JP2510675Y2 - Oil operated tensioner with check valve on fixed member - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-operated tensioner for applying a predetermined tension force to a toothed belt used for driving a camshaft of an engine.

[0002]

2. Description of the Related Art An example of the use of a toothed belt is driving a camshaft of an engine. The toothed belt in this case is suspended around the crank sprocket and the cam sprocket.
The toothed belt must be properly tensioned to prevent skipping between the toothed belt and the cam sprocket. Therefore, a tensioner is used.

FIG. 5 shows a conventional oil operated tensioner. This type of oil operated tensioner 50
A cylinder 52 filled with oil is loosely fitted with a small gap to divide the cylinder 52 into a piston front chamber 62 and a piston rear chamber 64, and a piston 70 having a rod 60 on the piston front chamber side is provided with a protrusion force by a spring 70. Then, tension is applied to the toothed belt. And
A check valve 74 that allows oil to flow into the piston rear chamber 64 in an oil passage 72 that connects the piston front chamber 62 and the piston rear chamber 64.
Is provided to prevent the piston 58 from retracting rapidly.

[0004]

In the above tensioner, the check valve 7 is provided in the oil passage 72 formed in the piston 58.
4 are provided. Therefore, the diameter of the oil passage 72 is small, and the length thereof is also considerably long, which inevitably increases the oil flow resistance. As a result, when the piston 58 moves forward, the piston front chamber 62
Therefore, there is a problem in that the time for the oil to flow into the piston rear chamber 64 becomes long and the piston 58 flutters back and forth. Further, since the check valve 74 is installed on the piston 58, when the piston 58 repeatedly vibrates slightly, the check valve 7
It is considered that the balls constituting No. 4 make an irregular movement due to inertial force, and the function required for the check valve is not fulfilled. In most cases, the oil passage of the piston 58 is the rod 60.
Since it will be provided at the base of the, there is also a strength problem such as a broken rod.

This invention intends to solve the above problems by making the length of the oil passage between the high pressure chamber and the low pressure chamber as short as possible and providing the check valve on the fixed member side. .

[0006]

According to the present invention, there is provided a cylindrical cylinder, a partition for dividing the cylinder into a front chamber and a rear chamber, and a cylindrical sleeve provided in the cylinder front chamber adjacent to the partition. A first piston having a rod which is fitted onto the sleeve with a small gap to form a high pressure chamber with the sleeve, and a seal provided between the cylinder and the first piston. Member and fit inside the sleeve part
A coil spring that is inserted to give a protruding force to the first piston, a sealing member that forms the cylinder rear chamber between the partition wall, and a communication between the cylinder rear chamber and the high pressure chamber. A first oil passage, the high pressure chamber to the sleeve and the first
Second oil passage configured to return the oil flowing out through a small gap between the piston and the second oil passage to the cylinder rear chamber, and allowing the oil to flow into the high pressure chamber provided in the first oil passage. An oil operated tensioner having a check valve solves the above problems.

[0007]

The rod of the first piston is in contact with the arm supporting the idler roller at its tip. When the tension force of the toothed belt increases, a pressing force is generated in the first piston in the backward direction of the piston. At this time, the check valve is closed and the oil in the high pressure chamber resists the pressing force to prevent the piston from moving backward.
The oil in the high-pressure chamber slowly flows out through the small gap between the sleeve and the first piston and returns to the cylinder rear chamber, so that the toothed belt is gradually relaxed in tension. Oil flows into the cylinder rear chamber through the second oil passage. The cylinder rear chamber acts as an accumulator chamber that absorbs the volume change of the high pressure chamber due to the back-and-forth movement of the first piston.

When the tension of the toothed belt decreases, the first piston projects due to the biasing force of the coil spring. At this time, the check valve opens and oil flows into the high pressure chamber through the first oil passage formed in the partition wall. Since the high-pressure chamber and the accumulator chamber are adjacent to the partition on both sides, and the partition is provided with the first oil passage, the flow resistance of the oil when the first piston moves forward is suppressed to a minimum . One piston can move forward quickly. Further, since the check valve is provided in the partition wall that is the fixing member, the check valve does not open due to the vibration of the first piston. In this way, when the toothed belt becomes loose, its tension is quickly recovered, and even if vibration occurs in the tensioner, the check valve is not affected by the vibration, so the tension is always constant. Can be kept at

A second member in which a sealing member is fitted in the rear chamber of the cylinder.
The cylinder rear chamber is maintained at a positive pressure by applying a biasing force to this piston in the direction of the cylinder rear chamber. When the piston moves forward, the check valve opens due to the negative pressure in the high pressure chamber, so that by maintaining the positive pressure in the cylinder rear chamber, rapid oil supply to the high pressure chamber is performed. In combination with the provision of the first oil passage in the partition wall, the forward speed of the piston is further increased, and when the toothed belt becomes loose, its tension force is rapidly recovered.

[0010]

1 is a sectional view of an oil operated tensioner according to an embodiment of the present invention. Oil operated tensioner 10
Has a cylindrical cylinder 14 divided into a cylinder front chamber 16 and a cylinder rear chamber 18 by a partition wall 12. In this embodiment, the partition wall 12 is integrally formed with the cylinder 14, but it may be pressed into the cylinder 14.

The cylinder front chamber 16 is provided with a cylindrical sleeve 20 concentric with the cylinder 14. The cylindrical sleeve 20 has a recess 13 (FIG. 3) formed in the partition wall 12.
One end is pressed into. The first piston 21 is fitted onto the sleeve 20 with a small gap. A rod 22 is integrally processed at the tip of the first piston 21. The rod 22 is in contact with an idler arm (not shown). A high pressure chamber 24 is formed by the sleeve 20 and the first piston 21, and a compression coil spring 26 is fitted and inserted therein.

The first piston 21 is inserted into the inner circumference of the cylinder 14 with a relatively large gap. A seal member 28 is provided in the cylinder front chamber 16. The seal member 28 is in contact with the rod 22 to prevent oil from leaking from the cylinder front chamber 16. First piston 21
Has a groove 23 extending in the axial direction on the outer peripheral side.
The oil reaches the seal member 28 through this groove. The diameters of the first piston 21 and the cylinder 14 may be set so that the first piston 21 slides on the inner peripheral surface of the cylinder 14.

As shown in FIGS. 2 and 3, the partition wall 12
A first oil passage 30 is provided in the center of the.
The first oil passage 30 connects the cylinder rear chamber 18 and the high pressure chamber 24. The partition wall 12 is further formed with a plurality of holes 32 near the inner circumference of the cylinder 14. Sleeve 20
The oil that has flowed out of the small gap between the first piston 21 and the first piston 21 passes through the hole 32 of the partition wall 12 and the annular chamber 34 formed between the inner circumference of the cylinder 14 and the sleeve 20 and the first piston 21. Returned to chamber 18. A check valve 36 is provided on the high-pressure chamber 24 side of the first oil passage 30. The check valve 36 blocks the reverse flow of oil from the high pressure chamber 24 to the cylinder rear chamber 18. Reference numeral 38 is a fastener that determines the protrusion limit of the first piston.

Returning to FIG. 1, the cylinder rear chamber 18 has a second
Piston 40 is inserted. This piston 40
Is urged toward the cylinder rear chamber 18 by a spring 42. Therefore, the hydraulic pressure in the cylinder rear chamber 18 is always kept positive. 44 is a seal member for the second piston 40.

Although the present invention has the above-described structure, various modifications can be made. For example, as shown in FIG. 4, the sleeve 20 'may simply be brought into contact with the partition wall 12'. In this case, the first piston 21 is the cylinder 1
4 is guided by the inner peripheral surface of the first piston 21
Prevents rattling. Further, in the first embodiment, the partition wall 12 and the sleeve 20 are separate bodies, but they may be integrally formed and press-fitted into the cylinder 14.

[0016]

[0017]

[Effect of the invention The present invention, since an above-described configuration, when the tension of the toothed belt is decreased, the spring is adapted to protrude the first piston, the check valve opens under the action of the second piston When oil is rapidly supplied from the cylinder rear chamber to the high pressure chamber, and the tension of the toothed belt increases, the check valve closes and the first piston does not retract suddenly, but the tension of the toothed belt slowly increases. The power can be relieved.

In particular, in the present invention, the cylinder rear chamber, which serves as an oil accumulator chamber, is adjacent to the high pressure chamber by one partition wall, and oil is supplied from the cylinder rear chamber to the high pressure chamber through an oil passage formed in this partition wall. I chose As a result, the distance of the oil passage can be minimized, and the oil flow resistance is minimized compared to the conventional piston provided with an oil passage, so that the first piston can be ejected quickly. It is possible to supply various oils. As a result, the time during which the oil is supplied to the high pressure chamber is shortened, and the fluttering of the first piston is suppressed. Furthermore, a cylindrical sleeve provided adjacent to the bulkhead
Since it was fitted inside the first piston, fit it inside the sleep
The coil spring has a position where the first piston protrudes or
Even if it moves backward, its entire length is always
The coil spring is crushed because it is expanded and contracted by being guided by one piston.
Proper pressure is applied to the first piston without bending
It is possible to secure the function of the tensioner.
It is capable of

The check valve is provided not on the first piston but on the partition wall serving as a fixing member, and the check valve may be affected by the vibration even when the first piston vibrates in the front-rear direction. Few. Accordingly, it is possible to always obtain proper operation of the check valve.

Further, by removing the oil passage from the first piston and arranging the accumulator chamber, which was in front of the piston in the past, at the rear of the partition wall, the total length of the piston and the rod can be shortened, and the strength of the piston can be shortened. It is possible to obtain a tensioner with improved performance.

In the tensioner of the second aspect, since the cylinder rear chamber is maintained at a positive pressure, when the check valve is opened, oil is rapidly supplied from the cylinder rear chamber to the high pressure chamber, and the toothed belt is The tension can be restored rapidly. In addition,
In the present invention, since the cylinder rear chamber, that is, the accumulator chamber is provided behind the high pressure chamber and the first piston, the cross sectional area of the accumulator chamber can be designed to be larger than that of the high pressure chamber. Therefore, the second piston absorbs the volume change of the high-pressure chamber due to the back-and-forth movement of the first piston by only slightly moving, so that the durability of the second piston and the seal member is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an oil operated tensioner according to the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a partially enlarged cross-sectional view showing another mounting relationship between the partition wall and the sleeve.

FIG. 5 is a sectional view of a conventional oil-operated tensioner.

[Explanation of symbols]

 10 Oil-operated tensioner 12, 12 'Partition wall 13 Recess 14 Cylinder 16 Cylinder front chamber 18 Cylinder rear chamber 20, 20' Sleeve 21 First piston 22 Rod 23 Groove 24 High pressure chamber 26 Compression coil spring 28 Seal member 30 1st Oil passage 32 hole (second oil passage) 34 annular chamber (second oil passage) 36 check valve 38 fastener 40 second piston (sealing member) 42 second spring 44 seal member

Claims (2)

(57) [Scope of utility model registration request] 1. A cylindrical cylinder, a partition wall dividing the cylinder into a front chamber and a rear chamber, a cylindrical sleeve provided adjacent to the partition wall in the cylinder front chamber, and externally fitted to the sleeve with a small gap. A first piston having a rod and forming a high-pressure chamber with the sleeve , a seal member provided between the cylinder and the first piston, and being inserted into the sleeve portion to be inserted into the sleeve. A coil spring that gives a thrust force to the first piston; a sealing member that forms the cylinder rear chamber between the partition wall; a first oil passage that connects the cylinder rear chamber and the high-pressure chamber; A second oil passage configured to return oil flowing from the high-pressure chamber through the small gap between the sleeve and the first piston to the cylinder rear chamber, and the second oil passage provided in the first oil passage. The flow of oil into the high pressure chamber Oil operated tensioner with check valve allowing. 2. The oil-operated tensioner according to claim 1, wherein the sealing member is a second piston fitted and inserted in the cylinder rear chamber, and the piston is biased toward the cylinder rear chamber.