JP2009257570A - Automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic tensioner for preventing a friction member from being deviated in the peripheral direction to generate friction resistance uniformly with respect to the peripheral direction and damp the shock-vibration transmitted from a transmission belt efficiently. <P>SOLUTION: In this automatic tensioner, each of four friction members 6 is brought into contact with a first friction face 6a and a second friction face 6b and is brought into contact with end faces in the peripheral direction of two projections 20 among four projections 20 with respect to the peripheral direction. The friction members 6 are prevented to deviate in the peripheral direction owing to these four projections 20 to generate friction resistance uniformly between the first friction face 6a and the second friction face 6b, respectively. Consequently, it is possible to damp the shock-vibration transmitted from the transmission belt efficiently. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an auto tensioner for automatically and appropriately maintaining the tension of a transmission belt of a belt drive mechanism.

Conventionally, this type of auto tensioner, as disclosed in, for example, Japanese Patent No. 3732446, includes a fixed plate and an inclined portion that are inclined so as to rise outward with respect to the axial center direction of the torsion coil spring. A plurality of friction members are arranged around the core portion of the spring support in a shape divided in the radial direction of the torsion coil spring, and an annular friction portion is arranged so as to surround the outer periphery of the friction member. . Therefore, the frictional member tries to spread outward in the radial direction by the expansion restoring force in the axial direction of the torsion coil spring applied to the swing arm, and is pressed against the annular frictional portion. Dispersed to the urging force. Since each urging force can independently generate a frictional resistance between the fixed plate and the annular friction portion, it is possible to disperse severe impacts and vibrations from the transmission belt and to attenuate efficiently. .
Japanese Patent No. 3732446

  However, since the plurality of friction portions are arranged in a shape divided in the radial direction of the torsion coil spring as in the conventional case, the friction portions are arranged without contacting each other through a gap. There is a possibility that the position of the friction portion is shifted in the circumferential direction due to intense impact and vibration from the transmission belt, and the initial uniform arrangement of the friction members may be destroyed. Accordingly, it is impossible to generate a frictional resistance uniformly between the friction member, the fixed plate, and the annular frictional portion, thereby preventing efficient damping of shock and vibration from the transmission belt.

  The present invention has been made in view of the above-mentioned problems, and prevents frictional members from shifting in the circumferential direction, thereby uniformly generating frictional resistance in the circumferential direction and efficiently attenuating impact and vibration from the transmission belt. An object is to provide an auto tensioner capable of performing the above.

  The auto tensioner according to claim 1 is provided with a housing, a swinging arm that is swingably mounted relative to the housing and rotatably supports a tension pulley, the housing and the swinging An auto-tensioner having a torsion coil spring that is compressed and inserted between the arm and the arm in a vertical direction, provided on the side where the torsion coil spring extends, and circumferentially about the axis of the torsion coil spring Between the plurality of protrusions fixed to either the housing or the swing arm and the plurality of protrusions in the circumferential direction so as to be in contact with the circumferential end surfaces of the two protrusions A plurality of friction members arranged in the manner described above, and suppression means for suppressing the friction members from moving in the direction of the extension restoring force in the axial direction of the torsion coil spring And wherein the friction member is characterized by generating a frictional resistance between the swing arm by the stretching restoring force.

  According to said structure, since each friction member contacts the end surface of the circumferential direction of two protrusion parts, it becomes possible to prevent the shift | offset | difference to the circumferential direction of a friction member, and maintaining the stable arrangement | sequence of a friction member. Can do. Accordingly, frictional resistance can be generated uniformly, and impact and vibration from the transmission belt can be efficiently attenuated.

  The autotensioner according to claim 2, wherein the circumferential end surfaces of the plurality of protrusions are such that the distance from the adjacent protrusions in the circumferential direction increases as the distance from the torsion spring increases in the axial direction. It is characterized by a tapered surface.

  According to said structure, a friction part shifts | deviates to an axial center direction by providing the suppression means and each friction member contacting the end surface of the circumferential direction of two protrusion parts, ie, a taper surface. Can be prevented. Therefore, a stable arrangement of the friction members can be maintained.

  The auto tensioner according to claim 3, wherein the plurality of friction members are annular so that the plurality of protrusions are connected to each other in the vicinity of the tip closer to the torsion spring in the axial direction. It is characterized by being.

  According to the above configuration, since the plurality of friction members are connected and integrated with each other, it is possible to reliably prevent the friction member from shifting in the direction away from the torsion spring with respect to the axial direction. Therefore, a stable arrangement of the friction members can be maintained.

  The auto tensioner according to claim 4, wherein the housing includes a shaft portion that passes through the torsion coil spring in an axial direction, and the swing arm is disposed so as to surround an outer periphery of the shaft portion. And an inner friction part provided with an annular first friction surface on the outer periphery, and an outer friction part arranged so as to surround the outer periphery of the inner friction part and provided with an annular second friction surface on the inner periphery. The friction member is in contact with the first friction surface and the second friction surface.

  According to the above configuration, the friction member can generate a frictional resistance between the first friction surface and the second friction surface, so that sliding is less than in the case where there is only one friction surface. It is possible to ensure the same frictional force in terms of area. Therefore, it is effective in saving the space of the auto tensioner. In addition, as compared with the case where there is only one friction surface, it is possible to ensure the same friction force even if the inclination angles of the first friction surface and the second friction surface are large. Therefore, it is possible to make it difficult for the tensioner to change in height due to wear of the friction member.

  The auto tensioner according to claim 5, wherein the plurality of protrusions are arranged on the housing and the swing arm so that the plurality of protrusions are arranged in a line-symmetrical or point-symmetrical manner in the circumferential direction around the axis of the torsion coil spring. It is characterized by being fixed to either.

  According to the above configuration, the friction members are uniformly arranged in the circumferential direction, and each friction member is in contact with the circumferential end surfaces of the two protrusions, thereby preventing the friction member from shifting in the circumferential direction. And a more stable arrangement of the friction members can be maintained. Accordingly, the frictional resistance can be generated more uniformly, and the impact / vibration from the transmission belt can be attenuated efficiently.

  The auto tensioner according to claim 6, wherein the first friction surface and the second friction surface are at an angle of 0 to 30 ° with respect to the axial direction from the first friction surface to the second friction surface. Is inclined in a direction that increases as the distance from the torsion spring increases.

  As described above, by making the inclination angle of the first friction surface and the second friction surface within the range of 0 to 30 °, the friction force is generated more effectively, and the impact and vibration from the transmission belt are efficiently performed. Can be attenuated.

  The auto tensioner according to claim 7 is characterized in that the friction member is made of at least one thermoplastic resin made of polyacetal, polyamide, and polyester.

  As described above, the friction member is made of at least one kind of thermoplastic resin composed of polyacetal, polyamide, and polyester, so that the friction force is generated more effectively and the impact and vibration from the transmission belt can be efficiently performed. Can be attenuated.

  The autotensioner according to claim 8 is characterized in that the friction member is made of polyamide 46 or polyamide 6T of 75 to 90% by mass and polytetrafluoroethylene of 10 to 25% by mass.

  As described above, the friction member is made of polyamide 46 or polyamide 6T 75 to 90% by mass and polytetrafluoroethylene 10 to 25% by mass, so that the coefficient of friction of the friction member is changed (variation). As the coefficient becomes smaller, the inner frictional part and the outer frictional part, which are counterpart materials, are less likely to be damaged.

  The auto tensioner according to claim 9 is characterized in that the material of the friction member further includes a benzoate plasticizer.

  As described above, when the friction member material further contains a benzoate plasticizer, the inner friction portion and the outer friction portion, which are counterpart materials, are hardly damaged.

  The auto tensioner according to claim 10, wherein the restraining means has a configuration in which friction members are respectively fixed to end faces in the circumferential direction of the two protrusions between the plurality of protrusions in the circumferential direction. It is characterized by.

  According to the above configuration, the friction members are respectively fixed to the circumferential end surfaces of the two protrusions between the plurality of protrusions in the circumferential direction, so that it is not necessary to additionally install a suppression unit. Auto tensioner can be simplified and manufacturing cost can be reduced.

Hereinafter, an example of an embodiment of the present invention will be described with reference to FIGS. When the auto tensioner 1 is viewed with the housing 30 positioned below as shown in FIG. 1, the upper part of the drawing is defined as the upper part of the auto tensioner, and the lower part of the drawing is defined as the lower part of the auto tensioner 1.
Referring to FIGS. 1 and 2, the auto tensioner 1 includes a torsion coil spring 5, a housing 30, four protrusions 20 fixed to the housing 30 above the torsion coil spring 5 in the axial direction, and an axis of the torsion coil spring 5. A swing arm 2 provided at the center so as to be swingable with respect to the housing 30, and four friction members 6 that generate a frictional resistance between the swing arm 2 and the swing arm 2 as the swing arm 2 swings. Contains. In this embodiment, the case where the housing 30 is located below the swing arm 2 and the axial center direction of the torsion coil spring 5 is the vertical direction will be described. However, the auto tensioner 1 is arranged. The direction is not limited to this.

  The housing 30 has a substantially cylindrical shape that is concentric with the spring housing 10 that is fixed to the spring housing 10 by a screw (not shown) that houses a length of about one turn from the lower end of the torsion coil spring 5. And a support 9.

  The spring accommodating body 10 has an inner peripheral wall portion 10 c inserted in the axial direction of the torsion coil spring 5 from a lower end portion of the torsion coil spring 5 to a position slightly lower than the middle portion. The other part of the spring housing 10 is a part called a cup part 10a. The cup portion 10a has a substantially L shape in the cross section shown in FIG. 1, and is an annular shape that is continuous with the lower end of the inner peripheral wall portion 10c and extends outward from the lower end of the inner peripheral wall portion 10c in the radial direction. And a cylindrical outer peripheral wall portion that is continuous with the outer peripheral end of the bottom wall portion and extends upward from the outer peripheral end of the bottom wall portion. The upper end of the outer peripheral wall is at substantially the same height as the upper end of the torsion coil spring 5. The torsion coil spring 5 is fixed while being in pressure contact with the helical fixed surface 10b, which is one turn from the lower end, which is the upper surface of the bottom wall portion. Similarly, the torsion coil spring 5 is fixed while being in pressure contact with the helical fixed surface 2 c that is one turn from the upper end thereof, which is the lower surface of the swing arm 2. That is, the torsion coil spring 5 is sandwiched between the swing arm 2 and the housing 30 and compressed.

  The support 9 penetrates the torsion coil spring 5 in the axial direction, is accommodated in the inner peripheral wall portion 10c, and is fixed to the inner peripheral wall portion 10c with screws, and the shaft portion 9a. And an annular protrusion support plate 9b extending outward in the radial direction with respect to the axial center of the torsion coil spring 5 from the tip not accommodated in the inner peripheral wall portion 10c.

  Further, as shown in FIG. 2, the four protrusions 20 are arranged at equal intervals in the circumferential direction around the shaft portion 9 a around the shaft 9 a, in other words, at positions that are line-symmetric or point-symmetric. It arrange | positions at the surface facing the torsion coil spring 5 in the protrusion support plate 9b so that it may arrange | position.

  The swing arm 2 includes a boss 2a facing the shaft 9a via the bush 8, a fixing portion 2b for fixing the vicinity of the upper end of the torsion coil spring 5, and an upward extension from the fixing portion 2b. An inner friction portion 2e disposed between the four protrusions 20 and the outer periphery of the shaft portion 9a so as to surround the outer periphery of the shaft portion 9a, and having an annular first friction surface 6a on the outer periphery; An outer friction portion 2d that extends upward from 2b and is disposed so as to surround the four protrusions 20 and has an annular second friction surface 6b on the inner periphery is formed. The fixing portion 2b is provided from the upper end portion of the torsion coil spring 5 to a height near the lower end of the protrusion 20, and has a fixing surface 2c to which the torsion coil spring 5 is fixed at the bottom portion. An arm 3 that rotatably supports a tension pulley 4 around which a transmission belt is wound is connected to the outer end of the swing arm 2. One of the first friction surface 6a and the second friction surface 6b may be a tapered surface, but it is desirable that both are tapered surfaces.

  The vicinity of both ends of the torsion coil spring 5 is fixed to the spring housing 10 and the swing arm 2, so that a biasing force (torsion restoring force) in the circumferential direction of the torsion coil spring 5 exists when the swing arm 2 swings. To do. With this torsional restoring force, the swing arm 2 and the tension pulley 4 can be urged toward one side of the swing direction to apply tension to the transmission belt. The movement of the tension pulley 4 according to the fluctuation is allowed.

  Further, the torsion coil spring 5 is fixed to the fixed surface 10b and the fixed surface 2c in a compressed state and is accommodated in the cup portion 10a and the fixed portion 2b. In the free state, the torsion coil spring 5 is expanded as compared with the accommodated state. To do. For this reason, the oscillating arm 2 is urged upward with respect to the spring housing 10 by the urging force (extension restoring force) in the axial direction of the torsion coil spring 5.

  Further, as shown in FIG. 2, the four friction members 6 are in contact with the end surfaces in the circumferential direction of the two protrusions 20 between the fixing portions 2 b and the protrusion support plate 9 b and between the protrusions 20 in the circumferential direction. In addition, the first friction surface 6a and the second friction surface 6b are arranged so as to be in contact with each other. The friction member 6 is restrained from moving in the direction of the extension restoring force in the axial direction of the torsion coil spring 5 by the protrusion support plate 9b. The friction member 6 is made of a thermoplastic resin such as polyamide 46, polyamide 66, polyamide 6T, polyamide 9T, or polyamide 9T.

Here, the experiment performed regarding the thermoplastic resin used for the friction member 6 is demonstrated. Polytetrafluoroethylene (PTFE) powder having a primary particle size of 0.2 μm shown in Table 1 in 80 to 93 mass% of each pellet of polyamide 46, polyamide 6T, polyamide 66, and polyamide 9T. After a predetermined amount of a dispersion aid (calcium stearate 12 hydroxycalcium stearate or magnesium stearate) was dry blended at room temperature, this blend was fed into the main feeder of a twin screw extruder (manufactured by Nippon Steel Works: TEX44α2). The test piece was molded under extrusion conditions (temperature 300 to 320 ° C., rotation speed 150 rpm, discharge rate 20 kg / hour), and the obtained test piece (outer diameter 50 mm, inner diameter 15 mm, thickness 3 mm) And used for the thrust test.
Furthermore, a predetermined amount of a dispersion aid (calcium stearate 12 calcium stearate or magnesium stearate), a predetermined amount of a benzoate plasticizer (Dainippon) is added to the polyamide pellets and polytetrafluoroethylene (PTFE) powder. Ink Chemical Industries, Ltd. (trade name: “PB-3A”) was added, and a test piece was molded by the same method and used for the thrust test.

  The friction coefficient of the above test piece was measured according to JIS-7218 using a thrust friction wear tester (Orientec Co., Ltd.), and the coefficient of variation (standard deviation / average value) was determined. The measurement conditions were a load of 450 N, a sliding speed of 0.1 m / S, a mating material A2017 (aluminum), a test time of 1 hour, and an ambient temperature of 95 ° C.

  Table 1 shows the damage state on the mating material surface after the test and classified into three stages. ◎ indicates almost no damage, ○ indicates little damage, △ indicates slight damage, and × indicates a case where a lot of damage is observed.

Therefore, among the thermoplastic resins used for the friction member 6, polyamide 46 or polyamide 6T 75 to 90% by mass of polytetrafluoroethylene added at 10 to 25% by weight (PTFE 10 to 20% by weight) is the friction member. This is preferable in that the coefficient of variation (coefficient of variation) of the friction coefficient is small and the counterpart material is not easily damaged. Polyamide 46 or polyamide 6T (T is a terephthalic acid component) is an aromatic polyamide obtained by polycondensation of an aromatic dicarboxylic acid and a diamine, and has a melting point exceeding 290 degrees.
Furthermore, when polytetrafluoroethylene is added to polyamide 46 or polyamide 6T 75 to 90% by weight and 10 to 25% by weight of benzoate plasticizer and 5 to 8% by weight of benzoate plasticizer are added, damage to the mating material is hardly seen. lost.

  Other specific examples of the benzoate ester plasticizer include ethylene glycol benzoate, diethylene glycol dibenzoate, triethylene glycol dibenzoate, polyethylene glycol dibenzoate, propylene glycol dibenzoate. Dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, 1,3-butanediol dibenzoate, 1,4-butanediol dibenzoate, 1,6-hexanediol dibenzoate, Examples include 3-methyl-1,5-pentanediol dibenzoate, 1,8-octanediol dibenzoate, and the like. These can be used individually by 1 type or in combination of 2 or more types.

  The operation of the auto tensioner 1 will be described.

  The auto tensioner 1 is used, for example, in an automobile engine belt system. The housing 30 is fixed to an engine block or the like, and a transmission belt is stretched around the tension pulley 4.

  A twist restoring force is applied to the swing arm 2 of the auto tensioner 1 described above, with one end of the torsion coil spring 5 supported by the spring housing 10 and the other end fixed to the swing arm 2. In FIG. 1, when the transmission belt rotates and is tensioned / relaxed to change the tension, the tension pulley 4 moves the rotation shaft accordingly, and the swing arm 2 swings. Then, the oscillating arm 2 is urged in the winding direction of the torsion coil spring 5 by the torsion restoring force of the torsion coil spring 5 so as to restore the oscillating position.

  The swing arm 2 is given a restoring force in the axial direction of the torsion coil spring 5. Since the friction member 6 is pressed against the protrusion support plate 9b by the expansion restoring force, the expansion restoring force of the torsion coil spring 5 applied to the friction member 6 is the urging force of the inner friction portion 2e against the first friction surface 6a. N1 and the urging force N2 against the second friction surface 6b of the outer friction portion 2d are distributed in two directions.

  Here, as shown in FIG. 3, the extension restoring force P of the torsion coil spring 5 is distributed in two directions: an urging force N1 perpendicular to the first friction surface 6a and an urging force N2 perpendicular to the second friction surface 6b. Shall. When any vibration or impact is applied to the transmission belt, it is suppressed from moving in the direction of the extension restoring force by being pressed against the swinging arm 2 that tries to move further in the direction of the extension restoring force and the protrusion support plate 9b. Friction occurs between the friction member 6 and, more specifically, between the first friction surface 6 a and the second friction surface 6 b and the friction member 6. In addition, since the friction member 6 is arrange | positioned so that it may each contact in the circumferential direction end surface of the two protrusions 20 between the protrusions 20 regarding the circumferential direction, it does not shift | deviate in the circumferential direction. Therefore, it is possible to generate a frictional resistance uniformly.

  At this time, the inclination angle of the first friction surface 6a with respect to the extension restoring force P is θ1, the inclination angle of the second friction surface 6b with respect to the extension restoring force P is θ2, and the dynamic friction between the first friction surface 6a and the second friction surface 6b. When the coefficient is μ, a frictional force μN1 acts in the direction away from the torsion coil spring 5 along the first friction surface 6a on the first friction surface 6a, and twists along the second friction surface 6b on the second friction surface 6b. A frictional force μN2 acts in a direction away from the coil spring 5. At this time, the relationship between the forces acting on the friction member 6 is expressed by the equation (2) in the direction perpendicular to the extension restoring force P as in the equation (1) in the same direction as the extension restoring force P of the torsion coil spring 5. .

(Expression 1) P = μN1 cos θ1 + μN2 cos θ2 + N1 sin θ1 + N2 sin θ2 (1)

(Equation 2) N1 cos θ1 + μN2sin θ2 = N2 cos θ2 + μN1 sin θ1 (2)

  FIG. 4 is a graph in which the average surface pressure of the friction member 6 when θ1 is set to 1 ° and θ2 is changed from 1 ° to 50 ° is obtained for each of the first friction surface 6a and the second friction surface 6b. Show. FIG. 5 is a graph showing changes in the damping force of the friction member 6 when θ1 is set to 1 ° and θ2 is changed from 1 ° to 50 °. 4 and 5, in both graphs, when the angle of θ2 is from 1 ° to around 30 °, the average surface pressure and the value of the damping force change greatly. When the angle is around 30 ° to 50 °, the amount of change in the values of the average surface pressure and the damping force is small. Therefore, it is effective that the inclination angle θ1 with respect to the extension restoring force P of the first friction surface 6a and the inclination angle θ2 with respect to the extension restoring force P of the second friction surface 6b are set to 30 ° as upper limit values.

  According to the auto tensioner 1 described above, the following effects can be obtained.

  Since each friction member 6 contacts the circumferential end surfaces of the two protrusions 20, it is possible to prevent the friction members 6 from being displaced in the circumferential direction, and a stable arrangement of the friction members 6 can be maintained. Accordingly, frictional resistance can be generated uniformly, and impact and vibration from the transmission belt can be efficiently attenuated. Further, since the friction member 6 can generate a frictional resistance between the first friction surface 6a and the second friction surface 6b, the sliding area is smaller than when only one friction surface is provided. It is possible to ensure the same frictional force. Therefore, it is effective in saving the space of the auto tensioner 1. Further, as compared with the case where there is only one friction surface, it is possible to ensure the same frictional force even when the inclination angles of the first friction surface 6a and the second friction surface 6b are large. Accordingly, the height change of the tensioner 1 due to wear of the friction member 6 can be made difficult to occur.

  The four protrusions 20 are fixed to the protrusion support plate 9b of the housing 30 so as to be arranged at positions that are line-symmetrical or point-symmetrical in the circumferential direction about the axis of the torsion coil spring 5, and each friction member Since 6 contacts the end surfaces in the circumferential direction of the two protrusions, the friction member 6 can be prevented from shifting in the circumferential direction, and a more stable arrangement of the friction members 6 can be maintained. Accordingly, the frictional resistance can be generated more uniformly, and the impact / vibration from the transmission belt can be attenuated efficiently.

  Furthermore, by setting the inclination angle of the first friction surface 6a and the second friction surface 6b within the range of 0 to 30 °, the friction force is generated more effectively, and the impact / vibration from the transmission belt is efficiently performed. Can be attenuated. Further, since the friction member 6 is made of at least one kind of thermoplastic resin made of polyacetal, polyamide, and polyester, the friction member 6 generates friction force more effectively and efficiently attenuates shock and vibration from the transmission belt. be able to.

  Further, when the friction member 6 is made of polyamide 46 or polyamide 6T 80 to 90% by mass and polytetrafluoroethylene 10 to 20% by mass, the coefficient of variation (variation coefficient) of the friction member 6 is reduced. At the same time, the inner friction part 2e and the outer friction part 2d, which are counterpart materials, are less likely to be damaged.

  Further, since the friction members 6 are fixed to the circumferential end surfaces of the two protrusions 20 between the four protrusions 20 in the circumferential direction, there is no need to additionally install a suppression means, and the auto tensioner 1 Simplification and manufacturing cost reduction.

  Next, with reference to FIG. 6, the 1st modification which added the change to the said embodiment is demonstrated. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

  As shown in FIG. 6, an inner friction portion 52e having a first friction surface 56a whose inclination angle with respect to the extension restoring force P is 0 °, and an outer friction portion 52d having an inclined second friction surface 56b, An auto tensioner 61 including a swing arm 52 having The swing arm 52 further includes a boss portion 52a installed on the shaft portion 9a via the bush 8 and a fixing portion 52b having a fixing surface 52c to which the torsion coil spring 5 is fixed at the bottom. In addition, the auto tensioner 61 is in contact with the circumferential end surfaces of the two protrusions 20 between the protrusions 20 in the circumferential direction between the fixed portion 52b and the protrusion support plate 9b, and the first friction surface 56a and the first friction surface 56a. Two friction members 56 are provided so as to be in contact with the two friction surfaces 56b.

  At this time, the extension restoring force P of the torsion coil spring 5 is distributed in two directions, ie, an urging force N3 perpendicular to the first friction surface 6a and an urging force N4 perpendicular to the second friction surface 6b. When the inclination angle of the surface 6b with respect to the extension restoring force P is θ4 and the dynamic friction coefficient of the first friction surface 6a and the second friction surface 6b is μ, the first friction surface 6a has a torsion coil spring along the first friction surface 6a. Friction force μN3 acts in the direction away from 5, and friction force μN4 acts in the direction away from the torsion coil spring 5 along the second friction surface 6b on the second friction surface 6b. At this time, the relationship between the forces acting on the friction member 6 is as shown in the equation (4) in the direction perpendicular to the extension restoring force P as shown in the equation (3) in the same direction as the extension restoring force P of the torsion coil spring 5. .

(Equation 3) P = μN 3 + μN 4 cos θ 4 + N 4 sin θ 4 (3)

(Equation 4) N3 + μN4sinθ4 = N4cosθ4 (4)

  Next, with reference to FIGS. 7-9, the 2nd modification which added the change to the said embodiment is demonstrated. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate. 7 corresponds to the cross section taken along line II-II in FIG. 1, and FIG. 8 corresponds to the cross section taken along line VIII-VIII in FIG. In FIG. 1, the line VIII-VIII is closer to the torsion coil spring 5 than the line II-II, and is slightly farther from the torsion coil spring 5 than the tip of the projection 20, that is, the portion closest to the torsion coil spring 5. . 9 is a cross-sectional view taken along line IX-IX in FIG.

  As shown in FIGS. 7 to 9, the four protrusions 120 may be used instead of the four protrusions 20, and the four friction members 106 may be used instead of the four friction members 6.

  Similar to the four protrusions 20, the four protrusions 120 are arranged around the shaft portion 9a at equal intervals in the circumferential direction around the axis of the torsion coil spring 5, in other words, at positions that are line-symmetric or point-symmetric. As described above, the protrusion support plate 9b is fixed to the surface facing the torsion coil spring 5. However, the circumferential end surfaces 120 a of the four protrusions 120 are tapered so that the distance from the adjacent protrusion 120 in the circumferential direction increases as the distance from the torsion coil spring 5 increases in the axial direction of the torsion coil spring 5. . That is, the distance between two adjacent protrusions 120 in the cross section shown in FIG. 7 is W1, and the two adjacent protrusions in the cross section shown in FIG. 8, that is, the cross section at a position closer to the torsion coil spring 5 than the cross section of FIG. When the distance between 120 is W2, W2 is smaller than W1.

  Similarly to the four friction members 6, the four friction members 106 are in contact with the end surfaces 120 a of the two protrusions 120 between the fixing portion 2 b and the protrusion support plate 9 b and between the protrusions 120 in the circumferential direction. At the same time, they are in contact with the first friction surface 6a and the second friction surface 6b.

  In this way, the four friction members 106 are in contact with the tapered surfaces 120a of the four protrusions 120 between the fixed portion 2b and the protrusion support plate 9b, so that the friction members 106 are in the axial center of the torsion coil spring 5. It is possible to prevent deviation in the direction. Therefore, a stable arrangement of the friction members 106 can be maintained.

  Next, with reference to FIG. 10, the 3rd modification which added the change to the said embodiment is demonstrated. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate. FIG. 10 corresponds to a cross section taken along line IX-IX in FIG.

  As shown in FIG. 10, one friction member 206 may be used instead of the four friction members 6. Similar to the four friction members 6, the friction member 206 is in contact with the end surfaces of the two protrusions 20 between the fixed portion 2 b and the protrusion support plate 9 b and between the protrusions 20 in the circumferential direction. There are four bases 206a in contact with the surface 6a and the second friction surface 6b. Further, the friction member 206 is integrally connected to the end portion of the base portion 206a closer to the fixing portion 2b, and between the four protrusions 20 and the fixing portion 2b, the fixing portion 2b of the four protrusions 20 is fixed. It has the annular part 206b extended so that it may contact | abut on the surface which opposes. That is, it can be said that the friction members 206 are formed in an annular shape so that the four friction members 6 are connected to each other while being in contact with the surfaces of the four protrusions 20 facing the fixed portion 2b.

  As described above, since the four base portions 206a of the friction member 206 are connected and integrated with each other, it is possible to reliably prevent the friction member 206 from shifting in the direction away from the torsion coil spring 5 with respect to the axial direction. . Therefore, a stable arrangement of the friction members 206 can be maintained.

  The embodiment described above and its modified form are examples of the embodiment of the present invention, and the present invention is not limited to such a configuration.

  For example, although the above-described embodiment has a configuration in which the protrusion 20 is fixed to the protrusion support plate 9b, it may be fixed to the fixing portion 2b instead. At this time, in order to suppress the friction member 6 from moving in the direction of the extension restoring force in the axial direction of the torsion coil spring 5, the projection support plate 9b may be similarly installed, or the projection support plate 9b is installed. Instead, the friction member 6 may be configured to be fixed to the circumferential end surfaces of the two protrusions 20 between the four protrusions 20 in the circumferential direction. In addition, although four friction members 6 and four protrusions 20 are provided, the number of these members is not limited. However, from the viewpoint of manufacturing cost, it is preferable that the number is about 2 to 6, respectively.

It is sectional drawing of the auto tensioner which concerns on embodiment of this invention. It is the II-II sectional view taken on the line of FIG. It is sectional drawing of the friction member vicinity of an auto tensioner. It is the graph which showed the average surface pressure with respect to inclination-angle (theta) 2. It is the graph which showed the damping force with respect to inclination-angle (theta) 2. It is sectional drawing of the auto tensioner which concerns on another modification. It is a figure corresponding to the II-II line cross section of FIG. It is a figure corresponding to the VIII-VIII line section of Drawing 1. It is the IX-IX sectional view taken on the line of FIG. It is a figure corresponding to the IX-IX line section of Drawing 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Auto tensioner 2 Swing arm 5 Torsion coil spring 6 Friction member 20 Protrusion 30 Housing

Claims (10)

A housing, a swing arm that is swingably mounted relative to the housing and rotatably supports a tension pulley, and is compressed vertically between the housing and the swing arm. An auto-tensioner having a torsion coil spring interposed therebetween,
A plurality of protrusions fixed to either the housing or the swing arm so that the torsion coil spring is provided on a side where the torsion coil spring extends, and is arranged in the circumferential direction around the axis of the torsion coil spring;
A plurality of friction members disposed between the plurality of protrusions in the circumferential direction so as to be in contact with the circumferential end surfaces of the two protrusions;
Suppression means for suppressing the friction member from moving in the direction of the extension restoring force in the axial direction of the torsion coil spring;
The auto tensioner, wherein the friction member generates a frictional resistance with the swing arm by the extension restoring force.   The end faces in the circumferential direction of the plurality of protrusions are tapered so that the distance from the adjacent protrusions in the circumferential direction increases with distance from the torsion spring in the axial direction. The auto tensioner according to claim 1.   The plurality of friction members are in an annular shape so as to be connected to each other in the vicinity of the distal ends of the plurality of protrusions close to the torsion spring in the axial direction. The described auto tensioner. The housing includes a shaft portion penetrating the torsion coil spring in the axial direction;
The swing arm is disposed so as to surround the outer periphery of the shaft portion, and is disposed so as to surround the inner friction portion having an annular first friction surface on the outer periphery, and the outer periphery of the inner friction portion. And an outer friction part provided with an annular second friction surface on the inner periphery,
The auto-tensioner according to any one of claims 1 to 3, wherein the friction member is in contact with the first friction surface and the second friction surface.   The plurality of protrusions are fixed to either the housing or the swing arm so as to be arranged at positions that are line-symmetrical or point-symmetrical in the circumferential direction about the axis of the torsion coil spring. The auto tensioner according to any one of claims 1 to 4.   The first friction surface and the second friction surface are at an angle of 0 to 30 ° with respect to the axial direction, and the distance from the first friction surface to the second friction surface increases as the distance from the torsion spring increases. The auto tensioner according to claim 4, wherein the auto tensioner is inclined in the following direction.   The auto-tensioner according to any one of claims 1 to 6, wherein the friction member is made of at least one thermoplastic resin made of polyacetal, polyamide, and polyester.   8. The auto tensioner according to claim 7, wherein the friction member is made of polyamide 46 or polyamide 6T of 75 to 90% by mass and polytetrafluoroethylene of 10 to 25% by mass.   The auto tensioner according to claim 8, wherein the friction member further includes a benzoate plasticizer.   The said suppression means is a structure by which the friction member is each fixed to the end surface of the circumferential direction of two said projection parts between these several projection parts regarding the circumferential direction. The auto tensioner according to any one of claims.

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