JP2012172823A - Hydraulic auto-tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic auto-tensioner capable of having a large attachment inclination angle.SOLUTION: A connection piece 2 attached to the lower surface of a bottom is connected to an engine block in a freely swingable manner, a sleeve fitting hole 3 is formed at the upper surface of the bottom of a cylinder 1 the interior of which is filled with hydraulic oil, and a rod 5 is inserted into a sleeve 4 the lower end of which is inserted into the sleeve fitting hole 3. A pressure chamber 6 provided in the sleeve 4 and a reservoir chamber 14 provided outside the sleeve 4 communicate with each other via an oil passage 15 formed between the sleeve fitting hole 3 and fitting surfaces of the sleeve 4. The phase of the upper opening 15c of the oil passage 15 is shifted in the circumferential direction from a reference line x-x which passes through the center of an upper opening of the sleeve fitting hole 3 and extends in a direction in which the tensioner can swing so that the attachment inclination angle of the hydraulic auto-tensioner can be increased.

Description

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

  As shown in FIG. 7, in a belt transmission device for transmitting the rotation of the crankshaft of an engine to various automobile accessories, a swingable pulley arm 33 for supporting a tension pulley 32 is provided on the slack side of the belt 31, and the pulley arm The adjustment force of the hydraulic auto tensioner A is applied to 33 to urge the pulley arm 33 in the direction in which the tension pulley 32 presses the belt 31 so that the tension of the belt 31 is kept constant.

  As a hydraulic auto tensioner A used for the belt transmission as described above, one described in Patent Document 1 has been conventionally known. 8 and 9 show the hydraulic auto tensioner described in Patent Document 1, in which a sleeve fitting hole 3 is provided on the upper surface of the bottom of the bottomed cylinder 1 filled with hydraulic oil, and the sleeve fitting hole 3 The lower portion of the rod 5 is slidably inserted into the sleeve 4 having the lower end inserted therein to form a pressure chamber 6 in the sleeve 4, and the spring seat 7 provided on the upper portion of the rod 5 and the bottom of the cylinder 1. A return spring 8 is incorporated between the upper surfaces to urge the rod 5 and the cylinder 1 in the extending direction.

  Further, a cylindrical spring cover 11 covering the upper part of the return spring 8 is provided at the lower part of the spring seat 7 so that the inner periphery of the seal member 13 incorporated in the upper opening of the cylinder 1 is brought into elastic contact with the outer periphery of the spring cover 11. A reservoir chamber 14 sealed between the cylinder 1 and the sleeve 4 is formed, and the reservoir chamber 14 and the pressure chamber 6 are formed between the fitting surfaces of the sleeve fitting hole 3 and the sleeve 4 through an oil passage 15, A check valve 17 is incorporated in the lower end opening of the sleeve 4.

  In the hydraulic auto tensioner having the above-described configuration, the connecting piece 2 provided on the bottom lower surface of the cylinder 1 is rotatably connected to the engine block, and the connecting piece 9 provided on the upper surface of the spring seat 7 is shown in FIG. When the pushing force in the direction of contracting the cylinder 1 and the rod 5 is applied from the belt 31 via the tension pulley 32 and the pulley arm 33, the check valve 17 is closed and the pressure chamber 6 is closed. The sealed hydraulic fluid is caused to flow through a minute gap 21 formed between the inner diameter surface of the sleeve 4 and the outer diameter surface of the rod 5, and a hydraulic damper force is generated in the pressure chamber 6 due to the viscous resistance of the hydraulic fluid at the time of the flow. Thus, the pushing force is buffered.

  Here, if the amount of hydraulic oil sealed in the cylinder 1 is too large, hydraulic oil may leak due to an increase in internal pressure due to an increase in ambient temperature when the auto tensioner contracts most.

  In view of this, in the conventional hydraulic auto tensioner, the amount of hydraulic oil enclosed is set to be less than 50% of the internal volume in the most contracted state of the auto tensioner in which the cylinder 1 and the rod 5 are relatively contracted relative to each other. The amount of hydraulic oil filled less than 50% substantially corresponds to 32% of the internal volume in the maximum extension state of the auto tensioner in which the cylinder 1 and the rod 5 are extended most.

  Here, in the hydraulic auto tensioner having the gas-liquid two-layer structure as described above, the inclination angle at the time of mounting is increased, and the oil surface of the hydraulic oil is disposed below the upper opening 15 c of the oil passage 15. When the cylinder 1 and the rod 5 are extended, the air in the reservoir chamber 14 is sucked into the pressure chamber 6 when the cylinder 1 and the rod 5 are extended, and the air is compressed when contracted, so that the hydraulic damper effect cannot be exhibited.

  Therefore, the hydraulic auto tensioner needs to be assembled so that the oil level of the hydraulic oil is not disposed below the upper opening 15c of the oil passage 15 when used in an inclined assembly.

JP 2009-275757 A

  By the way, in the conventional hydraulic auto tensioner, four oil passages 15 communicating with the pressure chamber 6 and the reservoir chamber 14 are arranged in a cross shape, and one of the two oil passages 15 arranged opposite to each other. A pair passes through the center of the upper opening of the sleeve fitting hole 3 perpendicular to the axis of the sleeve 4 and extends in the radial direction xx (reference line xx) extending in the swingable direction of the auto tensioner. Since the upper openings 15c of the respective oil passages 15 are arranged on the reference line xx, the mounting inclination angle of the auto tensioner cannot be increased, and the hydraulic oil When the inclination angle α from the vertical line exceeds 45 ° in relation to the amount of sealing, there is a problem that the oil level of the hydraulic oil falls from the upper opening 15c of the oil passage 15 and is easily restricted during installation.

8 shows the inclination angle of the hydraulic auto-tensioner α is, indicates the state of less than 45 °, the oil level of the hydraulic oil is located in the upper only [delta] ₁ from the upper opening 15c of the oil passage 15.

  An object of the present invention is to provide a hydraulic auto tensioner capable of increasing a mounting inclination angle.

  In order to solve the above problems, in the present invention, a sleeve fitting hole is provided in the upper surface of the bottom of a bottomed cylinder filled with hydraulic oil, and the lower end is inserted into the sleeve fitting hole. Insert the lower end of the rod slidably to form a pressure chamber in the sleeve, and urge the cylinder and rod in the direction of extension between the spring seat provided on the upper part of the rod and the inner bottom surface of the cylinder A return spring is installed, a cylindrical spring cover that covers the top of the return spring is provided on the spring seat, and the inner periphery of the seal member incorporated in the upper opening of the cylinder is brought into elastic contact with the outer periphery of the spring cover. The upper opening of the reservoir chamber formed between the cylinder and the sleeve is sealed, and the reservoir chamber and the pressure chamber are placed between the sleeve and the fitting surface of the sleeve fitting hole. An oil passage is provided, and a check valve is provided in a lower surface of the bottom of the cylinder, and a check valve is provided in the lower end of the sleeve that closes when the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber and blocks communication between the pressure chamber and the oil passage In the hydraulic auto tensioner in which the connected piece is pivotally connected to the engine block, swingable about the connecting portion, and can be assembled in an inclined manner, the axial center of the sleeve A radial line extending in the swinging direction of the tensioner that can swing around the connecting portion and passing through the center of the upper opening of the sleeve fitting hole orthogonally with the reference line as a reference line, phase from the reference line to the circumferential direction A configuration is adopted in which the upper end opening of the oil passage is disposed at a position shifted.

  Here, the oil passage may be composed of four oil passages arranged in a plane cross shape, or may be composed of two oil passages arranged opposite to each other. When the number of oil passages is four, the upper end opening of each oil passage is arranged at a position shifted by 45 ° in the circumferential direction with respect to the reference line, and the number of oil passages is two. The upper end opening of each oil passage is arranged at a position shifted by 90 ° in the circumferential direction with respect to the reference line.

  In the present invention, as described above, the reference line is a radial straight line that is orthogonal to the axis of the sleeve and extends in the swingable direction of the tensioner through the center of the upper opening of the sleeve fitting hole. Compared to the conventional auto tensioner in which the upper end opening of the oil passage is arranged on the reference line by arranging the upper end opening of the oil passage at a position shifted in the circumferential direction from the line, the auto tensioner is installed. Therefore, it is possible to provide an auto tensioner that is less subject to restrictions during installation.

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 a part of FIG. Sectional view along line III-III in Fig. 2 Sectional view along line IV-IV in FIG. Cross-sectional view showing another embodiment of the hydraulic auto tensioner according to the present invention 1 is a longitudinal sectional view showing an example of use of the hydraulic auto tensioner shown in FIG. 1 in an inclined state. Front view showing a tension adjusting device for an auxiliary machine driving belt A longitudinal sectional view showing a conventional hydraulic auto tensioner Sectional view along line IX-IX in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. As shown in FIG. 1, the cylinder 1 has a bottom, and a connecting piece 2 connected to the engine block is provided on the bottom of the cylinder 1.

  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 threadedly engaged with the engine block, and the cylinder 1 is swingably mounted around the fulcrum shaft 2b. The

  A sleeve fitting hole 3 is provided on the upper surface of the bottom of the cylinder 1, and a lower end portion of a steel sleeve 4 is press-fitted into the sleeve fitting hole 3. The lower portion of the rod 5 is slidably inserted into the sleeve 4, and the pressure chamber 6 is provided in the sleeve 4 by the insertion of 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 pulley arm 33 shown in FIG. 7 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 pulley arm 33 by a bolt inserted into the sleeve 9b.

  The spring seat 7 is formed of a molded product, and a cylindrical dust cover 10 covering the outer periphery of the upper portion of the cylinder 1 and a cylindrical spring cover 11 covering the upper portion of the return spring 8 are simultaneously molded to form the spring seat 7. It 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 hydraulic oil filled in the inside 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 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 sleeve 4 and a circular recess formed in the center of the bottom surface of the sleeve fitting hole 3. 16 to communicate with each other.

  As shown in FIGS. 2 to 4, the oil passage 15 includes an axial groove 15 a and a radial groove 15 b that extends radially inward from the lower end of the axial groove 15 a and communicates with the oil reservoir 16. The upper opening 15c of the axial groove 15a has a long hole shape facing outward in the radial direction.

  There are four oil passages 15, and the four oil passages 15 are arranged in a plane cross shape, and the upper openings 15 c of the respective oil passages 15 are arranged on a reference line xx as shown in FIG. 3. In contrast, the position is shifted by 45 ° in the circumferential direction.

  Here, the reference line xx refers to an auto tensioner that can swing about the fulcrum shaft 2b shown in FIG. 1 through the center of the upper opening of the sleeve fitting hole 3 perpendicular to the axis of the sleeve 4. A radial straight line extending in the swing direction (a straight line in the tilt direction when the auto tensioner is tilted about the fulcrum shaft 2b).

  As shown in FIG. 2, a check valve 17 is incorporated in the lower end portion of the sleeve 4. When the pressure in the pressure chamber 6 becomes higher than the pressure in the reservoir chamber 14, the check valve 17 closes and disconnects the communication between the pressure chamber 6 and the oil passage 15, and the hydraulic oil in the pressure chamber 6 passes through the oil passage 15. It is prevented from flowing through to the reservoir chamber 14.

  The rod 5 is formed with a ring groove 18 at a lower end portion located in the sleeve 4, and a retaining ring 19 fitted in the ring groove 18 is brought into contact with a step portion 20 formed at the upper inner periphery of the sleeve 4. The rod 5 is prevented from being pulled out.

  Here, the amount of hydraulic oil filled in the cylinder 1 is set to be less than 70 to 85% of the internal volume in the most contracted state of the auto tensioner in which the cylinder 1 and the rod 5 are most contracted. The amount of the hydraulic oil sealed in the range of 70 to 85% substantially corresponds to 40 to 60% of the internal volume in the maximum extension state of the auto tensioner in which the cylinder 1 and the rod 5 are extended most.

  The volume of the oil sump 16 provided on the bottom surface of the sleeve fitting hole 3 is 10 to 20% of the maximum amount of hydraulic oil sealed, and the cylinder 1 and the rod 5 are rapidly expanded to increase the volume of the pressure chamber 6. When the oil pressure suddenly increases, the hydraulic oil in the oil reservoir 16 is sent to the pressure chamber 6 so that the supply of the hydraulic oil to the pressure chamber 6 is not short.

  The hydraulic auto tensioner shown in the embodiment has the above-described configuration. When adjusting the tension of the accessory driving belt 31 shown in FIG. 7, the connecting piece 2 provided at the closed end of the cylinder 1 is connected to the engine block. In addition, the connecting piece 9 of the spring seat 7 is connected to the pulley arm 33, and an adjustment force is applied to the pulley arm 33.

  In the tension adjustment state of the belt 31 as described above, when the tension of the belt 31 changes due to a load change of the auxiliary machine and the tension of the belt 31 becomes weak, the cylinder 1 and the rod 5 are expanded by the pressing of the return spring 8. The slack of the belt 31 is absorbed by relative movement in the direction.

  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 opens the oil passage 15. For this reason, the hydraulic oil in the reservoir chamber 14 smoothly flows from the oil passage 15 into the pressure chamber 6, and the cylinder 1 and the rod 5 smoothly move relative to each other in the extending direction to immediately absorb the slack of the belt 31.

  On the other hand, when the tension of the belt 31 is increased, a pushing force in a direction of contracting the cylinder 1 and the rod 5 of the hydraulic auto tensioner from the belt 31 is loaded. 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 to block communication between the pressure chamber 6 and the oil passage 15.

  Further, the hydraulic oil in the pressure chamber 6 flows into the minute gap 21 formed between the inner diameter surface of the sleeve 4 and the outer diameter surface of the rod 5 and flows into the reservoir chamber 14. The hydraulic damper generates a hydraulic damper force in the pressure chamber 6 due to the viscous resistance, and the hydraulic damper force buffers the pushing force applied to the hydraulic auto tensioner, and the cylinder 1 and the rod 5 have a pushing force and a return spring. Relatively moves slowly in the direction of contraction to the position where the elastic force of 8 is balanced.

As shown in the embodiment, 45 ° in the circumferential direction from a reference line xx that is orthogonal to the axis of the sleeve 4 and extends in the swingable direction of the tensioner through the center of the upper opening of the sleeve fitting hole 3. The upper opening 15c of the oil passage 15 is positioned at a position out of phase, and the amount of hydraulic oil filled in the cylinder 1 is set to the inside of the auto tensioner in which the cylinder 1 and the rod 5 are most contracted in the most contracted state. By setting the volume to less than 70 to 85% of the volume, as shown in FIG. 6, even in a mounted state in which the hydraulic auto tensioner is inclined 60 ° from the vertical line around the fulcrum shaft 2b, the oil level of the hydraulic oil is The oil passage 15 is disposed above the upper opening 15c. δ ₂ indicates the distance between the oil surface of the hydraulic oil and the upper opening 15 c of the oil passage 15.

  For this reason, in use in the inclined mounting state shown in FIG. 6, when the cylinder 1 and the rod 5 are extended, the air in the reservoir chamber 14 is not sucked into the pressure chamber 6 from the oil passage 15. Compared with the conventional hydraulic auto tensioner shown in FIG. 8, the mounting inclination angle of the auto tensioner can be increased, and an auto tensioner that is less restricted during mounting can be obtained.

  In the embodiment shown in FIGS. 1 to 4, four oil passages 15 are formed between the fitting surfaces of the sleeve 4 and the sleeve fitting hole 3, but the number of oil passages 15 is limited to four. It is not a thing.

  In FIG. 5, the number of the oil passages 15 is two, the two oil passages 15 are arranged at opposing positions, and the upper openings of the respective oil passages 15 are shifted in phase by 90 ° with respect to the reference line xx It may be arranged at the position. In this case, the inclination angle of the hydraulic auto tensioner can be further increased as compared with the case shown in FIG. 1, and the restrictions at the time of attachment can be extremely reduced.

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Connecting piece 4 Sleeve 5 Rod 6 Pressure chamber 7 Spring seat 8 Return spring 11 Spring cover 13 Oil seal (seal member)
14 Reservoir chamber 15 Oil passage 15c Upper opening 17 Check valve

Claims (3)

A sleeve fitting hole is provided on the bottom upper surface of the bottomed cylinder filled with hydraulic oil, and the lower end of the rod is slidably inserted into the sleeve with the lower end inserted into the sleeve fitting hole. A pressure chamber is formed in the sleeve, and a return spring that urges the cylinder and the rod in the extending direction is incorporated between the spring seat provided at the upper portion of the rod and the inner bottom surface of the cylinder, and the upper portion of the return spring is installed in the spring seat. An upper opening of a reservoir chamber formed between the cylinder and the sleeve is provided by elastically contacting the inner periphery of the seal member incorporated in the upper opening of the cylinder with the outer periphery of the spring cover. And an oil passage that communicates the reservoir chamber and the pressure chamber between the sleeve and the fitting surface of the sleeve fitting hole, and in the lower end portion of the sleeve, When the pressure in the force chamber becomes higher than the pressure in the reservoir chamber, a check valve is provided to close the communication between the pressure chamber and the oil passage, and a connecting piece provided on the bottom bottom surface of the cylinder is rotatably connected to the engine block. In the hydraulic auto tensioner which can be swung around the connecting portion and can be assembled in an inclined manner,
The reference line is defined as a reference line, which is a radial line that passes through the center of the upper opening of the sleeve fitting hole perpendicular to the axis of the sleeve and extends in the swinging direction of the tensioner that can swing around the connecting portion. A hydraulic auto tensioner, wherein an upper end opening of the oil passage is arranged at a position shifted in a circumferential direction from the oil passage.   2. The oil passage according to claim 1, wherein the oil passage includes four oil passages arranged in a plane cross shape, and an upper end opening of each oil passage is provided at a position shifted by 45 ° in the circumferential direction with respect to the reference line. Hydraulic auto tensioner.   2. The hydraulic pressure according to claim 1, wherein the oil passage is composed of two oil passages arranged opposite to each other, and an upper end opening of each oil passage is provided at a position shifted by 90 ° in the circumferential direction with respect to the reference line. Auto tensioner.

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