A one-way clutch of an inscribed gear type has a cylindrical outer member having an inner gear at an inner circumference thereof; an inner member rotatably disposed in an inside space of the inner gear, and having gear receivers and a lock edge on one side in a circumferential direction of the gear receiver; and a planetary gear received rollably in each of the gear receivers to mesh with the inner gear. Shafts are projecting from both ends of the planetary gear, and bearing recesses are formed on the gear receiver to receive the shaft. By the engagement between the shafts and the bearing recesses, the planetary gear allows a circumferential displacement within a predetermined range with respect to the inner member required for engaging to or disengaging from the lock edge, and the planetary gear is prohibited from being displaced inward in a radial direction of the inner member.

TECHNICAL FIELD

The present invention relates to a one-way clutch and, more particularly, to a one-way clutch of an inscribed gear type.

BACKGROUND ART

As a one-way clutch for use in a sheet feeding mechanism for a facsimile, a copying machine, or the like, a one-way clutch of an inscribed gear type, is known, including a cylindrical outer member having an inner gear at its inner circumference; an inner member rotatably disposed in an inside space of the inner gear, having gear receivers at its outer periphery and a lock edge on one side in the circumferential direction of the gear receiver; and a planetary gear received rollably in each of the gear receivers so as to mesh with the inner gear (for example, Patent Document 1).

In a one-way clutch of an inscribed gear type, when an inner member is rotated in one direction with respect to an outer member, a planetary gear is displaced on one side in a circumferential direction inside of a gear receiver according to the rotation, so that a lock edge is fitted to a gear root of the planetary gear, thereby disenabling the planetary gear from rolling so as to connect the outer member and the inner member in a torque transmission relationship. To the contrary, when the inner member is rotated in the other direction with respect to the outer member, the planetary gear is displaced on the other side in the circumferential direction inside of the gear receiver according to the rotation, so that the lock edge is released (separated) from the gear root of the planetary gear, thereby enabling the planetary gear to roll so as to allow the outer member and the inner member to be rotated relatively to each other and break off the torque transmission relationship therebetween.

In the above-described one-way clutch of an inscribed gear type, the planetary gear rolls in the state in which its tip contacts with the inner circumferential surface of the gear receiver as if a polygonal member having the same number of vertexes as that of teeth of the planetary gear rolling inside of the gear receiver, thereby intermittently producing a chattering slide noise so as to inhibit silence.

In view of the above, there has been proposed a one-way clutch of an inscribed gear type including movement range regulating means for substantially prohibiting any radial displacement of a planetary gear, in which shafts project from both ends of the planetary gear, holes elongated in a circumferential direction are formed on both axial sides of a gear receiver, wherein the shafts of the planetary gear are fitted to the elongated holes, so that the planetary gear can be displaced in the circumferential direction with respect to an inner member but the tip of the planetary gear cannot contact with the inner circumferential surface of the gear receiver so as to allow the planetary gear to be fitted to or released from a lock edge (for example, Patent Document 2).

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: Japanese Patent Application Publication No. 2004-19757Patent Document 2: Japanese Patent Application Publication No. 2005-172199

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

In the movement range regulating means for the one-way clutch of an inscribed gear type in the prior art, the shafts projecting from both ends of the planetary gear are fitted to the elongated holes formed at both axial sides of the gear receiver, so that the planetary gear is doubly supported. Therefore, in incorporating the planetary gear such that the shafts projecting from both ends of the planetary gear are fitted to the elongated holes formed at both axial sides of each of the gear receivers, at least a wall on either side in the axial direction of the gear receiver, at which the elongated holes are formed, need to be constituted of a member independent of the inner member. As a consequence, the number of constituent parts and the number of incorporating man-hours are increased with a demand for incorporating precision in circumferentially positioning the elongated holes on both sides in the axial direction of the gear receiver.

A problem to be solved by the present invention is to prevent a planetary gear from rolling in the state in which the tip of the planetary gear contacts with the inner circumferential surface of a gear receiver without increasing the number of constituent parts and the number of incorporating man-hours and degrading incorporating precision so as to avoid a slide noise from occurring and secure silence in a one-way clutch of an inscribed gear type.

Means for Solving the Problem

A one-way clutch according to the present invention includes a cylindrical outer member having an inner gear at an inner circumference thereof; an inner member rotatably disposed in an inside space of the inner gear, and having gear receivers opened toward an outer peripheral side and a lock edge on either side in the circumferential direction of the gear receiver; and a planetary gear received rollably in each of the gear receivers to mesh with the inner gear.

When the inner member is rotated in one direction with respect to the outer member, the planetary gear is displaced on one side in the circumferential direction inside of the gear receiver according to the rotation and the lock edge is engaged to a gear root of the planetary gear. Thus, the planetary gear is disabled from rolling to connect the outer member and the inner member in a torque transmission relationship.

To the contrary, when the inner member is rotated the other direction with respect to the outer member, the planetary gear is displaced on the side in the other circumferential direction inside of the gear receiver according to the rotation and the lock edge is released from the gear root of the planetary gear. Thus, the planetary gear is enabled to rotate to allow the outer member and the inner member to be rotated relatively to each other and break off the torque transmission relationship therebetween.

The one-way clutch further includes shafts projecting from both ends in the axial direction of the planetary gear and bearing recesses formed on both end walls in the axial direction of the gear receiver to be released on the outer peripheral side of the inner member to receive the shafts. The fitting between the shafts and the bearing recesses allows a circumferential displacement of the planetary gear within a predetermined range with respect to the inner member, the displacement being required for fitting to or releasing from the lock edge, to prohibit the planetary gear from being displaced inward in the radial direction of the inner member.

With this configuration, the fitting between the shafts and the bearing recesses prohibits the planetary gear from being displaced inward in the radial direction of the inner member thereby securing that the tips of the planetary gear are not contacting with the inner circumferential surface of the gear receiver, so as to avoid any occurrence of a slide noise caused by the rolling in the state in which the tips of the planetary gear are contacting with the inner circumferential surface of the gear receiver. The displacement of the planetary gear outward in the radial direction of the inner member can be restricted by the mesh between the planetary gear and the inner teeth.

Although the bearing recesses formed on both end walls in the axial direction of the gear receiver prohibit the displacement of the planetary gear inward in the radial direction of the inner member due to the fitting to the shafts, they are released toward the outer periphery of the inner member, so that the shafts disposed at both axial ends of the planetary gear can be fitted to the bearing recesses from the outer periphery of the inner member. In this manner, it is unnecessary to constitute the wall on either side in the axial direction of the gear receiver independently of the inner member, thus preventing any problems of an increase in the number of component parts or incorporating man-hours and the degradation of incorporating precision.

In a one-way clutch according to the present invention, it is preferable that the tip surfaces of the shafts at both ends in the axial direction of the planetary gear should abut against the axial ends of the bearing recess, so as to restrict the axial movement of the planetary gear with respect to the inner member.

With this configuration, the planetary gear can be born in a thrust direction by fitting between the bearing recesses and the shafts, thereby avoiding any abutment of the tooth ends of the planetary gear against the axial side walls of the gear receiver, so as to avoid any occurrence of a slide noise caused by the abutment.

In a one-way clutch according to the present invention, it is preferable that the plurality of gear receivers for the planetary gears should be disposed at positions deviated from each other in the axial direction of the inner member.

With this configuration, the plurality of gear receivers are deviated from each other in the axial direction of the inner member, and therefore, the radial depth of the gear receivers can be increased more than the radius of the inner member without any interference of the gear receivers with each other. Consequently, the outer diameter of the one-way clutch can be reduced without reducing the diameter of the planetary gear.

Effects of the Invention

In the one-way clutch according to the present invention, the fitting between the shafts and the bearing recesses prohibits the planetary gear from being displaced inwardly in the radial direction of the inner member, thereby guaranteeing that the tips of the planetary gear does not contact with the inner circumferential surface of the gear receiver, so as to avoid any occurrence of a slide noise caused by the rolling in the state in which the tips of the planetary gear contact with the inner circumferential surface of the gear receiver. In addition, although the bearing recesses formed on both end walls in the axial direction of the gear receiver prohibit the displacement of the planetary gear inward in the radial direction of the inner member due to the engaging to the shafts, they are released toward the outer periphery of the inner member, so that the shafts disposed at both axial ends of the planetary gear can be fitted to the bearing recesses from the outer periphery of the inner member. In this manner, it is unnecessary to constitute the wall on either side in the axial direction of the gear receiver independently of the inner member, thus preventing any problems of an increase in the number of component parts or incorporating man-hours and the degradation of incorporating precision.

MODES FOR CARRYING OUT OF THE INVENTION

One preferred embodiment of a one-way clutch according to the present invention will be explained with reference toFIGS. 1 to 4.

A one-way clutch includes a cylindrical outer member10constituting a clutch case. A cylindrical rubber member or the like of a feed roller, not shown, is fixed to an outer periphery12of the outer member10. At the inner circumferential surface of the outer member10is formed a series of inner teeth (i.e., an inner gear)14in an inner circumferential direction.

In the cylindrical inside space of the outer member10, that is, an inside space of the inner gear, an inner member20having a substantially columnar shape penetrates in an axial direction (i.e., in a lateral direction inFIG. 1). Bearing outer peripheral portions22A and22B disposed at two portions apart from each other in the axial direction are slidably fitted to bearing inner circumferential portions16A and16B of the outer member10in a rotational direction, so that the inner member20is rotatably supported by the outer member10in a coaxial manner. An annular projection24is formed at the outer peripheral surface of the inner member20whereas an annular recessed groove18is formed at the inner circumferential surface of the outer member10. The annular projection24and the annular recessed groove18are fitted to each other, thus incorporating (i.e., stopping) the outer member10and the inner member20in the axial direction.

In the inner member20, portions projecting outwardly of the axial ends of the outer member10serve as bearings26and28that are rotatably supported on their own center axes via outside bearings, not shown. A driving outer gear30is formed at the outer peripheral portion in the inner member20and outward of the axial ends of the outer member10.

The inner member20includes a plurality of gear receivers, two in the present preferred embodiment,40and42. Each of the gear receivers40and42is formed into a cavity obtained by engraving a part of the outer peripheral portion of the inner member20into a pocket-like shape, and is opened onto the outer peripheral side of the inner member20. The gear receivers40and42are deviated from each other in the axial direction of the inner member20, and further, are formed at positions symmetric with respect to a point along the center axis of the inner member20, as viewed on an axial projection plane of the inner member20. That is to say, the gear receivers40and42are located at positions rotationally displaced at 180° from each other on the center axis of the inner member20.

In the inner member20, square-cornered lock edges52and54are formed at edges on one side in the circumferential direction of the gear receivers40and42, that is, at edges on a counterclockwise rotational advance side of the inner member20inFIGS. 2 and 3in the present preferred embodiment.

The gear receivers40and42respectively receive rollably therein planetary gears44and46having a series of outer teeth48and50at the outer peripheral surfaces, and further, in a displaceable manner by only predetermined amount in the circumferential direction of the inner member20. The respective outer teeth48and50of the planetary gears44and46mesh with the inner teeth14of the outer member10.

When the inner member20is rotated in one direction with respect to the outer member10(i.e., counterclockwise inFIGS. 2 and 3), the planetary gears44and46are displaced inside of the gear receivers40and42in one direction in the circumferential direction (in a counterclockwise advance direction, as viewed inFIGS. 2 and 3) according to the rotation of the inner member20, so that the lock edges52and54are fitted to the tooth roots of the planetary gears44and46, respectively. This fitting disenables the planetary gears44and46to roll with the outer teeth48and50meshing with the inner teeth14, and therefore, the outer member10and the inner member20are connected to each other in a torque transmission relationship, and thus, are integrally rotated in the same rotational direction (i.e., counterclockwise inFIGS. 2 and 3).

To the contrary, when the inner member20is rotated in the other direction with respect to the outer member10(clockwise inFIGS. 2 and 3), the planetary gears44and46are displaced inside of the gear receivers40and42in the other direction in the circumferential direction (in a clockwise advance direction, as viewed inFIGS. 2 and 3), so that the lock edges52and54are released from the tooth roots of the planetary gears44and46, respectively. This release enables the planetary gears44and46to roll with the outer teeth48and50meshing with the inner teeth14, and therefore, the outer member10and the inner member20are allowed to be rotated relatively to each other, so that they are released from the torque transmission relationship. In other words, the inner member20can be freely rotated counterclockwise inFIGS. 2 and 3with respect to the outer member10in the released state.

Shafts56and58project from both ends of the planetary gears44and46in the axial direction (i.e., in the lateral direction inFIG. 1). Bearing recesses60and62are formed and released on the outer peripheral side of the inner member20on both end walls of the gear receivers40and42in the axial direction (i.e., in the lateral direction inFIG. 1), so as to receive the shafts56and58, respectively.

To the bearing recesses60and62are fitted the shafts56and58of the planetary gears44and46, respectively. With this fitting, the planetary gears44and46are doubly supported at bottoms (i.e., inner circumferential surfaces)60A and62A of the bearing recesses60and62on the shafts56and58at both ends in the axial direction. Thus, the movement (i.e., the degree of freedom) of the planetary gears44and46inside of the gear receivers40and42are regulated by the shapes of the bearing recesses60and62(i.e., a lateral cross-sectional shape perpendicular to the axis of the inner member20).

In the bearing recesses60and62, the shafts56and58abut against the bottom60A and62A of the bearing recesses60and62in the mode in which the planetary gears44and46allow a circumferential displacement within a predetermined range with respect to the inner member10required for fitting to or releasing from the lock edges52and54, thereby prohibiting the planetary gears44and46from being displaced inward in the radial direction of the inner member20. The respective bottoms60A and62A of the bearing recesses60and62are formed into a shape having a linearly flat portion at which the planetary gears44and46are circumferentially displaced within the predetermined range with respect to the inner member10for fitting to or releasing from the lock edges52and54and an arcuate portion formed on a side on which the planetary gears44and46are released from the lock edges52and54, as well shown inFIG. 3, thereby retaining the shafts56and58in a freely rotating (rolling) manner.

Incidentally, although the respective bottoms (the inner circumferential surfaces)60A and62A of the bearing recesses60and62and the respective bottoms40A and42A of the gear receivers40and42are similar in shape to each other in the preferred embodiment shown in the drawings, the shape of each of the bottoms (the inner circumferential surfaces)60A and62A of the bearing recesses60and62cannot regulate the movement of the planetary gears44and46inside of the gear receivers40and42, and therefore, it may be freely set.

As described above, the fitting between the shafts56and58and the bearing recesses60and62can prohibit the planetary gears44and46from being displaced inward in the radial direction of the inner member20in the mode in which the planetary gears44and46allow the circumferential displacement required for the fitting to or releasing from the lock edges52and54within the predetermined range with respect to the inner member10. The outward displacement of the planetary gears44and46in the radial direction of the inner member20can be restricted by the mesh between the outer teeth48and50of the planetary gears44and46and the inner teeth14of the outer member10.

In this manner, with some assurances of the proper mesh between the outer teeth48and50of the planetary gears44and46and the inner teeth14of the outer member10, each of the component parts is dimensionally set, thereby securing clearances e between the tips of the planetary gears44and46and the bottoms60A and62A of the gear receivers40and42, so as to assure no contact of the tips of the planetary gears44and46with the bottoms60A and62A of the gear receivers40and42. As a consequence, the planetary gears44and46cannot roll in the state in which the tips of the planetary gears44and46contacts with the bottoms60A and62A of the gear receivers40and42, thus securely avoiding the occurrence of a slide noise caused by the rolling.

The bearing recesses60and62formed on both end walls in the axial direction of the gear receivers40and42prohibit the planetary gears44and46from being displaced inward in the radial direction of the inner member20due to the fitting to the shafts56and58. However, the bearing recesses60and62are formed into the shape released toward the outer periphery of the inner member20, and therefore, both of the shafts56and58disposed at both ends in the axial direction of the planetary gears44and46can be fitted to the bearing recesses60and62from the outer peripheral side of the inner member20. In this manner, the walls on either side in the axial direction of the gear receivers40and42need not be constituted of a member independent of the inner member20, thus raising no problem of an increase in the number of component parts or incorporating man-hours and degradation of the incorporating precision.

Moreover, in the present preferred embodiment, both axial ends of the outer teeth48and50of the planetary gears44and46are formed into chamfered shapes48A and50A. Consequently, the axial ends of the outer teeth48and50and the axial ends of the gear receivers40and42cannot slide contact with each other, thus preventing any occurrence of a slide noise at these portions.

The two gear receivers40and42for receiving the planetary gears44and46therein are deviated from each other in the axial direction of the inner member20and the adjacent gear receivers40and42do not overlap each other, as viewed in the axial direction of the inner member20in the above-described preferred embodiment. As a consequence, although the one-way clutch becomes long in the axial direction, the outer diameter of the one-way clutch can be reduced without reducing the diameter of each of the planetary gears44and46.

Here, although the number of gear receivers disposed in the inner member20is set to two in the above-described preferred embodiment, the number of gear receivers is not limited to two. It may be three, four, or more, as required.

The bearing recesses60and62may be formed into any shapes as long as the shafts56and58of the planetary gears44and46can be fitted into the bearing recesses60and62from the outer peripheral side of the inner member20. As shown inFIG. 5, a stopping protrusion61may be formed at an opening edge with respect to the outer peripheral surface of the inner member20. In this case, the shafts56and58come to be fitted into the bearing recesses60and62over the protrusion61from the outer peripheral side of the inner member20.

Another preferred embodiment of the one-way clutch according to the present invention will be described with reference toFIG. 6. InFIG. 6, component parts corresponding to those shown inFIG. 1are designated by the same reference numerals as those inFIG. 1, and therefore, their explanation will be omitted below.

Like the above-described preferred embodiment, in the present preferred embodiment, the fitting between shafts56and58and bearing recesses60and62can prohibit planetary gears44and46from being displaced inward in the radial direction of an inner member20in the mode in which the planetary gears44and46allow the circumferential displacement required for the fitting to or releasing from lock edges52and54within a predetermined range with respect to the inner member10. In addition, tip surfaces52A and54A of the shafts56and58at both ends in the axial direction of the planetary gears44and46abut against axial ends60B and62B of the bearing recesses60and62, thereby restricting the axial movement of the planetary gears44and46with respect to the inner member20.

In this manner, the planetary gears44and46are born in a thrust direction, thus avoiding the tooth ends of the planetary gears44and46from abutting against the axial side walls of gear receivers40and42, so as to avoid any occurrence of a slide noise caused by the abutment. In this case, both axial ends of outer teeth48and50of the planetary gears44and46need not always be formed into chamfered shapes48A and50A.

Furthermore, the tip surfaces52A and54A of the shafts56and58at both ends in the axial direction of the planetary gears44and46abut against the axial ends60B and62B of the bearing recesses60and62, thereby regulating the fixing attitude of the planetary gears44and46with respect to the inner member20, so as to prevent the center axes of the planetary gears44and46from being inclined with respect to the center axis of the inner member20. Consequently, the outer teeth48and50of the planetary gears44and46can mesh with inner teeth14with certainty, so that the outer teeth48and50of the planetary gears44and46can be excellently kept meshing with the inner teeth14.

Additionally, in the case where it is unnecessary to reduce the outer diameter of the one-way clutch, planetary gears72received in gear receivers70, respectively, may be arranged coaxially with an inner member20, as shown inFIG. 7.

Also in this preferred embodiment, the fitting between shafts74at both axial ends of the planetary gears72and bearing recesses76formed on both axial end walls of the gear receivers70can prohibit the planetary gears72from being displaced inward in the radial direction of the inner member20in the mode in which the planetary gears72allow the circumferential displacement required for the fitting to or releasing from lock edges78within a predetermined range with respect to the inner member10, like in the above-described preferred embodiments. Consequently, the same effects as those produced in the above-described preferred embodiments can be produced.

Although the present invention has been described by way of the preferred embodiments, it is not limited to the preferred embodiments as one skilled in the art can readily understand, and therefore, it can be appropriately changed within a range not departing from the scope of the present invention.

All of the disclosures of the Japanese Patent Application (Patent Application No. 2010-102162 filed on Apr. 27, 2010), which the present application claims the Convention priority based on, are incorporated in the specification of the present application by reference herein. All of the contents of the application, which the present application claims the Convention priority based on, and all of the contents of the prior art cited here in the present application constitute the specification of the present application by referring to them.

REFERENCE NUMERALS IN THE DRAWINGS