JP2008185216A - Hydraulic automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic automatic tensioner formed in a compact size without being restricted in a height direction. <P>SOLUTION: In this hydraulic automatic tensioner 1, an inner cylinder 7 is arranged inside of a casing 2, and a plunger 30 is inserted into the cylinder hole 7a of the inner cylinder 7. A high-pressure oil chamber 18 is formed between the end surface of the plunger 30 and the cylinder hole 7a, and a partition pipe 12 is arranged around the outer periphery of the inner cylinder 7. An oil passage 13 is formed between the outer peripheral surface of the inner cylinder 7 and the inner peripheral surface of the partition pipe 12, and a low-pressure oil chamber 19 is formed between the outer peripheral surface of the partition pipe 12 and the inner peripheral surface of the casing 2. The high-pressure oil chamber 18 and low-pressure oil chamber 19 are communicated with each other through the oil passage 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic auto tensioner for automatically applying an appropriate tension to a transmission member such as an endless annular flat belt, a V belt, a toothed belt, or a chain.

  As a conventional hydraulic auto tensioner, the one described in Japanese Utility Model Publication No. 3-13647 is known. 6 and 7 show the structure described in the publication, and an appropriate tension is applied to the V-belt 46 by the idler pulley 45. The idle pulley 45 is pivotally attached to the distal end of the arm 47, and the proximal end of the arm 47 is pivotally attached to the shaft portion 48. A hydraulic auto tensioner 50 is connected to the central portion of the arm 47 by a fixing member (not shown).

  The hydraulic auto tensioner 50 includes a bottomed cylindrical cylinder 51, a plunger 52 that enters the cylinder 51 from the opening end of the cylinder 51, and is connected to the lower end of the plunger 52 so as to move up and down with a clearance 62. A slidable piston 53 and an oil seal 54 provided at the opening end of the cylinder 51 and in sliding contact with the plunger 52 are provided, and the upper end of the plunger 52 is connected to the arm 47.

  A high pressure oil chamber 55 pressed by the piston 53 is formed in the lower part of the cylinder 51, and a low pressure oil chamber 56 is formed above the piston 53. The plunger 52 and the piston 53 are provided with a passage 57 for communicating them, and a check valve 58 is attached to the lower surface of the piston 53. A bearing 59 that can slide up and down in the cylinder 51 is attached to an upper portion of the plunger 52, and an annular spring seat 60 is supported on a stepped portion in the cylinder 51. A return spring 61 that urges the plunger 52 and the piston 53 upward is incorporated between the spring seat 60 and the bearing 59.

  In the hydraulic auto tensioner 50, when the tension of the V belt 46 becomes too small, the plunger 52 and the piston 53 move upward as shown in FIG. At this time, since the pressure in the high-pressure oil chamber 55 temporarily falls below the pressure in the low-pressure oil chamber 56, the check valve 58 releases the passage 57, and the oil passes through the passage 57 as shown by the arrow in FIG. Then, it flows from the low pressure oil chamber 56 to the high pressure oil chamber 55. On the other hand, when the tension of the V belt 46 becomes excessive, the plunger 52 and the piston 53 move downward as shown in FIG. At this time, since the oil in the high-pressure oil chamber 55 is compressed by the piston 53, the oil leaks from the high-pressure oil chamber 55 to the low-pressure oil chamber 56 via the clearance 62, as indicated by arrows in FIG.

  However, since the high-pressure oil chamber 55 and the low-pressure oil chamber 56 are arranged in series in the height direction, the hydraulic auto tensioner 50 is restricted in the height direction and there is a limit to downsizing.

  Therefore, an object of the present invention is to provide a hydraulic auto tensioner that can solve the above-described problems and can be made compact without being restricted in the height direction.

In order to achieve the above object, the hydraulic auto tensioner of the present invention is provided with an inner cylinder having an outer diameter smaller than the inner diameter of the casing inside the casing, and a plunger having a clearance in a cylinder hole formed inside the inner cylinder. In the hydraulic auto tensioner that slidably enters and forms a high-pressure oil chamber between the end face of the plunger and the cylinder hole,
A partition tube fixed to the upper outer peripheral surface of the inner cylinder is provided on the outer periphery of the inner cylinder, an oil passage is formed between the remaining outer peripheral surface of the inner cylinder and the inner peripheral surface of the partition tube, and the outer peripheral surface of the partition tube A low-pressure oil chamber is formed between the inner peripheral surface of the casing,
When the plunger is displaced in the direction of retreating from the inner cylinder, the oil is caused to flow from the low pressure oil chamber to the high pressure oil chamber via the oil passage, the communication hole provided in the plunger and the check valve for opening and closing the communication hole,
On the other hand, when the plunger is displaced in the direction of entering the inner cylinder, oil is leaked from the high pressure oil chamber to the low pressure oil chamber through the clearance and the oil passage.

Another hydraulic auto tensioner of the present invention is provided with an inner cylinder whose outer diameter is smaller than the inner diameter of the casing inside the casing, and the plunger enters the cylinder hole formed inside the inner cylinder so as to be slidable with a clearance. In a hydraulic auto tensioner that forms a high-pressure oil chamber between the end face of the plunger and the cylinder hole,
A partition tube fixed to the upper outer peripheral surface of the inner cylinder is provided on the outer periphery of the inner cylinder, an oil passage is formed between the remaining outer peripheral surface of the inner cylinder and the inner peripheral surface of the partition tube, and the outer peripheral surface of the partition tube A low-pressure oil chamber is formed between the inner peripheral surface of the casing, a horizontal hole communicating with the cylinder hole is provided in the middle part of the inner cylinder, and the middle part of the plunger above the communication hole provided in the plunger is compressed. A space is formed between the middle part and the inner cylinder, and the clearance is between the second clearance formed between the plunger and the upper part of the inner cylinder, and between the plunger and the middle part and the lower part of the inner cylinder. And a first clearance divided into two with a space in between,
When the plunger is displaced in the direction of retreating from the inner cylinder, oil flows from the low pressure oil chamber to the high pressure oil chamber through the oil passage, the lateral hole, the space, the communication hole, and the check valve that opens and closes the communication hole,
On the other hand, when the plunger is displaced in the direction of entering the inner cylinder, oil is leaked from the high pressure oil chamber to the low pressure oil chamber through the first clearance, the lateral hole, and the oil passage in this order.

  According to the hydraulic auto tensioner of the present invention, there is an excellent effect that it is possible to achieve compactness without being restricted in the height direction.

  Hereinafter, an embodiment in which a hydraulic auto tensioner of the present invention is embodied will be described with reference to FIGS. This hydraulic auto tensioner is a general-purpose product for automatically applying an appropriate tension to transmission members such as an endless annular flat belt, a V belt, a toothed belt, and a chain. The structure between the hydraulic auto tensioner and the transmission member is not particularly limited, and can be used, for example, as shown in FIG. In the figure, a V belt 40 is wound around a pulley 41 and a play pulley 42. The idler pulley 42 is pivotally attached to the distal end of the arm 43, and the proximal end of the arm 43 is pivotally attached to the shaft portion 44. The hydraulic auto tensioner 1 is connected to the central portion of the arm 43.

  The hydraulic auto tensioner 1 includes a bottomed cylindrical casing 2, and an attachment collar 3 formed integrally with the lower surface of the casing 2 is provided with an annular collar 4 rotatably via a dry bearing 5. Yes. A press-fit portion 6 having a reduced diameter is provided at the lower inner periphery of the casing 2.

  A bottomed inner cylinder 7 having an outer diameter slightly smaller than the inner diameter of the casing 2 is inserted into the casing 2, and a lower end portion thereof is press-fitted and fixed to the press-fit portion 6. Inside the inner cylinder 7 is a cylinder hole 7a into which a later-described piston portion 31 can enter. The inner cylinder 7 has an outer diameter of the middle portion 8 in the height direction smaller than that of the upper portion 9 and the lower portion 10, and left and right lateral holes 11 communicating with the cylinder hole 7 a are provided at the upper end of the middle portion 8. . A cylindrical partition tube 12 is provided on the outer periphery of the inner cylinder 7 from the upper part 9 to the middle part 8, and is fixed to the outer peripheral surface of the upper part 9. An oil passage 13 is formed between the outer peripheral surface of the middle portion 8 of the inner cylinder 7 and the inner peripheral surface of the partition tube 12. Further, the inner diameter of the upper part 9 of the inner cylinder 7 is smaller than the inner diameters of the intermediate part 8 and the lower part 10.

  The rod-like piston portion 31 provided at the lower end portion of the plunger 30 can slide up and down from the opening end portion of the casing 2 to the cylinder hole 7a of the inner cylinder 7 with the minimum clearances 14 and 15 necessary for sliding. Has entered. Here, since the inner diameter of the upper part 9 of the inner cylinder 7 is smaller than the inner diameters of the intermediate part 8 and the lower part 10 as described above, the second clearance 15 formed between the piston part 31 and the upper part 9 is the intermediate part 8. And the first clearance 14 formed between the lower portion 10 and the lower portion 10. In the figure, 16 is an engagement ring. An annular collar 4 is rotatably provided on the mounting portion 32 at the upper end of the plunger 30 via a dry bearing 5, and the collar 4 is connected to, for example, an arm 43 in FIG. 5.

  The piston portion 31 includes a communication hole 33 having a T-shaped cross section that opens at the lower end surface and the left and right outer peripheral surfaces, and a midway portion above the communication hole 33 is reduced in diameter so as to be between the inner peripheral surface of the inner cylinder 7. A space 17 is formed. A recess 34 is provided on the lower end surface of the piston portion 31, and a check valve 35 that opens and closes the communication hole 33 is attached. The check valve 35 includes a check ball 35a, a valve retainer 35b fitted in the recess 34, and a valve spring 35c that urges the check ball 35a upward.

  A high pressure oil chamber 18 is formed between the cylinder hole 7 a and the lower end surface of the piston portion 31, and a low pressure oil chamber 19 is formed between the outer peripheral surface of the partition pipe 12 and the inner peripheral surface of the casing 2. . An appropriate amount of oil is placed in the high-pressure oil chamber 18 and the low-pressure oil chamber 19. The high pressure oil chamber 18 and the low pressure oil chamber 19 can communicate in one direction from the low pressure oil chamber 19 to the high pressure oil chamber 18 through the oil passage 13, the communication hole 33, and the check valve 35. Further, the first clearance 14 is configured to allow oil to leak from the high pressure oil chamber 18 to the low pressure oil chamber 19 through the oil passage 13. Oil does not leak from the second clearance 15 that is narrower than the first clearance 14.

  At the upper part of the plunger 30 and below the attachment part 32, a long outer cylinder that has entered the opening of the casing 2, a short inner cylinder that is press-fitted into the outer periphery of the plunger 30, and a ceiling that blocks the upper ends of both cylinders A spring cover 20 integrally formed with the portion is press-fitted and fixed. A return spring 22 is mounted in a compressed state between the lower surface of the ceiling portion of the spring cover 20 and the spring seat 21 installed on the upper surface of the press-fit portion 6 to urge the plunger 30 upward. A seal ring 23 slidably contacting the outer cylinder of the spring cover 20 is attached to the stepped portion on the inner periphery of the opening end of the casing 2, and the seal ring 23 is fitted in a groove on the inner periphery of the opening end. It is locked from below so that it cannot be pulled out. Reference numeral 25 denotes an insert fitting for the seal ring 23.

  Thus, the outer cylinder of the spring cover 20 can protrude upward from the low pressure oil chamber 19 beyond the opening end of the casing 2, and a return spring is provided between the outer cylinder of the spring cover 20 and the plunger 30. Since 22 is arranged, the installation height of the return spring 22 can be secured to the maximum without increasing the height of the entire tensioner. Therefore, it is possible to use a long return spring 22 that exerts a high load while being compact, and corresponds to a tensioner for high tension (for example, a belt transmission member such as a four-cylinder engine or a diesel engine with high fluctuation torque). .

  Resin-made dust disposed on the upper end of the plunger 30 and below the attachment portion 32 from the plunger 30 to the outer periphery of the casing 2 by covering the opening end portions of the casing 2 (particularly, the spring cover 20 and the seal ring 23). A cover 26 is attached, and the dust cover 26 moves up and down together with the plunger 30. The dust cover 26 is formed integrally with a cylindrical portion 27 disposed on the outer periphery of the casing 2 and a plate-shaped lid portion 28 that closes the upper end of the cylindrical portion 27. The inner peripheral edge of the lid portion 28 is sandwiched between the flange portion 36 integrally formed on the upper portion of the plunger 30 and the upper surface of the ceiling portion of the spring cover 20, and is securely sealed.

  The operation when the auto tensioner 1 configured as described above is used as shown in FIG. 5 will be described.

  The return spring 22 always urges the plunger 30 upward. When the tension of the V-belt 40 becomes too small, the V-belt 40 allows the plunger 30 to be displaced upward by the return spring 22 via the idler pulley 42 and the arm 43. As shown in FIG. The portion 31 is displaced in the direction of exiting from the inner cylinder 7. Then, the pressure in the high-pressure oil chamber 18 temporarily drops below the pressure in the low-pressure oil chamber 19, the check valve 35 opens, and the oil in the low-pressure oil chamber 19 flows into the oil passage 13, as shown by the arrow in FIG. It flows into the high-pressure oil chamber 18 from the communication hole 33 through the horizontal hole 11 and the space 17 in order. Thus, an appropriate tension is applied to the V belt 40.

  When the tension of the V belt 40 becomes excessive due to overload or the like, the V belt 40 strongly presses the plunger 30 downward via the idler pulley 42 and the arm 43. Then, as indicated by arrows in FIGS. 2 and 4, the oil in the high-pressure oil chamber 18 passes through the first clearance 14 divided into two with the space 17 therebetween, and then passes through the horizontal hole 11 and the oil passage 13 in order. Leak to the oil chamber 19. Therefore, since the piston part 31 can be made to penetrate deeply into the inner cylinder 7, the tension of the V belt 40 can be reduced, and at the same time, changes in the belt length can be absorbed (automatic adjustment). In addition, the oil in the high pressure oil chamber 18 leaks from the first clearance 14 through the oil passage 13 to the low pressure oil chamber 19 without touching the air on the way, so that there is no possibility of entraining air. Since the second clearance 15 between the upper portion 9 of the inner cylinder 7 and the piston portion 31 is set to be narrower than the first clearance 14, the oil in the high-pressure oil chamber 18 is transferred from the second clearance 15 to the low-pressure oil at the same pressing time. There is virtually no amount of leakage into the chamber 19.

  According to the hydraulic auto tensioner 1 of the present embodiment, the partition pipe 12 is provided to form the oil passage 13, so that the low-pressure oil chamber 19 can be disposed on the outer periphery of the high-pressure oil chamber 18, and thus has a height. Compactness can be achieved without being restricted in the direction.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of invention, it can change suitably and can be actualized.

It is sectional drawing which cut | disconnects longitudinally and shows the expansion | extension state of the hydraulic auto tensioner which concerns on embodiment which actualized this invention. It is sectional drawing which shows the compression state of the same hydraulic auto tensioner by cut | disconnecting longitudinally in another position. It is a principal part expanded sectional view of FIG. It is a principal part expanded sectional view of FIG. It is the schematic which shows one example of use of a hydraulic auto tensioner. It is a partially broken front view which shows the expansion | extension state of the conventional hydraulic auto tensioner. It is a partially broken front view which shows the compression state of the hydraulic autotensioner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic type auto tensioner 2 Casing 7 Inner cylinder 7a Cylinder hole 8 Middle part 9 Upper part 10 Lower part 11 Horizontal hole 12 Partition pipe 13 Oil passage 14 First clearance 15 Second clearance 17 Space 18 High pressure oil room 19 Low pressure oil room 30 Plunger 31 Piston part 33 Communication hole 35 Check valve

Claims (2)

An inner cylinder (7) having an outer diameter smaller than the inner diameter of the casing (2) is provided inside the casing (2), and the plunger (30) has a clearance in a cylinder hole (7a) formed inside the inner cylinder (7). (14) In a hydraulic auto-tensioner that slidably enters with a high pressure oil chamber (18) between the end surface of the plunger (30) and the cylinder hole (7a),
A partition pipe (12) fixed to the outer peripheral surface of the upper part (9) of the inner cylinder (7) is provided on the outer periphery of the inner cylinder (7), and the remaining outer peripheral surface of the inner cylinder (7) and the partition pipe (12 ) Is formed between the outer peripheral surface of the partition pipe (12) and the inner peripheral surface of the casing (2). ,
When the plunger (30) is displaced in the direction of retreating from the inner cylinder (7), the oil passage (13), the communication hole (33) provided in the plunger (30), and the communication hole (33) are provided. Oil flows from the low pressure oil chamber (19) into the high pressure oil chamber (18) through a check valve (35) that opens and closes,
On the other hand, when the plunger (30) is displaced in the direction of entering the inner cylinder (7), the low pressure oil chamber (18) is moved from the high pressure oil chamber (18) through the clearance (14) and the oil passage (13). 19) A hydraulic auto tensioner which leaks oil to An inner cylinder (7) having an outer diameter smaller than the inner diameter of the casing (2) is provided inside the casing (2), and the plunger (30) has a clearance in a cylinder hole (7a) formed inside the inner cylinder (7). (14, 15) In a hydraulic auto-tensioner that slidably enters with (14, 15) and forms a high-pressure oil chamber (18) between the end face of the plunger (30) and the cylinder hole (7a),
A partition pipe (12) fixed to the outer peripheral surface of the upper part (9) of the inner cylinder (7) is provided on the outer periphery of the inner cylinder (7), and the remaining outer peripheral surface of the inner cylinder (7) and the partition pipe (12 ) Is formed between the outer peripheral surface of the partition pipe (12) and the inner peripheral surface of the casing (2). A horizontal hole (11) communicating with the cylinder hole (7a) is provided in the middle portion (8) of the inner cylinder (7), and is located above the communication hole (33) provided in the plunger (30). The middle part of the plunger (30) is reduced in diameter, a space (17) is formed between the middle part and the inner cylinder (7), and the clearances (14, 15) are connected to the plunger (30). A second clearance (15) formed between the upper part (9) of the inner cylinder (7), the plunger (30) and the inner cylinder (7) Is formed between the middle portion (8) and bottom (10), made from a first clearance (14) 2 divided in between the space (17),
When the plunger (30) is displaced in the direction of retreating from the inner cylinder (7), the oil passage (13), the lateral hole (11), the space (17), the communication hole (33), and the communication Oil flows from the low pressure oil chamber (19) to the high pressure oil chamber (18) through the check valve (35) for opening and closing the hole (33),
On the other hand, when the plunger (30) is displaced in the direction of entering the inner cylinder (7), the high pressure oil passes through the first clearance (14), the lateral hole (11), and the oil passage (13) in this order. A hydraulic auto tensioner characterized in that oil leaks from the chamber (18) to the low-pressure oil chamber (19).

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