Power transmission device for a scooter

Abstract

A power transmission device for a powered scooter is provided. The power transmission device includes a drive shaft, a driven shaft and two or more timing belt transmission device. The timing belt transmission device includes a first sprocket wheel attached on the drive shaft, a second sprocket wheel attached on the driven shaft, and a timing belt wound on the first sprocket wheel and the second sprocket wheel. The ratio of the diameter of the first sprocket wheel and the diameter of the second sprocket wheel is predetermined to provide a desired speed change ratio. The timing belt may be made of rubber or chain.

What is claimed is:  
     
         1 . A power transmission device for a powered scooter comprising: 
 a) a drive shaft;    b) a driven shaft; and    c) two or more timing belt transmission devices; 
 wherein each of the timing belt transmission devices includes a first sprocket wheel attached on the drive shaft, a second sprocket wheel attached on the driven shaft, and a timing belt wound on the first sprocket wheel and the second sprocket wheel;  
 wherein the ratio of the diameter of the first sprocket wheel and the diameter of the second sprocket wheel is predetermined.  
   
     
     
         2 . The power transmission device for a powered scooter of  claim 1  wherein the timing belt is made of rubber and has teeth that engage with the teeth of the first and second sprocket wheels.  
     
     
         3 . The power transmission device for a powered scooter of  claim 2  further comprising an automatic clutch connected to the drive shaft, wherein the automatic clutch transmits power of an engine of the powered scooter when the engine rotates above a predetermined rotational speed, and the automatic clutch does not transmit power of the engine when the engine rotates below a predetermined rotational speed.  
     
     
         4 . The power transmission device for a powered scooter of  claim 2  further comprising a housing that encloses the drive shaft, the driven shaft and the timing belt transmission devices.  
     
     
         5 . The power transmission device for a powered scooter of  claim 4  wherein the housing has recesses and bearings received in the recesses, wherein the drive shaft and the driven shaft are supported by the bearings.  
     
     
         6 . The power transmission device for a powered scooter of  claim 1  wherein the timing belt is a chain that has a plurality of links that engage with the teeth of the first and second sprocket wheels.  
     
     
         7 . The power transmission device for a powered scooter of  claim 6  further comprising an automatic clutch connected to the drive shaft, wherein the automatic clutch transmits power of an engine of the powered scooter when the engine rotates above a predetermined rotational speed, and the automatic clutch does not transmit power of the engine when the engine rotates below a predetermined rotational speed.  
     
     
         8 . The power transmission device for a powered scooter of  claim 6  further comprising a housing that encloses the drive shaft, the driven shaft and the timing belt transmission devices.  
     
     
         9 . The power transmission device for a powered scooter of  claim 8  wherein the housing has recesses and bearings received in the recesses, wherein the drive shaft and the driven shaft are supported by the bearings.