Abstract:
A ratchet type one-way clutch in which an outer ring is made of aluminum is improved in durability. In order to solve such problems as an increase in the number of parts, complication, bulkiness, an increase in weight and an increase in cost, there is provided a one-way clutch with the lock-up function also having the function of idly rotating only in one direction and the function of blocking the rotation in both directions. In a ratchet type one-way clutch having an outer ring having a pocket in the inner periphery thereof, an inner ring disposed coaxially with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the pocket and fitted in the notch of the inner ring for transmitting torque between the inner ring and the outer ring, and a resilient member for biasing the pawl toward the inner ring, the outer ring is made of aluminum, and the inner peripheral side surface of the outer ring is subjected to a hardening process.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a divisional of application Ser. No. 09/768,248 filed Jan. 25, 2001 now U.S. Pat. No. 6,557,681. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to improvements in a one-way clutch used in the transmission of an automobile, an agricultural machine, a construction machine, an industrial machine or the like, and particularly the automatic transmission of a vehicle or the like, and performing the function of a backstop. More particularly, it relates to a ratchet type one-way clutch using a ratchet (pawl) in a lock mechanism and a method of manufacturing the same. 
   2. Related Background Art 
   Generally, a one-way clutch used in an automatic transmission has an outer ring and an inner ring rotated relative to each other, and a sprag or a roller for transmitting torque between the outer ring and the inner ring meshes with a cam surface provided on the raceway surface of the outer ring or the inner ring to thereby transmit rotational torque only in one direction. Also, design is made such that the outer ring and the inner ring are idly rotated in the opposite direction. 
   Such one-way clutches include a ratchet type one-way clutch using a ratchet as a torque transmitting member for transmitting torque between the outer ring and the inner ring. Generally, the ratchet type one-way clutch is comprised of an outer ring having a pocket in the inner periphery thereof, an inner ring disposed coaxially with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the aforementioned pocket, fitted in the notch of the inner ring and bringing the one-way clutch into its locked state to thereby transmit torque between the inner ring and the outer ring, and a resilient member for biasing the pawl toward the inner ring. 
     FIG. 14  of the accompanying drawings is an axial fragmentary cross-sectional view of the side plate  190  and outer ring  130  of a ratchet type one-way clutch according to the prior art. A pocket  131  for containing a pawl therein is formed in the inner periphery of the outer ring  130 . Also, in a state wherein an inner ring and the outer ring are combined together, the side plate  190  abuts against an axial side of the outer ring  130  to thereby regulate the axial movement of the pawl. 
   Further, it is conceivable to provide, as means for preventing the circumferential relative movement of the outer ring  130  and the side plate  190 , a mountain portion  195  on the outer peripheral portion of the side plate  190  and a valley portion  138  in the outer peripheral surface of the outer ring  130 , and fit the mountain portion  195  into the valley portion  138 . 
   According to the above-described construction, it is necessary to provide the mountain portion  195  and valley portion  138  only for fitting the side plate  190  to the outer ring  130  in the side plate  190  and outer ring  130  constituting the ratchet type one-way clutch, and this leads to the problem that such clutch is of a shape difficult to work and the cost for the working becomes high. 
   In the ratchet type one-way clutch of the above-described construction, when the one-way clutch rotates in one direction, the pawl slides freely relative to the outer periphery of the inner ring and therefore, the outer ring and the inner ring idly rotate relative to each other. Next, when the one-way clutch is about to rotate in the other direction, the pawl fits in the notch and the one-way clutch assumes a locked-up state. 
   Usually, the outer ring of the ratchet type one-way clutch is made of aluminum, but it was not always satisfactory in respect of durability due to, for example, pivotal movement or the like repeated by the pawl in the pocket provided in the outer ring. 
   Also, the pawl of the ratchet type one-way clutch has a recess having a shape substantially complementary thereto, and fits in a notch formed in the outer periphery of the inner ring. However, satisfaction was not always obtained in respect to durability due to the meshing performance of the ratchet and for example, pivotal movement repeated by the pawl in the pocket provided in the outer ring. 
   SUMMARY OF THE INVENTION 
   So, it is an object of the present invention to improve durability in a ratchet type one-way clutch of which the outer ring is made of aluminum. 
   It is another object of the present invention to improve the meshing performance of a ratchet type one-way clutch to thereby improve the durability of the ratchet type one-way clutch. 
   It is still another object of the present invention to provide a ratchet type one-way clutch of which the construction of the side plate and outer ring can be simplified and in which the working step therefor can be simplified. 
   In order to achieve the above objects, the ratchet type one-way clutch of the present invention is a ratchet type one-way clutch comprised of an outer ring having a pocket in the inner periphery thereof, an inner ring disposed coaxially with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the pocket and fitted in the notch of the inner ring and transmitting torque between the inner ring and the outer ring, and a resilient member for biasing the pawl toward the inner ring, characterized in that the outer ring is made of aluminum and the inner peripheral surface of the outer ring is subjected to a hardening process. 
   Also, in order to achieve the above objects, the ratchet type one-way clutch of the present invention is a ratchet type one-way clutch comprised of an outer ring having a pocket in the inner periphery thereof, an inner ring disposed coaxially with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the pocket and fitted in the notch of the inner ring and transmitting torque between the inner ring and the outer ring, and a resilient member ( 50 ) for biasing the pawl toward the inner ring, characterized in that the pressure receiving surface of the notch has a predetermined angle of inclination with respect to a line linking the point of intersection between surfaces constituting the notch and the center of the inner ring together. 
   In order to achieve the above objects, the ratchet type one-way clutch of the present invention comprises an outer ring having a pocket in the inner periphery thereof, an inner ring disposed substantially concentrically with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the pocket for transmitting torque between the inner ring and the outer ring, a resilient member for biasing the pawl toward the inner ring, and a side plate for limiting the axial movement of the pawl, and is characterized in that the side plate is provided with a convex portion fitted into the pocket. 
   Also, in order to achieve the above objects, the method of manufacturing a ratchet type one-way clutch of the present invention is a method of manufacturing a ratchet type one-way clutch having an outer ring having a pocket in the inner periphery thereof, an inner ring disposed coaxially with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the pocket and fitted in the notch of the inner ring for transmitting torque between the inner ring and the outer ring, and a resilient member for biasing the pawl toward the inner ring, characterized by the steps of: 
   molding the outer ring from aluminum by diecasting; and 
   subjecting the surface of the inner peripheral side of the outer ring to a hardening process. 
   Also, the method of manufacturing a ratchet type one-way clutch of the present invention is a method of manufacturing a ratchet type one-way clutch having an outer ring having a pocket in the inner periphery thereof, an inner ring disposed coaxially with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the pocket and fitted in the notch of the inner ring for transmitting torque between the inner ring and the outer ring, and a resilient member for biasing the pawl toward the inner ring, characterized in that the arcuate portion of the pocket is molded by plastic working. 
   According to the ratchet type one-way clutch of the present invention, the surface of the inner peripheral side of the outer ring molded of aluminum is subjected to the hardening process and therefore the clutch is improved in durability. 
   Also, the method of manufacturing a ratchet type one-way clutch of the present invention has the steps of molding the outer ring from aluminum, and subjecting the surface of the inner peripheral side of the outer ring to the hardening process and can therefore manufacture a ratchet type one-way clutch improved in durability. 
   Also, the pressure receiving surface of the notch is designed to have a predetermined angle of inclination with respect to a line linking the point of intersection between surfaces constituting the notch and the center of the inner ring together and therefore, the pawl falls reliably during meshing engagement. 
   Also, by the construction as described above, there are obtained the action of restraining wear, and the action that it becomes difficult for fracture to occur because the pressure receiving surface does not become adjacent to a corner portion. 
   Further, by the construction as described above, the number of notches can be increased and there is obtained the action of decreasing backlash. 
   Also, by the construction as described above, as in the present invention, the pawl can be reliably dropped into the notch. 
   Herein, the “pressure receiving surface” refers to a surface having a torque load under its charge when the ratchet type one-way clutch meshes. 
   The present invention is a ratchet type one-way clutch comprising an outer ring having a pocket in the inner periphery thereof, an inner ring disposed substantially concentrically with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the pocket for transmitting torque between the inner ring and the outer ring, a resilient member for biasing the pawl toward the inner ring, and a side plate for limiting the axial movement of the pawl, the side plate being provided with a convex portion fitted in the pocket. 
   As the resilient member, utilization can be made of a coil spring, a garter spring, a wave spring or the like. Further, the side plate has a bearing function to the outer ring and the inner ring. Also, the convex portion may preferably be provided with a projection for supporting the axial side of the pawl. It is most desirable that this projection support the center of movement of the pawl. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view of a ratchet type one-way clutch to which each embodiment of the present invention is applied. 
       FIG. 2  is a cross-sectional view taken along the line  2 — 2  of FIG.  1 . 
       FIG. 3  is a fragmentary cross-sectional view showing the details of an outer ring in a first embodiment of the present invention. 
       FIG. 4  is a fragmentary cross-sectional view showing the details of the outer ring in the first embodiment of the present invention. 
       FIG. 5  is a cross-sectional view of the essential portions of a ratchet type one-way clutch according to a second embodiment of the present invention. 
       FIG. 6  is a fragmentary cross-sectional view showing the details of an outer ring in a third embodiment of the present invention. 
       FIG. 7  is a typical view showing the relation between a pawl and a notch in a fourth embodiment on an enlarged scale. 
       FIG. 8  is an enlarged front view of the pressure receiving surface of the pocket of an outer ring in a fifth embodiment of the present invention. 
       FIG. 9  is a cross-sectional view of the essential portions of a ratchet type one-way clutch according to a sixth embodiment of the present invention. 
       FIG. 10  shows a seventh embodiment of the present invention, and is an enlarged view of the essential portions of FIG.  9 . 
       FIG. 11  shows the seventh embodiment of the present invention, and is a front view showing the fitted state of a pawl and a notch. 
       FIG. 12  shows an eighth embodiment of the present invention, and is a fragmentary enlarged view of the ratchet type one-way clutch of FIG.  2 . 
       FIG. 13  is a circumferential cross-sectional view along the line  13 — 13  of FIG.  12 . 
       FIG. 14  is a circumferential fragmentary cross-sectional view of a ratchet type one-way clutch according to the prior art. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Some embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings. In the drawings, like portions are designated by like reference numerals. 
     FIG. 1  is a front view of a ratchet type one-way clutch to which each embodiment of the present invention is applicable, and  FIG. 2  is a cross-sectional view taken along the line  2 — 2  of FIG.  1 . 
   It is proposed, for example, in U.S. Pat. No. 5,947,245 to use a ratchet type one-way clutch  1  in the stator of a torque converter for an automatic transmission used in an automobile or the like. As shown in  FIG. 1  an annular outer ring  30  is molded from a aluminum by diecasting, and is formed integrally with the vanes  33  of a stator. The inner peripheral side of the outer ring  30  has a pocket  31  opening to an inner ring  20  side for containing a pawl  40  therein, and a spring pocket  32  formed in the inner portion of the pocket  31  and opening to the pocket  31  and containing therein a resilient member, i.e., a spring  50 , for pressing the tip end portion of the pawl  40  and biasing the pawl  40  to the inner diameter side. 
   While in  FIG. 1 , three such pawls  40 , pockets  31  and spring pockets  32  are provided circumferentially equidistantly, the number of these may be arbitrary and can be increased or decreased in the relation with torque or the like as required. However, it is preferable that they be provided at an equal pitch in the circumferential direction. Also,  FIG. 1  shows that the ratchet type one-way clutch is in a locked state wherein the pawls  40  are fitted in the notches  22  (which will be described later) of the inner ring  20 . Also, the springs  50  may preferably be coil springs, but of course, springs in other forms such as wave springs are also usable. 
   On the other hand, the inner ring  20  has in the outer peripheral side thereof notches  22  fitted to the pawls  40 , and has in the inner peripheral side thereof a spline  21  spline-fitted to a shaft, not shown. The notches  22  extends axially, and the axial length thereof corresponds to the axial width of the pawls  40 . As shown in  FIG. 1 , the notches  22  are formed by grinding the outer peripheral portion of a cylindrical member. Thus, the notches  22  and stepped portions  24  are circumferentially equidistantly disposed on the outer periphery of the inner race  20 . Of course, the number of the notches  22  and the number of the stepped portions  24  can be arbitrarily set in conformity with the number of the pawls  40 . 
   Also, as shown in  FIG. 2 , a bearing member  60  intervenes between the outer ring  30  and the inner ring  20  and at one axial end, and the bearing member  60  is prevented from axially slipping off by a snap ring  80 . Also, the axial opposite end portions of the ratchet type one-way clutch  1  are rotatably supported by needle bearings  70 . 
   In the ratchet type one-way clutch  1  constructed as described above, the outer ring  30  and each member disposed on the outer ring  30  perform the function that they can rotate rightwardly relative to the inner ring as viewed in  FIG. 1 , but cannot rotate leftwardly as viewed in  FIG. 1  due to the fitting between the pawls  40  and the notches  22 . That is, they can idly rotate in the rightward direction, but in the leftward direction, the one-way clutch becomes locked. 
   Each pawl  40  of the ratchet type one-way clutch  1  performing such an operation, as shown in  FIG. 5 , is supported from the axially opposite ends thereof by a projection  34  protruding axially inwardly of the pocket  31  from the wall of the axially inner portion of the pocket  31  of the outer ring  30  and a projection  93  protruding axially inwardly of the pocket  31  from the axial end surface of a bearing member  90 . Therefore, the pawl  40  pivotally moves about an axis linking the projection  34  and the projection  93  together, and is displaceable between a position in which it is fitted in the notch  22  and a position in which it slides relative to the outer peripheral surface of the inner ring  20 . 
   First to eighth embodiments of the present invention will hereinafter be described on the basis of the above-described ratchet type one-way clutch. 
   [First Embodiment] 
     FIGS. 3 and 4  are fragmentary cross-sectional views showing the details of the outer ring  30  in the first embodiment. The inner peripheral surface of the outer ring  30  was subjected to a hardening process to thereby form a hardened layer  103 . In  FIG. 3 , the entire inner peripheral surface of the outer ring  30  was subjected to the hardening process, but as shown, for example, in  FIG. 4 , only the surface thereof in the pocket  31  can also be subjected to the hardening process. By being subjected to the hardening process, the inner peripheral surface of the outer ring can be restrained from being indented or worn away by the pressure received from the pawl  40  during meshing and during repeated pivotal movement. Also, even if the pawl  40  vibrates or pivotally moves in the pocket  31 , the wear of the inner wall of the pocket  31  can be minimized. Thereby, the durability of the ratchet type one-way clutch is improved and the life thereof is extended. 
   [Second Embodiment] 
     FIG. 5  is a cross-sectional view of the essential portions of a ratchet type one-way clutch  1  according to the second embodiment of the present invention. As already described, the outer ring  30  is molded from aluminum by diecasting. At this time, from the relation of dies cutting, it is necessary to provide an inclined surface  110  having an angle of inclination (draft angle) α with the joint of the mold as the reference. This inclined surface  110  can be removed by planing work or the like at a later step, but this work requires labor and cost because the shape of the pocket  31  is somewhat complicated. Therefore, the joined surface  111  of the pawl  40  is given an angle of inclination α in advance in accordance with the draft angle α of the outer ring  30 . Thus, according to the present embodiment, the labor of working can be saved and the effect of reducing cost can be expected. Regarding the joined surfaces  114  and  115  to the bearing member  90  held by the inner ring  20  and the snap ring  102 , planing work becomes necessary in connection with dimensional accuracy and therefore, the inclination can be removed at this time. The joined surfaces to the inner ring  20  and the bearing member  90  are simple in shape and therefore do not require so much labor. 
   [Third Embodiment] 
     FIG. 6  is a fragmentary cross-sectional view showing the details of the outer ring in the third embodiment. In addition to the above-described diecasting step, the inner peripheral surface of the pocket  31  is subjected to coining or sizing to thereby improve dimensional accuracy and cause work hardening (strain hardening). For example, in the present embodiment, if the pressure receiving surface  104  of the pocket  31  against which the rear portion of the pawl  40  strikes under pressure is worked thus, the disposition accuracy of the pawl  40  is improved and the pressure receiving surface becomes capable of uniformly receiving a load. The “work hardening” used herein refers to the fact that the yield point by plastic deformation (stress which causes plastic deformation clearly to a certain degree) increases. 
   [Fourth Embodiment] 
     FIG. 7  is a typical view showing the fourth embodiment of the present invention, and showing the relation between the pawl  40  and the notch  22  on an enlarged scale. There is a case where during the reverse rotation of the outer ring  30  and the inner ring  20 , due to the pitch errors of the notches  22 , the pocket  31 , etc. some of the plurality of pawls  40  fall into the notches  22  and some of the pawls  40  do not fall into the notches  22 . At this time, a borne torque load comes to be applied to some notches  22  and pawls  40  and this hastens the wear or damage of the portions concerned. 
   In the fourth embodiment, the notch  22  is given an angle of inclination α for securing a width capable of absorbing the pitch errors of the notches  22 , the pocket  31 , etc. This angle of inclination α is provided with a segment L linking the point of intersection  100  between the extensions of two surfaces forming the notch  22 , i.e., a surface  23  radially rising and receiving a force F, and a bottom surface  27 , and the central point of the inner ring  20  together as the reference. However, the limit of this angle of inclination α is an angle at which the pawl  40  does not slip relative to the surface  23  during the meshing of the ratchet type one-way clutch  1 , specifically the order of 5.5°. When the inclination is a minus angle of inclination β with respect to the reference line L, even if the pawl  40  slips relative to the surface  23 , it is supported by the surface  27  and a corner portion  25  and therefore, such a problem does not arise. According to the present invention, it becomes possible to drop each pawl  40  reliably into the notch  22  during the meshing. 
   [Fifth Embodiment] 
     FIG. 8  is an enlarged front view of the pressure receiving surface of the pocket of the outer ring in the fifth embodiment of the present invention. During the idle rotation of the ratchet type one-way clutch  1 , the pawls  40  are normally urged against the inner ring  20  and therefore, the pawls  40  move in such a manner that they vibrate radially. If the pressure receiving surface of each of the pawls  40  and pocket  31  is flat, the pawls  40  repeat the contact with the pressure receiving surface  104  of the pocket  31  by the surface and corner portion and therefore the pressure receiving surface is liable to wear. 
   So, in the present embodiment, the pressure receiving  104  of the pocket  31  is formed into an arcuate shape having a predetermined radius of curvature R. In the present embodiment, there are the action of restraining wear and the action that it becomes difficult for fracture to occur because the pressure receiving surface  104  is not adjacent to the corner portion, and in addition, it becomes possible to make the angle of inclination α of the notch  22  somewhat great. This working of the pressure receiving surface  104  will be easy if plastic working is used. As this plastic working, there is the working by a reamer  101  shown in  FIG. 8 , broach working, slotter working or the like. 
   [Sixth Embodiment] 
     FIG. 9  is a cross-sectional view of the essential portions of a ratchet type one-way clutch according to the sixth embodiment of the present invention. Usually, the bearing member  90  is interposed between the outer ring  30  and the inner ring  20 , and the bearing between the outer ring  30  and the inner ring  20  can be provided by the outer peripheral surface  26  (see  FIG. 7 ) of the inner ring formed among the notches  22 , but according to the present embodiment, the outer peripheral surface  26  of the inner ring  20  can be decreased or eliminated and the number of the notches  22  can be increased, and there is obtained the effect of decreasing backlash. Here, the backlash means the amount of idle rotation in the meshing direction. 
   [Seventh Embodiment] 
     FIGS. 10 and 11  show the seventh embodiment of the present invention,  FIG. 10  being an enlarged view of the essential portions of  FIG. 9 , and  FIG. 11  being a front view showing the fitted state of the pawl and the notch. When one of the plurality of pawls  40  does not fall into the notch  22 , an eccentric load is created between the outer ring  30  and the inner ring  20 . In the present embodiment, a clearance S 1  ( FIG. 10 ) is provided between the bearing member  90  and the inner ring  20 , or a clearance S 2  ( FIG. 7 ) is provided between the inner peripheral surface  36  of the outer ring  30  and the outer peripheral surface  26  of the inner ring  20 . By these clearances, the pitch errors of the notches  22 , the pockets  31 , etc. can be absorbed and each pawl  40  can be reliably dropped into the notch  22 . 
   The total of the clearances S 1  and S 2  is set so as to be greater than the total of the accuracy errors of the size of the pawls  40 , the size and arrangement position of the pockets  31 , and the shape and arrangement position of the notches  22 . 
   [Eighth Embodiment] 
     FIG. 12  is a fragmentary enlarged view of the ratchet type one-way clutch of  FIG. 2 , illustrating the eighth embodiment of the present invention. The construction of the side plate  90  which is a part of the ratchet type one-way clutch  1  of the present invention will hereinafter be described in detail with reference to FIG.  12 . The side plate  90  having a substantially L-shaped cross-section comprises an annular plate portion  97 , a protruding portion  99  substantially perpendicularly protruding from one radial end portion of the plate portion  97 , and a convex portion  94  substantially perpendicularly protruding from the plate portion  97  in opposed relationship with the protruding portion. 
   Further, an axially protruding cylindrical projection  93  is provided on the axial side  94   b  of the convex portion  94 , and one axial side  40   a  of the pawl  40  is supported by the projection  93 . 
   On the other hand, an axially protruding cylindrical projection  35  is also provided on the wall surface  31   b  of the pocket  31 . Accordingly, the axially opposite sides of the pawl  40  are supported by the projection  35  provided on the outer ring and the projection  93  provided on the convex portion  94  of the side plate, respectively. The projection  35  and the projection  93  are provided with a view to reduce the viscosity resistance of lubricating oil relative to the pawl  40 . However, as the disposition of the projections, it is most desirable to provide the two projections so as to support the center of movement of the pawl  40 . 
   Further, the pocket  31  of the outer ring  30  and the convex portion  94  provided on the side plate  90  will now be described in detail with reference to FIG.  13 .  FIG. 13  is a fragmentary cross-sectional view taken along the line  13 — 13  of  FIG. 12 , and shows a state in which the convex portion  94  is fitted in the pocket  31 . However, the coil spring or the like provided in the spring pocket  32  is not shown for the purpose of clarifying the illustration. 
   The pocket  31  is comprised of an engagement surface  58  extending radially of the outer ring  30 , an upper surface  56  extending circumferentially from the engagement surface  58 , an inclined surface  54  inclined from the upper surface  56  toward the inner ring, and a rear surface  62  inclined from the inclined surface  54  toward the inner ring. The rear surface  62  is connected to an inner peripheral surface  60 . The spring pocket  32  for containing therein a resilient member for biasing the pawl  40  (see  FIG. 3 ) against the inner ring  20  is more proximate to a pawl  40   b  (see  FIG. 1 ) than the projection  93  and is formed substantially perpendicularly to the rear surface  62 . 
   The convex portion  94  of the side plate  90  is defined by an engagement surface  78 , an upper surface  76 , an inclined surface  74  and a rear surface  72  having shapes complementary to the engagement surface  58 , the upper surface  56 , the inclined surface  54  and the rear surface  62  defining the pocket  31 , and an abutting surface  94   b  having the projection  93 . 
   If circumferential positioning is effected by the convex portion  94  of the above-described construction, the position of the projection  93  can be maintained accurate and also, it becomes possible to regulate the movement of the side plate  90  in the circumferential direction. Further, it is possible to give the bearing function to all of the inner peripheral surface  60  of the side plate  90 , the inner peripheral side  52  of the convex portion  94  and the inner peripheral surface  24  of the outer ring  30 . 
   Of course, the above embodiments have been described as the illustrative examples of the present invention and do not restrict the present invention. 
   The present invention achieves the following various effects. 
   The surface of the pocket against which the pawl strikes is subjected to the hardening process and therefore, the durability of the ratchet type one-way clutch using the outer ring made of aluminum can be improved. 
   Also, the ratchet type one-way clutch is constructed so as to improve the meshing performance thereof and therefore, the durability of the ratchet type one-way clutch can be improved. 
   The pressure receiving surface of the notch is designed to have a predetermined angle of inclination with respect to a line linking the point of intersection between the surfaces forming the notch and the center of the inner ring together and therefore, during meshing, the pawl reliably falls into the notch. 
   The pressure receiving surface of the pocket and the pressure receiving surface of the pawl contacting with the said surface are arcuate and therefore, there are obtained the action of restraining wear and the action that it becomes difficult for fracture to occur because the pressure receiving surface is not adjacent to the corner portion. 
   The bearing member for securing the proper clearance between the inner ring and the outer ring is provided and the number of the notches can be increased, whereby there is obtained the action of decreasing backlash. 
   The clearance between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring or the clearance between the inner ring and the bearing member is greater than the total of the accuracy errors of the size of the pawls, the size and arrangement position of the pockets, and the shape and arrangement position of the notches and therefore, the pawls can be reliably dropped into the notches. 
   The side plate of the ratchet type one-way clutch is designed to be capable of being fitted in the pockets of the outer ring and be provided with a convex portion having the bearing function, whereby it is not necessary to provide convex portions and concave portions only for fitting the side plate to the outer ring on the outer ring and the side plate and therefore, the working process can be simplified.