Abstract:
A floor cleaning apparatus is disclosed including a nozzle assembly having an agitator cavity and a handle assembly pivotally connected to the nozzle assembly. The apparatus further includes a rotary agitator carried on the nozzle assembly in the agitator cavity. A dirt collection vessel is carried on either the nozzle assembly or the handle assembly. A drive linkage interconnects a drive motor with the rotary agitator. The drive linkage includes a ring gear including a dog clutch receiver and a dog clutch carried on the rotary agitator. The dog clutch engages the dog clutch receiver to interconnect the drive motor and the rotary agitator during normal operating conditions. In the event of an agitator Jam, the dog clutch functions to interrupt drive to the rotary agitator and protect the drive motor, rotary agitator and drive linkage from damage that might otherwise result from the overload.

Description:
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION 
       [0001]    The present invention relates generally to the floor care equipment field and, more particularly, to a floor cleaning apparatus incorporating a drive linkage between a drive motor and rotary agitator that interrupts drive to the rotary agitator in the presence of an agitator jam. 
       BACKGROUND OF THE INVENTION 
       [0002]    A vacuum cleaner is an electro-mechanical appliance utilized to effect the dry removal of dust, dirt and other small debris from carpets, rugs, fabrics or other surfaces in domestic, commercial and industrial environments. In order to achieve the desired dirt and dust removal, most vacuum cleaners incorporate a rotary agitator. The rotary agitator is provided to beat dirt and debris from the nap of the carpet or rug while a pressure drop or vacuum is used to force air entrained with this dirt and debris into the nozzle of the vacuum cleaner. The particulate laden air is then drawn into a dirt collection vessel. The air is then drawn through a filter before being directed through the motor of the suction generator to provide cooling. Finally, the air is filtered to remove any fine particles of carbon from the brushes of that motor or other dirt that might remain in the air-stream before being exhausted back into the environment. 
         [0003]    It has long been known that the drive train and motor must be protected from damage in the event of an agitator jam whether due to a bearing seizure, a foreign object stuck between the agitator and the nozzle assembly housing, ingestion of the power cord or other event. Presently there are two main types of agitator drive systems employed in the vacuum cleaner industry: (1) belt-drive and (2) gear-drive. All such systems usually include a mechanism to prevent damage to the drive train in the event the agitator becomes jammed. 
         [0004]    Belt-drive systems provide an inherent safeguard since the belt itself serves as an inexpensive, expendable weak-link, stretching or breaking at an overload condition and thereby preventing damage to the agitator and motor. Gear-drive systems generally rely upon an overload protector. Such a protector trips or opens a circuit to the agitator drive motor when the current drawn by that motor exceeds a pre-described threshold value anticipated to be produced during an agitator jam. A gear-drive system may, however, sustain gear-tooth fracture as the current ramps up to the threshold value that interrupts power to the drive motor. 
         [0005]    The present invention relates to a floor cleaning apparatus equipped with a drive linkage between the agitator and agitator drive motor that incorporates a spring-loaded dog clutch that will interrupt drive to the agitator when the rotary agitator becomes jammed for any reason. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with the purposes of the current invention as described herein, a floor cleaning apparatus is provided comprising a nozzle assembly including an agitator cavity and a handle assembly pivotally connected to the nozzle assembly. A rotary agitator is carried on the nozzle assembly in the agitator cavity. A dirt collection vessel is carried on one of the nozzle assembly and the handle assembly. A drive linkage interconnects a drive motor with the rotary agitator. The drive linkage includes a ring gear having a dog clutch receiver and a dog clutch carried on the rotary agitator. The dog clutch engages the dog clutch receiver to interconnect the drive motor with the rotary agitator. In the event of an agitator jam, the dog clutch functions to interrupt drive from the drive motor to the rotary agitator thereby preventing damage to the apparatus. 
         [0007]    More specifically describing the invention, the dog clutch includes a cam carried on a locating lug and a biaser that biases the cam into engagement with the dog clutch receiver. In one possible embodiment the biaser is a compression spring that is received around the locating lug. A cavity provided in the rotary agitator receives the locating lug and compression spring. 
         [0008]    In one possible embodiment the drive linkage comprises a worm gear drive. More specifically a worm gear is connected to a drive shaft of the drive motor and the ring gear comprises a cooperating worm wheel connected to the agitator. A dog clutch receiver in the form of an annular series of cam receiving grooves is provided on an inner surface of the worm wheel, The drive motor is interconnected with the rotary agitator when the cam of the dog clutch is received in one of the series of cam receiving grooves. Typically the cam has a radius of curvature of between about 1 mm and about 4 mm. The compression spring has a biasing force of between about 9 N and about 34 N. The cam and the locating lug have a weight between about 0.5 g and about 2.5 g. Further each receiving groove of the dog clutch receiver has a radius of curvature of between about 1 mm and about 4 mm and a depth of between about 0.5 mm and about 2 nm, The drive linkage may include multiple dog clutches on the rotary agitator. Two of the multiple dog clutches may be provided in opposing positions. 
         [0009]    Still further describing the invention the rotary agitator typically includes an axle, a body received over the axle and a cleaning element carried on the body. The axle is typically made of metal while the body is typically molded from plastic. The cleaning element is typically a series of bristle tufts. A bearing assembly is provided at each end of the axle to provide for free rotary movement of the agitator relative to the nozzle assembly. The ring gear may be provided on the rotary agitator adjacent one end of the axle. Alternatively, the body may include two sections and the ring gear Inlay be provided on the rotary agitator adjacent a center line of the rotary agitator between those two sections. 
         [0010]    In the following description there is shown and described several different embodiments of the invention, simply by way of illustration of some of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying drawings incorporated herein and forming a part of the specification, illustrate several aspects of the present invention and together with the description serve to explain certain principles of the invention. In the (drawings: 
           [0012]      FIG. 1  is a perspective view of the floor cleaning apparatus of the present invention; 
           [0013]      FIG. 2  is an exploded perspective view of one possible embodiment of the rotary agitator, drive motor and drive linkage of the present invention; 
           [0014]      FIGS. 3A and 3B  are both partially schematical and cross sectional views illustrating, respectively, engagement of the ring gear by the dog clutch during normal vacuum cleaner operation whereby power is transmitted from the agitator drive motor to the agitator and the retraction of the dog clutch and the interruption of drive between the drive motor and agitator in the event of an agitator jam condition; 
           [0015]      FIGS. 4A and 4B  are similar to  FIGS. 3A and 3B  but illustrate the force vectors and contact points; and 
           [0016]      FIG. 5  is an exploded perspective view of an alternative embodiment of the rotary agitator, drive motor and drive linkage of the present invention. 
       
    
    
       [0017]    Reference will now be made in detail to the present preferred embodiments of this invention, examples of which are illustrated in the accompanying drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Reference is now made to  FIG. 1  showing the upright vacuum cleaner  10  of the present invention. The upright vacuum cleaner  10  includes a housing comprising a nozzle assembly  14  and a handle or canister assembly  16 . The handle assembly  16  includes a control handle  18  and a handgrip  20 . A control switch  22  is provided for turning the vacuum cleaner  10  on and off. Of course, electrical power is supplied to the vacuum cleaner  10  from a standard electrical wall outlet through an electrical cord (not shown). 
         [0019]    A pair of rear wheels (not shown) are provided on the lower portion of the handle assembly  16  and a pair of front wheels (also not shown) are provided on the nozzle assembly  14 . Together these wheels support the vacuum cleaner  10  for movement across the floor. To allow for convenient storage of the vacuum cleaner  10 , a foot latch ( 24 ) functions to lock the canister assembly in an upright position as shown in  FIG. 1 . When the foot latch is released, the canister assembly  16  may be pivoted relative to the nozzle assembly  14  as the vacuum cleaner  10  is manipulated back and forth to clean the floor. 
         [0020]    In the presently illustrated embodiment, the handle assembly  16  includes a cavity adapted to receive and hold a dirt collection vessel  32 . The dirt collection vessel  32  may take the form of a dirt cup  34  including a cylindrical sidewall  36 , a tangentially directed inlet and an axially directed outlet. A primary filter  40  may be provided in the dirt cup  34  over the axially directed outlet. The primary filter  40  is cylindrical in shape and concentrically received within the cylindrical sidewall  36  of the dirt cup  34 . Such a structural arrangement induces cyclonic airflow in the dirt cup  34  and provides for enhanced cleaning efficiency. In an alternative design, the handle assembly  16  includes a closed compartment that houses a filter or vacuum cleaner bag, of a type known in the art, which functions as the dirt collection vessel  32 . 
         [0021]    The nozzle assembly  14  includes an agitator cavity  44 . A rotary agitator  46  is carried on the nozzle assembly  14  in the agitator cavity  44 . A suction generator  48 , including a final and a cooperating drive motor  52 , is carried on the canister assembly  16 . The suction generator  48  functions to generate a vacuum air stream for drawing dirt and debris from the surface to be cleaned. In one possible embodiment, the rotary agitator  46  is connected by power take off to the motor  52  of the suction generator  48 . In another possible embodiment, the rotary agitator  46  is driven by a separate, dedicated agitator drive motor  52 . While the suction generator  48  is illustrated as being carried on the handle assembly  16 , it should be appreciated that, alternatively, it could be carried on the nozzle assembly  14  if desired. 
         [0022]    During normal operation, the rotary agitator  46  is driven by the motor  52  of the suction generator  48  and functions to beat dirt and debris from the nap of an underlying carpet. The suction generator  48  functions to draw a vacuum air stream into the agitator cavity  44 . Dirt and debris from the carpet is entrained in the air stream, which is then drawn by the suction generator  48  into the dirt cup  34 , Dirt and debris is captured in the dirt cup  34  while relatively clean air is drawn through the primary filter  40 . That air stream passes over the motor  52  of the suction generator  48  to provide cooling before being exhausted through a final filter, such as a HEPA filter (not shown) before being exhausted through an exhaust port  38  into the environment. 
         [0023]    A first embodiment of the rotary agitator  46 , drive motor  52  and drive linkage  54  is illustrated in detail in  FIG. 2 . As illustrated, the rotary agitator  46  comprises an axle  56 , a body  58  received over the axle and a cleaning element  60  carried on the body. Typically the axle  56  is made of a strong metal such as steel while the body  48  is molded from a plastic such as ABS, nylon, polyvinyl chloride, or polypropylene. In the illustrated embodiment, the cleaning element  60  comprises bristle tufts. It should be appreciated, however, that substantially any other type of cleaning element known in the art may be utilized including but not limited to a beater bar, wiper, squeegee, or the like. 
         [0024]    More specifically describing the embodiment illustrating in  FIG. 2 , the body  58  comprises two sections  62   a ,  62   b  that are keyed together by cooperating lugs  64  at the center line of the agitator body  58 . The body  58  is hollow and the two opposing ends of the body are closed by end caps  66 . Cooperating nuts and washers  67  are received over and secured to threaded ends of the axle  56  to hold the agitator body  58  and axle  56  together. Each of the end caps  66  has a cavity that holds a bearing assembly  68 . The bearing assemblies  68  at each end of the rotary agitator  46  allow the rotary agitator to rotate or spin freely with respect to the bearing caps  70 , which are provided at the outermost ends of the rotary agitator  46 , said caps incorporating flanges that allow the mounting of the rotary agitator in the nozzle assembly  14  in a manner known in the art. 
         [0025]    As should be further appreciated from reviewing FIGS.  2 , 3   a  and  3   b , the drive linkage  54  includes a ring gear  72  in the form of a worm wheel. The ring gear  727  meshes with a worm gear  74  that is connected to the drive shaft  76  of the drive motor  52 . The interface of the ring gear  72  includes a dog clutch receiver  78  comprising an annular series of cam receiving grooves  80 . Typically the ring gear  72  is made from metal such as SMF  5040 . 
         [0026]    The ring gear  72  is mounted on the agitator body  58  at the centerline thereof overlying the lugs  64  that interconnect and key the two sections  62   a ,  62   b  of the body  58  together. As molded, the lugs  64  are inset relative to the outer circumference of the rest of the body  58  so as to form a channel to receive and hold the ring gear  72  in position. 
         [0027]    The drive linkage  54  also includes a dog clutch, generally designated by reference numeral  82 . The dog clutch  82  comprises a cam  84  carried on a locating lug  86 . The dog clutch  82  is carried on the rotary agitator  58 . More specifically, the lug  64  on the body section  62   b  includes a cavity  88 . The locating lug  86  of the dog clutch  82  is received in this cavity  88 . A biaser, in the form of a compression spring  90 , is received around the locating lug  86  and held in the cavity  88 . 
         [0028]    The dog clutch  82  is typically made from a metal such as steel. The cam  84  on the dog clutch typically has a radius of curvature of between about 1 mm and about 4 mm. The compression spring  90  typically has a biasing force of between about 9 N and about 34 N. The cam  84  and locating lug  86  of the dog clutch  82  typically have a weight of between about 0.5 g and about 2.5 g. Each receiving groove  80  of the dog clutch receiver  78  typically has a radius of curvature of between about 1 mm and about 4 mm and a depth of between about 0.5 mm and about, 2 mm. 
         [0029]    As illustrated in  FIGS. 3A and 4A , during normal vacuum cleaner operation, the biasing compression spring  90  and the centrifugal force acting upon the dog clutch  82  as a result of the high speed rotation of the agitator  46  causes the cam  84  to fully nest and stay within one of the grooves  80  of the dog clutch receiver  78 . This functions to key the ring gear  72  to the body  58  of the rotary agitator  46  thereby interconnecting the drive motor  52  with the rotary agitator  46 . Thus, during normal operating conditions, the drive linkage  54  maintains a radially directed resultant force F R  on the cam  84  at the point C. This force may be represented by additive sub-component forces F X  and F Y . Within normal running torque ranges, the spring force F S  of the compression spring  90  exceeds F Y  such that the cam remains in the home position fully nested in the groove  80  of the dog clutch receiver  78  so as to transfer gear torque to the agitator  46 . In the illustrated embodiment, two opposing dog clutches  82  are illustrated and the running torque is 2(F X *r). During normal operation 2(F X *r) exceeds the opposing torque F O *R generated by the drag force F O  of the carpet/tuft interaction. 
         [0030]    In the event the agitator becomes jammed for any reason (see  FIG. 4B ), then F O  increases to a maximum F max  governed by the maximum torque capability of the drive motor  52  and 2(F X *r)=F max *R. At this value of F X , the additive F Y  is increased to exceed F S , resulting in the compression of the spring  90  and the retraction of the cam  84  so that the cam is no longer nested in a groove  80  of the dog clutch receiver  78 . The disengagement of the cam  84  of the dog clutch  82  from the groove  80  interrupts drive between the motor  52  and the rotary agitator  46 . More specifically, the worm gear  74  on the drive shaft  76  of the drive motor  52  continues to turn the ring gear  72  but the ring gear is no longer keyed to the agitator body  58 . Thus, the meshing gears  72 ,  74  continue to turn so that the teeth are not damages but the agitator  46  is disconnected from the ring gear  72  and remains stationary. In this way, damage to the rotary agitator  46 , the drive linkage  54  and the drive motor  52  is prevented in a jam condition. 
         [0031]    An alternative embodiment of the rotary agitator  46  is illustrated in  FIG. 4 . In this embodiment, the agitator body  58  is a single piece that accepts a fitting  92  at one end thereof for receiving one or more dog clutches  82  and the ring gear  72  in the manner described above. The resulting drive linkage  54  functions in the manner previously described in the first embodiment illustrated in  FIG. 2  to interrupt drive in the event of a jam and prevent damage from occurring to the drive motor  52 , drive linkage  54  or the rotary agitator  46 . 
         [0032]    The foregoing description of the preferred embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated, All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled. The drawings and preferred embodiments do not and are not intended to limit the ordinary meaning of the claims in their fair and broad interpretation in any way.