Abstract:
In a one-way clutch, an outer retainer includes tapered surfaces formed by chamfering axially opposite side edges of an outermost part at a projection of the outer retainer, thereby facilitating the assembly of the clutch in an outer ring. In addition, a sufficient contact width is provided between the outer ring and the projection by forming the tapered surfaces at axially opposite ends of the outer retainer, thereby preventing the occurrence of cracks in the outer retainer.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a one-way clutch for use, for example, in automotive transmissions. 
     DESCRIPTION OF THE PRIOR ART 
     FIG. 20 is a sectional view showing a conventional one-way clutch assembly  100 . The one-way clutch assembly  100  is typically employed by the automotive torque converter or the like as means for transmitting motive force only in one direction. In the figure, a synthetic-resin outer retainer  101  is press-fitted in an outer ring  50 . Likewise, a synthetic-resin inner retainer  102  is press-fitted on an unillustrated inner ring. 
     FIG. 21 is a sectional view showing a state in which the one-way clutch  100  (only the outer retainer  101  is shown) is press-fitted in the outer ring  50 . In this process, an edge  101   a  of an outermost part of the outer retainer  101  abuts against the outer ring  50 , making it difficult to press-fit the outer retainer into the outer ring  50 . Hence, it is not easy to assemble the one-way clutch  100  in the outer ring  50 . 
     Aside from the above problem, the practical use of the one-way clutch assembly  100  involves the temperature elevation thereof, causing tensile stress in an inside circumferential surface of the outer retainer  101 . In a few cases, this may result in the occurrence of cracks in the outer retainer  101 . 
     IN THE SPECIFICATION 
     In view of the foregoing, it is an object of the present invention to provide a one-way clutch easy to assemble in the outer ring. The present invention has another object to provide the one-way clutch adapted to prevent the occurrence of cracks in the outer retainer. 
     A one-way clutch according to the invention comprises: 
     sprags circumferentially arranged at predetermined space intervals, 
     an outer retainer and an inner retainer for respectively retaining an outer side and inner side of the sprags, and 
     A spring for biasing the sprags in one circumferential direction, wherein 
     (1) said outer retainer has a general annular form with a predetermined axial width and includes outwardly projected projections and pockets with said sprags inserted therethrough, said projections and pockets being alternately arranged in the circumferential direction, wherein an outermost part at each of said projections has its axially opposite side edges chamfered; 
     (2) said outer retainer and said projections are integrally made of resin material; and 
     (3) a contact width of said outermost part with an outer ring in an axial direction is greater than an open width of said pocket in an axial direction of said outer retainer. 
     According to the one-way clutch featured by the above item (1), the chamfered portions of the outer retainer abut against an inside edge of the outer ring when the outer retainer is press-fitted therein. Hence, the outer retainer is guided in a manner to bring its axis into accurate alignment with the axis of the outer ring. This provides for smooth press-fitting of the one-way clutch, facilitating the assembly thereof in the outer ring. 
     Further, the one-way clutch featured by the above items (2) and (3) ensures a sufficiently great axial contact width between the projection and the outer ring. Accordingly, the outer retainer does not suffer the great tensile stress in its inside circumferential surface even when the outer retainer is thermally expanded due to the evaluated temperature. As a result, the occurrence of cracks is prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diametrical sectional view showing a one-way clutch press-fitted in an outer ring in accordance with a first embodiment of the present invention; 
     FIG. 2 is a sectional view of the above one-way clutch showing a relation between the outer ring and an outer retainer being press-fitted therein; 
     FIG. 3 is a front view showing the above outer retainer; 
     FIG. 4 is a sectional view taken on the line IV—IV in FIG. 3; 
     FIG. 5 is an enlarged view of a portion V in FIG. 3; 
     FIG. 6 is a view seen along the arrow VI in FIG. 3; 
     FIG. 7 is a perspective view showing the above outer retainer; 
     FIG. 8 is a front view showing the one-way clutch employing the above outer retainer; 
     FIG. 9 is a sectional view of the above one-way clutch as seen in the same direction as in FIG. 8; 
     FIG. 10 is a sectional view showing a relation between the above outer retainer and the outer ring; 
     FIG. 11 is a diametrical sectional view showing a one-way clutch press-fitted in the outer ring in accordance with a second embodiment of the present invention; 
     FIG. 12 is a sectional view of the one-way clutch in accordance with the second embodiment for showing a relation between the outer ring and an outer retainer being press-fitted therein; 
     FIG. 13 is a front view showing the outer retainer of the one-way clutch in accordance with the second embodiment; 
     FIG. 14 is a sectional view taken on the line XIV—XIV in FIG. 13; 
     FIG. 15 is a view seen along the arrow XV in FIG. 13; 
     FIG. 16 is a perspective view showing the outer retainer of the one-way clutch in accordance with the second embodiment; 
     FIG. 17 is a diametrical sectional view showing a one-way clutch press-fitted in the outer ring in accordance with a third embodiment of the present invention; 
     FIG. 18 is a sectional view of the one-way clutch in accordance with the third embodiment for showing a relation between the outer ring and an outer retainer being press-fitted therein; 
     FIG. 19 is an equivalent view to FIG. 6 for showing the outer retainer in accordance with the third embodiment; 
     FIG. 20 is a diametrical sectional view showing a conventional one-way clutch press-fitted in the outer ring; and 
     FIG. 21 is a sectional view showing an outer retainer being press-fitted in the outer ring of the conventional one-way clutch assembly. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 to FIG. 9 illustrate a one-way clutch according to a first embodiment of the present invention. First, a mode of an outer retainer  1  will be described with reference to FIG. 3 to FIG.  7 . FIG. 3 is a front view of the outer retainer  1  (including a fragmentary sectional view), whereas FIG. 4 is a sectional view taken on the line IV—IV in FIG.  3 . FIG. 5 is an enlarged view showing a portion V in FIG. 3, whereas FIG. 6 is a view seen along the arrow VI in FIG.  3 . FIG. 7 is a perspective view of the outer retainer  1 . Referring to these figures, the outer retainer  1  is integrally formed of a synthetic resin material (such as, Nylon  66  reinforced with glass fibers) in one molding step. The outer retainer  1  has a general annular shape and a predetermined width W with respect to an axial direction CL (FIG.  4 ). More specifically, the outer retainer  1  includes, as shown in FIG. 7, annular portions  1   a  disposed at axially opposite ends, and a plurality of vault-like projections  1   b  formed between these annular portions  1   a  and projected radially outwardly in an arcuate fashion (as seen from an axial end). The projections  1   b  and pockets (openings)  1   c  are circumferentially arranged in an alternating manner. 
     The projection  1   b  includes a recess  1   d  centrally of one side thereof with respect to the circumferential direction. As seen in FIG.  4  and FIG. 6, the projection  1   b  is formed with tapered surfaces  1   e  at axially opposite ends thereof. Crests of the tapered surfaces  1   e  define axially opposite side edges  1   g  of an outermost part  1   f  at the projection  1   b  (FIG.  6 ). In other words, the presence of the tapered surfaces  1   e  gives the projection  1   b  such a shape that the outermost part  1   f  is chamfered at the axially opposite side edges  1   g . 
     FIG. 8 is a front view of a one-way clutch  10  employing this outer retainer  1 . FIG. 9 is a sectional view of the one-way clutch  10  as seen in the same direction as in FIG.  8 . In FIG.  8  and FIG. 9, the one-way clutch  10  includes sprags  2  circumferentially arranged at predetermined space intervals, the outer retainer  1  for retaining an outer side (radially) of the sprags  2 , an inner retainer  3  for retaining an inner side of the sprags  2 , a ribbon spring  4  for biasing the sprags  2  in one circumferential direction (clockwise in this example). The inner retainer  3  is an annular member formed of the same material as the outer retainer  1 . As shown in FIG. 9, the inner retainer  3  includes pockets  3   a  of the same number as the pockets  1   c  of the outer retainer  1 . These pockets  3   a  are circumferentially arranged at predetermined space intervals. The sprags  2  are mounted in the pockets  1   c  and  3   a  of the outer and inner retainers  1  and  3 . The sprags  2  are also capable of coming in and out of the recesses  1   d  of the projections  1   b.    
     Assumed that the one-way clutch  10  of the above arrangement is mounted between an unillustrated outer ring and inner ring, the sprags  2 , in the state shown in FIG. 9, are in contact with a track face Tr 1  of the outer race and a track face Tr 2  of the inner race. When the inner-race track face Tr 2  rotates counterclockwise relative to the outer-race track face Tr 1 , the sprags  2  are turned clockwise, tending to erect. Thus, the sprags  2  rigidly lock the outer-race track face Tr 1  and the inner-race track face Tr 2  to each other, allowing unitary rotation of the inner and outer races. When, on the other hand, the inner-race track face Tr 2  rotates clockwise relative to the outer-race track face Tr 1 , the sprags  2  are turned counterclockwise against the ribbon spring  4 . As a result, the sprags  2  no more act as struts between the inner and outer races, so that the rotation of either one of the inner and outer races is not transmitted to the other race. 
     FIG. 1 is a diametrical sectional view of the one-way clutch  10  press-fitted in the outer ring  50 , whereas FIG. 2 is a sectional view showing a relation between the outer ring  50  and the outer retainer  1  being press-fitted therein. As seen in FIG. 2, the outer retainer  1  has the tapered surface  1   e . The tapered surface  1   e  abuts against an inside edge of the outer ring  50  when the one-way clutch  10  is inserted into the outer ring  50 . Thus, the outer retainer  1  is guided by the outer ring  50  in a manner to bring its axis into accurate alignment with the axis of the outer ring  50 . Accordingly, the one-way clutch  10  is smoothly inserted into the outer ring  50 . 
     Hence, the one-way clutch  10  is readily assembled in the outer ring  50 . 
     When elevated in temperature in the practical use, the one-way clutch may suffer the occurrence of cracks in a few cases. In the thermally expanded outer retainer  1 , as shown in FIG. 10, tensile stress is produced in its inside circumferential surface  1   h  because its opposite ends tend to deform in directions of the arrows in the figure. This may result in a crack X. It is thought that such a phenomenon results from that a contact width W 1  between the outer retainer  1  and the outer ring  50  is considerably smaller than an overall width of the outer retainer  1 . Second and third embodiments of the present invention hereinbelow contemplate the prevention of the occurrence of such cracks. 
     FIG. 11 to FIG. 16 illustrate a one-way clutch  20  according to the second embodiment, which differs from the first embodiment in the mode of an outer retainer  11 . FIG. 13 is a front view of the outer retainer  11  (including a fragmentary sectional view), whereas FIG. 14 is a sectional view taken on the line XIV—XIV in FIG.  13 . FIG. 15 is a view seen along the arrow XV in FIG. 13, whereas FIG. 16 is a perspective view of the outer retainer  11 . Likewise to the first embodiment, the outer retainer  11  is integrally formed of the synthetic resin material in one molding step, having a general annular shape. Further, the outer retainer  11  has a predetermined width W with respect to the axial direction (FIG.  14 ). In FIG.  15  and FIG. 16, an annular portion  11   a , projection  11   b , pocket  11   c , recess  11   d , tapered surface  11   e , outermost part  11   f  and axial side edge  11   g  correspond to the like portions  1   a  to  1   g  of the first embodiment, respectively. The difference from the outer retainer  1  of the first embodiment is that the tapered surfaces  11   e  are integrally formed over the annular portions  11   a . The axially opposite side edges  11   g , defining the respective crests of the tapered surfaces  11   e , are relatively located laterally outward of an open width Wp of the pocket  11   c , as shown in FIG.  15 . 
     FIG. 11 is a diametrical sectional view of the one-way clutch  20  press-fitted in the outer ring  50 , whereas FIG. 12 is a sectional view showing a relation between the outer ring  50  and the outer retainer  11  being press-fitted therein. When the one-way clutch  20  employing the outer retainer  11  is inserted into the outer ring  50 , the tapered surface  11   e  abuts against the inside edge of the outer ring  50 . Thus, the outer retainer  11  is guided by the outer ring  50  in a manner to bring its axis into accurate alignment with the axis of the outer ring  50 . Accordingly, the one-way clutch  20  is smoothly press-fitted in the outer ring  50 . Likewise to the first embodiment, the one-way clutch  20  is readily assembled in the outer ring  50 . 
     As shown in FIG. 11, a contact width W 2  between the outer retainer  11  and the outer ring  50  is greater than the contact width W 1 (FIG. 10) of the first embodiment. Therefore, the outer retainer  11  is less susceptible to deformation due to thermal expansion, so that the great tensile stress does not occur in its inside circumferential surface. This positively prevents the crack occurrence. 
     FIG. 17 to FIG. 19 illustrate a one-way clutch  30  according to a third embodiment. FIG. 17 is a diametrical sectional view of the one-way clutch  30  press-fitted in the outer ring  50 , whereas FIG. 18 is a sectional view showing a relation between the outer ring  50  and an outer retainer  21  being press-fitted therein. FIG. 19 corresponds to FIG. 6 showing the first embodiment. Although not contained herein, a front view of the outer retainer  21  is the same as FIG.  3 . This embodiment differs from the first and second embodiments in the mode of the outer retainer  21 . 
     Likewise to the first embodiment, the outer retainer  21  of this embodiment is integrally formed of the synthetic resin material in one molding step. The outer retainer  21  has a general annular shape and a predetermined axial width W (FIG.  18 ). An annular portion  21   a , pocket  21   c  and recess  21   d  shown in FIG. 19 correspond to the like portions  1   a ,  1   c  and  1   d  of the first embodiment, respectively. 
     As shown in FIG. 18, the outer retainer  21  of the third embodiment is formed with a pair of projections  21   b  on its axially opposite ends, the projections having an outwardly projected arcuate form in diametrical section. A crest of the projection  21   b  also defines an arcuate edge in the circumferential direction. Therefore in FIG. 19, the outermost part is defined by the crest  21   g  of the projection  21   b , the crest  21   g  being an intersection of the axial line (lateral direction as seen in the figure) and the circumferential line (perpendicular direction as seen in the figure) of the projection. Further, an axially outside portion of the crest  21   g  defines a slope  21   e  as the equivalent of the tapered surfaces  1   e  and  11   e  of the first and second embodiments. That is, the slope  21   e  is a chamfered face for the crest  21   g  of the projection  21   b.    
     The pair of crests  21   g  support the outer retainer  11  through point contact with the outer ring  50 . Therefore, an actual contact width between the outer retainer  11  and outer ring  50  with respect to the axial direction is equal to a contact width W 3  corresponding to a distance between the crests  21   g , as shown in FIG.  17 . It is noted that the crests  21   g  are at axial positions relatively outward of the open width Wp of the pocket  21   c  as seen in FIG.  19 . This ensures that the contact width W 3  between the projection pair  21   b  and the outer ring  50 , shown in FIG. 17, has as great value as the contact width W 2  (FIG. 11) of the second embodiment. 
     When the one-way clutch  30  employing this outer retainer  21  is inserted into the outer ring  50 , the projection  21   b  thereof abuts against the inside edge of the outer ring  50 , as shown in FIG.  18 . Thus, the outer retainer  21  is guided by the outer ring  50  in a manner to bring its axis into accurate alignment with the axis of the outer ring  50 . Accordingly, the one-way clutch  30  is smoothly inserted into the outer ring  50 . Likewise to the first embodiment, the one-way clutch  30  is readily assembled in the outer ring  50 . 
     As mentioned supra, the contact width W 3  between the outer retainer  21  and the outer ring  50  is greater than the contact width W 1  of the first embodiment. Thus, the outer retainer  21  is less susceptible to the deformation due to thermal expansion, so that no great tensile stress occurs in its inside circumferential surface. Therefore, the crack occurrence is positively prevented. In addition, the outer retainer is readily press-fitted in the outer ring by virtue of the point contact between the projections  21   b  and the outer ring  50 .