JPH0517252U - Auto tensioner - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent foreign matter from entering the case that covers the damper in an auto-tensioner with a built-in damper that keeps the belt tension constant. [Structure] A pedestal 2 attached to an engine block 1 is provided with a cylindrical surface 4. A cylindrical case 14 centered on the arm support shaft 3 is provided on an arm 6 which is swingably supported about the arm support shaft 3 provided on the pedestal 2. This case 14
One end of the cylindrical seal 27 is fixed to one of the open end and the cylindrical surface 4. A seal lip 29a provided at the other end of the seal 27 is pressed against the other to prevent foreign matter from entering.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an auto tensioner that keeps a belt tension constant in a belt transmission.

[0002]

[Prior Art]

 In belt transmissions that drive automobile accessories such as alternators, an auto tensioner is usually installed on the slack side of the belt to keep the belt tension constant.

As the above-mentioned auto tensioner, there is known one in which a swingably supported arm is biased by a torsion coil spring so that a pulley rotatably supported at the arm tip is pressed against a belt.

By the way, in the above-mentioned auto tensioner, the vibration of the belt cannot be effectively damped, and the vibration causes a problem that the durability of the belt itself or the driven object is deteriorated.

In order to solve the problem and provide a small auto tensioner, in the invention disclosed in Japanese Patent Laid-Open No. 2-102956, a fixed cylindrical case is fixed on the base side of an engine block or the like. And a torsion coil spring and a damper are installed inside the movable cylindrical case provided at the rear end of the arm, the arm is biased by the torsion coil spring and the pulley at the tip of the arm is pressed against the belt, and the damper is used to arm the arm. A rotation resistance is added to the to dampen the swing of the arm and the vibration of the belt.

In the above damper built-in type auto tensioner, if foreign matter or water enters the cylindrical case, the function of the damper may be impaired, so it is necessary to prevent the foreign matter or water from entering.

Therefore, in the auto tensioner described in the above publication, a ring groove is formed on the inner surface of the opening end of the movable cylindrical case, and the rubber seal attached to the ring groove is formed on the outer surface of the fixed cylindrical case. The close contact prevents foreign matter and water from entering.

[0008]

[Problems to be solved by the device]

 By the way, in the above-mentioned sealing structure, it is necessary to process the ring groove for holding the rubber seal and the seal contact surface with which the seal comes into close contact with extremely high precision, and the fixed cylindrical case and the movable cylindrical case are coaxial. Since it also requires a certain degree, there is a disadvantage that the processing cost becomes high.

The present invention aims to solve the above-mentioned inconveniences, reliably prevent foreign matter from entering the space for housing the torsion coil spring and the damper, and reduce the processing cost.

[0010]

[Means for Solving the Problems]

 In order to solve the above problems, according to the present invention, a pedestal having an arm support shaft is provided with a cylindrical surface centering on the arm support shaft, and an arm supported swingably about the arm support shaft. Is formed with a cylindrical case that covers the torsion coil spring for urging the arm and the vibration damping damper of the arm, and one of the cylindrical seals is fixed to the opening end of this case and one of the cylindrical surfaces. The seal lip formed on the other end of the seal was pressed against the other.

[0011]

[Action]

 When the arm swings toward the slack side or the tension side of the belt due to fluctuations in the belt tension, the seal lip of the seal rotates in close contact with the contact part to prevent foreign matter from entering the case.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 6 show a first embodiment of an auto tensioner according to the present invention.

As shown in FIGS. 1 and 2, an pedestal 2 attached to an engine block 1 serving as a base is provided with an arm support shaft 3 on the back side of the engine block 1. The outer periphery of the pedestal 2 is a cylindrical surface 4 centered on the arm support shaft 3, and a plurality of mounting legs 5 provided on the cylindrical surface 4 are screwed to the engine block 1.

The arm 6 provided on one side of the pedestal 2 has a guide cylinder 7 at one end, and the guide cylinder 7 is inserted outside the arm support shaft 3 and rotatably supported. The flange 9 of the tightening screw 8 screwed into the tip surface of the shaft 3 prevents the arm supporting shaft 3 from coming off.

Here, the arm 6 is swingable about the arm support shaft 3, and when it is in surface contact with the arm support shaft 3 and the flange 9, the contact resistance is large and the arm 6 can be swung smoothly. I can't. In order to reduce the contact resistance, a slide bearing 10 is incorporated between the arm support shaft 3 and the guide cylinder 7, and a slide plate 11 is incorporated between the flange 9 and the facing surface of the arm 6.

A pulley 13 is rotatably supported on the other end of the arm 6 via a rolling bearing 12. A cylindrical case 14 centering on the arm support shaft 3 is provided at one end of the arm 6, and a torsion coil spring 15 and a damper 16 are incorporated in the case 14.

One end of the torsion coil spring 15 is locked to the pedestal 2 side, and the other end is locked to an axially long hole 17 provided in the case 14 to urge the arm 6 to push the pulley 6. 13 is pressed against the belt 18.

The damper 16 slidably incorporates a slide cylinder 19 outside the guide cylinder 7, a guide cylinder 20 is provided outside the slide cylinder 19, and a flange 21 provided at the rear end of the guide cylinder 20 is provided. The rotation is stopped against the pedestal 2. Further, as shown in FIG. 5, a plurality of axial guide grooves 22 are formed on the inner surface of the guide cylinder 20, and the sliding cylinder 19 is provided with a ridge 23 to be inserted into the guide groove 22. The sliding cylinder 19 is prevented from rotating by the engagement of the strip 23 and the guide groove 22.

Further, as shown in FIG. 3, a spring seat 24 axially pressed by the torsion coil spring 15 is formed at the tip of the sliding cylinder 19, and an outer surface of the spring seat 24 is formed. The formed inclined cam surface 25 is brought into pressure contact with the inclined cam surface 26 provided on the inner surface of one end of the arm 6, and rotation resistance is given to the arm 6 by the contact between the inclined cam surfaces 25 and 26.

In the automatic tensioner having the above structure, when the belt 18 becomes loose, the elasticity of the torsion coil spring 15 causes the arm 6 to swing around the arm support shaft 3 toward the belt tension side. At this time, the inclined cam surface 26 on the arm side rotates in the direction of the arrow in FIG. 3, and the spring seat 24 moves toward the arm 6 side by the elasticity of the torsion coil spring 15. Therefore, the rotational resistance acting on the arm 6 is small, and the arm 6 smoothly swings in the direction in which the belt 18 is stretched, and the belt 18 is quickly tensioned.

On the other hand, when the tension of the belt 18 increases and the pulley 18 is pushed by the belt 18, the arm 6 swings around the arm support shaft 3 in the arrow direction of FIG. At this time, the inclined cam surface 26 on the arm side presses the inclined cam surface 25 on the spring seat side, so that the sliding cylinder 19 moves together with the spring seat 24 toward the pedestal 2 side against the elasticity of the torsion coil spring 15. ..

Therefore, the frictional resistance between the inclined cam surfaces 25 and 26 is large, and the frictional resistance serves as the rotation resistance of the arm 6, so that the arm 6 slowly swings in the direction in which the belt 18 is loosened.

When the auto tensioner operates as described above, foreign matter enters the case 14, and the foreign matter is caught between the inclined cam surfaces 25 and 26 or is caught between the spiral portions of the torsion coil spring 15. Then, the function of the damper 16 is hindered.

In order to prevent such inconvenience from occurring, in the present invention, as shown in FIGS. 1 and 6, one end of the cylindrical seal 27 is press-fitted or adhered to the cylindrical surface 4 of the pedestal 2. A groove 28 into which the opening end of the case 14 is inserted is formed at the other end of the seal 27, and a cylindrical outer seal lip 29a provided on the outer diameter side of the groove 28 is attached to the case 14 through the case 14. It is pressed against the outer diameter surface to prevent foreign matter from entering.

In FIG. 6, the entire inner diameter surface of the seal lip 29 a is pressed against the outer diameter surface of the case 14, but as shown in FIG. 7, the tip edge of the seal lip 29 a is the outer diameter surface of the case 14. You may make it press-contact with.

As described above, since the seal lip 29a is mounted so as to be in pressure contact with the outer diameter surface of the case 14, there is no possibility of disturbing the swing of the arm 6. In addition, since the seal structure is formed by pressure contact, it is not necessary to machine the outer diameter surface of the case 14 with high precision, and even if the cylindrical surface 4 of the pedestal 2 and the outer diameter surface of the case 14 are not coaxial with each other, it is possible to reduce The members can be reliably sealed, and the processing cost can be reduced.

The seal 27 may be fixed to the case 14 side, and the seal lip provided on the pedestal side may be brought into pressure contact with the cylindrical surface 4.

In the first embodiment, foreign matter enters the interior of the case 14 between the elongated holes 17 and the ends of the torsion coil spring 15, so that as shown in FIG. 1, an elastic plug such as rubber is used. The long hole 17 is sealed by the body 30. The stopper 30 is provided with a pair of insertion portions 32 that are inserted into both ends of the elongated hole 17 on the inner surface of a protective plate 31 that covers the entire surface of the elongated hole 17, and the inner surface of each insertion portion 32 is engaged with the inner surface of the case 14. The engaging piece 33 is provided, and the end of the torsion coil spring 15 is inserted between the insertion portions 32.

8 and 9 show a second embodiment of the auto tensioner according to the present invention. The damper 16 of the autotensioner in the second embodiment is provided with a plurality of axial holes 34 on the surface of the guide cylinder 7 facing the pedestal 2, and the sliders 35 and the sliders 35 are pedestal in each hole 34. A spring 36 to be pressed against 2 is incorporated, and the arm 6 is given a rotational resistance by the contact resistance of the slider 35.

Further, in the second embodiment, the base 2 is provided with a cylindrical fixed case 37 having the arm support shaft 3 as its center, and the cylindrical surface 38 inside the tip portion of the fixed case 37 has the first embodiment. A cylindrical seal 27 having the same shape as the above is fixed, the opening end of the arm side case 14 is inserted into a groove 28 formed on the other end surface of the seal 27, and the inner side of the groove 28 is provided inside. The seal lip 29b is pressed against the inner diameter surface of the arm-side case 14 to prevent foreign matter from entering the inside between the facing portions of the cases 14 and 37. Further, a cover 39 for covering the outer seal lip 29a provided on the outer diameter surface side of the groove 28 is provided at the tip of the fixed case 37 to protect the outer seal lip 29a.

Further, a long hole 40 that locks one end of the torsion coil spring 15 is formed in the fixed case 37, and the long hole 40 and the long hole 17 of the arm side case 14 are sealed with an elastic plug body 41. is doing.

Here, the stopper 41 is provided with an insertion portion 43 which is inserted between the end of the spring 15 and the long holes 17 and 40 on the inner surface of the protective plate 42 which covers the entire surfaces of the long holes 17 and 40. An engaging piece 44 that engages with the inner surface of each of the cases 14 and 37 is provided on the inner diameter side of the insertion portion 43.

10 and 11 show a third embodiment of the auto tensioner according to the present invention. In this embodiment, a hydraulic damper is used as the damper 16 for damping the swing of the arm 6, a spherical outer surface 46 is provided at the tip of the piston 45 of the hydraulic damper 16, and a contactor 47 that makes surface contact with the spherical outer surface 46 is provided. The inclined cam surface 48 formed on the pedestal 2 is brought into pressure contact with the arm 6 to impart rotational resistance to the arm 6.

Further, a seal 27 is incorporated between the fixed case 37 of the pedestal 2 and the case 14 of the arm 6. The seal 27 has a cylindrical shape, and a pair of annular grooves 50 and 51 into which the opening ends of the cases 14 and 37 can be inserted are provided on both end surfaces of the seal 27, and the annular groove 50 has an opening end of the fixed case 37. Is inserted and fixed, and the opening end of the arm side case 14 is inserted into the other annular groove 51, and the outer seal lip 52b of the pair of seal lips 52a and 52b formed inside and outside the other annular groove 51 is armed. It is pressed against the outer diameter surface of the side case 14.

As shown in FIG. 12, the inner seal lip 52a may be pressed against the inner diameter surface of the arm-side case 14.

Since the other structure is the same as that of the second embodiment, the description thereof will be omitted.

13 and 14 show another example of the seal 27 that seals between the facing portions of the pedestal-side fixed case 37 and the arm-side case 14. A seal 27 shown in FIG. 13 has one end of a cylindrical elastic seal 55 fixed to the outer diameter surface of a U-shaped ring 54 having a case insertion groove 53 by means such as baking.

In the seal 27 shown in FIG. 14, the end portion of the outer diameter side cylindrical portion of the U-shaped cross-section ring 56 having the case insertion groove 53 is bent to form a seal fitting groove 57 on the outside of the case insertion groove 53. After being formed, one end of a cylindrical elastic seal 58 is inserted into the seal fitting groove 57 and fixed by means such as adhesion.

In both seals, the rings 54 and 56 are fitted to one of the opening ends of the fixed case 37 and the arm-side case 14, and the lips 59 at the other ends of the elastic seals 55 and 58 are attached to the other case. It should be pressed against the outer diameter surface.

[0040]

[Effect of the device]

 As described above, in the autotensioner according to the present invention, one end of the cylindrical seal is fixed to one of the case and the cylindrical surface of the pedestal, and the seal lip provided to the other end of the seal is fixed. Since it is pressed against the other side, it is possible to reliably prevent foreign matter from entering the inside of the case.

Further, since the seal structure by press contact does not hinder the swinging of the arm, and even if the coaxiality of the arm side cover with respect to the pedestal is poor or the machining accuracy of the lip contact surface is poor, it can be reliably performed. Can be sealed. Therefore, high-precision processing is not required, and the processing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of an auto tensioner according to the present invention.

FIG. 2 is a front view of the above.

FIG. 3 is a side view showing a state in which only the above cover is cross-sectioned.

FIG. 4 is a bottom view of the above.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a cross-sectional view of the seal portion of the above.

FIG. 7 is a cross-sectional view showing another example of the above seal portion.

FIG. 8 is a vertical sectional front view showing a second embodiment of the same automatic tensioner.

FIG. 9 is a cross-sectional view of the seal portion of the same as above.

FIG. 10 is a vertical sectional front view showing a third embodiment of the same automatic tensioner.

FIG. 11 is a sectional view of the seal portion of the same as above.

FIG. 12 is a cross-sectional view showing another example of the above seal portion.

FIG. 13 is a sectional view showing another example of the same seal.

FIG. 14 is a sectional view showing another example of the same seal.

[Explanation of symbols]

 1 Engine Block 2 Pedestal 3 Arm Support Shaft 4 Cylindrical Surface 6 Arm 13 Pulley 14 Case 15 Torsion Coil Spring 16 Damper 27 Seal 29a, 29b, 59 Seal Lip

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[Procedure amendment]

[Submission date] February 1, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 14

[Correction method] Change

[Correction content]

FIG. 14

Claims (1)

[Scope of utility model registration request] 1. An arm having an arm support shaft provided on a pedestal fixed to a base, one end of which is rotatably supported about the arm support shaft, and a pulley being rotatably attached to the other end of the arm. A cylindrical case centered on the arm support shaft is provided, and a torsion coil spring that urges the arm to press the pulley against the belt in the case and a rotation resistance is applied to the arm to dampen the swing of the arm. In an auto tensioner incorporating a damper that forms a cylindrical surface centered on the pulley support shaft on the pedestal, and one end of a cylindrical seal is fixed to one of the cylindrical surface and the opening end of the case, An auto tensioner characterized in that a seal lip formed on the other end of the seal is brought into pressure contact with the other.