Patent Publication Number: US-2011070994-A1

Title: Differential with Coaxial Input Axle and Output Axle Assembly for Facilitating Reverse Gear

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to differentials of motor vehicles and more particularly to a differential of a motorcycle having a coaxial input axle and output axle assembly for facilitating a reverse gear. 
     2. Description of Related Art 
     Conventionally, a differential of a motorcycle has a fixed gear ratio. This is not desirable. Moreover, it is difficult of replacing the gear of the typical differential. In addition, it has the disadvantages of being difficult of assembly and disassembly, being time consuming and labor intensive in repair, and being cost ineffective. 
     A conventional differential  90  of a motorcycle with variable gear ratio is shown in  FIG. 6 . A non-axial design is implemented by the well known differential  90 . Hence, a number of limitations and drawbacks exist. For example, sprocket meshed with an input axle may interfere with an output axle. The sprocket meshed with input axle cannot be replaced with a larger sprocket. Moreover, gear ratio change is limited, input force is relatively distal from output force, and space is small. Thus, a need for improvement exists. 
     SUMMARY OF THE INVENTION 
     It is therefore one object of the invention to provide a differential for a motor vehicle, comprising a coaxial input axle and output axle assembly comprising an input axle and an output axle spaced from the input axle; a first gear mounted on the coaxial input axle and output axle assembly; a second gear mounted on the coaxial input axle and output axle assembly and spaced from the first gear coaxially, the second gear being operatively connected to the output axle; a clutch mounted on the coaxial input axle and output axle assembly between the first gear and the second gear and operatively connected to the coaxial input axle and output axle assembly wherein a distance between the first gear and the input axle is less than that between the second gear and the input axle; a first driven shaft comprising a third gear mounted thereon for operatively connecting thereto, the third gear being meshed with the first gear; and a second driven shaft comprising a fourth gear and a fifth gear mounted on both ends thereof wherein the fourth gear is meshed with the third gear and the fifth gear is meshed with the second gear; whereby in a first mode, engaging the clutch with the second gear will transmit power from the input axle to the output axle with both the input axle and the output axle rotating in the same direction; and whereby in a second mode, engaging the clutch with the first gear will transmit power from the input axle to the output axle by engaging the first driven shaft with the second driven shaft with the input axle and the output axle rotating in an opposite direction. 
     In one aspect of the invention there are further provided two oil seals disposed at both ends of the coaxial input axle and output axle assembly. 
     In another aspect of the invention there is further provided a bearing mounted between the oil seals. 
     By utilizing the invention, the following advantages can be obtained. The input axle and the output axle are mounted coaxially and together are adapted to effectively carry out forward gear or reverse gear operation. The typical drawbacks including a sprocket meshed with an input axle being incapable of being replaced with a larger sprocket, gear ratio change being limited, input force being relatively distal from output force, and space being small are eliminated. Most importantly, different gear ratios can be implemented depending on load and speed requirements and a drive source is not limited to a single kind. For example, the drive source can be implemented as an internal combustion engine or an electric motor. 
     The above and other objects, features and advantages of the invention will become apparent from the following detailed description taken with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a differential according to the invention where forward gear operation is shown; 
         FIG. 2  is a side elevation of  FIG. 1  with a drive source being operatively connected thereto; 
         FIG. 3  is a cross-sectional view of the differential according to the invention where reverse gear operation is shown; 
         FIG. 4  is a side elevation of  FIG. 3  with the drive source being operatively connected thereto; 
         FIG. 5  is a perspective view of the differential according to the invention; and 
         FIG. 6  is a perspective view of a conventional differential of a motorcycle with variable gear ratio. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 to 5 , a differential in accordance with the invention is shown. The differential is mounted in a motorcycle as a preferred embodiment of the invention. The differential has a coaxial input axle and output axle assembly for facilitating reverse gear as detailed below. 
     The differential comprises a coaxial input axle and output axle assembly  10 , a first gear  20 , a second gear  30 , a clutch  40 , a first driven shaft  50 , and a second driven shaft  60 . Each of above components will now be described in detail below. 
     The coaxial input axle and output axle assembly  10  comprises an input axle  11  and an output axle  12 . A drive source  70  has its power transmitted to a sprocket  80  via a chain (not numbered). The input axle  11  is in turn rotated by the sprocket  80 . The first gear  20  on mounted in the coaxial input axle and output axle assembly  10 . The second gear  30  is also mounted on the coaxial input axle and output axle assembly  10  but spaced from the first gear  20  coaxially. The second gear  30  can transmit power to the output axle  12 . The clutch  40  is mounted on the coaxial input axle and output axle assembly  10  between the first gear  20  and the second gear  30 . The clutch  40  is operatively connected to the coaxial input axle and output axle assembly  10 . The first gear  20  is proximate to the input axle  11  while the second gear  30  is distal the input axle  11 . A third gear  51  is mounted on the first driven shaft  50  so as to transmit power thereto. The third gear  51  is meshed with the first gear  20 . A fourth gear  61  and a fifth gear  62  are mounted on both ends of the second driven shaft  60 . The fourth gear  61  is meshed with the third gear  51 . The fifth gear  62  is meshed with the second gear  30 . 
     As shown in  FIGS. 1 and 2 , a person may manipulate a lever (not shown) to engage the clutch  40  with the second gear  30 . Hence, power may be transmitted from the input axle  11  to the output axle  12  with both the input axle  11  and the output axle  12  rotating in the same direction (e.g., counterclockwise). 
     As shown in  FIGS. 3 and 4 , alternatively, the person may manipulate the lever to engage the clutch  40  with the first gear  20 . Hence, power may be transmitted from the input axle  11  to the output axle  12  via the meshing engagement of the first driven shaft  50  and the second driven shaft  60  with the input axle  11  and the output axle  12  rotating in an opposite direction (e.g., the input axle  11  counterclockwise rotating and the output axle  12  clockwise rotating). 
     The drive source  70  can be implemented as an internal combustion engine or an electric motor. Hence, its applications are not limited. 
     The coaxial input axle and output axle assembly  10  further comprises two oil seals  13  at both ends thereof. That is, the oil seals  13  are mounted at the input axle  11  and the output axle  12  respectively. 
     The coaxial input axle and output axle assembly  10  further comprises a bearing  14  mounted between the other oil seal  13  on the output axle  12  and the second gear  30 . 
     The invention has the following advantages. The input axle  11  and the output axle  12  are mounted coaxially and together are adapted to effectively carry out forward gear or reverse gear operation. Hence, the well known drawbacks including the sprocket meshed with input axle being incapable of being replaced with a larger sprocket, gear ratio change being limited, input force being relatively distal from output force, and space being small are eliminated. Most importantly, different gear ratios can be implemented depending on load and speed requirements and the drive source  70  is not limited to a single kind. For example, the drive source  70  can be implemented as an internal combustion engine or an electric motor. 
     While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.