JPH0530595U - Auto tensioner - Google Patents

Abstract

(57) [Summary] [Purpose] In an automatic tensioner that applies proper tension to the belt by the belt transmission mechanism, prevents fluctuations in frictional force due to abrasion of friction members such as resin sleeves, and maintains stable vibration damping action for a long time. Excuse me. [Structure] A tensioner shaft is fixed to the center of a bowl-shaped portion (A) of a bowl-shaped fixing member for fixing the auto tensioner to another member, and the tension arm (4) also has a bowl-shaped portion (B). 5) is swingably attached, and a torsion spring (7) is inserted in the space formed by the bowl-shaped portions (A) and (B) facing each other, and further, the tension arm (5) In an auto tensioner (1) having an idler pulley (6) rotatably fixed at one end, the ends of both the bowl-shaped portions (A) and (B) of the fixing member and the tension arm are overlapped with each other, and the overlapping portion thereof is formed. A friction ring (9) for holding grease is inserted in the gap formed in (1).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an auto tensioner that applies proper tension to a belt in a belt drive mechanism.

[0002]

[Prior Art]

 In belt transmissions in which a transmission belt is wound between a drive pulley and a driven pulley, an autotensioner is usually used as a tension applying means.In the initial stage, this autotensioner uses an idler pulley as a torsion spring or a spring. It was constructed so that it could simply be pressed against the belt by means of tensile springs.

However, in recent years, a multi-shaft transmission mechanism for driving a multi-shaft driven shaft by a single belt has been developed centering around the drive power transmission of an auxiliary machine of an automobile, and the multi-shaft transmission mechanism has been put into practical use. Unlike conventional belt transmission, the mechanism has the drawback that the belt used is very long and the load is subject to a lot of fluctuations, which makes the belt susceptible to vibration. Auto tensioners are required to have the function of damping the vibration in addition to the function of applying a constant tension to the old pulley.

Therefore, an automatic tensioner for adjusting the tension of a belt having both of these functions has been developed, and is already disclosed in JP-A-58-72757, JP-A-63-147957, JP-A-64-58846 and the like. Although some concrete structures are disclosed, these structures generally include a fixed body, a rotating body rotatably mounted on the fixed body, and an axis parallel to the rotation axis of the rotating body. Is placed in an annular space formed by an idler pulley attached to the rotating body so that it can rotate and the fixed body and the rotating body, and tension is applied to a belt stretched between a plurality of pulleys. And a spring for elastically urging the rotating body so that the rotating body is attached to the rotating body. It has a structure in which a resin sleeve having a braking force by frictional sliding that decreases as it goes toward the belt urging direction of the idler pulley is interposed, and a constant tension is applied to the belt and the resin sleeve The vibration generated by is damped, and it has extremely preferable characteristics as an auto tensioner for multi-axis drive.

In the auto tensioner having the above structure, when the resin sleeve is provided on the inner peripheral side of the spring installation space, a smooth sleeve for sealing and dust protection is additionally provided in the gap on the outer peripheral side. Something is happening.

[0006]

[Problems to be solved by the device]

 As described above, the above-mentioned known autotensioners are extremely preferable in terms of adding vibration damping characteristics, but on the other hand, they exhibit high frictional force, so that the resin sleeve is clogged with worn powder, There is a risk that the roughness of the surface will change and the frictional force will change depending on the surface condition, resulting in unstable operation. Also, in a closed dustproof sleeve, clogging with abrasion powder may occur.

The present invention focuses on the above facts, and by lubricating the friction member such as the resin sleeve, the fluctuation of the friction force due to the wear is prevented, and the vibration damping action is stable over a long period of time. The purpose is to hold it.

[0008]

[Means for Solving the Problems]

 The feature of the auto tensioner of the present invention which meets the above-mentioned purpose is that the tensioner shaft is fixed to the center of the bowl-shaped portion (A) of the bowl-shaped fixing member for fixing the auto tensioner to other members, and the bowl-shaped fixing member is also attached to the tensioner shaft. A tension arm having a portion (B) is swingably attached such that the bowl-shaped portions (A) and (B) face each other, and is formed by the bowl-shaped portions (A) and (B). In the automatic tensioner in which a torsion spring is inserted to urge the tension arm in a fixed rotation direction in a fixed space, and an idler pulley is rotatably fixed to one end of the tension arm, the fixing member and the bowl of the tension arm are The ends of the parts (A) and (B) should be placed on top of each other, and a friction ring holding grease should be inserted into the gap formed in the overlapping part. In the configuration. Here, the friction ring that holds the grease may be either a ring-shaped one or a flat strip-shaped one that is rolled into a ring shape, but it is necessary to have a structure that holds oil and grease. Specifically, a small hole that can hold oil and grease or a recess is provided on the entire surface of the ring. The thickness of this friction ring is usually around 1 mm.

[0009]

[Action]

 The auto tensioner of the present invention is used by pressing the idler pulley against the belt as in the prior art. At this time, the tension arm is biased in a fixed direction by the coil spring, so that a desired tension can be applied to the belt. Further, in the present invention, since the friction ring is inserted between the bowl-shaped portions (A) and (B), when the tension arm swings, the bowl-shaped portions (A) and (B) pass through the friction ring. They rub against each other and generate a frictional force to exert a vibration damping action.At this time, the friction ring retains oil to provide good lubrication, and at first glance it seems to be in conflict with the frictional force. Eliminates instability due to high frictional force and secures stable operation for a long time.

[0010]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view of an automatic tensioner according to the present invention, and FIG. 2 is a sectional view of an automatic tensioner according to a second embodiment of the present invention. In the figure, (1) shows an auto tensioner. The auto tensioner (1) is a fixing member (3) that serves as a mounting seat for fixing to another member (2) such as an engine, a tensioner shaft (4), a tension arm (5), an idler pulley (6), a torsion spring. (7), a rolling bearing (ball bearing) (8) and the like.

Explaining in sequence, the fixing member (3) has a bowl-shaped outer shape formed by, for example, aluminum die casting, and has a side portion (18) forming a bowl-shaped wall around the disc-shaped mounting seat (10). ) Is provided in a wall shape, and the tensioner shaft (4) is integrally provided in the center of the bowl-shaped portion (A).

In the illustrated example, the tensioner shaft (4) has a root portion (11) from a position closer to the mounting seat portion (10), an intermediate portion (12) narrower than the root portion (11), and further than the intermediate portion (12). A bolt for a mounting bolt (30) which is formed to have a narrow rolling bearing contact portion (13), and which penetrates from the rolling bearing contact portion (13) side to the fixing member (3) side in the central portion. A hole (14) is provided. On the other hand, the tension arm (5) is composed of a bowl-shaped mounting portion (15) and an arm portion (16), which are integrally connected to each other. The part (15) further comprises an outer wall part (26) forming the bowl-shaped part (B) and a core part (17). The outer shape of the bowl-shaped outer wall portion (26) is slightly larger than the side portion (18) of the bowl-shaped portion (A) of the fixing member (3), the inner diameters thereof are substantially the same, and the outermost end portion is the fixing member (3). ) Has a large inner diameter so that the ends of the side portions (18) are inserted and overlapped with each other, and an oil having small holes (9 ') on the entire surface is formed in the gap of the overlapping portion as shown in FIG. , The friction ring (9) holding grease etc. is inserted. The core portion (17) is a shaft having a hole (20) provided at the center, and a ball bearing (8) is inserted in the inner portion (21) of the shaft.

The arm portion (16) of the tension arm (5) is plate-shaped, and the idler pulley (6) is rotatably attached to the tip extending from one end of the mounting portion (15). There is. In this embodiment, the idler pulley (6) is mounted at a position projecting forward from the mounting portion (15) of the tension arm (5), and the centerline of the idler pulley (6) is a ball bearing of the mounting portion (15). It does not match the center line of (8). Therefore, a moment force about the ball bearing (8) is generated in the core portion (17) of the attachment portion (16) of the tension arm (5). Here, since the idler pulley (6) and its fixing means are not different from known ones, detailed description thereof will be omitted.

Next, the torsion spring (7) applies a rotational force to the tension arm (5), and both ends thereof are folded back so as to be engageable with the fixing member (3) and the tension arm (5). .. In this embodiment, the torsion spring (7) has a rectangular cross section of its strands, which makes it more compact, but may of course have a circular cross section. The tensioner (5) of the auto tensioner (1) of the illustrated embodiment is such that the fixing member (3) and the bowl-shaped portions (A) and (B) of the tension arm (5) face each other, and the tension arm (5) bears the bearing (8). ) Is attached to the tensioner shaft (4) so that it can swing. Then, a torsion spring (7) locks both ends of the torsion spring (7) with the fixing member (3) and the tension arm (5) in the space formed by the bowl-shaped portions (A) and (B), respectively. It is installed in a state where it is tightened by force. Although not shown, the fixing member (3) and the tension arm (5) have engaging claws that limit the rotation angle to a certain amount, and do not allow free rotation exceeding a certain rotation angle. Therefore, the tension arm (5) is always biased in the loosening direction by winding the torsion spring (7).

In the autotensioner having the above-mentioned structure, however, (9) is a friction ring that holds greases such as oil and grease, which is a feature of the present invention, and the greases are spread over the entire surface as shown in FIG. Which have a large number of through holes or recesses (9 ') for holding, and which are previously annularly shaped or have flat belts rolled into an annular shape so that both bowl-shaped portions (A) and (B) face each other. It is inserted in the overlapping portion of the end. The friction ring (9) has a thickness of about 1 mm and can exhibit a large vibration damping capacity without necessarily using a material having a high friction coefficient, and rather has a low to medium friction coefficient. The method of using is preferable because the swinging of the tension arm is smooth. From this viewpoint, synthetic resins such as Teflon and nylon, particularly cast nylon, are preferable as the specific material for the friction ring.

However, of course, those having a medium friction coefficient such as copper alloy, oil-containing sintered material, and aluminum, and those having a high friction coefficient such as rubber and asbestos can also be used. In order for the friction ring and the bowl-shaped parts (A) and (B) to rub against each other, a force in the radial direction of the tensioner shaft that presses both of them is necessary, and this force is mainly due to the belt from the autotensioner. It is generated by the reaction force it receives. That is, when a reaction force is applied from the belt to the idler pulley, a moment is generated in the tension arm around the bearing that is obstructed by the tensioner shaft, and the entire tensioner shaft tends to tilt. By this force, the friction ring and the bowl-shaped portion (A) are pressed against each other.

Further, the bearing and other minute clearances are crushed by the reaction force received from the belt, and the tension arm itself is slightly eccentric from the tensioner shaft, so that both are pressed. These forces are generally small, but since the position where the frictional force is generated is far from the rotation center of the tension arm in the autotensioner of the present invention, this is amplified and a large brake torque is obtained.

However, in the above case, if the frictional force is too high, the abrasion powder is clogged and the frictional force becomes high or low, and the operation tends to become unstable. Therefore, the friction ring (9) is provided with a small hole (9 ') or the like to fill and hold oil and grease. The filling of oil and grease is achieved by applying oil and grease to both the front and back surfaces of the friction ring (9), but the ends of the bowl-shaped parts (A) and (B) that come into contact with the friction ring (9). It is more advantageous to apply oil and grease to the parts as well.

It should be noted that the friction ring (9) is usually inserted only into the gap formed by the bowl-shaped portions (A) and (B), and is not particularly fixed. This is because if cast nylon is used for the friction ring (9) and aluminum die cast is used for the fixing member (3), etc., if both are fixed, the friction ring will crack due to temperature change due to the difference in thermal expansion coefficient. is there. Therefore, if the material of the friction ring has a thermal expansion coefficient similar to that of the material of the fixing member, it is preferable to fix both materials. Further, the width of the friction ring (9) is determined and appropriately selected depending on the length of the overlapping portion of the bowl-shaped portions (A) and (B) into which it is inserted.

FIG. 2 shows that the embodiment shown in FIG. 1 has a friction ring (9) arranged outside the torsion spring (7), whereas a tension arm (9) is arranged inside the torsion spring (7). This is an example in which the friction ring (22) is also inserted between the tubular portion formed protruding from the core portion (17) of 5) and the intermediate portion (12) of the tensioner shaft (4). In this case, a ring similar to the friction ring (9) having a large number of grease holding holes (9 ') described above is used as the friction ring (22). Of course, it is also possible to use the above-mentioned friction ring (9) at the overlapping portion of the bowl-shaped portions (A) and (B) on the outer side of the torsion spring (7). However, when the friction ring is only inside the torsion spring (7), the same effect can be obtained by providing only the inside friction ring with the grease-holding structure of the present invention.

Thus, when the above automatic tensioner is used for the belt transmission mechanism and the idler pulley (6) is brought into contact with the belt to run the belt, if the belt vibrates due to fluctuations in the rotation of the engine or the like and load fluctuations, The tension arm (5) vibrates. However, this vibration causes friction between the tension arm (5) and the fixing member (3) via the friction rings (9) and (22), and the vibration energy is radiated as heat there. Therefore, the vibration of the belt converges early.

[0023]

[Effect of the device]

 As described above, the autotensioner of the present invention has the friction ring inserted to the overlapping portion of the bowl-shaped portions (A) and (B) of the tension arm and the fixing member, the friction ring having a structure for holding grease. When the arm oscillates, the bowl-shaped parts (A) and (B) are rubbed through the friction ring, and the frictional force is generated by the parts, so a large brake torque is obtained and a large vibration damping force is generated. It is possible to obtain extremely excellent performance as an auto tensioner. Moreover, as described above, the friction ring holds greases with a large number of small holes or dents and is smooth, so even if high frictional force does not occur, abrasion powder does not occur as in the conventional case, and therefore friction It is possible to prevent fluctuations in force and perform stable operation for a long period of time, and it is expected that the vibration damping effect will be extremely effectively exhibited. Since the friction ring is thin, it is not only easy to process, but also the friction force generation mechanism can be miniaturized, and it is possible to realize an autotensioner with a small overall size.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an auto tensioner according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the auto tensioner according to the present invention.

FIG. 3 is a perspective view showing an example of a friction ring material used in the present invention.

[Explanation of symbols]

 (1) Auto tensioner (3) Fixing member (4) Tensioner shaft (5) Tension arm (6) Idler pulley (7) Torsion spring (9) Friction ring (9 ') Grease retaining hole (22) Friction ring

Claims (2)

[Scope of utility model registration request] 1. A tensioner shaft is fixed to the center of a bowl-shaped portion (A) of a bowl-shaped fixing member for fixing the auto tensioner to another member, and a tension arm having the bowl-shaped portion (B) is also provided on the tensioner shaft. The bowl-shaped portions (A) and (B) are swingably attached so as to face each other, and the tension arm is provided in the space formed by the bowl-shaped portions (A) and (B). In an automatic tensioner in which a torsion spring is inserted to urge it in a constant rotation direction, and an idler pulley is rotatably fixed to one end of a tension arm, the fixing member and the bowl-shaped portions (A) and (B) of the tension arm are provided. The auto tensioner is characterized in that opposite ends of the are overlapped with each other, and a friction ring for holding grease is inserted in the overlapping portion. 2. The auto tensioner according to claim 1, wherein the friction ring for holding grease is a ring having a large number of small holes or depressions on the entire surface of the ring.