JP4740058B2 - Auto tensioner - Google Patents

Description

  The present invention relates to an auto tensioner for keeping a belt tension constant.

  2. Description of the Related Art Conventionally, an auto tensioner has been used as a device for keeping the tension of an auxiliary machine driving belt of an automobile engine constant. This auto tensioner is generally roughly divided into a hydraulic damper system and a friction damper system. Among these, the latter friction damper type auto tensioner is generally provided with a fixing member fixed to the vehicle body and a rotating member to which a pulley around which the belt is wound is attached. Relative motion is performed through the shaft portion to make it as constant as possible.

  In addition, a friction material (damping member) having a predetermined friction coefficient is provided on the shaft portion that rotatably connects the fixed member and the rotation member. In general, the fixed member and the rotating member are metal parts made of an aluminum alloy casting or the like, while the friction material is a synthetic resin part. Then, the friction material is fixed to one of the fixing member and the rotating member, and the friction material made of synthetic resin, the fixing member that is a metal part, and the other of the rotating member slide, so that the friction material and the metal part A frictional force is generated between the rotating member and the swinging member (pulley) to attenuate the swinging (damping function).

  Here, in order to quickly attenuate the swing of the rotating member and converge the belt vibration in a short time, an appropriate damping torque is required. For this purpose, a friction material and a metal component (fixing member or An appropriate frictional force is required on the sliding surface with the rotating member. This frictional force is represented by the product of the friction coefficient of the sliding surface and the vertical load acting on the sliding surface. However, the friction coefficient varies depending on the surface roughness of the synthetic resin friction material and the metal part as the sliding counterpart material, and it may not always be easy to obtain an appropriate frictional force, that is, a damping torque. For this reason, there is a problem that the yield of non-defective products at the time of manufacture is lowered.

  From the above viewpoint, the auto tensioner is preferably configured to be able to adjust the damping torque to an appropriate value. An example of such an auto tensioner is described in Patent Document 1. In the autotensioner of Patent Document 1, a cylindrical resin material (friction material) is provided between the shaft portion of the fixing member and the rotating member, and a sliding contact member made of synthetic resin is provided on the outer peripheral surface of the fixing member. Is attached. The sliding contact member is in contact with a tip end of an adjustment bolt that can be screwed to a side portion of the rotating member. Then, by changing the pressing force of the adjusting bolt against the sliding member on the fixed member side according to the amount of screwing of the adjusting bolt, it is possible to adjust the turning resistance (that is, the damping torque) of the turning member. It is configured.

Japanese Patent Laid-Open No. 7-4483

  The above-described damping torque adjusting mechanism of the auto tensioner of Patent Document 1 applies a damping torque by pressing an adjusting bolt against a sliding contact member to give an appropriate turning resistance to the turning member. With this configuration, it is possible to increase the basic damping torque obtained by the friction material, but it is impossible to decrease the damping torque. Therefore, the adjustable range of the damping torque is low. Moreover, since it is necessary to provide a resin member (sliding contact member) different from the friction material provided on the shaft portion on the metal fixing member for adjusting the damping torque, the number of parts increases accordingly. There is a problem that costs increase.

  In addition, the area of the sliding contact member is very small, and if the damping torque is adjusted to be large, the surface pressure of the sliding member increases, and as a result, the friction speed of the sliding contact member increases. It cannot be maintained. In general, if dust or the like enters the sliding portion interposed between the fixing member and the rotating member of the auto tensioner from the outside, the wear speed of the friction material increases. A cover or a sealing material may be provided. However, in the auto tensioner of Patent Document 1, the sliding contact member for adjusting the damping torque is provided and exposed on the outer peripheral portion of the fixed member, and the conventional structure prevents dust and the like from entering the sliding contact member. Therefore, the wear speed of the sliding contact member becomes large.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an auto tensioner that has a simple configuration, can easily adjust a damping torque even after assembly, and can withstand a long period of use. .

Means for Solving the Problems and Effects of the Invention

An autotensioner according to a first aspect of the present invention includes a fixing member, a rotating member rotatably supported by the fixing member, a pulley that is rotatably provided on the rotating member and that can contact a belt, A coil spring disposed between the fixed member and the rotating member and biasing the rotating member in a predetermined direction with respect to the fixed member; and between the fixed member and the rotating member A damping member interposed between the fixed member and the rotating member by a restoring force in the center line direction of the coil spring to attenuate the swing of the rotating member; by being operated, and a restoring force adjusting means for adjusting the restoring force of the center line direction the coil spring compression / decompression amount by varying of the coil spring, the restoring force adjusting means, the fixing member or A screw member that can be screwed to one of the rotating members, and when the head of the screw member is screwed, the pressing force to the coil spring by the screw member is changed, The coil spring is configured to adjust the amount of compression / extension in the center line direction, and an annular spacer is interposed between the screw member and the coil spring .

  According to this configuration, when the restoring force adjusting means adjusts the restoring force of the coil spring by changing the compression / extension amount in the center line direction of the coil spring by being operated from the outside, damping is performed accordingly. The frictional force generated between the fixed member and the rotating member is changed by the member. In other words, since the damping torque can be adjusted by adjusting the restoring force of the coil spring by an external operation, the damping torque can be easily adjusted even after assembly. Further, the damping torque at the time of assembly can be increased or decreased, and the adjustable range of the damping torque is wide. Further, since the damping torque is adjusted by changing the frictional force of the damping member provided between the fixed member and the rotating member, it is not necessary to provide a damping torque adjusting member separately from the damping member. Configuration is simplified. In addition, since the damping member is interposed between the fixed member and the rotating member, the dust cover and seal structure, etc. that have been used in the past can be used to ensure the ingress of dust from the outside. Therefore, it is possible to use the damping member for a long period of time by suppressing wear of the damping member.

Further, the restoring force of the coil spring can be easily adjusted by a simple external operation of screwing the head of the screw member.

Furthermore, the fluctuation of the compression / extension amount of the coil spring when the screw member is screwed becomes smooth.

Autotensioner second invention, in the first invention, the elastic body between the screw member and the coil spring is characterized in that it is interposed. According to this configuration, since the resonance of the coil spring is absorbed by the elastic body, generation of noise during operation can be suppressed.

According to a third aspect of the present invention, in the first or second aspect of the invention, the restoring force adjusting means is provided on the rotating member. According to this configuration, the restoring force adjusting means can be easily operated from the outside, and the damping torque can be easily adjusted even after the auto tensioner is assembled.

  Next, an embodiment of the present invention will be described. The present embodiment is an example in which the present invention is applied to an auto tensioner that keeps the tension of a transmission belt that drives an auxiliary machine of an automobile engine constant.

  As shown in FIG. 1, an auto tensioner 1 of the present embodiment includes a bottomed cylindrical housing 3 (fixed member) fixed to an engine block 2 indicated by a two-dot chain line in the drawing, and a shaft member 10 on the housing 3. A rotating member 4 rotatably supported via the arm 4, a pulley 5 rotatably provided on an arm portion 4 b of the rotating member 4, and the rotating member 4 rotated in a predetermined direction with respect to the housing 3. A coil spring 8 or the like that is urged to move is provided.

  The housing 3 is a metal part made of, for example, an aluminum alloy casting or the like. The housing 3 is formed in a fixed portion 3a fixed to the engine block 2 and a short cylinder extending upward from the fixed portion 3a in FIG. Is attached to the shaft mounting portion 3b, and an outer cylinder portion 3c extending further upward than the shaft mounting portion 3b around the shaft mounting portion 3b.

  The fixing portion 3a is fixed to the engine block 2 with a bolt or the like (not shown). A shaft member 10 having a hollow shaft shape is fixedly attached to the shaft attachment portion 3b. The shaft member 10 includes a cylindrical shaft portion 10a that is press-fitted into the shaft mounting portion 3b, and a tapered shaft portion 10b that is formed in a tapered shape that extends further upward from the upper end of the cylindrical shaft portion 10a and increases in diameter toward the upper side. Have Moreover, the outer cylinder part 3c forms the spring chamber 12 in which the coil spring 8 is accommodated together with the outer cylinder part 4c of the rotating member 4 described below.

  The rotating member 4 surrounds the boss 4a formed in a tapered cylindrical shape whose diameter decreases toward the lower side, an arm 4b projecting horizontally from the upper end of the boss 4a, and the boss 4a from the outside. The outer cylinder part 4c arrange | positioned is provided. This rotating member 4 is also a metal part made of an aluminum alloy casting or the like, like the housing 3 described above.

  The tapered shaft portion 10b of the shaft member 10 is inserted into the tapered cylindrical boss portion 4a. In addition, a friction cone 11 formed in a tapered cylindrical shape whose diameter decreases toward the lower side is interposed between the boss portion 4a and the tapered shaft portion 10b. The friction cone 11 may be made of a synthetic resin such as polyacetal, polyarylate, or nylon. Although not particularly shown, a key groove extending along the axial direction is formed on the inner surface or the outer surface of the friction cone 11, and the outer surface of the tapered shaft portion 10 b of the shaft member 10 or the rotation is formed in this key groove. The friction cone 11 is fixed to one of the shaft member 10 and the rotating member 4 so as not to be relatively rotatable by engaging a key portion formed on the inner surface of the boss portion 4 a of the member 4.

  A pulley 5 is attached with a bolt 7 to the top surface of the tip of the arm 4b that protrudes in the horizontal direction from the boss 4a, and is rotatably supported via a ball bearing 6. The rotation center of the pulley 5 is eccentric with respect to the rotation center of the rotation member 4 (the axis C of the shaft member 10), and the rotation member 4 rotates about the axis C of the shaft member 10. By doing so, the pulley 5 provided in the arm portion 4 b swings about the axis C of the shaft member 10.

  In this embodiment, the transmission belt 9 is wound around a crankshaft (not shown) of an automobile engine and a belt pulley (not shown) that drives an auxiliary machine such as an alternator, and the crankshaft is rotating. In this case, the rotation of the crankshaft is transmitted to the belt pulley by the transmission belt 9, and the auxiliary machine is driven. The pulley 5 described above is arranged so as to be able to contact the transmission belt 9 configured as described above.

  The outer cylinder part 4c of the rotating member 4 enters the outer cylinder part 3c of the housing 3, and a spring chamber 12 is formed by these two outer cylinder parts 3c, 4c. A coil spring 8 is disposed in a spring chamber 12 provided between the housing 3 and the rotating member 4 so as to be compressed in the center line direction (vertical direction). ) Is fixed to the housing 3, and the other end (upper end) is fixed to the rotating member 4. Then, by this coil spring 8, the rotating member 4 presses the pulley 5 against the transmission belt 9 in a predetermined rotation direction X (in the direction of arrow X in FIG. 1), that is, the tension of the transmission belt 9. It is urged to rotate in the direction of increasing. Therefore, when the transmission belt 9 is loosened and the tension temporarily decreases, the rotating member 4 rotates in the X direction, and the pulley 5 swings to increase the tension of the transmission belt 9. The tension of 9 is kept almost constant.

  Further, as described above, the friction cone 11 (damping member) is interposed between the boss portion 4 a of the rotating member 4 and the tapered shaft portion 10 b of the shaft member 10. Therefore, when the rotating member 4 rotates with respect to the shaft member 10, the friction cone 11 and the shaft member 10 fixed to the housing 3 (when the friction cone 11 is fixed to the rotating member 4), Alternatively, a damping torque that attenuates the swinging of the rotating member 4 is generated by a frictional force generated between the rotating member 4 (when the friction cone 11 is fixed to the shaft member 10), and the transmission belt 9 The vibration converges.

  Here, the boss portion 4a of the rotating member 4 and the tapered shaft portion 10b of the shaft member 10, and the friction cone 11 interposed therebetween are each formed in a tapered shape whose diameter decreases toward the lower side. Yes. Therefore, the frictional force according to the amount of compression (that is, the restoring force in the direction of the center line of the coil spring 8) in the center line direction of the coil spring 8 (that is, the direction of the axis C of the shaft member 10) is the boss portion 4a or It acts between the taper shaft portion 10b and the friction cone 11. Therefore, the magnitude of the damping torque varies according to the amount of compression of the coil spring 8 in the center line direction.

  Therefore, the auto tensioner 1 of the present embodiment includes a restoring force adjusting mechanism 20 (restoring force adjusting means) that adjusts the restoring force of the coil spring 8 by changing the compression amount of the coil spring 8, and this restoring force. The adjustment mechanism 20 is configured so that the damping torque can be easily adjusted.

  The restoring force adjusting mechanism 20 penetrates the peripheral portion of the boss portion 4a of the rotating member 4 and is attached so as to be screwable up and down, the tip of the screw member 21, and the upper end of the coil spring 8. And an annular spacer 22 interposed therebetween.

  A plurality of screw members 21 are provided at equal intervals in the circumferential direction so as to surround the periphery of the boss portion 4a. Each of the plurality of screw members 21 penetrates the rotating member 4 in the up and down direction, the tip reaches the spring chamber 12, and is in contact with the upper end of the coil spring 8 via the spacer 22. Accordingly, when the heads of the plurality of screw members 21 are screwed up and down (in the direction of the center line of the coil spring 8), the pressing force applied to the coil springs 8 by the screw members 21 is changed, thereby the coil springs 8 are changed. The amount of compression / extension in the center line direction of the coil spring 8 can be varied to adjust the restoring force in the center line direction of the coil spring 8, that is, the damping torque.

  The spacer 22 is an annular member made of, for example, a metal thin plate, and the annular spacer 22 is interposed between the tip (lower end) of the screw member 21 and the coil spring 8 so that a plurality of screws are provided. The local pressing force by the member 21 is dispersed by the spacer 22 and acts almost uniformly on the upper end surface of the coil spring 8. Therefore, the fluctuation of the compression amount of the coil spring 8 is smoothed when the screw member 21 is screwed to change the pressing force.

  Further, as shown in FIG. 2, between the spacer 22 and the coil spring 8, an annular ring made of a material (for example, a rubber material or a synthetic resin material) having a higher vibration absorption capacity than the spacer 22 or the coil spring 8 is used. An elastic body 23 is interposed. Therefore, the elastic body 23 absorbs the resonance of the coil spring 8 when the pulley 5 swings and the resonance of the coil spring 8 due to vibration from the engine by the elastic body 23, and noise during operation of the auto tensioner 1 is absorbed. It is suppressed.

Next, the operation of the auto tensioner 1 of the present embodiment will be described.
In the state where the rotation of the crankshaft is transmitted to the belt pulley for driving the auxiliary machine via the transmission belt 9, the rotation of the coil spring 8 is performed when the belt tension decreases due to the elongation or wear of the transmission belt 9. The rotating member 4 is rotated in the X direction shown in FIG. 1 with respect to the housing 3 by the urging force, and the pulley 5 attached to the arm portion 4b swings so as to press the transmission belt 9, thereby increasing the belt tension. To do.

  Further, when the rotating member 4 rotates (swings) in this manner, the friction cone 11 and the shaft member 10 or the rotating member 4 are arranged according to the amount of compression of the coil spring 8 in the center line direction. Since a frictional force is generated and a damping torque is generated by this frictional force, the swing of the arm portion 4b is quickly attenuated, and the vibration of the transmission belt 9 converges in a short time.

  Here, by screwing the head of the screw member 21 attached to the rotating member 4 by an external operation, the amount of compression of the coil spring 8, that is, the restoring force of the coil spring 8 is varied, and the damping is performed. Torque can be adjusted. Specifically, the damping torque is measured, and if the measured value is smaller than the predetermined torque, the screw member 21 is screwed downward to increase the compression amount of the coil spring 8, and the friction cone 11 and shaft The surface pressure (friction force) between the member 10 and the rotating member 4 is increased to increase the damping torque. On the other hand, when the measured damping torque is too large, the screw member 21 is screwed upward to reduce the compression amount of the coil spring 8, and between the friction cone 11 and the shaft member 10 or the rotating member 4. Decrease the damping torque by reducing the surface pressure (frictional force).

  As described above, since the damping torque can be adjusted by a simple external operation of screwing the head of the screw member 21, the damping torque can be easily adjusted even after the auto tensioner 1 is attached to the engine block 2. It can be carried out. In addition, since the damping torque at the time of assembly can be increased or decreased, the adjustable range of the damping torque is wide (the degree of freedom of adjustment is large). Further, the frictional force of the friction cone 11 provided between the housing 3 and the rotating member 4 is changed to increase or decrease the damping torque generated by the friction cone 11, so that the damping torque adjusting member is frictionally applied. There is no need to provide it separately from the cone 11, so that the number of parts is reduced and the configuration is simplified.

  In addition, since the friction cone 11 is interposed between the housing 3 and the rotating member 4, it is possible to infiltrate dust from the outside by using a conventionally used dust cover or seal structure. Can be reliably prevented, and wear of the friction cone 11 can be suppressed to enable use over a long period of time.

  Furthermore, since the screw member 21 is attached to the rotating member 4 instead of the housing 3 fixed to the engine block 2, the screw member 21 is externally attached even after the auto tensioner 1 is assembled to the engine block 2. It becomes easier to operate and it becomes easier to adjust the damping torque.

  The embodiment of the present invention has been described above with an example. However, the form to which the present invention can be applied is not limited to the above-described embodiment, and for example, the following modifications are possible.

  In the above embodiment, the spacer 22 and the elastic body 23 are interposed between the tip of the screw member 21 and the coil spring 8 (see FIG. 2). These spacer 22 and the elastic body 23 are essential members. Instead, even if one or both of the spacer 22 and the elastic body 23 are omitted, it is possible to adjust the restoring force by changing the compression amount of the coil spring 8 by the screw member 21.

  The restoring force adjusting mechanism that adjusts the restoring force by changing the compression amount of the coil spring 8 is not limited to the screw member 21 in the embodiment. In other words, any shape and configuration may be used as long as the amount of compression of the coil spring 8 can be changed by operating from the outside. For example, the coil spring 8 protrudes from the spring chamber 12 to above the rotating member 4. A pin-shaped member or a lever-shaped member protruding to the side of the rotating member 4 may be used.

  Furthermore, in the said embodiment, although the restoring force adjustment mechanism is comprised so that a restoring force may be adjusted by fluctuating the compression amount of the centerline direction of a coil spring, the expansion amount of the centerline direction of a coil spring is comprised. You may be comprised so that the restoring force may be adjusted by making it fluctuate.

  Moreover, in the said embodiment, although the restoring force adjustment mechanism is provided in the rotation member 4, you may provide in the housing 3 as a fixing member.

It is a longitudinal section of an auto tensioner concerning an embodiment of the present invention. FIG. 2 is an enlarged view around a screw member in FIG. 1.

Explanation of symbols

1 Auto tensioner 3 Housing (fixing member)
4 Rotating Member 4b Arm 5 Pulley 8 Coil Spring 9 Transmission Belt 11 Friction Cone (Damping Member)
20 Restoring force adjusting mechanism 21 Screw member 22 Spacer 23 Elastic body

Claims (3)

A fixing member;
A rotating member rotatably supported by the fixing member;
A pulley that is rotatably provided on the rotating member and that can contact the belt;
A coil spring disposed between the fixed member and the rotating member and configured to rotate and urge the rotating member in a predetermined direction with respect to the fixed member;
A frictional force is generated between the fixed member and the rotating member by a restoring force in a center line direction of the coil spring, and is interposed between the fixed member and the rotating member. A damping member for dampening the swing,
Restoring force adjusting means for adjusting the restoring force of the coil spring by changing the amount of compression / extension in the center line direction of the coil spring by being operated from the outside ,
The restoring force adjusting means has a screw member that can be screwed to one of the fixed member or the rotating member, and when the head of the screw member is screwed, the screw member It is configured to adjust the amount of compression / extension in the direction of the center line of the coil spring by changing the pressing force to the coil spring,
An auto tensioner , wherein an annular spacer is interposed between the screw member and the coil spring . The auto tensioner according to claim 1 , wherein an elastic body is interposed between the screw member and the coil spring. The auto tensioner according to claim 1 or 2 , wherein the restoring force adjusting means is provided on the rotating member.

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