Auto tensioner

Abstract

To provide a highly durable auto tensioner capable of imparting optimum belt tension by a simple configuration, and securing high followability by suppressing excessive oscillation of a pulley arm.SOLUTION: An auto tensioner includes: a first pulley arm 9; a second pulley arm 10; oscillating fulcrums 11 for supporting the two pulley arms 9 and 10 in an oscillating manner; an elastic member 22 for energizing the second pulley arm 10 to the first pulley arm 9 so that first and second idler pulleys 7 and 8 get closer to each other; oscillating resistance members 34 and 35 for generating oscillating resistance to the two pulley arms 9 and 10 only in one direction of each oscillating direction; and a stopper member 32 to regulate an oscillating angle in the one direction for at least one of the oscillating fulcrums 11 of the first pulley arm 9 and the second pully arm 10 to a predetermined angle or less while keeping the same phase around the axis with the oscillating fulcrum 11.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an auto-tensioner used for a belt system for driving auxiliary machines of an automotive engine, a timing belt, and the like.

Background Art

[0002] In recent years, in a belt system for driving auxiliary machines of an automotive engine, in addition to the functions of a conventional alternator, a belt starter generator (hereinafter abbreviated as BSG) that performs engine restart after idling stop and engine power assist during driving has been mounted on an increasing number of mild hybrid vehicles. This belt drive system for auxiliary machines has a belt drive device that transmits power by a belt (hereinafter referred to as a belt) stretched across between a crank pulley provided on the crankshaft of the engine and a pulley provided on the drive shaft of the BSG (hereinafter referred to as a BSG pulley).

[0003] This belt drive device has a feature that the tension side and the slack side of the belt are switched between normal operation in which the crank pulley drives and engine restart after idling stop or drive assist during driving in which the BSG pulley drives.

[0004] That is, during normal operation in which the BSG operates as a generator, the crank pulley drives the BSG pulley via the belt, so the portion of the belt traveling from the BSG pulley toward the crank pulley becomes the tension side, and the portion of the belt traveling from the crank pulley toward the BSG pulley becomes the slack side. On the other hand, during engine restart after idling stop by the BSG or drive assist during driving, the BSG pulley drives the crank pulley via the belt, so the portion of the belt traveling from the crank pulley toward the BSG pulley becomes the tension side, and the portion of the belt traveling from the BSG pulley toward the crank pulley becomes the slack side.

[0005] An autotensioner is used to prevent such belt slack and properly adjust the belt tension. In a configuration where the slack side of the belt changes between normal operation and engine restart, such as in a mild hybrid vehicle, for example, as shown in Patent Document 1, pulley of the autotensioner are arranged on the belt spans on both sides of the BSG pulley, and these pulleys are connected to be relatively movable by an intermediate member to interlock the pulleys with each other, thereby adjusting the belt tension during normal operation and engine restart after idling stop.

[0006] Also, as shown in Patent Document 2, after two pulley arms are respectively supported so as to be swingable by a swing fulcrum shaft, both pulley arms are biased by an elastic member so as to approach each other, and a swing resistance member composed of a C-shaped leaf spring or a coil spring is used to cause a swing resistance in only one direction of the respective swing directions of each pulley arm. According to this configuration, due to the swing resistance in one direction by the swing resistance member, an optimal belt tension can be applied in any case such as during normal operation and engine restart after idling stop, and excessive swing of the pulley arm can be suppressed to improve the followability to the accessory belt.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] When applying the conventional automatic tensioner shown in Patent Document 1 to a mild hybrid vehicle, by arranging automatic tensioners on the belt spans on both sides of the BSG pulley, the belt tension during normal operation and during engine restart after idling stop can be adjusted. However, since the automatic tensioners are arranged at two locations, there are problems that the weight and cost increase, and the assembly and replacement work become complicated.

[0009] Also, in the configuration shown in Patent Document 2, when a belt load larger than expected acts, the pulley arm swings greatly, and a large load acts due to the swing resistance member that resists the swing of the pulley arm deforming more than expected, and there is a risk that its durability will decrease.

[0010] The problem to be solved by the present invention is to be able to apply an optimal belt tension with a simple configuration during normal operation and during engine restart after idling stop, etc., and to suppress excessive swinging of the pulley arm and ensure high followability, and to provide an automatic tensioner having high durability.

Means for Solving the Problem

[0011] To solve the above problems, in the present invention, a first pulley arm that supports a first idler pulley that contacts the accessory belt, a second pulley arm that supports 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 biases the second pulley arm with respect 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 only in one direction of the respective swing directions with respect to the first pulley arm and the second pulley arm, A stopper member that regulates the swinging angle in the one direction with respect to the swinging fulcrum shaft of at least one of the first pulley arm or the second pulley arm to a predetermined angle or less while maintaining the same phase around the shaft as the swinging fulcrum shaft; An auto-tensioner having the same was configured.

[0012] By doing so, the optimal belt tension can be applied in both normal operation and when the engine is restarted after idling stop, etc., due to the swinging resistance in one direction by the swinging resistance member, and excessive swinging of the pulley arm can be suppressed and the followability to the accessory belt can be improved. Also, since the swinging angle is regulated to a predetermined angle or less by the stopper member, the load acting on the swinging resistance member is reduced, and the durability of this swinging resistance member can be improved.

[0013] In the above configuration, An insertion hole for inserting the swinging fulcrum shaft is formed in the stopper member, and the cross-sectional shape of the insertion end of the swinging fulcrum shaft into the insertion hole and the shape of the insertion hole are preferably formed in the same shape other than circular. In particular, it is preferable that the cross-sectional shape of the insertion end is a D shape or a key fitting shape.

[0014] By doing so, the in-phase state between the swinging fulcrum shaft and the stopper member is maintained, and when the pulley arm swings by the predetermined angle with respect to the swinging fulcrum shaft, the stopper member can surely prevent swinging exceeding that angle.

[0015] In all of the above configurations, It is preferable that a washer is inserted through the end of the swinging fulcrum shaft, and the washer and the stopper member are integrally formed.

[0016] By doing so, the assembly process is simplified, and the manufacturing cost can be reduced.

Advantages of the Invention

[0017] By configuring the auto-tensioner as described above, the optimal belt tension can be applied in both normal operation and engine restart after idling stop, etc., due to the one-way swinging resistance of the swinging resistance member, and excessive swinging of the pulley arm can be suppressed to enhance the followability to the accessory belt. Also, since the swinging angle is regulated to a predetermined angle or less by the stopper member, the load acting on the swinging resistance member is reduced, and the durability of this swinging resistance member can be improved.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

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Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiment for Carrying Out the Invention

[0019] An example of an accessory drive system using the auto-tensioner 1 according to the present invention is shown in FIGS. 1 and 2. This accessory drive system includes a BSG pulley 3 attached to a BSG drive shaft 2 (accessory drive shaft) of a belt starter generator (hereinafter abbreviated as BSG), a crank pulley 5 attached to a crankshaft 4, an accessory belt 6 (hereinafter simply abbreviated as belt 6) stretched across between the BSG pulley 3 and the crank pulley 5, and an auto-tensioner 1 for maintaining the tension of the belt 6 within an appropriate range.

[0020] The auto-tensioner 1 will be described with reference to FIGS. 2 to 9. This auto-tensioner 1 includes a first idler pulley 7, a second idler pulley 8, a first pulley arm 9 that supports the first idler pulley 7, a second pulley arm 10 that supports the second idler pulley 8, and a swing fulcrum shaft 11 that swingably supports the first pulley arm 9 and the second pulley arm 10.

[0021] The first idler pulley 7 is in contact with the outer peripheral surface of a portion of the belt 6 that runs from the BSG pulley 3 toward the crank pulley 5. Also, the second idler pulley 8 is in contact with the outer peripheral surface of a portion of the belt 6 that runs from the crank pulley 5 toward the BSG pulley 3. The axis of the swing fulcrum shaft 11 that supports both pulley arms 9 and 10 is arranged on a line connecting the axis of the crankshaft 4 and the axis of the BSG drive shaft 2.

[0022] The first pulley arm 9 and the second pulley arm 10 have base portions 12a, 12b (hereinafter, a is attached to the elements on the first pulley arm 9 side and b is attached to the elements on the second pulley arm 10 side), and extending pieces 13a, 13b extending radially outward from the base portions 12a, 12b. The first pulley arm 9 and the second pulley arm 10 are arranged such that their respective base portions 12a, 12b are arranged axially, and their respective extending pieces 13a, 13b are at different positions in the circumferential direction.

[0023] The base portions 12a, 12b are composed of concentric cylindrical small-diameter cylindrical portions 14a, 14b and large-diameter cylindrical portions 15a, 15b. One axial end portions of the small-diameter cylindrical portions 14a, 14b and the large-diameter cylindrical portions 15a, 15b are connected by flanges 16a, 16b extending in the radial direction. Sector-shaped recessed receiving portions 17a, 17b are formed in a part of the circumferential direction of the cylinders of the small-diameter cylindrical portions 14a, 14b (the inner diameter surfaces of the pulley arms 9, 10). In this embodiment, the central angles of the receiving portions 17a, 17b are about 50 degrees, but can be appropriately changed within a range of, for example, 20 degrees or more and 80 degrees or less. Slits 18a, 18b are formed in a part of the circumferential direction of the cylinders of the large-diameter cylindrical portions 15a, 15b. The receiving portions 17a, 17b and the slits 18a, 18b are formed at positions shifted from each other in the circumferential direction. Slide bearings 19a, 19b are press-fitted on the inner diameter sides of the small-diameter cylindrical portions 14a, 14b.

[0024] Through holes 21a, 21b for passing the rotation shafts 20a, 20b of the first idler pulley 7 and the second idler pulley 8 are formed at the tips of the extending pieces 13a, 13b. The lengths of the first pulley arm 9 and the second pulley arm 10 are determined such that the swing radius of the first idler pulley 7 (the distance from the axial center position of the swing fulcrum shaft 11 to the contact point between the first idler pulley 7 and the belt 6) and the swing radius of the second idler pulley 8 (the distance from the axial center position of the swing fulcrum shaft 11 to the contact point between the second idler pulley 8 and the belt 6) are the same. Here, the term "same" includes not only complete identity but also cases having some differences as long as they do not significantly affect the tension of the belt 6.

[0025] A common elastic member 22 is provided across both pulley arms 9 and 10 in the radial clearance between the small-diameter cylindrical portions 14a and 14b and the large-diameter cylindrical portions 15a and 15b of the first pulley arm 9 and the second pulley arm 10. This elastic member 22 is a steel coil spring. Both ends of this elastic member 22 are bent into bent pieces 23a and 23b that bend radially outward. The bent piece 23a on one end side is locked to a slit 18a formed in the large-diameter cylindrical portion 15a of the first pulley arm 9, and the bent piece 23b on the other end side is locked to a slit 18b formed in the large-diameter cylindrical portion 15b of the second pulley arm 10. By this elastic member 22, in the state of being attached to the auxiliary machine drive system, the second pulley arm 10 is biased with respect to the first pulley arm 9 so that the first idler pulley 7 and the second idler pulley 8 approach each other.

[0026] 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 that connects the first fulcrum shaft 24 and the second fulcrum shaft 25 by press-fitting. Both the first fulcrum shaft 24 and the second fulcrum shaft 25 are cylindrical members, and reduced-diameter portions 27a and 27b with an outer diameter smaller than other places are formed at the ends facing the main shaft 26. Further, stepped press-fitting stepped portions 28a and 28b are formed at the axial ends on the opposite sides of the reduced-diameter portions 27a and 27b formed on the first fulcrum shaft 24 and the second fulcrum shaft 25.

[0027] The main shaft 26 is a cylindrical member, and at the central portion in its axial direction, a flange 29 standing upright radially outward is formed over the entire circumference in the circumferential direction. Further, at one location in the circumferential direction of the main shaft 26, a contact portion 30 standing upright radially outward and extending along the axial direction is formed. By press-fitting the reduced-diameter portions 27a of the first fulcrum shaft 24 and the reduced-diameter portions 27b of the second fulcrum shaft 25 into both ends of the main shaft 26 respectively, they are integrated. Washers 31 are press-fitted into the press-fitting stepped portions 28a, 28b formed at both ends of the first fulcrum shaft 24 and the second fulcrum shaft 25 integrated with the main shaft 26. On the outer side in the axial direction of the washer 31 provided on the second fulcrum shaft 25 side, a stopper member 32 for restricting the swing angle of the swing fulcrum shaft 11 of the first pulley arm 9 and the second pulley arm 10 to a predetermined angle or less is provided. In this embodiment, the washer 31 and the stopper member 32 are integrally formed, but they can also be formed as separate members. A bolt 33 for fixing this auto-tensioner 1 to the engine E or the like is inserted through the axis of the swing fulcrum shaft 11.

[0028] The first fulcrum shaft 24 is disposed on the inner diameter side of the sliding bearing 19a press-fitted into the small-diameter cylindrical portion 14a of the first pulley arm 9, and the second fulcrum shaft 25 is disposed on the inner diameter side of the sliding bearing 19b press-fitted into the small-diameter cylindrical portion 14b of the second pulley arm 10.

[0029] Swing resistance members 34, 35 for generating swing resistance only in one direction in the respective swing directions are provided on the swing fulcrum shaft 11 with respect to the first pulley arm 9 and the second pulley arm 10. These swing resistance members 34, 35 are formed of an elastic material having a C-shaped arc shape. One end side on the arc is formed as terminal portions 36a, 36b that terminate along the circumferential direction, while the other end side is formed as bent portions 37a, 37b that bend radially outward. The swing resistance members 34, 35 are respectively provided on both axial sides of the flange 29 formed on the outer circumference of the main shaft 26. Hereinafter, the swing resistance member 34 provided on the first fulcrum shaft 24 side is referred to as the first swing resistance member 34, and the swing resistance member 35 provided on the second fulcrum shaft 25 side is referred to as the second swing resistance member 35.

[0030] The first swing resistance member 34 and the second swing resistance member 35 are attached in opposite directions with respect to the main shaft 26. That is, the end portion 36a of the first swing resistance member 34 abuts against the abutting portion 30 formed on the main shaft 26 from one direction in the circumferential direction, while the end portion 36b of the second swing resistance member 35 abuts against the abutting portion 30 formed on the main shaft 26 from the opposite direction in the circumferential direction. The bent portion 37a of the first swing resistance member 34 is provided in the receiving portion 17a formed in the small-diameter cylindrical portion 14a of the first pulley arm 9, and the bent portion 37b of the second swing resistance member 35 is provided in the receiving portion 17b formed in the small-diameter cylindrical portion 14b of the second pulley arm 10, respectively.

[0031] The bent portions 37a and 37b formed in the first swing resistance member 34 and the second swing resistance member 35 are allowed to move within the angular range of the central angle of the receiving portions 17a and 17b formed in the small-diameter cylindrical portions 14a and 14b of the first pulley arm 9 or the second pulley arm 10. In the attached state to the auxiliary machine drive system, the bent portions 37a and 37b are in contact with the inner edges at one end in the circumferential direction of the receiving portions 17a and 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 37a and 37b contact are opposite, but in any of the pulley arms 9 and 10, the direction from one end in the circumferential direction where the bent portions 37a and 37b contact the inner edges of the receiving portions 17a and 17b to the other end in the circumferential direction of the receiving portions 17a and 17b is referred to as the "one direction", and the direction opposite to the one direction is referred to as the "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.

[0032] 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, with the contact between the inner edge of the receiving portion 17a formed on the first pulley arm 9 and the bent portion 37a of the first swing resistance member 34, the first swing resistance member 34 elastically deforms. Thereby, a swing resistance acts on the first pulley arm 9. On the other hand, when the first pulley arm 9 swings in the reverse direction with respect to the swing fulcrum shaft 11, the space between the inner edge of the receiving portion 17a formed on the first pulley arm 9 and the bent portion 37a of the first swing resistance member 34 becomes separated, and the first pulley arm 9 can swing in the reverse direction without receiving the swing resistance from the first swing resistance member 34.

[0033] Also, when the second pulley arm 10 shown in FIG. 5 swings in one direction (the direction indicated by the arrow in FIG. 5) with respect to the swing fulcrum shaft 11, with the contact between the inner edge of the receiving portion 17b formed on the second pulley arm 10 and the bent portion 37b of the second swing resistance member 35, the second swing resistance member 35 elastically deforms. Thereby, a swing resistance acts on the second pulley arm 10. On the other hand, when the second pulley arm 10 swings in the reverse direction with respect to the swing fulcrum shaft 11, the space between the inner edge of the receiving portion 17b formed on the second pulley arm 10 and the bent portion 37b of the second swing resistance member 35 becomes separated, and the second pulley arm 10 can swing in the reverse direction without receiving the swing resistance from the second swing resistance member 35.

[0034] As shown in FIG. 8, the stopper member 32 has a flat plate portion 38 that is substantially V-shaped in a plan view having a plane normal parallel to the swing fulcrum axis 11, and a first contact piece 39a and a second contact piece 39b that extend along the plane normal of the flat plate portion 38 from the outer edges of both ends of the V-shape. The first contact piece 39a is configured to be able to contact the first pulley arm 9 when the first pulley arm 9 and the second pulley arm 10 rotate away from each other, and the second contact piece 39b is configured to be able to contact the second pulley arm 10 when the first pulley arm 9 and the second pulley arm 10 rotate away from each other. In this embodiment, since the stopper member 32 is provided along the second pulley arm 10, the first contact piece 39a that contacts the first pulley arm 9 is configured to have a longer extension length from the flat plate portion 38 than the second contact piece 39b that contacts the second pulley arm 10.

[0035] As shown in FIGS. 8 and 9, an insertion hole 41 for inserting the insertion end portion 40 (press-fitting step portion 28b) of the swing fulcrum axis 11 (second fulcrum axis 25) is formed in the central portion of the flat plate portion 38. In this embodiment, both the cross-sectional shape of the insertion end portion 40 and the shape of the insertion hole 41 are D-shaped. In this way, by making the cross-sectional shape of the insertion end portion 40 and the shape of the insertion hole 41 the same shape, the same phase state around the axis is maintained between the swing fulcrum axis 11 and the stopper member 32. Note that the cross-sectional shape of the insertion end portion 40 of the swing fulcrum axis 11 and the shape of the insertion hole 41 may be formed in the same shape other than circular. For example, as shown in FIG. 10, the insertion end portion 40 and the insertion hole 41 can also be formed in a key fitting shape.

[0036] An operation example of this auto-tensioner 1 will be described with reference to FIGS. 1, 11 to 14. When the engine is stopped, as shown in FIG. 1, both the BSG pulley 3 and the crank pulley 5 are in a stopped state. At this time, due to the biasing force acting on the belt 6 from the first idler pulley 7 and the second idler pulley 8, the belt tension of the belt 6 with which both idler pulleys 7 and 8 are in contact is in a balanced state.

[0037] During normal operation (when generating electricity in the BSG) shown in Fig. 11(a), the crank pulley 5 drives the BSG pulley 3 via the belt 6. The portion of the belt 6 running from the BSG pulley 3 towards the crank pulley 5 becomes the tension side, and the portion of the belt 6 running from the crank pulley 5 towards the BSG pulley 3 becomes the slack side. Then, the first pulley arm 9 swings in one direction (see arrow r1 in Fig. 11(a)) under the tension from the belt 6. At this time, as shown in Fig. 11(b), due to the elastic deformation of the first swing resistance member 34, a swing resistance acts on the first pulley arm 9, thus suppressing the swing of the first pulley arm 9. On the other hand, the second pulley arm 10 swings in the opposite direction (see arrow r2 in Fig. 11(a)) to accommodate the slack of the belt 6. At this time, as shown in Fig. 11(c), since no swing resistance acts on the second pulley arm 10 from the second swing resistance member 35, the second pulley arm 10 smoothly swings in the direction of urging the belt 6 by the biasing force of the elastic member 22.

[0038] During BSG operation (such as when restarting the engine after idling stop or assisting the driving force of the engine) shown in Fig. 12(a), the BSG pulley 3 drives the crank pulley 5 via the belt 6. The portion of the belt 6 running from the crank pulley 5 towards the BSG pulley 3 becomes the tension side, and the portion of the belt 6 running from the BSG pulley 3 towards the crank pulley 5 becomes the slack side. Then, the second pulley arm 10 swings in one direction (see arrow r2 in Fig. 12(a)) under the tension from the belt 6. At this time, as shown in Fig. 12(c), due to the elastic deformation of the second swing resistance member 35, a swing resistance acts on the second pulley arm 10, thus suppressing the swing of the second pulley arm 10. On the other hand, the first pulley arm 9 swings in the opposite direction (see arrow r1 in Fig. 12(a)) to accommodate the slack of the belt 6. At this time, as shown in Fig. 12(b), since no swing resistance occurs on the first pulley arm 9 from the first swing resistance member 34, the first pulley arm 9 smoothly swings in the direction of urging the belt 6 by the biasing force of the elastic member 22.

[0039] During normal operation and BSG operation, when a belt load larger than expected acts on each pulley arm 9, 10 from the belt 6 and each pulley arm 9, 10 swings greatly, and when the swing angle in the one direction with respect to the swing fulcrum shaft 11 reaches a predetermined angle, as shown in FIG. 13, the first contact piece 39a contacts the first pulley arm 9, or as shown in FIG. 14, the second contact piece 39b contacts the second pulley arm 10, the swing angle of each pulley arm 9, 10 in the one direction is restricted to a predetermined angle or less. This predetermined angle is set such that the bent portions 37a, 37b of the respective swing resistance members 34, 35 do not contact the circumferential end portions of the respective receiving portions 17a, 17b.

[0040] In the above-described automatic tensioner 1, even when the pulley arms 9, 10 swing so that the idler pulleys 7, 8 separate from the belt 6 due to the tension of the belt 6 during normal operation or BSG operation, the swing is suppressed by the swing resistance of the swing resistance members 34, 35. Therefore, an optimal belt tension can be applied in either case of normal operation or BSG operation, and excessive swinging of the pulley arms 9, 10 can be suppressed to enhance the followability to the belt 6.

[0041] Also, in the above-described automatic tensioner 1, since the swing resistance members 34, 35 are provided on each of the first pulley arm 9 and the second pulley arm 10, the belt tension can be appropriately maintained in any case such as during normal operation and at the time of engine restart after idling stop. Note that a configuration in which the swing resistance members 34, 35 are provided only on one of the pulley arms 9, 10 can also be adopted.

[0042] In addition, in the above-described automatic tensioner 1, since the stopper member 32 restricts the swing angle of each of the pulley arms 9 and 10 in the one direction with respect to the swing fulcrum shaft 11 to a predetermined angle or less, the load acting on the swing resistance members 34 and 35 is reduced, and the durability of the swing resistance members 34 and 35 can be improved. In the above-described embodiment, the stopper member 32 is configured to be able to contact both the first pulley arm 9 and the second pulley arm 10, but the stopper member 32 may be configured to be able to contact only one of the pulley arms 9 and 10.

[0043] In addition, in the above-described automatic tensioner 1, since the insertion hole 41 formed in the stopper member 32 and the cross-sectional shape of the insertion end portion 40 of the swing fulcrum shaft 11 inserted into the insertion hole 41 are of the same shape other than circular (for example, D-shaped or key-fitting shape), the in-phase state between the swing fulcrum shaft 11 and the stopper member 32 is maintained, and when each of the pulley arms 9 and 10 swings by the predetermined angle, the stopper member 32 can surely prevent the swing exceeding that angle.

[0044] In addition, in the above-described automatic tensioner 1, since the washer 31 inserted through the end portion of the swing fulcrum shaft 11 and the stopper member 32 are integrally formed, the assembly process can be simplified and the manufacturing cost can be reduced.

[0045] In addition, in the above-described automatic tensioner 1, since members having a C-shaped arc shape are used as the swing resistance members 34 and 35, swing resistance can be imparted to the pulley arms 9 and 10 from the swing fulcrum shaft 11 with a compact configuration. Moreover, bending portions 37a and 37b are formed in the swing resistance members 34 and 35, and the bending portions 37a and 37b are provided in receiving portions 17a and 17b formed by fan-shaped recesses formed in the pulley arms 9 and 10, so that swing resistance occurs only in one direction of the swing direction of the pulley arms 9 and 10. Therefore, while suppressing excessive swing of the entire automatic tensioner 1, it can instantaneously follow the slack of the belt 6 and can appropriately maintain the belt tension.

[0046] In the above-described automatic tensioner 1, in the state of being attached to the auxiliary machine drive system, the bent portions 37a and 37b formed on the swing resistance members 34 and 35 are brought into contact with the inner edges of the receiving portions 17a and 17b formed on the pulley arms 9 and 10 with a preload. Therefore, when the pulley arms 9 and 10 swing in one direction, the swing resistance by the swing resistance members 34 and 35 can be quickly exerted.

[0047] In the above-described automatic tensioner 1, the axis of the swing fulcrum shaft 11 is arranged on the line connecting the axis of the crankshaft 4 and the axis of the BSG drive shaft 2, and the lengths of the first pulley arm 9 and the second pulley arm 10 are determined so that the swing radii of the first idler pulley 7 and the second idler pulley 8 are the same. Therefore, the balance of the belt tension acting on the belt 6 from each idler pulley 7, 8 is improved, and stable followability is exhibited.

[0048] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0049] 6 Auxiliary machine belt (belt) 7 First idler pulley 8 Second idler pulley 9 First pulley arm 10 Second pulley arm 11 Swing fulcrum shaft 22 Elastic member 31 Washer 32 Stopper member 34 First swing resistance member 35 Second swing resistance member 40 Insertion end portion 41 Insertion hole

Claims

1. a first pulley arm (9) that supports a first idler pulley (7) in contact with the auxiliary machine belt (6); a second pulley arm (10) that supports a second idler pulley (8) in contact with the auxiliary machine 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) with respect to the first pulley arm (9) so that the first idler pulley (7) and the second idler pulley (8) approach each other; swing resistance members (34, 35) that generate 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); a stopper member (32) that regulates the swing angle in the one direction with respect to at least one of the first pulley arm (9) or the second pulley arm (10) with respect to the swing fulcrum shaft (11) while maintaining the same phase around the axis of the swing fulcrum shaft (11) to a predetermined angle or less; An automatic tensioner having the above.

2. An insertion hole (41) for inserting the swing fulcrum shaft (11) is formed in the stopper member (32), and the cross-sectional shape of the insertion end portion (40) of the swing fulcrum shaft (11) into the insertion hole (41) and the shape of the insertion hole (41) are formed in the same shape other than circular. The automatic tensioner according to claim 1.

3. The automatic tensioner according to claim 2, wherein the cross-sectional shape of the insertion end portion (40) is a D shape or a key fitting shape.

4. A washer (31) is inserted through an end portion of the swing fulcrum shaft (11), and the automatic tensioner according to any one of claims 1 to 3, wherein the washer (31) and the stopper member (32) are integrally formed.

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