JP2006144811A - One-way clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-way clutch which copes with both an engaging property and a high allowance torque property and dissolves engaging slippage and delay. <P>SOLUTION: The one-way clutch 5 comprises a plurality of rollers 13 respectively arranged in a plurality of wedge-shaped spaces 12 formed between an inner ring 3 and an outer ring 4, and a coil spring 14 urging each roller 13 in an engaging direction. A diameter of the roller 13 is 4 mm or more, the number of rollers 13 is 10 pieces or less, a wedged angle of the wedge-shaped space 12 is 4 to 9 degrees, and urging force of the coil spring 14 in a set position is set to be 1 Newton or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to, for example, a one-way clutch suitable for use in a belt drive starter in a belt transmission system for transmitting a rotational force by a belt when starting an internal combustion engine and driving an auxiliary machine by the internal combustion engine.

An inner ring, an outer ring, a plurality of rollers respectively disposed in a plurality of wedge-shaped spaces formed between the two wheels, a biasing member that biases each roller in the biting direction, and a cage that holds the plurality of rollers Directional clutches are conventionally known (Patent Document 1).
JP 2003-176866 A

  When using the one-way clutch of the above-mentioned Patent Document 1 as a starter for an engine, it is required to have meshability at the start in a cold region in winter, while also requiring high permissible torque, which is a function contrary to meshability. It is difficult to achieve both of these. For example, when the wedge angle of the wedge-shaped space is large, it is advantageous for the allowable torque, and when it is small, it is advantageous for the meshing property. By adjusting the angle of the wedge angle, it is possible to balance the allowable torque and the meshing property. Conceivable.

  However, with regard to meshing performance, it is necessary not only to improve the low-temperature meshing performance required at the time of starting, but also to eliminate meshing slippage and delay, and it is necessary to eliminate meshing slippage and delay only by adjusting the wedge angle. It is difficult, and in addition to satisfying both low-temperature meshing property and high permissible torque property, it is a new issue to reliably return the separated roller to the set position. It is the urging force of the urging member that returns the separated roller to the set position. Conventionally, this urging force is the urging force required to move the roller to the meshing position when meshing> (roller weight + roller inertia) Force + roller vibration load), and the biasing force required for the separated roller to return to the set position> the roller's own weight, and increasing the biasing force makes it difficult for the roller to separate. The biasing force of the biasing member was designed to be as small as possible within the range. Therefore, the urging force of the urging member at the set position is about 0.8N.

  The object of the present invention is to introduce the viscous force and adhesive force of grease, which has not been considered in the past, as an urging force determining factor of the urging member, thereby achieving both meshability and high allowable torque, The object is to provide a one-way clutch that eliminates the delay.

  The one-way clutch according to the present invention includes an inner ring, an outer ring, a plurality of rollers respectively disposed in a plurality of wedge-shaped spaces formed between the two wheels, a biasing member that biases each roller in the biting direction, and a plurality of rollers. In a one-way clutch provided with a retainer, the diameter of the roller is 4 mm or more, the number of rollers is 10 or less, the wedge angle of the wedge-shaped space is 4 to 9 °, and the biasing force of the biasing member at the set position is It is characterized by being 1N or more.

  By increasing the diameter of the roller, the centrifugal force applied to the roller can be increased, whereby the roller can be quickly separated. Therefore, the diameter of the roller is preferably 4 mm or more (20 mm or less). In the one-way clutch, the outer diameter of the outer ring and the inner diameter of the inner ring are determined by a device (for example, a pulley unit) in which the one-way clutch is used, and the upper limit of the roller diameter is the outer diameter of the outer ring (for example, the pulley outer diameter). And the inner diameter of the inner ring (for example, the outer diameter of the rotating shaft). The number of rollers is substantially determined by determining the diameter of the rollers. In order to make the diameter of the rollers 4 mm or more, the number of rollers is preferably 10 or less (4 or more). The wedge angle of the wedge-shaped space (the angle formed by the tangent at the contact position between the roller and the inner ring and the tangent at the contact position of the outer ring when engaged) is used to achieve both meshability and high permissible torque. Is preferably 4 to 9 °, and more preferably 5 to 7 ° in order to obtain excellent low-temperature meshability. The urging force of the urging member at the set position (the stop position of the roller when the inner and outer rings are not rotating) is preferably 1N or more. If the urging force is increased, the roller is less likely to be detached. Is done. The urging force of the urging member at the set position is more preferably 1.5 to 3N.

  Regarding the urging force of the urging member, conventionally, the urging force required to move the roller to the meshing position during meshing> (roller weight + roller inertial force + roller vibration load) and the separated roller returns to the set position. However, the one-way clutch of the present invention is designed as follows.

  Energizing force necessary to move the roller to the meshing position during meshing> (roller weight + roller inertial force + roller vibration load + grease viscosity force) and energizing force necessary for the separated roller to return to the set position> ( There is a relationship of roller self-weight + grease viscosity force + adhesion force (force that the roller sticks to the cam surface), and the biasing force of the biasing member at the set position is slightly larger than the larger of these two formulas Great value. Therefore, when the grease viscous force is larger than the biasing force of the biasing member at the set position based on the conventional concept, or when the adhesion force is relatively large, (the adhesion force minus the roller inertia force) -Roller vibration load) will be further increased.

  The one-way clutch is disposed in a wedge-shaped space formed by a cam surface provided on the inner peripheral surface of the outer ring and the cam surface and the outer peripheral surface of the inner ring, and the inner ring and the outer ring are in one direction (locking direction). By rotating relative to each other, the rollers as a plurality of engagement members that are engaged between the inner ring and the outer ring and release the engagement when rotated in the other direction (free direction), and the direction in which the rollers are engaged (wedge) A coil spring as an urging member for urging the narrow space) and a cage for positioning the rollers in the wedge-shaped space (outer ring cam type).

  This one-way clutch is suitable for use as, for example, a starter (particularly for an idle stop vehicle), and can also be used as an alternator. The belt-driven starter is locked only when the engine is started, and the locked state is short and low-speed rotation, and the free state is long and high-speed rotation. In contrast, the alternator is relatively locked. It takes a long time and high speed rotation, and the free state time is short and low speed rotation. However, for any use, the above conditions make it possible to achieve both meshability and high permissible torque. At the same time, meshing slips and delays can be eliminated.

  The one-way clutch is used as a pulley unit with a one-way clutch in which the one-way clutch is arranged between a shaft and a pulley arranged concentrically around the shaft, and rolling bearings are arranged on both sides thereof. It is suitable for. In this case, the one-way clutch may have an outer ring that is a member different from the pulley and an inner ring that is a member different from the hollow shaft, and an intermediate portion of the pulley is an outer ring of the one-way clutch. At the same time, the middle part of the hollow shaft may be the inner ring of the one-way clutch. In the case of the former (the outer ring and inner ring of the one-way clutch are separate members from the pulley or hollow shaft), for example, the inner diameter of the pulley is the same except for the annular groove portion for hermetic seal, and the outer ring of the bearing is Axial positioning is performed by contacting the outer ring of the one-way clutch. The outer diameter of the hollow shaft is the same except for the annular groove portion for hermetic sealing, and the inner ring of the bearing is positioned in the axial direction by contacting the inner ring of the one-way clutch during press-fitting. In the latter case (the pulley also serves as the outer ring of the one-way clutch and the hollow shaft also serves as the inner ring), for example, the inner diameter of the pulley is formed in a stepped shape in which both ends are larger in diameter than the intermediate part. The outer ring is positioned by the step portion of the pulley, and the inner ring of the bearing is positioned by positioning the outer ring.

  According to the one-way clutch of the present invention, the roller diameter is 4 mm or more, the number of rollers is 10 or less, and the wedge angle of the wedge-shaped space is 4 to 9 °, so that the meshing property and the high allowable torque property are high. Furthermore, since the urging force of the urging member at the set position is 1 N or more, the meshing slip and the delay can be eliminated.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the left and right refer to the left and right in FIG.

  1 and 2 show a pulley unit using a one-way clutch according to the present invention. This one-way clutch-equipped pulley unit (1) is arranged at a portion connecting an engine drive unit and a rotation shaft of a starter motor, and is a hollow shaft (3) fitted to the rotation shaft (2) of the starter motor. ) And a pulley (4) arranged concentrically therewith, a one-way clutch (5) is provided. On the outer periphery of the pulley (4), there is provided a belt spanning portion (4a) on which the V-ribbed belt (B) is spanned.

  The one-way clutch (5) is provided between the hollow shaft (3) and the intermediate portion in the axial direction of the pulley (4), and is located between the hollow shaft (3) and a portion near each end of the pulley (4). Between them, a roller bearing (6) whose rolling element is a roller (6a) and a ball bearing (7) whose rolling element is a ball (7a) are provided with a one-way clutch (5) interposed therebetween. The outer ring of the pulley (4) and the one-way clutch (5) and the outer ring of the bearings (6) and (7) are integrated, and the inner ring and the bearing of the hollow shaft (3) and the one-way clutch (5) ( 6) The inner ring of (7) is integrated.

  Seal members (8) and (9) are arranged on the outer sides in the axial direction of the roller bearing (6) and the ball bearing (7), respectively, and on the free end side (the left end side in the figure) of the pulley unit, the pulley unit In order to prevent intrusion of muddy water or the like inside, another seal member (10) is arranged.

  As shown in FIG. 2, the one-way clutch (5) includes a cam surface (11) provided on the inner peripheral surface of the pulley (4), a cam surface (11), and an outer peripheral surface of the hollow shaft (3). The hollow shaft (3) and the pulley (4) are arranged in the wedge-shaped space (12) formed, and the hollow shaft (3) and the pulley (4) rotate relative to each other in one direction (locking direction). Between the roller (13) as a plurality of biting members that release the bite when rotated relative to each other in the other direction (free direction) and the roller (13) in the biting direction (wedge-shaped space (12 A coil spring (14) as an urging member for urging to the narrow side) and a cage (15) for positioning the roller (13) in the wedge-shaped space (12).

  The cam surface (11) is configured by providing a plurality (three in this embodiment) of cam surfaces (11a) facing each other across the shaft center in the circumferential direction. Thus, by providing the cam surface (11) on the pulley (4), the pulley (4) is given a function as an outer ring of the one-way clutch (5), and the pulley (4) and the one-way clutch (5 ) Is integrated with the outer ring. As a result, while the outer diameter of the pulley (4) is suppressed, the P.P. C. D can be increased, and the centrifugal force acting on the roller (13) is large. A concave surface portion (16) for stopping the roller (13) receiving a centrifugal force with a circular cross section is provided at the end of the cam surface (11) on the wide side of the wedge-shaped space (12).

  As shown in FIG. 1, the inner diameter of the pulley (4) is stepped, and the outer ring of the roller bearing (6), the outer ring of the one-way clutch (5) and the ball bearing that the pulley (4) has. Regarding the dimensions corresponding to each function of the outer ring of (7), the inner diameter of the outer ring raceway portion of the roller bearing (6) is D1, and the minimum inner diameter of the outer ring of the one-way clutch (5) (in this embodiment, the outer ring cam surface (11) D1> D2 ≧ D3, where D2 is the distance between the two surfaces) and D3 is the inner diameter of the shoulder of the outer ring raceway of the ball bearing (7). The outer diameter of the hollow shaft (3) is constant except for the groove, and the inner ring raceway outer diameter of the roller bearing (6) = the inner ring outer diameter of the one-way clutch (5) = the ball bearing (7). The outer diameter of the outer ring raceway shoulder. As a result, the outer diameter of the inner ring is suppressed, and it is easy to ensure the dimensions of the one-way clutch.

  The cage (15) is made of synthetic resin and has an outer peripheral shape substantially along the cam surface (11) and an inner peripheral shape along the outer peripheral surface of the hollow shaft (3), and within the cam surface (11). It is press-fitted. A slight gap is provided between the cage (15) and the outer periphery of the hollow shaft (3). The cage (15) has a pocket for housing the roller (13) and the coil spring (14), and the pocket of the cage (15) has a spring receiving recess ( 17) is provided.

Grease is enclosed in the spring receiving recess (17) side of the pocket of the cage (15), and this grease has excellent meshing performance (particularly low-temperature meshing performance), for example, base oil is ester-based. The base oil kinematic viscosity is 90 mm ² / s-40 ° C. or higher, and the thickener is urea grease.

  In the one-way clutch (5), the diameter of the roller (13) is 4 mm or more (for example, 9 mm), the number of rollers (13) is 10 or less (for example, 6), and the wedge angle of the wedge-shaped space (12) ( The angle formed by the tangent point (13) at the contact position between the roller (13) and the inner ring (3) and the tangent line at the contact position of the outer ring (4) when in the biting state. ) Is 4-9 ° (for example, 6.5 °), and the biasing force of the coil spring (14) acting on the roller (13) in the set position (stop position when the inner and outer rings are not rotating) is 1 N or more (preferably 1 .5N-3N).

  The urging force of the coil spring (14) is designed in consideration of the following two expressions.

Energizing force required to move the roller to the meshing position during meshing> (roller weight + roller inertial force + roller vibration load + grease viscous force) (1)
Energizing force required for the separated roller to return to the set position>(roller's own weight + grease viscosity force + adhesion force) (2)
The mass of the roller is m, the acceleration is a, the angular acceleration is α, the roller PCD is r, and the roller weight is expressed in mg, the roller inertia force is mαr, and the roller vibration load is ma. The grease viscous force has a correlation with the consistency of grease, and in the grease of this embodiment, the viscous force is about 1.7 N. (Roller self-weight + Roller inertial force + Roller vibration load) is not so large. If this is ignored, from formula (1), the biasing force required to move the roller (13) to the meshing position during meshing is The condition that at least the grease viscosity is greater is obtained. Adhesion force is the force that the roller (13) sticks to the concave surface part (16) of the cam surface (11) .The type of grease, contact area between the roller (13) and cam surface (11), ambient temperature There is a correlation and can be obtained in advance. The adhesion force is, for example, about 1.0 N at −30 ° C. If the weight of the roller is ignored, Equation (2) shows that the biasing force required to move the roller (13) to the meshing position during meshing is at least greater than the sum of the grease viscous force and the adhesion force. It is done.

  The biasing force of the coil spring at the actual set position is set to a value that is slightly larger than the larger one of the values obtained from the equations (1) and (2) through detailed analysis.

  The pulley unit with a one-way clutch (1) is preferably used for a belt drive starter. In this case, the one-way clutch (5) operates as follows.

  First, at the time of starting, the hollow shaft (3) integrated with the rotation shaft (2) of the starter motor is rotated counterclockwise. As a result, the hollow shaft (3) of the one-way clutch (5) rotates counterclockwise, and the roller (13) is engaged with the narrow side of the wedge-shaped space (12) of the one-way clutch (5) to drive. The force is transmitted, and the hollow shaft (3) and the pulley (4) of the one-way clutch (5) rotate together (locked state). At this time, since the diameter of the roller (13) is 4 mm or more and the wedge angle of the wedge-shaped space (12) is 4 to 9 °, excellent engagement is exhibited even at a low temperature. The pulley (4) is connected to the crankshaft via a belt, and the engine is started by the rotation of the pulley (4). When the engine starts, the starter stops and the pulley (4) continues to rotate counterclockwise. As a result, the engagement of the roller (13) is released, and the state where only the pulley (4) rotates continues, and the roller (13) is on the wide side of the wedge-shaped space (12) when the engine rotates at high speed. It is received by the concave surface portion (16) and is brought into a non-contact state with the hollow shaft (3) (free state). Thus, when the pulley (4) reaches a predetermined rotational speed or higher, only the pulley (4) rotates, and energy loss due to rotation of a portion that does not contribute to driving of the engine can be suppressed. Thereafter, when the engine is stopped and restarted, the roller (13) needs to be positioned on the narrow side of the wedge-shaped space (12). However, the roller (13) in contact with the concave surface portion (16) on the wide side of the wedge-shaped space (12) does not leave the concave surface portion (16) due to the adhesive force on the contact surface and the viscous force of grease. There is a possibility, and in particular, there are concerns about meshing slip and delay under conditions where the starter is repeatedly turned on and off, such as in an idle stop vehicle. On the other hand, since the urging force of the coil spring (14) at the set position is 1 N or more, the roller (13) is surely positioned on the narrow side of the wedge-shaped space (12) when the engine is stopped. This prevents mesh slippage and delay.

  In the above embodiment, the outer ring of the one-way clutch (5) is integrated with the pulley (4), and the inner ring is integrated with the hollow shaft (3). May be a separate member from the pulley (4), and the inner ring may be a separate member from the hollow shaft (3). Further, although the coil spring (14) is shown as means for biasing the roller (13), a plate spring or the like can be used instead of the coil spring (14).

FIG. 1 is a longitudinal sectional view showing an embodiment of a one-way clutch according to the present invention. FIG. 2 is a partially enlarged view of the cross section of the pulley.

Explanation of symbols

(3) Hollow shaft (one-way clutch inner ring)
(4) Pulley (one-way clutch outer ring)
(5) One-way clutch
(11) Cam surface
(12) Wedge-shaped space
(13) Roll
(14) Coil spring (biasing member)
(15) Cage

Claims (2)

An inner ring, an outer ring, a plurality of rollers respectively disposed in a plurality of wedge-shaped spaces formed between the two wheels, a biasing member that biases each roller in the biting direction, and a cage that holds the plurality of rollers In the direction clutch,
The diameter of the roller is 4 mm or more, the number of rollers is 10 or less, the wedge angle of the wedge-shaped space is 4 to 9 °, and the urging force of the urging member at the set position is 1 N or more. Direction clutch.   The one-way clutch according to claim 1, wherein the urging force of the urging member at the set position is 1.5N to 3N.

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