WO2023189928A1 - Automatic tensioner - Google Patents

Abstract

The present invention is configured to have: a first pulley arm (9) that supports a first idler pulley (7) in contact with an accessory belt (6); a second pulley arm (10) that supports a second idler pulley (8) in contact with the accessory belt (6); a swing fulcrum shaft (11) that swingably supports the first pulley arm (9) and the second pulley arm (10); an elastic member (22) that biases the second pulley arm (10) against the first pulley arm (9) to bring the first idler pulley (7) and the second idler pulley (8) closer to each other; and swing resistance members (33, 34) that generate swinging resistance against the first pulley arm (9) and the second pulley arm (10) only in one of the swinging directions thereof, respectively.

Description

auto tensioner

The present invention relates to an autotensioner used in a belt system for driving auxiliary equipment of an automobile engine, a timing belt, and the like.

In recent years, in belt systems for driving auxiliary equipment of automobile engines, in addition to the functions of conventional alternators, belt starter generators have been introduced that restart the engine after idling and assist engine power while driving. The number of mild hybrid vehicles equipped with BSG (hereinafter abbreviated as BSG) is increasing. This auxiliary drive belt system is a belt system that spans between a crank pulley installed on the engine crankshaft and a pulley installed on the BSG drive shaft (hereinafter referred to as the BSG pulley). It has a belt transmission device that transmits power using a machine belt (hereinafter referred to as a belt).

This belt transmission device has the characteristic that the tension side and slack side of the belt are switched between during normal operation when the crank pulley is driven, and when restarting the engine after idling stop and when driving by assisting while driving, when the BSG pulley is driven. have

In other words, during normal operation when the BSG operates as a generator, the crank pulley drives the BSG pulley via the belt, so the part of the belt that runs from the BSG pulley toward the crank pulley becomes the tension side, and the belt runs from the crank pulley to the BSG pulley. The part of the belt that runs toward the pulley is the slack side. On the other hand, when restarting the engine after idling stop by BSG or during drive assist while driving, the BSG pulley drives the crank pulley via the belt, so the part of the belt that runs from the crank pulley to the BSG pulley is the tension side, and the part of the belt that runs from the BSG pulley to the crank pulley is the slack side.

In order to prevent such belt slack and appropriately adjust belt tension, an autotensioner disclosed in Patent Document 1, for example, is used. In a configuration such as a mild hybrid vehicle, in which the slack side of the belt changes between normal driving and engine restart, auto-tensioner pulleys are installed on the belt spans on both sides of the BSG pulley, for example, as shown in Patent Document 2. By connecting these pulleys so that they can move relative to each other through an intermediate member and interlocking the pulleys with each other, belt tension can be adjusted during normal operation and when restarting the engine after idling. Furthermore, as shown in Patent Document 3, for example, two pulley arms are attached to one swing fulcrum and interlocked, and an elastic member applies a biasing force in a direction in which both pulley arms approach each other, thereby imparting initial belt tension to the belt. A system has also been proposed in which tension fluctuations in the belt are eliminated by applying a damping force by pressing a friction member.

Japanese Patent Application Publication No. 2009-275757 Patent No. 5634685 Special Publication No. 2003-521639

When applying the conventional auto tensioner shown in Patent Document 1 to a mild hybrid vehicle, by arranging the auto tensioner on each belt span on both sides of the BSG pulley, the belt tensioner can be adjusted during normal driving and when restarting the engine after idling. Tension can be adjusted. However, since the autotensioners are disposed in two locations, the weight and cost increase, and the assembly and replacement work becomes complicated.

Furthermore, in the auto tensioner shown in Patent Document 2, which adjusts the tension of the belt spans on both sides of the BSG pulley by interlocking two pulleys, the entire auto tensioner is oscillated in response to changes in belt tension caused by changes in engine rotation. The belt tension is adjusted by the movement and biasing force. However, as belt tension fluctuations increase, the entire autotensioner swings larger, causing abnormal noise due to vibration or contact with the locking mechanism, or causing the belt and pulley to separate, causing tension to be applied to the belt. There is a risk that you may not be able to do so. Furthermore, in the autotensioner disclosed in Patent Document 3, since the damping force by the friction member acts in both directions of swing of the pulley arm, there is a possibility that tension cannot be applied quickly when the belt becomes slack.

The problem to be solved by the present invention is to be able to apply optimal belt tension during normal operation and when restarting the engine after idling, and to suppress excessive rocking of the pulley arm to improve followability. The objective is to provide an auto tensioner with high performance.

In order to solve the above problems, in the present invention,
a first pulley arm supporting a first idler pulley that contacts the accessory belt;
a second pulley arm supporting a second idler pulley that contacts the accessory belt;
a swing fulcrum shaft that swingably supports the first pulley arm and the second pulley arm;
an elastic member that urges the second pulley arm relative to the first pulley arm so that the first idler pulley and the second idler pulley approach each other;
a swing resistance member that generates swing resistance in only one direction of each swing direction with respect to the first pulley arm and the second pulley arm;
An auto tensioner was constructed with the following.

In this way, by the rocking resistance in one direction by the rocking resistance member, it is possible to apply the optimum belt tension both during normal operation and when restarting the engine after idling stop. Excessive swinging of the pulley arm can be suppressed to improve followability of the auxiliary belt.

In the above configuration,
The one direction is a direction in which the first pulley arm or the second pulley arm swings when the first idler pulley or the second idler pulley is pushed by the tension of the auxiliary belt. is preferred.

By doing this, when the pulley arm swings as the tension of the accessory belt increases and the idler pulley is about to separate from the accessory belt, the action of the swing resistance member causes the idler pulley to move away from the accessory belt. You can prevent them from leaving. On the other hand, when the auxiliary belt becomes slack, tension can be quickly applied to the auxiliary belt by the urging force of the elastic member without receiving rocking resistance from the rocking resistance member.

In all the above configurations,
Preferably, the rocking resistance member is provided on each of the first pulley arm and the second pulley arm.

In this way, the belt tension can be maintained appropriately both during normal operation and when restarting the engine after idling stop.

In all the above configurations,
The swing resistance member is made of an elastic material having a C-shaped arc, and one end of the arc is locked to the swing fulcrum shaft, while the other end is connected to the first pulley arm and the second pulley arm. It is provided in a receiving part formed on a pulley arm, and when the first pulley arm and the second pulley arm swing in the one direction, the other end side engages with the receiving part to prevent the swinging. It is preferable that the resistance member is elastically deformed to generate rocking resistance in the first pulley arm and the second pulley arm.

Alternatively, the rocking resistance member is a torsion coil spring, one end of which is locked to the rocking fulcrum shaft, and the other end of the rocking resistance member being a torsion coil spring that is fixed to the rocking fulcrum shaft, and the other end of the rocking resistance member is a torsion coil spring that is fixed to the rocking fulcrum shaft. When the first pulley arm and the second pulley arm swing in the one direction, the other end engages with the inner edge of the receiving part, and the swing resistance member becomes elastic. It is preferable that the first pulley arm and the second pulley arm generate rocking resistance by deforming.

In this way, only when the pulley arm swings in one direction, the swing resistance member is elastically deformed due to the engagement between the other end side of the swing resistance member and the inner edge of the receiving part, and the pulley arm relative to the swing fulcrum shaft is elastically deformed. On the other hand, when the pulley arm swings in the other direction, the other end of the swing resistance member does not engage with the inner edge of the receiving part, which prevents the pulley arm from swinging relative to the swing fulcrum axis. Dynamic resistance can be prevented from occurring.

In all the above configurations,
The receiving portion is a fan-shaped recess formed on the inner diameter surface of the first pulley arm and the second pulley arm, and the other end side of the swing resistance member is engageable with the receiving portion. Preferably, the bent portion is bent radially outward.

In this way, the bending portion of the swing resistance member can be easily engaged by machining the recess on the inner diameter surface of the pulley arm, and no additional parts are required, thereby reducing costs.

Instead of forming the sector-shaped recess,
An arm-side locking member that is a separate member from each pulley arm and has higher wear resistance than each pulley arm is provided on the inner diameter surface of the first pulley arm and the second pulley arm. portion is a circumferential end portion of the arm-side locking member, and the other end side of the rocking resistance member is a bent portion bent radially outward so as to be engageable with the receiving portion. is also preferable.

In this way, it is possible to prevent as much as possible the other end of the rocking resistance member from repeatedly coming into contact with the receiving portion, thereby preventing the receiving portion from being worn out, thereby increasing the durability of the auto-tensioner.

In the configuration in which the arm-side locking member is provided,
The arm-side locking member is a substantially C-shaped member, and one end of the arm side locking member in the circumferential direction is formed so as to protrude radially inward from the inner diameter surface of the first pulley arm and the second pulley arm. It is preferable that the other end in the circumferential direction thereof act as the receiving part that engages with the other end of the rocking resistance member.

Alternatively, it is preferable that the arm-side locking member is integrated with the first pulley arm and the second pulley arm.

In this way, it is possible to form a highly wear-resistant receiving part with a simple configuration, and when wear occurs, it is only necessary to replace this arm-side locking member, which reduces maintenance costs. I can do it.

In all the above configurations,
When attached to the auxiliary machine belt, the other end side of the swing resistance member comes into contact with the inner edge of the receiving portion, and preloads the first pulley arm and the second pulley arm in the one direction. is preferably in a loaded state.

In this way, when the pulley arm swings in one direction, the swing resistance member can quickly exert the swing resistance.

In all the above configurations,
Preferably, the rocking resistance member and the receiving portion are provided with a lubricant.

In this way, wear caused by repeated contact between the swing resistance member and the receiving portion can be prevented as much as possible.

In all the above configurations,
It is preferable that a lubricant reservoir portion for storing the lubricant supplied between the swing fulcrum shaft and the swing resistance member is formed. Furthermore, in this configuration, it is preferable that the lubricant reservoir is an oil groove formed in at least one of the swing fulcrum shaft and the receiving part so as to extend along the swing resistance member.

In this way, even if the lubricant is likely to be squeezed out from between the swing resistance member, the receiving part, and the swing fulcrum shaft due to their contact, this lubricant will easily remain in the lubricant reservoir. Therefore, the lubricity at the contact portion between the two is maintained. In particular, by making the lubricant reservoir part an oil groove, the effect of retaining the lubricant can be further improved.

In the configuration in which the lubricant reservoir is an oil groove,
The surface roughness of the inner surface of the oil groove may be greater than the surface roughness of the outer surface of the swing fulcrum shaft.

In this way, the holding power of the lubricant in the oil groove is increased, so that the lubricity between the swing resistance member, the receiving portion, and the swing fulcrum shaft can be further improved.

In all the above configurations,
A structure in which a solid lubricant layer or a plating layer formed by hardened chromium plating, electroless nickel plating, or ion plating is formed on the surface of at least one of the rocking resistance member and the receiving part, or the receiving part It is preferable to have a hard layer formed on the surface by tempering heat treatment, carburizing heat treatment, or carbonitriding heat treatment.

In this way, the lubricity and wear resistance of the rocking resistance member and the receiving portion are improved, and the durability of the autotensioner can be increased.

In all the above configurations,
The accessory belt is stretched across a crank pulley attached to the crankshaft of the engine and an accessory pulley attached to the accessory drive shaft, and the axis of the swing fulcrum shaft is aligned with the crank pulley. Preferably, it is arranged on a line connecting the axial center of the shaft and the axial center of the auxiliary drive shaft. Further, in this case, the lengths of the first pulley arm and the second pulley arm are determined so that the swing radius of the first idler pulley and the swing radius of the second idler pulley are the same. It is preferable that the

In this way, the belt tensions acting on the auxiliary belt from each idler pulley are well balanced, and stable followability is achieved.

In the auto tensioner of the present invention, the pulley arm that swings around the swing fulcrum axis is provided with a swing resistance member that generates swing resistance only in one direction of the swing direction of the pulley arm. Optimal belt tension can be applied in any case, such as when restarting the engine after idling, and excessive rocking of the pulley arm can be suppressed to improve followability to the auxiliary belt.

A front view showing an example of an auxiliary drive system using an autotensioner according to a first embodiment of the present invention A partially cutaway front view of the autotensioner shown in Figure 1 Cross-sectional view along line III-III in Figure 2 Cross-sectional view along line IV-IV in Figure 3 Cross-sectional view along line V-V in Figure 3 Exploded perspective view of the autotensioner shown in Figure 1 Front view showing the action of the auto tensioner during normal operation Cross-sectional view of the main parts of the first pulley arm Cross-sectional view of the main parts of the second pulley arm Front view showing the action of the auto tensioner during BSG operation Cross-sectional view of the main parts of the first pulley arm Cross-sectional view of the main parts of the second pulley arm A sectional view showing a modification of the main parts of the autotensioner shown in Fig. 1 Cross-sectional view along line XX in Figure 9 Cross-sectional view along line XI-XI in Figure 9 A sectional view of an autotensioner according to a second embodiment of the present invention Cross-sectional view along line XIII-XIII in Figure 12 Cross-sectional view along line XIV-XIV in Figure 12 A sectional view of an autotensioner according to a third embodiment of the present invention Cross-sectional view along line XVI-XVI in Figure 15 Cross-sectional view along line XVII-XVII in Figure 15 FIG. 16 is a sectional view showing the operation of the auto tensioner shown in FIG. 15, with the opening angle between both pulley arms being relatively small. FIG. 16 is a sectional view showing the action of the auto tensioner shown in FIG. 15, with the opening angle gradually increasing and the swing resistance member and the arm-side locking member coming into contact with each other; FIG. 16 is a sectional view showing the action of the auto tensioner shown in FIG. 15, with the opening angle further increased and the swing resistance member expanded in diameter; A sectional view of an autotensioner according to a fourth embodiment of the present invention Cross-sectional view along line XX-XX in Figure 19 Cross-sectional view along line XXI-XXI in Figure 19 Cross-sectional view along line XXII-XXII in Figure 19 A sectional view of the main parts of the auto tensioner shown in Figure 19 A sectional view of an autotensioner according to a fifth embodiment of the present invention Cross-sectional view along line XXV-XXV in Figure 24 Cross-sectional view along line XXVI-XXVI in Figure 24 A perspective view of the main shaft used in the autotensioner shown in Figure 24 A sectional view of essential parts of an autotensioner according to a sixth embodiment of the present invention A perspective view of the main shaft used in the autotensioner shown in Figure 28 A sectional view of essential parts of an autotensioner according to a sixth embodiment of the present invention Cross-sectional view showing a modification of FIG. 30A

An example of an auxiliary drive system using an autotensioner 1 according to the first embodiment of the present invention is shown in FIGS. 1 and 2. This accessory drive system consists of a BSG pulley 3 attached to a BSG drive shaft 2 (auxiliary drive shaft) of a belt starter generator (hereinafter referred to as BSG), and a crank attached to a crankshaft 4. The pulley 5, an auxiliary belt 6 (hereinafter simply referred to as the belt 6) stretched across the BSG pulley 3 and the crank pulley 5, and an auto tensioner that maintains the tension of the belt 6 within an appropriate range. 1.

As shown in FIGS. 3 to 6, the auto tensioner 1 includes a first idler pulley 7, a second idler pulley 8, a first pulley arm 9 supporting the first idler pulley 7, and a second idler pulley 7. It has a second pulley arm 10 that supports the idler pulley 8, and a swing fulcrum shaft 11 that swingably supports the first pulley arm 9 and the second pulley arm 10. In addition, in FIG. 3, illustration of the belt 6 is omitted.

The first idler pulley 7 is in contact with the outer peripheral surface of the portion of the belt 6 that runs from the BSG pulley 3 toward the crank pulley 5. Further, the second idler pulley 8 is in contact with the outer peripheral surface of the portion of the belt 6 that runs from the crank pulley 5 toward the BSG pulley 3. The axial center of the swing fulcrum shaft 11 that supports both pulley arms 9 and 10 is arranged on a line connecting the axial center of the crankshaft 4 and the axial center of the BSG drive shaft 2.

The first pulley arm 9 and the second pulley arm 10 have base parts 12a and 12b (hereinafter, the element on the first pulley arm 9 side is denoted by a, and the element on the second pulley arm 10 side is denoted by b). , extending pieces 13a, 13b extending radially outward from the bases 12a, 12b. The first pulley arm 9 and the second pulley arm 10 are arranged such that their respective base portions 12a and 12b are aligned in the axial direction, and their respective extending pieces 13a and 13b are at different positions in the circumferential direction.

The base portions 12a, 12b are composed of concentrically arranged small diameter cylindrical portions 14a, 14b and large diameter cylindrical portions 15a, 15b. One end in the axial direction of the small diameter cylindrical parts 14a, 14b and the large diameter cylindrical parts 15a, 15b are connected by flanges 16a, 16b extending in the radial direction. Receiving portions 17a, 17b in the form of fan-shaped concave portions are formed in a portion of the small diameter tube portions 14a, 14b in the circumferential direction of the cylinder (inner diameter surfaces of the pulley arms 9, 10). In this embodiment, the center angle of the receiving portions 17a, 17b is approximately 50 degrees, but it may be changed as appropriate within the range of, for example, 20 degrees or more and 80 degrees or less. Slits 18a, 18b are formed in a portion of the large diameter cylinder portions 15a, 15b in the circumferential direction of the cylinder. The receiving portions 17a, 17b and the slits 18a, 18b are formed at positions shifted from each other in the circumferential direction. Sliding bearings 19a and 19b are press-fitted into the inner diameter sides of the small diameter cylindrical portions 14a and 14b.

At the tips of the extending pieces 13a, 13b, through holes 21a, 21b are formed through which the rotating shafts 20a, 20b of the first idler pulley 7 and the second idler pulley 8 pass. The length of the first pulley arm 9 and the second pulley arm 10 is determined by the swing radius of the first idler pulley 7 (from the axial center position of the swing fulcrum shaft 11 to the point of contact between the first idler pulley 7 and the belt 6). so that the swing radius of the second idler pulley 8 (the distance from the axial center position of the swing fulcrum shaft 11 to the point of contact between the second idler pulley 8 and the belt 6) is the same. It's decided. Note that the term "identical" as used herein includes not only complete identity but also cases where there is some difference as long as the tension of the belt 6 is not significantly affected.

In the radial gap between the small diameter cylindrical parts 14a, 14b and the large diameter cylindrical parts 15a, 15b of the first pulley arm 9 and second pulley arm 10, a common elastic member 22 is provided so as to straddle both the pulley arms 9, 10. is provided. This elastic member 22 is a coil spring made of steel. Both ends of the elastic member 22 are bent pieces 23a and 23b bent radially outward. The bent piece 23a on one end side is formed in the slit 18a formed in the large diameter cylindrical part 15a of the first pulley arm 9, and the bent piece 23b on the other end side is formed in the large diameter cylindrical part 15b of the second pulley arm 10. They are respectively locked in the slits 18b. This elastic member 22 allows the second pulley arm 10 to be moved relative to the first pulley arm 9 so that the first idler pulley 7 and the second idler pulley 8 approach each other when attached to the accessory drive system. Forced.

The swing fulcrum shaft 11 swingably supports the first pulley arm 9 and the second pulley arm 10. The swing fulcrum shaft 11 has a first fulcrum shaft 24, a second fulcrum shaft 25, and a main shaft 26 to which the first fulcrum shaft 24 and the second fulcrum shaft 25 are connected by press fitting. There is. The first fulcrum shaft 24 and the second fulcrum shaft 25 are both cylindrical members, and reduced diameter portions 27a and 27b are formed at the ends facing the main shaft 26, the outer diameters of which are smaller than other parts. There is. Furthermore, stepped press-fit stepped portions 28a, 28b are formed at the axial ends opposite to the reduced diameter portions 27a, 27b formed on the first fulcrum shaft 24 and the second fulcrum shaft 25. There is.

The main shaft 26 is a cylindrical member, and a flange 29 that stands up radially outward is formed at the axial center of the main shaft 26 over the entire circumferential circumference. Further, a contact portion 30 is formed at one location in the circumferential direction of the main shaft 26, and stands up radially outward and extends along the axial direction. By press-fitting the reduced diameter portion 27a of the first fulcrum shaft 24 and the reduced diameter portion 27b of the second fulcrum shaft 25 into both ends of the main shaft 26, they are integrated. A washer 31 is press-fitted into press- fit step portions 28a and 28b formed at both ends of the first fulcrum shaft 24 and the second fulcrum shaft 25, which are integrated with the main shaft 26. A bolt 32 for fixing the autotensioner 1 to the engine E or the like is inserted through the axial center of the swing fulcrum shaft 11.

The first fulcrum shaft 24 is press-fitted into the inner diameter side of the sliding bearing 19a that is press-fitted into the small-diameter cylindrical portion 14a of the first pulley arm 9, and the second fulcrum shaft 25 is press-fitted into the small-diameter cylindrical portion 14b of the second pulley arm 10. The slide bearings 19b are arranged on the inner diameter side of the slide bearings 19b.

The swing fulcrum shaft 11 is provided with swing resistance members 33 and 34 that create swing resistance only in one direction of the respective swing directions with respect to the first pulley arm 9 and the second pulley arm 10. The swing resistance members 33 and 34 are made of an elastic material having a C-shaped arc. One end side of the arc is a terminal end portion 35a, 35b that terminates along the circumferential direction, while the other end side is a bent portion 36a, 36b that is bent outward in the radial direction. The swing resistance members 33 and 34 are provided on both sides in the axial direction of a flange 29 formed on the outer periphery of the main shaft 26, respectively. In the following, the swing resistance member 33 provided on the first fulcrum shaft 24 side will be referred to as the first swing resistance member 33, and the swing resistance member 34 provided on the second fulcrum shaft 25 side will be referred to as the second swing resistance member 33. They are respectively referred to as resistance members 34.

The first swing resistance member 33 and the second swing resistance member 34 are attached to the main shaft 26 in opposite directions. That is, the terminal end portion 35a of the first swing resistance member 33 contacts the contact portion 30 formed on the main shaft 26 from one direction in the circumferential direction, whereas the terminal end portion 35a of the second swing resistance member 34 contacts the contact portion 30 formed on the main shaft 26 from one direction in the circumferential direction. The terminal end portion 35b is in contact with the contact portion 30 formed on the main shaft 26 from the opposite direction in the circumferential direction. The bent portion 36a of the first swing resistance member 33 is connected to the receiving portion 17a formed in the small diameter cylindrical portion 14a of the first pulley arm 9, and the bent portion 36b of the second swing resistance member 34 is connected to the second They are respectively provided in receiving portions 17b formed in the small diameter cylindrical portion 14b of the pulley arm 10.

The bent portions 36a, 36b formed in the first swing resistance member 33 and the second swing resistance member 34 are formed in the small diameter cylindrical portions 14a, 14b of the first pulley arm 9 or the second pulley arm 10. Movement within the angular range of the central angle of the receiving parts 17a, 17b is allowed. In the attached state to the accessory drive system, each bent portion 36a, 36b is in contact with the inner edge of one circumferential end of each receiving portion 17a, 17b with a slight preload. As shown in FIGS. 4 and 5, in the first pulley arm 9 and the second pulley arm 10, the circumferential positions of the inner edges where the bent portions 36a and 36b contact are opposite, but in both pulley arms 9 and 10, , the direction from one end in the circumferential direction where the inner edges of the bent parts 36a, 36b and the inner edges of the receiving parts 17a, 17b are in contact with each other is called "one direction", and the direction opposite to the one direction is called "reverse". "direction" respectively. This one direction corresponds to the direction in which the first pulley arm 9 or the second pulley arm 10 swings when the first idler pulley 7 or the second idler pulley 8 is pushed by the tension of the belt 6.

When the first pulley arm 9 shown in FIG. 4 swings in one direction (the direction indicated by the arrow in FIG. 4) with respect to the swing fulcrum shaft 11, the inner edge of the receiving portion 17a formed on the first pulley arm 9 Upon contact with the bent portion 36a of the first swing resistance member 33, the first swing resistance member 33 is elastically deformed. As a result, rocking resistance acts on the first pulley arm 9. On the other hand, when the first pulley arm 9 is swung in the opposite direction with respect to the fulcrum shaft 11, the inner edge of the receiving portion 17a formed on the first pulley arm 9 and the first oscillation resistance member 33 are bent. The first pulley arm 9 can be swung in the opposite direction without receiving any swiveling resistance from the first swiveling resistance member 33.

Furthermore, when the second pulley arm 10 shown in FIG. As the inner edge contacts the bent portion 36b of the second swing resistance member 34, the second swing resistance member 34 is elastically deformed. As a result, rocking resistance acts on the second pulley arm 10. On the other hand, when the second pulley arm 10 is swung in the opposite direction with respect to the fulcrum shaft 11, the inner edge of the receiving portion 17b formed on the second pulley arm 10 and the second oscillation resistance member 34 are bent. 36b, and the second pulley arm 10 can be swung in the opposite direction without receiving swiveling resistance from the second swiveling resistance member 34.

An example of the operation of this autotensioner 1 will be explained using FIG. 1, FIGS. 7A to 7C, and FIGS. 8A to 8C. When the engine is stopped, both the BSG pulley 3 and the crank pulley 5 are in a stopped state, as shown in FIG. At this time, due to the urging forces acting on the belt 6 from the first idler pulley 7 and the second idler pulley 8, the belt tension of the belt 6 where both the idler pulleys 7 and 8 are in contact is in a balanced state.

During normal operation (during power generation in BSG) shown in FIG. 7A, the crank pulley 5 drives the BSG pulley 3 via the belt 6, and the portion of the belt 6 running from the BSG pulley 3 toward the crank pulley 5 is tensioned. The part of the belt 6 running from the crank pulley 5 toward the BSG pulley 3 is the slack side. Then, the first pulley arm 9 receives the tension from the belt 6 and swings in one direction (see arrow r1 in FIG. 7A). At this time, as shown in FIG. 7B, a swing resistance is applied to the first pulley arm 9 due to the elastic deformation of the first swing resistance member 33, so that the swing of the first pulley arm 9 is suppressed. . On the other hand, the second pulley arm 10 swings in the opposite direction (see arrow r2 in FIG. 7A) to correspond to the slack in the belt 6. At this time, as shown in FIG. 7C, since no rocking resistance acts on the second pulley arm 10 from the second rocking resistance member 34, the second pulley arm 10 is moved toward the belt by the urging force of the elastic member 22. 6 swings smoothly in the direction of urging.

During the BSG operation shown in FIG. 8A (such as when restarting the engine after idling stop or assisting the engine's driving force), the BSG pulley 3 drives the crank pulley 5 via the belt 6, and the The part of the belt 6 that runs toward the BSG pulley 3 becomes the tight side, and the part of the belt 6 that runs from the BSG pulley 3 toward the crank pulley 5 becomes the slack side. Then, the second pulley arm 10 receives the tension from the belt 6 and swings in one direction (see arrow r2 in FIG. 8A). At this time, as shown in FIG. 8C, swing resistance acts on the second pulley arm 10 due to the elastic deformation of the second swing resistance member 34, so that the swing of the second pulley arm 10 is suppressed. . On the other hand, the first pulley arm 9 swings in the opposite direction (see arrow r1 in FIG. 8A) to correspond to the slack in the belt 6. At this time, as shown in FIG. 8B, since no swing resistance is generated from the first swing resistance member 33 to the first pulley arm 9, the first pulley arm 9 is moved by the biasing force of the elastic member 22. 6 swings smoothly in the direction of urging.

In the auto tensioner 1 described above, even when the pulley arms 9 and 10 swing so that the idler pulleys 7 and 8 separate from the belt 6 due to the tension of the belt 6 during normal operation or BSG operation, the swing resistance member The rocking resistances 33 and 34 suppress the rocking. Therefore, the optimal belt tension can be applied both during normal operation and during BSG operation, and excessive swinging of the pulley arms 9 and 10 can be suppressed to improve followability to the belt 6. I can do it.

In addition, in the auto tensioner 1 described above, since the rocking resistance members 33 and 34 are provided on the first pulley arm 9 and the second pulley arm 10, respectively, the engine can be restarted during normal operation and after idling stop. In any case, the belt tension can be maintained appropriately. Note that it is also possible to provide a configuration in which the swing resistance members 33 and 34 are provided only on one of the pulley arms 9 and 10.

In addition, in the above-mentioned autotensioner 1, since C-shaped circular arc members are used as the swing resistance members 33 and 34, the swing resistance from the swing fulcrum shaft 11 to the pulley arms 9 and 10 is achieved with a compact structure. can be granted. Moreover, the swing resistance members 33 and 34 are formed with bent portions 36a and 36b, and the bent portions 36a and 36b are provided in the receiving portions 17a and 17b, which are fan-shaped recesses formed in the pulley arms 9 and 10. Since rocking resistance is generated only in one direction of the rocking direction of the pulley arms 9 and 10, it is possible to instantly follow slack in the belt 6 while suppressing excessive rocking of the entire autotensioner 1. This allows the belt tension to be maintained appropriately.

In addition, in the above-mentioned autotensioner 1, when it is attached to the accessory drive system, the bent portions 36a and 36b formed on the swing resistance members 33 and 34 are connected to the receiving portions 17a and 17a formed on the pulley arms 9 and 10, respectively. Since the inner edges of the pulley arms 17b are brought into contact with a preload, when the pulley arms 9 and 10 swing in one direction, the swing resistance by the swing resistance members 33 and 34 can be quickly exerted.

Further, in the auto tensioner 1 described above, the axial center of the swing fulcrum shaft 11 is arranged on a line connecting the axial center of the crankshaft 4 and the axial center of the BSG drive shaft 2, and the first idler pulley 7 The lengths of the first pulley arm 9 and the second pulley arm 10 are determined so that the swing radius of the second idler pulley 8 is the same as the swing radius of the second idler pulley 8. The balance of the belt tension acting on the belt 6 is improved, and stable followability is exhibited.

Main parts of a modification of this autotensioner 1 are shown in FIGS. 9 to 11. The auto tensioner 1 according to the modification has the same basic configuration as the auto tensioner 1 described above, but differs in the configuration of the rocking resistance members 33 and 34. The rocking resistance members 33 and 34 used in this modification are torsion coil springs, and one end thereof is a terminal end portion 35a, 35b that terminates along the circumferential direction, while the other end side is a terminal end portion 35a, 35b that terminates in the radial direction. The bent portions 36a and 36b are bent outward. The swing resistance members 33 and 34 are provided on both sides in the axial direction of a flange 29 formed on the outer periphery of the main shaft 26, respectively. Similarly to the above, in the following, the swing resistance member 33 provided on the first fulcrum shaft 24 side will be referred to as the first swing resistance member 33, and the swing resistance member 34 provided on the second fulcrum shaft 25 side will be referred to as the first swing resistance member 33. They are respectively referred to as second rocking resistance members 34.

The first swing resistance member 33 and the second swing resistance member 34 are attached to the main shaft 26 in opposite directions. That is, the terminal end portion 35a of the first swing resistance member 33 contacts the contact portion 30 formed on the main shaft 26 from one direction in the circumferential direction, whereas the terminal end portion 35a of the second swing resistance member 34 contacts the contact portion 30 formed on the main shaft 26 from one direction in the circumferential direction. The terminal end portion 35b is in contact with the contact portion 30 formed on the main shaft 26 from the opposite direction in the circumferential direction. As shown in FIGS. 10 and 11, the bent portion 36a of the first swing resistance member 33 is connected to the receiving portion 17a formed in the small diameter cylindrical portion 14a of the first pulley arm 9. 34 bent portions 36b are provided in receiving portions 17b formed in the small diameter cylindrical portion 14b of the second pulley arm 10, respectively.

The swing resistance members 33 and 34 made of torsion coil springs are also connected from the swing fulcrum shaft 11 to the pulley arms 9 and 10 in the same way as the swing resistance members 33 and 34 made of C-shaped arcuate elastic materials explained above. can provide rocking resistance. Moreover, the swing resistance members 33 and 34 are formed with bent portions 36a and 36b, and the bent portions 36a and 36b are provided in the receiving portions 17a and 17b, which are fan-shaped recesses formed in the pulley arms 9 and 10. Since rocking resistance is generated only in one direction of the rocking direction of the pulley arms 9 and 10, it is possible to instantly follow slack in the belt 6 while suppressing excessive rocking of the entire autotensioner 1. This allows the belt tension to be maintained appropriately.

An autotensioner 1 according to a second embodiment of the present invention is shown in FIGS. 12 to 14. The auto tensioner 1 according to the second embodiment has the same basic configuration as the auto tensioner 1 according to the first embodiment, but has bent portions 36a and 36b formed on the other end sides of the rocking resistance members 33 and 34. The configurations of the receiving portions 17a and 17b that come into contact with are different. In the following, descriptions of common points with the first embodiment will be omitted, and mainly different configurations will be described.

In the autotensioner 1 according to the second embodiment, the small-diameter cylindrical portions 14a and 14b (the inner diameter surface of each pulley arm 9 and 10) of the first pulley arm 9 and the second pulley arm 10 have retainers that protrude radially inward. A portion 37 is formed. This holding portion 37 is formed at a position shifted from the slits 18a, 18b formed in the large diameter cylindrical portions 15a, 15b of each pulley arm 9, 10 in the circumferential direction.

An arm-side locking member 38, which is a separate member from each pulley arm 9, 10 and is made of a material with higher wear resistance than each pulley arm 9, 10, is provided on the inner diameter side of the small diameter cylindrical portions 14a, 14b. There is. In this embodiment, the pulley arms 9 and 10 are made of aluminum alloy, while the arm-side locking member 38 is made of steel. The arm-side locking member 38 is a substantially C-shaped member, and one end in the circumferential direction contacts the holding portion 37, and the other end in the circumferential direction contacts the bent portion 36a of the swing resistance members 33 and 34. , 36b act as receiving portions 17a, 17b in contact with each other. A gap is formed between the holding portion 37 and the other end of the arm-side locking member 38 and has a center angle comparable to that of the receiving portions 17a and 17b of the autotensioner 1 according to the first embodiment.

When each pulley arm 9, 10 swings in one direction (the direction shown by the arrow in FIGS. 13 and 14, respectively) with respect to the swing fulcrum shaft 11, the receiving portions 17a, 17b of each pulley arm 9, 10 and each swing As the resistance members 33, 34 come into contact with the bending portions 36a, 36b, the respective rocking resistance members 33, 34 are elastically deformed (see the states shown in FIGS. 13 and 14). As a result, rocking resistance acts on each pulley arm 9, 10. On the other hand, when each pulley arm 9, 10 swings in the opposite direction with respect to the swing fulcrum shaft 11, the receiving portions 17a, 17b of each pulley arm 9, 10, the bent portion 36a of each swing resistance member 33, 34, 36b, and each pulley arm 9, 10 can swing in the opposite direction without receiving any swing resistance from each swing resistance member 33, 34.

In the auto tensioner 1 according to the second embodiment, the receiving parts 17a and 17b are made of the arm-side locking members 38 made of a material with higher wear resistance than the pulley arms 9 and 10, so that the swing resistance members 33 and 34 are It is possible to prevent the receiving portions 17a, 17b from being worn out as much as possible due to the other end repeatedly coming into contact with the receiving portions 17a, 17b, and the durability of the auto tensioner 1 can be increased. Moreover, the arm-side locking member 38 has a simple approximately C-shape and is easy to assemble. Even if wear occurs due to long-term use, it is only necessary to replace the arm-side locking member 38, and the pulley arm Since 9 and 10 themselves can be used as they are, maintenance costs can be suppressed.

An autotensioner 1 according to a third embodiment of the present invention is shown in FIGS. 15 to 17. The auto tensioner 1 according to the third embodiment also has the same basic configuration as the auto tensioner 1 according to the first embodiment, but has bent portions 36a and 36b formed on the other end sides of the rocking resistance members 33 and 34. The configurations of the receiving portions 17a and 17b that come into contact with are different.

In the auto tensioner 1 according to the third embodiment, the small diameter cylindrical portions 14a, 14b of the first pulley arm 9 and the second pulley arm 10 are separate members from each pulley arm 9, 10, and each pulley arm 9, 10 An arm-side locking member 38 made of a material with higher wear resistance than that of the arm-side locking member 38 is provided. In this embodiment, the pulley arms 9 and 10 are made of aluminum alloy, while the arm-side locking member 38 is made of steel. The arm-side locking member 38 is a pin-shaped member that is erected along the axial direction on the axial end surface of the small diameter cylindrical portions 14a, 14b.

This pin-shaped arm-side locking member 38 is inserted into an insertion hole extending in the axial direction formed in the axial end face of the small diameter cylindrical portions 14a, 14b, or embedded when the pulley arms 9, 10 are cast. By being integrated with the pulley arms 9 and 10 (small diameter cylindrical portions 14a and 14b), they function as receiving portions 17a and 17b.

The circumferential positional relationship between the arm-side locking member 38 and the bending portions 36a, 36b of the swing resistance members 33, 34 when the opening angle between both pulley arms 9, 10 changes is shown in FIGS. 18A to 18C. In each of these figures, only the arm-side locking member 38 and the bent portion 36b of the swing resistance member 34 of one pulley arm 10 of both pulley arms 9 and 10 are shown, and the arm-side locking member 38 of the other pulley arm 9 is shown. The description of the stop member 38 and the bent portion 36a of the swing resistance member 33 is omitted.

When the opening angle between both pulley arms 9 and 10 is relatively small, as shown in FIG. 18A, the arm-side locking member 38 and the bending portion 36b of the swing resistance member 34 are spaced apart in the radial direction, and the swing Both the terminal end portion 35b and the bent portion 36b of the dynamic resistance member 34 are in contact with the contact portion 30 of the main shaft 26. At this time, no rocking resistance acts on the pulley arm 10 from the rocking resistance member 34.

As the opening angle of both pulley arms 9 and 10 gradually increases, the arm-side locking member 38 integrated with the pulley arm 10 also rotates with respect to the main shaft 26, and as shown in FIG. 18B, the arm-side locking member 38 and the swinging The bent portion 36b of the dynamic resistance member 34 makes contact. At this time, rocking resistance is not yet acting on the pulley arm 10 from the rocking resistance member 34.

When the opening angle between both pulley arms 9 and 10 becomes even larger, the bent portion 36b of the swing resistance member 34 is pressed by the arm-side locking member 38, and the bent portion 36b is separated from the contact portion 30, as shown in FIG. 18C. Becomes separated. At this time, since the contact between the terminal end portion 35b and the abutment portion 30 is maintained, the swing resistance member 34 is pushed outward in the radial direction and is in an enlarged diameter state. In this expanded diameter state, swing resistance acts on the pulley arm 10 from the swing resistance member 34. The magnitude of this rocking resistance increases as the opening angle between both pulley arms 9 and 10 increases.

Since the auto tensioner 1 according to the third embodiment employs a pin-shaped member as the arm side locking member 38, for example, the approximately C-shaped arm side locking member 38 adopted in the auto tensioner 1 according to the second embodiment It is possible to achieve a reduction in size and weight compared to the previous model. Further, by integrating the arm-side locking member 38 with the pulley arms 9 and 10 in advance, the assembly process can be simplified and manufacturing costs can be suppressed.

An autotensioner 1 according to a fourth embodiment of the present invention is shown in FIGS. 19 to 23. The auto tensioner 1 according to the fourth embodiment also has the same basic configuration as the auto tensioner 1 according to the first embodiment, but a swing resistance member is provided between the first pulley arm 9 and the second pulley arm 10. The difference is that a sealing member 39 is provided to prevent leakage of the lubricant applied to the contact portions between the receiving portions 33 and 34 and the receiving portions 17a and 17b.

This sealing member 39 has a ring shape with a T-shaped cross section, and is arranged so that the T-shaped protrusion is sandwiched between the outer peripheral edges of the small diameter cylindrical portions 14a and 14b of both pulley arms 9 and 10. This seal member 39 forms a closed space on the inner diameter side of the small diameter cylindrical portions 14a, 14b. The shape of the seal member 39 shown here is merely an example, and a seal having a simple labyrinth structure, a contact seal, an O-ring, or the like may also be employed. Further, as the lubricant, a base oil made of a heat-resistant synthetic oil containing a solid lubricant can be used.

In this embodiment, in addition to lubrication with a lubricant, the surfaces of the rocking resistance members 33, 34 and the receiving portions 17a, 17b are treated with solid lubrication to form a solid lubrication layer 40, thereby improving lubricity and durability. Efforts are being made to improve wear resistance. When the material of the receiving parts 17a and 17b is an aluminum alloy, the surfaces thereof can be subjected to alumite treatment. Furthermore, wear resistance can be improved by forming a plating layer using hardened chromium plating, electroless nickel plating, ion plating, or the like instead of the solid lubricant layer 40.

Further, instead of forming the solid lubricant layer 40 and the plating layer described above, or in addition to forming these, a hard layer may be formed on the surfaces of the receiving portions 17a and 17b by various heat treatments such as tempering heat treatment, carburizing heat treatment, and carbonitriding heat treatment. Abrasion resistance can also be improved by forming a .

The auto tensioner 1 according to the fourth embodiment is provided with a seal member 39 and then applies lubricant to the contact portions between the rocking resistance members 33 and 34 and the receiving portions 17a and 17b to prevent leakage of this lubricant. In addition, since the solid lubricant layer 40 is formed on the surfaces of the rocking resistance members 33, 34 and the receiving portions 17a, 17b, the lubricity and wear resistance are improved, and the durability of the autotensioner 1 can be improved.

An autotensioner 1 according to a fifth embodiment of the present invention is shown in FIGS. 24 to 26. The auto tensioner 1 according to the fifth embodiment, like the auto tensioner 1 according to the second embodiment, is a separate member from each pulley arm 9, 10, and is made of a material with higher wear resistance than each pulley arm 9, 10. The main shaft 26 has a substantially C-shaped arm-side locking member 38 in common, but as shown in FIG. A lubricant that stores the lubricant supplied between the swing fulcrum shaft 11 and the swing resistance members 33 and 34 between the contact portion 30 of the main shaft 26 and the inner peripheral surfaces of the swing resistance members 33 and 34. The difference is that a reservoir 42 is formed.

When lubricating with a lubricant, when an elastic force is generated in the swing resistance members 33 and 34, the swing resistance members 33 and 34 are pushed toward the mating member ( receptacles 17a, 17b, etc.) that they come into contact with. The lubricant may be forced out on the contact surface, resulting in insufficient lubrication. Therefore, by forming the lubricant reservoir 42, if the lubricant is about to be pushed out from between the swing resistance members 33, 34, the receiving parts 17a, 17b, and the swing fulcrum shaft 11 due to contact with them. However, since this lubricant tends to remain in the lubricant reservoir 42, lubricity at the contact area between the two is maintained.

FIG. 28 shows the main parts of an autotensioner 1 according to a sixth embodiment of the present invention. The auto tensioner 1 according to the sixth embodiment, like the auto tensioner 1 according to the second embodiment, is a separate member from each pulley arm 9, 10, and is made of a material with higher wear resistance than each pulley arm 9, 10. However, as shown in FIGS. 28 and 29, the receiving portions 17a, 17b of the arm side locking member 38 and the main shaft 26 are The difference is that an oil groove 43 that extends in the axial direction along the swing resistance members 33 and 34 is formed as a lubricant reservoir 42 on the outer circumferential surface of the contact portion 30 and the main shaft 26 .

In this way, by forming the lubricant reservoir 42 as the oil groove 43, the effect of keeping the lubricant at the position where the oil groove 43 is formed can be further improved, so that the swing resistance members 33, 34 and the other side The lubricity at the contact portion between the members can be further improved. Furthermore, if the surface roughness within this oil groove 43 is made larger than the surface roughness of the surface of the main shaft 26 in contact with the rocking resistance members 33 and 34, the lubricant retention force in the oil groove 43 increases, and the rocking resistance member 33 , 34 and the receiving portions 17a, 17b and the swing fulcrum shaft 11 can be further improved in lubricity.

In this embodiment, as shown in FIG. 30A, the cross-sectional shape of the oil groove 43 is R-shaped with a rounded bottom, but as shown in FIG. 30B, it may also be wedge-shaped with a pointed bottom. The holding power is demonstrated. The formation position, number, cross-sectional shape, depth, etc. of the oil grooves 43 can be changed as appropriate as long as the lubricant holding power is sufficiently exerted.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

2 BSG drive shaft (auxiliary drive shaft)
3 BSG pulley (auxiliary pulley)
4 Crankshaft 5 Crank pulley 6 Auxiliary belt (belt)
7 First idler pulley 8 Second idler pulley 9 First pulley arm 10 Second pulley arm 11 Swing fulcrum shafts 17a, 17b Receiving portion 22 Elastic member 33 First swing resistance member 34 Second swing resistance Members 36a, 36b Bent portion 37 Holding portion 38 Arm-side locking member 40 Solid lubricant layer 42 Lubricant reservoir 43 Oil groove

Claims (18)

1. a first pulley arm (9) supporting a first idler pulley (7) in contact with an auxiliary belt (6);
   a second pulley arm (10) supporting a second idler pulley (8) in contact with the accessory belt (6);
   a swing fulcrum shaft (11) that swingably supports the first pulley arm (9) and the second pulley arm (10);
   an elastic member that biases the second pulley arm (10) against the first pulley arm (9) so that the first idler pulley (7) and the second idler pulley (8) approach each other; (22) and
   Swing resistance members (33, 34) that generate swing resistance only in one direction of each swing direction with respect to the first pulley arm (9) and the second pulley arm (10);
   Auto tensioner with.
2. When the first idler pulley (7) or the second idler pulley (8) is pushed by the tension of the auxiliary belt (6), the one direction is set to the first pulley arm (9) or the second idler pulley (8). Autotensioner according to claim 1, characterized in that the direction in which the second pulley arm (10) swings.
3. The autotensioner according to claim 1 or 2, wherein the swing resistance member (33, 34) is provided on each of the first pulley arm (9) and the second pulley arm (10).
4. The swing resistance members (33, 34) are made of an elastic material having a C-shaped arc, and one end of the arc is locked to the swing fulcrum shaft (11), while the other end is fixed to the swing fulcrum shaft (11). The first pulley arm (9) and the second pulley arm (10) are provided in receiving portions (17a, 17b) formed in the first pulley arm (9) and the second pulley arm (10). When swinging in the one direction, the other end side engages with the receiving portion (17a, 17b) and the swing resistance member (33, 34) is elastically deformed, so that the first pulley arm ( 9) and the second pulley arm (10) to generate rocking resistance.
5. The swing resistance members (33, 34) are torsion coil springs, one end of which is locked to the swing fulcrum shaft (11), and the other end of which is locked to the first pulley arm (9) and the swing fulcrum shaft (11). It is provided in the receiving portions (17a, 17b) formed in the second pulley arm (10), and when the first pulley arm (9) and the second pulley arm (10) swing in the one direction. When the other end side engages with the receiving portion (17a, 17b) and the swing resistance member (33, 34) is elastically deformed, the first pulley arm (9) and the second pulley arm The auto tensioner according to claim 1 or 2, wherein (10) generates rocking resistance.
6. The receiving portions (17a, 17b) are fan-shaped recesses formed in the inner diameter surfaces of the first pulley arm (9) and the second pulley arm (10), and 5. The autotensioner according to claim 4, wherein the other end side of the tensioner is a bent portion (36a, 36b) bent radially outward so as to be able to engage with the receiving portion (17a, 17b).
7. The inner diameter surfaces of the first pulley arm (9) and the second pulley arm (10) are provided with a material that is a separate member from the respective pulley arms (9, 10) and is more resistant to wear than the respective pulley arms (9, 10). An arm-side locking member (38) with high resistance is provided, and the receiving portions (17a, 17b) are circumferential ends of the arm-side locking member (38), and the swing resistance member The auto tensioner according to claim 4, wherein the other end side of the (33, 34) is a bent part (36a, 36b) bent radially outward so as to be able to engage with the receiving part (17a, 17b). .
8. The arm-side locking member (38) is a substantially C-shaped member, and one end of the arm side locking member (38) in the circumferential direction is radially connected to the inner diameter surface of the first pulley arm (9) and the second pulley arm (10). The receiving portion (17a) contacts the holding portion (37) formed to protrude inwardly, while the other end of the receiving portion (17a) in the circumferential direction engages with the other end of the swing resistance member (33, 34). , 17b).
9. The autotensioner according to claim 7, wherein the arm-side locking member (38) is integrated with the first pulley arm (9) and the second pulley arm (10).
10. When attached to the auxiliary belt (6), the other end sides of the swing resistance members (33, 34) contact the receiving portions (17a, 17b), and the first pulley arm (9) and The autotensioner according to claim 4, wherein the second pulley arm (10) is preloaded in the one direction.
11. The autotensioner according to claim 4, wherein a lubricant is provided in the rocking resistance member (33, 34) and the receiving portion (17a, 17b).
12. The auto according to claim 11, wherein a lubricant reservoir (42) for storing the lubricant supplied between the swing fulcrum shaft (11) and the swing resistance member (33, 34) is formed. tensioner.
13. The lubricant reservoir (42) is formed in at least one of the swing fulcrum shaft (11) and the receiving part (17a, 17b) along the swing resistance member (33, 34). The autotensioner according to claim 12, which is a groove (43).
14. The autotensioner according to claim 13, wherein the surface roughness of the inner surface of the oil groove (43) is greater than the surface roughness of the outer surface of the swing fulcrum shaft (11).
15. A solid lubricant layer (40) or formed by hardened chromium plating, electroless nickel plating, or ion plating on the surface of at least one of the rocking resistance member (33, 34) and the receiving part (17a, 17b). The autotensioner according to claim 4, further comprising a plating layer.
16. The autotensioner according to claim 4, wherein a hard layer is formed on the surface of the receiving portion (17a, 17b) by tempering heat treatment, carburizing heat treatment, or carbonitriding heat treatment.
17. The accessory belt (6) is stretched across a crank pulley (5) attached to a crankshaft (4) of the engine and an accessory pulley (3) attached to an accessory drive shaft (2). Claim 1 or 2, wherein the axial center of the swing fulcrum shaft (11) is arranged on a line connecting the axial center of the crankshaft (4) and the axial center of the auxiliary drive shaft (2). The auto tensioner described in 2.
18. The first pulley arm (9) and the second pulley arm (10) are arranged so that the swing radius of the first idler pulley (7) and the swing radius of the second idler pulley (8) are the same. 18. The autotensioner according to claim 17, wherein the length of the tensioner is determined.

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