JP6153421B2 - Hydraulic auto tensioner - Google Patents

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. 8A shows an engine belt transmission equipped with an ISG idle stop mechanism that achieves both engine accessory drive and engine start. The crankshaft pulley P ₁ attached to the crankshaft ₁ and the ISG a starter-generator pulley P ₂ attached to a rotating shaft of the starter-generator 2, looped belt 4 between accessory pulley P ₃ attached to a rotating shaft of the auxiliary machine 3 such as a water pump, the normal operation of the engine when, as shown in the figure, it drives the starter-generator 2 and the auxiliary 3 by rotation in the direction indicated by the arrow of the crankshaft pulley P _1, and so as to function the starter-generator 2 as a generator.

On the other hand, when the engine start by the driving of the starter-generator 2 to rotate 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 2 to function as a starter Yes.

The belt transmission device as described above, a tension pulley 5 provided on the crankshaft pulley P ₁ and the starter generator belt portion 4a over the pulley P _2, the swingable pulley arm 6 for rotatably supporting the tension pulley 5 The adjustment force of the hydraulic auto tensioner A is applied to urge the pulley arm 6 in the direction in which the tension pulley 5 presses the belt 4, and the tension change of the belt 4 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, the upper opening of the cylinder filled with oil is closed by incorporating a seal member, and the rod that slidably passes through the seal member is urged in a protruding direction by a return spring, A hydraulic damper mechanism that cushions the pushing force applied to the rod is provided at the lower end of the rod.

  The hydraulic damper mechanism connects a plunger that is slidable along the cylinder inner surface to the lower end of the rod, and a passage that communicates with the plunger and a pressure chamber provided on the lower side and a reservoir chamber provided on the upper side. And a check valve that closes the passage when the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber is provided at the lower end of the passage.

  In the hydraulic auto tensioner having the above-described configuration, the connecting piece provided on the lower surface of the cylinder is rotatably connected to the engine block E shown in FIG. 8A, and the upper connection of the spring seat provided on the upper portion of the rod. The piece is connected to the pulley arm 6 to prevent the rod from rotating. When a pushing force is applied from the belt 4 to the rod through the tension pulley 5 and the pulley arm 6, the check valve is closed and the oil sealed in the pressure chamber is removed. It is made to flow through a leak gap formed between the sliding surfaces of the valve sleeve and the rod, and a hydraulic damper force is generated in the pressure chamber by the viscous resistance of oil at the time of the flow to buffer the pushing force.

JP-A-9-177913

  By the way, in the conventional hydraulic auto tensioner, when a pushing force is applied to the rod, the oil in the pressure chamber leaks from a single leak gap formed between the sliding surface of the valve sleeve and the rod. Therefore, an appropriate tension cannot be applied to the belt 4 during normal operation of the engine and when the engine is started by the starter / generator 2.

That is, if the leak gap is set to a size that can absorb the belt tension fluctuation during the normal operation of the engine, the leak gap is large, so that the rod 4 is pushed greatly when the engine is started by driving the starter generator 2 and the belt 4 The belt 4 and the pulleys P _{1 to} P ₃ may slip, and the belt life may be shortened or the starter / generator 2 may fail to start the engine.

On the other hand, if the leak gap is set to a size that can absorb fluctuations in the tension of the belt 4 when the engine is started by driving the starter generator 2, the leak gap is small, so that the tension of the belt 4 during normal operation of the engine is reduced. Since the belt 4 becomes too high and the belt 4 becomes over-tensioned, the belt 4 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.

  Here, in Japanese Patent Laid-Open No. 10-122315, when a rod slidably passing through a sealing member is suddenly pushed, the belt can be held in tension by locking the rod by a locking mechanism using a sawtooth screw. A hydraulic auto tensioner is proposed, and the lock mechanism is applied to the hydraulic auto tensioner described in Patent Document 1, so that the rod is pushed greatly when the engine is started by driving the starter generator 2. It is thought that it can be prevented.

  However, the hydraulic auto tensioner described in Japanese Patent Application Laid-Open No. 10-122315 is for a timing belt and the rod can rotate relative to the cylinder. On the other hand, the hydraulic auto tensioner described in Patent Document 1 The rod is connected to a pulley arm, and the rod cannot be rotated relative to the cylinder by the connection. For this reason, when the lock mechanism is employed in a hydraulic auto-tensioner for driving auxiliary equipment, the nut member of the lock mechanism is fixed, so that the rod engaged with the nut member is moved in the axial direction while rotating the rod. The locking mechanism cannot be employed in the hydraulic auto tensioner described in Patent Document 1.

  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-mentioned problems, in the present invention, the upper opening of the cylinder filled with oil is closed by incorporating a seal member, and the seal member is slidably penetrated and rotated by being assembled to a belt transmission. The lower end of the rod to be stopped is connected to a plunger slidable along the inner diameter surface of the cylinder, and the plunger is connected to a pressure chamber provided below and a reservoir chamber provided above. In a hydraulic auto tensioner in which a check valve that closes when the pressure in the pressure chamber becomes higher than the reservoir chamber is installed in the passage, and the cylinder and the rod are urged in a direction to extend by a return spring, the lower end of the rod A male screw is provided on the outer periphery of the part, and a nut member that is screw-engaged with the male screw is assembled inside the cylinder and rotated. The flank angle of the pressure side flank that freely supports and restricts the movement in the axial direction and receives the pushing force in the direction in which the cylinder and the rod contract with the male screw and the female screw formed on the inner periphery of the nut member. The sawtooth flank is larger than the flank angle of the idle side flank, and the serrated screw is set in a loose condition in which the nut member rotates against the load of elastic force that the return spring presses the cylinder and rod in the extending direction. Therefore, a configuration is adopted in which the lock condition is set such that the rotation of the nut member is prevented against a sudden belt pressing force that contracts the cylinder and the rod.

  Here, the abrupt belt pushing force means the following. For example, when the engine is stopped by the idle stop mechanism or the like and the engine is started by starting the ISG, the tension of the belt pressed by the tension pulley attached to the tensioner is changed from the loose side to the tight side. Change. Thus, the tension of the belt suddenly increases as the tension of the belt pressed by the tension pulley changes from the loose side to the tension side.

  In the hydraulic auto tensioner having the above-described configuration, the tensioner mounting target such as the engine block and the tension pulley are supported when adjusting the belt tension in the belt drive device for driving the auxiliary machinery of the engine equipped with the ISG idle stop mechanism. The cylinder is connected to one of the pulley arms and the tip of the rod is connected to the other. The tension pulley urges the pulley arm in the direction of pressing the belt between the crankshaft pulley and the starter / generator pulley, and tensions the belt. .

  In the state in which the hydraulic auto tensioner is incorporated in the belt transmission device as described above, the belt tension is increased in the normal operation state of the engine, and the pushing force in the direction of contraction from the belt to both the cylinder and the rod is loaded. Then, the pressure in the pressure chamber increases, the check valve closes, the oil in the pressure chamber flows into the leak gap formed between the sliding surfaces of the cylinder and the plunger, and due to the hydraulic damper action due to the viscous resistance of the oil The pushing force is buffered.

  At this time, the axial screw clearance formed in the screw engaging portion of the male screw on the outer periphery of the rod and the female screw on the nut member is sized so as to absorb the belt tension change in the normal operation state of the engine by the hydraulic damper action. Is set. For this reason, the thread flank at the screw engaging portion of the male screw and the female screw is not in contact, the fluctuating load from the belt is supported only by the hydraulic damper, and the belt is held at an appropriate tension.

  When the belt tension is weakened, an elastic force is applied from the return spring to both the cylinder and the rod, and the cylinder and the rod move relative to each other so that the play side flank of the male screw and the female screw come into contact with each other. At this time, since the screw thread at the screw engaging portion of the male screw and the female screw is set to a loosening condition, the nut member rotates and the cylinder and the rod smoothly move relative to each other in the extending direction, and the belt tension and Stops at a position where the spring force of the return spring is balanced.

  On the other hand, when the engine is started by driving the starter generator, the belt tension suddenly increases, and a large belt pushing force that contracts from the belt to both the cylinder and the rod is suddenly applied, and the pressure side flank of the serrated male screw Contact the pressure side flank of the female thread. At this time, since the thread at the screw engagement between the male screw and the female screw is set to the locking condition from the relationship between the flank angle and the lead angle, the rod is not locked and pushed in with the pressure side flank contacting. Absent. For this reason, the belt is held at the belt tension necessary to drive the crankshaft, and slip between the belt and the pulley is prevented.

  After the engine starts, when the starter / generator switches to function as a generator, the belt changes from the tension side to the slack side, the cylinder and the rod extend due to the return spring pressing, and the pressure side flank of the male screw and female screw contact each other To do. At this time, since the screw thread in the screw engaging portion of the male screw and the female screw is in a loosening condition, the nut member rotates by pressing from the rod, and the cylinder and the rod extend smoothly.

  In the hydraulic auto tensioner according to the present invention, as a means for restricting movement of the nut member in the axial direction, a nut member incorporated in the cylinder and slidably supporting the plunger, and a nut member between the upper end surfaces of the sleeve It is possible to employ a structure comprising a retaining ring attached in the cylinder with an interval that allows the housing to be accommodated.

  Here, if a bearing is incorporated between the retaining ring and the nut member, the nut member is supported by the bearing, so that the nut rotates smoothly and the cylinder and the rod can be smoothly moved relative to each other in the extending direction.

  As the bearing, a thrust ball bearing, a thrust roller bearing, a sliding bearing made of a sintered oil-impregnated metal, or a sliding bearing made of a metal subjected to a low friction film treatment can be employed.

  In the hydraulic auto tensioner according to the present invention, as described above, a male screw is provided on the outer periphery of the lower end of the rod, and a nut member that is screw-engaged with the male screw is incorporated into the cylinder and is rotatably supported. The movement in the axial direction is restricted, and the thread of the male thread and the female thread formed on the inner periphery of the nut member is serrated, and the serrated thread is pressed in the direction in which the return spring extends the cylinder and the rod. By setting the loose condition for the nut member to rotate with respect to the load of the elastic force to be set, and the lock condition for preventing the nut member from rotating against the load of the belt pushing force due to sudden pressing, Appropriate tension can be applied to the belt during normal operation 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 drawing which expands and shows the principal part of FIG. Sectional drawing which expands and shows the screw engaging part of the external thread of the rod shown by FIG. 2, and the internal thread of a nut member Sectional view of the pressure side flank of male and female threads in contact with each other A cross-sectional view of the male and female threads with the play side flank in contact with each other Sectional view showing another example of bearing Partially cutaway perspective view showing still another example of bearing 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 10 whose lower part is closed has a steel bottomed sleeve 11 inside, and a connecting piece 12 is provided on the lower surface, and the connecting piece 12 is shown in FIG. It can be connected to the pulley arm 6.

  An oil seal 13 as a seal member is incorporated in the upper opening of the cylinder 10. The oil seal 13 is retained by a retaining ring 15, and a rod 16 is slidably inserted into a rod insertion hole 14 formed in the oil seal 13.

  A spring seat 17 is provided on the upper end portion of the rod 16 located outside the upper end of the cylinder 10 and is connected to an engine block E as a tensioner attachment target shown in FIG. A connecting piece 18 is provided. A cylindrical dust cover 19 that covers the upper opening of the cylinder 10 is provided on the lower surface of the spring seat 17.

  A return spring 20 is provided outside the cylinder 10. The lower end of the return spring 20 is supported by a flange 21 provided at the lower outer periphery of the cylinder 10, and the upper end is supported by a spring seat 17. The return spring 20 biases the cylinder 10 and the rod 16 in the extending direction.

  Inside the cylinder 10, a hydraulic damper mechanism 22 is provided for buffering the pushing force that urges the cylinder 10 and the rod 16 in the contracting direction.

  The hydraulic damper mechanism 22 connects a plunger 23 slidable along the inner diameter surface of the sleeve 11 to the lower end portion of the rod 16, and the plunger 23 is provided on the upper side with a pressure chamber 24 provided on the lower side thereof. A passage 26 communicating with the reservoir chamber 25 is formed, and a check valve 27 is provided at the opening end of the passage 26 on the pressure chamber 24 side.

  The check valve 27 closes the passage 26 when the cylinder 10 and the rod 16 are relatively contracted and the pressure in the pressure chamber 24 becomes higher than the pressure in the reservoir chamber 25.

  Here, when connecting the rod 16 and the plunger 23, a rod insertion hole 28 is formed on the upper surface of the plunger 23, and the lower end portion of the rod 16 is inserted into the rod insertion hole 28.

  As shown in FIGS. 1 and 2, the rod 16 is formed with a male screw 30 on the outer periphery in a range from a position slightly deviated from the upper end surface of the plunger 23 toward the upper end side to a central portion in the length direction. The nut member 31 is engaged with the screw.

  The nut member 31 is placed on the upper end surface of the sleeve 11 and is rotatable, and movement in the axial direction is restricted by a retaining ring 33 attached to the upper end surface of the sleeve 11 and the inner diameter surface of the cylinder 10. .

  A bearing 34 is incorporated between the opposing portions of the retaining ring 33 and the nut member 31, and a minute gap 35 is provided between the bearing 34 and the retaining ring 33, and the nut member 31 is movable within the range of the gap 35. Has been.

  Although the thrust ball bearing is adopted as the bearing 34 in FIG. 2, it is not limited to the thrust ball bearing. For example, the thrust roller bearing shown in FIG. 6 may be used, or the sliding bearing shown in FIG. 7 may be used. When a sliding bearing is employed as the bearing 34, it is preferable to employ a material made of a metal subjected to a low friction coating such as sintered oil-impregnated metal or diamond-like carbon (DLC) in order to smoothly rotate the nut member 31. .

  The external thread 30 on the outer periphery of the rod 16 and the internal thread 32 formed on the inner periphery of the nut member 31 are subjected to pressure when the pressing force in the direction in which the cylinder 10 and the rod 16 contract with each other is loaded. The flank angle of the flank 36 has a serrated shape larger than the flank angle of the play side flank 37, and the rod 16 extends in a direction extending relative to the cylinder 10 due to the relationship between the flank angle of the serrated screw and the lead angle (rod protrusion). (Direction) is a loosening condition, and the contracting direction (rod pushing direction) is a locking condition.

  Here, the loosening condition means that when the belt 4 shown in FIG. 8A is loosened due to the influence of thermal expansion or aging, the cylinder 10 and the rod 16 are connected to the male screw 30 and the female screw 32 by the elastic force of the return spring 20. The nut member is moved by the relative screw motion in which the play-side flank 37 of the male screw 30 and the female screw 32 comes into contact with each other and moves in the rod protruding direction by the axial screw gap formed between the screw engaging portions of the screw and the sliding portion causes slippage. This means that 31 rotates and the rod 16 moves smoothly in the protruding direction.

  On the other hand, the lock condition is a direction in which the tension of the belt 4 suddenly increases and the cylinder 10 and the rod 16 contract rapidly each other when the engine is started by driving the starter generator 2 shown in FIG. When the belt pushing force is applied, the rod 16 moves in the rod pushing direction by an axial screw gap formed between the screw engaging portions of the male screw 30 and the female screw 32, and the pressure side flank of the male screw 30 and the female screw 32 is moved. This means that the 36 comes into contact with each other, and the nut member 31 does not rotate and the rod 16 is held in a stopped state without slipping at the contact portion.

  In driving the engine, the vibration of the belt 4 interacts with the cylinder 10 and the rod 16, the male screw 30 and the female screw 32 move relative to each other in the axial direction, and the pressure side flank 36 intermittently contacts and separates repeatedly. When the pressure side flank 36 comes into contact with each other, the nut member 31 is intermittently rotated little by little without locking the relative screw motion of the pressure side flank 36 in contact, and the cylinder 10 and the rod 16 contract. It has become.

  The hydraulic auto tensioner shown in the embodiment has the above-described configuration, and is connected to the closed end of the cylinder 10 when the engine is installed in the belt transmission device of the engine equipped with the idle stop mechanism shown in FIG. The piece 12 is connected to the pulley arm 6, and the connecting piece 18 on the upper surface of the spring seat 17 provided at the upper end portion of the rod 16 is connected to the engine block E to apply adjustment force to the pulley arm 6.

  In the tension adjustment state of the belt 4 as described above, when the belt 4 vibrates due to a load fluctuation of the auxiliary machine 3 or the like, the cylinder 10 and the rod 16 receive a fluctuating load accompanying a change in the tension of the belt 4 and the pushing force is applied from the belt 4. When it is loaded, it contracts, and when the pushing load is unloaded, it expands due to the elastic force of the return spring 20.

  At that time, the check valve 27 held by the plunger 23 opens and closes. When the pressure in the pressure chamber 24 becomes lower than the pressure in the reservoir chamber 25, the check valve 27 opens the passage 26 and the oil in the reservoir chamber 25 flows into the pressure chamber 24. Further, when the pressure in the pressure chamber 24 becomes higher than the pressure in the reservoir chamber 25, the passage 26 is closed, and the tension change of the belt 4 is absorbed by the hydraulic damper action by the oil in the pressure chamber 24. Held in tension.

As shown in FIG. 3, in the normal operating state of the engine (during normal running), axial screw gaps G ₁ and G ₂ are provided between the screw engaging portions of the male screw 30 of the rod 16 and the female screw 32 of the nut member 31. Is provided. The screw gaps G ₁ and G ₂ are large enough to buffer the tension change of the belt 4 by the hydraulic damper action by the oil in the pressure chamber 24, and the pressure-side flank 36 and play of the male screw 30 and the female screw 32. The side flank 37 is not in contact, and the fluctuating load from the belt 4 is supported only by a hydraulic damper with oil in the pressure chamber 24.

  Here, when the pressure in the pressure chamber 24 becomes higher than the elastic force of the return spring 20, the oil in the pressure chamber 24 leaks into the reservoir chamber 25 from the leak gap 38 formed between the sliding surface of the sleeve 11 and the plunger 23. Since the hydraulic damper force is generated in the pressure chamber 24 due to the viscous resistance of the leaking oil, the damper force of the hydraulic damper can be set by the leak gap 38. The tension of the belt 4 is kept low by setting the damper force small.

  On the other hand, when the engine is started by driving the starter / generator 2, the tension of the belt 4 rapidly increases, and an extremely large belt pushing force is applied to the cylinder 10 and the rod 16. At this time, the cylinder 10 and the rod 16 are relatively pushed in until there is no axial screw gap in the screw engagement between the male screw 30 and the female screw 32, and the pressure side of the male screw 30 and the female screw 32 is shown in FIG. The flank 36 contacts each other.

In this case, the thread 16 at the screw engaging portion of the male screw 30 and the female screw 32 is set to the lock condition from the relationship between the flank angle and the lead angle, so the rod 16 is locked in a state where the pressure side flank 36 is in contact. Can not be pushed further. Therefore, the belt 4 is held in the belt tension required for driving the crankshaft 1, slip between the belt 4 and the pulleys P ₁ to P ₃ is prevented.

After the engine was started by the starter-generator 2, crankshaft pulley P ₁ and the starter generator belt portion 4a over the pulley P ₂ is changed to the slack side from tight side. At this time, when the cylinder 10 and the rod 16 are relatively moved in the extending direction, the play side flank 37 of the male screw 30 and the female screw 32 come into contact with each other as shown in FIG.

  In this case, the screw thread at the screw engaging portion of the male screw 30 and the female screw 32 is set to a loose condition from the relationship between the flank angle and the lead angle, so the nut member 31 rotates and the cylinder 10 and the rod 16 extend. Smooth relative movement in the direction you want.

  As described above, in the hydraulic auto tensioner according to the embodiment, an appropriate tension can be applied to the belt 4 during normal operation of the engine and when the engine is started by the starter / generator 2.

10 Cylinder 11 Sleeve 13 Oil seal (seal member)
16 Rod 20 Return spring 23 Plunger 24 Pressure chamber 25 Reservoir chamber 26 Passage 27 Check valve 30 Male thread 31 Nut member 32 Female thread 33 Retaining ring 34 Bearing 36 Pressure side flank 37 Play side flank

Claims (6)

The upper opening of the cylinder filled with oil is closed by incorporating a seal member, and the lower end of the rod that passes through the seal member in a slidable manner and is prevented from rotating by being assembled to the belt transmission device is connected to the inner diameter surface of the cylinder. The plunger is connected to a plunger slidable along the plunger, and the plunger is provided with a passage communicating with a pressure chamber provided on the lower side thereof and a reservoir chamber provided on the upper side. In a hydraulic auto tensioner that incorporates a check valve that closes when it is higher than the chamber, and urges the cylinder and rod in a direction to extend by a return spring,
A male screw is provided on the outer periphery of the lower end of the rod, and a nut member screw-engaged with the male screw is incorporated inside the cylinder to be rotatably supported, and the movement in the axial direction is restricted, and the male screw and the nut The female thread formed on the inner periphery of the member is formed into a sawtooth shape in which the flank angle of the pressure side flank receiving the pushing force in the direction in which the cylinder and the rod contract is larger than the flank angle of the play side flank, and the sawtooth screw is The nut member rotates in response to a load of elastic force that pushes the cylinder and rod in the direction in which the spring extends, and the nut member rotates in response to an abrupt belt pushing force that causes the cylinder and rod to contract. A hydraulic auto-tensioner, characterized in that the locking condition is set to be blocked.   The means for restricting the movement of the nut member in the axial direction includes a sleeve incorporated in the cylinder and slidably supporting the plunger, and an interval at which the nut member can be accommodated between the upper end surfaces of the sleeve. 2. The hydraulic auto tensioner according to claim 1, further comprising a retaining ring mounted in the cylinder.   The hydraulic auto tensioner according to claim 2, wherein a bearing for rotatably supporting the nut member is incorporated between the retaining ring and the nut member.   The hydraulic auto tensioner according to claim 3, wherein the bearing is a thrust ball bearing or a thrust roller bearing.   The hydraulic auto tensioner according to claim 3, wherein the bearing is a slide bearing.   The hydraulic auto tensioner according to claim 5, wherein the sliding bearing is made of a sintered oil-impregnated metal or a metal subjected to a low friction coating treatment.

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