JP2007016945A - Auto tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily control resistance of a throttle of an auto tensioner, and to improve reliability in operation of a rod. <P>SOLUTION: In this auto tensioner 4 wherein a piston 12 formed on an end portion of a rod 11 is slidably inserted into a sleeve 9, hydraulic oil is charged in a pressure chamber 14 in the sleeve 9, and stored in a reservoir chamber 15 formed between the cylinder 10 and the sleeve 9, a first passage 18 is formed to communicate the pressure chamber 14 and the reservoir chamber 15, a first check valve 19 is mounted in the first passage 18 to permit only the flow from a reservoir chamber 15 side to a pressure chamber 14 side, a second passage 20 is formed to communicate the pressure chamber 14 and the reservoir chamber 15, a second check valve 21 is mounted in the second passage 20 to permit only the flow from the pressure chamber 14 side to the reservoir chamber 15 side, the throttle is mounted in the second passage 20, and a return spring 17 is mounted to energize the rod 11 and the cylinder 10, a column member 26 provided with a plurality of through holes 25 from one end to the other end, is press fitted to the second passage 20, and the throttle is composed of the through holes 25 of the column member 26. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  An auxiliary machine of an automobile, such as a car air conditioner or a water pump, has a rotating shaft connected to a crankshaft of the engine by a belt, and is driven by the engine via the belt. In order to maintain the belt tension within an appropriate range, a rotatable tension pulley that contacts the belt, a swingable pulley arm that supports the tension pulley, and a pulley arm in a direction in which the tension pulley presses the belt are generally attached. An auto tensioner unit consisting of an active auto tensioner is used.

  As an auto tensioner used in such an auto tensioner unit, a piston formed at the bottom of a rod is slidably inserted into a sleeve fixed in the cylinder, and the rod and cylinder expand the volume of the pressure chamber in the sleeve. The thing biased with the return spring in the direction to make is 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.

  Further, the hydraulic oil is filled in the pressure chamber in the sleeve divided by the piston, and the hydraulic oil is also stored in the reservoir chamber formed between the sleeve and the cylinder. The lower part of the pressure chamber and the lower part of the reservoir chamber communicate with each other through the first passage. When the rod moves and the volume of the pressure chamber increases, the hydraulic oil in the reservoir chamber flows into the pressure chamber through the first passage. The rod also has a second passage communicating with the pressure chamber and the reservoir chamber. When the rod moves and the volume of the pressure chamber is reduced, the hydraulic oil in the pressure chamber passes through the second passage into the reservoir chamber. Flowing. The second passage is provided with an orifice, which restricts the flow rate of the hydraulic oil flowing from the pressure chamber to the reservoir chamber, thereby stabilizing the belt tension by allowing the rod to move slowly. .

  However, since the orifice diameter is generally as small as 0.1 to 0.2 mm, it is difficult to process and the hole diameter is likely to vary. Therefore, it has been difficult to manage the resistance of the orifice.

  In addition, since the orifice has a small hole diameter, foreign matter (for example, wear powder) contained in the hydraulic oil in the pressure chamber tends to be clogged. If the orifice is clogged with foreign matter, the rod will not move even if the belt tension increases, and the load on the belt will be excessive.

JP-A-2005-090724

  The problem to be solved by the present invention is to facilitate the management of the aperture resistance and improve the reliability of the rod operation.

  In order to solve the above-described problem, a cylindrical member in which a plurality of through holes extending from one end to the other end is press-fitted into the second passage, and a restriction is formed by the plurality of through holes of the cylindrical member. An auto tensioner employing this configuration can form a diaphragm having the same resistance as that of an orifice having a small cross-sectional dimension by increasing the length of the through hole of the cylindrical member as compared with the cross-sectional dimension.

This autotensioner becomes more preferable when the following configuration is added.
1) A step portion having a large diameter on the pressure chamber side is formed in the second passage, and the columnar member is press-fitted to the pressure chamber side from the step portion.
2) Provide an electromagnetic coil that keeps the second check valve closed when energized.

  The auto tensioner according to the present invention can easily manage the resistance of the diaphragm by managing the length of the through hole formed in the cylindrical member. In addition, since there are a plurality of through-holes constituting the throttle, even if any of the through-holes is clogged with foreign matter, hydraulic oil can flow through the other through-holes. Therefore, the operation reliability of the rod is high.

  Further, a step portion having a large diameter on the pressure chamber side is formed in the second passage, and the cylindrical member is press-fitted on the pressure chamber side than the step portion, since the cross-sectional area of the column member is large, It is easy to form a plurality of through holes, and processability is excellent.

  In addition, an electromagnetic coil that keeps the closed state of the second check valve by energization prevents the hydraulic oil from flowing from the pressure chamber to the reservoir chamber by energizing the electromagnetic coil. It is possible to temporarily prevent the rod from moving in the direction in which the volume decreases.

  Embodiments of an auto tensioner according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, a tension pulley 1 is rotatably attached to a pulley arm 2, and the pulley arm 2 is supported so as to be swingable about a support shaft 3. An auto tensioner 4 is connected to the pulley arm 2, and the auto tensioner 4 biases the pulley arm 2 in a direction in which the tension pulley 1 presses the belt 5.

  As shown in FIG. 2, the belt 5 connects the engine 6, the motor generator 7, and the auxiliary machine 8, and the tension pulley 1 presses the belt 5 at a position between the engine 6 and the motor generator 7.

  In the auto tensioner 4, as shown in FIG. 3, a sleeve 9 is inserted and fixed in a cylinder 10, and a piston 12 formed below the rod 11 is slidably inserted into the sleeve 9. A stop ring 13 is mounted in the sleeve 9 above the piston 12, and the stop ring 13 prevents the piston 12 from coming out of the sleeve 9. The pressure chamber 14 formed in the sleeve 9 by the piston 12 is filled with hydraulic oil. Further, hydraulic oil is also stored in a reservoir chamber 15 formed between the sleeve 9 and the cylinder 10.

  A spring seat 16 is fixed to the upper portion of the rod 11, and a return spring 17 is incorporated between the spring seat 16 and the cylinder 10. The return spring 17 urges the rod 11 and the cylinder 10 in the direction in which the volume of the pressure chamber 14 increases.

  The lower portion of the pressure chamber 14 and the lower portion of the reservoir chamber 15 communicate with each other via a first passage 18 formed in the cylinder 10, and this first passage 18 is connected to the pressure chamber 14 side from the reservoir chamber 15 side. A first check valve 19 that allows only flow is provided. The first check valve 19 includes a valve seat 19a fixed to the lower portion of the pressure chamber 14, a spherical valve body 19c that opens and closes a valve hole 19b formed in the valve seat 19a, and a stopper that limits the movement range of the valve body 19c. 19d.

  The rod 11 and the spring seat 16 are formed with a second passage 20 that communicates the upper portion of the pressure chamber 14 and the upper portion of the reservoir chamber 15. The second passage 20 includes a valve seat 21 a and a valve seat 21 a. A second check valve 21 including a valve body 21c supported so as to be able to advance and retract toward the formed valve hole 21b and a spring 21d that urges the valve body 21c toward the valve hole 21b is provided. As shown in FIG. 4, the second check valve only allows the flow from the pressure chamber 14 side to the reservoir chamber 15 side. As shown in FIG. 3, an electromagnetic coil 22 is mounted on the valve body 21c, and when the electromagnetic coil 22 is energized, the valve body 21c is pressed toward the valve hole 21b to maintain the closed state of the valve hole 21b. It is like that.

  The opening between the spring seat 16 and the cylinder 10 is closed with an expandable / contractible bellows 23, thereby preventing the hydraulic oil in the reservoir chamber 15 from leaking to the outside.

  In the second passage 20 of the rod 11, a step portion 24 having a large diameter on the pressure chamber 14 side is formed as shown in FIG. A cylindrical member 26 having a plurality of through holes 25 formed from one end to the other end is press-fitted to the pressure chamber 14 side of the step portion 24 of the second passage 20, and the through hole 25 of the cylindrical member 26 is formed as shown in FIG. As shown in FIG. 2, the aperture of the second passage 20 is configured.

  As shown in FIG. 3, a bush mounting hole 27 is formed in the upper part of the spring seat 16. A bush 28 is press-fitted into the bush mounting hole 27, and an inner ring 29 is rotatably inserted into the bush 28. Yes. The inner ring 29 is fixed to an engine block (not shown) with bolts 30 as shown in FIG. 1, and supports the auto tensioner 4 in a swingable manner.

  As shown in FIG. 3, a bush mounting hole 31 is also formed in the lower portion of the cylinder 10, a bush 32 is press-fitted into the bush mounting hole 31, and an inner ring 33 is rotatably inserted into the bush 32. . As shown in FIG. 1, the inner ring 33 is fixed to the pulley arm 2 with a bolt 34 to connect the auto tensioner 4 and the pulley arm 2 so as to be relatively rotatable.

  Next, the operation of the above-described auto tensioner 4 will be described.

  During normal running, the auxiliary machine 8 is driven by the engine 6 via the belt 5 as shown in FIG. At this time, when the load of the auxiliary machine 8 fluctuates and the tension of the belt 5 increases, the tension is transmitted to the auto tensioner 4 via the pulley arm 2 and the pressure in the pressure chamber 14 increases. When the pressure in the pressure chamber 14 increases, the valve body 21c of the second check valve 21 is separated from the valve seat 21a to open the valve hole 21b, and the hydraulic oil in the pressure chamber 14 passes through the second passage 20 to reach the reservoir chamber. To 15 The piston 12 in the sleeve 9 is moved by the outflow of the hydraulic oil, and the tension pulley 1 is moved to a position where the tension of the belt 5 and the urging force of the return spring 17 are balanced, thereby relaxing the tension of the belt 5. At this time, since the flow rate of the hydraulic oil is restricted by the through hole 25, the tension pulley 1 moves slowly. Therefore, the tension of the belt 5 is unlikely to become unstable.

  Further, when the load of the auxiliary machine 8 fluctuates and the tension of the belt 5 decreases, the pressure in the pressure chamber 14 decreases due to the urging force of the return spring 17. When the pressure in the pressure chamber 14 becomes low, the valve body 19c of the first check valve 19 is separated from the valve seat 19a to open the valve hole 19b, so that the hydraulic oil in the reservoir chamber 15 passes through the first passage 18 and the pressure chamber. 14 flows in. The piston 12 in the sleeve 9 is moved by the inflow of the hydraulic oil, and the tension pulley 1 is moved to a position where the tension of the belt 5 and the urging force of the return spring 17 are balanced to absorb the slack of the belt 5. At this time, since the first passage 18 has no restriction, the tension pulley 1 moves quickly and absorbs the slack of the belt 5 quickly.

  As described above, when the tension of the belt 5 at the position of the tension pulley 1 fluctuates, the tension pulley 1 moves to a position where the tension of the belt 5 and the urging force of the return spring 17 are balanced to absorb the tension fluctuation of the belt 5. The tension of the belt 5 is maintained in an appropriate range.

  On the other hand, when the engine 6 is restarted by the motor generator 7 after the engine 6 is temporarily stopped, the electromagnetic coil 22 is energized to keep the second check valve 21 closed as shown in FIG. In this way, since the hydraulic oil in the pressure chamber 14 does not flow into the reservoir chamber 15, the piston 12 in the sleeve 9 does not move, and the position of the tension pulley 1 is fixed. Therefore, the tension state of the belt 5 is maintained, the slip of the belt 5 can be prevented, and the engine can be started stably.

  The auto tensioner 4 can easily manage the resistance of the diaphragm by managing the length of the through hole 25. In addition, since there are a plurality of through holes 25 constituting the throttle, the hydraulic oil flows through the other through holes 25 even if any of the through holes 25 is clogged with foreign matter (for example, wear powder generated by sliding of the piston). Can do. Therefore, the operation reliability of the rod 11 is high.

  Further, since the step portion 24 having a large diameter on the pressure chamber 14 side is formed in the second passage 20 and the cylindrical member 26 is press-fitted to the pressure chamber 14 side than the step portion 24, the cross-sectional area of the column member 26 is large. . Therefore, it is easy to form the through hole 25 and the workability is excellent.

The front view which shows the usage example of the auto tensioner of embodiment of this invention The figure which shows the drive state of the auxiliary machine with the engine Sectional view along the axis of the auto tensioner in FIG. The enlarged view which shows the 2nd check valve of the auto tensioner of FIG. 1 is an exploded perspective view of the aperture of the auto tensioner of FIG. Sectional view along the axis of the iris of the auto tensioner in FIG. The figure which shows the starting state of the engine with the motor generator

Explanation of symbols

9 Sleeve 10 Cylinder 11 Rod 12 Piston 14 Pressure chamber 15 Reservoir chamber 17 Return spring 18 First passage 19 First check valve 20 Second passage 21 Second check valve 22 Electromagnetic coil 24 Step portion 25 Through hole 26 Column member

Claims (3)

  A piston 12 formed at the end of the rod 11 is slidably inserted into a sleeve 9 fixed in the cylinder 10 and filled with hydraulic oil in the pressure chamber 14 in the sleeve 9 whose volume changes as the piston 12 moves. The hydraulic oil is stored in a reservoir chamber 15 formed between the cylinder 10 and the sleeve 9, and a first passage 18 is provided to communicate the pressure chamber 14 and the reservoir chamber 15. A first check valve 19 that allows only a flow from the reservoir chamber 15 side to the pressure chamber 14 side is provided, a second passage 20 that communicates the pressure chamber 14 and the reservoir chamber 15 is provided, and the second passage 20 includes A second check valve 21 that allows only the flow from the pressure chamber 14 side to the reservoir chamber 15 side is provided, a throttle is provided in the second passage 20, and the volume of the pressure chamber 14 is increased. In an auto tensioner provided with a return spring 17 for urging the rod 11 and the cylinder 10, a cylindrical member 26 having a plurality of through holes 25 extending from one end to the other end is press-fitted into the second passage 20, and the cylindrical member 26. The auto tensioner according to claim 26, wherein the throttling is constituted by 26 of the plurality of through holes 25.   The auto tensioner according to claim 1, wherein a step portion 24 having a large diameter on the pressure chamber 14 side is formed in the second passage 20, and the cylindrical member 26 is press-fitted to the pressure chamber 14 side from the step portion 24. .   The auto tensioner according to claim 1 or 2, further comprising an electromagnetic coil 22 that holds the closed state of the second check valve 21 when energized.

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