Patent Publication Number: US-2021178894-A1

Title: Propeller shaft

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application based on PCT/JP2018/045605, filed on Dec. 12, 2018, claiming priority based on Japanese Patent Application No. 2018-227612, filed in Japan on Dec. 4, 2018, the contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a propeller shaft. 
     RELATED ART 
     A propeller shaft is a power transmission shaft extending in a longitudinal direction (front-rear direction) of a vehicle. The propeller shaft is configured to transmit power that is generated by a prime mover and reduced to a predetermined speed at a transmission to a final reduction gear unit. The propeller shaft has a universal joint provided on each end thereof through which the transmission and the final reduction gear unit are connected to the propeller shaft. In general, a cardan joint is used in the universal joint. However, a constant-velocity joint may be used to suppress vibration generated in a power transmission system. 
     The constant-velocity joint includes an outer race, an inner race disposed in the outer race, a power transmission member (e.g., a plurality of balls) arranged between the outer race and the inner race to transmit power (torque), and a shaft member having one end spline-fitted in the inner race and the other end joined to a pipe. 
     To prevent a leakage of lubricating grease filled in the outer race and also to prevent dust from entering the outer race, an opening of the outer race is sealed by a boot. As disclosed in JP 2006-300254 A, the boot generally includes a boot adapter (cylindrical member) made of metal and fitted onto the outer race, and a bellows portion (seal member) made of rubber and having one end fixed to the boot adapter and the other end fixed to a shaft member. 
     The bellows portion has a recess portion recessed frontward or rearward in the front-rear direction. If the recess portion is directed frontward, small stones or chunks of melt snow flipped up by the front wheels may enter the recess portion and the bellows portion may be damaged. For this reason, JP S61-059923 U1 proposes to provide a disc-shaped protection member in front of the bellows portion. 
     SUMMARY OF THE INVENTION 
     To connect the outer race and the input shaft of the final reduction gear unit, the outer race has a plurality of bolt holes arranged in the circumferential direction and each extending through the outer race in the axial direction. When a bolt inserted into a bolt hole is tightened with a bolt fastening tool, the bolt fastening tool may interfere with the protection member. 
     If the protection member is disposed spaced apart from the outer race to prevent the interference between the bolt fastening tool and the protection member, small stones and the like may easily enter the recess portion of the bellows portion. However, if the size of the protection member is increased to prevent stones from entering the bellows portion, the layout of the vehicle is adversely affected. 
     The present invention has been created to address this problem and it is an object of the present invention to provide a propeller shaft equipped with a protection member and capable of ensuring the workability for mounting the propeller shaft to the vehicle. 
     To solve the above problem, a propeller shaft according to the first aspect of the present invention comprises: an outer race having a plurality of bolt holes formed therethrough in an axial direction; a power transmission member swingable in the outer race; a shaft member having a front end portion in which a large-diameter portion is formed and a rear end portion connected to the power transmission member; a seal member made of rubber and configured to seal a front opening of the outer race; and a disc-shaped protection member mounted between the large-diameter portion and the rear end portion of the shaft member, wherein the protection member has a clearance portion for a bolt fastening tool, and wherein the clearance portion is annually formed around a shaft center. 
     Further, to solve the above problem, a propeller shaft according to the second aspect of the present invention comprises: an outer race having a plurality of bolt holes formed therethrough in an axial direction; a power transmission member swingable in the outer race; a shaft member having a front end portion in which a large-diameter portion is formed and a rear end portion connected to the power transmission member; a seal member made of rubber and configured to seal a front opening of the outer race; and a disc-shaped protection member mounted between the large-diameter portion and the rear end portion of the shaft member, wherein the protection member has clearance portions for a bolt fastening tool, each of the clearance portions being in phase with a corresponding bolt hole when viewing in the axial direction. 
     According to first and second aspects of the present invention as described above, it is possible to dispose a bolt fastening tool in the clearance portion of the protection member while tightening of a bolt, so that the tool does not interfere with the protection member. This can ensure the workability for mounting the propeller shaft to the vehicle. 
     In the second aspect, it is preferable that the protection member has a closure portion extending frontward from an edge portion of the clearance portion and configured to close a front side of the clearance portion. According to this configuration, flying stones and the like coming from the front side toward the clearance portion hit the closure portion and thus do not enter the recess portion of the seal member. 
     Further, in the second aspect, the protection member may be cut out at an edge portion of the clearance portion. According to this configuration, the protection member is simple in shape, which results in reduced manufacturing cost. 
     Further, in the first and second aspects, the protection member may be fitted to the shaft member. As an alternative, the protection member may be inserted onto the shaft member and retained by a ring member attached to the shaft member to prevent the protection member from coming off the shaft member. As a further alternative, the protection member may be inserted onto the shaft member and tightened by a tightening band. 
     Further, it is preferable that the tightening band simultaneously tightens an end portion of the seal member. According to this configuration, the number of parts required for the tightening band for tightening the seal member can be reduced. 
     Further, the propeller shaft according to the first and second aspects further comprises a cylindrical member having a rear end portion fixed to the outer race and a front end portion configured to support the seal member. The bolt holes may be formed in a main body portion of the outer race, and at least a portion of the clearance portion may be located radially inward of an outer peripheral surface of the cylindrical member. Further, the bolt holes may be formed in a flange of the outer race, and at least a portion of the clearance portion may be located radially inward of an outer peripheral surface of a main body portion of the outer race. 
     According to the present invention, it is possible to provide a propeller shaft equipped with a protection member and capable of ensuring the workability for mounting the propeller shaft to the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a propeller shaft according to a first embodiment when viewing from above. 
         FIG. 2  is an enlarged view of a rear universal joint according to the first embodiment. 
         FIG. 3  is a sectional view taken along the line of  FIG. 2 . 
         FIG. 4  is an enlarged view of a rear universal joint according to a second embodiment. 
         FIG. 5  is a sectional view taken along the line V-V of  FIG. 4 . 
         FIG. 6  is a perspective view of a protection member according to a third embodiment. 
         FIG. 7  is an enlarged view of a rear universal joint according to a fourth embodiment. 
         FIG. 8  is an enlarged view of a rear universal joint according to a fifth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the drawings, propeller shafts  1 ,  101 ,  201 ,  303 ,  401  according to first to fifth embodiments of the present invention will be described. In the description of each of the embodiments, the same or similar technical components are denoted by the same reference numerals and explanations thereof will be omitted. 
     &lt;First Embodiment&gt; 
     A propeller shaft  1  is mounted, for example, on an FF-based (Front-engine/Front-drive based) four-wheel drive vehicle. The propeller shaft  1  is disposed under a floor panel (not shown). The propeller shaft  1  extends in a longitudinal direction (front-rear direction) of the vehicle and is configured to transmit power outputted from a transmission (not shown) disposed in a front part of a vehicle body to a final reduction gear unit (not shown) disposed in a rear part of the vehicle body. 
     As seen in  FIG. 1 , the propeller shaft  1  includes a first pipe  2  and a second pipe  3  which are cylindrical steel pipes separately disposed in a front side and a rear side, an intermediate universal joint  4  connecting the first pipe  2  and the second pipe  3 , a front universal joint  6  disposed frontward of the first pipe  2 , a rear universal joint  7  disposed rearward of the second pipe  3 , and a protection member  8  disposed rearward of the second pipe  3 . 
     In the propeller shaft  1 , a stub shaft  4   c  (described later) of the intermediate universal joint  4  is rotatably supported by a bearing structure  5  attached to the floor panel (not shown). 
     The intermediate universal joint  4  uses a tripod type constant-velocity joint. The tripod type constant-velocity joint includes a cylindrical outer race  4   a  joined to a front end of the second pipe  3 , a power transmission member  4   b  swingable in the outer race  4   a,  a stub shaft  4   c  which is a solid shaft member connected to the power transmission member  4   b.    
     It should be noted that the intermediate universal joint  4  according to the present invention is not limited to a constant-velocity joint, and a cardan joint may be used. Further, if the constant-velocity joint is used in the present invention, it is not limited to a tripod type constant-velocity joint, and other non-limited joints such as a Birfield type joint and a double offset type joint may be used. 
     The same constant-velocity joint is used in the front universal joint  6  and in the rear universal joint  7 . Therefore, the rear universal joint  7  is described as a representative example, and the description of the front universal joint  6  will be omitted. 
     As seen in  FIG. 2 , a Birfield type constant-velocity joint is used as the rear universal joint  7 . The Birfield type constant-velocity joint includes an outer race  10 , an inner race  20 , a plurality of balls (not shown), a stub shaft  30  as a shaft member, a bellows portion  40 , and a s boot adapter  50 . 
     The outer race  10  is a forged component including a cylindrical main body portion  11  that opens to front and rear sides, and a ring-shaped flange  12  extending radially outward from the outer peripheral surface  11   a  of the main body portion  11 . 
     The inner peripheral surface of the main body portion  11  is formed in a spherical shape. Provided in the inner peripheral surface of the main body portion  11  are a plurality of outer grooves (not shown) each extending in the front-rear direction and having an arc-shaped cross-section in the circumferential direction. 
     The flange  12  is a portion to be connected to a companion flange  60  (see broken line of  FIG. 2 ) connected to an input shaft of the final reduction gear unit (not shown), and is located at the rear end of the outer peripheral surface  1  la of the main body portion  11 . The flange  12  has six bolt holes  13  extending therethrough in the direction of the axis of rotation O 1  and formed at equal intervals in the circumferential direction (only one bolt hole is shown in  FIG. 2 ). 
     The inner race  20  has a cylindrical shape, and a hole spline  21  is formed in the inner peripheral surface of the inner race  20 . The outer peripheral surface of the inner race  20  is formed to have a spherical shape. Provided in the outer peripheral surface of the inner race  20  are a plurality of inner grooves (not shown) each extending in the front-rear direction and having an arc-shaped cross-section in the circumferential direction. Further, a cage  23  is fitted on the outer peripheral surface of the inner race  20 . Window portions (not shown) as openings are formed in the cage  23 . 
     The balls are spherical members made of metal. The balls are partly exposed from the window portions of the cage  23  while being contained in the inner grooves of the inner race  20 . The partly exposed portions of the balls enter the outer grooves of the outer race  10 . 
     The cage  23  functions to retain the balls rolling between the inner grooves  22  of the inner race  20  and the outer grooves  1  lb of the outer race  10  such that they are arranged on the bisector of an angle made between the outer race  10  serving as an input shaft and the inner race  20  serving as an output shaft. With this function of the cage  23  the power is transmitted without causing rotational fluctuations of the input shaft and the output shaft. 
     The stub shaft  30  is a shaft member extending in the direction of the axis of rotation O 1 . The stub shaft  30  includes a large diameter portion  31  located at the front portion, a small diameter portion  32  located at the rear portion, and an intermediate portion  33  interposed between the large diameter portion  31  and the small diameter portion  32 . 
     The large diameter portion  31  has a circular configuration. The diameter of the large diameter portion  31  is the same as the diameter of the second pipe  3  and larger than the diameters of the small diameter portion  32  and the intermediate portion  33 . The front end of the large diameter portion  31  is joined to the second pipe  3  by welding. 
     A shaft spline  32   a  is formed on the outer peripheral surface of the small diameter portion  32 , so that the shaft spline  32   a  and the hole spline  21  of the inner race  20  are spline-fitted with each other. 
     A front end  41  of the bellows portion  40  is tightened by a band  43  and attached to the rear portion of the intermediate portion  33 . 
     A fitted portion  34 , onto which an attachment portion  81  (to be described later) of the protection member  8  is fitted, is formed on the front portion of the intermediate portion  33 . Further, a stepped surface  35  extending radially outward is formed on the front side of the fitted portion of the intermediate portion  33  so as to prevent the protection member  8  from moving forward. 
     The bellows portion  40  is a rubber component configured to close the front opening of the outer race  10 . The bellows portion  40  has a generally J-shaped cross-section with a recess portion  44  recessed or opened frontward. 
     The boot adapter  50  is a cylindrical component made of metal. The boot adapter  50  has a rear end  51  to be fitted onto and caulked with the outer peripheral surface  11   a  of the outer race  10 . A front end  52  of the boot adapter  50  is folded inward to hold the rear end  42  of the bellows portion  40 . 
     The protection member  8  is a thin plate-like component formed by processing a sheet metal. 
     The protection member  8  includes a cylindrical attachment portion  81  to be fitted onto the fitted portion  34 , a body portion  82  extending radially outward from the front end of the attachment portion  81 , and a closure portion  83  formed on the outer peripheral side of the body portion  82 . 
     As seen in  FIG. 3 , the body portion  82  has a circular plate shape whose center is the axis of rotation O 1 . The outer diameter of the body portion  82  is r 1 , which is smaller than the outer diameter r 2  of the outer race  10 . 
     With this configuration the outer peripheral edge  82   a  of the body portion  82  is located radially inward of the outer peripheral surface  11   a  of the outer race  10 , and an annular clearance portion (space)  84  is formed on the outer peripheral side of the outer peripheral edge  82   a  of the body portion  82 . 
     The closure portion  83  is a portion for closing the front side of the clearance portion  84 . 
     The closure portion  83  includes a longitudinal cylinder  83   a  extending frontward from the outer end of the body portion  82 , and a circular plate portion  83   b  extending radially outward from the front end of the longitudinal cylinder  83   a.    
     The longitudinal cylinder  83   a  has a length in the front-rear direction such that the circular plate portion  83   b  does not interfere with a bolt fastening tool  91  to be described below. 
     The operation for mounting the propeller shaft  1  will be described below. 
     After abutting the flange  12  of the outer race  10  and the flange  61  of the companion flange  60 , a bolt (not shown) is inserted from the front side of the bolt hole  13  and screwed into a nut (not shown). Rotating the bolt causes the flange  12  and the flange  61  to be fastened together. 
     When the bolts are inserted into the bolt holes  13  and tightened, the tightening torque of the bolts and nuts is set to a predetermined value. 
     If the bolt fastening tool  91  is to be engaged directly with the bolt head, an engagement portion  92  of the bolt fastening tool  91  interferes with the outer peripheral surface  11   a  of the outer race  10 , so that the engagement portion  92  cannot be engaged with the bolt head. Therefore, a rear end of an extension  90  is fitted to the bolt head and the bolt fastening tool  91  is engaged with the front end of the extension  90 . According to this, a part of the engagement portion  92  of the bolt fastening tool  91  is located in the clearance portion  84  of the protection member  8  (see  FIGS. 2 and 3 ). 
     Next, while a tool (not shown) is engaged with the nut and held to prevent the nut from rotating, the bolt fastening tool  91  is rotated around the center  02  of the bolt hole  13  and the tightening torque is set to a predetermined value. When the tightening torque of each bolt is set to a predetermined value, the mounting operation is completed. 
     As described above, according to the first embodiment, since the bolt fastening tool  91  does not interfere with the protection member  8  during the operation for tightening a bolt, it is possible to ease the bolt-tightening work. Further, since the protection member  8  includes the body portion  82  and the closure portion  83 , small stones and the like are less likely to enter the recess portion  44  of the bellows portion  40 . 
     &lt;Second Embodiment&gt; 
     A propeller shaft  101  according to the second embodiment will be described below. 
     As seen in  FIGS. 4 and 5 , a protection member  108  of the propeller shaft  101  includes a cylindrical attachment portion  181  to be fitted onto the fitted portion  34 , a body portion  182  extending radially outward from the front end of the attachment portion  181 , and six protruding tabs  183  extending further radially outward from the body portion  182 . 
     As seen in  FIG. 5 , the body portion  182  extends to the outer peripheral side of the intermediate portion  33  of the stub shaft  30  and is located radially inward of the outer peripheral surface  11   a  of the main body portion  11  of the outer race  10  (see auxiliary line L of  FIG. 5 ). 
     Meanwhile, the protruding tabs  183  protrude radially outward beyond the outer peripheral surface  11   a  of the outer race  10 . The protruding tabs  183  are spaced apart from each other and arranged on the outer peripheral side of the body portion  182 , so that a clearance portion (space)  184  is formed between two adjacent protruding tabs  183 . 
     Further, when viewing in the axial direction, the protruding tabs  183  are arranged so as not to overlap the bolt holes  13  of the outer race  10 , and the clearance portions  184  are arranged to overlap the bolt holes  13  of the outer race  10 . 
     As seen in  FIG. 4 , the outer peripheral end of each protruding tab  183  is bent rearward to form a bent portion  185 , so that the strength of the protruding tab  183  is improved. 
     As described above, according to the second embodiment, since a part of the engagement portion  92  of the bolt fastening tool  91  is located in the clearance portion  184  while tightening the bolts B using the extension  90 , the bolt fastening tool  91  does not interfere with the protection member  108 . 
     &lt;Third Embodiment&gt; 
     A propeller shaft  201  according to the third embodiment will be described below. 
     As seen in  FIG. 6 , a protection member  208  of the propeller shaft  201  includes a cylindrical attachment portion  181  to be fitted onto the fitted portion  34 , a body portion  182  extending radially outward from the front end of the attachment portion  181 , six protruding tabs  183  extending further radially outward from the body portion  182 , and closure portions  285  for closing the front side of each of the clearance portions  184 . Therefore, the protection member  208  is different from the protection member  108  according to the second embodiment in that the closure portions  285  are provided on the protection member  208 . 
     The closure portion  285  includes a generally U-shaped extension portion  285   a  extending frontward from the edge portion  184   a  of the clearance portion  184 , and a plate portion  285   b  continuous from the front end of the clearance portion  284  and extending in upward, downward, right and left directions. 
     As described above, according to the third embodiment, it is possible to ease the bolt-tightening work as with the first embodiment and the second embodiment. Further, since the closure portions  285  close the front side of the clearance portions  184 , small stones and the like are less likely to enter the recess portion  44  of the bellows portion  40  as compared with the protection member  108  according to the second embodiment. 
     &lt;Fourth Embodiment&gt; 
     A propeller shaft  301  according to the fourth embodiment will be described below. 
     As seen in  FIG. 7 , a protection member  308  of the propeller shaft  301  includes the attachment portion  81  to be fitted onto the fitted portion  34 , the body portion  82  extending radially outward from the front end of the attachment portion  81 , the closure portion  83  formed on the outer peripheral side of the body portion  82  and configured to close the front side of the clearance portion  384 , and an extension portion  385  extending rearward from the rear end of the attachment portion  81 . Therefore, the protection member  308  is different from the protection member  108  according to the second embodiment in that the extension portion  385  is provided on the protection member  308 . 
     The extension portion  385  extends along the stub shaft  30  and has a cylindrical shape. A rear end portion  385   a  of the extension portion  385  covers the outer peripheral side of the front end  41  of the bellows portion  40 . The rear end portion  385   a  of the extension portion  385  and the front end  41  of the bellows portion  40  are tightened by the band  43 . 
     As described above, according to the fourth embodiment, it is possible to ease the bolt-tightening work as with the above-described embodiments. Further, the fixing strength for the protection member  308  is improved. Further, the number of parts is decreased as compared with an alternative embodiment in which the protection member  308  and the bellows portion  40  are tightened independently using different bands  43 . This can lead to cost reduction. 
     &lt;Fifth Embodiment&gt; 
     A propeller shaft  401  according to the fifth embodiment will be described below. 
     As seen in  FIG. 8 , the propeller shaft  401  includes the first pipe  2  and the second pipe  3 , the intermediate universal joint  4 , the front universal joint  6 , a rear universal joint  407 , and a protection member  408 . 
     The rear universal joint  407  is a cross groove type constant-velocity joint. The rear universal joint  407  includes an outer race  410 , an inner race  420 , a plurality of balls (not shown), a stub shaft  430 , a bellows portion  440 , and a boot adapter  450 . It should be noted that the stub shaft  430  and the bellows portion  440  have the same configurations as those of the stub shaft  30  and the bellows portion  40  described in the first embodiment and detailed descriptions thereof will be omitted. 
     The outer race  410  consists of a cylindrical main body portion  411  that opens to front and rear sides. The main body portion  411  has a plurality of bolt holes  413  formed to extend through the front end face and the rear end face of the main body portion  411  and arranged in the circumferential direction. 
     The inner race  420  has a hole spline  421  formed in the inner peripheral surface thereof. The small diameter portion  432  of the stub shaft  430  and the hole spline  421  are spline-fitted with each other. A cage  423  is fitted on the outer peripheral surface of the inner race  420 . 
     The balls are partly exposed from window portions (not shown) of the cage  423  while being contained in inner grooves (not shown) of the inner race  420 . The partly exposed portions of the balls enter outer grooves (not shown) of the outer race  410 . 
     The cage  423  functions to retain the balls rolling between the inner grooves of the inner race  420  and the outer grooves (not shown) of the outer race  410  such that they are arranged on the bisector of an angle made between the outer race  410  serving as an input shaft and the inner race  420  serving as an output shaft. With this function of the cage  423  the power is transmitted without causing rotational fluctuations of the input shaft and the output shaft. 
     The boot adapter  450  includes an externally-fitting portion  451  to be fitted onto the outer peripheral surface of the main body portion  411  of the outer race  410 , a folded portion  452  formed by folding back the front end edge of the externally-fitting portion  451  in the radially inward direction, a cylinder portion  453  extending frontward from the inner edge of the folded portion  452 , and a holding portion  454  formed by folding back the front end of the cylinder portion  453  in the radially inward direction to hold the rear end  442  of the bellows portion  440 . 
     The protection member  408  includes a cylindrical attachment portion  481  to be fitted s onto the stub shaft  430 , a body portion  482  extending radially outward from the front end of the attachment portion  481 , and a closure portion  483  formed on the outer peripheral side of the body portion  482 . An annular clearance portion (space)  484  is formed on the outer peripheral side of the outer peripheral edge  482   a  of the body portion  482 . 
     The body portion  482  has a circular outer shape whose center is the axis of rotation O 1 . The outer diameter of the body portion  482  is set to be smaller than the outer diameter of the cylinder portion  453  of the boot adapter  450  (see auxiliary line M of  FIG. 8 ). Therefore, when viewing in the direction of the axis of rotation O 1 , the body portion  482  is located radially inward of the outer peripheral surface  453   a  of the cylinder portion  453 . 
     A bolt B inserted into the bolt hole  413  and tightening the main body portion  411  has a bolt head with a hexagonal hole B 1 . This is because the gap between the outer peripheral surface of the bolt head and the cylinder portion  453  is small. A washer W is disposed between the main body portion  411  and the bolt head of the bolt B. 
     As described above, according to the fifth embodiment, when a hexagonal shaft  90   a  formed on the front end portion of the extension  90  is inserted into the hexagonal hole B 1  of the bolt B and the engagement portion  92  of the bolt fastening tool  91  is engaged with the front end of the extension  90 , a part of the engagement portion  92  is located in the clearance portion  484  without interfering with the protection member  408 . Therefore, it is possible to ease the tightening work for the bolts B. 
     Although various embodiments of the present invention have been described above, the present invention is not limited to the specific configurations described in these embodiments. For example, the protection member  8  is not limited to one made of a steel plate material and may be formed of hard rubber and the like. 
     Further, a ring may be fitted onto the intermediate portion of the stub shaft  30  so as to abut on the rear end face of the body portion of the protection member. This can prevent the protection member from moving rearward and thus improve the fixing strength for the protection member. 
     Further, a Birfield type constant-velocity joint and a cross groove type constant-velocity joint have been used as the front universal joint and the rear universal joint. However, a tripod type constant-velocity joint or a double offset type constant-velocity joint may be used. As described in the first embodiment, if a tripod type constant-velocity joint or a double offset type constant-velocity joint is used, it is necessary that at least a portion of the clearance portion be located radially inward of the outer peripheral surface of the main body portion of the outer race.