JP2002139110A - Tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply desirable tension to a timing chain. SOLUTION: A tensioner comprises a shaft member 3 inserted in a case 2 for axial to-and-fro motion, an extruding spring 6 for applying driving force to the shaft member 3, a clutch 4 for engaging the shaft member 3 when the shaft member 3 is retreated to lock motion in the same direction and disengaging the shaft member 3 when the shaft member 3 is advanced, and a hydraulic means for applying oil pressure in the advance direction of the shaft member 3 to damp an input load on the shaft member 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tensioner for keeping the tension of an endless belt or chain constant.

[0002]

2. Description of the Related Art A tensioner presses an endless belt or chain, for example, a timing chain or a timing belt used in an automobile engine, with a predetermined force. Used to keep constant.

[0003] JP-A-8-152051 and 9-
No. 793305 discloses a conventional tensioner using a clutch. These tensioners hold the timing chain in the engine at a predetermined tension by abutting the shaft,
The shaft is inserted into the case so as to be able to move forward and backward. The shaft is urged in the extension direction by an extruding spring housed in the case.

A clutch for locking and releasing the shaft from moving forward and backward is arranged in the case. The clutch is detachable from the outer periphery of the shaft. This engagement and disengagement is performed by a screw structure. For this reason, a male screw portion is formed on the outer periphery of the shaft, and a female screw portion is formed on a surface of the clutch facing the shaft. Such engagement and disengagement is performed by moving the clutch in the radial direction of the shaft, and engaging (engaging) with the threaded portion of the shaft by moving the clutch in the radial direction.
Then, the clutch is disengaged from the engagement with the screw portion by moving in the radially expanding direction.

[0005] The radial movement of the clutch member is performed by a clutch guide disposed in a case. For this reason, the clutch guide has an inclined surface for guiding the clutch in the expanding / contracting direction. Further, in addition to the clutch guide, a clutch pressing spring for pressing the clutch is disposed in the case, and urges the clutch to move in the diameter reducing direction in which the clutch is engaged with the shaft.

[0006] Such a tensioner is attached to the engine in a locked state in which the shaft is prevented from advancing, and when the lock is released after the attachment to the engine, the shaft linearly advances by the spring force of the push-out spring. At this time, since the clutch moves in the radially expanding direction along the inclined surface of the clutch guide, the engagement (biting) with the shaft is released. As a result, the shaft comes into contact with the timing chain to apply tension.

When the engine is driven with such a shaft in contact with the timing chain, a load acts on the shaft from the timing chain. Then, when a load is applied in the pushing direction of the shaft, the shaft is retracted, and with this retraction, the clutch is engaged with the shaft to restrain the shaft from retracting. On the other hand, when the load from the timing chain decreases, the shaft advances by the spring force of the push-out spring, and the engagement of the clutch is released with this advance, and tension is applied to the timing chain. Therefore, by the above operation, the tensioner operates to apply a constant tension to the timing chain.

[0008]

In the conventional tensioner, the shaft is urged by an extruding spring.
The shaft moves forward and backward to respond to the increase and decrease of the load from the timing chain. Therefore, the input load from the timing chain is ultimately received by the push-out spring, and the amount of deflection of the push-out spring changes according to the magnitude of the input load. That is, when the input load is small, the deflection amount of the push-out spring is small, and when the input load is large, the deflection amount is large.

As described above, in the conventional tensioner, since the push-out spring receives the input load directly, when the push-out spring receives a large input load, the push-out spring needs to be largely bent correspondingly. May deteriorate. In the conventional tensioner, a clutch that engages with the shaft is provided so as to be freely engaged and disengaged. However, the basic operation of moving the shaft forward and backward is the same, and even in this case, the deflection of the pushing spring corresponds to the input load. And has the same problem as described above.

The present invention has been made in consideration of such conventional problems, and an object of the present invention is to provide a tensioner having good followability with respect to an input load.

[0011]

In order to achieve the above object, the present invention is directed to a shaft member inserted into a case so as to be able to advance and retreat in an axial direction, and an extruding spring for applying a propulsive force to the shaft member. When the shaft member retreats, it engages with the shaft member to lock the movement in the same direction, and when the shaft member advances, disengages from the engagement with the shaft member, and applies a hydraulic pressure in the advance direction of the shaft member. And a hydraulic means for attenuating the load input to the shaft member.

According to the present invention, the shaft member is advanced in the axial direction by the spring force of the push-out spring. In this advance,
Since the clutch is disengaged from engagement with the shaft member, the shaft member can be smoothly propelled, and tension can be applied. On the other hand, when a load is input to the shaft member, the shaft member retreats, and the clutch is engaged with the shaft member by the retreat. For this reason, the tension can be maintained without the shaft member retreating more than necessary.

[0013] The hydraulic means acts on the shaft member to apply oil pressure in the advance direction, and also acts to attenuate the input load to the shaft member based on the viscous resistance and fluid resistance of the oil. Thereby, the deflection of the push-out spring and the viscosity resistance and fluid resistance of the oil correspond to the input load to the shaft member, so that the followability to the input load is improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the clutch is capable of moving forward and backward along a shaft member within a predetermined stroke range in a state where the clutch is engaged with the shaft member. And

When the clutch is engaged with the shaft member, the clutch moves back and forth in a predetermined stroke range. When the clutch deviates from the predetermined range, the clutch disengages from the engagement of the shaft member. By setting this constant stroke to be able to absorb the slack allowance of the chain due to the temperature drop after the engine is stopped, the engagement position between the clutch and the shaft member does not change even after the engine is cooled. Therefore, even when the chain is stretched due to a temperature rise due to the engine start, the shaft member returns to the initial state, and the initial characteristics can be secured.

On the other hand, when a large load is input from the chain due to the high rotation of the engine, a push-back force acts on the shaft member. At this time, the shaft member is pushed back in a state in which the clutch is engaged, so that the shaft member does not return more than necessary, and the slack of the chain can be prevented. In addition to this, the damping effect of the hydraulic means is added,
It can respond well to the input load from the chain.

According to a third aspect of the present invention, in the first or second aspect, the shaft member moves forward and backward along the case when a propulsive force is applied by the pushing spring and the guide shaft inserted into the case. A movable plunger, wherein the clutch engages with and disengages from the guide shaft and has a receiving surface for receiving the plunger retreating.

According to the present invention, since the plunger of the shaft member moves along the case, even if an eccentric load in a direction inclined with respect to the axial direction is input, the eccentric load can be well coped with. Further, since the receiving surface for receiving the retreat of the plunger is provided on the clutch, the retreat of the plunger due to the input load can be controlled.

A fourth aspect of the present invention is the invention according to any one of the first to third aspects, wherein the clutch moves in a direction intersecting the axial direction of the shaft member to engage and disengage with the shaft member. And a guide means for guiding the movement of the clutch in a direction intersecting the axial direction of the shaft member is provided in the case.

In the present invention, the engagement and disengagement of the clutch with the shaft member are performed in a direction intersecting with the axial direction of the shaft member, so that the shaft member can smoothly move forward and backward. Further, since the guide means is provided, the movement of the clutch becomes smooth, and the clutch can be smoothly engaged and disengaged from the shaft member.

A fifth aspect of the present invention is the invention according to any one of the first to fourth aspects, wherein the clutch has a shape in which a nut is divided into a plurality of parts, and the shaft member has a threaded portion with which the clutch engages. Is formed.

As described above, by forming the nut into a divided shape, the clutch can be easily formed, and can be easily arranged in the case.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described more specifically with reference to the drawings. In each of the embodiments, the same elements are assigned the same reference numerals.

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention. The tensioner 1 according to this embodiment includes a case 2, a shaft member 3, and a clutch 4.

The case 2 has a storage hole 2a formed in the longitudinal direction. The shaft member 3, the clutch 4, the clutch guide 5, and other components are stored in the storage hole 2a. In this embodiment, the storage hole 2a is a three-step hole. A mounting flange 2b for mounting to the engine is formed on the outer surface of the case 2 so as to protrude, and a mounting hole 2c penetrates the mounting flange 2b.

The shaft member 3 is inserted into the intermediate hole of the storage hole 2a along the axial direction of the case 2, and is freely movable in the axial direction with respect to the case 2. The shaft member 3 is urged to move in the axial direction of the case 2 by a spring force of an extrusion spring 6 described later, and the shaft member 3 advances from the case 2 by this movement. The distal end portion (right end portion) of the shaft member 3 has a large diameter and is drawn out of the case 2 to form a shoe portion 3a that comes into contact with a timing chain (not shown). On the outer peripheral surface of the shaft member 3, a male screw portion 7 with which a clutch 4 described later is engaged in a meshing manner is formed.

The movement of the shaft member 3 in the forward and backward directions is guided by the shaft guide 8. The shaft guide 8 is formed by a cylindrical guide body 8a and a flange portion 8b that is integrally bent in a radial direction from a tip portion (right end portion) of the guide body 8a. Guide body 8
a is fitted in the intermediate hole of the storage hole 2a, and extends in the longitudinal direction of the shaft member 3 in this fitted state to guide the shaft member 3 to move forward and backward.

A damper spring 9 is disposed between the flange 8b, which is integrally bent at the end of the shaft guide 8, and the outer hole of the case 2, so that an excessive input load is applied. Is restricted by the spring force.

The front end surface of the flange portion 8b of the shaft guide 8 supports a clutch guide 11 in contact therewith. The clutch guide 11 is inserted so as to extend to the distal end portion of the case 2 with the shaft member 3 penetrating the center portion. The clutch 4 is a clutch guide 1
1.

The clutch 4 is a divided body having a shape obtained by dividing a nut into two parts. As shown in FIG. 2, the clutch 4 is disposed in the clutch guide 11 so that a pair thereof is opposed to each other. A female screw portion 12 that meshes with the male screw portion 7 of the shaft member 3 is formed on the opposed inner surface of the clutch 4.

The above-described clutch guide 11 is formed in a cylindrical shape as a whole, and has on its inner surface a first guide surface 11a having an inclined surface whose diameter gradually increases outward, and a first guide surface 11a.
And the second guide surface 11b, which is a similar inclined surface outside the guide surface 11a, is formed intermittently so as to be located inside and outside. These guide surfaces 11 a and 11 b are tapered surfaces whose diameter gradually decreases in the retreating direction of the shaft member 3.

A stroke portion 11c extending linearly in the axial direction is formed between the guide surfaces 11a and 11b. The stroke portion 11c contacts the outer surface of the clutch 4 and guides the clutch 4 to move linearly in this contact state. In this case, the stroke portion 11c guides the clutch 4 so as to linearly move within a predetermined stroke range L while being engaged with the shaft member 3.

On the other hand, a tapered contact surface 4a is formed on the base end surface (left end surface) of each clutch 4 similarly to the guide surfaces 11a and 11b. When the tapered surface 4a is in contact with the first guide surface 11a, the female screw portion 12 of each clutch 4
Each clutch 4 is supported by the clutch guide 11 in a state in which the clutch 4 is disengaged from the engagement with the shaft member 3 in a state in which the clutch 4 is engaged with the male screw portion 7 and abuts on the second guide surface 11b.

A bearing 13 through which the shaft member 3 penetrates is attached to the tip of the case 2, and is prevented from coming off by a circlip 14. The bearing 13 guides the shaft member 3 to advance and retreat when the shaft member 3 penetrates.
The inner diameter portion of the bearing 13 has a cylindrical shape through which the shaft member 3 penetrates, and a guide surface 13a inclined in the same direction as the above-described guide surfaces 11a and 11b is formed at the base end of the cylindrical shape. . On the other hand, at the tip of each clutch 4,
A contact surface 4b corresponding to the guide surface 13a is formed.
When the contact surface 4b contacts the guide surface 13a,
The clutch 4 moves radially outward and disengages from the engagement with the shaft member 3.

In such an embodiment, the clutch 4 slides on the guide surfaces 11a and 11b of the clutch guide 11 to move in a direction intersecting the axial direction of the shaft member 3 to engage with the shaft member 3 and break away. Therefore, the clutch guide 11 and the guide surface 13 a of the bearing 13 constitute guide means for guiding the clutch 4 in a direction intersecting the axial direction of the shaft member 3.

A washer 15 is in contact with the tip of the clutch 4, and a clutch pressing spring 16 is disposed between the washer 15 and the above-described bearing 13. The clutch pressing spring 16 urges the contact surface 4a of the clutch 4 so as to contact the first guide surface 11a of the clutch guide 11, and the clutch 4 is engaged with the shaft member 3 by this urging. I have.

At the center of the shaft member 3 described above,
A hollow oil reservoir 17 is formed in the axial direction,
The above-described push-out spring 6 is inserted into the oil reservoir 17. An oil supply hole 18 communicating with the inner hole of the case 2 is formed at the base end of the case 2. The oil of the engine is supplied to the oil supply hole 18 as described later. The oil supply hole 18 communicates with the oil sump 17 via the inner hole, whereby oil is supplied to the oil sump 17 of the shaft member 3. In addition,
A tubular spring guide 19 for guiding the spring 6 is provided at a base end (left end) of the extruding spring 6.

A check valve 20 made of a sphere is inserted into the inner hole of the case 2. Check valve 20
The oil supply hole 18 is urged by a check spring 21 composed of a small coil spring disposed in the inner hole in a direction in which the oil supply hole 18 is closed. Therefore, when the pressure of the oil becomes larger than the spring force of the check spring 21, the oil supply hole 1
8 flows into the case 2.

A relief hole 22 is formed in the outer hole of the case 2, and the inside of the case 2 communicates with the outside through the relief hole 22. Further, a spherical relief valve 23 is provided in a portion of the case 2 communicating with the outside of the relief hole 22 in the relief spring 2 made of a small coil spring.
4 are provided, and the relief hole 22 is closed by the relief valve 23. When the pressure of the oil supplied into the case 2 overcomes the spring force of the relief spring 24, the relief valve 23 is opened and the oil is discharged.

In such an embodiment, the oil reservoir 17 of the shaft member 3, the storage hole 2a of the case 2, and the oil supply hole 18 act to apply oil pressure in the advance direction of the shaft member 3 when oil is supplied. It functions as a hydraulic means to make it work.

FIG. 3 shows a state where the tensioner 1 of this embodiment is mounted on an engine body 31. A pair of cam sprockets 32, 32 and a crank sprocket 33 are arranged on the engine body 31, and a timing chain 34 is extended endlessly between the sprockets 32, 32, 33. A chain guide 35 is swingably disposed on the movement path of the timing chain 34, and the timing chain 34 moves while sliding on the chain guide 35. Lubricating oil (not shown) is sealed inside the engine body 31.

The tensioner 1 is mounted on the engine body 31 with the mounting flange 2b of the case 2 abutting on the outer surface of the engine body 31. In this state, the shaft member 3
The shoe portion 3a of FIG. 3 abuts on the chain guide 35, and applies a pushing force to the timing chain 34 via the chain guide 35. Also, the oil supply hole 1 of the tensioner 1
Reference numeral 8 is connected to the engine main body 31 via an oil pipe 36, and the oil of the engine main body 31 is supplied into the tensioner 1 to lubricate the inside of the tensioner 1.

In the tensioner 1 of this embodiment, oil from the engine body 31 is supplied to the oil supply hole 18.
Further, through the check valve 22, the space of the storage hole 2 a of the case 2 including the oil reservoir 17 of the shaft member 3 is filled. In this state, the clutch 4 is actuated by the spring force of the clutch pressing spring 16.
1 abuts on the first guide surface 11a, and the female screw portion 12
Are engaged with the male screw portion 7 of the shaft member 3.

At this time, the shaft member 3 advances by the spring force of the pushing spring 6. The clutch 4 engaged with the shaft member 3 moves in the advance direction together with the shaft member 3. The meshing state of the clutch 4
Are the first guide surface 11a of the clutch guide 11 and the second guide surface 11a.
While moving between the guide surfaces 11b.

The clutch 4 is connected to the guide surface 1 of the bearing 13.
When reaching the position 3a, the guide surface 13a comes into contact with the contact surface 14b, so that the clutch 4 moves outward along the second guide surface 11b of the clutch guide 11, and is disengaged from the shaft member 3. As a result, the shaft member 3 pushes the timing chain 34 and the timing chain 34
Maintain tension. The disengagement state of the clutch 4 is continued while the clutch 4 is supported on the second guide surface 11b of the clutch guide 11.

Next, when a load is input from the engine to the shaft member 3, the shaft member 3 retreats into the case 2 while bending the push-out spring 6, whereby the clutch 4 meshes with the shaft member 3. In this meshing state, the clutch 4 retreats together with the shaft member 3 until it comes into contact with the first guide surface 11a of the clutch guide 11. When the clutch 4 comes into contact with the first guide surface 11 a of the clutch guide 11, the damper spring 9 receives the shaft member 3 through the clutch guide 11. Therefore, the shaft member 3 is not pushed back more than necessary, and the tension of the timing chain 34 can be kept constant.

In such a structure, the spring force of the push-out spring 6 and the damper spring 9 inside the shaft member 3 opposes the input load. At the same time, the oil from the engine body 31 filled in the oil reservoir 17 of the shaft member 3 and the storage hole 2a of the case 2 has a viscosity resistance,
The input load is attenuated by fluid resistance or the like. Accordingly, since the oil damping action in addition to the spring force of the push-out spring 6 and the damper spring 9 opposes the input load, the ability to follow the input load is improved, and the tension of the timing chain 34 can be kept good.

In this embodiment, when the clutch 4 is engaged with the shaft member 3, a certain stroke range L
Is moved linearly and deviates from the stroke range L,
The clutch 4 is disengaged from the meshed state with the shaft member 3. In a cold state after the engine is stopped, the timing chain 34 tends to loosen and the shaft member 3 tends to advance, but in this embodiment, the shaft member 3 is engaged with the clutch 4 and the shaft member 3 engaged.
, The shaft member 3 does not advance beyond necessity beyond meshing. Therefore, in the warm state after the engine is started, the shaft member 3 can return to the initial state, and the initial characteristics can be secured.

When a large load is input from the timing chain 34 and a push-back force is applied to the shaft member 3, the shaft member 3 is pushed back in a state where the clutch 4 is engaged. 34 can be prevented. In a region other than the clutch engagement region, the clutch 4 has been disengaged from the shaft member 3, so that the shaft member 3 advances by the spring force of the push-out spring 6 to cope with the elongation of the timing chain 34. can do.

FIG. 4 shows a modification of this embodiment.
In this embodiment, the clutch 4 having a shape in which the nut is divided is connected to one.
The clutch guide 11 has a first guide surface 11a corresponding to one clutch 4 and a second guide surface 11a.
Guide surface 11b is formed. As described above, even when only one clutch 4 is used, the same operation as described above can be performed. In this embodiment, the damper spring 9 and the shaft guide 8 are omitted from the embodiment of FIG. 1, but they may be assembled.

FIG. 5 shows still another modification of this embodiment. This embodiment has a structure in which the damper spring 9 and the shaft guide 8 are omitted from the embodiment of FIG. 1, and the other members are the same as those of FIG. For this reason, it can operate similarly to FIG.

In the embodiment shown in FIGS. 4 and 5, a relief flow passage 25 coaxially communicating with the oil reservoir 17 is formed at the tip end of the shaft member 3, and the oil supply hole 18 extends through the oil reservoir 17. An excess amount of the oil supplied to the shaft member 3 is discharged from a distal end portion of the shaft member 3.

(Embodiment 2) FIG. 6 shows Embodiment 2 of the present invention. The tensioner 1 according to this embodiment has a structure shown in FIG.
A single guide surface 11d is formed on the clutch guide 11 in the tensioner 1 shown in FIG. Guide surface 1
1d is an inclined surface whose diameter gradually increases toward the outside, whereby the guide surface 11d is a tapered surface whose diameter gradually decreases in the retreating direction of the shaft member 3.
The guide surface 11d is formed so as to have a length greater than the thickness of the clutch 4. The clutch 4 is initially engaged with the shaft member 3 when moving along the guide surface 11d. When the shaft member 3 has been moved, it is released from engagement with the shaft member 3.

In this embodiment, the operation is substantially the same as that of the first embodiment, so that the input load from the timing chain 34 can be followed well, and the tension of the timing chain 34 can be maintained well. be able to. In this embodiment, the linear stroke portion 11c of the first embodiment is not formed on the clutch guide 11. Therefore, in this embodiment, the engagement and release of the clutch 4 with the shaft member 3 are performed in conjunction with the advance and retreat of the shaft member 3. Since the guide surface 13a of the bearing 13 guides the movement of the clutch 4 in the disengagement direction, it can surely be disengaged from the shaft member 3.

Third Embodiment FIGS. 7 to 9 show a tensioner 41 according to a third embodiment. In this embodiment, the shaft member 3 is composed of two members, the guide shaft 42 and the plunger 43. Guide shaft 4
2 is inserted into the storage hole 2 a so as to extend in the axial direction of the case 2. A washer 44 is in contact with the base end of the guide shaft 42, and a damper spring 9 that opposes when a large load is input is inserted between the washer 44 and the case 2.

The outer surface of the guide shaft 42 has a clutch 4
The male screw portion 7 is formed so that the female screw portion 12 of the female screw portion can be engaged and disengaged. The oil reservoir 17 communicating with the oil supply hole 18 of the case 2 penetrates the guide shaft 42 in the axial direction.

The plunger 43 is formed in a tubular shape whose end is closed, and is inserted between the guide shaft 42 and the inside of the storage hole 2 a of the case 2. Guide shaft 42
Is inserted in the plunger 43, and a shaft hole 43a is formed in the axial direction. The plunger 43 is in contact with the inner surface of the storage hole 2a of the case 2,
It moves forward and backward with respect to case 2. The movement of the plunger 43 in the advance direction is performed by the spring force of the push-out spring 6 inserted into the case 2.

The push-out spring 6 is externally inserted into the guide shaft 42. In this embodiment, an intermediate washer 45 externally inserted into the intermediate portion of the guide shaft 42 and a flange 42a at the base end of the guide shaft 42 are provided. It is located between.

Extrusion spring 6 in intermediate washer 45
The clutch 4 is disposed on the side opposite to the above. Similar to the first embodiment, the clutch 4 has a split body shape in which a nut is divided into two parts, and is inserted between the pushing spring 6 and the plunger 43. The clutch 4 is urged by the clutch pressing spring 16 disposed between the clutch 4 and the intermediate washer 45 so as to contact the plunger 43.

On the opposing surface of the clutch 4 and the plunger 43, a guide surface 4 for moving the clutch 4 in the direction of engaging and disengaging the male thread 7 of the guide shaft 42.
d and 43d are formed. These guide surfaces 4d
And 43d are inclined surfaces whose diameter gradually increases toward the outside, and are thereby formed in a tapered shape whose diameter gradually increases in the retreating direction of the plunger 43. In this case, the guide surface 4d of the clutch 4 is a receiving surface for receiving the retreat of the plunger 43 when the plunger 43 retreats, and thereby controls the retreat of the plunger 43 due to the input load.

In addition to the above, the plunger 43 is formed with a relief channel 25 for discharging oil. The relief flow passage 25 is formed in a direction intersecting with the axial direction of the plunger 43, and communicates with the shaft hole 43a.

Next, the operation of this embodiment will be described with reference to FIGS.
This will be described with reference to FIG. In these figures, oil from the engine body 31 is supplied to the oil reservoir 17 of the guide shaft 42 through the oil supply hole 18 and the check valve 22.
And the space of the storage hole 2a of the case 2 is filled. In FIG. 7, the clutch 4 is pressed against the plunger 42 by the spring force of the clutch pressing spring 16, whereby the female screw portion 12 of the clutch 4 meshes with the male screw portion 7 of the guide shaft 42.

In this state, the plunger 43 advances by the spring force of the pushing spring 6. By this advance, the clutch 4 is spread radially outward along the guide surface 43d of the plunger 43, and disengages from engagement with the guide shaft 42 as shown in FIG. Therefore, plunger 4
3 advances until it comes into contact with the timing chain 34, and balances with the tension of the timing chain 34.

The plunger 43 is the timing chain 34
, The clutch 4 is pushed out toward the plunger 43 by the spring force of the clutch pressing spring 16. This causes the clutch 4 to move in the diameter reducing direction along the guide surface 43d, so that the clutch 4 meshes with the guide shaft 42 as shown in FIG.

From the timing chain 34 to the plunger 4
When a large load is input to 3, the plunger 43 retreats into the case 2. In this retreat, the clutch 4 retreats while being engaged with the guide shaft 42. At this time, the guide surface 4 d of the clutch 4 is connected to the guide surface 43 of the plunger 43.
Since the contact is made with d, the retreat of the plunger 43 can be restricted.

When a larger load is input, the guide shaft 42 with which the clutch 4 is engaged
Moves backward while pressing the damper spring 9. Therefore, the spring force of the damper spring 9 and the spring force of the push-out spring 6 oppose the input load. At this time, the oil from the engine body 31 filled in the oil reservoir 17 of the guide shaft 42, the shaft hole 43a of the plunger 43, and the housing hole 2a of the case 2 applies an input load due to its viscous resistance, fluid resistance and the like. Decay. Therefore, also in such a structure, in addition to the spring force of the push-out spring 6 and the damper spring 9, the oil damping action counters the input load, so that the tension of the timing chain 34 can be favorably held.

Therefore, such an embodiment has the same functions and effects as those of the first embodiment. In addition, since the plunger 43 is guided while being in contact with the storage hole 2a of the case 2, linear movement can be secured, and a strong eccentric load in a direction inclined with respect to the axial direction is input. Can well cope with the unbalanced load. A receiving surface (guide surface) 4 for receiving the retreat of the plunger 43.
Since d is provided in the clutch 4, the retreat of the plunger 43 due to the input load can be controlled.

Fourth Embodiment FIG. 10 shows a tensioner 51 according to a fourth embodiment. In this embodiment, an annular pressing ring 52 is disposed between the plunger 43 and the clutch 4 that constitute the shaft member 3. Guide surfaces 4d and 52d for moving the clutch 4 in a direction in which the clutch 4 is engaged with and disengaged from the male screw portion 7 of the guide shaft 42 are formed on a surface of the pressing ring 52 facing the clutch 4. These guide surfaces 4d and 52d are inclined surfaces whose diameter gradually increases outward, and are thereby formed in a tapered shape whose diameter gradually increases in the retreating direction of the plunger 43.

The pressing ring 52 reciprocates in the axial direction within a certain range along the inner surface of the plunger 4. In this case, a stopper 54 is attached to a predetermined position on the inner surface of the plunger 43, and regulates the stroke of the pressing ring 52 so that the pressing ring 52 does not press the clutch 4 more than necessary.

A ring pressing spring 53 is disposed between the pressing ring 52 and the plunger 43, and urges the pressing ring 52 to move in the direction of contact with the clutch 4. Also in this embodiment, the guide surface 4d of the clutch 4 is a receiving surface for receiving the retreat of the pressing ring 52 that moves rearward based on the retreat of the plunger 43, and thereby the retreat of the plunger 43 due to the input load. Is controlled.

Since the tensioner 51 of this embodiment basically performs the same operation as the tensioner 41 of the third embodiment shown in FIGS. 7 to 9, only the differences from the tensioner 41 of the third embodiment will be described. I do.

In the tensioner 51 of this embodiment,
The plunger 43 advances from the case 2 by the spring force of the push-out spring 6. At the time of this advance, the clutch 4 attempts to move in the spreading direction out of engagement with the guide shaft 42, but the pressing ring 52 urged by the ring pressing spring 53 pushes the clutch 4 to restrict the movement in the spreading direction. . For this reason, the clutch 4 moves together with the plunger 43 within a certain stroke range while being engaged with the guide shaft 42. When the plunger 43 has advanced beyond a certain value, the clutch 4 is expanded and disengaged from the engagement with the guide shaft 42. Then, the plunger 43 contacts the timing chain 34 to apply tension to the timing chain 34.

In the contact state with the timing chain 34, a load is input to the plunger 43 according to the rotation state of the engine. The plunger 43 is pressed by the input load, and the pressing ring 52 presses the clutch 4 via the ring pressing spring 53. As a result, the clutch 4 meshes with the guide shaft 42, so that the movement of the plunger 43 in the retreating direction is restricted via the pressing ring 52 and the ring pressing spring 53. Therefore, it is possible to prevent the timing chain 34 from being loosened more than necessary.

On the other hand, when the input load from the timing chain 34 is small, the plunger 43 tries to advance by the urging force of the pushing spring 6, but the ring pressing spring 53
Because the clutch 4 is in a state of being engaged with the guide shaft 42 by the spring force, the timing chain 34 is not pressed more than necessary.

In such an embodiment, the spring force of the push-out spring 6, the engagement force of the clutch 4 with the guide shaft 42, and the storage hole 2a of the case 2 including the oil reservoir 17 and the shaft hole 43a. The load applied to the plunger 43 is opposed by the viscous resistance and the fluid resistance of the oil supplied to the gap, so that the followability to the input load is improved, and good tension can be maintained.

Further, since the stopper 54 restricts the movement of the pressing ring 52 more than necessary, the clutch 4 does not mesh with the guide shaft 42 more than necessary, and the clutch 4 and the guide shaft 42 are damaged by excessive stress. Disappears.

(Fifth Embodiment) FIGS. 11 to 13 show a tensioner 61 according to a fifth embodiment. As shown in FIG. 14, the tensioner 61 of this embodiment
1 and is supplied with the oil in the engine body 31. For this reason, an oil introduction hole 62 communicating with the oil supply hole 18 is formed on the outer surface of the case 2, and the oil in the engine main body 31 flows through the oil introduction hole 62 and the oil supply hole 18 to the oil reservoir 17. It is supplied into the space of the storage hole 2 a of the case 2. Other configurations are the same as those of the first embodiment shown in FIG.

FIG. 11 shows a state in which the clutch 4 is engaged with the shaft member 3. In this state, the shaft member 3 advances out of the case 2. When the shaft member 3 advances, the clutch 4 moves together with the shaft member 3 while engaging with the shaft member 3 during the stroke range L in FIG. Further movement of the shaft member 3 causes the contact surface 4b of the clutch 4 to contact the guide surface 13a of the bearing 13, so that the clutch 4 moves in the direction in which the diameter increases as shown in FIG. Thus, the clutch 4 is disengaged from the shaft member 3. The shaft guide 11 falls into the second guide surface 11b and maintains the meshing and disengaging state.

(Embodiment 6) FIGS. 15 to 17 show another embodiment of the clutch 4. FIG. The clutch 4 has a shape obtained by dividing a nut, and has a female thread 12
The nut may be divided into three parts, and each divided part may be used as the clutch 4 as shown in FIG. Further, the female screw portion 12 and the shaft member 3 of the clutch 4
The lead angle of the external thread portion 7 (including the guide shaft 42) can be set to a high angle.
Can correspond to a small input load.

As shown in FIG. 16, a non-circular shape having a D-cut parallel to the outer surface and a non-circular shape are arranged in the clutch guide 11 also having a D-cut parallel to the inner surface so that the clutch guide 11 can move in a rotationally restricted state. It may be. FIG. 17 shows a mode in which an operation section 65 is provided on the clutch 4.
5 extends outside the case 2. With this configuration, the clutch 4 can be moved in the axial direction of the shaft member 3 by gripping the operation unit 65. Thereby, the shaft member 3 can be returned from the outside.

In the above embodiment, the shaft member 32
The male thread 7 is formed, and the female thread is formed on the clutch 4 to engage and disengage them. The structure for engaging and disengaging is formed by other members, for example, grooves and projections engaging with the grooves. There may be.

[0082]

According to the first aspect of the present invention, the hydraulic means acts on the shaft member in the advancing direction, and attenuates the input load to the shaft member based on the viscosity resistance and fluid resistance of the oil. Since it acts, the ability to follow an input load is good, and a good tension can be applied from a low load to a high load.

According to the second aspect of the present invention, in addition to having the same effect as the first aspect of the present invention, the clutch can be moved forward and backward within a predetermined stroke range together with the shaft member in a state where the clutch is engaged with the shaft member. Therefore, it is possible to flexibly respond to the magnitude of the input load.

According to the invention of claim 3, claim 1 or 2
In addition to having the same effects as those of the invention described above, even if an unbalanced load in a direction inclined with respect to the axial direction is more strongly input, the unbalanced load can be well coped with.

According to the fourth aspect of the invention, in addition to having the same effects as any of the first to third aspects of the present invention, the shaft member can smoothly move forward and backward, and the guide means is provided. Therefore, the movement of the clutch becomes smooth, and the clutch can be smoothly engaged and disengaged from the shaft member.

According to the fifth aspect of the present invention, in addition to having the same effect as any one of the first to fourth aspects of the present invention, the clutch can be easily formed and the arrangement in the case is simple. Can be done.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view of a clutch part in FIG.

FIG. 3 is a sectional view showing the inside of the engine body.

FIG. 4 is a sectional view showing a modification of the first embodiment.

FIG. 5 is a sectional view showing another modification of the first embodiment.

FIG. 6 is a sectional view showing a tensioner according to a second embodiment.

FIG. 7 is a sectional view showing a tensioner according to a third embodiment.

FIG. 8 is a sectional view showing the operation of the tensioner according to the third embodiment.

FIG. 9 is a cross-sectional view showing the operation of the tensioner according to the third embodiment.

FIG. 10 is a sectional view showing a tensioner according to a fourth embodiment.

FIG. 11 is a sectional view showing a tensioner according to a fifth embodiment.

FIG. 12 is a sectional view showing the operation of the tensioner according to the fifth embodiment.

FIG. 13 is a sectional view showing the operation of the tensioner according to the fifth embodiment.

FIG. 14 is a sectional view showing another arrangement of the tensioner on the engine body.

FIG. 15 is a sectional view showing another embodiment of the clutch.

FIG. 16 is a sectional view showing still another embodiment of the clutch.

FIG. 17 is a cross-sectional view showing a form of a clutch that enables external operation.

[Explanation of symbols]

 1, 41, 51, 61 Tensioner 2 Case 3 Shaft member 4 Clutch 6 Extrusion spring 7 Male thread 8 Shaft guide 9 Damper spring 11 Clutch guide 12 Female thread 13 Bearing 17 Oil reservoir 18 Oil supply hole 42 Guide shaft 43 Plunger

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Takao Kobayashi 3131 Miyatamura, Kamiina-gun, Nagano Japan F-term (reference) 3J049 AA01 AA08 AB03 BB02 BB13 BB23 BB35 BC08 BD05 CA01

Claims (5)

[Claims] 1. A shaft member inserted into a case so as to be able to advance and retreat in an axial direction, an extruding spring for applying a propulsive force to the shaft member, A clutch that locks movement and disengages from engagement with the shaft member when the shaft member advances, and hydraulic means that applies a hydraulic pressure in the advance direction of the shaft member to attenuate a load input to the shaft member. Tensioner characterized by being. 2. The tensioner according to claim 1, wherein the clutch is capable of moving forward and backward within a predetermined stroke range together with the shaft member while being engaged with the shaft member. 3. The shaft member includes a guide shaft inserted into a case, and a plunger to which a propulsive force is applied by the push-out spring to move forward and backward along the case, and the clutch is engaged with the guide shaft. The tensioner according to claim 1, further comprising a receiving surface that separates and receives the plunger withdrawal. 4. The clutch moves in a direction intersecting the axial direction of the shaft member to engage and disengage with the shaft member, and the clutch moves in a direction intersecting the axial direction of the shaft member. The tensioner according to any one of claims 1 to 3, wherein a guide means for guiding the movement of the tensioner is provided in the case. 5. The clutch according to claim 1, wherein the clutch has a shape in which a nut is divided into a plurality of parts, and the shaft member is formed with a threaded portion that meshes with the clutch.
The tensioner according to any one of claims 1 to 4.