JPH0694089A - Tensioner - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a tensioner that can effectively prevent the plunger 2 from popping out during assembly and has excellent protection of chains and the like. [Structure] A tensioner includes a plunger 2 fitted in an oil chamber 10 and a ratchet portion 3 for restricting the backward movement of the plunger 2.
And a protrusion control unit 4. The protrusion restricting portion 4 includes a piston chamber 40 formed in a direction substantially orthogonal to the axis of the oil chamber 10, a lock piston 42 fitted in the piston chamber 40, and a biasing spring 44 for biasing the lock piston 42. It consists of and. When the tensioner is assembled to the cylinder head, the biasing spring 44 causes the locking projection 42
d is locked in the locking hole 26 of the plunger 2. Oil chamber 1
When the hydraulic pressure acts on 0, the hydraulic pressure in the oil chamber 10 acts on the pressure receiving surfaces 42a and 42c of the lock piston 42, and the lock piston 42 moves in the arrow Y6 direction. Then, the locking protrusion 4
2d separates from the locking hole 26 of the plunger 2, and the lock by the lock piston 42 is released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tensioner for adjusting the tension of a winding body such as a chain. This tensioner
For example, it can be applied to a chain device that drives a cam shaft of an internal combustion engine of a vehicle.

[0002]

2. Description of the Related Art Conventionally, a tensioner has been used to adjust the tension of a wound body such as a chain or a belt.
As the tensioner, as shown in FIG. 5, a housing 101 having an oil chamber 100 in the shape of a cylinder hole, a plunger 102 fitted in the oil chamber 100, a coil spring 103 for urging the plunger 102, and an axis line of the plunger 102. The piston 104 and the piston 1 which are arranged obliquely with respect to
There is known one provided with a biasing spring 105 for biasing 04 (Japanese Patent Laid-Open No. 1-229152). In this structure, a rack 106 is formed on the outer peripheral portion of the plunger 102, and the tip end surface of the piston 104 urged by the spring 105 engages with the teeth of the rack 106 to restrict the movement of the plunger 102.

When the oil pressure in the oil chamber 100 increases, a force for moving the plunger 102 forward in the direction of the arrow X1 is generated, so that the inclined tooth surface 106a of the rack 106 causes the piston 1 to move.
04 in the direction of the arrow Y1 to move the tooth surface 10 of the rack 106.
6a and piston 104 are separated. The plunger 102 moves forward in the direction of the arrow X1 by repeating this detachment. As a result, the chain 202 wound between the sprockets 200 and 201 is pressed via the shoes 203, and the chain 2
Prevent loosening of 02.

In this structure, since the tip of the piston 104 is locked to the rack 106, the retreat of the plunger 102 in the direction of the arrow X2 is restricted even when the oil pressure in the oil chamber 100 is reduced, and the chain 202 of the chain 202 is prevented. Looseness is prevented. By the way, when assembling the tensioner to the cylinder head or the like, it is necessary to consider so that the plunger 102 does not pop out from the regular position. If the plunger 102 is mounted in a protruding state, the tension of the chain 202 becomes excessive. In this case, problems such as wear of the chain sprocket, guide breakage, and chain breakage occur, so the chain is not sufficiently protected.

In the tensioner shown in FIG. 5, the rack 106 is used.
Because the tooth surface 106a of the plunger is inclined,
When a relatively large force is applied to pull out the rack in the direction of arrow X1, the rack 10 is operated by the so-called "wedge principle".
The tooth flank 106a of 6 may retract the piston 104 in the direction of the arrow Y1, and the tooth flanks 106a to 106c may cross over the tip surface of the piston 104 one after another.
The performance of preventing the pop-out of No. 2 is not satisfactory.

Conventionally, a hook 30 is attached to a housing 300 as a plunger protrusion limiting portion as shown in FIG.
There is known a tensioner in which No. 1 is swingably provided by a shaft 302 and a pin 306 is projectingly provided on a plunger 305 (Japanese Utility Model Laid-Open No. 56-170347). In this structure, when the tensioner is assembled to the cylinder head, the claw 301a of the hook 301 and the pin 306 are locked as shown in FIG. 6, so that the plunger 305 is prevented from protruding. However, when assembled, the hook 301 may accidentally swing in the direction of the arrow Y2 and come off from the pin 306, which is not always sufficient as the pop-out prevention performance.

Further, as disclosed in Japanese Utility Model Laid-Open No. 63-154850, a ratchet part is released when the oil pressure in the oil chamber exceeds a predetermined value, as a retreat part for restricting the retreat of the plunger. A tensioner is known in which the plunger can be retracted and the excess tension of the chain is loosened. However, although this can prevent excessive tension of the chain, it does not have sufficient performance for preventing the plunger from popping out when the tensioner is assembled.

Further, conventionally, as a tensioner, as disclosed in Japanese Unexamined Patent Publication No. 56-57552, a method of advancing the plunger by the spring force of a spring has been adopted, and the tip of the stopper pin is in the axial direction of the plunger. It is known that the spring force is locked by inserting the spring into the slit groove of the mainspring and locking the spring to prevent the plunger from protruding. In this case, the stopper pin is likely to come off, which is not sufficient for preventing the plunger from popping out when the tensioner is assembled.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and an object thereof is to effectively prevent the plunger from jumping out at the time of assembly and to protect a winding body such as a chain. It is to provide a tensioner with excellent properties.

[0010]

The tensioner of the present invention comprises:
A housing having an oil chamber in the shape of a cylinder hole with an open end, and an oil chamber that can move forward along the axis of the oil chamber in a direction in which the degree of protrusion from the opening increases, and can retract in a direction in which the degree of protrusion from the opening decreases. Has a concave or convex locked portion formed on the outer peripheral portion thereof, and moves forward with the pressure of the oil pressure of the oil chamber to press the endless winding body to move the winding body. It consists of a plunger that adjusts the tension, a retreat restricting part that restricts the retreat of the plunger, and a pop-out restricting part that restricts the protrusion of the plunger from the opening. A piston chamber that is formed on the outer peripheral side of the oil chamber and communicates with the oil chamber in a substantially orthogonal direction, and a locking projection that is movably fitted in the piston chamber and that locks with the locked portion of the plunger. It has a pressure receiving surface that receives the hydraulic pressure of the chamber, and the locking projection is plunged as the pressure is received. Of the lock piston that is disengaged from the locked portion of the piston, and the biasing spring that biases the lock piston in a direction substantially orthogonal to the axis of the oil chamber and locks the locking projection of the lock piston with the locked portion of the plunger. It is characterized by being composed of and.

[0011]

When the oil pressure in the oil chamber is low or absent, the locking projection of the lock piston urged by the urging spring moves in a direction substantially orthogonal to the axis of the oil chamber to lock the locked portion of the plunger. The lock function is obtained by the lock piston. As a result, the protrusion of the plunger from the opening is restricted.

When the tensioner is assembled to the mounting portion such as the cylinder head, the oil pressure is not applied to the oil chamber, so that the lock piston exerts the lock function and the protrusion of the plunger is restricted. On the other hand, when the oil pressure in the oil chamber increases, the oil pressure in the oil chamber also acts on the pressure receiving surface of the lock piston, so the lock piston moves in the piston chamber so as to move away from the plunger, and the locking protrusion of the lock piston moves to the plunger. Release from the locked part. As a result, the lock function of the lock piston is automatically released.

When the lock is released, the hydraulic pressure in the oil chamber advances the plunger to adjust the tension of the winding body.

[0014]

EXAMPLE An example of a tensioner of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. (Structure) FIG. 1 shows a cross section of the main part of the tensioner. Figure 1
As shown in FIG. 3, the housing 1 is formed with a cylinder-hole-shaped oil chamber 10 having an open end, and a through hole 12 communicating with the oil chamber 10. The through hole 12 communicates with the hydraulic system of the internal combustion engine, and hydraulic oil is supplied from the hydraulic system to the oil chamber 10 through the through hole 12.

A plunger 2 is fitted in the oil chamber 10. The plunger 2 can move forward in a direction in which the degree of protrusion from the opening 13 of the oil chamber 10 increases, and can retract in a direction in which the degree of protrusion from the opening 13 decreases. It is said that. Spring chamber 2 of plunger 2
A coil spring 22 is interposed at 0. Coil spring 2
2 urges the plunger 2 in the direction of arrow X5. A rack 25 is formed on the outer peripheral portion of the plunger 2, and a locking hole 26 as a locked portion is further formed.

A ratchet portion 3 is provided on the front end side of the housing 1 as a backward movement regulating portion. Ratchet part 3
Is composed of an oscillating body 31 pivotally supported by the housing 1 by a shaft 30 and a spring 32 for urging the oscillating body 31 in the direction of arrow S1. The locking teeth 31 a of the rocking body 31 urged by the spring 32 are attached to the rack 25 of the plunger 2.
Lock on. This allows the plunger 2 to move forward in the direction of arrow X5, but restricts the backward movement of the plunger 2 in the direction of arrow X6.

The pop-out restricting portion 4 is composed of a piston chamber 40, a lock piston 42, and a biasing spring 44. The piston chamber 40 is located on the outer peripheral side of the oil chamber 10 and is formed in communication with the oil chamber 10. The axis P1 of the piston chamber 40 is orthogonal to the axis of the oil chamber 10. The cross section of the piston chamber 40 may be circular or angular. A lid 46 is attached to the piston chamber 40. Piston chamber 4
A step portion 47 is formed on the inner wall portion of 0. The step portion 47 may be continuous in the circumferential direction of the piston chamber 40, or a plurality of step portions 47 may be provided at predetermined intervals in the circumferential direction.

The lock piston 42 is movably fitted in the piston chamber 40. The lock piston 42 is formed of a disk-shaped large-diameter portion 42b having a pressure receiving surface 42a and a rod-shaped locking projection 42d having a pressure receiving surface 42c. Oil chamber 1
When there is no hydraulic pressure of 0, the large diameter portion 42b is seated on the step portion 47. The biasing spring 44 biases the lock piston 42 along the axis P1. As shown in FIG. 1, the locking projection 42d of the lock piston 42 locks in the locking hole 26 of the plunger 2 as the bias is applied.

(Operation and Effect) When the tensioner is assembled to the cylinder head of the vehicle, the oil pressure is not applied to the oil chamber 10 and the condition is as shown in FIG. Therefore, the lock piston 42 urged by the urging spring 44 is urged along the axis P1 and seated on the step portion 47, and the locking protrusion 42d of the lock piston 42 is locked in the locking hole of the plunger 2. 26
Is locked to. Therefore, even if an external force acts on the tensioner, the protrusion of the plunger 2 from the opening 13 is prevented.

In particular, in this embodiment, the locking projection 42d of the lock piston 42 moves in a direction parallel to the axis P1 and locks the locking hole 26 of the plunger 2, so that the so-called "wedge principle" is applied. It does not work, and the protrusion of the plunger 2 is reliably prevented. This point is different from the conventional example shown in FIG. Therefore, the tip end surface 2a of the plunger 2 is set to the regular position M when the tensioner is assembled. This causes excessive tension on the chain, wear on the chain sprocket,
Problems such as broken guides and broken chains are avoided.

Further, in this embodiment, when the tensioner is assembled, the locking projection 42d of the lock piston 42 is locked in the locking hole 26 of the plunger 2, so that the plunger 2
The circumference of the plunger is restricted, and the plunger 2
Is also advantageous for positioning. Therefore, it is also advantageous to maintain the degree of engagement between the engagement teeth 31a of the ratchet portion 31 and the rack 25.

After the tensioner is assembled to the cylinder head, the working oil flows into the oil chamber 10 through the through hole 12 as the internal combustion engine is driven, and the oil pressure acts on the oil chamber 10. Since the oil pressure of the oil chamber 10 also acts on the pressure receiving surfaces 42a and 42c of the lock piston 42 via the spring chamber 20, the locking hole 26, and the passage 10c, the lock piston 42 compresses the urging spring 44 with the pressure. While moving in the direction of arrow Y6,
Get away from 7. As a result, the locking projection 42d of the lock piston 42 is disengaged from the locking hole 26 of the plunger 2 as shown in FIG. 2, and the lock by the lock piston 42 is released.

Therefore, the oil pressure of the oil chamber 10 and the coil spring 22
The plunger 2 moves forward in the direction of arrow X5 due to the urging force of
The protrusion degree from the opening 13 is increased, the looseness of the chain is adjusted, and the required tension degree of the chain is obtained. That is, in this embodiment, when the internal combustion engine is driven and the hydraulic pressure is increased with the tensioner assembled to the cylinder head, the lock by the lock piston 42 is automatically released.

When the internal combustion engine is stopped, the oil pressure in the oil chamber 10 drops or disappears.
Although there is a possibility of retreating in six directions, in this respect, since the locking teeth 31a of the rocking body 31 of the ratchet portion 3 are locked to the rack 25, the retreat of the plunger 2 is restricted and the chain is prevented from loosening. It Therefore, when the internal combustion engine is restarted, even if the hydraulic pressure acting on the oil chamber 10 is still small, the degree of tension of the chain is secured, so that problems such as chain jumping can be avoided.

Even when the oil pressure in the oil chamber 10 drops or disappears as described above, the ratchet portion 3 restricts the retreat of the plunger 2. Therefore, the locking projection 42d of the lock piston 42 is formed. Does not re-engage in the locking hole 26. (Other Example) FIG. 3 shows another example. This example is shown in FIG. 1 and FIG.
The configuration is basically the same as the example shown in. However, a reinforcing rib 42f is provided in a protruding manner on the locking projection 42d of the lock piston 42. Therefore, because the coil spring 22 biases the plunger 2 in the direction of arrow X5, even if the inner wall surface 26a of the locking hole 26 presses the locking projection 42d, it is advantageous to secure the strength of the locking projection 42d. Is. Also, the locking protrusion 42d
The solid lubricating film 42h is laminated on the solid lubricating film 4h.
Since the lubricity is further secured by 2 h, the locking protrusion 42
The friction between d and the inner wall surface 26a of the locking hole 26 is further reduced, and the movement of the lock piston 42 in the arrow Y6 direction is smoothed.

FIG. 4 shows another example. This example is shown in Figure 1.
The configuration is basically the same as the example shown in. However, since the lock piston 42 separates from the step portion 47,
When the lock function by is released, the ball 49 urged by the spring 48 is automatically locked in the groove 42k of the lock piston 42, and the lock piston 42 is held at that position. Therefore, even if the oil pressure in the oil chamber 10 drops due to the stop of the internal combustion engine, the lock piston 42 does not move in the arrow Y7 direction. Therefore, sliding contact between the pressure receiving surface 42c and the outer peripheral surface 2c of the plunger 2 is reliably avoided, and the forward and backward movement of the plunger 2 is facilitated.

Further, in each of the above-mentioned embodiments, the lock piston 42 includes the disk-shaped large-diameter portion 42b and the rod-shaped locking projection 42d.
However, the present invention is not limited to this, and it is also possible to form a rod-shaped body having substantially the same diameter in the length direction. Other,
The present invention is not limited to the embodiment described above and shown in the drawings. For example, instead of the locking hole 26 formed in the outer peripheral portion of the plunger 2, a convex projection is provided, and this projection and the lock piston are provided. The locking projection 42d of 42 may be locked, and the invention may be applied to not only a chain but also a belt, and various modifications may be made without departing from the scope of the invention.

[0028]

According to the tensioner of the present invention, when the tensioner is assembled to the mounting portion such as the cylinder head, the locking projection of the lock piston biased by the biasing spring is the locked portion of the plunger. Is locked to. Therefore, even if an external force acts on the tensioner, the protrusion of the plunger from the opening is reliably prevented. In particular, since the locking projection of the lock piston moves in a direction substantially orthogonal to the axis of the oil chamber and locks on the locked portion of the plunger, the projection of the plunger is surely prevented.

Therefore, when the tensioner is assembled to the mounting portion such as the cylinder head, the tip end surface of the plunger is surely set at the proper position. This avoids problems such as excessive chain tension, chain sprocket wear, broken guides, and broken chains. The plunger is prevented from popping out not only when assembled but also when the tensioner is stored or transported.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a tensioner.

FIG. 2 is a cross-sectional view showing a state in which a locking projection of a lock piston is disengaged from a locking hole.

FIG. 3 is a cross-sectional view near a lock piston according to another example.

FIG. 4 is a cross-sectional view near a lock piston according to another example.

FIG. 5 is a side view of a tensioner according to a conventional example in a sectional view showing a usage state.

FIG. 6 is a side view around a hook according to another conventional example.

[Explanation of symbols]

In the figure, 1 is a housing, 10 is an oil chamber, 13 is an opening, 2 is a plunger, 26 is a locking hole (locked part), 3 is a ratchet part (retraction restriction part), 4 is a projection restriction part, 40 Is a piston chamber, 42 is a lock piston, 42b is a large diameter portion, 42d
Is a locking projection, and 44 is a biasing spring.

Claims (1)

[Claims] 1. A housing having an oil chamber in the shape of a cylinder hole having an opening at the tip, and can be advanced along the axis of the oil chamber in a direction in which the degree of protrusion from the opening increases, and the degree of protrusion from the opening decreases. The endless winding body is fitted in the oil chamber so as to be retractable in a direction and has a recessed or convex locked portion formed on the outer peripheral portion thereof, and moves forward in response to the oil pressure of the oil chamber. A plunger for adjusting the tension of the wound body, a retreat restricting part for restricting the retreat of the plunger, and a protrusion restricting part for restricting the protrusion of the plunger from the opening. The pop-out restricting portion communicates with the housing in the housing in a direction substantially orthogonal to the axis of the housing and is formed on the outer peripheral side of the housing, and is movably fitted into the housing. A locking projection that locks with the locked part of the plunger and a receiver that receives the hydraulic pressure of the oil chamber. A lock piston, which has a surface and whose locking projection is disengaged from the locked portion of the plunger when pressure is applied, and biases the lock piston in a direction substantially orthogonal to the axis of the oil chamber. And a biasing spring that locks the locking projection of the above with the locked portion of the plunger.