JP2003240071A - Hydraulic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tensioner capable of reducing the number of parts. sufficiently securing backlash, and surely preventing retraction of a plunger. <P>SOLUTION: This tensioner has an interior space 3a slidably inserted in a hole 2a of a housing 2 and forming a fluid chamber 20 between it and the hole 2a; a hollow plunger 3 with rack teeth 3b formed at one part of its outer periphery; a spring 4 enerdizing the plunger 3 in a protruding direction; a ratchet part 72a to be engaged with the rack teeth 3b of the plunger 3; a wedge-like slider 72, which is slidably installed in a direction crossing with an axial line L of the plunger 3 along an inclined face 72b on the opposite side, allows movement of the plunger 3 in the protruding direction, and performs a wedge effect at the retraction of the plunger 3 so as to prevent retraction of the plunger 3; and a spring 73 enerdizing the slider 72 in a direction that the ratchet part 72a is engaged with the rack teeth 3b. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic tensioner for exerting an appropriate tension on a chain or a belt, and more particularly to a ratchet mechanism for preventing the plunger from retracting when the hydraulic pressure decreases. Regarding what you have.

[0002]

2. Description of the Related Art A hydraulic tensioner generally includes a housing, a hollow plunger slidably inserted into a hole formed in the housing and biased in a protruding direction by a spring, and the housing hole and the plunger. And a fluid chamber defined by During operation of the tensioner, the pressing force that acts on the tip of the plunger from the chain or belt balances the elastic force of the spring and the drag force of the hydraulic pressure in the chamber.

By the way, in a hydraulic tensioner applied to a timing system for an automobile, under a situation where sufficient hydraulic pressure is not acting in the chamber, such as when the engine is started, the chain tip to the tip of the plunger. When the pressing force is applied, the plunger may be easily pushed into the housing and the plunger may be retracted, resulting in noise or vibration.

Therefore, in order to prevent such a contraction of the plunger, various hydraulic tensioners having a ratchet mechanism are disclosed, for example, in Japanese Patent Laid-Open Nos. 2000-136859 and 2001-304360. Is proposed.

Japanese Patent Application Laid-Open No. 2000-136859 discloses a rack movably supported in a vertical hole formed in a housing and a rack movably supported in a horizontal cavity formed in the housing. It is composed of a ratchet that engages with the rack and a spring that is housed in the cavity and biases the ratchet in the direction of engaging with the rack.

[0006]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-136859

However, in this case, the rack is provided separately from the plunger, and the number of parts is large.
Further, in the case of a chain having a relatively long center-to-center distance, there is a demand to increase the backlash of the ratchet mechanism to some extent. However, in the above publication, the backlash of the ratchet mechanism is reduced to the backlash between the rack and the ratchet. It has the drawback of not being able to do better than rush.

In Japanese Patent Laid-Open No. 2001-304360, a rack groove formed on the outer circumference of a piston and a lateral hole extending in a direction intersecting the axis of the piston inside a housing are slid through an inner wall surface and a predetermined play. It is composed of a claw member that is freely accommodated and that engages with the rack groove, and a spring that is accommodated in the lateral hole and that biases the claw member in a direction that engages with the rack groove.

[0009]

[Patent Document 2] Japanese Patent Laid-Open No. 2001-304360

In this case, by providing a predetermined play between the claw member and the inner wall surface of the lateral hole, the backlash of the ratchet mechanism can be made equal to or greater than the backlash between the groove and the claw member. It is possible for the time being. However, in this case, if the play is made too large, the pawl member may cause chattering inside the lateral hole, so the amount of play cannot be increased so much that the backlash of the ratchet mechanism is made sufficiently large. Is difficult to do.

The present invention has been made to solve such conventional problems, and the object thereof is to reduce the number of parts, to secure a sufficient backlash, and to reliably prevent the plunger from being retracted. It is to provide a hydraulic tensioner with a ratchet mechanism.

[0012]

According to another aspect of the present invention, there is provided a hydraulic tensioner which has a housing having a hole formed at one end thereof and a fluid chamber which is slidably inserted into the hole of the housing. And a hollow plunger having rack teeth formed on at least a part of its outer periphery, a first urging member for urging the plunger in the protruding direction, and a movement of the plunger in the protruding direction. And a wedge-shaped slider that exerts a wedge effect when the plunger retracts to prevent the plunger from contracting, and a second biasing member that biases the slider in a direction in which the ratchet portion engages with the rack teeth. There is. The slider has a ratchet portion capable of engaging with a rack tooth of the plunger on a first side surface, and intersects the axial direction of the plunger along an inclined surface formed on a second side surface opposite to the first side surface. It is provided so that it can slide in any direction.

According to the first aspect of the present invention, the rack teeth are formed on the outer circumference of the plunger, and it is not necessary to provide the rack member separately from the plunger, so that the number of parts can be reduced.

Further, in this case, when the plunger moves in the protruding direction during the operation of the tensioner, the slider follows the inclined surface of the slider through the engagement state of the rack tooth of the plunger and the ratchet portion of the slider. Since it slides in the direction, the total backlash amount can be increased corresponding to this slide movement amount. This makes it possible to secure sufficient backlash.

In the conventional tensioner disclosed in, for example, Japanese Unexamined Patent Publication No. 2000-136859, when the plunger projects, the ratchet moves in the direction orthogonal to the rack moving direction, so that the ratchet moving amount increases backlash. Does not contribute to. In addition, Japanese Patent Laid-Open No. 2001-2001
According to Japanese Patent Laid-Open No. 304360, when the piston is projected, the claw member moves in a direction diagonally intersecting with the moving direction of the rack groove, but in this case, the movement amount of the claw member does not contribute much to the increase of backlash. At this time, the amount of play between the claw member and the inner wall surface of the lateral hole contributes to an increase in backlash, but as described above, this play cannot be increased so much that the total amount of backlash is sufficient. It is difficult to increase.

On the other hand, according to the first aspect of the invention, the slider is arranged on the side opposite to the first side surface having the ratchet portion and along the inclined surface of the second side surface facing the first side surface. It is designed to move, which makes it possible to sufficiently increase the total backlash amount.

In addition, in this case, when the plunger is retracted, the wedge-shaped slider exerts a wedge effect, whereby the plunger can be reliably prevented from retracting.

According to another aspect of the present invention, the housing is provided with a support block having a slider accommodating portion for accommodating the slider, and the slider accommodating portion has an inclined surface shape in which the inclined surface of the slider slidably abuts. The slide surface is formed, and the second biasing member biases the slider so that the slider moves along the slide surface. In this case, when the slider moves, the slider is guided by the inclined slide surface formed in the slider accommodating portion of the support block under the action of the urging force of the second urging member. Will be able to move smoothly.

According to the third aspect of the invention, the second biasing member is a coil spring, and its axis is arranged parallel to the slide surface of the slider accommodating portion. As a result, the biasing force of the coil spring can be transmitted to the slider without loss while maintaining the contact state between the inclined surface of the slider and the sliding surface of the support block.

In the fourth aspect of the invention, the slider accommodating portion is formed with a stopper surface which can prevent the slider from moving by contacting the rear end surface of the slider when the plunger is retracted. This makes it possible to reliably prevent the movement of the slider and the movement of the plunger when the plunger is retracted.

According to the invention of claim 5, a wall surface facing the front end surface of the slider is formed in the slider accommodating portion, one end of the second urging member is locked to the wall surface, and the other end is the slider. Is locked to the front end face of the. As a result, the slider and the second biasing member are integrally housed inside the support block, which facilitates the assembly of the tensioner.

According to the sixth aspect of the invention, the rear end of the rack tooth of the plunger abuts the rear end of the ratchet portion of the slider when the plunger is fully extended, and the ratchet portion is sandwiched between the ratchet portion and the wall surface. A stopper surface for preventing the plunger from coming off is formed. This makes it possible to prevent the plunger from coming off with a simple configuration.

According to the seventh aspect of the invention, in order to release the engagement between the ratchet portion of the slider and the rack tooth of the plunger, a lock releasing pin is provided between the rear end surface of the slider and the stopper surface of the slider accommodating portion. A first through hole for insertion is formed in the housing, and further, a retaining pin is inserted between the front end surface of the slider and the wall surface of the slider accommodating portion in order to hold the plunger in a retracted state. Second through hole is formed in the housing.

In this case, the engagement state between the slider and the rack tooth of the plunger can be easily released by inserting the lock release pin into the first through hole. By releasing the engagement state, for example, at the time of shipping the tensioner, an operator can easily push the plunger into the inside of the housing. Then, from this state, the retracting state of the plunger can be easily maintained by inserting the retaining pin into the second through hole. As a result, the tensioner can be easily attached to the chain. In addition, after assembling to the chain, by removing this retaining pin,
The tensioner is operational.

The lock release pin and the retaining pin are preferably constituted by a common pin having a tapered tip as in the invention of claim 8. In this case, since the tip of the pin is formed in a tapered shape, the gap between the rear end surface of the slider and the stopper surface of the slider accommodating portion, and the gap between the front end surface of the slider and the wall surface of the slider accommodating portion are The pin can be easily inserted into the gap. In addition, the number of parts can be further reduced by sharing each pin with one type of pin.

According to the invention of claim 9, a recess is formed in the housing adjacent to the hole of the housing and extending in a direction intersecting with the hole, and the tilted surface of the slider is slidably abutted in the recess. A planar slide surface is formed, and the second biasing member biases the slider so that the slider moves along the slide surface.
In this case, when the slider is moved, the slider is guided by the slanted slide surface formed in the recess of the housing under the action of the biasing force of the second biasing member. You will be able to move smoothly. Further, in this case, since it is not necessary to separately provide a support block as in the invention of claim 2 to support the slider, the structure can be simplified.

According to the tenth aspect of the invention, the second biasing member is a coil spring, and its axis is arranged parallel to the slide surface. As a result, the biasing force of the coil spring can be transmitted to the slider without loss while maintaining the contact state between the inclined surface of the slider and the sliding surface of the recess.

In the eleventh aspect of the present invention, a stopper surface is formed behind the slide surface in the recess so that the rear end surface of the slider abuts when the plunger is retracted to prevent the slider from moving. This makes it possible to reliably prevent the movement of the slider and the movement of the plunger when the plunger is retracted.

In the twelfth aspect of the invention, a plug member facing the front end face of the slider is provided in front of the slide surface in the recess, and one end of the second biasing member is locked to the plug member. The other end is locked to the front end surface of the slider.

In the thirteenth aspect of the present invention, the rear end of the rack tooth of the plunger is brought into contact with the rear end of the ratchet portion of the slider when the plunger is fully extended, and the ratchet portion is held between the ratchet portion and the plug member. A stopper surface for preventing the plunger from coming off is formed.
This makes it possible to prevent the plunger from coming off with a simple configuration.

In the fourteenth aspect of the present invention, the concave portion has a pair of flat surfaces facing each other on both sides of the sliding surface,
Both side surfaces of the slider are slidably supported by the flat surfaces of the recess. In this case, when the slider is slid, the flat surface guides the slider from both sides, so that the slider can be prevented from swinging. As a result, the engagement between the ratchet portion of the slider and the rack tooth of the plunger can be reliably maintained.

According to the fifteenth aspect of the present invention, a check valve for allowing the fluid flow into the chamber and preventing the fluid flow in the opposite direction is provided at the bottom of the hole of the housing. In this case, the check valve is closed when the plunger is retracted, so that the hydraulic pressure in the chamber acts as a drag force on the plunger, which reliably prevents the plunger from retracting.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a vertical cross-sectional view of a hydraulic tensioner according to an embodiment of the present invention, FIG. 2 is an enlarged view of a ratchet mechanism portion in the hydraulic tensioner of FIG. 1, and FIG. 3 illustrates a positional relationship between a ratchet mechanism and an unlock pin. FIG. 4 is a diagram for explaining the positional relationship between the ratchet mechanism and the retaining pin, FIGS. 5 to 9 are diagrams for explaining the operation of the ratchet mechanism when the plunger is extended, and FIG. 10 is a diagram for when the plunger is retracted. FIG. 6 is a view for explaining the operation of the ratchet mechanism of FIG.

As shown in FIG. 1, the hydraulic tensioner 1 is
A housing 2, a hollow plunger 3 slidably inserted into a hole 2a formed in the housing 2, a spring (first urging member) 4 for urging the plunger 3 in a direction projecting from the hole 2a, It is mainly composed of

In the housing 2, a fluid chamber 20 is formed from the inner space 3a formed in the plunger 3 and the inner wall surface of the hole 2a. A check valve 5 is provided at the bottom of the hole 2a in the housing 2. The check valve 5 allows the fluid to flow into the chamber 20 while blocking the fluid from flowing in the opposite direction to the ball 50.
The ball seat 51 with which the ball 50 contacts, and the ball 50
And a spring 52 that urges the ball 52 toward the ball seat 51. In addition, as the check valve 5,
Other configurations may be adopted. The housing 2 is also provided with a flow path 6 for connecting the chamber 20 to an external source of pressurized fluid (not shown).

Rack teeth 3b are formed on a part of the outer peripheral surface of the plunger 3. A ratchet mechanism 7 for preventing the plunger 3 from contracting is provided at the hole opening of the housing 2.

The ratchet mechanism 7, as shown in FIG.
The support block 70 is arranged in the notch 2b formed in the hole opening of the housing 2, and is housed in the concave slider accommodating portion 71 formed in the support block 70, and engages with the rack teeth 3b on the outer periphery of the plunger. Possible ratchet part 72
A wedge-shaped slider 72 having a on the first side surface, and a spring (second urging member) 73 for urging the slider 72 in a direction in which the ratchet portion 72a of the slider 72 engages with the rack teeth 3b. Has been done.

A through hole 70a is formed in the support block 70, and the support block 70 is fixed in the notch 2b of the housing 2 via a mounting bolt (not shown) inserted through the through hole 70a. There is.

The slider 72 has an inclined surface 72b on the second side surface arranged on the opposite side of the first side surface having the ratchet portion 72a. The slider housing portion 71 has an inclined slide surface 71a on which the inclined surface 72b of the slider 72 slidably abuts. Sliding surface 71a
Extends in a direction intersecting with the axis L of the plunger 3, and the distance between the slide surface 71a and the axis L of the plunger 3 gradually decreases as the plunger 3 moves backward (that is, leftward in FIG. 2). There is. Sliding surface 71
The angle formed by a with the axis L of the plunger 3 is preferably 45 degrees or smaller, and in this embodiment, is set to about 30 degrees. This is to ensure sufficient backlash in the ratchet mechanism 7.

The slider 72 has a rear end surface 72c and a front end surface 72d which are arranged to face each other between the first and second side surfaces. On the other hand, the slider accommodating portion 71 includes the slider 7
2 is arranged so as to face the rear end surface 72c of the slider 7, and the rear end surface 72c of the slider 72 comes into contact with the slider 7 when the plunger 3 retracts.
It has a stopper surface 71b that can prevent the movement of the second.
Further, the slider accommodating portion 71 includes the front end surface 7 of the slider 72.
It has a wall surface 71c arranged opposite to 2d.

One end of the spring 73 is locked in the engaging recess 72e formed on the front end surface 72d of the slider 72, and the other end is engaged recess 71d formed on the wall surface 71c.
Is locked to.

A coil spring is used as the spring 73 in the present embodiment, but it is preferable that the axis m thereof is arranged parallel to the slide surface 71a of the slider accommodating portion 71. This is the inclined surface 72b of the slider 72.
This is for transmitting the spring force of the spring 73 to the slider 72 without loss while maintaining the contact state between the slide surface 71a and the slide surface 71a.

With such a configuration, the ratchet mechanism 7
Allows the plunger 3 to move in the protruding direction (rightward in FIG. 2), and when the plunger 3 is retracted, it exerts a wedge effect between the slider accommodating portion 71 and the outer peripheral surface of the plunger 3 to allow the plunger 3 to move. It is designed to prevent degeneration. Further, since the slider 72 and the spring 73 are integrally housed inside the support block 70, the tensioner can be easily assembled.

The housing 2 is provided with first and second through holes 25, 26 which penetrate the outer peripheral surface of the housing 2 in a direction orthogonal to the axial direction (direction perpendicular to the plane of FIG. 2). The first through hole 25 is provided in the slider accommodating portion 7
The second through hole 26 is disposed on the rear end side of the slider housing portion 71.

The first through hole 25, as shown in FIG.
This is a hole into which a lock release pin P1 for releasing the engagement locked state between the ratchet portion 72a of the slider 72 and the rack tooth 3b of the plunger 3 is inserted. The second through hole 26 is a hole into which a retaining pin P2 for holding the plunger 3 in a retracted state is inserted, as shown in FIG. Lock release pin P1 and retaining pin P
In each of No. 2, the tip is formed in a tapered shape. It should be noted that these pins may share one pin, thereby reducing the number of parts.

Next, the operation of the ratchet mechanism 7 during the operation of the tensioner will be described with reference to FIG.
Will be explained. When the engine starts, oil is supplied to the tensioner 1 from the flow path 6 through the check valve 5 into the chamber 20. When the chamber 20 is filled with oil, the hydraulic pressure of the oil causes the plunger 3 to move in the protruding direction.

As shown in FIG. 5, when the rack teeth 3b of the plunger 3 are engaged with the ratchet portion 72a of the slider 72 and the plunger 3 starts to move forward, that is, in the protruding direction (the direction of the arrow in the figure), the rack teeth The slider 72 starts to move in the arrow direction against the spring force of the spring 73 while being guided by the slide surface 71a of the support block 70 through the engagement state between the 3b and the ratchet portion 72a. In FIG. 5 and FIGS. 6 to 10 below, a black circle on a part of the rack tooth 3b of the plunger 3 is added for convenience in order to visually grasp the movement of the plunger 3.

With the movement of the slider 72, the ratchet portion 72a of the slider 72 gradually rides on the rack teeth 3b of the plunger 3, as shown in FIG. When the slider 72 continues to move due to the movement of the plunger 3, as shown in FIG. 7, the ratchet portion 72 a of the slider 72 is in a state of completely riding on the rack teeth 3 b of the plunger 3. At this time, the gap B _m between the rear end surface 72 c of the slider 72 and the stopper surface 71 b of the support block 70 is the maximum backlash of the ratchet mechanism 7. During operation of the tensioner, the slider 72 moves within the range of this maximum backlash B _m .

When the plunger 3 further moves in the projecting direction from the state shown in FIG. 7, the rack teeth 3b of the plunger 3 move the ratchet portion 72 of the slider 72 as shown in FIG.
Go over the teeth of a for one mountain. Then, the slider 72
Due to the elastic repulsive force of the spring 73, the support block 70
The movement starts in the direction opposite to the movement direction along the slide surface 71a. Then, as shown in FIG. 9, when the teeth of the ratchet portion 72a of the slider 72 engage with the rack teeth 3b of the plunger 3, the movement of the slider 72 in the reverse direction stops.

When the plunger 3 further moves in the protruding direction, the operations shown in FIGS. 6 to 9 are repeated thereafter. When the plunger 3 is maximally extended, the stopper stopper surface 3d (FIG. 1) formed on the rearmost end of the rack tooth 3b of the plunger 3 comes into contact with the rear end of the ratchet portion 72a of the slider 72 so that the slider 72 moves. It is sandwiched between the wall surface 71c of the slider housing portion 71. As a result, further movement of the plunger 3 in the protruding direction is restricted, and the plunger 3 is prevented from coming off.

Next, when the tension of the chain increases and the pressing force acts on the plunger tip 3c from the chain, the ball check valve 6 is closed, and the hydraulic pressure in the chamber 20 acts as a drag force on the plunger. Since it acts on 3, the retracting of the plunger 3 is prevented.

Further, when the plunger 3 is retracted, as shown in FIG.
As shown in FIG. 5, the slider 72 moves in the plunger retreating direction together with the plunger 3 along the slide surface 71 a of the support block 70 through the engaged state of the rack tooth 3 b of the plunger 3 and the ratchet portion 72 a of the slider 72. To do. As a result, the wedge-shaped slider 72 exerts a wedge effect between the slide surface 71a of the slider accommodating portion 71 of the support block 70 and the plunger 3, so that the plunger 3 is reliably prevented from retracting.

As described above, when the tensioner is operated, the slider 72 moves along the slanted slide surface 71a of the support block 70 along with the movement of the plunger 3, so that the ratchet portion 72a and the rack tooth 3b are moved.
Maximum backlash B that is larger than the backlash with
_The slider 72 moves within the range of _m . Thereby, the amount of backlash of the entire ratchet mechanism can be increased, and sufficient backlash can be secured.

Next, when a pressing force acts on the plunger tip portion 3c from the chain under a situation where sufficient hydraulic pressure is not acting in the chamber 20, such as when starting the engine, the same applies. The wedge-shaped slider 72 is a slide surface 71 of the slider accommodating portion 71 of the support block 70.
Since a wedge effect is exerted between a and the plunger 3 and the rear end surface 72c of the slider 72 contacts the stopper surface 71b of the support block 70 (see FIG. 10), the movement of the slider 72 is blocked, The degeneration of the plunger 3 can be reliably prevented.

Next, when releasing the engagement locked state between the plunger 3 and the slider 72 to bring the plunger 3 into the retracted state such as when the tensioner is shipped or when the tensioner is installed, it is shown in FIG. As described above, the lock release pin P1 is inserted into the first through hole 25 formed in the housing 2. As a result, the rear end surface 72c of the slider 72 and the stopper surface 71b of the slider housing portion 71 are separated from each other, and the engagement between the ratchet portion 72a of the slider 72 and the rack tooth 3b of the plunger 3 is released. From this state, the worker can easily bring the plunger 3 into the retracted state by pushing the plunger 3 into the housing.

At the time of shipping the tensioner, as shown in FIG. 4, with the tip 3c of the plunger 3 held down so that the plunger 3 does not project, as shown in FIG.
Is removed from the first through hole 25, and the retaining pin P2 is inserted into the second through hole 26 formed in the housing. The retaining pin P2 prevents the slider 72 from moving in the direction of the arrow in FIG. 4, so that the movement of the plunger 3 in the protruding direction is restricted and the retracted state of the plunger 3 is maintained.

After assembling the tensioner to the chain,
By pulling out the retaining pin P2 from the second through hole 26, the spring force of the spring 4 causes the plunger 3 to move in the protruding direction together with the slider 72, so that the tensioner can be operated.

As described above, according to this embodiment, since the rack teeth 3b are formed on the outer periphery of the plunger 3, it is not necessary to provide a rack member separately from the plunger 3.
The number of parts can be reduced. Further, since the slider 72 moves along the slanted slide surface 71a of the slider accommodating portion 71a, sufficient backlash can be ensured for the entire ratchet mechanism. Furthermore, when the plunger 3 is retracted, the wedge-shaped slider 72 exerts a wedge effect between the slide surface 71a and the plunger 3, so that the plunger 3 can be reliably prevented from retracting.

[ Other Embodiments ] In the above embodiment, the ratchet mechanism is provided in the slider accommodating portion of the support block provided separately from the housing. However, the application of the present invention is not limited to this. Not the ratchet mechanism,
It may be provided directly on the housing. 11 to 13 are views for explaining a hydraulic tensioner having such a ratchet mechanism according to another embodiment of the present invention, and FIG. 11 is an enlarged view of a ratchet mechanism portion of the hydraulic tensioner. , FIG. 12 is a sectional view taken along line XII-XII in FIG.
FIG. 13 is a view for explaining the operation of the ratchet mechanism at the time of maximum extension of the plunger. In these figures, the same reference numerals as those used in the above embodiment indicate the same or corresponding portions.

As shown in FIG. 11, the hole 2 of the housing 2
In the opening of a, concave portions 8 and 9 are formed adjacent to the hole 2a and extending in a direction intersecting the hole 2a. The recess 8 is the hole 2
It is formed on the opening end side of a and the recess 9 is formed on the back side thereof.

As shown in FIG. 12, the cross-sectional shape of the recess 8 is composed of a semicircular portion and flat portions 8a and 8b which are continuous with the flat portion and extend in parallel with each other. The cross-sectional shape of 9 is composed of a semicircular portion and flat portions 9a and 9b which are continuous with the semicircular portion and extend parallel to each other. In this example, the spacing between the flat portions 8a and 8b is the same as the spacing between the flat portions 9a and 9b, and the flat portions 8a and 9a and the flat portions 8b and 9b are flush with each other. Although the formed example is shown, the space between the flat portions 8a and 8b is equal to the flat portion 9
It may be larger than the distance between a and 9b.

A plug member 11 is press-fitted into the concave portion 8,
A slider 12 is provided in the recess 9, and a spring 13 (second biasing member) is provided between the plug member 11 and the slider 12. These plug members 1
1, the slider 12, and the spring 13 constitute a ratchet mechanism 10 for preventing the plunger 3 from contracting.

The slider 12 is a substantially wedge-shaped member having a ratchet portion 12a which can be engaged with the rack teeth 3b on the outer periphery of the plunger on the first side surface and a second side surface opposite to the first side surface. It has the inclined surface 12b formed in. The inclined surface 12b slidably contacts a semicircular portion that functions as an inclined slide surface in the recess 9. In addition, the both sides of the slider 12 are
Abutting on each flat portion 9a, 9b (see FIG. 12). As a result, the slider 12 is prevented from swinging left and right in the recess 9, and as a result, the engagement between the ratchet portion 12a of the slider 12 and the rack tooth 3b of the plunger 3 is maintained. ing.

The slider 12 has a shaft portion 12c.
Further, the plug member 11 is formed with a hole 11a. One end of the spring 13 is connected to the shaft portion 12 of the slider 12.
c, and the other end is engaged with the hole 11a of the plug member 11. Due to the elastic repulsive force of the spring 13, the slider 12 is urged toward the side where the ratchet portion 12 a engages with the rack tooth 3 b of the plunger 3. The axis m of the spring 13 is arranged parallel to the axis of the recess 9 and intersects the axis L of the plunger 3 at an acute angle.

With such a configuration, the ratchet mechanism 1
0 allows the plunger 3 to move in the protruding direction (rightward in FIG. 11), and when the plunger 3 is retracted, it exhibits a wedge effect between the recess 9 and the outer peripheral surface of the plunger 3 to retract the plunger 3. It is designed to prevent

Regarding the operation of the ratchet mechanism 10 during the operation of the tensioner, the ratchet mechanism 7 according to the above-mentioned embodiment is used.
Since it is the same as the case of 1, the description is omitted here. When the plunger 3 is maximally extended, as shown in FIG. 13, the retaining stopper surface 3d formed on the rearmost end of the rack tooth 3b of the plunger 3 contacts the rear end of the ratchet portion 12a of the slider 12. Slider 12 plug 11
By sandwiching the plunger 3 with the stopper 3, further movement of the plunger 3 in the protruding direction is restricted, and the plunger 3 is prevented from coming off.

Also in this case, since the rack teeth 3b are formed on the outer periphery of the plunger 3 as in the above embodiment, it is not necessary to provide a rack member separately from the plunger 3, and the number of parts can be reduced. Also, the slider 1
Since 2 moves along the slanted slide surface of the recessed portion 9, sufficient backlash can be secured for the ratchet mechanism as a whole. Further, when the plunger 3 is retracted, the wedge-shaped slider 12 exerts a wedge effect between the slide surface of the recess 9 and the plunger 3, so that the plunger 3
Can surely be prevented from degeneration.

[0068]

As described above in detail, according to the hydraulic tensioner of the present invention, the number of parts can be reduced, sufficient backlash can be secured, and the plunger can be surely prevented from being retracted.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a hydraulic tensioner according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a ratchet mechanism portion in the hydraulic tensioner (FIG. 1).

FIG. 3 is a diagram for explaining a positional relationship between a ratchet mechanism and a lock release pin.

FIG. 4 is a diagram for explaining a positional relationship between a ratchet mechanism and a retaining pin.

FIG. 5 is a view for explaining the operation of the ratchet mechanism when the plunger is extended.

FIG. 6 is a view for explaining the operation of the ratchet mechanism when the plunger is extended.

FIG. 7 is a view for explaining the operation of the ratchet mechanism when the plunger is extended.

FIG. 8 is a view for explaining the operation of the ratchet mechanism when the plunger is extended.

FIG. 9 is a view for explaining the operation of the ratchet mechanism when the plunger is extended.

FIG. 10 is a view for explaining the operation of the ratchet mechanism when the plunger is retracted.

FIG. 11 is an enlarged view of a ratchet mechanism portion of a hydraulic tensioner according to another embodiment of the present invention.

12 is a sectional view taken along line XII-XII in FIG.

FIG. 13 is a view for explaining the operation of the ratchet mechanism at the time of maximum extension of the plunger.

[Explanation of symbols]

1: Hydraulic tensioner 2: Housing 2a: hole 20: Fluid chamber 3: Plunger 3a: Internal space 3b: rack teeth 4: Spring (first biasing member) 5: Check valve 7: Ratchet mechanism 70: Support block 71: Slider housing 72: Slider 72a: Ratchet part 73: Spring (second biasing member) P1: Lock release pin P2: Retaining pin 25: First through hole 26: Second through hole

Claims (15)

[Claims] 1. A hydraulic tensioner for exerting a tension force on a chain, comprising: a housing having a hole formed at one end thereof; and a fluid chamber slidably inserted into the hole. A hollow plunger having an internal space that forms a rack tooth and formed on at least a part of the outer periphery, a first biasing member that biases the plunger in a protruding direction, and the rack tooth of the plunger. A ratchet portion that can be engaged is provided on a first side surface, and is provided slidably in a direction intersecting the axis of the plunger along an inclined surface formed on a second side surface opposite to the first side surface. And a wedge-shaped slider that allows the plunger to move in the protruding direction and exhibits a wedge effect when the plunger retracts to prevent the plunger from retracting. Hydraulic tensioner with a second urging member that jet portion for biasing the slider in the direction of engagement with the rack teeth, a. 2. The support block according to claim 1, wherein the housing is provided with a support block having a slider housing portion for housing the slider, and the inclined surface of the slider slides in the slider housing portion. A slanted slide surface that freely abuts is formed, and the second biasing member biases the slider so that the slider moves along the slide surface. And hydraulic tensioner. 3. The liquid according to claim 2, wherein the second biasing member is a coil spring, and its axis is arranged parallel to the slide surface of the slider accommodating portion. Pressure tensioner. 4. The stopper surface according to claim 2, wherein the slider accommodating portion is formed with a stopper surface capable of preventing the slider from moving by contacting a rear end surface of the slider when the plunger is retracted. And hydraulic tensioner. 5. The slider housing portion according to claim 4, wherein a wall surface facing the front end surface of the slider is formed, and one end of the second biasing member is locked to the wall surface, and A hydraulic tensioner, the end of which is locked to the front end surface of the slider. 6. The rear end of the rack tooth of the plunger according to claim 5, wherein the ratchet portion of the slider contacts the rear end of the ratchet portion of the slider when the plunger is fully extended. A hydraulic tensioner characterized in that a stopper surface for preventing the plunger from coming off is formed by sandwiching the plunger with the hydraulic tensioner. 7. The rear end surface of the slider and the stopper surface of the slider accommodating portion according to claim 5, for releasing an engagement locked state between the ratchet portion of the slider and the rack tooth of the plunger. A first through hole for inserting an unlocking pin between the slider and the housing, and the front end surface of the slider and the slider accommodating portion for holding the plunger in a retracted state. A hydraulic tensioner, wherein a second through hole for inserting a retaining pin between the wall surface and the wall surface is formed in the housing. 8. The hydraulic tensioner according to claim 7, wherein the lock release pin and the retaining pin are common pins having tapered ends. 9. The recess according to claim 1, wherein the housing is formed with a recess adjacent to the hole and extending in a direction intersecting with the hole, and the recess allows the inclined surface of the slider to slide. A hydraulic pressure having a slidable slide surface that abuts, and the second biasing member biases the slider so that the slider moves along the slide surface. Tensioner. 10. The hydraulic tensioner according to claim 9, wherein the second urging member is a coil spring, and the axis of the second urging member is arranged parallel to the slide surface. 11. The stopper surface according to claim 9, wherein a rear end surface of the slider is in contact with the rear surface of the slide surface in the recess when the plunger is retracted to prevent the slider from moving. A hydraulic tensioner characterized by the fact that 12. The plug member facing the front end surface of the slider is provided in front of the slide surface in the recess, and one end of the second biasing member is the plug member. A hydraulic tensioner, wherein the hydraulic tensioner is locked to a member and the other end is locked to the front end surface of the slider. 13. The rear end of the rack tooth of the plunger according to claim 12, wherein the ratchet portion of the slider contacts the rear end of the ratchet portion of the slider when the plunger is fully extended. A hydraulic tensioner characterized in that a stopper surface for retaining is formed to prevent retaining of the plunger by sandwiching it between them. 14. The recess according to claim 9, wherein the recess has a pair of flat surfaces facing each other on both sides of the slide surface, and both side surfaces of the slider are slidably supported by the flat surfaces. A hydraulic tensioner characterized by the following. 15. The check valve according to claim 1, wherein a bottom portion of the hole of the housing is provided with a check valve that allows fluid flow into the fluid chamber and blocks fluid flow in the opposite direction. A hydraulic tensioner characterized by the following.