WO2010061805A1

WO2010061805A1 - Pulley unit

Info

Publication number: WO2010061805A1
Application number: PCT/JP2009/069763
Authority: WO
Inventors: 智昭牧野
Original assignee: Ntn株式会社
Priority date: 2008-11-27
Filing date: 2009-11-24
Publication date: 2010-06-03

Abstract

Decreased durability is suppressed in a bearing that is between a pulley and a pulley hub and that supports those components so as to freely rotate relative to one another. A pulley (1) and a pulley hub (3), which is assembled on the inside thereof, are supported by a bearing (4) so as to freely rotate relative to one another; a flange (7) and a stop ring (8) are provided on the outer diameter surface of the pulley hub (3); and a female threaded member (10),the rotation of which is prevented relative to the pulley (1), and the outward axial movement of which is prevented by the stop ring (8), and a male threaded member (9), which is supported so as to rotate and move axially relative to the pulley hub (3), and which forms a ball screw together with the female threaded member (10), are assembled between the flange (7) and the stop ring (8). A friction plate (17), the rotation of which is prevented relative to the pulley hub (3), and which forms a friction clutch between that and the male threaded member (9), and an elastic member (20), which forces the friction plate (17) toward the male threaded member (9), are assembled between the male threaded member (9) and the flange (7) such that the compression force of the elastic member (20) is received by the flange (7) and the stop ring (8), and the compression force is not exerted on the bearing (4).

Description

Pulley unit

The present invention relates to a pulley unit that is used by being attached to a rotating shaft of an engine auxiliary machine such as an alternator using an engine as a drive source.

Generally, the rotation of the crankshaft of the engine is transmitted to the rotation shaft of an engine accessory such as an alternator via a belt transmission.

In such an engine accessory drive device, when the engine is suddenly decelerated, the pulley attached to the rotating shaft of the engine accessory also tries to decelerate suddenly. At this time, when the engine accessory is an alternator, the rotating shaft of the alternator has a large inertia force, so the pulley attached to the rotating shaft tries to keep rotating at a constant speed, and the pulley on the crankshaft and the alternator rotate. A large rotational speed difference is generated between the pulleys on the shaft, and the belt tension is increased and the belt is easily damaged.

Also, the crankshaft varies in angular speed during one rotation under the influence of intermittent combustion in the cylinder and inertial force of the reciprocating piston, and the crankshaft is caused by the fluctuation of the angular speed. A slip occurs between the pulley and the belt, and the belt wears due to the slip and the durability is lowered.

In order to solve this problem, a clutch built-in pulley in which a roller type one-way clutch is incorporated in a pulley provided on a rotating shaft of an engine accessory has been proposed (for example, see Patent Document 1).

JP 2003-232433 A

By mounting this pulley with built-in clutch on the rotating shaft of the engine accessory, if the rotating speed of the pulley is lower than the rotating speed of the rotating shaft of the engine accessory, the one-way clutch is disengaged and the pulley is free. Since it rotates, an increase in belt tension is prevented, and a decrease in belt durability can be suppressed.

In the pulley with a built-in clutch described in Patent Document 1, when the one-way clutch switches from the unlocked state to the locked state, the roller suddenly engages the opposing surfaces of the inner ring and the outer ring, so that fluctuations in the rotation speed of the pulley are effective. Therefore, there is room for improvement in reducing the belt tension.

In order to solve this problem, a power transmission device described in Patent Document 2 that can effectively absorb fluctuations in the rotational speed of the pulley has been proposed. This power transmission device is prevented from rotating with respect to the pulley between the pulley and the rotor shaft, and can move in the axial direction, and can rotate with respect to the rotor shaft and move in the axial direction. And the second annular race is incorporated, and the first annular race is biased toward the second annular race by the pressing of the coil spring, and on the back side of the second annular race (opposite to the first annular race). A friction clutch that clutches the second annular race and the rotor shaft by pressing the coil spring is provided.

When the rotational speed of the pulley changes, the first annular race is separated from the second annular race by the cam action of the arcuate inclined surface formed on the opposing surfaces of the first annular race and the second annular race. The rotational speed is absorbed by the movement of the first annular race in the axial direction and the compression of the coil spring.
JP 2006-38183 A

The power transmission device described in Patent Document 1 has a configuration in which the second annular race and the friction clutch are positioned in the axial direction by a rolling bearing that supports a pulley and a rotor shaft so as to be relatively rotatable, and a coil spring is formed by the rolling bearing. And a reaction force of the axial force applied to the first annular race by the cam action of the arcuate inclined surface. As a result, there is a problem that the durability of the rolling bearing is lowered.

Therefore, an object of the present invention is to suppress a decrease in durability of a bearing that supports these members so as to be relatively rotatable between a pulley and a pulley hub.

In order to solve the above-mentioned problems, the present invention supports a pulley and a pulley hub incorporated inside the pulley so as to be relatively rotatable by a bearing incorporated between one end portions of both the members. Two projecting portions are provided on the outer diameter surface or the inner diameter surface of the pulley at an interval in the axial direction, and a male screw member and a female screw member that are screw-engaged with each other are incorporated between the two projecting portions. One of the screw members is prevented from rotating around one of the pulley or the pulley hub, and the one projecting portion prevents movement outward in the axial direction, and the other screw member is the other of the pulley or the pulley hub. The pulley or the pulley hub is supported between the other screw member and the other protrusion so as to be rotatable with respect to the shaft and movable in the axial direction. A friction plate that is prevented from rotating and that is movable in the axial direction to form a friction clutch with the other screw member, and an elastic member that urges the friction plate toward the one projecting portion are incorporated, and When the pulley rotates relative to the pulley hub in one direction, the other screw member rotates relative to the one screw member in one direction, and axially moves toward the other protrusion with the friction plate. When the friction plate is moved, the elastic member is pushed by the friction plate to be elastically deformed so that the friction clutch is engaged, and the rotation of the pulley is transmitted to the pulley hub. Was adopted.

In the pulley unit configured as described above, in a state where torque is not applied to the pulley and the pulley hub, that is, in a state where the pulley is stopped, the friction plate is pressed against the other screw member by the biasing force of the elastic member. A small pressing force is acting.

When a rotational torque in the forward rotation direction is input to the pulley while the pressing force is applied to the friction plate, that is, when the pulley rotates relative to the pulley hub in one direction, the other screw member is applied to one screw member. Rotate relative to one direction. Since the female screw member and the male screw member are screw-engaged with each other, the relative rotation of the female screw member moves the other screw member toward the other projecting portion with respect to the one screw member, and the friction plate also has the other screw member. The elastic member is elastically deformed by moving together.

Due to the elastic deformation of the elastic member, the friction plate is strongly pressed against the other screw member, and the friction clutch is engaged. Further, since the screw portion of the other screw member against which the friction plate is pressed presses the screw portion of the one screw member, the friction resistance between the screw portions of both screw members increases.

¡By increasing the frictional resistance, the rotation of the pulley is transmitted to the pulley hub via the friction plate, and the pulley hub rotates in the same direction as the pulley.

In the state of transmission of rotation from the pulley to the pulley hub, when the rotational speed fluctuates in the pulley, one screw member and the other screw member rotate relative to each other, and the other screw member moves in the axial direction with respect to the one screw member. Thus, the amount of elastic deformation in the axial direction of the elastic member due to pressing from the friction plate varies. Due to the variation in the amount of elastic deformation, the variation in the rotational speed of the pulley is absorbed, the transmission of the rotational variation of the pulley to the pulley hub is prevented, and the friction clutch is maintained in the coupled state.

When the pulley stops, the pulley hub tries to continue to rotate due to the inertial force, and the rotation of the pulley hub causes the friction plate to rotate, and the other screw member and one screw member that are clutch-coupled with the friction plate move in the other direction. Relative rotation occurs, and the other screw member moves to one projecting portion side. By the movement, the friction plate is also moved, the elastic member is extended, and the pressing force to the other screw member by the friction plate is lowered. As a result, the coupled state of the friction clutch is released, slip occurs at the contact portion between the friction plate and the other screw member, and the pulley hub continues to rotate due to the inertial force.

As described above, when the rotational fluctuation occurs in the pulley, the elastic member elastically deforms to absorb the rotational fluctuation of the pulley, and when the pulley stops, slippage occurs at the contact portion between the other screw member and the friction plate. The pulley hub continues to rotate due to the inertial force. For this reason, it is possible to prevent the belt tension from abruptly increasing or slipping between the pulley and the belt.

In addition, according to this configuration, the pulley and the pulley hub are configured to receive the pressing force of the elastic member that presses the friction plate against the other screw member by the two protruding portions formed on the outer diameter surface of the pulley hub or the inner diameter surface of the pulley. The bearing is supported so as to be relatively rotatable, and the pressing force is not applied to the bearing, so that a decrease in the durability of the bearing can be suppressed.

In the above configuration, the configuration of the two protrusions with respect to the outer diameter surface of the pulley hub or the inner diameter surface of the pulley, and one screw member of the two screw members when the pulley rotates relative to the pulley hub in one direction. However, the following can be adopted as a specific configuration that rotates relative to the other screw member in one direction.
That is, the two protrusions are provided on the outer diameter surface of the pulley hub at an axial interval, and are prevented from rotating by the pulley between the two protrusions. The female screw member that is prevented from moving to the pulley hub and the male screw member that is supported so as to be rotatable and axially movable with respect to the pulley hub are incorporated, and between the male screw member and the other protruding portion. A configuration in which the friction plate that is prevented from rotating with respect to the pulley hub and the elastic member are incorporated can be employed.

In this configuration, a stopper is provided on the outer diameter surface of the pulley hub to restrict the axial movement amount of the male screw member within the range of the maximum axial movement amount of the male screw member that is moved by the screw portion of the female screw portion. Then, excessive bending of the elastic member due to the male screw member moving in the axial direction more than necessary can be prevented, and a decrease in durability of the elastic member can be suppressed.

It is possible to employ a configuration in which a second friction plate is provided between the female screw member and the one protruding portion, and the second friction plate is prevented from rotating with respect to the pulley hub. In this case, since the transmission torque from the pulley is transmitted to the pulley hub by each of the two friction plates, the transmission torque per friction plate is reduced, and the friction plates are prevented from being worn. Or generation | occurrence | production of image sticking is prevented.

Further, in order to receive a larger radial load applied to the pulley, a configuration in which a radial bearing is incorporated between the inner diameter surface of the male screw member and the outer diameter surface of the pulley hub, or the one projecting portion and the female screw member It is possible to adopt a configuration in which a bearing holding member is provided between the opposite surfaces of the bearing holding member, and a radial bearing is incorporated between the radial outer surface of the bearing holding member and the inner diameter surface of the pulley.

In the above configuration, when the two protrusions rotate relative to the outer diameter surface of the pulley hub or the inner diameter surface of the pulley, and when the pulley rotates relative to the pulley hub in one direction, one of the two screw members. The following can be adopted as a specific configuration in which the screw member rotates relative to the other screw member in one direction.
That is, the two projecting portions are provided on the inner diameter surface of the pulley with an axial interval, and between the two projecting portions, the pulley hub is prevented from rotating, and the one projecting portion is axially outward. Incorporating the male screw member that is prevented from moving and the female screw member supported so as to be rotatable and axially movable with respect to the pulley, between the female screw member and the other protrusion, A configuration incorporating the friction plate that is prevented from rotating with respect to the pulley and the elastic member may be employed.

Further, when a stopper for restricting the axial movement amount of the female screw member within the range of the axial maximum movement amount of the female screw member moved by the screw portion of the male screw portion is provided on the inner diameter surface of the pulley, Excessive bending of the elastic member due to movement of the female screw member in the axial direction more than necessary can be prevented, and a decrease in durability of the elastic member can be suppressed.

It is possible to adopt a configuration in which a second friction plate is provided between the male screw member and the one protruding portion, and the second friction plate is prevented from rotating with respect to the pulley. In this case, since the transmission torque from the pulley is transmitted to the pulley hub by each of the two friction plates, the transmission torque per friction plate is reduced, and the friction plates are prevented from being worn. Or generation | occurrence | production of image sticking is prevented.

In order to receive a larger radial load applied to the pulley, a configuration in which a radial bearing is incorporated between the outer diameter surface of the female screw member and the inner diameter surface of the pulley, or the one projecting portion and the male screw member A structure in which a bearing holding member is provided between the opposing surfaces and a radial bearing is incorporated between the radial inner surface of the bearing holding member and the outer diameter surface of the pulley hub can be employed.

In the pulley unit according to the present invention, a configuration in which the male screw member and the female screw member are ball screws in which screws are engaged via balls, or a configuration in which the screw portions of the male screw member and the female screw member are slide screws is adopted. be able to.

Compared with the case where the screw engagement is a screw connection between a screw thread and a screw groove, which is a general screw connection, when a ball screw is used, the driving torque is reduced due to the rolling of the ball. Therefore, the relative rotation of the female screw member with respect to the male screw member becomes smooth. In addition, since the starting torque is small, torque transmission from the pulley to the pulley hub or switching between cutoffs becomes faster.

In addition, when a friction material is provided on at least one of the opposing surfaces of the male screw member or the female screw member, which is the other screw member forming the friction clutch, and the friction plate, in a contact portion between the female screw member and the friction plate The friction coefficient can be increased, and the capacity of the transmission torque can be increased. Further, when the friction coefficient at the contact portion is increased, the pressing force applied to the friction plate by the elastic member necessary for torque transmission is reduced, and a decrease in the durability of the friction plate can be suppressed.

When adopting a configuration in which the second friction plate is provided between one screw member and one projecting portion of the male screw member and the female screw member, the male screw member or the female screw member that is the one screw member and the first screw member A friction material may be provided on at least one of the opposing surfaces of the two friction plates. Also in this case, similarly to the configuration in which the friction material is provided on at least one of the opposing surfaces of the other screw member and the friction plate, the capacity of the transmission torque can be increased and the decrease in the durability of the second friction plate can be suppressed. it can.

In addition, if a thrust bearing is incorporated between the one projecting portion and the opposing surface of the one screw member, the male screw member or the female screw member, rotational torque transmitted from the one projecting portion to the pulley hub is reduced. Thus, it is possible to stabilize the torque transmitted to one of the screw members, and it is possible to further improve the absorption performance of fluctuations in rotational speed.

The pulley unit of the present invention receives the pressing force of the elastic member that presses the friction plate against the other screw member of the male screw member or the female screw member by two protrusions formed on the outer diameter surface of the pulley hub or the inner diameter surface of the pulley. As a result, the bearing that supports the pulley and the pulley hub so as to be relatively rotatable can be prevented from being subjected to the pressing force, so that a decrease in the durability of the bearing can be suppressed, and the life can be extended.

Sectional drawing which shows the pulley unit which concerns on 1st Embodiment. Enlarged sectional view showing the state before the pulley unit is activated Enlarged sectional view showing the operating state of the pulley unit Sectional drawing which shows the external thread member and internal thread member in the operation state of a pulley unit Sectional drawing which shows the other structure of the external thread member and internal thread member of a pulley unit Sectional drawing which shows the pulley unit which concerns on 2nd Embodiment. Sectional drawing which shows the pulley unit which concerns on 3rd Embodiment. Sectional drawing which shows the pulley unit which concerns on 4th Embodiment Enlarged sectional view showing the state before the pulley unit is activated Enlarged sectional view showing the operating state of the pulley unit Sectional drawing which shows the external thread member and internal thread member in the operation state of a pulley unit Sectional drawing which shows the other structure of the external thread member and internal thread member of a pulley unit Sectional drawing which shows the pulley unit which concerns on 5th Embodiment Sectional drawing which shows the pulley unit which concerns on 6th Embodiment

A pulley unit according to a first embodiment of the present invention will be described below with reference to FIGS.
This pulley unit is applied to an engine accessory of an automobile, and as shown in FIG. 1, includes a cylindrical pulley 1 having a double row V-groove 2 on an outer peripheral surface, and a pulley hub 3 incorporated inside the pulley. Yes. The pulley 1 and the pulley hub 3 are supported so as to be relatively rotatable by a bearing 4 incorporated between opposite one ends thereof, and the bearing 4 includes a seal on one end side in the axial direction.

In the pulley 1, the outer periphery of the seal member 5 is press-fitted to the inner periphery of the other end, and the lip 6 formed on the inner periphery of the seal member 5 is in sliding contact with the outer periphery of the other end of the pulley hub 3. The other end opening between the pulley 1 and the pulley hub 3 is closed to prevent foreign matter from entering the inside.

The pulley hub 3 is provided with a flange 7 as a protruding portion for positioning the bearing 4 in the axial direction at one end portion of the outer diameter surface, and a retaining ring 8 as a protruding portion is attached to the inner periphery of the other end portion. As shown in FIG. 2, a male screw member 9 and a female screw member 10 that are screw-engaged with each other are incorporated between the flange 7 and the retaining ring 8, and one of the

screw members

9 and 10 is one screw member. A washer 11 is incorporated between the female screw member 10 and the retaining ring 8.

The male screw member 9, which is the other screw member of the both

screw members

9, 10, has a cylindrical shape, has a flange-shaped large diameter portion at the flange 7 side end portion, and an outer peripheral portion of the male screw member 9 on the retaining ring 8 side. A helical thread groove 13 is formed as a threaded portion. The male screw member 9 is supported by a radial bearing 14 formed of a needle roller bearing built between the inner periphery thereof and the outer periphery of the pulley hub 3 so as to be rotatable and movable in the axial direction.

By incorporating the radial bearing 14, it is possible to receive a larger radial load applied to the pulley 1. However, when the radial load applied to the pulley 1 is relatively small, the radial bearing 14 may be omitted. Good.

The female screw member 10 that engages with the outer side of the male screw member 9 in the radial direction has a cylindrical shape. A spline 12 is formed on the outer periphery of the male screw member 9. And rotate together. Further, the female screw member 10 is prevented from moving outward in the axial direction via a washer 11 by a retaining ring 8 which is a protruding portion.

A spiral screw groove 15 as a screw portion is formed in the inner peripheral portion of the female screw member 10, and a plurality of balls 16 are interposed between the screw groove 15 and the screw groove 13 of the male screw member 9. Yes. Accordingly, the male screw member 9, the female screw member 10 and the ball 16 constitute a ball screw. The female screw member 10 and the male screw member 9 are screw-engaged via the ball 16, and the male screw member 9 is axially connected to the female screw member 10. It can be moved to.

In addition, a friction plate 17 is incorporated between the male screw member 9 and the flange 7 to form a friction clutch with the large diameter portion of the male screw member 9. The friction plate 17 is prevented from rotating with respect to the pulley hub 3 by fitting of a spline 18 formed between the fitting surfaces with the pulley hub 3 and is rotated integrally with the pulley hub 3.

The friction plate 17 can fix a friction material 19 mainly composed of a non-metallic material to a surface facing the male screw member 9 by a known bonding means. The friction material 19 is not limited to a structure that is fixed only to the friction plate 17 as long as the friction coefficient can be increased at the contact portion between the male screw member 9 and the friction plate 17 forming the friction clutch. And at least one of them.

An elastic member 20 is incorporated between the friction plate 17 and the flange 7. In this embodiment, a disc spring is employed as the elastic member 20, and the friction plate 17 is biased toward the male screw member 9 (retaining ring 8), and the male screw member 9 moves toward the flange 7 with respect to the female screw member 10. Then, it is pressed by the friction plate 17 and elastically deforms. The friction plate 17 is pressed against the male screw member 9 by this elastic deformation, and the friction clutch is brought into a coupled state.

A ring-shaped stopper 21 is fitted between the friction plate 17 on the outer diameter surface of the pulley hub 3 and the flange 7, and the amount of movement of the male screw member 9 in the axial direction is moved by the screw portion of the female screw member 10. The male screw member 9 is restricted within the range of the maximum amount of movement in the axial direction.

The pulley unit according to the first embodiment has the above-described structure, and when driving an alternator as an engine accessory, the pulley hub 3 is fitted to the rotating shaft of the alternator to prevent rotation, and the pulley 1 of the pulley unit A belt is stretched between a pulley attached to a crankshaft of the engine and the rotation of the crankshaft is transmitted to the pulley 1.

When the pulley unit is in use, the friction plate 17 biased by the elastic member 20 exerts a small pressing force on the female screw member 10 in a state where the rotation of the pulley 1 is stopped. When rotational torque is input to the pulley 1 in the forward rotation direction in a state where this pressing force is applied, the female screw member 10 that is prevented from rotating about the pulley 1 rotates relative to the male screw member 9 in one direction.

Since the female screw member 10 and the male screw member 9 are screw-engaged with each other, the relative rotation of the male screw member 9 moves toward the flange 7 as the other protruding portion with respect to the female screw member 10, and the friction plate 17. The elastic member 20 is also elastically deformed so as to move together with the male screw member 9 and compress the elastic member 20 (see FIG. 3).

The friction plate 17 is strongly pressed against the male screw member 9 by the elastic restoring force of the elastic member 20 that has been elastically deformed, and the friction clutch is engaged. Further, when the male screw member 9 is pressed against the other axial end side (retaining ring 8 side) by the friction plate 17 (see arrow a in FIG. 4), one end side of the groove wall of the screw groove 13 of the male screw member 9 ( The portion on the flange 7 side presses the portion on the other end side (the retaining ring 8 side) of the groove wall of the thread groove 15 of the female screw member 10 through the ball 16.

As the amount of movement of the male screw member 9 toward the flange 7 increases, the elastic restoring force of the compressed elastic member 20 increases, and the ball between the male screw member 9 and the female screw member 10 is pressed against the female screw member 10. 16, the frictional resistance between the screw portions increases.

Due to this frictional resistance, the rotation of the pulley 1 is transmitted from the female screw member 10 to the male screw member 9 and is also transmitted to the pulley hub 3 via the friction plate 17 that forms a friction clutch with the male screw member 9. It rotates in the same direction as the pulley 1.

When the rotational speed of the pulley 1 varies due to the change in the angular speed of the crankshaft in the state of rotational torque transmission from the pulley 1 to the pulley hub 3, the male screw member 9 and the female screw member 10 rotate relative to each other, and the male screw member 9 becomes the female screw member 10. The amount of elastic deformation in the axial direction of the elastic member 20 due to the pressing from the friction plate 17 varies.

The fluctuation of the rotational speed of the pulley 1 is absorbed by the fluctuation of the elastic deformation amount. As a result, transmission of fluctuations in the rotational speed of the pulley 1 to the pulley hub 3 is prevented, and the friction clutch is maintained in the coupled state.

When the pulley 1 suddenly decelerates or stops due to the sudden deceleration or stop of the engine, the pulley hub 3 tries to continue to rotate because the rotating shaft of the alternator has a large inertial force. Due to the rotation of the pulley hub 3 by the inertial force, the male screw member 9 and the female screw member 10 are relatively rotated in the other direction, and the male screw member 9 is moved in the axial direction opposite to the friction plate 17 side. As the male screw member 9 moves, the friction plate 17 also moves, the elastic member 20 extends, and the pressing force of the friction plate 17 on the male screw member 9 decreases. As a result, the coupled state of the friction clutch is released, slip occurs at the contact portion between the friction plate 17 and the male screw member 9, and the pulley hub 3 continues to rotate due to inertial force.

Thus, when the fluctuation of the rotational speed occurs in the pulley 1, the elastic member 20 is elastically deformed to absorb the fluctuation of the rotational speed of the pulley 1, and when the pulley 1 is suddenly decelerated or stopped, Sliding occurs at the contact portion with the friction plate 17, and the pulley hub 3 continues to rotate due to the inertial force. For this reason, it is possible to prevent an abrupt increase in the tension of the belt and to prevent the occurrence of slip between the pulley 1 and the belt.

Further, the male screw member 9 that receives the pressing force of the elastic member 20 by the flange 7 and the retaining ring 8 and is not loaded on the bearing 4 and is movable in the axial direction by relative rotation with the female screw member 10 is The radial bearing 14 is slid and moved so that a large axial load is not applied to the radial bearing 14. For this reason, the possibility of damage to the bearing 4 and the radial bearing 14 is extremely reduced, and a pulley unit having excellent durability can be obtained.

In this embodiment, when the amount of movement of the male screw member 9 in the axial direction is larger than necessary due to the relative rotation of the male screw member 9 and the female screw member 10 in one direction, the male screw member 9 is pressed by the friction plate 17 that moves with the male screw member 9. The elastic member 20 may be bent excessively and be damaged.

However, the pulley unit according to this embodiment includes a ring-shaped stopper 21 on the outer diameter surface of the pulley hub 3 as shown in FIG. The stopper 21 limits the amount of axial movement of the friction plate 17 that moves together with the male screw member 9, and can prevent excessive deformation of the elastic member 20.

In the pulley unit according to this embodiment, as shown in FIG. 3, a configuration is adopted in which the threaded portions of the male screw member 9 and the female screw member 10 are formed of ball screws that are screw-engaged via the balls 16. A configuration in which the thread portion of the female screw member 10 is formed of a sliding screw can be employed. As shown in FIG. 5, the sliding screw is obtained by screwing a helical thread 22 formed on the inner peripheral surface of the female screw member 10 into the screw groove 13 of the male screw member 9.

In the configuration including the slide screw, as in the case where the configuration including the ball screw is adopted, when the male screw member 9 is moved in the axial direction toward the flange 7, the male screw member 9 is moved to the other axial end side (retaining ring) by the friction plate 17. 8 (see arrow b in FIG. 5), one end side (flange 7 side) portion of the groove wall of the screw groove 13 of the male screw member 9 presses the thread 22 of the female screw member 10. As a result, the frictional resistance between the screw thread 22 and the groove wall of the screw groove 13 is increased, and the rotation of the pulley 1 is transmitted from the female screw member 10 to the pulley hub 3 via the male screw member 9.

A pulley unit according to a second embodiment of the present invention will be described with reference to FIG.
In this embodiment, a bearing holding member 23 and a second friction plate 24 are incorporated between the retaining ring 8 and the female screw member 10, and instead of the radial bearing 14 incorporated between the pulley hub 3 and the male screw member 9, This is different from the first embodiment described above in that a radial bearing 25 is incorporated between the outer diameter surface of the bearing holding member 23 and the inner diameter surface of the pulley 1. In other configurations, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The bearing holding member 23 is positioned in the axial direction by the retaining ring 8 and is prevented from rotating with respect to the pulley hub 3, and a radial bearing 25 is incorporated between the outer diameter portion of the pulley 1 and the inner diameter surface of the pulley 1. The radial bearing 25 can receive a radial load applied to the pulley 1, and the outer diameter surface of the pulley hub 3 and the inner diameter surface of the male screw member 9 according to the magnitude of the radial load applied to the pulley 1. Further, a radial bearing may be incorporated between the two.

The second friction plate 24 is prevented from rotating on the pulley hub 3 by fitting a spline 28 formed between the fitting surfaces with the pulley hub 3. Further, for the purpose of increasing the friction coefficient at the facing surface between the female screw member 10 and the second friction plate 24, a friction material 26 mainly composed of a non-metallic material may be fixed to at least one of the facing surfaces. .

As shown in FIG. 6, when the second friction plate 24 is provided, the transmission torque from the pulley 1 can be transmitted from each of the two

friction plates

17 and 24 to the pulley hub 3. The transmission power can be reduced, wear of the

friction plates

17 and 24 is suppressed, and the occurrence of seizure is prevented.

A pulley unit according to a third embodiment of the present invention will be described with reference to FIG.
In this embodiment, the bearing holding member 23 is incorporated between the retaining ring 8 and the female screw member 10, and the outer diameter of the bearing holding member 23 is used instead of the radial bearing 14 incorporated between the pulley hub 3 and the male screw member 9. This is different from the first embodiment in that a radial bearing 25 is incorporated between the surface and the inner diameter surface of the pulley 1 and a thrust bearing 27 is incorporated between the opposed surfaces of the bearing holding member 23 and the female screw member 10. To do. In other configurations, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 7, the rotational resistance of the female screw member 10 can be reduced by incorporating a thrust bearing 27 between the opposed surfaces of the female screw member 10 and the bearing holding member 23, and the male screw member 9, the female screw member 10, Torque transmission during the period becomes stable, and the absorption performance of fluctuations in rotational speed can be further enhanced.

In addition, since the radial bearing 25 is incorporated between the outer diameter surface of the bearing holding member 23 and the inner diameter surface of the pulley 1, it is possible to receive a radial load applied to the pulley 1. A radial bearing may be further incorporated between the outer diameter surface of the pulley hub 3 and the inner diameter surface of the male screw member 9 according to the magnitude of the radial load applied to the pulley 1.

When the flange 7 and the retaining ring 8 which are the two protrusions are configured with respect to the outer diameter surface of the pulley hub 3 or the inner diameter surface of the pulley 1, and when the pulley 1 rotates in one direction relative to the pulley hub 3, A specific configuration in which one of the

screw members

9 and 10 rotates relative to the other screw member in one direction is described above in the bearing 4 that supports the pulley 1 and the pulley hub 3 so as to be relatively rotatable. If the pressing force is not loaded, it can be changed as appropriate. As an example, a fourth embodiment of the present invention is shown in FIGS. In the following, differences from the first embodiment will be mainly described, and the same reference numerals will be used for the same conceivable configurations.

As shown in FIG. 8, the bearing with the resin pulley according to the fourth embodiment has a flange 7 and a retaining ring 8 that are two projecting portions provided on the inner diameter surface of the pulley 1 at an interval in the axial direction. The male screw member 9 and the female screw member 10 are incorporated between the retaining ring 8 and the friction plate 17 and the elastic member 20 that are prevented from rotating with respect to the pulley 1 between the female screw member 10 and the flange 7. It is incorporated.

As shown in FIG. 9, a male screw member 9 and a female screw member 10 are incorporated between the flange 7 and the retaining ring 8, and a washer 11 is incorporated between the male screw member 9 and the retaining ring 8.

The male screw member 9 has a cylindrical shape and is prevented from rotating with respect to the pulley hub 3 by fitting a spline 12 formed on the inner peripheral portion thereof, so that the pulley hub 3 rotates integrally. Further, a helical thread groove 13 as a threaded portion is formed on the outer peripheral portion of the male screw member 9.

The female screw member 10 has a cylindrical shape with a bottom closed at one end in the axial direction, and is rotatably and axially moved by a radial bearing 14 formed of a needle roller bearing built in between the inner periphery of the pulley 1. Supported as possible.

The female screw member 10 is formed with a helical thread groove 15 as a threaded portion on the inner peripheral portion of the cylindrical portion, and the thread groove 15 and the thread groove 13 of the male screw member 9 disposed inside the cylindrical portion. A plurality of balls 16 are interposed therebetween. Accordingly, the male screw member 9, the female screw member 10 and the ball 16 constitute a ball screw. The female screw member 10 and the male screw member 9 are screw-engaged via the ball 16, and the female screw member 10 is axial with respect to the male screw member 9. It can be moved to.

Also, a friction plate 17 is incorporated between the closed end of the female screw member 10 and the flange 7 to form a friction clutch between the closed end of the female screw member 10. The friction plate 17 is prevented from rotating around the pulley 1 by the fitting of a spline 18 formed between the fitting surfaces with the pulley 1, and rotates integrally with the pulley 1.

The friction plate 17 can fix a friction material 19 mainly composed of a non-metallic material to a surface facing the female screw member 10 by a known bonding means. The friction material 19 can be fixed to at least one of the female screw member 10 and the friction plate 17.

A disc spring is employed as the elastic member 20 between the friction plate 17 and the flange 7, and the friction plate 17 is biased toward the female screw member 10, and the female screw member 10 moves toward the flange 7 with respect to the male screw member 9. When it moves, it is elastically deformed by being pressed by the friction plate 17. The friction plate 17 is pressed against the female screw member 10 by this elastic deformation, and the friction clutch is brought into a coupled state.

A ring-shaped stopper 21 is fitted between the friction plate 17 and the flange 7 on the inner peripheral surface of the pulley 1, and the axial movement amount of the male screw member 9 is moved by the screw portion of the male screw member 9 by the stopper 21. The internal thread member 10 is restricted within the range of the maximum amount of movement in the axial direction.

The pulley unit according to the fourth embodiment has the above-described structure. When the pulley unit 1 is in use and the rotation of the pulley 1 is stopped, the friction plate 17 biased by the elastic member 20 is A small pressing force is applied. When a rotational torque is input to the pulley 1 in the forward rotation direction with this pressing force acting, the torque is transmitted from the friction plate 17 to the female screw member 10, and the female screw member 10 and the male screw member 9 are relatively relative to each other in one direction. Rotate.

By the relative rotation of the female screw member 10 and the male screw member 9, the female screw member 10 is screw-engaged with the male screw member 9, and therefore moves to the flange 7 side as the other protruding portion (see FIG. 10). As the internal thread member 10 moves, the friction plate 17 also moves and elastically deforms so that the elastic member 20 is compressed.

The friction plate 17 is strongly pressed against the female screw member 10 by the elastic restoring force of the elastic member 20 which has been elastically deformed, and the friction clutch is engaged. When the female screw member 10 is pressed against the other axial end by the friction plate 17 (see arrow a in FIG. 11), the other end portion of the groove wall of the screw groove 15 of the female screw member 10 becomes the ball 16. A portion on one end side of the groove wall of the screw groove 13 of the male screw member 9 is pressed through

As the amount of movement of the female screw member 10 toward the flange 7 increases, the elastic restoring force of the elastic member 20 increases, and the screw portion between the female screw member 10 and the male screw member 9 is pressed between the female screw member 9 and the male screw member 9. Increases frictional resistance.

Due to this frictional resistance, the rotation of the pulley 1 is transmitted from the friction plate 17 to the female screw member 10 and from the female screw member 10 to the pulley hub 3 via the male screw member 9, and the pulley hub 3 rotates in the same direction as the pulley 1. .

When the rotational speed of the pulley 1 is changed due to the change in the angular speed of the crankshaft in the state where the rotational torque is transmitted from the pulley 1 to the pulley hub 3, the male screw member 9 and the female screw member 10 are relative to each other as in the first embodiment. The female screw member 10 rotates and the female screw member 10 moves in the axial direction with respect to the male screw member 9, and the elastic deformation amount of the elastic member 20 in the axial direction due to the pressing from the friction plate 17 varies.

When the pulley 1 suddenly decelerates or stops due to the sudden deceleration or stop of the engine, the pulley hub 3 tries to continue to rotate because the rotating shaft of the alternator has a large inertial force. Due to the rotation of the pulley hub 3 by the inertial force, the male screw member 9 and the female screw member 10 rotate relative to each other, and the female screw member 10 moves in the axial direction opposite to the friction plate 17 side. As the female screw member 10 moves, the friction plate 17 also moves, the elastic member 20 expands, and the pressing force applied to the female screw member by the friction plate 17 decreases. As a result, the coupled state of the friction clutch is released, slip occurs at the contact portion between the friction plate 17 and the female screw member 10, and the pulley hub 3 continues to rotate due to the inertial force.

As described above, when the rotational speed of the pulley 1 is changed, the elastic member 20 is elastically deformed to absorb the rotational speed of the pulley 1, and when the pulley 1 is suddenly decelerated or stopped, Sliding occurs at the contact portion with the friction plate 17, and the pulley hub 3 continues to rotate due to the inertial force. For this reason, it is possible to prevent an abrupt increase in the tension of the belt and to prevent the occurrence of slip between the pulley 1 and the belt.

In addition, the female screw member 10 that receives the pressing force of the elastic member 20 by the flange 7 and the retaining ring 8 and is not loaded on the bearing 4 and can move in the axial direction by relative rotation with the male screw member 9 is The radial bearing 14 is slid and moved so that a large axial load is not applied to the radial bearing 14. For this reason, the possibility of damage to the bearing 4 and the radial bearing 14 is extremely reduced, and a pulley unit having excellent durability can be obtained.

In this embodiment, when the movement amount in the axial direction of the female screw member 10 is larger than necessary due to the relative rotation of the male screw member 9 and the female screw member 10, the friction plate 17 that moves together with the female screw member 10 is pressed. The elastic member 20 may be bent due to excessive bending.

However, the pulley unit according to this embodiment includes a ring-shaped stopper 21 on the inner diameter surface of the pulley 1 as shown in FIG. The stopper 21 limits the amount of axial movement of the friction plate 17 that moves together with the female screw member 10, and can prevent excessive deformation of the elastic member 20.

In the pulley unit according to this embodiment, as shown in FIG. 10, the male screw member 9 and the screw portion of the female screw member 10 are composed of ball screws that are screw-engaged via balls 16. A configuration in which the thread portion of the female screw member 10 is formed of a sliding screw can be employed. As shown in FIG. 12, the sliding screw is obtained by screwing a helical thread 22 formed on the inner peripheral surface of the female screw member 10 into the screw groove 13 of the male screw member 9.

In the configuration including the slide screw, as in the case where the configuration including the ball screw is employed, when the internal thread member 10 moves in the axial direction toward the flange 7, the internal thread member 10 is pressed against the other end in the axial direction by the friction plate 17. (See arrow b in FIG. 12), the thread 22 of the female screw member 10 presses a portion on one end side of the groove wall of the screw groove 13 of the male screw member 9. As a result, the frictional resistance between the screw thread 22 and the groove wall of the screw groove 13 is increased, and the rotation of the pulley 1 is transmitted from the female screw member 10 to the pulley hub 3 via the male screw member 9.

A pulley unit according to a fifth embodiment of the present invention will be described with reference to FIG.
In this embodiment, a bearing holding member 23 and a second friction plate 24 are incorporated between the retaining ring 8 and the male screw member 9, and instead of the radial bearing 14 incorporated between the pulley 1 and the female screw member 10, This differs from the fourth embodiment described above in that a radial bearing 25 is incorporated between the inner diameter surface of the bearing holding member 23 and the outer diameter surface of the pulley hub 3. In other configurations, the same components as those in the fourth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The bearing holding member 23 is positioned in the axial direction by the retaining ring 8 and is prevented from rotating with respect to the pulley 1, and a radial bearing 25 is incorporated between the outer diameter surface of the pulley hub 3 at the inner diameter portion thereof. The radial bearing 25 can receive a radial load applied to the pulley 1, and further, between the inner diameter surface of the pulley 1 and the outer diameter surface of the female screw member 10, depending on the magnitude of the radial load. A radial bearing may be incorporated.

The second friction plate 24 is prevented from rotating around the pulley 1 by fitting a spline 28 formed between the fitting surfaces with the pulley 1. Further, for the purpose of increasing the friction coefficient at the facing surface between the male screw member 9 and the second friction plate 24, a friction material 26 mainly composed of a nonmetallic material may be fixed to at least one of the facing surfaces. .

As shown in FIG. 13, when the second friction plate 24 is provided, the transmission torque from the pulley 1 can be transmitted from each of the two

friction plates

17 and 24 is suppressed, and the occurrence of seizure is prevented.

A pulley unit according to a sixth embodiment of the present invention will be described with reference to FIG.
In this embodiment, a bearing holding member 23 is incorporated between the retaining ring 8 and the male screw member 9, and an inner diameter surface of the bearing holding member 23 is used instead of the radial bearing 14 incorporated between the pulley 1 and the female screw member 10. Is different from the above-described fourth embodiment in that a radial bearing 25 is incorporated between the outer peripheral surface of the pulley hub 3 and the thrust bearing 27 between the opposing surfaces of the bearing holding member 23 and the male screw member 9. To do. In other configurations, the same components as those in the fourth embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 14, the rotational resistance of the male screw member 9 can be reduced by incorporating the thrust bearing 27 between the opposing surfaces of the male screw member 9 and the bearing holding member 23, and the male screw member 9, the female screw member 10, Torque transmission during the period becomes stable, and the absorption performance of fluctuations in rotational speed can be further enhanced.

In addition, since the radial bearing 25 is incorporated between the inner diameter surface of the bearing holding member 23 and the outer diameter surface of the pulley hub 3, it is possible to receive a radial load applied to the pulley 1. A radial bearing may be further incorporated between the inner diameter surface of the pulley 1 and the outer diameter surface of the female screw member 10 according to the magnitude of the radial load.

DESCRIPTION OF SYMBOLS 1 Pulley 2 V groove 3 Pulley hub 4 Bearing 5 Seal member 6 Lip 7 Flange 8 Retaining ring 9 Male thread member 10 Female thread member 11 Washer 12 Spline 13 Thread groove 14 Radial bearing 15 Thread groove 16 Ball 17 Friction plate 18 Spline 19 Friction material 20 Elasticity Member 21 Stopper 22 Thread 23 Bearing holding member 24 Second friction plate 25 Radial bearing 26 Friction material 27 Thrust bearing 28 Spline

Claims

A pulley and a pulley hub incorporated inside the pulley are rotatably supported by a bearing incorporated between one end portions of the two members, and two pulleys are provided on the outer diameter surface of the pulley hub or the inner diameter surface of the pulley. Protrusions are provided at intervals in the axial direction, and between the two protrusions, a male screw member and a female screw member that engage with each other are incorporated, and one of the two screw members is the one of the pulley or the pulley hub. One of them is prevented from rotating, the one protrusion prevents movement outward in the axial direction, and the other screw member is rotatable relative to the other of the pulley or pulley hub and moves in the axial direction. Supported as possible,
Between the other screw member and the other protrusion, it is prevented from rotating with respect to the other of the pulley or the pulley hub and is movable in the axial direction to form a friction clutch with the other screw member. A friction plate and an elastic member that urges the friction plate toward the one protrusion,
When the pulley rotates relative to the pulley hub in one direction, the other screw member rotates relative to the one screw member in one direction and pivots together with the friction plate toward the other protrusion. When the friction plate is moved, the elastic member is pushed by the friction plate to be elastically deformed so that the friction clutch is engaged, and the rotation of the pulley is transmitted to the pulley hub. Pulley unit.
The two projecting portions are provided on the outer diameter surface of the pulley hub at an axial interval, and between the two projecting portions, the pulley is prevented from rotating, and the one projecting portion causes the first projecting portion to axially outward. Incorporating the female screw member that is the one screw member that is prevented from moving, and the male screw member that is the other screw member that is supported rotatably and axially movable with respect to the pulley hub, 2. The pulley unit according to claim 1, wherein the friction plate that is prevented from rotating with respect to the pulley hub and the elastic member are incorporated between the male screw member and the other protruding portion.
The stopper which restrict | limits the moving amount of the axial direction of the said external thread member to the outer diameter surface of the said pulley hub within the range of the maximum axial movement amount of the said external thread member moved by the thread part of the said internal thread part is provided. The pulley unit described in 1.
4. The pulley unit according to claim 2, wherein a second friction plate is provided between the female screw member and the one protruding portion, and the second friction plate is prevented from rotating with respect to the pulley hub.
The pulley unit according to any one of claims 2 to 4, wherein a radial bearing is incorporated between an inner diameter surface of the male screw member and an outer diameter surface of the pulley hub.
The bearing holding member is provided between the opposing surfaces of the one projecting portion and the female screw member, and a radial bearing is incorporated between the radially outer surface of the bearing holding member and the inner diameter surface of the pulley. The pulley unit according to any one of 5.
The two protrusions are axially spaced on the inner diameter surface of the pulley, and between the two protrusions, the pulley hub is prevented from rotating, and the one protrusion moves outward in the axial direction. The male screw member, which is blocked, and the female screw member supported so as to be rotatable and axially movable with respect to the pulley are incorporated, and the pulley is interposed between the female screw member and the other protrusion. The pulley unit according to claim 1, wherein the friction plate that is prevented from rotating with respect to the elastic member is incorporated.
8. A stopper for restricting an axial movement amount of the female screw member within a range of a maximum axial movement amount of the female screw member that is moved by the screw portion of the male screw portion, on the inner diameter surface of the pulley. The pulley unit described.
The pulley unit according to claim 7 or 8, wherein a second friction plate is provided between the male screw member and the one projecting portion, and the second friction plate is prevented from rotating with respect to the pulley.
The pulley unit according to any one of claims 7 to 9, wherein a radial bearing is incorporated between an outer diameter surface of the female screw member and an inner diameter surface of the pulley.
8. A bearing holding member is provided between opposing surfaces of the one projecting portion and the male screw member, and a radial bearing is incorporated between a radially inner surface of the bearing holding member and an outer diameter surface of the pulley hub. The pulley unit according to any one of 1 to 9.
The pulley unit according to any one of claims 1 to 11, wherein a thread portion of the male screw member and the female screw member is a ball screw screw-engaged via a ball.
The pulley unit according to claim 1 or 11, wherein a thread portion of the male screw member and the female screw member is a slide screw.
14. The friction material is provided on at least one of opposing surfaces of the male screw member or the female screw member, which is the other screw member forming the friction clutch, and the friction plate. Pulley unit.
The pulley unit according to claim 4 or 9, wherein a friction material is provided on at least one of the opposing surfaces of the male screw member or the female screw member that is the one screw member and the second friction plate.
The pulley unit according to any one of claims 1 to 15, wherein a thrust bearing is incorporated between opposing surfaces of the one protruding portion and the male screw member or the female screw member that are the one screw member.