JP2015064004A - Hydraulic auto tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic auto tensioner capable of adding proper tension to a belt during normal drive and starting of an engine.SOLUTION: A rod 5 is slidably inserted in the inside of a valve sleeve 4 standing on a bottom surface of a cylinder 1 to provide a pressure chamber 6 in the valve sleeve, and the rod and the valve sleeve are energized in an expanding direction by a return spring 8. When pushing-in force is loaded on the rod, oil in the pressure chamber generates hydraulic damper force in the pressure chamber by viscous resistance of the oil leaking from a leak clearance 19 formed between sliding surfaces of the valve sleeve and the rod, thereby buffering the pushing-in force. A seal ring 20 is assembled between the sliding surfaces of the valve sleeve and the rod. Oil circulation amount in an abutment 21 provided on the seal ring is made to be larger than oil circulation amount in the leak clearance, and the seal ring is set to have size concentrating leak oil from the leak clearance to the abutment to interfere with each other when pressure in the pressure chamber abruptly raised.

Description

  The present invention relates to a hydraulic auto tensioner used for tension adjustment of a belt that drives an auxiliary machine such as an alternator, a water pump, and a compressor of an air conditioner.

  An engine equipped with an ISG (Integrated Starter Generator) idle stop mechanism that stops the engine when the vehicle is stopped and instantly starts the engine when the vehicle is started by depressing the accelerator pedal to reduce carbon dioxide emissions Has been proposed.

FIG. 7A shows an engine belt transmission equipped with an ISG idle stop mechanism that achieves both engine auxiliary drive and engine start. The crankshaft pulley P ₁ attached to the crankshaft 31 and the ISG a starter-generator pulley P ₂ attached to a rotating shaft of the starter generator 32, passing over the belt 34 between the accessory pulley P ₃ attached to a rotating shaft of the auxiliary machine 33 such as a water pump, the normal operation of the engine when, as shown in the figure, it drives the starter generator 32 and the auxiliary 33 by rotation in the direction indicated by the arrow of the crankshaft pulley P _1, so that to function starter generator 32 as a generator.

On the other hand, when the engine is started by driving the starter generator 32, rotates the crankshaft pulley P ₁ by rotation in the direction indicated by the arrow of the starter-generator pulley P _2, and the starter generator 32 so as to function as a starter Yes.

The belt transmission device as described above, a tension pulley 35 provided on the crankshaft pulley P ₁ and the starter generator belt portion 34a over the pulley P _2, the swingable pulley arm 36 for rotatably supporting the tension pulley 35 The adjustment force of the hydraulic auto tensioner A is applied to urge the pulley arm 36 in the direction in which the tension pulley 35 presses the belt 34, and the tension change of the belt 34 is absorbed by the hydraulic auto tensioner A.

  As a hydraulic autotensioner A, what was described in patent document 1 is conventionally known. In this hydraulic auto tensioner, a lower end portion of a rod is slidably inserted into a valve sleeve projecting on the bottom surface of the cylinder, a pressure chamber is formed in the valve sleeve, and the upper end portion of the rod is A return spring is incorporated between the provided spring seat and the bottom surface of the cylinder to urge the rod and the valve sleeve in the extending direction.

  In addition, a sealed reservoir chamber is provided between the inner periphery of the cylinder and the outer periphery of the valve sleeve, and the lower portion of the reservoir chamber and the lower portion of the pressure chamber communicate with each other through an oil passage formed in the bottom surface of the cylinder. A check valve is installed in the lower end, and when the pushing force is applied to the rod and the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber, the check valve is closed to block the communication between the oil passage and the pressure chamber. ing.

  In the hydraulic auto tensioner having the above-described configuration, the connecting piece provided on the upper surface of the spring seat is rotatably connected to the engine block E shown in FIG. 7A, and the connecting piece provided on the lower surface of the cylinder is connected. When a pushing force is applied to the rod from the belt 34 via the tension pulley 35 and the pulley arm 36, the check valve is closed and the oil sealed in the pressure chamber is slid between the valve sleeve and the rod. The fluid is caused to flow in a leak gap formed between the surfaces, and a hydraulic damper force is generated in the pressure chamber by the viscous resistance of the oil at the time of flow to buffer the pushing force.

JP 2012-241794 A

  By the way, in the conventional hydraulic auto tensioner, when the pushing force is applied to the rod, the oil in the pressure chamber leaks from the leak gap formed between the sliding surface of the valve sleeve and the rod. The proper tension cannot be applied to the belt 34 in each of the normal operation and at the start of the engine by the starter / generator 32.

That is, if the leak gap is set to a size that can absorb fluctuations in belt tension during normal operation of the engine, the leak gap is large. Therefore, the rod is pushed in greatly when the engine is started by driving the starter generator 32, and the belt There is a possibility that slack occurs in the belt 34 and slip occurs at the contact portion between the belt 34 and the pulleys P _{1 to} P ₃ , and the belt life may be shortened or the starter / generator 32 may fail to start the engine.

On the other hand, when the leak gap is set to a size that can absorb fluctuations in the tension of the belt 34 when the engine is started by driving the starter generator 32, the tension of the belt 34 during normal operation of the engine is reduced because the leak gap is small. Since the belt 34 becomes too high and the belt 34 becomes over-tensioned, the belt 34 and the bearings that rotatably support the pulleys P _{1 to} P ₃ are liable to be damaged, resulting in a problem of increased fuel consumption.

  An object of the present invention is to provide a hydraulic auto tensioner that can apply an appropriate tension to a belt during normal operation of the engine and when the engine is started by a starter generator.

  In order to solve the above problems, in the present invention, a valve sleeve is projected from the bottom of a bottomed cylinder filled with oil, and the lower end of the rod is slidably inserted into the valve sleeve. A pressure spring is provided in the valve sleeve, and a return spring that urges the cylinder and the rod in the extending direction is incorporated between a spring seat provided at the top of the rod and the bottom surface of the cylinder, and the inner circumference of the cylinder and the valve sleeve A reservoir chamber is provided between the outer periphery of the cylinder, and an oil passage is formed in the bottom of the cylinder so as to communicate a lower portion of the reservoir chamber and a lower portion of the pressure chamber. The pressure of the pressure chamber is stored in the lower portion of the valve sleeve. A check valve is provided that closes when the pressure inside the chamber becomes higher and blocks the communication between the pressure chamber and the oil passage. The hydraulic damper force is generated in the pressure chamber by the viscous resistance of the oil leaking from the leak gap formed between the valve sleeve and the sliding surface of the rod, and the pushing force applied to the rod is buffered. In the hydraulic auto tensioner, a seal ring is incorporated between the sliding surfaces of the valve sleeve and the rod to seal between the sliding surfaces, and the seal ring has a joint in a part in the circumferential direction. The oil flow rate at the joint is larger than the oil flow rate at the leak gap, and when the pressure rises rapidly in the pressure chamber, the leak oil concentrates from the leak gap to the joint and interferes with the oil flow. The configuration set to the size to be used was adopted.

  Here, when the pressure in the pressure chamber suddenly increases, for example, when the engine is stopped from the engine operation by an idle stop mechanism and the engine is started by ISG start, it is pressed by a tension pulley attached to the tensioner. The belt tension on the belt side changes from the loose side to the tight side. In this way, as the belt tension on the side pressed by the tension pulley changes from the loose side to the tension side, the belt tension suddenly increases, and the tensioner is pushed suddenly by the belt tension. A pressure increase.

  In the hydraulic auto tensioner according to the present invention, the size of the joint formed in the seal ring is 0.2 mm to 2.0 mm, and the flow rate of oil required depending on the use and size of the hydraulic auto tensioner Therefore, the size is appropriately set within the above size range.

  Specifically, when the engine is started by driving the starter / generator, the oil flow rate is faster than in the normal operation state of the engine. Therefore, when starting the engine, the oil flow rate is fast, so the oil flow rate is set to a level that restricts the oil flow due to interference between oils, and the oil flow rate is slow during normal engine operation. Therefore, the oil flow rate may be set so as to flow without being restricted at the joint.

  In the hydraulic auto tensioner having the above-described configuration, when adjusting the belt tension in the belt drive device for driving an auxiliary machine of an engine equipped with an ISG idle stop mechanism, a cylinder is connected to a tensioner mounting target such as an engine block, The spring seat at the tip of the rod is connected to a pulley arm that supports a tension pulley, and the tension pulley urges the pulley arm in a direction to press the belt portion between the crankshaft pulley and the motor / generator pulley, thereby tensioning the belt.

  In the state where the hydraulic auto tensioner is incorporated in the belt transmission as described above, if the belt tension is increased in the normal operation state of the engine and a pushing force is applied from the belt to the rod, the pressure in the pressure chamber increases. Thus, the check valve is closed, and the oil in the pressure chamber flows into the leak gap and the joint of the seal ring, and a hydraulic damper force is generated in the pressure chamber due to the viscous resistance of the oil at the time of the flow. The pushing force is buffered.

  At this time, since the oil flow rate through the leak gap is smaller than the oil flow rate at the joint, the leak gap is set to a size that can absorb fluctuations in belt tension during normal operation of the engine. The oil that has flowed will flow without restriction at the joint. As a result, the tension of the belt during normal operation of the engine does not become too high and is maintained at an appropriate tension.

  On the other hand, when the engine is started by driving the starter / generator, the tension of the belt suddenly increases and the pressure in the pressure chamber rises abruptly, the check valve closes, and the oil in the pressure chamber closes the leak gap and seal ring joint. To flow. At this time, the oil pressure is higher than the oil pressure during normal operation of the engine, so the oil flow rate in the leak gap is fast, and the leak oil concentrates from the annular leak gap to the seal ring joint and interferes with each other. Oil spillage will be hindered.

  As a result, the pressure drop in the pressure chamber is small, the push of the rod is suppressed by the action of the hydraulic damper in the pressure chamber, the belt is held at the belt tension necessary to drive the crankshaft, and the slip between the belt and the pulley Is prevented.

  In the hydraulic auto tensioner according to the present invention, the seal ring may be made of a synthetic resin.

  Further, the joint formed in the seal ring may be straight cut, angle cut, or step cut.

  Furthermore, the seal ring may be incorporated in a ring groove formed on the outer diameter surface of the rod, or may be incorporated in a ring groove formed on the inner diameter surface of the valve sleeve.

  In the present invention, as described above, a seal ring is incorporated between the sliding surfaces of the valve sleeve and the rod, and the oil flow rate at the joint provided in the circumferential direction of the seal ring is determined by the valve sleeve and the rod. By setting the oil flow rate to be larger than the oil flow rate in the leak gap formed between the sliding surfaces, and to allow the leak oil to concentrate and interfere from the leak gap to the entrance when the pressure in the pressure chamber suddenly increases An appropriate tension can be applied to the belt during normal operation of the engine and when the engine is started by the starter generator.

1 is a longitudinal sectional view showing an embodiment of a hydraulic auto tensioner according to the present invention. Sectional view along the line II-II in FIG. 2 is a perspective view of the seal ring shown in FIG. Perspective view showing another example of seal ring A perspective view showing still another example of a seal ring Sectional view showing another example of assembly of seal ring 1 shows a belt transmission device of an engine equipped with an idle stop mechanism, (a) is a front view showing a normal operation state of the engine, and (b) is a front view showing a start state of the engine by a starter generator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the cylinder 1 has a bottom portion, and a connecting piece 2 connected to a pulley arm 36 shown in FIG. 7A is provided on the bottom surface of the bottom portion.

  The connecting piece 2 is provided with a shaft insertion hole 2a penetrating from one side surface to the other side surface, and a cylindrical fulcrum shaft 2b and a sliding bearing 2c for rotatably supporting the fulcrum shaft 2b in the shaft insertion hole 2a. The fulcrum shaft 2b is fixed by tightening a bolt that is inserted into the fulcrum shaft 2b and screw-engaged with the pulley arm 36, and the cylinder 1 is swingably mounted around the fulcrum shaft 2b. The

  A sleeve fitting hole 3 is provided on the bottom surface of the cylinder 1, and a lower end portion of a steel valve sleeve 4 is press-fitted into the sleeve fitting hole 3. A large diameter portion 5 a provided at the lower portion of the rod 5 is slidably inserted into the valve sleeve 4, and a pressure chamber 6 is provided in the valve sleeve 4 by inserting the rod 5.

  A spring seat 7 is fixed to an upper end portion of the rod 5 located outside the cylinder 1, and a return spring 8 incorporated between the spring seat 7 and the bottom surface of the cylinder 1 extends relative to the cylinder 1 and the rod 5. It is energizing in the direction to do.

  A connecting piece 9 connected to the engine block E shown in FIG. 7A is provided at the upper end of the spring seat 7. The connecting piece 9 is formed with a sleeve insertion hole 9a penetrating from one side surface to the other side surface, and a sleeve 9b and a slide bearing 9c for rotatably supporting the sleeve 9b are incorporated in the sleeve insertion hole 9a. The connecting piece 9 is rotatably connected to the engine block E by a bolt inserted into the sleeve 9b.

  The spring seat 7 is formed of a molded product, and a cylindrical dust cover 10 that covers the upper outer periphery of the cylinder 1 and a cylindrical spring cover 11 that covers the upper portion of the return spring 8 are molded at the same time to form the spring seat 7. Is integrated.

  Here, the spring seat 7 may be an aluminum die-cast molded product, or may be a molded product of a resin such as a thermosetting resin.

  The entire outer periphery of the spring cover 11 is covered with a cylindrical body 12 that is insert-molded when the spring seat 7 is molded. The cylinder 12 is made of a press-formed product of a steel plate.

  An oil seal 13 as a seal member is incorporated in the upper opening of the cylinder 1, and the inner periphery of the oil seal 13 is in elastic contact with the outer peripheral surface of the cylinder 12 to close the upper opening of the cylinder 1. This prevents the oil filled inside the tank from leaking to the outside and prevents dust from entering the inside.

  By incorporating the oil seal 13, a sealed reservoir chamber 14 is formed between the cylinder 1 and the valve sleeve 4. The reservoir chamber 14 and the pressure chamber 6 are an oil reservoir comprising an oil passage 15 formed between the fitting surfaces of the sleeve fitting hole 3 and the valve sleeve 4 and a circular recess formed at the center of the bottom surface of the sleeve fitting hole 3. 16 to communicate with each other.

  A check valve 17 is incorporated in the lower end portion of the valve sleeve 4. When the pressure in the pressure chamber 6 becomes higher than the pressure in the reservoir chamber 14, the check valve 17 is closed to cut off the communication between the pressure chamber 6 and the oil passage 15, and the oil in the pressure chamber 6 passes through the oil passage 15. This prevents the flow into the reservoir chamber 14.

  As shown in FIGS. 1 and 2, a ring groove 18 is formed in the large diameter portion 5 a provided in the lower portion of the rod 5, and a seal ring 20 is incorporated in the ring groove 18.

  The seal ring 20 seals a leak gap 19 formed between the outer diameter surface of the large diameter portion 5 a and the inner diameter surface of the valve sleeve 4. The seal ring 20 is made of synthetic resin, and an abutment 21 is provided in a part of the circumferential direction.

  The joint 21 may be a straight cut parallel to the axis as shown in FIG. 3, or an angle cut inclined with respect to the axis as shown in FIG. May be. Furthermore, as shown in FIG. 5, the projecting portion 21a and the recessed portion 21b are provided on each of the abutting end surfaces, and the projecting portion 21a and the recessed portion 21b are inserted into the facing recess portion 21b and the projecting portion 21a. It may be a thing.

  Here, the leak gap 19 is set to a size capable of absorbing belt tension fluctuations during normal operation of the engine. On the other hand, in the abutment 21, the oil circulation amount in the abutment 21 is made larger than the oil circulation amount in the leak gap 19, and the pressure in the pressure chamber 6 rises rapidly and leaks from the annular leak gap 19 to the abutment 21. When the oil is concentrated, the size is set so that the leaked oil interferes with each other and interferes with circulation.

  As shown in FIG. 1, an annular groove 22 is formed at the upper end of the inner diameter surface of the valve sleeve 4, and a retaining ring 23 is incorporated in the annular groove 22. The inner peripheral portion of the retaining ring 23 is located inward from the inner diameter surface of the valve sleeve 4, and the rod 5 is brought into contact with the inner peripheral portion of the retaining ring 23 by the contact of the upper end surface of the large diameter portion 5 a of the rod 5. It is prevented from exiting.

  The hydraulic auto tensioner shown in the embodiment has the above-described configuration, and is connected to the closed end of the cylinder 1 when the engine is installed in the belt transmission of the engine equipped with the idle stop mechanism shown in FIG. The piece 2 is connected to the pulley arm 36, and the connecting piece 9 of the spring seat 7 is connected to the engine block E to apply an adjusting force to the pulley arm 36.

  In the tension adjustment state of the belt 34 as described above, when the tension of the belt 34 changes due to a load fluctuation of the auxiliary machine 33 in the normal operation state of the engine, and the tension of the belt 34 becomes weak, the return spring 8 is pressed. The slack of the belt 34 is absorbed by relative movement in the direction in which the cylinder 1 and the rod 5 extend.

  Here, when the cylinder 1 and the rod 5 move relative to each other in the extending direction, the pressure in the pressure chamber 6 becomes lower than the pressure in the reservoir chamber 14, so that the check valve 17 is opened. For this reason, the oil in the reservoir chamber 14 smoothly flows from the oil passage 15 through the oil reservoir 16 into the pressure chamber 6, and the cylinder 1 and the rod 5 smoothly move relative to each other in the extending direction to thereby loosen the belt 34. Absorb immediately.

  On the other hand, when the tension of the belt 34 is increased, a pushing force in a direction of contracting the cylinder 1 and the rod 5 of the hydraulic auto tensioner is applied from the belt 34. At this time, since the pressure in the pressure chamber 6 becomes higher than the pressure in the reservoir chamber 14, the check valve 17 is closed.

  The oil in the pressure chamber 6 flows from the leak gap 19 formed between the inner diameter surface of the valve sleeve 4 and the outer diameter surface of the rod 5 through the joint 21 of the seal ring 20 and flows into the reservoir chamber 14. A hydraulic damper force is generated in the pressure chamber 6 due to the viscous resistance of the oil flowing through the leak gap 19, and the pushing force applied to the hydraulic auto tensioner is buffered by the hydraulic damper force.

  At this time, the amount of oil flowing through the leak gap 19 is smaller than the amount of oil flowing through the joint 21 in the seal ring 20, and the leak gap 19 is set to a size that can absorb fluctuations in the tension of the belt 34 during normal operation of the engine. Therefore, the oil leaking into the leak gap 19 flows without restricting the flow rate at the joint 21. As a result, the tension of the belt 34 during the normal operation of the engine does not become too high and is maintained at an appropriate tension.

  On the other hand, when the engine is started by driving the starter / generator 32, the tension of the belt 34 increases rapidly, the pressure in the pressure chamber 6 increases rapidly, the check valve 17 closes, and the oil in the pressure chamber 6 leaks. It flows into the gap 19 and the abutment 21 of the seal ring 20. At this time, since the oil pressure is higher than the oil pressure during normal operation of the engine, the oil flow rate in the leak gap 19 is fast, and the leak oil concentrates from the annular leak gap 19 to the joint 21 of the seal ring 20. They will interfere with each other and oil spillage will be hindered.

For this reason, there is no sudden pressure drop in the pressure chamber 6, and the pushing of the rod 5 is suppressed by the hydraulic damper action in the pressure chamber 6, and the belt 34 is held at the belt tension necessary for driving the crankshaft 31. , slip between the belt 34 and the pulleys _{P 1} to _{P 3} is prevented.

  In FIG. 1, the ring groove 18 is formed in the large-diameter portion 5a provided at the lower part of the rod 5, and the seal ring 20 is incorporated in the ring groove 18. However, as shown in FIG. A small-diameter hole portion 4a into which the rod 5 is slidably inserted is provided at the upper part of the valve sleeve 4, and a ring groove 24 is formed on the inner diameter surface of the small-diameter hole portion 4a. The seal ring 20 having the joint 21 may be incorporated in the ring groove 24.

  In this case, an annular groove 25 is provided on the outer periphery of the lower end portion of the rod 5, a retaining ring 26 is attached to the annular groove 25, and the rod 5 is prevented from being pulled out by contact of the retaining ring 26 with the lower end surface of the small diameter hole 4a.

1 Cylinder 4 Valve sleeve 5 Rod 6 Pressure chamber 7 Spring seat 8 Return spring 14 Reservoir chamber 15 Oil passage 17 Check valve 18 Ring groove 19 Leakage clearance 20 Seal ring 21 Auxiliary 24 Ring groove

Claims (5)

A valve sleeve protrudes from the bottom of the bottomed cylinder containing oil, and the lower end of the rod is slidably inserted into the valve sleeve to provide a pressure chamber in the valve sleeve. A return spring that urges the cylinder and rod in the extending direction is incorporated between the spring seat provided on the cylinder and the bottom surface of the cylinder, and a reservoir chamber is provided between the inner circumference of the cylinder and the outer circumference of the valve sleeve. Forms an oil passage that communicates the lower portion of the reservoir chamber and the lower portion of the pressure chamber, and closes in the lower portion of the valve sleeve when the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber. A check valve that cuts off the communication between the pressure chamber and the valve sleeve is closed when a pushing force is applied to the rod. In hydraulic auto-tensioner which is adapted to generate a hydraulic damper force in the pressure chamber by viscous resistance of the oil leaking from the leak gap formed between the sliding surfaces of buffering the pushing force loaded on the rod,
A seal ring is incorporated between the sliding surfaces of the valve sleeve and the rod, the space between the sliding surfaces is sealed, and the seal ring has a joint in a part of the circumferential direction. It is larger than the oil flow rate in the leak gap, and when the pressure rises suddenly in the pressure chamber, the leak oil concentrates on the abutment from the leak gap and interferes with the oil flow. Hydraulic auto tensioner to perform.   The hydraulic auto tensioner according to claim 1, wherein the seal ring is made of a synthetic resin.   The hydraulic auto tensioner according to claim 1 or 2, wherein the joint is made of one of straight cut, angle cut, and step cut.   The hydraulic auto tensioner according to any one of claims 1 to 3, wherein a ring groove is provided on an outer diameter surface of the rod, and the seal ring is incorporated in the ring groove.   The hydraulic auto tensioner according to any one of claims 1 to 3, wherein a ring groove is provided on an inner diameter surface of the valve sleeve, and the seal ring is incorporated in the ring groove.

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