JP2007285471A - One-way clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of a fatigue life of a spring piece for energizing a roller in the narrowing direction of a wedge angle and to obtain high rotational accuracy over a long period of time in a one-way clutch in which rolling elements are stored in a predetermined number of pockets provided on the inside diameter face of an outer ring, when a shaft rotates in the narrow direction of the wedge angle formed between cam faces of the pockets and the shaft, the rolling elements bite into the wedge angle and the shaft is locked, and when the shaft rotates in a reverse direction, locking is released and the shaft is idly rotated. <P>SOLUTION: Out of the predetermined number of pockets 9 formed on the inside diameter face of the outer ring 1, an interval between two specified pockets 9 adjacent to each other in the circumferential direction is formed relatively larger than the intervals between the other pockets 9. A bearing part 8 is formed at the part that is formed large. A radial load applied to the shaft 6 is supported by the bearing part 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 one-way clutch having a bearing function.

  Conventional one-way clutches used in office machines such as printers and copiers are provided with a plurality of pockets at regular intervals in the circumferential direction on the inner diameter surface of the outer ring, and the bottom surface of the pocket rotates between the shafts. A cam surface that forms a wedge angle inclined in one direction is provided, and a bearing portion is formed on the inner surface of the outer ring between the pockets, and a rolling element (usually a roller) and the rolling element are placed in the pocket. It consists of the structure which accommodated the spring piece urged | biased in the narrow direction. The one-way clutch stores an outer ring containing rollers and spring pieces while blocking the outer ring member with one end closed and the other end open, and closing the open end of the outer ring member with a lid member. The rolling element is brought into contact with a shaft penetrating the closed end of the lid member, the outer ring and the outer ring member, and a load acting on the shaft is supported by the bearing portion (Patent Document 1).

  In the one-way clutch, when the shaft and the outer ring member rotate relative to each other in the narrow direction of the wedge angle, the rolling element engages and locks in the narrow portion, and the shaft, the outer ring member, and the casing are integrated with each other. Stop the rotation. Further, when rotating in the opposite direction, the rolling element moves in the enlargement direction, so that the lock is released and the shaft and the outer ring member relatively idle so as to act as a one-way clutch.

The one-way clutch is used, for example, in a fixing unit of a copying machine, for preventing web slack, and for preventing reverse rotation of a normally rotating shaft (Patent Document 2).
Japanese Patent Laid-Open No. 9-89011 (see “Embodiment”) Japanese Patent Laid-Open No. 2003-167466 (see FIG. 3, one-way clutch 643, paragraph 0040)

  In the use example of the one-way clutch as shown in Patent Document 2, the rolling elements as shown in Patent Document 1 are evenly arranged over the entire circumference, and a bearing is provided between the rolling elements. When the clutch is used, the rolling element may be located in a portion that receives a radial load from the shaft. If the shaft idles in this state, the rolling element moves in the direction of the spring piece, compressing the spring piece and generating excessive stress on the spring piece, resulting in an early fatigue life and loss of the ability to bias the rolling element. There is a case. If the spring piece loses the ability to urge the rolling element, the position of the rolling element becomes unstable, and the shaft is supported at an unstable position, which causes a problem that the rotational accuracy of the shaft is lowered.

  Accordingly, an object of the present invention is to provide a one-way clutch that prevents a radial load from a shaft from being received by a rolling element, thereby suppressing fatigue of a spring piece and obtaining high rotational accuracy over a long period of time.

  In order to achieve the above-mentioned object, as shown in the accompanying drawings, the present invention is provided with a plurality of pockets 9 provided at a predetermined interval in the circumferential direction on the inner surface of the outer ring 1 and between the plurality of pockets 9. A bearing portion 8 is provided, and a cam surface 12 is formed on the bottom surface of each pocket 9 to form a wedge angle θ that faces one direction of rotation with respect to the shaft 6. In the one-way clutch that houses the spring piece 11 that biases the moving body 2 in the narrow direction of the wedge angle θ, the interval between the two specific pockets 9 adjacent in the circumferential direction is between the other pockets 9. The bearing portion 8 is formed to be relatively larger than the interval, and the bearing portion 8 is formed in the larger portion.

  The one-way clutch having the above-described configuration is used in a portion where the outer ring 1 is fixed and the shaft 6 is rotated, and a one-way clutch action is performed at a contact portion between the rolling element 2 and the shaft 6. Bearing action takes place at the contact portion. In the case of the prior art, the bearing portions 8 are distributed over the entire circumference, but in the case of the present invention, the bearing portions 8 are concentrated in one place, so the position of the bearing portion 8 acts on the shaft 6. By setting the attitude of the outer ring 1 so as to be in a direction to receive a radial load, the radial load acting when the shaft 6 is idling is supported by the bearing portion 8. The rolling element 2 performs only a one-way clutch action, and is not affected by the radial load acting on the shaft 6, and it is possible to avoid an excessive stress from acting on the spring piece 11 that biases the rolling element 2.

  In addition, if the structure formed in the magnitude | size which reaches the half circumference of the internal diameter surface of the outer ring | wheel 1 as a magnitude | size (length of the circumferential direction) of the said bearing part 8, the area | region which performs a one-way clutch action | operation The bearing area can be more reliably separated.

  As described above, in the one-way clutch according to the present invention, the region that performs the clutch action and the region that performs the bearing action are separated from each other, so that the radial load acting on the shaft is supported only at the bearing portion, Will not be supported. For this reason, the fatigue life of the spring piece that performs the biasing action of the rolling element is also reduced, and the biasing action on the rolling element is reliably maintained. As a result, the posture of the rolling element can be stabilized and high rotation accuracy can be maintained over a long period of time.

  Further, by providing the bearing with a lubricant reservoir, the lubrication function of the bearing can be maintained for a long time.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  The one-way clutch of the embodiment includes an outer ring 1, a required number of rolling elements 2 (in this case, rollers), a spring member 3, an outer ring member 4, and a lid member 5, and a shaft 6 penetrates the inner diameter surface of the outer ring 1. Is done.

  The outer ring 1 has a clutch part 7 on the half circumference of the entire circumference of the inner diameter surface and a bearing part 8 on the other half. The clutch portion 7 includes four pockets 9 formed at regular intervals in the circumferential direction, rolling elements 2 accommodated in the pockets 9 and spring pieces 11 for biasing the rolling elements 2. The bearing portion 8 is provided with a lubricant reservoir 10 extending over the entire length in the axial direction.

  Each pocket 9 is provided over the entire length of the outer ring 1 in the axial direction, and a cam surface 12 inclined in a certain rotational direction is formed on the bottom surface thereof. A constant wedge angle θ is formed by the cam surface 12 and the tangent line drawn on the shaft 6 facing the cam surface 12. Further, a spring receiving recess 13 is provided at the enlarged end of the wedge angle θ of the pocket 9, and the spring piece 11 is inserted into the spring receiving recess 13 in the axial direction. The rolling element 2 is accommodated in the cam surface 12 and is urged by the spring piece 11 in the narrowing direction of the wedge angle θ.

As shown in FIG. 4, the spring member 3 includes an annular portion 14 formed by punching an elastic metal plate, and a spring piece formed on the outer peripheral edge of the half circumference with a space between the spring receiving recesses 13 in the circumferential direction. 11 consists of. The spring piece 11 is bent in the axial direction, but its middle part is folded back, and the folded part has appropriate elasticity. The annular portion 14 has a shaft hole 14 ′ that matches the inner diameter of the outer ring 1, the spring pieces 11 are inserted into the corresponding spring receiving recesses 13, and the annular portion 14 is pressed against one end surface of the outer ring 1. (See FIG. 3). In addition, an axial rotation prevention groove 15 is formed on the outer diameter surface of the outer ring 1,
The outer ring member 4 is provided with a closing surface 16 at one end and a shaft hole 17 at the center of the closing surface 16. A non-rotating protrusion 18 is provided on the inner diameter surface of the outer ring member 4, and a fitting groove 19 is provided on the inner periphery of the open surface. The outer ring 1 is housed inside the outer ring 1 in a state in which the detent groove 15 is fitted to the detent protrusion 18. A fitting protrusion 21 is provided on the outer peripheral surface of the lid member 5, and the opening surface of the outer ring member 4 is closed by the lid member 5 by fitting the fitting protrusion 21 into the fitting groove 19. The lid member 5 is also provided with a shaft hole 22 through which the shaft 6 penetrating from the shaft hole 22 to the shaft hole 17 of the outer ring 1 and the outer ring member 4 is inserted.

  The one-way clutch of the embodiment is configured as described above, and the operation thereof will be described next. In the state of use, the outer ring member 4 and the outer ring 1 integral with the outer ring member 4 are fixed to the device in such a posture that the bearing portion 8 is downward. The rolling elements 2 are urged by the spring pieces 11 in the narrow direction of the wedge angle θ, and are held in a stable posture. Further, a lubricant is sealed inside the outer ring 1, and a part of the lubricant is collected in the lubricant reservoir 10.

  When the shaft 6 is rotated in the direction in which the wedge angle θ is enlarged (the direction of the arrow A in FIG. 1), the rolling element 2 moves while compressing the biasing spring piece 11 and enters the unlocked free state. Is idle. During the idling, the rolling element 2 rotates while being held at a position where the rotational force from the shaft 6 and the pressing force of the spring piece 11 are balanced. At this time, the radial load acting on the shaft 6 is directly supported by the bearing portion 8. Since the range of the bearing portion 8 is wide enough to reach substantially half the inner circumference of the outer ring 1, the bearing portion 8 does not deviate from the bearing portion 8 even if the radial load direction fluctuates. For this reason, supporting a load via the rolling element 2 is avoided, and an excessive stress is prevented from acting on the spring piece 11. The bearing 8 is lubricated by the lubricant enclosed in the outer ring 1 and the lubricant stored in the lubricant reservoir 10.

  When the shaft 6 is rotated in the opposite direction, the rolling element 2 moves in the narrow direction of the wedge angle θ and enters a locked state, and the rotation of the shaft 6 is stopped.

  The basic structure of the one-way clutch is composed of the outer ring 1, the rolling element 2, and the spring piece 11. In order to prevent the rolling element 2 and the biasing spring piece 11 from slipping out and to enclose the lubricant. In addition, a structure that is housed inside the outer ring member 4 and is closed by the lid member 5 is generally employed.

Sectional view of the one-way clutch of the embodiment Sectional view along line XX in FIG. FIG. 2 is a partially omitted sectional view taken along line YY in FIG. Exploded perspective view of one-way clutch of the embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Roller 3 Spring member 4 Outer ring member 5 Lid member 6 Shaft 7 Clutch part 8 Bearing part 9 Pocket 10 Lubricant accumulation part 11 Spring piece 12 Cam surface 13 Spring receiving recessed part 14 Annular part 14 'Shaft hole 15 Anti-rotation groove 16 Blocking surface 17 Shaft hole 18 Non-rotating protrusion 19 Fitting groove 21 Fitting protrusion 22 Shaft hole

Claims (4)

  A plurality of pockets (9) are provided on the inner diameter surface of the outer ring (1) at a required interval in the circumferential direction, and a bearing portion (8) is provided between the plurality of pockets (9). Is provided with a cam surface (12) that forms a wedge angle θ in one direction of rotation with respect to the shaft (6), and the pocket (9) has a rolling element (2) and its rolling element (2 ) In the narrow direction of the wedge angle θ, in the one-way clutch, the interval between the two adjacent pockets (9) adjacent in the circumferential direction is the other pocket. (9) A one-way clutch characterized in that it is formed to be relatively larger than the interval between them, and the bearing portion (8) is formed in the larger portion.   The one-way clutch according to claim 1, wherein the bearing portion (8) is formed to have a size that reaches substantially the length of a half circumference of the inner surface of the outer ring (1).   The one-way clutch according to claim 1 or 2, wherein the bearing portion (8) is provided with a lubricant reservoir (10).   The outer ring (1) incorporating the rolling element (2) and the spring piece (11) is housed in the outer ring member (4) with a lid having a shaft hole (17) with a rotation stop. The one-way clutch according to any one of claims 1 to 3.

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