JP3527583B2 - Belt tensioner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt tensioner, and more particularly, to a tensioner for a timing belt of, for example, an engine of an automobile. 2. Description of the Related Art A belt tensioner is used to apply an appropriate tension to a belt such as a timing belt of an automobile engine. FIG. 3 shows a conventional timing belt tensioner, in which a tension pulley 3 is rotatably mounted around a shaft 1 via a bearing 2, and a shaft hole 4 is formed at an eccentric position of the shaft 1. A stat bolt 6 screwed and fixed to 5 is inserted into the shaft hole 4, and a lock nut 7 is attached to a tip of the stat bolt 6. A coil portion 9 of a tension setting spring 8 composed of a torsion coil spring is wound around the shaft 1 between the bearing 2 and the engine block 5, and one end of the coil portion 9 is connected to a stud bolt 6.
To form a bent portion 11, which is inserted into the locking hole 12 of the engine block 5 and locked. Further, the other end 1 of the tension setting spring 8 is provided.
3 is locked in a locking hole 14 provided in a radial direction at a position apart from the stud bolt 6 on the outer peripheral surface of the shaft 1. As a result, the tension setting spring 8 biases the shaft 1 to eccentrically rotate it. [0005] The tensioner having the above-described structure operates with the lock nut 7 while the belt 15 is pressed against the tension pulley 3.
Is loosened, the tension pulley 3 rotates eccentrically to an angle at which the spring force of the tension setting spring 8 and the tension of the belt 15 are balanced. When a predetermined tension is applied to the belt 15 and the lock nut 7 is tightened and fixed to the engine block 5, the belt 15 is held at a constant tension. In the tension pulley as described above, the operation of inserting and locking the end of the tension setting spring 8 into the locking hole 12 of the engine block 5 or the locking hole 14 of the shaft 1 is performed. Although it has to be done manually, the work is more difficult because it requires skill and must be performed in a very narrow space between the tension pulley 3 and the engine block 5. Furthermore, a jig is required to urge the shaft 1 by eccentric rotation in order to apply tension to the belt 15, which hinders workability. Further, the need to machine the shaft hole 4 in the shaft 1 also causes an increase in the cost of the tensioner. It is an object of the present invention to improve the workability of assembling a tensioner and to reduce the cost. [0008] In order to achieve the above object, the present invention is directed to a tension pulley mounted on a fixed block, and the tension pulley is attached to a belt by a spring force of a tension setting spring comprising a torsion coil spring. The tension pulley is rotatably supported by a hollow shaft, and the hollow shaft is movably fixed in a radial direction by a fixed shaft member inserted into the tension pulley. Attached to a block, the coil portion of the tension setting spring is extrapolated to the hollow shaft, a locking portion is provided on a fixed block at a position away from the upper portion of the hollow shaft in a direction opposite to the belt, and the coil of the torsion coil spring is A fulcrum end is provided at a tip of a linear portion extending from one end of the portion, the fulcrum end is locked to the locking portion, and the fulcrum end extends from the other end of the coil portion. The straight portion is extended between the locking portion and the belt beyond the straight portion, and a bent portion is provided between the locking portion and the belt to be bent in the opposite direction to the belt. The bent portion is locked to the same locking portion as the fulcrum end in a state where the spring force is generated by largely elastically bending, and the hollow shaft is fixed by the fixed shaft member. After the fulcrum end of the tension setting spring is locked to the locking pin while the tension pulley is in contact with the belt, the bending angle of the bending portion at the other end of the spring is further increased. When elastically deformed and the engaging recess of the bent portion is locked to the locking pin, the elastic force of the bent portion moves the hollow shaft and the tension pulley supported by the hollow shaft to apply a predetermined tension to the belt. I do. Then, the hollow shaft is fixed to the fixed block by the fixed shaft member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. The first embodiment shown in FIG. 1 and FIG.
A rolling surface 22 is formed on the outer periphery of the distal end of the hollow shaft 21, and a plurality of balls 25 are interposed between the outer race 24 press-fitted and fixed to the inner peripheral surface of the tension pulley 23 and the above-mentioned rolling surface 22. Thus, the pulley 23 is rotatably supported. Note that, instead of the configuration in which the rolling surface 22 is directly provided on the hollow shaft 21, a configuration in which a bearing inner ring is fitted to the outer diameter of the hollow shaft 21 can be adopted. A fixing bolt 26 having an outer diameter smaller than the inner diameter is inserted into the hollow shaft 21, and a washer 28 is interposed between the bolt head 27 and the end face of the hollow shaft 21. The fixing bolt 26 is inserted and fixed in the engine block 29, and fixes the hollow shaft 21 to the engine block 29 via the washer 28. When the fixing bolt 26 is loosened, the hollow shaft 21 slides between the inner surface of the washer 28 and the engine block 29 and can move in the radial direction within a range of a diameter difference from the fixing bolt 26. A coil portion 32 of a tension setting spring 31 composed of a torsion coil spring is extrapolated around the hollow shaft 21 between the tension pulley 23 and the engine block 29. As shown in FIG. 2, one end of the tension setting spring 31 is formed with a linear portion 41 extending from the coil portion 32, and the tip of the straight portion 41 is bent into a hook shape to form a fulcrum end 33. The other linear portion 42 extending from the coil portion 32 intersects with the linear portion 41, and
A bent portion 38 which extends between the belt 7 and the belt 36 and is bent about 90 degrees toward the locking pin 37 is formed at that portion.
An engagement recess 39 is formed in the bent portion 38. In the natural state of the tension setting spring 31 described above,
The bent portion 38 exists above the locking pin 37, but after the fulcrum end 33 is locked to the locking pin 37, the bent portion 38 is elastically deformed so as to further increase the bending angle (FIG. 2), the engaging recess 39 is locked to the surface of the locking pin 37 on the tension pulley 23 side (see the dashed line in FIG. 2). Thereby, a constant tension balanced with the spring force of the tension setting spring 31 is applied to the belt 36. The operation of applying a predetermined tension to the belt 36 by the tensioner having the above-described structure is performed by bringing the tension pulley 23 into contact with the belt 36 and temporarily fastening the fixing bolt 26 to the fulcrum end of the tension setting spring 31. 33 is locked to the locking pin 37 and the other bent portion 38 is elastically deformed as described above.
The coil portion 32 swings around the fulcrum 3 to move the hollow shaft 21 and the tension pulley 23 supported by the hollow shaft 21 to apply a predetermined tension to the belt 36 (see a dashed line in FIG. 2). When the engaging recess 39 of the bent portion 38 is locked to the locking pin 37, the tension of the belt 36 is set to a constant value. In this state, the fixing bolt 26 is firmly fastened to the engine block 29 to fix the hollow shaft 21. The present invention is as described above, and exhibits the following effects. (1) A predetermined tension can be easily applied to the belt simply by locking both ends of the tension setting spring to one locking pin of a fixing member such as an engine block. Workability when incorporating a spring is improved. (2) After the fulcrum end of the tension setting spring is locked to the locking pin, the bent portion at the other end is further bent and deformed to be locked to the same locking pin as described above. Since tension can be applied, there is the convenience that no special jig is required. (3) Since a hollow shaft is used as a support member for the tension pulley, it is not necessary to machine an eccentric hole in the shaft as in the prior art, and thus the weight and cost of the tensioner can be reduced.

[Brief description of the drawings] FIG. 1 is a longitudinal sectional side view of an embodiment. FIG. 2 is a longitudinal sectional front view of the above. FIG. 3 is a longitudinal sectional side view of a conventional example. [Explanation of symbols] 21 hollow shaft 22 Rolling surface 23 tension pulley 24 Outer ring 25 balls 26 Fixing bolt 27 bolt head 28 Washer 29 engine block 31 Tension setting spring 32 coil part 33 fulcrum end 36 belt 37 Locking pin 38 Bend 39 engagement recess 41 Straight section 42 straight section

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16H ^7/ 00-7/24 F02B 67/06

Claims (1)

(57) [Claim 1] A tension pulley is attached to a fixed block, and the tension pulley is pressed against a belt by a spring force of a tension setting spring composed of a torsion coil spring to apply a predetermined tension. Belt tensioner
The tension pulley is rotatably supported by a hollow shaft, and the hollow shaft is mounted on the fixed block so as to be movable in a radial direction by a fixed shaft member inserted therein, and a coil portion of the tension setting spring is attached to the hollow shaft. Inserting, a locking portion is provided on a fixed block at a position away from the upper portion of the hollow shaft in a direction opposite to the belt, and a fulcrum end is provided at a tip of a linear portion extending from one end of the coil portion of the torsion coil spring. The fulcrum end is locked to the locking portion, and a linear portion extending from the other end of the coil portion is extended between the locking portion and the belt beyond the linear portion, and the locking portion is A bent portion is provided between the belts and bent in the opposite direction to the belt, and the bent portion is bent more elastically to generate a spring force so that the bent portion is fixed to the same locking portion as the fulcrum end. Locked, said fixed shaft member Belt tensioner, characterized in that more fixed the hollow shaft.