JP2008190579A - Automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic tensioner with few parts which can exhibit stable damping effect over long period of time. <P>SOLUTION: The automatic tensioner is characterized in that hydraulic fluid is accumulated in a cylinder 10, in that a lower periphery of sleeve 11 is inserted in a sleeve fitting concavity 12 formed in a bottom 9 of the cylinder, in that the cylinder is partitioned into a pressure chamber 14 and reservoir chamber 15 by slidably inserting a rod 13 in the sleeve, in that a return spring 17 biassing the rod is arranged, in that a passage 24 communicating a lower portion of the pressure chamber and lower portion of the reservoir chamber is formed between the sleeve fitting concavity and sleeve fitting surface, in that a seal ring 25 capable of closing an opening of pressure chamber side of the passage is slidably arranged in a lower inner periphery of the sleeve, in that a moving range of the seal ring is regulated by a step 26 formed in an inner periphery of the sleeve, in that only a stream of the hydraulic fluid from passage reservoir chamber side to pressure chamber side is permitted by the seal ring, and in that a steel seal ring seat 27 contacted when the seal ring closes the passage is arranged in the sleeve fitting concavity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an auto tensioner used for maintaining the tension of a belt for driving an automobile auxiliary machine such as an alternator.

  An auxiliary machine of an automobile, for example, an alternator, a car air conditioner, a water pump, or the like has a rotating shaft connected to a crankshaft of an engine by a belt, and is driven by the engine through the belt. In order to keep the tension of this belt within an appropriate range, generally, a pulley arm that is swingable about a fulcrum shaft, a tension pulley that is rotatably attached to the pulley arm, and a direction in which the tension pulley is pressed against the belt. A tension adjusting device including an auto tensioner that biases the pulley arm is used.

  As an auto tensioner incorporated in this tension adjustment device, hydraulic oil is stored in a cylinder having a bottom at the bottom, and the outer periphery of the lower portion of the sleeve is fitted into a sleeve fitting recess formed at the bottom of the cylinder, and a rod is placed in the sleeve. It is known that the cylinder is slidably inserted in the axial direction and the inside of the cylinder is partitioned into a pressure chamber and a reservoir chamber, and the rod is urged by a return spring in the direction of expanding the volume of the pressure chamber (Patent) Reference 1).

  In this auto tensioner, the rod moves to a position where the urging force of the return spring balances with the belt tension, thereby absorbing the belt tension fluctuation and keeping the belt tension within an appropriate range.

  Further, the pressure chamber and the reservoir chamber communicate with each other through a leak gap formed between the sliding surface of the sleeve and the rod, and when the rod moves in a direction in which the volume of the pressure chamber decreases, the hydraulic oil in the pressure chamber Flows out through the leak gap. At this time, since the flow rate of the hydraulic oil flowing through the leak gap is limited, the rod moves slowly and absorbs the tension while keeping the belt in a stable state.

Further, in this auto tensioner, a passage is formed between the sleeve fitting recess and the fitting surface of the sleeve so as to communicate the lower portion of the pressure chamber and the lower portion of the reservoir chamber, and from the reservoir chamber side of the passage to the pressure chamber side. A check valve that allows only the flow of the hydraulic oil is incorporated in the lower part of the sleeve. Therefore, in this auto tensioner, the rod quickly moves in the direction in which the volume of the pressure chamber increases, and quickly absorbs the slack of the belt.
Special Table 2000-504395

  However, in this auto tensioner, the check valve has a valve seat that is press-fitted into the lower inner periphery of the sleeve, a check ball that can close a valve hole formed in the upper surface of the valve seat, and an upper portion of the check ball. It consists of a retainer that regulates the range of movement and a valve spring that urges the check ball toward the valve seat. Therefore, this auto tensioner has poor assembly workability.

  Therefore, in order to improve the assembly workability of the auto tensioner, the inventor of the present invention stores hydraulic oil in an aluminum alloy cylinder having a bottom at the bottom, and in a sleeve fitting recess formed at the bottom of the cylinder. The lower outer periphery of the sleeve is fitted, the rod is inserted into the sleeve so as to be slidable in the axial direction, and the inside of the cylinder is divided into a pressure chamber and a reservoir chamber, and is formed between the sliding surface of the sleeve and the rod. A return spring is provided that communicates the pressure chamber and the reservoir chamber via a leak gap, and urges the rod in a direction of expanding the volume of the pressure chamber, and between the sleeve fitting recess and the fitting surface of the sleeve. A passage that connects the lower portion of the pressure chamber and the lower portion of the reservoir chamber is formed, and a seal ring that can close the opening on the pressure chamber side of the passage is slid in the axial direction on the lower inner periphery of the sleeve And the range of upward movement of the seal ring is restricted by a step formed on the inner periphery of the sleeve, and only the flow of hydraulic oil from the reservoir chamber side to the pressure chamber side of the passage is performed by the seal ring. An auto-tensioner designed to allow this is devised.

  In this auto tensioner, the seal ring functions as a valve body of a check valve that allows only the flow of hydraulic oil from the reservoir chamber side to the pressure chamber side of the passage, and a retainer that restricts the upward movement range of the valve body. Since the step portion formed on the sleeve is used, it is not necessary to incorporate a part other than the sleeve as a retainer. Therefore, this auto tensioner has a small number of parts and is excellent in assembling workability.

  However, when the seal ring closes the sleeve fitting recess made of an aluminum alloy when the seal ring closes the opening on the pressure chamber side of the passage, the auto tensioner The abutment surface is easily worn. When the contact surface is worn, the hydraulic oil tends to leak from the pressure chamber to the passage due to the wear, and the auto tensioner may not be able to sufficiently exhibit the damping effect. Further, when the cylinder is produced by casting, if a cast hole is formed on the contact surface of the sleeve fitting recess with the seal ring, hydraulic oil may leak through the cast hole.

  The problem to be solved by the present invention is to provide an auto tensioner having a small number of parts and capable of exhibiting a stable damping effect over a long period of time.

  In order to solve the above-mentioned problems, the above-described configuration is adopted in an auto tensioner, and a steel seal ring seat that abuts when the seal ring closes the opening on the pressure chamber side of the passage is provided with the sleeve fitting recess. Provided inside.

  This autotensioner becomes more preferable when the seal ring seat is subjected to a surface hardening treatment (for example, soft nitriding treatment, carburizing and quenching treatment).

  In the auto tensioner according to the present invention, the seal ring is provided with which the seal ring comes into contact when the opening on the pressure chamber side of the passage is closed, and the seal ring seat is made of steel. Therefore, the passage is closed with the seal ring. When the operation is repeated, the contact surface of the seal ring seat with the seal ring is not easily worn. Therefore, this auto tensioner can exhibit a stable damping effect over a long period of time.

  In addition, when the seal ring seat is subjected to a surface hardening treatment, the seal ring seat is more excellent in wear resistance, and thus can exhibit a stable damping effect for a longer period of time.

  1 and 2 show a tension adjusting device for a belt 1 for driving an automobile auxiliary machine. This tension adjusting device has a tension pulley 2 that contacts the belt 1 and a pulley arm 3 that rotatably supports the tension pulley 2, and the pulley arm 3 is attached to a fulcrum shaft 5 that is fixed to the engine block 4 shown in FIG. It is supported so that it can swing.

  One end of an auto tensioner 6 according to an embodiment of the present invention is rotatably connected to the pulley arm 3 around a connecting shaft 7, and the other end of the auto tensioner 6 is rotatable to a connecting shaft 8 fixed to the engine block 4. It is connected to. The auto tensioner 6 biases the pulley arm 3 to press the tension pulley 2 against the belt 1.

  As shown in FIG. 2, in the auto tensioner 6, hydraulic oil is stored in a cylinder 10 having a bottom 9 at the bottom. In the cylinder 10, a sleeve 11 is inserted coaxially with the cylinder 10, and a lower outer periphery of the sleeve 11 is fitted in a sleeve fitting recess 12 formed in the bottom 9 of the cylinder 10. A rod 13 is inserted into the sleeve 11 so as to be slidable in the axial direction, and the cylinder 10 is partitioned into a pressure chamber 14 and a reservoir chamber 15 by the sleeve 11 and the rod 13.

  A spring seat 16 is fixed to the upper portion of the rod 13. A return spring 17 is incorporated between the spring seat 16 and the bottom 9 of the cylinder 10, and the return spring 17 urges the rod 13 in the direction of expanding the volume of the pressure chamber 14.

  The spring seat 16 is provided with a cylindrical skirt 19 slidably contacting an annular seal member 18 provided on the inner periphery of the upper portion of the cylinder 10, whereby the hydraulic oil in the cylinder 10 is sealed. .

  A groove 20 continuous in the circumferential direction is formed on the lower outer periphery of the rod 13, and a C-shaped ring-shaped retaining ring 21 is fitted in the groove 20. Further, a step portion 22 having a small diameter on the reservoir chamber 15 side is formed on the inner periphery of the sleeve 11, and the retaining ring 21 is stepped when the rod 13 moves in the direction of increasing the volume of the pressure chamber 14. The rod 13 is latched to the sleeve 11 by the latching.

  Between the sliding surfaces of the sleeve 11 and the rod 13, a leak gap 23 that connects the pressure chamber 14 and the reservoir chamber 15 is formed.

  Between the sleeve fitting recess 12 and the fitting surface of the sleeve 11, a passage 24 that communicates the lower portion of the pressure chamber 14 and the lower portion of the reservoir chamber 15 as shown in FIG. 3 is spaced in the circumferential direction as shown in FIG. A plurality are formed. The passage 24 can be formed by providing a groove on the inner surface of the sleeve fitting recess 12.

  A seal ring 25 is provided on the inner periphery of the lower portion of the sleeve 11 so as to be slidable in the axial direction. With the seal ring 25, the opening on the pressure chamber 14 side of the passage 24 can be closed. In addition, a step portion 26 having a large diameter on the lower side is formed on the inner periphery of the sleeve 11, and the range of upward movement of the seal ring 25 is regulated by the step portion 26.

  As shown in FIG. 6, the seal ring 25 has an outer peripheral upper portion 25 </ b> A divided in the circumferential direction, and an outer peripheral lower portion 25 </ b> B is divided in the circumferential direction at a position shifted in the circumferential direction with respect to the division position of the outer peripheral upper portion. 25C has a shape that is divided in the circumferential direction at a position shifted in the circumferential direction with respect to any of the divided position of the outer peripheral upper portion 25A and the divided position of the outer peripheral lower portion 25B, and the circumferential gap at each divided position The diameter can be increased by changing the size of. The seal ring 25 is made of a fluororesin material.

  As shown in FIG. 3, a seal ring seat 27 is provided in the sleeve fitting recess 12. The seal ring seat 27 includes a cylindrical portion 28 and a flange portion 29 formed at the lower end of the cylindrical portion 28. The cylindrical portion 28 is attached to a protrusion 30 formed on the inner bottom surface of the sleeve fitting recess 12 with a margin to fix the position of the seal ring seat 27. The flange portion 29 faces the lower surface of the seal ring 25, and the seal ring 25 comes into contact when the seal ring 25 closes the opening of the passage 24 on the pressure chamber 14 side.

  Next, an operation example of the auto tensioner 6 will be described.

  When the tension of the belt 1 increases, the tension is transmitted to the rod 13 through the tension pulley 2, the pulley arm 3, and the spring seat 16, and the pressure in the pressure chamber 14 increases. When the pressure in the pressure chamber 14 becomes higher than the pressure in the reservoir chamber 15, the hydraulic oil flows through the leak gap 23 from the pressure chamber 14 side to the reservoir chamber 15 side. At this time, as shown in FIG. 3, due to the pressure difference between the pressure chamber 14 and the reservoir chamber 15, the seal ring 25 moves downward to contact the seal ring seat 27 and close the opening on the pressure chamber 14 side of the passage 24. Therefore, the hydraulic oil does not flow through the passage 24. As the hydraulic oil flows through the leak gap 23 in this way, the rod 13 moves downward, and the tension pulley 2 moves to a position where the tension of the belt 1 and the biasing force of the return spring 17 are balanced. At this time, since the flow rate of the hydraulic oil flowing through the leak gap 23 is limited and a damping effect is generated, the tension pulley 2 moves slowly and absorbs the tension while keeping the belt 1 in a stable state.

  On the other hand, when the tension of the belt 1 is reduced, the rod 13 is moved upward by the urging force of the return spring 17 and the volume of the pressure chamber 14 is increased, so that the pressure in the pressure chamber 14 is lowered. When the pressure in the pressure chamber 14 becomes lower than the pressure in the reservoir chamber 15, the seal ring 25 moves away from the seal ring seat 27 due to the pressure difference between the pressure chamber 14 and the reservoir chamber 15 as shown in FIG. As a result, the opening of the passage 24 on the pressure chamber 14 side is opened, and hydraulic oil flows through the passage 24 from the reservoir chamber 15 side to the pressure chamber 14 side. At this time, the tension pulley 2 quickly moves to a position where the tension of the belt 1 and the urging force of the return spring 17 are balanced, and quickly absorbs the slack of the belt 1.

  The auto tensioner 6 functions as a valve body of a check valve in which the seal ring 25 allows only the flow of hydraulic oil from the reservoir chamber 15 side to the pressure chamber 14 side of the passage 24, and the valve body moves upward. Since the step portion 26 formed on the sleeve 11 is used as a retainer for regulating the range, it is not necessary to incorporate a part other than the sleeve 11 as a retainer. Therefore, the auto tensioner 6 has a small number of parts and is excellent in assembling workability.

  Further, in this auto tensioner 6, since the seal ring seat 27 is made of steel, the contact surface of the seal ring seat 27 with the seal ring 25 is not easily worn when the operation of closing the passage 24 with the seal ring 25 is repeated. . Therefore, the auto tensioner 6 can exhibit a stable damping effect over a long period of time.

  Furthermore, when the autotensioner 6 is subjected to surface hardening treatment (for example, soft nitriding treatment, carburizing and quenching treatment, etc.) on the seal ring seat 27 to improve the wear resistance of the seal ring seat 27, a stable damping effect over a longer period of time. Demonstrate.

  In addition, since the seal ring 25 does not come into contact with the inner bottom surface of the sleeve fitting recess 12 when the passage 24 is closed by the seal ring 25, the auto tensioner 6 is produced by casting the cylinder 10 into the sleeve fitting recess 12. Even in the case where a cast hole is generated, there is no leakage of hydraulic oil through the cast hole.

  Further, since the diameter of the seal ring 25 can be increased, when the passage 24 is closed by the seal ring 25, the diameter of the seal ring 25 is increased due to the pressure difference between the pressure chamber 14 and the reservoir chamber 15. It is pressed against the inner periphery of the sleeve 11. Therefore, a gap is hardly generated between the outer periphery of the seal ring 25 and the inner periphery of the sleeve 11, and the hydraulic oil in the pressure chamber 14 hardly leaks between the outer periphery of the seal ring 25 and the inner periphery of the sleeve 11.

  Further, as shown in FIG. 4, the division position of the outer peripheral upper portion 25 </ b> A and the division position of the outer peripheral lower portion 25 </ b> B are shifted from each other, so that the pressure chamber 14 is closed when the passage 24 is closed by the seal ring 25. The hydraulic oil inside is less likely to leak from the upper surface to the lower surface of the seal ring 25. Further, as shown in FIG. 4, the division position of the inner peripheral portion 25C of the seal ring 25 is shifted from both the division position of the outer peripheral upper portion 25A and the division position of the outer peripheral lower portion 25B. When the passage 24 is closed, the hydraulic oil in the pressure chamber 14 is unlikely to leak from the inner periphery of the seal ring 25 to the lower surface.

The front view which shows the tension adjustment apparatus incorporating the auto tensioner of embodiment of this invention Expanded sectional view along the line II-II in FIG. FIG. 2 is an enlarged sectional view of the vicinity of the lower portion of the sleeve. Sectional view along line IV-IV in FIG. FIG. 3 is an enlarged cross-sectional view showing a process in which the rod of FIG. 3 moves in the direction of enlarging the volume of the pressure chamber. 3 is a perspective view of the seal ring shown in FIG.

Explanation of symbols

9 Bottom 10 Cylinder 11 Sleeve 12 Sleeve fitting recess 13 Rod 14 Pressure chamber 15 Reservoir chamber 17 Return spring 22 Step portion 23 Leak gap 24 Passage 25 Seal ring 26 Step portion 27 Seal ring seat

Claims (2)

  The hydraulic oil is stored in an aluminum alloy cylinder (10) having a bottom (9) at the bottom, and a sleeve fitting recess (12) formed on the bottom (9) of the cylinder (10) is placed under the sleeve (11). The outer periphery is fitted, the rod (13) is inserted into the sleeve (11) so as to be slidable in the axial direction, and the cylinder (10) is partitioned into a pressure chamber (14) and a reservoir chamber (15), and the sleeve The pressure chamber (14) and the reservoir chamber (15) communicate with each other via a leak gap (23) formed between the sliding surface of the rod (13) and the rod (13), and the pressure chamber (14) A return spring (17) for urging the rod (13) in the direction of expanding the volume is provided, and a lower portion of the pressure chamber (14) is provided between the fitting surface of the sleeve fitting recess (12) and the sleeve (11). Communicate with the lower part of the reservoir chamber (15) A seal ring (25) that forms a passage (24) and can close the opening of the passage (24) on the pressure chamber (14) side is provided on the inner periphery of the lower portion of the sleeve (11) so as to be slidable in the axial direction The upward movement range of the seal ring (25) is regulated by a step portion (26) formed on the inner periphery of the sleeve (11), and the reservoir chamber of the passage (24) is formed by the seal ring (25). (15) When only the flow of hydraulic oil from the side to the pressure chamber (14) is allowed, and when the seal ring (25) closes the opening of the passage (24) on the pressure chamber (14) side An auto tensioner having a steel seal ring seat (27) in contact with the sleeve fitting recess (12).   The auto tensioner according to claim 1, wherein the seal ring seat (27) is subjected to a surface hardening treatment.

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