JP2008082457A - One-way clutch with torque limiter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-way clutch with a torque limiter which prevents an engaging slippage causing breakage of the one-way clutch. <P>SOLUTION: A cross-sectional shape of a cam surface 16 is formed so as to be an arcuate surface taking as a center a position E deviated from the center of a one-way clutch having a radius R shorter than a distance from the center of the one-way clutch. By so doing, a wedge angle θ between a lock position and an unlocking recess 19 is set not wider than that of the lock position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a one-way clutch, and more particularly to a one-way clutch with a torque limiter that is configured to release a locked state when an overload is applied in the locked state.

  For example, in a pulley unit equipped in an auxiliary machine (for example, a compressor for an air conditioner) driven from a crankshaft of an automobile engine or the like by using a belt, the use of a one-way clutch causes fluctuations in belt tension. It is designed to absorb the rotational fluctuation of the pulley.

  A pulley unit (1) for a compressor for an automobile air conditioner shown in FIG. 3 is connected to a crankshaft of an automobile engine via a belt (4) to transmit the engine power to a rotating shaft (3) of the compressor (2). ), A pulley (5) around which a belt (4) is wound, and a hollow shaft arranged on the inner diameter side of the pulley (5) and fixed to the rotating shaft (3) of the compressor (2) (6), an inner ring (71), an outer ring (72), a plurality of balls (73) arranged in two rows, and a retainer (74) for holding these balls (73), and a pulley inner diameter and a hollow shaft Double-row rolling bearing (7) placed between the outer diameter and bottomed cylindrical hub (supporting member for one-way clutch outer ring) fixed to the end of the rotating shaft (3) by a cap nut (8) (9), the inner ring (75) integrated with the outer ring (72) of the rolling bearing (7), the outer ring (76), a plurality of rollers (77) disposed between the two rings (75) (76), each roller ( 77) and a biasing member (not shown) for biasing in the biting direction It has a cage (78) with a pocket to hold a number of rollers (77) and is arranged between the outer diameter of the outer ring (71) of the rolling bearing (7) and the inner diameter of the cylindrical part (9a) of the hub (9). And a one-way clutch (10).

  The outer ring (76) of the one-way clutch (10) is integrated with the rotating shaft (3) via the hub (9), and the inner ring (75) of the one-way clutch (10) is integrated with the pulley (5). Has been. Accordingly, when the pulley (5) is rotationally driven by the belt (4) and power is transmitted from the pulley (5) to the rotating shaft (3) of the compressor (2) via the one-way clutch (10). The one-way clutch (10) is locked when the rotational speed of the pulley (5) is relatively faster than the rotational shaft (3) of the compressor (2), and the pulley (4), hub (9 ) And the rotating shaft (3) are integrated and rotated synchronously, and when the rotational speed of the pulley (5) becomes relatively slower than the rotating shaft (3) of the compressor (2), it enters a free state. Then, the transmission of the rotational power from the pulley (5) to the rotating shaft (3) of the compressor (2) is cut off, so that the rotating shaft (3) continues to rotate only with the rotary inertia force.

  A general one-way clutch does not have a function of interrupting transmission of power from the belt to the rotating shaft of the compressor when an overload is applied. There is a problem of burning or damage. In order to solve this problem, although not shown in the drawings, in Patent Document 1, a recess into which the roller enters is formed in a region beyond the lock position on the cam surface. A one-way clutch with a torque limiter is proposed in which the roller is constrained to not act as a biting member, whereby the outer ring and the inner ring are in a free state, and the operation as a torque limiter that interrupts power transmission is obtained. ing.

In this one-way clutch with a torque limiter, for example, when an abnormality occurs in the rotation of the rotary shaft due to a burn-in failure of the compressor, the load torque of the one-way clutch increases, and this value becomes a required specified value (for example, 60 Nm). When it reaches, the roller is moved to the narrower side of the lock position in the wedge-shaped space and enters the concave portion of the cam surface, so that the roller is not in contact with the pulley or idles, so that only the pulley rotates. Thus, the function of a torque limiter that cuts off power transmission from the pulley to the rotating shaft of the compressor is achieved.
JP 2002-106608 A

  According to the one-way clutch with a torque limiter disclosed in Patent Document 1, when the roller is overloaded, the roller enters the concave portion, so that the locked state is eliminated, thereby interrupting the transmission of power from the belt to the rotating shaft of the compressor. As a result, the problem of belt burn-in or breakage is solved, but the following problems exist in order to ensure a more reliable power shut-off state. That is, when the roller enters the recess, slipping (meshing slip) may occur due to a decrease in the coefficient of friction, and the one-way clutch may be damaged by popping, so it is necessary to prevent the meshing slip.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a one-way clutch with a torque limiter that prevents a meshing slip that causes the one-way clutch to be damaged.

  A one-way clutch with a torque limiter according to the present invention includes a plurality of rollers disposed between an outer ring, an inner ring, and both races, a biasing member that biases each roller in a biting direction, and a holding pocket that holds each roller. A cam surface that defines the lock position and the free position is formed on one of the outer ring and the inner ring, and an overload is applied to the region beyond the lock position on the cam surface. In a one-way clutch with a torque limiter that is formed with an unlocking recess where the roller sometimes enters, the wedge angle between the locking position and the unlocking recess is less than the wedge angle of the locking position. It is formed so that it may become.

  The wedge angle is an angle formed by tangent lines between the rollers and the inner and outer ring raceways. Between the locking position and the recess for unlocking, the wedge angle may be constant or may change as the roller revolves. In any case, the size is the size of the wedge angle at the locking position. Is kept below.

  As the wedge angle increases, the normal force decreases accordingly, the frictional force decreases, and the possibility of causing slip (meshing slip) increases. The condition where the meshing slip does not occur is that tan (θ / 2) <μ, where μ is the friction coefficient and θ is the wedge angle, and this condition has been secured in the locked position from the past. By making the size of the wedge angle between the two is less than the size of the wedge angle at the lock position, it is possible to reliably prevent the meshing slip at the time of operating the torque limiter.

  In the case of an inner ring cam having an inner ring formed in a polygonal shape, if a recess for unlocking is formed in a region beyond the lock position on the polygonal cam surface, the wedge angle between the lock position and the recess for unlocking is increased. This increases the possibility of meshing slippage. In order to prevent this, for example, the wedge angle may be reduced by changing the cross-sectional shape near the recess for unlocking from a straight line to a curved line. At this time, the cam surface may be formed into an eccentric R cam shape (the cross-sectional shape of each cam surface is formed by an arc centered at a position shifted from the center of the one-way clutch), and this increases the wedge angle. Can be reduced.

  This one-way clutch includes, for example, a pulley around which a belt is wound, a rotating shaft arranged on the inner diameter side of the pulley, a rolling bearing arranged between the inner diameter of the pulley and the outer diameter of the rotating shaft, and a rolling bearing. It is suitably used as a one-way clutch in a pulley unit (power transmission device) having a one-way clutch disposed between an outer ring and a cylindrical hub inner diameter fixed to a rotating shaft. Such a pulley unit can be used in an auxiliary machine such as a compressor for an air conditioner of an automobile and other various devices.

  The outer ring, inner ring and rollers of the one-way clutch are made of metal, and the cage is made of synthetic resin. The biasing member is, for example, a coil spring, but is not limited thereto. The urging member is positioned and held by an urging member holding portion having a protrusion or a recess provided on the cage, and is held between the urging member holding portion. The cam surface may be formed on the inner ring or may be formed on the outer ring.

  According to the one-way clutch with a torque limiter of the present invention, the wedge angle between the lock position and the unlocking recess that is not used at the time of transition between the normal locked state and the free state is the wedge angle of the locked position. By making it smaller than the size, it is possible to prevent the meshing slip that causes the one-way clutch to be damaged.

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

  1 and 2 (a) show an embodiment of a one-way clutch with a torque limiter according to the present invention.

  This one-way clutch (10) is used as the one-way clutch (10) shown in FIG. 3, and is formed into a cylindrical outer ring (11) and a polygonal shape. Is disposed in a wedge-shaped space (17) formed by the cam ring (16) defining the inner ring (12), the cam surface (16) and the inner peripheral surface of the outer ring (11), and the outer ring (11) When the inner ring (12) rotates relative to one direction (locking direction), the outer ring (11) engages with the inner ring (12), and when it rotates relative to the other direction (free direction) A roller (13) as a plurality of biting members to be released, a coil spring (15) as a biasing member for biasing the roller (13) in the biting direction (narrow side of the wedge-shaped space (17)), (13) and a pocket (18) for accommodating the coil spring (15), and an annular cage (14) for positioning the roller (13) in the wedge-shaped space (17).

  The cam surface (16) is formed by the outer peripheral surface of the inner ring (12) having an eccentric R cam shape with a circular arc cross section, and a counterclockwise side portion of each surface (side in the cross section) and the outer ring ( 11) A space between the inner peripheral surface and the wedge-shaped space (17) is used. As shown in detail in FIG. 2 (a), the eccentric R cam shape has a one-way clutch (10) with the cross-sectional shape of the cam surface (16) centered at a position E that is eccentric from the center of the one-way clutch (10). ) Is formed as a circular arc surface having a radius R smaller than the distance from the center. Since the radius R is smaller than the distance from the center of the one-way clutch (10), the retainer (14) is in a direction opposite to the roller (13) revolution direction in the overload state (clockwise in FIG. 1). ) Cannot be rotated. Note that the cross-sectional shape of the cam surface (16) is not entirely circular, but the arc from the free or locked position of the roller (13) to the unlocking recess (19). The direction side may be a straight line (a part of a polygon).

  On the narrow side of the wedge-shaped space (17), that is, in the locked position, in order to prevent meshing and slipping, the wedge angle (tangent point at the contact position between the roller (13) and the inner ring (12) when engaged) (13 ) And the tangent line at the contact position of the outer ring (11)) θ is set so that tan (θ / 2) <μ holds, where the friction coefficient is μ. By making the cam surface (16) into an eccentric R cam shape, the wedge angle between the lock position and the unlocking recess (19) is made smaller than the wedge angle at the lock position. Thus, tan (θ / 2) <μ, which is a condition for preventing meshing slippage, is also established between the locked position and the unlocking recess (19).

  The inner ring (12) is formed with a lock release recess (19) in which the roller (13) enters when overloaded, in a region beyond the lock position on the cam surface (16).

  According to this one-way clutch (10), when the rotational speed of the outer ring (11) is relatively higher than that of the inner ring (12), the roller (13) moves to the narrow side of the wedge-shaped space (17) (counterclockwise in the figure). The outer ring (11) and the inner ring (12) are integrated and rotate synchronously. However, when the rotation speed of the outer ring (11) becomes relatively slower than the inner ring (12), the roller (13) is rolled to the wide side (clockwise in the figure) of the wedge-shaped space (17) and is free. Therefore, transmission of rotational power from the outer ring (11) to the inner ring (12) is interrupted, and the inner ring (12) continues to rotate only with the rotational inertia force.

  When a large torque load is applied, the roller (13) is forcibly moved in a narrower direction of the wedge-shaped space (17) while being engaged between the inner ring (12) and the outer ring (11). When the roller (13) further moves counterclockwise and the roller (13) fits into the unlocking recess (19), the inner ring (12) and the outer ring (11) are in a free state.

  In the case of the conventional one-way clutch with a torque limiter shown in FIG. 2B, when the torque is applied and the roller (77) moves, the wedge angle θ increases, and the unlocking recess (79) Before reaching tan (θ / 2)> μ, there is a possibility of meshing slippage. On the other hand, according to the one-way clutch (10) with a torque limiter according to the present invention, as described above, μ> tan (θ / 2) is secured for the wedge angle θ until the torque limiter is actuated. Is reliably prevented.

  Therefore, according to this pulley unit for a compressor, for example, if an abnormality occurs in the rotation of the rotating shaft (3) due to a seizure failure of the compressor (2), the load torque of the one-way clutch (10) increases, and this When the value reaches the required specified value (for example 60 Nm), the roller (13) is moved to the narrower side (counterclockwise in the figure) of the locking position in the wedge-shaped space (17). Without being generated, the cam surface (16) enters the unlocking recess (19). As a result, the rollers (13) cannot be engaged between the two wheels (11) and (12), and the power transmission from the pulley (5) to the rotating shaft (3) of the compressor (2) is cut off. The function of the torque limiter is fulfilled. As a result, even when an overload is applied, the one-way clutch (10) is prevented from being damaged due to the meshing slip, and after that, the pulley (5) continues to rotate and causes a rotation loss of the crankshaft. The belt (4) does not slip on the pulley (5) and the life of the belt (4) is improved, and the devices connected through the compressor (2) and the belt (4) are not adversely affected. .

  In the above embodiment, the one-way clutch (10) has been described as a compressor pulley unit for an air conditioner of an automobile. However, the use of the one-way clutch is not limited to this. In addition, the one-way clutch (10) has a cam surface (16) formed on the inner ring (12). However, the above-described configuration of the wedge angle has a cam surface formed on the outer ring. The same applies to a one-way clutch.

FIG. 1 is a cross-sectional view showing an embodiment of a one-way clutch with a torque limiter according to the present invention. FIG. 2 (a) is a diagram for explaining the wedge angle on the cam surface of the one-way clutch with torque limiter according to the present invention, and FIG. 2 (b) shows the wedge angle on the cam surface of the conventional one-way clutch with torque limiter. It is a figure explaining. FIG. 3 is a cross-sectional view showing a pulley unit for a compressor as an example in which the one-way clutch according to the present invention is used.

Explanation of symbols

(10) One-way clutch
(11) Outer ring
(12) Inner ring
(13) Roll
(14) Cage
(15) Coil spring (biasing member)
(16) Cam surface
(18) Pocket
(19) Unlock recess

Claims (1)

A plurality of rollers arranged between the outer ring, the inner ring, and both race rings, a biasing member that biases each roller in the biting direction, and a retainer having a pocket that holds each roller; A cam surface that defines the lock position and free position is formed on one of the raceways, and a lock release recess is formed in the region beyond the lock position on the cam surface. In the one-way clutch with a torque limiter,
A one-way clutch with a torque limiter, wherein the wedge angle between the lock position and the unlocking recess is formed so that the size thereof is equal to or less than the size of the wedge angle at the lock position.

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