JP3586527B2 - Auto tensioner - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an auto-tensioner which always maintains a belt for driving an automobile accessory at an appropriate tension.
[0002]
[Prior art]
The applicant of the present application has already proposed an automatic tensioner for adjusting the tension of a belt for driving an automobile accessory such as an alternator, which is described in Japanese Utility Model Laid-Open No. 4-105245.
[0003]
As shown in FIGS. 4 and 5, the auto tensioner fixes a cylindrical housing 33 with bolts 32 screwed into an engine block 31 and swings a pulley arm 35 about a fulcrum shaft 34 provided in the housing 33. A belt guide pulley 36 is rotatably provided at the swinging end of the pulley arm 35, and the pulley arm 35 is urged by a spring 37 incorporated in the housing 33 to move the pulley 36 to a belt. A pressed.
[0004]
Further, a direct-acting hydraulic damper 38 is provided on the pulley arm 35, and a pressing force acting on the pulley arm 35 from the belt A via the pulley 36 is provided on the hydraulic damper 38, and a projecting property is provided outward by a damper spring 39. The received pressure is received by the damper member 40 and the pressing force is buffered by the hydraulic damper 38.
[0005]
In the above-mentioned auto-tensioner, when the belt A becomes slack, the pulley 36 rapidly moves in a direction to absorb the slack of the belt A. Conversely, when the tension of the belt A increases, the tension is reduced by the hydraulic damper 38. Since the belt A is received and buffered, the pulley 36 can follow the tension change of the belt A well, and the tension of the belt A can be always kept constant.
[0006]
In addition, the provision of the hydraulic damper 38 on the pulley arm 35 facilitates the assembling, and is small in size as a whole, so that it takes up little space.
[0007]
[Problems to be solved by the invention]
By the way, in the above-mentioned auto tensioner, the hydraulic damper 38 is arranged on a straight line whose center line connects the center of the bolt 32 and the center of the pulley 36, and the hydraulic damper 38 is provided with a projecting property to the outside of the hydraulic damper 38. The tip of the member 40 is brought into contact with the inclined cam surface 41 formed on the outer periphery of the housing 33, and when the tension of the belt A is increased, the damper member 40 of the hydraulic damper 38 that swings together with the pulley arm 35 moves in the upward gradient direction of the inclined cam surface 41. When the tension is buffered, a large eccentric load acts on the damper member 40 to hinder the movement of the hydraulic damper, or fretting or wear may occur on the sliding portion of the damper member 40. It is thought that it will be promoted, and there are still points to be improved.
[0008]
An object of the present invention is to provide an auto-tensioner that can prevent fretting or wear in a sliding portion of a damper member and can operate the damper member smoothly.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, according to the present invention, a fulcrum shaft is provided on a central axis of a cylindrical housing mounted on a fixed member, and a swing of a pulley arm swingably supported about the fulcrum axis is provided. side end portion of the pulley for the belt guide rotatably supported on, the interior of the cylindrical housing incorporates a spring pulley urges the pulley arm in a direction to tension the belt, the damper member slidable on the pulley arm a damper having provided, the pressing force acting on the pulley arm through the pulley from the belt in the automatic tensioner you so that to the buffer is received by the damper member, the damper, the sliding direction of the damper member is the fulcrum shaft pulley the inclined arrangement with an inclination with respect to a straight line connecting the center of the tip of the damper member to said cylindrical housing It had adopted a structure in which a pin to be contact.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS.
[0011]
As shown, a cylindrical housing 2 is provided on the outer periphery of an engine block 1 as a fixing member. The housing 2 has a cylindrical fulcrum shaft 3 at the center, and the housing 2 is fixed by tightening a bolt 4 inserted into the fulcrum shaft 3 and screwed into the engine block 1.
[0012]
A cylindrical slide bearing 5 is fitted to the fulcrum shaft 3, and a cylindrical body 7 provided at one end of a pulley arm 6 is rotatably supported by the slide bearing 5. For this reason, the pulley arm 6 can swing about the fulcrum shaft 3, and a pulley 8 for guiding the movement of the belt A is rotatably supported at the swing side end.
[0013]
Pulley arm 6, a pulley 8 is biased in a direction to tension the belt A by a spring 9 provided on the inner side of the housing 2.
[0014]
The pulley arm 6 is provided with a direct-acting hydraulic damper 10 that buffers the pressing force when the pulley arm 6 swings by receiving a pressing force from the belt A.
[0015]
The hydraulic damper 10 forms a cylinder chamber 11 having an upper end opening in the pulley arm 6, and a damper member 12 is slidably assembled in the cylinder chamber 11, and the damper member 12 is provided with an outward projecting property by a damper spring 13. are doing.
[0016]
The damper member 12 includes a rod 15 slidably penetrating an oil seal 14 attached to an upper opening of the cylinder chamber 11, and a piston 16 provided below the rod 15. A wear ring 17 is attached to the rod 15. The damper spring 13 receives the elasticity of the mounting and the wear ring 17.
[0017]
The piston 16 is provided with a passage 20 for communicating the lower pressure chamber 18 and the upper reservoir chamber 19, and the pressure in the pressure chamber 18 is higher than the pressure in the reservoir chamber 19 at the lower end of the passage 20. At this time, a check valve 21 for closing the passage 20 is provided. Reference numeral 22 denotes a spring that presses the piston 16 upward.
[0018]
Here, the cylinder chamber 11 is filled with hydraulic oil, and an air layer is provided between the hydraulic oil and the oil seal 14.
[0019]
The hydraulic damper 10 has a slanted arrangement in which the center line of the cylinder chamber 11 is inclined with respect to a straight line connecting the fulcrum shaft 3 and the center of the pulley 8. The tip is pressed against the outer periphery of a pin 23 provided in the housing 2.
[0020]
Now, when the belt A becomes slack, the pulley arm 6 swings in the direction in which the pulley 8 presses the belt A by the elastic force of the spring 9. At this time, since the rod 15 of the hydraulic damper 10 that swings together with the pulley arm 6 is in a direction away from the pin 23, the pulley arm 6 moves quickly in the direction in which the belt A is stretched, and immediately tightens the belt A. Further, the rod 15 moves outward by the elastic force of the damper spring 13, and the piston 16 also moves in the same direction as the rod 15. At this time, since the pressure in the pressure chamber 18 becomes lower than the pressure in the reservoir chamber 19, 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, so that the rod 15 is The rod moves quickly in the direction, and the rod tip comes into contact with the outer periphery of the pin 23.
[0021]
On the other hand, when the belt A is tensioned and the pulley 8 is pushed by the belt A, a pushing force acts on the rod 15 of the hydraulic damper 10. At this time, since the pressure in the pressure chamber 18 is higher than the pressure in the reservoir chamber 19, the pressing force from the belt A is buffered by the working oil sealed in the pressure chamber 18. When the above pressing force is stronger than the pressing force of the damper spring 13, the hydraulic oil in the pressure chamber 18 flows into the reservoir chamber 19 from between the sliding surfaces of the cylinder chamber 11 and the piston 16, and the rod 15 is moved by the pressing force and the damper spring 13. And slowly retreats to a position where the pressing force is balanced. Thereafter, the pulley arm 6 swings in the direction pushed by the belt A by retreating, and the tip end surface of the rod 15 of the hydraulic damper 10 rotates around the outer peripheral surface of the pin 23.
[0022]
As described above, when the pulley arm 6 is pushed by the belt A and oscillates, the tip of the rod 15 rotates on the outer peripheral surface of the pin 23, so that the eccentric load acting on the rod 15 is extremely small, and the damper member 12 smoothly moves. , And fretting or wear can be prevented from occurring in the sliding portion of the damper member 12.
[0023]
The auto-tensioner according to the above-described embodiment also has a feature that, similarly to the conventional auto-tensioner, the pulley 8 can follow the tension fluctuation of the belt A well, and can be easily attached to the belt transmission.
[0024]
In the embodiment, the damper for damping the pressing force acting on the pulley arm 6 from the belt A is constituted by the hydraulic damper 10 of the gas-liquid two-phase structure in which the air layer is provided on the working oil. Is not limited to this. For example, the damper member may include a damper member formed of a plunger and a damper spring that presses the damper member outward in the cylinder chamber, and the pressing force may be buffered by the damper spring.
[0025]
【The invention's effect】
As described above, in the present invention, the damper for damping the pressing force acting on the pulley arm from the belt via the pulley is inclined with respect to the straight line connecting the fulcrum axis and the center of the pulley, and the tip of the damper member of the damper is inclined. When the belt is tensioned and pushed by the belt, and the pulley arm swings, the tip end face of the damper member rotates along the outer circumference of the pin because it is made to contact the outer peripheral surface of the fixedly arranged pin. become.
[0026]
Therefore, the unbalanced load acting on the damper member is extremely small as compared with the conventional auto tensioner, so that the damper member can be operated smoothly and fretting and wear in the sliding portion of the damper member can be prevented. it can.
[Brief description of the drawings]
FIG. 1 is a partially cutaway front view showing an embodiment of an auto tensioner according to the present invention; FIG. 2 is a longitudinal sectional side view of the same; FIG. 3 is a cross-sectional view taken along the line III-III in FIG. Partially notched front view showing a conventional auto tensioner [Fig. 5] Vertical sectional side view of the same [Description of reference numerals]
1 engine block 3 fulcrum shaft 6 pulley arm 8 pulley 9 spring 10 hydraulic damper 12 damper member 23 pin

Claims (1)

A fulcrum shaft is provided on the center axis of the cylindrical housing attached to the fixing member, and a pulley for belt guide is rotatably supported at the swinging end of the pulley arm that is swingably supported about the fulcrum axis. Then, a spring for urging the pulley arm in the direction in which the pulley stretches the belt is incorporated inside the cylindrical housing, and a damper having a slidable damper member is provided on the pulley arm, and the pulley arm acts on the pulley arm via the pulley. in the auto tensioner pressing force was so that to the buffer is received by the damper member, the damper, inclined with an inclination with respect to a straight line sliding direction of the damper member connecting the center of the fulcrum shaft and the pulley Ototen the arrangement of the, and wherein the tip of the damper member to said cylindrical housing is provided with a pin which abuts ® Na.

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