JPH0747632Y2 - Chain tensioner device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a chain tensioner device used in a chain drive mechanism.

(Prior Art) A conventional chain tensioner device arranges the pressure of the oil pumped from an oil pump in the body body with a groove for discharging the oil and a small diameter oil hole, and reduces the pressure to a pressure suitable for that case. There is a type that adjusts the tension of the chain by this plunger and a type that a check valve is provided in the passage through which the oil passes to limit the retreat of the plunger. However, the former does not prevent the retraction of the plunger due to the tension of the chain, and when the chain vibrates, it cannot be suppressed and causes noise.

Also, in the latter, the inflow of oil from the check valve and the outflow of oil from the leak groove are repeated according to the movement of the plunger.
When the tension of the chain is suddenly increased, the oil outflow from the leak groove cannot catch up, the hydraulic pressure in the plunger increases significantly, and the chain is pressed with more force than necessary. In addition to producing sound, it has been desired to deal with the tensioner itself in order to further improve its durability.

(Problems to be solved by the invention) In order to solve the above-mentioned problems, the chain tensioner device according to the present invention is provided with a biasing means capable of following a sudden vibration of the chain so that the plunger is always provided with a hydraulic pressure adapted to that case. The tensioner device according to the present invention is provided.

(Means for Solving the Problems) Therefore, the present invention comprises a body, a plunger slidably inserted into the body, and a piston slidably inserted into the body. A first hydraulic chamber formed between them and a second hydraulic chamber formed between the body and the piston, and the piston is provided facing the first hydraulic chamber, and the plunger and the piston respectively have pistons. A tensioner device for providing tension to a chain by providing a spring for urging, the tip end portion of the plunger protruding from the shoulder portion of the body, and contacting the tensioner band, wherein the first hydraulic chamber is caused by movement of the plunger. In order to prevent the hydraulic pressure from rising excessively, if the pressure in the first hydraulic chamber rises, the piston is retracted to adjust the fluctuation of the volume of the first hydraulic chamber. It is a means for solution.

(Operation) In the above configuration, when the number of revolutions is high and the chain is abnormally tensioned, the piston retracts and the pressure in the first hydraulic chamber is adjusted. Further, if the number of rotations decreases and the slack of the chain comes out, the plunger is moved forward by a spring provided as a biasing means on the plunger and the piston, and the tension of the chain can be adjusted.

In addition, even when the plunger is suddenly pressed, the piston retreats quickly and the pressure fluctuation in the first hydraulic chamber is suppressed.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a state in which the chain tensioner device according to the present invention is used, in which the tensioner band 21 is slid on the chain 20 and the tensioner band 21 is pressed by the tensioner device 1.

2 and 3 show an embodiment of the tensioner device of the present invention, FIG. 2 shows the case where the chain is bent, and FIG. 3 shows the state in which the chain is stretched.

The above embodiment will be described with reference to FIG. 2. In the body 2, the first hydraulic chamber 5, the second hydraulic chamber 9, and the oil passages 13 and 14 connecting these two hydraulic chambers are arranged in the piston 7. . The body 2 is provided with an oil inlet 16 leading to the second hydraulic chamber 9 as shown in the figure. The plunger 3 is movably and airtightly fitted in the first hydraulic chamber 5, and the end of the plunger 3 presses the tensioner band 21.

A spring 4 for urging the pressing force of the plunger 3 is inserted inside the plunger 3, and one end of the spring 4 is supported by one end of the plunger 3 and the other end is formed by the body 2
It is supported by the end wall of the first hydraulic chamber 5. The piston 7 is movably and airtightly fitted in the second hydraulic chamber 9, and a check valve 11 is provided inside the piston 7 to increase the pressure in the first hydraulic chamber 5. At this time, the oil is prevented from flowing into the second hydraulic chamber 9. A spring 8 for urging the piston 7 is inserted inside the second hydraulic chamber 9, one end of the spring 8 is supported by one end of the piston 7, and the other end is supported by a stopper 10.

FIG. 2 shows the state in which the chain is bent, and the oil supplied from the oil inlet 16 is
The hydraulic chamber 9 is filled, and the oil passages 14 and 13 are further introduced to fill the first hydraulic chamber 5. At this time, the piston 7 is the spring 8
Due to the urging of the piston 7, the collar 17 of the piston 7 is attached to the body 2.

The plunger 3 pushes the chain 20 via the tensioner band 21 by the resultant force of the hydraulic pressure in the first hydraulic chamber 5, the second hydraulic chamber 9 and the spring 4, and the chain 20 is tensioned and the chain 20 When vibrating, the plunger 3 repeats forward and backward movements.

FIG. 3 shows that in the embodiment shown in FIG.
The plunger 3 is pushed via 21 and the plunger 3 moves backward against the spring 4 in the downward direction of the first hydraulic chamber 5. At this time, the pressure in the first hydraulic chamber rises, and the oil leaks through the leak groove 6 without delay. When the pressure rises further, the oil is blocked by the check valve 11. Therefore, the piston 7 in the body 2 has the spring 8 Move downwards against. This state is shown.

If the plunger 3 is pushed downward by the vibration of the chain and tries to retreat against the resultant force between the hydraulic pressure in the first hydraulic chamber 5 and the spring 4, the hydraulic pressure in the first hydraulic chamber 5 becomes high and the piston 7 and the spring 8 also move. Against this, the pressure in the first hydraulic chamber 5 is relieved, and unnecessary tension is not applied to the chain. If the chain comes loose, plunge 3
Moves upward, and the hydraulic pressure in the first hydraulic chamber decreases. Then, oil flows from the inflow port 16 and passes through the second hydraulic chamber to the oil passages 14, 13
Flow into the first hydraulic chamber 5. Further, springs 4 and 8 are provided as biasing means in order to accelerate the return of the plunger 3 and the piston 7.

FIG. 4 shows the relationship between the pressure of the first hydraulic chamber and the plunger frequency which influence the chain pressing force of the tensioner device, and P shows the pressure of the first hydraulic chamber 5 shown in FIG. f represents the frequency of the plunger 3 shown in FIG. 2, and the curve A in the figure represents the relationship between the chamber pressure of the conventional tensioner and the plunger frequency. In the conventional tensioner device, the chamber pressure increases significantly as the frequency increases,
The tensioner of the chain will be pushed too much. Curve B shows the relationship between the chamber pressure of the first hydraulic chamber 5 and the vibration frequency of the plunger 3 of the tensioner device of the present invention. At a low frequency, the pressure is equivalent to that of the conventional example, but the frequency is large. In this case, the rise of the chamber pressure due to the retreat of the piston 7 is small, and it means that an appropriate pressing force is maintained on the chain.

(Effect of the Invention) In the conventional tensioner device, when a pressing force is applied to the plunger 3 as shown in FIG. 5, the plunger 3 retreats downward, and if the pressing force is small, the oil in the plunger 3 leaks. However, if the rotation speed increases and the vibration frequency of the plunger 3 increases, the oil will not flow out and the hydraulic pressure in the plunger will be high, resulting in an increase in the tensioner pressing force and pressing the chain more than necessary. It will be. Then, an unpleasant sound is generated and wear is caused, and it is desired to cope with it in order to further improve durability.

In the tensioner device of the present invention, since the plunger always has an appropriate amount of retreat, the chain will not be pushed with an abnormally large force, a constant tension can be given to the chain, and the durability of the tensioner device itself is improved. Therefore, it is possible to prevent the generation of noise due to the contact between the chain and the tensioner belt.

Further, compared with the conventional one, even if the hydraulic pressure in the plunger hydraulic chamber rises, the pressure is adjusted without discharging the high pressure oil, so that the followability is improved and there is an advantage that noise can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a chain tensioner device according to the present invention, FIG. 2 is an enlarged view of FIG. 1 showing a state in which a chain is bent, and FIG. FIG. 4 is an enlarged view of the drawing and is a cross-sectional view showing a state in which the chain is stretched, and FIG. 4 shows the relationship between the pressure in the hydraulic chamber and the plunger frequency. FIG. 5 is a sectional view of a conventional example. 1 …… Tensioner device 2 …… Body 3 …… Plunger 4 …… Spring 5 …… First hydraulic chamber 6 …… Leak groove 7 …… Piston 8 …… Spring 9 …… Second hydraulic chamber 11 …… Check valve 13 ...... Oil passage 14 ...... Oil passage 16 ...... Inlet

Claims (1)

[Scope of utility model registration request] 1. A body, a plunger slidably inserted into the body to press a tensioner band against a chain, and a first spring interposed between the body and the plunger to urge the plunger in a forward direction. In a chain tensioner device having a first hydraulic chamber formed between the body and the plunger, a piston is slidably inserted into the body facing the first hydraulic chamber, the body and the piston A second spring for urging between the body and the piston, a second hydraulic chamber is provided between the body and the piston, and the piston blocks the flow of oil from the first hydraulic chamber to the second hydraulic chamber. A check valve is provided, and when the hydraulic pressure of the first hydraulic chamber rises due to the movement of the plunger, the urging means is provided to retract the piston to keep the first hydraulic chamber at a constant pressure. That the chain tensioner device.