JP2008014382A - Automatic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cool the tensioner unit of an automatic tensioner by a simple structure. <P>SOLUTION: In the automatic tensioner, even if a friction member 15 for damping a load transmitted from an endless belt 11 to a coiled spring 17 is heated when a tension is applied to the endless belt 11 by biasing a tension pulley 20 around which the endless belt 11 is wound, a fan 20c installed on the tension pulley 20 cools the friction member 15 by guiding the generated cool air toward the tension unit 32 by an air guide member 23. Since the fan 20c is rotated while the tension pulley 20 is rotated, a special drive source for driving the fan 20c is eliminated, and the number of parts is reduced, and the structure is simplified. Since the air guide member 23 is supported on a swing arm 16 swingably supporting the tension pulley 20, the relation of the positions of the tension pulley 20 and the air guide member 23 is kept unchanged even if the tension pulley 20 is swung when the swing arm 16 is swung. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a rotating body on which an endless transmission member is wound, a swing arm that supports the rotating body and can swing in a direction approaching and separating from the endless transmission member, and applies tension to the endless transmission member. The present invention relates to an auto tensioner that includes a tensioner unit that urges a swing arm in a direction and attenuates a load transmitted from an endless transmission member to the swing arm.

  The base end of the swing arm that pivotally supports the tensioner pulley that applies tension to the endless belt is pivotally supported by the support shaft of the tensioner unit, and the swing arm is attached to the support shaft in one direction with a spring. The tensioner pulley is biased toward the endless belt, and the behavior of the swing arm is stabilized by a damping means in which a synthetic resin friction material is disposed between the support shaft and the base end of the swing arm. Is known from Patent Document 1 below.

A tensioner unit is connected to the middle of the swing arm that pivotally supports the end of the tensioner pulley that applies tension to the endless belt, and the swing arm is urged in the tensioner unit so that the pulley contacts the endless belt. Japanese Patent Application Laid-Open No. 2004-151867 discloses a spring that houses a spring that performs a hydraulic pressure damping means that applies a damping force to the expansion and contraction of the cylinder accompanying the swing of the swing arm.
Japanese Patent Laid-Open No. 9-42392 Japanese translation of PCT publication 2-500210

  By the way, as described in the above-mentioned Patent Document 1, when the swing arm swings around the support shaft, frictional heat is generated in a process in which the friction material of the tensioner unit slides against the swing arm and generates a damping force. Further, in the above-mentioned Patent Document 2, when the swing arm swings, the frictional heat is generated in the process in which the fluid of the tensioner unit passes through the orifice and generates the damping force. However, there is a problem that the fluid is worn out or the fluid is deteriorated at an early stage. Depending on the installation location of the auto tensioner, the temperature of the tensioner unit may rise due to radiant heat from the exhaust system of the engine or the radiator, and it is necessary to actively cool the tensioner unit by some means.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to allow a tensioner unit of an auto tensioner to be cooled with a simple structure.

  In order to achieve the above object, according to the first aspect of the present invention, the rotating body on which the endless transmission member is wound and the rotating body that supports the rotating body and moves toward and away from the endless transmission member are supported. An automatic tensioner comprising: a movable swing arm; and a tensioner unit that urges the swing arm in a direction to apply tension to the endless transmission member and attenuates a load transmitted from the endless transmission member to the swing arm. There is proposed an auto tensioner comprising: a fan provided on the rotating body; and an air guide member for guiding the cooling air generated by the fan toward the tensioner unit.

  According to the invention described in claim 2, in addition to the configuration of claim 1, an auto tensioner is proposed in which the air guide member is supported by the swing arm.

  According to the invention described in claim 3, in addition to the configuration of claim 1 or 2, the cooling air generated by the fan is guided to the swing arm interposed between the fan and the air guide member. There is proposed an auto tensioner including an air guide port leading to a wind member.

  According to the configuration of the first aspect, when the tension arm unit urges the swing arm that supports the rotating body around which the endless transmission member is wound to apply tension to the endless transmission member, the endless transmission member is swung from the endless transmission member. Even if the tensioner unit that attenuates the load transmitted to the moving arm generates heat, the tensioner unit can be cooled by guiding the cooling air generated by the fan provided on the rotating body with the air guide member. In addition, since the fan automatically rotates with the rotation of the rotating body, a special drive source for driving the fan is not required, and the number of parts can be reduced and the structure can be simplified.

  According to the second aspect of the present invention, since the wind guide member is supported by the swing arm that supports the rotating body, the positional relationship between the rotary body and the wind guide member is maintained even if the rotary body swings together with the swing arm. There is no change. Therefore, it is not necessary to enlarge the air guide member so as to cover the swinging range of the rotating body, and the air guide member can be downsized.

  According to the third aspect of the present invention, the cooling air generated by the fan is guided to the air guide member by providing the air guide port in the swing arm interposed between the fan and the air guide member. It is possible to prevent a part of the wind from being blocked by the swing arm and not being supplied to the air guide member.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 3 show a first embodiment of the present invention. FIG. 1 is a front view of an auto tensioner, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. FIG.

  An auto tensioner for preventing slip by applying tension to an endless belt 11 that transmits the driving force of a crankshaft of an automobile engine to an auxiliary machine has a mounting flange 13a fixed to the engine block 12 with bolts 14 and 14. A tensioner unit 13 is provided. A cylindrical friction material 15 is fitted to the outer periphery of the support shaft 13b of the tensioner unit 13 so as to be relatively rotatable, and a cylindrical portion 16a at the base end of the swing arm 16 is fitted to the outer periphery of the friction material 15 so as to be relatively rotatable. Match. The swing arm 16 is urged in one direction with respect to the tensioner unit 13 by a torsion coil spring 17 disposed along the outer periphery of the cylindrical portion 16a. The outside of the torsion coil spring 17 is covered with a dust-proof cover 13 c formed integrally with the tensioner unit 13 and a dust-proof cover 16 b formed integrally with the swing arm 16.

  A plate-like arm main body 16c extends in the radial direction from the cylindrical portion 16a of the swing arm 16, and both side edges of the arm main body 16c are reinforced by plate-like ribs 16d and 16d. A tensioner pulley 20 is rotatably supported via a ball bearing 19 by a boss portion 16e formed integrally with the tip of the arm body 16c, and is prevented from coming off by a washer 21 and a bolt 22. The tensioner pulley 20 includes an inner ring 20a supported by the ball bearing 19, an outer ring 20b that supports the endless belt 11, and an axial-flow fan 20c that connects the inner ring 20a and the outer ring 20b.

  The air guide member 23 provided on the opposite side of the swinger arm 16 from the tensioner pulley 20 includes a first portion 23a formed in a hemisphere having the same diameter as the tensioner pulley 20, and the swing arm 16 from the first portion 23a. And a cylindrical second portion 23b extending toward the tensioner unit 13 along the arm main body 16c. A cooling air outlet 23c opens at the tip of the second portion 23b.

  Although the circular opening of the hemispherical first portion 23a of the air guide member 22 faces the fan 20c of the tensioner pulley 20, a part of the circular opening is interposed between the swing arm 16 and the fan 20c. Is blocked by the arm main body 16c. An air guide port 16g through which cooling air passes is formed at a portion where the arm main body 16c of the swing arm 16 blocks the opening of the first portion 23a of the air guide member 22.

  Next, the operation of the first embodiment having the above configuration will be described.

  The swing arm 16 of the auto tensioner is biased in the direction of arrow A in FIG. 1 by the elastic force of the torsion coil spring 17, and the tensioner pulley 20 is pressed against the endless belt 11 by the biasing force. A predetermined tension is applied to 11. When the tension of the endless belt 11 fluctuates due to load fluctuations of the auxiliary machine driven by the endless belt 11 or fluctuations in the engine speed, the swing arm 16 swings to absorb the tension variation. That is, when the tension of the endless belt 11 increases, the swing arm 16 swings in the direction of arrow A 'while compressing the torsion coil spring 17, and when the tension of the endless belt 11 decreases, the swing arm 16 twists. It swings in the direction of arrow A by the elastic force of the coil spring 17. When the swing arm 16 reciprocally swings in this way, the friction material 15 slides against the outer peripheral surface of the support shaft 13b of the tensioner unit 13 and the inner peripheral surface of the cylindrical portion 16a of the swing arm 16, The swinging arm 16 is prevented from rampage by the damping force generated by the friction, and the tension of the endless belt 11 can be stabilized.

  Now, when the swing arm 16 reciprocally swings and the friction material 15 generates frictional heat, the temperature rises. Therefore, cooling is necessary to prevent abnormal wear of the friction material 15 and ensure durability.

  When the tensioner pulley 20 is rotated by the endless belt 11, the cooling air generated by the fan 20c provided on the tensioner pulley 20 is cooled from the hemispherical first portion 23a of the air guide member 23 through the cylindrical second portion 23b. By ejecting toward the tensioner unit 13 from the wind outlet 23c, the tensioner unit 13 accommodated therein is cooled.

  As described above, since the fan 20c is provided in the tensioner pulley 20 rotated by the endless belt 11, a special drive source for driving the fan 20c becomes unnecessary, and the number of parts can be reduced and the structure can be simplified. Moreover, since the air guide member 23 is provided on the swing arm 16 that supports the tensioner pulley 20, even if the swing arm 16 swings and the position of the tensioner pulley 20 changes, the tension pulley 20 and the air guide member 23 The positional relationship of is not changed. Therefore, it is not necessary to enlarge the air guide member 23 so as to cover the swing range of the tensioner pulley 20, and the air guide member 23 can be downsized.

  Further, since the arm main body 16c of the swing arm 16 partially blocks between the fan 20c and the opening of the air guide member 23, the cooling air generated by the fan 20c may not be sufficiently guided to the air guide member 23. However, by forming the air guide port 16g in the arm body 16c, the cooling air generated by the fan 20c can be guided to the air guide member 23 without waste, and the cooling effect of the tensioner unit 13 can be enhanced.

  4 to 8 show a second embodiment of the present invention. FIG. 4 is a front view of the auto tensioner, FIG. 5 is a sectional view taken along line 5-5 in FIG. 4, and FIG. FIG. 7 is a sectional view of the tensioner unit (when contracted), and FIG. 8 is a sectional view of the tensioner unit (when extended).

  In the second embodiment, the tensioner pulley 20 is freely rotatable via a ball bearing 19, a washer 21, and a bolt 22 on a boss portion 16 e formed at one end of a swing arm 16 pivotally supported by a support shaft 31. The other end of the swing arm 16 is connected to the engine block 12 via the tensioner unit 32.

  The tensioner unit 32 includes a first connecting portion 34 connected to the other end of the swing arm 16 via a fulcrum pin 33, and a second connecting portion 36 connected to the engine block 12 via a fulcrum pin 35. A compression coil spring 37 is disposed between the first and second connecting portions 34 and 36.

  A cylinder 39 is formed inside a cylindrical housing 38 provided integrally with the first connecting portion 34, and is provided integrally with a piston 41 slidably fitted to the cylinder 39 via a seal member 40. The piston rod 42 is connected to the second connecting portion 36 through the seal member 44 provided on the end plate 43 that closes the upper end of the cylinder 39. The lower end of the cylinder 39 is closed by a valve block 45, a first fluid chamber 46 is formed in the upper part of the piston 41, a second fluid chamber 47 is formed between the piston 41 and the valve block 45, and the lower part of the valve block 45 A third fluid chamber 48 is formed. The third fluid chamber 48 communicates with a reservoir 49 formed between the housing 38 and the cylinder 39, and an air chamber 50 is formed above the reservoir 49.

  The piston 41 allows the fluid flow from the second fluid chamber 47 to the first fluid chamber 46 and prevents the fluid from flowing in the opposite direction, and the first check valve 51 from the second fluid chamber 47 to the first fluid chamber 47. A second check valve 52 that prevents the fluid from flowing into the first fluid chamber 46 and allows the fluid to flow in the opposite direction is provided. The valve block 45 also includes a third check valve 53 that allows fluid to flow from the second fluid chamber 47 to the third fluid chamber 48 and prevents fluid flow in the opposite direction, and the second fluid chamber 47. A fourth check valve 54 is provided that prevents the fluid from flowing into the third fluid chamber 48 and allows the fluid to flow in the opposite direction.

  The first check valve 51 includes a first recess 55 that opens to the first fluid chamber 46, a first fluid passage 56 that communicates with the bottom of the first recess 55 and opens to the second fluid chamber 47, and a first recess 55. The first check ball 57 is accommodated. The second check valve 52 includes a second recess 58 that opens to the second fluid chamber 47, a second fluid passage 59 that communicates with the bottom of the second recess 58 and opens to the third fluid chamber 48, and a second recess 58. It is comprised with the 2nd check ball 60 accommodated. The first fluid passage 56 is formed narrower than the second fluid passage 59.

  The third check valve 53 includes a third recess 61 that opens to the third fluid chamber 48, a third fluid passage 62 that communicates with the bottom of the third recess 61 and opens to the second fluid chamber 47, and the third recess 61. The third check ball 63 is accommodated. The fourth check valve 54 includes a fourth recess 64 that opens to the second fluid chamber 47, a fourth fluid passage 65 that communicates with the bottom of the fourth recess 64 and opens to the third fluid chamber 48, and a fourth recess 64. The fourth check ball 66 is accommodated. The third fluid passage 62 is formed narrower than the fourth fluid passage 65.

  In the radial direction of the piston 41, the outer ends of the first to fourth recesses 55, 58, 61, 64 of the first to fourth check valves 51 to 54 are first to fourth fluid passages 56, 59, 62, 65, respectively. It is located outside of the outer edge. An annular groove 41 a formed on the outer peripheral surface of the piston 41 to support the seal member 40 is between the first and second recesses 55, 58 of the first and second check valves 51, 52 in the axial direction of the piston 41. Is located.

  As described above, the first and second check valves 51 and 52 and the third and fourth check valves 53 and 54 are arranged vertically symmetrically with the second fluid chamber 47 interposed therebetween.

  A tensioner pulley 20 is rotatably supported at the tip of an arm main body 16c extending from a support portion 16f of the swing arm 16, and a centrifugal fan 20e is provided on a disc portion 20d fixed to one end face of the tensioner pulley 20. It is done.

  A wind guide member 72 fixed to the support portion 16f of the swing arm 16 by two bolts 71, 71 cooperates with the disk portion 20d to surround the outer periphery of the fan 20e, and a first portion 72a. The second portion 72b extends in a tangential direction from the first portion 72a and faces the tensioner unit 32, and a cooling air outlet 72c opens at the tip of the second portion 72b.

  Next, the operation of the second embodiment having the above configuration will be described.

  In FIG. 4, when the tension of the endless belt 11 increases, the swing arm 16 swings clockwise around the support shaft 31, and the first connection portion 34 of the tensioner unit 32 compresses the compression coil spring 37 while performing the second connection. It moves in a direction approaching the part 36. As a result, as shown in FIG. 7, the piston 41 is lowered so as to be pushed into the cylinder 39 and the volume of the second fluid chamber 47 is reduced, so that the first and third check valves 51 and 53 are opened. Then, the second and fourth check valves 52 and 54 are closed, and the fluid in the second fluid chamber 47 passes through the narrow first and third fluid passages 56 and 62 of the first and third check valves 51 and 53. Flow into the first and third fluid chambers 46 and 48. Thus, when the tension of the endless belt 11 increases and the tensioner unit 32 contracts, a large damping force is generated by the fluid passing through the narrower first and third fluid passages 56 and 62. When the tensioner unit 32 is contracted, the volume of the air chamber 50 is reduced by the volume of the piston rod 42 entering the first fluid chamber 46, thereby preventing the piston 41 from being locked.

  On the contrary, when the tension of the endless belt 11 decreases, the swinging arm 16 swings counterclockwise around the support shaft 31 by the elastic force of the compression coil spring 37, and the first connecting portion 34 of the tensioner unit 32 is second connected. It moves in a direction away from the portion 36. As a result, as shown in FIG. 8, the piston 41 is lifted in the direction of being pulled out from the cylinder 39 and the volume of the second fluid chamber 47 is increased, so that the first and third check valves 51 and 53 are closed. The second and fourth check valves 52 and 54 are opened, the fluid in the first fluid chamber 46 passes through the thick second fluid passage 59 of the second check valve 52 and flows into the second fluid chamber 47, and A small damping force is generated when the fluid in the three fluid chambers 48 passes through the thick fourth fluid passage 65 of the fourth check valve 54 and flows into the second fluid chamber 47. When the tensioner unit 32 is extended, the volume of the air chamber 50 is increased by the volume of the piston rod 42 that retreats from the first fluid chamber 46, thereby preventing the piston 41 from being locked.

  As described above, when the tension of the endless belt 11 increases, the tensioner unit 32 generates a large damping force and slowly contracts. When the tension of the endless belt 11 decreases, the tensioner unit 32 generates a small damping force and quickly. By elongating, the ramp of the tensioner pulley 20 can be prevented and the behavior of the endless belt 11 can be stabilized.

  Now, the piston 41 is provided with first and second check valves 51 and 52 and a seal member 40. In order to minimize the outer diameter of the piston 41 and reduce the size of the tensioner unit 32, these are used. It is necessary to lay out so as not to interfere.

  In the present embodiment, the first and second recesses 55 and 58 having a diameter larger than those of the first and second fluid passages 56 and 59 are arranged shifted in the axial direction of the piston 41, and the seal member 40 is disposed on the outer periphery of the piston 41. Since the supporting annular groove 41a is formed at a position sandwiched between the first and second recesses 55 and 58 in the axial direction of the piston 41, the outer diameter of the piston 41 can be minimized. If the first and second recesses 55 and 58 and the annular groove 41a are arranged on the same cross section of the piston 41, the outer diameter of the piston 41 becomes larger than that of the present embodiment.

  By the way, when the fluid passes through the first to fourth fluid passages 56, 59, 62, and 65 as the tensioner unit 32 expands and contracts, the fluid may generate heat due to shearing force and deteriorate early. However, according to the present embodiment, when the tensioner pulley 20 is rotated by the endless belt 11, the cooling air generated by the fan 20 e provided on the tensioner pulley 20 is transmitted from the hemispherical first portion 72 a of the air guide member 72. By ejecting from the cooling air outlet 72c toward the tensioner unit 32 through the cylindrical second portion 72b, the fluid can be cooled and the temperature rise can be suppressed.

  As in the first embodiment, the fan 20e is provided on the tensioner pulley 20 that is rotated by the endless belt 11, so that a special drive source for driving the fan 20e is not required, the number of parts is reduced, and the structure is simplified. Is possible. Moreover, since the air guide member 72 is provided on the swing arm 16 that supports the tensioner pulley 20, even if the swing arm 16 swings and the position of the tensioner pulley 20 changes, the tension pulley 20 and the air guide member 72 The positional relationship of is not changed. Therefore, it is not necessary to enlarge the air guide member 72 so as to cover the swing range of the tensioner pulley 20, and the air guide member 72 can be downsized.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the rotating body and the endless transmission member of the present invention are not limited to the pulley 20 and the endless belt 11, but may be a sprocket and an endless chain.

Front view of the auto tensioner according to the first embodiment 2-2 sectional view of FIG. 3-3 sectional view of FIG. Front view of the auto tensioner according to the second embodiment Sectional view along line 5-5 in FIG. 6-6 sectional view of FIG. Cross section of tensioner unit (when contracted) Cross section of tensioner unit (when extended)

Explanation of symbols

11 Endless belt (endless transmission member)
13 Tensioner unit 16 Oscillating arm 16g Air guide 20 Tensioner pulley (rotating body)
20c Fan 20e Fan 23 Air guide member 32 Tensioner unit 72 Air guide member

Claims (3)

A rotating body (20) around which an endless transmission member (11) is wound;
A swing arm (16) that supports the rotating body (20) and can swing in a direction approaching and separating from the endless transmission member (11);
A tensioner unit (13) that urges the swing arm (16) in a direction to apply tension to the endless transmission member (11) and attenuates a load transmitted from the endless transmission member (11) to the swing arm (16). , 32),
In an auto tensioner with
Fans (20c, 20e) provided on the rotating body (20) and air guide members (23, 72) for guiding the cooling air generated by the fans (20c, 20e) toward the tensioner unit (13, 32). An auto tensioner characterized by comprising.   The auto tensioner according to claim 1, characterized in that the air guide member (23, 72) is supported by the swing arm (16). The swing arm (16) interposed between the fan (20c) and the air guide member (23) is provided with an air guide port (16g) for guiding the cooling air generated by the fan (20c) to the air guide member (23). The auto tensioner according to claim 1 or 2, characterized by the above.

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