JP2006097710A - One-way clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-way clutch capable of making meshing property compatible with high allowable torque property and solving a problem of short service life caused by it. <P>SOLUTION: As for a plurality of wedge-like spaces 12A, 12B, its wedge angle has two kinds, and comparatively large wedge angle 12A and comparatively small wedge angle 12B are alternately arranged every one another. Energizing force that a roller 13A in the wedge-like space 12A having large wedge angle receives>energizing force that a roller 13B in the wedge-like space 12B having small wedge angle receives. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a one-way clutch suitable for use in, for example, a belt drive starter or an alternator 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).
JP2003-156075A

  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.

  If the wedge angle of the wedge-shaped space is large, it is advantageous for the allowable torque, and if it is small, it is advantageous for the meshing property.Therefore, the wedge angle of some wedge-shaped spaces is changed to balance the allowable torque and the meshing property. It is possible to take. However, if it does in this way, the burden of the roller arrange | positioned in the wedge-shaped space with a small wedge angle will become large, and we are anxious about lifetime reducing.

  An object of the present invention is to provide a one-way clutch in which the meshing property and the high permissible torque are made compatible and the problem of short life that can occur with this is solved.

  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 the one-way clutch provided with a retainer for holding, at least one of the plurality of wedge-shaped spaces has a wedge angle different in size from the wedge angle of the other wedge-shaped spaces, and has a wedge shape with a large wedge angle. The biasing force received by the rollers in the space is greater than the biasing force received by the rollers in the wedge-shaped space with a small wedge angle.

  The wedge angle means an angle θ formed by the tangent line between the roller and the inner ring and the tangent line with the outer ring when in the engaged state (see FIG. 3). The wedge angle is the same for all rollers, and the inclination angle from the normal direction of the cam surface (either the inner peripheral surface of the outer ring cam or the outer peripheral surface of the inner ring cam) is set to the required value. , Can be set to a predetermined value.

  The wedge angle may be two kinds of large and small sizes, but may be three kinds of large, medium and small sizes. It is preferable that there are two types of wedge angles, and one having a relatively large wedge angle and one having a relatively small wedge angle are arranged alternately. The small wedge angle is a size that can be surely meshed under given conditions, and the large wedge angle is about 1 to 2 ° larger than this (for example, 8 ° or less).

  When the biasing force received by the rollers in the wedge-shaped space having a large wedge angle is greater than the biasing force received by the rollers in the wedge-shaped space having a small wedge angle, the biasing force should be such that all the rollers are released at substantially the same rotational speed. It is preferably set.

  When only the wedge angle is changed with the same urging force applied to the roller, in the one-way clutch for starter, when the starter motor is started, the roller in the wedge-shaped space with the small wedge angle is the roller in the wedge-shaped space with the large wedge angle. Engage first, and then the rollers in the wedge-shaped space with a large wedge angle mesh with each other as the rotational speed increases. When the rotational speed is further increased and the free state is entered, the rollers in the wedge-shaped space having a large wedge angle are first removed, and finally the rollers in the wedge-shaped space having a small wedge angle are separated. In other words, the rollers in the wedge-shaped space having different wedge angles are separated at different rotational speeds. Under conditions where the starter is repeatedly turned on and off, such as in an idle stop vehicle, the rollers in the wedge-shaped space with a small wedge angle engage with each other first and finally disengage. There is concern that the product will have a short life due to wear. In the one-way clutch for an alternator, when there is a slight rotational fluctuation in the vicinity of the number of revolutions that shift from the meshed state to the released state, the rollers in the wedge-shaped space with a small wedge angle have a width of the wedge-shaped space with a large wedge angle. In a state where the rollers are disengaged, the meshing and disengagement are repeated, and there is a concern that the load is concentrated and the life is shortened similarly to the starter.

  On the other hand, in the above-described one-way clutch according to the present invention, the biasing force received by the roller in the wedge-shaped space having a large wedge angle is greater than the biasing force received by the roller in the wedge-shaped space having a small wedge angle. A roller with a wedge-shaped space with a high wedge angle has improved releasability with respect to the biasing force, and conversely, a roller with a wedge-shaped space with a low wedge angle with low meshing property has reduced releasability with respect to the biasing force. Thus, all the rollers are separated at the same or substantially the same rotational speed, and this makes it difficult for the life of the rollers to be unbalanced, and ensures a long life as a whole.

  To change the biasing force that the roller receives, the spring constant of the coil spring as the biasing member may be changed (the free length of the coil spring in this case is the same), and the spring constant as the biasing member should not be changed. The length of the coil spring may be changed without changing (the spring constant in this case is the same, and the roller setting position is constant regardless of the spring length because it is determined by the cam surface dimensions and the diameter of the rotating shaft) The same coil spring may be used, and the roller setting position (the position of the roller when the inner and outer rings are not rotating) may be changed by changing the cam surface dimension.

  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 to the narrow side of the ring-shaped space, and a cage for positioning the roller in the wedge-shaped space (outer ring cam type), and the outer peripheral surface of the inner ring Is disposed in a wedge-shaped space formed by the cam surface and the inner peripheral surface of the outer ring, and the inner ring and the outer ring rotate relative to each other in one direction so that the inner ring and the outer ring are positioned between each other. Bite and bite when rotated relative to other direction A roller as a plurality of biting members for releasing jamming, and a coil spring as a biasing member for biasing the rollers in the biting direction (narrow side of the wedge-shaped space) (inner ring cam type) is there.

  This one-way clutch is suitable for use as an starter for an idle stop vehicle, for example, as an outer ring cam type. Further, it is suitable for use as an alternator as an outer ring cam type. 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 time is short and low speed rotation, but for any use, the biasing force received by the rollers in the wedge-shaped space with a large wedge angle> wedge with a small wedge angle By using the urging force received by the rollers in the space, the meshing property and the high permissible torque are compatible while the life is secured.

  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, since at least one of the plurality of wedge-shaped spaces has a wedge angle different in size from the wedge angle of the other wedge-shaped spaces, the value of the smaller wedge angle is given. Ensuring that the size of meshing is ensured under the specified conditions, it is possible to achieve both a high level of meshing and high permissible torque, and the biasing force received by the rollers in the wedge-shaped space with a large wedge angle is greater than the wedge angle. Since it is set as the urging | biasing force which the roller of a wedge-shaped space receives, the burden to the roller of the higher meshing property is reduced, and it is prevented that it becomes short life.

  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 to 3 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). A roller bearing (6) and a ball bearing (7) are provided between the one-way clutch (5). 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) is arranged in the plurality of wedge-shaped spaces (12A) and (12B), and the hollow shaft (3) and the pulley (4) are rotated relative to each other in one direction (locking direction). Rollers (13A) (13B) and rollers (13A) (13B) as a plurality of biting members that get caught between pulleys (4) and release when they rotate relative to the other direction (free direction) ) In the biting direction (narrow side of the wedge-shaped space (12A) (12B)) and the coil springs (14A) (14B) as the biasing member and the rollers (13A) (13B) 12A) and a cage (15) positioned in 12B.

  The cam surface (11) is configured by providing a plurality of sets (four sets in this embodiment) in the circumferential direction with two surfaces (11a), (11b), (11c), and (11d) facing each other across the axis. . 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. At the wide end of the wedge-shaped space (12A) (12B) of the opposing two surfaces (11a), (11b), (11c), and (11d) of the cam, a roller (13A ) (13B) is provided with a concave surface portion (16).

  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 (15a) for storing the rollers (13A) (13B) and the coil springs (14A) (14B), and the pocket (15a) of the cage (15) has a coil A spring receiving recess (17) for positioning the springs (14A) (14B) is provided. Grease is sealed in the spring receiving recess (17) side of the pocket (15a) of the cage (15).

  In FIG. 2, for a plurality (eight illustrated) wedge-shaped spaces (12A) and (12B), there are two types of wedge angles, and those having a relatively large wedge angle (12A) and relative wedge angles. The small ones (12B) are arranged every other. That is, the inclination angle of the two opposite two surfaces (11b) and (11d) of the cam is made smaller than the inclination angle of the other two opposite two surfaces (11a) and (11c) of the cam. The wedge angle of the wedge-shaped space (12B) formed by the cam surface represented by 11d) is made small. Correspondingly, the coil springs (14A) and (14B) have the same free length and the spring constant has been changed, and the biasing force received by the rollers in the wedge-shaped space (12A) with a large wedge angle> wedge angle It is considered as the biasing force received by the rollers in the small wedge-shaped space (12B). The rollers (13A) and (13B) that are arranged in any of the wedge-shaped spaces (12A) and (12B) have the same shape and the same size.

  As schematically shown in FIG. 3, the wedge angle θ is determined by the tangent points (13A) (13B) between the rollers (13A) (13B) and the inner ring (3) and the outer ring (not shown) The wedge angle θ can be set to a predetermined value by setting the inclination angle from the normal direction of the cam surface (11) to a required value. In FIG. 3, N = F × μ and μ = tan (θ / 2) and the wedge-shaped space roller (13B) with a small wedge angle is a wedge-shaped roller (13A) with a large wedge angle. As a result, the meshing property is improved, and as a result, the allowable torque contradicting the meshing property is reduced. As shown in FIG. 2, the biasing force received by the rollers in the wedge-shaped space (12A) having a large wedge angle (the spring constant of the coil spring (14A) arranged in the wedge-shaped space (12A) having a large wedge angle) > Engagement due to the biasing force received by the rollers in the wedge-shaped space (12B) with a small wedge angle (the spring constant of the coil spring (14B) arranged in the wedge-shaped space (12B) with a small wedge angle) The roller (13B) in the wedge-shaped space (12B) with a high wedge angle is improved in detachment with respect to the urging force, and conversely, the roller in the wedge-shaped space (12A) with a large wedge angle (12A) with low meshing properties ( In the case of 13A), with respect to the urging force, the detachability is suppressed, and all the rollers (13A) and (13B) are separated at the same or substantially the same rotational speed.

  For example, in the case of a one-way clutch for a starter, the small wedge angle is set to a size (for example, 6.5 ° or less) that reliably engages under a given condition (for example, −30 ° C.). ˜2 ° larger (for example, 8 ° or less).

  The pulley unit (1) with a one-way clutch is preferably used for a belt drive starter and an alternator.

  When used in a belt drive starter, 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 wedge-shaped space (12A (12B) of the one-way clutch (5) has rollers (13A) (13B) on the narrow side. The hollow shaft (3) and the pulley (4) of the one-way clutch (5) rotate as a unit (locked state) by being engaged and driven, and the pulley (4) passes through the belt. Connected to the crankshaft, the engine is started by the rotation of the pulley (4) When the engine is started, the starter stops and the pulley (4) continues to rotate counterclockwise, so that the rollers (13A) (13B) is released from engagement and only the pulley (4) continues to rotate. When the engine rotates at high speed, the rollers (13A) and (13B) are not in contact with the hollow shaft (3) ( In this way, if the pulley (4) exceeds the specified rotational speed, only the pulley (4) will rotate, contributing to the engine drive. You can have portions can be suppressed energy loss caused to rotate.

  When only the wedge angle is changed with the urging force applied to the rollers (13A) and (13B) being the same, in the one-way clutch for the starter, when the starter motor starts, the rollers in the wedge-shaped space (12B) with a small wedge angle ( 13B) meshes before the roller (13A) in the wedge-shaped space (12A) with a large wedge angle, and then the roller (13A) in the wedge-shaped space (12A) with a large wedge angle meshes as the rotational speed increases. When the rotational speed is further increased and the free state is entered, the roller (13A) in the wedge-shaped space (12A) with a large wedge angle is smaller than the roller (13B) in the wedge-shaped space (12B) with a small wedge angle. First, the rollers (13B) in the wedge-shaped space (12B) with a small wedge angle are separated. That is, the rollers (13A) and (13B) in the wedge-shaped spaces (12A) and (12B) having different wedge angles are separated at different rotational speeds. Under conditions where the starter is repeatedly turned on and off, such as in an idle stop vehicle, the roller (13B) in the wedge-shaped space (12B) with a small wedge angle engages first and finally disengages, so the load due to engagement There is a concern that the wear may be shortened due to intensive load due to wear due to sliding with the inner ring.

  In contrast, in the one-way clutch (5), the biasing force received by the roller (13A) in the wedge-shaped space (12A) having a large wedge angle> the roller (13B) in the wedge-shaped space (12B) having a small wedge angle is provided. Since the urging force is applied, all the rollers (13A) and (13B) are separated at the same or substantially the same rotational speed, and thus there is no life imbalance, so that a long life is ensured as a whole.

  When used in an alternator, the one-way clutch (5) operates as follows.

  Also in the alternator, the one-way clutch switches between the free state and the locked state according to the rotational difference between the pulley (4) and the rotating shaft (rotor shaft) (2), and from the pulley (4) to the rotating shaft (2). Rotational power is transmitted or cut off. In an alternator not provided with a one-way clutch, the pulley is rotationally driven via a belt by the crankshaft of the engine. Therefore, if the rotation speed of the crankshaft decreases, the power generation efficiency of the alternator decreases. By using a pulley unit with a clutch, when the rotational speed of the pulley (4) decreases, the one-way clutch functions so that the rotational speed of the rotating shaft (2) is maintained at a high frequency by its own inertial force. Can contribute to the improvement of power generation efficiency. In addition, when power is transmitted via a belt to a crankshaft with a large rotational fluctuation due to the engine operation process, a pulley and an alternator pulley with a large inertial force, and the shaft through the belt, slippage occurs between the belt and the pulley. Although abnormal noise becomes a problem, rotational fluctuation can be absorbed by switching the free or locked state of the one-way clutch (5) between the pulley (4) of the alternator and the rotating shaft (2).

  When only the wedge angle is changed with the same urging force applied to the rollers (13A) and (13B), the one-way clutch for the alternator has a slight rotational fluctuation in the vicinity of the rotational speed at which it shifts from the meshed state to the released state. In this case, the roller (13B) in the wedge-shaped space (12B) with a small wedge angle repeatedly engages and disengages while the roller (13A) in the wedge-shaped space (12A) with a large wedge angle remains disengaged. In addition, there is a concern that the load will be concentrated and the service life may be shortened. In contrast, in the one-way clutch (5), the biasing force received by the roller (13A) in the wedge-shaped space (12A) having a large wedge angle> the roller (13B) in the wedge-shaped space (12B) having a small wedge angle is provided. The roller (13B) in the wedge-shaped space (12B) with a small wedge angle with a high meshing property is improved in terms of urging force. The roller (13A) in the wedge-shaped space (12A) will have reduced releasability with respect to the urging force, and when used for an alternator, all rollers (13A) (13B) Since they are disengaged at the same or substantially the same number of revolutions and there is no life imbalance, a long life is ensured as a whole.

FIG. 1 is a longitudinal sectional view showing an embodiment of a one-way clutch according to the present invention. FIG. 2 is a cross-sectional view of the pulley. FIG. 3 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
(12A) (12B) Wedge-shaped space
(13A) (13B) Roller
(14A) (14B) Coil spring (biasing member)
(15) Cage

Claims (4)

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,
At least one of the plurality of wedge-shaped spaces has a wedge angle having a size different from the wedge angle of the other wedge-shaped spaces, and the biasing force received by the rollers in the wedge-shaped space having a large wedge angle is larger than the wedge angle. A one-way clutch characterized in that it is a biasing force received by a roller in a wedge-shaped space.   The one-way clutch according to claim 1, wherein the biasing force received by the roller is changed by changing a spring constant of the biasing member.   The one-way clutch according to claim 1, wherein the biasing force received by the roller is changed by changing a length of a coil spring as a biasing member.   The one-way clutch according to claim 1, wherein the urging force received by the roller is changed by changing a position of the roller when the inner and outer rings are not rotated.

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