JP4711900B2 - Tensioner unit - Google Patents

Description

  The present invention relates to a tensioner unit that generates a damping force by expanding and contracting with a load transmitted from an endless transmission member to a rotating body in order to absorb fluctuations in tension of the endless transmission member wound around the rotating body.

  A tensioner unit is connected to the middle part of a swinging arm that pivotally supports a tensioner pulley that applies tension to the endless belt, and a spring that urges the tensioner pulley in a direction to contact the endless belt inside the tensioner unit. Patent Document 1 listed below discloses a housing that contains a fluid pressure type damping means that applies a damping force to the swing of the swing arm.

In the conventional tensioner unit, a pair of check valves having different valve opening directions are provided in a partition wall provided in the cylinder, and the difference in the cross-sectional area of the throttle passages connected to the pair of check valves that open according to the advancement and retraction of the piston is made. By setting it, the damping force when the tensioner unit contracts is increased, and the damping force when extended is reduced.
Japanese Utility Model Publication No. 61-43000

  By the way, although what was described in the said patent document 1 provided a pair of check valve in the partition wall of the cylinder of a tensioner unit, if a pair of check valve was provided in the piston slidably fitted to a cylinder, the above-mentioned The axial dimension of the cylinder can be reduced by eliminating the partition. At this time, when a check valve having a structure in which a check ball is accommodated in a recess formed in the piston is employed and the space between the inner peripheral surface of the cylinder is sealed with a seal member supported by an annular groove formed on the outer peripheral surface of the piston, In order to avoid interference between the recess and the annular groove, the outer diameter of the piston increases, which may increase the size of the tensioner unit.

  The present invention has been made in view of the above circumstances, and an object thereof is to reduce the outer diameter of a piston that is slidably fitted to a cylinder of an auto tensioner.

  In order to achieve the above object, according to the first aspect of the present invention, the load transmitted from the endless transmission member to the rotating body is absorbed in order to absorb the fluctuation in tension of the endless transmission member wound around the rotating body. In the tensioner unit that expands and contracts to generate damping force, it is formed on both sides of the cylinder, the piston that slidably fits in the cylinder and moves according to the tension fluctuation of the endless transmission member, and the piston in the cylinder First and second fluid chambers, a seal member that fits in an annular groove formed on the outer periphery of the piston, and a first member that is provided on the piston and allows only movement of fluid from the second fluid chamber to the first fluid chamber. 1 check valve and a second check valve provided on the piston and allowing only movement of the fluid from the first fluid chamber to the second fluid chamber. The first check valve is on the first fluid chamber side of the piston. Open The first concave portion, the first fluid passage connected in series to the first concave portion and opened to the second fluid chamber, and the first check ball accommodated in the first concave portion are configured to be first in the radial direction of the piston. The outer end of the recess is located outside the outer end of the first fluid passage, and the second check valve is connected in series to the second recess opening to the second fluid chamber side of the piston and the second recess. The second fluid passage is open to the first fluid chamber, and the second check ball is housed in the second recess. The outer end of the second recess is outside the outer end of the second fluid passage in the radial direction of the piston. A tensioner unit is proposed in which the annular groove is disposed between the first and second recesses in the axial direction of the piston.

  The endless belt 11 of the embodiment corresponds to the endless transmission member of the present invention, and the tensioner pulley 16 of the embodiment corresponds to the rotating body of the present invention.

  According to the configuration of the first aspect, the first valve opening direction is different from the piston that is slidably fitted to the cylinder of the tensioner unit that expands and contracts by the load transmitted from the endless transmission member to the rotating body to generate the damping force. When the second check valve is provided, the first and second recesses for storing the first and second check balls of the first and second check valves are shifted in the axial direction of the piston and arranged on the outer periphery of the piston. Since the annular groove formed to support the seal member is disposed between the first and second recesses in the axial direction of the piston, the first and second recesses and the annular groove are disposed on the same cross section of the piston. Compared to the case, the outer diameter of the piston can be reduced to reduce the size of the tensioner unit.

  Hereinafter, embodiments of the present invention will be described 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 an enlarged view of a tensioner unit (when contracted), and FIG. 3 corresponds to FIG. It is action explanatory drawing (at the time of expansion | extension).

  An auto tensioner for preventing slip by applying tension to an endless belt 11 that transmits a driving force of a crankshaft of an automobile engine to an auxiliary machine is pivotally supported on a support shaft 13 provided on an engine block 12. The bell crank-shaped swing arm 14 is provided. The endless belt 11 is wound around a tensioner pulley 16 rotatably supported at one end of a swing arm 14 via a pulley shaft 15, and a tensioner unit is provided between the other end of the swing arm 14 and the engine block 12. 32 is provided.

  The tensioner unit 32 includes a first connecting portion 34 connected to the other end of the swing arm 14 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.

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

  In FIG. 1, when the tension of the endless belt 11 increases, the swing arm 14 swings clockwise around the support shaft 13, 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. 2, 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 other hand, when the tension of the endless belt 11 decreases, the swinging arm 14 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. 3, 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.

  Next, a second embodiment of the present invention will be described based on FIG. 4 and FIG. 4 and 5 correspond to FIGS. 2 and 3 of the first embodiment, respectively.

  In the first embodiment described above, the cross-sectional areas of the first and third fluid passages 56 and 62 of the first to fourth check valves 51 to 54 and the flow of the second and fourth fluid passages 59 and 65 are described. By making the road cross-sectional area different, there is a difference in the damping force at the time of contraction and extension of the tensioner unit 32. In the second embodiment, the first to fourth check valves 51 to 54 are different. A difference is given to the damping force by making the flow path cross-sectional areas of the first to fourth recesses 55, 58, 61, 64 different.

  That is, the diameters of the first and third recesses 55 and 61 of the first and third check valves 51 and 53 that open when the tensioner unit 32 contracts are set small, and the second and second check valves 51 and 53 that open when the tensioner unit 32 extends. By setting the diameters of the second and fourth recesses 58 and 64 of the fourth check valves 52 and 54 to be large, the first to fourth recesses 55, 58, 61 and 64 and the same diameter held therein are set. The cross-sectional areas of the flow paths are made different by changing the sizes of the gaps between the first to fourth check balls 57, 60, 63 and 66.

  Also in the second embodiment, the first and second recesses 55 and 58 are arranged to be shifted in the axial direction of the piston 41, and the annular groove 41 a that supports the seal member 40 on the outer periphery of the piston 41 is provided in the axial direction of the piston 41. Thus, the outer diameter of the piston 41 can be minimized, and the same effect as that of the first embodiment can be achieved. it can.

  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 tensioner pulley 20 and the endless belt 11, and may be a sprocket and an endless chain.

  In the embodiment, the tensioner unit 32 includes the valve block 45 provided with the third and fourth check valves 53 and 54, but the valve block 45 may be omitted.

Front view of the auto tensioner according to the first embodiment Enlarged view of tensioner unit (when retracted) Action explanatory diagram corresponding to FIG. 2 (when extended) Enlarged view of tensioner unit according to the second embodiment (when contracted) Action explanatory diagram corresponding to FIG. 4 (during extension)

Explanation of symbols

11 Endless belt (endless transmission member)
16 Tensioner pulley (Rotating body)
39 cylinder 40 sealing member 41 piston 41a annular groove 46 first fluid chamber 47 second fluid chamber 51 first check valve 52 second check valve 55 first recess 56 first fluid passage 57 first check ball 58 second recess 59 first 2 fluid passage 60 second check ball

Claims (1)

In order to absorb fluctuations in tension of the endless transmission member (11) wound around the rotating body (16), it is expanded and contracted by a load transmitted from the endless transmission member (11) to the rotating body (16) to generate a damping force. In the tensioner unit,
A cylinder (39);
A piston (41) that is slidably fitted to the cylinder (39) and moves in accordance with a change in tension of the endless transmission member (11);
First and second fluid chambers (46, 47) formed on both sides sandwiching the piston (41) in the cylinder (39);
A seal member (40) fitted in an annular groove (41a) formed on the outer periphery of the piston (41);
A first check valve (51) provided on the piston (41) and allowing only movement of fluid from the second fluid chamber (47) to the first fluid chamber (46);
A second check valve (52) provided on the piston (41) and allowing only movement of fluid from the first fluid chamber (46) to the second fluid chamber (47);
With
The first check valve (51) is connected in series to the first recess (55) that opens to the first fluid chamber side (46) of the piston (41), and to the first recess (55). The first fluid passage (56) opened in (47) and the first check ball (57) housed in the first recess (55), and the first recess (55 in the radial direction of the piston (41). ) At the outer end of the first fluid passage (56) outside the outer end,
The second check valve (52) is connected in series to the second recess (58) that opens to the second fluid chamber side (47) of the piston (41) and the second recess (58). The second fluid passageway (59) opened in (46) and the second check ball (60) housed in the second recessed portion (58), and the second recessed portion (58 in the radial direction of the piston (41). ) At the outer end of the second fluid passage (59) outside the outer end,
A tensioner unit characterized in that the annular groove (41a) is disposed between the first and second recesses (55, 58) in the axial direction of the piston (41).

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