JP2622587B2 - Tensioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tensioner that maintains a belt or a chain in an appropriate tensioned state by advancing a tension rod.

[Prior Art] In this type of tensioner, if the belt or chain swings due to fluctuations in driving torque and the tension rod does not advance too much and does not return, the belt or chain becomes too tight and generates a beat sound, In view of the fact that the belt or the chain is significantly deteriorated, a tensioner 100 having a return characteristic added to a tension rod has been developed (Japanese Utility Model Application Laid-Open No. 62-13257).

As shown in FIG. 8, the tensioner 100 is mounted in a tension case 104 so that a tension rod 101 for pressing a chain can be advanced by a coil spring 105, and a ratchet claw 102 is engaged with one side of the tension rod 101. And the spindle 103 of the ratchet claw 102
Is inserted into the elongated hole 106 of the tension case 104 so that the ratchet pawl 102 can rotate to change the pawl position. The tensioner 100 normally moves the tension rod 101 forward to keep the chain properly taut when the chain is loosened, but the return direction of the tension rod 101 is regulated by the ratchet pawl 102. On the other hand, when the tension rod 101 advances too much and the chain is too tight, the support shaft 103 of the ratchet claw 102 can retreat within the range of the long hole 106, so that the chain can be prevented from being too tight.

In addition, a tensioner 200 has been developed in which a return characteristic is given to a tension pulley that comes into contact with the belt (see FIG. 6).
2-185958).

As shown in FIG. 9, the tensioner 200 applies an appropriate tension to the timing belt by the tension pulley 201 abutting against the timing belt (not shown) and pressing the timing belt with the spring force of the torsion spring 202. It has become. Further, a cylindrical arm attachment member 204 that rotatably supports the tension pulley 201 via an arm 203 is attached to the tensioner 200, and resin bushes 205 and 206 are attached so as to sandwich the attachment member 204.

According to the tensioner 200, the return characteristic is given to the tension pulley 201 to prevent the belt from being overstretched, and even if the torsion spring 202 resonates with the timing belt fluttering, the bush 205, 206 is attached to the arm. The resonance can be suppressed by a frictional force with the member 204.

[Problems to be Solved by the Invention] However, in the tensioner 100, since the return amount of the tension rod 101 is regulated by the elongated hole 105, the return amount of the tension rod 101 that has excessively advanced due to the resonance of the belt or the chain is Decrease by that much,
Finally, the spindle 103 of the ratchet pawl comes into contact with the lower end of the long hole 106, which is the maximum return point of the long hole 106, and the tension rod 101
Is a problem in that it becomes rigid against the reaction force from the belt or chain and loses the function of preventing the belt from being overstretched, and there is nothing to absorb this resonance when the belt or chain resonates. Alternatively, there is a problem that the fluttering of the chain cannot be prevented.

Further, in the tensioner 200, since the torsion spring 202, the arm mounting member 204, and the bush 206 have a multiplex structure, the device is complicated and large, and the mounting space is limited.
If the friction between 05 and 206 is increased, the response of the tension pulley will decrease, so it is difficult to adjust to obtain the required friction, and the wear of the bushes 205 and 206 will reduce the resonance damping effect and lack reliability. Had problems.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a compact tensioner having a simple structure, which has a quick response to a slack of a belt or a chain, can attenuate resonance of the belt or the like and prevent overstretching, and has a simple structure.

Means for Solving the Problems In order to achieve the above object, the present invention provides a tensioner for maintaining a belt or a chain in an appropriate tensioned state by advancing a tension rod. Is performed by a single coil spring exhibiting a non-linear characteristic by an unequal pitch attached so that the inflection point of the load deflection characteristic is set to the set position.

Further, the coil spring is formed using a stranded wire.

[Function] In the present invention, the tension rod for maintaining the belt or the chain in the stretched state and the maintenance of the advanced state are performed by the coil spring. Deflects to retract the tension rod, which acts to prevent the belt or chain from becoming too tight.

Also, one coil spring exhibiting non-linear characteristics due to unequal pitch attached so that the inflection point of the load deflection characteristic is set to the set position, the effective number of turns of the coil spring at the time of resonance of the belt or the chain is the above-mentioned inflection Change at the point,
A change in the natural frequency of the coil spring due to this change acts to attenuate the resonance.

A coil spring that exhibits non-linear characteristics due to unequal pitch formed by stranded wires, when the belt or chain resonates, the effective number of turns of the coil spring changes at the inflection point as described above, and this change causes The resonance is attenuated by the change in the natural frequency of the coil spring, and the friction acts between the wires constituting the coil spring to bend so as to attenuate the resonance.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to the illustrated examples.

FIG. 1 is a front view of a tensioner 1 according to the present invention (see FIG. 1).
FIG. 1 (a)) and a side sectional view (FIG. 1 (b)).

A tension rod 2 is inserted into a tensioner 1 in a cylindrical casing 3 having a bottom so as to advance and retreat. One end of the tension rod 2 is in contact with a hole bottom 4a of a through-hole 4 having a U-shaped cross section having an opening facing the bottom 3a of the casing 3, and the other end is in contact with the bottom 3a of the casing 3 so that the coil 3 A spring 5 is mounted. And tension rod 2
Is mounted in the casing 3 without falling off from the casing 3 irrespective of the biasing force of the coil spring 5 by the stopper 6 penetrated between the casing 3 and the tension rod 2.

In the drawing, reference numeral 7 denotes a mounting piece for fixing the tensioner 1 projecting from both sides of the casing 3 to an appropriate fixing member, and the mounting piece 7 is provided with a mounting hole 7a. Reference numeral 8 in the figure denotes an O-ring fitted into an annular groove of the cylindrical inner wall of the casing 3 to seal the sliding contact portion of the tension rod 2.

The tensioner 1 stretches an endless belt E suspended from three pulleys A, B, and C installed at fixed positions, for example, as shown in FIG. Used to The belt E is given an appropriate tension by being pressed by the tension pulley D, and the tension pulley D is pressed by the tensioner 1. That is, the tension pulley D is swingably mounted around a fixed axis G via an arm F. The tension of the tension pulley D is brought into contact with the tip of the tension rod 2 which advances by the urging force of the coil spring 5 against the arm F. The pulley D is pressed against the belt E. The extension of the tension rod 2 is performed by removing the stopper 6.

As the coil spring 5, a coil spring having a non-linear characteristic or a coil spring formed of a stranded wire having a non-linear characteristic is used.

The coil spring having the non-linear characteristic of the present invention is, for example, a third type.
The coil spring shown in FIG. This coil spring has a two-step unequal pitch coil spring 9 in which one end 9a is formed at a small pitch and the other end 9b is formed at a large pitch around a substantially central portion in the longitudinal direction. It is.

The tensioner 1 using the unequal-pitch coil spring 9 is mounted in the casing 1 with all the coils in a state of close contact (FIG. 3 (b)), and the advancement of the tension rod 2 is locked by the stopper 6. Assembled (see FIG. 1 (b)). The tensioner 1 assembled in this manner is fixed to a predetermined position via the mounting hole 7a, and the slide lock of the tension rod 2 is released by removing the stopper 6, and the tip of the tension rod 2 is connected to the arm F of the tension pulley.
(See FIG. 2). As shown in FIG. 3 (c), the state of the unequal pitch coil spring 9 in this setting is such that the small pitch portion 9a is in close contact with the large pitch portion 9b and the large pitch portion 9b is in a pitch wound state in which the coils are separated from each other. Has become. The small pitch portion 9a is a belt E
Following the slight slack, the coils are in close contact with each other, as shown in FIG.

When this represented by load deflection characteristic diagram of the unequal pitch coil spring 9 becomes as shown by a solid line a in FIG. 4, irregular pitch coil spring 9 is setting at the inflection point a ₁ of the load deflection characteristics diagram that Appropriate widths on both sides act so as to fall within the usual range.

That is, irregular pitch coil spring 9 as will become an inflection point a ₁ of the load deflection characteristics of the spring in the set position the casing 3
Mounted inside.

By mounting the unequal-pitch coil spring 9 in this way, the return characteristic of the tension rod 2 retreating into the casing 3 with the deflection of the coil spring 9 without becoming a rigid body against an excessive reaction force from the belt E is obtained. Since the belt E is provided, the belt E can be prevented from being overly stretched. Further, when the resonance of the belt E, irregular pitch coil spring 9 in the boundary of the inflection point a ₁ burden deflection characteristics vary the effective number of turns, and attenuates be varied the resonance eigenfrequency This change Let it.

Tensioner 1 using this unequal pitch coil spring 9
The following various variations are also conceivable.

The unequal pitch coil spring 9 may be formed by a stranded wire.
As shown in FIG. 5, the unequal pitch coil spring 9 is formed by, for example, coiling a wire obtained by twisting three strands 9a, 9b, 9c.

When such a stranded unequal-pitch coil spring 9 is used, friction occurs between the strands 9a, 9b, and 9c when the spring bends, and the characteristic is that the frictional force is applied to the spring force. The characteristic is indicated by a broken line b in FIG. This property is a big characteristic hysteresis having the characteristics b ₁ and return characteristics b ₂ snow, to effectively damp the resonance of the belt E together with the natural frequency of the change in the irregular pitch coil spring 9 itself.

In addition, viscous grease is sealed between the tension rod 2 and the inner peripheral wall of the casing 3 or is applied to an unequal-pitch coil spring made of the above-described stranded wire to slide the tension rod 2 and the stranded wire 9a, The shear resistance of the viscous grease may be applied when a gap occurs between 9b and 9c, and the resonance energy of the belt E may be absorbed by the shear resistance.

Further, a damper member 10 is provided inside the unequal pitch coil spring 9 mounted on the tensioner 1 as shown in FIG.
May be provided. This damper member 10 is provided for eliminating the feeling of bottom contact of the tension rod 2.
The rear end abuts against the bottom 3 a of the casing 3 and the front end is attached to the bottom 4 a of the tension rod 2 so as to face the bottom 4 a. Then, before all the coils of the coil spring 9 come into close contact with each other near the return end point of the tension rod 2, the tip of the damper member 10 abuts on the hole bottom 4a of the tension rod 2 to obtain a damper effect. The characteristic of the tension rod 2 at this time is indicated by a dashed line c in FIG.

In order to obtain the damper effect, the damper member 10
A cylindrical body made of an elastic member such as rubber or a coil spring is used. This coil spring may be a coil spring formed of a stranded wire. However, when the unequal-pitch coil spring 9 of the stranded wire is used, the winding direction and the twist direction are different so that the two wires do not bite (for example, one side). To S twist and the other to Z twist). When the damper member 10 exerts the damper effect, the damper member 10 expands outward and comes into contact with the unequal-pitch coil spring 9 to generate friction, so that the damper effect can be further increased. This damper effect is the first
As shown in FIG. 6 and FIG. 6, the sliding surface of the tension rod 2 is sealed by the O-ring 8 fitted on the inner peripheral wall of the casing 3 and the casing 3 is sealed, so that the operation of the air damper is also loaded and larger. Has a damper effect.

 Further, the present invention includes the following various modifications.

The coil spring having the non-linear characteristic is not limited to the unequal-pitch coil spring 9 described above, and includes an unequal-pitch coil spring having three or more pitches as well as the coil diameter or the element forming the coil. It also includes a coil spring having a non-linear characteristic by other means such as changing the line thickness between pitches.

Further, as shown in FIG. 2, the method of using the tensioner may be such that the belt E is not only pushed by the tension rod via the tension pulley D but also pulled by the tension rod. An example of use in this case is as shown in FIGS. 7 (a) and 7 (b), for example.

In the figure, tension pulley D and tensioner 1
Are disposed so as to be located inside and outside the belt E, respectively. One end of the tension pulley D is pivotally supported by the other end of the arm H pivotally supported by the fixed shaft G, and is mounted to be swingable about the fixed shaft G.

On the other hand, the tensioner 1 is oriented so that the tip of the tension rod 2 is located on the opposite side of the tension pulley D. The tension pulley D and the tensioner 1 are connected via a connecting member J. The connecting member J is formed by bending one end of a substantially rectangular plate material at a substantially right angle to form a connecting piece K. The tip of the tension rod 2 is brought into contact with the inner surface of the connecting piece K, and the connecting piece K is formed. The other end on the opposite side is pivotally supported on a pivot shaft M of the tension pulley D, whereby the tension pulley D and the tensioner 1 are connected.

When the tensioner 1 is used in this manner, the tension pulley D is pulled in the direction of the arrow via the connecting member J by the advancement of the tension rod 2, and the belt E is maintained in an appropriate tension state by the pulling force at this time.

[Effects of the Invention] Since the present invention is configured as described above, it has the following various effects.

Since the tension rod advances and maintains the advanced state by the coil spring, sufficient return characteristics are provided, and the belt or chain can be prevented from being excessively tensioned, and the proper tension state can be maintained.

Since coil springs that exhibit non-linear characteristics due to unequal pitch are used so that the inflection point of the load deflection characteristics is set to the set position, the resonance of the belt or chain is caused by the natural frequency of the coil spring itself. It is effectively attenuated by the change, and the belt or the like can be operated without fluttering.

Since the maintenance of the proper tension state of the belt and the like and the prevention of the resonance are performed by one coil spring used as the urging means of the tension rod, other return characteristic imparting means and the resonance preventing means become unnecessary. Since only the urging structure of the rod is sufficient, the structure is simple and easy to assemble, and the whole is small and compact, so that there is no need to select a mounting space. Also, the number of parts is small.

[Brief description of the drawings]

1 (a) and 1 (b) are a front view and a cross-sectional view taken along line XX of a tensioner according to the present invention, FIG. 2 is a use state diagram showing an example of the use of the tensioner, and FIG. FIGS. 3A and 3B are longitudinal sectional views of the unequal-pitch coil spring used in FIGS.
Is a set state diagram, (d) is a state diagram slightly extended from the time of setting, FIG. 4 is a load deflection characteristic diagram of the unequal-pitch coil spring, and FIG. 5 is a twisted wire constituting the unequal-pitch coil spring. (A) is a partial side view thereof, (b) is a cross-sectional view thereof, FIG. 6 is a cross-sectional view showing a variation of the same tensioner,
FIG. 7 shows another use state of the tensioner of the present invention,
(A) is a front view, (b) is a side view, and FIGS. 8 and 9 are cross-sectional views of a conventional tensioner. DESCRIPTION OF SYMBOLS 1 ... tensioner, 2 ... tension rod, 3 ... casing, 5 ... coil spring, 9 ... unequal pitch coil spring (coil spring having nonlinear characteristics).

Claims (2)

(57) [Claims] In a tensioner for maintaining a belt or a chain in an appropriate tensioned state by extension of a tension rod, the extension of the tension rod and the maintenance of the extension state are determined by setting an inflection point of a load deflection characteristic to a set position. The tensioner is provided by a single coil spring exhibiting a non-linear characteristic by an unequal pitch attached as described above. 2. The tensioner according to claim 1, wherein the coil spring is formed using a stranded wire.