JP2007010130A - Hydraulic auto tensioner and tension adjusting device for belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic auto tensioner capable of always obtaining stable hydraulic damper force. <P>SOLUTION: A return spring 20 is assembled between a spring seat 17 provided in an upper part of a rod 15 and an inner bottom face of a cylinder 11. A check valve 26 is provided in a first passage 25 for communicating a reservoir chamber 24 and a pressure chamber 16 mutually. A second passage 35 for communicating the pressure chamber 16 and the reservoir chamber 24 mutually is formed in the rod 15, and a restriction 38 is provided in the second passage 35. Hydraulic damper force is generated by flow resistance when hydraulic fluid in the pressure chamber 16 circulates in the restriction 38 to buffer pressing-in force loaded on the rod 15. A hydraulic damper is stabilized without affecting the restriction 38 at all even when the cylinder 11 and the rod 15 are relatively inclined. A retaining ring 43 is attached to the inner periphery of an opening end part of the valve sleeve 14 to prevent the piston 15a from coming off and prevent the rod 15 from being dismantled from the valve sleeve 14 in a condition before assembling. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydraulic auto tensioner that maintains a constant tension of a timing belt for driving a camshaft and a belt for driving an auxiliary machine, and a belt tension adjusting device using the hydraulic auto tensioner.

  As a hydraulic auto-tensioner that keeps the tension of an auxiliary machine driving belt for driving an auxiliary machine such as an alternator, an air conditioner compressor, or a water pump constant, the one described in Patent Document 1 has been conventionally known. Yes.

  In the above hydraulic auto tensioner, a valve sleeve rising from the inner bottom surface is provided inside the cylinder closed at the lower part, and the lower end of the rod is slidably inserted into the valve sleeve, and the pressure chamber is inserted into the valve sleeve. And a return spring is incorporated between a spring seat provided on the upper portion of the rod and the inner bottom surface of the cylinder to urge the rod and the cylinder in a relatively extending direction. Further, one end portion is fitted to the outer periphery of the spring seat, and the other end portion is closed to the upper outer periphery of the cylinder to close the upper opening of the cylinder to form a reservoir chamber between the cylinder and the valve sleeve, A check valve is provided in a first passage communicating the reservoir chamber and the pressure chamber.

  In the hydraulic auto tensioner, the connecting piece provided at the lower end of the cylinder is connected to the engine block so as to be rotatable, and the connecting piece provided on the spring seat is connected to the swingable pulley arm so as to be rotatable. The adjustment force of the hydraulic auto tensioner is applied to the pulley arm, and the tension pulley supported by the pulley arm is pressed against the belt.

When the pushing force is applied to the rod from the belt via the tension pulley and the pulley arm, the first passage is closed by the check valve, and the hydraulic oil in the pressure chamber is formed between the sliding surface of the valve sleeve and the rod. A hydraulic damper force is generated by a flow resistance when flowing from a small leak clearance into the reservoir chamber to absorb a change in belt tension.
US Pat. No. 4,790,801

  By the way, in the conventional hydraulic auto tensioner, when the pulley arm swings due to a change in belt tension, the hydraulic auto tensioner itself swings, and a moment load is generated in the connecting piece of the cylinder and the connecting piece of the spring seat. The moment load is received by the valve sleeve and the rod. At this time, since the valve sleeve and the rod are relatively inclined, the size of the leak clearance formed between the sliding surfaces of the valve sleeve and the rod becomes uneven in the circumferential direction, and the flow of hydraulic oil flowing through the leak clearance The resistance changes, and a stable hydraulic damper force cannot be obtained.

  Further, when an excessive pushing force is applied to the rod and the pressure in the pressure chamber suddenly increases, the valve sleeve may expand and deform. At this time, since the leak clearance formed between the sliding surfaces of the valve sleeve and the rod changes, a stable hydraulic damper force cannot be obtained as described above.

  An object of the present invention is to provide a hydraulic auto tensioner capable of always obtaining a stable hydraulic damper force and a belt tension adjusting device using the hydraulic auto tensioner.

  In order to solve the above-described problems, in the hydraulic auto tensioner according to the present invention, a valve sleeve rising from the inner bottom surface is provided in a cylinder having a closed end at a lower portion, and the lower end portion of the rod is slid into the valve sleeve. A return spring is formed that is movably inserted to form a pressure chamber in the valve sleeve, and that urges the cylinder and the rod in a relatively extending direction between a spring seat provided at the top of the rod and the inner bottom surface of the cylinder. Built-in, the upper end of the cylinder is closed by an extendable bellows with one end fixed to the outer periphery of the spring seat and the other end fixed to the upper outer periphery of the cylinder to form a reservoir chamber between the cylinder and the valve sleeve. When the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber, the first passage communicating the lower portion of the reservoir chamber and the lower portion of the pressure chamber In a hydraulic auto tensioner provided with a check valve for closing a passage, the rod is slidable within the valve sleeve, a small-diameter shaft portion provided on an upper end surface of the piston, and an upper end of the small-diameter shaft portion A large-diameter shaft portion provided on the rod, and a seal member seals between the sliding surfaces of the piston and the valve sleeve, and a second passage communicating the pressure chamber and the reservoir chamber is provided at the lower end portion of the rod. Formed, a throttle is provided in the second passage, an engagement groove is formed on the inner periphery of the opening end of the valve sleeve, and a retaining ring is attached to the engagement groove to prevent the piston from coming out of the valve sleeve. The configuration was adopted.

  Here, if the cross-sectional shape of the retaining ring is a square, the retaining ring does not shrink even when an axial load is applied from the piston, so that the piston can be securely retained and the spring force as a return spring can be secured. Can be used.

When the length from the lower surface of the spring seat to the lower surface of the large-diameter shaft portion is L ₁ and the length from the upper end of the valve sleeve to the engagement groove is L ₂ , L ₁ > L ₂ and the small diameter Adopting a configuration in which the outer diameter of the shaft portion is smaller than the inner diameter of the retaining ring in the state where the outer diameter of the retaining ring is matched with the inner diameter of the valve sleeve, and a tapered surface is formed on the inner periphery of the opening end of the valve sleeve. By fitting a retaining ring to the small diameter shaft part, inserting a piston into the valve sleeve and pushing the rod, the retaining ring is pushed by the lower surface of the large diameter shaft part and contracted by contact with the tapered surface. When it is pushed into the valve sleeve and pushed to the position facing the engagement groove, the diameter is expanded by the restoring elasticity and engaged with the engagement groove, so that the retaining ring can be easily attached without using a tool.

  In the belt tension adjusting device according to the present invention, a tension pulley is rotatably provided at the swinging side end of a pulley arm that is swingably supported by a fixed member, and the adjustment force of the hydraulic auto tensioner is applied to the pulley arm. A configuration was adopted in which the pulley arm was biased in the direction in which the tension pulley pressed the belt under load.

  In the belt tension adjusting device having the above-described configuration, the hydraulic auto tensioner may be configured such that the spring seat is rotatably connected to the pulley arm and the closed end of the cylinder is rotatably connected to the fixing member. Alternatively, the spring seat may be rotatably connected to the fixed member, and the closed end of the cylinder may be rotatably connected to the pulley arm.

  As described above, in the hydraulic auto tensioner, a second passage that connects the pressure chamber and the reservoir chamber is formed at the lower end of the rod, and a throttle is provided in the second passage, so that the hydraulic oil in the pressure chamber Since the hydraulic damper force is generated by the flow resistance when flowing into the reservoir chamber, the cylinder and the rod are relatively inclined due to moment load, etc., or the pressure in the pressure chamber suddenly increases and the valve sleeve Even if it expands and deforms, the throttle that generates the hydraulic damper force is not affected at all. As a result, a stable hydraulic damper effect can be obtained at all times.

  In addition, an engagement groove is formed in the opening end of the valve sleeve, and a retaining ring is attached to the engagement groove to prevent the piston from coming off, so that the rod is disassembled from the valve sleeve before the hydraulic auto tensioner is assembled. Can be prevented.

  The adjustment force of the hydraulic auto tensioner as described above is applied to the swingable pulley arm, and the tension pulley provided at the swing side end of the pulley arm is pressed against the belt, whereby the belt is driven by the hydraulic auto tensioner. Thus, the belt tension can be absorbed smoothly, and the belt tension can always be maintained at an appropriate level.

  Here, the spring seat of the hydraulic auto tensioner is rotatably connected to the fixed member, and the closed end of the cylinder is rotatably connected to the pulley arm, so that the hydraulic auto tensioner is disposed outside the belt. Because of the layout, the belt does not interfere with the assembly of the hydraulic auto tensioner, and the hydraulic auto tensioner can be easily assembled.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a belt tension adjusting device. As shown in the figure, the pulley arm 1 is swingably supported around a fulcrum shaft 2 supported by a fixed member such as an engine block, and a tension pulley 3 is rotatably supported at the end of the swing side. . A hydraulic auto tensioner 10 is connected to the pulley arm 1 between the fulcrum shaft 2 and the tension pulley 3.

  The pulley arm 1 is disposed inside the belt 4 and is urged in a direction in which the tension pulley 3 presses the inner surface of the belt 4 by an adjusting force loaded from the hydraulic auto tensioner 10.

  As shown in FIG. 2, the hydraulic auto tensioner 10 has a cylinder 11 made of an aluminum alloy. The cylinder 11 has a closed end at a lower portion, and a connecting piece 12 that is rotatably attached to a fixing member such as an engine block is provided at the closed end.

  A sleeve fitting hole 13 is formed in the inner bottom surface of the cylinder 11, and a lower end portion of a steel valve sleeve 14 is press-fitted into the sleeve fitting hole 13. A rod 15 having a lower end inserted into the valve sleeve 14 includes a piston 15a slidable within the valve sleeve 14, a small-diameter shaft portion 15b provided on the upper end surface of the piston 15a, and a small-diameter shaft portion 15b. The pressure chamber 16 is formed in the valve sleeve 14 by incorporating the piston 15a into the valve sleeve 14 and comprising a large-diameter shaft portion 15c provided at the upper end.

  The large-diameter shaft portion 15 c at the upper end of the rod 15 has an outer diameter that can be inserted into the valve sleeve 14. A spring seat 17 is attached to the upper portion of the large-diameter shaft portion 15 c, and a return spring 20 is assembled between the spring seat 17 and the inner bottom surface of the cylinder 11. The return spring 20 presses the cylinder 11 and the rod 15 in opposite directions so as to move relative to each other in the direction in which the cylinder 11 and the rod 15 extend.

  A connecting piece 21 is provided at the upper end of the spring seat 17 so as to be rotatably connected to the pulley arm 1. A cylindrical body 22 that covers the upper portion of the return spring 20 is provided on the outer peripheral portion of the lower surface of the spring seat 17, and one end of an extendable bellows 23 made of an elastic body such as rubber is fitted to the outside of the cylindrical body 22. It has been fixed. Further, the other end of the bellows 23 is fitted and fixed to the upper outer periphery of the cylinder 11, and the upper opening of the cylinder 11 is closed by the attachment of the bellows 23, so that the inner diameter surface of the cylinder 11 and the outer diameter surface of the valve sleeve 14 are closed. A reservoir chamber 24 is formed therebetween.

  A first passage 25 that connects the pressure chamber 16 and the reservoir chamber 24 is formed between the sleeve fitting hole 13 of the cylinder 11 and the fitting surface of the lower end portion of the valve sleeve 14, and a check for opening and closing the first passage 25 is performed. A valve 26 is incorporated in the lower end of the valve sleeve 14.

  The check valve 26 includes a valve seat 27 having a valve hole 28, a spherical valve body 29 that opens and closes the valve hole 28 of the valve seat 27, and a retainer 30 that limits the opening and closing amount of the valve body 29.

  The retainer 30 has a cap shape, and a flange 31 is formed outwardly at the opening end. The flange 31 abuts on the upper surface of the valve seat 27 by press-fitting the retainer 30 with respect to the protrusion 32 formed on the upper surface of the valve seat 27. Further, the check valve 26 is made an assembly by press-fitting the retainer 30. The check valve 26 is attached by press-fitting into a valve fitting recess 33 formed at the lower end portion of the valve sleeve 14, and the flange 31 of the retainer 30 is formed on the inner periphery of the lower end portion of the valve sleeve 14 by the valve seat 27 by the attachment. Pressed against the shoulder 34.

  The check valve 26 closes the first passage 25 when the pressure in the pressure chamber 16 becomes higher than the pressure in the reservoir chamber 24.

  A second passage 35 communicating with the pressure chamber 16 and the reservoir chamber 24 is formed at the lower end of the rod 15. A fitting recess 36 is formed at the end of the second passage 35 on the pressure chamber 16 side, and a throttle member 37 is press-fitted into the fitting recess 36. The throttle member 37 is made of a metal such as iron or a synthetic resin, and the throttle member 37 is provided with a throttle 38 having a diameter smaller than that of the second passage 35.

  Since the throttle 38 generates a hydraulic damper force by the flow resistance when the hydraulic oil in the pressure chamber 16 flows, if the inner diameter is less than 0.1 mm, the flow resistance of the hydraulic oil becomes too large and the cylinder 11 The relative movement in the direction in which the rod 15 contracts is hindered, and the belt 4 becomes over-tensioned. On the other hand, when it exceeds 0.5 mm, the hydraulic oil in the pressure chamber 16 flows smoothly into the reservoir chamber 24 and the hydraulic damper force cannot be obtained. For this reason, the inner diameter of the diaphragm 38 is in the range of 0.1 to 0.5 mm.

  A seal groove 39 is formed on the outer periphery of the piston 15 a, and a seal member 40 formed of an O-ring incorporated in the seal groove 39 is in elastic contact with the inner diameter surface of the valve sleeve 14, so that the piston 15 a and the valve sleeve 14 slide. Seals between the faces.

  A retaining means 41 is provided in the upper opening of the valve sleeve 14 to restrict the relative movement of the rod 15 and the valve sleeve 14 in the extending direction and prevent the lower end of the rod 15 from slipping out of the valve sleeve 14. Yes.

  The retaining means 41 is formed with an engaging groove 42 in the upper end opening of the valve sleeve 14, and a retaining ring 43 that is elastically deformed in the radial direction by cutting a part in the circumferential direction is attached to the engaging groove 42. The rod 15 is prevented from coming off by contact of the upper surface of the piston 15a with the retaining ring 43.

Here, the retaining ring 43 has a square cross section. The retaining ring 43 needs to be attached to the engaging groove 42 after the return spring 20 is assembled, and it is difficult to attach the retaining ring 43 using a tool from the outside. In order to facilitate the assembly of the retaining ring 43, the length L ₁ from the lower surface of the spring seat 17 to the lower surface of the large-diameter shaft portion 15 c is engaged from the upper end surface of the valve sleeve 14 as shown in FIG. In a state where the length to the groove 42 is longer than the length L ₂ (L ₁ > L ₂ ), and the outer diameter D ₁ of the small-diameter shaft portion 15b of the rod 15 is matched with the inner diameter of the valve sleeve 14 The diameter of the retaining ring 43 is smaller than the inner diameter of the retaining ring 43. Further, a tapered surface 44 is provided on the inner periphery of the opening end of the valve sleeve 14, and the retaining ring 43 is attached to the small-diameter shaft portion 15b of the rod 15 (FIG. 3 (I )), The retaining ring 43 is pushed into the valve sleeve 14 on the lower surface of the large-diameter shaft portion 15c.

  When the retaining ring 43 is pushed in, the retaining ring 43 is reduced in diameter by contact with the tapered surface 44 and enters the valve sleeve 14 and faces the engaging groove 42 as shown in FIG. 3 (II). When pushed in, the retaining ring 43 expands in diameter due to its own restoring elasticity and engages with the engaging groove 42 as shown in FIG. For this reason, the retaining ring 43 can be easily attached without using a tool.

  The belt tension adjusting device shown in the embodiment has the above-described structure, and when the auxiliary machine is driven by the movement of the belt 4, the tension of the belt 4 changes due to the load fluctuation of the auxiliary machine. Is weakened, the cylinder 11 and the rod 15 are moved relative to each other by the pressing force of the return spring 20, the pulley arm 1 is swung by the relative movement, and the tension pulley 3 is pressed against the belt 4 to loosen the belt 4. Absorbs.

  When the cylinder 11 and the rod 15 move relative to each other in the extending direction, the pressure in the pressure chamber 16 is lower than the pressure in the reservoir chamber 24, so the check valve 26 opens the first passage 25. For this reason, the hydraulic oil in the reservoir chamber 24 flows smoothly from the first passage 25 into the pressure chamber 16, and the cylinder 11 and the rod 15 smoothly move relative to each other in the extending direction to immediately absorb the slack of the belt 4.

  On the other hand, when the tension of the belt 4 is increased, a pushing force is applied to the rod 15 via the tension pulley 3 and the pulley arm 1. At this time, since the pressure in the pressure chamber 16 becomes higher than the pressure in the reservoir chamber 24, the check valve 26 closes the first passage 25. Further, the hydraulic oil in the pressure chamber 16 flows into the throttle 38 and the second passage 35 and flows into the reservoir chamber 24, and a hydraulic damper force is generated by the flow resistance of the hydraulic oil flowing through the throttle 38. The pushing force applied to the rod 15 is buffered by the hydraulic damper force, and the cylinder 11 and the rod 15 are contracted to a position where the pushing force applied to the rod 15 and the pushing force of the return spring 20 are balanced. Slowly move relative.

  When the cylinder 11 and the rod 15 move relative to each other in the contracting direction, the hydraulic auto tensioner 10 swings about a connecting piece 12 connected to a fixing member such as an engine block. At the time of swinging, even if a moment load is applied to the connecting pieces 12 and 21 of the spring seat 17 provided on the cylinder 11 and the rod 15 and the cylinder 11 and the rod 15 are inclined relatively, a hydraulic damper force is generated. Since the diaphragm 38 to be moved is provided at the lower end portion of the rod 15, nothing is affected. Further, even if the pressure in the pressure chamber 16 increases and the valve sleeve 14 expands and deforms, the throttle 38 is not affected at all. For this reason, a stable hydraulic damper effect can be obtained at all times, and the belt 4 can always be maintained at an appropriate tension.

  Further, by setting the inner diameter of the throttle 38 in the range of 0.1 to 0.5 mm, an optimal hydraulic damper force can be generated.

  Further, an engagement groove 42 is formed on the inner periphery of the opening end of the valve sleeve 14, and the piston 15a is prevented from coming off by a retaining ring 43 attached to the engagement groove 42, so that the hydraulic auto tensioner can be assembled. It is possible to prevent the rod 15 from being disassembled from the valve sleeve 14 at this stage.

  Further, by making the cross-sectional shape of the retaining ring 43 square, the retaining ring 43 is not reduced in diameter by the pressing force applied from the piston 15a, and the retaining ring 43 can reliably prevent the piston 15a from coming off. The return spring 20 can have a large spring elasticity.

  Further, the retaining ring 43 can be attached to the engaging groove 42 by pushing the rod 15 into the valve sleeve 14 with the retaining ring 43 fitted to the small-diameter shaft portion 15 b of the rod 15. The retaining ring 43 can be easily attached without using a tool.

  FIG. 4 shows another embodiment of the belt tension adjusting device. In this embodiment, a pulley arm 1 that can swing around a fulcrum shaft 2 supported by a fixed member such as an engine block is provided outside the belt 4, and the closed end of the cylinder 11 of the hydraulic auto tensioner 10 is provided on the pulley arm 1. The connecting piece 12 provided in the part is connected rotatably, and the connecting piece 21 of the spring seat 17 provided on the upper portion of the rod 15 is connected rotatably to a fixing member such as an engine block.

  As described above, by connecting the connecting piece 12 provided at the closed end of the cylinder 11 of the hydraulic auto tensioner 10 to the pulley arm 1 and connecting the connecting piece 21 of the spring seat 17 to the fixing member, Since the tensioner 10 has a layout arranged outside the belt 4, there is no inconvenience that the belt 4 interferes with the assembly of the hydraulic auto tensioner 10, and the hydraulic auto tensioner 10 can be easily assembled. .

Front view of a belt tension adjusting device employing a hydraulic auto tensioner according to the present invention. 1 is a longitudinal front view of the hydraulic auto tensioner shown in FIG. (I) is a sectional view showing a state before the retaining ring is assembled, (II) is a sectional view showing a state where the retaining ring is being assembled, and (III) is a sectional view showing a state where the retaining ring has been assembled. Front view showing another embodiment of belt tension adjusting device

Explanation of symbols

1 Pulley arm 3 Tension pulley 4 Belt 10 Hydraulic auto tensioner 11 Cylinder 14 Valve sleeve 15 Rod 15a Piston 15b Small diameter shaft portion 15c Large diameter shaft portion 16 Pressure chamber 17 Spring seat 20 Return spring 23 Bellows 24 Reservoir chamber 25 First passage 26 Check Valve 35 Second passage 40 Seal member 42 Engaging groove 43 Retaining ring 44 Tapered surface

Claims (6)

  A valve sleeve rising from the inner bottom surface is provided in a cylinder having a closed end at the bottom, and the lower end of the rod is slidably inserted into the valve sleeve to form a pressure chamber in the valve sleeve. A return spring that urges the cylinder and rod in a relatively extending direction is installed between the spring seat provided at the top and the inner bottom surface of the cylinder, and one end is fixed to the outer periphery of the spring seat. A first passage that closes the upper opening of the cylinder by an extendable bellows with the other end fixed to form a reservoir chamber between the cylinder and the valve sleeve, and communicates the lower portion of the reservoir chamber and the lower portion of the pressure chamber. In the hydraulic auto tensioner provided with a check valve for closing the first passage when the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber, the rod A piston slidable within the valve sleeve, a small-diameter shaft portion provided on an upper end surface of the piston, and a large-diameter shaft portion provided on an upper end of the small-diameter shaft portion. A seal member seals between the sliding surfaces of the sleeve, and a second passage that communicates the pressure chamber and the reservoir chamber is formed at the lower end portion of the rod. A throttle is provided in the second passage, and the valve sleeve is opened. A hydraulic auto tensioner, wherein an engagement groove is formed on an inner periphery of an end portion, and a retaining ring is attached to the engagement groove to prevent the piston from coming out of the valve sleeve.   The hydraulic auto tensioner according to claim 1, wherein the retaining ring has a square cross section. When the length from the lower surface of the spring seat to the lower surface of the large-diameter shaft portion is L ₁ and the length from the upper end of the valve sleeve to the engagement groove is L ₂ , L ₁ > L ₂ and the small-diameter shaft portion The outer diameter of the valve sleeve is smaller than the inner diameter of the retaining ring in a state where the outer diameter of the retaining ring matches the inner diameter of the valve sleeve, and a tapered surface is formed on the inner periphery of the opening end of the valve sleeve. The hydraulic auto tensioner described.   A tension pulley is rotatably provided at a swing side end of a pulley arm that is swingably supported by a fixed member, and the adjustment force of the hydraulic auto tensioner according to any one of claims 1 to 3 is loaded on the pulley arm. Then, the belt tension adjusting device that urges the pulley arm in the direction in which the tension pulley presses the belt.   The belt tension adjusting device according to claim 4, wherein a spring seat of the hydraulic auto tensioner is rotatably connected to a pulley arm, and a closed end portion of the cylinder is rotatably connected to a fixing member.   The belt tension adjusting device according to claim 4, wherein a spring seat of the hydraulic auto tensioner is rotatably connected to a fixed member, and a closed end portion of the cylinder is rotatably connected to a pulley arm.

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