JP2891446B2 - Auto tensioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto tensioner for applying a predetermined tension to a belt wound around a pulley.

[0002]

2. Description of the Related Art Conventionally, for example, alternators for automobiles,
An auto-tensioner is used to keep the tension of a belt wound around a plurality of accessories such as a cooler pump and a power steering pump constant. FIG. 4 is a front view showing an example of a conventional auto tensioner. In this auto tensioner, an eccentric ring-shaped eccentric member 93 is swingably fitted in an eccentric state to a sleeve 92 fixed to a fixed portion A of an engine or the like by a support shaft 91. A pulley 94 is rotatably mounted on the outer periphery via a bearing, and a tension coil spring 96 is stretched between the bracket 95 fixed to the eccentric member 93 and the fixed portion A to pull the bracket 95. Thereby, the eccentric member 93 is rotationally biased to press the pulley 94 against the belt B.

[0003]

The pressure contact position between the belt B and the pulley 94 depends on variations in the overall length of the belt B, variations in the relative position of the pulley around which the belt B is wound, and manufacturing errors in the outer diameter of the pulley. Due to the accumulation, it initially fluctuates within a range of about 1 mm along the pressing direction of the belt B (see a two-dot chain line in FIG. 4). However, in the above-described auto tensioner, since the center position of the swing of the eccentric member 93 is invariable,
In order to cope with the fluctuation of the pressed position, it is necessary to rotate the pulley 94 around the swing center of the eccentric member 93 within a predetermined angle θ. For this reason, the initial set length L of the spring 96 is changed according to the change of the pressure contact position between the belt B and the pulley 94.
, And the pressing force of the belt B by the pulley 94 fluctuates from product to product, and the original function of the auto tensioner, which keeps the belt tension constant, cannot be effectively exhibited. There was a problem.

The present invention has been made in view of the above problems, and provides an automatic tensioner that can constantly adjust a belt to a constant tension without being affected by a change in a pressure contact position between a belt and a pulley. The purpose is to do.

[0005]

In order to achieve the above object, an automatic tensioner according to the present invention is fitted to a support shaft attached to a fixed portion so as to be rotatable and adjustable while being eccentric to the outer periphery of the support shaft. An eccentric tubular fixed eccentric member fixed to the fixed portion by the support shaft, a movable eccentric member eccentrically fitted to the outer periphery of the fixed eccentric member and swingably fitted thereto, and a rotating eccentric member. A freely supported pulley, a bracket fixed to the movable eccentric member, a spring stretched between the fixed portion and the bracket, and a spring for biasing the movable eccentric member in a direction in which the pulley presses against the belt; A stopper is provided for abutting a movable eccentric member or a bracket at the time of rotation adjustment of the fixed eccentric member and positioning a rotation position of the fixed eccentric member.

[0006]

According to the auto-tensioner having the above structure, the spring is stretched between the bracket and the fixed portion while the fixed eccentric member is temporarily fixed to the fixed portion by the support shaft.
By rotating the movable eccentric member toward the belt around the fixed eccentric member by the urging force of the spring, the pulley can be brought into contact with the belt. In this state, when the fixed member is rotationally adjusted, the movable eccentric member Is eccentric with respect to the fixed eccentric member, so that the swing center position of the movable eccentric member can be moved. Accordingly, if the fixed eccentric member is rotationally adjusted in a direction in which the swing center of the movable eccentric member approaches the belt, the movable eccentric member is opposed to the biasing force of the spring by the reaction force from the belt. It will be pivoted around. Accordingly, if the fixed eccentric member is rotationally adjusted until the movable eccentric member or the bracket abuts the stopper, and the fixed eccentric member is positioned and fixed to the fixed portion in this state, the spring is always initialized to a fixed length. Can be.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a sectional view showing an embodiment of the auto tensioner of the present invention, and FIG. 2 is a front view. This auto-tensioner uses a support shaft 1 to secure a fixed portion A of an engine or the like.
The movable eccentric member 3 is fixed to the outer periphery of the fixed eccentric member 2
Is rotatably fitted, a pulley 5 is rotatably mounted on the outer periphery of the movable eccentric member 3 via a rolling bearing 4, and a bracket 6 is mounted on the movable eccentric member 3 so as to be integrally rotatable.

The support shaft 1 is formed by bolts, and is screwed and fixed to the fixing portion A with the fixed eccentric member 2 inserted. The fixed eccentric member 2 is an eccentric cylindrical member whose inner periphery is eccentric with respect to the outer periphery, and in a state where its axis Q2 is eccentric with respect to the axis Q1 of the support shaft 1,
It is fitted on the outer periphery of the support shaft 1 so as to be able to adjust the rotation. Side plates 21 and 22 are disposed at both ends of the fixed eccentric member 2, and the side plates 21 and 22 respectively connect the short cylindrical portions 21a and 22a protruding from the inner peripheral side to the fixed eccentric member 2.
Is press-fitted into the inner periphery of the fixed eccentric member 2 so as to be integrally rotatable. A tongue piece 21b protrudes from one of the side plates 21, and an engagement hole 21c for engaging a tool for adjusting the rotation of the fixed eccentric member 2 is formed through the tongue piece 21b. ing.

The movable eccentric member 3 is formed by press-fitting an eccentric ring 32 around the outer periphery of an end of a sleeve 31. The sleeve 31 is fixedly eccentric member 2 via an annular friction member 23.
Is swingably inserted into the housing. The axis of the sleeve 31 is concentric with the axis Q2 of the fixed eccentric member 2, and the axis Q3 of the eccentric ring 32 is eccentric with respect to the axis Q2 of the fixed eccentric member 2. Therefore, the eccentric ring 32 of the movable eccentric member 3 can swing about the axis Q2 of the fixed eccentric member 2, and the fixed eccentric member 2 can be rotated and adjusted about the axis Q1 of the support shaft 1. Thus, the swing center can be moved and adjusted. The eccentric ring 32 also serves as an inner ring of the rolling bearing 4, and a track 41 is formed on the outer periphery thereof.

The bracket 6 is fitted to the outer periphery of the sleeve 31 of the movable eccentric member 3 so as to be integrally rotatable, and has an annular base 6 that is press-fitted into the outer periphery of the sleeve 31.
1 and an arm 62 extending obliquely upward from the base 61 (see FIG. 3). A tension coil spring 7 for rotatingly biasing the movable eccentric member 3 in a direction in which the pulley 5 presses the belt B is stretched between the tip of the arm 62 and the fixed portion A. Further, a pin-shaped stopper 8 for projecting the arm 62 of the bracket 6 is provided on the fixing portion A so as to protrude. The stopper 8 is removably inserted into the fixed portion A.

With the above construction, the tension coil spring 7 is stretched between the fixed portion A and the bracket 6 while the fixed eccentric member 2 is temporarily fixed to the fixed portion A by the support shaft 1. Due to the tensile force of the tension coil spring 7, the movable eccentric member 3 is moved around the axis Q2 of the fixed eccentric member 2 as shown in FIG.
, The pulley 5 can be brought into contact with the belt B by rotating clockwise. Next, the tool is engaged with the engagement hole 21c of the side plate 21, and the swing center Q2 of the movable eccentric member 3 is moved.
If the fixed eccentric member 2 is rotationally adjusted clockwise so as to approach the belt B, the movable eccentric member 3 can be rotated counterclockwise by the reaction force from the belt B.
When the arm 62 of the bracket 6 hits the stopper 8, the rotation of the fixed eccentric member 2 is stopped,
By further screwing the support shaft 1 and positioning and fixing the fixed eccentric member 2, the tension coil spring 7 can always be set to a constant initial set length L. Therefore, even if the pressure contact position between the belt B and the pulley 5 fluctuates due to variations in the overall length of the belt B, the belt B can be pressed with a constant pressure by the automatic tensioner. The stopper 8 is pulled out from the fixed portion A after the fixed eccentric member 2 is fixed.

The auto-tensioner according to the present invention is not limited to the above embodiment.
May abut a predetermined portion of the movable eccentric member 3, or may be provided, for example, on the automatic assembly device side other than the fixed portion A.

[0013]

As described above, according to the auto tensioner of the present invention, even if the pressure contact position between the belt and the pulley fluctuates, the initial setting length of the spring stretched between the bracket and the fixing portion can be reduced. Since the belt can be kept constant, it has a unique effect that the belt can always be adjusted to a constant tension.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of an auto tensioner of the present invention.

FIG. 2 is a front view of the same.

FIG. 3 is a rear view of the same.

FIG. 4 is a front view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support shaft 2 Fixed eccentric member 3 Movable eccentric member 5 Pulley 6 Bracket 7 Tension coil spring 8 Stopper A Fixed part

Claims (1)

(57) [Claims] An eccentric tubular fixed eccentric member fitted to a support shaft attached to a fixed portion so as to be rotatable and adjustable on an outer periphery of the support shaft and fixed to the fixed portion by the support shaft. A movable eccentric member that is swingably fitted to the outer periphery of the fixed eccentric member, a pulley rotatably supported by the movable eccentric member, a bracket fixed to the movable eccentric member, and fixed. A spring that is stretched between the section and the bracket, and that urges the movable eccentric member to rotate in a direction in which the pulley presses against the belt; and abuts the movable eccentric member or the bracket when rotating the fixed eccentric member. An auto-tensioner comprising: a stopper for positioning a rotation position of a fixed eccentric member.