JPH0746831Y2 - Belt tension adjustment device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a belt tension adjusting device for keeping the tension of a timing belt of an engine constant, and in particular, it absorbs slack of the belt due to aging and The present invention relates to a so-called belt tensioner that holds the.

[Conventional technology]

In a small engine or the like, a fixed belt tensioner has been conventionally used to maintain the belt tension. The fixed belt tensioner does not have the function of keeping the tension of the belt constant by following the slack of the belt.Therefore, in a vehicle equipped with such an engine, if the mileage reaches tens of thousands of km, it may change with time. In order to remove the slack, it is necessary to adjust the belt tension at repair shops.

In order to eliminate such maintenance, it has been proposed to use a belt tensioner having a one-way clutch and a ratchet mechanism in place of the fixed tensioner (Japanese Utility Model Publication No. 64-15851 and Japanese Utility Model Publication No. 64-7940).

[Problems to be solved by the device]

However, a belt tensioner equipped with a one-way clutch and a ratchet mechanism always has play in the axial direction and the circumferential direction. Since the force acting on the tension pulley from the belt is always a fluctuating load, the rattling as described above easily causes abrasion and damage, resulting in lack of durability.

Therefore, an object of the present invention is to provide a belt tension adjusting device capable of smoothly following the slack of the belt due to a change with time and the like and keeping the tension of the belt.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention rotatably supports a pulley shaft by inserting a fulcrum bolt at an eccentric position of a pulley shaft facing a surface of a pulley pedestal integrated with a fixing member. The fulcrum bolt is fixed to a fixing member, one end of a tension adjusting spring that urges the pulley in the belt tension direction is attached to the pulley shaft, and the inner end surface of the pulley shaft on the pulley seat side is fixed in the radial direction from the fulcrum bolt. A pin parallel to this is provided at a distance, and behind the pin when viewed in the rotation direction of the pulley shaft by the urging force of the tension adjusting spring,
A screw insertion arm along the pin is provided on the pedestal, and a male screw is screwed into the screw insertion arm at a right distance from the fulcrum bolt from the side opposite to the pin, and the tip of the male screw is pressed against the pin. , One end of a torsion coil spring attached to the rear end portion of the male screw is engaged with the pulley pedestal, the male screw is screwed by the coil spring in a direction to push the pin, and the pin is pushed to the pulley shaft. The tension adjusting spring applies a rotational torque in the same direction as the tension adjusting spring.

[Action]

The belt tension adjusting device described above is normally used in a state in which the rotational torque due to the tension of the belt, the rotational torque due to the tension adjusting spring facing the belt and the sum of the rotational torque due to the force pushing the pin by the male screw are balanced. Stop.

When the belt is loosened, the balance is lost, and the pulley follows the looseness of the belt and swings to maintain the tension. Further, simultaneously with the swinging of the pulley, the male screw moves forward while rotating by the spring force of the torsion coil spring, and no gap is created between the tip and the focus.

〔Example〕

A pulley 1 of the embodiment shown in the drawings comprises an inner ring 3 fixed around a pulley shaft 2 and an outer ring 5 rotatably held via a rolling element 4.

A slide bearing 6 is inserted into the pulley shaft 2 at an eccentric position,
The fulcrum sleeve 7 is inserted into the inner diameter surface of the slide bearing 6. The axial length of the fulcrum sleeve 7 is formed to be slightly longer than the axial length of the pulley shaft 2.

A fulcrum bolt 8 is inserted into the fulcrum sleeve 7. The fulcrum bolt 8 penetrates the pulley base 9 and is fixed to a fixing member 10 such as an engine block by screwing. Fulcrum bolt 8
Washers 11 and 11 ′ are respectively interposed between the head of the fulcrum and the fulcrum sleeve 7 and between the other end of the fulcrum sleeve 7 and the pulley pedestal 9. The fulcrum sleeve 7 is, as described above, the pulley shaft 2
Since it is formed to be slightly longer, even if the fulcrum bolt 8 is tightened, it does not hinder the rotation of the pulley shaft 2.

Around the pulley shaft 2 described above, an arm is provided inside the inner ring 3.
The bosses 13 of 12 are press-fitted and integrated with the pulley shaft 2.
One end of a tension adjusting spring 14 is engaged with the arm 12.

On the other hand, the pulley pedestal 9 is provided with a screw insertion arm 9a projecting from the fulcrum bolt 8 on the inner end surface of the pulley shaft 2, and a pin 16 parallel to this is fixed to the fixing member 10.
Is projected in the direction of.

The positional relationship between the screw insertion arm 9a and the pin 16 is such that the screw insertion arm 9a has the pin 16 when viewed in the direction in which the pulley shaft 2 is rotated by the urging force of the tension adjusting spring 14 (see arrow B in FIG. 2). Is in a position along the pin 16 behind.

The male screw 15 is screwed into the screw insertion arm 9a from the surface opposite to the pin 16. The tip of the male screw 15 penetrates to the pin 16 side and is pressed against the pin 16.

The male screw 15 may be a normal bolt, but in the case of the illustration,
It has a sawtooth shape in which the flank angle of the thread surface on the front end side is high and the flank angle of the thread surface on the rear end side is low. Due to the above-described difference in the flank angle of the thread surface, the male screw 15 moves with a small rotational torque in the forward direction, but requires a large rotational torque for the backward movement. A vertical groove 18 is formed at the rear end of the male screw 15, and one end of a torsion coil spring 19 inserted around the rear end is engaged with the vertical groove 18. The other end of the torsion coil spring 19 is engaged with a screw 20 screwed into the pulley base 9. The spring 19 applies a rotational torque to the male screw 15 to rotate it in the forward direction, and a rotational torque to the pulley shaft 2 via the pin 16.

Therefore, the stopper pin is attached to the pulley shaft 2 so that the male screw 15 does not come out in the forward direction in the state before assembly.
21 is penetrated, and the tip end side surface is a side surface 23 of the pulley pedestal 9.
Apply to.

The belt tension adjusting device of the embodiment is configured as described above,
The fulcrum bolt 8 is fastened to the fixing member 10, the belt 22 is hung on the outer ring, and then the stopper pin 21 is removed.

Then, the belt 22 gives a rotational torque in the direction of arrow A in FIG. Further, the spring force of the tension adjusting spring 14 and the male screw 15 give a rotational torque in the direction of arrow B. The swinging of the pulley 1 is stopped at the balance point of both rotational torques, and the tension of the belt 22 is kept constant.

From this state, the belt 22 is slackened so that the pulley 1 is indicated by the arrow B.
When it is swung in the direction, the pin 16 integrated with the pulley shaft 2
Since the male screw 15 moves in the direction away from the tip of the pin 15, the male screw 15 moves forward while rotating by the spring force of the torsion coil spring 19 and follows the pin 16 (see FIG. 4).

At this time, the end of the torsion coil spring 19 on the male screw 15 side is
It moves relatively to the rear end of the vertical groove 18.

Contrary to the above, when the tension of the belt 22 increases, a force acts in the backward direction of the male screw 15 via the pin 16, but this force causes the rear flank surface of the male screw 15 to move to the rear flank surface of the female screw. It acts to press and locks the male screw 15 with respect to the female screw. Since the frictional force in this case is sufficiently large especially in the case of a low flank angle, the male screw 15 does not retract.

[Effect of device]

As described above, according to the present invention, the tension of the belt is kept constant by the balance of the sum of the rotational torque due to the belt tension, the rotational torque due to the tension adjusting spring facing the belt tension, and the rotational torque due to the pressing force of the male screw, while maintaining the belt tension constant. A rotating torque is applied to the shaft by a torsion coil spring, and its tip is pressed against a pin protruding from the pulley shaft. Therefore, when the pulley sways following the slack of the belt, the male screw does not move forward to cause a gap with the pin. Further, when the tension of the belt increases, the male screw is locked and does not move backward. Therefore, the pulley of the present invention smoothly moves to follow the slack of the belt over time and maintains its tension constant, and there is no rattling in the mating portion of the male screw. There is.

[Brief description of drawings]

FIG. 1 is a vertical side view of the embodiment, and FIG. 2 is II-II of FIG.
FIG. 3 is a front view of the same as that of FIG. 1, and FIG.
FIG. 11 is a cross-sectional view in another state along the line II-II. 1 ... Pulley, 2 ... Pulley shaft, 3 ... Inner ring, 4 ... Rolling element, 5 ... Outer ring, 6 ... Slide bearing, 7 ... Support sleeve, 8 ... Support bolt, 9 ... Pulley seat ,,Ten……
Fixing member, 11 …… washer, 12 …… arm, 13 …… boss part,
14 …… tension adjusting spring, 15 …… male screw, 16 …… pin, 18…
… Vertical split groove, 19 …… Torsion coil spring, 20 …… Screw, 21
…… Stopper pin, 22 …… Belt.

Claims (1)

[Scope of utility model registration request] 1. A fulcrum bolt is inserted into an eccentric position of a pulley shaft facing a surface of a pulley pedestal integrated with a fixing member to rotatably support the pulley shaft, and the fulcrum bolt is fixed to the fixing member. Fix and attach one end of a tension adjusting spring that urges the pulley in the belt tension direction to the pulley shaft, and keep a certain distance in the radial direction from the fulcrum bolt on the inner end surface of the pulley shaft on the pulley seat side and parallel it. A projecting pin, the screw inserting arm along the pin is provided on the pedestal behind the pin when viewed in the rotation direction of the pulley shaft by the biasing force of the tension adjusting spring, and the screw inserting arm is provided with the pin. A male screw is screwed in at a right angle from the opposite side at a certain distance from the fulcrum bolt, the tip of the male screw is pressed against the pin, and one end of a torsion coil spring attached to the rear end of the male screw is attached to the pulley base. Belt tension adjustment in which the male screw is screwed in the direction of pressing the pin by the coil spring, and the pin is pressed to impart a rotational torque in the same direction as the tension adjusting spring to the pulley shaft. apparatus.