JP5282994B2 - Auto tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight and low-cost auto-tensioner. <P>SOLUTION: An operating oil is stored inside a cylinder 10. An underneath outer circumference of a sleeve 11 is fitted into a sleeve fitting depression 12 formed on a bottom 9 of the cylinder 10. A rod 13 is axially inserted slidably into the sleeve 11 to compartment an interior portion of the cylinder 10 into a pressure room 14 and a reservoir room 15. Then, the pressure room 14 and the reservoir room 15 are allowed to communicate with each other via a leak gap 16 formed between sliding surfaces of the rod 13 and sleeve 11. Besides, the pressure room 14 and the reservoir room 15 are allowed to communicate with each other via a pathway 17 provided with a seal ring 18 which allows only a flow of the operating oil from the reservoir room 15 to the pressure room 14. A spring seat 23 is fixed to an upper extremity of the rod 13. Further, a return spring 29 is provided which energizes the spring seat 23 in a direction to increase the pressure room 14 in volume. In the auto-tensioner 6 thus structured, at least either the cylinder 10 or the spring seat 23 is made of thermosetting resin. <P>COPYRIGHT: (C)2009,JPO&amp;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 built into this tension adjusting device, hydraulic oil is stored in a cylinder having a bottom at the bottom, a sleeve is fixed coaxially with the cylinder in the cylinder, and the rod can be slid in the sleeve in the axial direction. The cylinder is divided into a pressure chamber and a reservoir chamber, a spring seat is integrally formed at the upper end of the rod, and the spring seat is urged by a return spring in the direction in which the volume of the pressure chamber increases. Known (Patent Document 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.

  The pressure chamber and the reservoir chamber communicate with each other through a leak gap formed between the sliding surfaces of the rod and the sleeve. 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.

In addition, the pressure chamber and the reservoir chamber communicate with each other through a passage provided with a check valve that allows only the flow of hydraulic oil from the reservoir chamber side to the pressure chamber side, and the rod extends in the direction in which the volume of the pressure chamber increases. Moves, the check valve is opened, and hydraulic oil flows from the reservoir chamber side to the pressure chamber side through the passage. Therefore, the rod moves quickly in the direction in which the volume of the pressure chamber increases.
Special Table 2000-504395

  By the way, in this auto tensioner, the rod and cylinder are formed by aluminum die casting, so the thickness of the rod and cylinder is reduced in order to prevent the hydraulic oil in the pressure chamber from penetrating into the rod and cylinder and leaking outside. It was necessary to increase the size and it was difficult to reduce the weight. In addition, it is difficult to mold a thin and thin product by aluminum die casting, and the cost is high.

  The problem to be solved by the present invention is to provide a light-weight and low-cost auto tensioner.

  In order to solve the above problems, at least one of the cylinder and the spring seat is formed of a thermosetting resin.

  For example, a phenol resin can be adopted as the thermosetting resin. Moreover, an inorganic fiber can be added to the said thermosetting resin, and an inorganic fiber can be added so that 40-60 weight% of inorganic fibers may be contained in this case. As said inorganic fiber, glass fiber is employable, for example.

  Further, the auto tensioner can form at least a spring seat of the cylinder and the spring seat with a thermosetting resin, and can fix the spring seat to the upper end of the rod by insert molding. If the circumferential groove is formed on the outer periphery of the upper end of the rod, the fixing strength of the rod with respect to the spring seat can be increased.

  In addition, the auto tensioner is a cylindrical collar that is slidably in contact with the inner periphery of an annular seal member that is formed of a thermosetting resin at least the spring seat of the cylinder and the spring seat. , And the upper end of the collar can be fixed to the spring seat by insert molding. In this case, if the enlarged diameter portion is formed at the upper end of the collar, the fixing strength of the collar with respect to the spring seat can be increased.

  In the auto tensioner according to the present invention, since at least one of the cylinder and the spring seat is formed of a thermosetting resin, the hydraulic oil does not easily leak through the member. Therefore, the thickness of the member formed with the thermosetting resin can be reduced, and the weight of the auto tensioner can be reduced. Moreover, since it is easy to resin-mold a thin and thin one, this auto tensioner is low in cost.

  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. The cylinder 10 is made of a thermosetting resin to which inorganic fibers are added, and contains 40 to 60% by weight of inorganic fibers. For example, a phenol resin can be used as the thermosetting resin, and a glass fiber can be used as the inorganic fiber.

  In the cylinder 10, a steel 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 steel 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.

  The pressure chamber 14 and the reservoir chamber 15 communicate with each other via a leak gap 16 formed between the sliding surfaces of the sleeve 11 and the rod 13. A passage 17 is provided between the sleeve fitting recess 12 and the fitting surface of the sleeve 11 to communicate the lower part of the pressure chamber 14 and the lower part of the reservoir chamber 15.

  As shown in FIG. 4, a seal ring 18 is slidably provided in the lower inner periphery of the sleeve 11 in the axial direction. The seal ring 18 functions as a check valve that allows only the flow of hydraulic oil from the reservoir chamber 15 side to the pressure chamber 14 side, and when the pressure in the pressure chamber 14 becomes lower than the pressure in the reservoir chamber 15, The pressure chamber 14 side opening of the passage 17 is opened. On the other hand, when the pressure in the pressure chamber 14 becomes higher than the pressure in the reservoir chamber 15, the passage 17 moves downward and the pressure chamber in the passage 17 is moved. The 14 side opening is closed. A coil spring 19 that urges the seal ring 18 downward is incorporated in the sleeve 11.

  As shown in FIG. 2, a circumferentially continuous groove 20 is formed on the lower outer periphery of the rod 13, and a C-shaped ring-shaped retaining ring 21 is fitted into the groove 20. Further, a step portion 22 having a large diameter on the lower side is formed on the inner periphery of the sleeve 11, and the retaining ring 21 is moved to the step portion 22 when the rod 13 moves in the direction of expanding the volume of the pressure chamber 14. The rod 13 is prevented from coming off from the sleeve 11 by the locking.

  A spring seat 23 is fixed to the upper end of the rod 13. The spring seat 23 is made of the same thermosetting resin as that of the cylinder 10, and the spring seat 23 is molded (insert molding) in a state where the upper end of the rod 13 is set in the molding die of the spring seat 23, whereby the rod 13 The top of the is fixed.

  An annular seal member 24 is attached to the inner periphery of the upper end of the cylinder 10. The seal member 24 is in sliding contact with the outer periphery of a cylindrical collar 25 fixed to the spring seat 23 and seals the hydraulic oil in the cylinder 10. The collar 25 is fixed to the spring seat 23 by molding the spring seat 23 (insert molding) with the upper end of the collar 25 set in the molding die of the spring seat 23.

  The spring seat 23 is integrally formed with a cylindrical dust cover 26 facing the upper outer periphery of the cylinder 10.

  As shown in FIG. 3, a circumferential groove 27 is formed on the outer periphery of the upper end of the rod 13. Further, an enlarged diameter portion 28 is formed at the upper end of the collar 25.

  As shown in FIG. 2, a return spring 29 is incorporated between the spring seat 23 and the bottom 9 of the cylinder 10, and the return spring 29 is attached with the spring seat 23 in the direction of increasing the volume of the pressure chamber 14. It is fast. As shown in FIG. 4, the lower end of the return spring 29 is supported by an annular spring receiver 30, and the spring receiver 30 is supported by a step portion 31 formed on the outer periphery of the sleeve 11 and having a large diameter on the lower side. Has been.

  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 via the tension pulley 2, the pulley arm 3, and the spring seat 23, 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 16 from the pressure chamber 14 side to the reservoir chamber 15 side, whereby the rod 13 moves downward and the belt 1. The tension pulley 2 moves to a position where the tension of the return spring 29 and the biasing force of the return spring 29 are balanced, and the tension of the belt 1 is absorbed. At this time, since the flow rate of the hydraulic oil flowing through the leak gap 16 is limited and a damper action occurs, the tension pulley 2 moves slowly and keeps the tension of the belt 1 stable. Further, as shown in FIG. 4, because the seal ring 18 closes the opening of the passage 17 on the pressure chamber 14 side due to the pressure difference between the pressure chamber 14 and the reservoir chamber 15, the hydraulic oil does not flow through the passage 17.

  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 29 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 18 opens the opening on the pressure chamber 14 side of the passage 17 due to the pressure difference between the pressure chamber 14 and the reservoir chamber 15, as shown in FIG. Then, the hydraulic oil flows through the passage 17 from the reservoir chamber 15 side to the pressure chamber 14 side. Therefore, the tension pulley 2 quickly moves to a position where the tension of the belt 1 and the biasing force of the return spring 29 are balanced, and quickly absorbs the slack of the belt 1.

  In the auto tensioner 6, the cylinder 10 and the spring seat 23 are formed of a thermosetting resin, so that hydraulic oil permeation leakage through the cylinder 10 and hydraulic oil permeation leakage through the spring seat 23 are unlikely to occur. Therefore, the thickness of the cylinder 10 and the thickness of the spring seat 23 can be reduced, and the weight of the auto tensioner 6 can be reduced.

  In addition, the thin cylinder 10 and the thin spring seat 23 of the dust cover 26 are resin-molded when the thin cylinder 10 and the thin spring seat 23 of the dust cover 26 are formed by aluminum die casting. It is easy compared with. Therefore, this auto tensioner 6 is low cost.

  Further, in the auto tensioner 6, since the cylinder 10 is made of a thermosetting resin, a difference in thermal expansion hardly occurs between the cylinder 10 and the sleeve 11 when the ambient temperature rises. Therefore, the fitting state of the sleeve fitting recess 12 and the sleeve 11 is maintained even at a high temperature, and the sleeve 11 can be reliably prevented from coming off from the sleeve fitting recess 12.

  Further, in the auto tensioner 6, since the spring seat 23 is made of a thermosetting resin, a difference in thermal expansion hardly occurs between the spring seat 23 and the rod 13 when the ambient temperature rises. Therefore, the fixing of the rod 13 to the spring seat 23 is stable even at high temperatures.

  Further, the auto tensioner 6 has a high fixing strength of the rod 13 because the upper end of the rod 13 is prevented from coming off from the spring seat 23 by the circumferential groove 27 on the outer periphery of the upper end of the rod 13. For this reason, when the belt of the tension adjusting device is cut, the step portion 22 engages the retaining ring 21 and the pulling force is dynamically applied between the spring seat 23 and the rod 13. The rod 13 does not come off and the auto tensioner 6 can be reliably prevented from disassembling.

  In addition, since the upper end of the collar 25 is prevented from coming off from the spring seat 23 by the enlarged diameter portion 28 at the upper end of the collar 25, the fixing strength of the collar 25 is high.

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 cross-sectional view near the upper end of the rod. 2 is an enlarged cross-sectional view near the lower end of the sleeve of FIG. 4 is an enlarged cross-sectional view showing a process in which the rod of FIG. 4 moves in the direction of enlarging the volume of the pressure chamber.

Explanation of symbols

6 Auto tensioner 9 Bottom 10 Cylinder 11 Sleeve 12 Sleeve fitting recess 13 Rod 14 Pressure chamber 15 Reservoir chamber 16 Leakage gap 17 Passage 18 Seal ring 23 Spring seat 24 Seal member 25 Collar 27 Circumferential groove 29 Return spring

Claims (6)

Hydraulic oil is stored in a cylinder (10) having a bottom (9) at the bottom, and the lower outer periphery of the sleeve (11) is fitted into a sleeve fitting recess (12) formed on the bottom (9) of the cylinder (10). The rod (13) is slidably inserted in the sleeve (11) in the axial direction to divide the cylinder (10) into a pressure chamber (14) and a reservoir chamber (15), and the rod (13) The pressure chamber (14) communicates with the reservoir chamber (15) through a leak gap (16) formed between the sliding surfaces of the sleeve (11), and the pressure chamber (14) is connected from the reservoir chamber (15) side. The pressure chamber (14) and the reservoir chamber (15) communicate with each other via a passage (17) provided with a check valve (18) that allows only the flow of hydraulic oil to the The spring seat (23) is fixed to the upper end, and the spring seat ( In 3) the pressure chamber (14) autotensioner volume provided a return spring (29) which biases the expansion (6),
Of the annular seal member (24), at least the spring seat (23) of the cylinder (10) and the spring seat (23) is formed of a thermosetting resin and attached to the inner periphery of the upper end of the cylinder (10). An auto tensioner provided with a cylindrical collar (25) slidably in contact with the periphery, and the upper end of the collar (25) being fixed to the spring seat (23) by insert molding. The auto tensioner according to claim 1 , wherein an enlarged diameter portion is formed at an upper end of the collar (25). The auto tensioner according to claim 1 or 2 , wherein the thermosetting resin is a phenol resin. The auto tensioner according to any one of claims 1 to 3 , wherein inorganic fibers are added to the thermosetting resin. The auto tensioner according to claim 4 , wherein the thermosetting resin contains 40 to 60% by weight of the inorganic fiber. The autotensioner according to claim 4 or 5 , wherein the inorganic fibers are glass fibers.

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