Resiliently-coupled drive wheel assembly for self-propelled vacuum cleaner

Abstract

A wheel assembly for a self-propelled apparatus such as a vacuum cleaner is disclosed. The self-propelled apparatus includes a drive motor, a drive axle coupled to the drive motor, and at least one drive wheel assembly. The drive wheel assembly includes a drive member rotatably secured to the drive axle, an outer wheel casing at least partially surrounding the drive member, and a resilient coupling mechanism for establishing a rotational engagement between the drive member and the outer wheel casing after a predetermined amount of rotation of the drive member relative to the outer wheel casing.

What is claimed is:  
     
         1 . A wheel assembly for a vacuum cleaner having a drive axle mechanically coupled to a drive source, the wheel assembly comprising: 
 a drive member rotatably secured to the drive axle;    a wheel casing at least partially surrounding the drive member; and    a resilient coupling that establishes a rotational engagement between the drive member and the wheel casing after a predetermined amount of rotation of the drive member relative to the wheel casing.    
     
     
         2 . The wheel assembly of  claim 1 , wherein the resilient coupling includes a resistance means and a damping means, the resistance means exhibiting a linear resistance versus displacement characteristic and the damping means exhibiting a linear resistance versus velocity characteristic.  
     
     
         3 . The wheel assembly of  claim 1 , wherein the resilient coupling includes at least one of a resistance means and a damping means, the resistance means exhibiting a linear resistance versus displacement characteristic and the damping means exhibiting a linear resistance versus velocity characteristic.  
     
     
         4 . The wheel assembly of  claim 1 , wherein the resilient coupling includes at least one elastic member secured to the drive member and the wheel casing, the elastic member exhibiting a linear resistance versus displacement characteristic.  
     
     
         5 . The wheel assembly of  claim 1 , wherein the resilient coupling includes at least one coil spring having a first end secured to the drive member and a second end secured to the wheel casing.  
     
     
         6 . The wheel assembly of  claim 1 , wherein the resilient coupling includes at least one damping member secured between the drive member and the wheel casing, the damping member exhibiting a linear resistance versus velocity characteristic.  
     
     
         7 . The wheel assembly of  claim 1 , wherein the resilient coupling includes at least one dashpot having a first end secured to the drive member and a second end secured to the wheel casing.  
     
     
         8 . The wheel assembly of  claim 1 , wherein the wheel casing includes a wheel housing having a cavity that accommodates the drive member, the cavity having a plurality of projections that cooperate to define a plurality of chamber portions, and the drive member having a plurality of vanes each positioned within a respective chamber portion.  
     
     
         9 . The wheel assembly of  claim 8 , wherein the resilient coupling includes at least one coil spring positioned between one of the plurality of drive member vanes and one of the plurality of projections.  
     
     
         10 . The wheel assembly of  claim 9 , wherein the resilient coupling further includes at least one dashpot positioned between another one of the plurality of drive member vanes and another one of the plurality of projections.  
     
     
         11 . The wheel assembly of  claim 8 , wherein the resilient coupling includes at least one dashpot positioned between one of the plurality of drive member vanes and one of the plurality of projections.  
     
     
         12 . The wheel assembly of  claim 1 , wherein 
 the wheel casing includes a wheel housing having a cavity that accommodates the drive member and a wheel cover that encloses the cavity,    the drive member includes first and second disk-shaped end walls separated by a reduced diameter cylindrical portion that defines a channel, and    the resilient coupling includes at least one elastic member having a first end secured to the drive member within the channel and a second end that is fixed for rotation with the wheel casing.    
     
     
         13 . The wheel assembly of  claim 12 , wherein the resilient coupling further includes an arcuate groove defined in the first disk-shaped end wall, and a drive pin fixed for rotation with the wheel casing, a free end of the drive pin extending into the arcuate groove, the drive member rotating into abutment with the drive pin to establish a positive rotational engagement between the drive member and the wheel casing after the predetermined amount of rotation of the drive member relative to the wheel casing.  
     
     
         14 . A self-propelled vacuum cleaner comprising: 
 a drive motor;    a drive axle coupled to the drive motor; and    at least one drive wheel assembly including a drive member rotatably secured to the drive axle, an outer wheel casing surrounding the drive member, and a resilient coupling that establishes a positive rotational engagement between the drive member and the wheel casing after the predetermined amount of rotation of the drive member relative to the wheel casing.    
     
     
         15 . The vacuum cleaner of  claim 14 , wherein the resilient coupling includes at least one spring linking the drive member to the outer wheel casing.  
     
     
         16 . The vacuum cleaner of  claim 15 , wherein the resilient coupling further includes at least one dashpot linking the drive member to the outer wheel casing.  
     
     
         17 . The vacuum cleaner of  claim 14 , wherein the wheel casing includes a wheel housing having a cavity that accommodates the drive member, the cavity having a plurality of projections that cooperate to define a plurality of chamber portions, and the drive member having a plurality of vanes each positioned within a respective chamber portion.  
     
     
         18 . The vacuum cleaner of  claim 17 , wherein the resilient coupling includes at least one coil spring positioned between one of the plurality of drive member vanes and one of the plurality of projections.  
     
     
         19 . The vacuum cleaner of  claim 18 , wherein the resilient coupling further includes at least one dashpot positioned between another one of the plurality of drive member vanes and another one of the plurality of projections.  
     
     
         20 . The vacuum cleaner of  claim 17 , wherein the resilient coupling includes at least one dashpot positioned between one of the plurality of drive member vanes and one of the plurality of projections.  
     
     
         21 . The vacuum cleaner of  claim 14 , wherein 
 the wheel casing includes a wheel housing having a cavity that accommodates the drive member and a wheel cover that encloses the cavity,    the drive member includes first and second disk-shaped end walls separated by a reduced diameter cylindrical portion that defines a channel, and    the resilient coupling includes at least one elastic member having a first end secured to the drive member within the channel and a second end that is fixed for rotation with the wheel casing.    
     
     
         22 . The vacuum cleaner of  claim 21 , wherein the resilient coupling further includes an arcuate groove defined in the first disk-shaped end wall, and a drive pin fixed for rotation with the wheel casing, a free end of the drive pin extending into the arcuate groove, the drive member rotating into abutment with the drive pin to establish a positive rotational engagement between the drive member and the wheel casing after the predetermined amount of rotation of the drive member relative to the wheel casing.  
     
     
         23 . A method of propelling a vacuum cleaner including a drive motor, a drive axle coupled to the drive motor, and at least one drive wheel assembly having a drive member rotatably secured to the drive axle, the at least one drive wheel assembly further including an outer wheel casing surrounding the drive member, and a resilient coupling that establishes a positive rotational engagement between the drive member and the wheel casing after the predetermined amount of rotation of the drive member relative to the wheel casing, the method comprising: 
 rotating the drive axle and the drive member while maintaining the outer wheel casing stationary for a predetermined period of time; and    establishing a positive rotational engagement between the drive member and the outer wheel casing after the predetermined period of time has elapsed to cause the outer wheel casing to rotate.    
     
     
         24 . The method of  claim 23 , wherein 
 the step of rotating includes the subsidiary step of rotating a semi-circular channel associated with the drive member about a drive pin associated with the outer wheel casing, and    the step of establishing includes the subsidiary step of contacting the wheel drive pin with an end wall of the semi-circular channel.    
     
     
         25 . The method of  claim 24 , wherein 
 the step of rotating further includes the subsidiary step of tensioning at least one spring linking the drive member to the outer wheel casing.    
     
     
         26 . The method of  claim 23 , wherein the step of rotating further includes the subsidiary step of compressing at least one elastic member linking the drive member to the outer wheel casing.  
     
     
         27 . The method of  claim 26 , wherein the step of rotating further includes the subsidiary step of tensioning at least another elastic member linking the drive member to the outer wheel casing.  
     
     
         28 . The method of  claim 26 , wherein the step of rotating step further includes the subsidiary step of compressing at least one damping member linking the drive member to the outer wheel casing.  
     
     
         29 . The method of  claim 23 , wherein the step of rotating further includes the subsidiary step compressing at least one elastic member and at least one damping member, and tensioning at least another elastic member and at least another damping member.