JPH1027U - Auto tensioner - Google Patents

Abstract

(57) [Summary] [Purpose] In an auto-tensioner that maintains the belt tension at a set tension, the tension is smoothly adjusted with respect to the fluctuation of the belt tension. A pulley is rotatably attached to an arm supported swingably about a fulcrum shaft. A one-way hydraulic damper 12 is incorporated in the arm 7, and the plunger 14 of the hydraulic damper 12 is brought into contact with the braking surface 6 provided on a fixedly arranged case outer peripheral surface. When the belt becomes slack,
The arm 7 is rapidly moved to the belt tension side by the elastic force of the elastic member 10 applied to the arm 7. When the belt is tensioned and the arm 7 swings to the belt slack side due to the belt, the plunger 14 is brought into contact with the braking surface 6.
Is slowly retracted, and the arm 7 is slowly swung toward the slack side of the belt by the frictional force acting on the contact portion between the braking surface 6 and the plunger 14.

Description

[Detailed description of the invention]

[0001]

[Industrial applications]

 The present invention mainly relates to an automatic tensioner for maintaining the tension of a belt for driving an automobile auxiliary machine at an appropriate tension.

[0002]

[Prior art]

 As an auto-tensioner for maintaining the tension of a belt for driving an automobile accessory such as an alternator at an appropriate tension, the one shown in FIG. 3 is conventionally known.

The auto tensioner fixes a housing 32 by tightening a bolt 31 screwed into an engine block 30, and a cylindrical portion provided at a rear end of an arm 34 outside an arm support shaft 33 provided on the housing 32. A pulley 36 is rotatably mounted on the tip of the arm 34, and the arm 34 is urged by a torsion coil spring 37 incorporated in the housing 32, thereby pulling the pulley 3. 6 is pressed against a belt not shown.

Further, axial holes that open at the rear end surface of the cylindrical portion 35 are provided at equal intervals in the circumferential direction, and a friction member 39 is provided in each of the holes 38 and a spring that presses the friction member 39 against the bottom surface of the housing 32. 40 is incorporated to attenuate the swing of the arm 34 and the vibration of the belt due to the contact resistance of the friction member 39.

[0005]

[Problems to be solved by the invention]

 By the way, in the above-mentioned auto tensioner, the frictional resistance of the frictional member 39 which attenuates the swing of the arm 34 is always constant, and the frictional resistance needs to be set large so as to withstand the maximum load fluctuation. Therefore, the swing of the arm 34 must be slow in both directions of the tension side and the slack side of the belt.

For this reason, when the belt is suddenly loosened due to engine start or the like, the arm 34 tends to swing in a direction for applying tension to the belt, but due to the frictional resistance, the arm 34 cannot swing smoothly, and the arm 34 cannot swing smoothly. Abnormal noise is generated by the vibration, and there is no proper tension on the belt, causing problems such as tooth skipping.

It is a technical object of the present invention to solve the above-mentioned inconvenience and to provide an auto-tensioner capable of smoothly adjusting the tension with respect to the fluctuation of the belt tension.

[0008]

[Means for Solving the Problems]

 In order to solve the above-mentioned problem, in the present invention, a fulcrum shaft protruding from a fixed portion, an arm swingably supported about the fulcrum shaft, and a rotatable tip end of the arm are provided. An auto-tensioner, comprising a pulley supported by a pulley and an elastic member for urging the arm in the direction in which the pulley pushes the belt, is slidably provided with an outward projecting property by a spring. A hydraulic damper, which has a plunger and buffers a pushing force applied to the plunger by a hydraulic pressure sealed in the back thereof, is disposed on a plane orthogonal to the fulcrum axis, and the tip of the plunger is provided at the tip of the plunger. Assembled inside the arm so that it is located outward from the outer periphery of the arm, and the tip of the plunger is brought into contact with the arm. The abutment member configuration provided a fastening arrangement for loading a pushing force to Nja is adopted.

[0009]

[Action]

 In the above-mentioned auto tensioner, when the belt is loosened, the arm swings in the direction in which the belt is stretched by the elasticity of the elastic member. At this time, since the plunger of the hydraulic damper does not receive the pushing force from the contact member, the sliding resistance of the plunger with respect to the contact member is small, and the arm swings quickly in the direction of tensioning the belt.

When the tension of the belt increases, the pulley is pushed by the belt, and the arm swings in a direction to loosen the belt, the plunger of the hydraulic damper is slowly retracted by receiving the pushing force from the contact member. As a result, the sliding resistance of the plunger with respect to the contact member is large, and the arm swings slowly in the direction in which the belt is loosened.

[0011]

【Example】

 As shown in FIGS. 1 and 2, a bolt 2 is screwed into a base 1 such as an engine block, and an arm support member 3 is attached by tightening the bolt 2.

The arm support member 3 has a cylindrical fulcrum shaft 4 through which the bolt 2 is inserted. A case 5 as a cylindrical contact member is provided outside the fulcrum shaft 4. On the outer periphery of the distal end portion of the case 5, there is provided an inclined braking surface 6 having a circumferential gradient in which the radius from the center of the fulcrum shaft 4 gradually increases from one end to the other end.

A rear end of an arm 7 is rotatably supported at a front end of the fulcrum shaft 4, and a pulley 9 is rotatably supported at a front end of the arm 7 via a bearing 8. . The arm 7 is urged by an elastic member 10 composed of a torsion coil spring incorporated in the case 5 and the pulley 9 is pressed against the belt 11. In addition, a linear motion type hydraulic damper 12 is incorporated in the arm 7 so as to face the braking surface 6.

The hydraulic damper 12 has a plunger 14 slidably incorporated in a cylinder chamber 13 formed in the arm 7, and a piston 16 and a spring 16 in an axial hole 15 opened at the rear end surface of the plunger 14. The spring 17 presses the rear end of the piston 16 against the bottom surface of the cylinder chamber 13 and the front end of the plunger 14 against the braking surface 6.

Further, a pressure chamber 18 is formed inside the plunger 14 by incorporating the piston 16, and the pressure chamber 18 and a reservoir chamber 19 provided inside the piston 16 are filled with hydraulic oil. , 19 are communicated through a passage 20 formed in the plunger 14, and the opening of the passage 20 on the pressure chamber 18 side is opened and closed by a check valve 21.

In the auto-tensioner having the above configuration, when the belt 11 is loosened, the elastic force of the elastic member 10 causes the arm 7 to rotate around the fulcrum shaft 4 in the direction in which the belt 11 is stretched, as shown by the arrow in FIG. Rocks.

At this time, the plunger 14 of the hydraulic damper 12 slides along the braking surface 6 and moves downward in the gradient direction, and the movement of the plunger 14 lowers the pressure in the pressure chamber 18. The check valve 21 opens the passage 20, and the hydraulic oil in the reservoir chamber 19 flows from the passage 20 to the pressure chamber 18. Therefore, the plunger 14 smoothly moves outward, the frictional resistance of the plunger 14 against the braking surface 6 is small, and the arm 7 swings quickly in the direction in which the belt 11 is stretched.

When the tension of the belt 11 increases and the pulley 9 is pushed by the belt 11, the arm 7 swings around the fulcrum shaft 4 in a direction to loosen the belt 11. At this time, the plunger 14 slides on the braking surface 6 and moves in the upward gradient direction. As a result, the plunger 14 is pushed into the cylinder chamber 13 and the pressure in the pressure chamber 18 increases, so that the check valve 21 closes the passage 20 and the operating oil in the pressure chamber 18 slides between the plunger 14 and the piston 16. Leakage enters the reservoir chamber 19 from between the surfaces, and the plunger 14 gradually retreats into the cylinder chamber 13.

Therefore, the sliding resistance of the plunger 14 with respect to the braking surface 6 is large, and the sliding resistance acts as the swing resistance of the arm 7, so that the arm 7 swings slowly in the direction in which the belt 11 becomes slack. .

[0020]

[Effect of the invention]

 As described above, in the auto-tensioner according to the present invention, the hydraulic damper is incorporated in the arm and the plunger of the hydraulic damper is brought into contact with the fixedly arranged contact member, so that the belt can withstand the fluctuation of the belt. The tension can be adjusted smoothly.

Further, since the hydraulic damper is arranged on a plane orthogonal to the fulcrum axis and the plunger is moved on the plane, the arm receives the pressing force by which the plunger presses the abutting member, and the arm moves with respect to the plane. Without tilting, preventing uneven wear on the thrust bearing surface of the bearing part that supports the arm so that it can swing freely, and at the same time, the pulley tilts and the belt hits one side. This prevents uneven wear and lateral running of the belt.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment of an auto tensioner according to the present invention.

FIG. 2 is a side view of the above.

FIG. 3 is a longitudinal sectional front view showing a conventional auto tensioner.

[Explanation of symbols]

 4 fulcrum shaft 5 case 7 arm 9 pulley 10 elastic member 12 hydraulic damper 14 plunger 17 spring

Claims (1)

[Utility model registration claims] 1. A fulcrum shaft protruding from a fixed portion, an arm supported swingably about the fulcrum shaft, a pulley rotatably supported at a tip end of the arm, and a pulley. An auto-tensioner comprising an elastic member for urging the arm in the direction of pushing the belt, the auto-tensioner having a slidable plunger provided with an outward projecting property by a spring, and applying a pushing force applied to the plunger. A hydraulic damper, which is buffered by hydraulic pressure sealed in the back, is arranged on a plane perpendicular to the fulcrum axis, and the tip of the plunger is located outward from the outer periphery of the arm. The plunger has a fixed arrangement in which the tip of the plunger abuts and the tension of the belt increases and the arm swings to apply a pushing force to the plunger. An auto tensioner having a contact member.