JPS6267358A - Tensioner for endless driving belt - Google Patents

Abstract

PURPOSE:To obtain the good follow-up action for change of a load, by eccentrically fixing a bearing supporter to a supporting bed through an initial tension adjusting spring and fixing a ball bearing fixed ring to an eccentric collar turnably provided in the bearing supporter through a tension adjusting spring. CONSTITUTION:A tensioner, turning a bearing supporter 10 to be displaced and giving initial tension to a belt through an initial tension adjusting spring 35, is fixed to a supporting bed 40 by a bolt 18. The tensioner, receiving force by a ball bearing 30 from the belt, turns the center O1 of the bearing 30 about the center O2 of the bearing supporter 10 serving as the center through an eccentric collar 25 integrally formed with an inner ring 31, and the tensioner, applying an initial load to a tension adjusting spring 36, applies secondary initial tension to the belt. If tension of the belt rapidly increases, the tensioner, displacing the inner ring 31 to be turned in a belt advancing direction about O2 serving as the center through the collar 25 against the spring 36, decreases the tension, and if the tension rapidly decreases, restoring force, previously applied to the spring 36, acts on the collar 25, and the tensioner, turning the inner ring oppositely to the belt advancing direction, performs a follow-up movement.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a tensioner for an endless drive belt, and in particular, to a tensioner for an endless drive belt, which can quickly follow changes in belt tension and suppress changes in belt tension to a minimum. This is what I did.

[Conventional technology]

Conventionally, this type of tensioner has been used, for example, in a timing belt for driving a camshaft of a vehicle engine or a belt for driving other auxiliary equipment.

This tensioner is attached to the engine block on the slack side of the timing belt, which is stretched endlessly between the timing bobber on the crank side and the timing pulley on the camshaft side, and is set to a predetermined initial tension (for example, By applying +rf to 20 to 30, the occurrence of tooth skipping between the timing belt and the timing belt meshing therewith is prevented.

As this type of tensioner, fixed tensioners and automatic tensioners are known.

A fixed tensioner has a structure in which the inner ring of a rolling bearing is fitted onto the outer circumferential surface of a bearing carrier. One end of a torsion coil spring is fixed to the engine block, and the other end is fixed to the bearing carrier. was rotated to apply twisting force to the torsion coil spring. In this state, the bolts are inserted into the eccentric bolt holes of the bearing carrier to secure it to the engine block and apply initial tension to the timing belt.

As an automatic tensioner, for example, a proposal related to West German Published Patent Application No. 2524744 is known, in which the inner ring of a rolling bearing is eccentric with respect to a tightening member fixed to a fixed housing by a tightening port. The belt is held rotatably, and a torsion coil spring fixed between the inner ring (eccentric ring) and the tightening member brings the eccentric ring into contact with the belt at an appropriate rotational position to apply initial tension to the belt. When the tension fluctuates, the belt tension is automatically adjusted by rotating the eccentric ring using a torsion coil spring, and the rotation angle of the eccentric ring relative to the tightening member is The restriction is achieved by sliding a stopper bin provided on one of the and eccentric wheels in a groove provided on the other.

[Problem that the invention seeks to solve]

The fixed tensioner mentioned above operates normally when used at room temperature, but when temperature changes occur, the following problems occur due to the difference in dimensional changes between the engine block and timing belt. do. That is, for example, the linear expansion coefficient of an aluminum engine block is 24 x
10-6/'c, but since the linear expansion coefficient of the timing belt with reinforcing wire is 6 x 10-'/'C, the engine block is larger than the timing belt at low temperatures. Due to the contraction, the distance between the timing pulleys shortens and the belt loosens, which increases belt vibration and may cause tooth skipping.On the other hand, at high temperatures, In this case, the elongation between the timing pulleys is greater than the elongation of the timing heald, increasing belt tension (for example, belt tension increases by about 20 kgf under operating conditions of about 80°C), which reduces belt durability. This will result in a decline.

On the other hand, automatic tensioners do not suffer from the above-mentioned problems due to temperature changes, but they do have problems when the timing belt starts, stops, or when braking suddenly, or when foreign objects get caught between the belt and the timing pulley. When the belt tension on the loose side increases and the tensioner receives a large load, such as when tightening, the tightening member rotates rapidly and sensitively around the port position by an amount that balances the load. , the belt is thrown off the belt, and because the belt cannot follow the movement when it suddenly loosens, the belt vibrates each time, which causes the tooth skipping phenomenon. In particular, there is a problem in that tooth skipping is likely to occur when the engine is started with low belt tension at low temperatures.

As for the load function of the automatic tensioner mentioned above, if the timing belt is only given a predetermined initial tension, a torsion coil spring with low rigidity can be used. For this reason, it is necessary to prevent sudden vibrations of the belt using a torsion coil spring with high rigidity.

However, the same torsion coil spring cannot simultaneously satisfy these contradictory conditions.

Therefore, although conventional automatic tensioners are sufficient for the initial tension, they cannot provide the necessary and sufficient followability to minimize changes in belt tension during sudden load changes. It turns out.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a tensioner that separately and independently has the function of applying initial tension to an endless drive belt and the function of suppressing changes in tension during load fluctuations.

[Means for solving problems]

In the tensioner of the present invention, the central axis of the bearing carrier fixed to the support base at an eccentric position and the axis of the rolling bearing are eccentrically arranged, and the fixed ring of the rolling bearing is rotatably fitted to the outer peripheral surface of the bearing carrier. A spring member is provided between the bearing carrier and the support base to apply an initial tension to the endless drive belt, and a spring member is provided between the eccentric collar and the bearing carrier to apply an initial tension to the endless drive belt. A spring member is provided to adjust the tension during fluctuations.

[1, Part A] 1. When a sudden load change occurs on the east end drive belt, the eccentric collar rotates against the spring member installed between it and the bearing 11 or due to the restoring force of the spring member. , the axis of the rolling bearing rotates around the central axis of the bearing carrier (7
It quickly follows the movement of the endless drive belt.

A spring for adjusting the tension of the endless drive belt by 1 during this load change υJ (the Q member and the spring member for applying initial tension are selected and used with different rigidities depending on their functions. .

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1. FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, and FIG. This is a cross-sectional view taken along the line b.

In the above figure 1, the code 10 indicates the small diameter part 11 and the large diameter part 12.
This shows a hollow cylindrical bearing carrier consisting of - on the small diameter side.
...An eccentric bolt hole 14 is provided in the bottom part 13 of the wire, and the other end on the large diameter side is an open end. A torsion coil spring 35, which will be described later, is accommodated in the large diameter portion 12 of the bearing carrier 10, and the open end of the large diameter portion is brought into contact with a support base 40 such as an engine block, and the small diameter portion side is placed in contact with a support base 40 such as an engine block. Cover the bottom 13 with the lid 15, insert the positioning pin 17,
Align the bolt holes 16 of the lid 15 with the bolt holes 14 of the bottom 13, insert the bolts 18, and insert the bolts 18 into the support base 4.
It is designed to be fixed by screwing onto the 0.

A sliding bearing 22 having a flange 23 at one end is mounted on the outer peripheral surface of the small diameter portion 11 of the bearing carrier 10.
is fitted into contact with the stepped surface of the bearing carrier 10.

An inner ring (fixed ring) 31 of a rolling bearing 30 centered at a point O, which is eccentric by 62 from the center 02 of the bearing carrier 10, is fitted onto the outer peripheral surface of the sliding bearing 22 via an eccentric collar 25. There is. The inner ring 31 of the rolling bearing 30 and the eccentric collar 25 are press-fitted and fixed, and the eccentric collar 25 has a flange 26 provided at one end thereof.
It is rotatably fitted to the outer circumferential surface of the slide bearing 22 in a state where it is brought into contact with the flap and rung 23 of the slide bearing 22.

The inner ring 31 of the rolling bearing 30 includes balls 3 as rolling elements.
2, and an outer ring 33 is rotatably assembled.

The eccentric distance δ2 between the axis 01 of the rolling bearing 30 and the center axis 02 of the bearing carrier 10 and the eccentric collar 25 is the eccentric distance δ2 between the center O8 of the bolt hole 14 of the bearing carrier 10 and the axis O5 of the rolling bearing 30. The eccentric distance between them is smaller than the eccentric distance δ1.

Further, a torsion coil spring 36 is provided between the eccentric collar 25 and the bearing carrier 10. This torsion coil spring 36
is attached so as to surround the outer periphery of the large diameter portion 12 of the bearing carrier 10, and the leg 36a at one end is attached to the bearing carrier 10.
The leg 36b at the other end is fixed to the large diameter portion 12 of the eccentric collar 2.
The flange 26c of No. 5 is attached correctly.

If the tensioner has the above configuration, the outer ring 3 of the rolling bearing 30
An endless drive belt (not shown) comes into contact with the outer peripheral surface between the pot parts 34 extending on both sides in the axial direction of the tensioner 3 and is rotated. After fixing the leg 35a at one end and the leg 35b at the other end of the tear coil spring 35 housed in the bearing carrier 10 to the bearing carrier 10 and the support base 40, respectively, turn the tensioner by an appropriate angle. Turn the torsion coil spring 35 and tighten the bolt 18 while it is in contact with the belt.
is screwed onto the support base 40 and fixed. As a result, the tensioner is deflected within the limit of the eccentric distance δ1, and a predetermined initial tension is applied to the endless drive belt with which the outer ring 33 of the rolling bearing 30 comes into contact.

In addition, at the stage where this initial tension is applied, the rolling bearing 30 naturally receives force from the belt and rotates via the eccentric collar 25 integrated with the inner ring 31, causing torsion between the eccentric collar 25 and the bearing carrier 10. The coil spring 36 is in a twisted state beforehand. As a result, the axial center OI of the rolling bearing 30 rotates around the central axis 02 of the bearing carrier 10, so that a secondary initial tension is applied to the endless drive belt.

If a sudden load change occurs during operation of the endless drive belt, for example when the belt tension increases and the tensioner is under a large load, the rolling bearing 30 will move around the bearing carrier 10 via the eccentric collar 25. By rotating in the traveling direction of the belt, it follows the movement of the belt, and when the belt tension returns to normal, the torsional force added to the torsion coil spring 36 when the belt tension increases is restored and the rolling is prevented. The bearing 30 is returned to its original position.

Also, contrary to the above, when the belt tension decreases and the load on the tensioner is reduced, the restoring force of the torsion force applied in advance to the torsion coil spring 36 when setting the initial tension acts on the eccentric collar 25, causing it to roll. The bearing 30 is the bearing carrier 10
When the belt tension returns to normal, the rolling bearing 30 rotates around the bearing carrier 10 in the direction of belt travel to follow the movement of the belt. and return to the original position.

The rotation of the rolling bearing 30 when the tensioner follows the movement of the belt due to fluctuations in belt tension is caused by the movement of the inner ring 31.
Since the eccentric collar 25, which is fitted integrally with the slide shaft 22, is fitted into the sliding shaft auger 22, this can be done smoothly. Rolling bearing 30
The axial movement and slight angular runout of the bearing carrier 10
It is limited by the stepped surface on the large diameter side and the side surface of M2S on the small diameter side.

As mentioned above, the tear coil spring 35 provided between the bearing carrier 10 and the support base 40 is a spring dedicated to setting the initial tension of the belt, and the torsion coil spring 35 provided between the eccentric collar 25 and the bearing carrier 10 is a spring dedicated to setting the initial tension of the belt. 36 is a spring mainly for adjusting the tension 3FI when the belt load fluctuates, so the torsion coil spring 36 for tension adjustment is selected to have greater rigidity than the torsion coil spring 35 for setting the initial tension. There is a need.

Further, the amount of deviation due to rotation of the rolling bearing 30 with respect to the bearing carrier 10 can be arbitrarily changed by appropriately selecting the eccentric distance δ2 of the eccentric collar 25. Therefore, the eccentric distance 1ya δ2 is set to be the most appropriate distance depending on the load conditions of the endless drive belt used.

3 and 4 show other embodiments of the invention,
A tension coil spring is used instead of a torsion coil spring for setting the initial tension.

The bearing carrier IO has a bracket 19 fixed on its outer periphery, a lower end 19a of the bracket 19 is rotatably attached to a support base 40 with a pin 20, and a hook at one end of the tension coil spring 37 is attached to the upper end 19b of the bracket 19. The hook at the other end is fixed to the support base 40.

Further, the bearing carrier 10 has a bolt hole I4 provided at its center.
The bolt 18 is inserted into the support base 40 to fix it to the support base 40.

The bolt hole 14 of the bearing carrier 10 is cut on both the left and right sides to form an arc-shaped groove 21a, and the bolt hole 16 of 5 is also formed with a groove 21b of the same shape. 21b are overlapped with each other in a matching state.

This tensioner moves the bearing carrier 1o to its center position T:
After fixing to the support base 4o with the bolt 18, the tension coil spring 37 is pulled, and the bearing carrier 10 is rotated about the pin 2° of the lower end 1.92 of the bracket 19 as a fulcrum, so that it contacts the belt at an eccentric position. By bringing them into contact, a predetermined initial tension is applied to the belt.

The configuration other than the above is the same as the embodiment shown in Fig. 1, and the belt tension adjustment function when the belt load fluctuates is also the same, so the same parts are given the same reference numerals and repeated explanations will be omitted. .

In the two embodiments described above, the inner ring and the eccentric collar are separate bodies, but they can also be integrated.

〔Effect of the invention〕

As explained above, in the tensioner of the present invention, the spring member that applies the initial tension to the endless drive belt and the spring member that adjusts the tension when the load fluctuates are separately provided. The ability to follow load fluctuations is quick, and changes in belt tension can be suppressed to a minimum.

Therefore, if the present invention is applied as a tensioner for a timing belt, it is possible to suppress the wave motion of the belt and to prevent the tooth skipping phenomenon from occurring between the timing pulley and the timing belt.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a longitudinal sectional view showing another embodiment of the invention. Figure 4 is its front view. In the figure, 10 is a bearing carrier, 25 is an eccentric collar, 30 is a rolling bearing, 31 is a fixed ring of the rolling bearing, 35 is a torsion coil spring (for initial tension setting), 36 is a torsion coil spring (for tension adjustment), 40 is the support base, δ is the eccentric distance of the bolt hole of the bearing carrier, and δ2 is the eccentric distance of the eccentric collar. 1st FM Figure 2

Claims (1)

[Claims] In an endless drive belt tensioner comprising a bearing carrier fixed to a support base at an eccentric position and a rolling bearing rotatably assembled on the outer periphery of the bearing carrier, the axis of the rolling bearing is relative to the central axis of the bearing carrier. eccentric,
A fixed ring of a rolling bearing is fitted and fixed to an eccentric collar rotatably fitted to the outer peripheral surface of a bearing carrier, and a spring member is provided between the bearing carrier and the support base to apply initial tension to the endless drive belt. A tensioner for an endless drive belt, characterized in that a spring member is provided between the eccentric collar and the bearing carrier to adjust the tension of the endless drive belt when the load fluctuates.