should the shaft 24 be cut off or 
otherwise damaged, it can easily be detached for repair or replacement, 
and the repaired or replaced shaft 24 can easily be mounted in place. 
The power transmitting shaft 24 will be described in greater detail with 
reference to FIGS. 2 through 4. To give the motor-driven fan 4 which is 
relatively small in size a sufficient suction capability, the motor shaft 
10 is rotated at 20,000 rpm. The drive pulley 13 operatively coupled by 
the belt 15 to the motor shaft 10 is rotated at 8,000 rpm due to a speed 
reduction ability of the belt 15. The power transmitting shaft 24 is 
composed of an inner wire 28 coupled to the clutch shaft 11 and an 
opposite end to the pulley shaft 19. The inner wire 28 is therefore 
rotated at 8,000 rpm. For cleaning a rug thoroughly with the agitator 2, 
the agitator 2 is required to be rotated at about 4,000 rpm. The pulley 
21, the belt 23, and the pulley 22 jointly serve as a speed reducer to 
reduce the speed of rotation of the pulley shaft 19 by half and transmits 
the slowed rotation to the agitator 2, and also as a torque limiter 
mechanism identical in function to the torque limiter mechanism of the 
intermediate power transmitting mechanism 8. 
The above-specified numbers of rpm are determined by the various 
components, especially the power transmitting shaft 24. 
Where the inner wire 28 has an outside diameter of 2.5 mm, the power 
transmitting shaft 24 is generally capable of transmitting a torque up to 
0.4 kg - cm and can be curved to an arcuate shape having a radius of 
curvature R (FIG. 3) greater than 60 mm as can be seen from the following 
table: 
______________________________________ 
Allowable inner wire performance 
Outside dia. 
Radius of curvature 
Transmitted torque 
______________________________________ 
2 mm &gt;50 mm &lt;0.13 kg - cm 
2.5 mm &gt;60 mm &lt;0.4 kg - cm 
3.2 mm &gt;100 mm &lt;1.2 kg - cm 
______________________________________ 
The power required for rotating the agitator 2 which has double rows of 
bristles and an outside diameter of 50 mm is 0.8 kg - cm or 32.9 W 
measured at 4,000 rpm. Therefore, the load torque of the inner wire 28 is 
0.4 kg - cm. 
A durability test was conducted in which a rug was cleaned under the above 
condition with the inner wire 28 of 2.5 mm across, curved at a radius of 
curvature R of 60 mm (the main cleaner assembly 3 had a width of 120 mm 
and the floor nozzle 1 had a width of 350 mm). It was confirmed in the 
test that the inner wire 28 had a service life of at least 1,000 hours. 
Where the power transmitting shaft 24 is to be disposed within or 
substantially outside of the main cleaner assembly 3, it is important that 
the shaft 24 be housed in the compact main cleaner assembly 3 with the 
radius of curvature R as small as possible. To meet such a requirement, 
the inner wire 28 should be as thin as possible to reduce the radius of 
curvature R. However, the torque that can be transmitted by the shaft 24 
is reduced as shown in the above table. It is preferable therefore to use 
the inner wire 28 which is capable of transmitting a small torque, rotated 
at a high speed, and as thin as possible. These conditions for use of the 
inner wire have been found by carrying out many experiments, based on 
which the foregoing specific conditions have been achieved. 
In actual use, the agitator 2 frequently bites into the rug and is locked 
thereby against rotation. As described earlier, the intermediate power 
transmitting mehcanism 8 has a torque limiter mechanism for preventing the 
motor from suffering a burnout if the agitator 2 is locked. The allowable 
torque that can be transmitted by the inner wire 28 is 0.4 kg - cm, as 
described, which is about 1/10 of a torque by which the inner wire 28 can 
be cut off. When the torque transmitted by the inner wire 28 exceeds 1 kg 
- cm immediately before the agitator 2 is locked, the intermediate power 
transmitting mechanism 3 with the torque limiter capability is disabled to 
stop the inner wire 28, and no more torque is transmitted by the inner 
wire 28. The inner wire 28 is thus protected from damage. 
There is a clearance between the inner wire 28 and the outer wire 29 with 
grease filled in the clearance for allowing the inner wire 28 to rotate 
smoothly in the outer wire 29. When the inner wire 28 is rotated at a high 
speed, however, sounds are produced due to sliding engagement between the 
inner and outer wires 28, 29. In addition, since the agitator 2 is 
subjected to a varying load, the torque imposed on the agitator 2 also 
varier, and the inner wire 28 vibrates. To prevent such noise and 
vibration from being transmitted to the main cleaner assembly 3 and the 
floor nozzle 1, the outer wire 29 is mounted by a vibroisolating member 
29a to the attachment base 9. 
The power transmitting shaft 24 may be curved in its entirety to keep the 
inner and outer shafts 28, 29 in contact with each other under a constant 
force for thereby preventing the inner wire 28 from being vibrated and 
permitting the same to rotate stably. 
The inner and outer wires 28, 29 of the shaft 24 will be described in 
greater detail with reference to FIGS. 8 and 9. The inner wire 28 is 
composed of a core wire 30 in the form of a steel wire having a diameter 
of 0.34 mm, first-layer winding wires 31 in the form of four parallel 
steel wires each having a diameter of 0.36 mm and helically wound around 
the core wire 30, second-layer winding wires 32 in the form of four 
parallel steel wires each having a diameter of 0.36 mm and helically wound 
around the first-layer winding wires 31 in close contact therewith in a 
direction opposite to that in which the first-layer winding wires 31 are 
helically wound, and third- or outermost-layer winding wires 33 in the 
form of six steel wires each having a diameter of 0.36 mm and helically 
wound around the second-layer winding wires 32 in close contact therewith 
in a direction opposite to that in which the second-layer winding wires 32 
are helically wound. The wires of the inner wire 28 are pressed together 
at one end thereof by an inner wire retainer 34 of a square cross section 
inserted in the clutch shaft 11 for transmitting rotative power from the 
clutch shaft 11 to the inner wire 28. However, the inner wire retainer 34 
may be dispensed with, and the end of the inner wire 28 may be 
cross-sectionally shaped at its end for insertion in the clutch shaft 11. 
When the inner wire retainer 34 is rotated about its own axis in the 
direction of the arrow 38 in FIG. 9, the outermost-layer wires 33 of the 
inner wire 28 are tightened to produce a torrional force with which a 
large torque can be transmitted. Therefore, the allowable torque as 
referred to above can be transmitted by the inner wire 28 when rotating 
the same in the direction of the arrow 38. 
If the inner wire retainer 34 were rotated in the direction of the arrow 
39, then the outermost-layer wires 33 would be loosened to reduce the 
allowable torque which could be transmitted to half. If the inner wire 28 
were subjected to a torque greater than the half of the allowable torque, 
then the outermost-layer wires 33 would be separated from the second-layer 
wires 32, resulting in a failure to transmit the torque. 
The outer wire 29 is composed of an inner tubular core 35 comprising a 
steel wire of a rectangular cross section helically wound in close 
contact, a cover 36 of synthetic resin or rubber covering the outer 
peripheral surface of the core 35, and a cap 37 of metal or synthetic 
resin mounted on an end of the outer wire 29, the inner wire 28 extending 
through the cap 37. 
Since the inner core 35 comprises a steel wire, it presents a small 
frictional resistance with respect to the inner wire 28, and can be curved 
to an arcuate shape of an even radius of curvature. The cap 37 is 
effective in preventing any leakage of the grease filled in the clearance 
between the inner wire 28 and the inner core 35 of the outer wire 29. The 
cover 36 serves to absorb or attenuate vibrations and noise generated upon 
rotation of the inner wire 28 within the outer wire 29, and also to 
prevent grease leakage. 
The power transmitting shaft 24 can be used for most effective torque 
transmission when rotated about its own axis in a direction to tighten the 
outermost-layer wires 33 of the inner wire 28. The power transmitting 
shaft 24 of the above construction is of a compact design and inexpesnive 
to manufacture. 
Although certain preferred embodiments of the present invention have been 
shown and described in detail, it should be understood that various 
changes and modifications may be made therein without departing from the 
scope of the appended claims.