JPH08128509A - Autotensioner device - Google Patents

Abstract

PURPOSE: To provide a plate spring type autotensioner device in which prescribed tension can be given, the deflection quantity can be set large, the size can be made small, and it is suitable for the automatic tension adjusting device of a belt for driving auxiliaries of an automobile engine. CONSTITUTION: This invention is concerned with an autotensioner device provided with a pulley 4 pressed against a belt and a plate spring 2 rotatably holding the pulley 4 at the extreme end position, and giving tension to the belt by deflection of the plate spring 2. It is the point that a supporting base 3 extending along the plate spring 2 is provided, the supporting base 3 is provided with a supporting part 50 separating by a prescribed clearance 51 against the free plate spring 2 so as to contact with the spring at deflecting the plate spring 2, and the free length of the plate spring 2 becomes shorter as the deflection increases by means of the supporting part 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tensioner device for applying a required tension to a belt such as a V-ribbed belt wound around a plurality of pulleys, and more particularly to an automatic V-ribbed belt for driving an auxiliary machine of an automobile engine. The present invention relates to a suitable tension adjusting device.

[0002]

2. Description of the Related Art At present, as an automatic tension adjusting device for a V-ribbed belt for driving an auxiliary machine of an automobile engine, firstly, as disclosed in Japanese Patent Publication No. 62-2182, a twisting mechanism characterized by a turning arm is used. An automatic tensioner device with a built-in spring is known. Secondly, a lever type automatic tensioner device using a linear spring is widely used. The auto tensioner device used for the auxiliary drive V-ribbed belt is required to have the original function of maintaining the belt tension during stable running, as well as the function of suppressing the displacement vibration and belt vibration of the auto tensioner during sudden belt tension increase. To be

In order to provide a vibration suppressing function when the belt tension suddenly increases, a friction damping means is used in the first automatic tensioner device with a built-in torsion spring. An oil type shock absorber is also used in the auto tensioner device using the second linear spring. However, the vibration suppressing function using the friction damping means has a drawback that the coefficient of friction is likely to change and reliability is poor. The vibration suppression function that the oil type shock absorber also uses is
Since the oil type shock absorber and the linear spring are used side by side in parallel, there is a problem that the structure is complicated and the cost is high.

By the way, as a general auto tensioner device, Japanese Utility Model Laid-Open No. 51-59777 and Japanese Utility Model Laid-Open No. 59 are used.
As disclosed in Japanese Laid-Open Patent Publication No. 56455, a pulley that is pressed against a belt, a leaf spring that rotatably holds the pulley at the tip position, and a base that cantilevers the fixed end of the leaf spring are provided. There is known an automatic tensioner device that applies tension to the belt by bending of the leaf spring.

It is conceivable to employ the auto tensioner device using this leaf spring in an automatic tension adjusting device for a V-ribbed belt for driving an auxiliary machine of an automobile engine. However, in the case of an auto tensioner device using a leaf spring, it is necessary to increase the bending amount of the leaf spring and increase the load at the time of bending in order to satisfy both the belt tension maintaining function and the vibration suppressing function to some extent. Inevitably, a large leaf spring must be used, and it is difficult to mount it on the engine due to dimensional restrictions. Therefore, it has been considered that the leaf spring type auto tensioner device cannot be adopted as an automatic tension adjusting device for a V-ribbed belt for driving an auxiliary machine of an automobile engine.

[0006]

That is, in the leaf spring type autotensioner device, in order to increase the amount of deflection, it is necessary to reduce the moment of inertia of area of the leaf spring. Needs to be small. However, if the cross-sectional area of the leaf spring is simply reduced, the belt cannot be given a predetermined tension. for that reason,
The amount of bending of the leaf spring is further increased to increase the load, but on the other hand, the bending stress due to the bending moment load is increased, which causes a problem in strength. This strength problem is a serious problem for engine reliability. Eventually, the length of the leaf spring having a large cross-sectional area is increased, the amount of bending is increased, and the load is increased, which imposes dimensional constraints.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is a leaf spring type automatic tensioner device,
It is an object of the present invention to provide an autotensioner device that can apply a predetermined tension and can increase the amount of bending and can be downsized.

[0008]

An automatic tensioner device for solving the above problems comprises a pulley that is pressed against a belt and a leaf spring that rotatably holds the pulley at the tip position. In the automatic tensioner device for applying tension to the belt, a support base extending along the leaf spring is provided, and the support base is a free leaf spring so as to come into contact when the leaf spring bends. The gist of the present invention is to have a supporting portion which separates a predetermined gap therebetween, and the free length of the leaf spring is shortened as the bending increases due to the supporting portion. Particularly preferred applications,
This is a case where it is used as an automatic tension adjusting device for a belt for driving an accessory of an automobile engine.

In order to apply a large pressing force together with the flexure, the support portion of the support base is formed by a continuous surface along the leaf spring, and the predetermined gap extends from the fixed end of the leaf spring to the tip. It is preferable that the free length is increased in series, and the free length is continuously shortened with the bending.
In particular, when the fixed end of the leaf spring is the origin, the tangential direction from the fixed end of the leaf spring is the X axis, and the gap direction between the leaf spring and the support base is the Y axis, the rectangular coordinates are It is preferable that the function is a non-linear function that can be represented by a power polynomial of Y = aX ⁿ (n is an integer of 3 or more). However, the support portion of the support base may be formed of one or more contact fulcrums provided along the leaf spring, and the free length may be gradually reduced as it flexes.

For the initial setting work on the belt,
The belt is provided with a pulley that is pressed against the belt, a leaf spring that rotatably holds the pulley at the tip position, and a base that supports the fixed end of the leaf spring in a cantilever manner. In the automatic tensioner device for applying the above, a support base extending along the plate spring is provided so as to project from the base, and the support base is free so as to come into contact when the plate spring bends. And a supporting portion that is separated from the leaf spring by a predetermined distance so that the free length of the leaf spring becomes shorter as the bending increases, and the base has the same bending direction as the leaf spring. A fulcrum rotatable in a direction and a fixed point for fixing in a predetermined rotation state are provided, and the support base is provided with a force point for applying a rotational force about the fulcrum. preferable. Further, it is more preferable that the support base is provided with a retracting means for maintaining the state where the leaf spring is in contact with the support portion.

[0011]

Since the free length of the leaf spring becomes shorter as the flexure increases, the relationship between the flexure and the load is not proportional, and the load sharply increases as the flexure increases. That is, in the range where the load is small,
Although a small load causes a large amount of bending, a large load causes a small amount of bending in a large load range. Therefore, when an initial tension is applied to the belt, the flexure can be considerably increased under a predetermined load, and when a large load is applied to the belt, the slight tension can counteract the large tension. That is, when a large fluctuating load is applied to the belt, the bending fluctuation is reduced, and displacement vibration based on the exciting force is suppressed. As described above, both the function of maintaining the belt tension during stable running and the function of suppressing the displacement vibration during the rapid increase in tension are achieved, and thus it is suitable as an automatic tension adjusting device for a belt for driving an accessory of an automobile engine.

If the support portion of the support base along the leaf spring is formed by a continuous surface, the free length of the leaf spring also becomes shorter continuously. However, since the relationship between the flexure of the leaf spring and the free length is non-linear, if the gap between the leaf spring of the support portion of the support along this leaf spring is also made non-linear, continuous contact with the continuous surface of the support portion will occur. Reserved. When the leaf springs have the same cross section, the relationship between the flexure of the leaf spring and the free length becomes a non-linear third power, and if the function relating to the gap between the support bases is also the third power, the relationship that the free length becomes shorter with the flexure can be maintained.

At the time of mounting the auto tensioner device, the initial tension to the belt is set on the basis of the flexure of the leaf spring. In this case, the entire device is pressed against the belt about the rotation fulcrum of the base. Become. In this case, if the support point projecting from the base along the leaf spring is the force point,
A large pressing force can be generated with a small force according to the lever principle. Also, if the leaf spring is retracted along this support base, the initial position of the entire device is set and the base is fixed before the initial tension is applied to the belt. When the leaf spring is released from the means, a predetermined load can be applied to the belt.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a front view of an auto tensioner according to a first embodiment of the present invention, FIG. 2 is a plan view, FIG. 3 is a left side view, and FIG.
Is a right side view, and FIG. 5 is a sectional view taken along line AA of FIG.

1 to 5, the auto tensioner device has a pulley 4, a leaf spring 2, a support 3 and a base 8 as main components.

A pulley shaft portion 5 which rotatably supports and holds the pulley 4 is integrally formed at the tip of the leaf spring 2 by means such as welding. The pulley 4 is attached to the pulley shaft portion 5 via a ball bearing 7 by a pulley attaching bolt 6 (see FIG. 5).

The section M of the fixed end 2a of the leaf spring 2 has a support base 3
It is fixed to the flat portion of the root portion 3b of the base by appropriate fixing means such as bolting, welding, or integrated cutting by slit processing. A support portion 50 having a curved surface along the leaf spring 2 is formed on an extending portion 3a continuously protruding from a root portion 3b of a section M of the support base 3. That is, the leaf spring 2
Is projectingly provided in a cantilever manner from the root portion 3b, and a gap 51 that increases in a series is formed between the leaf spring 2 and the support portion 50. Further, a screw hole 9 is formed in the support base 3, and a through hole 10 corresponding to the screw hole 9 is formed in the plate spring 2, so that a plate spring drawing bolt described later can be screwed in.

The support base 3 is fixed to the base 8 as an integral structure. That is, the base portion 3b of the support base 3 is the base 8
Has become a part of. Further, at the four corners of the base 8, a round hole 12 serving as a rotation fulcrum for mounting and elongated holes 13 to 15 serving as fixing points for mounting are provided, respectively. The predetermined mounting surface 53 has a pin pivot 52 at a position corresponding to the round hole 12.
(See FIG. 9) are projected to form a rotation fulcrum. Long hole 1
Screw holes 16 are formed at positions corresponding to 3 to 15. The pedestal 8 is fitted into the pin pivot 52 with the round hole 12 in a predetermined rotation posture, and is fixed to the mounting surface 53 by screwing a fixing bolt (not shown) into the screw hole 16 through the long holes 13 to 15. Has become. A rectangular hole 11 for engaging a dedicated lever, which will be described later, is provided on the side surface of the support base 3 and serves as a force point for rotating the base 8 by a predetermined angle via the support base 3.

When the end O of the fixed end of the leaf spring 2 is the origin, the extending direction of the leaf spring 2 is the X axis, and the direction of the gap 51 with the support base 3 is the Y axis, the support portion of the support base 3 is shown. 50 curved surface is Y
= AX ³ . Then, the leaf spring 2 bends according to the load applied to the pulley 4, and the contact portion between the leaf spring 2 and the support portion 50 continuously moves to the right in the drawing. As a result, the free length of the leaf spring 2 is shortened in proportion to the load. If the leaf springs 2 have the same cross-sectional area, the rigidity increases with the cube of the free length of the leaf springs 2, and the amount of bending corresponding to the load decreases exponentially. To put it the other way around, the load increases exponentially with increasing deflection. Therefore, when the initial tension is applied to the belt, the flexure can be considerably increased under a predetermined load, and when a large load is applied to the belt, the slight tension can counteract the large tension. That is, when a large fluctuating load is applied to the belt, the fluctuation in bending is reduced, and the exciting force based on the displacement vibration is suppressed.

The above will be described in more detail. As is well known, the spring constant of the leaf spring 2 is obtained as follows by a theoretical formula of material mechanics.

[0021]

[Equation 1]

As shown in the above equation, the spring constant K ₀ of the leaf spring increases in proportion to the cube of L as the leaf spring free length L decreases. That is, the spring constant K ₀ and the leaf spring effective length L have a non-linear relationship. Therefore, if the effective length of the leaf spring is reduced as the deflection of the leaf spring increases as in the present invention, the spring constant increases as the deflection of the leaf spring increases, so that the required load is satisfied. At the same time, the amount of bending can be increased.

Then, the plate spring extends along the lengthwise direction of the plate spring so that the gap between the plate spring and the plate spring increases non-linearly from the fixed end to the tip. When the leaf spring is configured to have a support portion that is brought into contact with the leaf spring sequentially from the fixed end and temporarily fixed as the flexure increases, the leaf spring effective length L is temporarily fixed to the support portion. Becomes smaller, and the spring constant K ₀ becomes larger in proportion to the cube of this L, and finally becomes infinite. The operation will be described below by replacing this with the tension of the V-ribbed belt for supplementary driving of the automobile engine.

That is, during stable rotation of the crankshaft (during stable running of the vehicle), the belt tension fluctuates in a stable state. At this time, the spring constant K ₀ of the leaf spring takes a relatively small constant, and the sensitivity to the load is low. In other words, the reaction force of the leaf spring is insensitive to the belt winding length. However, when the crankshaft is rapidly accelerated or decelerated, or when the auxiliary machine load is rapidly increased, the belt tension is rapidly increased, and the load on the leaf spring via the pulley shaft load is rapidly increased. When the leaf spring according to the present invention is used, the pulley shaft is softly landed from the flexed state to the fixed state due to the non-linear action of the spring constant K ₀ against this load. This action achieves both the basic function of the belt tensioner, that is, the function of maintaining the belt tension during stable running, and the function of suppressing the displacement vibration of the automatic tensioner and the lateral vibration of the belt when the belt tension increases rapidly.

Next, the procedure for mounting the above-mentioned auto tensioner 1 will be described with reference to FIG. First, pull-in bolt 3
0 is screwed into the screw hole 9 of the support base 3 through the through hole 10 of the leaf spring 2 so that the plate spring 2 is fully bent and is aligned with the support surface 50 of the support base 3, The leaf spring 2 is fixed to the support base 3. And the mounting plate 8
The round hole 12 is fitted into the pin pivot 52 to be at the position indicated by the alternate long and short dash line. At this time, the belt B is hung on the pressing roller 4 in a bent state. Alternatively, it may be suspended above by a suspension means (not shown). Next, as indicated by the arrow, the base 8 is rotated to the predetermined position, which is the solid line position. At this time, for example, a dedicated lever (not shown) provided with a concave portion engaging with the pin pivot 52 at the tip of the rod-shaped member and a convex portion engaging with the square hole 11 of the support base 3 in the middle is prepared. And the concave portion to the pin pivot 52, the square hole 11
When the dedicated lever is rotated around the pin pivot 52 with the square hole 11 as the force point, the lever action is easily performed by the lever action with the round hole 12 as a rotation fulcrum against the tension of the belt. Can be rotated.

Then, the pull-in bolt 30 is removed to release the leaf spring 2 (direction). Then, the leaf spring 2 and the roller 4 are at the two-dot chain line position which is the initial hospital length state,
A predetermined initial tension is applied to the belt 4. With this configuration, since the load of the leaf spring 2 changes largely with respect to the amount of bending, in the above-described auto tensioner device that requires higher accuracy in the initial position of the roller 4 than in the conventional case, the initial stage of the belt 4 at the time of mounting. Tension can be performed with high precision. If the initial tension is not properly applied, it is impossible to absorb the slack at the initial stage of belt attachment and the elongation after lapse of time, and it is impossible to apply the required tension to the belt.

Next, a second embodiment will be described with reference to FIG. FIG. 7 is a side view of the auto tensioner device. 7 is different from FIG. 1 in that the leaf spring 32 and the support base 3 are different.
3 shape. That is, the support portion 34 of the support base 33 is a flat surface, while the leaf spring 32 is formed so that the clearance between the support spring 34 and the support surface 34 increases exponentially with a cubic function in the extending direction of the support surface 34. ing. As a result, the leaf spring 32
As the deflection increases, along the supporting surface in sequence, as shown in FIG.
As in the case of, the load increases exponentially with bending. Even with such a configuration, it is possible to obtain the same effects as in the above case and there is an advantage that the processing of the support portion 34 of the support base 33 becomes easy.

Next, a third embodiment will be described with reference to FIG. FIG. 8A is a side view of the auto tensioner device in which the leaf spring is free, and FIG. 8B is a side view of the auto tensioner device in a state where the leaf spring is bent.
8 is different from FIG. 1 in the shape of the support base 43. That is, the support base 43 is provided with one convex support portion 44 having a predetermined gap D from the leaf spring 2 at a predetermined position L0 on the surface (upper surface) facing the leaf spring 2. As a result, the effective length of the leaf spring 2 was L1 at the initial stage, but when it is bent by D, the effective length becomes short to L2, and the spring constant K ₀ thereof increases sharply in a bent shape, and the leaf spring 2 gradually increases. Increase to. As described above, the use state of the auto tensioner is divided into a stable running condition where the required load is low load and a sudden increase in the belt tension where the required load is high load. You can
It is possible to simplify the configuration of the support portion and the like. Further, the position L0 of the supporting portion 44 and the gap D between the supporting portion 44 and the leaf spring 2 can be arbitrarily set, and further, a plurality of supporting portions 44 are provided in the length direction of the leaf spring 2 and By increasing the gap between the supporting portion of the plate spring 2 and the leaf spring 2 from the fixed end of the leaf spring 2 toward the tip, the spring constant is increased in a plurality of bent shapes to approximate a series increase. You can also

Next, a fourth embodiment will be described with reference to FIG. 8 is different from FIG. 8 in that the base 8 is not provided, a round hole 45 serving as a rotation fulcrum for attachment is provided at the base of the support base 43, and the entire support base 43 is pressed against the belt by the jack bolt 46. That is the point. In this way, it is possible to integrally form the base and the support. In addition,
The leaf springs of the above-described first to fourth embodiments have been described as having the same cross-sectional area. However, a leaf spring having a smaller cross-sectional area as it approaches the tip of the leaf spring is used so that the relationship between the load and the deflection is almost linear. Then, the free length of the leaf spring can be continuously shortened so that the spring constant can be increased exponentially by increasing the gap between the support portion of the support base and the leaf spring in a proportional linear manner.

Next, an experimental example relating to the first embodiment shown in FIGS. 1 to 5 will be described in comparison with a comparative example. First, referring to FIG. 10, an outline of a belt drive system for driving an accessory of an automobile engine used in the experiment will be described. This transmission system
A C / R pulley connected to the crankshaft of the engine, a P / S pulley connected to the power steering, an A / C pulley connected to the input shaft of the air conditioner, and an input shaft of the AC generator. The V-ribbed belt B is wound around a plurality of pulleys called ALT pulleys. The C / R pulley is a drive pulley, and the A / C pulley, ALT pulley, and P / S pulley are driven pulleys, and power is transmitted. The auto tensioner device 1 is provided between the ALT pulley and the C / R pulley to apply a predetermined tension to the V-ribbed belt B.

FIG. 11 is a schematic configuration diagram of a leaf spring type automatic tensioner according to the present invention, and FIG. 12 is a schematic configuration diagram of a leaf spring type automatic tensioner according to a comparative example. Figure 11
In the above, the roller 4 pressed against the belt B is installed and held on the tip of the leaf spring 2, and
Below the leaf spring 2, a support body 3 in which a later-described non-linear curved surface support portion 50 is formed is disposed along the length direction thereof. The point that the support base 3 is provided is different from the conventional automatic tensioner 61 of the comparative example shown in FIG. The roller 4 presses the belt B due to the elasticity of the leaf spring 2, and adjusts the tension of the roller 4 by displacing it in the counterclockwise direction along the circular locus shown by the dotted line in the drawing.

In FIG. 13, the free length of the leaf spring is L, the end of the fixed end of the free leaf spring is the origin of the coordinates, and the direction in which the leaf springs are sequentially contacted (the length direction of the leaf spring) is the X axis. The Y axis is the bending direction of the leaf spring (the bearing holding portion of the pulley 4 in FIG. 11). Now, let the curved surface of the support stand be the curve y = f
Denoting (x) and letting the load on the tip of the leaf spring be P, if the leaf spring is in contact with the support from the fixed origin to x, the deflection δ of the tip is as follows.

[0033]

[Equation 2]

Now, the specifications of the leaf spring are as follows.
L = 150 mm, b = 30 mm, h = 3 mm, E = 21
000 [kgf / mm ² ], ν = 0.3, at this time, second moment of area I = 74.17 [mm ⁴ ], spring constant K
It becomes ₀ = 1.38 [kgf / mm]. Next, when the above curve equation y = f (x) is y = 1/3 × 10 ⁻⁵ × x ³ , the relationship between the y coordinate (deflection) of the leaf spring tip and the load when the leaf spring is used is shown in Table 1. It becomes the street.

[0035]

[Table 1]

In order to make the results of Table 1 easy to understand, FIG.
Is shown in the graph. As shown in FIG. 14, when the same leaf spring is used, the spring constant is linear in a conventional leaf spring without a support, and the spring constant is a series in a leaf spring in which the support has a curved surface that can be represented by nonlinear y = ax ^3. It can be seen that the nonlinearity increases. Next, how the nonlinear leaf spring of the present invention enhances the basic function of the automatic tensioner device will be described. In the case of the linear leaf spring autotensioner device of the comparative example and the non-linear leaf spring autotensioner device of the present embodiment shown in FIG. 14, the spring constant cannot be used over the entire range, and the purpose of the autotensioner is There is a usage range that conforms to. That is, the region where the spring constant approaches zero is contrary to the purpose of maintaining the belt tension properly, and conversely, the region where the spring constant approaches infinity causes abnormal belt tension when the belt tension increases due to the system such as auxiliary machinery load. As a result, the durability of the belt is increased and damage to the mechanical system due to an increase in the axial load is caused.

Operation when the non-linear leaf spring type auto tensioner device of this embodiment and the conventional linear leaf spring type auto tensioner device and torsion spring type auto tensioner device are used in appropriate ranges as comparative examples. The characteristics are shown in FIG. 15 as (a), (b) and (c), respectively.
The horizontal axis of FIG. 15 is the deflection (displacement), and the vertical axis is the spring load (belt reaction force). In FIG. 15, the torsion spring type auto tensioner of FIG. 15 (c) is most likely to obtain the flat characteristic, then the linear leaf spring type of auto tensioner device of FIG. 15 (b) and finally the nonlinear leaf spring type of auto tensioner of FIG. In order of equipment. Now, assuming that a belt tension fluctuation caused by a system such as an auxiliary machine load occurs and a load fluctuation input of (d) is input to the auto tensioner device via the belt, the displacement outputs are respectively non-linear leaf spring type auto tensioner devices. Is a curve (e), a linear leaf spring type automatic tensioner device is a curved line (f), and a torsion spring type automatic tensioner device is a curved line (g). That is, in the case of the non-linear leaf spring type autotensioner device, the spring constant rapidly increases and the displacement amplitude becomes the smallest. Therefore, the damping effect is greatest. On the other hand, a linear leaf spring type auto tensioner device,
When the torsion spring type auto tensioner device is used, the displacement amplitude becomes large and the vibration of the auto tensioner device becomes large.

[0038]

As described above, the autotensioner device of the present invention is provided with the support base extending along the leaf spring, and the support base is free so as to hit when the leaf spring bends. And a supporting portion that separates a predetermined gap from the supporting spring and the supporting portion so that the free length of the leaf spring is shortened as the bending increases. Therefore, the spring constant K ₀ is increased and the bending amount is increased. It has become possible to take large. That is, it is possible to achieve both the basic function of the automatic tensioner device, that is, the function of maintaining the belt tension during stable running and the function of suppressing the displacement vibration and the lateral vibration of the belt tensioner during the rapid increase in the belt tension. As a result, the leaf spring, which has the simplest configuration, can drive the auxiliary drive V for the automobile engine.
The economical effect that it can be used for the auto tensioner device used for the ribbed belt is great.

[Brief description of drawings]

FIG. 1 is a front view of an auto tensioner device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the auto tensioner device of FIG.

FIG. 3 is a left side view of the auto tensioner device of FIG.

4 is a right side view of the auto tensioner device of FIG. 1. FIG.

5 is a cross-sectional view taken along the line AA of the auto tensioner device of FIG.

FIG. 6 is a side view showing an example of using the auto tensioner of FIG.

FIG. 7 is a front view of an auto tensioner device according to a second embodiment of the present invention.

FIG. 8 is a front view of an auto tensioner device according to a third embodiment of the invention.

FIG. 9 is a front view of an auto tensioner device according to a fourth embodiment of the present invention.

FIG. 10 is a schematic diagram of a transmission system for driving an accessory of an automobile engine.

FIG. 11 is a mounting view of an auto tensioner device according to an experimental example.

FIG. 12 is a mounting view of an auto tensioner device according to a comparative example.

13 is a graph showing a curved surface function of the support base of FIG.

FIG. 14 is a load-displacement characteristic diagram of a linear leaf spring and a non-linear leaf spring.

FIG. 15 is an operational characteristic diagram of a linear leaf spring, a non-linear leaf spring, and a torsion spring.

[Explanation of symbols]

 L Effective length δ Deflection 1 Auto tensioner device 2 Leaf spring 3 Support base 4 Pulley 5 Pulley shaft mounting base 6 Pulley mounting bolt 7 Ball bearing 8 Base 9 Screw hole 10 Through hole 11 Square hole (force point) 12 Round hole (rotation) Support point 13, 14, 15 Long hole (fixed support point) 16 Screw hole 30 Fixing bolt 50 Support part 51 Gap 52 Pin pivot a Nonlinear leaf spring operating characteristic (load-displacement) b Linear leaf spring operating characteristic (load- Displacement) c Operating characteristics of torsion spring (load-displacement) d Load input due to belt reaction force e Displacement output of nonlinear leaf spring (a) f Displacement output of linear leaf spring (b) g Torsion spring (c ) Displacement output

Claims (7)

[Claims] 1. An automatic tensioner device, comprising: a pulley that is pressed against a belt; and a leaf spring that rotatably holds the pulley at a tip position, wherein tension is applied to the belt by bending of the leaf spring. A support base extending along the spring is provided, and the support base has a support portion that separates a predetermined gap from the free leaf spring so as to abut when the leaf spring bends. An automatic tensioner device characterized in that the free length of the leaf spring is shortened as the flexure increases due to the supporting portion. 2. The automatic tensioner device according to claim 1, which is used as an automatic tension adjusting device for a belt for driving an accessory of an automobile engine. 3. The support portion of the support base is formed by a continuous surface along the leaf spring, and the predetermined gap increases exponentially from a fixed end of the leaf spring toward a tip thereof. The autotensioner device according to claim 1, wherein the free length is continuously shortened with the bending. 4. When the fixed end of the leaf spring is the origin, the tangential direction from the fixed end of the leaf spring is the X axis, and the gap direction between the leaf spring and the support base is the Y axis, the coordinates are right-angled coordinates. The function related to the gap is Y = aX ⁿ (n is an integer of 3 or more)
The autotensioner device according to claim 3, which is a non-linear function that can be represented by a power polynomial of 5. The auto tensioner according to claim 1, wherein the support portion of the support base is formed by one or more contact fulcrums provided along the leaf spring, and the free length is gradually reduced as the flexure is caused. apparatus. 6. A pulley that is pressed against the belt, and a leaf spring that rotatably holds the pulley at the tip position.
An autotensioner device, comprising: a base for supporting the fixed end of the leaf spring in a cantilever manner, and applying tension to the belt by bending of the leaf spring, wherein the support base extending along the leaf spring is the base. Projecting from the plate, the support base has a support part that separates a predetermined gap from the free leaf spring so as to come into contact when the leaf spring bends. The free length of the spring is shortened as the flexure increases, and the base is provided with a fulcrum that is rotatable in the bending direction and the moving direction of the leaf spring, and a fixing point for fixing in a predetermined rotation state. An automatic tensioner device in which a force point for applying a rotational force about the fulcrum is provided on the support base. 7. The auto tensioner device according to claim 6, wherein the support base is provided with a retracting means for maintaining a state where the plate spring is in contact with the support portion.