JP2006162027A - One-way clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem where a shaft free from quenching treatment is worn away by a bearing portion formed by an inside diameter face of an outer ring between pockets, in an one-way clutch wherein rollers are stored in the required number of pockets formed on the inside diameter face of the outer ring, the rollers are locked to transmit torque when the shaft is rotated in the direction of narrowing a wedge angle formed by a cam face of the pocket and the shaft, and the rollers are idled to cut off the transmission of torque when the shaft is rotated in the reverse direction. <P>SOLUTION: Arm portions 14 having the shape same as the shape between the pockets 12 are formed on a lid member closing one end face of the outer ring 1, the arm portions 14 are respectively inserted between the pockets 12, the bearing portion 16 is formed by the inner faces of the arm portions 14, and the lid member including the arm portions 14 is made of a synthetic resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a one-way clutch used in a driving unit such as a paper feeding unit of a printer or a copying machine, and more particularly to a bearing unit.

  Conventional one-way clutches used in office machines such as printers and copiers are provided with a plurality of pockets on the inner ring surface of the outer ring in the circumferential direction at a required interval and rotated between the shaft on the bottom surface of the pockets. And a cam member that forms a wedge angle inclined in one direction, a bearing portion is formed on the inner ring inner surface between the pockets, and the roller and the roller are biased in the pocket in the direction of narrowing the wedge angle. The outer ring is housed in a casing that is closed at one end and open at the other end, and the open end of the casing is closed by the lid member, and the shaft that passes through the closed end of the lid member, the outer ring, and the casing is inserted into the casing. It is made to support in a bearing part (patent document 1).

In the one-way clutch, when the shaft rotates in the narrow direction of the wedge angle, the roller engages and locks the narrow portion, and the shaft, the outer ring member, and the casing rotate integrally. When it rotates, the roller moves in the enlargement direction so that the shaft rotates idly.
Japanese Patent Laid-Open No. 9-89011 (see “Embodiment”)

  In the one-way clutch, since the outer ring is usually made of a sintered alloy, slippage occurs between the bearing portion of the outer ring and the shaft when the shaft idles in a state where a radial load is applied. As measures against shaft wear due to this slip, measures to increase the shaft hardness or lower the radial load are required. Since the shaft used for the office machine has many non-quenched shafts and low hardness, measures to reduce the radial load are usually taken. However, there is a problem that lowering the radial load leads to machine specification reduction. In order to avoid this, if the hardness of the shaft is increased, there is a problem that leads to an increase in cost.

  Therefore, an object of the present invention is to provide a one-way clutch capable of applying a sufficiently large radial load without increasing the shaft hardness by improving the bearing portion of the outer ring.

  In order to achieve the above-mentioned object, the present invention provides a plurality of pockets at a predetermined interval in the circumferential direction on the inner diameter surface of the outer ring, and faces one direction of rotation between the bottom surface of the pocket and the shaft. A cam surface for forming a wedge angle is provided, a bearing portion is formed on the inner ring inner surface between the pockets, and a roller and a spring member for urging the roller in a narrow direction of the wedge angle are housed in the pocket. In the one-way clutch in which a shaft is passed through the lid member closed at one end and the outer ring, and a radial load acting on the shaft is supported by the bearing portion, the cam surface of the pocket is narrowed in the wedge angle direction. The extension surface is formed to reach the enlarged side end portion of the cam surface of the adjacent pocket, and the inner surface of the lid member is required to fit within the range of each extension surface. A number of arms To form the enlarged end and the narrow end of each pocket by side facing the circumferential direction of the arm portions of two adjacent, employing the configuration to form a bearing portion of the by the inner surface of the arm portion.

  In the one-way clutch having the above configuration, the cam surface of the pocket is formed on the outer ring, but both end portions in the rotational direction of the pocket are formed by side surfaces of the arm portion provided integrally with the lid member, and the inner surface of the arm portion The bearing portion is formed. Since the lid member and the arm portion integrated with the lid member are made of synthetic resin, they are not worn even if a radial load is applied thereto when the shaft is not quenched.

  Further, the length of the arm portion is formed such that the tip portion reaches the end surface opposite to the lid member fitting end surface of the outer ring, and the engagement convex portion provided on the tip portion is provided on the outer ring end surface. It is desirable to adopt a configuration in which the fitting recess is fitted with a snap fit. With this configuration, the lid member is engaged and integrated with the outer ring, and the roller and the spring member are held in each pocket by the pressing force and the reaction force of the spring member, so that they are not housed in the casing. The outer ring, the lid member, the roller, and the spring member are not separated and dispersed, and can be handled in an integrated state.

  In addition, the structure which provided the bearing auxiliary | assistant part protruded from the said bearing part to the pocket side in the side surface of the said arm part which forms the narrow side end surface of the wedge angle of the said pocket can be taken. According to this configuration, the contact area of the bearing portion is increased, and the concave portion that accommodates the spring member is formed between the bearing auxiliary portion and the step portion at the enlarged-side end portion of the wedge angle opposed in the radial direction. And the spring member can be held stably.

  As described above, in the one-way clutch according to the present invention, the bearing portion that is conventionally provided directly on the outer ring is formed by the arm portion that is provided on the synthetic resin lid member separate from the outer ring. Even when the shaft is not subjected to quenching treatment, there is no possibility that the shaft is worn even when it is used with a required radial load.

  Further, by engaging the engaging convex portion provided at the tip of the arm with the engaging concave portion provided at the end surface of the outer ring by snap fitting, the constituent members of the outer ring, the lid member, the roller, and the spring member are integrated. Therefore, the handleability is improved.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 to 3, the one-way clutch includes an outer ring 1, a lid member 2, the same number of spring members 4 and casings 5 as the required number of rollers 3.

  The outer ring 1 is made of a sintered alloy, and both end surfaces are opened. On the inner diameter surface, as shown in FIG. 4A, a curved surface 6 having a gradually decreasing radius in a constant rotational direction is formed at a position equally divided into five in the circumferential direction. A step 7 in the radial direction is formed at the boundary between the curved surfaces 6. Further, on one end surface of the outer ring 1, an engagement recess 8 is formed in the radial direction from the middle of the curved surface 6. A range from the maximum diameter side end of the curved surface 6 to the engagement recess 8 is indicated by A, and a range from the remaining minimum diameter side end (the maximum diameter side end of the adjacent curved surface 6) is indicated by B. . A portion of the curved surface 6 in the range A is referred to as a cam surface 9, and a portion of the curved surface 6 in the range B is referred to as an extended surface 10 of the cam surface 9. The engaging recess 8 is formed within the range of the extended surface 10, and both sides 8a and 8b have a spread of an angle α.

  As will be described later, a shaft 11 passes through the outer ring 1 via a roller 3. The angle θ between the tangent lines of the cam surface 9 and the shaft 11 is referred to as a wedge angle.

  The range from the side 8b seen in the narrow direction of the wedge angle θ of the engagement recess 8 to the side 8a of the next engagement recess 8 is D. The range from one side 8b of the engaging recess 8 to the step 7 is C.

  In order to divide the inner diameter surface of the outer ring 1 in the circumferential direction to form five pockets 12, the five arm portions 14 are directed in the axial direction along the shaft hole 13 (see FIG. 3) on the inner surface of the lid member 2. Provided. The length L of each arm portion 14 is formed to coincide with the length L of the outer ring 1 (see FIGS. 4B and 4C). The arm part 14 has a columnar shape with an L-shaped cross section, and is provided with an engaging convex part 15 protruding outward in the radial direction at the tip part (see FIGS. 4C and 4D). The end portion of the arm portion 14 including the engagement convex portion 15 has a spread corresponding to the spread angle α of the engagement concave portion 8 (see FIG. 4D). When the arm portion 14 is inserted from the end of the outer ring 1, the engagement convex portion 15 is slidably contacted with the extended surface 10, whereby the arm portion 14 is elastically deformed inward (see the one-dot chain line in FIG. 1), and pushed forward. When the other open end is reached, the engaging convex portion 15 is snap-fitted into the engaging concave portion 8.

  A projecting portion 17 is provided over the entire length of the arm portion 14 along the inner surface of the arm portion 14, whereby the cross-sectional shape of the arm portion 14 is L-shaped as described above. The inner surface portion on the inner diameter side of the arm portion 14 and the protruding portion 17 serves as a bearing portion 16, and the bearing portion 16 is in sliding contact with the shaft 11. Further, the projecting portion 17 is opposed to a portion in the range C of the extended surface 10 in the radial direction, and a spring accommodating recess 18 is formed between the facing surfaces (see FIGS. 2 and 4A).

  Examples of the material of the lid member 2 include POM, PPS, and PEEK. POM is desirable when cost and performance are considered, and PPS and PEEK are desirable when used at high temperatures.

  In the state where the lid member 2 is combined with the outer ring 1 and the engagement convex portion 15 of each arm portion 14 is fitted to the engagement concave portion 8 by snap fitting, the range D (see FIG. 4A). The inner side surfaces of the two arm portions 14 are opposed to each other in the circumferential direction at both ends, and a large diameter side end portion of the pocket 12 is formed on one inner side surface, and a small diameter side end portion is formed on the other inner side surface. The The roller 3 is interposed between the cam surface 9 of each pocket 12 and the shaft 11, and the spring member 3 is accommodated in the spring accommodating recess 18. The spring member 3 is formed by bending a leaf spring into an S-shape, and by pressing this against the roller 3, the roller 3 is urged in the narrow direction of the wedge angle θ, and at the same time, the spring member 3 is caused by the reaction force. Is pressed against the inner surface of the spring housing recess 18.

  As described above, the lid member 2 is combined with the outer ring 1, and the roller 3 and the spring member 4 are stored in the pocket 12 defined by the arm portion 14 integrated with the lid member 2, and the roller 3 is attached to the spring member 4. In the biased state, the outer ring 1, the lid member 2, the roller 3 and the spring member 4 are integrated to form an intermediate assembly.

  The intermediate assembly is stored in the casing 5. The casing 5 is provided with a shaft hole 19 at the closed end of one end, and a circumferential groove 21 is formed on the inner peripheral surface of the open end. A shallow anti-rotation recess 22 formed in the axial direction on the outer diameter surface of the outer ring 1 is fitted with a protrusion 23 provided on the inner diameter surface of the casing 5 without rattling and is prevented from rotating. Further, the engaging rib 24 formed on the outer peripheral surface of the lid member 2 is engaged with the circumferential groove 21 so that the casing 5 and the lid member 2 are integrated.

  The shaft 11 extends from the shaft hole 13 of the lid member 2 to the shaft hole 19 of the casing 5, and the bearing portion 16 of each arm portion 14 contacts the outer diameter surface of the shaft 11 inside the outer ring 1.

  The one-way clutch of the embodiment is configured as described above. When the shaft 11 rotates in the direction of the arrow a in FIG. 2 (the narrow direction of the wedge angle θ) with respect to the casing 5, the roller 3 becomes the cam surface 9 and the roller 3. And a locked state, and the torque of the shaft 11 is transmitted to the casing 5. When the shaft 1 rotates in the direction opposite to the above, the roller 3 moves in the direction in which the wedge angle θ is enlarged, and the shaft 11 is idled so that torque transmission is interrupted. In addition, when torque is transmitted in the direction of the shaft 11 from the casing 5 side, it is transmitted by the same action.

  A radial load applied to the shaft 11 is supported by a bearing portion 16 made of synthetic resin, and is in sliding contact with the bearing portion 16 when the shaft 11 is idling. The PV value of the bearing portion 16 is higher than the original PV value of the resin of the lid member 2 due to the presence of the lubricant filled in the outer ring 1. Further, since the bearing portion 16 is made of synthetic resin, the shaft 11 that has not been quenched is not worn. Moreover, since the cam surface 9 is formed of sintered metal as usual, sufficient wear resistance is ensured.

Cross-sectional view of one-way clutch of embodiment Sectional view along line XX in FIG. Exploded perspective view (A) is an end view of the outer ring, (b) is a sectional view, (c) is a partial side view of the lid member, and (d) is an end view of the arm portion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Lid member 3 Roller 4 Spring member 5 Casing 6 Curved surface 7 Step part 8 Engagement recessed part 9 Cam surface 10 Extension surface 11 Shaft 12 Pocket 13 Shaft hole 14 Arm part 15 Engagement convex part 16 Bearing part 17 Projection part 18 Spring Storage recess 19 Shaft hole 21 Circumferential groove 22 Anti-rotation recess 23 Projection 24 Engagement rib

Claims (5)

  A plurality of pockets are provided on the inner diameter surface of the outer ring at a predetermined interval in the circumferential direction, and a cam surface is formed on the bottom surface of the pocket to form a wedge angle facing one direction of rotation with the shaft. A bearing portion is formed on the inner surface of the outer ring, a roller and a spring member that urges the roller in the direction of narrowing of the wedge angle are housed in the pocket, and a lid member and an outer ring that are closed at one end of the outer ring are shafts. In the one-way clutch in which the radial load acting on the shaft is supported by the bearing portion, the cam surface of the pocket is extended in the narrow direction of the wedge angle to form an extension surface and the extension surface Is formed so as to reach the enlarged side end of the cam surface of the adjacent pocket, and the inner surface of the lid member is provided with a required number of arm portions that fit within the range of the extended surfaces, and two adjacent arms Pair in the circumferential direction of the part One-way clutch to the narrow end of each pocket by side to form a larger end, characterized by the inner surface of the arm portion to the formation of the bearing portion of the.   The front end of the arm portion is formed to a length that reaches the end surface of the outer ring opposite to the lid member fitting end surface, and the engagement convex portion provided at the front end portion is snapped to the engagement concave portion provided at the outer ring end surface. The one-way clutch according to claim 1, wherein the one-way clutch is fitted by fitting.   3. The one-way clutch according to claim 1, wherein a bearing auxiliary portion protruding from the bearing portion toward the pocket side is provided on a side surface of the arm portion forming the enlarged side end portion of the pocket.   The one-way clutch according to claim 3, wherein a concave portion for accommodating the spring member is formed between the bearing auxiliary portion and a step portion at an enlarged side end opposed to the bearing auxiliary portion in the radial direction.   The outer ring is housed in a casing having a closed end at one end and an open end at the other end, and the shaft is inserted into a through-hole provided in the closed end. The one-way clutch according to any one of claims 1 to 3, wherein the lid member is fitted.

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