JP6537415B2 - Hydraulic auto tensioner - Google Patents

Description

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

  In order to reduce carbon dioxide emissions, the engine is equipped with an ISG (Integrated Starter Generator) idle stop mechanism that stops the engine when the vehicle is stopped and starts the engine instantly when the vehicle starts by depressing the accelerator pedal. Proposed.

9 (a) and 9 (b) show a belt transmission of an engine equipped with an ISG idle stop mechanism which achieves both engine accessory driving and engine starting, and a crankshaft pulley P ₁ attached to a crankshaft 51 When, passing over the starter-generator pulley P ₂ attached to a rotating shaft of the ISG of the starter generator 52, an accessory pulley P ₃ between the belt 54 which is attached to a rotating shaft of the auxiliary machine 53 such as a water pump, during normal operation of the engine, as shown in FIG. 9 (a), to drive the starter-generator 52 and the auxiliary 53 by rotation in the direction indicated by the arrow of the crankshaft pulley P _1, to function starter-generator 52 as a generator It is like that.

On the other hand, when the engine is started by driving the starter generator 52, as shown in FIG. 9 (b), rotates the crankshaft pulley P ₁ by rotation in the direction indicated by the arrow of the starter-generator pulley P _2, starter The generator 52 is made to function as a starter.

The belt transmission device as described above, a tension pulley 55 provided on the crankshaft pulley P ₁ and the starter generator belt portion 54a over the pulley P _2, the swingable pulley arm 56 for rotatably supporting the tension pulley 55 The adjustment force of the hydraulic auto tensioner A is applied to bias the pulley arm 56 in the direction in which the tension pulley 55 presses the belt 54, and the change in tension of the belt 54 is absorbed by the hydraulic auto tensioner A.

  As hydraulic type automatic tensioner A, what was indicated in patent documents 1 is known conventionally. In this hydraulic auto-tensioner, the lower end of the rod is slidably inserted into a valve sleeve erected on the bottom of the cylinder to form a pressure chamber in the valve sleeve, and the upper end of the rod is A return spring is incorporated between the provided spring seat and the bottom of the cylinder to bias the rod and the valve sleeve in the extending direction.

  Further, 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 are communicated with an oil passage formed on the bottom portion of the cylinder. A check valve is incorporated in the lower end, pushing force is applied to the rod, and when the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber, the check valve is closed to shut off the communication between the oil passage and the pressure chamber. ing.

  The hydraulic auto-tensioner having the above-described configuration rotatably connects the connecting piece provided on the upper surface of the spring seat to the engine block E shown in FIG. 9A, and the connecting piece provided on the lower surface of the cylinder. When a pressing force is applied from the belt 54 to the rod via the tension pulley 55 and the pulley arm 56, the check valve is closed, and the oil enclosed in the pressure chamber slides between the valve sleeve and the rod. The fluid is made to flow into a leak gap formed between the surfaces, and a hydraulic damper force is generated in the pressure chamber by the viscosity resistance of the oil at the time of the flow to buffer the pressing force.

JP, 2009-277557, A

  By the way, in the above-mentioned conventional hydraulic auto tensioner, when pushing force is applied to the rod, the oil in the pressure chamber is leaked from the single leak gap formed between the sliding surfaces of the valve sleeve and the rod. As a result, the belt 54 can not be tensioned properly during normal operation of the engine and at engine startup by the starter generator 52, respectively.

That is, when the leak gap is set to a size that can absorb the tension fluctuation of the belt during normal operation of the engine, the rod is greatly pushed when the engine is started by the drive of the starter generator 52 because the leak gap is large. to the resulting slack, slippage occurs at the contact portion of the belt 54 and the pulley P ₁ to P _3, there is a possibility that the engine start failure is caused by the degradation or the starter generator 52 of the belt life.

On the other hand, if the leak clearance is set to a size that can absorb the tension fluctuation of the belt 54 at the start of the engine by driving the starter generator 52, the tension of the belt 54 during normal operation of the engine too high belt 54 becomes excessive tension, tends bearings supporting the belt 54 and the pulley P ₁ to P ₃ rotatably is damaged, a problem that fuel consumption is increased occurs.

  The object of the present invention is to ensure that the appropriate tension is applied to the belt during normal operation of the engine and at the start of the engine by the starter generator, and the slip of the belt at the start of the engine by the starter generator is ensured. It is an object of the present invention to provide a hydraulic auto-tensioner which can be prevented.

  In order to solve the above problems, in the present invention, a valve sleeve is erected on the bottom surface of the bottomed cylinder, and the lower end of the rod is slidably inserted into the valve sleeve to be inserted into the valve sleeve. A pressure chamber is provided, and a return spring for biasing the spring seat and the cylinder in an extending direction is incorporated between a spring seat provided on the upper portion of the rod and the bottom of the cylinder, and between the inner periphery of the cylinder and the outer periphery of the valve sleeve An oil passage communicating the lower portion of the formed reservoir chamber and the lower portion of the pressure chamber is formed, and is closed in the lower end portion of the valve sleeve when the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber. The first check valve is provided to shut off the fluid communication, and when the pressing force is applied to the rod through the spring seat, the first check valve is closed to re-load the oil in the pressure chamber. In a hydraulic auto-tensioner which leaks into a valve chamber and cushions a pressing force applied to a rod by hydraulic damper action by oil in a pressure chamber, between an outer diameter surface of the rod and an inner diameter surface of the valve sleeve A slidable cylindrical plunger is fitted to provide a first leak clearance between the sliding surface of the plunger and the rod, and between the sliding surfaces of the plunger and the valve sleeve, the first leak clearance is provided. A second leak gap having a large flow path resistance is provided, and a second check valve is provided between the rod and the plunger for closing the first leak gap when the plunger rises due to the pressure increase in the pressure chamber, A valve spring is provided which biases the plunger toward a stopper provided at the lower end of the rod, and the valve seat of the second check valve It had adopted a configuration in which with a difference in the surface hardness of the seat surface.

  In the hydraulic auto-tensioner having the above configuration, when adjusting the tension of the belt in an accessory drive belt drive of an engine equipped with an ISG idle stop mechanism, a spring seat at the end of a rod is attached to a tensioner such as an engine block. The lower end of the cylinder is connected to the pulley arm, and the tension pulley supported by the pulley arm urges the pulley arm in the direction to press the belt portion between the crankshaft pulley and the starter / generator pulley to tension the belt. Let

  When the hydraulic auto tensioner is incorporated into the belt drive as described above, the tension in the belt becomes strong in the normal operation of the engine, and if the pushing force is applied to the rod from the belt, the pressure in the pressure chamber is high. As the first check valve closes, the oil in the pressure chamber leaks from the first leak gap with a small flow path resistance into the reservoir chamber, and the viscous drag of the oil flowing in the first leak gap causes the hydraulic damper force to As a result, the above-mentioned pushing force is buffered by the hydraulic damper force, and the belt is held at an appropriate tension.

  On the other hand, when the engine is started by driving the starter / generator, the tension of the belt is rapidly increased and the pressure in the pressure chamber is rapidly increased. At this time, the first check valve is closed, and after the first check valve is closed, the plunger is raised to close the second check valve and the first leak gap is closed.

  Therefore, the oil in the pressure chamber leaks from the second leak gap into the reservoir chamber. Since the flow passage resistance of the second leak clearance is larger than the flow passage resistance of the first leak clearance, the pressure drop in the pressure chamber is small, and the push of the rod is suppressed by the hydraulic damper action in the pressure chamber, and the belt is a crankshaft The belt tension necessary to drive the belt is held to prevent slippage between the belt and the pulleys.

  Here, if the closing of the second check valve is incomplete, the oil also leaks from the first leak gap having a small flow path resistance, so that the damper force becomes small, which may cause belt slip.

  However, in the present invention, since the surface hardness of the valve seat and the seat surface of the second check valve is different, in the initial stage of using the product (hydraulic type auto tensioner), the second check valve is produced by elastic deformation of the contact portion. Closure can be perfect. On the other hand, by using the second check valve repeatedly by opening and closing, plastic deformation occurs at the contact portion between the valve seat and the seat surface to obtain a conformal effect, and complete closing of the second check valve can do. Therefore, the belt does not slip when the engine is started by driving the starter generator.

  Here, as the second check valve, a valve seat is formed at the lower end of the large diameter shaft portion located outside from the plunger upper end of the rod, and a seat surface capable of seating on the valve seat is provided on the upper inner diameter surface of the plunger. It is possible to adopt one having a different configuration.

  When one of the valve seat and the seat surface of the second check valve is a convex curved surface, and the other is a tapered flat surface, the contact between the valve seat and the seat surface can be made line contact, so Plastic deformation is likely to occur, and a good conforming effect can be obtained.

  Further, by making the member having the convex surface to have high hardness, the member having the low hardness side can easily conform to the convex surface having high hardness, and a better conforming effect can be obtained.

  The surface hardness can be achieved by increasing the hardness of the convex-curved member. As surface hardening treatment, diamond-like carbon treatment (DLC treatment), coating treatment of a hard film, shot peening, WPC treatment can be adopted.

  In the hydraulic auto-tensioner according to the present invention, a coil spring, a disc spring, a wave washer, and a wave spring may be employed as a valve spring which biases the plunger toward the stopper for stopper that is provided at the lower end of the rod. it can.

  In the present invention, as described above, during normal operation of the engine, oil in the pressure chamber leaks from the first leak gap with small flow path resistance to the reservoir chamber, while the pressure chamber is started when the engine is started by the starter generator. Since the oil of the above leaks into the reservoir chamber from the second leak gap where the flow path resistance is large, it is possible to apply an appropriate tension to the belt at the time of normal operation of the engine and at the start of the engine by the starter generator.

  In addition, since the surface hardness of the valve seat and the seat surface of the second check valve is made different, at the initial stage of use of the product, the closing of the second check valve should be completed by the elastic deformation of the contact portion. In addition, the closing of the second check valve can be perfected by using the same to obtain the fitting effect to the contact part by repeating the opening and closing of the second check valve, and by driving the starter generator. Belt slip at the time of engine start can be reliably prevented.

A longitudinal sectional view showing an embodiment of a hydraulic auto tensioner according to the present invention Sectional drawing which expands and shows the formation site of the 1st leak gap of Drawing 1, and the 2nd leak gap. Sectional view showing a state of oil leak from the second leak clearance (a) is sectional drawing which expands and shows the 2nd check valve part of FIG. 3, (b) is sectional drawing which shows the familiar state of a sheet | seat surface Sectional view showing another example of a valve spring Sectional view showing still another example of a valve spring Sectional view showing still another example of a valve spring Graph showing measurement examples of reaction force characteristics of the embodiment and the conventional hydraulic auto-tensioner The belt transmission of the engine in which the idle stop mechanism was mounted is shown, (a) is a front view showing the normal operation state of the engine, (b) is a front view showing the starting state of the engine by the starter generator.

  Hereinafter, embodiments of the present invention will be described based on the drawings. As shown in FIG. 1, the cylinder 10 has a bottom, and the lower surface of the bottom is provided with a connecting piece 11 connected to the pulley arm 56 of FIG.

  The connection piece 11 is provided with a shaft insertion hole 11a penetrating from one side to the other side, and a cylindrical fulcrum shaft 11b and a slide bearing 11c rotatably supporting the fulcrum shaft 11b in the shaft insertion hole 11a. The fulcrum shaft 11b is fixed by tightening a bolt inserted into the fulcrum shaft 11b and screwed to the pulley arm 56, and the connection piece 11 is rotatably attached to the pulley arm 56.

  A valve sleeve fitting hole 12 is provided on the bottom surface of the cylinder 10, and a lower end portion of a steel valve sleeve 13 is press-fitted into the valve sleeve fitting hole 12. The lower portion of the rod 14 is slidably inserted in the valve sleeve 13, and by the insertion of the rod 14, a pressure chamber 15 is provided in the valve sleeve 13 below the rod 14.

  A spring seat 16 is provided at an upper end portion of the rod 14 located outside the cylinder 10, and a return spring 17 incorporated between the spring seat 16 and the bottom surface of the cylinder 10 allows the cylinder 10 and the rod 14 to extend relatively. It is biased in the direction of

  The upper end of the spring seat 16 is provided with a connecting piece 18 connected to the engine block. The connection piece 18 is formed with a sleeve insertion hole 18a penetrating from one side to the other side, and a sleeve 18b and a slide bearing 18c rotatably supporting the sleeve 18b are incorporated in the sleeve insertion hole 18a. The connecting piece 18 is rotatably connected to the engine block by a bolt inserted into the sleeve 18b.

  The spring seat 16 is formed of a molded product, and at the time of molding, the cylindrical dust cover 20 covering the upper outer periphery of the cylinder 10 and the cylindrical spring cover 21 covering the upper part of the return spring 17 are simultaneously molded.

  Here, the spring seat 16 may be a die-cast molded product of aluminum, or may be a molded product of a resin such as a thermosetting resin.

  The entire outer periphery of the spring cover 21 is covered by a cylindrical body 22 which is insert-molded when the spring seat 16 is formed. The cylindrical body 22 consists of a press-formed product of a steel plate.

  An oil seal 23 as a seal member is incorporated in the upper opening of the cylinder 10, and the inner periphery of the oil seal 23 resiliently contacts the outer peripheral surface of the cylindrical body 22 to close the upper opening of the cylinder 10. It prevents the leakage of the oil filled inside the container and prevents the intrusion of dust into the container.

  The incorporation of the oil seal 23 forms a sealed reservoir chamber 24 between the cylinder 10 and the valve sleeve 13. The reservoir chamber 24 and the pressure chamber 15 are composed of an oil passage 25 formed between the fitting surfaces of the valve sleeve fitting hole 12 and the valve sleeve 13 and a circular recess formed in the central portion of the bottom of the valve sleeve fitting hole 12. It communicates through an oil reservoir 26.

  A first check valve 27 is incorporated in the lower end portion of the valve sleeve 13. The first check valve 27 has a steel check ball 27c for opening and closing the valve hole 27b of the valve seat 27a press-fit into the lower end portion of the valve sleeve 13 from the pressure chamber 15 side, and the check ball 27c faces the valve hole 27b. It comprises a spring 27d for biasing and a retainer 27e for regulating the opening and closing amount of the check ball 27c.

  In the first check valve 27, when the pressure in the pressure chamber 15 becomes higher than the pressure in the reservoir chamber 24, the check ball 27c closes the valve hole 27b and the communication between the pressure chamber 15 and the oil passage 25 is shut off. The oil in 15 is prevented from flowing to the reservoir chamber 24 through the oil passage 25.

  As shown in FIGS. 1 and 2, a cylindrical plunger 28 is fitted to the rod 14. The plunger 28 is slidable along the small diameter inner diameter surface 13 a formed on the outer diameter surface of the rod 14 and the inner peripheral upper portion of the valve sleeve 13, and is cylindrical between the sliding surfaces of the rod 14 and the plunger 28. A first leak gap 31 is formed. In addition, a cylindrical second leak gap 32 is provided between the sliding surfaces of the plunger 28 and the valve sleeve 13.

  The gap amount of the second leak gap 32 is smaller than the gap amount of the first leak gap 31, and the flow path resistance of the second leak gap 32 becomes larger than the flow path resistance of the first leak gap 31 from the difference in the gap amount. There is.

  Each of the first leak gap 31 and the second leak gap 32 causes the hydraulic damper action in the pressure chamber 15 by the viscous resistance when the oil in the pressure chamber 15 leaks along the respective leak gaps 31, 32. It is supposed to be.

  The first leak gap 31 is set to a size that can absorb the tension fluctuation of the belt 54 during the normal operation of the engine shown in FIG. 9A by the hydraulic damper action caused by the oil leak. On the other hand, the second leak gap 32 is set to such a size that the rod 14 is not rapidly pushed in when the engine is started by the drive of the starter / generator 52 shown in FIG. 9B.

  As shown in FIG. 2, a stopper 34 is provided at the lower end portion of the rod 14 for retaining the plunger 28. Here, a retaining ring is employed as the stopper 34 and is attached to a ring groove 33 provided at the lower end of the rod 14.

  Here, the stopper 34 formed of the retaining ring has the separation part 34a in a part in the circumferential direction, and the pressure chamber 15 and the first leak gap 31 are always in communication via the separation part 34a.

  Between the rod 14 and the plunger 28, there is provided a second check valve 35 for closing the first leak gap 31 when the pressure rises at the time of engine start by the drive of the starter generator 52 (see FIG. 9).

  The second check valve 35 is provided with a large diameter shaft portion 14a at the upper part positioned from the upper end of the plunger 28 of the rod 14 to the outside, and a convex curved valve seat 35a is provided at the lower end portion of the large diameter shaft portion 14a The seat surface 35b formed of a tapered flat surface is formed on the upper inner diameter surface of the plunger 28, and when the plunger 28 is lifted by the pressure in the pressure chamber 15, as shown in FIG. The upper end opening of the first leak gap 31 is closed by being seated.

  Here, the valve seat 35a formed on the large diameter shaft portion 14a is surface-hardened to increase its strength, and its surface hardness is harder than the surface hardness of the seat surface 35b of the plunger 28. Here, DLC treatment is applied as the surface hardening treatment, but instead of the DLC treatment, a hard coating may be applied or shot peening may be applied.

  As described above, when the surface hardness of the convexly curved valve seat 35a is made harder than the surface hardness of the flat sheet surface 35b, the valve seat 35a and the valve seat 35a are initially used as shown in FIG. The seat surface 35b is in line contact, and the elastic deformation of the contact portion allows the second check valve 35 to be completely closed. On the other hand, by using the second check valve 35 repeatedly by opening and closing, plastic deformation is generated in the seat surface 35b to make it fit, and as shown in FIG. 4 (b), the convex curved surface of the valve seat 35a In the state of surface contact, the second check valve 35 can be completely closed.

  In FIG. 4A, the valve seat 35a is made convex and harder than the surface hardness of the seat surface 35b made of a flat surface, but the seat surface 35b is made convex and the valve seat 35a is made a tapered flat surface. The surface hardness of the seat surface 35b may be harder than the surface hardness of the valve seat 35a.

  In the embodiment, the second check valve 35 is provided on the upper end side of the plunger 28. Alternatively, the second check valve 35 may be provided on the inside of the plunger 28 or on the lower end side of the plunger 28. .

  As shown in FIGS. 1 and 2, an outward flange 29 is provided on the top of the plunger 28, and a valve spring 37 is incorporated between the flange 29 and the facing surface of the spring seat 16. The valve spring 37 biases the plunger 28 toward the aforementioned stopper 34 mounted on the lower end of the rod 14.

  Although a coil spring is employed as the valve spring 37 in FIG. 2, it may be a disc spring as shown in FIG. 5, or may be a wave washer as shown in FIG. Furthermore, as shown in FIG. 7, it may be a wave spring. When a corrugated washer is employed, as shown in FIG. 6, a plain washer 38 is interposed between the overlapping portions of the plurality of corrugated washers 37.

  As shown in FIG. 2, a ring-shaped tapered groove 39 having a large diameter at the lower portion is provided in the outer peripheral lower portion of the plunger 28, and the retaining ring 40 is attached in the tapered groove 39. The outer diameter of the retaining ring 40 in the natural state is larger than the outer diameter of the plunger 28 so that the outer peripheral portion is located outside the outer diameter surface of the plunger 28 and is formed on the inner peripheral upper portion of the valve sleeve 13 The contact of the lower end of the small diameter inner diameter surface 13a with the step 13b prevents the plunger 28 and the rod 14 from coming out of the upper end of the valve sleeve 13 upward.

  The hydraulic auto-tensioner shown in the embodiment has the above-described configuration, and is provided at the closed end of the cylinder 10 when incorporated into the accessory drive belt drive of the engine equipped with the idle stop mechanism shown in FIG. The connecting piece 11 is connected to the pulley arm 56, and the connecting piece 18 of the spring seat 16 is connected to the engine block to apply an adjusting force to the pulley arm 56.

  In the tension adjustment state of the belt 54 as described above, when the tension of the belt 54 changes due to the load fluctuation of the accessory 53 or the like in the normal operation state of the engine and the tension of the belt 54 becomes weak, the pressure of the return spring 17 The cylinder 10 and the spring seat 16 move relative to each other in the direction in which the cylinder 10 and the spring seat 16 extend to absorb slack of the belt 54.

  Here, when the cylinder 10 and the spring seat 16 relatively move in the extending direction, the pressure in the pressure chamber 15 becomes lower than the pressure in the reservoir chamber 24, so the first check valve 27 opens. Therefore, the oil in the reservoir chamber 24 smoothly flows from the oil passage 25 through the oil reservoir 26 and into the pressure chamber 15, and the cylinder 10 and the spring seat 16 move smoothly relative to each other in the extension direction to loosen the belt 54. Absorb immediately.

  On the other hand, when the tension of the belt 54 becomes strong, the pushing force in the direction of contracting the cylinder 10 and the spring seat 16 of the hydraulic auto tensioner is applied from the belt 54. At this time, since the pressure in the pressure chamber 15 becomes higher than the pressure in the reservoir chamber 24, the check ball 27c of the first check valve 27 closes the valve hole 27b.

  Further, the oil in the pressure chamber 15 flows through the first leak gap 31 as shown by the arrow in FIG. 2, and leaks from the upper end opening of the first leak gap 31 to the reservoir chamber 24 shown in FIG. A hydraulic damper force is generated in the pressure chamber 15 by the oil flowing through the first leak gap 31. The pressing force applied to the hydraulic auto-tensioner is buffered by the hydraulic damper force.

  At this time, since the first leak gap 31 is set to a size that can absorb the tension fluctuation of the belt 54 during normal operation of the engine, the tension of the belt 54 during normal operation of the engine may be too high. It is kept in proper tension.

  On the other hand, when the engine is started by driving the starter / generator 52, the tension of the belt 54 rapidly increases and the pushing force to the rod 14 acting via the spring seat 16 becomes strong, and the pressure in the pressure chamber 15 rapidly increases. . At this time, the first check valve 27 closes and the pressure in the pressure chamber 15 rises, and when the pressure becomes higher than the elastic force of the valve spring 37, the plunger 28 rises against the elasticity of the valve spring 37, As shown in FIG. 3, the seat surface 35b is seated on the valve seat 35a, and the second check valve 35 is closed.

  The upper end opening of the first leak gap 31 is closed by closing the second check valve 35, and the oil in the pressure chamber 15 flows into the second leak gap 32 as shown by the arrow in FIG. It leaks into the reservoir chamber 24.

At this time, since the flow passage resistance of the second leak gap 32 is larger than the flow passage resistance of the first leak gap 31, the oil in the pressure chamber 15 flows slowly in the second leak gap 32. For this reason, there is no rapid pressure drop in the pressure chamber 15, and the pushing action of the rod 14 is suppressed by the hydraulic damper action in the pressure chamber 15, and the belt 54 is maintained at the belt tension necessary to drive the crankshaft 51. the slip between the belt 54 and the pulleys _{P 1} to _{P 3} is prevented.

  As described above, during normal operation of the engine, the oil in the pressure chamber 15 leaks from the first leak gap 31 having a small flow path resistance to the reservoir chamber 24 while the pressure chamber is started when the engine is started by the starter generator 52. The oil in 15 leaks to the reservoir chamber 24 from the second leak gap 32 having a large flow path resistance, so that the belt 54 is properly tensioned at the normal operation of the engine and at the start of the engine by the starter generator. be able to.

  Here, if the closing of the second check valve 35 is incomplete when the engine is started by the starter / generator 52, the oil also leaks from the first leak gap 31 having a small flow path resistance, so the damper force is small. And belt slip may occur.

  However, in the embodiment, since the surface hardness of the valve seat 35a and the seat surface 35b of the second check valve 35 is different, as shown in FIG. 4A at the initial stage of use of the hydraulic autotensioner. The closing of the second check valve 35 is completed by the elastic deformation of the contact portion between the valve seat 35a and the seat surface 35b. On the other hand, by using the second check valve 35 repeatedly by opening and closing, plastic deformation is generated in the seat surface 35b to make it fit, and as shown in FIG. 4B, the convex curved surface of the valve seat 35a In the state of surface contact, the closing of the second check valve 35 is completed. Therefore, the belt 54 does not slip when the engine is started by the drive of the starter generator 52 shown in FIG. 9 (b).

  FIG. 8 shows a measurement example comparing the reaction force characteristic of the hydraulic autotensioner of the above embodiment (hereinafter referred to as “implementation product”) with the reaction force characteristic of a conventional hydraulic autotensioner (hereinafter referred to as “conventional product”). Indicates It will be described below.

  As an implementation item, the tensioner described in the above embodiment was used. That is, as shown in FIGS. 1 and 2, a bottomed cylindrical cylinder 10, a valve sleeve 13 extending upward from the bottom surface of the cylinder 10, and a plunger slidably inserted into the valve sleeve 13 in the vertical direction. 28, a rod 14 slidably inserted into the plunger 28 up and down, a pressure chamber 15 surrounded by the valve sleeve 13, the rod 14 and the plunger 28, and a sliding surface of the rod 14 and the plunger 28 The first cylindrical leak space 31, the cylindrical second leak space 32 formed between the sliding surfaces of the plunger 28 and the valve sleeve 13, the spring seat 16 fixed to the upper end of the rod 14, and A return spring 17 biasing the spring seat 16 upward with respect to the cylinder 10, a valve spring 37 biasing the plunger 28 downward, and a rod 4 has a valve seat 35a as an upper stopper for restricting the upward movement range of the plunger 28 with respect to the point 4 and a retaining ring as a lower stopper 34 for restricting the downward movement range of the plunger 28 relative to the rod 14 Used a tensioner. Then, with the cylinder 10 fixed, the spring seat 16 was vibrated up and down, and the change in the upward force (tensioner reaction force) acting on the spring seat 16 was measured.

  Further, as a conventional product, a tensioner shown in FIG. 1 of JP-A-2009-275757 (a tensioner having no member corresponding to the plunger 28 of the embodiment product, the rod 14 slides directly on the valve sleeve 13) was used.

The excitation conditions are as follows.
Control method: Displacement control Excitation waveform: Sine wave Excitation frequency: 10 Hz

  The displacement control controls the displacement of the spring seat 16 so that the temporal change in the position of the spring seat 16 becomes a sine wave, regardless of how the force (tensioner reaction force) acting on the spring seat 16 increases or decreases. It is a control method. The amplitude of the excitation was ± 0.5 mm, which is larger than the amplitude (for example, about ± 0.1 mm to ± 0.2 mm) applied to the tensioner during normal operation of the engine. Both the embodiment and the conventional use a return spring 17 having a spring coefficient of about 35 N / mm.

  The relationship between the tensioner displacement (downward displacement of the spring seat 16) and the tensioner reaction force (upward force acting on the spring seat 16) obtained by the above-described vibration test is shown in FIG.

  As shown in FIG. 8, in the embodiment, in the process of contraction of the tensioner, the reaction force of the tensioner changes in three strokes of rapid, gentle and sudden. That is, in the process of contraction of the tensioner, the tensioner reaction force of the implemented product almost increases with the first stroke (point P1 to point P2) which relatively rapidly increases starting from the minimum value (point P1) of the tensioner reaction force. The maximum tensioner reaction force (the point P2 to the point P3) and the relatively rapid increase of the third stroke (the point P3 to the point P4) are maintained in this order. It changes to point P4).

  Thereafter, in the implemented product, in the process of extension of the tensioner, the tensioner reaction force changes in four strokes of rapid, gentle, rapid and gentle. That is, in the process of extension of the tensioner, the tensioner reaction force of the implemented product is almost reduced to the first stroke (point P4 to point P5) which decreases relatively rapidly starting from the maximum value (point P4) of the tensioner reaction force. The second stroke (point P5 to point P6) that maintains a substantially constant size without causing a problem and the third stroke (point P6 to point P7) that decreases relatively rapidly It changes to the minimum value (point P1) of a tensioner reaction force through the 4th stroke (point P7-point P1) which maintains tension in order.

  On the other hand, in the conventional product, the tensioner reaction force increases approximately monotonically from the minimum value (point Q1) to the maximum value (point Q2) in the process of contraction of the tensioner. Further, in the conventional product, in the process of tensioner extension, the tensioner reaction force changes in a two-step stroke of rapid and loose. That is, in the process of extension of the tensioner, the tensioner reaction force of the conventional product is almost reduced to the first stroke (point Q2 to point Q3) which decreases relatively rapidly starting from the maximum value (point Q2) of the tensioner reaction force. The second stroke (point Q3 to point Q1) maintaining a substantially constant magnitude without passing is sequentially changed to the minimum value (point Q1) of the tensioner reaction force.

  That is, in the tensioner of the implemented product, in the process of contraction of the tensioner, a change point P2 at which the increase rate of the tensioner reaction changes from sudden to loose and a change point P3 at which the increase rate of the tensioner reactive changes from loose to rapid in order The reaction force characteristic which it has is shown. In the tensioner of the embodiment, in the process of extension of the tensioner, a change point P5 at which the reduction rate of the tensioner reaction changes from sudden to moderate, a change point P6 at which the reduction rate of the tensioner reaction changes from gentle to rapid, The reaction force characteristic which has a change point P7 in which the decreasing rate of reaction force changes from sudden to gentle is shown in order.

  The reason why the tensioner of the embodiment shows the reaction force characteristic will be described with reference to FIG. 1, FIG. 2, and FIG.

<Point P1 to Point P2>
The rod 14 shown in FIG. 2 starts to descend. At this time, since the plunger 28 is urged downward by the valve spring 37 and pressed by the stopper 34, the plunger 28 is also lowered integrally with the rod 14. When the plunger 28 and the rod 14 are integrally lowered, a part of the oil in the pressure chamber 15 flows out of the pressure chamber 15 through the first leak gap 31, and the oil in the pressure chamber 15 is compressed. When the oil in the pressure chamber 15 is compressed, the pressure of the oil in the pressure chamber 15 is increased, and the tensioner reaction force is relatively rapidly increased (point P1 to point P2 in FIG. 8). Then, at point P2 in FIG. 8, the upward pressure acting on the plunger 28 from the oil in the pressure chamber 15 and the downward biasing force acting on the plunger 28 from the valve spring 37 are balanced.

<Point P2 to Point P3>
The rod 14 shown in FIG. 2 is further lowered. At this time, the upward pressure acting on the plunger 28 from the oil in the pressure chamber 15 exceeds the downward biasing force acting on the plunger 28 from the valve spring 37, whereby the plunger 28 is raised. During this time, the pressure rise of the pressure chamber 15 is suppressed by raising the plunger 28, and the tensioner reaction force becomes substantially constant (point P2 to point P3 in FIG. 8). That is, since the plunger 28 ascends as the rod 14 descends, the volume of the pressure chamber 15 hardly changes, and the pressure in the pressure chamber 15 becomes almost constant. At this time, since the volume of the pressure chamber 15 hardly changes, almost no oil flows in the first leak gap 31 and the second leak gap 32. Then, at point P3 in FIG. 8, as shown in FIG. 3, the seat surface 35b is seated on the valve seat 35a, and the lifting of the plunger 28 is stopped.

<Point P3 to Point P4>
The rod 14 shown in FIG. 3 is further lowered. At this time, as shown in FIG. 3, since the seat surface 35b is seated on the valve seat 35a, the plunger 28 is also lowered integrally with the rod 14. When the plunger 28 and the rod 14 descend integrally, the oil in the pressure chamber 15 is further compressed, so the pressure of the oil in the pressure chamber 15 increases again, and the tensioner reaction force increases again (see FIG. 8). Point P3 to point P4). At this time, as shown in FIG. 3, since the seat surface 35b is seated on the valve seat 35a, the oil does not flow in the first leak gap 31, and a part of the oil in the pressure chamber 15 is the second leak gap. It flows out of the pressure chamber 15 through 32.

<Point P4 to Point P5>
The rod 14 shown in FIG. 3 starts to ascend. At this time, since the upward pressure acting on the plunger 28 from the oil in the pressure chamber 15 exceeds the downward biasing force acting on the plunger 28 from the valve spring 37, the plunger 28 also rises integrally with the rod 14. When the plunger 28 and the rod 14 are integrally raised, the compression of the oil in the pressure chamber 15 is gradually released, so the pressure of the oil in the pressure chamber 15 decreases and the tensioner reaction force relatively decreases (see FIG. 8 points P4 to P5). At this time, compression of the oil in the pressure chamber 15 is released (that is, the oil in the pressure chamber 15 expands) and the volume of the oil in the pressure chamber 15 increases. Hardly flows. Further, as shown in FIG. 3, since the seat surface 35 b is seated on the valve seat 35 a, the oil does not flow to the first leak gap 31. Then, at point P5 in FIG. 8, the upward pressure acting on the plunger 28 from the oil in the pressure chamber 15 and the downward biasing force acting on the plunger 28 from the valve spring 37 are balanced.

<Point P5 to Point P6>
The rod 14 shown in FIG. 3 is further raised. At this time, the upward pressure acting on the plunger 28 from the oil in the pressure chamber 15 is lower than the downward biasing force acting on the plunger 28 from the valve spring 37, whereby the plunger 28 is lowered. During this time, the pressure drop of the pressure chamber 15 is suppressed by lowering the plunger 28, and the tensioner reaction force becomes substantially constant (point P5 to point P6 in FIG. 8). That is, since the plunger 28 descends with the rise of the rod 14, the volume of the pressure chamber 15 hardly changes, and the pressure in the pressure chamber 15 becomes almost constant. At this time, as in the points P4 to P5, the volume of the oil in the pressure chamber 15 is increased by releasing the compression of the oil in the pressure chamber 15 (that is, the oil in the pressure chamber 15 expands). Therefore, almost no oil flows in the first leak gap 31 and the second leak gap 32. Then, at point P6 in FIG. 8, as shown in FIG. 2, the downward movement of the plunger 28 is blocked by the stopper 34, and the lowering of the plunger 28 is stopped.

<Point P6 to Point P7>
The rod 14 shown in FIG. 2 further rises. At this time, as shown in FIG. 2, since the downward relative movement of the plunger 28 with respect to the rod 14 is blocked by the stopper 34, the plunger 28 is also lifted integrally with the rod 14. When the plunger 28 and the rod 14 are integrally raised, the compression of the oil in the pressure chamber 15 is further released, so the pressure of the oil in the pressure chamber 15 starts to decrease again and the tensioner reaction force decreases again ( Points P6 to P7 in FIG. 8). At this time, as in the points P4 to P5, the volume of the oil in the pressure chamber 15 is increased by releasing the compression of the oil in the pressure chamber 15 (that is, the oil in the pressure chamber 15 expands). Therefore, almost no oil flows in the first leak gap 31 and the second leak gap 32. Then, at point P7 in FIG. 8, the pressure of the oil in the pressure chamber 15 shown in FIG. 1 decreases to a pressure equivalent to the oil in the reservoir chamber 24, and the compression of the oil in the pressure chamber 15 is completely released. It becomes a state.

<Point P7 to Point P1>
The rod 14 shown in FIG. 1 is further raised. At this time, since the downward relative movement of the plunger 28 with respect to the rod 14 is blocked by the stopper 34, the plunger 28 is also lifted integrally with the rod 14. When the plunger 28 and the rod 14 move up integrally, the pressure of the oil in the pressure chamber 15 falls below the pressure in the reservoir chamber 24 so that the first check valve 27 opens and the oil passes from the reservoir chamber 24 through the oil passage 25. It flows into the pressure chamber 15. Therefore, the pressure of the oil in the pressure chamber 15 hardly changes, and the tensioner reaction force becomes almost constant (point P7 to point P1 in FIG. 8).

  As described above, in the embodiment, when the tensioner reaction force reaches a predetermined value (the value at point P2 in FIG. 8) in the process of contraction of the tensioner, the plunger 28 ascends to change the volume of the pressure chamber 15 During this time, the tensioner reaction force becomes substantially constant (point P2 to point P3 in FIG. 8). Therefore, in the process of the tensioner contracting, the implemented product has a change point P2 at which the increase rate of the tensioner reaction changes from sudden to slow and a change point P3 at which the increase rate of the tensioner reaction changes from slow to rapid. It shows force characteristics.

  Further, in the embodiment, when the tensioner reaction force reaches a predetermined value (the value at point P5 in FIG. 8) in the process of tensioner extension, the plunger 28 descends to absorb the change in volume of the pressure chamber 15 Meanwhile, the tensioner reaction force becomes substantially constant (point P5 to point P6 in FIG. 8). Therefore, in the process of tensioner extension, the implemented product has a change point P5 at which the reduction rate of the tensioner reaction decreases rapidly and gradually and a change point P6 at which the reduction rate of the tensioner reaction changes gradually to the sudden change. It shows force characteristics.

By having the above-described reaction force characteristic, the tensioner of the embodiment suppresses the magnitude of the tensioner reaction force to a small value during normal operation of the engine, and the tension applied to the belt 54 by the tension pulley 55 shown in FIG. can be suppressed small, whereas, at the time of starting the engine by driving the starter generator 52, a large tensioners to generate a reaction force, slip between the belt 54 and the pulley P ₂ shown in effectively Figure 9 (b) It can be prevented.

  That is, during normal operation of the engine, the tensioner is displaced at an amplitude smaller than ± 0.5 mm (for example, an amplitude of approximately ± 0.1 mm to ± 0.2 mm) as indicated by symbol S1 in FIG. At this time, the tensioner reaction force increases from the point P1 through the point P2 to a value between the point P2 and the point P3 in the process of contraction of the tensioner, and then in the process of extension of the tensioner, the point P2 Starting from the point between P. and P.sub.3, it decreases to the value between P.sub.5 and P.sub.6, and then decreases to P.sub.1 through point P.sub.6 and P.sub.7 in order. Thus, when the tensioner of the embodiment is used, the maximum value of the tensioner reaction force can be suppressed to a value between the point P2 and the point P3 during the normal operation of the engine, and the tension pulley 55 shown in FIG. However, the tension applied to the belt 54 can be reduced to reduce the fuel consumption of the engine.

On the other hand, at the time of engine start by the drive of the starter generator 52, the tensioner contracts to the maximum value of the amplitude of ± 0.5 mm or in the vicinity thereof as shown by symbol S2 in FIG. At this time, the tensioner reaction force increases to or near the point P4. Therefore, when starting the engine by driving the starter generator 52, greater tensioner reaction force can be generated, it is possible to effectively prevent the slippage between the belt 54 and the pulley P ₂ shown in FIG. 9 (b) .

  On the other hand, in the conventional tensioner, the tension of the belt 54 tends to be excessive during normal operation of the engine. That is, when the tensioner is displaced with the amplitude indicated by the symbol S1 in FIG. 8, in the process of contraction of the tensioner, the tensioner reaction force increases from the point Q1 to a value between the point Q1 and the point Q2, and then In the process of extension of the tensioner, starting from the value between point Q1 and point Q2, it decreases to the value between point Q3 and point Q1, and further decreases to point Q1. As described above, when the conventional tensioner is used, the maximum value of the tensioner reaction force increases to a value between the point Q1 and the point Q2 during the normal operation of the engine, so the tension pulley 55 shown in FIG. The tension applied to the belt 54 is likely to be excessive, and it is difficult to reduce the fuel consumption of the engine.

Further, in the conventional tensioner, it is difficult to generate a large tensioner reaction force at the time of engine start by the drive of the starter generator 52. That is,
When the tensioner contracts to the maximum value of the amplitude of ± 0.5 mm shown by symbol S2 in FIG. 8 or in the vicinity thereof, the tensioner reaction force increases only to the point Q2 or the vicinity thereof. Therefore, when the engine is started by driving the starter generator 52, a large tensioner it is difficult to generate a reaction force, slip is likely to occur between the belt 54 and the pulley P ₂ shown in Figure 9 (b).

10 cylinder 13 valve sleeve 14 rod 15 pressure chamber 16 spring seat 17 return spring 24 reservoir chamber 25 oil passage 27 first check valve 28 plunger 31 first leak gap 32 second leak gap 34 stopper 35 second check valve 35a valve seat 35b Seat surface 37 valve spring

Claims (5)

A valve sleeve (13) is erected on the bottom surface of the bottomed cylinder (10), and the lower end of the rod (14) is slidably inserted into the valve sleeve (13) so that the inside of the valve sleeve (13) is And a pressure chamber (15) between the spring seat (16) provided on the top of the rod (14) and the bottom surface of the cylinder (10) in the direction to extend the spring seat (16) and the cylinder (10). Incorporate a biasing return spring (17) and communicate the lower part of the reservoir chamber (24) formed between the inner periphery of the cylinder (10) and the outer periphery of the valve sleeve (13) with the lower part of the pressure chamber (15) An oil passage (25) is formed, and closed in the lower end portion of the valve sleeve (13) when the pressure in the pressure chamber (15) becomes higher than the pressure in the reservoir chamber (24) to close the pressure chamber (15) and the oil passage. Block the communication of (25) First check valve (27), and when the pressing force is applied to the rod (14) through the spring seat (16), the first check valve (27) is closed and the pressure chamber (15) is closed. In a hydraulic auto-tensioner in which oil is leaked to a reservoir chamber (24) and a pressing force applied to a rod (14) is buffered by a hydraulic damper action by oil in a pressure chamber (15).
A slidable cylindrical plunger (28) is fitted between the outer diameter surface of the rod (14) and the inner diameter surface of the valve sleeve (13) to slide the plunger (28) and the rod (14) A first leak gap (31) is provided between the moving surfaces, and a second leak having a larger flow resistance than the first leak gap (31) between the sliding surfaces of the plunger (28) and the valve sleeve (13). A gap (32) is provided, and the first leak gap (31) is formed between the rod (14) and the plunger (28) when the plunger (28) rises due to pressure increase in the pressure chamber (15). A second check valve (35) for closing the valve, and a valve spring (37) for biasing the plunger (28) toward a stopper (34) provided at the lower end of the rod (14). Provided, the second check Hydraulic auto-tensioner which is characterized in that with a difference in the surface hardness of the valve the valve seat (35a) and the seat surface of the (35) (35b).   The second check valve (35) is provided with a valve seat (35a) at the lower end of the large diameter shaft portion (14a) located outside the upper end of the plunger (28) of the rod (14), and the plunger (28) The hydraulic auto-tensioner according to claim 1, wherein a seat surface (35b) capable of being seated on the valve seat (35a) is provided on the upper inner diameter surface of.   The hydraulic auto-tensioner according to claim 1 or 2, wherein one of the valve seat (35a) and the seat surface (35b) of the second check valve (35) is a convex surface and the other is a flat surface.   The hydraulic auto-tensioner according to claim 3, wherein the member on the convex curved surface side has high hardness.   The hydraulic auto-tensioner according to claim 1, wherein the valve spring (37) comprises one of a coil spring, a disc spring, a wave washer and a wave spring.

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